The present disclosure relates to a fuel injection valve that injects fuel.
A conventional fuel injection valve includes a fixed core that generates a magnetic attraction force upon energization of a coil, a movable core that is attracted and moved by the fixed core, and a valve body that is actuated by the moving movable core to open the valve such that fuel is jetted from a nozzle hole. In recent years, fuel pressure becomes high, and a valve closing force urging the valve body tends to increase. Hence, a large valve opening force is required in order to open the valve against the large valve closing force.
According to at least one embodiment of the present disclosure, a fuel injection valve includes: a valve body that opens and closes a nozzle hole for injecting a fuel; a fixed core that generates a magnetic attraction force upon energization of a coil; a movable core that is attracted and moved by the fixed core in a direction away from the nozzle hole, the movable core coming into contact with the valve body when the movable core is moved by a predetermined distance to cause the valve body to start a valve opening operation; a spring member that is elastically deformed by the valve opening operation of the valve body and exerts a valve closing elastic force that causes the valve body to perform a valve closing operation; and a valve closing force transmission member that is movable relative to the valve body and transmits the valve closing elastic force to the valve body by relatively moving toward the nozzle hole and contacting the valve body. The movable core includes a first core contact surface that contacts the valve body at the predetermined distance the movable core is moved in the direction away from the nozzle hole, and a second core contact surface that contacts the valve closing force transmission member when moving in the direction away from the nozzle hole. The movable core, the valve closing force transmission member and the valve body form a fuel storage chamber in which fuel is accumulated when the valve body closes the nozzle hole, the fuel storage chamber being surrounded by the movable core, the valve closing force transmission member and the valve body. The first core contact surface is located inside the fuel storage chamber. A portion of the valve closing force transmission member, which contacts the second core contact surface, separates an inside space of the fuel storage chamber from an outside space. The first core contact surface and the second core contact surface have a communication groove through which the inside space of the fuel storage chamber communicates with the outside space.
The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims.
A general fuel injection valve includes a fixed core that generates a magnetic attraction force upon energization of a coil, a movable core that is attracted and moved by the fixed core, and a valve body that is actuated by the moving movable core to open the valve such that fuel is jetted from a nozzle hole. In recent years, fuel pressure becomes high, and a valve closing force urging the valve body tends to increase. Hence, a large valve opening force is required in order to open the valve against the large valve closing force.
As a countermeasure against the above, a core boost structure may be proposed as a comparative example. That is, for the valve opening operation of the valve body, first, movement of the movable core is started in a state in which the movable core is not engaged with the valve body. And thereafter, when the movable core is moved by a predetermined distance, the movable core is brought into contact with the valve body to start the valve opening operation.
According to the core boost structure described above, since the movable core is not yet engaged with the valve body immediately after a start of energization, the movable core which is not subjected to a force of a fuel pressure can quickly raise a moving speed of the movable core by an initial small magnetomotive force. Then, since the movable core comes into contact with the valve body and starts the valve opening operation when the moving speed becomes sufficiently high, that is, when the movable core is moved by the predetermined distance, the valve opening operation can be performed by the aid of a collision force of the movable core in addition to a magnetic attraction force. Therefore, the valve opening operation of the valve body can be performed even when the fuel pressure is high. Further, magnetic attraction force required for opening the valve can be reduced.
However, in the core boost structure described above, the movable core moves in two stages: a movement from the start of the energization to the contact with the valve body; and a subsequent movement while keeping contact with the valve body. For that reason, variation in time period from the start of the energization to the start of the valve opening operation is directly linked to variation in amount of injected fuel in one valve opening operation. Further, not only such variation in time period from the start of energization to opening of the valve, but also variation in time period from an end of the energization to closure of the valve can be considered.
In contrast to the comparative example, according to a first aspect of the present disclosure, a fuel injection valve includes: a valve body that opens and closes a nozzle hole for injecting a fuel; a fixed core that generates a magnetic attraction force upon energization of a coil; a movable core that is attracted and moved by the fixed core in a direction away from the nozzle hole, the movable core coming into contact with the valve body when the movable core is moved by a predetermined distance to cause the valve body to start a valve opening operation; a spring member that is elastically deformed by the valve opening operation of the valve body and exerts a valve closing elastic force that causes the valve body to perform a valve closing operation; and a valve closing force transmission member that is movable relative to the valve body and transmits the valve closing elastic force to the valve body by relatively moving toward the nozzle hole and contacting the valve body. The movable core includes a first core contact surface that contacts the valve body at the predetermined distance the movable core is moved in the direction away from the nozzle hole, and a second core contact surface that contacts the valve closing force transmission member when moving in the direction away from the nozzle hole. The movable core, the valve closing force transmission member and the valve body form a fuel storage chamber in which fuel is accumulated when the valve body closes the nozzle hole, the fuel storage chamber being surrounded by the movable core, the valve closing force transmission member and the valve body. The first core contact surface is located inside the fuel storage chamber. A portion of the valve closing force transmission member, which contacts the second core contact surface, separates an inside space of the fuel storage chamber from an outside space. The first core contact surface and the second core contact surface have a communication groove through which the inside space of the fuel storage chamber communicates with the outside space.
In short, the fuel injection valve according to the first aspect has a core boost structure in which the movable core contacts a valve body at a point in time when the movable core moves by a predetermined distance in the direction away from the nozzle hole to open the valve. The fuel injection valve includes the valve closing force transmission member that contacts the valve body to transmit an elastic force to the valve body by moving relative to the valve body toward the nozzle hole. The first core contact surface and the second core contact surface of the movable core have the communication groove. The inside and the outside of the fuel storage chamber, surrounded by the movable core, the valve closing force transmission member, and the valve body, communicate with each other through the communication groove.
When the fuel existing in the fuel storage chamber is compressed as the movable core moves away from the nozzle hole, movement of the movable core is blocked, and therefore a moving speed of the movable core becomes low at the time of contacting the valve body at the predetermined movement distance. This results in reduction of the above-mentioned effect of the core boost structure, that is, the effect that the valve opening operation of the valve body can be performed even when fuel pressure is high while reducing the magnetic attraction force required to open the valve. In addition, since the movement of the movable core is obstructed, a variation in the valve opening timing of the valve body becomes large, and a variation in the fuel injection amount becomes large.
On the other hand, according to the first aspect described above, since the inside and the outside of the fuel storage chamber communicate with each other through the communication groove, when the movable core moves away from the nozzle hole, the fuel accumulated in the fuel storage chamber flows out to the outside through the communication groove. Therefore, the compression of the fuel accumulated in the fuel storage chamber is reduced, so that the movable core easily moves. For that reason, a reduction in the collision speed of the movable core can be prevented, so that the effect of reducing the magnetic attraction force by the core boost structure can be promoted. In addition, since the movable core easily moves, a variation in the valve opening timing of the valve body can be reduced, and consequently, a variation in the fuel injection amount can be reduced.
According to the first aspect, the communication groove is provided in the movable core, whereas in Patent Literature 1 described above, the communication groove is provided in a flange portion accommodation member. However, in the case where the communication groove is provided in the valve closing force transmission member in the above manner, the communication groove is gradually covered with the wall surface of the valve body as the movable core moves away from the nozzle hole. Thus, a passage cross-sectional area of the communication groove is gradually reduced, and a function of allowing the fuel to flow out to the outside of the fuel storage chamber is not sufficiently exhibited.
On the other hand, in the first aspect, since the communication groove is provided in the movable core, the passage cross-sectional area of the communication groove is maintained without any decrease even when the movable core contacts the valve body, as well as during a period in which the movable core moves by a predetermined distance away from the nozzle hole. For that reason, the function of allowing the fuel to flow out to the outside of the fuel storage chamber can be sufficiently exhibited, and a decrease in the collision speed force of the movable core can be sufficiently reduced.
According to a second aspect of the present disclosure, a fuel injection valve includes: a valve body that opens and closes a nozzle hole for injecting a fuel; a fixed core that generates a magnetic attraction force upon energization of a coil; a movable core that is attracted and moved by the fixed core in a direction away from the nozzle hole, the movable core coming into contact with the valve body when the movable core is moved by a predetermined distance to cause the valve body to start a valve opening operation; a spring member that is elastically deformed by the valve opening operation of the valve body and exerts a valve closing elastic force that causes the valve body to perform a valve closing operation; and a valve closing force transmission member that is movable relative to the valve body and transmits the valve closing elastic force to the valve body by relatively moving toward the nozzle hole and contacting the valve body. The movable core, the valve closing force transmission member and the valve body form a fuel storage chamber in which fuel is accumulated when the valve body closes the nozzle hole, the fuel storage chamber being surrounded by the movable core, the valve closing force transmission member and the valve body. The valve body has an internal passage inside the valve body, through which the fuel flows to be supplied to the nozzle hole. The valve body has a communication hole through which the fuel storage chamber communicates with the internal passage.
In short, the fuel injection valve according to the second aspect has a core boost structure in which the movable core contacts the valve body at a point in time when the movable core moves by the predetermined distance away from the nozzle holes to open the valve. In the valve closing operation, the valve closing force transmission member moves relative to the valve body toward the nozzle hole to contact the valve body and transmit an elastic force to the valve body. The valve body has a communication hole through which the internal passage provided inside the valve body communicates with the fuel storage chamber.
As a result, when the movable core moves away from the nozzle hole, the fuel accumulated in the fuel storage chamber flows out to the outside through the communication hole. Therefore, the compression of the fuel accumulated in the fuel storage chamber is reduced, so that the movable core easily moves. As a result, similar to the first embodiment, since a decrease in the collision speed of the movable core can be reduced, the effect of reducing the magnetic attraction force by the core boost structure can be promoted. In addition, since the movable core easily moves, a variation in the valve opening timing of the valve body can be reduced, and consequently, a variation in the fuel injection amount can be reduced.
According to a third aspect of the present disclosure, a fuel injection valve includes: a valve body that opens and closes a nozzle hole for injecting a fuel; a fixed core that generates a magnetic attraction force upon energization of a coil; a movable core that is attracted and moved by the fixed core in a direction away from the nozzle hole, the movable core coming into contact with the valve body when the movable core is moved by a predetermined distance to cause the valve body to start a valve opening operation; a spring member that is elastically deformed by the valve opening operation of the valve body and exerts a valve closing elastic force that causes the valve body to perform a valve closing operation; and a valve closing force transmission member that is slidable relative to the valve body and transmits the valve closing elastic force to the valve body by sliding toward the nozzle hole and contacting the valve body. The movable core, the valve closing force transmission member, and the valve body form a fuel storage chamber in which fuel is accumulated when the valve body closes the nozzle hole, the fuel storage chamber being surrounded by the movable core, the valve closing force transmission member and the valve body. The valve body has a valve body-side sliding surface on which the valve closing force transmission member slides. The valve closing force transmission member has a transmission member-side sliding surface on which the valve body slides. The valve body-side sliding surface or the transmission member-side sliding surface has a sliding surface communication groove through which an inside space of the fuel storage chamber communicates with an outside space.
In short, the fuel injection valve according to the third aspect has a core boost structure in which the movable core contacts the valve body at a point in time when the movable core moves by the predetermined distance away from the nozzle holes to open the valve. In the valve closing operation, the valve closing force transmission member moves relative to the valve body toward the nozzle hole to contact the valve body and transmit an elastic force to the valve body. The sliding surface communication groove, through which the inside and the outside of the fuel storage chamber communicate with each other, is provided on the valve body-side sliding surface on which the valve closing force transmission member slides, or provided on the transmission member-side sliding surface of the valve closing force transmission member on which the valve body slides.
As a result, when the movable core moves away from the nozzle hole, the fuel accumulated in the fuel storage chamber flows out through the sliding surface communication groove. Therefore, the compression of the fuel accumulated in the fuel storage chamber is reduced, so that the movable core easily moves. As a result, similar to the first embodiment, since a decrease in the collision speed of the movable core can be reduced, the effect of reducing the magnetic attraction force by the core boost structure can be promoted. In addition, since the movable core easily moves, a variation in the valve opening timing of the valve body can be reduced, and consequently, a variation in the fuel injection amount can be reduced.
Hereinafter, multiple embodiments for implementing the present disclosure will be described referring to drawings. In the respective embodiments, a part that corresponds to a matter described in a preceding embodiment may be assigned the same reference numeral, and redundant explanation for the part may be omitted.
When only a part of a configuration is described in an embodiment, another preceding embodiment may be applied to the other parts of the configuration. The parts may be combined even if it is not explicitly described that the parts can be combined. The embodiments may be partially combined even if it is not explicitly described that the embodiments can be combined, provided there is no harm in the combination.
A fuel injection valve 1 shown in
The fuel injection valve 1 includes a nozzle hole body 11, a main body 12, a fixed core 13, a non-magnetic member 14, a coil 17, a support member 18, a first spring member SP1, a second spring member SP2, a needle 20, a movable core 30, a sleeve 40, a cup 50, a guide member 60, and the like. The nozzle hole body 11, the main body 12, the fixed core 13, the support member 18, the needle 20, the movable core 30, the sleeve 40, the cup 50, and the guide member 60 are made of metal.
As shown in
The main body 12 and the non-magnetic member 14 are cylindrical in shape. A cylindrical end portion of the main body 12, which is closer to the nozzle holes 11a with respect to the main body 12 (on a nozzle hole side), is fixed to the nozzle hole body 11 by welding. A cylindrical end portion of the main body 12 on a side facing away from the nozzle holes 11a with respect to the main body 12 (on a side opposite to the nozzle holes), is fixed to a cylindrical end portion of the non-magnetic member 14 by welding. A cylindrical end portion of the non-magnetic member 14 on the side opposite to the nozzle hole is fixed to the fixed core 13 by welding.
A nut member 15 is fastened to a threaded portion 13N of the fixed core 13 in a state of being locked to a locking portion 12c of the main body 12. An axial force generated by the fastening generates a surface pressure pressing the nut member 15, the main body 12, the non-magnetic member 14, and the fixed core 13 against each other in a direction of the axis line C (in a vertical direction in
The main body 12 is made of a magnetic material such as stainless steel, and has a flow channel 12b for allowing the fuel to flow in the nozzle holes 11a inside. In the flow channel 12b, the needle 20 is accommodated so as to be movable in the direction of the axis line C. The main body 12 and the non-magnetic member 14 correspond to a “holder” having a movable chamber 12a filled with the fuel. A movable portion M (refer to
The flow channel 12b is shaped to communicate with a downstream side of the movable chamber 12a and extend in the direction of the axis line C. A center line of the flow channel 12b and the movable chamber 12a coincides with a cylindrical center line (axis line C) of the main body 12. A nozzle hole side portion of the needle 20 is slidably supported by an inner wall surface 11c of the nozzle hole body 11, and a portion of the needle 20 on a side opposite to the nozzle holes is slidably supported by an inner wall surface 51b of the cup 50 (refer to
The needle 20 corresponds to a “valve body” that opens and closes the nozzle holes 11a, and is made of a magnetic material such as stainless steel, and has a shape extending in the direction of the axis line C. The valve body-side seat 20s described above is formed on a downstream-side end face of the needle 20. When the needle 20 moves to the downstream side in the direction of the axis line C (valve closing operation), the valve body-side seat 20s is seated on the body-side seat 11s to close the flow channel 11b and the nozzle holes 11a. When the needle 20 moves to the upstream side in the direction of the axis line C (valve opening operation), the valve body-side seat 20s is separated from the body-side seat 11s to open the flow channel 11b and the nozzle holes 11a.
The needle 20 has an internal passage 20a and lateral holes 20b for allowing the fuel to flow through the nozzle holes 11a (refer to
As shown in
The cup 50 is slidably assembled to the contact portion 21, and an outer peripheral surface of the contact portion 21 slides with an inner peripheral surface of the cup 50. The movable core 30 is slidably assembled to the core sliding portion 22, and an outer peripheral surface of the core sliding portion 22 slides with an inner peripheral surface of the movable core 30. A sleeve 40 is press-fitted into the press-fit portion 23. The lateral holes 20b are provided in the outflow portion 24.
An outer diameter D1 of the contact portion 21 is set to be larger than an outer diameter D2 of the core sliding portion 22, the outer diameter D2 of the core sliding portion 22 is set to be larger than an outer diameter D3 of the press-fit portion 23, and the outer diameter D3 of the press-fit portion 23 is set to be larger than an outer diameter of the outflow portion 24. A connection part 22a between the core sliding portion 22 and the press-fit portion 23 and a connection portion 23a between the press-fit portion 23 and the outflow portion 24 are each formed in a tapered shape. A diameter of an inner peripheral surface 41a of the sleeve 40 in a state before press-fitting is set to be smaller than the outer diameter D3 of the press-fit portion 23, and press-fitting can be performed.
The outer diameters of the first large diameter portion 25 and the second large diameter portion 27 are larger than the outer diameters of the first small diameter portion 26 and the second small diameter portion 28. The weight reduction is achieved by having the first small diameter portion 26 and the second small diameter portion 28. The first large diameter portion 25 and the second large diameter portion 27 function as a support portion when the needle 20 is cut. The second small diameter portion 28 functions as an escape portion so that a cutting tool does not interfere with cutting of the nozzle hole-side support portion 29. The nozzle hole-side support portion 29 is slidably supported by the inner wall surface 11c of the nozzle hole body 11.
The cup 50 has a circular plate portion 52 having a circular plate shape and a cylindrical portion 51 having a cylindrical shape. The circular plate portion 52 has a through hole 52a penetrating in the direction of the axis line C. A surface of the circular plate portion 52 on a side opposite to the nozzle holes functions as a spring contact surface 52b that contacts the first spring member SP1. A surface of the circular plate portion 52 on a nozzle hole side functions as a valve closing force transmission contact surface 52c that contacts the needle 20 and transmits a first elastic force (a valve closing elastic force). The circular plate portion 52 corresponds to a “valve body transmission portion” that contacts the first spring member SP1 and the needle 20 to transmit the first elastic force to the needle 20. The cylindrical portion 51 has a cylindrical shape extending from an outer peripheral end of the circular plate portion 52 to the nozzle hole side. A nozzle hole-side end face of the cylindrical portion 51 functions as a core contact end face 51a that contacts the movable core 30. The inner wall surface 51b of the cylindrical portion 51 slides with the outer peripheral surface of the contact portion 21 of the needle 20.
The fixed core 13 is made of a magnetic material such as stainless steel, and has a flow channel 13a for allowing the fuel to flow through the nozzle holes 11a. The flow channel 13a communicates with the internal passage 20a provided inside the needle 20 (refer to
The support member 18 has a cylindrical shape and is press-fitted into an inner wall surface of the fixed core 13. The first spring member SP1 is a coiled spring disposed on the downstream side of the support member 18, and elastically deforms in the direction of the axis line C. An upstream-side end face of the first spring member SP1 is supported by the support member 18, and a downstream-side end face of the first spring member SP1 is supported by the cup 50. A force generated by the elastic deformation of the first spring member SP1 (a first elastic force) urges the cup 50 toward the downstream side. The degree of press-fitting of the support member 18 in the direction of the axis line C is adjusted, to thereby adjust a magnitude of the elastic force for urging the cup 50 (first set load).
As shown in
In short, the guide member 60 has a guide function of sliding the outer peripheral surface of the cup 50 moving in the direction of the axis line C, and a stopper function of contacting the movable core 30 moving in the direction of the axis line C and restricting the movable core 30 from moving to the side opposite to the nozzle holes. In other words, the guide member 60 corresponds to a “stopper member” that contacts the movable core 30 and restricts the movable core 30 from moving away from the nozzle holes 11a.
A resin member 16 is provided on an outer peripheral surface of the fixed core 13. The resin member 16 has a connector housing 16a, and a terminal 16b is accommodated in the connector housing 16a. The terminal 16b is electrically connected to the coil 17. An external connector (not shown) is connected to the connector housing 16a, and an electric power is supplied to the coil 17 through the terminal 16b. The coil 17 is wound around a bobbin 17a having an electrical insulation property to form a cylindrical shape, and is disposed on a radially outer side of the fixed core 13, the non-magnetic member 14, and the movable core 30. The fixed core 13, the nut member 15, the main body 12, and the movable core 30 form a magnetic circuit for flowing a magnetic flux generated accompanying a power supply (energization) to the coil 17 (refer to a dotted arrow in
As shown in
The needle 20 is inserted into a cylindrical inner portion of the inner core 32. The inner core 32 is assembled to the needle 20 so as to be slidable relative to the needle 20 in the axis line C. A gap (inner gap) between an inner peripheral surface of the inner core 32 and an outer peripheral surface of the needle 20 is set to be smaller than a gap (outer gap) between an outer peripheral surface of the outer core 31 and an inner peripheral surface of the main body 12. Those gaps are set so that the outer core 31 does not contact the main body 12 while allowing the inner core 32 to contact the needle 20.
The inner core 32 contacts the guide member 60 as a stopper member, the cup 50, and the needle 20. For that reason, a material having a higher hardness than that of the outer core 31 is used for the inner core 32. The outer core 31 has a movable core facing surface 31c facing the fixed core 13, and a gap is provided between the movable core facing surface 31c and the fixed core 13. Therefore, in a state in which a magnetic flux flows by energizing the coil 17 as described above, a magnetic attraction force attracted to the fixed core 13 acts on the outer core 31 by provision of the gap.
The sleeve 40 corresponds to a “fixed member” that is press-fitted into the needle 20. The sleeve 40 is made of a cylindrical metal having a through hole 40a (refer to
The second spring member SP2 is a coiled spring disposed on the side opposite to the nozzle holes with respect to the support portion 43, and is elastically deformed in the direction of the axis line C. An end face of the second spring member SP2 on the side opposite to the nozzle hole is supported by the movable core 30, specifically, the outer core 31. A nozzle hole-side end face of the second spring member SP2 is supported by the support portion 43. The force generated by the elastic deformation of the second spring member SP2 (the second elastic force) urges the outer core 31 toward the side opposite to the nozzle holes. With adjustment of the degree of press-fitting of the insertion cylindrical portion 41 in the direction of the axis line C, a magnitude of the second elastic force for urging the movable core 30 (a second set load) at the time of closing the valve is adjusted. The second set load related to the second spring member SP2 is smaller than the first set load related to the first spring member SP1. Further, not only when the valve is closed, but also when the movable core 30 is urged in another situation, the magnitude of the second elastic force may be set as the second set load adjusted by the degree of press-fitting.
<Description of Operation>
Next, the operation of the fuel injection valve 1 will be described with reference to
As shown in a column (a) of
The movable core 30 is urged toward the valve closing side by the first elastic force of the first spring member SP1 transmitted from the cup 50, and the movable core 30 is urged toward the valve opening side by the second elastic force of the second spring member SP2. Since the first elastic force is larger than the second elastic force, the movable core 30 is pushed by the cup 50 and is moved (lifted down) toward the nozzle holes. The needle 20 is urged to the valve closing side by the first elastic force transmitted from the cup 50, and is pushed by the cup 50 to move (lift down) to the nozzle hole side, that is, seated on the body-side seat 11s to close the valve. In the valve closed state, a gap is provided between the valve opening contact surface 21a (refer to
As shown in a column (b) of
Since the elastic force of the first spring member SP1 does not act on the needle 20 until the time of the collision, the collision speed of the movable core 30 can be increased accordingly. Since such a collision force is added to the magnetic attraction force and used as the valve opening force of the needle 20, the needle 20 can be operated to open the valve even with a high-pressure fuel while inhibiting an increase in the magnetic attraction force required for opening the valve. The elastic force of the first spring member SP1 acts on the needle 20 toward the valve closing side in the state shown in the column (a), but does not act on the needle 20 in the state shown in the column (b). For that reason, an inhibition of the increase in the magnetic attraction force required for opening the valve can be further promoted.
After the collision, the movable core 30 continues to move further by the magnetic attraction force, and when the movement amount after the collision reaches the lift L2, the inner core 32 collides with the guide member 60 and stops moving as shown in the column (c) of
When the operation described above will be described in detail with reference to
Thereafter, at a time t3 when the moving amount of the movable core 30 reaches the gap L1, the movable core 30 collides with the needle 20, and the needle 20 starts the valve opening operation (refer to a column (d)). As a result, the fuel is injected from the nozzle holes 11a. Thereafter, the movable core 30 lifts up the needle 20 against the valve closing elastic force, and at a time t4 when the movable core 30 collides with the guide member 60, the lift of the needle 20 reaches the full lift (lift L2). A zero point shown on a vertical axis of the column (d) indicates a collision position between the movable core 30 and the needle 20 at the time t3.
Thereafter, a full lift state of the needle 20 is maintained by the magnetic attraction force, and the fuel injection is continued. Thereafter, when the energization is switched off at a time t5, the magnetic attraction force also decreases with a decrease in the drive current. At a time t6 when the magnetic attraction force reaches the actual valve closing elastic force F0, the movable core 30 starts moving to the valve closing side together with the cup 50. The needle 20 is pushed by a pressure of the fuel filled between the needle 20 and the cup 50 to start the lift-down operation (the valve closing operation) simultaneously with the start of the movement of the movable core 30.
Thereafter, at a time t7 when the needle 20 is lifted down by the lift L2, the valve body-side seat 20s is seated on the body-side seat 11s to close the flow channel 11b and the nozzle holes 11a. Thereafter, the movable core 30 continues to move to the valve closing side together with the cup 50, and the movement of the cup 50 to the valve closing side is stopped at a time t8 when the cup 50 contacts the needle 20. Thereafter, the movable core 30 continues to move to the valve closing side (inertial movement) by an inertial force, and then the movable core 30 moves (rebounds) to the valve opening side by the elastic force of the second spring member SP2. Thereafter, the movable core 30 collides with the cup 50 at a time t9 and moves (rebounds) to the valve opening side together with the cup 50, but is quickly pushed back by the valve closing elastic force and converges to an initial state shown in the column (a) of
Therefore, the smaller such rebound and the shorter the time required for convergence, the shorter the time from the end of injection to the return to the initial state. For that reason, when the multi-stage injection in which the fuel is injected multiple times per one combustion cycle of the internal combustion engine is executed, an interval between the injections can be shortened, and the number of injections included in the multi-stage injection can be increased. In addition, when the convergence time is shortened as described above, the injection amount when a partial lift injection to be described below is executed can be controlled with a high accuracy. The partial lift injection is injection of a small amount due to a short valve opening time by stopping the energization of the coil 17 and starting the valve closing operation before the needle 20 performing the valve opening operation reaches the full lift position.
<Description of Manufacturing Method>
Next, a method of manufacturing the fuel injection valve 1 will be described.
This manufacturing method includes the first set load adjustment process, the movable portion assembling process, the welding process, the fastening process and the resin molding process described below.
In a movable portion manufacturing process, the movable core 30, the second spring member SP2, the sleeve 40, and the cup 50 are assembled to the needle 20 to manufacture the movable portion M. As will be described later in detail, the movable portion M is manufactured so that the elastic force of the second spring member SP2 urged by the movable core 30 becomes a target value of the second set load.
In the welding process to be executed next, first, the nozzle hole body 11 is welded and joined to the main body 12. Next, the movable portion M is disposed in the movable chamber 12a of the main body 12, and thereafter, the fixed core 13 to which the support member 18 and the first spring member SP1 are assembled, the main body 12 to which the movable portion M is disposed, and the non-magnetic member 14 are welded and coupled to each other.
In the fastening process to be executed next, the bobbin 17a in a state in which the coil 17 is wound is disposed between the nut member 15 and the fixed core 13. Thereafter, the nut member 15 is fastened to the fixed core 13 so that the main body 12, the non-magnetic member 14, and the fixed core 13 are assembled by generating a surface pressure.
In the resin molding process to be executed next, the resin member 16 having the connector housing 16a is resin molded by pouring and solidifying molten resin on the outer peripheral surface of the fixed core 13.
In the first set load adjusting process to be performed thereafter, first, the first spring member SP1 is assembled to the flow channel 13a of the fixed core 13. Thereafter, the support member 18 is press-fitted into the flow channel 13a of the fixed core 13 to a predetermined position. The predetermined position of the press-fit may be determined in accordance with variations in the elastic modulus of the first spring member SP1 and the length in the direction of the axis line C, and variations in the dimensions of the respective portions of the fixed core 13. In any case, the predetermined position (press-fit position) is set so that the first elastic force urged by the needle 20 becomes a target value of the first set load. The fuel injection valve 1 is manufactured by the manufacturing method including the above processes.
<Detailed Description of Configuration Group A>
Next, among the configurations of the fuel injection valve 1 according to the present embodiment, a configuration group A including at least the press-fit portion 23 formed on the needle 20 and the configuration related to the press-fit portion 23 will be described in detail.
The movable portion assembling process described above includes Steps S10 to S15 shown in detail in
In the subsequent Step S11, the needle 20 is pressed against the cup 50 in a state in which the cup 50 is assembled to the contact portion 21 of the needle 20, and the valve closing force transmission contact surface 52c contacts the valve closing contact surface 21b (refer to
In the subsequent Step S12, the sleeve 40 is temporarily press-fitted into the press-fit portion 23 by a predetermined degree of press-fitting. For example, while the cup 50 is supported in the direction of the axis line C with the use of a support device J1, the press-fit load F2 is applied to the load application surface 43b of the sleeve 40 in the direction of the axis line C with the use of the load application device J2. In a temporary press-fitting, the movable core 30 contacts the cup 50, the second spring member SP2 contacts the sleeve 40 and the movable core 30, and the second spring member SP2 is in an elastically deformed state. Therefore, the support device J1 exhibits a reaction force F1 against the second elastic force by the second spring member SP2 to support the cup 50.
The temporary press-fit is a first press-fit, and thereafter, a second press-fit (main press-fit) is performed in Step S15 (to be described later). The degree of press-fitting in the temporary press-fit is a predetermined amount regardless of a machine difference variation, and for example, the temporary press-fit is performed to a position separated from the nozzle hole side end portion of the press-fit portion 23 toward the side opposite to the nozzle holes by a predetermined length in the direction of the axis line C.
In the subsequent Step S13, the second elastic force by the second spring member SP2, that is, the second set load is measured. For example, a force (reaction force F1) by which the support device J1 is pushed by the second elastic force is measured with the use of a measurement device (not shown). In this Step S13, the measurement is performed in a state in which the cup 50 is positioned above the needle 20, that is, in a state in which the direction of the movable portion M is set in the direction of an arrow indicating the vertical direction in
In the subsequent Step S14, a shortage amount of the measured second set load with respect to a target second set load is calculated, and an additional degree of press-fitting corresponding to the deficit amount is calculated. For example, an elastic modulus of the second spring member SP2 may be measured in advance, and the additional degree of press-fitting may be calculated based on the measured load shortage amount and the elastic modulus. Alternatively, the elastic modulus of the second spring member SP2 may be regarded as a standard value, and the additional degree of press-fitting may be calculated based on the measured load shortage amount and the standard value.
In the subsequent Step S15, the sleeve 40 is further press-fitted (main press-fitted) into the press-fit portion 23 by the additional degree of press-fitting calculated in Step S14. As described above, the assembling of the movable portion M is completed. In short, the second set load is measured during the press-fitting, and a main press-fit is executed in accordance with the measured value. Each step described above is an example of the configuration group A described above.
In short, the fuel injection valve 1 according to the present embodiment has the core boost structure in which the fuel injection valve 1 contacts the needle 20 at the time when the movable core 30 is moved by a predetermined distance to the side opposite to the nozzle holes to open the fuel injection valve 1, and includes the sleeve 40 that supports the second spring member SP2 that urges the movable core 30 toward the side opposite to the nozzle holes. The sleeve 40 is fixed to the needle 20 by press-fitting the sleeve 40, and the press-fitting direction of the sleeve 40 is the urging direction of the second spring member SP2. This makes it possible to adjust and fix the degree of press-fitting while measuring the second elastic force which increases with the progress of the press-fit. Therefore, the second elastic force at the time of completion of press-fitting can be set to the target set load of the second spring member SP2 with a high accuracy.
The set load is a second elastic force exerted by the elastic deformation of the second spring member in a state in which the second spring member is assembled to the fuel injection valve. Since the magnitude of the set load affects the valve opening and closing timing of the valve body, setting the set load to the target value with a high accuracy contributes to a reduction of the variation in the fuel injection amount. In contrast to the present embodiment in which the fixed member is press-fitted into the valve body, when a structure in which the fixed member is welded and fixed to the valve body is employed, the welded portion cannot be adjusted while measuring the second elastic force. For that reason, the set load varies due to variations among individuals such as variations in machine difference of the second spring member and variations in valve body length, and also due to thermal strain caused by welding.
On the other hand, in the present embodiment, since the fixed member is press-fitted into the valve body, the set load can be set to the target value with a high accuracy as described above. This makes it possible to reduce the variation of the fuel injection amount while adopting the core boost structure.
In contrast to the present embodiment, when the sleeve 40 and the press-fit portion 23 have the same hardness, there is a concern that the sleeve 40 and the press-fit portion 23 adhere to each other when the press-fit is temporarily stopped when the degree of press-fitting is adjusted while measuring. When the adhesion occurs, a load required to restart the press-fitting increases, and the workability of the press-fitting deteriorates. Therefore, according to the present embodiment having the different hardness, the above-mentioned adhesion concern can be reduced and the workability of press-fitting can be improved. The needle 20 is preferably harder than sleeve 40. The sleeve 40 preferably has a higher hardness than that of the movable core 30. A specific example of the material of the needle 20 is martensitic stainless steel. A specific example of the material of the sleeve 40 is ferritic stainless steel.
In press-fitting, at least one of the two members to be press-fitted needs to be plastically deformed. As the hardness is lower, the member is more easily plastically deformed, and the press-fit load required for press-fitting can be reduced. In view of the above circumstance, since the needle 20 requires hardness to withstand the collision with the body-side seat 11s (valve seat), there is a fear that the press-fit load required for press-fitting may be increased if the sleeve 40 is made harder than the hardness of the needle 20 to produce a hardness difference. Therefore, according to the present embodiment in which the sleeve 40 has a hardness lower than that of the press-fit portion 23, the above-mentioned concern can be inhibited to improve the press-fit workability. Further, since the sleeve 40 according to the present embodiment is not in contact with the movable core 30, a material softer than that of the inner core 32 or the like requiring the contact can be employed.
For example, solid lines A1 and A2 in
In contrast to the present embodiment, in a structure in which the sleeve 40 and the movable core 30 are in contact with each other, since there is a need to strengthen the press-fit of the sleeve 40, there is a need to set a large press-fit margin and increase the amount of plastic deformation caused by the press-fit. Therefore, according to the present embodiment of the structure in which the sleeve 40 and the movable core 30 do not contact each other, the necessity of strengthening the press-fit can be reduced, so that the press-fit load required for the press-fit can be reduced, and the workability of the press-fit can be improved.
In short, in the manufacturing method according to the present embodiment, the fuel injection valve 1 having the core boosting structure, which includes the sleeve 40 supporting the second spring member SP2 for urging the movable core 30 toward the side opposite to the nozzle holes is to be manufactured. While the sleeve 40 is press-fitted into the press-fit portion 23 of the needle 20, the second elastic force is measured while the movable core 30 is not moved, and the amount of press-fit is adjusted based on the measurement result to complete the press-fit. Therefore, the second elastic force at the time of completion of press-fitting can be set to the target set load of the second spring member SP2 with a high accuracy.
As described above, since the magnitude of the set load influences the valve opening and closing timing of the needle 20, setting the set load to the target value with a high accuracy contributes to the reduction of a variation in the fuel injection amount. For that reason, according to the present embodiment in which the set load can be set to the target value with a high accuracy as described above, the variation of the fuel injection amount can be reduced while employing the core boost structure.
Further, in the manufacturing method according to the present embodiment, the next fuel injection valve 1 is to be manufactured. The fuel injection valve 1 is disposed so as to be movable relative to the needle 20, and includes the cup 50 that contacts the needle 20 by moving relative to the fuel nozzle holes and transmits the first elastic force from the first spring member SP1 to the needle 20. In the manufacturing method described above, in Step S13 (load measurement process), the cup 50 is relatively moved to contact the needle 20, and the cup 50 in the contacting state is in contact with the movable core 30, thereby regulating the movement of the movable core 30.
The magnitude of the second set load due to the second spring member SP2 is important for inhibiting the movable core 30 from moving toward the nozzle hole after the valve has been closed, that is, important for quickly converging the rebound. Therefore, setting the second elastic force in the valve closed state as the second set load is advantageous for managing the rebound convergence. Therefore, since the second elastic force is measured by regulating the movement of the movable core 30 by contacting the cup 50, which contacts the needle 20, on the movable core 30, the second elastic force in the valve closed state is measured. This makes it possible to easily manage the rebound convergence.
<Detailed Description of Configuration Group B>
Next, among the configurations of the fuel injection valve 1 according to the present embodiment, a configuration group B including at least the fuel storage chamber B1, which will be described below, and the configuration related to the fuel storage chamber B1 will be described in detail with reference to
As shown in
Since the movable core 30 is urged to the cup 50 by the second elastic force, the movable core 30 is always in contact with the cup 50 except when the movable core 30 is inertially moved after the valve is closed and separated from the cup 50. More specifically, the second core contact surface 32b of the inner core 32 is always in contact with the core contact end face 51a of the cup 50. The cylindrical portion 51 of the cup 50, which forms the core contact end face 51a, separates the inside and the outside of the fuel storage chamber B1 from each other. The outside is a region where the fuel exists radially outside the outer peripheral surface 51d of the cup 50, the first core contact surface 32c is located inside the fuel storage chamber B1, and the third core contact surface 32d is located outside the fuel storage chamber B1.
The fuel storage chamber B1 is a region surrounded by the outer peripheral surface of the core sliding portion 22 of the needle 20, the valve opening contact surface 21a, the inner wall surface of the through hole 32a of the inner core 32, the first core contact surface 32c, and the inner peripheral surface of the cylindrical portion 51 of the cup 50. The fuel storage chamber B1 is a region surrounded as described above in a state in which the movable core 30 and the cup 50 contact each other. The fuel storage chamber B1 is a region surrounded as described above in a state in which the valve body-side seat 20s contacts the body-side seat 11s and the needle 20 is closed.
Communication grooves 32e are provided in the first core contact surface 32c and the second core contact surface 32b of the inner core 32. The communication grooves 32e communicate the inside and the outside of the fuel storage chamber B1 with each other in a state in which the second core contact surface 32b contacts the core contact end face 51a. The outside is a space different from the fuel storage chamber B1 when the cup 50 and the movable core 30 contact each other.
Here, the outside of the fuel storage chamber B1 corresponds to a region which will be exemplified below. In other words, a first region between the stopper contact end face 61a and the third core contact surface 32d of the guide member 60 corresponds to an outside. The first region is a region formed in a state in which the cup 50 and the movable core 30 contact each other and the movable core 30 and the guide member 60 do not contact each other. A surface of the fixed core 13 facing the movable core 30 is referred to as a fixed side core facing surface 13b. A surface of the outer core 31 facing the fixed core 13 is referred to as a movable core facing surface 31c. A second region between the fixed side core facing surface 13b and the movable core facing surface 31c, which is a region communicating with the first region, corresponds to the outside. A third region, which communicates with the second region, between the inner peripheral surfaces of the main body 12 (holder) and the non-magnetic member 14 (holder) and the outer peripheral surface of the outer core 31 corresponds to the outside.
As shown in
The inner core 32 corresponds to a “contact portion” in which the first core contact surface 32c and the second core contact surface 32b are formed. The outer core 31 corresponds to a “core body portion” made of a material different from that of the inner core 32 on which the movable core facing surface 31c facing the fixed core 13 is formed. The core body portion is outside a range in which the communication grooves 32e extend. In other words, the communication grooves 32e are provided in the inner core 32 but are not provided in the outer core 31.
The communication grooves 32e are provided over the entire area in the radial direction of the inner core 32, and are provided over the inner peripheral surface to the outer peripheral surface of the inner core 32. In other words, the communication grooves 32e are provided over the entire area in the radial direction of the first core contact surface 32c, the second core contact surface 32b, and the third core contact surface 32d.
As shown in
Examples of the method of machining the communication grooves 32e include laser machining, electric discharge machining, cutting with an end mill, and the like. First, a groove having a rectangular cross-sectional shape including the vertical wall surface 32e2 and the bottom wall surface 32e1 is processed. At this point of time, a burr generated at the time of processing may remain in the peripheral portion of the groove opening 32e4 in the vertical wall surface 32e2. After that, however, the tapered surface 32e3 having a trapezoidal cross-sectional shape is processed to remove the burr.
On the other hand, the fuel injection valve 1 according to the present embodiment includes the needle 20 (valve body), the fixed core 13, the movable core 30, the first spring member SP1 (spring member), and the cup 50 (valve closing force transmission member). The movable core 30 contacts the needle 20 at a point in time when the movable core 30 is attracted by the fixed core 13 and moved by a predetermined amount to the side opposite to the nozzle holes, and opens the needle 20. The first spring member SP1 is elastically deformed accompanying the valve opening operation of the needle 20, and exhibits a valve closing elastic force for closing the needle 20. The cup 50 is disposed so as to be movable relative to the needle 20, and when the cup 50 is moved relative to the nozzle hole side, the cup 50 contacts the needle 20 to transmit the valve closing elastic force to the needle 20. The movable core 30 has the first core contact surface 32c and the second core contact surface 32b, and the communication grooves 32e are provided in the first core contact surface 32c and the second core contact surface 32b to communicate the inside and the outside of the fuel storage chamber B1 with each other.
For that reason, when the movable core 30 moves to the side opposite to the nozzle holes, the fuel accumulated in the fuel storage chamber B1 flows out to the outside through the communication grooves 32e. Therefore, the compression of the fuel accumulated in the fuel storage chamber B1 is inhibited, so that the movable core 30 easily moves. For that reason, the reduction in the collision speed of the movable core 30 can be inhibited, so that the effect of reducing the magnetic attraction force by the core boost structure can be promoted. In addition, since the movable core 30 easily moves, the variation in the valve opening timing of the needle 20 can be reduced, and consequently, the variation in the fuel injection amount can be reduced.
According to the above configuration, the portions that easily flow out from the fuel storage chamber B1 to the outside are present at regular intervals around the axial direction. For that reason, when the movable core 30 moves in the axial direction, a change in the inclination direction of the movable core 30 with respect to the axial direction can be reduced. Therefore, since the behavior of the movable core 30 can be inhibited from becoming unstable, the variation in the valve opening response can be further reduced. If three or more communication grooves 32e are provided at regular intervals in the circumferential direction, the effect of inhibiting the behavior instability is promoted.
According to the above configuration, since the movable core facing surface 31c of the outer core 31 can have a flat shape having no groove, the magnetic attraction force attracted to the fixed core 13 can be inhibited from being reduced by the communication grooves.
When the needle 20 is in the full lift position, the inner core 32 contacts the guide member 60. In the above contact state, if the stopper contact end face 61a of the guide member 60 and the third core contact surface 32d of the inner core 32 are in close contact with each other, there is a concern that a phenomenon (linking phenomenon) occurs in which the third core contact surface 32d is hardly separated from the stopper contact end face 61a. In view of the above concern, in the present embodiment, since the communication grooves 32e are also provided in the third core contact surface 32d, when the movable core 30 starts moving to the nozzle hole side with the energization off, the fuel is supplied to the third core contact surface 32d in a state of contacting the stopper contact end face 61a. For that reason, since the movable core 30 can be inhibited from coming into close contact with the guide member 60 and from becoming difficult to separate from the guide member 60, the possibility that the start of the movement of the movable core 30 to the nozzle hole side is delayed due to the above-mentioned force of adhesion can be reduced. Therefore, a valve closing response time from when the energization is turned off to when the needle 20 closes the valve can be reduced, and the valve closing response can be improved.
In order to remove burrs generated in the groove opening 32e4 of the communication grooves 32e, it is desirable to polish the first core contact surface 32c and the second core contact surface 32b. For example, polishing is performed from a position indicated by a two-dot chain line in
Contrary to the present embodiment, in the case where the vertical wall surface 32e2 is not provided and the shape is shown by a one-dot chain line, a cross-sectional area of the communication grooves 32e becomes small, and a ratio of the cross-sectional area to be polished to the cross-sectional area of the communication grooves 32e becomes large. As a result, an influence of the variation in the polishing depth on the cross-sectional area of the communication grooves 32e becomes large, so that the variation in the cross-sectional area of the communication grooves 32e becomes large. For that reason, a variation in the degree of the fuel flowing out from the fuel storage chamber B1 to the outside through the communication grooves 32e becomes large, and a variation in the ease of movement of the movable core 30 becomes large, which hinders a reduction of the variation in the valve opening timing of the needle 20. On the other hand, according to the present embodiment, since the vertical wall surface 32e2 is provided, the ratio of the cross-sectional area to be polished becomes small, and the influence of the variation in a polishing depth on the cross-sectional area of the communication grooves 32e becomes small. For that reason, the variation in the degree of outflow of the fuel from the fuel storage chamber B1 to the outside through the communication grooves 32e is reduced, and the variation in the valve opening timing of the needle 20 can be promoted.
[Modification B1]
Although the communication grooves 32e shown in
As shown in
The outer communication grooves 31e and the communication grooves 32e have the same position in the circumferential direction. In an example of
The outer communication grooves 31e are provided over the entire area of the outer core 31 in the radial direction, and is provided from the inner peripheral surface to the outer peripheral surface of the outer core 31. In other words, the outer communication grooves 31e are provided over the entire area of the movable core facing surface 31c in the radial direction. The cross-sectional shape of the outer communication grooves 31e is the same as the cross-sectional shape of the communication grooves 32e shown in
As described above, according to the present modification having the outer communication grooves 31e, since the fuel flowing out from the outer diameter side end portion of the communication grooves 32e is diffused through the outer communication grooves 31e, an increase in a fuel pressure at the outer diameter side end portion of the communication grooves 32e can be inhibited, and the fuel flowing out through the communication grooves 32e can be promoted. This makes it possible to inhibit an increase in the fuel pressure between the guide member 60 and the inner core 32.
Further, in the present modification, since the inner diameter side end portion of the outer communication grooves 31e directly communicates with the outer diameter side end portion of the communication grooves 32e, the outflow of the fuel from the outer diameter side end portion can be further promoted.
Further, in the present modification, since the outer communication grooves 31e are provided over the entire area of the movable core facing surface 31c in the radial direction, the fuel flowing out from the outer diameter side end portion of the outer communication grooves 31e directly flows into the gap between the inner peripheral surface of the holder and the outer peripheral surface of the outer core 31. For that reason, an increase in the fuel pressure at the outer diameter side end portion of the outer communication grooves 31e can be inhibited, and the fuel outflow through the communication grooves 32e and the outer communication grooves 31e can be promoted.
Further, in the present modification, with respect to the dimension of the outer communication grooves 31e, a width dimension (dimension in circumferential direction) of a portion of the outer communication grooves 31e which opens toward the fixed core 13 is set to be smaller than a depth dimension (dimension in the axis line C) of the outer communication grooves 31e. According to the above configuration, the flow channel cross-sectional area of the outer communication grooves 31e can be increased while a decrease in the area of the movable core facing surface 31c caused by the provision of the outer communication grooves 31e can be inhibited. The “flow channel cross-sectional area” is an area of a cross section perpendicular to the flow direction when the fuel in the fuel storage chamber B1 flows radially outward through the outer communication grooves 31e. In other words, since the width dimension is smaller than the depth dimension as described above, the fuel discharge from the fuel storage chamber B1 at the time of the valve opening operation can be realized while inhibiting the reduction of the magnetic attraction force.
[Modification B2]
In the present modification shown in
Also, in the embodiment shown in
As described above, according to the present modification having the connection groove 32f, since the fuel flowing out from the outer diameter side end portion of the communication grooves 32e is diffused through the connection groove 32f, an increase in the fuel pressure at the outer diameter side end portion of the communication grooves 32e can be inhibited, and the fuel flowing out through the communication grooves 32e can be promoted.
Further, with the connection of the multiple communication grooves 31e, since the fuel can be promoted to flow out uniformly from the multiple communication grooves 31e, a change in the inclination direction of the movable core 30 with respect to the axial direction can be inhibited when the movable core 30 moves in the axial direction. Therefore, since the behavior of the movable core 30 can be inhibited from becoming unstable, the variation in the valve opening response can be further reduced.
[Modification B3]
The communication grooves 32e shown in
The communication grooves 32e shown in
As described above, according to the present modification having the conical communication grooves 32g, the communication grooves 32g can be provided only by pressing a tip of a drill blade against the movable core 30, and therefore the communication grooves 32g can be easily processed.
[Modification B4]
In the embodiment shown in
As described above, according to the present modification in which the communication holes 20c are provided in the needle 20, when the movable core 30 moves to the side opposite to the nozzle holes, the fuel accumulated in the fuel storage chamber B1 flows out to the internal passage 20a (the outside) of the needle 20 through the communication holes 20c. Therefore, the compression of the fuel accumulated in the fuel storage chamber B1 is inhibited, so that the movable core 30 easily moves. For that reason, the reduction in the collision speed of the movable core 30 can be inhibited, so that the effect of reducing the magnetic attraction force by the core boost structure can be promoted. In addition, since the movable core 30 easily moves, the variation in the valve opening timing of the needle 20 can be reduced, and consequently, the variation in the fuel injection amount can be reduced.
[Modification B5]
In the present modification shown in
The multiple sliding surface communication grooves 20d are provided, and the multiple sliding surface communication grooves 20d are arranged at regular intervals in the circumferential direction when viewed from the moving direction of the needle 20. The sliding surface communication grooves 20d each have a shape linearly extending in the direction of the axis line C of the needle 20.
As described above, according to the present modification in which the sliding surface communication grooves 20d are provided in the valve body-side sliding surface 21c which is the sliding surface between the needle 20 and the cup 50, when the movable core 30 moves to the side opposite to the nozzle holes, the fuel accumulated in the fuel storage chamber B1 flows out to the outside through the sliding surface communication grooves 20d. In the present specification, the outside is a gap between the valve closing contact surface 21b and the valve closing force transmission contact surface 52c, and the internal passage 20a. Therefore, the compression of the fuel accumulated in the fuel storage chamber B1 is inhibited, so that the movable core 30 easily moves. For that reason, the reduction in the collision speed of the movable core 30 can be inhibited, so that the effect of reducing the magnetic attraction force by the core boost structure can be promoted. In addition, since the movable core 30 easily moves, the variation in the valve opening timing of the needle 20 can be reduced, and consequently, the variation in the fuel injection amount can be reduced.
[Modification B6]
In the present modification shown in
The multiple second sliding surface communication grooves 32h are provided, and the multiple second sliding surface communication grooves 32h are arranged at regular intervals in the circumferential direction when viewed from the moving direction of the movable core 30. The second sliding surface communication grooves 32h each have a shape linearly extending in the direction of the axis line C of the movable core 30.
As described above, according to the present modification in which the second sliding surface communication grooves 32h are provided on the sliding surface between the needle 20 and the inner core 32, when the movable core 30 moves to the side opposite to the nozzle holes, the fuel accumulated in the fuel storage chamber B1 flows out to the movable chamber 12a (the outside) through the second sliding surface communication grooves 32h. Therefore, the compression of the fuel accumulated in the fuel storage chamber B1 is inhibited, so that the movable core 30 easily moves. For that reason, the reduction in the collision speed of the movable core 30 can be inhibited, so that the effect of reducing the magnetic attraction force by the core boost structure can be promoted. In addition, since the movable core 30 easily moves, the variation in the valve opening timing of the needle 20 can be reduced, and consequently, the variation in the fuel injection amount can be reduced.
<Detailed Description of Configuration Group C>
Next, among the configurations of the fuel injection valve 1 according to the present embodiment, a configuration group C including at least a supply flow channel to be described below and a configuration related to the supply flow channel will be described in detail with reference to
As shown in
The annular inner side corresponds to an internal passage 20a of the needle 20. The annular outer side corresponds to a gap B2 (refer to
The main flow channels 20e (supply flow channels) each have a shape extending so as to connect an inner peripheral surface of the needle 20 that defines the internal passage 20a and an outer peripheral surface of the needle 20. The outer peripheral surface of the needle 20 functions as a wall surface of a passage through which the fuel flows through the nozzle holes 11a. The fuel flowing through the passage provided by the gap between the outer peripheral surface of the needle 20 and the inner peripheral surface of the cylindrical portion 51 flows into the fuel storage chamber B1. Thereafter, the fuel flows into the movable chamber 12a through a gap between the inner peripheral surface of the movable core 30 and the outer peripheral surface of the needle 20 and a gap between the outer peripheral surface of the movable core 30 and the inner peripheral surface of the main body 12, and flows into the nozzle holes 11a through the flow channel 12b.
As shown in
As shown in
A depth dimension 201h of the main flow channels 20e is defined as a dimension of the main flow channels 20e in the direction of the axis line C, and a width dimension 201w of the main flow channels 20e is defined as a dimension of the needle 20 around the direction of the axis line C (refer to
To cope with the above concern, the present embodiment includes the needle 20 (valve body), the fixed core 13, the movable core 30, the first spring member SP1 (spring member), and the cup 50 (valve closing force transmission member). When the movable core 30 is attracted by the fixed core 13 and moved by a predetermined amount, the movable core 30 contacts the valve opening contact surface 21a, which is formed on the needle 20, and operates the needle 20 to open the valve. The first spring member SP1 is elastically deformed accompanying the valve opening operation of the needle 20, and exhibits a valve closing elastic force for closing the needle 20. The cup 50 contacts the valve closing contact surface 21b formed on the needle 20, and transmits the valve closing elastic force to the needle 20. When the movable core 30 starts to move together with the cup 50 by the predetermined amount, the cup 50 contacts the valve closing contact surface 21b. The needle 20 has the main flow channels 20e (supply flow channels) for supplying the fuel to the valve closing contact surface 21b in a state of contacting the cup 50.
Therefore, when the movable core 30 starts to move by the predetermined amount, the fuel is supplied to the valve closing contact surface 21b in a state in which the movable core 30 contacts the cup 50. For that reason, since the cup 50 can be inhibited from coming into close contact with the needle 20 and becoming difficult to separate from the needle 20, the possibility that the start of the movement of the movable core 30 by the predetermined amount is delayed due to the above-mentioned force of close contact can be reduced. Therefore, the valve opening response time from the start of the energization of the coil 17 to the start of the valve opening of the needle 20 can be shortened, and the valve opening response can be improved. In addition, the variation in the valve opening timing due to the obstruction of the movement of the movable core 30 can be reduced, and the variation in the fuel injection amount can be reduced.
In view of the above points, in the fuel injection valve 1 according to the present embodiment, the depth dimension 201h of the main flow channels 20e is set to be larger than the width dimension 201w of the main flow channels 20e. For that reason, the flow rate of the fuel flowing through the main flow channels 20e can be sufficiently ensured, and the progress of the wear of the valve closing contact surface 21b due to the excessive surface pressure can be inhibited.
[Modification C1] In the present modification, the cross-sectional shape of the main flow channels 20e is modified. In other words, the straight portion 201 of the main flow channels 20e shown in
As shown in
As a machining method of the main flow channels 20e shown in
[Modification C2]
In the present modification shown in
In an example of
In an example of
In a state in which the needle 20 contacts the cup 50, a part of the fuel flowing into the main flow channels 20e from both sides of the annular inner side and the annular outer side is supplied to the valve closing contact surface 21b from the circumferential direction. Further, the fuel that has flowed into the branch flow channel 205 after having flowed into the main flow channels 20e is supplied to the valve closing contact surface 21b from the radial direction.
[Modification C3]
In the present modification shown in
Among the fuel inflow ports 203 and 204 provided at both ends of the main flow channels 20e, the inflow port 203 located outside the above-mentioned annularly extending region is provided with the inflow portion 202 having an enlarged area. On the other hand, the inflow port 204 located inside the annularly extending region is not provided with an inflow portion having an enlarged area. Corner portions of the outer peripheral portion and the inner peripheral portion of the contact portion 21 of the needle 20 are chamfered, and the outer peripheral portion and the inner peripheral portion of the contact portion 21 are formed in a tapered shape.
The main flow channels 20e are provided by laser processing. A one-dot chain line in
After the laser beam has been moved to the outer end portion of the straight portion 201 to complete the processing of the straight portion 201, the laser beam is further moved to the radially outer side, and the groove in the portion corresponding to the inflow portion 202 is processed by the laser as shown in the column (b) of
[Modification C4]
The supply flow channel shown in
According to the above configuration, when the movable core 30 starts to move by a predetermined amount, the fuel of the flow channel 13a is supplied to the valve closing contact surface 21b in a state in which the movable core 30 contacts the cup 50 through the through hole 52d. For that reason, similarly to the embodiment of
[Modification C5]
In the supply flow channel shown in
The plate 210 is disposed between the needle 20 and the cup 50 and is circular plate-shaped and made of metal. In the illustrated example, the main flow channel 210e is provided on the surface of the plate 210 on the nozzle hole side, alternatively may be formed on the surface of the plate 210 on the side opposite to the nozzle hole side. The multiple (for example, four) main flow channels 210e are provided, and the multiple main flow channels 210e are arranged at regular intervals in the circumferential direction when viewed from the moving direction of the movable core 30. The main flow channels 210e each have a shape linearly extending in the radial direction. The multiple main flow channels 210e each have the same shape.
The main flow channels 210e each have a shape extending so as to connect the annular inner side and the annular outer side across the annular region in which the valve closing contact surface 21b is formed in the same manner as the main flow channels 20e shown in
The plate 210 is not coupled to the needle 20 and the cup 50, but is defined as a part of the needle 20 or the cup 50. A through hole 52a of the cup 50 and a through hole 210a communicating with the internal passage 20a of the needle 20 are provided in the plate 210.
As described above, according to the present modification, when the movable core 30 starts to move by a predetermined amount, the fuel in the flow channel 13a is supplied to the valve closing contact surface 21b in a state in which the movable core 30 contacts the cup 50 through the plate 210 through the main flow channel 210e. For that reason, similarly to the embodiment of
[Modification C6]
The supply flow channel shown in
According to the supply flow channel by the unevenness, the hardness of the valve closing contact surface 21b is increased by shot blasting. For that reason, the abrasion resistance of the valve closing contact surface 21b can be improved due to the repeated collision of the cup 50 with the needle 20.
Instead of performing the shot blasting on the needle 20 to form the unevenness as described above, shot blasting may be performed on the valve closing force transmission contact surface 52c of the cup 50 to form the unevenness. In that case, the supply flow channel is provided by the unevenness formed on the valve closing force transmission contact surface 52c.
<Detailed Description of Configuration Group D>
Next, among the configurations of the fuel injection valve 1 according to the present embodiment, a configuration group D including at least a recessed surface 60a to be described below and a configuration related to the recessed surface 60a will be described in detail with reference to
As described above, the inner peripheral surface of the cylindrical portion 61 of the guide member 60 forms the sliding surface 61b that slides with the outer peripheral surface 51d of the cylindrical portion 51 of the cup 50. The sliding surface 61b slides the outer peripheral surface 51d of the cup 50 so as to guide the movement of the cup 50 in the direction of the axis line C while restricting the movement of the cup 50 in the radial direction. The sliding surface 61b is a surface having a shape extending in parallel with the direction of the axis line C.
The recessed surface 60a is formed on a surface of the inner surface of the guide member 60 which is connected to the side opposite to the nozzle holes of the sliding surface 61b. The recessed surface 60a is shaped to be recessed in a direction in which the gap to the cup 50 is enlarged in the radial direction. The recessed surface 60a has a shape extending annularly around the axis line C, and has the same shape in any cross section in the circumferential direction.
An adjacent surface 60a1 of the recessed surface 60a adjacent to the sliding surface 61b is a surface connected to the sliding surface 61b on the side opposite to the nozzle hole, and is shaped to gradually enlarge a gap CL1 from the cup 50 in the radial direction as a distance from the sliding surface 61b increases. The adjacent surface 60a1 includes a tapered surface 60a2 extending linearly in a cross section including the axis line C. A boundary portion 60b of the guide member 60 including a boundary between the adjacent surface 60a1 and the sliding surface 61b has a shape curved to be convex inward in the radial direction, that is, an R-shape. As a result, the cup 50 can be inhibited from being worn by the guide member 60.
A chamfered portion 61c formed in a tapered shape by chamfering is provided at a portion connecting the stopper contact end face 61a and the sliding surface 61b. The boundary portion including the boundary between the chamfered portion 61c and the sliding surface 61b has a shape curved to be convex inward in the radial direction, and inhibits the cup 50 from being worn by the guide member 60.
In the cup 50, a corner portion 51g connecting the outer peripheral surface 51d and the core contact end face 51a and a corner portion 51h connecting the transmission member-side sliding surface 51c and the core contact end face 51a are chamfered so as to have a tapered shape or an R shape. A corner portion 21d of the needle 20, which connects the valve body-side sliding surface 21c and the valve opening contact surface 21a, is also chamfered so as to have a tapered shape or an R-shape. A boundary portion 21e including a boundary between the chamfered portion formed on the side opposite to the nozzle hole with respect to the valve body-side sliding surface 21c and the valve body-side sliding surface 21c has a shape curved to be convex outward in the radial direction, and inhibits wear between the cup 50 and the needle 20.
In the following description, a part of the surface of the cup 50, which includes the outer peripheral surface 51d of the cylindrical portion 51 of the cup 50 and extends in parallel with the direction of the axis line C, is referred to as a parallel surface. In an example of
Further, a surface which is connected to the side opposite to the nozzle holes of the parallel surface and which is located in the radially inner side of the parallel surface is referred to as a connection surface 51e. The connection surface 51e is curved to be convex outward of the cup 50 in the radial direction. In the surface of the cup 50, a range indicated by a symbol M2 in
A boundary line between the parallel surface and the connection surface 51e is referred to as a connection boundary line 51f (refer to a circle in
The outer peripheral surface of the guide member 60 is press-fitted into the enlarged diameter portion 13c of the fixed core 13. In this manner, since the guide member 60 is press-fitted into the fixed core 13, the guide member 60 is not tilted with respect to the fixed core 13. However, a dimensional tolerance of the outer peripheral surface of the guide member 60 or the inner peripheral surface of the enlarged diameter portion 13c is tilted. On the other hand, since the cup 50 is slidably disposed with respect to the guide member 60, a gap CL1 for sliding is provided between the cup 50 and the guide member 60. Accordingly, the cup 50 can be tilted with respect to the fixed core 13 and the guide member 60. In other words, the axis line C of the cup 50 may be tilted with respect to the axis line C of the fixed core 13.
Since the needle 20 is slidably disposed on the cup 50, a gap CL2 for sliding is provided between the needle 20 and the cup 50. Therefore, the needle 20 may be further tilted with respect to the inclinable cup 50. In other words, the axis line C of the needle 20 may be further tilted relative to the axis line C of the inclinable cup 50. Therefore, an angle (maximum inclination angle) at which the needle 20 is tilted to the maximum and the cup 50 is tilted to the maximum in the same direction as that of the needle 20 corresponds to the assumed maximum inclination angle θ2 (refer to
The gap CL1 between the parallel surface of the cup 50 and the sliding surface 61b of the guide member 60 is set to be larger than the gap CL2 between the cup 50 and the needle 20. Therefore, the inclination angle of the cup 50 when the gap CL2 is zero is larger than the inclination angle of the needle 20 when the gap CL1 is zero.
A sliding distance between the cup 50 and the guide member 60 in the gap CL1 is set to be longer than a sliding distance between the cup 50 and the needle 20 in the gap CL2. In this example, the longer the sliding distance, the smaller the inclination caused by the gap. For example, the longer the sliding distance in the gap CL1, the smaller the inclination of the cup 50 with respect to the guide member 60. The longer the sliding distance in the gap CL2, the smaller the inclination of the needle 20 with respect to the cup 50. Even if both those inclinations are maximum, the connection surface 51e is set so as not to contact the guide member 60.
The guide member 60 is made of a magnetic material, and the cup 50 is made of a non-magnetic material. In general, a nonmagnetic material has a lower hardness than a magnetic material. Nevertheless, in the present embodiment, the cup 50 and the guide member 60 have the same hardness. In other words, a high hardness nonmagnetic material is used as the cup 50 instead of a general nonmagnetic material. The hardness of the cup 50 (cup hardness) and the hardness of the guide member 60 (guide member hardness) are, for example, values ranging from Vickers hardness HV600 to HV700. If the deviation of the guide member hardness with respect to the cup hardness falls within a range of −10% to +10% of the cup hardness, both the hardness are considered to have the same hardness.
To cope with the above concern, the present embodiment includes the needle 20 (valve body), the fixed core 13, the movable core 30, the first spring member SP1 (spring member), the cup 50 (valve closing force transmission member), and the guide member 60.
The movable core 30 contacts the needle 20 at a point of time when the movable core 30 is attracted by the fixed core 13 and moved by a predetermined amount, and causes the needle 20 to perform the valve opening operation. The first spring member SP1 is elastically deformed accompanying the valve opening operation of the needle 20, and exhibits a valve closing elastic force for closing the needle 20. The cup 50 has a valve body transmission portion (circular plate portion 52) that contacts the first spring member SP1 and the needle 20 to transmit the valve closing elastic force to the needle 20, and a cylindrical portion 51 that urges the movable core 30 toward the nozzle holes. The guide member 60 has a sliding surface 61b that slides the outer peripheral surface 51d of the cylindrical portion 51 so as to guide the movement of the cylindrical portion 51 in the direction of the axis line C while restricting the movement of the cylindrical portion 51 in the radial direction. The guide member 60 is provided with the recessed surface 60a which is a surface connected to the sliding surface 61b on the side opposite to the nozzle hole and which is recessed in a direction in which the gap with the cup 50 is enlarged in the radial direction. The valve body transmission portion is a circular plate portion 52 having a circular plate shape, and the cylindrical portion 51 is a shape extending from the circular plate outer peripheral edge of the circular plate portion 52 to the nozzle hole side.
In the surface of the cup 50, a surface that includes the outer peripheral surface of the cylindrical portion 51 and extends in parallel with the axis line C direction is the parallel surface, a surface that is connected to the parallel surface on the side opposite to the nozzle holes and is located on the radially inner side of the parallel surface is the connection surface 51e, and a boundary line between the parallel surface and the connection surface 51e is the connection boundary line 51f. The movable range M3 of the connection boundary line 51f in the axial direction is entirely located within a range N1 of the recessed surface 60a in the axial direction. In other words, the position of the connection boundary line 51f in the axial direction is in the range N1 in which the recessed surface 60a is provided, regardless of whether the needle 20 is fully lifted or closed.
For that reason, when the cup 50 moves in the axial direction while sliding on the guide member 60, the connection boundary line 51f faces the recessed surface 60a and does not contact the sliding surface 61b. This makes it possible to inhibit the cup 50 from being pressed against the guide member 60 in a state where the surface pressure component in the axial direction is large, and makes it possible to reduce the wear of the cup 50. For that reason, the inclination of the cup 50 can be reduced, and consequently the inclination of the needle 20 can be reduced, so that the variation in the fuel injection amount due to the variation in the valve opening and closing timing of the needle 20 can be reduced.
In this example, the needle 20 may be opened and closed in a state of being tilted with respect to the direction of the axis line C. When the needle 20 is tilted, the cup 50 is tilted by a tilting force, and when the cup 50 is tilted, the force with which the cup 50 is pressed against the guide member 60 increases, which may cause wear. Therefore, according to the present embodiment in which the recessed surface 60a is applied to a configuration in which wear is concerned as described above, the wear reduction effect by the recessed surface 60a can be more effectively exhibited.
<Detailed Description of Configuration Group E>
Next, a configuration group E including at least the press-fit structure between the outer core 31 and the inner core 32 and the configuration related to the press-fit structure among the configurations of the fuel injection valve 1 according to the present embodiment will be described in detail with reference to
As shown in
In the present embodiment, the press-fit surfaces 31p and 32p are formed on a part of the movable core 30 on the side opposite to the nozzle hole, and in the following description, a portion of the outer core 31 where the press-fit surface 31p is formed and the entire portion in the direction of the axis line C including the press-fit surface 31p is referred to as a press-fit region 311. A portion of the outer core 31 where the press-fit surface 31p is not formed and the entire portion in the radial direction which does not include the press-fit surface 31p is referred to as a non-press-fit region 312. In other words, in the direction of the axis line C, the outer core 31 is divided into a press-fit region 311 on a side opposite to the nozzle hole and a non-press-fit region 312 on the nozzle hole side adjacent to the press-fit region in the direction of the axis line C.
The non-press-fit region 312 is formed with a locking portion 31b that contacts a locking portion 32i of the inner core 32 in the direction of the axis line C. The locking portion 32i prevents the inner core 32 from being deviated toward the nozzle hole side with respect to the outer core 31 due to the collision of the inner core 32 with the guide member 60 and the like. In the inner peripheral surface of the non-press-fit region 312, a gap B3 from the inner core 32 is provided in a portion from the locking portion 31b to the boundary of the press-fit region 311. In other words, the gap B3 is located at the boundary between the press-fit region 311 and the non-press-fit region 312.
The gap B3 functions as a region for confining burrs generated when the inner core 32 is press-fitted into the outer core 31. Since the material of the outer core 31 is softer than that of the inner core 32, the burrs are generated on the press-fit surface 31p of the outer core 31. More specifically, the above-mentioned burrs are generated when the nozzle hole side end portion of the press-fit surface 32p of the inner core 32 scrapes off a part of the press-fit surface 31p of the outer core 31.
In the present embodiment, after the inner core 32 has been assembled to the outer core 31, the communication grooves 32e and the outer communication grooves 31e are provided by cutting or the like, and then the first core contact surface 32c and the second core contact surface 32b are ground. As a result, the positions of the first core contact surface 32c and the second core contact surface 32b in the axis line C are aligned.
The outer peripheral surface of the outer core 31 indicated by a solid line in
The holder for movably accommodating the movable core 30 has the main body 12, which is a magnetic member having magnetism, and the non-magnetic member 14 adjacent to the main body 12 in the moving direction, and an end face of the main body 12 and an end face of the non-magnetic member 14 are welded to each other. A portion of the holder facing the outer peripheral surface of the press-fit region 311 is defined as a press-fit facing portion H1, and a portion of the holder facing the outer peripheral surface of the non-press-fit region 312 is defined as a non-press-fit facing portion H2. A minimum gap in the radial direction between the inner peripheral surface of the press-fit facing portion H1 and the outer peripheral surface of the press-fit region 311 is defined as a press-fit portion gap CL3, and a minimum gap in the radial direction between the inner peripheral surface of the non-press-fit facing portion H2 and the outer peripheral surface of the non-press-fit region 312 is defined as a non-press-fit portion gap CL4. A minimum inner diameter of the press-fit facing portion H1 is set to be larger than a minimum inner diameter of the non-press-fit facing portion H2 so that the press-fit portion gap CL3 is larger than the non-press-fit portion gap CL4.
The inner peripheral surface of the press-fit facing portion H1 has a shape extending in parallel with the moving direction of the movable core 30 (in the direction of the axis line C). The inner peripheral surface of the non-press-fit facing portion H2 has a parallel surface H2a extending in parallel with the moving direction, and a connection surface H2b connecting the inner peripheral surface of the press-fit facing portion H1 and the parallel surface H2a. The connection surface H2b has a shape in which the inner diameter gradually decreases toward the parallel surface H2a. Although a part of the main body 12 is included in the non-press-fit facing portion H2, the non-magnetic member 14 is not included in the non-press-fit facing portion H2, and the parallel surface H2a and the connection surface H2b are formed by the main body 12. In other words, the main body 12 has a shape having the parallel surface H2a and the connection surface H2b having different inner diameter dimensions. The non-press-fit portion gap CL4, which is the smallest gap between the non-press-fit facing portion H2 and the non-press-fit region 312, corresponds to a gap in the parallel surface H2a formed by the main body 12.
More specifically, a flow channel cross-sectional area defined by the press-fit portion gap CL3 is larger than a flow channel cross-sectional area defined by the non-press-fit portion gap CL4. Those flow channel cross-sectional areas are areas of a cross section perpendicular to the axis line C of the flow channel defined by the press-fit portion gap CL3 and CL4.
The inner peripheral surface H1a of the press-fit facing portion H1 has a shape extending in parallel with the moving direction. The press-fit facing portion H1 includes a part of the non-magnetic member 14 and a part of the main body 12. The non-magnetic member 14 is formed to have a uniform inner diameter dimension along the entire axis line C direction. The press-fit portion gap CL3, which is the smallest gap between the press-fit facing portion H1 and the press-fit region 311, corresponds to a gap at a portion of the main body 12 on the side opposite to the nozzle hole with respect to the connection surface H2b, or at the non-magnetic member 14.
On the other hand, the fuel injection valve 1 according to the present embodiment includes the needle 20 (valve body), the fixed core 13, the movable core 30, the main body 12 (holder) and the non-magnetic member 14 (holder), and the guide member 60 (stopper member). The movable core 30 has a cylindrical shape, and moves together with the needle 20 by the magnetic attraction force to open the nozzle holes 11a. The holder has a movable chamber 12a filled with fuel, and accommodates the movable core 30 in the movable chamber 12a in a movable state. The guide member 60 contacts the movable core 30 and restricts the movable core 30 from moving away from the nozzle holes 11a. The movable core 30 has the inner core 32 contacting the guide member 60, and the outer core 31 press-fitted into the outer peripheral surface of the inner core 32. The outer core 31 has the press-fit region 311 which is press-fitted into the outer peripheral surface of the inner core 32 in the moving direction of the movable core 30, and the non-press-fit region 312 which is not press-fit into the outer peripheral surface of the inner core 32 and is adjacent to the press-fit region 311 in the moving direction. Among the gaps between the inner peripheral surface of the holder and the outer peripheral surface of the movable core 30, the smallest gap CL3 in the press-fit region 311 is larger than the smallest gap CL4 in the non-press-fit region 312.
In this example, the flow resistance received by the movable core 30 from the fuel existing in the gap between the outer core outer peripheral surface and the holder inner peripheral surface is greatly influenced by the smallest gap when the size of the gap changes in accordance with the axial position. The gap CL3 in the press-fit region 311 in the gap between the inner peripheral surface of the holder and the outer peripheral surface of the movable cores is larger than the gap CL4 in the non-press-fit region 312. Therefore, contrary to the present embodiment, when the minimum gap CL3 in the press-fit region 311 is smaller than the minimum gap CL4 in the non-press-fit region 312, the flow resistance is greatly affected by the gap CL3 in the press-fit region 311. As a result, a large variation in the flow resistance between machines occurs. In contrast, according to the present embodiment, the minimum gap CL3 in the press-fit region 311 is larger than the minimum gap CL4 in the non-press-fit region 312. For that reason, the flow resistance can be inhibited from being affected by the gap CL3 in the press-fit regions 311, and the moving speed of the movable core 30 can be inhibited from varying. As a result, the machine difference variation in the valve opening response can be inhibited, and consequently, the injection amount variation can be reduced.
A boundary between a portion (large expansion portion 311b) in which expansion is largely generated by press-fitting and a portion (small expansion portion 311a) in which expansion is hardly generated is gradually expanded. In view of the above circumstances, according to the present embodiment having the connection surface H2b whose inner diameter gradually decreases, the gap of the magnetic circuit provided by the portion of the connection surface H2b can be made as small as possible. As shown in
[Modification E1]
In the present modification shown in
Specifically, the outer diameter of the press-fit region 311 is formed to be sufficiently smaller than the outer diameter of the non-press-fit region 312 before press-fitting, and the outer diameter of the press-fit region 311 is formed to be smaller than the outer diameter of the non-press-fit region 312 even when the press-fit region 311 is expanded by press-fitting. In short, in a state before press-fitting, the outer peripheral surface of the press-fit region 311 is cut to form a recess portion 311c, and a cutting depth of the recess portion 311c is set to be sufficiently large so that the recess portion 311c remains even after expansion due to press-fitting. In addition, an inner diameter dimension of the non-press-fit facing portion H2 is the same in the direction of the axis line C in the same manner as the press-fit facing portion H1.
As described above, since the outer peripheral surface of the press-fit region 311 is formed to be smaller than the non-press-fit region 312 and the inner peripheral surface of the non-press-fit facing portion H2 is formed to be the same as the press-fit facing portion H1, the press-fit portion gap CL3 is larger than the non-press-fit portion gap CL4. For that reason, the same effects as those of the fuel injection valve 1 shown in
[Modification E2]
In the present modification shown in
[Modification E3]
In the present modification shown in
More specifically, in a state before press-fitting with the inner core 32, the outer core 31 whose outer peripheral surface is circular (perfect circle) in a top view is prepared (preparation process) and is press-fitted with the inner core 32 (press-fitting process). Thereafter, the large expansion portion 311b (refer to
While the valve closing force transmission member according to the first embodiment is provided by the cup 50, a valve closing force transmission member according to the present embodiment is provided by a first cup 501, a second cup 502, and a third spring member SP3 (refer to
The first cup 501 contacts a first spring member SP1 and a needle 20, and transmits a valve closing elastic force by the first spring member SP1 to the needle 20. In short, the first cup 501 exhibits the same function as the circular plate portion 52 of the cup 50 according to the first embodiment. The first cup 501 is formed with a through hole 52a similar to that of the first embodiment.
The third spring member SP3 is an elastic member that is elastically deformed in the axial direction to exert an elastic force. One end of the third spring member SP3 contacts a contact surface 501a of the first cup 501, and the other end of the third spring member SP3 contacts a contact surface 502a of the second cup 502. As a result, the third spring member SP3 is sandwiched between the first cup 501 and the second cup 502 and is elastically deformed in the axial direction, and exhibits an elastic force due to the elastic deformation.
The second cup 502 contacts the movable core 30 during the valve closing operation to urge the movable core 30 toward the nozzle holes. In short, the second cup 502 exhibits the same function as that of the cylindrical portion 51 of the cup 50 according to the first embodiment. The third spring member SP3 exerts a function of transmitting a force in the axial direction between the first cup 501 and the second cup 502.
The needle 20 has a main body portion 2001 and an enlarged diameter portion 2002. A valve closing contact surface 21b is formed at an end of the main body portion 2001 on the side opposite to the nozzle holes. The valve closing contact surface 21b contacts a valve closing force transmission contact surface 52c of the valve closing force transmission member (first cup 501) in the same manner as in the first embodiment.
The enlarged diameter portion 2002 is located closer to the nozzle hole side than the valve closing contact surface 21b, and has a circular plate shape in which a diameter of the main body portion 2001 is enlarged. A valve opening contact surface 21a is formed on a surface of the nozzle hole side of the enlarged diameter portion 2002. The valve opening contact surface 21a contacts the first core contact surface 32c of the movable core 30 in the same manner as in the first embodiment. A length of a gap between the valve opening contact surface 21a and the first core contact surface 32c in the direction of the axis line C in a valve close state corresponds to a gap L1 according to the first embodiment.
In a state immediately after the energization of a coil 17 has been switched from OFF to ON, a magnetic attraction force acts on the movable core 30 to start the movement of the movable core 30 toward the valve opening side. Then, when the movable core 30 moves while pushing up the second cup 502 and the moving amount reaches the gap L1, the first core contact surface 32c of the movable core 30 collides with the valve opening contact surface 21a in the needle 20.
In the present embodiment, the guide member 60 is eliminated, and the movable core 30 contacts the fixed core 13, thereby regulating the valve opening operation amount of the needle 20. When the movable core 30 collides with the needle 20 as described above, a gap is provided between the fixed core 13 and the movable core 30, and the length of the gap in the direction of the axis line C corresponds to a lift L2 of the first embodiment.
The elastic force of the first spring member SP1 also acts on the needle 20 until the time of the collision. After the collision, the movable core 30 continues to move further by the magnetic attraction force, and when the movement amount after the collision reaches a lift L2, the movable core 30 collides with the fixed core 13 and stops moving. A separation distance between the body-side seat 11s and the valve body-side seat 20s in the direction of the axis line C at the time of stopping the movement corresponds to a full lift of the needle 20, and corresponds to the lift L2 described above.
The valve closing force transmission member (cup 50) according to the first embodiment has the cup shape having the cylindrical portion 51 and the circular plate portion 52. On the other hand, a valve closing force transmission member according to the present embodiment has a circular plate shape configured by a circular plate portion 52 in which the cylindrical portion 51 is eliminated (refer to
In the first embodiment, a surface (core contact end face 51a) of the valve closing force transmission member, with which the contact surface (second core contact surface 32b) of the movable core 30 is in contact, is formed in the cylindrical portion 51. On the other hand, in the present embodiment, a surface of the circular plate portion 52 on the nozzle hole side functions as a core contact end face 52e (refer to
The disclosure herein is not limited to the combinations of components and/or elements shown in the embodiments. The disclosure may have additional portions that may be added to the embodiments. The disclosure encompasses omission of components and/or elements of the embodiments. The disclosure encompasses the replacement or combination of components and/or elements between one embodiment and another. For example, the fuel injection valve 1 according to the first embodiment includes all of the configuration groups A, B, C, D, and E, but may be a fuel injection valve having any combination of the configuration groups A, B, C, D, and E.
In the first embodiment, the temporary press-fitting is performed once as shown in
In the press-fitting operation shown in
In the press-fitting operation shown in
The communication grooves 32e shown in
Although the outer communication grooves 31e shown in
In the examples of
Although the sliding surface communication grooves 20d are provided in the needle 20 in an example of
In an example of
In the first embodiment, the movable portion M is supported in the radial direction at two points of the needle 20, that is, the portion facing the inner wall surface 11c of the nozzle hole body 11 (the needle tip portion), and the outer peripheral surface 51d of the cup 50. On the other hand, the movable portion M may be supported from the radial direction at two positions, that is, the outer peripheral surface of the movable core 30 and the needle tip portion.
In the first embodiment, the inner core 32 is made of a nonmagnetic material, but may be made of a magnetic material. When the inner core 32 is made of a magnetic material, the inner core 32 may be made of a weak magnetic material that is weaker in magnetism than the outer core 31. Similarly, the needle 20 and the guide member 60 may be made of a weak magnetic material that is weaker than the outer core 31.
In the first embodiment, the cup 50 is interposed between the first spring member SP1 and the movable core 30 in order to realize a core boost structure in which the movable core 30 contacts the needle 20 to start the valve opening operation when the movable core 30 moves by a predetermined distance. On the other hand, the cup 50 may be eliminated, and a core boost structure in which a third spring member different from the first spring member SP1 is provided, and the movable core 30 is urged toward the nozzle hole by the third spring member may be employed.
In the first embodiment, in order to avoid a magnetic short circuit between the fixed core 13 and the main body 12, the non-magnetic member 14 is disposed between the fixed core 13 and the main body 12. Instead of the non-magnetic member 14, a magnetic member having a shape having a magnetic throttle portion for inhibiting the magnetic short-circuit may be disposed between the fixed core 13 and the main body 12. Alternatively, the non-magnetic member 14 may be eliminated, and a magnetic throttle portion for inhibiting the magnetic short circuit may be formed in the fixed core 13 or the main body 12.
The sleeve 40 according to the first embodiment has a shape in which the connection portion 42 extends on the upper side of the support portion 43 (on the side opposite to the nozzle holes) and the insertion cylindrical portion 41 extends on the upper side of the connection portion 42. On the other hand, the sleeve 40 may have a shape in which the connection portion 42 extends below the support portion 43 (on the nozzle hole side) and the insertion cylindrical portion 41 further extends below the connection portion 42. The sleeve 40 may also be a hollow shaped ring extending annularly around the needle 20. In this instance, the upper surface of the ring supports the second spring member SP2, and the inner peripheral surface of the ring is press-fitted into the press-fit portion 23.
The cup 50 according to the first embodiment has the cup shape having the circular plate portion 52 and the cylindrical portion 51. On the other hand, the cup 50 may have a flat plate shape. In this instance, the upper surface (upper surface) of the flat plate contacts the first spring member SP1, and the lower surface (lower surface) of the flat plate contacts the movable core 30.
The support member 18 according to the first embodiment has the cylindrical shape, but may have a C-shaped cross-sectional shape in which a slit extending in the direction of the axis line C is provided in a cylindrical shape.
The movable core 30 according to the first embodiment has the structure having two parts, that is, the outer core 31 and the inner core 32. The inner core 32 is made of a material having a higher hardness than the outer core 31, and has a surface that contacts the cup 50 and the guide member 60, and a surface that slides with the needle 20. On the other hand, the movable core 30 may have a structure in which the inner core 32 is eliminated.
When the movable core 30 has the structure in which the inner core 32 is eliminated as described above, it is preferable that the contact surface of the movable core 30 that contacts the cup 50 and the guide member 60 and the sliding surface that slides with the needle 20 are plated. One specific example of plating applied to the contact surface is chromium. One specific example of plating applied to the sliding surface is nickel phosphorus.
The fuel injection valve 1 according to the first embodiment has the structure in which the movable core 30 contacts the guide member 60 attached to the fixed core 13. On the other hand, the movable core 30 may contact the fixed core 13 in which the guide member 60 is eliminated. In short, the inner core 32 may contact the guide member 60, or the inner core 32 may contact the fixed core 13 in which the guide member 60 is eliminated. Further, the structure may be applied in which the movable core 30 in which the inner core 32 is abolished contacts the guide member 60, or the structure may be applied in which the movable core 30 in which the inner core 32 is abolished contacts the fixed core 13 in which the guide member 60 is abolished.
In the case where the movable core 30 has the structure in which the inner core 32 is eliminated as described above, the surface of the movable core 30 on the side opposite to the nozzle hole, which contacts the needle 20, corresponds to the first core contact surface 32c. Further, in the case of the structure in which the guide member 60 is eliminated as described above, the surface of the movable core 30 that contacts the fixed core 13 corresponds to the third core contact surface 32d.
In the first embodiment, the communication grooves 32e are provided in the portion of the inner core 32 which contacts the guide member 60. On the other hand, in the case of the structure in which the guide member 60 is eliminated as described above, the communication grooves 32e are provided in the portion of the inner core 32 which contacts the fixed core 13. When the movable core 30 has the structure in which the inner core 32 is eliminated as described above, the communication grooves 32e are provided in the portion of the movable core 30 which contacts the fixed core 13.
The cup 50 according to the first embodiment slides in the direction of the axis line C while contacting the inner peripheral surface of the guide member 60. On the other hand, the cup 50 may be configured to move in the direction of the axis line C while defining a predetermined gap with the inner peripheral surface of the guide member 60.
In the first embodiment, the inner peripheral surface of the second spring member SP2 is guided by the connection portion 42 of the sleeve 40. On the other hand, the outer peripheral surface of the second spring member SP2 may be guided by the outer core 31.
In the first embodiment, one end of the second spring member SP2 is supported by the movable core 30, and the other end of the second spring member SP2 is supported by the sleeve 40 attached to the needle 20. On the other hand, the sleeve 40 may be eliminated, and the other end of the second spring member SP2 may be supported by the main body 12.
While the present disclosure has been described with reference to embodiments thereof, it is to be understood that the disclosure is not limited to the embodiments and constructions. To the contrary, the present disclosure is intended to cover various modification and equivalent arrangements. In addition, while the various elements are shown in various combinations and configurations, which are exemplary, other combinations and configurations, including more, less or only a single element, are also within the spirit and scope of the present disclosure.
Number | Date | Country | Kind |
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JP2017-189883 | Sep 2017 | JP | national |
JP2018-169993 | Sep 2018 | JP | national |
The present application is a continuation application of International Patent Application No. PCT/JP2018/034644 filed on Sep. 19, 2018, which designated the U.S. and claims the benefit of priority from Japanese Patent Application No. 2017-189883 filed on Sep. 29, 2017, and Japanese Patent Application No. 2018-169993 filed on Sep. 11, 2018. The entire disclosures of all of the above applications are incorporated herein by reference.
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20160097358 | Miyake et al. | Apr 2016 | A1 |
20180080420 | Yamamoto et al. | Mar 2018 | A1 |
20190338739 | Matsukawa et al. | Nov 2019 | A1 |
Number | Date | Country |
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10326343 | Dec 2004 | DE |
2013-104340 | May 2013 | JP |
2015232334 | Dec 2015 | JP |
2019065406 | Apr 2019 | WO |
2019065412 | Apr 2019 | WO |
2019065413 | Apr 2019 | WO |
2019065414 | Apr 2019 | WO |
Entry |
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Machine Translation of DE-10326343-A1 Description, Espacenet, May 2022, 8 Pages (Year: 2022). |
Machine Translation of JP-2015232334-A Description, Espacenet, May 2022, 10 Pages (Year: 2022). |
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Number | Date | Country | |
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20200224620 A1 | Jul 2020 | US |
Number | Date | Country | |
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Parent | PCT/JP2018/034644 | Sep 2018 | US |
Child | 16830839 | US |