Patent Application
20230228238
The present invention relates to a prestroke adjustment method for a fuel injection valve that performs a valve opening/closing operation of a valve member by driving a movable element, and relates to a prestroke adjustment method for adjusting a magnitude of a prestroke defined by a gap formed between the valve member and the movable element.
A fuel injection valve used in an internal combustion engine includes a valve member having a valve body in contact with a valve seat, and a movable element relatively displaceable in a valve opening/closing direction with respect to the valve member, and performs a valve opening/closing operation of the valve member by driving the movable element. Among such fuel injection valves, there is known a technique in which a gap forming member (intermediate material) is disposed so as to be able to abut on a valve member (plunger rod) and a movable element (anchor) to form a gap defining a prestroke between the valve member and the movable element in a valve closed state, and the movable element enters (displaces) by a size of the gap without accompanying the valve member, and then engages with an engagement portion of the valve member (after the prestroke) to move the valve member in a valve opening direction (see, for example, PTL 1). The technique aims to improve the responsiveness of the valve opening operation by utilizing the kinetic energy of the movable element stored by approach for the valve opening operation of the valve member.
The fuel injection valve described in PTL 1 includes, in addition to the valve member and the anchor, a fixed core that applies a magnetic attraction force to the anchor to attract the anchor in the valve opening direction, a first spring that biases the valve member in the valve closing direction, and a second spring that biases the anchor in the valve opening direction from the opposite side of the fixed core. Both the anchor and the valve member are provided with an engagement portion that engages with each other when the anchor is displaced in the valve opening direction with respect to the valve member to regulate the displacement of the anchor in the valve opening direction. The anchor is biased in the valve closing direction from the fixed core side by a third spring whose biasing force is smaller than that of the first spring and larger than that of the second spring. When the gap forming member abuts on the anchor in a state of being positioned at the reference position of the valve member, a gap defining a prestroke is formed between the engagement portion on the valve member side and the engagement portion on the anchor side, and the third spring biases the gap forming member in the valve closing direction so as to be positioned at the reference position.
PTL 1: WO 2016/042896
Meanwhile, in a case where the gap defining the prestroke described above is formed excessively small, the kinetic energy of the movable element (anchor) is too low to be used for the valve opening operation, and the valve cannot be opened under a high pressure condition (for example, 25 MPa or more). Conversely, in a case where the gap defining the prestroke is excessively formed, the action of the magnetic attraction force on the movable element becomes weak, and the movable element is not attracted in the valve opening direction and cannot be opened. For this reason, the magnitude (prestroke amount) of the prestroke for improving the responsiveness of the valve opening operation has a narrow allowable range of variation of ±several tens of μm.
In the fuel injection valve described in PTL 1, the gap forming member includes a recess capable of accommodating the engagement portion (flange-shaped stepped portion) of the plunger rod on the end surface side facing the anchor, and the recess opening side of the gap forming member abuts on the anchor in a state where the bottom surface of the recess of the gap forming member is positioned at the engagement portion (reference position) of the plunger rod, whereby a gap defining a prestroke is formed between the engagement portion of the plunger rod and the engagement portion of the anchor. That is, a dimension obtained by subtracting a distance dimension (height dimension) between both stepped portions of the stepped portion of the plunger rod from a depth dimension of the recess of the gap forming member corresponds to the prestroke amount. That is, the prestroke amount is defined by a dimensional difference between two components.
For this reason, it is conceivable to set the dimensional tolerance of each of the single component to ±several μm in order to keep the variation in the prestroke amount within the above-described allowable range. However, it is difficult to manufacture the component with such dimensional tolerances from the viewpoint of machining accuracy and cost of the machine tool. On the other hand, when two components machined with a machining accuracy with a dimensional tolerance larger than ±several pm are arbitrarily assembled, the variation in the prestroke amount may exceed the above-described allowable range.
Therefore, all the dimensions (the depth dimension of the recess of the gap forming member and the interval dimension of the stepped portion of the plunger rod) of a large number of two components processed with a predetermined machining accuracy are actually measured, and the two components are selected and combined so that the variation in the prestroke amount falls within a predetermined allowable range. For this reason, many man-hours are required in order to keep the variation in the prestroke amount within a predetermined allowable range.
The present invention has been made to solve the above problems, and an object of the present invention is to provide a prestroke adjustment method for a fuel injection valve capable of reducing variations in a prestroke amount regardless of the level of machining accuracy of a component.
The present application includes a plurality of means for solving the above problems, and an example thereof is a prestroke adjustment method for adjusting a prestroke amount of a fuel injection valve that includes: a valve member having a valve body at a tip portion, the valve body being capable of seating on and separating from a valve seat; a movable element relatively displaceable in a valve opening/closing direction with respect to the valve member and engageable with the valve member; and a gap forming member configured to be relatively displaceable in a valve opening/closing direction with respect to the valve member and the movable element, the gap forming member forming a gap defining a prestroke between the valve member and an engagement portion of the movable element by a second portion abutting on the movable element in a state where a first portion is positioned at a reference position of the valve member. The gap forming member has an adjustment margin before adjustment of the prestroke amount. A load in a direction from the first portion toward the reference position of the valve member is applied to the gap forming member in a state of being assembled to the valve member. The gap forming member is plastically deformed to reduce a relative length between the first portion and the second portion to set a prestroke amount to a target value.
According to the present invention, by plastically deforming the gap forming member in a state of being assembled to the valve member, the dimensional difference (corresponding to the prestroke amount) at the predetermined position between the two components of the valve member and the gap forming member can be shortened to the target value. Therefore, even if the two components have a large dimensional tolerance due to the machining accuracy, the influence of the dimensional tolerance on the dimensional difference at the predetermined position between the two components after adjustment can be reduced. That is, the variation in the prestroke amount can be reduced regardless of the machining accuracy of the components.
Objects, configurations, and effects besides the above description will be apparent through the explanation on the following embodiments.
Hereinafter, a prestroke adjustment method for a fuel injection valve according to an embodiment of the present invention will be described with reference to the drawings. An example in which the stroke adjustment method of the present embodiment is applied to an electromagnetic fuel injection valve that electromagnetically drives a valve member has been described.
First, a configuration of a fuel injection valve to which a prestroke adjustment method according to a first embodiment of the present invention is applied will be described with reference to
In
The fuel introduction mechanism 10 includes a fuel pipe 11 extending along the central axis C and having an inside constituting a part of a fuel passage, and a filter 12 disposed inside the fuel pipe 11. The fuel pipe 11 has a fuel introduction port 11a into which fuel is introduced at one end portion (in
The nozzle mechanism 20 includes a nozzle member 21 having a fuel injection hole 21a (see also
The nozzle member 21 is inserted and fixed inside the tip portion of the small-diameter cylindrical portion 23. The nozzle member 21 is formed of, for example, a member called an orifice cup formed in a cup shape, and has a conical valve seat 21b (see also
The valve member 30 is disposed inside the nozzle holder 22 so as to be movable in a contacting/separating direction (in
The electromagnetic drive mechanism 40 includes a fixed core 41 attached to the opening of the large-diameter cylindrical portion 24 of the nozzle holder 22, a movable core 42 movably disposed inside the large-diameter cylindrical portion 24, an annular or tubular electromagnetic coil 43 disposed on the outer peripheral sides of the fixed core 41 and the large-diameter cylindrical portion 24, and a housing 44 surrounding the outer peripheral portions of the large-diameter cylindrical portion 24 and the electromagnetic coil 43 and functioning as a yoke. An annular magnetic passage surrounding the electromagnetic coil 43 is formed by the large-diameter cylindrical portion 24 of the nozzle holder 22, the fixed core 41, the movable core 42, and the housing 44.
An outer peripheral portion of one end portion (in
The movable core 42 is located closer to the nozzle member 21 than the fixed core 41, and is a member (movable element) attracted toward the fixed core 41 by the action of a magnetic attraction force. The outer peripheral surface of the movable core 42 slides on the inner peripheral surface of the large-diameter cylindrical portion 24 of the nozzle holder 22, so that the movement is guided in the valve opening/closing direction (the extending direction of the large-diameter cylindrical portion 24). That is, the large-diameter cylindrical portion 24 functions as a guide that guides the movement of the movable core 42. The movable core 42 has an insertion hole 421 into which the valve rod portion 31 of the valve member 30 can be inserted at the central portion, and is configured to be movable relative to the valve member 30. That is, the movable core 42 is configured such that the inner peripheral surface forming the insertion hole 421 is slidable with respect to the outer peripheral surface of the valve rod portion 31, and has a guide function of guiding the movement of the valve member 30. The movable core 42 has a through hole 422 constituting a fuel passage around the insertion hole 421. The movable core 42 is configured to be engaged with the flange portion 33 of the valve member 30 from the valve body 32 side (in
The electromagnetic coil 43 is wound around an annular bobbin 46 having a U-shaped cross section and opening radially outward. A conductor portion 47 having high rigidity is attached to both end portions of the electromagnetic coil 43. The conductor portion 47 is drawn out from a hole 45a provided in the space of the missing portion of the core member 45 fitted to the outer periphery of the fixed core 41.
The housing 44 is formed in a tubular shape, and is fitted in a state where the large-diameter cylindrical portion 24 of the nozzle holder 22 is located inside. Inside the housing 44, most of the fixed core 41 and the electromagnetic coil 43 are disposed with a gap from the inner peripheral surface of the housing 44. The housing 44 constitutes a part of the outer shell of the fuel injection valve 1 together with the small-diameter cylindrical portion 23 of the nozzle holder 22.
The outer peripheral sides of the portions of the electromagnetic coil 43, the fixed core 41, and the fuel pipe 11 on the fixed core 41 side are covered with a resin cover 48. The resin cover 48 is molded by injecting an insulating resin from an opening of the housing 44 on the fuel introduction port 11a side. The resin cover 48 includes a connector 48a connectable to a plug for supplying power from a high-voltage power supply or a battery power supply. The conductor portion 47 is mostly embedded in the resin cover 48, but is partially exposed at the connector 48a.
In the large-diameter cylindrical portion 24 of the nozzle holder 22, the gap forming member 50 is disposed so as to be able to abut on the flange portion 33 (engagement portion) of the valve member 30 and the movable core 42 and to be relatively movable in the valve opening/closing direction (extending direction of the central axis C) with respect to the valve member 30 and the movable core 42. The gap forming member 50 is a member that forms a gap between the flange portion 33 (engagement portion) of the valve member 30 and the movable core 42 in the valve closed state in the valve opening/closing direction (extending direction of the central axis C) that defines the prestroke. The prestroke indicates that the movable core 42 moves in the valve opening direction while the valve body 32 of the valve member 30 remains in the valve closed state at the time of the valve opening operation. Details of the structure of the gap forming member 50 will be described later.
Inside the through hole 41a of the fixed core 41, the first biasing spring 61 is disposed at a position closer to the fuel introduction port 11a than the valve member 30 (in
Inside the large-diameter cylindrical portion 24 of the nozzle holder 22, a second biasing spring 62 is disposed at a position closer to the nozzle member 21 than the movable core 42. The second biasing spring 62 biases the valve member 30 in the valve opening direction (in
The third biasing spring 63 is disposed between the cap 36 and the gap forming member 50. The third biasing spring 63 biases the gap forming member 50 toward the movable core 42. The third biasing spring 63 has one end portion (in
The above-described three biasing springs 61, 62, and 63 are a first biasing spring 61, a third biasing spring 63, and a second biasing spring 62 in descending order of biasing force.
Next, the structure of each member (valve member to which a cap is attached, movable core, and gap forming member) constituting the movable portion of the fuel injection valve will be described in detail with reference to
In
The cap 36 attached to the valve member 30 can be disposed inside the through hole 41a of the fixed core 41. The cap 36 includes, for example, a cylindrical portion 37 fitted with the protrusion 34, and a bottom 38 that closes the opening of the cylindrical portion 37 on the fuel introduction port 11a (see
A first outer surface 38c of the bottom 38 of the cap 36 facing the fuel introduction port 11a side (in
The movable core 42 has a first end surface 42a (in
In a central portion of the movable core 42 on the first end surface 42a side, for example, a recess 423 opened to the fixed core 41 side is formed. The recess 423 has an inner diameter and a height capable of housing the entire flange portion 33 of the valve member 30 and the entire gap forming member 50. A bottom surface 423a of the recess 423 is a portion that can be engaged with the engagement surface 33a (in
The insertion hole 421 of the movable core 42 is a hole penetrating from the bottom surface 423a to the second end surface 42b of the recess 423. A hole diameter of the insertion hole 421 is smaller than an outer diameter of the flange portion 33 of the valve rod portion 31, and is set to a size that allows the valve rod portion 31 to slide. That is, the inner peripheral surface forming the insertion hole 421 of the movable core 42 constitutes a sliding surface that slides relative to the outer peripheral surface of the valve rod portion 31. When the bottom surface 423a of the recess 423 is engaged with the engagement surface 33a of the flange portion 33 of the valve member 30, the movable core 42 moves in cooperation with the valve member 30 at the time of the valve opening operation for shifting from the valve closed state to the valve open state or at the time of the valve closing operation for shifting from the valve open state to the valve closed state. When the force for moving the movable core 42 downward or the force for moving the valve member 30 upward acts independently, the movable core 42 moves so as to be relatively displaced with respect to the valve member 30.
The gap forming member 50 is a bottomed cylindrical body having an internal space 50a that can accommodate the entire flange portion 33 of the valve member 30 as an engagement portion with respect to the movable core 42. The gap forming member 50 includes a bottom 51 having a bottom surface 51a that can be brought into contact with the contact surface 33b (in
The internal space of the gap forming member 50 is formed such that a height Hs (a length dimension from the bottom surface 51a to the opening side tip of the peripheral wall portion 52) is larger than a height Hc of the flange portion 33 (a length dimension between the engagement surface 33a and the contact surface 33b of the flange portion 33), and an inner diameter thereof (an inner diameter of the peripheral wall portion 52) is larger than an outer diameter of the flange portion 33. The gap forming member 50 is configured such that the opening side end portion 52a (contact portion) of the peripheral wall portion 52 abuts on the movable core 42 in a state of being positioned on the contact surface 33b (reference position) of the flange portion 33 of the valve member 30, thereby forming a gap G2 defining the prestroke between the engagement surface 33a (engagement portion) of the flange portion 33 of the valve member 30 and the bottom surface 423a (engagement portion) of the recess 423 of the movable core 42. That is, the magnitude of the prestroke (prestroke amount) is a dimension D2 obtained by subtracting the height dimension Hc of the flange portion 33 from the height dimension Hs of the internal space 50a of the gap forming member 50. When the movable core 42 is displaced from the state illustrated in
As illustrated in
The end surface 41b (collision surface) of the fixed core 41, the first end surface (collision surface) 42a of the movable core 42, the bottom surface 51a of the gap forming member 50, the engagement surface 33a of the flange portion 33 of the valve member 30, and the contact surface 33b may be plated in order to improve durability. For example, when relatively soft magnetic stainless steel is used for the movable core 42, durability and reliability can be secured by using hard chromium plating or electroless nickel plating.
However, the collision force at the contact portions 423a and 52a between the movable core 42 and the gap forming member 50 and the contact portions 33b and 51a between the flange portion 33 of the valve member 30 and the gap forming member 50 is considerably smaller than the collision force at the collision surfaces 41b and 42a between the fixed core 41 and the movable core 42. Therefore, the necessity of plating at the contact portions 423a and 52a between the movable core 42 and the gap forming member 50 and the contact portions 33b and 51a between the flange portion 33 of the valve member 30 and the gap forming member 50 is significantly smaller than the necessity of plating at the collision surfaces 41b and 42a between the fixed core 41 and the movable core 42.
When plating is applied to the contact portions 423a and 52a between the movable core 42 and the gap forming member 50 and the contact portions 33b and 51a between the flange portion 33 of the valve member 30 and the gap forming member 50, the prestroke amount is determined based on the dimension including the thickness of the plating.
The stroke adjustment of the movable portion including the valve member 30 and the movable core 42 is as follows. The movable core 42 is disposed in the large-diameter cylindrical portion 24 of the nozzle holder 22, and the electromagnetic coil 43 and the housing 44 are attached to the outer periphery of the large-diameter cylindrical portion 24. After the gap forming member 50 and the third biasing spring 63 are assembled to the protrusion 34 side of the valve member 30 in this order, the cap 36 is press-fitted into the protrusion 34 of the valve member 30. Next, the valve member 30 to which the member is assembled is inserted into the through hole 41a of the fixed core 41, and the valve rod portion 31 of the valve member 30 is inserted into the movable core 42. Then, the first biasing spring 61 and the adjuster 64 are attached to the through hole 41a of the fixed core 41 in this order. In this state, the valve member 30 is pressed to the valve closing position by a jig, and the press-fitting position of the nozzle member 21 is determined while the stroke of the valve member 30 is detected when the electromagnetic coil 43 is energized. Thus, the stroke of the movable core 42 is adjusted. For example, in a state where the initial load of the first biasing spring 61 is adjusted, the end surface 41b of the fixed core 41 is adjusted to face the first end surface 42a of the movable core 42 with the magnetic attraction gap G1 of about 70 to 150 μm interposed between them.
Next, a valve opening operation of the fuel injection valve to which the prestroke adjustment method according to the first embodiment of the present invention is applied will be described with reference to
A drive current is supplied to the electromagnetic coil 43 illustrated in
In a state where the electromagnetic coil 43 is not energized, as illustrated in
At this time, the movable core 42 is stationary in a state where the bottom surface 423a of the recess 423 abuts on the tip portion 52a on the opening side of the peripheral wall portion 52 of the gap forming member 50. This state is referred to as a valve closed stationary state. In the valve closed stationary state, a gap G1 exists between the first end surface 42a (collision surface) of the movable core 42 and the end surface 41b (collision surface) of the fixed core 41. On the other hand, in the gap forming member 50, the tip portion 52a of the peripheral wall portion 52 is in contact with the bottom surface 423a of the recess 423 of the movable core 42, and the bottom surface 51a of the bottom 51 is in contact with the contact surface 33b of the flange portion 33 of the valve member 30. Therefore, a gap G2 exists between the engagement surface 33a of the flange portion 33 of the valve member 30 and the bottom surface 423a of the recess 423 of the movable core 42. At this time, the size (dimension) of the gap G1 is D1 (G1=D1), and the size (dimension) of the gap G2 is D2 (G2=D2). The magnitude (prestroke amount) of the prestroke is defined by the size (dimension) of the gap G2 between the engagement portion of the valve member 30 (the engagement surface 33a of the flange portion 33) and the engagement portion of the movable core 42 (the bottom surface 423a of the recess 423) in a state where the gap forming member 50 is positioned at the reference position of the valve member 30 (the contact surface 33b of the flange portion 33) and abuts on the movable core 42. Therefore, the size D2 of the gap G2 is the prestroke amount. Since the bottom surface 51a of the gap forming member 50 and the contact surface 33b of the flange portion 33 of the valve member 30 are in contact with each other, the size (dimension) of a gap G3 between the bottom surface 51a of the gap forming member 50 and the contact surface 33b of the flange portion 33 of the valve member 30 is 0.
When energization of the electromagnetic coil 43 illustrated in
In
That is, the size (dimension) of the gap G2 between the engagement portion (bottom surface 423a) of the movable core 42 and the engagement portion (engagement surface 33a of the flange portion 33) of the valve member 30 is 0 (G2=0). At this time, the movable core 42 is engaged with the flange portion 33 of the valve member 30 with a certain speed by displacing the approach distance corresponding to the size of the gap G2 in the valve closed stationary state without accompanying the valve member 30. Since the gap G2 in the valve closed stationary state has the necessary prestroke amount D2, the valve member 30 can be quickly lifted when the movable core 42 is engaged with the flange portion 33 of the valve member 30, and as a result, the valve opening operation of the valve body 32 is quickly started.
The gap G3 is formed between the bottom surface 51a of the gap forming member 50 and the contact surface 33b of the flange portion 33 of the valve member 30 by the gap forming member 50 being displaced toward the fixed core 41 as the movable core 42 is displaced toward the fixed core 41. At this time, in a state where the tip portion 52a of the peripheral wall portion 52 of the gap forming member 50 on the opening side and the bottom surface 423a of the movable core 42 are in contact with each other, the bottom surface 423a of the movable core 42 is engaged with the engagement surface 33a of the flange portion 33 of the valve member 30, and thus, the size (dimension) of the gap G3 is D2 which is the same as the prestroke amount (G3=D2). The prestroke amount matches to a dimension obtained by subtracting the height dimension Hc of the flange portion 33 of the valve member 30 from the height dimension Hs of the internal space 50a of the gap forming member 50. That is, the prestroke amount corresponds to a size (dimension) in which the valve member 30 and the movable core 42 can be relatively displaced in a state where the tip portion 52a of the peripheral wall portion 52 of the gap forming member 50 on the opening side is in contact with the bottom surface 423a of the movable core 42.
As the movable core 42 is displaced toward the fixed core 41, the size of the gap G1 between the first end surface 42a of the movable core 42 and the end surface 41b of the fixed core 41 is reduced accordingly. The size (dimension) of the gap G1 is D3 which is a size obtained by subtracting the prestroke amount D2 from D1 in the valve closed stationary state (G1=D3<D1).
When the movable core 42 is engaged with the flange portion 33 of the valve member 30, the propulsion force of the movable core 42 in the valve opening direction is larger than the biasing force of the first biasing spring 61 by the magnetic attraction force generated by the energization of the electromagnetic coil 43 and the kinetic energy of the movable core 42 by the acceleration corresponding to the approach distance of the prestroke amount D2. Therefore, as illustrated in
Thereafter, the valve member 30 is further displaced in a direction away from the movable core 42 by the kinetic energy of the valve member 30. That is, the engagement between the engagement portion of the valve member 30 (the engagement surface 33a of the flange portion 33) and the engagement portion of the movable core 42 (the bottom surface 423a of the recess 423) is released. Therefore, the valve open state of the valve member 30 is maintained.
As described above, in the fuel injection valve 1, in a state where the gap forming member 50 is positioned at the reference position of the valve member 30 and abuts on the movable core 42, the gap G2 is formed between the engagement portion of the flange portion 33 of the valve member 30 (the engagement surface 33a of the flange portion 33) and the engagement portion of the movable core 42 (the bottom surface 423a of the recess 423). This gap G2 defines the prestroke. Since the fuel injection valve 1 includes the prestroke, the movable core 42 can acquire kinetic energy by the approach by the prestroke amount before being engaged with the valve member 30. As a result, when the movable core 42 is engaged with the valve member 30, the movable core 42 can quickly lift the valve member 30, so that a quick valve opening operation of the valve body 32 can be performed, and the responsiveness of the valve opening operation is improved.
When the prestroke amount is too small, the kinetic energy of the movable core 42 is too low to be used for the valve opening operation, and the valve cannot be opened under a high pressure condition (for example, 25 MPa or more). Conversely, when the prestroke amount is excessive, the action of the magnetic attraction force on the movable core 42 becomes weak, the movable core 42 is not attracted toward the fixed core 41, and the valve cannot be opened. For this reason, the allowable range of the variation in the prestroke amount is narrowed to ±several tens of μm.
As described above, the prestroke amount is defined by the dimensional difference between the two components of the gap forming member 50 and the valve member 30. More specifically, a size obtained by subtracting the height dimension Hc of the flange portion 33 of the valve member 30 from the height dimension Hs of the internal space 50a of the gap forming member 50 corresponds to the prestroke amount D2.
For this reason, it is conceivable to set the dimensional tolerance of each of the components 30 and 50 to ±several μm in order to keep the variation in the prestroke amount within the above-described allowable range. However, it is difficult to manufacture the components 30 and 50 with such dimensional tolerances from the viewpoint of machining accuracy and cost of the machine tool. On the other hand, when the two components 30 and 50 machined with machining accuracy lower than ±several μm are arbitrarily assembled, the variation in the prestroke amount may exceed the above-described allowable range. Therefore, it is conceivable to actually measure all the dimensions of the large number of two components 30 and 50, and select and combine the two components 30 and 50 so that the variation in the prestroke amount falls within the allowable range. However, in this case, many man-hours are required, and there is a problem that the cost increases.
Therefore, in the prestroke adjustment method of the fuel injection valve 1 according to the present embodiment, the variation in the prestroke amount defined by the dimensional difference between the two components of the gap forming member 50 and the valve member 30 can be kept within a predetermined allowable range without being affected by the machining accuracy of the components 30 and 50.
Next, a prestroke adjustment method of the fuel injection valve according to the first embodiment of the present invention will be described with reference to
In the prestroke adjustment method for the fuel injection valve 1 according to the present embodiment, the prestroke amount D2 (see
First, the gap forming member 50 has an adjustment margin A1 before the adjustment of the prestroke amount. That is, a gap forming member 50M (an intermediate material having a predetermined portion larger in dimension than the gap forming member 50 as a final component after the prestroke adjustment) having the adjustment margin A1 and the valve member 30 having no adjustment margin as a final component are prepared. The valve member 30 and the gap forming member 50M as an intermediate material are processed with predetermined machining accuracy. The machining accuracy may be low. At this time, both the valve member 30 and the gap forming member 50M as an intermediate material have variations in component dimensions due to machining accuracy.
In
The prestroke amount D2(b) before adjustment is finally set to the target value T2 from T1. Therefore, the height Hs(b) of the internal space 50a of the gap forming member 50M as an intermediate material is set such that the prestroke amount D2(b) before adjustment becomes a value obtained by adding the adjustment margin A1 to the target value T2. At this time, the dimensions of the processed valve member 30 and the gap forming member 50M as an intermediate material have dimensional tolerances due to machining accuracy. That is, D2(b)=T1±α=T2+A1±α. Finally, by plastically deforming the gap forming member 50M, the height dimension Hs(b) of the internal space 50a before adjustment is shortened by the adjustment margin A1, so that the prestroke amount D2 is set to the target value T2.
Secondly, as illustrated in
The first jig 100 has an insertion hole 101 through which the valve rod portion 31 of the valve member 30 can be inserted. The diameter of the insertion hole 101 is set to be smaller than the outer diameter of the flange portion 33 of the valve member 30 and slightly larger than the valve rod portion 31.
The first jig 100 has an annular contact surface 102 abutting on the engagement surface 33a of the flange portion 33 of the valve member 30 at the opening edge portion of the insertion hole 101, and has a first pressing surface 103 on which the tip portion 52a of the peripheral wall portion 52 of the gap forming member 50 abuts on the outer peripheral side of the contact surface 102. The contact surface 102 is formed at a position higher than the first pressing surface 103 by the target value T2 of the prestroke amount D2. That is, the contact surface 102 forms a step S1 having a height corresponding to the target value T2 of the prestroke amount D2 with respect to the first pressing surface 103. The area of the contact surface 102 on which the engagement surface 33a of the flange portion 33 of the valve member 30 abuts is set to such a size that stress causing plastic deformation of the flange portion 33 due to application of a load described later is not generated. The prestroke adjustment method according to the present embodiment does not plastically deform the flange portion 33 of the valve member 30.
The dimensional accuracy of the step S1 of the first jig 100 is strictly controlled with high accuracy, and is higher than the dimensional tolerance of the valve member 30 and the gap forming member 50M as an intermediate material. Therefore, the error in the height dimension of the step S1 with respect to the first pressing surface 103 of the contact surface 102 is negligible as compared with the dimensional tolerance of the valve member 30 and the gap forming member 50M as an intermediate material. That is, S1=T2. The height dimension of the step S1 forms a prestroke corresponding to a dimensional difference between the two components.
The contact surface 102 and the first pressing surface 103 are connected by a first tapered portion 104. The connection portion between the first tapered portion 104 and the first pressing surface 103 is located inside the inner peripheral surface of the peripheral wall portion 52 of the gap forming member 50M as an intermediate material. The inner peripheral surface forming the insertion hole 101 and the contact surface 102 are connected by a second tapered portion 105. The second tapered portion 105 has a function of guiding insertion of the valve body 32 and the valve rod portion 31 of the valve member 30 into the insertion hole 101.
The second jig 110 has a fitting hole 111 into which the inclination regulating portion 54 of the gap forming member 50M as an intermediate material can be inserted. The diameter of the fitting hole 111 is set to be smaller than the outer diameter of the peripheral wall portion 52 of the gap forming member 50M as an intermediate material and slightly larger than the outer diameter of the inclination regulating portion 54. The second jig 110 has a second pressing surface 113 in contact with the outer surface 51b of the bottom 51 of the gap forming member 50M as an intermediate material.
With respect to the first jig 100 having such a configuration, the valve rod portion 31 of the valve member 30 is inserted into the insertion hole 101, and the engagement surface 33a of the flange portion 33 of the valve member 30 is brought into contact with the contact surface 102 of the stepped portion. At this time, in the gap forming member 50M as an intermediate material assembled to the valve member 30, the tip portion 52a on the opening side of the peripheral wall portion 52 abuts on the first pressing surface.
As described above, in a state where the valve member 30 and the gap forming member 50M as an intermediate material are set in the first jig 100, a gap G4 is formed between the bottom surface 51a of the gap forming member 50M as an intermediate material and the contact surface 33b of the flange portion 33 of the valve member 30. The size of the gap G4 corresponds to the adjustment margin A1 of the prestroke (G4=A1).
Third, as shown in
Specifically, the gap forming member 50 (peripheral wall portion 52) is plastically deformed until the bottom surface 51a of the internal space 50a of the gap forming member 50 comes into contact with the contact surface 33b of the flange portion 33 of the valve member 30. As a result, the size of the gap G4 between the bottom surface 51a of the gap forming member 50 and the contact surface 33b of the flange portion 33 becomes 0 from the adjustment margin A1 (G4=0). On the other hand, since the first jig 100 is not deformed, the size of the step S1 of the contact surface 102 of the first jig 100 with respect to the first pressing surface 103 is unchanged at the target value T2 of the prestroke amount. As a result, the height dimension Hs(a) of the internal space 50a after adjustment is shortened by the adjustment margin A1 from the height dimension Hs(b) of the internal space 50a before adjustment. Therefore, the prestroke amount D2(a) corresponding to a dimension obtained by subtracting the height dimension Hc of the flange portion 33 of the valve member 30 from the height dimension Hs(a) of the internal space 50a of the gap forming member 50 becomes the target value T2.
At this time, since the peripheral wall portion 52 of the gap forming member 50 expands in the radial direction by plastic deformation, the inner diameter of the peripheral wall portion 52 is larger than the inner diameter of the gap forming member 50M as an intermediate material. The tip portion 52a of the peripheral wall portion 52 of the gap forming member 50 on the opening side is pressed against the first pressing surface 103 of the first jig 100 and plastically deformed, whereby the tool mark is crushed. As a result, the surface roughness of the tip portion 52a of the gap forming member 50 is improved, and the durability is improved since the tip portion is machined and hardened by plastic deformation.
Depending on the machining accuracy of the gap forming member 50 and the valve member 30, the bottom surface 51a of the gap forming member 50 may be formed in a state of being somewhat inclined with respect to the contact surface 33b of the flange portion 33 of the valve member 30. However, in the present embodiment, since the gap forming member 50M as an intermediate material is plastically deformed until the bottom surface 51a of the gap forming member 50 abuts on the contact surface 33b of the flange portion 33 of the valve member 30, the contact portion of the contact surface 33b of the flange portion 33 in the bottom surface 51a of the gap forming member 50 after plastic deformation is in a deformed state following the shape of the contact surface 33b. Therefore, the collision area between the bottom surface 51a of the gap forming member 50 and the contact surface 33b of the flange portion 33 of the valve member 30 can be maximized. As a result, it is possible to reduce the stress at the time of collision between both components generated on the bottom surface 51a of the gap forming member 50 and the flange portion 33 of the valve member 30, and the durability of both components 30 and 50 is improved.
As described above, the prestroke adjustment method of the fuel injection valve 1 according to the first embodiment of the present invention is to adjust the prestroke amount D2 of the fuel injection valve 1 which includes the valve member 30 having the valve body 32 at the tip portion which can be seated on and separated from the valve seat 21b, the movable core 42 (movable element) that can be relatively displaced in the valve opening/closing direction with respect to the valve member 30 and can be engaged with the valve member 30, and the gap forming member 50 that is configured to be relatively displaceable in the valve opening/closing direction with respect to the valve member 30 and the movable core 42 (movable element) and forms the gap G2 defining a prestroke between the engagement portion 33a and 423a of the valve member 30 and the movable core 42 (movable element) by the second portion 52a in contact with the movable core 42 (movable element) in a state where the first portion 51a is positioned at the reference position 33b of the valve member 30. The gap forming member 50 has the adjustment margin A1 before the adjustment of the prestroke amount D2. In the prestroke adjustment method, the load L in a direction from the first portion 51a toward the reference position 33b of the valve member 30 is applied to the gap forming member 50 in a state of being assembled to the valve member 30, and the gap forming member 50 is plastically deformed, so that a relative length (height dimension Hs of the internal space) between the first portion 51a and the second portion 52a is shortened, and the prestroke amount D2 is set to the target value T2.
According to this method, by plastically deforming the gap forming member 50 assembled to the valve member 30, the dimensional difference (corresponding to the prestroke amount) at the predetermined position between the two components of the valve member 30 and the gap forming member 50 can be shortened to the target value T2. Therefore, even if the two components 30 and 50 have a large dimensional tolerance due to the machining accuracy, the influence of the dimensional tolerance on the dimensional difference at the predetermined position between the two components 30 and 50 after adjustment can be reduced. That is, the variation in the prestroke amount D2 can be reduced regardless of the machining accuracy of the components 30 and 50.
In the prestroke adjustment method according to the present embodiment, the load L is applied to the gap forming member 50 by sandwiching the gap forming member 50 assembled to the valve member 30 between the first jig 100 and the second jig 110.
According to this method, it is possible to adjust the dimensional difference (corresponding to the prestroke amount D2) at a predetermined position between the two components 30 and 50 only by simply sandwiching the two components of the valve member 30 and the gap forming member 50 by the two jigs 100 and 110 without following a complicated procedure. Therefore, the adjustment of the prestroke amount D2 can be easily executed.
In the prestroke adjustment method according to the present embodiment, the first jig 100 has the contact surface 102 on which the engagement surface 33a (the engagement portion or the first side portion) of the flange portion 33 of the valve member 30 abuts and the first pressing surface 103 on which the opening side end portion 52a (the second portion) of the gap forming member 50 abuts. The contact surface 102 forms a step S1 having a height corresponding to the target value T2 of the prestroke amount with respect to the first pressing surface 103. The plastic deformation of the gap forming member 50 is performed until the bottom surface 51a (first portion) of the gap forming member 50 comes into contact with the contact surface 33b (the reference position or the second side portion) of the flange portion 33 of the valve member 30 in a state where the engagement surface 33a (the engagement portion or the first side portion) of the flange portion 33 of the valve member 30 is in contact with the contact surface 102 of the first jig 100 and in a state where the opening side end portion 52a (second portion) of the gap forming member 50 is in contact with the first pressing surface 103 of the first jig 100.
According to this method, by only plastically deforming the gap forming member 50 until the bottom surface 51a (first portion) of the gap forming member 50 comes into contact with the contact surface 33b (the reference position or the second side portion) of the flange portion 33 of the valve member 30, a gap having a height of the step S1 of the first jig can be formed between the opening side end portion 52a (second portion) of the gap forming member 50 and the engagement surface 33a (the engagement portion or the first side portion) of the flange portion 33 of the valve member 30. Therefore, it is possible to adjust the prestroke amount D2 according to the accuracy of the height dimension of the step S1 of the first jig without being affected by the machining accuracy of the two components of the gap forming member 50 and the valve member 30. Therefore, it is possible to easily reduce the variation in the prestroke amount D2 without being affected by the machining accuracy of the components 30 and 50.
In the fuel injection valve 1 using the prestroke adjustment method of the present embodiment, the valve member 30 includes the valve rod portion 31 in which the valve body 32 is provided at one end portion and extends in the valve opening/closing direction, and the flange portion 33 provided at the other end portion of the valve rod portion 31 and protruding radially outward from the valve rod portion 31. In the flange portion 33, the engagement surface 33a (first side portion) facing the valve body 32 side constitutes an engagement portion with respect to the movable core 42 (movable element), and the contact surface 33b (second side portion) facing the opposite side to the valve body 32 side constitutes a reference position. The gap forming member 50 has the internal space 50a capable of accommodating the flange portion 33, and is a bottomed cylindrical body opened to the movable core 42 (movable element) side. The height dimension Hs from the bottom surface 51a of the internal space 50a of the gap forming member 50 to the opening end is set to be larger than the height dimension Hc from the engagement surface 33a (first side portion) of the flange portion 33 to the contact surface 33b (second side portion). In the gap forming member 50, the bottom surface 51a constitutes the first portion, and the opening side end portion 52a constitutes the second portion. The plastic deformation of the gap forming member 50 is performed until the bottom surface 51a of the gap forming member 50 comes into contact with the contact surface 33b (second side portion) of the flange portion 33 in a state where the gap forming member 50 and the valve member 30 are arranged such that the dimensional difference between the opening side end portion 52a of the gap forming member 50 and the engagement surface 33a (first side portion) of the flange portion 33 of the valve member 30 becomes the target value T2 of the prestroke amount D2.
According to this configuration, by only plastically deforming the gap forming member 50 until the bottom surface 51a of the gap forming member 50 comes into contact with the contact surface 33b of the flange portion 33 of the valve member 30, the dimensional difference (corresponding to the prestroke amount D2) between the opening side end portion 52a of the gap forming member 50 and the engagement surface 33a of the flange portion 33 of the valve member 30 can be set to the target value T2. Therefore, the prestroke amount D2 can be adjusted to the target value without being affected by the machining accuracy of the two components of the gap forming member 50 and the valve member 30. Therefore, it is possible to easily reduce the variation in the prestroke amount D2 without being affected by the machining accuracy of the components 30 and 50.
In the prestroke adjustment method according to the present embodiment, the first jig 100 has the insertion hole 101 through which the valve body 32 and the valve rod portion 31 of the valve member 30 can be inserted, and the contact surface 102 of the first jig 100 is formed at the opening edge portion of the insertion hole 101. When the load L is applied to the gap forming member 50, the valve member 30 has the flange portion 33 in contact with the contact surface 102 of the first jig 100 in a state where the valve body 32 and the valve rod portion 31 are inserted into the insertion hole 101 of the first jig 100.
According to this configuration, the valve member 30 can be easily positioned with respect to the first jig 100, and the positional displacement of the valve member 30 and the gap forming member 50 can be suppressed when the load L is applied to the gap forming member 50.
In the prestroke adjustment method according to the present embodiment, the valve member 30 includes the protrusion 34 extending from the flange portion 33 to the opposite side of the valve rod portion 31, and the gap forming member 50 includes the cylindrical inclination regulating portion 54 slidable on the protrusion 34 of the valve member 30. The second jig 110 has the fitting hole 111 into which the inclination regulating portion 54 can be fitted, and has the second pressing surface 113 in contact with the bottom 51 of the gap forming member 50 on the outer peripheral side of the fitting hole 111. The load L is applied to the gap forming member 50 by bringing the second pressing surface 113 of the second jig 110 into contact with the bottom 51 of the gap forming member 50 in a state where the fitting hole 111 of the second jig 110 is fitted to the inclination regulating portion 54 of the gap forming member 50.
According to this configuration, positioning of the second jig 110 with respect to the valve member 30 and the gap forming member 50 becomes easy. Further, when the load L is applied to the gap forming member 50, the inclination of the gap forming member 50 with respect to the valve member 30 is suppressed, so that the load L can be applied to the gap forming member 50 in an appropriate direction, and the prestroke amount D2 can be appropriately adjusted.
In the embodiment described above, the example in which the present stroke adjustment method is applied to the electromagnetic fuel injection valve 1 that electromagnetically drives the valve member 30 has been described. However, the stroke adjustment method can also be applied to a fuel injection valve that drives the valve member 30 by a piezoelectric effect or a magnetostrictive phenomenon.
The present invention is not limited to the above embodiments, but various modifications may be contained. The above-described embodiments have been described in detail for clear understating of the present invention, and are not necessarily limited to those having all the described configurations. Some of the configurations of a certain embodiment may be replaced with the configurations of the other embodiments, and the configurations of the other embodiments may be added to the configurations of a certain embodiment. In addition, some of the configurations of each embodiment may be omitted, replaced with other configurations, and added to other configurations.
For example, in the above-described embodiment, the example of the configuration in which the first end surface 42a of the movable core 42 and the end surface 41b of the fixed core 41 come into contact with each other has been described. However, it is also possible to provide a protrusion on at least one of the first end surface 42a of the movable core 42 and the end surface 41b of the fixed core 41 such that the protrusion of one member and the end surface of the other member or the protrusions of both members abut on each other. In this case, the above-described gap G1 is a gap between both abutting portions of the fixed core 41 and the movable core 42.
In the above-described embodiment, the example of the configuration in which the recess 423 is formed in the movable core 42 has been described. However, the recess 423 may not be formed in the movable core 42. In this case, the first end surface 42a of the movable core 42 is engaged with the engagement surface 33a of the flange portion 33 of the valve member 30, and serves as a contact portion that abuts on the tip portion 52a on the opening side of the peripheral wall portion 52 of the gap forming member 50. Even in this case, the same effects as those of the above-described embodiment can be obtained.
1 fuel injection valve
21
b valve seat
30 valve member
31 valve rod portion
32 valve body
33 flange portion (engagement portion)
33
a engagement surface (engagement portion, first side portion)
33
b contact surface (reference position, second side portion)
34 protrusion
33
b contact surface (reference position)
41 fixed core
42 movable core (movable element)
423
a bottom surface (engagement portion)
50 gap forming member
50
a internal space
51
a bottom surface (first portion)
52
a opening side end portion (second portion)
54 inclination regulating portion
100 first jig
101 insertion hole
102 contact surface
103 first pressing surface
110 second jig
111 fitting hole
113 second pressing surface
G2 gap
Hs height dimension of internal space
Hc height dimension of flange portion
S1 step
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-105611 | Jun 2020 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/004269 | 2/5/2021 | WO |
