Patent Application
20240287954
The present disclosure relates to a solenoid device and an electromagnetic valve for a fuel injection system.
A common rail fuel injection system used in an engine such as a diesel engine includes a fuel pump, a common rail, and fuel injectors. The fuel pump suctions the fuel from a fuel tank, pressurizes the fuel, and supplies the fuel as high-pressure fuel into the common rail. The common rail keeps the high-pressure fuel from the fuel pump at a predetermined pressure. The fuel injectors open and close the injection valves, to inject high-pressure fuel in the common rail into the combustion chamber of the diesel engine.
Such a fuel injector includes, for example, a solenoid device that generates electromagnetic force, by applying an electric current to the coil wound around the core, and an electromagnetic valve having a valve unit made from a magnetic material. Such an electromagnetic valve applies an elastic force to the valve unit to block the fuel channel, for example. While no electromagnetic force is generated by the solenoid device, the valve unit is caused to close the fuel channel by the elastic force. With the electromagnetic force being generated by the solenoid device, the electromagnetic force in the solenoid device pulls the valve unit, and causes the valve unit to separate from the channel, to open the channel.
As a stopper for ensuring a very narrow gap between the valve unit and the solenoid device, so as not to bring the valve unit into contact with the electromagnetic force generating surface of the solenoid device when the valve unit is attracted toward the solenoid device, a configuration that includes a cylindrical sleeve or the like embedded in the core, and in which the valve unit is brought into contact with only this part has been known (see, for example, Patent Literature 1).
In the configuration described in Patent Literature 1, when the valve unit is brought into contact with the sleeve, the impact is applied to the core and other internal parts of the solenoid device via the sleeve, and weakens the force by which the sleeve is fixed, and may cause instability in the lift of the valve unit. Therefore, there has been a demand for a solenoid device with a stopper that is highly shock resistant.
The present disclosure is made in view of the above, and an object of the present disclosure is to provide a solenoid device and an electromagnetic valve for a fuel injection system, having a stopper structure with excellent shock resistance.
A solenoid device according to the present disclosure is configured to drive by electromagnetic force a valve unit in an electromagnetic valve provided to a fuel injection system. The solenoid device includes: a cylindrical core; a coil that is wound around the core; a casing that houses the core and the coil and covers at least one end of the core on one side in an axial direction of a center axis; a terminal fixing member that is disposed between the core and the casing in the axial direction to fix a terminal connected to the coil; and a cylindrical member that is disposed on an inner circumference of the core in a manner of passing through the core and the casing in the axial direction, the cylindrical member having a protrusion that radially protrudes in a direction perpendicular to the axial direction and is held between the casing and the terminal fixing member from both sides in the axial direction, the cylindrical member having an end on another side of the axial direction located at a position that is allowed to come into contact with the valve unit.
An electromagnetic valve for a fuel injection system according to the present disclosure includes: the above-described solenoid device; and a valve unit that is made from a magnetic material, disposed facing an end of the core on the other side in the axial direction, and applied with an elastic force in a direction separating from the core in the axial direction, the valve unit being configured to block and close a passage for fuel by the elastic force when no electromagnetic force is generated by the solenoid device, and to open the passage by being attracted toward the core by the electromagnetic force to a position where the valve unit is brought into contact with the cylindrical member so that the valve unit is separated from the passage, when the electromagnetic force is generated by the solenoid device.
According to the present disclosure, it is possible to provide a solenoid device and an electromagnetic valve for a fuel injection system, having an excellent shock resistance.
An embodiment of a solenoid device and an electromagnetic valve for a fuel injection system according to the present disclosure will now be explained with reference to drawings. The embodiment is not intended to limit the scope of the present invention in any way. Elements in the following embodiments include those that are replaceable and that are easily replaced by those skilled in the art, or those that are substantially the same.
The fuel pump 11 is connected to a fuel tank 14 via a fuel line L11. The fuel pump 11 suctions the fuel stored in the fuel tank 14 via the fuel line L11, and pressurizes the fuel into high-pressure fuel. The fuel pump 11 is connected to the common rail 12 via a high-pressure fuel line L12. The common rail 12 keeps the high-pressure fuel supplied from the fuel pump 11 at a predetermined pressure. The common rail 12 is connected to the fuel injectors 13 via a plurality of (four, in this embodiment) fuel supply lines L13, respectively. Each of the fuel injectors 13 opens and closes the corresponding electromagnetic valve, to inject high-pressure fuel in the common rail 12 into the corresponding cylinder (combustion chamber) of the diesel engine.
The injection unit 20 includes a casing 21 and a piston valve 22. The casing 21 includes a fuel inlet 24, an injection-side channel 25, a control-side channel 26, an injection-side pressure chamber 27, a control-side pressure chamber 28, a cylinder chamber 29, a fuel injection port 30, a fuel discharge port 31, and an electromagnetic-valve-side pressure chamber 32.
The fuel inlet 24 allows the entry of the fuel via the fuel supply line L13. The injection-side channel 25 connects the fuel inlet 24 to the injection-side pressure chamber 27. The control-side channel 26 connects the fuel inlet 24 to the control-side pressure chamber 28.
The injection-side pressure chamber 27 is connected to the fuel injection port 30. The fuel injection port 30 is disposed at the tip end of the casing 21, and discharges the fuel into the corresponding cylinder of the diesel engine.
The control-side pressure chamber 28 is connected to the fuel discharge port 31. The fuel discharge port 31 is disposed at the base end of the casing 21, and is connected to the electromagnetic-valve-side pressure chamber 32. The electromagnetic-valve-side pressure chamber 32 is connected to the electromagnetic valve 40 (a space 46d, which will be described later).
The cylinder chamber 29 is connected to the injection-side pressure chamber 27 and the control-side pressure chamber 28. The piston valve 22 is housed in the cylinder chamber 29. The cylinder chamber 29 is connected to the electromagnetic-valve-side pressure chamber 32 via a channel 29a.
The piston valve 22 is housed inside the cylinder chamber 29, and is provided movably toward the injection-side pressure chamber 27 or toward the control-side pressure chamber 28. The piston valve 22 has a spring seat member 22a, a control-side piston member 22b, a joint member 22c, and a valve 22d. The spring seat member 22a, the control-side piston member 22b, and the joint member 22c are configured as one piece. The spring seat member 22a receives the elastic force of an elastic member 23, which will be described later. The control-side piston member 22b receives the pressure inside the control-side pressure chamber 28. The joint member 22c joins the spring seat member 22a and the control-side piston member 22b. The valve 22d protrudes from the spring seat member 22a toward the tip-end side in the axial direction of the center axis AX. The valve 22d is brought into contact with the spring seat member 22a by the net force of the pressure received from the pressure chambers and the elastic force. The tip end of the valve 22d has a shape enabled to close the fuel injection port 30. The valve 22d receives the pressure of the injection-side pressure chamber 27.
When the pressure inside the injection-side pressure chamber 27 is lower than the net force of the pressure from the control-side pressure chamber 28 and the elastic force of the elastic member 23, the piston valve 22 is pressed toward the injection-side pressure chamber 27. In this configuration, the fuel injection port 30 is closed by the valve 22d. From this configuration, when the pressure inside the injection-side pressure chamber 27 rises to a level higher than the net force of the pressure inside the control-side pressure chamber 28 and the elastic force of the elastic member 23, the piston valve 22 is pressed toward the control-side pressure chamber 28. The valve 22d is then separated from the fuel injection port 30, and the fuel injection port 30 is opened.
The electromagnetic valve 40 includes a solenoid device 41 and a valve unit 42.
The core 43 has a cylindrical portion 43a, a flange 43b, and a side surface 43c. The cylindrical portion 43a has a cylindrical shape, for example. The flange 43b has a disk-like shape, for example, and is disposed on the base-end side of the core 43. The cylindrical portion 43a and the flange 43b are disposed coaxially with the center axis AX of the fuel injector 13.
The side surface 43c has a cylindrical shape surrounding the cylindrical portion 43a. The side surface 43c is radially spaced from the cylindrical portion 43a, and extends toward the tip-end side. The cylindrical portion 43a, the flange 43b, and the side surface 43c are made from a magnetic material. The coil 44 is housed inside the space surrounded by the cylindrical portion 43a, the flange 43b, and the side surface 43c of the core 43. The space inside the core 43, where the coil 44 is disposed, is sealed by a seal member 49. The seal member 49 is made from a resin material, for example. The terminal fixing member 47 is disposed between the core 43 and the casing 45, which will be described later, in the axial direction of the center axis AX, and fixes the terminal 44a connected to the coil 44. The terminal 44a is pulled out to the external, in a manner of passing through the casing 45. The terminal fixing member 47 is made from a resin material, for example.
The coil 44 is disposed in a manner wound around the cylindrical portion 43a. The coil 44 is passed is through the casing 45, which will be described later, and connected to a power supply unit, not illustrated. The solenoid device 41 generates the electromagnetic force by applying electric current to the coil 44.
The core 43 and the coil 44 are housed inside the casing 45. The casing 45 includes a core housing 45a and a holder 45b. The core housing 45a and the holder 45b are configured as one piece made from a non-magnetic material. The core 43, including the coil 44, is housed inside the core housing 45a. The core housing 45a is disposed in a manner covering the flange 43b and the side surface 43c of the core 43. The holder 45b is positioned on the base-end side of the core housing 45a. The holder 45b holds the cylindrical member 46. The holder 45b includes a stepped portion 45d corresponding to a protrusion 46a of the cylindrical member 46, which will be described later. The shape, the dimensions, and the like of the stepped portion 45d are set in such a manner that the holder 45b holds the protrusion 46a in complete in contact with the protrusion 46a.
The cylindrical member 46 is housed inside of the holder 45b of the casing 45, and the terminal fixing member 47 and the core 43 are housed inside the core housing 45a. With this, it possible to achieve a structure in which the protrusion 46a is held in a manner nipped between the holder 45b of the casing 45 and the terminal fixing member 47, from both sides in the axial direction of the center axis AX.
The cylindrical member 46 is provided in a manner of passing through the core 43 and the casing 45 in the axial direction of the center axis AX.
The cylindrical member 46 has the protrusion 46a. The protrusion 46a protrudes radially from the outer circumference of the cylindrical member 46, in a direction perpendicular to the axial direction of the center axis AX. The protrusion 46a is held between the holder 45b of the casing 45 and the terminal fixing member 47, from both sides in the axial direction of the center axis AX. In other words, the stepped portion 45d holds the base-end side and the side surface of the protrusion 46a, and the terminal fixing member 47 holds the tip-end side, in the axial direction of the center axis AX. With this structure, axial movements of the cylindrical member 46 along the center axis AX are restricted. Thus, for example, it is possible to suppress a relative sliding movement of the cylindrical member 46 with respect to the inner circumference of the core 43, in the axial direction of the center axis AX. Therefore, it is possible to suppress wearing of the core 43. This structure also prevents entry of the fuel into the worn part of the core 43.
The cylindrical member 46 is disposed at a position where a tip-side end face 46b can be brought into contact with the valve unit 42. In this embodiment, the end face 46b is flush with an end face of the side surface 43c of the core 43 on the tip-end side, and with an end face of the seal member 49 on tip-end side, for example. The cylindrical member 46 may also be disposed at a position where the end face 46b projects out toward the tip-end side, with respect to the tip-end side end face of the side surface 43c and the tip-end side end face of the seal member 49.
A supporting portion 46d is provided along the inner circumference of the cylindrical member 46. The supporting portion 46d has a stepped shape in a cross-sectional view, as a smaller-diameter part of the cylindrical member 46. An elastic member 48 is housed in the cylindrical member 46, inside a space 46e between the end face 46b and the supporting portion 46d. The elastic member 48 is housed inside the space 46e with the base end thereof supported by the supporting portion 46d. The elastic member 48 applies an elastic force to the valve unit 42 in a direction toward the tip-end side in the axial direction of the center axis AX.
The cylindrical member 46 has a connecting portion 46c. The connecting portion 46c is provided in a manner protruding from the holder 45b of the casing 45 toward the base-end side. The connecting portion 46c is connected to an external fuel discharge channel 50. A space 46f is provided on the inner circumference side of the connecting portion 46c. The space 46f is connected to the space 46e via a connecting channel 46g. Therefore, the internal of the cylindrical member 46 is continuous across the tip-end side toward the base-end side. The space 46e of the cylindrical member 46 is connected to the electromagnetic-valve-side pressure chamber 32. Therefore, the cylindrical member 46 functions as a joint for connecting the electromagnetic-valve-side pressure chamber 32 to the external fuel discharge channel 50.
As illustrated in
The stepped portion 42c is provided as a projection projecting toward the solenoid device 41, at the center of the armature 42a. The stepped portion 42c has a shape and dimensions bringing the stepped portion 42c into abutment against the end face 46b of the cylindrical member 46, when the valve unit 42 is retracted toward the solenoid device 41. The stepped portion 42c receives the elastic force of the elastic member 48. The elastic force of the elastic member 48 is transmitted to the armature 42a and the valve 42b via the stepped portion 42c. The armature 42a and the valve 42b receive the elastic force of the elastic member 48, in the direction toward the tip-end side of the axial end of the center axis AX. It is also possible for the stepped portion 42c not be provided.
An operation of the fuel injector 13 having the structure as described above will now be explained. While no current is applied to the coil 44 of the solenoid device 41, no electromagnetic force is generated in the solenoid device 41. At this time, the valve unit 42 is caused to press the valve 42b against the fuel discharge port 31 toward the tip-end side by the elastic force of the elastic member 48. The fuel discharge port 31 is thus kept closed.
While the fuel discharge port 31 is closed, the net force of the pressure received from the control-side pressure chamber 28 and the elastic force of the elastic member 23 is greater than the pressure received from the injection-side pressure chamber 27. As a result, the piston valve 22 blocks and closes the fuel injection port 30.
When a current is applied to the coil 44 of the solenoid device 41, an electromagnetic force is generated in the solenoid device 41.
As the fuel discharge port 31 opens, the pressure inside the control-side pressure chamber 28 drops. When the net force of the pressure received from the control-side pressure chamber 28 and the elastic force of the elastic member 23 becomes smaller than the pressure received from the injection-side pressure chamber 27, the piston valve 22 is caused to move toward the control-side pressure chamber 28. At this time, the valve 22d of the piston valve 22 is then separated from the fuel injection port 30, and the fuel injection port 30 is opened. When the fuel injection port 30 opens, the fuel having passed through the fuel inlet 24 and the injection-side channel 25, and having entered the injection-side pressure chamber 27 is injected from the fuel injection port 30.
During this operation, as the valve unit 42 is attracted toward the core 43, by the electromagnetic force of the solenoid device 41, the stepped portion 42c of the valve unit 42 is brought into contact with the end face 46b of the cylindrical member 46, as illustrated in
When the stepped portion 42c is brought into contact with the end face 46b of the cylindrical member 46, the internal of the solenoid device 41, such as the core 43, receives the impact, via the cylindrical member 46. In the solenoid device 41 according to this embodiment, the protrusion 46a of the cylindrical member 46 is held between the casing 45 and the terminal fixing member 47, from both sides in the axial direction of the center axis AX. Therefore, the casing 45 and the terminal fixing member 47 receive the impact caused when the valve unit 42 is brought into contact with the cylindrical member 46. By the valve unit 42 being brought into contact, the movement of the cylindrical member 46 in the axial direction of the center axis AX is restricted. As a result, sliding movement of the cylindrical member 46 and the core 43 with respect to each other is suppressed, and damages such as wearing of the inner surface of the core 43 are suppressed.
As described above, the solenoid device 41 according to this embodiment is the solenoid device 41 configured to drive the valve unit 42 included in the electromagnetic valve 40 provided to the fuel injection system 10, using electromagnetic force, and includes the core 43 that is cylindrical, the coil 44 that is wound around the core 43, the casing 45 in which the core 43 and the coil 44 are housed, and that covers at least one end of the core 43, the one end being an end in the axial direction of the center axis AX of the core 43, the terminal fixing member 47 that is disposed between the core 43 and the casing 45 in the axial direction, and that fixes the terminal 44a connected to the coil 44, and the cylindrical member 46 that is disposed on an inner circumference of the core 43, in a manner of passing through the core 43 and the casing 45 in the axial direction, and that includes a protrusion 46a protruding in a radial direction perpendicular to the axial direction and held between casing 45 and the terminal fixing member 47 from both sides in the axial direction, and that is disposed at a position where the valve unit 42 is allowed to be brought into contact with the end face 46b.
In this configuration, the protrusion 46a of the cylindrical member 46 is held between the casing 45 and the terminal fixing member 47, from both sides in the axial direction of the center axis AX. This configuration allows the casing 45 and the terminal fixing member 47 to receive the impact caused by the valve unit 42 being brought into contact with the cylindrical member 46. By the valve unit 42 being brought into contact, the movement of the cylindrical member 46 in the axial direction of the center axis AX is restricted. As a result, sliding movement of the cylindrical member 46 and the core 43 with respect to each other is suppressed, and damages such as wearing of the inner surface of the core 43 are suppressed. In this manner, it becomes possible to provide a solenoid device 41 with excellent shock resistance.
In the solenoid device 41 according to this embodiment, the protrusion 46a has mating portions 46h mating with the casing 45 around the axial direction of the center axis AX. With this configuration, a rotation of the cylindrical member 46 around the axial direction of the center axis AX is suppressed. Therefore, it is possible to prevent damages of the core 43 and other parts of the solenoid device 41 more reliably.
In this solenoid device 41, one end of the cylindrical member 46 in the axial direction has a connecting portion 46c to be connected to the external fuel discharge channel 50. With this configuration, the number of parts can be reduced because the portion being brought into contact with the valve unit 42 and the joint connected with the fuel discharge channel 50 are provided on a single member, the cylindrical member 46.
The electromagnetic valve 40 in the fuel injection system 10 according to this embodiment includes the solenoid device 41 described above, and the valve unit 42 that is made from a magnetic material, disposed facing the other end of the core 43 in the axial direction, and applied with an elastic force in the direction separating from the core 43 in the axial direction. The valve unit 42 is caused to block and close a fuel passage by the elastic force when no electromagnetic force is generated by the solenoid device 41, and the valve unit 42 is attracted toward the core 43 by the electromagnetic force to a position where the valve unit 42 is brought into contact with the cylindrical member 46, and is separated from the passage, thereby opening the passage, when the electromagnetic force is generated by the solenoid device 41.
Because this configuration includes the solenoid device 41 capable of suppressing damages of the internal structures, it is possible to achieve an electromagnetic valve 40 with high shock resistance.
In the electromagnetic valve 40 in the fuel injection system 10 according to this embodiment, the cylindrical member 46 includes the supporting portion 46d that supports the elastic member 48 by which an elastic force is applied to the valve unit 42. With this configuration, because the portion brought into contact with the valve unit 42 and the supporting portion 46d of the elastic member 48 are provided on a single member, the cylindrical member 46, it is possible to reduce the number of parts.
The technical scope of the invention is not limited to the embodiment described above, and modifications may be made, as appropriate, within the scope not deviating from the essence of the invention. For example, explained above in the embodiment is an example of a configuration in which the electromagnetic valve 40 is installed in the fuel injector 13 of the fuel injection system 10, but the embodiment is not limited thereto. The electromagnetic valve 40 may also be installed in another part of the fuel injection system 10.
The configurations of the fuel injection system 10 and the fuel pump 11 are not limited to those described above in the embodiment. For example, the number of common rails 12 and the fuel injectors 13, and the position at which the fuel pump 11 is connected may be set as appropriate.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-122275 | Jul 2021 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/026991 | 7/7/2022 | WO |
