JP6800238B2 - Fuel injection device - Google Patents

Description

The present invention relates to a fuel injection device used in an internal combustion engine and mainly injecting fuel.

As a background technique in this technical field, there is Japanese Patent Application Laid-Open No. 2011-137442 (Patent Document 1). In this publication, in the fuel injection nozzle, an intermediate member that slides on both the movable iron core and the valve body and forms a gap in the displacement direction between the movable iron core and the valve body in the valve closed state is provided. As a result, the movable iron core collides with the valve body when the valve is opened, so that the movement time required for opening the injection hole can be shortened, and the relative movement between the movable iron core and the valve becomes possible after the on-off valve. Controllability is improved.

Japanese Unexamined Patent Publication No. 2011-137442

The fuel injection device is required to promote atomization of the spray and stabilize the injection amount. The worsening factor of spray atomization is that the fuel flow velocity becomes slow during the low lift period when the valve body starts to open. A factor that deteriorates the stabilization of the injection amount is that the valve operation converges slowly after the valve is opened. Therefore, it is necessary for the fuel injection device to make the opening steep at the same time and to quickly converge the operation of the valve body after the valve is opened. In Patent Document 1, by providing a gap in the displacement direction between the movable iron core and the valve body, only the movable iron core is operated before the start of energization, and an impact force at the time of collision is applied to the valve body when the valve is opened, resulting in a low lift engine. By providing an intermediate member between the valve bodies of the movable iron core, the relative movement between the valve body and the movable iron core can be made possible, and the injection amount can be stabilized.

However, when the intermediate member continues to be displaced in the valve closing direction after the valve is closed and the injection is performed before returning to the valve closing standby state, a state in which the gap in the displacement direction is small occurs and the valve is opened. There was a problem that the valve behavior was not stable.

Therefore, an object of the present invention is to open a fuel injection device in which the valve body receives an impact force from a movable iron core at the time of valve opening and can shorten the low lift period at the time of valve opening even when the injection interval is shortened. It is an object of the present invention to provide a structure that improves the stability of the operation of the valve body at the time of valve and promotes the stabilization of the injection amount.

In order to achieve the above object, the fuel injection device of the present invention includes a valve body that opens and closes a flow path, a movable iron core that moves the valve body in the valve opening direction by magnetic attraction, and the movable iron core in a valve closed state. An intermediate member configured to form a preliminary stroke gap (g1) between the valve body and the valve body, a spring for the movable iron core that urges the movable iron core in the valve opening direction, and the intermediate member in the valve closing direction. The intermediate member is provided with a spring for urging the intermediate member so that the moving distance of the intermediate member becomes less than the preliminary stroke gap (g1) when the movable iron core collides with the intermediate member after the valve body is closed. The spring force of the movable iron core spring and the intermediate member spring was set in 1.

According to the configuration of the present invention, it is possible to reduce the displacement amount of the intermediate member during the valve closing operation and suppress the period during which the preliminary stroke gap becomes small, and it is possible to promote the stabilization of the fuel injection amount. Other configurations, actions, and effects of the present invention will be described in detail in the following examples.

It is sectional drawing which shows the structure of the fuel-injection apparatus which concerns on 1st Embodiment of this invention, and is the vertical sectional view which shows the cut surface parallel to the central axis 100a. FIG. 5 is an enlarged cross-sectional view showing an electromagnetic drive unit of the fuel injection device shown in FIG. 1. It is a figure explaining the operation of the movable part at the time of setting the spring force corresponding to the injection command pulse in the Example of this invention. It is a figure explaining the operation of the movable part when the spring force is not set corresponding to the injection command pulse in the Example of this invention. It is sectional drawing which shows the structure of the fuel injection apparatus which concerns on 2nd Embodiment of this invention, and is the vertical sectional view which shows the cut surface parallel to the central axis 100a.

Hereinafter, examples according to the present invention will be described.

The configuration of the fuel injection device 100 according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 4. FIG. 1 is a cross-sectional view showing the structure of the fuel injection device according to the first embodiment of the present invention, and is a vertical cross-sectional view showing a cut surface parallel to the central axis 100a. FIG. 2 is an enlarged cross-sectional view of the electromagnetic drive unit 400 shown in FIG. FIG. 3 is a diagram illustrating the operation of the movable iron core 404. 3 (a) and 4 (a) show the ON-OFF state of the injection command pulse, and FIGS. 3 (b) and 4 (b) show the movable iron core 404 with the valve closed state of the plunger rod 102 as displacement 0. And the displacement of the intermediate member 414. The operations of the movable iron core 404 and the intermediate member 414 shown in FIGS. 3 (b) and 4 (b) from t0 to t6 are the same.

The fuel injection device 100 includes a fuel supply unit 200 for supplying fuel, a nozzle unit 300 provided with a valve unit 300a at the tip for allowing or shutting off the flow of fuel, and an electromagnetic drive unit for driving the valve unit 300a. It is composed of 400. In this embodiment, an electromagnetic fuel injection device for an internal combustion engine using gasoline as a fuel will be described as an example. The fuel supply unit 200, the valve unit 300a, the nozzle unit 300, and the electromagnetic drive unit 400 indicate the corresponding parts with respect to the cross section shown in FIG. 1, and do not indicate a single part.

In the fuel injection device 100 of the present embodiment, the fuel supply unit 200 is configured on the upper end side of the drawing, the nozzle unit 300 is configured on the lower end side, and the electromagnetic drive unit 400 is configured between the fuel supply unit 200 and the nozzle unit 300. ing. That is, the fuel supply unit 200, the electromagnetic drive unit 400, and the nozzle unit 300 are arranged in this order along the central axis 100a direction.

The end of the fuel supply unit 200 on the opposite side of the nozzle unit 300 is connected to a fuel pipe (not shown). The end of the nozzle portion 300 opposite to the fuel supply portion 200 is a mounting hole (insertion hole) formed in an intake pipe or a combustion chamber forming member (cylinder block, cylinder head, etc.) of an internal combustion engine (not shown). Will be inserted. The electromagnetic fuel injection device 100 receives fuel from the fuel pipe through the fuel supply unit 200, and injects fuel from the tip of the nozzle unit 300 into the intake pipe or the combustion chamber. Inside the fuel injection device 100, a fuel passage 101 is provided so that fuel flows substantially along the central axis 100a of the electromagnetic fuel injection device 100 from the end of the fuel supply unit 200 to the tip of the nozzle unit 300. (101a to 101f) are configured.

In the following description, with respect to both ends in the direction along the central axis 100a of the fuel injection device 100, the end or end side of the fuel supply unit 200 located on the opposite side of the nozzle unit 300 is the base end or the base. It is called the end side, and the end portion or the end portion side of the nozzle portion 300 located on the opposite side to the fuel supply portion 200 is referred to as the tip portion or the tip end side. Further, with reference to the vertical direction of FIG. 1, each part constituting the electromagnetic fuel injection device will be described with "upper" or "lower".
This is done for the sake of easy understanding, and does not limit the mounting form of the electromagnetic fuel injection device to the internal combustion engine in the vertical direction.

(Structure explanation)
Hereinafter, the configurations of the fuel supply unit 200, the electromagnetic drive unit 400, and the nozzle unit 300 will be described in detail.

The fuel supply unit 200 is composed of a fuel pipe 201. A fuel supply port 201a is provided at one end (upper end) of the fuel pipe 201, and a fuel passage 101a is formed inside the fuel pipe 201 so as to penetrate in a direction along the central axis 100a. The other end (lower end) of the fuel pipe 201 is joined to one end (upper end) of the fixed iron core 401.

An O-ring 202 and a backup ring 203 are provided on the outer peripheral side of the upper end portion of the fuel pipe 201.
The O-ring 202 functions as a seal to prevent fuel leakage when the fuel supply port 201a is attached to the fuel pipe. The backup ring 203 is for backing up the O-ring 202. The backup ring 203 may be formed by laminating a plurality of ring-shaped members. A filter 204 for filtering foreign matter mixed in the fuel is provided inside the fuel supply port 201a.
The nozzle portion 300 includes a nozzle body 300b, and a valve portion 300a is formed at the tip end portion (lower end portion) of the nozzle body 300b. The nozzle body 300b is a hollow tubular body, and a fuel passage 101f is formed on the upstream side of the valve portion 300a. Further, a movable iron core receiving portion 311 is configured in the lower fuel passage portion 101e of the electromagnetic drive portion 400. A tip seal 103 that maintains airtightness when mounted on an internal combustion engine is provided on the outer peripheral surface of the tip of the nozzle body 300b.

The valve portion 300a includes an injection hole forming member 301, a guide member 302, and a valve body 303 provided at one end (end end on the lower end side) of the plunger rod 102.
The injection hole forming member 301 includes a valve seat 301a that is in contact with the valve body 303 to seal the fuel, and a fuel injection hole 301b that injects the fuel. The injection hole forming member 301 is inserted into and fixed to the concave inner peripheral surface 300ba formed at the tip of the nozzle body 300b. At this time, the outer circumference of the tip surface of the injection hole forming member 301 and the inner circumference of the tip surface of the nozzle body 300b are welded to seal the fuel.

The guide portion 302 is located on the inner peripheral side of the injection hole forming member 301, constitutes a guide surface on the tip end side (lower end side) of the plunger rod 102, and moves the plunger rod 102 in the direction along the central axis 100a (opening / closing valve direction). To guide you.

The electromagnetic drive unit 400 includes a fixed iron core 401, a coil 402, a housing 403, a movable iron core 404, an intermediate member 414, a plunger cap 410, a first spring member 405, a third spring member 406, and a second. It is composed of a spring member 407. The fixed iron core 401 is also called a fixed core. The movable iron core 404 is called a movable core, a movable element, or an amercha.

The fixed iron core 401 has a fuel passage 101c and a joint portion 401a with the fuel pipe 201 at the center. The outer peripheral surface 401b of the fixed iron core 401 is fitted and joined with the large diameter inner peripheral portion 300c of the nozzle body 300b, and is fitted and joined with the outer peripheral side fixed iron core 401d at the outer peripheral surface 401e having a diameter larger than the outer peripheral surface 401b. There is. A coil 402 is wound around the outer peripheral side of the fixed iron core 401 and the large diameter portion 300c of the tubular member.

The housing 403 is provided so as to surround the outer peripheral side of the coil 402, and constitutes the outer circumference of the electromagnetic fuel injection device 100. The upper end side inner peripheral surface 403a of the housing 403 is connected to the outer peripheral surface 401f of the outer peripheral side fixed iron core 401d, which is joined to the outer peripheral surface 401e of the fixed iron core 401.

A movable iron core 404 is arranged on the lower end surface 401 g side of the fixed iron core 401. The upper end surface 404c of the movable iron core 404 faces the lower end surface 401g of the fixed iron core 401 with a gap g2 in the valve closed state. Further, the outer peripheral surface of the movable iron core 404 faces the inner peripheral surface of the large diameter portion 300c of the nozzle body 300b via a slight gap, and the movable iron core 404 is the central axis inside the large diameter portion 300c of the tubular member. It is provided so as to be movable in the direction along 100a.

A magnetic path is formed in the fixed iron core 401, the movable iron core 404, the housing 403, and the large diameter portion 300c of the tubular member so that the magnetic flux circulates. The movable iron core 404 is attracted toward the fixed iron core 401 by the magnetic attraction generated by the magnetic flux flowing between the lower end surface 401 g of the fixed iron core 401 and the upper end surface 404c of the movable iron core 404.

A recess 404b recessed from the upper end surface 404c side to the lower end surface 404a side is formed in the central portion of the movable iron core 404. A fuel passage hole 404d is formed on the upper end surface 404c and the bottom surface 404'of the recess 404b as a fuel passage 101d penetrating to the lower end surface 404a in the direction along the central axis 100a. Further, the bottom surface 404'of the recess 404b is formed with a through hole 404e that penetrates to the lower end surface 404a in the direction along the central axis 100a. A plunger rod 102 is provided so as to insert the through hole 404e.

A plunger cap 410 is fixed to the plunger rod 102 by fitting, and has a large diameter portion 102a. The intermediate member 414 is a tubular member having a recess 404b having a step on the inner and outer circumferences, the inner peripheral side surface 414a is in contact with the upper surface 102b of the plunger rod large diameter portion 102a, and the outer peripheral side surface 414b is the movable iron core 404. It is in contact with the bottom surface 404b'of the recess 404b. There is a gap g1 between the lower surface 102c of the large diameter portion of the plunger rod and the lower surface 404b'of the movable iron core 404 recess 404b. The length obtained by subtracting the height h formed by the upper surface 102b and the lower surface 102c of the plunger rod thick diameter portion 102a from the height 414h of the recessed step of the intermediate member 414 is the gap g1.
The upper end of the first spring member 405 abuts on the lower end surface of the spring force adjusting member 106, and the lower end of the first spring member 405 abuts on the upper spring receiver 410a of the plunger cap 410 via the plunger cap 410. The rod 102 is urged downward. The upper end of the third spring member 406 abuts on the lower spring receiving portion 410b of the plunger cap 410, and the lower end of the third spring member 406 abuts on the upper surface 414c of the intermediate member 414 to close the intermediate member 414 in the valve closing direction. I'm urging.

The upper end of the second spring 407 is in contact with the lower surface 404a of the movable iron core 404, and the lower end of the second spring 407 is in contact with the stepped portion 300d of the nozzle body 300b to urge the movable iron core 404 in the valve opening direction. .. That is, the solenoid valve (fuel injection device 100) of this embodiment is attached to the first spring member 405 that urges the valve body 303 toward the valve closing direction, the stopper portion 410c, or the valve body 303, and has a preliminary stroke. The first spring member 405 includes a third spring member 406 that urges the intermediate member 414 in the direction of increasing the gap (g1) and a second spring member 407 that urges the movable iron core 404 in the valve opening direction. The spring force of the third spring member 406> the spring force of the second spring member 407. As a result, a preliminary stroke gap (g1) is formed in the valve closed state.

The coil 402 is assembled on the outer peripheral side of the fixed iron core 401 and the large diameter portion 300b of the tubular member in a state of being wound around the bobbin, and a resin material is molded around the fixed iron core 401. The resin material used in this mold integrally molds the connector 105 having the terminal 104 drawn from the coil 402.

(Operation explanation)
Next, the operation of the fuel injection device 100 in this embodiment will be described. This will be described mainly with reference to FIG. 2 which is an enlarged view of the electromagnetic drive unit 400 and FIGS. 3 and 4 which explain the operation of the movable unit. Note that FIGS. 3 (a) and 4 (a) are the same, and FIGS. 3 (b) and 4 (b) show the same operation of the movable iron core 404 and the intermediate member 414 from t0 to t6.

(Valve closed state definition, gap explanation)
In the valve closed state in which the coil 402 is not energized, the plunger rod 102 is urged in the valve closing direction by the first spring member 405. On the other hand, a force obtained by subtracting the urging force of the third spring member 406 from the urging force of the second spring member 407 acts in the valve opening direction, and the urging force of the first spring member 405 described above is in the valve opening direction. Since it is larger than the urging force on the valve seat 301a, the plunger rod 102 abuts on the valve seat 301a and closes the valve. This state is called a valve closed stationary state. At this time, the movable iron core 404 is in contact with the outer peripheral side step portion 414b of the intermediate member 414 and is arranged at the valve closing position. In the valve closed state of the fuel injection device of this embodiment, the gaps related to the moving parts related to the valve opening operation are configured as follows. There is a gap g1 between the bottom surface 404b'of the recess 404b of the movable iron core 404 and the bottom surface 102c of the large diameter portion 102a of the plunger rod.

(Operates after energization)
After energizing the coil 402 (P1), a magnetomotive force is generated by the electromagnet composed of the fixed iron core 401, the coil 402, and the housing 403. Due to this magnetomotive force, a magnetic flux orbiting a magnetic path composed of a fixed iron core 401, a housing 403, a large diameter portion 300d of a nozzle body, and a movable iron core 404 configured to surround the coil 402 flows. At this time, a magnetic attraction force acts between the upper end surface 404c of the movable iron core 404 and the lower end surface 401g of the fixed iron core 401, and the movable iron core 404 and the intermediate member 414 are displaced toward the fixed iron core 401. After that, the movable iron core 404 is displaced by g1 (between t0 and t1) until it abuts on the lower surface 102c of the plunger rod large diameter portion 102a. At this time, the plunger rod 102 does not move.

After that, when the movable iron core 404 abuts on the lower surface 102c of the large diameter portion of the plunger rod 102 at the timing of t1, the plunger rod 102 receives an impact force from the movable iron core 404 and is pulled up, and the plunger rod 102 separates from the valve seat 301a. This creates a gap in the valve seat and opens the fuel passage. Since the valve opening is started by receiving the impact force, the plunger rod 102 rises steeply (3A). At this time, the movable iron core and the intermediate member 414 operate in the same manner as the plunger rod 102.

After that, when the plunger rod 102 is displaced by g3 and the upper surface 404c of the movable iron core 404 comes into contact with the lower surface 401g of the fixed iron core 401 at the timing of t2, the intermediate member 414 is displaced upward (3B) and the movable iron core 404. Displaces downward (3B'), and after contacting again (3C), separates again, the plunger rod 102 is displaced upward (3D), and the movable iron core 404 is displaced downward (3D') and then stabilized at the displacement of g3 (3D'). 3E).

(Action, effect)
In the present invention, there is an intermediate member 414 below the third spring 406 that generates a spring force in the movable iron core 404 and the plunger rod 102, and the bottom surface 404b'of the recess 404b of the movable iron core 404 and the large diameter portion of the plunger rod 102. It is arranged in contact with the upper surface 102b. Therefore, when the movable iron core 404, the plunger rod 102, and the intermediate member 414 open the valve, and the movable iron core 404 and the fixed iron core 401 collide with each other at the timing t2, the movable iron core 404 moves in the valve closing direction, but is intermediate. The member 414 and the plunger rod 102 continue to move in the valve opening direction. In this state, the spring force acting between the movable iron core 404 and the plunger rod 102 is not generated, and the spring force is separated. Therefore, the spring force that changes with the movement of the movable iron core 404 is not transmitted to the plunger rod 102, and conversely, the spring force that changes with the movement of the plunger rod 102 is not transmitted to the movable iron core 404. They independently vibrate with each other (3B, 3B'). Further, when the collision occurs again (3C), the movable iron core 404 bounces in the valve closing direction (3D') and the plunger rod 102 bounces in the valve opening direction (3D) again, but they do not transfer force to each other. The plunger rod 102 and the movable iron core 404 have a small force while moving without applying a spring force that changes with each other's movement. Therefore, the bounce of the moving parts converges faster than when the spring force that changes with each other's movement is applied (3E). This effect makes it possible to stabilize the fuel injection amount.
Further, in the valve closed state, the gap g1 in which the movable iron core 404 is displaced is set by the recess height 414h of the intermediate member 414 and the height h of the plunger rod large diameter portion 102a (the height h formed by the upper surface 102b and the lower surface 102c of 102a). Since it is configured by the difference between the above, it is determined by the parts size, so that the adjustment in the assembly process is not required and the assembly process can be simplified.

At the timing t3, when the energization of the coil 402 is cut off (P2), the magnetic force begins to disappear, and the valve is closed by the urging force of the spring in the valve closing direction. After the displacement of the plunger rod 102 becomes 0 at the timing of t4, the plunger rod 102 comes into contact with the valve seat 301a to complete the valve closing. Further, since the intermediate member 414 is in contact with the upper surface 102b of the plunger rod large diameter portion 102a, the displacement cannot be smaller than 0.

On the other hand, the movable iron core 404 is further displaced in the valve closing direction even after the displacement of the intermediate member 414 becomes 0 at the timing of t4. After the movable iron core 404 is displaced most in the valve closing direction at the timing of t5, it is displaced in the valve opening direction by the second spring member so that the displacement becomes 0 again. At the timing of t6, the displacement becomes 0 again, and the movable iron core 404 and the intermediate member 414 collide with each other.

FIG. 4 shows the movable iron core 404 and the intermediate member 414 when the spring force of the second spring member 407 and the third spring member 406 for securing the preliminary stroke gap (g1) in the valve closing operation is not set. Shows the displacement of. Here, after the movable iron core 404 and the intermediate member 414 collide with each other at the timing of t6 and the displacement becomes 0, the movable iron core 404 and the intermediate member 414 move in the valve opening direction. After that, the movable iron core 404 and the intermediate member 414 operate in a direction in which the preliminary stroke gap (g1) disappears, and the bottom surface 404b'of the movable iron core 404 collides with the lower surface 102c of the large diameter portion of the plunger rod at the timing of t7'. At this timing t7', the preliminary stroke gap (g1) disappears.

The intermediate member 414 and the intermediate member 414 are further displaced in the valve opening direction from the preliminary stroke gap (g1) between t7'and t8, and the state without the preliminary stroke gap (g1) continues for a certain period of time. In this state, when the next pulse signal is sent, the movable iron core 404 cannot open the plunger rod 102 because there is no preliminary stroke gap (g1), and there is a risk that fuel injection cannot be performed.

On the other hand, FIG. 3 shows a case where the spring force of the second spring member 407 and the third spring member 406 for securing the preliminary stroke gap (g1) in the valve closing operation is set. From t6 to t7, the intermediate member 414 is displaced again in the valve closing direction by the spring force of the third spring member 406 without being displaced from the preliminary stroke gap (g1) in the valve opening direction, and as a result, the intermediate member 414 is movable. A preliminary stroke gap (g1) of the iron core 404 can be secured.

That is, the solenoid valve (fuel injection device 100) of the present embodiment has a valve body 303 that opens and closes the flow path, a movable iron core 404 that moves the valve body 303 in the valve opening direction by magnetic attraction, and is movable in the valve closed state. An intermediate member 414 configured to form a preliminary stroke gap (g1) between the iron core 404 and the valve body 303 is provided. The solenoid valve (fuel injection device 100) is for a movable iron core spring (second spring member 407) that urges the movable iron core 404 in the valve opening direction and an intermediate member that urges the intermediate member 414 in the valve closing direction. It includes a spring (third spring member 406).

Then, when the intermediate member 414 moves in the direction of reducing the preliminary stroke gap (g1), the spring force of the intermediate member spring (third spring member 406) for securing the preliminary stroke gap (g1) is set. ing. More specifically, when the movable iron core 404 collides with the intermediate member 414 after the valve body 303 is closed, the movable iron core spring (second) so that the moving distance of the intermediate member 414 is less than the preliminary stroke gap (g1). The spring force of the spring member 407) and the spring for the intermediate member (third spring member 406) is set. In particular, when the movable iron core 404 collides with the intermediate member 414 at the maximum speed after the valve body 303 is closed, the movable iron core spring (second) so that the moving distance of the intermediate member 414 is less than the preliminary stroke gap (g1). The spring force of the spring member 407) and the spring for the intermediate member (third spring member 406) is set.

A target fuel pressure is set for a common rail (not shown) to which a solenoid valve (fuel injection device 100) is attached. When the assumed common rail fuel pressure is maximum, the solenoid valve (fuel injection device 100) of this embodiment is intermediate when the movable iron core 404 collides with the intermediate member 414 after the valve body 303 is closed. The spring force of the movable iron core spring (second spring member 407) and the intermediate member spring (third spring member 406) is set so that the moving distance of the member 414 is less than the preliminary stroke gap (g1). .. Especially, it is desirable that the collision occurs at the maximum speed. As a result, the return to the initial state of valve closing is quickened, and the stability of the fuel injection amount is improved.

In order to secure a preliminary stroke gap (g1) in the valve closing operation, the present inventors have a relationship in which the maximum collision speed V at which the movable iron core 404 in the valve closing operation collides with the intermediate member 414 is shown in Equation 1 below. In some cases, it has been found that the spring force F3 of the third spring member needs to satisfy the relationship of Equation 2 below. Therefore, in the solenoid valve (fuel injection device 100) of the present embodiment, the spring force of the spring for the plunger rod, the spring for the movable iron core, and the spring for the intermediate member is set so that the following equations 1 and 2 are established. ..

In Equations 1 and 2, the spring force of the plunger rod spring (first spring member 405) is F1, the spring force of the movable iron core spring (second spring member 407) is F2, and the spring for the intermediate member (first). The spring force of the spring member 406) of 3 is F3, the differential pressure between the upstream side of the movable iron core 404 and the downstream side of the movable iron core 404 is F4, and the spring constant of the plunger rod spring (first spring member 405) is k1, movable. The spring constant of the iron core spring (second spring member 407) is k2, the spring constant of the intermediate member spring (third spring member 406) is k3, the mass of the intermediate member 414 is m1, and the mass of the movable iron core 404 is m2. , The mass of the valve body 303 was set to m3. In addition, g1 and g2 have the following relationship as described above.

g1 is the gap between the lower surface 102c of the plunger rod large diameter portion 102a and the bottom surface 404b'of the recess 404b of the movable iron core 404 when the valve is closed, and g2 is the gap between the upper end surface 404c of the movable iron core 404 and the lower end surface 401g of the fixed iron core 401. It is a gap between them.
V = {(k1-k3) * g2 ^ 2 + (F1-F3 + F4) * g2} / (m2 + m3) ・ ・ ・ (1)
F2> {(1/2 * (m1 + m2) * V ^ 2-1 / 2 * (k2-k3) * G1 ^ 2) / G1} + F3 ・ ・ ・ (2)
A flow path is formed in the movable iron core 404, but this acts as a throttle to cause a pressure loss, so that a differential pressure is generated between the upstream side and the downstream side. The differential pressure of the movable iron core 404 is referred to as F4, which indicates the differential pressure generated at the maximum collision speed V at which the movable iron core 404 collides with the intermediate member 414 in the valve closing operation.

Therefore, the spring force F2 of the movable iron core spring (second spring member 407) and the intermediate member spring (third spring) so that the amount of upward displacement of the movable iron core 404 in the valve closing operation is smaller than the preliminary stroke gap g1. By setting the spring force F3 of the member 406), the state in which the gap g1 is shortened is suppressed, so that the stability of the valve opening operation is improved.

Further, in the configuration of this embodiment, the outer diameter 414D of the intermediate member 414 is smaller than the inner diameter 401D of the fixed iron core. Therefore, when assembling the fuel injection device, the gap g1 is determined by the step height 414h of the intermediate member 414 and the height h of the plunger rod large diameter portion 102a, and then the spring force adjusting member 106 and the first spring member 405. The plunger cap 410, the plunger rod 102, the third spring member 406, and the intermediate member 414 can be integrated in advance and incorporated into the fuel injection device in a state where the plunger cap 410, the plunger rod 102, and the intermediate member 414 are integrated in advance, so that the assembly is easy and stable. It is possible to manage the gap g1. In this embodiment, the large diameter portion 414D of the intermediate member 414 is made smaller than the inner diameter 401D of the fixed iron core 401, but it is sufficient that the outermost diameter of the member to be assembled in advance is smaller, and the maximum of the plunger cap 410 is used. When the outer diameter is larger than the outermost diameter 414D of the intermediate member 414, the outermost diameter of the plunger cap 410 may be smaller than the inner diameter 401D of the fixed iron core 401.

In this embodiment, even if there is no movable iron core 404 recess 404b and the surface is the same as the 404c, the same operation and effect as in this embodiment can be obtained. By providing the recess 404b of the movable iron core 404, the intermediate member 414 can be arranged on the lower side, the length of the plunger rod 102 in the on-off valve direction can be shortened, and the plunger rod 102 with high accuracy can be shortened. This is because it becomes possible to configure.

The configuration of the second embodiment of the present invention will be described with reference to FIG. In the figure, there is no difference in the constituent action effect of the parts having the same numbers as those of the first embodiment, and thus the description thereof will be omitted.

In the valve closed state, the movable iron core 404 has a recess 404 b'depressed from the lower end surface side to the upper end surface side of the central portion, and the movable iron core 404 is formed on the bottom surface 404e of the recess 404 b'in the direction along the central axis 100a. A through hole 404e that penetrates to the upper end surface side of the above is configured. Further, a convex intermediate member 414 is inserted into the through hole 404f from the downstream side, and the upper surface 414b of the large diameter portion comes into contact with the recess 404b'of the movable iron core 404. Further, the intermediate member 414 is configured with a through hole 414e penetrating in the direction along the central axis 100a, and a plunger rod 102 is provided in the through hole 414e so as to pass through the through hole 414e. In the valve closed state, the upper end surface 414c of the intermediate member 414 and the lower end surface 102g of the plunger rod large diameter portion 102f are in contact with each other.

The height from the upper surface 414b of the large diameter portion of the intermediate member 414 to the upper end surface 414f is larger than the height from the bottom surface 404e of the recess of the movable iron core 404 to the upper end surface 404c by g1.

Here, the configuration of the third spring member 406 will also be described.
The third spring member 406 is housed in the recess 404'of the movable iron core 404. One end of the third spring member 406 is locked to the bottom surface 415b of the recess recessed from the upper end side to the lower end surface side of the central portion of the stopper 415 housed in the recess 404b'of the movable iron core 404, and the third spring member 406 The other end surface of the intermediate member 414 is locked to the lower end surface 414c of the intermediate member 414. That is, the solenoid valve (fuel injection device 100) of this embodiment includes a third spring member 406 that urges the intermediate member 414 in the valve opening direction, and the intermediate member 414 is movable with the valve body 303 by the third spring member 406. By urging the iron core 404 in the valve opening direction, a preliminary stroke gap (g1) in the valve closed state is formed.

In this embodiment, the lower end surface 415c of the stopper 415 and the stepped portion 300d of the nozzle body 300b are in contact with each other, but the stopper 415 is fixed to the movable iron core 404 and forms a gap with the stepped portion 300d of the nozzle body 300b. In some cases.
Further, the stopper portion 415a of the stopper 415 is arranged with respect to the lower end surface 414c of the intermediate member 414 through a gap (g2) larger than the preliminary stroke gap (g1).

Also in this embodiment, as in the first embodiment, when the movable iron core 404 collides with the intermediate member 414 after the valve body 303 is closed, the moving distance of the intermediate member 414 is less than the preliminary stroke gap (g1). The spring force of the movable iron core spring (second spring member 407) and the intermediate member spring (third spring member 406) is set. In particular, when the movable iron core 404 collides with the intermediate member 414 at the maximum speed after the valve body 303 is closed, the movable iron core spring (second) so that the moving distance of the intermediate member 414 is less than the preliminary stroke gap (g1). The spring force of the spring member 407) and the spring for the intermediate member (third spring member 406) is set.

Further, the solenoid valve (fuel injection device 100) is in the case where the assumed common rail fuel pressure is maximum, and in the solenoid valve (fuel injection device 100) of this embodiment, the movable iron core 404 is intermediate after the valve body 303 is closed. The movable iron core spring (second spring member 407) and the intermediate member spring (third spring member 406) so that the moving distance of the intermediate member 414 becomes less than the preliminary stroke gap (g1) when colliding with the member 414. Spring force is set. Especially, it is desirable that the collision occurs at the maximum speed. As a result, the return to the initial state of valve closing is quickened, and the stability of the fuel injection amount is improved.

Further, the solenoid valve (fuel injection device 100) is set so that the maximum collision speed V at which the movable iron core 404 in the valve closing operation collides with the intermediate member 414 satisfies the relationship of the equations 1 and 2 of the embodiment.

The present invention is not limited to the above-described examples, and includes various modifications. For example, the above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to the one including all the configurations. Further, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Further, it is possible to add / delete / replace a part of the configuration of each embodiment with another configuration.

100 ... Fuel injection device 101 ... Fuel passage 102 ... Plunger rod 200 ... Fuel supply unit 300 ... Nozzle unit 301a ... Valve seat 301b ... Fuel injection hole 311 ... Movable Iron core receiving part 400 ... Electromagnetic drive part 401 ... Fixed iron core 402 ... Coil 403 ... Housing 404 ... Movable iron core 405 ... First spring member 406 ... Third spring member 407 ...・ ・ Second spring member 414 ・ ・ ・ Intermediate member

Claims (5)

A valve body that opens and closes the flow path and
A movable iron core that moves the valve body in the valve opening direction by magnetic attraction,
An intermediate member configured to form a preliminary stroke gap (g1) between the movable iron core and the valve body in the closed state.
A spring for the movable iron core that urges the movable iron core in the valve opening direction,
An intermediate member spring that urges the intermediate member in the valve opening direction,
A stopper for supporting one end of the intermediate member spring is provided.
The stopper can move relative to the movable iron core in the opening / closing direction of the valve body.
The intermediate member spring is arranged between the stopper and the intermediate member in the opening / closing direction of the valve body.
When the movable iron core collides with the intermediate member after the valve body is closed, the movable iron core spring and the intermediate member spring are provided so that the moving distance of the intermediate member is less than the preliminary stroke gap (g1). A solenoid valve characterized by a set spring force. In the solenoid valve according to claim 1,
The movable iron core spring and the intermediate member so that the moving distance of the intermediate member becomes less than the preliminary stroke gap (g1) when the movable iron core collides with the intermediate member at the maximum speed after the valve body is closed. A solenoid valve characterized in that the spring force of a spring is set. In the solenoid valve according to claim 1,
When the fuel pressure of the common rail to which the solenoid valve is attached is maximum and the movable iron core collides with the intermediate member after the valve body is closed, the moving distance of the intermediate member is the preliminary stroke gap (g1). ), The solenoid valve is characterized in that the spring force of the movable iron core spring and the intermediate member spring is set so as to be less than. In the solenoid valve according to claim 1,
The intermediate member abuts on the valve closing direction side surface of the valve body and also abuts on the valve closing direction side surface of the movable iron core, and the valve body and the movable iron core are opened in the valve opening direction by the intermediate member spring. A solenoid valve characterized by being urged. In the solenoid valve according to claim 1,
A solenoid valve characterized in that the stopper and a nozzle body having a valve portion to which the valve body comes into contact with each other are in contact with each other.

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