JPH064368U - Electromagnetic fuel injection valve - Google Patents

Abstract

(57) [Abstract] [Purpose] A valve body and a movable core that is interlocked with and linked to the rear end portion of the valve body are housed in a housing so as to be movable in the axial direction. In an electromagnetic fuel injection valve that is spring-biased in the direction in which the seat is seated on the valve seat, bouncing during seating is suppressed and low-quantity fuel injection is enabled. [Structure] A rear end portion of a valve body 21 is fitted to a movable core 24 so as to allow relative sliding in an axial direction, and the valve body 21 and a fixed core 8 are
A first spring 25 for urging the valve body 21 forward is provided between them, and a second spring 26 for urging the movable core 24 backward is provided between the movable core 24 and the housing 1.
A receiving surface 31 provided with a smaller spring load than the receiving surface 31 provided on the movable core 24 facing the rear, and an abutting surface provided on the rear end of the valve body 21 so as to be able to abut the receiving surface 31. 32 between the fuel passages 17 and 2 in the housing 1.
A damper chamber 35 that communicates with the second chamber 2 through a throttle 36 is formed.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 According to the present invention, a fixed core is fixedly arranged at a rear part of a housing, and a valve body that faces the rear and can be seated at a valve seat provided at a front end of a housing and a rear end of the valve body are interlocked. , The movable core that is connected and arranged in front of the fixed core is housed in the housing so as to be movable in the axial direction, and the valve body and the movable core are spring-biased in the direction in which the tip of the valve body is seated on the valve seat. Electromagnetic fuel injection valve.

[0002]

[Prior art]

 Conventionally, such an electromagnetic fuel injection valve is known, for example, from Japanese Utility Model Laid-Open No. 1-176749.

[0003]

[Problems to be solved by the device]

 In the above-mentioned conventional type, the rear end portion of the valve body is integrally connected to the movable core by press fitting into the movable core and caulking, and when the valve is closed, the valve body and the movable core are integrally closed. It is designed to operate on the valve side. At this time, a bouncing phenomenon occurs in which the tip of the valve element bounces when it is seated on the valve seat.Therefore, fuel is injected before the tip of the valve element is completely seated on the valve seat, resulting in a low flow rate injection. Will be difficult. This is because the valve body and the movable core are relatively heavy due to their integral structure, which results in a large impact when seated and a large lift amount of the valve body due to bouncing.

The present invention has been made in view of such circumstances, and it is an object of the present invention to provide an electromagnetic fuel injection valve capable of suppressing a valve lift amount due to bouncing at the time of seating and injecting a small amount of fuel. To aim.

[0005]

[Means for Solving the Problems]

 In order to achieve the above object, according to the present invention, the rear end portion of the valve body is fitted to a movable core so as to allow relative sliding in the axial direction, and the valve body is provided between the valve body and the fixed core. A first spring for urging the movable core forward is provided, and a second spring for urging the movable core rearward is provided between the movable core and the housing with a spring load smaller than that of the first spring. A fuel passage formed in the housing is narrowed between the receiving surface provided on the movable core and the abutting surface provided on the rear end portion of the valve body capable of abutting on the receiving surface. A damper chamber that communicates with each other is formed.

[0006]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings.

1 to 4 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of an electromagnetic fuel injection valve, and FIG. 2 is an enlarged view of a main part of FIG. 1 in a valve closed state. FIG. 3 is a sectional view corresponding to FIG. 2 when the movable core is overshooting, and FIG. 4 is a diagram showing operating characteristics in comparison with a conventional example.

First, referring to FIG. 1, a housing 1 of this electromagnetic fuel injection valve includes a housing body 2 having a basically cylindrical shape, and a bottomed cylindrical valve housing fixedly mounted on a tip portion of the housing body 2. 3 and an electromagnetic housing 4 fixed to the rear end side of the housing body 2.

The housing main body 2 is composed of a large-diameter cylindrical portion 2a on the rear side and a small-diameter cylindrical portion 2b on the front side, which are coaxially and integrally connected to each other via a step portion 2c. A collar portion 5 extending inward in the radial direction is integrally provided on the inner surface of the intermediate portion of the portion 2b over the entire circumference.

The valve housing 3 is formed in a bottomed cylindrical shape having a diameter-increased portion 3a having a stepped diameter on the rear end side and a front-end side having a closed end. The enlarged diameter portion 3a of the valve housing 3 is fitted in the small diameter cylindrical portion 2b with a ring-shaped seal plate 6 interposed between the enlarged diameter portion 3a and the flange portion 5, and a cap nut 7 that engages with the enlarged diameter portion 3a. The valve housing 3 is fixed to the tip of the housing body 2 by being screwed onto the outer surface of the small diameter cylindrical portion 2b.

The electromagnetic section housing 4 includes a fixed core 8, a cylindrical yoke 9 that coaxially surrounds the fixed core 8, a connecting plate 10 that connects the fixed core 8 and the rear end of the yoke 9, and the fixed core 8. It has a connecting cylinder 11 coaxially connected to the rear end thereof, and a yoke 9 is screwed into the large-diameter cylindrical portion 2a of the housing body 2.

A coil 13 wound around a bobbin 12 is inserted between the fixed core of the electromagnetic housing 4 and the yoke 9, and a connecting plate is connected to nuts 14 embedded in the bobbin 12 at a plurality of circumferential positions, for example, at two positions. The coil 13 is fixed to the electromagnetic unit housing 4 by screwing the screw members 15 penetrating the respective screws 10. Further, from the bobbin 12, a pair of connection terminals 16 penetrating the connecting plate 10 and projecting outward are drawn out. Further, a fuel passage 17 is coaxially provided in the connecting cylinder 11 and the fixed core 8, and a filter 18 is attached to a rear end portion of the fuel passage 17.

Referring also to FIG. 2, a valve seat 20 having an ejection hole 19 in the center is provided on the inner surface of the valve closing portion of the valve housing 3 so as to face rearward, and the valve seat 20 has its tip at the valve seat 20. A needle-shaped valve body 21 that can be seated to close the ejection hole 19 is axially movably inserted into the valve housing 3 so as to form an annular fuel passage 22 with the inner surface of the valve housing 3. To be done. The valve body 21 is provided with a pair of guide portions 23, 23 slidably contacting the inner surface of the valve housing 3 at intervals in the axial direction, and these guide portions 23, 23 are provided at a plurality of circumferential positions. Are provided with flat notches 23a, 23a for avoiding blocking of the fuel passage 22, respectively.

The rear end portion of the valve body 21 projects into the front end portion of the large-diameter cylindrical portion 2 a of the housing body 2, and the rear end portion of the valve body 21 is located in front of the fixed core 8. The movable core 24 is interlocked and coupled so as to be capable of relative movement in the axial direction within a limited range, and between the rear end of the valve body 21 and the fixed core 8, the first core biases the valve body 21 to the front side. The spring 25 is contracted, and the second spring 26 for urging the movable core 24 toward the fixed core 8 is contracted between the flange portion 5 of the housing body 2 and the movable core 24, and the spring load of the first spring 25 is reduced. Is set larger than the second spring 26.

The movable core 24 is formed by coaxially and integrally connecting a forwardly extending cylindrical portion 24b to a central portion of a disc portion 24a facing the tips of the fixed core 8 and the yoke 9. A plurality of through holes 27 are formed in 24a to allow the flow of fuel. A large-diameter hole 28 on the rear side and a small-diameter hole 29 on the front side are coaxially formed in the movable core 24 so as to form a step between the large-diameter hole 28 and the small-diameter hole 29. A cylindrical sleeve 30 having a locking collar 30a for locking at the rear end is press-fitted into the small-diameter hole 29 such that the tip of the cylindrical sleeve 30 projects forward from the movable core 24.

The rear end portion of the valve body 21 is slidably fitted to the sleeve 30, and the overhanging collar 21 a provided at the rear end of the valve body 21 is attached to the locking collar 30 a of the sleeve 30. It is inserted into the large diameter hole 28 so as to face each other. A flat receiving surface 31 is formed rearward on the locking collar 30a of the sleeve 30 which is integral with the movable core 24, and the protruding flange 21a at the rear end of the valve body 21 has a receiving surface. A flat contact surface 32 capable of contacting 31 is formed facing the front. A communication passage 33 is formed in the rear end portion of the valve body 21 for communicating the fuel passage 17 formed in the rear portion of the housing 1 with the fuel passage 22 formed in the front portion of the housing 1. Set up.

By the way, in the state where the tip of the valve body 21 is seated on the valve seat 20, the movable core 24 has its receiving surface 31 separated from the contact surface 32 of the valve body 21, and is shown in FIG. Thus, the damper chamber 35 is formed between the contact surface 32 of the valve body 21 and the receiving surface 31 of the movable core 24. Moreover, between the outer surface of the protruding flange 21a at the rear end portion of the valve body 21 and the inner surface of the large diameter hole 28 in the movable core 24, there is formed a minute throttle 36 that allows the damper chamber 35 to communicate with the fuel passages 17 and 22. The gap is formed in an annular shape.

Next, the operation of this embodiment will be described. When the coil 13 is demagnetized, the valve body 21 urged by the first spring 25 having a large spring load is seated on the valve seat 20. Since the ejection hole 19 is closed and the movable core 24 is urged by the second spring 26 having a small spring load at that time, the receiving surface 31 is brought into contact with the contact surface 32 of the valve body 21. Is in When the coil 13 is excited in this state, the movable core 24 is attracted to the fixed core 8 side, and the contact surface 32 is in contact with the receiving surface 31, so that the valve body 21 resists the spring force of the first spring 25. And moves toward the fixed core 8 side, the tip of the valve body 21 separates from the valve seat 20, and the ejection hole 19 is opened. Therefore, the fuel filtered by the filter 18 is ejected from the fuel passage 17 through the communication passage 33 and the fuel passage 22 through the ejection hole 19.

The fuel injection amount is controlled by changing the duty ratio of the coil 13, that is, the excitation time of the coil 13 within a fixed time, and changes the coil 13 from the excitation state to the demagnetization state. When the attraction force to the fixed core 8 disappears, the valve body 21 is urged toward the fixed core 8 side by the second spring 26 having a small spring load due to the spring force of the first spring 25 having a large spring load. While moving the movable core 24 which is being pushed, the movable core 24 is moved forward, the tip of the valve body 21 is seated on the valve seat 20, and the ejection hole 19 is closed.

When the valve body 21 is seated on the valve seat 21, the valve body 21 is pushed by the first spring 25 having a large spring load, the weight of the valve body 21 itself is relatively small, and the fuel pressure is high. Acting in the seating direction, the valve seat 20 is smoothly seated and bouncing does not occur.

On the other hand, the movable core 24 is movable in the axial direction relative to the valve body 21, and when the valve body 21 is seated, the inertia force of the movable core 24 is a spring of the second spring 26 having a relatively small spring load. When the force exceeds the force, the movable core 24 overshoots, and when the movable core 24 returns by the spring force of the second spring 26, the receiving surface 31 of the movable core 24 collides with the contact surface 32 of the valve body 21, thereby It will separate from the valve seat 20 again. However, before the overshoot, the contact surface 32 of the valve body 21 is in close contact with the receiving surface 31 of the movable core 24. Therefore, due to the viscosity of the fuel, “sticking” between the receiving surface 31 and the contact surface 32 occurs. In addition, the damper chamber 35 formed between the receiving surface 31 and the contact surface 32 communicates with the fuel passages 17 and 22 via the throttle 36. Therefore, when the movable core 24 overshoots, the overshoot speed of the movable core 24 is attenuated by the resistance due to the “sticking” and the damper effect of the damper chamber 35. Since the viscous resistance due to the fuel accompanying the operation in the fuel also acts, the overshoot speed of the movable core 24 is further attenuated. As a result, the collision speed of the movable core 24 against the valve body 21 at the time of returning is suppressed, and the impact at the time of collision is separated, so that the lift amount of the valve body 21 in the valve opening direction is suppressed to be small.

Therefore, as shown in FIG. 4A, it is possible to reduce the overshoot of the movable core 24 and suppress the valve opening lift amount of the valve body 21 due to the re-collision to a small amount, and to inject a small amount of fuel. It can be possible. On the other hand, in the conventional structure in which the valve body and the movable core are integrally connected, as shown in FIG. 4B, a bouncing phenomenon in which the valve opening lift amount is relatively large occurs, and it is difficult to inject at a low flow rate. It will be.

As another embodiment of the present invention, as shown in FIG. 5, a throttle 36 ′ for communicating the damper chamber 35 with the fuel passage 22 is directly formed in the rear end portion of the valve body 21. It is also possible to obtain the same effect as that of the above embodiment.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the present invention described in the scope of claims for utility model registration. It is possible to make small design changes.

[0025]

[Effect of device]

 As described above, according to the present invention, the rear end portion of the valve body is fitted to the movable core so as to allow relative sliding in the axial direction, and the valve body is moved forward between the valve body and the fixed core. A first spring that biases the movable core is provided between the movable core and the housing, and a second spring that biases the movable core rearward is provided with a smaller spring load than the first spring. A fuel passage formed in the housing is passed through a throttle between a receiving surface provided on the core and an abutting surface provided on a rear end portion of the valve body capable of abutting on the receiving surface. Since a damper chamber that twists is formed, the bouncing of the valve body when seated is suppressed, and the overshoot speed of the movable core is attenuated to re-collide with the valve body of the movable core. The lift amount can be suppressed to a low level, and a low amount of fuel can be injected.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an electromagnetic fuel injection valve according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of FIG. 1 in a valve closed state.

FIG. 3 is a cross-sectional view corresponding to FIG. 2 when the movable core overshoots.

FIG. 4 is a diagram showing operating characteristics in comparison with a conventional example.

FIG. 5 is a sectional view of another embodiment corresponding to FIG.

[Explanation of symbols]

 1 Housing 8 Fixed Core 17,22 Fuel Passage 20 Valve Seat 21 Valve Body 24 Movable Core 25 First Spring 26 Second Spring 31 Bearing Surface 32 Abutment Surface 35 Damper Chamber 36, 36 'Throttle

Continued Front Page (72) Inventor Masami Nakamura 1-4-1 Chuo, Wako-shi, Saitama, Ltd. Inside Honda R & D Co., Ltd.

Claims (1)

[Scope of utility model registration request] 1. A valve in which a fixed core (8) is fixedly arranged at a rear portion of a housing (1), and a front end of which can be seated on a valve seat (20) provided at a front end of the housing (1). The body (21) and a movable core (24) arranged in front of the fixed core (8) interlockingly connected to the rear end of the valve body (21) are axially movable so that the housing (1). It is housed in a valve body (21) and a movable core (2
4) is an electromagnetic fuel injection valve in which the tip end of the valve body (21) is seated on the valve seat (20), the rear end of the valve body (21) slides in the axial direction. And a movable core (24) which enables the valve body (21) and the fixed core (8) to urge the valve body (21) forward.
A spring (25) is provided, and between the movable core (24) and the housing (1), a second spring (26) that biases the movable core (24) rearward has a spring load greater than that of the first spring (25). Movable core (24)
Between the receiving surface (31) provided on the housing and the abutting surface (32) provided on the rear end of the valve body (21) so as to be able to contact the receiving surface (31). ) An electromagnetic fuel injection valve is characterized in that a damper chamber (35) communicating with a fuel passage (17, 22) formed in the inside is formed through a throttle (36, 36 ').