JP2024039312A - electromagnetic fuel injection valve - Google Patents

Abstract

To early converge bouncing of a movable core that is in impulsive contact with a valve closing side stopper when a coil is de-energized, in an electromagnetic fuel injection valve.SOLUTION: While on a front end surface of a movable core 41, an annular recess part 50 concentric therewith is provided, on a rear end surface of a valve closing side stopper 49, an annular protrusion part 51 is provided that enters into the annular recess part 50 and closes the opening part of the annular recess part 50 when the movable core 41 is in contact with the valve closing side stopper 49.SELECTED DRAWING: Figure 4

Description

The present invention relates to an electromagnetic fuel injection valve mainly used in a fuel supply system of an internal combustion engine, and in particular, to a valve housing having a valve seat at the front end, and a hollow fixed core connected to the rear end of the valve housing. a coil disposed around the outer periphery of the fixed core; a valve element having a rod connected to a valve portion that cooperates with the valve seat; a movable core that is slidably fitted on an inner periphery and an outer periphery of the rod to allow fuel to flow within the valve housing; a movable core that is fixed to the rod and faces the rear end surface of the movable core and that a valve-opening side stopper that is pushed by the movable core that is attracted to the fixed core and opens the valve body when energized; and a valve-opening stopper that is fixed to the rod opposite to the front end surface of the movable core. a valve-side stopper; a valve spring that biases the valve body in a valve-closing direction; and a valve spring configured to cause the movable core to move away from the valve-opening side stopper and come into contact with the valve-closing side stopper when the coil is not energized. The present invention relates to an improvement in an electromagnetic fuel injection valve equipped with an auxiliary spring that biases the fuel injection valve.

Such an electromagnetic fuel injection valve is already known as disclosed in Patent Document 1 below.

Patent No. 6788085

In such an electromagnetic fuel injection valve, the set load of the auxiliary spring that biases the movable core toward the valve-closing stopper side is set smaller than the set load of the valve spring that biases the valve body in the valve-closing direction. When the coil is energized, in the process of increasing the attractive force of the fixed core against the movable core, the movable core quickly resists the set load of the auxiliary spring and approaches the fixed core. immediately pushes the valve-opening stopper against the set load of the valve spring and is attracted to the fixed core, thereby opening the valve quickly. This has the advantage of increasing the valve opening response of the valve body and reducing the power consumption of the coil.

On the other hand, because the set load of the auxiliary spring that biases the movable core toward the valve-closing stopper side is small, it is difficult to cut off current to the coil when the fuel injection interval time is extremely short, such as in a multi-stage fuel injection valve. Therefore, when a bouncing phenomenon occurs in the movable core that impacts the valve-closing stopper, it may be difficult to bring it under control by the time the coil is energized for the next valve opening. If the bouncing phenomenon that occurs in the movable core continues until the next time the coil is energized, the predetermined opening stroke of the valve body will be slightly deviated, potentially affecting the fuel injection characteristics.

The present invention has been made in view of the above circumstances, and provides an electromagnetic fuel injection valve capable of suppressing bouncing of the movable core by reducing the contact impact of the movable core against the valve closing side stopper when the coil is cut off. The purpose is to provide.

In order to achieve the above object, the present invention provides a valve housing having a valve seat at the front end, a hollow fixed core connected to the rear end of the valve housing, and a hollow fixed core arranged around the outer periphery of the fixed core. a coil, a valve element having a rod connected to a valve part that cooperates with the valve seat, and a valve body that is slidable on the inner periphery of the valve housing and the outer periphery of the rod while facing the front end surface of the fixed core. a movable core that is fitted and allows fuel to flow within the valve housing; and a movable core that is fixed to the rod and faces the rear end surface of the movable core, and that is attracted to the fixed core when the coil is energized. A valve-opening stopper that is pushed by the movable core to open the valve body; a valve-closing stopper that is fixed to the rod facing the front end surface of the movable core; an auxiliary spring that urges the movable core to move away from the valve-opening side stopper and come into contact with the valve-closing side stopper when the coil is de-energized. In the injection valve, a front end surface of the movable core is provided with an annular recess concentric therewith, and a rear end surface of the valve-closing stopper is provided with the annular recess when the movable core comes into contact with the valve-closing stopper. The first feature is that an annular convex portion is provided that closes the opening of the annular recess while allowing the top portion to enter the annular concave portion.

In addition to the first feature, the present invention has a second feature that the annular convex portion is formed to have an arcuate cross section.

According to the first feature of the present invention, when the movable core approaches the valve-closing stopper due to the biasing force of the auxiliary spring when the coil is de-energized, the annular protrusion of the valve-closing stopper contacts the annular recess of the movable core. As the fuel enters the annular recess and pressurizes the fuel that fills the inside, the opening is constricted, so the fuel inside the annular recess is strongly squeezed by the constricted part and flows out of the annular recess. Due to the damper effect, the contact impact of the movable core against the valve closing side stopper is alleviated. If the movable core tries to jump up immediately after the annular protrusion closes the opening of the annular recess, the sticking force generated as the pressure inside the annular recess is reduced prevents the movable core from jumping up. By repeating such actions, the bouncing of the movable core can be brought to an early end.

According to the second feature of the present invention, the annular convex portion is formed to have an arcuate cross section, so that when the coil is de-energized, the movable core contacts the valve-closing stopper in an inclined or eccentric state. However, due to the engagement of the annular convex portion and the annular concave portion, an alignment effect is exerted between the movable core and the valve-closing stopper, and the above-mentioned squeezing and sticking force can be generated.

1 is a longitudinal sectional view showing an embodiment of an electromagnetic fuel injection valve for an internal combustion engine according to the present invention. FIG. 2 is an enlarged sectional view taken along arrow 2 in FIG. 1, showing the fuel injection valve in a closed state. FIG. 3 is a diagram corresponding to FIG. 2 showing the open state of the fuel injection valve. An enlarged view of part 4 of FIG. 2. FIG. 4 is an enlarged view of part 4 of FIG. 2 (showing a state in which the movable core 41 approaches the valve-closing stopper 49 during the valve-closing process of the valve body).

Embodiments of the present invention will be described with reference to the accompanying FIGS. 1 to 4.

First, in FIGS. 1 and 2, the cylinder head 5 of the internal combustion engine E is provided with a mounting hole 7 that opens into the combustion chamber 6. An injection valve I is mounted in the mounting hole 7. In the electromagnetic fuel injection valve I of the present invention, the fuel injection side is the front side, and the opposite side is the rear side.

The valve housing 9 of this electromagnetic fuel injection valve I includes a hollow cylindrical housing body 10, a valve seat member 11 that fits and is welded to the inner periphery of the front end of the housing body 10, and a rear end of the housing body 10. A magnetic cylindrical body 12 is welded to the housing body 10 with its front end fitted to the outer periphery of the magnetic cylinder 12, and a non-magnetic cylindrical body 13 whose front end is coaxially connected to the rear end of the magnetic cylinder 12. Ru. A front end of a cylindrical fixed core 14 having a hollow part 15 is coaxially connected to the rear end of the non-magnetic cylindrical body 13, and a fuel supply connected to the hollow part 15 is connected to the rear end of the fixed core 14. The tubes 16 are integrally and coaxially connected.

The magnetic cylindrical body 12 has a flange-like yoke part 12a integrally in its axially intermediate part, and is accommodated in an annular groove 17 provided in the cylinder head 5 so as to surround the outer end of the mounting hole 7. A cushioning material 18 is interposed between the cylinder head 5 and the yoke portion 12a.

At the entrance of the fuel supply cylinder 16, an orifice member 24 and a fuel filter 19 located downstream thereof are installed. A fuel supply cap 21 branched from a fuel distribution pipe 20 connected to a discharge port of a fuel pump (not shown) is fitted into the fuel supply tube 16 via an annular seal member 22 . A bracket 23 is secured to the top of the fuel supply cap 21, and this bracket 23 is removably fastened to the cylinder head 5 using an appropriate fixing means (for example, a bolt) to a support (not shown) that is installed upright on the cylinder head 5. be done.

An elastic member 26 made of a leaf spring is interposed between the fuel supply cap 21 and an annular stepped portion 25 provided in the middle of the fuel supply cylinder 16 and facing the fuel supply cap 21 side. The electromagnetic fuel injection valve I is held in the cylinder head 5 by the elastic force exerted by the elastic member 26.

The valve seat member 11 has a bottomed cylindrical shape with an end wall portion 11a at the front end, and a conical valve seat 27 is formed on the end wall portion 11a. A plurality of fuel nozzle holes 28 are provided that open near the center of the fuel injection hole 27 . The valve seat member 11 is fitted and welded to the front end of the housing body 10 so that the fuel injection hole 28 opens toward the combustion chamber 6. That is, the valve housing 9 is configured to have a valve seat 27 at its front end.

A coil assembly 30 is fitted onto the outer peripheral surface of the magnetic cylindrical body 12 from the rear end to the fixed core 14 . This coil assembly 30 consists of a bobbin 31 that fits on the outer peripheral surface, and a coil 32 that is wound around the bobbin 31. The front end of a magnetic coil housing 33 that surrounds this coil assembly 30 is It is combined with the magnetic cylinder 12.

The outer periphery of the rear end of the fixed core 14 is covered with a synthetic resin coating layer 34 that is molded so as to be continuous with the rear end of the coil housing 33 . A coupler 34a holding the electromagnetic fuel injection valve I is integrally formed so as to protrude from one side thereof.

The rear end portion of the non-magnetic cylindrical body 13 is fitted into the small diameter portion of the front end of the fixed core 14 so that its outer peripheral surface is connected to the fixed core 14, and welded in a liquid-tight manner.

A portion of the valve body 40 and a movable core 41 are accommodated in the valve housing 9 extending from the valve seat member 11 to the non-magnetic cylindrical body 13. The valve body 40 includes a valve portion 42 that opens and closes the fuel injection hole 28 in cooperation with the valve seat 27, and a rod 43 that extends into the fixed core 14. The valve portion 42 is formed into a spherical shape so as to slide within the valve seat member 11, and the rod 43 is formed to have a smaller diameter than the valve portion 42. An annular fuel passage 44 is defined between the valve seat member 11 and the rod 43, and a plurality of flat parts 45 are formed on the outer circumferential surface of the valve portion 42 to define fuel passages between the valve seat member 11 and the rod 43. be done. Therefore, the valve seat member 11 allows fuel to pass through while guiding the opening and closing operations of the valve body 40.

The movable core 41 slides and rotates on the inner circumferential surface of the valve housing 9 and the outer circumferential surface of the rod 43, with its rear end surface (suction surface 41a) facing the front end surface (suction surface 14a) of the fixed core 14. Possibly fitted. Therefore, an annular gap 56a is provided between the outer circumferential surface of the movable core 41 and the inner circumferential surface of the valve housing 9, and an annular gap 56b is provided between the inner circumferential surface of the movable core 41 and the outer circumferential surface of the rod 43, respectively. Furthermore, the movable core 41 is arranged astride the magnetic cylindrical body 12 and the non-magnetic cylindrical body 13.

In order to regulate the sliding stroke of the movable core 41 on the rod 43 to a constant value, a valve-opening side stopper 48 and a valve-closing side stopper 49 that are arranged to sandwich the movable core 41 are fixed to the rod 43 by welding. At this time, the valve-opening side stopper 48 faces the suction surface 41a of the movable core 41, which is opposite to the fixed core 14, and the valve-closing side stopper 49 faces the suction surface 41a of the movable core 41. They are arranged so as to be able to abut and face the front end surface on the opposite side.

When the valve body 40 is in the closed state (see FIG. 2), the movable core 41 is in contact with the valve-closing stopper 49 and has a gap between it and the valve-opening stopper 48 corresponding to the sliding stroke. They face each other with an interval, and this interval, that is, the sliding stroke is set smaller than the interval provided between the movable core 41 and the fixed core 14 that are in contact with the valve-closing stopper 49. Therefore, when the fixed core 14 attracts the movable core 41 as the coil 32 is energized, the movable core 41 first contacts the valve-opening side stopper 48 and then is attracted to the fixed core 14.

The valve opening side stopper 48 is composed of a flange portion 48a that is slidably fitted to the inner circumferential surface of the fixed core 14, and a cylindrical shaft portion 48b that protrudes from the flange portion 48a toward the movable core 41 side. . The flange portion 48a is fixed to the rod 43 by welding, and a portion of the shaft portion 48b protrudes toward the movable core 41 side than the suction surface 14a when the valve body 40 is in the closed position.

Referring again to FIGS. 1 and 2, a pipe-shaped retainer 53 is fitted into the hollow portion 15 of the fixed core 14 and fixed by caulking. A valve spring 54 is compressed between the retainer 53 and the flange portion 48a of the valve-opening stopper 48, and urges the valve body 40 in the seating direction on the valve seat 27, that is, in the valve-closing direction.

Further, an auxiliary spring 55 that surrounds the shaft portion 48b of the valve-opening side stopper 48 is compressed between the flange portion 48a of the valve-opening side stopper 48 and the movable core 41. This auxiliary spring 55 is given a set load smaller than the set load of the valve spring 54, and urges the movable core 41 to move away from the valve-opening side stopper 48 and come into contact with the valve-closing side stopper 49. .

The rear end of the rod 43 protrudes beyond the flange 48a of the valve-opening stopper 48, fits into the inner peripheral surface of the movable end of the valve spring 54, and plays a positioning role. Further, the shaft portion 48b of the valve-opening side stopper 48 fits into the inner circumferential surface of the auxiliary spring 55, and plays the role of positioning the auxiliary spring 55.

At multiple locations on the outer periphery of the flange portion 48a of the valve-opening side stopper 48, flat portions 57 are provided that define fuel passages between them and the inner peripheral surface of the fixed core 14. A plurality of fuel holes 58 are provided.

As shown in FIGS. 2 and 4, an annular recess 50 concentric with the movable core 41 is provided on the front end surface of the movable core 41 inside a plurality of annularly arranged fuel holes 58. , the movable core 41 has a V-shaped cross section opening at the front end side, and the apex angle θ of the V-shaped cross section is set to be an obtuse angle. On the other hand, an annular protrusion 51 is provided on the rear end surface of the movable core 41 of the valve-closing side stopper 49, and is arranged concentrically with the valve-closing side stopper 49 and coaxially with the annular recess 50. , its cross section is formed into a convex arc. When the movable core 41 comes into contact with the valve-closing stopper 49, the annular convex portion 51 causes its apex 51a to enter the annular recess 50, thereby forming two grooves on the inner and outer circumferences of the annular recess 50. It comes into contact with the edge of the opening, thereby closing the opening of the annular recess 50. In FIG. 4, the symbol R indicates the radius of the arc of the cross-sectional shape of the annular convex portion 51, and the center O of the arc is located on the bisector Y of the V-shaped cross section of the annular recess 50. .

Next, the operation of this embodiment will be explained.

In the electromagnetic fuel injection valve I, when the coil 32 is in a non-energized state, the valve body 40 is pressed by the set load of the valve spring 54 to close the fuel injection hole 28 by seating on the valve seat 27. state. In this valve-closed state, high-pressure fuel discharged from a fuel pump (not shown) to the fuel distribution pipe 20 is supplied to the fuel supply cylinder 16 through the fuel supply cap 21, and the inside of the fuel injection valve I, that is, the fuel supply pipe 16, is The insides of the retainer 53, fixed core 14, movable core 41, valve housing 9, etc. are filled and standby.

At this time, the pulsations in the fuel pressure that occur in the fuel distribution pipe 20 due to variations in the discharge pressure of the fuel pump, etc., are attenuated by the orifice of the orifice member 24 at the inlet of the fuel supply cylinder 16, and the pulsations are transferred to the inside of the fuel injection valve I. The impact of this is eliminated or reduced.

On the other hand, as shown in FIG. 2, in such a valve-closed state, the movable core 41 engages the annular concave portion 50 of the movable core 41 with the annular convex portion 51 of the valve-closing stopper 49 due to the set load of the auxiliary spring 55. The fixed core 14 is maintained at a predetermined distance from the fixed core 14.

When the coil 32 is energized in such a valve closed state, the movable core 41 is attracted to the fixed core 14 by the magnetic force generated between the fixed core 14 and the movable core 41, so first, while compressing the auxiliary spring 55, It slides upward on the rod 43 and comes into contact with the valve opening side stopper 48. That is, at the time of its initial movement, the movable core 41 approaches the fixed core 14 while quickly compressing the auxiliary spring 55, which has a smaller set load than the valve spring 54, and obtains a sudden increase in the suction force from the fixed core 14, so that the movable core 41 moves toward the valve opening side. Push up the stopper 48 vigorously.

Therefore, the movable core 41 quickly moves further rearward against the large set load of the valve spring 54 while being accompanied by the valve opening side stopper 48, and is attracted to the suction surface 14a of the movable core 41.

Since the valve-opening stopper 48, which moves rearward together with the movable core 41, is fixed to the rod 43 of the valve body 40, it is possible to displace the valve portion 42 from the valve seat 27 and open the valve. When the valve body 40 opens, high-pressure fuel waiting inside the valve housing 9 or the like is directly injected from the fuel injection hole 28 into the combustion chamber 6 of the internal combustion engine E. In this way, the valve-opening response of the valve body 40 can be improved, and the power consumption of the coil 32 can be reduced.

Next, when the current to the coil 32 is cut off, the valve opening side stopper 48 is pushed by the large set load of the valve spring 54, so the valve opening side stopper 48 moves with the movable core 41 and the valve body 40. It immediately moves to the valve seat 27 side, seats the valve portion 42 on the valve seat 27, and closes the valve to stop fuel injection from the fuel injection hole 28. This closed state of the valve body 40 is reliably maintained by a large set load of the valve spring 54.

On the other hand, the movable core 41 is forcefully pressed toward the valve-closing stopper 49 by the set load of the auxiliary spring 55. Then, as shown in FIG. 5, when the movable core 41 approaches the valve-closing stopper 49, the annular protrusion 51 of the valve-closing stopper 49 causes its top 51a to enter the annular recess 50 of the movable core 41. Since the opening of the annular recess 50 is squeezed while pressurizing the fuel filling the inside of the annular recess 50, the fuel inside the annular recess 50 flows out of the annular recess 50 while being strongly squeezed by the throttle. The resulting damper effect reduces the impact of the movable core 41 against the valve-closing stopper 49. Immediately after the annular convex part 51 closes the opening of the annular concave part 50, if the movable core 41 tries to jump up and the top part 51a of the annular convex part 51 tries to come out of the annular concave part 50, the inside of the annular concave part 50 A sticking force is generated due to the reduced pressure and suppresses the movable core 41 from jumping up. By repeating such actions, the bouncing of the movable core 41 can be brought to an early end.

Further, since the annular concave portion 50 is formed with a V-shaped cross section, and the annular convex portion 51 is formed with an arc-shaped cross section, the movable core 41 is tilted with respect to the valve-closing stopper 49 when the coil 32 is de-energized. , or even when they abut in an eccentric state, the engagement between the annular convex portion 51 and the annular concave portion 50 causes an alignment action between the movable core 41 and the valve-closing stopper 49, producing the above-mentioned squeezing and sticking force. , it is possible to achieve early convergence of bouncing of the movable core 41.

In this way, the bouncing time of the movable core can be significantly shortened, and even if the fuel injection interval time is extremely short, such as in a multi-stage fuel injection valve, the bouncing phenomenon can be resolved by the time the coil 32 is energized next. It is possible to maintain predetermined fuel injection characteristics.

By the way, when the coil 32 is energized and the movable core 41 is separated from the valve-closing side stopper 49 by the suction force of the fixed core 14, the depressurization resistance generated in an attempt to pull back the annular protrusion 51 within the annular recess 50 is excessive. In this case, the valve opening responsiveness of the valve body 40 will be reduced, so the magnitude of the pressure reducing resistance should be set to satisfy both the bouncing suppression of the movable core 41 and the valve opening responsiveness of the valve body 40. Therefore, it is necessary to control the This control can be achieved, for example, by adjusting the radius R of the arc-shaped cross section of the annular protrusion 51 and adjusting the volume of the annular protrusion 51 entering the annular recess 50 .

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the scope of the present invention as set forth in the claims. It is possible. For example, the cross-sectional shape of the annular recess 50 may be U-shaped.

I...Electromagnetic fuel injection valve 9...Valve housing 14...Fixed core 27...Valve seat 32...Coil 40...Valve body 41...Movable core 42... Valve portion 43... Rod 48... Valve opening side stopper 49... Valve closing side stopper 50... Annular recess 51... Annular protrusion 51a... Top of annular protrusion 54... Valve spring 55... Auxiliary spring

Claims (2)

A valve housing (9) having a valve seat (27) at the front end, a hollow fixed core (14) connected to the rear end of the valve housing (9), and arranged around the outer periphery of the fixed core (14). a coil (32) provided therein, a valve body (40) in which a rod (43) is connected to a valve portion (42) that cooperates with the valve seat (27), and a front end of the fixed core (14). A movable core (41) is slidably fitted to the inner periphery of the valve housing (9) and the outer periphery of the rod (43) while facing the surface thereof, and allows fuel to flow within the valve housing (9). ), the movable core (41) is fixed to the rod (43), faces the rear end surface of the movable core (41), and is attracted to the fixed core (14) when the coil (32) is energized. a valve-opening side stopper (48) that is pushed by and opens the valve body (40); and a valve-closing side stopper (48) that is fixed to the rod (43) facing the front end surface of the movable core (41). A stopper (49), a valve spring (54) that biases the valve body (40) in the valve-closing direction, and a valve spring (54) that moves the movable core (41) to the valve-opening side stopper ( 48) and an auxiliary spring (55) that urges the valve to come into contact with the valve-closing side stopper (49),
The front end surface of the movable core (41) is provided with an annular recess (50) concentric therewith, while the rear end surface of the valve closing side stopper (49) is provided with the valve closing side stopper (49) of the movable core (41). 49), an annular protrusion (51) is provided that closes the opening of the annular recess (50) while allowing the apex (50a) to enter the annular recess (50); Electromagnetic fuel injection valve. The electromagnetic fuel injection valve according to claim 1, wherein the annular convex portion (51) has an arcuate cross section.