JP2024021372A - electromagnetic fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic fuel injection valve in which, when a coil is energized, valve opening characteristics are properly maintained by avoiding operation delay of a movable core, and when energization of the coil is cut off, bouncing of the movable core can be suppressed.

SOLUTION: An annular convex part 50 concentric with a movable core 41 is provided at a front end surface of the movable core 41 so as to abut against a flat rear end surface of a valve closing side stopper 49 fixed in the inner periphery of a valve housing 9. The annular convex part 50 is formed on the basis of an annular convex curve surface Ta' of a virtual torus T set concentrically with the movable core 41. A notch 51 traversing the apex 50a is provided to the annular convex part 50.

SELECTED DRAWING: Figure 2

COPYRIGHT: (C)2024,JPO&INPIT

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 the inner periphery and the outer periphery of the rod and allows fuel to flow within the valve housing; and a movable core that is fixed to the rod and 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; and an annular closing stopper that is fitted and fixed to the inner peripheral surface of the valve housing facing 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.

Special Publication No. 2002-506502

In the electromagnetic fuel injection valve described in Patent Document 1, the movable core and the valve-closing-side stopper have their entire opposing surfaces flat, so that when the valve body is closed, they come into surface contact over a wide area. In such a device, when the movable core is pressed to the contact position with the valve-closing stopper by the biasing force of the auxiliary spring as the coil is de-energized, a fuel oil film is formed between the wide contact surface of the movable core and the valve-closing stopper. This generates a large sticking force, which has the advantage of suppressing bouncing of the movable core.

However, when the coil is de-energized, if the sticking force generated at the abutting part of the movable core and the valve-closing stopper becomes excessive, the movable core will experience a delay in operation when the coil is energized, and the valve-opening response of the valve body will be affected. This causes the inconvenience of significantly lowering the quality of the product.

The present invention has been made in view of the above circumstances, and makes it possible to appropriately control the sticking force due to the fuel oil film generated at the contact portion of the movable core and the valve closing side stopper when the coil is energized, and when the coil is energized. It is an object of the present invention to provide the electromagnetic fuel injection valve that avoids delay in operation of the movable core and maintains good valve opening characteristics, and that can suppress bouncing of the movable core when power is cut off to the coil.

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 is attracted to the fixed core when the coil is energized, and is pushed by the movable core to move the valve body. a valve-opening stopper that operates to open the valve; an annular valve-closing stopper that faces the front end surface of the movable core and fits and is fixed to the inner peripheral surface of the valve housing; 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, an annular convex portion concentric with the movable core is provided on the front end surface of the movable core so as to be able to come into contact with the flat rear end surface of the valve-closing side stopper, and the annular convex portion is in contact with the movable core. The first feature is that it is formed following the annular Ta of the virtual torus set concentrically, and that the annular convex portion is provided with a notch that crosses its apex.

In addition to the first feature, the present invention has a second feature that the annular convex portion is provided with three or more of the notches at equal intervals.

Furthermore, in addition to the first or second feature, the present invention has a third feature that the notch is formed to become wider toward the outside in the radial direction of the movable core.

According to the first feature of the present invention, the annular convex portion provided on the front end surface of the movable core is formed following the annular shape of a virtual torus set concentrically with the movable core, and the annular convex portion includes: Since a notch is provided across the apex, when the coil is cut off, the thickness of the fuel oil film generated at the contact area between the annular protrusion of the movable core and the flat rear end surface of the valve-closing stopper is as follows: The force increases radially outward and inward from the apex of the annular convex portion, and the sticking force of the abutting portion gradually decreases. Further, the sticking force of the abutting portion is reduced by the area of the notch on the annular convex portion. Therefore, by appropriately setting the radius of curvature of the annular convex portion and the area of the notch, it is possible to control the sticking force as desired, and both suppress movable core bouncing and improve valve opening response. can be done.

Moreover, when the movable core comes into contact with the valve-closing side stopper in an inclined position when the coil is de-energized, one point of the annular convex part of the movable core touches the flat side of the valve-closing side stopper, regardless of the size of the tilt angle. This allows the movable core to quickly return to its proper posture due to the biasing force of the auxiliary spring, which contributes to suppressing bouncing of the movable core, and also prevents the annular convex portion and the closed end surface from rolling. This can also contribute to improving the wear resistance of the abutting portion of the valve-side stopper.

According to the second feature of the present invention, the annular protrusion is provided with three or more notches at equal intervals, so that when the coil is cut off, the annular protrusion comes into contact with the valve-closing stopper. It equalizes the impact force and the sticking force due to the fuel oil film over the entire circumference of the annular convex portion, contributing to suppressing bouncing of the movable core, improving valve opening response, and improving durability.

According to the third feature of the present invention, the notch is formed so as to become wider toward the outside in the radial direction of the annular convex portion, so that the inner surface of the notch and the outer peripheral edge of the annular convex portion The impact resistance of the corners can be ensured by avoiding sharp corners.

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 view of part 2 of FIG. 1 showing a closed state of the fuel injection valve. FIG. 3 is a sectional view taken along line 3-3 in FIG. 2. Correspondence diagram with Fig. 2 showing the open state of the above fuel injection valve FIG. 3 is a schematic diagram showing a state in which the movable core contacts a valve-closing stopper in an inclined posture when the fuel injection valve is closed;

Embodiments of the present invention will be described with reference to the accompanying FIGS. 1 to 5.

First, in FIG. 1, a cylinder head 5 of an internal combustion engine E is provided with a mounting hole 7 that opens into a combustion chamber 6, and an electromagnetic fuel injection valve I of the present invention that can inject fuel toward the combustion chamber 6 is installed. 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-shaped yoke part 12a integrally in its axially intermediate part, and is accommodated in an annular recess 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 adjacent to the orifice member 24 on the downstream side 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 a support (not shown) provided upright on the cylinder head 5 with a fastener such as a bolt.

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 of the non-magnetic cylindrical body 13 is fitted to 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 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.

As shown in FIGS. 1 to 3, a valve-opening side stopper 48 disposed within the fixed core 14 is fixed to the rod 43. This 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.

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.

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.

An annular valve-closing stopper 49 facing the outer peripheral front end surface of the movable core 41 is press-fitted and fixed to the inner peripheral surface of the magnetic cylindrical body 12 . To position the valve-closing stopper 49, an annular positioning step 47 is formed on the inner periphery of the magnetic cylinder 12 to support the front end surface of the outer peripheral portion of the valve-closing stopper 49.

An auxiliary spring 55 is provided between the movable core 41 and the flange 48a of the valve-opening stopper 48 for biasing the movable core 41 toward the valve-closing stopper 49. The set load of this auxiliary spring 55 is set smaller than that of the valve spring 54.

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.

Therefore, when the valve body 40 is in the valve-closing position and the movable core 41 is in the abutment position with the valve-closing stopper 49, the suction surface 14a of the fixed core 14 and the suction surface 41a of the movable core 41 are in contact with each other. An interval corresponding to the opening/closing stroke of the valve body 40 is ensured between them, and the front end of the shaft portion 48b of the valve-opening side stopper 48 occupies an intermediate position in the interval. 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 attracts the fixed core 14 with the valve-opening side stopper 48. This is the timing to do so.

As clearly shown in FIGS. 2 and 3, an annular convex portion 50 concentric with the movable core 41 is provided on the front end surface of the movable core 41 so as to be able to come into contact with the flat rear end surface of the valve-closing side stopper 49. . The annular convex portion 50 is formed to follow the annular convex curved surface Ta' on the front end side of the virtual torus T, which is set concentrically with the movable core 41. At this time, the center O of the small circle Ta of the virtual torus T is set close to the outer circumference of the movable core 41 so that the apex 50a of the annular convex portion 50 is close to the outer circumference of the movable core 41. Note that in FIG. 2, the symbol R indicates the radius of the great circle of the virtual torus T.

The annular convex portion 50 is provided with three or more notches 51 at regular intervals, which extend across the apex 50a and become wider toward the outside in the radial direction. In this case, it is desirable that both inner surfaces of each notch 51 be formed along the radius line s of the movable core 41, as shown in the illustrated example.

Furthermore, a truncated conical recess 59 is provided on the front end surface of the movable core 41 and continues to the inner peripheral edge of the annular convex portion 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 fluctuations 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. Eliminate or reduce the impact of

On the other hand, as shown in FIG. 2, in such a valve-closing state, the movable core 41 is held in contact with the valve-closing stopper 49 by the set load of the auxiliary spring 55, and there is no space between the movable core 41 and the fixed core 14. The predetermined distance is maintained.

When the coil 32 is energized in such a closed state, the movable core 41 is attracted to the fixed core 14 due to the magnetic force generated between the fixed core 14 and the movable core 41, so first, while compressing the auxiliary spring 55, It slides backward on the rod 43 and comes into contact with the valve opening side stopper 48. That is, when the movable core 41 initially moves, it approaches the fixed core 14 while quickly compressing the auxiliary spring 55, which has a smaller set load than the valve spring 54, and rapidly increases the suction force from the fixed core 14, so that it moves at an accelerated pace. and comes into contact with the valve opening side stopper 48.

Then, as shown in FIG. 4, the movable core 41 immediately moves further rearward against the large set load of the valve spring 54 while being accompanied by the valve-opening side stopper 48, and moves toward the suction surface of the movable core 41. 14a.

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 coil 32 is de-energized, the valve-opening side stopper 48 is pushed by the biasing force of the valve spring 54, so the valve-opening side stopper 48, together with the valve body 40, immediately moves toward the valve seat 27 side. , the valve portion 42 is seated on the valve seat 27, the valve is closed, and fuel injection from the fuel injection hole 28 is stopped. 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 pressed by the urging force of the auxiliary spring 55 and received by the valve-closing stopper 49 . At this time, the annular convex portion 50 on the front end surface of the movable core 41 comes into contact with the flat rear end surface of the valve-closing stopper 49. At this time, a fuel oil film is generated between the annular convex portion 50 of the movable core 41 and the flat rear end surface of the valve-closing side stopper 49, and the thickness of the fuel oil film varies from the apex 50a of the annular convex portion 50. It increases radially outward and inward, causing the sticking force to gradually decrease. Further, the sticking force of the abutting portion is reduced by the area of the notch 51 on the annular convex portion 50. Therefore, by appropriately setting the radius of curvature of the annular convex portion 50, that is, the radius r of the small circle, and by appropriately setting the area (number and width) of the notches 51, the sticking force can be controlled as desired, and the movable core It is possible to satisfy both the bouncing suppression and the improvement in valve opening response of No. 41.

Furthermore, when the movable core 41 comes into contact with the valve-closing side stopper 49 in an inclined position as shown in FIG. One point P of the convex portion 50 rollably contacts the flat rear end surface of the valve-closing stopper 49.

At this time, in particular, the apex 50a of the annular convex portion 50 is arranged near the outer periphery of the front end surface of the movable core 41, so that the apex 50a occupies a large diameter position close to the outer diameter of the movable core 41. Therefore, the contact point P, that is, the fulcrum P is located near the outer periphery of the movable core 41, and with a large arm length L between the fulcrum P and the central axis Y of the auxiliary spring 55, the auxiliary spring 55 The urging force causes a large return moment M to act on the movable core 41. Furthermore, since the fulcrum P can roll on the flat rear end surface of the valve-closing stopper 49, the movable core 41 can quickly return to the proper posture in which the entire annular convex portion 50 contacts the valve-closing stopper 49. This not only contributes to suppressing bouncing of the movable core 41, but also improves the abrasion resistance of the contact portion of the annular convex portion 50 and the valve-closing stopper 49.

Suppressing the bouncing of the movable core 41 means that the bouncing of the movable core 41 can be converged by the time of the next energization of the coil 32, and predetermined fuel injection characteristics can be stabilized.

Further, each of the notches 51 in the annular convex portion 50 is formed to become wider toward the outside in the radial direction of the annular convex portion 50, so that the inner surface of the notch 51 and the outer peripheral edge of the annular convex portion 50 By avoiding the angle θ of the corner 60 formed by the angle θ from becoming an acute angle, the impact resistance of the corner 60 can be ensured.

Furthermore, since the three or more notches 51 are provided at equal intervals in the annular protrusion, when the coil 32 is cut off, the contact impact force of the annular protrusion 50 against the valve closing side stopper 49 and the fuel The sticking force due to the oil film is equalized over the entire circumference of the annular convex portion 50, which can contribute to suppressing bouncing of the movable core, improving valve opening response, and improving durability.

In addition, the truncated conical recess 59 provided on the front end surface of the movable core 41 in series with the inner circumferential edge of the annular convex portion 50 prevents the magnetic path formed in the movable core 41 from being constricted when the coil 32 is energized. This can contribute to reducing the weight of the movable core 41 and, by extension, improving the responsiveness of the movable core 41.

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.

I...Electromagnetic fuel injection valve T...Virtual torus Ta...Small circle Ta' of virtual torus...Annular convex curved surface O...Small circle center r of virtual torus...Virtual Small circle radius R of the torus...large circle radius 9 of the virtual torus...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 convex portion 50a... Apex 51... Notch 54... Valve spring 55...Auxiliary spring 60...Corner part

Claims (3)

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) that is slidably fitted to the inner periphery of the valve housing (9) and the outer periphery of the rod while facing the surface thereof, and allows fuel to flow within the valve housing (9); When the coil (32) is energized, the movable core (41), which is fixed to the rod (43) and is attracted to the fixed core (14), pushes and opens the valve body (40). a valve-opening side stopper (48); an annular valve-closing side stopper (49) that faces the front end surface of the movable core (41) and fits and is fixed to the inner circumferential surface of the valve housing (9); A valve spring (54) biases the valve body (40) in the valve closing direction, and a valve spring (54) that moves the movable core (41) away from the valve opening side stopper (48) when the coil (32) is not energized. An electromagnetic fuel injection valve including an auxiliary spring (55) that urges the valve-closing stopper (49) to come into contact with the valve-closing side stopper (49),
An annular convex portion (50) concentric with the movable core (41) is provided on the front end surface of the movable core (41) so as to be able to come into contact with the flat rear end surface of the valve-closing side stopper (49). The convex portion (50) is formed following the annular convex curved surface (Ta') of the virtual torus (T) that is set concentrically with the movable core (41), and the annular convex portion (50) includes An electromagnetic fuel injection valve characterized in that a notch (51) is provided across the apex (50a). The electromagnetic fuel injection valve according to claim 1, wherein the annular convex portion (50) is provided with three or more of the notches (51) at equal intervals. The electromagnetic fuel injection valve according to claim 1 or 2, wherein the notch (51) is formed to become wider toward the outside in the radial direction of the movable core (41).