JPH10159672A - Fuel injection device of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the fuel injection device of an engine which can prevent the deformation of the ball of a ball valve which is provided in a discharge passage to discharge the fuel invaded in a spring chamber, when the ball strikes against the wall surface of a hollow housing the ball. SOLUTION: Between a fuel feeding main body 5 and a spacer main body 81, an elastic plate 100 as a shock ansorbing member is provided so as to be held between the lower surface 92 of the fuel feeding main body 5 and the upper surface 93 of the spacer main body 81. When the fuel which has invaded in a spring chamber is discharged through a discharge passage 83 to a fuel camber in the operating time of a booster piston, a ball 94 is going to strike against the spacer main body 81 side strongly, but since the elastic plate 100 absorbs the striking energy of the ball 94, the deformation of the ball 94 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for an engine, which boosts fuel in a booster chamber supplied from a common rail by a booster piston.

[0002]

2. Description of the Related Art Conventionally, as a hydraulically operated electronically controlled fuel injection device for an engine, there have been disclosed, for example, JP-A-6-294362 and JP-A-6-511524. These fuel injection devices variably control the fuel flow rate characteristics of a hydraulically operated injector during the fuel injection stroke of the engine or enable quick start. For example, as shown in FIG. It has a structure.

[0003] As shown in FIG. 9, a fuel injection device 1 includes a main body having a hollow hole and an injection hole 13, and a case 6 having a gap formed so as to form a fuel chamber 20 outside the main body. It is configured. The main body of the fuel injection device 1 includes a nozzle main body 2 having a hollow hole 46 and having an injection port 13 formed therein, a fuel supply main body (plunger barrel) 5 forming a pressure intensifying chamber 7, and a nozzle main body 2 and a fuel supply main body 5. The hollow spacer body 21 having the spacer body 81 and the hollow hole 29 located therebetween, the injector body 4 having the pressure chamber 8 to which the high-pressure hydraulic oil is supplied, and the drain groove 39 and the drain passage 38 serving as leak passages It comprises a solenoid body 3 provided with a solenoid valve 16.
The case 6 surrounds the nozzle main body 2, the spacer main body 81, the hollow spacer main body 21, and the fuel supply main body 5 to form the fuel chamber 20. In order to form the fuel chamber 20 formed between the case 6 and the main body, one end of the case 6 is sealed by being locked on the contact surface 14 of the step portion of the nozzle main body 2 and the other end is connected to the injector main body 4. Is sealed by a fitting surface 80 screwed into the connector. A fuel supply port 11 and a fuel discharge port 12 formed in the case 6 are opened in the common rail 51, and fuel is constantly supplied from the common rail 51 to the fuel chamber 20.

[0004] The fuel injection device 1 is for increasing the pressure of the fuel supplied from the fuel chamber 20, a pressure increasing chamber 7 formed in a fuel supply main body 5, and for supplying fuel from the pressure increasing chamber 7 to the injection port 13. , Spacer body 81, hollow spacer body 21
A fuel passage 22 formed in the nozzle body 2, a needle valve 23 slidably held in a hollow hole 46 of the nozzle body 2 to open the injection port 13 by fuel pressure, and a pressure increasing chamber for increasing the pressure of the fuel in the pressure increasing chamber 7. The pressure piston 9 includes a pressure chamber 8 to which high-pressure hydraulic oil for supplying high pressure is supplied to an end of the pressure-increasing piston 9, and a solenoid valve (control valve) 16 for controlling the supply of the high-pressure hydraulic oil to the pressure chamber 8. ing.

The return spring 18 is disposed in a hollow hole 29 formed in the hollow spacer body 21 and
A spring force is applied to the needle valve 23 in a direction to close the needle valve 3. One end of the return spring 18 contacts the upper end of the needle valve 23,
The other end is in contact with the spacer body 81. The hollow spring chamber 30 formed by the hollow hole 26 formed in the injector main body 4 is formed between the end face of the large-diameter portion 25 of the pressure-intensifying piston 9 and the end face of the fuel supply main body 5. A return spring 17 for urging the pressure-intensifying piston 9 toward the pressure chamber 8 is disposed in the spring chamber 30. In a hollow hole 85 formed in the injector main body 4, a return spring 19 for urging the solenoid valve 16 on the side where the operating oil is cut is arranged. The spring chamber 30 in which the pressure-intensifying piston 9 is disposed communicates with the fuel chamber 20 through a discharge path 83 formed in the fuel supply main body 5 and a ball valve 84 disposed in the discharge path 83. Normally, the leaked fuel enters the spring chamber 30 and is in the same state as the fuel pressure in the fuel chamber 20.
A void is removed from zero.

The pressure-intensifying piston 9 has a small-diameter portion 24 which is a plunger that forms a part of the pressure-increasing chamber 7 at the lower end surface, a part of the pressure chamber 8 that is formed at the upper end surface, and a hollow hole 26 of the injector body 4. , And a guide ring portion 41 that hangs down from the entire periphery of the outer peripheral portion of the large diameter portion 25 and forms a sliding surface that slides on the inner surface of the hollow hole 26. The guide ring portion 41 has a function of stabilizing the vertical movement of the pressure-intensifying piston 9. Small-diameter portion 2 of booster piston 9
4 reciprocates in a hollow hole 42 formed in the fuel supply main body 5, and the large diameter portion 25 reciprocates in a hollow hole 26 formed in the injector main body 4. A seal member 44 is disposed in the hollow hole 26 formed in the injector body 4, and seals a gap between the pressure-intensifying piston 9 and the hollow hole 26 with the seal member 44. The spring chamber 30 and the pressure chamber 8 are shut off so that the working oil does not leak into the spring chamber 30.

[0007] At the end of the hollow hole 42 formed in the fuel supply main body 5, a pressure increasing chamber 7 is formed. The fuel is supplied to the pressure intensifying chamber 7 from the fuel chamber 20 through the hollow spacer body 2.
1 through the fuel passage 37 formed in the spacer body 81. In the fuel passage 35,
A check valve 36 is incorporated to prevent the high pressure fuel in the pressure intensifying chamber 7 from flowing back into the fuel chamber 20. Also,
The fuel whose pressure has been increased in the pressure increasing chamber 7 is supplied to the injection port 13 through a fuel passage 22 formed in the spacer body 81, the hollow spacer body 21, and the nozzle body 2. A fuel passage is formed between the nozzle body 2 and the needle valve 23, and the needle valve 2
The needle valve 23 is lifted by applying a high fuel pressure to the tapered surface 45 at the end of the needle 3. The needle valve 23 is slidably held in the hollow hole 46 of the nozzle body 2, lifted by fuel pressure, and opens the injection port 13.

The pressure-increasing piston 9 has a flat surface 73 in which an outer peripheral portion of a top surface 65 of the large-diameter portion 25 facing the pressure chamber 8 is cut off.
Is formed. The wall surface of the injector body 4 forming the pressure chamber 8 is formed as a flat surface 72 parallel to the top surface 65 of the pressure increasing piston 9. Therefore, in the pressure chamber 8, a narrow annular gap 74 is formed between the flat surface 73 of the pressure-intensifying piston 9 and the flat surface 72 of the injector body 4. The pressure-increasing piston 9 has a top surface 6.
The central projection of 5 is in contact with the flat surface 72 of the injector body 4 by the spring force of the return spring 17.

In the fuel injection device 1, a spring chamber 30 accommodating the return spring 17 is formed in a hollow hole 26 formed in the injector body 4 in which the large-diameter portion 25 of the pressure-intensifying piston 9 and the guide ring portion 41 slide. Have been. Intensifier piston 9 and hollow hole 26 in injector body 4
Is sealed by a seal member 44 disposed between the large diameter portion 25 and the hollow hole 26, so that leakage of fuel from the spring chamber 30 to the pressure chamber 8 is prevented. The fuel that has entered the spring chamber 30 is configured to be discharged to the fuel chamber 20 through a discharge path 83 formed in the fuel supply main body 5. Booster piston 9
In the spring chamber 30 in which the return spring 17 is disposed, the clearance 28 around the plunger of the small diameter portion 24, that is, the sliding surface between the hollow hole 42 of the fuel supply body 5 and the outer peripheral surface of the small diameter portion 24, and the injector body 4 and fuel supply body 5
The fuel from the fuel chamber 20 leaks and penetrates through the gap 48 between the contact surfaces. The fuel that has entered the spring chamber 30 is discharged to the fuel chamber 20 through the discharge path 83. Since the ball valve 84 is provided in the discharge path 83, the fuel is prevented from flowing backward from the fuel chamber 20 to the spring chamber 30 through the discharge path 83. Normally, a space corresponding to the stroke of the pressure-intensifying piston 9 is formed in the spring chamber 30, and fuel enters. Then, when the fuel enters to such an extent that the empty space in the spring chamber 30 becomes equal to or less than the stroke of the booster piston 9, the spring chamber 30 in the hollow hole 26 is reciprocated with the booster piston 9.
Existing in the fuel chamber 20 through the discharge passage 83
, But the backflow is prevented by the operation of the ball valve 84.

FIG. 8 shows a known fuel supply system for an engine in which the fuel injection device 1 is incorporated. In the fuel supply system, a fuel injection device 1 is provided for each cylinder of the engine. The fuel injection device 1 is provided with a common rail 51 which is a common passage for supplying fuel. The fuel in the fuel tank 52 is supplied to the common rail 51 through the fuel filter 54 by the driving of the fuel pump 53. The common rail 51 communicates with each fuel injection device 1 and has a fuel recovery passage 55
Through the fuel tank 52. That is, the fuel injection device 1 is disposed on the common rail 51 in which fuel at a predetermined pressure is constantly supplied to the fuel supply port 11 and the fuel discharge port 12 thereof.

The fuel injection device 1 is configured to supply a high-pressure working fluid, that is, working oil, to the pressure chamber 8 to increase the fuel pressure. The fuel injection device 1 is connected to the high-pressure oil manifold 56, respectively. Oil from an oil reservoir 57 is supplied to the high-pressure oil manifold 56 through an oil supply path 61 by operation of an oil pump 58, and an oil cooler 59 and an oil filter 60 are provided in the oil supply path 61. The oil supply passage 61 branches into a lubrication system passage 67 leading to the oil gallery 62 and a working oil system passage 66 supplied to the pressure chamber of the fuel injection device 1. A high-pressure oil pump 63 is provided in the working oil system passage 66, and the supply of oil from the high-pressure oil pump 63 to the high-pressure oil manifold 56 is controlled via a flow control valve 64. The controller 50 is configured to control the flow control valve 64 and control the solenoid 10 of the fuel injection device 1. The controller 50 receives, as the operating state of the engine, the engine speed detected by the rotation sensor 68, the accelerator opening detected by the load sensor 69, and the crank angle detected by the position sensor 70.
The controller 50 includes a high-pressure oil manifold 5.
The working oil pressure of the high-pressure oil manifold 56 detected by the pressure sensor 71 installed at 6 is input.

In the fuel injection device 1, the opening and closing operation of the injection port 13 by the needle valve 23 is performed by controlling the solenoid 10. When the solenoid 10 is energized by a command from the controller 50, the armature 32 is attracted. The solenoid valve 16 fixed to the armature 32 lifts against the spring force of the return spring 19. When the solenoid valve 16 is lifted, the passage 33 formed between the tapered surface 86 of the solenoid valve 16 and the valve seat 87 of the injector body 4 opens, and high-pressure operating oil is formed in the injector body 4 from the high-pressure oil manifold 56. The pressure is supplied to the pressure chamber 8 through the supply path 31 and the passage 34. When high-pressure hydraulic oil is supplied to the pressure chamber 8, the top surface 65 of the large-diameter portion 25 of the pressure-intensifying piston 9 and the injector body 4
Annular gap 7 formed between a wall surface (flat surface) 72 of
4 is supplied with high-pressure operating oil, and the pressure-increasing piston 9 is energized with operating pressure. On the other hand, the fuel of the common rail 51 is supplied from the supply port 11 formed in the case 6 to the fuel chamber 20, and then the fuel passage 37 formed in the hollow spacer body 21 and the fuel formed in the spacer body 81 from the fuel chamber 20. The pressure is supplied to the pressure increasing chamber 7 through the passage 35.

When the pressure-increasing piston 9 is lowered by the pressure of the working oil in the pressure chamber 8, the fuel passage 35 is closed by the check valve 36, and the pressure in the pressure-increasing chamber 7 is increased. Booster chamber 7
When the pressure of the fuel is increased, the fuel pressure is
The needle valve 23 is lifted against the spring force of No. 8. Further, when the urging force of the solenoid 10 to the solenoid valve 16 is released, the solenoid valve 16 is lowered by the spring force of the return spring 19, and the drain groove 3 provided in the solenoid valve 16 is provided.
9 is opened, and the high-pressure hydraulic oil in the pressure chamber 8 is
And discharged through the drain passage 38. When the high-pressure hydraulic oil in the pressure chamber 8 is discharged, the pressure-intensifying piston 9 returns to the original pressure by the spring force of the return spring 17, and the pressure in the pressure-increasing chamber 7 becomes equal to the pressure of the fuel chamber 20, and is applied to the needle valve 23. The fuel pressure is reduced, and the taper surface 45 of the needle valve 23 is seated on the valve seat of the nozzle body 2 by the spring force of the return spring 18 and the injection port 13 is closed.

[0014]

As described above, when the fuel in the spring chamber 30 increases and the vacant space in the spring chamber 30 decreases to a value equal to or less than the stroke of the pressure-intensifying piston 9, as described above, the surplus fuel is removed. , Booster piston 9
The fuel existing in the spring chamber 30 in the hollow hole 26 is discharged to the fuel chamber 20 through the discharge path 83 with the reciprocation of the fuel cell. The discharge of the fuel is performed by a ball valve 84 provided in the discharge passage 83 against the fuel pressure in the fuel chamber 20.
This is done by pushing open.

The fuel is supplied to the fuel chamber 2 through the discharge passage 83.
0, the ball 94 of the ball valve 84
Is caused to collide with the upper surface 93 of the spacer body 81 which is a part of the wall surface forming the hollow portion for accommodating the ball, and the ball 94 is deformed while repeating the collision, thereby impairing the function of the ball valve 84. May be Ball 94
When such deformation occurs, the fuel flows back from the fuel chamber 20 to the spring chamber 30 through the gap between the deformed portion of the ball 94 and the valve seat and is filled. As a result, it is necessary to discharge a large amount of fuel when the pressure-intensifying piston 9 operates, and the discharge work of the pressure-intensifying piston 9 increases, so that the target fuel injection amount cannot be obtained in the same manner as described above. In this case, a situation occurs in which the pressure-intensifying piston 9 cannot stroke and fuel is not injected.

[0016]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems, and a fuel injection device for an engine in which fuel in a pressure boosting chamber supplied from a common rail is boosted by a pressure boosting piston and injected. In the above, when the fuel that has entered the spring chamber is discharged to the fuel chamber, even if the ball that is the valve element of the ball valve provided in the discharge path lifts from the valve seat and collides with the wall surface when the valve is opened, An object of the present invention is to provide a fuel injection device for an engine that can prevent a ball from deforming and can secure a target fuel injection amount.

According to the present invention, a pressure boosting chamber formed in a main body to which fuel from a common rail is supplied is driven by a working fluid supplied to a pressure chamber formed in the main body to increase the pressure of the fuel in the pressure boosting chamber. A pressure-intensifying piston, a needle valve slidably housed in the main body for opening and closing a nozzle for injecting fuel from the pressure-intensifying chamber by fuel pressure, and a pressure chamber for a working fluid that drives the pressure-increasing piston. A control valve for controlling the supply of a fuel supply port, and a case in which a fuel supply port and a fuel discharge port are formed on a periphery of the main body to form a fuel chamber and open to the common rail. The pressure increasing chamber comprises a small diameter portion forming a part of a wall surface of the pressure increasing chamber, and a large diameter portion forming a part of a wall surface of the pressure chamber, wherein the large diameter portion of the pressure increasing piston slides and returns. Spring arranged A spring chamber and a discharge path communicating the spring chamber with the fuel chamber and having a ball valve provided therein, and a hollow portion forming a part of the discharge path accommodates the ball of the ball valve. And
The present invention relates to a fuel injection device for an engine, wherein a shock-absorbing member is provided on a wall surface of the hollow portion where the ball collides.

Since the fuel injection device of this engine is constructed as described above, the ball valve opens based on the difference between the fuel pressure in the spring chamber and the fuel pressure in the fuel chamber, and the fuel valve in the spring chamber is opened. Will be discharged to the fuel chamber through the discharge path, but when the ball valve opens and closes, the ball will collide at a high speed. The impact energy is relieved by the shock absorbing member, that is, converted into deformation of the shock absorbing member and released as its distortion energy, and is not spent on deformation of the ball. Therefore, the deformation of the ball as the valve body is prevented.

The main body is formed by combining a plurality of divided main bodies. That is, the main body slidably accommodates the injector main body in which the pressure chamber and the spring chamber are formed, the fuel supply main body in contact with the injector main body and in which the pressure increasing chamber and the discharge passage are formed, and the needle valve. A spacer body having a nozzle body formed therein, a fuel passage disposed between the fuel supply body and the nozzle body and communicating the fuel chamber with the pressure increasing chamber, and a fuel passage communicating the pressure increasing chamber with the injection port. It has.

The hollow portion is constituted by a hollow hole formed in the fuel supply main body on the spacer main body side. That is, the fuel supply main body and the spacer main body are disposed to face each other, and the hollow hole is preferably formed as a part of a discharge path formed in the fuel supply main body from the viewpoint of manufacturing and cost. . Therefore, it is preferable that the hollow portion is constituted by a hollow hole formed in the fuel supply main body facing the spacer main body.

When the hollow portion in which the ball valve is disposed is formed of a hollow hole as described above, when the ball valve is opened, the ball lifts from the valve seat and collides with the opposing wall surface. Since the colliding wall surface is a surface portion of the spacer main body facing the hollow hole, the cushioning member can be an elastic plate interposed between opposing surfaces of the fuel supply main body and the spacer main body. Further, the buffer member may be a leaf spring formed by cutting and raising a plate interposed between opposing surfaces of the fuel supply main body and the spacer main body. Also,
The buffer member may be a resin body or a rubber body fitted in a hole formed in a plate interposed between the opposing surfaces of the fuel supply main body and the spacer main body. Further, the cushioning member may be a coil spring disposed in the hollow portion.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an engine fuel injection device according to the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of the entire fuel injection device for an engine according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of a main part of FIG. The fuel injection device of the engine shown in FIG. 1 has the same configuration as the fuel injection device of the conventional engine shown in FIG. 9 except that a buffer member is interposed between the fuel supply main body and the spacer main body. Since they have the same functions, the same components are denoted by the same reference numerals, and redundant description will be omitted. In addition, since there is no change in the basic fuel injection operation as the fuel injection device of the engine, the overlapping description of the fuel injection operation is omitted.

The fuel injection device of this engine is applied by being incorporated in a fuel supply system shown in FIG. 8, and is arranged in each cylinder of the engine. In this embodiment, one fuel injection device will be described with reference to FIG. The fuel injection device 1 is in a state where the fuel supply port 11 and the fuel discharge port 12 are opened in the common rail 51 in the fuel supply system, and the fuel on the common rail 51 is always supplied. In the fuel injection device of this engine, when the pressure-intensifying piston 9 is driven by the working oil supplied to the pressure chamber 8, the fuel that has entered the spring chamber 30 in which the return spring 17 is accommodated passes through the discharge passage 83. It may be discharged to the fuel chamber 20.

The details of the ball valve 84 will be described with reference to FIG. That is, the ball valve 84 is a ball check valve having the ball 94 that can be seated on the tapered valve seat 95. A hollow portion 96 is formed in the fuel supply body 5 as a part of the discharge path 83, and the hollow portion 96 accommodates the ball 94 of the ball valve 84. In the closed state in which the ball 94 is seated on the valve seat 95, the fuel flows from the hollow portion 96 to the discharge path 83, that is, the fuel flows from the fuel chamber 20 (see FIG. 1) to the spring chamber 30 (see FIG. 1). Is blocked, and the discharge path 83 is opened when the ball 94 is lifted from the valve seat 95.
Of the fuel through the hollow portion 96, ie, the spring chamber 3
Fuel flow from 0 to the fuel chamber 20 is allowed.
The ball 94 is suddenly lifted from the valve seat 95 by the high pressure in the spring chamber 30 which overcomes the pressure in the fuel chamber 20, and the upper surface 93 of the opposing spacer body 81 is lifted.
Try to collide towards.

In the embodiment shown in FIGS. 1 and 2, between the fuel supply main body 5 and the spacer main body 81, a lower surface 92 of the fuel supply main body 5 and an upper surface of the spacer main body 81, which are opposite surfaces of both. An elastic plate 100 as a buffer member is provided so as to be sandwiched between the elastic plate 100 and the elastic member 93. According to this embodiment, even if the ball 94 tries to collide with the spacer body 81, the elastic plate 100 absorbs and reduces the collision energy of the ball 94, so that the deformation of the ball 94 can be prevented.

FIGS. 3 and 4 show another embodiment of the fuel injection system for an engine according to the present invention. FIG. 3 is an enlarged sectional view of a main part thereof, and FIG. 4 is an enlarged perspective view of a cushioning member. Note that the configuration of the fuel injection device itself is the same as that shown in FIG. 1, and a description thereof will not be repeated. The structure of the ball valve 84 itself is not different from the structure shown in FIG. In the embodiment shown in FIGS. 3 and 4, between the fuel supply main body 5 and the spacer main body 81, between the lower surface 92 of the fuel supply main body 5 and the upper surface 93 of the spacer main body 81,
A thin plate 101 is interposed. The thin plate 101 may be a thin metal plate, but is not limited thereto, and may be a composite material. When the case 6 and the injector main body 4 are connected to each other, the thin plate 101 is strongly sandwiched between the fuel supply main body 5 and the spacer main body 81. The portion facing the hollow portion 96 of the thin plate 101 is separated from the main body portion 102 of the thin plate 101 by the hollow portion 9.
The plate spring 103 is cut and raised toward the sixth side. The leaf spring 103 constitutes a buffer member according to the present invention. When the ball valve 84 opens, the ball 94 moving at a high speed collides with the leaf spring 103 of the thin plate 101, and the kinetic energy of the ball 94 is gradually absorbed by the elastic deformation of the leaf spring 103. Therefore, the collision of the ball 94 with the leaf spring 103 does not become an impact that deforms the ball 94.

FIGS. 5 and 6 show another embodiment of the fuel injection system for an engine according to the present invention. FIG. 5 is an enlarged sectional view of a main part thereof, and FIG. 6 is an enlarged perspective view of a cushioning member. Also in this embodiment, the configuration of the fuel injection device 1 itself is the same as that shown in FIG. 1, and the structure of the ball valve 84 is the same as the example shown in FIGS. Is omitted. Fuel supply body 5
Supply body 5, which is a surface facing the spacer body 81 and the fuel supply body 5
Between the lower surface 92 of the spacer body and the upper surface 93 of the spacer body 81.
A thin plate 104 is interposed. The thin plate 104 may be a metal thin plate or an elastic thin plate, and is not limited thereto, and may be a composite material. When the case 6 and the injector main body 4 are connected, the thin plate 104 is strongly sandwiched between the fuel supply main body 5 and the spacer main body 81. A portion facing the hollow portion 96 of the thin plate 104 is provided with the spacer body 8.
A large-diameter hole 105 is formed on one side, and a small-diameter hole 106 is formed on the hollow part 96 side so as to penetrate the thin plate 104. Large-diameter portions 108 for holes 105 and 106 respectively
And a resin body or rubber body 107 composed of a large diameter portion 108 and a small diameter portion 109 having an integral structure is fitted and arranged. Small diameter part 1
Reference numeral 09 slightly protrudes toward the hollow portion 96 of the thin plate 104, and the ball 9 moving at high speed toward the thin plate 104.
4 to cushion the ball 94 to prevent the ball 94 from being deformed.

FIG. 7 shows still another embodiment of the engine fuel injection device according to the present invention. FIG. 7 is an enlarged sectional view of the main part. Also in this embodiment, the configuration of the fuel injection device 1 itself is the same as that shown in FIG. 1, and the structure of the ball valve 84 is the same as the example shown in FIG. 2, FIG. 3 or FIG. Is also omitted. In this embodiment, the coil spring 1 is disposed on the upper surface 93 of the spacer body 81 so as to be disposed in the hollow portion 96.
10 are provided. The direction in which the central axis of the coil spring 110 extends is selected so as to coincide with the lift direction of the ball 94. Note that the coil spring 110 need not always be in contact with the ball 94. Ball 94
When it is attempted to collide with the upper surface 93 of the spacer body with a force based on the fuel pressure difference between the spring chamber 30 and the fuel chamber 20, the ball 94 collides with the coil spring 110 in a cushioning manner, and the coil spring 110 The contraction reduces the collision energy and prevents the ball 94 from being deformed.

[0029]

As described above, in the fuel injection device for an engine according to the present invention, the ball valve is provided in the discharge passage of the main body of the fuel injection device, and the ball of the ball valve is provided in the hollow portion forming a part of the discharge passage. And the cushioning member is arranged on the wall surface of the hollow portion where the ball collides, so that when the ball collides with the wall surface of the hollow portion, such as when the ball valve is opened, the collision energy of the buffer member is reduced. It is converted into deformation and released as its distortion energy, and is not spent on deformation of the ball, so that deformation of the ball as a valve body is prevented. Therefore, if the ball is deformed, fuel flows backward from the fuel chamber to the spring chamber through the gap between the deformed portion and the valve seat while the valve is in the closed state, and as a result, the fuel discharge work of the pressure boosting piston increases. It is possible to avoid a situation in which the target fuel injection amount is not obtained or the fuel is not injected due to the inability of the booster piston to stroke, and the target fuel injection amount can be reliably realized.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an engine fuel injection device according to the present invention.

FIG. 2 is an enlarged sectional view of a main part of the fuel injection device for the engine shown in FIG.

FIG. 3 is a main part enlarged sectional view showing another embodiment of the fuel injection device for the engine according to the present invention.

FIG. 4 is an enlarged perspective view of a cushioning member used in the embodiment shown in FIG.

FIG. 5 is an enlarged sectional view of a main part showing another embodiment of the fuel injection device for an engine according to the present invention.

FIG. 6 is an enlarged perspective view of a cushioning member used in the embodiment shown in FIG.

FIG. 7 is an enlarged sectional view of a main part showing still another embodiment of the fuel injection device for an engine according to the present invention.

FIG. 8 is a schematic explanatory view showing a fuel supply system of a fuel injection device for an engine.

FIG. 9 is a sectional view showing a conventional fuel injection device for an engine.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 fuel injection device 2 nozzle body 3 solenoid body 4 injector body 5 fuel supply body 6 case 7 booster chamber 8 pressure chamber 9 booster piston 11 fuel supply port 12 fuel outlet 13 injection port 16 solenoid valve (control valve) 17 return spring Reference Signs List 20 fuel chamber 21 hollow spacer main body 22 fuel passage 23 needle valve 24 small diameter portion 25 large diameter portion 26 hollow hole 28 gap 29 hollow hole 30 spring chamber 35 fuel passage 37 fuel passage 42 hollow hole 45 tapered surface 48 gap 51 common rail 81 spacer body 83 discharge path 84 ball valve 92 lower surface 93 upper surface 94 ball 96 hollow portion 100 elastic plate 101 thin plate 103 leaf spring 104 thin plate 107 resin body or rubber body 110 coil spring

Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02M 61/16 F02M 61/16 X

Claims (7)

[Claims] An intensifying chamber formed in a main body to which fuel from a common rail is supplied, and a pressure intensifier driven by a working fluid supplied to a pressure chamber formed in the main body to increase the pressure of the fuel in the intensifying chamber. A piston, a needle valve slidably housed in the main body for opening and closing a nozzle for injecting fuel from the pressure boosting chamber by fuel pressure, and supply of a working fluid for driving the pressure boosting piston to the pressure chamber. And a control valve disposed on the outer periphery of the main body to form a fuel chamber and having a fuel supply port and a fuel discharge port opened to the common rail. The pressure chamber comprises a small-diameter portion forming part of a wall surface of the pressure chamber, and a large-diameter portion forming part of a wall surface of the pressure chamber. The main body slides on the large-diameter portion of the pressure-intensifying piston, and a return spring is provided. Sprit placed And a discharge path provided with a ball valve and communicating the spring chamber with the fuel chamber, and the ball of the ball valve is housed in a hollow portion forming a part of the discharge path. A fuel injection device for an engine, wherein a cushioning member is provided on a wall surface of the hollow portion where the ball collides. 2. The injector body in which the pressure chamber and the spring chamber are formed, the fuel supply body in contact with the injector body and in which the pressure boosting chamber and the discharge passage are formed, and the needle valve. A nozzle body in which the nozzle is slidably accommodated and in which the injection port is formed; a fuel passage disposed between the fuel supply body and the nozzle body to communicate the fuel chamber with the pressure increasing chamber; The fuel injection device for an engine according to claim 1, further comprising a spacer main body in which a fuel passage communicating the pressure chamber and the injection port is formed. 3. The fuel injection device for an engine according to claim 2, wherein the hollow portion is formed by a hollow hole formed in the fuel supply main body on the spacer main body side. 4. The fuel injection device for an engine according to claim 2, wherein the cushioning member is an elastic plate interposed between opposing surfaces of the fuel supply main body and the spacer main body. 5. The fuel injection according to claim 2, wherein the buffer member is a leaf spring formed by cutting and raising a plate interposed between the opposed surfaces of the fuel supply main body and the spacer main body. apparatus. 6. A resin body or a rubber body fitted in a hole formed in a plate interposed between opposing surfaces of the fuel supply main body and the spacer main body. The fuel injection device of the engine according to the above. 7. The fuel injection device for an engine according to claim 2, wherein the cushioning member is a coil spring disposed in the hollow portion.