JPH0932681A - Fuel injection device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To connect a control piston and a needle valve integrally in the axial direction by a connecting member by allowing dislocation in the shaft center direction. SOLUTION: A valve body to open a nozzle hole 50 by fuel pressure is constituted of a control piston 2 to expose its end surface in a balance chamber 35 and a needle valve 3 to open and close the nozzle hole 50. Thereafter, the control piston 2 is supported on a holder main body 1 free to slide, and the needle valve 3 is supported on a nozzle main body 4 free to slide. The control piston 2 and the needle valve 3 are integrally held in the shaft center direction by a connecting member 38 having spring force to allow shaft center dislocation in a direction orthogonal in the shaft center direction. It comes to be unnecessary to conform a shaft center of the control piston 2 and the needle valve 3 in high precision, and the shaft center dislocation is absorbed by the connecting member 38 and smooth sliding is secured.

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 used in an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, in a fuel injection system for a multi-cylinder engine, a fuel injection system (electronically controlled fuel injection system) in which an injection amount and an injection timing are controlled by an electronic circuit, an injection pump, and a common passage There are a common injection system (common rail injection system) that distributes fuel to the combustion chambers, a pressure accumulation type injection system (accumulator injection system) that distributes fuel to each combustion chamber from an injection pump through a common passage and a pressure accumulation chamber, and the like. The fuel injection system itself does not have a pressure accumulating chamber for temporarily accumulating fuel from the injection pump, so the fuel is supplied to each fuel injecting device through a common rail or pressure accumulating chamber that is a common passage. Has been done.

Conventionally, as an electronically controlled fuel injector used in an internal combustion engine, for example, there is one disclosed in Japanese Patent Application Laid-Open No. 1-290960. The electronically controlled fuel injector intermittently injects a high-pressure fuel provided with a valve member into an internal combustion engine, and the movement of the valve member for opening and closing the fuel outlet is different from that of the valve piston. It is controlled by the fuel pressure in the control chamber acting on the opposite side. A cylindrical member surrounds the upper portion of the valve piston. When the solenoid is excited,
The pilot valve opens and then the fuel pressure in the control chamber drops rapidly. The solenoid is mounted in the housing,
In addition to functioning as a high speed actuator for the pilot valve, it also supports the force created by fuel pressure in the control chamber. Further, the needle valve piston is integrally formed with the needle valve, or the portions having different outer diameters are press-fitted or welded to be firmly connected.

Further, as an electromagnetically controlled fuel injection valve used in an internal combustion engine, there is one disclosed in JP-A-1-257754. The opening and closing of the nozzle of the electromagnetically controlled fuel injection valve is controlled by a needle that can move in the axial direction inside a central cavity in the main body. The lower zone of the central cavity forms an injection chamber in which fuel is injected under pressure by a pump through a supply passage formed in the body. The body is provided with an opening for engagement of the supply opening and the centering stopper. The needle is formed by abutting two axial portions (needle valve and control piston) without fixing them in the axial direction, but may be formed in a single piece. The presence of the feed opening requires a cumulative volume of pressurized fuel but a large passage cross-section in the body.

[0005]

[Problems to be Solved by the Invention] Japanese Patent Laid-Open No. 1-290
In the electronically controlled fuel injector disclosed in Japanese Patent Publication No. 960,
Needle valve Not only when the piston and needle valve are constructed as an integral piece, but when both are fixed by pressure fitting or welding, they both lengthen in the longitudinal direction, so the piston guide part and needle valve guide And the seat surface of the tip of the needle valve is centered to hold the piston and the needle valve. Therefore, the piston is held by the holder main body, and the needle valve is held by the nozzle main body, so that the needle valve is held across the holder main body and the nozzle main body even though the needle valve has an integral structure. In the above electronically controlled fuel injector, since the needle valve piston and the needle valve are integrally formed by press-fitting or the like, their diameters are long even if they are thin, and the holder body holds the needle valve piston. Since the needle valve is held by the nozzle body, it is difficult to hold the needle valve piston and the needle valve, which are separate bodies, in the holder body and nozzle body, with their axes aligned. It is very difficult to do this, and because the parts that support the needle valve piston and needle valve are separate parts,
Since machining tolerances are accumulated, it is difficult to ideally keep the axes of both shafts aligned. Moreover, the machinability, productivity, and accuracy assurance of these parts are significantly deteriorated.
Further, there is a problem that the cost becomes high due to the centering and the like when the parts are replaced, especially when the needle valve is replaced.

Further, in the electromagnetically controlled fuel injection valve disclosed in Japanese Patent Laid-Open No. 1-257754, the needle is constructed by abutting the needle valve and the control piston, but such a structure is established. The case where the supply passage is independent and the upper part of the needle valve and the periphery of the control piston are not high pressure chambers. That is, if the upper portion of the needle valve and the area around the control piston are high-pressure chambers, the force of lowering the needle valve acts on the gap between the abutting portions, that is, the abutting portions, so that the needle valve cannot be lifted.

[0007]

The present invention is applied to a fuel injection device of a type in which fuel is supplied through a common rail, that is, a pressure accumulating chamber, which is a common passage, and reciprocates in a main body composed of a holder main body and a nozzle main body. Separately from the needle valve that slidably holds the moving valve body to open and close the injection hole, and the control piston that is held in the holder body and lifts the needle valve according to the fuel pressure in the balance chamber. The present invention relates to a fuel injection device in which a needle valve and a control piston are connected by a connecting member having a spring force, the connecting member allows axial misalignment of the both and is firmly held integrally in the axial direction. .

According to the present invention, there is provided a valve body which reciprocates in a main body having an injection hole for injecting fuel and opens the injection hole by a fuel pressure, and the valve in the main body for accumulating fuel which the valve body penetrates. A fuel chamber formed around the body, a balance chamber for controlling lift of the valve body by a fuel pressure formed by a control sleeve fixed to the body,
And a control piston that drives an on-off valve that opens and closes a discharge passage that releases fuel pressure in the balance chamber, the valve body having an end surface exposed to the balance chamber and penetrating the fuel chamber, and the control piston. A needle valve that opens and closes the injection hole and is connected to the piston with its end faces abutting each other; the main body is connected to the holder main body that slidably supports the control piston in the axial direction; And a nozzle main body having the nozzle hole that slidably supports the needle valve in the axial direction, and the control piston and the needle valve are springs that allow axial misalignment in a direction orthogonal to the axial direction. A fuel injection device for an internal combustion engine, wherein the fuel injection device is integrally held in the axial direction by a connecting member having force. .

Further, the connecting member is composed of a ring that is fitted over the ends of the needle valve and the control piston, and has an annular shape formed at the ends of the needle valve at both ends of the connecting member. An inwardly projecting locking portion is formed to be fitted into the groove and the annular groove formed at the end of the control piston.

Alternatively, the connecting member comprises a split ring that fits over the ends of the needle valve and the control piston and has tongues that engage with each other along the longitudinal slit edges. The connecting member is formed at both ends with inwardly projecting locking portions that respectively fit in the annular groove formed at the end of the needle valve and the annular groove formed at the end of the control piston. ing. Further, an end portion of the tongue portion formed on the connection member is formed as a folded portion bent outward.

Alternatively, the connecting member has a ball connector having a spring force due to a slit provided in one of the needle valve and the control piston, and the ball connector provided in the other one with the spring force. It is composed of a ball fitting hole that can be inserted against.

Alternatively, the connecting member is composed of a ring-shaped spring plate having a notch which is fitted over the ends of the needle valve and the control piston, and the notch of the ring-shaped spring plate. An engaging portion is formed at an edge portion of each of the needle valve and an annular groove formed at an end portion of the control piston, respectively.

Since the fuel injection device is constructed as described above, the axial center deviation between the control piston and the needle valve is absorbed by the spring force of the connecting member, and the machining accuracy in the axial direction for both is high. Accuracy is not required, and both can be assembled and connected with one touch, workability can be improved, and processing cost can be reduced.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a fuel injection device according to the present invention will be described below with reference to the drawings. In the following drawings, parts having the same structure and function are designated by the same reference numerals, and overlapping description will be omitted. First, an embodiment of a fuel injection device according to the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a sectional view showing an embodiment of a fuel injection device according to the present invention, and FIG. 2 is a sectional view showing an essential part of the fuel injection device of FIG.

This fuel injection device is not shown,
It is applied to a common rail injection system or an accumulator injection system, and a common passage or accumulator which is supplied with fuel from an injection pump (hereinafter referred to as common rail 29).
The high-pressure fuel supplied through the above is injected into each combustion chamber provided in the internal combustion engine. The holder body 1 in this fuel injection device is hermetically attached to a hole (not shown) provided in a base such as a cylinder head via a seal member 42. At the lower end of the holder body 1, the nozzle body 4
Is fixed by screwing the sleeve nut 40 into the threaded portion of the holder body 1, and the lower end surface of the holder body 1 and the upper end surface of the nozzle body 4 form a sealing surface 2
Make up 2. The outer peripheral surface of the nozzle body 4 has an upper portion formed in a large diameter portion and a lower portion formed in a small diameter portion.
Is screwed into the threaded portion of the holder body 1 while being fitted to the step surface 55 at the bottom of the nozzle body 4.

A plug mounting hole 45 for mounting the threaded fuel inlet plug 5 is formed in the upper portion of the holder body 1. The fuel inlet plug 5 is screwed into the plug mounting hole 45 of the holder body 1 to be mounted. A solenoid valve mechanism 65 for reciprocating the valve body is fixed to the upper end of the holder body 1 by screwing the sleeve nut 46 into the threaded portion of the holder body 1. Sealing between the solenoid valve mechanism 65 and the holder body 1 and the sleeve nut 46 is performed by the seal members 31 and 32. The fuel from the common rail 29 of the high-pressure fuel supply source is supplied to the fuel injection device through the fuel inlet plug 5. Further, in this fuel injection device, the current of the operation signal from the control unit 34 is supplied to the solenoid type valve mechanism 65 from the terminal 16 through the connector or the harness 13. The solenoid valve mechanism 65 is an actuator (a coil 14 and a solenoid 11 which will be described later) which releases the fuel pressure applied to the valve body through a discharge passage (a fuel passage 26, an orifice 25, a hollow chamber 63 and a fuel return pipe 12 which will be described later). , The solenoid valve 10 and the ball 27).

The fuel inlet plug 5 is screwed into the screw hole 45 formed in the holder body 1. The seal between the holder body 1 and the fuel inlet plug 5 is achieved by the seal member 30. A central through hole 47 is formed in the holder body 1 for penetrating the valve body, and the central through hole 47 is formed.
A supply hole 6 that communicates with the fuel inlet 49 of the fuel inlet plug 5 is formed. Further, a guide portion 66 in which the diameter of the central through hole 47 is reduced is formed substantially in the center of the central through hole 47 of the holder body 1, and the control piston 2 of the valve element penetrates through the guide portion 66 to guide the guide surface. 36 is formed. The central through hole 47 of the holder body 1 forms a fuel chamber 37 which penetrates the central through hole 47 and stores fuel around the control piston 2. Further, the nozzle body 4 is formed with a central through hole 48 into which the needle valve 3 of the valve body communicating with the central through hole 47 is inserted, and an injection hole 50 for injecting fuel into a combustion chamber (not shown). Has been formed.

As described above, the valve body is provided with the fuel chamber 37.
And a needle valve 3 connected to the control piston 2 by a connecting member 38. A fuel chamber 56 communicating with the fuel chamber 37 is formed in a region where the control piston 2 and the needle valve 3 are connected by the connecting member 38.
The needle valve 3 is slidably inserted in the central through hole 48 of the nozzle body 4 in a state of forming a gap 52, and the face surface of the tip portion 41 of the needle valve 3 is formed in the nozzle hole 50 formed in the nozzle body 4.
Is seated on the seat surface on which is formed. A gap 52 formed around the needle valve 3 forms a passage for high pressure fuel. A sliding surface 21 having a gap 52 is formed between the central through hole 48 of the nozzle body 4 and the outer peripheral surface of the needle valve 3. The nozzle hole 50 of the nozzle body 4 is seated in the nozzle hole 50.
The fuel pressure applied to the tapered surface of the tip of the needle valve 3 that opens and closes the valve acts as a force to raise the valve body. The fuel pressure applied to the control piston 2 in the fuel chamber 37 is configured to be zero in total.

The control sleeve 7 is fitted in the central through hole 47 of the holder main body 1 and the fitting surface 19 also serves as a seal.
In addition, the shoulder portion of the control sleeve 7 abuts on the upper step portion of the central through hole 47, and the abutting seal surface 2
3 are formed. Further, an annular chamber 18 is formed between the outer peripheral surface of the control sleeve 7, the holder body 1 and the central through hole 47. Control sleeve 7
Are fixed by a fixing plug 8 having a hollow hole 44 screwed into the threaded portion at the upper end of the holder body 1. A complete seal between the holder body 1 and the control sleeve 7 is achieved by the sealing member 33. Supply hole 1 of the supply passage formed in the annular chamber 18 and the holder body 1.
7 to the fuel inlet 49. A sliding surface 20 into which the control piston 2 is slidably fitted is inserted into a hollow hole portion 54 that opens below the control sleeve 7.
And a balance chamber 35 is formed in the upper part of the hole 54 between the upper surface of the control piston 2 and the upper part of the hole 54. The balance chamber 35 communicates with the annular chamber 18 through the orifice 24. Further, the control sleeve 7 is formed with an orifice 24 which communicates the balance chamber 35 with the supply hole 17, an orifice 25 which communicates with the upper surface of the control sleeve 7, and a fuel passage 26. The balance chamber 35 has a function of applying fuel pressure to the upper surface of the control piston 2 and controlling the lift of the control piston 2.

In the solenoid valve mechanism 65 of this fuel injection device, the control sleeve 7 is attached to the holder body 1
A hollow chamber 63 is formed in the fixed plug 8 that is fixed to the fixed plug 8, and a ball 27 that can open and close the outlet of the orifice 25 is disposed in the hollow chamber 63. The ball 27 is the solenoid 11
It is fixed to the lower end surface of the solenoid valve 10 that moves up and down by the urging force of 1 to form an integral structure. The solenoid 11 is fixed to the holder body 1 by a sleeve nut 46 with the solenoid support member 15 interposed. A coil 14 is provided on the outer peripheral surface of the solenoid 11, and a solenoid valve spring 9 is provided above the solenoid 11, and the solenoid valve spring 9 includes a set screw 6
At 4, the solenoid 11 is set. A current corresponding to a signal from the control unit 34 is supplied to the coil 14 through the terminal 16 and the connector (harness) 13. Energizing the coil 14 energizes the solenoid 11,
The energized solenoid 11 causes the solenoid valve 10 to overcome the spring force of the solenoid valve spring 9 and pull up.

The fuel return pipe 1 extending from the sleeve nut 46 is provided above the solenoid valve mechanism 65.
2 are provided. The fuel return pipe 12 communicates with the hollow chamber 63 through a passage formed on the outer circumference of the solenoid 11. Therefore, the fuel supplied into the balance chamber 35 is supplied from the balance chamber 35 through the fuel passage 26, the orifice 25 and the hollow chamber 63 by the ball 27 integrated with the solenoid valve 10 opening the orifice 25. Is discharged to. That is, the solenoid valve mechanism 6 that constitutes the actuator
When the valve 5 operates, the solenoid valve 1 that constitutes the on-off valve
0 and the ball 27 open the orifice 25, and the fuel pressure in the balance chamber 35 constitutes the discharge passage.
6, orifice 25, hollow chamber 63 and fuel return pipe 1
It is canceled through 2.

In this fuel injection device, the needle valve 3
The return operation for closing the injection hole 50 by means of between the retainer 39 fixed to the lower part of the control piston 2 and the retainer 53 fixed to the step portion 43 in the central through hole 47 of the holder body 1 is performed. This is performed by the return spring 28 provided. The retainer 39 fixed to the lower portion of the control piston 2 is set at a position corresponding to a large diameter portion below the step portion 62 of the central through hole 47 of the holder body 1.

This fuel injection device is characterized by, in particular, the structure in which the control piston 2 constituting the valve body and the needle valve 3 are connected by the connecting member 38 in the above structure. That is, the control piston 2 and the needle valve 3, which form the valve body, are arranged such that their respective end faces abut on the contact surface 57, and a spring force that allows axial misalignment in a direction orthogonal to the axial direction of the two. Connecting member 38 having
Are held integrally in the axial direction. The connecting member 38 is formed of an elastic body such as a leaf spring into a split ring shape, and is elastically deformable in the ring radial direction. An annular groove 58 is formed at the lower end of the control piston 2,
An annular groove 58 is formed at the upper end of the needle valve 3. In addition, beads 59 that form locking portions that project inward are formed at both ends of the connecting member 38. The connecting member 38 is fitted across the ends of the needle valve 3 and the control piston 2, and the bead 59 of the connecting member 38 is fitted in the annular groove 58 of the control piston 2 and the annular groove 58 of the needle valve 3. There is. Therefore, the control piston 2 is held by the holder main body 1 and the needle valve 3 is held by the nozzle main body 4, but the control piston 2 and the needle valve 3 are connected by the connecting member 38 and connected in the axial direction. The contact surfaces 57 are abutted against each other by the spring force of the member 38 and reciprocally slide in synchronism with each other, but the axes of the control piston 2 and the needle valve 3 are not always aligned. The unaligned state of the two shaft cores is allowed by the connecting member 38.

The fuel injection device according to the present invention is constructed as described above and operates as follows. In this fuel injection device, the solenoid valve mechanism 65 is not biased, the solenoid valve 10 and the ball 27 are pressed downward by the spring force of the solenoid spring 9, and the orifice 25 is closed by the ball 27. . In this state, the high pressure fuel from the common rail 29 is supplied to the fuel inlet 49 through the fuel inlet plug 5. In the fuel chamber 37 formed around the control piston 2 and the needle valve 3, high-pressure fuel is supplied from the fuel inlet 49 to the supply hole 6
Is filled through. The gap 52 formed between the outer periphery of the needle valve 3 and the nozzle body 4 is filled with high-pressure fuel. Further, the annular chamber 18 is filled with high-pressure fuel from the fuel inlet 49 through the supply hole 17, and the balance chamber 35 is filled with high-pressure fuel from the annular chamber 18 through the orifice 24. Fuel chamber 3
The high-pressure fuel filled in 7 is sealed by the seal members 30 and 33. Further, the high-pressure fuel in the annular chamber 18 and the balance chamber 35 is blocked by the seal member 33 except for communicating with the high-pressure fuel in the fuel chamber 37 through the orifice 24.

When the orifice 25 is closed by the solenoid valve 10 and the ball 27, the supply hole 1
7 and the high pressure fuel in the balance chamber 35 supplied through the orifice 24, the fuel pressure is applied to the upper surface of the control piston 2 and acts as a pressing force for pushing the control piston 2 downward. Further, the spring force of the return spring 28 acts as a spring force that pushes down the valve body. On the other hand, the fuel pressure applied to the taper surface of the tip of the needle valve 3 that is seated in the injection hole 50 of the nozzle body 4 to open and close the injection hole 50 acts as a force to raise the valve body. In other words, the valve body composed of the control piston 2 and the needle valve 3 rises due to the fuel pressure applied to the valve body, and the injection hole 5
Although the structure is such that 0 can be opened, in this embodiment,
The fuel pressure applied to the taper surface of the tip of the needle valve 3 which is seated in the injection hole 50 of the nozzle body 4 and opens and closes the injection hole 50 depends on the spring force of the return spring 28 and the control piston 2.
Is larger than the sum total of the fuel pressure of the balance chamber 35 applied to the upper surface of the. Moreover, the sum of the pressing force acting on the control piston 2 in the balance chamber 35 and the spring force of the return spring 28 is set to be larger than the pushing-up force applied to the tapered surface of the tip of the needle valve 3, The needle valve 3 is balanced so as to close the injection hole 50.

Then, when the coil 14 of the solenoid valve mechanism 65 is energized by a command from the control unit 34, the energized solenoid 11 lifts the solenoid valve 10 and the ball 27 and opens the orifice 25. When the orifice 25 is opened, the high pressure fuel in the balance chamber 35 is discharged into the hollow chamber 63 through the fuel passage 26 and the orifice 25, and then the hollow chamber 6 is discharged.
3 is returned to the fuel tank through the fuel return pipe 12. When the high-pressure fuel in the balance chamber 35 is discharged, the pushing force acting on the tapered surface of the tip of the needle valve 3 overcomes the force of the return spring 28 and rises, and is fixed to the control piston 2 in the axial direction. The needle valve 4 rises, the injection hole 50 is opened, and fuel is injected into the combustion chamber (not shown).

Then, when the coil 14 of the solenoid valve mechanism 65 is de-energized by a command from the control unit 34, the solenoid 11 is de-energized and the spring force of the valve spring 9 causes the solenoid valve 10 to operate. The ball 27 descends and the ball 27 causes the orifice 25
To close. When the orifice 25 is closed, the high-pressure fuel from the common rail 29 is supplied to the balance chamber 35 through the fuel inlet 49, the supply hole 17 and the orifice 24, and the high-pressure fuel is stored in the balance chamber 35 again, and the high-pressure fuel in the balance chamber 35 is stored. Acts on the upper surface of the control piston 2 again to push down the control piston 2, the needle valve 3 closes the injection hole 50, and the fuel injection from the injection hole 50 ends. This fuel injection device
By repeating the above operation, fuel can be intermittently injected into the combustion chamber.

Next, another embodiment of this fuel injection device will be described with reference to FIGS. 3, 4 and 5. This embodiment has the same structure as the above embodiment except that the structure of the connecting member is different. This embodiment is characterized in that the control piston 2 and the needle valve 3 are connected by a connecting member 70. As shown in FIG. 4, the connecting member 70 is fitted over the end portions of the needle valve 3 and the control piston 2 and is engaged with each other along the opposite edges of the slit 73 in the longitudinal direction. The split ring is composed of a spring plate having a portion 71. Further, at both ends of the connecting member 70, inwardly projecting locking portions are respectively fitted into the annular groove 58 formed at the end of the needle valve 3 and the annular groove 58 formed at the end of the control piston 2. Beads 59 are formed. Therefore, the control piston 2 and the needle valve 3 are connected by the connecting member 70, and the connecting member 70 is axially connected.
The contact surfaces 57 are abutted against each other by the spring force of and are reciprocally slid in synchronization with each other. However, the axes of the control piston 2 and the needle valve 3 are not always aligned, and both of them are not aligned. The unaligned state of the shaft core is allowed by the connecting member 70. Further, as clearly shown in FIG. 5, as the connecting member 70, a folded-back portion 72 in which the tip end member of the tongue portion 71 is bent outward can be formed. Tongue 71
When the folded-back portion 72 is formed in, the ring of the connecting member 70 can be expanded by sandwiching the folded-back portion 72 with a tool or the like, and when the connecting member 70 is expanded, the control piston 2 and the needle valve 3 are separated. If they are fitted to the ends, the connecting work between them becomes easy.

Next, still another embodiment of this fuel injection device will be described with reference to FIG. This embodiment has the same structure as the above-mentioned embodiments except that the structure of the connecting member is different. This embodiment is characterized in that the control piston 2 and the needle valve 3 are connected by a connecting member 74. The connection member 74 is
It is configured in the form of a ball joint, and FIG.
Then, the ball connector 75 divided into two by the slit 77 is integrally provided at the end of the control piston 2. The ball connector 75 has a structure in which a slit 77 is formed so that it can be elastically deformed and a spring force acts. A ball fitting hole 76 into which the ball connector 75 is fitted is formed in the needle valve 3. Therefore, when the ball connector 75 at the end of the control piston 2 is fitted into the ball fitting hole 76 of the needle valve 3, the control piston 2 and the needle valve 3 are elastically connected with one touch. Therefore, the control piston 2 and the needle valve 3 are connected by the connecting member 74, and the abutting surfaces 57 are abutted against each other by the spring force of the connecting member 74 in the axial direction and reciprocally slide integrally in synchronization. However, the axes of the control piston 2 and the needle valve 3 are not necessarily aligned, and the unaligned state of the axes of the two is allowed by the connecting member 74.

Next, another embodiment of the fuel injection device will be described with reference to FIGS. 7 and 8. This embodiment is different from the above embodiments except that the structure of the connecting member is different.
It has the same structure. This embodiment is characterized in that the control piston 2 and the needle valve 3 are connected by a connecting member 78. Connection member 78
Is composed of a ring-shaped spring plate having notches 79 that are fitted over the ends of the needle valve 3 and the control piston 2, respectively. Ring-shaped spring plate notch 7
At the edge of 9, needle valve 3 and control piston 2
An engaging portion 80 is formed to be fitted into each of the annular grooves 58 formed at the ends of and. Therefore, the control piston 2 and the needle valve 3 are connected by the connecting member 78, and the contact surfaces 57 are abutted against each other by the spring force of the connecting member 78 in the axial direction and reciprocally slide integrally in synchronization. However, the axes of the control piston 2 and the needle valve 3 are not always aligned, and the unaligned state of the axes of the two is allowed by the connecting member 78.

[0031]

The fuel injection device according to the present invention is constructed as described above and has the following unique effects. That is, in this fuel injection device, a valve body that opens an injection hole by fuel pressure is a needle valve that opens and closes a control piston that has an end surface exposed to a balance chamber and that penetrates the fuel chamber and a injection hole that is connected to the control piston. And the control piston is slidably supported by the holder body, the needle valve is slidably supported by the nozzle body connected to the holder body, and the control piston and the needle valve are axial. Since it is integrally held in the axial direction by the connecting member having a spring force that allows axial misalignment in the direction orthogonal to the axial direction, it is necessary to align the axial centers of the control piston and the needle valve with high accuracy. It disappears and the axial misalignment is absorbed by the connecting member, and smooth sliding is ensured.

Therefore, in this fuel injection device, workability, productivity, and accuracy of the holder body, the nozzle body, the control piston, and the needle valve can be very easily secured, and the manufacturing cost can be reduced. Moreover, the parts such as the needle valve can be easily replaced and the cost can be reduced. Further, the control piston and the needle valve each independently have to provide the shaft center accuracy with respect to the holder body and the nozzle body, and defects such as uneven wear do not occur and durability is improved. it can. Furthermore, since the control piston and the needle valve can be manufactured separately, the respective materials can be appropriately selected, and for example, only the needle valve can be manufactured with expensive heat-resistant steel or the like having excellent heat resistance. The piston can be made of an inexpensive material, and although the performance is good, the material cost can be reduced.

Further, in this fuel injection device, the connecting member for connecting the control piston and the needle valve absorbs the axial deviation of the two with a spring force and integrally fixes the two axial directions. It can be formed into various structures, and the connecting work between the two can be accomplished by one touch, and the workability can be improved.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view of essential parts showing an embodiment of the fuel injection device of FIG.

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

FIG. 4 is a front view of a main part showing an embodiment of a connecting member used in the fuel injection device of FIG.

5 is a perspective view of a main part showing another embodiment of a connecting member used in the fuel injection device of FIG.

FIG. 6 is a cross-sectional view of a main part showing still another embodiment of the fuel injection device according to the present invention.

FIG. 7 is a cross-sectional view of essential parts showing another embodiment of the fuel injection device according to the present invention.

8 is a perspective view of a main part showing an embodiment of a connecting member used in the fuel injection device of FIG.

[Explanation of symbols]

 1 Holder Body 2 Control Piston 3 Needle Valve 4 Nozzle Body 7 Control Sleeve 18 Annular Chamber 35 Balance Chamber 37 Fuel Chamber 38, 70, 74, 78 Connection Member 50 Injection Hole 57 Abutment Surface 58 Annular Groove 59 Bead (Locking Part) 71 Tongue part 72 Folded part 73, 77 Slit 75 Ball connector 76 Ball fitting hole 79 Notch 80 Locking part

Claims (6)

[Claims] 1. A valve body which reciprocates in a main body having an injection hole for injecting fuel and opens the injection hole by fuel pressure, and a valve body in the main body for accumulating fuel which the valve body penetrates. A fuel chamber formed around the balance chamber, a balance chamber for controlling the lift of the valve body by a fuel pressure formed by a control sleeve fixed to the main body, and a discharge passage for releasing the fuel pressure in the balance chamber are opened and closed. A control piston having an actuator for driving an opening / closing valve, the valve body having an end surface exposed to the balance chamber and penetrating the fuel chamber, and the injection hole connected to the control piston with the end surfaces abutting each other. A needle valve that opens and closes, and the main body is a holder main body that slidably supports the control piston in the axial direction and the holder main body. A nozzle main body provided with the injection hole that slidably supports the needle valve connected to the body in the axial direction, and the control piston and the needle valve are misaligned in the direction orthogonal to the axial direction. A fuel injection device for an internal combustion engine, wherein the fuel injection device is integrally held in the axial direction by a connecting member having a spring force that allows 2. The connecting member comprises a ring that is fitted across the ends of the needle valve and the control piston, and has an annular shape formed at the ends of the needle valve at both ends of the connecting member. 2. The fuel injection device for an internal combustion engine according to claim 1, further comprising inwardly projecting locking portions that are respectively fitted in the groove and the annular groove formed at the end of the control piston. 3. The connecting member is composed of a split ring having a tongue portion that is fitted across the end portions of the needle valve and the control piston and that engages with each other along a slit edge in the longitudinal direction. The connecting member is formed at both ends with inwardly projecting locking portions that respectively fit in the annular groove formed at the end of the needle valve and the annular groove formed at the end of the control piston. The fuel injection device for an internal combustion engine according to claim 1, wherein: 4. The fuel injection device for an internal combustion engine according to claim 3, wherein an end portion of the tongue portion formed on the connection member is formed as a folded portion that is bent outward. 5. The connecting member is a ball connector having a spring force due to a slit provided in one of the needle valve and the control piston, and the ball connector provided in the other is provided with the spring force. 2. The fuel injection device for an internal combustion engine according to claim 1, wherein the fuel injection device comprises a ball fitting hole that can be inserted against the ball. 6. The connecting member is composed of a ring-shaped spring plate having a notch that is fitted over the ends of the needle valve and the control piston, and the notch of the ring-shaped spring plate. 2. The fuel for an internal combustion engine according to claim 1, wherein an engaging portion is formed at an edge portion of each of the needle valve and an annular groove formed at an end portion of the control piston, respectively. Injection device.