JPH0932684A - Fuel injection device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve productivity by easily regulating a sliding clearance between a control sleeve and a control piston constituting a balance chamber and simplifying processing of the control piston. SOLUTION: A balance chamber 35 is formed in a hollow hole 54 of a control sleeve 7 fixed on a holder main body 1, and lift of a valve body is controlled by fuel pressure in the balance chamber 35. A ball 70 is fastened on an upper end surface of a control piston 2 of the valve body, and a sliding clearance between the control sleeve 7 and the valve body is controlled in a clearance between the control sleeve 7 and the ball 70. Control of a sliding clearance 71 between the control piston 2 and the control sleeve 7 is facilitated and manufacturing cost of the control piston is reduced.

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, a fuel injection device as shown in FIG. 5 is known. In the fuel injection device, the control sleeve 7 is fitted and fixed in the central through hole 47 of the holder body 1, and the control piston 2 of the valve body is slidably fitted in the hollow hole 54 of the control sleeve 7. The sliding clearance 71 of the control piston 2 with respect to the control sleeve 7 is achieved by processing both. An annular chamber 18 is formed between the holder body 1 and the control sleeve 7, and the annular chamber 18 communicates with a supply hole 17 that communicates with a high pressure fuel source such as a common rail. In the central hole 54 of the control sleeve, the balance chamber 35 is formed between the central hole 54 and the upper surface of the control piston 2.
Are formed. At the lower end of the annular chamber 18 between the control sleeve 7 and the holder body 1, the seal member 3 is provided.
3 are provided. The lift of the control piston 2 is configured to act on and control the fuel pressure in the balance chamber 35. The balance chamber 35 has an annular chamber 1 for supplying fuel pressure through an orifice 68.
8 and to the outside through the fuel passage 26 and the orifice 25 for releasing the fuel pressure. Orifice 25
Is configured to be opened and closed by a ball 27 fixed to the solenoid valve 10.

Further, as an injector, there is, for example, one disclosed in Japanese Patent Laid-Open No. 262164/1987.
The injector is configured such that the fuel pressure in the control chamber formed of a cylindrical part pushes the needle valve piston to bring the needle valve into close contact with the valve seat and close the injection hole, thereby rapidly lowering the fuel pressure in the control chamber to reduce the needle pressure. Fuel is injected by raising the valve to open the injection hole. The supply of fuel to the control chamber communicates with the supply passage of pressurized fuel through a passage formed in the needle valve piston, a ring passage formed in a cylindrical part, and the like.

Further, as a diesel engine electromagnetic fuel injection device, there is one disclosed in Japanese Patent Application Laid-Open No. 3-964. In order to supply pressurized fuel to a control chamber for controlling a plunger formed of a main body and a sleeve and an injection chamber in which fuel is stored for injecting fuel, the electromagnetic fuel injection device for diesel engine requires 2 A separate passage is formed in the body and sleeve. The fuel is supplied to the control chamber through a supply orifice or an annular recess formed in the main body.

Further, as an electromagnetic internal combustion engine fuel injection device, there is one disclosed in Japanese Patent Laid-Open No. 5-118261. In the fuel injection device of the electromagnetic internal combustion engine, the valve body is housed in the hollow body of the injection device by the liquid-tight connecting means. The liquid-tight connection means comprises a pair of precision ground surfaces and a sealing ring adjacent to the surfaces and compressed between the hollow body and the valve body. A cylindrical axial cavity and a control chamber are formed in the hollow body, and the sliding rod is controlled by the pressure in the control chamber and the cavity. Fuel is supplied to the control chamber and the cavity through an input conduit, an annular chamber and a conduit formed in the hollow body.

[0007]

In the conventional fuel injection device as shown in FIG. 5, the sliding clearance 71 between the outer peripheral surface of the control piston 2 and the hollow hole 54 of the control sleeve 7 is processed by both of them. It is achieved by managing with high precision. In addition, the balance chamber 3 is used to control the control piston 2 and the needle valve.
Although the fuel pressure in 5 is biased to the upper surface of the control piston 2, the fuel is supplied to the balance chamber 35 through a high-pressure fuel supply source such as a common rail.
This is done through an orifice 68 formed in the control sleeve 7 communicating with 7 and an annular chamber 18 formed in the holder body 1. By the way, each of the above-mentioned publications has the same structure.

[0008]

The present invention is applied to a fuel injection device of the type in which fuel is supplied through a common rail, that is, a pressure accumulating chamber, which is a common passage, and a control piston having a valve body fixed to a needle valve and a ball. The ball is fixed to the end surface of the control piston that slides in the control sleeve that constitutes the balance chamber, and the sliding clearance between the control sleeve and the valve body is controlled by the gap between the ball and the control sleeve.
It is configured so that proper adjustment of the sliding clearance between the control piston and the control sleeve is not required and the processing precision of both is not required. Furthermore, the fuel supply to the balance chamber is formed in the holder body and the control sleeve. Of the control sleeve or the ball and the control sleeve to control the flow rate of the supply to the balance chamber when the supply passage is formed by using the sliding clearance between the control sleeve and the valve body. A fuel injection device that can be set by sliding clearance with and does not need to form a separate fuel supply passage in the holder body or control sleeve, facilitates machining of the control piston, reduces machining cost, and improves productivity. .

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 formed in a hollow hole of a control sleeve fixed to the main body, and controlling a lift of the valve body by a fuel pressure supplied through a supply passage, and a balance chamber in the balance chamber. An actuator that drives an on-off valve that opens and closes a discharge path that releases the fuel pressure of the valve body, the valve body being connected to a control piston that penetrates the fuel chamber whose end surface is located on the balance chamber side and the control piston. A needle valve that opens and closes the injection hole, and the control piston has an upper end surface for the control sleeve. That ball adjusting the sliding clearance of cement roll piston is secured a fuel injection system for an internal combustion engine, characterized.

The supply passage for supplying the fuel to the balance chamber is formed between the holder body and the control sleeve and communicates with a fuel supply source. And an orifice opening to the balance chamber formed in the sleeve.

Alternatively, the supply passage for supplying fuel to the balance chamber is formed by a sliding clearance between a wall surface of the hollow hole of the control sleeve and a spherical surface of the ball fixed to the control piston. There is. The sliding clearance formed between the control sleeve and the ball is set to a predetermined amount that is predetermined according to the amount of fuel supplied from the fuel chamber to the balance chamber. Further, the end surface of the control piston on which the ball is seated is formed with a recess at the center thereof, and the control piston and the ball are fixed so that the center of the ball is located on the axis of the control piston. Is preferred.

An end surface of the control piston is exposed to the balance chamber, and the needle valve is connected to the control piston by a connecting member with the end surfaces abutting each other.

Since this fuel injection device is constructed as described above, it is not necessary to adjust the sliding clearance of the control piston with respect to the control sleeve.
Only the sliding clearance of the ball with respect to the control sleeve is managed, the sliding clearance can be adjusted very easily, and the manufacturing cost can be reduced. That is, as the balls that can be used here, for example, the same balls as those used for bearings can be used,
Usually, such balls have a size difference of about 1 μm, so it is easy to select the optimum ball diameter, and set the optimum conditions for the sliding clearance between the control sleeve and the ball. Yes, it is extremely easy to manage. Especially, the sliding clearance between the control sleeve and the ball can be properly managed by selecting the ball.
Since the gap between the control sleeve and the control piston can be made large so that they do not come into contact with each other, the friction due to the sliding of the control piston can be greatly reduced and the operation response of the control piston can be improved. That is, since the sliding clearance between the control sleeve and the control piston can be set larger than the sliding clearance between the ball and the control sleeve, the sliding resistance is only the sliding clearance between the ball and the control sleeve. Even if they contact each other, the contact surface is small, the friction due to the sliding of the control piston can be greatly reduced, and the operational response of the control piston can be improved.

Further, in this fuel injection device, the fuel supply to the balance chamber for controlling the lift between the control piston and the needle valve is performed by an annular chamber formed in the control piston and the holder body,
Orifices or passages can be utilized. Alternatively,
The fuel supply to the balance chamber can also be configured by utilizing the sliding clearance between the control piston and the ball and the control sleeve,
In that case, without providing the annular chamber, the orifice, or the passage as described above, it is not necessary to dispose the seal member between the nozzle body and the control sleeve, and the structure itself can be simply configured. Cost can be reduced and productivity can be improved.

[0015]

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.

Although not shown, this fuel injection device is
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 releases the fuel pressure applied to the valve body through a fuel pressure discharge passage (a fuel passage 26, an orifice 25, a hollow chamber 63, and a fuel return pipe 12 described later) (a coil 14, a later-described coil 14, Solenoid 11 and solenoid valve 10
And a 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.

The above valve body includes a control piston 2 penetrating the fuel chamber 37, a ball 70 fixed to the upper end surface 75 of the control piston 2, and a needle valve connected to the lower end surface of the control piston 2 by a connecting member 38. It consists of three. Two balls 70 are arranged in series in the figure, but one or three balls 70 can be formed. Control piston 2
The needle valve 3 and the needle valve 3 are arranged in a state in which the respective end surfaces abut on the contact surface 57, and are connected to each other in the axial direction by a connecting member 38 having a spring force that allows axial misalignment in a direction orthogonal to the axial direction of both. It is held together. An annular groove 58 is formed at the lower end of the control piston 2, and an annular groove 58 is formed at the upper end of the needle valve 3. At both ends of the connecting member 38, beads 59 that form locking portions that project inward are formed. 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.

In the region where the control piston 2 and the needle valve 3 are connected by the connecting member 38, the fuel chamber 3
A fuel chamber 56 communicating with 7 is formed. The needle valve 3 has a gap 52 in the central through hole 48 of the nozzle body 4.
Is slidably inserted in the state of forming
The face surface is seated on the seat surface in which the nozzle holes 50 formed in the nozzle body 4 are 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 fuel pressure applied to the tapered surface of the tip of the needle valve 3 which is seated in the injection hole 50 of the nozzle body 4 to open and close the injection hole 50 is
It acts as a force to raise the valve body. Further, the fuel pressure applied to the control piston 2 in the fuel chamber 37 is formed to be zero in total.

The control sleeve 7 is fitted in the central through hole 47 of the holder main body 1 so that 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. By fitting the control sleeve 7 into the holder body 1, an annular chamber 18 is formed between them. The seal member 33 seals the annular chamber 18 between the holder body 1 and the control sleeve 7. The control sleeve 7 is 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. The seal between the holder body 1 and the control sleeve 7 is achieved by the butt seal surface 23.

A sliding surface 20 into which the ball 70 and the control piston 2 are slidably fitted is formed in a hollow hole 54 opened below the control sleeve 7, and an upper portion of the hollow hole 54 is provided. Control piston 2
A balance chamber 35 is formed between the ball 70 and the upper hemisphere of the ball 70. The control sleeve 7 is formed with an orifice 24 that connects the balance chamber 35 and the supply hole 17, and an orifice 25 and a fuel passage 26 that communicate with the upper surface of the control sleeve 7. The supply hole 17 communicates with the common rail 29 of the high-pressure fuel source through the fuel inlet plug 5. The balance chamber 35 communicates with the annular chamber 18 through the orifice 24. Therefore, the fuel is supplied to the balance chamber 35 from the common rail 29 through the fuel inlet plug 5, the fuel inlet 49, the supply hole 17, the annular chamber 18 and the orifice 24. The balance chamber 35 is
The lift of the control piston 2 is controlled by the fuel pressure in the balance chamber 35. Further, the control sleeve 7 is formed with an orifice 25 and a fuel passage 26, which are formed on the upper surface of the control sleeve 7 and constitute a discharge passage for discharging the fuel to the outside.

This fuel injection device is equipped with a balance chamber 3
The ball 70 is attached to the end face 75 of the control piston 2 on the 5 side.
Are fixed by electric resistance welding or the like at a fixing portion 73 that makes a circular contact. Another ball 70 is fixed to the upper surface of the ball 70 fixed to the control piston 2 at a fixing portion 74 by electric resistance welding or the like. In particular, the sliding clearance 72 between the spherical surface of the ball 70 and the wall surface of the hollow hole 54 of the control sleeve 7 is set to an appropriate predetermined amount. On the other hand, the sliding clearance 71 between the outer peripheral surface of the control piston 2 and the inner wall surface of the hollow hole 54 of the control sleeve 7 is equal to the sliding clearance 7
If it is set to have a cross-sectional area larger than 2, high accuracy is not required for machining those wall surfaces.
Further, the upper end surface 75 of the control piston 2 on which the ball 70 is seated is formed with a recess 76 at the center thereof, so that the setting of the ball 70 to the control piston 2 can be stably and reliably fixed. The control piston 2 and the ball 70 are fixed so that the center of the ball 70 is located on the axis of the control piston 2.

In the solenoid valve mechanism 65, a hollow chamber 63 is formed in the fixed plug 8 for fixing the control sleeve 7 to the holder body 1, and a ball 27 that can open and close the outlet of the orifice 25 is arranged in the hollow chamber 63. Has been done. The ball 27 is fixed to the lower end surface of the solenoid valve 10 that moves up and down by the urging force of the solenoid 11, and is configured as 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. The solenoid valve spring 9 is attached to the solenoid 11 by a set screw 64.
Is set to The control unit 3 is connected to the coil 14 through the terminal 16 and the connector (harness) 13.
A current corresponding to the signal from 4 is supplied. The energization of the coil 14 energizes the solenoid 11, and the energized solenoid 11 causes the solenoid valve 10 to overcome the spring force of the solenoid valve spring 9 and pull up.
That is, the ball 27 and the solenoid valve 10 function as an actuator that opens the orifice 25.

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 high pressure 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. It is discharged to 12. That is, when the solenoid valve mechanism 65 that constitutes the actuator operates, the ball 27 that constitutes the on-off valve opens the orifice 25, and the fuel pressure in the balance chamber 35 is changed to the fuel passage 26 that constitutes the discharge passage and the orifice 2.
5, released through the hollow chamber 63 and the fuel return pipe 12.

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.

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. A portion of the high pressure fuel from the fuel inlet 49 passes through the supply hole 17, the annular chamber 18 and the orifice 24, and the balance chamber 35.
Is supplied to. Further, a part of the high-pressure fuel from the fuel inlet 49 is supplied to the fuel chambers 37 and 56 formed around the control piston 2 and the needle valve 3 through the supply hole 6, and the outer periphery of the fuel chamber 37 and 56 and the needle valve 3. The high pressure fuel is filled in the gap 52 formed between the nozzle body 4 and the nozzle body 4. The high pressure fuel filled in the fuel chamber 37 is sealed by the seal member 30.

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.

Then, when the coil 14 of the solenoid valve mechanism 65 is energized by a command from the control unit 34, the solenoid 11 which is energized lifts the solenoid valve 10 and the ball 27, and the orifice 25 is opened. 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 push-up force acting on the tapered surface of the needle valve 3 overcomes the force of the return spring 28 and rises, and the needle valve 3 is fixed to the control piston 2 in the axial direction. The needle valve 3 is raised, the injection hole 50 is opened, and fuel is injected into the combustion chamber (not shown).

Next, 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, the annular chamber 18 and the orifice 24, and the high-pressure fuel is stored in the balance chamber 35 again, and the balance chamber 35 The high-pressure fuel inside the ball is fixed to the control piston 2 again.
Acting on the upper surface of 0, the control piston 2 is pushed down, the needle valve 3 closes the injection hole 50, and the fuel injection from the injection hole 50 ends. This fuel injection device can intermittently inject fuel into the combustion chamber by repeating the above operation.

Next, another embodiment of this fuel injection device will be described with reference to FIGS. 3 and 4. FIG. 3 is a sectional view showing another embodiment of the fuel injection device according to the present invention, and FIG. 4 is a sectional view showing a main part of the fuel injection device of FIG. This embodiment has the same configuration and operates in the same manner except that the structure for supplying the fuel to the balance chamber 35 is different from that of the above-mentioned embodiment, and therefore duplicated description will be omitted here. To do.

In this fuel injection device, in particular, the balance chamber 35 has a sliding clearance 7 between the outer peripheral surface of the control piston 2 and the wall surface of the control sleeve 7.
1 and the ball 70 and the control sleeve 7 are in communication with the fuel chamber 37 through a sliding clearance 72. Further, the control sleeve 7 is provided with an orifice 25 and a fuel passage 26 which communicate with the upper surface of the control sleeve 7. The orifice which constitutes a supply passage for supplying the high pressure fuel to the balance chamber 35 provided in the above embodiment. 24, annular chamber 18 and feed hole 17
Is not formed, and the seal member 33 is not provided. The balance chamber 35 is supplied with high-pressure fuel from a fuel chamber 37 formed in the holder body 1 for accumulating the fuel that the control piston 2 penetrates, and has a function of controlling the lift of the control piston 2 by the fuel pressure. .

In this fuel injection device, as described above, the control sleeve 7 and the holder body 1 are not provided with the supply passage for supplying the high-pressure fuel to the balance chamber 35, and the control piston 2 and the control sleeve 7 are provided.
The high pressure fuel is transferred from the fuel chamber 37 to the balance chamber 3 through a sliding clearance 71 between the control sleeve 7 and the ball 70.
5 is configured to be supplied. Sliding clearance 7 formed between the control sleeve 7 and the ball 70 fixed to the control piston 2.
2 is set to a proper predetermined amount that is predetermined according to the amount of fuel supplied from the fuel chamber 37 to the balance chamber 35. That is, the high-pressure fuel from the common rail 29 is supplied to the fuel inlet 49 through the fuel inlet plug 5, and then from the fuel inlet 49 through the supply hole 6 to the fuel chambers 37 and 56 formed around the control piston 2 and the needle valve 3. And the gap 52 formed between the outer periphery of the needle valve 3 and the nozzle body 4 is filled. On the other hand, the balance chamber 35 is filled with high-pressure fuel from the fuel chamber 37 through the sliding clearance 71 between the control sleeve 7 and the control piston 2 and the sliding clearance 72 between the control sleeve 7 and the ball 70. The high pressure fuel filled in the fuel chamber 37 is sealed by the seal member 30. Further, the fuel chamber 37 and the balance chamber 35 are configured to communicate with each other by the sliding clearances 71 and 72.

In this embodiment, the control piston 2
The structure of the ball 70 and the like fixed to the upper end surface 75 of the above is similar to that of the above-mentioned embodiment, but the sliding clearance 7
1, 72 form a supply path of high-pressure fuel to the balance chamber 35. That is, the sliding clearance 72 between the spherical surface of the ball 70 and the wall surface of the hollow hole 54 of the control sleeve 7 is from the fuel chamber 37 to the balance chamber 35.
It is set to a predetermined amount that is determined in advance according to the fuel supply amount to the engine. Therefore, the sliding clearance 71 formed by the inner wall surface of the control sleeve 7, the control piston 2, and the outer peripheral surface has a flow passage area larger than that of the sliding clearance 72, and the fuel contains the balance chamber 35.
If it is set so that it can flow into the wall, high precision is not required for machining those wall surfaces.

[0035]

Since the fuel injection device according to the present invention is constructed as described above, it has the following unique effects. That is, this fuel injection device does not need to adjust the sliding clearance between the control sleeve and the control piston with high accuracy, and only manages the sliding clearance of the ball fixed to the control piston with respect to the control sleeve. It is easy to control the sliding clearance and can be adjusted with high accuracy.
Friction of the control piston can be greatly reduced, its operation response can be improved, and the manufacturing cost of the control piston can be reduced. Further, fuel can be supplied to the balance chamber for controlling the lift between the control piston and the needle valve through a passage such as an annular chamber or an orifice formed in the control piston and the holder body.

Alternatively, when the sliding clearance between the control sleeve and the valve body is formed in the high pressure fuel supply path to the balance chamber, the fuel supply to the balance chamber is performed by the control sleeve, the control piston, and the ball fixed to the control sleeve. The flow rate supplied to the balance chamber can be set by the sliding clearance or the clearance between the ball fixed to the upper surface of the control piston and the wall surface of the control sleeve. In that case, it is not necessary to separately form an orifice, an annular chamber, or a fuel supply passage in the holder main body or the control sleeve, and high precision is not required in the processing of the control piston, and the processing can be facilitated. That is, the ball is fixed to the upper end surface of the control piston, and the position determined in advance according to the fuel supply amount from the fuel chamber to the balance chamber is determined by the sliding clearance between the spherical surface of the ball and the inner wall surface of the hollow hole of the control sleeve. Since it is only set to a fixed amount, the gap between the ball and the control piston can be easily managed, the control piston does not need to be machined with high precision, the clearance can be managed very easily, and the machining cost can be reduced. , Productivity 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 sectional view showing another embodiment of the fuel injection device according to the present invention.

FIG. 4 is a cross-sectional view of a main part showing an embodiment of the fuel injection device of FIG.

FIG. 5 is a cross-sectional view showing an example of a region of a fuel supply passage to a balance chamber in a conventional fuel injection device.

[Explanation of symbols]

 1 Holder Main Body 2 Control Piston 3 Needle Valve 4 Nozzle Main Body 7 Control Sleeve 18 Annular Chamber 24, 25 Orifice 35 Balance Chamber 37, 56 Fuel Chamber 38 Connection Member 50 Injection Hole 54 Hollow Hole 70 Ball 71, 72 Sliding Clearance 73, 74 Fixed part 75 Upper end surface 76 Recess

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 formed in a hollow hole of a control sleeve fixed to the main body, and controlling a lift of the valve body by a fuel pressure supplied through a supply passage, and a fuel in the balance chamber. An actuator for driving an on-off valve for opening and closing a discharge passage for releasing pressure is provided, wherein the valve body penetrates the fuel chamber whose end surface is located on the balance chamber side and the injection piston connected to the control piston. A needle valve for opening and closing the hole, and the control piston for the control sleeve is provided on the upper end surface of the control piston. A fuel injection device for an internal combustion engine, wherein a ball for adjusting a sliding clearance of a piston is fixed. 2. The supply passage for supplying fuel to the balance chamber, the annular chamber being formed between the holder body and the control sleeve and communicating with a fuel supply source; and the control chamber communicating with the annular chamber. The fuel injection device for an internal combustion engine according to claim 1, wherein the fuel injection device is formed by an orifice formed in a sleeve and opening in the balance chamber. 3. The supply passage for supplying fuel to the balance chamber is formed by a sliding clearance between a wall surface of the hollow hole of the control sleeve and a spherical surface of the ball fixed to the control piston. The fuel injection device for an internal combustion engine according to claim 1, wherein: 4. The sliding clearance formed between the control sleeve and the ball is set to a predetermined amount that is predetermined according to the amount of fuel supplied from the fuel chamber to the balance chamber. The fuel injection device for an internal combustion engine according to claim 3, wherein 5. The end face of the control piston on which the ball is seated is formed with a recess at the center thereof, and the control piston and the ball are arranged such that the center of the ball is located on the axis of the control piston. The fuel injection device for an internal combustion engine according to claim 3, wherein the fuel injection device is fixed. 6. The end surface of the control piston is exposed to the balance chamber, and the needle valve is connected to the control piston by connecting members with the end surfaces abutting each other. 5. The fuel injection device for an internal combustion engine according to any one of 5 above.