JP2001263195A - Common rail fuel injector - Google Patents

Abstract

(57) Abstract: The present invention relates to a common rail that absorbs vibration and reduces transmission of vibration to a cylinder head or the like, even if vibration occurs in the common rail due to pressure fluctuation caused by fuel injection by an injector. A fuel injection device is provided. SOLUTION: A common rail 56 for storing a working fluid.
Is composed of a mounting seat 104 provided on a cylinder head 101 (cam carrier 102), and a damping member 105 having a mounting layer 107 and a damping material layer 106 made of heat-resistant rubber or resin. It is attached to the cylinder head 101 by one vibration reduction structure 103. The injector 1 and the common rail 56 are connected by a flexible tube 111 constituting a second vibration reduction structure. The vibration caused by the fuel injection from the injector 1 is absorbed by the first vibration reduction structure 103 and the second vibration reduction structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a common rail type fuel injection device having a cylinder head provided with a common rail and an injector, wherein at least the common rail is attached to the cylinder head with a vibration damping action.

[0002]

2. Description of the Related Art Conventionally, a common rail type fuel injection system is known as a fuel injection system applied to a multi-cylinder engine such as a diesel engine. The common rail type fuel injection system operates the engine using the pressure action of the working fluid supplied to the injector from the common rail by pumping the working fluid pressurized by the high pressure pump to the common rail and storing the working fluid in the common rail. This is a system in which each injector injects fuel into the combustion chamber under fuel injection conditions such as optimum injection pressure, fuel injection amount, and fuel injection timing determined according to the state. Each injector is provided with a control valve for controlling the passage of fuel to or from the injection hole. The pressure of the common rail and the operation of the control valve of each injector are controlled so that the fuel is injected in each injector under optimum injection conditions for the engine operating state.

FIG. 4 shows an example of a common rail type fuel injection system. FIG. 4 is a schematic view showing an example of a common rail type fuel injection system in which engine oil is used as a working fluid to be pumped. Is provided for each cylinder. The fuel pump 53 that sends out the fuel in the fuel tank 52 is a feed pump that sends the fuel at a low pressure (for example, about 5 to 10 MP).
Is supplied to each injector 1 through the fuel filter 54 and the supply path 51. The injector 1 is connected to a supply passage 51 at a fuel supply port 11 and a fuel discharge port 12. Fuel not consumed by the injector 1 is collected in the fuel tank 52 through the fuel collection passage 55.

Each injector 1 has a common rail (also called an oil rail or a high-pressure oil manifold) 56.
, And the engine oil stored in the common rail 56 in a pressure accumulated state is supplied to each injector 1. The oil from the oil reservoir 57 is supplied to the common rail 56 through the oil supply path 61 by the operation of the oil pump 58. An oil cooler 59 and an oil filter 60 are provided in the middle of 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 high-pressure oil pump 63. The supply of oil from the high-pressure oil pump 63 to the common rail 56 is controlled by a flow control valve 64. Excess oil is returned to the oil reservoir 57 through the return pipe 66a. In order to control the flow control valve 64 and control the operation of the injector 1, a controller 50 which is an electronic control module (ECM) of the engine is provided. The controller 50 includes an engine speed sensor 68 that detects the engine speed Ne, an accelerator opening sensor 69 that indicates a load such as the amount of depression of an accelerator pedal, and a crank angle sensor 70 that detects a crank angle. The detection signals from the various sensors and the oil pressure detected by the pressure sensor 71 provided on the common rail 56 are input as the common rail pressure. Other input signals to the controller 50 include various types of sensors for detecting the operating state of the engine, such as a cooling water temperature sensor, an engine cylinder discrimination sensor, a top dead center detection sensor, an atmospheric temperature sensor, an atmospheric pressure sensor, and an intake pipe pressure sensor. There is a signal from the sensor.

FIG. 5 is a detailed sectional view of each injector 1. As shown in FIG. 5, it is composed of a main body having a hollow hole and an injection hole 13 formed therein, and a case 6 disposed with a gap formed so as to form a fuel chamber 20 outside the main body. The main body of the injector 1 includes a nozzle main body 2 having a hollow hole 46 and the injection hole 13 formed therein, a fuel supply main body (plunger barrel) 5 forming the pressure increasing chamber 7, and a nozzle main body 2.
Spacer body 81 having a hollow body 29 and a spacer body 81 located between the fuel supply body 5 and the fuel supply body 5, an injector body 4 having a pressure chamber 8 to which high-pressure hydraulic oil is supplied, and a drain as a leak passage It comprises a solenoid body 3 having a groove 39 and a drain passage 38 and having the solenoid valve 16 disposed therein. The case 6 includes the nozzle body 2 and the spacer body 8 for forming the fuel chamber 20.
1. Surrounds the hollow spacer body 21 and the fuel supply body 5. 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. The supply path 51 opens to a fuel supply port 11 and a fuel discharge port 12 formed in the case 6, and fuel is always supplied from the supply path 51 to the fuel chamber 20.

[0006] The injector 1 is provided with a pressure increasing chamber 7 formed in a fuel supply main body 5 for increasing the pressure of the fuel supplied from the fuel chamber 20, and a fuel is supplied from the pressure increasing chamber 7 to the injection hole 13. Spacer body 81, hollow spacer body 21
The fuel passage 22 formed in the nozzle body 2, the needle valve 23 slidably held in the hollow hole 46 of the nozzle body 2 and opening the injection hole 13 by the fuel pressure, and increasing the pressure of the fuel in the pressure increasing chamber 7. It has a pressure-intensifying piston 9, a pressure chamber 8 to which high-pressure operating oil for applying a high pressure to the end of the pressure-increasing piston 9 is supplied, and a control valve (solenoid valve) 16 for controlling the supply of the high-pressure operating oil to the pressure chamber 8. are doing.

The return spring 18 is disposed in a hollow hole 29 formed in the hollow spacer main 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 return spring 17 for urging the pressure-intensifying piston 9 toward the pressure chamber 8 is
A hollow hole 26 formed in the injector body 4 is disposed in a hollow spring chamber 30 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 body 5. 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 is provided with a discharge passage 8 formed in the fuel supply main body 5.
3 and to the fuel chamber 20 through a check valve 84 disposed in the discharge path 83. In the spring chamber 30,
Normally, the leaked fuel has entered and is in the same state as the fuel pressure in the fuel chamber 20, but the inflow fuel is removed from the spring chamber 30 by the reciprocating motion of the pressure increasing piston 9 to form a void.

The pressure-intensifying piston 9 has a small-diameter portion 24 which is a plunger forming a part of the pressure-intensifying chamber 7 at a lower end surface, a part of the pressure chamber 8 at an upper end surface, and a hollow hole 26 of the injector body 4. The large-diameter portion 25 reciprocatingly moves, and a sliding surface that hangs down from the entire periphery of the outer periphery of the large-diameter portion 25 and slides on the inner surface of the hollow hole 26 is formed to stabilize the vertical movement of the pressure-intensifying piston 9. The guide ring section 41 has a function of causing the guide ring section 41 to function. The small-diameter portion 24 of the pressure-intensifying piston 9 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. In addition, a hollow hole 26 formed in the injector body 4 has:
A sealing member 44 is disposed, and the pressure increasing piston 9 and the hollow hole 2 are arranged.
The gap between the spring chamber 30 and the pressure chamber 8 is shut off so that the high-pressure hydraulic oil in the pressure chamber 8 does not leak to the spring chamber 30.

A pressure increasing chamber 7 is formed at an end of a hollow hole 42 formed in the fuel supply main body 5. 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 intensified in the pressure intensifying chamber 7 is supplied to the fuel passage 22 formed in the spacer main body 81, the hollow spacer main body 21 and the nozzle main body 2, and the fuel formed between the nozzle main body 2 and the needle valve 23. It is supplied to the injection hole 13 through the passage. The needle valve 23 slidably held in the hollow hole 46 of the nozzle body 2 is lifted based on the fuel pressure acting on the tapered surface 45 to open the injection hole 13.

The pressure increasing piston 9 has a flat surface 73 in which the outer peripheral portion of the top surface 65 of the large diameter portion 25 facing the pressure chamber 8 is cut out.
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 injector 1, the spring chamber 3
Numeral 0 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. In the spring chamber 30, the gap 28 between 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 the fuel The fuel leaks and enters through the gap 48 between the contact surface with the supply main body 5. 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 fuel existing in the spring chamber 30 is formed in the fuel supply main body 5 with the reciprocating motion of the booster piston 9. The fuel is discharged to the fuel chamber 20 through the discharged discharge path 83. Since the check valve 84 is provided in the discharge path 83, the fuel is prevented from flowing back from the fuel chamber 20 to the spring chamber 30.

In the injector 1, the opening and closing operation of the injection hole 13 by the needle valve 23 is performed by the control of an actuator 10 such as an electromagnetic solenoid, and when the actuator 10 is energized by a command from the controller 50, The armature 32 is attracted, and the control valve 16 fixed to the armature 32 lifts against the spring force of the return spring 19. When the control valve 16 is lifted,
The passage 33 formed between the tapered surface 86 of the control valve 16 and the valve seat 87 of the injector body 4 is opened, and high-pressure oil is supplied from the common rail 56 to the pressure chamber through the supply passage 31 and the passage 34 formed in the injector body 4. 8 is supplied. When the high-pressure oil is supplied to the pressure chamber 8, the high-pressure oil flows into an annular gap 74 formed between the top surface 65 of the large-diameter portion 25 of the pressure-intensifying piston 9 and the wall surface (flat surface) 72 of the injector body 4. Is supplied, and the operating pressure is urged to the pressure increasing piston 9. The fuel in the supply passage 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 main body 21 and the fuel passage formed in the spacer main body 81 from the fuel chamber 20. The pressure is supplied to the pressure increasing chamber 7 through 35.

When the pressure-increasing piston 9 descends due to the pressure of the high-pressure oil in the pressure chamber 8, the fuel passage 35 is closed by a check valve 36, and the pressure in the pressure-increasing chamber 7 is increased. Booster chamber 7
When the pressure of the fuel of the needle valve 2 is increased, the fuel is pressed against the spring force of the return spring 18 by the increased pressure.
3 is lifted and injected from the injection hole 13. When the urging force of the actuator 10 to the control valve 16 is released, the control valve 16 is lowered by the spring force of the return spring 19, the drain groove 39 provided in the control valve 16 is opened, and the high-pressure oil in the pressure chamber 8 is discharged. The air is discharged through the drain groove 39 and the drain passage 38. When the high-pressure 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 the fuel applied to the needle valve 23 The pressure drops. Due to the spring force of the return spring 18, the tapered surface 45 of the needle valve 23 is seated on the valve seat of the nozzle body 2 and
3 is closed and fuel injection is stopped.

The controller 50 controls the flow control valve 64 of the oil pump 63 and the actuator 10 of each injector 1 so that the fuel is injected in each injector 1 under optimum injection conditions for the operating state of the engine. . The controller 50 outputs a command pulse signal in accordance with a target injection condition set based on a detection signal from each of the above sensors and a previously determined injection characteristic map.
0 is supplied. The target injection conditions include, for example, a target oil pressure, a target fuel injection timing (an injection start timing and an injection start timing) such that the engine output becomes an optimum output in accordance with the operating state of the engine, that is, the engine speed Ne and the accelerator opening Ac. Period) and the target injection amount. The fuel injection amount is the injection pressure (the fuel pressure increased in the pressure increasing chamber 7).
And the fuel injection period, that is, the oil pressure on the common rail 56 in the pressure chamber 8 for increasing the pressure, and the lift of the needle valve 23 (lift amount, lift period). Therefore, the fuel injection timing and the fuel injection amount are eventually
And the pulse timing and pulse width of the command pulse signal output by the controller 50 to control the control valve 16. The controller 50 performs fuel injection control for each injector 1 arranged corresponding to each cylinder.

Since the fuel injection pressure from the injector 1 is related to the oil pressure at the common rail 56,
The fuel injection pressure is controlled by controlling the oil pressure. On the other hand, when the oil in the common rail 56 is consumed for fuel injection from the injector 1, the oil pressure decreases. Accordingly, the controller 50 controls the oil pumping amount of the oil pump 63 so as to maintain a constant pressure corresponding to the operating state of the engine if the operating state is constant, or to change the operating state of the engine. For example, in response to the change, the oil pressure Pr is increased or decreased so as to be optimal for the operating state of the engine.

FIGS. 6 and 7 show an example of a conventional common rail fuel injection system in which the common rail 56 and each injector 1 are arranged on the cylinder head 101. FIG. FIG. 6 is a perspective view showing a conventional common rail fuel injection device, and FIG. 7 is a perspective view showing a part of the common rail fuel injection device shown in FIG. The engine to which the common rail type fuel injection device 120 is applied is an in-line four-cylinder engine, and four injectors 1 are arranged in a line on the cylinder head 101. A rotary camshaft (not shown) on which a cam for opening and closing the intake and exhaust valves of the engine is formed on the cylinder head 101.
A cam carrier 102 for supporting the camera is mounted. The high-pressure oil pumped from the high-pressure oil pump is stored in the common rail 56 in a pressure-accumulated state. The common rail 56
It is composed of a long cylindrical member having a space in which high-pressure oil can be stored, and on the cam carrier 102,
It is mounted parallel to the rows of injectors 1 via a plurality of spaced mounting seats 123.

In the common rail type fuel injection system 120, the common rail 56 and the injector 1 are firmly fixed to the cylinder head 101 in consideration of vibration and system stability. That is, the common rail 56 is attached to the cam carrier 102 in a state of being directly sandwiched between a plurality of pairs of attachment seats 123 erected on the cam carrier 102 by the attachment bolts 129. A fluid supply path 130 (FIG. 7) that connects the common rail 56 to each injector 1 and supplies oil as a working fluid from the common rail 56 to each injector 1 is also formed as a rigid body and a supply pipe 131 extending integrally from the common rail 56. Is rigidly connected to each injector 1.

Japanese Patent Application Laid-Open No. 10-109963 proposes an example of a pressure-accumulation type fuel injection device capable of withstanding high pressure and vibration in a fuel passage connecting a common rail type pressure accumulation chamber and an injector. According to the accumulator type fuel injection device disclosed in this publication, each injector is fixed by a clamp fixed to a common rail by a horo screw.
It is attached to the cylinder head via a common rail. The pressure accumulation chamber of the common rail communicates with the injector through a passage formed inside the horo screw and a passage formed in the clamp. By connecting the injector to the common rail without a pipe, the occurrence of internal pressure fatigue due to high-pressure fuel and fatigue of the connection part due to vibration are suppressed.

A fuel injection device in which a manifold (common rail) for storing a working fluid and an injector are mounted without being affected by thermal expansion of a cylinder head is disclosed in Japanese Patent Application Laid-Open No. Hei 10-68365 by the present applicant. Some have been disclosed. The supply pipe in which the ring portion is fitted to the manifold is directly attached to the body of the injector, and the oil supply port formed in the manifold at the fitting position communicates with the supply pipe, and further communicates with the inside of the injector. I have.

Japanese Patent Application Laid-Open No. Hei 10-30511 discloses a fuel supply device for simply connecting an in-cylinder injector to a fuel distribution common rail provided in a high-pressure line. By connecting the common rail and the pressure-resistant fuel pipe connected to each injector with a relay pipe consisting of a pressure-resistant hose by a joint consisting of a one-touch coupler, etc., the pipe connection between the common rail type and the injector is simplified. I have.

The common rail fuel injection system of the above type is an oil pressure control type common rail fuel injection system in which engine oil is used as a working fluid and oil pressure is increased by a pressure increasing piston to pressurize fuel. Instead of this type of system, the fuel itself is used as the working fluid, and the control valve controls the fuel pressure in the pressure control chamber to control the lift of the needle valve. An injection system (for example, Japanese Patent Application Laid-Open No. Hei 7-109963) has also been proposed.

[0022]

However, in order to firmly fix the common rail and the injector to the cylinder head, there is a problem that simply increasing the rigidity causes an increase in weight and an increase in production cost. Also,
Even if the structure of the common rail itself is increased, or the fastening force of the common rail to the cylinder head is increased, the common rail itself is the source of vibration, so the entire engine will be vibrated and the engine vibration will be attenuated. It has a difficult structure.

The vibration noise in the oil pressure operated type common rail fuel injection system as described above is caused by pressure fluctuation (pulsation) generated when the solenoid valve, which is the control valve of the injector, is opened and closed, and when the pressure increasing piston is moved up and down. Turned out to be. With the conventional structure in which the common rail is firmly fastened to the cylinder head, the vibration of the common rail caused by the pressure fluctuation synchronized with the pulsation generated from the injector directly propagates to the engine body, causing the common rail vibration and noise to occur, and This is the cause of early deterioration of the supply pipe. Also in a fuel pressure operated common rail type fuel injection system using fuel as a working fluid, pressure pulsation is applied to the common rail due to opening / closing of a control valve of the injector and lifting / lowering of a needle valve, and vibration is generated in the common rail.

Therefore, in the common rail type fuel injection system, even if the pressure fluctuation (pulsation) generated in the injector reaches the common rail and the common rail vibrates, the vibration generated in the common rail is generated by the cylinder mounting the common rail. There is a problem to be solved in that the engine including the cylinder head is prevented from generating vibration and noise by absorbing the vibration during transmission so as not to be transmitted to the head. Further, there is another problem to be solved in that the vibration generated in the common rail is prevented from being transmitted to the injector via the fluid supply path or the durability of the connection portion between the injector and the fluid supply pipe is reduced.

[0025]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problem. Even if the common rail vibrates due to the pressure fluctuation of the working fluid caused by the fuel injection by the injector, the vibration is generated by the cylinder head. It is an object of the present invention to provide a common rail type fuel injection device capable of preventing engine noise and unpleasant vibration by being prevented from causing engine vibration and noise by being directly transmitted to the engine. Further, if the vibration of the common rail is permitted, the durability of the connecting portion of the fluid supply pipe for the working fluid connecting the common rail and the injector may become a problem. An object of the present invention is to provide a common rail type fuel injection device having good connection part durability.

According to the present invention, there is provided a common rail mounted on a cylinder head for storing a working fluid in a pressure-accumulated state, and operated based on a pressure action of a working fluid mounted on the cylinder head and supplied from the common rail through a fluid supply path. An injector for injecting fuel into the combustion chamber, wherein the common rail is attached to the cylinder head via a first vibration reduction structure, and the injector is attached to the common rail via a second vibration reduction structure. And a common rail fuel injection device.

According to this common rail fuel injection system, even if the common rail vibrates due to pressure fluctuations caused by the fuel injection of the injector, the common rail is mounted on the cylinder head via the first vibration reduction structure. Is prevented from being transmitted, and the generation of engine vibration and noise caused by the vibration of the common rail is suppressed. Further, since the common rail and the injector are mounted via the second vibration reduction structure, transmission of the vibration of the common rail to the injector is suppressed by the second vibration reduction structure.

The first vibration reduction structure includes a mounting seat disposed on the cylinder head, and a damping member disposed between the mounting seat and the common rail. Further, the damping member, a damping material layer made of heat-resistant rubber or resin that is in contact with the outer periphery of the common rail,
A mounting plate is disposed over the outside of the damping material layer and is mounted on the mounting seat, so that the structure is simple and the manufacturing cost is low. Further, the damping material layer and the mounting plate of the damping member are respectively divided into a side of the common rail facing the cylinder head and a side opposite to the cylinder head, and the divided mounting plates are respectively mounted on the common rail. It is attached to the seat.

The second vibration reduction structure is constituted by a flexible pipe having both ends connected to the common rail and the injector, respectively, and forming the fluid supply passage therein. The flexible tube is configured by reinforcing the outer surface of a heat-resistant nylon tube with a metal mesh. By configuring the fluid supply path with a flexible pipe, the vibration of the common rail is not transmitted directly to the injector as it is, but is transmitted in a reduced state due to the damping action of the flexible pipe itself, and the communication between the flexible pipe and the injector is performed. The occurrence of troubles such as fatigue at the connecting portion is reduced.

In the common rail type fuel injection device, the working fluid is engine oil, and the injector is
An oil pressure operated common rail type fuel injection device for injecting fuel into the combustion chamber based on the pressure action of the engine oil supplied from the common rail. Alternatively, the working fluid is used as fuel, and the injector is a fuel pressure operated common rail fuel injection device that injects the fuel into the combustion chamber with the pressure of the fuel supplied from the common rail.

The injector controls a pressure of the working fluid supplied from the common rail based on a control signal from a controller, and moves up and down based on a pressure action of the working fluid controlled by the control valve. A needle valve that opens and closes an injection hole for injecting fuel formed at the tip of the injector, and controls the elevation of the needle valve by controlling the control valve to adjust the fuel injection timing from the injector. And the fuel injection amount can be controlled.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a common rail fuel injection device according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective view showing an embodiment of a common rail type fuel injection device according to the present invention, FIG. 2 is an enlarged perspective view showing a part of the common rail type fuel injection device shown in FIG. 1, and FIG. 5 is a graph showing a damping effect of the conventional fuel injection device in comparison with a conventional fuel injection device.

1 and 2, the same components as those used in the conventional common rail fuel injection system shown in FIG. 4, the injector shown in FIG. 5, and the conventional common rail fuel injection device shown in FIGS. For the element,
The same reference numerals are given, and the description will not be repeated. In the common rail fuel injection device 100, the common rail 5
6 is attached to the cylinder head 101 (specifically, the cam carrier 102) by the first vibration reduction structure 103. The first vibration reduction structure 103 includes a plurality of mounting seats 104 disposed on the cylinder head 101 (cam carrier 102), and a damping member 105 disposed between the mounting seat 104 and the common rail. The mounting seats 104 are provided in a plurality of pairs such that the pair of mounting seats 104 sandwich the common rail 56.

The damping member 105 includes a damping material layer 106 made of heat-resistant rubber or resin which is in contact with the outer periphery of the common rail 56, and a mounting member which is disposed so as to cover the outside of the damping material layer 106 and is mounted on the mounting seat 104. The mounting plate 107 is fixed to the mounting seat 104 by mounting bolts 110. Damping member 105
Are above and below the common rail 56, that is, the common rail 56
Are divided into a side facing the cylinder head 101 and a side facing the cylinder head 101, and are arranged so as to sandwich the common rail 56 from above and below. The damping member 105 configured as described above has a very simple structure with a small number of parts and has a well-balanced arrangement with respect to the common rail 56 having a tubular structure laid horizontally. In addition, it has an effect on vibration damping and reduces the manufacturing cost.

Each mounting plate 107 has a cover 108 located at the center of the main body in contact with the damping material layer 106, and a flange formed by bending both sides of the cover 108 so as to be parallel to the mounting surface of the mounting seat 104. The common rail 56 is attached to the cylinder head 101 (or the cam carrier 102) by passing the attachment bolt 110 of the flange 109 and screwing it into the attachment seat 104.

Since the damping material layer 106 is formed of heat-resistant rubber or heat-resistant resin, even if the common rail 56 vibrates due to pressure pulsation generated in the working fluid due to fuel injection from the injector 1, the common rail 56 is The vibration is
From the mounting plate 107 to the mounting seat 104, the common rail 56
Is not directly transmitted, but is absorbed by the damping material layer 106 before being transmitted to the cylinder head 101, so that vibration and noise generated from the common rail 56 can be reduced.

FIG. 3 is a graph showing the effect of reducing the vibration of the common rail by the common rail fuel injection device according to the present invention. The horizontal axis in FIG. 3 represents the frequency [Hz] of the vibration of the common rail, and the vertical axis represents the acceleration [m / m / obtained from the result of the vibration analysis of the vibration of the common rail by the finite element method.
sec ² ]. In FIG. 3, the solid line graph shows the state of the common rail vibration (vibration at the rear end) in the conventional common rail type fuel injection device, and the thick solid line shows the state of the common rail vibration in the common rail type fuel injection device improved by the present invention. Is shown. As can be seen from the graph of FIG. 3, the vibration level of the common rail fuel injection device according to the present invention is significantly reduced in the region of the vibration frequency of about 2000 Hz and the vibration frequency of 4000 Hz or more compared with the conventional one. ing.

A fluid supply path 1 for connecting the common rail 56 to each injector 1 and supplying the working fluid (engine oil) in the common rail 56 to each injector 1
18 is a flexible tube 1 constituting the second vibration reduction structure
11 and has a structure in which even if the common rail 56 vibrates, problems such as cracks are unlikely to occur.
The flexible tube 111 is not made of a hard material such as a steel pipe, but is basically made of a nylon tube 112, and the outside thereof is covered with a metal mesh 113. The metal mesh 113 protects the nylon tube 112 from collision with an external member or foreign matter.
When the common rail 56 vibrates, the vibration is attenuated during transmission through the flexible pipe 111, so that the transmission of the vibration to the injector 1 is reduced.

The connecting portion 114 connecting the end of the flexible tube 111 to the common rail 56 or the injector 1
An enlarged portion 115 which is expanded in a flange shape is formed on the end of the nylon tube on the outside, and the end face of the metal mesh 113 terminated immediately before the enlarged portion 115 is formed in a structure in which the end face is in contact with the enlarged portion 115. The enlarged portion 115 of the nylon tube 112 and the end of the metal mesh 113 are held down by the mounting fastener 116 so that the mounting bolt 11
7 attaches to the common rail 56 or the injector 1 to obtain a good sealing state. Attach the end of the flexible pipe 111 to the mounting fastener 116 and the mounting bolt 11.
7, the connecting portion 114 connected to the common rail 56 or the injector 1 is covered by the damping material layer 106 which is raised in the convex portion formed on the upper mounting plate 107 of the first vibration reduction structure 103. Vibration reduction is ensured. Vibration is absorbed by the flexible tube 111 itself constituting the second vibration reduction structure, so that vibration transmission to the injector 1 is reduced, and the connecting portion 11 is deformed according to the vibration of the flexible tube 111.
Since the stress load of Step 4 is reduced, the durability of the connecting portion 114 is not impaired.

[0040]

As described above, the common rail fuel injection device according to the present invention has a structure in which the common rail vibrates by the first vibration reduction structure even if the common rail vibrates due to the pressure fluctuation of the working fluid caused by the fuel injection by the injector. Since the structure is such that vibration is not transmitted from the cylinder head to the components of the engine, the generation of uncomfortable vibration and noise of the engine caused by the vibration of the common rail can be significantly reduced. On the other hand, if the vibration of the common rail is allowed, the durability of the connection part of the fluid supply pipe connecting the common rail and the injector may be a problem. However, the fluid supply pipe connecting the common rail and the injector may be subject to the second vibration. Since the flexible pipe is used as a reduction structure, the vibration of the common rail is attenuated by the flexible pipe, and the flexible pipe reduces the stress on the connecting part due to vibration deformation. Durability can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a common rail fuel injection device according to the present invention.

FIG. 2 is an enlarged perspective view showing a part of the common rail type fuel injection device shown in FIG.

FIG. 3 is a graph showing the damping effect of the common rail fuel injection device according to the present invention in comparison with a conventional fuel injection device.

FIG. 4 is a schematic view showing an example of a conventional common rail fuel injection system.

5 is a sectional view showing details of an injector used in the common rail type fuel injection system shown in FIG.

FIG. 6 is a perspective view showing a conventional common rail fuel injection device.

FIG. 7 is a partially cutaway perspective view of the common rail type fuel injection device shown in FIG.

[Explanation of symbols]

 Reference Signs List 1 injector 13 injection hole 16 control valve 23 needle valve 50 controller 56 common rail 100 common rail fuel injection device 101 cylinder head 103 first vibration reduction structure 104 mounting seat 105 damping member 106 damping material layer 107 mounting plate 111 flexible pipe (second vibration Reduction structure) 112 Nylon tube 113 Metal mesh 114 Connection part 118 Fluid supply path

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02M 47/00 F02M 47/00 EF 47/04 47/04 57/02 320 57/02 320B 330 330B 63 / 00 63/00 DF term (reference) 3G066 AA07 AB02 AC08 AC09 AD12 BA12 BA22 BA40 BA46 BA61 CA01T CA08 CA09 CB01 CB05 CB12 CC06T CC14 CC26 CD04 CD14 CD17 CD26 CD28 CE12 CE13 DA01 DA04 DC04 DC05 DC09 DC18 3G301 HA02 HA06 LC12 LB11 LB11 LB11 LB11 LC08 MA18 ND01 PB03A PB03Z PB08A PB08Z PE01Z PE03Z PF03Z

Claims (9)

[Claims] 1. A common rail attached to a cylinder head for storing a working fluid in a pressure-accumulated state, and a common rail attached to the cylinder head and operated based on a pressure action of a working fluid supplied from the common rail through a fluid supply path. An injector for injecting fuel into the combustion chamber, wherein the common rail is attached to the cylinder head via a first vibration reduction structure, and the injector is attached to the common rail via a second vibration reduction structure. A common rail fuel injection device. 2. The apparatus according to claim 1, wherein the first vibration reducing structure includes a mounting seat disposed on a cylinder head, and a damping member disposed between the mounting seat and the common rail. 2. The common rail fuel injection device according to 1. 3. The damping member is disposed so as to cover a heat-resistant rubber or resin damping material layer abutting on the outer periphery of the common rail, and the damping material layer, and is attached to the mounting seat. 3. The common rail type fuel injection device according to claim 2, comprising a mounting plate. 4. The damping material layer and the mounting plate of the damping member are divided into a side of the common rail facing the cylinder head and a side of the common rail facing away from the cylinder head. 4. The common rail fuel injection device according to claim 3, wherein the fuel injection device is mounted on each of the mounting seats. 5. The second vibration reduction structure according to claim 1, wherein both ends are formed by a flexible pipe connected to the common rail and the injector to form the fluid supply passage therein. 5. The common rail fuel injection device according to any one of 4. 6. The common rail fuel injection device according to claim 5, wherein the flexible tube is formed by reinforcing an outer surface of a heat-resistant nylon tube with a metal mesh. 7. The working fluid is engine oil,
7. The common rail fuel injection device according to claim 1, wherein the injector is configured to inject a fuel whose pressure has been increased based on a pressure action of engine oil supplied from the common rail into the combustion chamber. 8. . 8. The common rail according to claim 1, wherein the working fluid is fuel, and the injector injects the fuel into the combustion chamber at a pressure of the fuel supplied from the common rail. Type fuel injection device. 9. A control valve for controlling the pressure of the working fluid supplied from the common rail based on a control signal from a controller, and the injector moves up and down based on a pressure action of the working fluid controlled by the control valve. A needle valve for opening and closing an injection hole for injecting fuel formed at the tip of the injector, and controlling the elevation of the needle valve by controlling the control valve to thereby control the fuel from the injector. 9. The common rail fuel injection device according to claim 7, wherein the injection timing and the fuel injection amount are controllable.