JP2002081357A - Fuel injection device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection device of an internal combustion engine capable of making compact the engine by disposing an accumulator and a fuel feed pump between a cylinder head and a cylinder head cover in a layout not causing an interference with a valve gear on the cylinder head. SOLUTION: In this accumulator fuel injection device 1 formed by comprising an accumulator 11 storing fuel pressurized and fed by a fuel feed pump 12 and feeding the fuel to a plurality of injectors 13, the accumulator 11 is formed as an intermediate member 10 between the cylinder head 2 and the cylinder head cover 3, and placed on the cylinder head 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure accumulating type fuel injection device for an internal combustion engine in which high pressure fuel stored in a pressure accumulator is injected from a plurality of injectors into a combustion chamber.

[0002]

2. Description of the Related Art In recent years, in a fuel injection device for a diesel engine, a fuel efficiency has been improved by increasing a combustion efficiency, and a cleanness of exhaust gas with respect to smoke, NOx, etc. has been increased.
Accumulation type (common rail type) that can perform high-pressure injection and has excellent controllability of fuel injection due to the need to take measures against noise, etc.
Fuel injection devices have been widely used.

This accumulator type fuel injection device is a device for accumulating high-pressure fuel in a pressure accumulator and then injecting fuel. By adopting this accumulator type fuel injection device, the injection pressure, Optimal combustion control can be performed by finely controlling the injection timing, the injection amount, and the number of injections, and the fuel consumption can be reduced. In addition, according to this accumulator type fuel injection device, since split injection is also possible, the combustion temperature can be controlled and NOx (nitrogen oxide) can be reduced.

When the fuel is injected at a high pressure, the injected fuel can be made finer and the injection control can be made finer, and the combustion efficiency can be improved and smoke can be reduced. Conventional 100MPa-130
From the range of MPa, further, 130 MPa to 150 MPa
Is moving into the range exceeding.

[0005] This prior art accumulator type fuel injection device 20
As shown in FIG. 5, a pressure accumulator (common rail) 21 is mounted beside a cylinder head 2 and a cylinder head cover 3 using a mounting seat or a bracket, and a pressure accumulator chamber of the pressure accumulator 21 and an injector in the cylinder head cover 3 are provided. 23
Are connected by a high-pressure pipe 24, and the length of the pipe 24 is formed so as to be the same in view of the timing of fuel injection. Also, a fuel supply pump (supply pump) 2
2 is attached to an engine body such as the cylinder head 2 by a bracket, and is driven from a drive shaft of the engine via a gear or a belt.

[0006] Therefore, the accumulator type fuel injection device of the prior art has the following problems of pipe sealing, fuel supply pump vibration, and pressure pulsation of the accumulator chamber. With this, it has become an increasingly serious problem.

First, the first problem of sealing the piping is a problem relating to the reliability and durability of the fastening portion seal of each component due to the high pressure of the pressure accumulating chamber, and the improvement of the pressure resistance of the piping and the sealing of the fastening portion. If a structure that can increase the fastening force for ensuring the quality is adopted, there is a problem that the quality assurance cost increases.

[0008] The problem of the vibration of the second fuel supply pump is related to the rigidity of the fuel supply pump, and the fuel supply pump is generally driven by an output shaft of an engine whose output fluctuates due to combustion. Have been. Therefore, load fluctuations and vibrations occur in the fuel supply pump, and the vibrations increase as the pressure of the fuel increases, so that durability of the mounting portion becomes a problem. For this reason, it is necessary to increase the rigidity of the mounting portion. However, it is difficult to increase the mounting rigidity while avoiding an increase in weight by the conventional method of mounting the engine body with a bracket or the like.

[0009] The third problem of pressure pulsation in the accumulator relates to the volume of the pipe between the accumulator and the injector. In the prior art, a steel pipe is usually arranged between the accumulator and the injector, and the length of the pipe is set to be the longest to each injector due to the timing control of injection.

However, if the pipe length becomes longer, the pulsation cycle of the fuel pressure generated at each injection becomes larger, which affects the fuel injection at the time of the next subsequent fuel injection. A problem arises in that the fuel injection amount to be injected cannot be accurately injected.

The problem of pressure pulsation develops into the problem of injection control. That is, in the fuel injection control, a pressure sensor is provided at the end of the accumulator, for example, the start of fuel injection is detected when the fuel pressure starts dropping, and the end of fuel injection is detected when the pressure drop ends. The fuel injection is finely controlled by calculating the injection amount from the time before and the pressure before fuel injection, but when the pulsation of the pressure in the accumulator becomes large, these detections become uncertain. However, there arises a problem that correct control cannot be performed.

In order to solve these problems, Japanese Patent Application Laid-Open No.
As described in U.S. Pat. No. 2,642,277 and Japanese Patent Application Laid-Open No. 9-88861, the pressure accumulator (common rail) is arranged inside or above the cylinder head and the pipes are shortened or omitted. ing.

In the pressure accumulating fuel injection device disclosed in Japanese Patent Application Laid-Open No. 9-264277, the pressure accumulator is fitted in the cylindrical cavity of the cylinder head main body to reduce the space around the engine main body and to reduce the length of the fuel tube. Make it shorter
The weight is reduced. In the fuel injection device for an internal combustion engine disclosed in Japanese Patent Application Laid-Open No. 9-88861, the pressure accumulator and the fuel pump are mounted and fixed on the cylinder head, and the fuel pump and the injector are directly fixed to the pressure accumulator by a joint. Thereby, pipes are omitted to improve the reliability of the connection portion and to make the overall layout compact.

[0014]

However, when an accumulator is to be fitted into a cylindrical cavity of a cylinder head body as disclosed in Japanese Patent Application Laid-Open No. 9-264277, a valve operating mechanism or the like is provided inside the cylinder head. Since the intake / exhaust passage, the cooling water passage, and the like are arranged in a complicated and complicated manner, there is a problem that a space in which the common rail can be arranged without interfering with the passage cannot be actually secured.

In the apparatus disclosed in Japanese Patent Application Laid-Open No. 9-87661, the position of the pressure accumulator becomes a problem similarly to the above, and the fuel pump is driven by the cam of the valve operating mechanism. And the fuel pump is arranged adjacent to the valve operating mechanism.

Further, since the pressure accumulators are arranged on the injectors and are accommodated in the cylinder head, the height of the engine is increased and the engine cannot be accommodated in the engine room.

In addition, these structures are greatly different from the conventional structure in which a pressure accumulator is arranged on the side of a cylinder head. Since the pressure accumulator and the like are mounted on the cylinder head, the pressure accumulator and the fuel pump, etc. Significant changes in engine layout are required to avoid interference with valve trains and injectors.

Accordingly, it is not enough to change the design of only a part of the engine, but it is necessary to redesign the engine structure itself.
Therefore, there is a problem that it cannot be applied to an engine already on the production line.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide a layout in which a valve accumulator and a fuel supply pump are connected to a cylinder head with little influence on a valve operating mechanism on the cylinder head. It is an object of the present invention to provide a fuel injection device for an internal combustion engine, which can be arranged at a portion of a wall member of an engine body between cylinder head covers and can make the engine compact.

[0020]

A fuel injection device for an internal combustion engine for achieving the above object is configured as follows.

1) In a pressure accumulating fuel injection device formed to have a pressure accumulator for accumulating fuel pressurized and supplied by a fuel supply pump and supplying the fuel to a plurality of injectors, the accumulator is connected to a cylinder head. As an intermediate member between the cylinder head cover and the cylinder head cover, and is mounted on the cylinder head.

That is, when the pressure accumulator (common rail) is mounted on the cylinder head, not on the cylinder head but on the cylinder head, the side portion of the portion where the valve operating mechanism and the injector are arranged, that is, in the conventional art. The cylinder head cover is formed near the portion where the side wall member was located, and is formed as an intermediate member on which the cylinder head cover is placed. The intermediate member is assembled to the engine body while being sandwiched between the cylinder head and the cylinder head cover.

According to this structure, in the structure of the conventional engine, a part of the wall member of the cylinder head cover above the outer wall of the cylinder head is constituted by the pressure accumulator, so that it interferes with the valve mechanism on the cylinder head. Without doing
An accumulator can be arranged. In addition, it can be arranged at a site that can be directly connected to the injector.

This means that the present invention can be applied to an engine on an existing production line with only a slight design change, and the production line can be dealt with with only a partial change. Means that it is possible to achieve very difficult.

Further, since the pressure accumulator formed to be strong to withstand high pressure is mounted on the cylinder head in the longitudinal direction, the pressure accumulator functions as a reinforcing member for the cylinder head, and the rigidity of the cylinder head is improved. Therefore, vibration and noise can be reduced.

2) In the pressure accumulating fuel injection device, the fuel supply pump is directly connected to and integrated with the pressure accumulator to form a part of the intermediate member.

By directly connecting the fuel supply pump to the pressure accumulator, piping and a mounting bracket are not required, the reliability of sealing is increased, and the weight is reduced. Since the fuel supply pump is fixed to the vessel and a part of the fuel supply pump is also sandwiched between the cylinder head and the cylinder head cover, the mounting rigidity of the fuel supply pump is improved.

3) In the pressure accumulating fuel injection device, the injector is directly connected to and integrated with the pressure accumulator to form a part of the intermediate member.

According to this configuration, the piping is omitted by directly connecting the injector to the pressure accumulator, so that the sealing performance is improved. Further, the path leading to the injector is shortened, the pulsation generated in the pressure in the pressure accumulator can be reduced, and the injection control such as the timing of fuel injection can be accurately performed with the pressure in the pressure accumulator.

Further, by integrally assembling the accumulator, the fuel supply pump, and the injector, when assembling the engine, these parts can be pre-assembled and handled as a module, so that the number of parts in the production line is reduced. Engine efficiency can be improved.

4) In the pressure accumulating fuel injection device, the injector is connected to the pressure accumulator via a mounting position adjusting mechanism.

When the pressure accumulator, the fuel supply pump and the injector are integrally mounted to form a module, even if the assembly dimensional accuracy of the tip of the injector in this module can be maintained, since the opposed cylinder head side is a cast product, The dimensional accuracy of the position where the tip of the injector comes into contact is not obtained.

The portion of the nozzle sleeve hole of the cylinder head where the tip of the injector comes into contact is an important part for sealing the combustion chamber, and if both do not contact in a correct positional relationship, sufficient sealing performance is obtained. I can't secure it.

For this reason, a mounting position adjusting mechanism is provided so that the position of the tip of each injector integrated with the common rail can be adjusted in accordance with the contact portion on the cylinder head side.

With this configuration, the accumulator, the fuel supply pump, and the injector after modularization can be handled as one part, so that the number of parts handled on the production line is reduced, and the productivity is improved.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fuel injection device for an internal combustion engine according to the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a fuel injection device 1 for an internal combustion engine pressurizes fuel to accumulator (common rail) 11.
A fuel injection pump (supply pump) 12 for supplying to the
An accumulator 11 for accumulating the fuel supplied from the fuel injection pump 12 and a plurality of injectors 13 for injecting the high-pressure fuel supplied from the accumulator 11 into a combustion chamber of the internal combustion engine are formed. .

The injector 13 is controlled by a control device (not shown) called an engine control unit (ECU). The accumulator 1 of the accumulator 11
A pressure sensor 16 is attached to the end of 1a, and its output is input to the control device. The control device controls the pressure sensor 1
A change in pressure in the pressure accumulator 11 is detected by 6 and is used for injection control of the injector 13.

The pressure accumulator 11 has a pressure accumulating chamber 11a, is formed as an intermediate member 10 mounted on the cylinder head 2, and is provided between the cylinder head cover 3 and the cylinder head 2 by a bolt inserted into a bolt hole 10a. The cylinder head 2 is provided not on the cylinder head 2 but on the cylinder head 2 and continuously on the outer wall of the cylinder head 2. The intermediate member 10 is mounted on the cylinder head 2 and the cylinder head cover 3 is mounted thereon to form a part of a wall member of the engine.

Further, a fuel injection pump 12 for pressurizing and supplying the fuel to the accumulator 11 and a plurality of injectors 13 for injecting the fuel of the accumulator 11 into the combustion chamber are inserted into a holder 13a, and a pipe (pipe) is formed. The pressure accumulator 11 and the injector 13 are directly connected to each other without passing through, and are integrally formed.

The pressure accumulator 11 of the injector 13
Attachment and connection to the camera are performed via the attachment position adjusting mechanism 14. In the mechanism shown in FIG. 4, the mounting position adjusting mechanism 14 includes two fixing screw portions 14a and 14b, and a hole 14a into which one of the screws is inserted is formed as a long hole or a stupid hole. Is configured to be adjustable. The mounting position adjusting mechanism can use a well-known technique without being limited to the elongated hole or the stupid hole.

With this configuration, even if the fuel supply pump 12 and the injector 13 are previously mounted on the accumulator 11 and modularized, the nozzle sleeve hole on the side of the cylinder head 2 on which the dimensional accuracy is not obtained because it is a cast product is not aligned. Thus, the position of the distal end portion of the injector 13 can be adjusted and attached, and in an important portion for sealing the combustion chamber, both can be brought into contact in a correct positional relationship, and sufficient sealing performance can be secured.

According to the fuel injection device 1 for an internal combustion engine having the above configuration, the following effects can be obtained.

An accumulator (common rail) 11 is formed as an intermediate member 10 disposed between the cylinder head 2 and the cylinder head cover 3 and is used as a part of an engine wall member. Since the portion where the wall surface of the cylinder head cover 3 placed on the cylinder head 2 was present is constituted by the pressure accumulator 11, it is directly connected to the injector 13 without affecting the valve mechanism 4 on the cylinder head 2. Where possible
An accumulator 11 can be arranged. Therefore, the present invention can be applied to an internal combustion engine on an existing production line with only a slight design change, and the production line can be dealt with with only a partial change.

Further, since the pressure accumulator 11, which is ruggedly formed to withstand high pressure, is mounted on the cylinder head 2 in the longitudinal direction, the pressure accumulator 11 serves as a reinforcing member for the cylinder head 2. Since the rigidity can be increased, it can contribute to the reduction of engine vibration and noise.

Then, the fuel supply pump 12 is connected to the accumulator 11
By directly connecting to the pipe, a piping and a mounting bracket are not required, so that the reliability of the sealing property is increased and the weight can be reduced. Further, the fuel supply pump 12 is fixed to the pressure accumulator 11, and a part or the whole of the fuel supply pump 12 is formed as a part of the intermediate member 10 and is sandwiched between the cylinder head 2 and the cylinder head cover 3.
2 can improve the mounting rigidity.

Further, by directly connecting the injector 13 to the pressure accumulator 11, the sealing performance is improved by omitting the piping, and the path to the injector 13 is shortened. Can be reduced. Therefore, injection control such as fuel injection timing can be accurately performed with reference to a change in pressure detected in the accumulator 11.

Further, by integrally assembling the accumulator 11, the fuel supply pump 12, and the injector 13, at the time of assembling the internal combustion engine, these parts can be assembled in advance and handled as a module. The number of parts can be reduced, and the production efficiency of the internal combustion engine can be improved.

[0049]

As described above, the fuel injection device for an internal combustion engine according to the present invention has the following effects.

1) Since the pressure accumulator (common rail) is sandwiched between the cylinder head and the cylinder head cover and is formed as a part of an intermediate member serving as a wall member of the engine, in other words, the pressure accumulator is formed of the cylinder head cover. Since the outer wall is disposed at the portion where the outer wall was, it can be disposed at a portion directly connectable to the injector without interfering with the valve operating mechanism on the cylinder head.

Therefore, it can be applied to an engine on an existing production line with only a slight design change.
The production line can also be handled with only a partial change.

2) Since the fuel supply pump is directly connected to the accumulator and a part of the fuel supply pump is formed as a part of the intermediate member and is sandwiched between the cylinder head and the cylinder head cover, the fuel supply pump is Can significantly improve the mounting rigidity. Therefore, even if the driving force is directly received from the engine, the problem of vibration and noise does not occur.

3) Since the pressure accumulator, which is ruggedly formed to withstand high pressure, is mounted on the cylinder head in the longitudinal direction, this pressure accumulator functions as a reinforcing member for the cylinder head, and Since the rigidity of the head is increased, it can contribute to reduction of vibration and noise.

4) In addition, since the injector is directly attached to the pressure accumulator without using a pipe and is integrally formed, the pipe is eliminated and the joint portion is reduced, so that the sealing performance is improved.

5) Furthermore, since the accumulator, the fuel supply pump and the injector are integrally assembled, these parts can be assembled in advance and handled as a module when assembling the engine, and the number of parts in the production line can be reduced. Therefore, the production efficiency of the engine can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view of an internal combustion engine to which a fuel injection device for an internal combustion engine according to an embodiment of the present invention is attached.

FIG. 2 is a perspective view of a pressure accumulating fuel injection device for the internal combustion engine of FIG. 1;

FIG. 3 is a partial perspective view showing a joint between an injector and a pressure accumulator according to the present invention.

FIG. 4 is a perspective view showing a mounting position adjusting mechanism according to the present invention.

FIG. 5 is a configuration diagram showing a conventional accumulator type fuel injection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Accumulation type fuel injection device of an internal combustion engine 2 Cylinder head 3 Cylinder head cover 10 Intermediate member 11 Accumulator (common rail) 12 Fuel supply pump (Supply pump) 13 Injector 14 Mounting position adjustment mechanism 15 Peripheral wall of intermediate member

Claims (4)

[Claims] 1. A pressure accumulating type fuel injection device comprising a pressure accumulator for accumulating fuel pressurized and supplied by a fuel supply pump and supplying the fuel to a plurality of injectors, wherein the accumulator is a cylinder head. A fuel injection device for an internal combustion engine, formed as an intermediate member between the cylinder head cover and the cylinder head cover, and mounted on the cylinder head. 2. The fuel injection device for an internal combustion engine according to claim 1, wherein the fuel supply pump is directly connected to the pressure accumulator to be integrated and formed as a part of the intermediate member. 3. The fuel injection device for an internal combustion engine according to claim 1, wherein the injector is directly connected to and integrated with the pressure accumulator, and is formed as a part of the intermediate member. 4. The fuel injection device for an internal combustion engine according to claim 3, wherein the injector is connected to the pressure accumulator via a mounting position adjusting mechanism.