JPH1073062A - Fuel system and fuel pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize fuel injection by suppressing pressure pulsation in a fuel passage and thus removing resonance therein. SOLUTION: A low-pressure fuel pump 13 and a high-pressure fuel pump 17 are interposed in a fuel passage 14 which connects a fuel tank 11 to delivery pipes 19 and 21 including respective fuel injection valves 18 and 20 arranged in an internal combustion engine, for feeding fuel to the fuel injection valves 18 and 20 upon the drive of the internal combustion engine. The high-pressure fuel pump 17 is provided at its discharge opening with resonators 26 and 27 for removing resonance in the fuel passage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuel system and a fuel pump particularly suitable for use in a direct injection internal combustion engine.
The pressure pulsation in the fuel passage is suppressed to eliminate resonance.

[0002]

2. Description of the Related Art As internal combustion engines of the type in which fuel is injected into cylinders, there are, for example, so-called direct injection internal combustion engines and direct injection internal combustion engines (direct injection internal combustion engines). Diesel engines are widely used. Are known. However, in recent years, an in-cylinder injection type engine has also been proposed for a spark ignition type engine (generally, a gasoline engine is used, and is hereinafter referred to as a gasoline engine).

[0003] In such a direct injection internal combustion engine, in order to improve the performance of the engine and reduce the exhaust gas, there is a tendency that the fuel injection pressure is increased to atomize the fuel spray and shorten the fuel injection period. Further, in an engine having a supercharging mechanism, a high fuel injection pressure corresponding to the supercharging pressure is required at the time of supercharging.
For example, a fuel supply device applied to a direct injection internal combustion engine is configured to obtain such a sufficiently high fuel injection pressure (for example, about several tens of atmospheres).

For example, Japanese Patent Application Laid-Open No.
There is one disclosed in Japanese Patent Application No. -77118. FIG. 18 schematically shows a fuel supply device applied to a conventional direct injection internal combustion engine.

As shown in FIG. 18, reference numeral 101 denotes a fuel tank, which has a fuel filter 102 and a low-pressure fuel pump 103. A check valve 105 and a fuel filter 106 are provided in a supply passage 104a of a fuel passage 104 connected from the low-pressure fuel pump 103.
The high-pressure fuel pump 107 is connected via the. Downstream of the high-pressure fuel pump 107, a first delivery pipe 109 provided with a fuel injection valve 108 and a second delivery pipe 111 provided with a fuel injection valve 110 are connected.
In addition, a first bypass passage 112 that bypasses the high-pressure fuel pump 107 is provided in the supply passage 104a, and a check valve 113 is mounted in the first bypass passage 112.

A high-pressure control valve 114 is connected to the downstream side of the second delivery pipe 111, and is connected to the fuel tank 101 by a return passage 104 b of the fuel passage 104. The return path 104b is provided with a second bypass passage 115 for bypassing the high-pressure control valve 114. The second bypass passage 115 is provided with an electromagnetic switching valve 116 and a throttle valve 117. Also, the fuel passage
A communication path 118 is provided between the upstream side of the high-pressure fuel pump 107 and the most downstream side of the return path 104b in the supply path 104a of the communication path 104, and a low-pressure control valve 119 is mounted in the communication path 118. I have.

Therefore, in such a fuel supply apparatus, the low-pressure fuel pump 103 of the fuel tank 101 sends out the fuel pressurized to a certain extent to the supply passage 104a of the fuel passage 104, and the low-pressure fuel is supplied by the high-pressure fuel pump 107. Further pressurization increases the fuel pressure to a predetermined pressure. At this time, the discharge pressure from the low-pressure fuel pump 103 is stabilized to a predetermined range by the low-pressure control valve 119, and the discharge pressure from the high-pressure fuel pump 107 is further stabilized to a predetermined range by the high-pressure control valve 114. Therefore, the fuel injection valve of each delivery pipe 109, 111
Fuel of a predetermined pressure is injected from 108 and 110.

[0008]

Incidentally, fuel is intermittently supplied to the fuel system by a positive displacement fuel pump, or
When discharging from a fuel system (including fuel injection by an injection valve), a pressure wave corresponding to the supply and discharge frequency is generated in the fuel system. When the frequency of the pressure wave serving as the vibration source approaches the natural frequency of the fuel system, a resonance phenomenon occurs, and the pressure amplitude in the fuel system may become extremely large.

In the above-described conventional fuel supply device,
Because of the in-cylinder injection internal combustion engine, the low-pressure fuel pump 103
The fuel pressurized to some extent by the high-pressure fuel pump 107
To further increase the fuel pressure to a predetermined pressure.
As the high-pressure fuel pump 107 for increasing the fuel pressure to a predetermined pressure, for example, there is a single plunger type pump. This single plunger type pump is a pump that discharges once per injection, and intermittently supplies fuel to the fuel system. Therefore, the single plunger type pump resonates at a certain engine rotation speed, and the pressure amplitude becomes extremely high. is there.

Here, experimental results regarding the pressure amplitude and the fuel pressure when a single plunger type pump is used will be described. FIG. 3 is a graph showing the fuel pressure amplitude with respect to the engine speed at the downstream end of the second delivery pipe. As can be seen from the graph of FIG. 3, in the conventional fuel supply apparatus described above, as indicated by the dotted line in the graph of FIG. 3, the fuel pressure amplitude increases when the engine speed is 5000 rpm. It can be seen that this is the resonance speed. FIG. 19 is a graph showing the fuel pressure with respect to the crank angle when the engine speed is 5000 rpm. FIG. 19A shows the fuel pressure at the upstream end (measurement point A) of the first delivery pipe, and FIG.
Indicates the fuel pressure at the downstream end (measurement point B) of the second delivery pipe. As can be seen from the graph of FIG. 19, the high amplitude at the measurement point A
The pressure wave generated at the time of fuel discharge by the above and the pressure wave that has returned after hitting the downstream end of the second delivery pipe 111 with this pressure wave overlap. On the other hand, the high amplitude at the measurement point B indicates that the high-pressure fuel pump 107
The pressure wave that has propagated to the downstream end of 11 and the pressure wave that has propagated toward the high-pressure fuel pump 107 and collided with the pressure wave that has returned to the downstream end of the second delivery pipe 111 again overlap. Further, due to the repetition, the pressure waves overlap to have a large pressure amplitude.

Thus, at a certain engine speed,
A pressure wave is generated for the fuel discharged from the high-pressure fuel pump 107 into the fuel passage 104, and a fuel flow path extending from the downstream end of the second delivery pipe 111 or the downstream end of the first delivery pipe to the fuel passage 104 is formed. The pressure wave is collided and reflected at the narrowing portion, and a large number of pressure waves overlap to have a large pressure amplitude, and the pressure amplitude becomes extremely high due to resonance. In a rotational speed region where this resonance occurs, there has been a problem that an excessive pressure amplitude hinders metering (flow rate adjustment) of the fuel or causes the pressure resistance of the fuel injection valve to be exceeded. In order to solve such a problem, it is conceivable to provide a known spring-type damper downstream of the high-pressure fuel pump. However, as the pressure of the fuel system increases, problems such as durability and the size of parts increase. And it becomes difficult to apply. It is also conceivable to use a high-pressure gas-filled damper that can reduce the size of parts.
Insufficient reliability.

[0012] Conventionally, as a device for reducing pressure pulsation in a liquid pipeline system, there is one disclosed in Japanese Patent Publication No. 2-47640. In the pressure pulsation reduction device of the liquid pipeline system, a resonance chamber hermetically sealed with a rigid material is arranged outside the liquid pipeline, and the resonance chamber and the inside of the pipeline are connected by a thin tube. The same liquid as the inside is filled, and the volume of the resonance chamber is set based on the inner diameter of the pipe and the frequency of the pressure pulsation to be reduced.

However, the pressure pulsation reducing device for a liquid pipeline system disclosed in Japanese Patent Publication No. 2-47640 is applied to a discharge pipe of a pump having an impeller.
In addition, this device absorbs and removes pressure pulsations propagating in the pipeline, with the number of blades and the number of rotations of the impeller being constant and always having the same waveform. However, in the fuel supply device, a resonance phenomenon occurs when the pressure pulsation wave of the fuel pump whose frequency changes according to the engine rotation speed approaches the natural frequency of the fuel system. Therefore, when the above-described pressure pulsation reducing device is applied to a fuel injection device of an internal combustion engine to absorb pressure pulsation, a problem arises in that a large number of resonance chambers having large capacities are required according to the rotation range of the engine. However, in practice, it is difficult to mount such a conventional pressure pulsation reducing device on a vehicle. Further, the conventional pressure pulsation reduction device does not eliminate the above-described resonance phenomenon.

The present invention solves such a problem, and provides a fuel system and a fuel pump that stabilize fuel injection by suppressing pressure pulsation in a fuel passage and removing resonance. A first object is to provide a relatively small one at an appropriate place, and a second object is to reliably remove resonance.

[0015]

A fuel system according to the present invention for achieving the above object has a fuel passage communicating between a fuel injection valve provided in an internal combustion engine and a fuel tank, and a fuel passage provided in the fuel passage. A high-pressure fuel pump that operates with the driving of the internal combustion engine to supply fuel to the fuel injection valve, and a resonator provided on the downstream side of the high-pressure fuel pump so as to remove resonance of the fuel passage. It is characterized by having.

Accordingly, when the high-pressure fuel pump is driven in accordance with the operation of the internal combustion engine, the pressure of the fuel in the fuel tank is increased to a predetermined pressure and supplied to the fuel injection valve through a fuel passage. At this time, a pressure wave is generated in the fuel passage along with the discharge of the high-pressure fuel by the high-pressure fuel pump, and this pressure wave is reflected in the fuel passage and tries to resonate. The reflected pressure wave is canceled by a resonator provided downstream of the high-pressure fuel pump, and resonance in the fuel passage is removed.

It is desirable that this resonator be provided downstream of the high-pressure fuel pump and near the discharge port, which is more effective in eliminating resonance. The resonator is preferably composed of a volume chamber having a predetermined volume, and a narrow path smaller than the diameter of the fuel passage communicating the fuel passage with the volume chamber.

In the fuel system according to the second aspect of the present invention, a closed portion is provided on the downstream side of the fuel injection valve, and the natural frequency of the resonator is such that the fuel frequency from the downstream side of the high-pressure fuel pump to the closed portion is It is set based on the natural frequency of the passage.

Therefore, the pressure wave generated in the fuel passage due to the discharge of the high-pressure fuel by the high-pressure fuel pump collides with the closing portion on the downstream side of the fuel injection valve and is reflected, and the natural frequency of the resonator is increased by the high pressure. By setting based on the natural frequency of the fuel passage from the downstream side of the fuel pump to the blockage, the frequency of the reflected pressure wave and the natural frequency of the resonator cancel each other out, effectively resonating in the fuel passage. Removed.

In the returnless fuel system having no pressure control valve or the like downstream of the high-pressure fuel pump, the closing portion provided downstream of the fuel injection valve is provided at the downstream end of the delivery pipe to which the fuel injection valve is attached. A pressure control valve is provided downstream of the high-pressure fuel pump, and serves as a pressure control valve in a return fuel system in which surplus fuel returns to the fuel tank through the pressure control valve.

Further, in the fuel system according to a third aspect of the present invention, the resonator is arranged near the downstream side of the high-pressure fuel pump, or
It is characterized by being provided in at least one of the upstream vicinity of the closing part.

Therefore, the influence of the pressure amplitude, that is, at least one of the vicinity near the downstream (vibration source) of the high-pressure fuel pump or the vicinity near the upstream (reflection source) side of the closing part, where the pressure amplitude increases. By providing the resonator, the resonance of the fuel system can be efficiently removed.

In particular, when the resonance frequency cannot be removed by a single resonator, a plurality of resonators may be provided either in the vicinity of the downstream side of the high-pressure fuel pump serving as the vibration source or in the vicinity of the upstream side of the blocking portion serving as the reflection source. It may be provided on one side, or may be provided near the downstream side of the high-pressure fuel pump and near the upstream side of the closing portion. Further, a delivery pipe for distributing the fuel discharged from the high-pressure fuel pump to the fuel injection valve is provided in the fuel passage, and the fuel injection valve is provided in the delivery pipe. In the case of a fuel system provided with a pressure control valve for adjusting the fuel pressure, it is preferable that the closing portion be a pressure control valve and the resonator be provided near the downstream of the high-pressure fuel pump and near the upstream of the pressure control valve. Further, it is more preferable that each resonator is formed integrally with the high-pressure fuel pump and the pressure control valve.

In the fuel system according to a fourth aspect of the present invention, first and second delivery pipes for distributing fuel discharged from the high-pressure fuel pump to the fuel injection valves are provided in the fuel passage.
The first and second delivery pipes are each provided with the fuel injection valve, and the first and second delivery pipes are connected in series by a communication pipe having a smaller diameter than each of the delivery pipes. (2) a fuel system in which a closing portion is provided on the downstream side of the delivery pipe, wherein a first resonator whose natural frequency is set based on a natural frequency of a fuel passage from the high-pressure fuel pump to the closing portion; A second resonator configured to set a natural frequency based on a natural frequency of a fuel passage from the high-pressure fuel pump to a downstream end of the first delivery pipe.

Accordingly, the fuel, which has been raised to a predetermined pressure by driving the high-pressure fuel pump, is supplied to the first and second delivery pipes through the fuel passage, distributed to the respective fuel injection valves, and injected. In the fuel passage, a pressure wave is generated due to the discharge of the high-pressure fuel by the high-pressure fuel pump, and the pressure wave reflected at the closed portion and the downstream end of the first delivery pipe tends to resonate. The pressure wave canceled by the resonator and reflected at the downstream end of the first delivery pipe is canceled by the second resonator, and the resonance in the fuel passage is removed.

The fuel system according to a fifth aspect of the present invention is characterized in that the resonator is formed integrally with the high-pressure fuel pump.

Therefore, since the resonator for absorbing the pressure wave is formed integrally with the high-pressure fuel pump, the size of the apparatus is reduced and the assembling workability is improved.

According to a sixth aspect of the present invention, in the fuel system, a shock absorber having a larger flow path cross-sectional area than the fuel passage is formed integrally with the high pressure fuel pump at a discharge port of the high pressure fuel pump. It is a feature.

Therefore, a pressure wave is generated and reflected in the fuel passage with the discharge of the high-pressure fuel by the high-pressure fuel pump, and a large number of the pressure waves are shifted and polymerized. In addition, the pressure amplitude in all the rotation speed regions is kept low, the pressure wave is reliably canceled by the resonator, and the resonance in the fuel passage is eliminated.

Preferably, the resonator is provided in the fuel passage near the shock absorber and is formed integrally with the discharge port of the high-pressure fuel pump.

In the fuel system according to a seventh aspect of the present invention, a low-pressure fuel pump is provided between the fuel tank and the high-pressure fuel pump, and a shock absorber is provided near an upstream side of the high-pressure fuel pump. It is a feature.

Therefore, the low-pressure fuel pump pressurizes the fuel from the fuel tank to some extent and sends it to the fuel passage. The low-pressure fuel is further pressurized by the high-pressure fuel pump, so that the fuel pressure can be increased to a predetermined pressure. The fuel is supplied to the fuel injection valve through the fuel passage. At this time, a pressure wave is generated in the fuel passage upstream of the high-pressure fuel pump along with the discharge of the low-pressure fuel by the low-pressure fuel pump. It is absorbed by a shock absorber provided downstream of the fuel pump. As a result, the fuel supply to the high-pressure fuel pump is stabilized, and accordingly, the fuel supply to the fuel injection valve by the high-pressure fuel pump is also stabilized.

The shock absorber is preferably a spring damper, a volume chamber, an accumulator, or the like.

In the fuel system according to the present invention, a delivery pipe for distributing fuel discharged from the high-pressure fuel pump to the fuel injection valve is provided in the fuel passage, and the resonator is provided upstream of the delivery pipe. A fuel system disposed, wherein the natural frequency of the fuel system in a predetermined section defined between the high-pressure fuel pump and the resonator is at least 2
kHz or more.

Therefore, the pressure wave generated by the discharge of the high-pressure fuel by the high-pressure fuel pump is propagated in the fuel passage, but the natural frequency of the fuel system in the fuel system for a predetermined section between the high-pressure fuel pump and the resonator is at least set. By setting the frequency to 2 kHz or more, a frequency band that is extremely sensitive to human hearing is removed. On the other hand, it is relatively easy to remove a natural frequency of 2 kHz or more, and the quietness in the vehicle interior is improved.

It is preferable that the resonator is disposed near the downstream side of the high-pressure fuel pump, and particularly near the fuel discharge port of the high-pressure fuel pump.

According to a ninth aspect of the present invention, in the fuel system according to the ninth aspect, the predetermined section fuel system includes a dead volume of a cylinder chamber in the high-pressure fuel pump, a volume chamber of the resonator, and a fuel connecting the cylinder chamber and the volume chamber. It is characterized by comprising a passage.

Therefore, by setting the natural frequency of the dead volume in the high-pressure fuel pump, the volume chamber of the resonator, and the fuel passage connecting them both to at least 2 kHz,
Frequency bands that are extremely sensitive to human hearing are removed.

In the fuel system according to a tenth aspect of the present invention, the dead volume of the high-pressure fuel pump is V _a , the volume of the volume chamber of the resonator is V _b , and a section connecting the cylinder chamber and the volume chamber. Assuming that the length of the fuel passage is L _a , the cross-sectional area of the section fuel passage is F _a , and the sound velocity of the fuel is a, the natural frequency fn is calculated by the following equation, and the calculated natural frequency fn is 2 kHz or more. The above parameters are set so that

(Equation 2)

Therefore, based on this equation, the natural frequency f
The dead volume volume V _a , the volume V _{b of} the resonator, and the length of the section fuel passage are set to L so that n becomes 2 kHz or more.
By setting the _a and cross-sectional area F _a, the vibration of the highly sensitive frequency band lower than 2kHz is reliably reduced to human hearing.

In this case, the dead volume volume V
less than 1.8cc to _a, it is desirable to about 1.2 cc, also, the length of a section fuel passage shorter than 50mm and L _a, it is desirable to 25mm or less, further, the diameter of the section fuel passage It is preferable to set it to about 8 mm, which is larger than 6 mm that can be mass-produced.

In the fuel pump of the present invention, a resonator is provided in a fuel passage for supplying fuel to a fuel injection valve, and a resonator for removing resonance of the fuel passage is integrally provided downstream of the fuel pump. It is characterized by having been done.

Therefore, the fuel pump supplies fuel to the fuel injection valve through the fuel passage, and the fuel injection valve injects fuel at a predetermined pressure. At this time, the fuel passage is supplied to the fuel passage along with the discharge of the fuel by the fuel pump. Pressure wave is generated, and this pressure wave is reflected in the fuel passage and tries to resonate.
This reflected pressure wave is canceled by the resonator,
Resonance in the fuel passage is eliminated. Further, since the resonator is mounted near the high-pressure fuel pump serving as a vibration source, resonance can be removed very efficiently. Further, since the resonator is provided integrally with the fuel pump, the size of the apparatus is reduced and the assembling workability is improved.

The fuel pump according to the twelfth aspect of the present invention
A shock absorber having a flow passage cross-sectional area larger than the fuel passage is formed integrally with the discharge port.

Accordingly, the fuel pump supplies the fuel to the fuel injection valve through the fuel passage. The fuel injection valve injects the fuel at a predetermined pressure. At this time, the pressure wave is supplied to the fuel passage along with the discharge of the fuel by the fuel pump. This pressure wave is reflected in the fuel passage and a number of pressure waves are shifted and polymerized. However, the waveform is shaped by the shock absorber, and the pressure wave is reliably canceled by the resonator.

[0046]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 schematically shows a fuel system as a first embodiment of the present invention applied to a fuel supply device for an internal combustion engine, FIG. 2 shows a schematic diagram of a high-pressure fuel pump device, and FIG. 3 shows an engine at a closed end of a fuel passage. FIG. 4 is a graph showing the fuel pressure amplitude with respect to the rotation speed, FIG. 4 is a graph showing the fuel pressure with respect to the crank angle when the first resonator is applied, and FIG. 5 is a graph showing the fuel pressure with respect to the crank angle when the first and second resonators are applied. Show.

The fuel supply device for an internal combustion engine according to the present embodiment
4 cycle gasoline engine as internal combustion engine, especially
It is applied to an in-cylinder injection V-type engine (displacement: 2000 to 4000 cc) that injects fuel directly into a cylinder. A low-pressure fuel pump and a high-pressure fuel pump are mounted in a fuel passage communicating between the fuel tank and the fuel injection valve, and two delivery pipes having the fuel injection valve are mounted downstream of the high-pressure fuel pump. The fuel passage is a return fuel system composed of a supply passage for supplying fuel from the fuel tank to the fuel injection valve and a return passage for returning fuel not injected by the fuel injection valve to the fuel tank. I have.

That is, as shown in FIG. 1, reference numeral 11 denotes a fuel tank, which includes a fuel filter 12 and a low-pressure fuel pump 13.
have. A high-pressure fuel pump 17 is connected via a check valve 15 and a fuel filter 16 to a feed path 14 a of a fuel passage 14 connected to the low-pressure fuel pump 13. The high-pressure fuel pump 17 has a fuel injection valve 1
Delivery pipe 19 equipped with the fuel injection valve 8 and the fuel injection valve 2
0 is connected to the second delivery pipe 21 to which 0 is attached. In addition, a first bypass passage 22 that bypasses the high-pressure fuel pump 17 is provided in the feed passage 14a, and a check valve 23 is mounted in the first bypass passage 22.

The low-pressure fuel pump 13 is a feed pump provided in the fuel tank 11 upstream of the feed passage 14a of the fuel passage 14. An electric pump is used. The fuel in the fuel tank 11 flows to the downstream side of the feed path 14a while filtering. The pressurization of the fuel by the low-pressure fuel pump 13 at this time is performed from an atmospheric pressure state to several atmospheric pressures. The low-pressure fuel pump 13
Are started when the engine is started and stopped when the engine is stopped. Of course, the predetermined discharge pressure can be generated without depending on the rotation speed of the engine.

On the other hand, the high-pressure fuel pump 17 pressurizes the fuel discharged from the low-pressure fuel pump 13 to about several tens of atmospheres. The low-pressure fuel pump 17 is controlled by a check valve 15 provided in the middle of the feed line 14a. The discharge pressure from the fuel pump 13 is maintained, and the fuel is further filtered by the fuel filter 16. For the high-pressure fuel pump 17, an engine-driven pump (hereinafter, referred to as an engine-driven pump) such as a reciprocating compression pump, which is advantageous as a high-pressure pump in terms of pump efficiency and cost, is used. The engine operates directly in conjunction with the operation of the engine, and generates a discharge pressure in accordance with the rotation speed of the engine.

As described above, the fuel flowing through the supply passage 14a of the fuel passage 14 is supplied to the upstream of the high-pressure fuel pump 17 so that the fuel can be supplied to the delivery pipes 19 and 21 by bypassing the high-pressure fuel pump 17. A first bypass passage 22 that connects the side portion and the downstream portion is provided, and a check valve 23 that allows fuel to pass only from the upstream side to the downstream side of the feed passage 14a is provided in the first bypass passage 22. I have. This check valve 23 opens the first bypass passage 22 if the high-pressure fuel pump 17 does not operate sufficiently and the fuel pressure is lower on the downstream side than on the upstream side of the high-pressure fuel pump 17. Operates sufficiently and the high-pressure fuel pump 17
When the fuel pressure is higher on the downstream side than on the upstream side, the first bypass passage 22 is closed.

Incidentally, the in-cylinder injection type engine of this embodiment shows a case where a reciprocating compression pump is applied, and this reciprocating compression pump supplies intermittent fuel supply to the fuel system. Therefore, a pressure wave is generated for the fuel discharged from the high-pressure fuel pump 17 into the fuel passage 14, and the pressure wave collides and reflects at the closed end of the fuel passage 14 and at a portion where the fuel flow path becomes narrow. At the engine rotation speed, a large number of pressure waves overlap with each other to have a large pressure amplitude, and resonance occurs. For this reason, in the high-pressure fuel pump 17 used in the present fuel system, a spring damper 24 as a shock absorber is provided on the upstream side of the high-pressure fuel pump 17, while the fuel passage 14 is provided on the downstream side of the high-pressure fuel pump 17. Also, a buffer container 25 as a buffer device having a large flow path cross-sectional area and first and second resonators 26 and 27 for removing resonance of the fuel passage are provided. The spring damper 24, the buffer container 25, and the resonators 26 and 27 are integrally formed with the high-pressure fuel pump 17 to constitute a high-pressure fuel pump device 28.

Here, the high-pressure fuel pump device 28 will be specifically described. As shown in FIG. 2, the housing 41 is formed with a supply port 42 that communicates with the downstream end of the supply path 14 a of the fuel path 14 from the low-pressure fuel pump 13. The flow path communicates with the supply port 42. 43 is communicated with the spring damper 24. The spring damper 24 is provided with a high-pressure fuel pump 17 that intermittently feeds fuel in order to use the fuel continuously sent from the low-pressure fuel pump 13 installed in the fuel tank 11 without waste. When the intake valve is closed, the fuel is temporarily stored, and when the intake valve is opened, the fuel is added to the fuel sent from the low-pressure fuel pump 13 and supplied to the high-pressure fuel pump 17. Note that the high-pressure fuel pump 17 has a function of suppressing pulsation on the low-pressure side caused by intermittent driving of the low-pressure fuel pump 13, which continuously transports fuel. On the other hand, in the high-pressure fuel pump 17,
A sleeve 44 is fixed to the housing 41 by a fixing ring 45.
6 is movably supported. Also, this piston 4
A cam 47 is provided at one end in the axial direction of the piston 6 so as to be directly linked to the operation of the engine. A compression spring 48 interposed between the other end of the piston 46 in the axial direction and the housing 41 causes one end of the piston 46 to move. Are in pressure contact with the cam 47. A sealing member 49 for preventing fuel leakage is provided between the sleeve 44 and the piston 46.

A suction passage 51 is provided in a cylinder chamber 50 formed by reciprocating a piston 46 through the sleeve 44.
And one end of the discharge path 52 communicate with each other, and reed valves 53a and 53b are provided therebetween. The other end of the suction path 51 communicates with the spring damper 24 and the discharge path 5
The other end of 2 communicates with buffer container 25. The first resonator 26 includes a volume chamber 26a having a certain predetermined volume (for example, 8 cc), and a small-diameter passage 26 smaller than a diameter of a fuel passage connecting the discharge passage 52 (fuel passage 14) and the volume chamber 26a.
b. The first resonator 26 communicates with the discharge path 52 on the downstream side of the buffer container 25 through the small-diameter path 26b. The buffer container 25 communicates with the discharge port 55 through the communication path 54, and the discharge port 55 The first delivery pipe 19 communicates with a supply path 14 a communicating with the first delivery pipe 19.

In the high-pressure fuel pump device 28, the first resonator 26 and the first
Although not shown, a second resonator 27 (not shown) having a smaller volume chamber than the volume chamber 26a of the resonator 26 is integrally formed in communication, but the description is omitted here. Further, the high-pressure fuel pump device 28 is provided with a first bypass passage 22 connecting the suction passage 51 and the discharge passage 52 so as to bypass the high-pressure fuel pump 17 and a check valve 23 (see FIG. 1). However, the description is omitted here.

Accordingly, in the high-pressure fuel pump device 28, the piston 46 reciprocates in the axial direction by rotating the cam 47 directly in conjunction with the operation of the engine. Low pressure fuel is supplied to the supply port 42 through the passage 14a. At this time, when the piston 46 moves to one side in the axial direction (downward in FIG. 2), the cylinder chamber 50 becomes negative pressure, and the low-pressure fuel in the flow passage 43 and the suction passage 51 is transferred to the cylinder chamber 50 via the reed valve 53a. Inhaled. When the piston 46 moves to the other axial direction (upward in FIG. 2), the cylinder chamber 50 is pressurized to pressurize the internal fuel to a predetermined pressure, and the high-pressure fuel passes through the reed valve 53b. The liquid is discharged to the discharge path 51, flows to the discharge port 55 via the buffer container 25 and the communication path 54, and flows from the discharge port 55 to the first port.
It flows to the supply path 14 a communicating with the delivery pipe 19.

The high-pressure fuel pump device 28 is configured as described above. As shown in FIG. 1, the fuel discharged from the high-pressure fuel pump device 28 (high-pressure fuel pump 17) is distributed to the fuel injection valves 18 and 20. First and second delivery pipe 1
9 and 21 are connected in series by a communication pipe 14 c having a smaller diameter than the delivery pipes 19 and 21. Therefore,
Assuming that the high-pressure fuel pump 17 supplies the fuel injected by the fuel injection valves 18 and 20 at one time to the respective delivery pipes 19 and 21, a high-pressure control valve device described later is provided near the downstream end of the second delivery pipe 21. 33, the downstream end 21a (high-pressure control valve device 33) of the second delivery pipe 21 is considered as a closed portion, and the pressure wave generated when the high-pressure fuel pump 17 discharges high-pressure fuel is The light is collided and reflected by the closing portion 21a. In addition, the first delivery pipe 19 and the second delivery pipe 21 are formed of the communication pipe 1 having a small diameter.
The pressure wave generated when the high-pressure fuel pump 17 discharges high-pressure fuel is collided and reflected at the downstream end 19 a of the first delivery pipe 19 because the high-pressure fuel pump 17 discharges high-pressure fuel.

From the above, the first resonator 26
The natural frequency is set based on the natural frequency of the fuel passage 14 from the high-pressure fuel pump 17 to the downstream end 21a (actually, the high-pressure control valve device 33) of the second delivery pipe 21, and the second resonator 27 Is set based on the natural frequency of the fuel passage 14 from the high-pressure fuel pump 17 to the downstream end 19a of the first delivery pipe 19. Note that the downstream end of the second delivery pipe 21 is closed
As described later, the high pressure control valve 29 is provided in the fuel passage 14 on the downstream side of the second delivery pipe 21.
Since the pressure in the fuel passage 14 downstream of the high-pressure fuel pump 17 is adjusted by the high-pressure control valve 29, the portion from the high-pressure fuel pump 17 to the closing portion 21a is not completely closed. Therefore, in practice, the natural frequency is set in consideration of the modulation amount of the high-pressure control valve 29 and the like with respect to the length from the high-pressure fuel pump 17 to the closing portion 21a.

Here, a method of setting the natural frequency of each of the resonators 26 and 27 will be specifically described.

The natural frequency of the fuel passage: From the fn high-pressure fuel pump 17 to the closing part 21a, the impedance at each part is set to Z _{1 to} Z as shown in FIG.
_{Assume 5} . At this time, for example, the impedances Z ₁ and Z ₂ before and after the fuel passage from the high-pressure fuel pump 17 to the upstream end of the first delivery pipe 19 can be obtained from the following equation (1) using the acoustic impedance method.

[0062]

(Equation 3)

The relationship between the impedance Z ₂ , Z ₃ before and after the fuel passage from the upstream end to the downstream end of the first delivery pipe 19 and the _second impedance from the downstream end of the first delivery pipe 19
The impedance Z ₃ , Z ₄ before and after the fuel passage to the upstream end of the delivery pipe 21 and the impedance Z ₄ , Z ₅ before and after the fuel passage from the upstream end to the downstream end of the second delivery pipe 21 are formulated, and the high-pressure fuel is formulated. The fuel passage from the pump 17 to the closing portion 21a is closed at both ends, that is, Z ₁ =
Each angular velocity ωn that satisfies the condition of Z ₅ = ∝ is the natural angular velocity of this fuel passage, and the natural frequency can be obtained from the following equation (2).

[0064]

(Equation 4)

The natural frequency of the resonator: frz On the other hand, the natural frequency of the resonator can be obtained from the following equation (3) using the Helmholtz resonance box equation.

[0066]

(Equation 5)

In this way, the resonators 26, 27
By making the natural frequency frz of the fuel passage equal to the natural frequency fn of the fuel passage, an increase in pressure amplitude at the time of resonance can be suppressed. Here, the second resonator 27 is smaller than the first resonator 26. For example, the first resonator 26 is 5 to 10 cc, and the second resonator 27 is 1 to 5 cc.
It is. In this case, when air mixes with the fuel flowing in the fuel passage 14, the sound speed a of the fuel changes. However, the natural frequency fn of the fuel passage and the natural frequency frz of the resonators 26 and 27 are functions of the sound speed a. They are set so that they do not adversely affect each other.

On the other hand, the buffer container 25 is
7 forms a waveform in which a pressure wave generated when the high-pressure fuel is discharged and a pressure wave that is reflected by the pressure wave at the downstream end 19a of the first delivery pipe 19 and the closed end 21a of the second delivery pipe 21 overlap. For example, it is about 5 to 30 cc. Further, the spring damper 24 absorbs a pressure wave generated when the low-pressure fuel pump 13 discharges low-pressure fuel to the high-pressure fuel pump 17 through the supply path 14 a of the fuel passage 14, and supplies fuel supplied to the high-pressure fuel pump 17. It is to stabilize.

The high-pressure fuel pump 1 is connected to the return passage 14 b of the fuel passage 14 on the downstream side of the second delivery pipe 21.
A high-pressure control valve 29 for adjusting the discharge pressure from the pressure 7 to a set pressure is provided, and the return path 14 b is connected to the fuel tank 11. The high-pressure control valve 29 is closed until the discharge pressure from the high-pressure fuel pump 17 exceeds a set pressure (for example, 50 atm). When the discharge pressure exceeds the set pressure, the fuel corresponding to the pressure exceeds the set pressure. Is returned to the fuel tank 11 through the return path 14b, and the fuel injection valves 18, 20
Is stabilized at a predetermined pressure.

The return path 14b is provided with an upstream portion of the high pressure control valve 29 so that the fuel of the fuel injection valves 18 and 20 can be discharged to the fuel tank 11 by bypassing the high pressure control valve 29. A second bypass passage 30 connecting the downstream portion is provided. This second bypass passage 3
Numeral 0 is for discharging vapor (bubbles) contained near the fuel injection valve 17 in the fuel passage 14 at an early stage of engine start. Therefore, an electromagnetic switching valve 31 that opens and closes the second bypass passage 30 is provided in the second bypass passage 30. The solenoid-operated switching valve 31 opens the second bypass passage 30 when the power is received, and closes the second bypass passage 30 when the power is stopped. Then, when an ignition key switch (not shown) is operated to the starter position, the ignition key switch is actuated in conjunction therewith to open the second bypass passage 30, thereby discharging the vapor contained in the vicinity of the fuel injection valves 18, 20. Is stopped after a lapse of a predetermined time to complete the second bypass passage 3
0 is closed.

Further, a low pressure control valve 32 is provided in the return passage 14b of the fuel passage 14 where the second bypass passage 30 joins, and the high pressure control valve 29, the second bypass passage 30, the electromagnetic switching valve 31, and the low pressure control valve 31 The high-pressure control valve device 33 is formed by integrally forming the control valve 32 with the control valve 32. The low-pressure control valve 32 causes the fuel pressure to drop sharply from upstream of the high-pressure control valve 29 with the opening operation of the high-pressure control valve 29, causing pulsation in the fuel passage 14 downstream of the high-pressure control valve 29. Has been suppressed.

Further, the fuel filter 1 in the fuel supply passage 14 between the supply passage 14a and the return passage 14b, that is, the fuel filter 1
6, a communication path 34 is provided between a portion upstream of the high-pressure fuel pump device 28 and the most downstream portion of the return path 14b.
Is provided. The communication path 34 is provided with a low-pressure control valve 35 for adjusting the discharge pressure from the low-pressure fuel pump 13 to a set pressure. The low-pressure control valve 35 is closed until the discharge pressure from the low-pressure fuel pump 13 exceeds a set pressure (for example, 3 atm). Is returned directly to the fuel tank 11 so that the high-pressure fuel pump device 28
The pressure of the fuel supplied to the pump is stabilized near the set pressure. Of course, the low-pressure fuel pump 13 is set so that the discharge pressure thereof is equal to or higher than the set pressure so that the set pressure can be obtained.

Hereinafter, the operation of the fuel supply device for an internal combustion engine according to the present embodiment configured as described above will be described. As shown in FIG. 1, when the engine is started by turning an ignition key switch (not shown) to a starter ON position, the low-pressure fuel pump 13
And the high-pressure fuel pump 17 operates. Low pressure fuel pump 1
In the case of No. 3, an output pressure state of a predetermined pressure (several atmospheric pressures) is immediately obtained after the start, but the rotation of the engine does not increase immediately after the start of the engine, so that the high-pressure fuel pump 17 does not generate a sufficient discharge pressure.

For this reason, immediately after the engine is started, the high-pressure fuel pump 17 becomes rather a resistance to the flow of fuel in the fuel passage 14 due to the discharge pressure from the low-pressure fuel pump 13. Since fuel is supplied to the first and second delivery pipes 19 and 21 through the first bypass passage 22 provided in parallel with the fuel injection valve 17, the pressure adjusted by the low pressure control valve 35 from each of the fuel injection valves 18 and 20. Fuel injection can be performed at a fuel pressure of the order.

In other words, the first bypass passage 22 is provided with the check valve 23. The check valve 23 is provided when the fuel pressure is lower on the downstream side of the high-pressure fuel pump 17 than on the upstream side. Since the first bypass passage 22 is opened, if the high-pressure fuel pump 17 does not generate a sufficient discharge pressure, the first and second
The fuel is supplied to the delivery pipes 19 and 21 at a pressure on the order of the adjustment level of the low-pressure control valve 35.

Generally, immediately after the start of the engine, the amount of fuel required for combustion is small, the pulse width of the fuel injection is short, and the pulse timing of the fuel injection is the same as that of the conventional multipoint injection (MPI). Similarly,
This is performed only during the intake stroke. Therefore, even if the fuel pressure is about the adjustment pressure level of the low-pressure control valve 35, if the fuel pressure is stable, the rotation of the engine can be smoothly increased. . As a result, the discharge flow rate of the high-pressure fuel pump 17 increases as the engine speed increases, and the discharge pressure also increases smoothly.

When the high-pressure fuel pump 17 starts operating to some extent, the fuel pressure becomes higher on the downstream side than on the upstream side of the high-pressure fuel pump 17, and the check valve 23 closes the first bypass passage 22. And the high-pressure fuel pump 1
7 without loss.
The fuel pressure on the downstream side of is increased to increase the fuel pressure beyond the adjustment pressure of the high-pressure control valve 29.

As a result, the discharge pressure of the high-pressure fuel pump 17 rises to a sufficient level, and fuel can be injected from each of the fuel injection valves 18 and 20 at a fuel pressure as high as the adjustment pressure of the high-pressure control valve 29. In this way, for example, in an in-cylinder injection type internal combustion engine, it is required to shorten the fuel injection period (that is, the pulse width of the fuel injection) while smoothly increasing the engine rotation speed immediately after the engine start. In addition, a high fuel injection pressure required according to the supercharging pressure at the time of supercharging can be obtained.

On the other hand, for example, in the case of an internal combustion engine for an automobile, after the engine stops, the temperature rise in the engine room caused by the stop of the engine cooling system, the pressure control valve 2
Due to fuel leaks at the fuel injectors 9 and 35 and the fuel injection valves 18 and 20, vapor (bubbles) is generated in the fuel passage 14, and when the engine is started next time, fuel is supplied in a state where the vapor is contained in the fuel passage 14. Be started. In particular, vapor present near the fuel injection valves 18 and 20 causes delays and variations in the rise of the fuel pressure to be injected, or causes idle injection from the fuel injection valves 18 and 20, making it difficult to control the fuel injection. I do.

The vapor existing in the vicinity of the fuel injection valves 18 and 20 passes through the return passage 14b of the fuel passage 14 when the fuel flows through the fuel passage 14 by starting the fuel supply device. The high-pressure control valve 2 provided in the return path 14b may be discharged together with the circulating fuel.
9 closes when the fuel pressure is not high and shuts off the fuel flow. Accordingly, vapor discharge is also hindered, but in this device, the second bypass passage 30 is provided in parallel with the high-pressure control valve 29, and the electromagnetic switching valve 31 that opens and closes the second bypass passage 30 is provided with a predetermined value after the engine is started. During the opening period, fuel flows through the second bypass passage 30 and the high-pressure control valve 29.
Circulates downstream of the return path 14b while bypassing the path.

The vapor contained in the fuel passage 14 near the fuel injection valves 18 and 20 together with the fuel flow is
It is discharged to the outside. Further, even if the second bypass passage 30 is open, the second bypass passage 3
A low pressure control valve 32 is provided in the return path 14b downstream of
Since the low-pressure control valve 32 maintains the fuel pressure near the fuel injection valves 18 and 20 at least close to the set pressure controlled by the low-pressure control valve 35, the fuel is released from the fuel injection valves 18 and 20 while discharging the vapor. Is sufficient when the engine is started.

Therefore, it is possible to obtain a certain fuel injection pressure while preventing a phenomenon such as a delay or variation in the rise of the fuel pressure caused by the vapor immediately after the start of the engine and an idle injection. Thus, the engine rotation speed can be smoothly increased while maintaining good engine combustion, and for example, the practicality of an in-cylinder injection type engine can be greatly improved. Also, the electromagnetic switching valve 31 that opens and closes the second bypass passage 30 closes after a predetermined time (relatively short time) has elapsed after the engine has been started and the vapor has been sufficiently discharged. The fuel pressure can be increased to the pressure controlled by the control valve 29. For example, a sufficient fuel injection pressure can be obtained during high-speed operation or the like.

By the way, when the fuel flows as described above in the present apparatus, that is, the fuel pressurized low by the low pressure fuel pump 13 is pressurized high by the high pressure fuel pump 17 and raised to a predetermined pressure. When discharged into the fuel passage 14,
Since the high-pressure fuel pump 17 intermittently supplies fuel to the fuel passage 14 based on the engine speed, the pressure amplitude becomes extremely high due to resonance at a certain engine speed.

That is, as shown by the dotted line in FIG. 3, when the engine speed is 5000 rpm, the pressure amplitude of the fuel is large, and this is the resonance speed. The high-pressure fuel pump device 28 includes the high-pressure fuel pump 1
7, a spring damper 24 is provided on the upstream side, and a buffer container 25 and first and second resonators 26 and 27 are provided on the downstream side.

At the same time as the high-pressure fuel pump 17 discharges high-pressure fuel, a pressure wave is generated, and this pressure wave propagates through the fuel passage 14 to the downstream side. And, for example, this pressure wave is the first
From the delivery pipe 19 to the communication pipe 14c, a small diameter portion,
That is, it collides with the downstream end 19a of the first delivery pipe 19 and is reflected. In addition, the downstream end of the second delivery pipe 21 collides with the closing portion 21a and is reflected. Then, FIG. 19 (a)
As shown in FIG. 1, the upstream end of the first delivery pipe 19 (FIG. 1)
At the measurement point A), the pressure wave generated when the high-pressure fuel pump 17 discharges fuel and the pressure wave
9 and the downstream end of the second delivery pipe 21 have a high amplitude in which the pressure wave reflected by the collision with the closing portion 21a and the like overlaps. On the other hand, as shown in FIG. 19B, at the downstream end of the second delivery pipe 21 (measurement point B in FIG. 1), the pressure wave generated at the time of fuel discharge of the high-pressure fuel pump 17 propagates, Pressure wave is high pressure fuel pump 17
The pressure wave reflected by the discharge port and returned again has a high amplitude that overlaps.

In the high pressure fuel pump device 28 of the present device, two resonators 26, 2 are provided at the discharge port of the high pressure fuel pump 17.
7 is attached, and the natural frequency of the first resonator 26 is
It is set based on the natural frequency of the fuel passage 14 from the high-pressure fuel pump 17 to the closing portion 21a of the second delivery pipe 21. Therefore, the pressure wave reflected by the closing portion 21 a of the second delivery pipe 21 propagates upstream through the fuel passage 14 and reaches the vicinity of the high-pressure fuel pump 17, where it is canceled by the natural frequency of the first resonator 26. Therefore, the resonance between the reflected pressure wave and the pressure wave generated when the high-pressure fuel pump 17 discharges the high-pressure fuel in the fuel passage 14 is suppressed. The natural frequency of the second resonator 27 is set based on the natural frequency of the fuel passage 14 from the high-pressure fuel pump 17 to the downstream end 19a of the first delivery pipe 19. Accordingly, the pressure wave reflected at the downstream end 19 a of the first delivery pipe 19 propagates upstream in the fuel passage 14 and reaches the vicinity of the high-pressure fuel pump 17, where it is canceled by the natural frequency of the second resonator 27. Therefore, the resonance between the reflected pressure wave and the pressure wave generated when the high-pressure fuel pump 17 discharges the high-pressure fuel in the fuel passage 14 is suppressed.

This is clear from the graphs of FIGS. 3, 4 and 5. That is, conventionally, as shown by the dotted line in FIG. 3, the pressure amplitude of the fuel was large when the engine speed was 5000 rpm, but the two resonators 26,
In the fuel system of the present embodiment equipped with 27, the pressure amplitude of the fuel when the engine speed is 5000 rpm is reduced as shown by the solid line in FIG. FIG. 4 shows the measurement results when only the first resonator 26 is mounted. As shown in FIG.
At the upstream end (measurement point A) of the high-pressure fuel pump 1, the pressure wave reflected by colliding with the closing portion 21 a of the second delivery pipe 21 is canceled by the first resonator 26.
7, only the pressure wave generated at the time of fuel discharge has a low amplitude. On the other hand, as shown in FIG. 4B, at the downstream end (measurement point B) of the second delivery pipe 21, the second delivery pipe 2
The pressure wave reflected by the collision with the first closed portion 21a is canceled by the first resonator 26 at the discharge port of the high-pressure fuel pump 17, so that the pressure wave does not return again but is generated when the high-pressure fuel pump 17 discharges fuel. The pressure wave has a low amplitude of only the propagated pressure wave.

FIG. 5 shows the measurement results when both the first and second resonators 26 and 27 are mounted. As shown in FIG. 5A, the upstream end of the first delivery pipe 19 is measured. At (measurement point A), the pressure wave reflected by colliding with the closing portion 21a of the second delivery pipe 21 is canceled by the first resonator 26, and the first delivery pipe 1
The pressure wave reflected upon colliding with the downstream end 19a of 9 is canceled by the second resonator 27, so that only the pressure wave generated when the high-pressure fuel pump 17 discharges fuel has a low amplitude. On the other hand, as shown in FIG. 5B, at the downstream end (measurement point B) of the second delivery pipe 21, the pressure wave colliding with the closing portion 21 a of the second delivery pipe 21 is reflected by the high-pressure fuel pump 17. The downstream end 19 of the first delivery pipe 19 is canceled by the first resonator 26 at the discharge port.
The pressure wave reflected upon collision with a is canceled by the second resonator 27, so that it does not return here again,
The pressure wave generated when the high-pressure fuel pump 17 discharges the fuel has a low amplitude of only the propagated pressure wave.

Further, a buffer container 25 is attached to the discharge port of the high-pressure fuel pump 17 between the two resonators 26 and 27. As described above, the pressure wave generated when the high-pressure fuel pump 17 discharges the high-pressure fuel is the second pressure wave.
It collides with the closing portion 21 a of the delivery pipe 21 and the downstream end 19 a of the first delivery pipe 19, is reflected, and returns to the discharge port of the high-pressure fuel pump 17. At this time, the waveform of the pressure wave returning to the discharge port of the high-pressure fuel pump 17 is slightly shifted due to the influence of the high-pressure control valve 29 and the like downstream of the second delivery pipe 21. The buffer container 25 can make the cycle of the shifted pressure wave substantially the same, and can suppress the pressure amplitude in all the rotation regions to be low. In addition, the first and second resonators 26 and 27 can cancel the pressure wave. Therefore, by performing appropriate metering (flow rate adjustment) of the fuel, the high-pressure fuel pump 17 can discharge an appropriate amount of fuel at an appropriate pressure.

When the low-pressure fuel pump 13 discharges the low-pressure fuel to the supply path 14a leading to the high-pressure fuel pump 17,
A low pressure wave is generated with the discharge of the low pressure fuel. Therefore, a spring damper 24 is mounted on the upstream side of the high-pressure fuel pump 17. Therefore, the pressure wave generated when the low-pressure fuel pump 13 discharges the low-pressure fuel acts on the feed path 14 a of the fuel passage 14 between the low-pressure fuel pump 13 and the high-pressure fuel pump 17. Is absorbed by the spring damper 24. In addition, a volume chamber, an accumulator, or the like may be used as the shock absorbing device in addition to the spring damper 24.

In the above-described first embodiment, the first resonator 26 and the second resonator 27 are provided in the buffer container 25 on the fuel passage 14, but the mounting position is not limited to this. FIG. 6 schematically shows a modification of the high-pressure fuel pump device when the fuel system according to the first embodiment of the present invention is applied to a fuel supply device for an internal combustion engine. Note that members having the same functions as those described in the above-described embodiment are denoted by the same reference numerals, and redundant description will be omitted.

As shown in FIG. 6, the high pressure fuel pump 28A
, The supply passage 14 a of the fuel passage 14 is connected to a high-pressure fuel pump 17, and a buffer container 25 having a larger flow path cross-sectional area than the fuel passage 14 is connected downstream of the high-pressure fuel pump 17. Downstream of the buffer container 25, first and second resonators 26 and 27 for removing resonance of the fuel passage 14 are connected. Therefore, the pressure wave generated when the high-pressure fuel pump 17 discharges high-pressure fuel is reflected in the fuel passage 14 and returns to the discharge port of the high-pressure fuel pump 17. At this time, diffusion in the fuel passage is suppressed by the buffer container 25, and is canceled by the natural frequencies of the first resonator 26 and the second resonator 27, so that resonance in the fuel passage 14 can be removed.

FIG. 7 schematically shows a fuel system according to a second embodiment of the present invention applied to a fuel supply device for an internal combustion engine. Note that members having the same functions as those described in the above-described first embodiment are denoted by the same reference numerals, and redundant description will be omitted.

As shown in FIG. 7, the high pressure fuel pump 28B
, The supply passage 14 a of the fuel passage 14 is connected to a high-pressure fuel pump 17, and a buffer container 25 having a larger flow path cross-sectional area than the fuel passage 14 is connected downstream of the high-pressure fuel pump 17. A second resonator 27 is connected downstream of the buffer container 25. In the high-pressure control valve device 33B, the first resonator 26 is connected downstream of the second delivery pipe 21 and upstream of the high-pressure control valve 29. The first resonator 26 has a natural frequency set based on the natural frequency of the fuel passage 14 from the high-pressure fuel pump 17 to the high-pressure control valve 29, and the second resonator 27 has a first frequency from the high-pressure fuel pump 17. The natural frequency is set based on the natural frequency of the fuel passage 14 to the downstream end 19a of the delivery pipe 19.

Therefore, a pressure wave generated when the high-pressure fuel pump 17 discharges high-pressure fuel is reflected by the high-pressure control valve 29 in the fuel passage 14. This reflected wave is canceled by the natural frequency of the first resonator 26, and the resonance in the fuel passage 14 can be suppressed. At this time, the reflected wave is not diffused in the fuel passage by the buffer container 25, and the resonance can be effectively suppressed. Further, the pressure wave generated when the high-pressure fuel pump 17 discharges the high-pressure fuel is the first wave in the fuel passage 14.
The light is reflected at the downstream end 19 a of the delivery pipe 19. This reflected wave is canceled by each natural frequency of the second resonator 27, and resonance in the fuel passage 14 can be suppressed.

As described above, the reflected wave from the high-pressure control valve 29 is transmitted to the first resonator 2 provided near the high-pressure control valve 29.
6 can be effectively removed. Further, the first resonator 26 is formed integrally with the high-pressure control valve 29 and the like to constitute the high-pressure fuel pump 28B, and is reduced in size and has good assemblability. Although the first resonator 26 is provided only on the upstream side of the high-pressure control valve 29,
And may be provided on the downstream side of the high-pressure fuel pump 17 as in the first embodiment.

FIG. 8 schematically shows a third embodiment of the present invention in which a fuel system is applied to a fuel supply device for an internal combustion engine. Members having the same functions as those described in the first and second embodiments described above are denoted by the same reference numerals, and redundant description will be omitted.

In this embodiment, the present invention is applied to a fuel injection device for a series-type internal combustion engine. As shown in FIG. 8, a delivery having a fuel injection valve 18 in a fuel passage 14 downstream of a high-pressure fuel pump device 28C is provided. The delivery pipe 19 is connected to a pipe 19, and the delivery pipe 19 communicates with the fuel injection valve 18.
9b and a return path 19c communicating with the high-pressure control valve 29. The downstream side of the delivery pipe 19 is connected to the high-pressure control valve device 33C. In this high-pressure fuel pump 28C, the supply passage 14a of the fuel passage 14 is connected to the high-pressure fuel pump 17, and a buffer vessel having a passage cross-sectional area larger than that of the fuel passage 14 is provided downstream of the high-pressure fuel pump 17. The second resonator 27 is connected to the downstream side of the buffer container 25. In the high-pressure control valve device 33C, the delivery pipe 1
9 and on the upstream side of the high pressure control valve 29, the first
The resonator 26 is connected. The first resonator 26 is connected to the high-pressure control valve 2 by the high-pressure fuel pump 17.
The natural frequency is set based on the natural frequencies of the fuel passage 14 up to nine. In the fuel injection device for a serial internal combustion engine, only the high pressure control valve 29 is used as a reflection source.
Although only the first resonator 26 that removes the reflected wave is sufficient, the second resonator 2 is used to enhance the resonance removal effect.
7 are provided.

Therefore, the pressure wave generated when the high-pressure fuel pump 17 discharges high-pressure fuel is reflected by the high-pressure control valve 29 in the fuel passage 14 and returns to the discharge port of the high-pressure fuel pump 17. At this time, the amplitude of the pressure pulsation can be suppressed low by the buffer container 25, and the resonance in the fuel passage 14 can be suppressed by being canceled out by the natural frequency of the first resonator 26. Although the two resonators 26 and 27 are provided in the fuel passage 14, only the first resonator 26 may be provided when there is no change in the resonance frequency.

FIG. 9 schematically shows a fuel system according to a fourth embodiment of the present invention applied to a fuel supply device for an internal combustion engine. Note that members having the same functions as those described in the first, second, and third embodiments are given the same reference numerals, and redundant description will be omitted.

In the present embodiment, the present invention is applied to a fuel injection device for a series-type internal combustion engine, but has a returnless fuel system in which supplied fuel is not returned. As shown in FIG. 9, the fuel passage 14 on the downstream side of the high-pressure fuel pump device 28D is connected to a delivery pipe 19 having a fuel injection valve 18, and this fuel passage 14 branches off on the upstream side of the delivery pipe 19 to perform high-pressure control. It is connected to the valve device 33. In the high-pressure fuel pump 28D, the supply passage 14a of the fuel passage 14 is connected to the high-pressure fuel pump 17, and a buffer vessel having a flow path cross-sectional area larger than that of the fuel passage 14 is provided downstream of the high-pressure fuel pump 17. The resonator 25 is connected to the buffer container 25. Since the high-pressure control valve device 33 is connected to the fuel passage 14 on the upstream side of the delivery pipe 19, the resonator 26 is moved from the high-pressure fuel pump 17 to the delivery pipe 19.
The natural frequency is set based on the natural frequency of the fuel passage 14 up to the downstream end of the fuel passage 14. Note that the resonator 26 may be provided in the fuel passage 14 to the upstream side of the high-pressure control valve 29, or another resonator may be provided at the downstream end of the delivery pipe 19 in order to enhance the resonance removing effect.

Therefore, the pressure wave generated when the high-pressure fuel pump 17 discharges high-pressure fuel is reflected at the downstream end of the delivery pipe 19 in the fuel passage 14 and is reflected by the high-pressure fuel pump 1.
7 returns to the outlet. At this time, the amplitude of the pressure pulsation can be suppressed low by the buffer container 25, the reflected wave is canceled by the natural frequency of the resonator 26, and the resonance in the fuel passage 14 can be suppressed.

In the above embodiment, the high-pressure fuel pump 17
A high-pressure control valve device 33 is provided between the pump and the delivery pipe 19. However, a high-pressure control valve device 33 is provided downstream of the delivery pipe 19, and the fuel returned from the high-pressure control valve 29 is supplied to a high-pressure fuel pump. A returnless fuel system that supplies the fuel downstream of the fuel tank 17 and does not completely return the fuel to the fuel tank 11 may be used.

FIG. 10 schematically shows a fuel supply system for an internal combustion engine in which a fuel system according to a fifth embodiment of the present invention is applied.
11 is a schematic diagram of a high-pressure fuel pump device, FIG. 12 is a schematic diagram of a section fuel passage composed of a high-pressure fuel pump, a buffer vessel, a resonator, and a delivery pipe. FIG. 13 is a dead volume with respect to a pressure wave generated in the section fuel passage. FIG. 14 is a graph showing a change in the frequency band according to the change in the frequency band according to the change in the length of the passage with respect to the pressure wave generated in the section fuel passage, and FIG. FIG. 16 is a graph showing a change in a frequency band corresponding to a change in the diameter of a passage with respect to a pressure wave generated in FIG. 16, FIG. 16 is a graph showing a noise level with respect to an engine speed, and FIG. Show. Note that members having the same functions as those described in the above-described first embodiment are denoted by the same reference numerals, and redundant description will be omitted.

The fuel supply device for an internal combustion engine according to the present embodiment
The present invention is applied to an in-line four-cylinder engine as an internal combustion engine. As shown in FIG.
The fuel passage 14 downstream of E is connected to a delivery pipe 19 having a fuel injection valve 18.
Is connected to the high-pressure control valve device 33E. In the high-pressure fuel pump 28E, the feed path 1 of the fuel passage 14
A high pressure fuel pump 17 is connected to a high pressure fuel pump 17. A downstream side of the high pressure fuel pump 17 is connected to a buffer container 25 having a flow path cross-sectional area larger than that of the fuel passage 14. 26 are connected. In the high-pressure control valve device 33E, the delivery pipe 1
9 and on the upstream side of the high-pressure control valve 29, the second
The resonator 27 is connected. The first resonator 26 has its natural frequency set based on the natural frequency of the fuel passage 14 from the high-pressure fuel pump 17 to the downstream end 19a of the delivery pipe 19, and the second resonator 27
The natural frequency is set based on the natural frequency of the fuel passage 14 from the high-pressure fuel pump 17 to the high-pressure control valve 29.

In the high-pressure fuel pump device 28E,
As shown in FIG. 11, a feed port 62 is formed in the housing 61 to communicate with a downstream end of a feed path 14 a of the fuel passage 14 from the low-pressure fuel pump 13.
The flow passage 63 communicating with the second 2 is communicated with the spring damper (pulsation damper) 24. On the other hand, in the high-pressure fuel pump 17, a sleeve 64 is provided on the housing 61.
Are fixed by a fixing ring 65 and an insulator 66, and a plunger 67 is movably supported by the sleeve 64. A tappet 68 is fixed to one end of the plunger 67 in the axial direction, and a compression spring 69 is attached to the other end.
9, the tappet 68 of the plunger 67 is pressed against the cam 70 which is directly linked to the operation of the engine. Also,
A bellows 71 for preventing fuel leakage is provided between the sleeve 64 and the plunger 67.

A suction passage 7 is provided in a cylinder chamber 72 formed by the reciprocating movement of the plunger 67 through the sleeve 64.
3 and one end of the discharge path 74 communicate with each other, and reed valves 75a and 75b are provided therebetween. The other end of the suction passage 73 communicates with the spring damper 24, and the other end of the discharge passage 74 communicates with the buffer container 25. The first resonator 26 includes a volume chamber 26a having a predetermined volume,
The orifice 26b communicates with the discharge passage 74 (fuel passage 14) and the volume chamber 26a. The first resonator 26 communicates with the discharge path 74 on the downstream side of the buffer container 25 through the orifice 26b.
The buffer container 25 communicates with a discharge port 77 through a communication passage 76, and the discharge port 77 communicates with a supply path 14a that communicates with the delivery pipe 19.

Therefore, the above-described high-pressure fuel pump device 28
In E, the plunger 67 is reciprocatingly driven in the axial direction by the rotation of the cam 70 in direct association with the operation of the engine.
Low pressure fuel is supplied to the supply port 62 through 4a. At this time, the plunger 67 is moved in one axial direction (FIG. 11).
To the left), the cylinder chamber 72 becomes negative pressure,
Low-pressure fuel in the flow passage 63 and the suction passage 73 is sucked into the cylinder chamber 71 via the reed valve 75a. And
When the plunger 67 moves to the other side in the axial direction (to the right in FIG. 11), the cylinder chamber 71 is pressurized to pressurize the internal fuel to a predetermined pressure, and the high-pressure fuel is supplied to the reed valve 7.
5b, flows into the discharge port 77 through the buffer vessel 25 and the communication path 76, and is connected to the delivery port 1 from the discharge port 77 to the delivery pipe 19.
4a.

The high-pressure fuel pump device 28E is configured as described above, and as shown in FIG.
The pressure wave generated when the high-pressure fuel is discharged by the nozzle 7 is reflected at the downstream end 19 a of the delivery pipe 19 in the fuel passage 14. This reflected wave is canceled by each natural frequency of the first resonator 26, and the resonance in the fuel passage 14 can be suppressed. Further, the reflected wave reflected by the high-pressure control valve 29 in the fuel passage 14 is canceled by the natural frequency of the second resonator 27, and the resonance in the fuel passage 14 can be suppressed.

Incidentally, the high-pressure fuel pump device 28E
Then, the high-pressure fuel pump 17 discharges the high-pressure fuel and cancels the reflected waves that are reflected and returned by the respective closed portions such as the delivery pipe 19 and the high-pressure control valve 29, and to suppress the amplitude of the pressure pulsation. 25 and the resonators 26 and 27 are provided, but vibrations corresponding to the discharge of the high-pressure fuel by the high-pressure fuel pump 17 occur in the fuel passage 14 between the high-pressure fuel pump 17 and the buffer container 25 (first resonator 26). I will. This is because the pressure wave from the high-pressure fuel pump 17 is reflected on the buffer container 25. For this reason, in the present embodiment, as shown in FIG. 12A, the natural frequency of the section fuel system defined between the high-pressure fuel pump 17 and the buffer container 25 (resonator 26) is set to at least 2 kHz.
That is all. In this case, the interval fuel system, connecting the dead volume D _V of the cylinder chamber 71 in the high pressure fuel pump 17, the volume chamber of the buffer vessel 25 (volume chamber 26a of the first resonator 26), the cylinder chamber 71 and the buffer vessel 25 It is composed of a fuel passage 14d.

Here, the high-pressure fuel pump 17 and the buffer container 2
A method for setting the natural frequency fn of the section fuel system defined between the fuel cell 5 and the resonator 26 will be specifically described.

As the vibration model of the section fuel system described above, there are a closed type shown in FIG. 12 (b) and an open type shown in FIG. 12 (c). High pressure fuel pump 17 to buffer container 2
When the respective impedances up to 5 (resonator 26) are Z _a and Z _b as shown in FIGS. 12B and 12C, the impedances Z _a and Z _b are determined using the acoustic impedance method. It can be obtained from the following equation (4).

[0113]

(Equation 6)

Based on the equation (4), first, FIG.
Given in a closed type shown in (b), the impedance Z _a of the exit of the volume V _a of the cylinder chamber 71 of the high-pressure fuel pump 17, the impedance Z _b at the inlet of the volume V _b of the buffer vessel 25, respectively below Can be sought.

[0115]

(Equation 7)

Then, when the equations (5) and (6) are substituted into the above-described equation (4) and arranged, the following equation (7) is obtained.

[0117]

(Equation 8)

Here, tan (k) is added to the obtained equation (7).
By adding an approximation of L _a ) ≒ kL _a , the following equation (8) is obtained.
Can be obtained, and the natural frequency fn of the section fuel system in the closed type can be calculated. Note that ωn is a natural angular velocity.

[0119]

(Equation 9)

[0120] On the other hand, considering the open type shown in FIG. 12 (c), the impedance Z _a of the exit of the volume V _a of the cylinder chamber 71 of the high-pressure fuel pump 17, at the inlet of the volume V _b of the buffer vessel 25 impedance Z _b, similarly to the above, can be obtained as follows.

[0121]

(Equation 10)

Then, by substituting the equations (9) and (10) into the above-described equation (4) and rearranging, the following equation (11) is obtained.
The relationship shown in FIG.

[0123]

[Equation 11]

Here, tan (kL) is added to the obtained equation (11).
_a ) When an approximation of ≒ kL _a is added, the following equation (12) is obtained.
Can be obtained, and the natural frequency fn of the section fuel system in the open type can be calculated.

[0125]

(Equation 12)

[0126] Here, in each formula thus determined, each parameter, i.e., a fuel passage connecting the volume V _a of the dead volume D _V, the volume V _b of the buffer vessel 25, the cylinder chamber 71 and the buffer vessel 25 change in the length L _a and cross-sectional area F _a of 14d is consider the impact on the natural frequency fn of the interval fuel system. Note that, in the above-described equation (8),
_{(F a L a + V a} + V b) / V b of the section, in fact V _b> F _a
Because it is L _a + V _a, close to this section is extremely 1, the equation (8) Equation (12) and can be considered to be similar, if both are there is a change in approximately the same natural frequency fn Conceivable.

Therefore, from equations (8) and (12),
The following can be seen. Natural frequency fn is increased in proportion to the square root of the volume V _a of the dead volume D _V. Fuel passage 1 connecting cylinder chamber 71 and buffer container 25
In proportion to the square root of the length L _a of 4d natural frequency fn is decreased. Fuel passage 1 connecting cylinder chamber 71 and buffer container 25
In proportion to the square root of 4d of the cross-sectional area F _a natural frequency fn
Increase. The effect of the change in the volume _Vb of the buffer container 25 on the natural frequency fn is extremely small.

Since there is a calculation error in the above-mentioned equations (8) and (12), the actual calculation is performed using the equations (7) and (1).
It is desirable to calculate directly from 1). That is, in Equations (8) and (12), since an approximation of tan (kL _a ) ≒ kL _a is used, a calculation error occurs here.

[0129] On the other hand, the volume V _a of the dead volume D _V,
The volume _Vb of the buffer container 25, the cylinder chamber 71 and the buffer container 2
Length of the fuel passage 14d connecting the 5 L _a and cross-sectional area F
Experimental results are shown on the influence of the change in _a (diameter d) on the vibration frequency generated in the section fuel system. 13, the length L _a of the fuel passage 14d 50 mm, and 6mm diameter d _a, when the rotation of the engine speed at 6000 rpm,
It is a graph showing the pressure amplitude with respect to frequency when changing the volume V _a of the dead volume D _V. From this graph, as shown in FIG. 13 (a), eaves volume V _a 41.8cc of dead volume, pressure amplitude of the frequency of 2~3kHz is large. FIG. 13B and FIG.
As shown in 3 (c), when the volume V _a of the dead volume 0.68 cc, decreases with 0.11 cc, the pressure amplitude of the frequency is greater larger than 2 kHz. On the other hand, as shown in FIG. 13 (d), when the volume V _a of the dead volume increases with 2.04Cc, pressure amplitude at 2kHz frequency is increased. That is, in this condition, smaller than 1.8cc volume V _a dead volume, it is desirable to about 1.2 cc.

[0130] Further, FIG. 14, 6 mm 1.8 cc, the diameter d _a of the fuel passage 14d of the volume V _a of the dead volume D _V
And then, when the rotation of the engine speed at 6000 rpm, which is a graph showing the pressure amplitude with respect to frequency when changing the length L _a of the fuel passage 14d. From this graph, as shown in FIG. 14 (a), the length L _a of the fuel passage 14d of 50mm eaves, the pressure amplitude of the frequency of 2~3kHz is large. Then, as shown in FIG.
When the length L _a of the fuel passage 14d is shortened to 25mm, 2kH
The pressure amplitude at frequencies greater than z is larger. On the other hand, as shown in FIG. 14 (c), when the length L _a of the fuel passage 14d for as long as 75 mm, the pressure amplitude at 2kHz frequency is increased. That is, in this condition, the length L _a of the fuel passage 14d shorter than 50 mm, it is desirable to 25mm or less.

[0131] Further, FIG. 15, 1.8 cc volume V _a dead volume D _V, the fuel passage 14d of the length L _a 50
and mm, when the rotation of the engine speed at 6000 rpm, which is a graph showing the pressure amplitude with respect to frequency when changing the diameter d _a of the fuel passage 14d. From this graph, as shown in FIG. 15 (a), the diameter d _a of the fuel passage 14d is 6mm eaves, the pressure amplitude of the frequency of 2~3kHz is large. Then, as shown in FIG. 15 (b) and FIG. 15 (c), the diameter d _a of the fuel passage 14d 8 mm, 12 mm
, The pressure amplitude at a frequency greater than 2 kHz increases. That is, in this condition, it is desirable that the diameter d _a of the fuel passage 14d to 6mm larger 8mm about possible mass production.

Here, the above-mentioned equation (7),
The natural frequency fn will be calculated using (12), or equations (8) and (12). For example, unlike a conventional, volume V _a = 1.8 cc of dead volume D _V, the fuel passage 1
4d length L _a = 64 mm, diameter d _{a of} fuel passage 14d =
6 mm, the cross-sectional area of the fuel passage ^{_{14d F a = πd 2 / 4mm}} 2, when the speed of sound a = 1000 m / s of the fuel, the equation (7),
The natural frequency fn = 2290 Hz, the natural frequency fn = 2670 Hz in the formula (8), the natural frequency fn = 2150 Hz in the formula (11), and the natural frequency fn = 2490 Hz in the formula (12).

[0133] On the other hand, as in this embodiment, the volume V _a = 1.2 cc of dead volume D _V, the fuel passage 14d length L _a = 64 mm, the diameter d _a = 8 mm of the fuel passage 14d, the fuel passage 14d sectional area ^{_{F a = πd 2 / 4mm 2}} , the fuel sound speed a
= 1000 m / s, the natural frequency fn = 3100 Hz in equation (7), and the natural frequency fn = 3100 Hz in equation (8).
4430 Hz, and in the equation (11), the natural frequency fn
= 2900 Hz, and in equation (12), the natural frequency fn = 4
070 Hz.

As described above, the volume _V of the dead volume DV
or decreasing the length L _a of _a and the fuel passage 14d, by increasing the diameter d _a of the fuel passage 14d, the interval fuel system defined between the high-pressure fuel pump 17 and the buffer vessel 25 (resonator 26) The natural frequency fn generated at
Can be greater than Hz. That is, the frequency band that is extremely sensitive to human hearing is around 2000 Hz. By removing the pressure amplitude in the frequency band around 2000 Hz, the occupant does not feel uncomfortable. The frequency band around 2000 Hz is, for example, a frequency band in which a pressure amplitude is generated due to the vibration of the cylinder head. By removing the pressure amplitude around 2000 Hz in the high-pressure fuel pump device 28E, resonance is suppressed. Is done.

FIG. 16 is a graph comparing noise levels of the conventional high-pressure fuel pump device and the high-pressure fuel pump device 28E of the present embodiment. Even if the overall level is as shown in FIG.
It can be seen that even in the region of 2.5 kHz, the noise level is reduced in the entire region of the engine speed. And FIG.
Numeral 7 compares the noise levels of the conventional high-pressure fuel pump device and the high-pressure fuel pump device 28E of this embodiment at each frequency. In contrast to the conventional high-pressure fuel pump device shown in FIG. 17A, the high-pressure fuel pump device 28E of this embodiment shown in FIG. 17B has a significantly reduced noise level in the range of 1 to 2.5 kHz. You can see that

Note that the fuel system of the present invention is not limited to the above-described embodiments.
Delivery pipe 21 as a closing part from the downstream side of
When the capacity to the downstream end 21a and the high-pressure control valve 29 is large, the pressure amplitude generated at the time of fuel discharge becomes small in all rotation regions of the internal combustion engine, so that the buffer container 25 may not be particularly provided. Also, the number of the resonators 26 and 27 provided in each part of the fuel passage 14 is not one or two, but is three depending on the configuration of the fuel system and the frequency of the pressure wave to be removed.
One or more may be provided. Further, the fuel system of the present invention is described, for example, in Japanese Patent Laid-Open No. 5-33741.
The invention can also be applied to a "accumulator-type fuel injection device" disclosed in Japanese Patent Application Laid-Open Publication No. H10-209,878.

[0137]

As described above in detail in the embodiment, according to the fuel system of the present invention, the drive of the internal combustion engine is provided in the fuel passage communicating the fuel injection valve and the fuel tank provided in the internal combustion engine. And a high-pressure fuel pump that supplies fuel to the fuel injection valve in accordance with the above, and a resonator is provided downstream of the high-pressure fuel pump so as to eliminate resonance of the fuel passage. When the fuel is discharged into the fuel passage, a pressure wave acts on the fuel passage along with the discharge of the high-pressure fuel, and the pressure wave is reflected in the fuel passage and tries to resonate. Thus, the resonance in the fuel passage can be eliminated, and as a result, a suitable amount and pressure of fuel can be stably injected from the fuel injection valve, and the engine can be stably burned.

Further, according to the fuel system of the second aspect,
A closing portion is provided on the downstream side of the fuel injection valve, and the natural frequency of the resonator is set based on the natural frequency of the fuel passage from the downstream side of the high-pressure fuel pump to the closing portion. The pressure wave generated by the discharge collides with the obstruction and is reflected, but the frequency of the reflected pressure wave and the natural frequency of the resonator cancel each other, effectively eliminating resonance in the fuel passage. can do.

Further, according to the fuel system of the third aspect of the present invention,
Since the resonator is provided at least in the vicinity of the downstream side of the high-pressure fuel pump or in the vicinity of the upstream side of the closing portion, the resonance of the fuel system can be efficiently removed at a place where the pressure amplitude that influences the pressure amplitude becomes large. .

Further, according to the fuel system of claim 4,
First and second delivery pipes for distributing the fuel discharged from the high-pressure fuel pump to the fuel injection valve are provided in the fuel passage.
And a fuel injection valve is provided in the second delivery pipe, and each delivery pipe is connected in series with a communication pipe having a smaller diameter than the fuel injection valve to form a fuel system having a closed portion on the downstream side of the second delivery pipe. A first resonator whose natural frequency is set based on the natural frequency of the fuel passage from the fuel pump to the closing portion; and a natural oscillator based on the natural frequency of the fuel passage from the high-pressure fuel pump to the downstream end of the first delivery pipe. Since the second resonator whose frequency is set is provided, a pressure wave is generated with the discharge of the high-pressure fuel by the high-pressure fuel pump, and the pressure wave reflected by the closing portion is canceled by the first resonator, and the first delivery is performed. The pressure wave reflected at the downstream end of the pipe is canceled by the second resonator, so that resonance in the fuel passage can be reliably removed.

According to the fuel system of the fifth aspect,
Since the resonator is formed integrally with the high-pressure fuel pump, it is possible to reduce the size of the device and improve the assembling workability.

Further, according to the fuel system of the invention of claim 6,
A shock absorber with a larger flow path cross-sectional area than the fuel passage is formed integrally with the high-pressure fuel pump at the discharge port of the high-pressure fuel pump, so that a pressure wave is generated in the fuel passage as the high-pressure fuel is discharged by the high-pressure fuel pump. Then, this pressure wave is reflected in the fuel passage and a number of pressure waves are shifted and polymerized.However, the pressure wave is formed by the shock absorber, and the pressure amplitude in all the rotation regions can be suppressed low. Can be reliably canceled by the resonator, and the resonance in the fuel passage can be eliminated.

Further, according to the fuel system of the invention of claim 7,
A low-pressure fuel pump is provided between the fuel tank and the high-pressure fuel pump, and a buffer is provided near the upstream side of the high-pressure fuel pump. Even if a pressure wave is generated in the passage, the pressure wave can be absorbed by the shock absorber.

Further, according to the fuel system of the eighth aspect,
A delivery pipe for distributing the fuel discharged from the high-pressure fuel pump to the fuel injection valve is provided in the fuel passage, and a resonator is provided on the upstream side of the delivery pipe. Since the natural frequency is set to at least 2 kHz, a frequency band lower than 2 kHz, which is extremely sensitive to human hearing, is removed, and quietness in the vehicle interior can be improved. Is easy, and reliable sound insulation measures can be taken.

Further, according to the fuel system of the ninth aspect,
Since the fuel system in the predetermined section includes the dead volume of the cylinder chamber in the high-pressure fuel pump, the volume chamber of the resonator, and the fuel passage connecting the cylinder chamber and the volume chamber, the frequency band that is extremely sensitive to human hearing is reliably removed. be able to.

Further, according to the fuel system of the tenth aspect, the volume of the dead volume of the high-pressure fuel pump is V _a ,
Volume of V _b of the volume chamber of the resonator, when the length L _a of the interval fuel passage connecting the cylinder chamber and the volume chamber, the cross-sectional area of the section fuel passage and F _a, the sound velocity of the fuel and a, the natural frequency f
n is calculated by a predetermined formula, and each parameter is set so that the calculated natural frequency fn is 2 kHz or more. Therefore, based on this formula, the dead volume volume V is set so that the natural frequency fn is 2 kHz or more. _a, the volume V _b of the resonator, the length of a section the fuel passage by setting the L _a and cross-sectional area F _a, it is possible to reduce the vibration of the highly sensitive frequency band lower than 2kHz to human hearing.

Further, according to the fuel pump of the present invention, the resonator for removing the resonance of the fuel passage is integrally provided downstream of the fuel pump provided in the fuel passage and supplying the fuel to the fuel injection valve. When the fuel pump discharges the fuel into the fuel passage, a pressure wave is generated in the fuel passage along with the discharge of the fuel by the fuel pump, and the pressure wave is reflected in the fuel passage and tends to resonate. The generated pressure wave is canceled by the resonator, so that resonance in the fuel passage can be eliminated. In addition, since the resonator is provided integrally with the fuel pump, the size of the apparatus can be reduced, and assembling workability can be improved.

According to the fuel pump of the twelfth aspect of the present invention, the shock absorber having a larger flow path cross-sectional area than the fuel passage is formed integrally with the discharge port. A pressure wave is generated in the passage, and the pressure wave is reflected in the fuel passage and a large number of pressure waves are shifted and polymerized.However, the waveform is shaped by the shock absorber, and the pressure amplitude in all rotation areas is kept low. Thus, the pressure wave is reliably canceled by the resonator, the resonance in the fuel passage can be eliminated, and the device can be downsized to improve the assembling workability.

[Brief description of the drawings]

FIG. 1 is a schematic view of a fuel system according to an embodiment of the present invention applied to a fuel supply device for an internal combustion engine.

FIG. 2 is a schematic diagram of a high-pressure fuel pump device.

FIG. 3 is a graph showing a fuel pressure amplitude with respect to an engine speed at a closed end of a fuel passage.

FIG. 4 is a graph showing a fuel pressure with respect to a crank angle when a first resonator is applied.

FIG. 5 is a graph showing a fuel pressure with respect to a crank angle when the first and second resonators are applied.

FIG. 6 is a schematic diagram illustrating a modified example of the high-pressure fuel pump device when the fuel system according to the first embodiment of the present invention is applied to a fuel supply device for an internal combustion engine.

FIG. 7 is a schematic diagram of a fuel system according to a second embodiment of the present invention applied to a fuel supply device for an internal combustion engine.

FIG. 8 is a schematic diagram of a fuel system according to a third embodiment of the present invention applied to a fuel supply device for an internal combustion engine.

FIG. 9 is a schematic view of a fuel system according to a fourth embodiment of the present invention applied to a fuel supply device for an internal combustion engine.

FIG. 10 is a schematic view of a fuel system according to a fifth embodiment of the present invention applied to a fuel supply device for an internal combustion engine.

FIG. 11 is a schematic view of a high-pressure fuel pump device.

FIG. 12 is a schematic view of a section fuel passage formed by a high-pressure fuel pump, a resonator, a buffer container, and a delivery pipe.

FIG. 13 is a graph showing a change in a frequency band according to a change in a dead volume with respect to a pressure wave generated in a section fuel passage.

FIG. 14 is a graph showing a change in a frequency band according to a change in length with respect to a pressure wave generated in a section fuel passage.

FIG. 15 is a graph showing a change in a frequency band according to a change in a diameter with respect to a pressure wave generated in a section fuel passage.

FIG. 16 is a graph showing a noise level with respect to an engine speed.

FIG. 17 is a graph showing a noise level with respect to a noise generation frequency.

FIG. 18 is a schematic diagram of a fuel supply device applied to a conventional direct injection internal combustion engine.

FIG. 19 is a graph showing a fuel pressure with respect to a crank angle in a conventional fuel supply device.

[Explanation of symbols]

REFERENCE SIGNS LIST 11 fuel tank 13 low-pressure fuel pump 14 fuel passage 14 a supply path 14 b return path 17 high-pressure fuel pump 18, 20 fuel injection valve 19, 21 delivery pipe 19 a downstream end 21 a downstream end (closed portion) 22 first bypass passage 24 spring damper (Buffer device) 25 buffer container (buffer device) 26 first resonator 27 second resonator 28, 28A, 28B, 28C, 28D, 28E high-pressure fuel pump device 29 high-pressure control valve (blocking portion) 30 second bypass passage 31 electromagnetic switching Valve 32,35 Low pressure control valve 33,33B, 33D 33E High pressure control valve device

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Fumiyasu Niwa 5-33-8 Shiba, Minato-ku, Tokyo Inside Mitsubishi Motors Corporation (72) Inventor Hiromitsu Ando 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation (72) Inventor Hiroshi Tanada 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation (72) Shigeo Yamamoto 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Inside Industrial Co., Ltd. (72) Inventor Akihito Miyamoto 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation (72) Insider Tetsu Kadota 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation Inside the company (72) Inventor Hideo Nakai Inside Mitsubishi Motors Corporation, 5-33-8 Shiba, Minato-ku, Tokyo

Claims (12)

[Claims] 1. A fuel passage provided in an internal combustion engine, which communicates with a fuel injection valve and a fuel tank, and a fuel passage provided in the fuel passage and operated in accordance with driving of the internal combustion engine to supply fuel to the fuel injection valve. A fuel system comprising: a high-pressure fuel pump to be supplied; and a resonator provided downstream of the high-pressure fuel pump so as to eliminate resonance of the fuel passage. 2. The fuel system according to claim 1, wherein a closing portion is provided on a downstream side of the fuel injection valve, and a natural frequency of the resonator is a fuel passage from a downstream side of the high-pressure fuel pump to the closing portion. A fuel system set based on the natural frequency of the fuel system. 3. The fuel system according to claim 2, wherein the resonator is located near a downstream side of the high-pressure fuel pump, or
A fuel system provided in at least one of the vicinity of the upstream side of the closing part. 4. The fuel system according to claim 1, wherein first and second delivery pipes for distributing fuel discharged from the high-pressure fuel pump to the fuel injection valve are provided in the fuel passage.
The first and second delivery pipes are each provided with the fuel injection valve, and the first and second delivery pipes are connected in series by a communication pipe having a smaller diameter than each of the delivery pipes. (2) a fuel system in which a closing portion is provided on the downstream side of the delivery pipe, wherein a first resonator whose natural frequency is set based on a natural frequency of a fuel passage from the high-pressure fuel pump to the closing portion; A fuel system comprising: a second resonator configured to set a natural frequency based on a natural frequency of a fuel passage from the high-pressure fuel pump to a downstream end of the first delivery pipe. 5. The fuel system according to claim 1, wherein said resonator is formed integrally with said high-pressure fuel pump. 6. The fuel system according to claim 5, wherein a shock absorber having a passage cross-sectional area larger than the fuel passage is formed integrally with the high-pressure fuel pump at a discharge port of the high-pressure fuel pump. Characteristic fuel system. 7. The fuel system according to claim 1, wherein a low-pressure fuel pump is provided between the fuel tank and the high-pressure fuel pump, and a shock absorber is provided near an upstream side of the high-pressure fuel pump. Characteristic fuel system. 8. The fuel system according to claim 1, wherein a delivery pipe for distributing the fuel discharged from the high-pressure fuel pump to the fuel injection valve is provided in the fuel passage, and the resonator is provided upstream of the delivery pipe. Wherein the natural frequency of the fuel system in a predetermined section defined between the high-pressure fuel pump and the resonator is at least 2
A fuel system characterized by being at least kHz. 9. The fuel system according to claim 8, wherein the predetermined section fuel system includes a dead volume of a cylinder chamber of the high-pressure fuel pump, a volume chamber of the resonator, and a fuel passage connecting the cylinder chamber and the volume chamber. A fuel system comprising: 10. The fuel system according to claim 9, wherein the volume of the dead volume of the high-pressure fuel pump is V _a , the volume of the volume chamber of the resonator is V _b , and the section fuel connecting the cylinder chamber and the volume chamber. Assuming that the length of the passage is L _a , the sectional area of the section fuel passage is F _a , and the sound velocity of the fuel is a, the natural frequency fn is calculated by the following equation, and the calculated natural frequency fn is 2 kHz or more. A fuel system wherein each of the parameters is set so that (Equation 1) 11. A fuel pump provided in a fuel passage for supplying fuel to a fuel injection valve, wherein a resonator for removing resonance of the fuel passage is integrally provided downstream of the fuel pump. Fuel pump. 12. The fuel pump according to claim 11, wherein a buffer device having a flow path cross-sectional area larger than the fuel passage is formed integrally with the discharge port.