JP2003184697A - High pressure fuel supply system for internal combustion engine - Google Patents

Abstract

(57) Abstract: To provide a high-pressure fuel supply device for an internal combustion engine that can prevent occurrence of a large torque shock when returning from fuel cut during engine deceleration. The fuel injection valve includes a delivery pipe connected to each fuel injection valve, a high-pressure pump connected to the delivery pipe, and a leak passage connected to the delivery pipe.
The leak passage is used to reduce the fuel pressure in the delivery pipe to a predetermined fuel amount such that the fuel injection amount during the minimum valve opening time of the fuel injection valve does not cause a large torque shock at the time of fuel cut return during engine deceleration. The high-pressure pump is capable of pumping a larger amount of fuel into the delivery pipe than leaks from the delivery pipe through the leak passage during operation of the engine. Stop pumping fuel to fuel.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a high pressure fuel supply system for an internal combustion engine.

[0002]

2. Description of the Related Art In order to directly inject fuel into a cylinder of an internal combustion engine, it is necessary to supply high-pressure fuel to each fuel injection valve, and a high-pressure fuel supply device therefor is known.

A general high-pressure fuel supply system is equipped with a delivery pipe leading to each fuel injection valve. The delivery pipe is provided with a relief valve to prevent the fuel pressure in the delivery pipe from rising abnormally higher than the desired high fuel pressure which is the fuel injection pressure during engine operation. JP-A-11-
In Japanese Patent No. 351088, the valve opening pressure of the relief valve is set to be lower than the desired high fuel pressure instead of the abnormally high fuel pressure, and at the time of engine operation, the amount of fuel flowing out from the delivery pipe through the relief valve is set to be larger than the desired amount. It has been proposed to maintain a desired high fuel pressure in the delivery pipe by pumping it into the delivery pipe with a high pressure pump.

In this prior art, when the fuel pressure feeding into the delivery pipe by the high pressure pump is stopped when the engine is stopped, the fuel pressure in the delivery pipe immediately becomes the relief valve opening pressure lower than the desired high fuel pressure. Thereby,
Even when the engine is restarted immediately after it is stopped, the fuel pressure in the delivery pipe is not high and it is not necessary to open the fuel injection valve against this high pressure. Although the driving force at the time of opening the valve decreases, the fuel injection valve can be sufficiently opened by the decreased driving force.

[0005]

By the way, it is general to carry out fuel cut when the engine is decelerated. The fuel cut is to reduce the engine speed early, but if the engine speed is reduced too much, it will be difficult to restart the engine.Therefore, when the engine speed drops to the specified speed, the engine decelerates. The fuel injection is restarted and the fuel cut is resumed even if is continued. In the general and the above-mentioned conventional high-pressure fuel supply devices, the fuel pressure in the delivery pipe is maintained at the desired high fuel injection even during the fuel cut. As a result, a relatively large amount of fuel is injected at the time of fuel cut return even if the opening time of the fuel injection valve is minimized, and at the time of fuel cut return, a relatively large engine output is suddenly generated and a large torque shock is brought about.

Therefore, an object of the present invention is to provide a high pressure fuel supply system for an internal combustion engine which can prevent a large torque shock from occurring when the fuel cut is restored during deceleration of the engine.

[0007]

According to a first aspect of the present invention, there is provided a high pressure fuel supply system for an internal combustion engine, a delivery pipe communicating with each fuel injection valve, a high pressure pump connected to the delivery pipe, and the delivery pipe. A leak passage connected to a pipe, wherein the leak passage controls the fuel pressure in the delivery pipe such that the fuel injection amount in the minimum valve opening time of the fuel injection valve at the time of fuel cut recovery during engine deceleration. It is possible to reduce to a predetermined fuel pressure such that the fuel injection amount does not generate a large torque shock, and the high-pressure pump has an amount that is greater than that which leaks from the delivery pipe through the leak passage during engine operation. The fuel can be pumped into the delivery pipe, and the fuel is pumped to the delivery pipe during the fuel cut. Characterized in that it.

A high pressure fuel supply system for an internal combustion engine according to a second aspect of the present invention is the high pressure fuel supply system for an internal combustion engine according to the first aspect, wherein the leak passage includes the high pressure pump and the delivery pipe. Is shared with a high-pressure passage that communicates with the fuel cell, and leaks fuel from the delivery pipe through the high-pressure pump.

A high pressure fuel supply system for an internal combustion engine according to a third aspect of the present invention is the high pressure fuel supply system for an internal combustion engine according to the second aspect, wherein the high pressure passage extends from the high pressure pump to the delivery pipe. A check valve that allows only the fuel flow to the check valve is disposed, and the valve body of the check valve itself or the seat portion of the valve body always communicates the upstream side and the downstream side of the check valve. Is formed, whereby the high-pressure passage also functions as the leak passage.

A high pressure fuel supply system for an internal combustion engine according to a fourth aspect of the present invention is the high pressure fuel supply system for an internal combustion engine according to the first aspect, further comprising a low pressure pump for supplying fuel to the high pressure pump. The leak passage leaks the fuel in the delivery pipe to a low pressure passage that connects the high pressure pump and the low pressure pump.

According to a fifth aspect of the present invention, there is provided a high-pressure fuel supply system for an internal combustion engine according to the first aspect, wherein the delivery pipe has a fuel pressure in the delivery pipe. Is provided with a relief passage for preventing an abnormal rise, and the valve body itself of the relief valve or the seat portion of the valve body arranged in the relief passage has an upstream side and a downstream side of the relief valve. It is characterized in that a communication passage that is always in communication is formed so that the relief passage also functions as the leak passage.

A high pressure fuel supply system for an internal combustion engine according to a sixth aspect of the present invention is the high pressure fuel supply system for an internal combustion engine according to the first aspect, wherein the leak passage is responsive to a decrease in fuel temperature. A pressure control valve that reduces the valve opening pressure is provided to prevent the fuel pressure in the delivery pipe from becoming saturated vapor pressure at each fuel temperature even if the fuel temperature in the delivery pipe decreases while the engine is stopped. It is characterized by doing.

[0013]

1 is a schematic view showing an embodiment of a high-pressure fuel supply device according to the present invention. In the figure, 1
Is a fuel injection valve, for example, for directly injecting fuel into each cylinder of the internal combustion engine. Reference numeral 2 is a delivery pipe for supplying high-pressure fuel to each fuel injection valve 1. Reference numeral 3 denotes a fuel tank, and a low pressure pump 4 is arranged in the fuel tank 3. The low-pressure pump 4 is an electric pump driven by a battery, for example, 0.3M
It has a rated discharge pressure of Pa. The low-pressure pump 4 is operated at the same time as the starter switch ON signal. A filter 6 is provided on the suction side of the low-pressure pump 4 to remove foreign matter when sucking fuel from the fuel tank 3.

Reference numeral 7 is a high-pressure pump for maintaining the fuel pressure in the delivery pipe 2 near the target high fuel pressure. This high-pressure pump 7 includes a cam 7 that works with a crankshaft.
It is an engine drive type driven by e. High pressure pump 7
Discharges the fuel sucked into the cylinder 7d through the suction port 7b from the discharge port 7c, and has a plunger 7a that slides in the cylinder 7d for this purpose.
The suction port 7b is connected to the discharge side of the low pressure pump 4 via a low pressure pipe 8, and the discharge port 7c is connected to the delivery pipe 2 via a high pressure pipe 11. A filter 10 for removing foreign matter in the fuel is also arranged in the low-pressure pipe 8.

The plunger 7a has a spring 7 as a suction stroke.
It is moved by f so as to enlarge the space inside the cylinder 7d, and is moved so as to reduce the space inside the cylinder 7d by the cam 7e as the discharge stroke. 16 is a suction port 7b
Is a valve element for opening and closing, and is always biased in the valve opening direction by a spring 16b. 16a is a valve body 16 spring 1
6b is a solenoid for urging in the valve closing direction against 6b. The solenoid 16a is de-energized in the suction stroke of the high-pressure pump 7, and the valve body 16 is opened by the spring 16b. Therefore, the low-pressure pipe 8 is opened via the suction port 7b.
Fuel is sucked into the cylinder 7d from. Since this fuel has been boosted to 0.3 MPa by the low-pressure pump 4 as described above, fuel vapor due to negative pressure is not generated in the low-pressure pipe 8 during the intake stroke.

On the other hand, in the discharge stroke of the high pressure pump 7,
The solenoid 16a is energized at a desired time, and the valve body 1
6 is closed. The fuel in the cylinder 7d is returned to the low pressure pump 4 via the low pressure pipe 8 without being pumped into the high pressure delivery pipe 2 before the valve body 16 is closed, but after the valve body 16 is closed. It is pumped into the delivery pipe 2. In this high-pressure fuel supply device, the discharge stroke of the high-pressure pump 7 is provided for each fuel injection of the two cylinders, and the valve closing timing of the valve element 16 is controlled,
By adjusting the amount of fuel used for fuel injection into these two cylinders and pumping the fuel into the delivery pipe 2, the inside of the delivery pipe 2 can be maintained near the target high fuel pressure.

A check valve 12 that opens with a slight pressure difference is arranged in the high-pressure pipe 11 in order to prevent the fuel from flowing backward due to the pressure pulsation generated by the high-pressure pump 7. Reference numeral 21 is a pressure sensor for monitoring the fuel pressure in the delivery pipe 2.

As described above, since unnecessary fuel of all the fuel discharged by the plunger 7a is returned to the fuel tank 3 through the low-pressure pipe 8, at this time, high-pressure fuel is stored in the low-pressure pump 4. Will flow backwards. In order to prevent this backflow, the low-pressure pipe 8 may be connected to the fuel tank 3 via a safety valve that opens at a pressure slightly exceeding the rated discharge pressure of the low-pressure pump 4.

Since the high-pressure pump 7 operates well during engine operation, the intended fuel discharge is possible and the inside of the delivery pipe 2 can be maintained near the target high fuel pressure.
Good fuel injection is possible via the fuel injection valve 1. The target high fuel pressure is, for example, 1 regardless of the fuel injection amount.
It may be fixed to the first target high fuel pressure such as 2 MPa, but when the fuel injection amount is small such as when the engine load is low,
Since the valve opening time of the fuel injection valve becomes very short and it becomes difficult to control the accurate fuel injection amount, even if the second target high fuel pressure such as 8 MPa is provided for this time, for example. good. Of course, three or more target high fuel pressures may be set according to the engine load or the engine operating state.

Reference numeral 22 is a relief pipe that connects the delivery pipe 2 and the fuel tank 3, and a relief valve 23 that opens at a pressure slightly higher than the first target high fuel pressure is arranged. Is prevented from exceeding the first target high fuel pressure and rising abnormally due to some factor.

During engine deceleration, fuel injection from each fuel injection valve 1 is stopped, that is, fuel cut is performed, for the purpose of reducing fuel consumption and early deceleration. As a result, the engine speed decreases relatively rapidly. If the engine deceleration time is relatively long and the engine speed is still decelerating even when the engine speed drops to a predetermined speed, for example, the idling speed, fuel injection is performed to ensure a reliable restart of operation. Is restarted and the fuel cut is restored.

In a general high-pressure fuel supply device, even if the fuel pressure feeding to the delivery pipe by the high-pressure pump is stopped at the same time as the fuel cut is performed, the fuel pressure in the delivery pipe at the time of returning from the fuel cut is Since there is no fuel consumption in the delivery pipe due to the cut, it is the value immediately before the engine deceleration, that is, the fuel pressure during normal operation. Immediately before deceleration of the engine, high load operation is often performed, and this fuel pressure is close to the first target high fuel pressure on the high side even when there are two target high fuel pressures as described above. Is often set.

When the fuel pressure in the delivery pipe is high when the fuel cut is restored, a comparatively large amount of fuel is supplied to the cylinder even if the fuel injection valve is opened for the minimum opening time. High engine output will occur. As a result, a great torque shock is brought about when the fuel cut is restored during deceleration of the engine, and the driver feels uncomfortable.

Of course, when the driver does not return to the fuel cut during deceleration of the engine as described above, but when the driver intentionally finishes the deceleration of the engine and depresses the accelerator pedal to accelerate the engine to return from the fuel cut, Suddenly, a relatively large engine output is generated and a similar torque shock is brought about, but this is the intention of the driver and the driver does not feel uncomfortable.

The purpose of this embodiment is to prevent the occurrence of torque shock when the fuel cut is restored during deceleration of the engine. Therefore, the check valve 12 arranged in the high pressure pipe 11 has a structure as shown in FIG. A general check valve has a spherical valve body and a spring that biases the valve body against the seat portion. The check valve 12 arranged in the high-pressure pipe 11 of the present embodiment has a valve body 12
The notch A is provided in a part of the annular seat portion 12b which abuts against. As a result, the valve body 12a becomes the spring 1
Even if the seat portion 12b is urged by the 2c, the upstream side and the downstream side of the check valve 12 are always communicated by the notch A. That is, the notch A constitutes a communication passage that always connects the upstream side and the downstream side of the check valve 12 with each other.

In the present embodiment, the fuel pressure feeding of the high pressure pump 7 is stopped during the fuel cut, that is, the solenoid 16a in the discharge stroke of the high pressure pump 7.
Is not excited, and the valve body 16 is kept open. Thereby, during the fuel cut, the fuel in the delivery pipe 2 leaks through the notch A in the seat portion 12b of the check valve 12 and is returned to the fuel tank 3 through the high pressure pump 7.

Thus, when the engine speed is reduced to a predetermined speed during engine deceleration and the fuel cut is restored, the fuel pressure in the delivery pipe 2 is the fuel pressure at the fuel cut start time which is the first target high fuel. Even if it is near the pressure, it is lower than the second target high fuel pressure due to the fuel leak during the fuel cut. As a result, the fuel injection amount during the minimum valve opening time of the fuel injection valve at the time of fuel cut recovery can be made smaller than the fuel injection amount at the time of idling, for example, and the generated engine output is very small and a large torque shock is generated. Does not bring

In the present embodiment, the size of the notch in the seal portion 12b of the check valve 12 is selected so that, for example, a fuel leak that reduces the fuel pressure in the delivery pipe by about 1 MPa per second occurs. This fuel leak amount is 1/10 or less of the fuel pressure feed amount in the cranking of a normal high pressure pump. As a result, even during normal operation, this fuel leak occurs, but the fuel leak amount is offset by slightly increasing the amount of fuel pumped by the high-pressure pump, and the first target high fuel pressure in the delivery pipe 2 is offset. Alternatively, the second target high fuel pressure can be sufficiently maintained.

In the present embodiment, the leak passage is made common with the high pressure passage which connects the high pressure pump 7 and the delivery pipe 2 by the structure of the above-mentioned check valve, and the fuel leaks from the delivery pipe through the high pressure pump. Has become. As a result, in the discharge stroke of the high-pressure pump 7 during normal operation, the fuel pressure in the cylinder 7d of the high-pressure pump 7 is higher than the fuel pressure in the delivery pipe 2, so fuel leakage from the delivery pipe 2 does not occur. Of course, the leak passage may directly connect the delivery pipe 2 and the fuel tank, but the leak passage of the present embodiment can reduce the fuel leak amount during engine operation as described above. Therefore, it is possible to reduce the load of the high-pressure pump 7 by reducing the amount of the fuel to be pumped by the high-pressure pump 7 accordingly.

Further, the check valve 12 is provided with a communication passage so that the high pressure passage and the leak passage are common to each other.
The fuel flows in the communication passage in the opposite directions when the high-pressure pump 7 pumps the fuel and when the fuel leaks, so that the notch A forming the communication passage is not clogged with foreign matter.

FIG. 3 shows another structure of the check valve for making the leak passage common to the high pressure passage 11 which communicates the high pressure pump 7 and the delivery pipe 2, and this check valve 12 'is shown. A groove B as a communication passage that connects the upstream side and the downstream side of the check valve 12 'is formed in the valve body 12a'. Of course, even with such a configuration, the same effect as described above can be obtained.

In the present embodiment, the check valve 12 disposed in the high pressure passage 11 is provided with a communication passage so that the leak passage is formed into the high pressure passage 1.
However, if a similar communication passage is formed not in the check valve 12 but in the relief valve 23, the leak passage can also be made common with the relief passage 22.

FIG. 4 is a schematic view showing another embodiment of the high-pressure fuel supply device according to the present invention. Only the differences from the above embodiment will be described below. In the present embodiment, the check valve 12 arranged in the high pressure pipe 11 is a general one in which a communication passage is not formed in the valve body and the seat portion. The fuel leak passage 24 is formed so as to connect the high pressure pipe 11 and the low pressure pipe 8 to each other. Of course, the delivery pipe 2 and the low pressure pipe 8 may be communicated with each other. The leak passage 24 has a narrowed section 2 with a narrow passage cross section.
5 is formed, and if the fuel pressure feeding by the high-pressure pump is stopped during the fuel cut, the fuel pressure in the delivery pipe 2 due to the fuel leak through the leak passage 24 is the same as the leak passage in the embodiment of FIG. Is
For example, the pressure is reduced by 1 MPa per second.

With such a configuration, also in the high-pressure fuel supply system of this embodiment, as in the embodiment of FIG. 1, when the fuel cut is restored during deceleration of the engine, the leak passage 2
The fuel pressure in the delivery pipe 2 can be made sufficiently low by the fuel leak through 4, so that a small amount of fuel can be injected by the fuel injection valve and a large torque shock does not occur.

By the way, when the engine is started, the fuel pressure in the delivery pipe 2, which has been reduced to almost atmospheric pressure, must be immediately increased. Since the low-pressure pump 4 is electrically driven, it is possible to pump a relatively large amount of fuel from the beginning of cranking. With cranking engine speed, only a small amount of fuel can be pumped. In the present embodiment, since the low-pressure pipe and the high-pressure pipe are connected by the leak passage 24, fuel is pumped into the delivery pipe 2 by the high-pressure pump during the discharge stroke of the high-pressure pump 7 at the time of engine start. During the suction stroke of the high pressure pump 7, fuel is pumped into the delivery pipe 2 by the low pressure pump 4 through the leak passage 24. Thereby, when the fuel pressure in the delivery pipe 2 is set to the rated discharge pressure of the low-pressure pump 4 or a desired pressure higher than the rated pressure, the time until the start of fuel injection can be shortened.

In the present embodiment, instead of the throttle portion 25, the check valve of FIG. 2 or 3 may be arranged in the leak passage 24. As a result, during the intake stroke of the high-pressure pump 7 when the engine is started, the discharge fuel of the low-pressure pump 4 opens the check valve and is easily pumped into the delivery pipe 2, and further until the start of fuel injection. The time can be shortened. Further, the fuel flows in the communication passage of the check valve 12 arranged in the leak passage 24 in the opposite directions at the time of engine start and at the time of fuel leakage, and foreign matter is clogged in the notches forming the communication passage. There is nothing left to leave.

FIG. 5 is a sectional view of a leak passage showing a modification of the embodiment shown in FIG. The leak passage 24 'of the present modification is provided with a throttle portion 25 similar to that of the embodiment of FIG. 4, and a pressure adjusting valve 26 is disposed on the low pressure pipe side of the throttle portion 25'. The pressure adjusting valve 26 is a valve body 26.
a and a spring 26c for urging the valve body 26a toward the seat portion 26b. If the pressure difference between the high pressure pipe and the low pressure pipe is larger than the urging force of the spring 26c, the valve body 26a is opened and Allow fuel flow to low pressure piping.

The spring 26c changes the urging force acting on the valve body 26a depending on the temperature of the bimetal or the shape memory alloy. The lower the temperature, the smaller the urging force. With this configuration as well, when the fuel cut is restored during deceleration of the engine, the pressure adjusting valve 26 opens due to the relatively large pressure difference between the high-pressure pipe and the low-pressure pipe, which is similar to the embodiment of FIG. In addition, the fuel pressure in the delivery pipe 2 can be sufficiently lowered by the fuel leak through the leak passage 24 ', and a small amount of fuel can be injected by the fuel injection valve, which causes a large torque shock. Absent.

By the way, the fuel pressure in the delivery pipe 2 is stopped by the high-pressure pump 7 even when the engine is stopped, so that the fuel pressure in the delivery pipe 2 is gradually increased by the fuel leak through the leak passage 24 '. The pressure drops. Further, the fuel temperature in the delivery pipe 2 is lower than the temperature of the delivery pipe 2 due to the relatively low temperature fuel supplied from the fuel tank during engine operation. Since such fuel supply is lost, the temperature becomes equal to the temperature of the delivery pipe 2, and then gradually decreases with the temperature of the delivery pipe 2.

When the fuel temperature rises immediately after the engine is stopped, the urging force of the spring 26c increases, and when the fuel pressure in the delivery pipe 2 drops to a certain pressure, the pressure regulating valve 26 is closed and the leak passage 24 '. No fuel leaks through. Then, as the fuel temperature decreases with the temperature of the delivery pipe 2, the spring 2
Since the urging force of 6c gradually decreases, the leak passage 2
It is possible to keep the fuel pressure in the delivery pipe 2 higher as the fuel temperature in the delivery pipe 2 is higher by repeatedly generating and stopping the fuel leak through 4 '.

The fuel has a saturated vapor pressure which becomes higher as the temperature rises. The pressure adjustment valve 26 of the present embodiment is set so that the valve opening pressure with respect to the fuel temperature is higher than the saturated vapor pressure with respect to the fuel temperature. This prevents the fuel pressure in the delivery pipe 2 from becoming saturated vapor pressure at each fuel temperature after the engine is stopped, and the fuel vapor is not generated in the delivery pipe 2.

Since the internal combustion engine to which the present high-pressure fuel supply device is attached is of the cylinder injection type, the homogeneous combustion that forms a homogeneous mixture in the cylinder by the fuel injection in the intake stroke and the fuel injection in the compression stroke are performed. It is possible to carry out stratified combustion in which a combustible mixture is formed only in the vicinity of the spark plug. Generally, homogeneous combustion is performed on the high load side, and stratified combustion is performed on the low load side. Since it is difficult to make the fuel pressure in the delivery pipe 2 that has decreased to near atmospheric pressure to the target high fuel pressure at the time of engine start, homogeneous combustion that enables fuel injection in the intake stroke with low in-cylinder pressure is performed. Be implemented.

However, even in the intake stroke injection,
The higher the injection pressure, the greater the frictional force with the intake air, and the vaporization of the injected fuel is promoted. Therefore, it is preferable to inject the fuel at the highest possible pressure. When the engine is started, the low-pressure pump 4 alone or the low-pressure pump 4 and the high-pressure pump 7 pressurize the inside of the delivery pipe 2 to a desired pressure to start the fuel injection. If it is formed, first, this space must be compressed, and it takes a long time to pressurize to the desired pressure, which deteriorates the engine startability. According to the present embodiment, since fuel vapor is not generated in the delivery pipe 2 while the engine is stopped, such deterioration of engine startability can be prevented.

In the case where the pressure regulating valve 26 of the present embodiment shares the leak passage with the relief passage 22 as described above, even if the pressure regulating valve 26 is arranged in the relief passage 22 on the downstream side of the relief valve 23, the engine is stopped. It is possible to prevent the generation of fuel vapor in the delivery pipe 2 inside.

The high-pressure pump 7 in the high-pressure fuel supply apparatus described above is designed to meter and pump the required amount of fuel so as to maintain the desired high fuel pressure in the delivery pipe 2 during normal operation. This is not a limitation of the present invention. For example, if the relief pipe 22 is connected to the delivery pipe 2 and the relief pressure of the relief pipe 22 is set to a desired high fuel pressure in the delivery pipe 2, the spill mechanism as a high pressure pump is not always provided and the entire amount is pumped. Things can also be used. In this case, in order to stop the fuel pressure feeding to the delivery pipe by the high pressure pump during the fuel cut, the operation of the high pressure pump may be stopped using a clutch or the like. Of course, even in the metering type high pressure pump, if the engine driving force is transmitted through the clutch, the clutch may be disengaged during fuel cut to stop the fuel pressure feeding. Also,
If the high-pressure pump is an electric drive type, the power supply may be stopped and the fuel pressure feeding may be stopped.

[0046]

According to the high-pressure fuel supply system for an internal combustion engine of the present invention, it is provided with a leak passage connected to the delivery pipe, and the leak passage has fuel in the delivery pipe when the fuel cut is restored during deceleration of the engine. It is possible to reduce the pressure to a predetermined fuel pressure. During engine operation, the high-pressure pump can maintain a desired high fuel pressure in the delivery pipe in order to pump into the delivery pipe an amount of fuel more than the amount of fuel leaking from the delivery pipe through the leak passage. . Further, since the high-pressure pump stops the fuel pressure feeding to the delivery pipe during the fuel cut, the fuel pressure in the delivery pipe decreases to a predetermined pressure due to the leak passage when the fuel cut returns during the engine deceleration. The fuel injection amount during the minimum valve opening time is the fuel injection amount that does not generate a large torque shock. As a result, it is possible to prevent a large torque shock from occurring when the fuel cut is restored during deceleration of the engine.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of a high-pressure fuel supply device according to the present invention.

FIG. 2 is a cross-sectional view showing the structure of a check valve for high pressure piping in the high pressure fuel supply system of FIG.

3 is a cross-sectional view showing another structure of the check valve of the high-pressure pipe in the high-pressure fuel supply system of FIG.

FIG. 4 is a schematic view showing another embodiment of the high-pressure fuel supply device according to the present invention.

5 is a cross-sectional view of a leak passage showing a modified example of the embodiment of FIG.

[Explanation of symbols]

1 ... Fuel injection valve 2… Delivery pipe 4 ... Low pressure pump 7 ... High-pressure pump 8 ... Low pressure piping 11 ... High-pressure piping 12 ... Check valve 22 ... Relief passage 23 ... Relief valve 24, 24 '... Leak passage 25 ... diaphragm part 26 ... Pressure regulating valve

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02M 47/00 F02M 47/00 Z 59/46 59/46 Y

Claims (6)

[Claims] 1. A delivery pipe communicating with each fuel injection valve, a high-pressure pump connected to the delivery pipe, and a leak passage connected to the delivery pipe.
In the leak passage, the fuel pressure in the delivery pipe is set so that the fuel injection amount during the minimum valve opening time of the fuel injection valve at the time of fuel cut recovery during engine deceleration does not cause a large torque shock. It is possible to reduce the fuel pressure to a predetermined predetermined value, and the high-pressure pump is capable of pumping into the delivery pipe an amount of fuel more than the amount of fuel leaking from the delivery pipe through the leak passage during engine operation. A high-pressure fuel supply system for an internal combustion engine, characterized in that the fuel pressure feed to the delivery pipe is stopped during fuel cut. 2. The leak passage is common to a high pressure passage that connects the high pressure pump and the delivery pipe,
The high pressure fuel supply apparatus for an internal combustion engine according to claim 1, wherein fuel is leaked from the delivery pipe through the high pressure pump. 3. A check valve that allows only a fuel flow from the high pressure pump to the delivery pipe is arranged in the high pressure passage, and the check valve valve body itself or the seat portion of the valve body is provided. The high pressure fuel for an internal combustion engine according to claim 2, wherein a communication passage is formed which always connects the upstream side and the downstream side of the check valve, and thereby the high pressure passage also functions as the leak passage. Supply device. 4. A low-pressure pump for supplying fuel to the high-pressure pump is provided, wherein the leak passage leaks fuel in the delivery pipe to a low-pressure passage that connects the high-pressure pump and the low-pressure pump. The high-pressure fuel supply system for an internal combustion engine according to claim 1. 5. The delivery pipe is provided with a relief passage for preventing the fuel pressure in the delivery pipe from rising abnormally, and the relief valve valve element itself or the relief valve disposed in the relief passage is provided. 2. A communication passage that always communicates the upstream side and the downstream side of the relief valve is formed in the seat portion of the valve body, whereby the relief passage also functions as the leak passage.
A high-pressure fuel supply system for an internal combustion engine as set forth in. 6. The delivery pipe is provided in the leak passage with a valve opening pressure that decreases in accordance with a decrease in fuel temperature, and the delivery pipe is maintained even if the fuel temperature in the delivery pipe decreases while the engine is stopped. 2. The high pressure fuel supply system for an internal combustion engine according to claim 1, wherein the internal fuel pressure is prevented from becoming a saturated vapor pressure at each fuel temperature.