JP3116746B2 - Fuel supply device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply system for an internal combustion engine, and more particularly to a fuel supply system for an internal combustion engine having high startability when the engine is stopped at a high temperature and restarted.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram of a conventional fuel supply device. A fuel supply system for an internal combustion engine generally uses a fuel return system as shown in FIG. Normally, an engine unit 10 is provided at a front portion of a vehicle and a tank 1 is provided at a rear portion, and fuel such as gasoline is stored in the tank 1. The fuel in the tank 1 is sucked and discharged by a fuel pump 2 having a check valve, and sent to a delivery pipe 4 via a supply passage 12 and a fuel filter 3 for filtering the fuel. The fuel sent to the delivery pipe 4 goes to an intake port (not shown) of each cylinder of the engine when the fuel injection valve 5 contained in the delivery pipe 4 is opened by a control device (not shown). Is injected. Four fuel injection valves 5 are provided for a four-cylinder engine, and six fuel injection valves are provided for a six-cylinder engine. When the pressure of the fuel supplied into the delivery pipe 4 becomes equal to or higher than the set pressure, the pressure regulator 6 opens the valve and returns the excess fuel to the tank 1 via the return passage 7. A reference pressure chamber in the pressure regulator 6 is connected to an intake pipe (not shown) of the engine, and a pressure obtained by adding and subtracting a spring force provided in the reference pressure chamber and a negative pressure of the intake pipe is used. When the pressure of the supplied fuel becomes higher than the set pressure of the spring, the valve is opened and the excess fuel is returned to the tank 1. When the negative pressure of the intake pipe is generated, the negative pressure is generated when the negative pressure of the intake pipe is generated. The pressure that pushes the diaphragm decreases by that amount, the pressure of the supplied fuel decreases by that negative pressure, and when a positive pressure occurs in the intake pipe, the pressure that pushes the diaphragm increases by that positive pressure, and the pressure of the supplied fuel increases by that positive pressure. The pressure is increased by the pressure, and the pressure difference between the supply fuel pressure and the intake pipe negative pressure is always kept constant. Therefore, the fuel injection amount from the fuel injection valve 5 for a predetermined time is kept substantially constant. The fuel pump 2 is provided with a suction filter 11 at an inlet thereof, and pumps up only filtered fuel.

In the above-described fuel supply apparatus, when the engine is started again after high-temperature soaking immediately after the engine is stopped, the temperature of the fuel rises due to the heat from the engine body, the fuel boils, and steam is generated. Since the reference pressure is a negative pressure, the fuel pressure is low, and the starting performance of the engine is poor. Therefore, there is another fuel supply device provided with a three-way solenoid valve that normally connects the reference pressure chamber in the pressure regulator 6 to the intake pipe and connects to the atmosphere during high-temperature soaking. This device switches the pressure for pressing the spring in the reference pressure chamber in the pressure regulator 6 to the intake pipe negative pressure or the atmospheric pressure by a three-way solenoid valve according to the fuel temperature or the engine temperature, and connects the reference pressure chamber to the atmosphere when the engine is started. By doing so, the pressure in the reference pressure chamber is increased to close the pressure regulator 6, and the pressure of the supplied fuel is increased. As a result, the steam is crushed and liquefied, and the decrease in the fuel injection amount due to the generation of steam is suppressed to improve the startability of the engine. It was made. However, this fuel supply device cannot increase the pressure of the supplied fuel until the steam is surely crushed, and the startability is poor when the engine temperature is high. Therefore, 63-1
The fuel supply device disclosed in Japanese Patent No. 74568 is a temperature sensor (not shown) for detecting the temperature of fuel between the delivery pipe 4 and the pressure regulator 6 in the device shown in FIG.
And a closing valve (not shown) for stopping the flow of fuel. When the temperature detected by the temperature sensor is equal to or higher than a predetermined temperature at the time of starting the engine, the solenoid valve of the closing valve is de-energized, the closing valve is closed, and The pump 2 is operated to increase the pressure of the supplied fuel to near the cutoff pressure of the fuel pump 2, thereby crushing the steam and improving the startability of the engine.

[0004]

However, the above-described prior art fuel supply apparatus disclosed in Japanese Utility Model Laid-Open Publication No. Sho 63-174568 has the following various problems. First, a temperature sensor, a closing valve, and a drive circuit for an electromagnetic valve for exciting the closing valve are required, and the apparatus becomes expensive. Second, when the closing valve moves from closed to open, the pressure of the supplied fuel fluctuates, and the fluctuation deteriorates drivability. Third, when the closing valve is closed, the load on the fuel pump increases, and the durability and reliability of the pump are impaired. Fourth, during a high temperature soak after the engine is stopped, the fuel pump is stopped, so that the fuel pressure cannot be increased. Although the pressure can be gradually increased after the restart, the startability of the engine is poor because the pressure is low immediately after the restart and the steam is not crushed. Fifth, regardless of the properties of the fuel to be used, the fuel pressure is increased to destroy the vapor, so that the non-volatile fuel becomes excessively fuel-injected, causing a rich misfire.

[0005] From the above, the present invention solves the first to fourth problems, without using a temperature sensor or a closing valve,
A main object of the present invention is to provide a fuel supply device for an internal combustion engine that does not generate steam in a delivery pipe when the engine is restarted after a high-temperature soak after the engine is stopped and has good engine startability.

[0006] The present invention also solves the fifth problem,
It is another object of the present invention to provide a fuel supply device for an internal combustion engine that crushes steam according to the properties of the fuel to be used and does not cause a rich misfire even with a non-volatile fuel.

[0007]

A fuel supply device for an internal combustion engine according to the present invention, which achieves the above-mentioned main object, comprises a fuel pump for pumping fuel stored in a tank for storing fuel,
A pressure regulator that returns a part of the fuel into the tank when the pressure of the fuel pumped by the fuel pump becomes equal to or higher than a predetermined pressure. A fuel supply device for an internal combustion engine that supplies fuel to a delivery pipe containing a fuel injection valve, sequentially opens a plurality of fuel injection valves intermittently, and injects fuel supplied to the delivery pipe toward an intake port of the engine. A check valve for preventing the fuel supplied to the delivery pipe from flowing back into the supply passage toward the tank with the pressure regulator (6);
It is characterized by being provided between the delivery pipe (4) .

According to another aspect of the present invention, there is provided a fuel supply device for an internal combustion engine, wherein a check valve is provided in a tank, and the check valve is supplied to the delivery pipe in the tank between the check valve and the delivery pipe. A fuel auxiliary storage chamber for storing the fuel.

[0009]

According to the fuel supply device for an internal combustion engine of the present invention, the check valve is provided between the pressure regulator and the delivery pipe, so that the fuel in the delivery pipe becomes high during the high temperature soak after the engine is stopped. To generate steam,
Since fuel is not returned from the delivery pipe of a predetermined volume to the fuel tank, the steam generated by the pressure increase due to expansion can be crushed and minimized. Since the fuel pressure is increased, fuel injection is improved, and the restartability of the engine after a high-temperature soak is improved. After the check valve is closed, the fuel in the delivery pipe evaporates and the fuel pressure increases as the fuel becomes more volatile depending on the fuel property. In other words, the more volatile fuel, the more steam is generated, the smaller the fuel injection amount is, and the more easily the fuel becomes lean.However, the amount of steam generated increases the fuel pressure in the delivery pipe, and fuel is injected under this increased pressure. The air-fuel ratio can be controlled well regardless of the degree of volatility, and the drivability is improved.

The fuel supply system for an internal combustion engine according to the present invention further comprises a check valve provided in the tank and a fuel auxiliary storage chamber provided in the tank between the check valve and the delivery pipe. Since the check valve and the auxiliary fuel storage chamber are provided at a location away from the engine, the temperature rise of the fuel due to the temperature rise of the engine is less than that of the case where these are installed near the engine, and therefore the generation of steam is also small, Since the fuel pressure in the delivery pipe is moderately attenuated, and the fuel injection amount fluctuates little due to the fuel pressure fluctuation, the drivability does not deteriorate. Further, since the fuel auxiliary storage chamber is provided in the tank, the fuel is kept at a low temperature, and the injection system is cooled quickly after the restart during the high-temperature soak.

[0011]

FIG. 1 is a basic configuration diagram of a fuel supply device according to a first embodiment of the present invention. In this figure, the same parts as those in FIG. 5 are indicated by the same reference numerals. The fuel supply device for an internal combustion engine shown in FIG. 1 is of a fuel returnless type. An engine unit 10 is provided at a front portion of a vehicle, and a tank 1 is provided at a rear portion. A fuel such as gasoline is stored in the tank 1. ing. A fuel pump 2 having a check valve, a fuel filter 3 and a pressure regulator 6 are provided in the tank 1. The fuel in the tank 1 is filtered by a suction filter 11 attached to an inlet of the fuel pump 2, and the fuel is filtered. It is sucked and discharged by the pump 2 and further filtered by the fuel filter 3. The pressure regulator 6 supplies only necessary fuel to the supply passage 12 out of the fuel sucked and discharged from the tank 1 by the fuel pump 2 and filtered by the fuel filter 3.
The fuel is supplied to the engine side via the controller and adjusted to return unnecessary fuel to the tank 1. The filtered fuel sent to the engine side via the supply passage 12 is sent to the delivery pipe 4 via the check valve 8. The fuel sent to the delivery pipe 4 goes to an intake port (not shown) of each cylinder of the engine when the fuel injection valve 5 contained in the delivery pipe 4 is opened by a control device (not shown). Is injected. Four fuel injection valves 5 are provided for a four-cylinder engine, and six fuel injection valves are provided for a six-cylinder engine.

Next, the operation of the valve of the pressure regulator 6 will be described. The reference pressure chamber in the pressure regulator 6 is connected to the air in the tank, and presses the diaphragm in the pressure regulator 6 with a pressure obtained by adding the spring force and the air pressure provided in the reference pressure chamber, and the fuel is charged into the engine unit 10. When the fuel pressure is lower than the pressure for pressing the diaphragm, the pressure regulator is closed. When the fuel pressure is higher than the pressure for pressing the diaphragm, the pressure regulator is opened to return the fuel to the tank. Next, the operation of the check valve 8 will be described. Pressure of fuel supplied to the supply passage 12 in front of the check valve 8 (hereinafter referred to as valve front fuel pressure)
Is greater than the pressure of the fuel charged from the check valve 8 to the delivery pipe 4 (hereinafter referred to as post-valve fuel pressure), the check valve 8 opens, and if the pre-valve fuel pressure is smaller than the post-valve fuel pressure, close. Since the fuel pump 2 stops with the stop of the engine, no fuel is supplied into the delivery pipe 4 and no fuel flows out of the fuel injection valve 5, so that the fuel in the delivery pipe 4 is trapped without being circulated. Can be Also,
Immediately after the engine is stopped, the fuel is heated from the high temperature engine section 10 to the fuel in the delivery pipe that is not circulated.
The temperature of the fuel rises. As a result, steam is generated in the fuel and expands to increase the pressure, the check valve 8 closes, the fuel in the delivery pipe further expands, the pressure increases, and the generated steam is crushed. Therefore, when the engine is restarted, the post-valve fuel pressure is higher than the pressure set by the pressure regulator, and the engine starts well. After the restart, when fuel is injected, the post-valve fuel pressure gradually attenuates to the pressure set by the pressure regulator.

After the check valve 8 is closed during a high-temperature soak, when volatile fuel is used, the amount of steam generated due to an increase in the engine temperature is increased as compared with non-volatile fuel, and the post-valve fuel pressure is increased. That is, the post-valve fuel pressure increases according to the fuel properties, and fuel is injected under that pressure, so that rich misfire does not occur and drivability is improved. This rich misfire occurs when the post-valve fuel pressure increases regardless of the fuel properties.
In the case of a non-volatile fuel, a large amount of fuel is injected because of a small amount of steam, and the fuel becomes over-rich.

FIG. 2 is a basic configuration diagram of a fuel supply device according to a second embodiment of the present invention. The fuel supply device of the second embodiment differs from the first embodiment shown in FIG. 1 only in that a check valve 8 and an auxiliary fuel storage chamber 9 are provided in the tank 1. With such a configuration, the fuel storage volume from the check valve 8 to the delivery pipe 4 is increased, on the one hand, the generation of steam due to the temperature rise of the engine around the delivery pipe 4 is reduced, and on the other hand, after the check valve 8 is closed, The increased post-valve fuel pressure is gradually attenuated by the fuel injection after the engine is restarted, so that the drivability does not deteriorate due to a rapid change in the fuel pressure. Further, since the fuel auxiliary storage chamber is provided in the tank, the fuel is kept at a low temperature, and the injection system can be cooled quickly after restarting during the high-temperature soak.

FIG. 3 is a diagram showing a change in fuel pressure after a high-temperature soak. In this figure, the horizontal axis represents time, and the vertical axis represents fuel pressure. In this figure, thin solid lines, thick solid lines, dashed lines, and broken lines show the time change of the fuel pressure of the fuel supply device, and in the case of the prior art shown in FIG. The time change of the fuel pressure when a high fuel is used, when a low volatile fuel is used in the first embodiment, and when a high volatile fuel is used in the second embodiment is shown.
It should be noted that the fuel pressure referred to in the drawing means the fuel pressure after the valve, that is, the fuel pressure in the delivery pipe. Hereinafter, each case will be briefly described.

In the case of the prior art shown in FIG. 5, as indicated by a thin solid line, the negative pressure P
The pressure of the fuel i increases from time t0, and increases at time t1.
, The pressure Ps becomes the set pressure Ps of the pressure regulator. During the high-temperature soak, the pressure Ps is maintained. When the engine is started at time t5, the pressure immediately drops to the negative pressure Pi of the intake pipe and becomes substantially constant at that pressure.

When a highly volatile fuel is used in the first embodiment, the engine stops at time t0 as indicated by the thick solid line.
Then, the pressure of the fuel, which is the set pressure Ps of the pressure regulator, increases from time t0, reaches the vapor pressure Pv1 at time t2, and maintains the pressure Pv1 during the high-temperature soak, and at time t5
When the engine is started, the pressure is gradually reduced to fall to the set pressure Ps of the pressure regulator at time t7, and becomes substantially constant at that pressure.

In the first embodiment, when a fuel having low volatility is used, as indicated by a dashed line, the engine is stopped at time t0.
Then, the pressure of the fuel, which is the set pressure Ps of the pressure regulator, increases from time t0, and at time t3, the vapor pressure Pv2
(Pv2 <Pv1), and the pressure Pv2 is maintained during the high-temperature soak. When the engine is started at time t5, the pressure is gradually reduced, and at time t6, falls to the pressure Ps of the pressure regulator, and becomes substantially constant at that pressure. .

When a highly volatile fuel is used in the second embodiment, as shown by the broken line, at time t0 when the engine is stopped, the pressure of the fuel, which is the set pressure Ps of the pressure regulator, increases from time t0, At time t4, the vapor pressure becomes Pv1, and during the high-temperature soak, the pressure Pv1 is maintained. When the engine is started at time t5, the pressure is gradually reduced, and at time t8, falls to the set pressure Ps of the pressure regulator. Become.

FIG. 4 is a schematic sectional view of a check valve used in the present invention. The left side of the check valve shown in the center of the figure is connected to the fuel pump side via the pressure regulator and the fuel filter, and the right side is connected to the delivery pipe side. The check valve is a valve that allows fuel on the fuel pump side to flow to the delivery pipe side but does not allow fuel on the delivery pipe side to flow to the fuel pump side. The safety valve shown on the right side of this drawing is a valve that suppresses a rise in fuel pressure from the delivery pipe side and prevents a check valve or pipe from being broken.

[0021]

As described above, according to the fuel supply system for an internal combustion engine of the present invention, the check valve is provided between the pressure regulator and the delivery pipe.
During the high temperature soak after the engine is stopped, the fuel in the delivery pipe becomes hot and expands and the pressure rises, the fuel becomes hot and the generated steam is crushed. Improves the restartability after high-temperature soak. Also, after the check valve closes, depending on the fuel properties,
As the fuel becomes more volatile, the fuel pressure rises, and fuel is injected under the pressure. Therefore, rich misfire does not occur and drivability is improved.

According to another aspect of the present invention, the check valve is provided in the tank, and the auxiliary fuel storage chamber is provided in the tank between the check valve and the delivery pipe. However, since these are provided at a location away from the engine, the temperature rise of the fuel due to the temperature rise of the engine is less than that when the engine is provided near the engine, so that the generation of steam is less, and the fuel in the delivery pipe is Since the pressure attenuates slowly and the fuel injection amount fluctuates little due to the fuel pressure fluctuation, drivability is improved. Further, since the fuel auxiliary storage chamber is provided in the tank, the fuel is kept at a low temperature, and the injection system can be cooled quickly after the restart during the high-temperature soak. In addition, fuel leakage at the fastening portion of the fuel pipe is also allowed because it is inside the tank.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of a fuel supply device according to a first embodiment of the present invention.

FIG. 2 is a basic configuration diagram of a fuel supply device according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a change in fuel pressure after a high-temperature soak;

FIG. 4 is a schematic sectional view of a check valve used in the present invention.

FIG. 5 is a configuration diagram of a conventional fuel supply device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Tank 2 ... Fuel pump 3 ... Fuel filter 4 ... Delivery pipe 5 ... Fuel injection valve 6 ... Pressure regulator 7 ... Return passage 8 ... Check valve 9 ... Fuel auxiliary storage room 10 ... Engine part

Claims (2)

(57) [Claims] 1. A fuel pump (2) for pumping fuel stored in a tank (1) for storing fuel, and when the pressure of the fuel pumped by the fuel pump (2) becomes higher than a predetermined pressure, Part of the fuel in the tank (1)
And a pressure regulator (6) for returning the fuel at the predetermined pressure to a plurality of fuel injection valves (5) through a supply passage (12).
And a plurality of fuel injection valves (5) are sequentially and intermittently opened to inject fuel supplied to the delivery pipe (4) toward an intake port of the engine. the fuel supplied to the delivery pipe (4) is, the check valve (8) which prevents the flowing back into the supply passage toward the to the tank (1) pressure regulator
A fuel supply device for an internal combustion engine, which is provided between (6) and the delivery pipe (4) . 2. The non-return valve (8) is provided in the tank (1) and in the tank (1) between the non-return valve (8) and the delivery pipe (4). The fuel supply device for an internal combustion engine according to claim 1, further comprising a fuel auxiliary storage chamber (9) for storing fuel supplied to the delivery pipe (4).