JP2001165013A - Fuel supplying device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reconcile prevention of vapor lock of a high pressure fuel pump 5 and reduction of vapor generating amount in a fuel tank 1. SOLUTION: Fuel in the fuel tank 1 is forcibly supplied by a low pressure fuel pump 2, and excess fuel is returned by a low pressure regulator 3. Fuel from the low pressure fuel pump 2 is pressurized in a high level by a high pressure fuel pump 5, and is supplied to a fuel injection valve 6. The excess fuel is returned to an intake side of the high pressure fuel pump 5 by a high pressure regulator 7, and then, it is returned to the fuel tank 1 through a return passage 9. A return control valve 10 which is opened at the time of a high temperature by a signal of a fuel temperature sensor 13 is disposed in the return passage 9, and first and second orifices 11, 12 are disposed. The low pressure regulator 3 is constituted so as to set opening valve pressure by the sum of built-in spring force and pressure of a valve opening pressure varying port 3a, and pressure between the orifices 11, 12 is led to the port 3a so as to increase fuel pressure in a low pressure system when the return control valve 10 is opened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuel supply device for an internal combustion engine for supplying high-pressure fuel.

[0002]

2. Description of the Related Art As a fuel supply device for a conventional internal combustion engine (particularly, a direct injection spark ignition type internal combustion engine), Japanese Patent Application Laid-Open No. 10-3317 is known.
Japanese Patent Publication No. 38 discloses such a device.

This includes a low-pressure fuel pump that sucks and discharges fuel in a fuel tank, a high-pressure fuel pump that sucks and discharges fuel from the low-pressure fuel pump to further increase the pressure, and supplies the fuel to an injector. A low-pressure regulator that opens at low pressure to return excess fuel to the fuel tank from the discharge side of the low-pressure fuel pump, and suctions excess fuel from the discharge side of the high-pressure fuel pump by opening at a predetermined high pressure In a fuel supply device for an internal combustion engine having a high-pressure regulator that returns to the high-pressure fuel pump, a high-pressure fuel pump suction side (high-pressure A return passage for returning fuel from the outlet side of the regulator to the fuel tank is provided, and an orifice for regulating the return amount is provided in this return passage.

In other words, the outlet side of the high-pressure regulator is connected to the suction side of the high-pressure fuel pump and the fuel tank, and an orifice for regulating the return amount to the fuel tank from the outlet side of the high-pressure regulator to the fuel tank. It is provided.

[0005] According to this, the discharge flow rate of the high-pressure fuel pump is increased, and excess fuel whose temperature has risen due to deprivation of heat from the high-pressure fuel pump is returned to the fuel tank. It is possible to prevent vapor lock of the fuel pump.

[0006] Further, when all the surplus fuel whose temperature has risen due to heat taken from the high-pressure fuel pump is returned to the fuel tank, the fuel temperature in the fuel tank rises and a large amount of vapor is generated in the fuel tank. This may cause overflow of the canister, etc., but excess fuel is returned from the outlet side of the high-pressure regulator to the suction side of the high-pressure fuel pump and the fuel tank, and the return amount to the fuel tank is regulated by the orifice. In addition, the amount of fuel received by the high-pressure fuel pump and returned to the fuel tank can be made constant, and the amount of vapor generated in the fuel tank can be reduced.

[0007]

However, in such a conventional fuel supply system for an internal combustion engine, although a relatively small amount of fuel is always returned to the inside of the fuel tank, a fixed amount of the received fuel always returns to the fuel tank. It is inevitable that the fuel temperature in the tank rises, and there is a problem that generation of vapor in the fuel tank cannot be completely suppressed, and there is still room for improvement.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to achieve both higher-dimensional prevention of vapor lock of a high-pressure fuel pump and reduction of the amount of vapor generated in a fuel tank. .

[0009]

Therefore, in the present invention,
An internal combustion engine fuel supply device having the following conceptual device configuration is provided.

According to the first aspect of the present invention, there is provided a low-pressure fuel pump for sucking and discharging fuel in a fuel tank, a high-pressure fuel pump for sucking and discharging fuel from the low-pressure fuel pump and supplying the fuel to a fuel injection valve, and a low-pressure fuel pump. A low-pressure regulator that returns excess fuel from the discharge side of the pump to the fuel tank, a high-pressure regulator that returns excess fuel from the discharge side of the high-pressure fuel pump to the suction side of the high-pressure fuel pump, and a part of fuel from the suction side of the high-pressure fuel pump A fuel supply device for an internal combustion engine, comprising: a return passage returning to a fuel tank; a fuel temperature detecting means for detecting a fuel temperature; Return control means for returning to the tank and closing the return passage when the temperature is low.

In the invention according to claim 2, when the fuel is returned to the fuel tank by the return control means, the valve opening pressure of the low-pressure regulator is increased to increase the fuel supply pressure to the high-pressure fuel pump. A low-pressure fuel pressurizing means at the time of return is provided.

According to a third aspect of the present invention, the return control means returns a part of the fuel to the fuel tank through the return passage even when the engine is started. The present invention also provides a fuel supply device for an internal combustion engine having the following specific device configuration so that the above-described return control and the like can be optimally performed (claims 4 to 11).

According to a fourth aspect of the present invention, there is provided a low-pressure fuel pump for sucking and discharging fuel in a fuel tank, a high-pressure fuel pump for sucking and discharging fuel from the low-pressure fuel pump and supplying the fuel to a fuel injection valve, and a low-pressure fuel pump. A low-pressure regulator that returns excess fuel from the discharge side of the pump to the fuel tank, a high-pressure regulator that returns excess fuel from the discharge side of the high-pressure fuel pump to the suction side of the high-pressure fuel pump, and a part of fuel from the suction side of the high-pressure fuel pump In a fuel supply device for an internal combustion engine, comprising: a return passage returning to a fuel tank; a return control valve capable of opening and closing the passage in the return passage; and an orifice (second orifice) disposed downstream of the control valve. On the other hand, the low-pressure regulator, by the sum of the built-in spring force and the pressure guided to the valve opening pressure variable port,
A valve opening pressure is set, and a pressure between the return control valve and the orifice is guided to the valve opening pressure variable port.

According to a fifth aspect of the present invention, the return control valve is controlled to be ON / OFF. An orifice (first orifice) different from the orifice is provided in series with the return control valve, and the variable valve opening pressure is provided. The pressure between the two orifices is directed to the application port.

In the invention according to claim 6, a bypass passage is provided to bypass the downstream orifice (second orifice) and communicates with the fuel tank, and a regulator that opens the valve at a predetermined pressure or higher is provided in the bypass passage. It is characterized by.

In the invention according to claim 7, the opening of the return control valve can be continuously controlled, and the opening of the return control valve is controlled so that the supply pressure of the fuel to the high-pressure fuel pump becomes a target value when the valve is opened. It is characterized by being performed.

The invention according to claim 8 is characterized in that the return control valve is disposed in a fuel tank. The invention according to claim 9 is characterized in that the return control valve is arranged in a casing of a high-pressure fuel pump.

According to a tenth aspect of the present invention, a fuel temperature sensor for controlling the return control valve is provided in a fuel passage in a casing of the high-pressure fuel pump. The invention according to claim 11 is characterized in that a fuel temperature sensor for controlling the return control valve is provided in a fuel pipe in a fuel tank.

[0019]

According to the first aspect of the present invention, the fuel temperature (preferably, the fuel temperature near the high-pressure fuel pump) is detected directly or indirectly, and the return at high temperature is performed according to the detected fuel temperature. A part of the fuel is returned to the fuel tank by the passage, and the return passage is closed at low temperatures to return the fuel to the fuel tank only when heat-resistant (when high-pressure fuel pump cooling is required). As a lesson,
The fuel temperature in the fuel tank can be reduced.

According to the second aspect of the present invention, when the fuel returns in a high temperature state, the valve opening pressure of the low pressure regulator is increased to increase the supply pressure of the fuel to the high pressure fuel pump, thereby increasing the pressure of the high pressure fuel pump. The generation of vapor at the time can be suppressed, and the vapor lock can be reliably prevented.

According to the third aspect of the present invention, even when the engine is started, a part of the fuel is returned to the fuel tank through the return passage, so that the vehicle travels in a returnless state, and the low pressure is applied when the engine is restarted immediately after the engine is stopped. Scavenging of the vapor in the system fuel pipe becomes possible, and startability can be improved. Further, if the fuel pressure of the low-pressure system is increased at the same time as the fuel return at the time of starting the engine, it is possible to liquefy the vapor and further improve the startability.

According to the fourth aspect of the present invention, the return passage is provided with a return control valve capable of opening and closing the passage and an orifice disposed downstream of the control valve, while a low-pressure regulator is provided. The valve opening pressure is set by the sum of the spring force and the pressure guided to the valve opening pressure variable port, and the pressure between the return control valve and the orifice is applied to the valve opening pressure variable port. , Return control and increase in fuel pressure of the low-pressure system at the time of return can be performed with a simple device configuration.

According to the fifth aspect of the present invention, when the return control valve is controlled to be turned on / off, an orifice is attached to the return control valve, and the pressure between the orifice and the downstream orifice is reduced. By guiding to the valve pressure variable port, a desired valve opening pressure variable pressure can be obtained at the time of return, and it is possible to reliably increase the fuel pressure of the low pressure system at the time of return.

According to the sixth aspect of the present invention, by providing a bypass passage that bypasses the downstream orifice and communicates with the fuel tank, and by providing a regulator that opens the valve at a predetermined pressure or higher in the bypass passage, the return time is reduced. Using the regulator, a desired valve opening pressure variable pressure can be more accurately obtained, and the fuel pressure of the low-pressure system can be more reliably increased at the time of return. In this case, the orifice on the downstream side has a function of releasing fuel and releasing the increase in fuel pressure of the low-pressure system when the returnless state is established.

According to the seventh aspect of the present invention, the opening of the return control valve is continuously controlled so that the fuel supply pressure to the high-pressure fuel pump is set to the target value when the return control valve is opened.
The fuel pressure of the low-pressure system can be increased accurately and reliably.

According to the eighth aspect of the present invention, by arranging the return control valve in the fuel tank, the pressure for varying the valve opening pressure can be controlled with good response. Controllability is improved.

According to the ninth aspect of the present invention, the return control valve is disposed in the casing of the high-pressure fuel pump and is incorporated in the high-pressure fuel pump, so that the cost can be reduced and the layout can be improved.

According to the tenth aspect of the present invention, the fuel temperature sensor is provided in the fuel passage in the casing of the high-pressure fuel pump, so that the fuel temperature in the vicinity of the high-pressure fuel pump, which is closely related to the vapor lock, can be accurately detected. can do.

According to the eleventh aspect, by providing the fuel temperature sensor in the fuel pipe in the fuel tank, the layout can be improved.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention.

A low-pressure fuel pump 2 and a low-pressure regulator 3 are provided in the fuel tank 1. The low-pressure fuel pump 2 is driven by an electric motor, and sucks and discharges the fuel in the fuel tank 1. The low-pressure regulator 3 opens when the pressure on the discharge side of the low-pressure fuel pump 2 becomes equal to or higher than a predetermined valve opening pressure, and returns excess fuel from the discharge side of the low-pressure fuel pump 2 to the fuel tank 1.

Here, the low pressure regulator 3 has a valve opening pressure varying port 3a, and the valve opening pressure is set by the sum of a built-in spring force and a pressure guided to the port. When the pressure guided to the valve opening pressure variable port 3a is atmospheric pressure, the valve opening pressure of the low pressure regulator 3 is set to, for example, 0.35 MPa by the built-in spring force, and the pressure is guided to the valve opening pressure variable port 3a. The applied pressure is, for example, 0.35MP
a, the valve opening pressure of the low pressure regulator 3 becomes 0.35+
0.35 = 0.7 MPa.

The fuel from the low pressure fuel pump 2 is sent to the suction side of the high pressure fuel pump 5 by the fuel supply pipe 4. The high-pressure fuel pump 5 is driven by a crankshaft of the engine via a belt and a pulley, inhales and discharges fuel from the low-pressure fuel pump 2, further increases the pressure, and supplies the fuel to an electromagnetic fuel injection valve 6 of the engine.

The engine is a direct injection spark ignition type internal combustion engine, and a fuel injection valve 6 is provided for each cylinder to inject fuel directly into the combustion chamber. The high pressure regulator 7
Incorporated in the casing 8 of the high-pressure fuel pump 5,
When the pressure on the discharge side of the high-pressure fuel pump 5 becomes equal to or higher than a predetermined valve opening pressure (set by a built-in spring force, for example, 7 to 10 MPa), the valve is opened, and excess fuel is discharged from the discharge side of the high-pressure fuel pump 5 to the high-pressure fuel. Return to the suction side of pump 5.

Here, the outlet side of the high-pressure regulator 7 is
It is connected to the suction side of the high-pressure fuel pump 5, and is connected to the fuel tank 1 by a return passage 9 from the suction side of the high-pressure fuel pump 5.

In the fuel tank 1, the return passage 9
Is provided with a return control valve 10 that can open and close the passage by ON / OFF control, and the return control valve 10 includes a first orifice 11 that regulates the flow rate of the return passage 9 integrally therewith. ing.

In the fuel tank 1, a second orifice 12 is provided downstream of the return control valve 10 and the first orifice 11 in the return passage 9, and the return passage 9 connects the second orifice 12. The fuel tank 1 is open through the fuel tank 1.

Here, the pressure between the first orifice 11 and the second orifice 12 is led to the valve opening pressure varying port 3a of the low pressure regulator 3.

In order to control the return control valve 10,
In order to detect the fuel temperature near the high-pressure fuel pump 5, a fuel temperature sensor 13 is provided in a fuel passage in the casing 8 of the high-pressure fuel pump 5, specifically, on the outlet side of the high-pressure regulator 7.

FIG. 2 is a conceptual block diagram of the control of the return control valve 10. The fuel temperature is detected by the fuel temperature detecting means (fuel temperature sensor 13), and the return control means responds to the detected fuel temperature. When the temperature is high, the return control valve 10 is opened, and a part of the fuel is returned to the fuel tank 1 through the return passage 9.
0 is closed, and the return passage 9 is closed.

When fuel is returned to the fuel tank 1 by the return control means, the low-pressure fuel pressurizing means at the time of return, that is, the pressure between the first and second orifices 11 and 12 at this time causes the low-pressure regulator 3 to operate. The supply pressure of fuel to the high-pressure fuel pump 5 is increased by increasing the valve opening pressure.

FIG. 3 is a flowchart showing a specific example (1) of the return control. This flow is started by turning on the ignition switch. In S11, the fuel temperature Tf detected by the fuel temperature sensor 13 is read, and it is determined whether or not the temperature is equal to or higher than a predetermined value (heat-resistant limit temperature) A.

If the fuel temperature Tf <A (low temperature), S
Proceeding to 14, the return control valve 10 is turned off and closed. As a result, a returnless state is established, and an increase in the fuel temperature in the fuel tank 1 is suppressed.

If the fuel temperature Tf ≧ A (when the temperature is high), the process proceeds to S12, where the return control valve 10 is turned on to open. As a result, a fuel return state is established, the high-pressure fuel pump 5 can be cooled, and generation of vapor can be suppressed.

In the fuel return state, the process proceeds to S13,
The fuel temperature Tf detected by the fuel temperature sensor 13 is read, and it is determined whether or not the temperature has become equal to or lower than a predetermined value B lower than the predetermined value (heat-resistant limit temperature) A.

As long as the fuel temperature Tf> B, this determination is repeated while the fuel return state is maintained, and the fuel temperature Tf ≦ B
Then, the routine proceeds to S14, where the return control valve 10 is turned off.
F and close to returnless state.

Here, when the fuel temperature Tf is low and the return control valve 10 is closed, the pressure between the first and second orifices 11 and 12 is substantially atmospheric pressure.
The pressure guided to the valve opening pressure varying port 3a of the low pressure regulator 3 also becomes substantially atmospheric pressure, and the valve opening pressure of the low pressure regulator 3 is set to, for example, 0.35 MPa by a built-in spring.

The fuel temperature Tf is a predetermined value (heat-resistant limit temperature) A
After the above, the return control valve 10 is opened until the fuel pressure returns to the predetermined value B, and the fuel is returned. The return flow rate at this time is regulated by the first orifice 11.

The second orifice 11 is located downstream of the second orifice 11.
An orifice 12 is provided, and in a fuel return state, a pressure between the first and second orifices 11 and 12 is a predetermined value,
For example, it is maintained at 0.35 MPa.

Therefore, at this time, the low-pressure regulator 3
Since the pressure of 0.35 MPa is guided to the valve opening pressure variable port 3a of the low pressure regulator 3, the valve opening pressure of the low pressure regulator 3 is 0.35 MPa.
+ 0.35 = 0.7 MPa.

Therefore, in the fuel return state where the fuel temperature Tf is high, the supply pressure of the fuel to the high-pressure fuel pump 5 is increased to suppress the generation of vapor in the high-pressure fuel pump 5 and to reliably prevent the vapor lock. .

FIG. 4 is a flowchart showing a specific example (2) of the return control. In this flow, S1 and S2 are added to the flow of FIG. In S1, it is determined whether or not the start switch (ST / SW) is ON. If the switch is ON, the control from S11 is performed as in the flow of FIG.

If the start switch is OFF, the process goes to S2
Then, the engine speed Ne is read, and it is determined whether the engine speed Ne is equal to or lower than a predetermined engine stall determination speed X (for example, 400 to 500 rpm). If Ne> X, the control from S11 onward is performed similarly to the flow of FIG. Do.

On the other hand, when Ne ≦ X (at the time of engine stall), the routine proceeds to S14, where the return control valve 10 is turned off.
And return to the returnless state. This is for suppressing the pressure drop of the fuel system and improving the restartability.

FIG. 5 is a flowchart showing a specific example (3) of the return control. In this flow, S1, S3, and S4 are added to the flow of FIG. In S1, it is determined whether or not the start switch (ST / SW) is ON, and
In the case of F, the control from S11 onward is performed as in the flow of FIG.

If the start switch is ON, the process proceeds to S3, where the return control valve 10 is turned ON to open. As a result, at the time of starting, the fuel return state is forcibly set.
This allows the vehicle to travel in a returnless state and scavenge the vapor in the low-pressure fuel pipe at the time of restarting immediately after stopping the engine, for example, and improve the startability. Further, since the fuel pressure of the low-pressure system is increased at the same time as the fuel return at the time of starting, the vaporization of the vapor is also possible, and the startability can be further improved. In addition, since high-pressure fuel can be obtained quickly at the time of starting, it is possible to atomize the injected fuel and secure a required flow rate, and the starting fuel can be sufficiently covered only by the direct injection type fuel injection valve.

After S3, the process proceeds to S4, in which it is determined whether or not a predetermined time (for example, 2 seconds) has elapsed. After the predetermined time has elapsed, the control in S11 and subsequent steps is performed as in the flow of FIG. The reason why the compulsory fuel return time at the start is not synchronized with the ON time of the start switch and is set to a predetermined time from the start of the start is that the fuel return time is insufficient when the ON time of the start switch is extremely short. This is to prevent it.

FIG. 6 is a flowchart showing a specific example (4) of the return control. In this flow, S1, S2, S3, and S4 are added to the flow of FIG.
And the flow of FIG. 5 are integrated.

At S1, the start switch (ST / S
It is determined whether or not W) is ON. Start switch is ON
In the case of, the process proceeds to S3, where the return control valve 10 is turned on to open. As a result, at the time of starting, the fuel return state is forcibly set.

After S3, the process proceeds to S4, in which it is determined whether or not a predetermined time (for example, 2 seconds) has elapsed. After the predetermined time has elapsed, the control in S11 and subsequent steps is performed as in the flow of FIG. If the start switch is OFF, the process proceeds to S2, where the engine speed Ne is read, and a predetermined engine stop speed X is determined.
(For example, 400 to 500 rpm) or less,
If Ne> X, the control from S11 onward is performed as in the flow of FIG.

On the other hand, when Ne ≦ X (at the time of engine stall), the routine proceeds to S14, where the return control valve 10 is turned off.
And return to the returnless state. Next, in the present embodiment, when the return control valve 10 is opened, the first
Pressure P2 between orifice 11 and second orifice 12
The reason why can be controlled to a predetermined value (for example, 0.35 MPa) will be described with reference to FIG.

The discharge flow rate of the low-pressure fuel pump 2 is defined as Q0,
The flow rate returned from the discharge side of the low-pressure fuel pump 2 to the fuel tank 1 through the low-pressure regulator 3 is Q1, and the flow rate returned to the fuel tank 1 through the return control valve 10 is Q2.
And The flow rate consumed and consumed from the fuel injection valve 6 is defined as Q3.

Further, the basic valve opening pressure by only the built-in spring force of the low pressure regulator 3 is P0, and the pressure on the discharge side of the low pressure fuel pump 2 to be controlled (the actual valve opening pressure of the low pressure regulator 3) is P1. .

The throttle coefficient of the first orifice 11 is set to A
And the throttle coefficient of the second orifice 12 is B. Here, the following relationship is established.

Q2 = A × √ (P1-P2) (1) Q2 = B × √ (P2) (2) P1 = P0 + P2 (3) where (1), (1) From the equation 3), Q2 = A × √ (P0). . . (4)

From equations (2) and (4), P2 = P0 × (A / B) ² (5) Further, from equations (3) and (5), P1 = P0 + P0 × (A / B B) ² ... (6)

Therefore, the first and second orifices 11, 1
The pressure P2 between the two is determined by the basic valve opening pressure (spring force) P0 of the low pressure regulator 3 and the throttling coefficients A and B of the first and second orifices 11 and 12, as can be seen from equation (5). You.

As can be seen from equation (6), the pressure P1 of the low-pressure fuel system also includes the basic valve-opening pressure (spring force) P0 of the low-pressure regulator and the throttling coefficients A and A of the first and second orifices 11 and 12. B.

FIG. 8 shows a second embodiment of the present invention. In the first embodiment (FIG. 1), the return control valve 10 and the first orifice 11 are arranged in the fuel tank 1, whereas in the second embodiment (FIG. 8), the return control valve 10
And the first orifice 11 is arranged in the casing 8 of the high-pressure fuel pump 5.

When the return control valve 10 is opened at the time of starting, a predetermined pressure is immediately introduced to the valve opening pressure varying port 3a of the low pressure regulator 3 to increase the fuel pressure of the low pressure system. One embodiment is better,
In the case of the second embodiment, since the return control valve 10 and the first orifice 11 can be integrated into the high-pressure fuel pump 5, there are merits in cost and layout.

Further, in the first embodiment (FIG. 1), the fuel temperature sensor 13 is provided in the fuel passage in the casing 8 of the high-pressure fuel pump 5, whereas in the second embodiment (FIG. 8)
Here, the fuel temperature sensor 13 is provided on the fuel pipe in the fuel tank 1, specifically, on the outlet side of the low-pressure fuel pump 2.

The first embodiment is superior in detecting the fuel temperature in the vicinity of the high-pressure fuel pump 5 where vapor lock is a problem, but the fuel temperature in the fuel pipe in the fuel tank 1 and the high-pressure fuel pump Since there is a correlation with the fuel temperature in the vicinity of 5, it is possible to estimate the latter from the former, and the second embodiment may be superior in layout in some cases.

FIG. 9 shows a third embodiment of the present invention. In the third embodiment, a bypass passage 14 that bypasses the second orifice 12 and communicates with the fuel tank 1 is provided.
A regulator 15 is provided in the bypass passage 14 at a pressure equal to or higher than a predetermined pressure.

Therefore, if the valve opening pressure (spring force) of the regulator 15 is set to, for example, 0.35 MPa,
When the return control valve 10 is opened, the first orifice 11 guided to the valve opening pressure variable port 3a of the low pressure regulator 3
The pressure between the pressure regulator and the regulator 15 can be reliably regulated to a predetermined pressure (0.35 MPa), and the valve opening pressure of the low-pressure regulator 3 can be accurately increased.

In this case, the second orifice 12 acts to return the pressure guided to the valve opening pressure changing port 3a of the low pressure regulator 3 to approximately atmospheric pressure after the return control valve 10 is closed.

FIG. 10 shows a fourth embodiment of the present invention. The fourth embodiment is different from the third embodiment (FIG. 9) in that the return control valve 10 and the first orifice 11 are connected to the casing 8 of the high-pressure fuel pump 5 similarly to the second embodiment (FIG. 8).
And the fuel temperature sensor 13 is connected to the fuel tank 1.
The fuel pipe is provided at the outlet side of the low-pressure fuel pump 2. Therefore, the operation and effect of the third embodiment and the operation and effect of the second embodiment are combined.

FIG. 11 shows a fifth embodiment of the present invention. The fifth embodiment is different from the first embodiment (FIG. 1) in that the opening of the return control valve 10 can be continuously controlled by duty control, and the discharge side of the low-pressure fuel pump 2 (the low-pressure regulator 3 A pressure sensor 16 for detecting the pressure P1 on the inlet side is provided, and when the return control valve 10 is opened, the opening degree is controlled so that the supply pressure to the high-pressure fuel pump 5 becomes a target value (for example, 0.7 MPa). It was made.

In this case, when the return control valve 10 is turned on in S12 of the return control example of FIG. 3 or FIG. 4 or S3 and S12 of the return control example of FIG. Duty control is performed according to a subroutine shown in FIG.

That is, in S101, the fuel pressure P1 is detected by the pressure sensor 16 and the target value (for example, 0.7MPa) is detected.
Compared with a), if P1 <target value, the routine proceeds to S102, in which the valve opening duty (valve opening time ratio) for the return control valve 10 is increased. As a result, the pressure guided to the valve opening pressure changing port 3a of the low pressure regulator 3 increases, and the valve opening pressure increases, so that the fuel pressure P1 can approach the target value.

Conversely, if P1> target value, the routine proceeds to S103, where the valve opening duty (valve opening time ratio) for the return control valve 10 is reduced. As a result, the pressure guided to the valve opening pressure varying port 3a of the low pressure regulator 3 decreases, and the valve opening pressure decreases. As a result, the fuel pressure P1 can approach the target value.

In other words, by the duty control of the return control valve 10, the pressure guided to the valve opening pressure variable port 3 a of the low pressure regulator 3 is set to a predetermined value (0.35 MPa).
Thus, the pressure on the discharge side of the low-pressure fuel pump 2 is accurately controlled to the target value (0.7 MPa).

In this case, since the return control valve 10 is provided with an orifice function by controlling the opening degree of the return control valve 10, the first orifice 11 can be eliminated.
Also, as in the third and fourth embodiments, the regulator 1
5, the pressure guided to the valve opening pressure variable port 3a of the low pressure regulator 3 is set to a predetermined value (for example, 0.35
MPa) can be accurately controlled.

In the fifth embodiment, similarly to the second embodiment (FIG. 8), the return control valve 10 is disposed in the casing 8 of the high-pressure fuel pump 5, and the fuel temperature sensor 13 is connected to the fuel tank. 1 may be provided in the fuel pipe.

FIG. 13 shows a timing chart of the above control example particularly in the case of a hot restart. After the ignition switch (IGN / SW) is turned on, when the fuel temperature Tf is higher than a predetermined value (heat-resistant limit value) A when the start switch (ST / SW) is turned on, the return control valve 10 is operated until the fuel temperature Tf drops to a predetermined value B. The valve is fully opened or is opened while the duty is being controlled, and the valve opening pressure of the low-pressure regulator 3 is changed from a predetermined value a (0.35 MPa) to a predetermined value b (0.7MPa).
a).

After the start switch is turned off, the fuel temperature T
When f becomes higher than a predetermined value (heat resistance limit value) A, a predetermined value B
Until the return control valve 10 is fully opened,
Open while controlling duty, low pressure regulator 3
The valve opening pressure from the predetermined value a (0.35 MPa) to the predetermined value b
(0.7 MPa).

[Brief description of the drawings]

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

FIG. 2 is a conceptual block diagram of control.

FIG. 3 is a flowchart showing a return control example (1).

FIG. 4 is a flowchart showing a return control example (2).

FIG. 5 is a flowchart showing a return control example (3).

FIG. 6 is a flowchart showing a return control example (4).

FIG. 7 is an explanatory diagram of a pressure between orifices.

FIG. 8 is a system diagram of a fuel supply device according to a second embodiment of the present invention.

FIG. 9 is a system diagram of a fuel supply device according to a third embodiment of the present invention.

FIG. 10 is a system diagram of a fuel supply device according to a fourth embodiment of the present invention.

FIG. 11 is a system diagram of a fuel supply device according to a fifth embodiment of the present invention.

FIG. 12 is a diagram showing a duty control subroutine in a fifth embodiment.

FIG. 13 Time chart

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel tank 2 Low pressure fuel pump 3 Low pressure regulator 3a Valve opening pressure variable port 4 Fuel supply pipe 5 High pressure fuel pump 6 Fuel injection valve 7 High pressure regulator 8 Casing 9 Return passage 10 Return control valve 11 First orifice 12 Second orifice 13 Fuel temperature sensor 14 Bypass passage 15 Regulator 16 Pressure sensor

Claims (11)

[Claims] 1. A low-pressure fuel pump for sucking and discharging fuel in a fuel tank, a high-pressure fuel pump for sucking and discharging fuel from the low-pressure fuel pump and supplying it to a fuel injection valve, and a surplus from a discharge side of the low-pressure fuel pump. A low-pressure regulator that returns fuel to the fuel tank, a high-pressure regulator that returns excess fuel from the discharge side of the high-pressure fuel pump to the suction side of the high-pressure fuel pump, and a return passage that returns part of the fuel from the suction side of the high-pressure fuel pump to the fuel tank. A fuel temperature detecting means for detecting a fuel temperature; and returning a part of the fuel to the fuel tank by the return passage at a high temperature according to the detected fuel temperature. And a return control means for closing the return passage. 2. A return-time low-pressure fuel pressurizing means for increasing the valve opening pressure of the low-pressure regulator to increase the supply pressure of fuel to the high-pressure fuel pump when returning fuel to the fuel tank by the return control means. The fuel supply device for an internal combustion engine according to claim 1, wherein: 3. The fuel supply device for an internal combustion engine according to claim 1, wherein said return control means returns a part of the fuel to the fuel tank through the return passage even when the engine is started. 4. A low-pressure fuel pump for sucking and discharging fuel in a fuel tank, a high-pressure fuel pump for sucking and discharging fuel from the low-pressure fuel pump and supplying the fuel to a fuel injection valve, and a surplus from the discharge side of the low-pressure fuel pump. A low-pressure regulator that returns fuel to the fuel tank, a high-pressure regulator that returns excess fuel from the discharge side of the high-pressure fuel pump to the suction side of the high-pressure fuel pump, and a return passage that returns part of the fuel from the suction side of the high-pressure fuel pump to the fuel tank. In the fuel supply device for an internal combustion engine, comprising: a return control valve capable of opening and closing the passage, and an orifice disposed downstream of the control valve in the return passage; The valve opening pressure is set by the sum of the spring force of the valve and the pressure guided to the valve opening pressure variable port. The fuel supply apparatus for an internal combustion engine, characterized in that to guide the pressure between the return control valve and the orifice. 5. The return control valve is controlled to be ON / OFF. The return control valve is provided with an orifice different from the orifice in series with the return control valve.
5. The fuel supply device for an internal combustion engine according to claim 4, wherein a pressure between two orifices is introduced. 6. The internal combustion engine according to claim 5, wherein a bypass passage is provided to bypass the downstream orifice and communicates with the fuel tank, and a regulator is provided in the bypass passage at a predetermined pressure or higher. Fuel supply system. 7. The return control valve is capable of continuously controlling an opening degree, and is controlled such that a fuel supply pressure to a high-pressure fuel pump is set to a target value when the return control valve is opened. The fuel supply device for an internal combustion engine according to claim 4, wherein 8. The fuel supply system according to claim 4, wherein said return control valve is disposed in a fuel tank.
A fuel supply device for an internal combustion engine according to any one of claims 1 to 3. 9. The fuel supply device for an internal combustion engine according to claim 4, wherein the return control valve is disposed in a casing of the high-pressure fuel pump. 10. A fuel temperature sensor for controlling the return control valve is provided in a fuel passage in a casing of a high-pressure fuel pump according to any one of claims 4 to 9. Fuel supply device for internal combustion engine. 11. The internal combustion engine according to claim 4, wherein a fuel temperature sensor for controlling the return control valve is provided in a fuel pipe in a fuel tank. Fuel supply device.