JP2001295724A - Fuel supply device for internal combustion engine - Google Patents

Abstract

(57) [Problem] To provide a fuel supply device for an internal combustion engine which can variably set an optimum fuel pressure in an operation state by using a simple structure, and which can be easily reduced in cost. SOLUTION: Fuel passages 5 and 6 connecting a fuel tank 7 and a fuel injection valve 2 provided in an engine 1, a high-pressure pump 13 provided in the fuel passage, and a fuel from the fuel pump 13 are provided. In a fuel supply device A for an internal combustion engine including a high-pressure regulator 18 for regulating pressure, the high-pressure regulator 18 includes a first port a for introducing fuel, a second port b for discharging surplus fuel, and a A plunger (adjustment member) 24 for switching and adjusting the communication state of
A spring 27 for urging the plunger 24 in a direction to close the second port b, and an upper space e1 or a lower space e2 (fuel pressure adjustment chamber) into which hydraulic pressure (pressure for fuel pressure adjustment) for adjusting the urging force of the spring is introduced. ).

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 use in a direct injection type internal combustion engine or the like, and more particularly to a method for switching a fuel injection pressure of a fuel injection valve to a combustion chamber of an internal combustion engine in accordance with an operation state. The present invention relates to a fuel supply device for an internal combustion engine that can be adjusted.

[0002]

2. Description of the Related Art A fuel supply device for a direct injection type engine is:
For example, the fuel in the fuel tank is first pressurized by a low-pressure pump, and the low-pressure fuel is secondarily pressurized by a high-pressure pump and supplied to the fuel injection valve of each cylinder. Each fuel injection valve is injection-controlled at a predetermined fuel injection timing by a fuel injection control system to perform fuel injection into the cylinder. A high-pressure regulator is provided in the discharge path of the high-pressure pump, and is configured to return surplus fuel of the high-pressure fuel that has been secondarily pressurized to the fuel tank.

[0003] In such a direct injection engine,
The fuel injection valve needs to perform a relatively large amount of fuel injection in response to a change in the operating range of the engine, that is, a relatively large amount of fuel injection during high-speed high-load operation and a relatively small amount of fuel injection during low-speed low-load operation. However, when the fuel injection pressure of the fuel injection valve is adjusted to be constant by the high-pressure regulator, the fuel injection time width becomes relatively short during high-speed high-load operation, and the fuel injection pressure is not sufficiently increased. And the required injection amount cannot be secured, the fuel injection pressure is set to a high pressure (for example, 8 to 10).
Mpa) is desirable. However, if the fuel injection pressure is set to a high pressure, the penetration of the fuel spray is strengthened, the fuel spray tends to adhere to the cylinder liner, and a new problem of reducing the lubricity of the liner is likely to occur. Conversely, during low-speed low-load operation, it is necessary to keep the fuel injection amount low. Therefore, it is desirable to keep the fuel injection time width as short as possible and set the fuel injection pressure to a low pressure (for example, 5 Mpa). In this case, there is no problem if the dynamic range of the fuel injection valve is widened to secure a large adjustment width of the injection amount. However, in this case, the size of the fuel injection valve becomes large, and problems in mounting and cost are likely to occur.

In order to solve such a problem, it is desirable that the fuel injection pressure is set to be low in a low rotation speed operation range and the fuel injection pressure is set to be high in a high rotation speed operation range. As shown in FIG.
FIG. 1A shows a high-pressure spill type fuel supply device, and FIG.
A low pressure spill type fuel supply device shown in FIG. 3 (b) is known. The high-pressure spill type fuel supply device shown in FIG.
, And pressurizes the high-pressure fuel in the delivery pipe 12.
The fuel is supplied to each of the fuel injection valves 130 through the fuel injection chamber 130 to perform fuel injection into the combustion chamber. Here, a part of the secondary pressurized high-pressure fuel is returned to the drain side via the duty solenoid valve 140. The duty solenoid valve 140 is connected to the controller 160 via the driver 150, and the controller sets the current fuel pressure of the high-pressure fuel in the delivery pipe detected by the fuel pressure sensor 170 to one of a plurality of set fuel pressures set according to the operation range. The pressure of the duty solenoid valve 140 is controlled so that the pressure is adjusted.

A low pressure spill type fuel supply device shown in FIG. 13B has a solenoid valve 1 which is an open / close valve before fuel from a primary pressurizing section 100 is supplied to a high pressure pump 110.
At 80, the pumping fuel amount is adjusted by increasing / decreasing the suction period, the fuel pressure is controlled, and a part is returned to the drain side. The high-pressure fuel secondary-pressurized by the high-pressure pump 110 is supplied to the delivery pipe 1
The fuel is supplied to each fuel injection valve 130 via the fuel injection valve 20 and injected into the combustion chamber. The solenoid valve 180 is connected to the driver 15
0, the controller 160 detects the injector injection amount, the crank angle or the cam angle (for adjusting the closing timing of the solenoid valve), and the fuel pressure from the fuel pressure sensor 170, and closes the valve in the pump suction stroke. The timing is controlled and the amount of pumping is adjusted.

[0006]

In the case of the high-pressure spill type fuel supply device shown in FIG. 13A, the controllability is facilitated, but the drive is performed by returning the high-pressure fuel to the drain side by the duty solenoid valve 140. Loss is relatively large. The low-pressure spill type fuel supply device shown in FIG.
Although the secondary pressurized fuel in the high-pressure pump 110 is all injected, the driving loss is small, but there is a problem that the fuel pressure drop takes time because the fuel pressure drop depends only on the injection of the injector 130. In addition, high responsiveness of the solenoid valve 180 is required, and control becomes complicated. An object of the present invention is to provide a fuel supply device for an internal combustion engine that can variably set an optimum fuel pressure for an operation state using a simple structure and that is easy to reduce cost based on the above-described problem.

[0007]

To achieve the above object, according to the first aspect of the present invention, there is provided a fuel passage connecting between a fuel tank and a fuel injection valve provided in an internal combustion engine; A fuel pump provided therein and driven by the internal combustion engine; and a pressure adjusting mechanism for adjusting the pressure of fuel discharged from the fuel pump. A second port for discharging surplus fuel, an adjusting member for adjusting a fuel pressure by switching a communication state between the first port and the second port, and It is characterized by comprising an urging member for urging the adjusting member in a closing direction, and a fuel pressure adjusting chamber into which a fuel pressure adjusting pressure for adjusting the urging force of the urging member is introduced. As described above, the fuel pressure can be variably adjusted by the fuel pressure adjusting pressure in the fuel pressure adjusting chamber, and the optimum fuel pressure can be obtained for the operating state using a relatively simple structure, and cost reduction can be easily achieved. Furthermore, the fuel pressure adjustment chamber receives the pressure for adjusting the fuel pressure different from the fuel and variably adjusts the fuel pressure, thereby improving the safety, high durability and reliability of the device itself, and furthermore, the pressure adjustment mechanism is improved. Because it is downstream of the pump, it has excellent controllability. Preferably, the pressure adjustment chamber may adjust the biasing force of the biasing member after boosting the pressure introduced into the same chamber using a booster mechanism,
In this case, the booster mechanism can perform high fuel pressure control using relatively low fuel pressure adjustment pressure.

According to a second aspect of the present invention, in the fuel supply device for an internal combustion engine according to the first aspect, the fuel pressure adjusting chamber includes a discharge pressure from an oil pump driven by the internal combustion engine, an intake pressure of the internal combustion engine, It is characterized in that any one of the exhaust air pressures is introduced as the fuel adjustment pressure. When the discharge pressure from the oil pump or the air pressure of the intake or exhaust of the internal combustion engine is used, the fuel pressure can be variably adjusted according to the number of revolutions of the internal combustion engine with a simple structure.
Safety, high durability and reliability of the device itself can be further improved. Preferably, the air pressure of the intake or exhaust of the internal combustion engine is a supercharging pressure by a supercharger arranged in the internal combustion engine,
The intake negative pressure in the intake manifold of the internal combustion engine or the exhaust positive pressure in the exhaust manifold may be used. In this case, the configuration can be further simplified.

According to a third aspect of the present invention, in the fuel supply system for an internal combustion engine according to the first aspect, a passage for introducing the pressure into the fuel pressure adjustment chamber and the passage are provided in the passage, and are provided depending on the driving state of the vehicle. And a controlled electric control valve. When this electric control valve is used, electronic control can be performed so as to obtain an optimum fuel pressure in accordance with the operation state, and more accurate control can be performed. As the above-mentioned electric control valve, an ON-OFF valve which is switched when a predetermined operation state is achieved, or a solenoid valve which can perform duty control can be used. In particular, in the case of duty control, the fuel pressure can be continuously varied. In particular, when the fuel pressure adjustment chamber adjusts the urging force of the urging member using a booster mechanism, it is possible to perform high fuel pressure control using a relatively low pressure for fuel pressure adjustment, and the electric control valve The size and power consumption can be reduced, and controllability is improved.

[0010]

FIG. 1 shows a fuel supply device for an internal combustion engine as one embodiment of the present invention. The fuel supply device A for an internal combustion engine is mounted on a four-cylinder in-cylinder injection engine (hereinafter simply referred to as an engine) 1 so that fuel can be directly injected into a combustion chamber (not shown) of each cylinder via an injector 2. Have been. Each injector 2 is connected to an appropriate position of a delivery pipe 3 which is provided along the longitudinal direction of the engine and is always supplied with high-pressure fuel. A drive coil (not shown) of each injector 2 is provided by a controller (ECU) 10 which forms a fuel injection control device. The injection operation is performed when an injection signal is received via the driver 4 (only one ignition system is shown in FIG. 1). A fuel pressure sensor 40 for outputting a fuel pressure in the delivery pipe 3 to the controller 10 is provided at a leading end of the delivery pipe 3, and an inflow end of the delivery pipe 3 is connected to a secondary fuel pipe 5 through a secondary fuel pipe 5 forming a part of a fuel passage. The upstream end of the secondary pressurizing system U2 is connected to a primary pressurizing system U1 via a primary fuel pipe 6 forming a part of a fuel passage. The upstream end side of the system U1 is formed so that the fuel in the fuel tank 7 can be sucked.

The primary pressurizing system U1 is housed in a fuel tank 7 and is electrically driven by a low-pressure fuel pump 8 supported by a tank body.
Is provided. The low-pressure fuel pump 8 discharges the fuel sucked through the filter 9 and the check valve 11 to the external primary fuel pipe 6 via the fuel pipe 601 in the tank at the time of driving. A part of the fuel pipe 601 in the tank is branched to open a drain port in the tank, and the branch pipe 602 is provided with the low-pressure regulator 12. The low-pressure regulator 12 is closed while the fuel pressure of the fuel pipe 601 in the tank is lower than a set primary pressurization value, and is opened when the fuel pressure is higher than the set primary pressurization value so as to maintain the set primary pressurization value. .

The secondary pressurizing system U2 includes a high-pressure fuel pump (hereinafter simply referred to as a high-pressure pump) 13 supported on a cylinder head (not shown). The high-pressure pump is pressurized in conjunction with engine driving. The fuel from the primary fuel pipe 6 is pressurized and discharged to the secondary fuel pipe 5. A bypass 14 is provided between the discharge side and the suction side of the high-pressure pump 13, and a first check valve which allows only the fuel flow from the primary fuel pipe 6 to the secondary fuel pipe 5 is provided in the bypass path 14. A valve 15 is provided. A second check valve 16 that allows only the flow of the discharge flow of the high-pressure pump 13 is provided in the vicinity of the discharge port of the high-pressure pump 13, and a second branch pipe 17 is provided between the second check valve 16 and the delivery pipe 3. It is extended. The second branch pipe 17 is connected to a later-described inflow port (first port) a of the high-pressure regulator 18, and connects a later-described outflow port b of the high-pressure regulator 18 to the drain pipe 17.
1 and communicate with the inside of the fuel tank 7. FIG.
Reference numeral 41 in the middle indicates a drain pipe that returns fuel leaking from the casing of the high-pressure pump 13 into the fuel tank 7.

As shown in FIG.
Is disposed in a receiving hole 21 formed in the cylinder head 19 of the engine 1. A fixing plug 23 is screwed into the opening of the accommodation hole 21, and the cylindrical main body 22 is accommodated in the back side, and the plunger sheet 20 is accommodated in the deepest part. Note that the cylindrical body 22 and the plunger sheet 20 are securely fixed to the accommodation holes 21 by tightening the fixing plugs 23. The cylindrical main body 22 has an inner hole 221, a lower part of a plunger (adjustment member) 24 described later is fitted in a lower part thereof, and a spring seat 28 is slidably inserted in an upper part thereof. It is fitted. The spring 27 functions as an urging member for urging the plunger 24 in a downward direction, which is a direction for closing an outflow port (second port) b described later. The cylindrical body 22 has a lower outer peripheral wall having a smaller diameter than an upper outer peripheral wall, and has an annular gap 42 between the lower peripheral wall and the inner wall of the housing hole 21. An outflow port b as a second port is formed in a portion of the cylindrical main body 22 facing the annular gap 42, and the outflow port b is formed in a portion of the cylinder head 19 that faces the annular gap 42, such as a leak hole 222 and a drain. Excess fuel in the accommodation hole 21 is discharged to the fuel tank 7 via the pipe 171.

The plunger seat 20 has a vertically formed valve hole 25 and a valve seat 26 at an open end thereof. An inflow port a as a first port into which the high-pressure fuel of the second branch pipe 17 is introduced is formed in a part of the valve hole 25. A plunger 24 as an adjusting member is slidably fitted in the valve hole 25 in a vertical direction. The plunger 24 is formed with a spring receiver 241 at the top, a valve part 242 below the spring receiver, and a guide part 243 under which the lower end slides only in the valve hole 25. The plunger 24 always receives the pressing force of the spring 27 in contact with the spring receiver 241 in the valve closing direction, and
2 can be closed by contacting the valve seat 26, the valve portion 242 receives the fuel pressure on the inflow port a side in the valve opening direction, and opens and closes in accordance with the balance between the opposing opening and closing forces. That is,
The plunger 24 functions as an adjusting member that switches the communication state between the inflow port a and the outflow port b to adjust the fuel pressure in the second branch pipe 17.

The fixing plug 23 has a substantially cylindrical shape and supports a cylindrical support frame 29 inside. The cylindrical support frame 29 includes a support portion 291 that is screwed to the inner peripheral wall of the fixed plug 23 and a cylinder portion 292 that is continuously formed with an enlarged diameter at an outer end thereof.
A lock nut 34 is screwed onto the outer peripheral wall of the support portion 291, thereby positioning the reference position of the support portion 291, that is, the upper end position h 1 of the spring seat 28. The cylinder part 292 is screwed with the cover 30 at the upper end which is the opening end thereof, thereby closing the cylinder part 292.
The cylinder portion 292 slidably fits the piston 31, and the center hole 293 of the support portion 291 slidably fits the piston rod 32 extending from the piston 31. Piston rod 3
The tip (lower end) of 2 is formed to be able to protrude below the lower end of the support portion 291 by a set amount t. That is, when the piston 31 moves from the upper end position H1 to the lower end position H2, the distal end of the piston rod 32 integrated therewith pushes the spring seat 28 against the pressing force of the spring 27 and the upper end position h1.
The lower end position h2 can be moved and held by the set amount t below,
At this time, the elastic biasing force of the spring 27 can be increased and corrected.

The cylinder portion 292 is divided by the piston 31 into upper and lower spaces e1 and e2. The lower space e2 is a communication path r1 extending from a fore-edge formed in the cylinder 292.
Is connected to a throttle upstream side of an intake system (not shown) of the engine 1 through the engine. The piston rod 32 is formed with a communication passage r2 extending from the lower end in the longitudinal direction of the axial center to the upper end. For this reason, the communication paths r1 and r2 communicate the gap e3 between the spring seat 28 and the support portion 291 and the lower space e2 to an intake system (not shown) on the open side of the atmosphere, and the negative pressure is generated by a change in the volume of these spaces. Has been prevented.

The upper space e1 of the cylinder portion 292 functions as a fuel pressure adjusting chamber into which engine oil as fuel pressure adjusting pressure is introduced. The upper space e1 communicates with a main gallery 36 in a cylinder block (not shown) via an oil pipe 35 connected to the cover 30. Main gallery 36
Is connected to a hydraulic pump 38 that sucks and discharges oil from an oil pan 37 in conjunction with the rotation of the engine 1. Since the hydraulic pump 38 is interlocked with the engine 1 while maintaining a predetermined rotation ratio, as shown in FIG. 3, the engine oil pressure is increased or decreased according to the increase or decrease of the engine speed. The branch pipe 361 is equipped with a hydraulic regulator 39 which keeps the oil in the main gallery 36 below the allowable maximum hydraulic pressure pm when the hydraulic pump 38 over-rotates and avoids unnecessary pump operation. Operate the regulator.

The piston 31 here is a piston rod 3
2 and an outer diameter larger than the spring seat 28 to constitute a hydraulic booster. The shape of the pressure receiving surface of the piston 31 is set as follows. Here, the spring seat 28 is held at the upper end position h1 by the pressing force of the spring 27 while the engine rotation speed is lower than the lower limit rotation speed n1, and when the engine rotation speed exceeds the lower limit rotation speed n1, the spring seat 28 is compressed and displaced downward against the pressing force of the spring 27. The pressure receiving surface of the piston 31 is set so as to generate a pressing force that reaches the lower end position h2 when the rotation speed exceeds the upper limit rotation speed n2. For this reason, when the engine speed is equal to or lower than the lower limit speed n1, the spring 27 is held in the initial biased state, and the plunger 24 moves between the inflow port a and the outflow port b while receiving the low-speed biasing force from the spring. And the fuel pressure in the second branch pipe 17 is adjusted to the low rotation fuel pressure FP _L (see FIG. 3). vice versa,
When the engine rotation speed is equal to or higher than the upper limit rotation speed n2, the spring 27 is kept in the set biased state, and the plunger 24 communicates between the inflow port a and the outflow port b while receiving the high rotation biasing force from the spring 27. By switching the state, the fuel pressure in the second branch pipe 17 is adjusted to the high rotation fuel pressure FP _H (see FIG. 3). The spring seat 28 moves to a position where the pressing force of the spring 27 and the hydraulic pressure are balanced between the lower limit rotation speed n1 and the upper limit rotation speed n2.
The pressing force applied to No. 4 is increased as compared with the case where the pressing force is retained at the upper end position h1. Therefore, as shown by inclined lines (n1~n2) in FIG. 3, in accordance with the rotation increase _{(FP H -FP L) / (} n2-n
The fuel pressure at a ratio of 1) is successively increased displacement from FP _L to FP _H.

When the engine 1 equipped with the fuel supply system for an internal combustion engine as described above is driven, the electric low-pressure fuel pump 8 and the high-pressure pump 13 pressurize the fuel in the fuel tank 7 to the primary and secondary levels. The high-pressure fuel is pressure-fed to the delivery pipe 3 to replenish the fuel injected and consumed by the injector 2. The controller (ECU) 10 calculates the injection amount and the injection timing according to the current fuel pressure of the engine and other operating conditions as fuel injection control means, and sends an injection signal corresponding to the calculation result to the injector 2 of each cylinder to the driver 4. And an injection operation of an appropriate injection amount by the injector 2 is performed. The controller (ECU) 10 is in calculating the injection timing and injection amount, the fuel injection time width and the injection timing as fuel held in the low rotation fuel pressure FP _L is injected by the injector 2 of the delivery pipe 3 side calculated, and executes the correction process described later when it reaches the high rotation fuel pressure FP _H.

If the primary fuel pipe 6 is excessively pressurized when the engine 1 is driven, the low pressure regulator 12 is opened to prevent an excessive rise in fuel pressure on the discharge side of the low pressure pump 8. 2
The fuel pressure of the secondary fuel pipe 5 is adjusted by the operation of the high-pressure regulator 18. At this time, in an operation range where the engine speed is relatively low (for example, a range of the lower limit speed n1 or less), the discharge amount of the hydraulic pump 38 is relatively small, and the upper space e1 of the cylinder portion 292 functioning as a fuel pressure adjustment chamber. The oil pressure is relatively low, the pressing force of the spring 27 is larger than the downward pressing force f1 applied to the piston 31, and the piston 31 is moved to the upper end position H1 as shown in the left half of FIG.
Are supported at the upper end position h1. In this case, the spring 27 has a relatively low low-rotation pressing force Ps1 (Ps1 in the figure).
Is applied to the plunger 24, and the valve portion 242 of the plunger 24 is pressed toward the valve seat 26 with the same pressing force Ps1.
Therefore, the lower limit rotation speed n1 following operation range, a relatively low low rotation fuel pressure FP _L moves the plunger 24 upward at the time of exceeding the low rotation pressure Ps1 some fuel tank 7 side of the fuel And the fuel pressure of the secondary fuel pipe 5 is maintained at the low-pressure fuel pressure.

[0021] In this case, fuel held in the low rotation fuel pressure FP _L is injected by the injector 2 of the delivery pipe 3 side, in this case, surely perform a small amount injected, the engine speed is at a relatively low operating range Can reliably execute the fuel injection amount control. On the other hand, the upper limit engine speed n where the engine speed is relatively high
2, the discharge amount of the hydraulic pump 38 rapidly increases, the oil pressure in the upper space e1 of the cylinder portion 292 is relatively high, and the downward pressure f2 applied to the piston 31
The compression force of the spring exceeds the pressing force of the
Reference numeral 1 denotes a lower end position H2 as shown in the right half of FIG. 2, and a spring seat 28 is supported at a lower end position h2.
At the same pressing force Ps2.
To the valve seat 26 side. For this reason, when the fuel pressure of the secondary fuel pipe 5 is applied to the valve portion 242 through the second branch pipe 17 in the operating range where the engine speed exceeds the relatively high upper limit speed n2, the fuel pressure FP _H for high rotation is relatively high. When the pressure exceeds the high-rotation pressing force Ps2, the plunger 24 moves completely upward, and a part of the fuel leaks to the fuel tank 7 side, so that the fuel pressure of the secondary fuel pipe 5 is maintained at the high-rotation fuel pressure.

In the region where the engine speed increases from the lower limit speed n1 to the upper limit speed n2, the piston 31 and the spring seat 28 move downward against the pressing force of the spring 27, and the pressing force of the spring 27 increases. There gradually increases, this with a slight increase also adjusted pressure operated plunger 24, fuel pressure from the low rotation fuel pressure FP _L to the high rotation fuel pressure FP _H rises removal plant.
Conversely, when the engine rotational speed is displaced from the upper limit rotational speed n2 to the lower limit rotational speed n1, the return operation can be sent due to the frictional resistance of the piston 31, and the falling displacement of the high-speed fuel pressure FP _H is delayed as shown by the broken line. Will cause hysteresis. Such a fuel pressure displacement is caused by the controller (ECU) 1
0, and the subroutine of FIG. 4 is executed by a time interruption or the like in the middle of the main routine.

In this subroutine, steps s1, 2
In, the operation information such as the engine speed and the accelerator opening is read, and then the current fuel pressure of the delivery pipe 3 is read. Next, in step s3, it is determined whether or not the current engine speed is in an operating range exceeding a threshold value nα (here, (n2 + n1) / 2). It regarded there and normal fuel injection control region in the vicinity of the rotating fuel pressure FP _L, to terminate this subroutine control. On the other hand, if it is determined in step s3 that the current engine speed is in the operating range exceeding the threshold value nα, step s3
Go to 4,5. Here, in the operation range of the high-rotation of the current operating region is above a threshold value n [alpha, regarded as the fuel pressure in the delivery pipe 3 is close to the high rotation fuel pressure FP _H, the injection amount per unit time is relatively large Then, an injection time width correction value corresponding to the current engine speed and accelerator opening is read from an injection correction value calculation map (not shown). Note that this injection correction value may be set as a constant value in an operation range on the high rotation side. Next, the current injection time width value calculated in a fuel injection amount calculation routine (not shown) is corrected with the current injection time width correction value, and the corrected injection time width value is transmitted to a fuel injection drive routine (not shown). The current fuel injection is executed based on the data.

By this injection time width correction processing, the delivery
The fuel pressure of the pipe 3 is low rotation fuel pressure FP _LAs in the fuel
The injection time width is calculated and the injection control is performed.
The shift range is changed to the high rotation side exceeding the threshold value nα,
Diversion fuel pressure FP_HOf fuel is injected from each injector 2
The fuel pressure FP for high rotation_HSuitable for
Injection processing is performed. Thus, the cylinder part 29
The oil pressure (fuel pressure adjustment pressure) of the upper space e1 (fuel pressure adjustment chamber)
Force) to adjust the fuel pressure variably and use a relatively simple structure
To obtain the optimal fuel pressure for the operating condition and low cost
It is easy to plan. Furthermore, the upper space e1 is different from the fuel
By variably adjusting the fuel pressure in response to the oil pressure,
It can improve safety, high durability and reliability, and
The high pressure regulator 18 (pressure regulating mechanism) is located downstream of the pump.
Therefore, the controllability is also excellent. Further, the upper space e1
(Fuel pressure adjustment chamber) boosts hydraulic pressure introduced into the same chamber by piston boosting
Adjust the biasing force of the spring 27 after boosting using the mechanism
This means that the booster mechanism uses relatively low oil pressure to
Pressure control can be performed.

FIGS. 5 and 6 show modifications of the embodiment of FIG. The fuel supply device A1 for an internal combustion engine is different from the fuel supply device A for an internal combustion engine in FIG.
An oil control valve 43, which is an ON-OFF valve, is provided in the middle of the oil pipe 35 reaching the upper space e1 of the cylinder portion 292 from the position 6, and the valve is controlled by a controller (ECU).
The difference is that the switching control is performed by 10a, and the other parts have the same configuration as that of the internal combustion engine fuel supply device A of FIG. 1, and redundant description is omitted here. The controller (ECU) 10a takes in the engine speed and the accelerator opening degree θa as a load, and based on an operation range map ma shown in FIG. 6B, a low fuel pressure range (low rotation fuel pressure F
P _L ) or the high fuel pressure range (high rotation fuel pressure FP _H ). In addition, when the current operation range is the low fuel pressure range, the output to the oil control valve 43 is kept off, the space between the main gallery 36 and the oil pipe 35 is shut off, the oil pressure in the upper space e1 is reduced, and the piston 31 At the upper end position H1,
Each of the spring seats 28 is supported at the upper end position h1, and a relatively low low-rotation pressing force Ps1 (shown as Ps in the drawing) is applied to the plunger 24, and the plunger 24 performs a pressure adjusting operation with the pressing force Ps1. Relatively low low rotation fuel pressure F
The fuel pressure on the delivery pipe 3 side is held at P _L (indicated as Low in FIG. 6A).

On the other hand, if the controller (ECU) 10a determines that the current operating range is the high fuel pressure range, it keeps the output to the oil control valve 43 on to make the main gallery 36 and the oil pipe 35 communicate with each other. , Upper space e
1 and raise the piston 31 to the upper end position H1,
The spring seats 28 are supported at the upper end positions h1, respectively, and a relatively high high-rotation pressing force Ps2 (see Ps in FIG. 1) is applied to the plunger 24, and the plunger 24 is regulated by the pressing force Ps2 to be relatively high. Fuel pressure FP _L for high rotation
(High shown in FIG. 6A) holds the fuel pressure on the secondary fuel pipe 5 and the delivery pipe 3 side.

This controller (ECU) 10a executes the subroutine of FIG. 4 in the same manner as the apparatus of FIG. Also in this case, if the current operation range is in the low fuel pressure range (low-pressure fuel pressure FP _L ) and is regarded as a normal fuel injection control range, no correction processing is performed, and the current engine speed is changed to the high fuel pressure range (high If the fuel pressure is FP _H ), the injection amount per unit time is considered to be relatively large, and the injection time width correction value corresponding to the current engine speed and accelerator opening is read from an injection correction value calculation map (not shown). Then, the current injection time width value calculated in a fuel injection amount calculation routine (not shown) is corrected with the current injection time width correction value, and the corrected injection time width value is transmitted to a fuel injection drive routine (not shown). The current fuel injection is executed based on the data.

The fuel supply system A1 for the internal combustion engine has the same operation and effect as the fuel supply system A for the internal combustion engine in FIG.
In particular, the degree of freedom in setting the operating range is increased, and more precise fuel pressure switching control can be executed. 7 and 8 show another embodiment. The fuel supply device A2 for the internal combustion engine differs from the fuel supply device A for the internal combustion engine in FIG. 1 in the vicinity of the piston 31b of the high-pressure regulator 18b and the oil control valve 45 as an electric control valve of a hydraulic control system. However, the other parts have the same configuration, and redundant description is omitted here.

When the fixing plug 23 is tightened to the cylinder head 19, the cylindrical main body 22 and the plunger sheet 20 are fixed to the back side thereof. The plunger 24, a spring 27 for urging the plunger downward, and a piston rod 32b having a spring receiving portion with which the upper end of the spring abuts are fitted into the cylindrical main body 22. The upper end of the piston rod 32b is enlarged in diameter to integrally form a piston 31b, and the piston is slidably fitted into a space covered by a cylinder cover 47 fixed to the cylinder head 19 and a cylinder portion. The space is vertically divided by a piston 31b. The upper space e1 and the lower space e2 communicate with upper and lower ports g1 and g2, and these ports communicate with the valve chamber h of the oil control valve 45. Note that reference numeral 4
Reference numeral 9 denotes a screw positioned at a reference position (a position indicated by a solid line) of the piston 31b. The oil control valve 45, which is an electric control valve, includes a solenoid 451, a movable iron core 452, and a valve body 453 extending from the movable iron core and housed in the valve chamber h.

When the valve body 453 is located at the low pressure position E1 (the position in FIG. 8A) at the lower end of the valve chamber h, the upper space e1
From the upper port g1 and the drain port g3 to the low pressure oil pipe 44 and the oil tank 37, and the lower space e2 from the lower port g2, the high pressure port g4 and the oil pipe 35 to the main gallery 36. When the valve body 453 is located at the high pressure position E2 (the position in FIG. 8B) at the upper end of the valve chamber, the upper space e1 is connected to the upper port g1, the high pressure port g4, and the oil pipe 35.
The lower space e2 communicates with the lower gallery g2 from the lower port e2, and the low-pressure oil pipe 44 from the drain port g3.
It communicates with the oil tank 37. Further, when the valve body 453 is held at a neutral position (not shown) between the low pressure position E1 and the high pressure position E2, the upper port g1 of the upper space e1 and the lower port g2 of the lower space e2 are connected to the drain port g3 and the high pressure. It can be completely disconnected from the port g4.

The solenoid 451 is connected to a controller (EC
U) The duty is controlled by 10b, and at this time, the hydraulic pressure difference between the upper space e1 and the lower space e2 can be variably adjusted, and the positions of the piston 31b and the piston rod 32b, that is, the compression amount of the spring 27 can be variably adjusted. Thus, the adjustment value of the fuel pressure of the plunger (adjustment member) 24 can be variably controlled. The controller (ECU) 10b takes in the engine speed, the accelerator opening θa and the fuel pressure as the load, determines the current operating range, and determines the appropriate fuel pressure in this operating range on the operating range map shown in FIG. mb,
The duty control of the position of the oil control valve 45 is performed so that the target fuel pressure matches the current fuel pressure.

This controller (ECU) 10b is also shown in FIG.
As in the case of the apparatus described above, a subroutine similar to the subroutine of FIG.
Also in this case, the current operating range is the low fuel pressure range (low-speed fuel pressure F
P _L) is in i1 and regarded as normal fuel injection control area without the correction process, the high fuel pressure region other than the current operation range is a low rotation fuel pressure FP _L i2 to i5 (high rotation fuel pressure FP _H) Then, the process proceeds to the injection time width correction mode. In this case, it is determined which of the high fuel pressure ranges i2 to i5 corresponds to the operating range according to the current engine speed and the accelerator opening, and the injection time width correction value in the corresponding high fuel pressure range is not shown in the injection correction. The current injection time width value read from the value calculation map and then calculated in a fuel injection amount calculation routine (not shown) is corrected with the current injection time width correction value, and the corrected injection time width value is used as a fuel injection drive (not shown). This is transmitted to the routine side, and the current fuel injection is executed based on the data.

The fuel supply system A2 for the internal combustion engine also has the same function and effect as the fuel supply system A for the internal combustion engine in FIG.
In particular, since the duty control can be performed, the fuel pressure can be continuously variably controlled, the degree of freedom of the fuel pressure adjustment increases, and it is possible to execute more detailed fuel pressure switching control. Further, since the biasing force of the spring 27 is adjusted using the hydraulic booster, high fuel pressure control can be performed using relatively low hydraulic pressure, and the oil control valve 45 can be reduced in size and power consumption can be reduced.
Controllability is improved. Each of the above-described fuel supply devices A to A2 for the internal combustion engine in FIGS. 1, 5, and 8 has a hydraulic piston type hydraulic booster, and the fuel pressure is variably set using the high pressure regulators 18 and 18b. Instead, the fuel supply device A3 for the internal combustion engine may be configured using a high pressure regulator driven by a supercharging pressure as shown in FIG. In this case, the high-pressure regulator 50 uses the supercharging pressure or the exhaust pressure (exhaust positive pressure) T of the exhaust system as the fuel pressure adjusting pressure, and
Except for the point that the structure 2 is different from that of the high-pressure regulator 18 in FIG. 1, there are many identical components, and a repeated description is omitted here.

A high pressure regulator 50 driven by a supercharging pressure as shown in FIG. 10 has a fixed plug 23 which is fastened to the cylinder head 19, and the cylindrical main body 22 and the plunger sheet 20 are fixed to the back side thereof. The fixing plug 23 supports the cylinder portion 292c, and the cylinder portion 292c has the cover 30c fixed to the upper end, which is the open end thereof, and the diaphragm 52 is sandwiched between both peripheral flanges. The central portion of the diaphragm 52 is connected to the upper end of the piston rod 32c slidably supported by the support portion 291c. The lower end of the piston rod 32c is formed so as to protrude below the lower end of the support portion 291c by a set amount t (see FIG. 2),
It comes into contact with the spring seat 28. An upper space e1 between the cover 30c and the diaphragm 52 is connected to a positive pressure introducing section (not shown) through a positive pressure pipe 53 connected to the cover 30c, where a supercharger pressure in the intake system or a discharge pressure (exhaust positive pressure) T in the exhaust system is not shown. T
More have been introduced. In addition, a solenoid valve 54 is provided in the middle of the positive pressure pipe 53. Solenoid valve 5
Reference numeral 4 denotes a controller (ECU)
10c, the valve body 542 communicates the upper space e1 with the atmosphere opening port 543 when the switching signal is off, and communicates with the positive pressure introducing portion T when it is on, and functions as a three-way switching valve. The lower space e2 is always open to the atmosphere.

The controller 10c used by the fuel supply system A3 for the internal combustion engine shown in FIG. 10 is configured so that the positive pressure rotation speed np (FIG. 11)
(Refer to the operation range map mc in (b)), the solenoid valve 54 is turned off before the positive pressure rotation speed np is detected, and the spring seat 28 is supported at the upper end position h1.
At this time, the spring 27 adjusts the pressure of the plunger 24 with a relatively low pressing force Ps1 (indicated as Ps in FIG. 10), and a relatively low fuel pressure FP _L for low rotation (shown as Low in FIG. 11A). ) Holds the fuel pressure on the delivery pipe 3 side. on the other hand,
When the controller 10c detects the positive pressure rotation speed np, the solenoid valve 54 is switched from off to on, and the operating pressure, which has been made positive by supercharging, switches the spring seat 28 to the lower end position h2 via the diaphragm 52, and is relatively high. The pressure of the plunger 24 is adjusted by the pressing force Ps2, and the relatively high fuel pressure FP _H for high rotation (FIG. 11A shows Hig
h), the fuel pressure on the delivery pipe 3 side is maintained.

The controller 10c of FIG. 10 has the same low-speed fuel pressure FP as that of the controller 10 of FIG.
_{In L} , no correction processing is performed, and the current operating range is the fuel pressure F for high rotation.
If it is P _H, the process proceeds to the mode of injection time width correction, corrects the current injection time width value that is computed by the fuel injection amount calculation routine (not shown), the current fuel injection based on the corrected injection time width value Be executed.

The fuel supply system A3 for the internal combustion engine has the same function and effect as the fuel supply system A for the internal combustion engine in FIG.
In particular, since the diaphragm type high pressure regulator 50 is used instead of the hydraulic piston type high pressure regulator 18,
The cost can be easily reduced as compared with the case where a hydraulic pipe system such as a hydraulic system is provided.

The diaphragm type high pressure regulator 50 shown in FIG. 10 is a positive pressure drive type using a supercharging pressure.
Instead, negative pressure driven high pressure regulators 50d and 50e as shown in FIGS. 12 (a) and 12 (b) may be used. In the case of FIG. 12A, the diaphragm 52 and the cover 3
The upper space e1 between 0d is opened to the atmosphere, and the lower space e2 is connected to the negative pressure source (negative pressure tank or intake hold) through the negative pressure pipe 55. In the case of FIG. 12B, a return spring 58 is provided in the upper space e1 between the diaphragm 52 and the cover 30d, and the lower space e2 is opened to the atmosphere. Moreover,
The upper space e1 is connected to a negative pressure source (a negative pressure tank or an intake manifold) 56 via a negative pressure pipe 59. Further, the negative pressure pipes 55 and 59 shown in FIGS. 12A and 12B are also provided with a solenoid valve 57 in the middle thereof. FIG.
The solenoid 571 of the solenoid valve 57 shown in FIG. 7A is connected to the controller 10d. The valve 572 communicates the lower space e2 with the atmosphere opening port 573 when the switching signal is off, and communicates with the negative pressure tank 56 when it is on. Functions as a switching valve. The solenoid portion 571 of the solenoid valve 57 shown in FIG. 12B is connected to the controller 10e. The valve body 572 communicates the upper space e1 with the atmosphere opening port 573 when the switching signal is off, and communicates with the negative pressure tank 56 when it is on. Functions as a three-way switching valve.

The high-pressure regulator 50d shown in FIG. 12 (a) projects the spring seat 28 (see FIG. 2) downward through the piston rod 32d and holds the spring seat 28 at the lower end position h2 when the lower space e2 is made negative. Low fuel pressure F
It is possible to perform pressure regulation of the high rotation fuel pressure FP _H than P _L. The high-pressure regulator 50d shown in FIG. 12B projects the spring seat 28 (see FIG. 2) downward through the piston rod 32e by the spring force when the upper space e1 is switched from the negative pressure state to the atmospheric release state, and the lower end position is set. held in h2, thereby the fuel pressure for high rotation than the low rotation fuel pressure FP _L F
It is possible to perform pressure adjustment to the P _H. When the high-pressure regulators 50d and 50e shown in FIGS. 12A and 12B are used instead of the high-pressure regulator 50 shown in FIG. 10, the same effect can be obtained by the internal combustion engine fuel supply device A3.

[0040]

As described above, according to the first aspect of the present invention, the fuel pressure can be variably adjusted by the fuel pressure adjusting pressure of the fuel pressure adjusting chamber, and the optimum fuel pressure can be obtained in an operating state using a relatively simple structure. It is easy to reduce costs. Furthermore, the fuel pressure adjustment chamber receives the pressure for adjusting the fuel pressure different from the fuel and variably adjusts the fuel pressure, thereby improving the safety, high durability and reliability of the device itself, and furthermore, the pressure adjustment mechanism is improved. Because it is downstream of the pump, it has excellent controllability.

According to the second aspect of the present invention, since a discharge pressure from an oil pump or an air pressure of intake or exhaust of the internal combustion engine is used, a simple structure can be adopted, and the fuel pressure can be variably adjusted according to the rotation speed of the internal combustion engine. In addition, safety, high durability and reliability of the device itself can be further improved.

According to the third aspect of the present invention, since the electric control valve is used, electronic control can be performed so that an optimal fuel pressure can be obtained according to the operating state, and more precise control can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a fuel supply device for an internal combustion engine as one embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a high-pressure regulator used in the fuel supply device for an internal combustion engine of FIG.

FIG. 3 is a diagram illustrating a fuel pressure adjusting function of the high-pressure regulator of FIG. 1;

FIG. 4 is a block diagram of a subroutine showing a fuel injection amount correction process used by the fuel supply device for an internal combustion engine of FIG. 1;

FIG. 5 is a schematic configuration diagram of a fuel supply device for an internal combustion engine as another embodiment of the present invention.

FIG. 6 is an explanatory diagram of fuel pressure control used in the fuel supply device for an internal combustion engine in FIG. 5;
(B) is a diagram of a fuel pressure map for fuel pressure switching.

FIG. 7 is a schematic configuration diagram of a main part of a fuel supply device for an internal combustion engine as another embodiment of the present invention.

8A and 8B show a high-pressure regulator used in the fuel supply device for an internal combustion engine of FIG. 7; FIG.
FIG. 7 is a partial cross-sectional view showing another mode of the switching valve in the high-pressure regulator.

9 is a diagram of a fuel pressure switching operation range map used by the internal combustion engine fuel supply device of FIG. 7;

FIG. 10 is a cross-sectional view of a high-pressure regulator used in a fuel supply device for an internal combustion engine as another embodiment of the present invention.

11A and 11B are explanatory diagrams of fuel pressure control of the fuel supply device for an internal combustion engine in FIG. 10, wherein FIG.
FIG. 3 is a diagram of an operating range map for switching fuel pressure.

FIG. 12 shows a main part of a diaphragm-type high-pressure regulator used in a fuel supply device for an internal combustion engine as another embodiment of the present invention, and (a) is an enlarged cross-sectional view of a main part of a first other high-pressure regulator. (B) is an enlarged sectional view of a main part of a second other high-pressure regulator.

13A illustrates a first conventional fuel supply device for an internal combustion engine, and FIG. 13B illustrates a second conventional fuel supply device for an internal combustion engine.

[Explanation of symbols]

 Reference Signs List 1 engine 2 fuel injection valve 5 secondary fuel pipe 6 primary fuel pipe 7 fuel tank 13 high pressure pump 18 high pressure regulator (pressure regulating mechanism) 19 cylinder head 24 plunger (adjusting member) 27 spring (biasing member) a inflow port ( 1st port) b Outflow port (2nd port) e1 Upper space e2 Lower space A Fuel supply device for internal combustion engine

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F02M 69/00 340 F02M 69/00 340Q

Claims (3)

[Claims] 1. A fuel passage connecting a fuel tank and a fuel injection valve provided in an internal combustion engine, a fuel pump provided in the fuel passage and driven by the internal combustion engine, and a discharge from the fuel pump. A fuel supply device for an internal combustion engine, comprising: a first port through which fuel is introduced; a second port through which excess fuel is discharged; and a second port through which excess fuel is discharged. An adjusting member for adjusting a fuel pressure by switching a communication state between the first port and the second port; an urging member for urging the adjusting member in a direction to close the second port; A fuel supply apparatus for an internal combustion engine, comprising: a fuel pressure adjustment chamber into which a fuel pressure adjustment pressure for adjusting an urging force is introduced. 2. The fuel supply device for an internal combustion engine according to claim 1, wherein the fuel pressure adjusting chamber includes any one of a discharge pressure from an oil pump driven by the internal combustion engine, and an air pressure of intake air or exhaust air of the internal combustion engine. Wherein the pressure is introduced as the fuel adjustment pressure. 3. The fuel supply device for an internal combustion engine according to claim 1, further comprising: a passage for introducing the pressure into the fuel pressure adjustment chamber; and an electric system disposed in the passage and controlled in accordance with an operation state of the vehicle. A fuel supply device for an internal combustion engine, comprising: a control valve.