JPH1150933A - Accumulator fuel injection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an accumulator fuel injection system that is able to reduce an amount of watt consumption, and also high in reliability. SOLUTION: In an accumulator fuel injection system 3, high pressure fuel to be supplied out of a fuel feed pump 9 is forcibly fed to an accumulator 11 by way of a high pressure passage 17 for pressure accumulation. In this high pressure passage 17, a solenoid control valve 25 is opened or closed in response to a control signal of a controller 39, whereby a fuel supply quantity to be forcibly fed to the accumulator 11 is controlled. Thus, since a fuel quantity to be forcibly fed to the accumulator 11 is controlled by opening or closing the solenoid control valve 25, the degree of freedom in operating conditions is high enough and operation is made possible to be done under the most efficient condition in this fuel feed pump, so that watt consumption is thus reducible, and also reliability is improvable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-accumulation type fuel injection device for pumping fuel from a motor-driven fuel supply pump to a pressure accumulator and injecting fuel into an internal combustion engine by a fuel injection valve of the pressure accumulator.

[0002]

2. Description of the Related Art For example, a direct injection type internal combustion engine for directly injecting gasoline fuel into a combustion chamber of a gasoline engine is known. In a fuel injection device used for this type of internal combustion engine,
Fuel is pumped from a fuel supply pump to an accumulator, and after accumulating pressure in the accumulator, fuel is injected into the internal combustion engine by a fuel injection valve.

[0003] As the fuel supply pump, there are a fuel supply pump connected to a drive shaft of an internal combustion engine to drive the pump and a so-called motor-driven fuel supply pump driven by a motor.

[0004] As the former, a pressure accumulating type fuel injection device having a pump driven by a drive shaft of an internal combustion engine, as disclosed in Japanese Patent Application Laid-Open No. 7-72512, high pressure fuel is fed from a fuel pump to a pressure accumulator. There is a configuration in which a fuel overflow pipe returning to a fuel tank is provided between a fuel pump and an accumulator, and excess fuel is returned by the fuel overflow pipe. That is, in the pump of the drive shaft type, since a constant rotation of the drive shaft cannot be obtained, the pressure control of the fuel discharged from the fuel pump cannot be performed. Therefore, the pressure control is performed by opening and closing the solenoid valve.

On the other hand, in the latter motor-driven fuel supply pump, which is driven by a motor, the discharge amount (or discharge pressure) can be controlled by controlling the rotation speed of the motor. It can be done easily and there is little waste of power.

As shown in FIG. 4, a conventional pressure-accumulation type fuel injection device equipped with such a motor-driven fuel supply pump has a motor-driven high-pressure pump 109 from a fuel tank 105 by a feed pump (low-pressure pump) 107. Is supplied to the common rail (pressure accumulator) 111, and the fuel in the common rail 111 is supplied from an injector (injection valve) 135 connected to the common rail to each cylinder of the engine. It is gushing. Each injector 135 has an IDU (injector drive unit) 137 according to the engine speed and load.
Is controlled through. On the rear end side of the common rail 111, a recirculation circuit 121 is formed which goes to the fuel tank 105 via the orifice 113.
A part of the high-pressure fuel in 1 is returned from the recirculation circuit 121 to the fuel tank 105. The fuel pressure is controlled by receiving a signal from a pressure sensor 141 attached to the common rail 111,
The rotation speed of the motor 131 of the high-pressure pump 109 is controlled via the PDU (pressure control unit) 150 so that the CU (electronic control unit) 139 has the target fuel pressure.

[0007]

However, in the fuel injection device (fuel injection system) equipped with the above-described motor-driven high-pressure pump, if the amount of fuel recirculated from the recirculation circuit is too large, unnecessary power is consumed. There is a disadvantage of consumption. On the other hand, when the amount of recirculation is small, problems such as a rise in the temperature of the high-pressure fuel in the common rail, a non-uniform temperature distribution, and the incorporation of air occur, and the amount of fuel injected from the injector becomes unstable. .

Further, when the vehicle is driven at a low load or idling,
When the fuel consumption of the engine is small, the high-pressure pump is driven at a low rotational speed at which boundary lubrication is performed. Therefore, the driving torque of the high-pressure pump increases, and the power consumption increases.

Further, in a transient state in which the engine load suddenly changes, for example, when an engine brake is used, the rotation speed of the drive motor cannot be changed abruptly, so that a large pressure change occurs and the fuel piping system is changed. There is an inconvenience that the durability and reliability of the device are reduced.

That is, in the conventional fuel injection device equipped with the motor-driven fuel supply pump, the power consumption is high and the reliability is not sufficient.

SUMMARY OF THE INVENTION An object of the present invention is to provide a pressure-accumulation type fuel injection device which can reduce power consumption and has high reliability.

[0012]

In order to achieve the above object, according to the first aspect of the present invention, a fuel is pumped from a motor drive type fuel supply pump to a pressure accumulator through a high pressure passage, and the fuel is supplied to the pressure accumulator. In a pressure accumulating fuel injection device that injects fuel into an internal combustion engine by a provided fuel injection valve, one end communicates with the high-pressure passage, and the other end communicates with the low-pressure side of the device. And a control device for controlling the opening and closing of the electromagnetic control valve.

According to the first aspect of the present invention, the high-pressure fuel supplied from the fuel supply pump is pressure-fed to the accumulator through the high-pressure passage to be accumulated. In the high-pressure passage, the electromagnetic control valve is opened and closed in response to a control signal from the control device to control the amount of fuel supplied to the pressure accumulator. As described above, since the amount of pressure feeding to the pressure accumulator is controlled by opening and closing the electromagnetic control valve, the fuel supply pump has a high degree of freedom in operating conditions,
Operation can be performed under the most efficient conditions, and power consumption can be reduced and reliability can be improved. In particular, the durability and reliability of the fuel supply pump can be improved by operating the fuel supply pump so as not to perform low-speed operation of boundary lubrication by controlling the pumping amount by opening and closing the electromagnetic control valve. Further, according to the opening / closing control of the electromagnetic control valve, it is possible to easily respond to a sudden load change, so that the durability and reliability of the fuel circuit are improved. Furthermore, by combining the two controls of the number of rotations of the motor and the electromagnetic control valve, a fine and wide range of control can be performed,
The amount refluxed to the fuel tank can be adjusted to an appropriate amount.

According to a second aspect of the present invention, in the first aspect of the present invention, the high-pressure passage includes a one-way valve for permitting only the flow of fuel from the fuel supply pump to the accumulator, and One end of the passage is communicated between the one-way valve and the fuel supply pump.

According to the second aspect of the present invention, the one-way valve prohibits the flow of fuel from the accumulator toward the high pressure passage, so that when the electromagnetic control valve is opened, the fuel in the accumulator is inhibited. Prevents the pressure from dropping due to backflow. Therefore, even when the electromagnetic control valve is opened, the pressure in the accumulator can be maintained, energy can be prevented from being wasted, and efficient operation can be performed.

The third aspect of the present invention is the first or second aspect.
In the invention described in (1), the control device opens and closes the electromagnetic control valve in synchronization with the pressure feeding timing of a fuel supply pump.

According to the third aspect of the present invention, the electromagnetic control valve controls the fuel pumped to the pressure accumulator by opening and closing in synchronization with the pumping timing of the fuel supply pump.

The invention described in claim 4 is the first to third aspects of the present invention.
In the invention according to any one of the above, the fuel supply pump is characterized in that, when the operation of the internal combustion engine is in a normal range, a motor that drives the fuel supply pump is controlled at a constant speed. Is what you do.

According to the fourth aspect of the present invention, since the motor drive is controlled at a constant rotation speed, the power consumption of the motor can be reduced, and the durability and reliability are improved.

The invention described in claim 5 is the invention according to claims 1 to 3
In the invention described in any one of the above, when the operation of the internal combustion engine is in a normal range, the motor for driving the fuel supply pump is driven at a constant voltage. Things.

According to the fifth aspect of the present invention, since the motor drive is controlled to a constant voltage, the power consumption of the motor can be reduced, and the durability and reliability are improved.

[0022]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 and FIG.
The first embodiment of the present invention will be described in detail with reference to FIG.
The accumulator-type fuel injection device 3 according to the embodiment of the present invention includes:
The gasoline engine directly injects gasoline into the combustion chamber (cylinder) of the gasoline engine, and is a so-called direct injection gasoline engine.

The accumulator type fuel injection device 3 generally includes a fuel tank 5, a low pressure pump (feed pump) 7 for supplying fuel to the fuel tank 5, a motor driven high pressure pump 9,
A circuit is configured by connecting a common rail 11, an orifice 13, and a low-pressure regulator 15 as an accumulator for accumulating the fuel pressure-fed from the high-pressure pump 9. The high-pressure passage 1 between the high-pressure pump 9 and the common rail 11
7 and a low-pressure passage (recirculation circuit) 21 downstream of the orifice 13 are communicated by a communication passage 23. The communication of the communication passage 23 is controlled by opening and closing an electromagnetic control valve 25. . The electromagnetic control valve 25 is an ECU which will be described later.
Opening / closing is controlled by a control signal from the ECU 39.

The low-pressure pump 7 pumps fuel (gasoline) in the fuel tank 5 to the high-pressure pump 9, and a filter 27 is interposed between the low-pressure pump 7 and the high-pressure pump 9.
This low pressure pump is driven by a motor 29.

The high-pressure pump 9 pressurizes the fuel supplied from the low-pressure pump 7 to a high pressure. The high-pressure pump 9 pressurizes the fuel to a high pressure and sends it to the common rail 11 through a high-pressure passage 17. The high-pressure pump 9 is of a motor drive type driven by a motor 31, and pumps fuel by driving the motor. The high-pressure pump 9 may be of a variable fuel pressure or a constant fuel pressure. In the present embodiment, the high-pressure pump 9 has a constant fuel pressure. The high-pressure pump 9 is provided with a return passage 33 connected to the low-pressure passage 21 so that fuel leaking from the high-pressure pump 9 or cooling fuel is returned to the low-pressure passage 21.

A plurality of injectors (injection valves) 35 are connected to the common rail 11.
The fuel stored at a high pressure is injected from each injector 35 into an internal combustion engine (not shown). The ejection of each of these injectors 35 is controlled via an IDU 37. The IDU 37 is connected to an ECU 39 as a control device described later, and is driven by a drive signal of the electronic control unit 39.

A pressure detector 41 is connected to the common rail 11 so that a pressure detection signal is sent to the ECU 37. When receiving the pressure detection signal from the pressure detector 41, the ECU 39 controls the electromagnetic control valve 25 so that the pressure in the common rail 9 becomes the target pressure, and controls the drive of the IDU 37 according to the detected pressure. .

In the high-pressure passage 17 provided between the high-pressure pump 9 and the common rail 11, a one-way valve 43 is provided to permit only the flow of fuel from the high-pressure pump 9 to the common rail 11. The flow from to the common rail 11 is prohibited. Thus, by providing the one-way valve 43, when the electromagnetic control valve 25 is opened, the backflow is prohibited and the pressure in the common rail 11 is prevented from lowering.

The low-pressure passage 21 is a passage that returns from the downstream side of the orifice 13 to the fuel tank 5. This low pressure passage 21
A low-pressure regulator 45 is provided downstream of the communication path between the communication path 23 and the return path 33.

Next, the operation of the present embodiment will be described. During operation of the fuel injection pump, the fuel in the fuel tank 5 is supplied from the low-pressure pump 7 to the high-pressure pump 9 and is supplied to the high-pressure pump 9.
After the high-pressure fuel is pumped into the high-pressure passage 17 and the amount of pumping is controlled by opening and closing the electromagnetic control valve 25, the one-way valve 43
The fuel is accumulated in the common rail 11 and fuel is ejected from each injector 35 of the common rail 11.

The ECU 37 controls the fuel pressure to be fed to the common rail 11 according to the detection signal received from the pressure detector 41 so that the fuel pressure in the common rail 11 becomes the target pressure. , Electromagnetic control valve 2
5 is controlled by opening and closing.

The high-pressure pump 9 is driven by a motor 31 and controls the fuel pressure discharged from the high-pressure pump 9 by the rotation of the motor 31. The number of rotations of the motor 31 can be easily controlled by changing the voltage. . Further, the voltage may be kept constant and the number of revolutions of the motor 31 may be kept constant.

In the communication passage 23 communicating with the high-pressure passage 17,
The electromagnetic control valve 25 is opened and closed in response to a control signal from the ECU 39 to control fuel to be pumped to the common rail 11. In other words, the amount of fuel discharged under pressure to the common rail 11 via the high-pressure passage 17 is controlled. In this case, when the electromagnetic control valve 25 is opened and fuel escapes from the communication passage 23 to the low pressure side, the one-way valve 43 prohibits the fuel pressure of the common rail 11 from escaping. At the time of opening, the fuel pressure in the common rail 11 is prevented from dropping,
Energy is wasted and driving efficiency is increased. The fuel recirculated from the communication passage 23 is returned to the fuel tank 5 via the low-pressure passage 21 and the low-pressure regulator 45.

As described above, in the present embodiment, since the amount of pressure to be fed to the common rail 11 is controlled by opening and closing the electromagnetic control valve 25, the degree of freedom in operating conditions of the high-pressure pump 9 is high, and the motor 31 As shown in FIG. 2, operation can be performed under the most efficient conditions, and power consumption can be reduced and reliability can be increased. That is, FIG. 2 is a graph showing the relationship between the rotational speed of the motor 31 in the high-pressure pump 31 and the operating efficiency. The motor 31 is driven in the rotational speed range A where the operating efficiency is excellent, and the common rail 11 is driven. The amount of fuel to be pumped is adjusted by opening and closing the electromagnetic control valve 25.

For example, a normally open electromagnetic control valve 2
In No. 5, if the energizing time is shortened, the motor rotation speed can be set high, the torque in the high-pressure pump 9 can be reduced, and the reliability can be improved. On the other hand, if the energization time of the electromagnetic control valve 25 is lengthened, the motor speed can be set small, and the power consumption can be reduced. Therefore, from the relationship between the power consumption of the motor and the power consumption due to the energization of the electromagnetic control valve, it is possible to operate under the condition that the power consumption is minimized.

In particular, when the operation of the internal combustion engine is in the normal range, if the rotation speed of the motor 31 is kept constant, the motor 31
Power consumption can be reduced, and pressure fluctuations in the fuel circuit are small, so that the durability and reliability of the fuel circuit are improved. Also, when the operation of the internal combustion engine is in the normal range,
The motor 31 may be driven at a constant voltage. Also in this case, since the motor drive is controlled to a constant voltage, power consumption of the motor 31 can be reduced, and pressure fluctuation in the fuel circuit is small, so that durability and reliability in the fuel circuit are improved.

On the other hand, if the high-pressure pump 9 is operated at a low rotational speed for boundary lubrication, the operating efficiency is poor, and parts are worn and noise is generated. By driving the motor 3, the durability and reliability of the high-pressure pump are improved. Further, the number of rotations of the motor 31 and the electromagnetic control valve 25
By controlling the fuel pumping amount by combining the two controls, a fine and wide range of control can be performed, and the durability and reliability are improved.

When the engine load suddenly changes due to engine braking or the like, it is difficult to rapidly change the rotation speed of the motor 31.
, The amount of fuel pumped can be easily varied in response to a sudden load. In this case, the electromagnetic control valve can respond instantaneously, so that the response is good.
Regarding responsiveness, normally open electromagnetic control valve 25
Then, if the energization time is shortened, the amount of fuel to be pumped decreases,
If the energization time is lengthened, the amount of fuel to be pumped increases, so
By controlling the amount of fuel to be pressure-fed to the common rail 11 by the electromagnetic control valve 25, the response is quick and it is possible to respond instantaneously to a load change.

As described above, by responding to a sudden change in load, the reliability of each fuel pipe can be improved.

Next, another embodiment of the present invention will be described. The same reference numerals are given to the same portions as those in the above-described first embodiment, and the detailed description of the portions will be omitted. .

In the second embodiment shown in FIG. 3, the rotational position detector 4 is mounted on the motor 31 of the high-pressure pump 9 or on the pump itself.
7 is incorporated or connected, and controls the electromagnetic control valve 25 in synchronization with the detected rotational position signal. In the second embodiment, the same effects as those in the first embodiment can be obtained. In addition, the electromagnetic control valve 25 controls the opening and closing in synchronization with the pumping timing of the fuel supply pump 9. Good response to pressure fluctuation.

The present invention is not limited to the above-described embodiment, but can be variously modified without departing from the gist of the invention. For example, the present invention is not limited to providing the orifice on the downstream side of the common rail, and the downstream side of the common rail may be a closed circuit, and the high-pressure passage 17 may be provided with an accumulator or the like.

Further, the present invention is not limited to the direct injection type gasoline engine, and the same effect can be obtained even when used in a fuel injection device of a diesel engine.

[0044]

According to the first aspect of the present invention, the fuel supply pump is controlled by opening and closing the electromagnetic control valve to control the fuel to be pumped from the fuel supply pump to the accumulator.
The degree of freedom in operating conditions is high, and operation can be performed under the most efficient conditions, so that power consumption can be reduced and reliability can be improved.

According to the second aspect of the present invention, since the one-way valve is provided in the high-pressure passage, it is possible to prevent the fuel pressure of the accumulator from decreasing when the electromagnetic control valve is opened.
This prevents waste of energy and enables efficient operation.

According to the third aspect of the present invention, the electromagnetic control valve is controlled to open and close in synchronization with the timing of pumping the fuel supply pump, thereby facilitating control of the fuel to be pumped.

According to the fourth aspect of the present invention, since the motor drive is controlled to a constant rotation speed, the power consumption of the motor can be reduced, and the durability and reliability are improved.

According to the fifth aspect of the present invention, since the motor drive is controlled to a constant voltage, the power consumption of the motor can be reduced, and the durability and reliability are improved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a pressure accumulating fuel injection device according to a first embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the number of rotations of a motor and efficiency.

FIG. 3 is a circuit diagram of a pressure accumulating fuel injection device according to a second embodiment of the present invention.

FIG. 4 is a circuit diagram of a conventional pressure accumulating fuel injection device.

[Explanation of symbols]

 3 Accumulation type fuel injection device 9 High pressure pump 11 Common rail (accumulator) 17 High pressure passage 23 Communication passage 25 Electromagnetic control valve 39 ECU (Control device)

Claims (5)

[Claims] 1. A pressure-accumulation type fuel injection device for pumping fuel from a motor-driven fuel supply pump to a pressure accumulator through a high-pressure passage and injecting fuel into an internal combustion engine by a fuel injection valve provided in the pressure accumulator. A communication device having one end communicating with the high-pressure passage and the other end communicating with the low-pressure side of the device; an electromagnetic control valve provided in the communication passage for opening and closing the communication passage; and a control device for controlling opening and closing of the electromagnetic control valve. And a pressure-accumulation fuel injection device. 2. The high-pressure passage includes a one-way valve for permitting only a flow of fuel from the fuel supply pump to the accumulator, and one end of the communication passage is provided between the one-way valve and the fuel supply pump. 2. The communication according to claim 1, wherein
3. An accumulator type fuel injection device according to claim 1. 3. The accumulator-type fuel injection device according to claim 1, wherein the control device opens and closes the electromagnetic control valve in synchronization with a pressure feeding timing of a fuel supply pump. 4. The fuel supply pump according to claim 1, wherein, when the operation of the internal combustion engine is in a normal range, a motor for driving the fuel supply pump is controlled at a constant rotational speed. The pressure accumulating fuel injection device according to any one of claims 1 to 7. 5. The fuel supply pump according to claim 1, wherein when the operation of the internal combustion engine is in a normal range, a motor for driving the fuel supply pump is driven at a constant voltage. An accumulator-type fuel injection device according to any one of the preceding claims.