JP2005256735A - Fuel injection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection apparatus 1 capable of reducing the useless supply of fuel by an electric type low pressure pump 5 and reducing the power consumption of an electric motor for driving the low pressure pump 5. <P>SOLUTION: A control means 6 of the fuel injection apparatus 1 controls the supply quantity of fuel by the low pressure pump 5 by adjusting the current flowing quantity to the electric motor 3 according to a detection signal from a common rail pressure detecting means 8. The power consumption of the electric motor 3 for driving the low pressure pump 5 can thereby be adjusted according to a force-feed quantity by a high pressure pump 2. As a result, power consumption at the electric motor 3 can be reduced, and the useless supply of fuel by the low pressure pump 5 can be reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel injection device that injects and supplies fuel to an engine, and more particularly to a fuel injection device that pumps fuel from a fuel tank by an electric actuator (for example, an electric motor).

[Conventional technology]
2. Description of the Related Art Conventionally, a fuel injection device that injects and supplies fuel to an engine includes a high-pressure pump that increases the pressure of the fuel and supplies the engine to the engine via an injection valve, and a low-pressure pump that pumps fuel from a fuel tank and supplies the fuel to the high-pressure pump. I have. The high-pressure pump has a rotating shaft that is driven to rotate by the engine, and the rotating shaft rotates to suck in fuel supplied from the low-pressure pump, increase the pressure, and pump the fuel to the injection valve. The low-pressure pump is attached to one end of the rotary shaft of the high-pressure pump, and pumps fuel from the fuel tank and supplies it to the high-pressure pump as the rotary shaft rotates. As described above, the high-pressure pump and the low-pressure pump are driven by the engine, and supply the engine with fuel corresponding to the engine speed, that is, the fuel requirement amount of the engine.

  In recent years, instead of an engine drive system in which a high pressure pump and a low pressure pump of a fuel injection device are driven by an engine, an electric system in which the high pressure pump and the low pressure pump are driven by an electric actuator (for example, an electric motor) has been studied (for example, patent References 1 and 2). A fuel injection apparatus employing this electric system, particularly a fuel injection apparatus including an electric low-pressure pump, is more advantageous than a fuel injection apparatus including an engine-driven low-pressure pump in the following points.

First, since the engine-driven low-pressure pump cannot supply fuel in an amount higher than the engine speed, there is a risk that supply shortage occurs at a low speed immediately after the engine is started. On the other hand, since the electric low-pressure pump can supply a fixed amount of fuel regardless of the engine speed, supply shortage does not occur at low rotation immediately after engine startup.
Secondly, since the engine-driven low-pressure pump is attached to one end of the rotary shaft of the high-pressure pump, it is a separate unit for filling the fuel flow path from the fuel tank to the low-pressure pump with fuel at the time of out-of-gassing restart or shipping. Need a pump. On the other hand, the electric low-pressure pump can be mounted close to the fuel tank because the degree of freedom of the mounting position is large. For this reason, a fuel filling pump is unnecessary.

[Problems with conventional technology]
However, the conventional electric low-pressure pump needs to always supply the fuel corresponding to the maximum required amount so that the fuel supply amount does not become smaller than the fuel required amount of the engine. For this reason, the conventional electric low pressure pump is wasteful in supplying fuel and consumes a large amount of power consumed by the electric actuator. Therefore, the electric power required when starting the engine (mainly, the electric power for energizing the starter and the electric power for energizing the electric actuator for the low-pressure pump) is increased, and the alternator may need to be enlarged. is there
Japanese Patent Laid-Open No. 9-209870 JP 2000-179427 A

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to reduce waste of fuel supply by an electric low-pressure pump and to reduce power consumption of an electric actuator that drives the low-pressure pump. An object of the present invention is to provide a fuel injection device that can be reduced.

[Means of Claim 1]
According to the means of claim 1, the fuel injection device includes a high-pressure pump that increases the pressure of the fuel and supplies the fuel to the engine, a low-pressure pump that is driven by the electric actuator, pumps the fuel from the fuel tank, and supplies the fuel to the high-pressure pump; And a control means for controlling the amount of fuel supplied by the low-pressure pump by adjusting the amount of current supplied to the.
Thereby, the energization amount to the electric actuator that drives the low-pressure pump can be adjusted according to the fuel requirement amount of the engine. As a result, power consumption of the electric actuator can be reduced, and waste of fuel supply by the low pressure pump can be reduced.

[Means of claim 2]
According to the means of claim 2, the fuel injection device comprises an injection valve for injecting fuel supplied from the high-pressure pump into the engine, and the control means is an injection amount command by the injection valve calculated in response to a request from the engine. The energization amount to the electric actuator is adjusted according to the value.

[Means of claim 3]
According to the means of claim 3, the fuel injection device comprises a common rail for accumulating fuel supplied from the high pressure pump in a high pressure state, and a common rail pressure detecting means for detecting the fuel pressure of the common rail, and the control means includes the common rail pressure. The energization amount to the electric actuator is adjusted according to the detection signal from the detection means.

[Means of claim 4]
According to the means of claim 4, the fuel injection device includes a common rail for accumulating the fuel supplied from the high pressure pump in a high pressure state, a common rail pressure detecting means for detecting the fuel pressure of the common rail, and a fuel supplied from the low pressure pump. A suction metering valve for adjusting the amount of fuel sucked into the high-pressure pump, and the control means outputs a control signal for adjusting the valve opening of the suction metering valve from the common rail pressure detection means. And the amount of current supplied to the electric actuator is adjusted according to the control signal.

  The best mode fuel injection device includes a high pressure pump that supplies fuel to an engine with high pressure, a low pressure pump that is driven by an electric actuator, pumps fuel from a fuel tank and supplies the fuel to a high pressure pump, and an energization amount to the electric actuator By adjusting the fuel supply amount by the low pressure pump, a common rail for accumulating the fuel supplied from the high pressure pump in a high pressure state, and a common rail pressure detecting means for detecting the fuel pressure of the common rail, The control means adjusts the energization amount to the electric actuator according to the detection signal from the common rail pressure detection means.

[Configuration of Example 1]
The configuration of the fuel injection device 1 according to the first embodiment will be described with reference to FIG.
The fuel injection device 1 is driven by a high-pressure pump 2 that increases the pressure of fuel and supplies it to an engine (not shown) and an electric motor 3 as an electric actuator, and pumps fuel from a fuel tank 4 and supplies it to the high-pressure pump 2. A control means 6 for controlling the amount of fuel supplied by the low-pressure pump 5 by adjusting the amount of current supplied to the low-pressure pump 5 and the electric motor 3, and a common rail 7 for accumulating fuel supplied from the high-pressure pump 2 in a high-pressure state And common rail pressure detecting means 8 for detecting the fuel pressure of the common rail 7 (hereinafter referred to as common rail pressure).

  The high-pressure pump 2 injects and supplies high-pressure fuel to the engine via a common rail 7 that accumulates high-pressure fuel and an injection valve 10 (hereinafter referred to as an injector) that injects high-pressure fuel from the common rail 7 into the engine. The high-pressure pump 2 includes a cam mechanism 11 driven by an engine and a pressurizing chamber 12 that can be expanded and contracted. The high-pressure pump 2 is operated by the cam mechanism 11 to suck fuel into the pressurizing chamber 12 and feed the sucked fuel into the injector 10. A plurality of pressurizing sections 16 for pumping and an intake metering valve 17 (hereinafter referred to as SCV) for adjusting the amount of fuel sucked into the pressurizing chamber 12 out of the fuel supplied from the low pressure pump 5. .

The cam mechanism 11 is rotatably supported by bearings 18 and 19 and slidably accommodates a rotating shaft 21 that is rotationally driven by an engine, a cylindrical cam 22 that is eccentrically assembled to the rotating shaft 21, and the cam 22. The cam ring 23 is provided.
The pressurizing unit 16 is slidably accommodated in the cylinder 24 and is driven by the cam mechanism 11 in the counter-rotating shaft direction, a spring 26 that biases the plunger 25 in the rotating shaft direction, and the pressurizing chamber 12. A pressure-feed-side check valve 27 that is attached to a fuel flow path a between the common rail 7 and the common rail 7 to prevent a backflow of fuel from the common rail 7 to the pressurizing chamber 12, and a fuel between the pressurizing chamber 12 and the SCV 17 A suction-side check valve 28 that is attached to the flow path b and prevents the backflow of fuel from the pressurizing chamber 12 to the SCV 17 is provided. A plunger tappet 31 is provided at the distal end of the plunger 25 on the rotating shaft side, and is in sliding contact with a sliding surface formed on the outer periphery of the cam ring 23 by the biasing force of the spring 26.

  The pressurizing chamber 12 is formed by the inner peripheral surface of the cylinder 24, the end surface on the counter-rotating shaft side of the plunger 25, and the like. The plurality of pressure units 16 are arranged at equal angular intervals (for example, every 180 ° or 120 ° intervals) with the rotation shaft 21 as the center. The plurality of fuel flow paths a extending from the plurality of pressure-feed side check valves 27 merge into one and are connected to the common rail 7.

  The cam 22, the cam ring 23, the plunger tappet 31, and the like are accommodated in the cam chamber 32. A part of the fuel supplied from the low-pressure pump 5 is circulated and supplied to the cam chamber 32 as lubricating fuel, and seizure by sliding contact between the cam 22 and the cam ring 23 and seizure by sliding contact between the plunger tappet 31 and the cam ring 23. Is prevented. Lubricating fuel is supplied to the cam chamber 32 through the fuel flow path d branched from the fuel flow path c from the low-pressure pump 5 toward the SCV 17. A throttle 33 is disposed in the fuel flow path d, and the amount of lubrication fuel supplied is limited so as not to hinder the fuel suction into the pressurizing chamber 12. Further, the lubricating fuel supplied to the cam chamber 32 returns to the fuel tank 4 through the fuel flow path e.

  Here, the operation of the cam mechanism 11 and the pressure unit 16 will be described. When the rotating shaft 21 is driven to rotate by the engine, the cam 22 revolves around the axis of the rotating shaft 21. Thereby, when the rotating shaft 21 makes one rotation, the plunger 25 reciprocates once in the cylinder 24. That is, when the rotating shaft 21 makes one revolution, the plunger 25 is displaced from the position where the pressurizing chamber 12 becomes the maximum volume to the position where it becomes the minimum volume, for example, and is again moved to the position where it becomes the maximum volume. During this time, the plunger tappet 31 slides on the sliding surface of the cam ring 23.

  Next, fuel suction and pressure feeding accompanying the operation of the cam mechanism 11 and the pressurizing unit 16 will be described. When the volume of the pressurizing chamber 12 becomes maximum, the suction of fuel into the pressurizing chamber 12 is finished and the suction side check valve 28 is closed. At the same time, the pressure-feed side check valve 27 is opened, and the fuel pressure from the pressurizing chamber 12 is started. Then, the fuel pressure in the pressurizing chamber 12 changes in a high pressure state until the volume of the pressurizing chamber 12 becomes the minimum to the minimum, and the high-pressure fuel is pumped from the pressurizing chamber 12 to the common rail 7. When the volume of the pressurizing chamber 12 is minimized, the pumping of the high-pressure fuel from the pressurizing chamber 12 is finished, and the pumping side check valve 27 is closed. At the same time, the suction side check valve 28 is opened, and the suction of fuel into the pressurizing chamber 12 starts. Then, the fuel pressure in the pressurizing chamber 12 changes in a low pressure state until the volume of the pressurizing chamber 12 reaches the maximum, and the low pressure fuel is sucked into the pressurizing chamber 12.

  The SCV 17 adjusts the amount of fuel sucked into the pressurizing chamber 12 of the high pressure pump 2 out of the fuel supplied from the low pressure pump 5. In the SCV 17, a valve body (not shown) is driven by a magnetic force generated by energizing a solenoid (not shown). Further, the value of the energized current is duty-controlled to adjust the valve opening as will be described later. When the energization of the solenoid is stopped, the SCV 17 is fully opened or closed by a biasing force such as a spring (not shown).

  The low-pressure pump 5 is a well-known pump that pumps fuel from the fuel tank 4 and supplies it to the high-pressure pump 2 as the impeller 34 rotates. The impeller 34 of the low pressure pump 5 is driven to rotate by the electric motor 3, thereby pumping up fuel from the fuel tank 4 and supplying it to the high pressure pump 2. A fuel filter 35 is attached to the fuel flow path c from the low-pressure pump 5 toward the SCV 17 to remove foreign matters contained in the fuel. Further, surplus fuel that has not passed through the SCV 17 and the throttle 33 among the fuel supplied from the low-pressure pump 5 passes through the fuel flow path f branched from the fuel flow path d and returns to the fuel tank 4 via the cam chamber 32. . In the fuel flow path f, a pressure regulating valve 36 for allowing excess fuel to escape is disposed.

  The common rail 7 is a pressure accumulating container that accumulates fuel supplied from the high-pressure pump 2 at a common rail pressure corresponding to the injection pressure by the injector 10. The common rail 7 is connected to a plurality of injectors 10 mounted on each cylinder (not shown) of the engine by a plurality of fuel flow paths g. In the injector 10, a valve body (not shown) is driven by a magnetic force generated by energizing a solenoid (not shown) to open a valve hole (not shown), and a spring (not shown) or the like is stopped by energization. The valve body is driven by the urging force to close the valve hole. And the fuel of the common rail 7 is injected and supplied to a cylinder by opening a valve hole.

Moreover, the common rail 7 has a pressure limiter 37 for suppressing the common rail pressure to a limit pressure or less. The pressure limiter 37 operates when the common rail pressure exceeds a predetermined set value, and intermittently releases the fuel in the common rail 7 to the fuel tank 4 through the fuel flow path h until the common rail pressure is stabilized below the set value. The surplus fuel in the injector 10 returns to the fuel tank 4 through the fuel flow path i that joins the fuel flow path h. The fuel flow path e and the fuel flow path h merge to form one fuel flow path j and are connected to the fuel tank 4.
The common rail pressure detecting means 8 is a known pressure sensor attached to the common rail 7.

  The control means 6 includes a CPU for performing control processing and arithmetic processing, a storage device for storing various programs and data, an ECU 41 having a computer including an input device and an output device, and an injector drive circuit for energizing the solenoid of the injector 10 (Not shown), an SCV drive circuit (not shown) for energizing the solenoid of the SCV 17, a low pressure pump drive circuit 42 for energizing the electric motor 3 of the low pressure pump 5, and the like. The control means 6 includes an engine speed detecting means 43 for detecting a signal for measuring the engine speed, an accelerator opening detecting means 44 for detecting a signal for measuring the accelerator opening, and a common rail pressure detecting means 8. Detection signals from these are input, and various controls are executed based on these detection signals.

  For example, the control means 6 controls the fuel injection amount and injection timing to each cylinder by the injector 10 in response to requests from the engine such as the engine speed and the accelerator opening. That is, the control means 6 calculates the fuel injection amount and injection timing to each cylinder by the injector 10 in accordance with detection signals from the engine speed detection means 43 and the accelerator opening degree detection means 44. Based on the calculated injection amount command value and injection timing command value, the solenoid of the injector 10 is energized, and fuel is supplied to each cylinder by the injector 10.

  Further, the control means 6 adjusts the pumping amount (suction amount by the SCV 17) by the high-pressure pump 2 so that the common rail pressure substantially matches the injection pressure by the injector 10. That is, the control means 6 calculates the SCV drive current energized to the solenoid of the SCV 17 according to the detection signal from the common rail pressure detection means 8, and the duty ratio control signal according to the calculated SCV drive current command value. Is synthesized. Then, by this control signal, the solenoid of the SCV 17 is energized and the valve opening of the SCV 17 is adjusted. Thereby, the suction amount by the SCV 17, that is, the pumping amount by the high-pressure pump 2 is adjusted.

[Features of Example 1]
The control means 6 of the first embodiment controls the supply amount by the low-pressure pump 5 by adjusting the energization amount to the electric motor 3 according to the common rail pressure. That is, the ECU 41 measures the common rail pressure using the detection signal input from the common rail pressure detection means 8. Then, the ECU 41 calculates a motor drive current that is supplied to the electric motor 3 in accordance with the difference between the measured value and the target value of the common rail pressure. Then, the ECU 41 synthesizes a control signal having a duty ratio corresponding to the calculated motor drive current command value and outputs it to the low-pressure pump drive circuit 42. In response to this control signal, the electric motor energization transistor 45 of the low-pressure pump drive circuit 42 performs a switching operation, and a current having a value substantially equal to the motor drive current command value is energized from the battery 46 to the electric motor 3. The In this way, the number of rotations of the impeller 34 is adjusted by adjusting the energization amount to the electric motor 3, and the supply amount by the low-pressure pump 5 is controlled.

[Effect of Example 1]
The control means 6 of Example 1 controls the supply amount by the low pressure pump 5 by adjusting the energization amount to the electric motor 3 according to the measured value of the common rail pressure.
Thereby, the power consumption in the electric motor 3 that drives the low-pressure pump 5 can be adjusted according to the pumping amount by the high-pressure pump 2. As a result, as shown in FIG. 2, the power consumption W of the electric motor 3 can be reduced, and the waste of fuel supply by the low-pressure pump 5 can be reduced.
That is, the conventional low-pressure pump supplies a constant amount Q′max of fuel corresponding to the maximum pumping amount Qmax of the high-pressure pump 2 regardless of the value of the pumping amount Q of the high-pressure pump 2 as shown by the correlation line C. It was. For this reason, like the correlation line A, the power consumption W by the electric motor 3 is always constant power Wmax. However, by adjusting the energization amount to the electric motor 3 according to the common rail pressure, the power consumption W of the electric motor 3 can be adjusted according to the pressure feed amount Q by the high-pressure pump 2 like the correlation line B. Similarly, the supply amount Q ′ by the low-pressure pump 5 can be controlled according to the pumping amount Q by the high-pressure pump 2 as shown by the correlation line D.

[Modification]
Although the control means 6 of the present embodiment adjusts the energization amount to the electric motor 3 by duty-controlling a control signal for driving the electric motor 3, it may be adjusted using a variable resistor.
The control means 6 of the present embodiment adjusts the energization amount to the electric motor 3 according to the measured value of the common rail pressure, but according to the injection amount command value by the injector 10, the SCV drive current command value, or the SCV drive current. You may adjust according to a duty ratio.
Although the control means 6 of the present embodiment is applied to the pressure accumulation type fuel injection device 1 that injects and supplies fuel to the engine via the common rail 7 where high pressure fuel is accumulated, it is applied to the fuel injection device that does not use the common rail. May be.

It is explanatory drawing which shows the structure of a fuel-injection apparatus. (A) is a correlation diagram between the pumping amount of the high-pressure pump and the electric power consumption of the electric motor, and (b) is a correlation diagram between the pumping amount of the high-pressure pump and the supply amount of the low-pressure pump.

Explanation of symbols

1 Fuel Injector 2 High Pressure Pump 3 Electric Motor (Electric Actuator)
4 Fuel tank 5 Low pressure pump 6 Control means 7 Common rail 8 Common rail pressure detection means 10 Injector (injection valve)
17 SCV (Suction metering valve)

Claims (4)

In a fuel injection device for injecting and supplying fuel to an engine,
A high-pressure pump for increasing the pressure of the fuel and supplying the fuel to the engine;
A low pressure pump driven by an electric actuator, pumping fuel from a fuel tank and supplying the pump to the high pressure pump;
A fuel injection device comprising: control means for controlling a fuel supply amount by the low-pressure pump by adjusting an energization amount to the electric actuator. The fuel injection device according to claim 1,
An injection valve for injecting fuel supplied from the high-pressure pump into the engine;
The fuel injection device according to claim 1, wherein the control means adjusts an energization amount to the electric actuator in accordance with an injection amount command value by the injection valve calculated in response to a request from the engine. The fuel injection device according to claim 1,
A common rail for accumulating fuel supplied from the high-pressure pump in a high-pressure state;
A common rail pressure detecting means for detecting the fuel pressure of the common rail,
The fuel injection device according to claim 1, wherein the control means adjusts an energization amount to the electric actuator in accordance with a detection signal from the common rail pressure detection means. The fuel injection device according to claim 1,
A common rail for accumulating fuel supplied from the high-pressure pump in a high-pressure state;
Common rail pressure detecting means for detecting the fuel pressure of the common rail;
An intake metering valve that adjusts an intake amount of fuel sucked into the high-pressure pump out of fuel supplied from the low-pressure pump;
The control means synthesizes a control signal for adjusting the valve opening of the intake metering valve in accordance with a detection signal from the common rail pressure detection means, and energizes the electric actuator in accordance with the control signal. A fuel injection device characterized by adjusting an amount.

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