JP2005106000A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine which prevents useless consumption of a battery.
A control device for an internal combustion engine includes a pump control unit that controls the operation of a fuel pump that supplies fuel to the internal combustion engine, and an intake passage that is provided in the intake passage. A pump operation determination unit that determines the start or end of the operation of the fuel pump 16 based on a signal from the air flow sensor 14 that measures the air amount, and the pump control unit is based on a determination result by the pump operation determination unit. Thus, the operation of the fuel pump 16 is controlled.
[Selection] Figure 1

Description

  The present invention relates to a control device that controls fuel injection of an internal combustion engine.

  A control device for an internal combustion engine used in a vehicle or the like operates a fuel pump provided in the internal combustion engine by a crank sensor signal transmitted from a crank sensor that detects a crank angle or a starter motor operation signal that senses the operation of a starter motor. Whether or not to perform the control is determined, and control for operating or stopping the fuel pump is performed based on the determination result.

In a conventional control device for an internal combustion engine, for example, a fuel pressure adjustment valve whose pressure is increased by a fuel pump that is operated immediately after key-on and fuel is sent from a fuel tank, and a fuel pressure detection device that detects fuel pressure in the fuel pressure adjustment valve And a control device for an internal combustion engine. This control device for an internal combustion engine holds the fuel injection valve closed and stops fuel injection until the fuel pressure detected by the fuel pressure detection device reaches a predetermined value (see Patent Document 1).
Another control device for an internal combustion engine provided with a fuel pump, which learns the time from key-on to starter-on, operates the fuel pump according to the time, and reduces the operating noise of the fuel pump There is a control device (see Patent Document 2).
Further, there is a control device for an internal combustion engine provided with a fuel pump, which operates the fuel pump in accordance with the engine coolant temperature after key-on and reduces the operating noise of the fuel pump ( (See Patent Document 3).
Japanese Patent Publication No. 60-8340 (page 1-2, Fig. 2) JP-A-6-323183 (page 3-6, FIG. 1) Japanese Patent Laid-Open No. 7-34993 (page 4-5, FIG. 2)

In a conventional control device for an internal combustion engine, when a crank sensor is not installed or when a manual recoil starter is provided without a starter motor, such as a general-purpose engine, a fuel pump is controlled based on each sensor. Cannot determine whether to work. Therefore, it becomes impossible to control the operation or stop of the fuel pump. Therefore, while operating the internal combustion engine, the fuel pump must be continuously operated with the battery as a power source. As a result, while operating the internal combustion engine, the fuel pump is operated even when it is not necessary to operate the fuel pump, so that there is a problem that the battery for supplying power to the fuel pump is wasted.
Similarly, before the internal combustion engine is started, that is, after the key-on and until the internal combustion engine is started, the fuel pump must always be operated with the battery as a power source. As a result, since the fuel pump is operated even when it is not necessary to operate the fuel pump before the internal combustion engine is started, there is a problem that a battery for supplying power to the fuel pump is wasted.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a control device for an internal combustion engine that prevents wasteful consumption of a battery.

The present invention employs the following means in order to solve the above problems.
A control device for an internal combustion engine (for example, the control device 7 in the present embodiment) according to the present invention is a fuel pump (for example, the fuel pump 16 in the present embodiment) that supplies fuel to the internal combustion engine (for example, the engine 2 in the present embodiment). A pump control unit (for example, the pump control unit 7a in the present embodiment) that controls the operation and an amount of air taken into the intake passage provided in the intake passage (for example, the intake passage 4 in the present embodiment) of the internal combustion engine are measured. A pump operation determining unit (for example, the pump operation determining unit 7b in the present embodiment) that determines the start or end of the operation of the fuel pump based on a signal from an air flow sensor (for example, the air flow meter 14 in the present embodiment). The pump control unit controls the operation of the fuel pump based on a determination result by the pump operation determination unit. Characterized in that it.

  According to the present invention, the control device for the internal combustion engine measures the amount of air taken into the internal combustion engine by the air flow sensor provided in the intake passage of the internal combustion engine, and the pump operation determination unit determines from the signal of the air flow sensor. The start or end of the operation of the fuel pump is determined. For example, when the amount of air sucked into the internal combustion engine increases and fuel supply becomes necessary, the pump operation determination unit determines the start of operation of the fuel pump, and the amount of air sucked into the internal combustion engine decreases to reduce the amount of fuel. When the supply is unnecessary, the pump operation determination unit determines the end of the operation of the fuel pump. When the pump operation determining unit determines that the operation of the fuel pump is started or ended, a pump control unit that controls the operation of the fuel pump starts or ends the operation of the fuel pump. That is, the pump control unit that controls the operation of the fuel pump operates the fuel pump only when the fuel needs to be supplied. Therefore, it is not necessary to always operate the fuel pump even after the internal combustion engine is started.

In the control device for an internal combustion engine according to the present invention, the air flow rate sensor is provided on a downstream side of a throttle valve provided in the intake passage.
In the control device for an internal combustion engine according to the present invention, the air flow rate sensor is an air flow meter capable of detecting the air amount as a mass flow rate.
According to the present invention, the air flow sensor is provided in the intake passage so that the amount of air actually taken into the internal combustion engine among the air supplied through the throttle valve can be accurately detected. It is preferable to be provided downstream of the valve. The air flow sensor is preferably an air flow meter that can detect the amount of air sucked into the internal combustion engine as a mass flow rate.

  According to the control device for an internal combustion engine of the present invention, the pump control unit that controls the operation of the fuel pump operates the fuel pump only when the fuel needs to be supplied. Even after the internal combustion engine is started, the fuel pump Since it is not necessary to always operate the battery, wasteful consumption of the battery can be prevented.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing an engine control system including a control device for an internal combustion engine in the present embodiment.
An engine control system 1 of the present embodiment shown in FIG. 1 sucks air from an intake passage 4 connected to an intake manifold 3 of an engine 2 that is an internal combustion engine, and this air and an injector disposed in the intake manifold 3. When the fuel ejected from 5 is mixed and then combusted in the combustion chamber 2a of the engine 2 and the combustion gas after combustion is discharged from the exhaust manifold 6, the control device 7 of the internal combustion engine takes in the air that the engine 2 takes in The injection amount and injection timing of the fuel to be injected are controlled according to the amount (intake amount).

  The intake passage 4 includes an air cleaner 11 and a throttle body 13 having a throttle valve 12 that is a throttle valve that adjusts the air amount downstream of the air cleaner 11. The amount of air sucked into the engine 2 through the intake passage 4 is detected as a mass flow rate in an air flow meter (air flow sensor) 14 that is a sensor disposed so as to be located downstream of the throttle valve 12. Is done. Since the air flow meter 14 is downstream of the throttle valve 12, the amount of air actually taken into the combustion chamber 2a of the engine 2 out of the air that has passed through the air cleaner 11 can be accurately detected. In order to detect the amount of air that has passed through the air cleaner 11, the air flow meter 14 may be located upstream of the throttle valve 12.

The air flow meter 14 suitable for this embodiment includes a sensor that deposits a platinum thin film on a silicon substrate and energizes the platinum thin film to keep the temperature constant. As the mass of air flowing around the platinum film increases, the amount of heat dissipated from the platinum film through the air increases, and the temperature of the platinum film decreases proportionally. At this time, the air flow meter 14 increases the current applied to the platinum thin film so as to keep the temperature constant. On the other hand, when the mass of the air flowing around the platinum thin film decreases, the amount of heat dissipated from the platinum thin film through the air decreases and the temperature of the platinum thin film rises. Decrease. Thus, since the current value increases and decreases in proportion to the increase and decrease of the mass of air flowing around the platinum thin film, the amount of air can be measured by monitoring this current value.
In addition, since such an air flow meter 14 can reduce a heat mass compared with the case where the wire made from platinum is used, it has implement | achieved high responsiveness and high measurement accuracy.

The injector 5 ejects fuel into the air flowing through the intake manifold 3 by opening / closing operation of the electromagnetic injection valve. The injector 5 is pumped from a fuel pump 16 provided in the fuel tank 15 and regulated by a regulator 17. The supplied fuel is supplied.
Supply of the mixed gas to the combustion chamber 2a and discharge after combustion are performed by an intake valve 2b and an exhaust valve 2c driven by a valve timing mechanism (not shown).
Ignition of the mixed gas is performed by a spark plug 8. The spark plug 8 discharges using the high energy accumulated in the ignition circuit 9.

  A control device 7 that performs control in the engine control system 1 is a so-called ECU (Electronic Control Unit), has a CPU (Central Processing Unit), a ROM (Read Only Memory), and the like, and receives power supply from the battery 10. Works. As shown in FIG. 2, the control device 7 uses a pump control unit 7 a that controls the operation of the fuel pump 16 that supplies fuel to the engine 2, and the start or end of the operation of the fuel pump 16 as a signal of the air flow meter 14. A pump operation determination unit 7b for determining the amount of fuel to be supplied from the fuel pump 16 to the injector 5 by using the output current of the air flow meter 14 as input data and performing predetermined processing. The injection amount and the injection timing thereof, the timing for starting charging the ignition circuit 9, and the ignition timing are determined, and command signals are output to the respective parts.

Next, functions and operations of the control apparatus for an internal combustion engine having the above-described configuration will be described.
When the engine 2 is operated, the intake of air into the engine 2 is started after a certain amount of time has elapsed, the air amount gradually increases, and after the air amount reaches the maximum, the air amount gradually increases. In time, the amount of air approaches zero and the inhalation of air is terminated.
Here, the start and end of inhalation processed by the pump control unit 7 will be described.
FIG. 3 is a diagram showing a change in the air amount that changes as the engine 2 is operated. The horizontal axis indicates the passage of time, and the vertical axis indicates the intake air amount.

  In FIG. 3, the amount of air that fluctuates over time is a value obtained by multiplying the output current from the air flow meter 14 by a predetermined coefficient. The obtained air amount is treated as a forward flow when it is larger than a predetermined threshold value (reference value), and as a reverse flow when it is less than that. Note that forward flow means that air flows in the direction of being drawn into the engine 2. The reverse flow means that the air flows in the reverse direction, that is, in the direction in which the throttle valve 12 is present. When the intake valve 2b of the engine 2 is closed, the blocked air flows in the reverse direction. Caused by. A state in which such forward flow and reverse flow are alternately generated is defined as a pulsating flow.

  Further, the intake valve 2b of the engine 2 may be opened with the throttle valve 12 being slightly opened. In such a case, a negative pressure is generated in the intake passage 4. Since this negative pressure remains even when the intake valve 2b is closed, a slight flow of air flowing in through the throttle valve 12 may occur. The flow of air generated under such conditions is set to an underflow.

A region where the air amount increases beyond the range of pulsating flow and underflow is a region where air is sucked into the engine 2 and corresponds to an intake process of the engine 2. The start of intake (rise of intake) is the start point (point A in FIG. 3) of the rise of air when the amount of air exceeds the magnitude of pulsating flow and underflow. Since this starting point is determined by the opening timing of the intake valve 2b of the engine 2 (the crankshaft 2d is at a predetermined angle), the fuel injection timing and the ignition timing can be controlled with this point as a reference point.
In addition, the end of intake (fall of intake) is when the amount of air that decreases beyond the peak value drops to 0 (point B in FIG. 3). Further, the peak position is a place where the amount of change in the air amount within a predetermined time is close to 0 (point C in FIG. 3).

Here, the function of the control device 7 of the internal combustion engine will be described based on the flowchart of FIG.
When detecting the air amount detected by the air flow meter 14, the pump operation determining unit 7 b of the control device 7 for the internal combustion engine determines that the rising of the air amount is the start of intake, and then the time when the air amount drops to zero. It is determined that the intake is finished.
When the engine 2 and the air flow meter 14 are activated, the air flow meter 14 detects the amount of air taken into the engine 2 (step S1). When the air flow meter 14 continues to detect the air amount from the air amount detected by the air flow meter 14 until the pump operation determination unit 7b determines that the intake air starts, and when the pump operation determination unit 7b determines the start of intake air (step S2) The pump control unit 7a of the control device 7 for the internal combustion engine issues an instruction to operate the fuel pump 16 in the fuel tank 15 (step S3), and starts the operation of the fuel pump 16 (step S4). As a result, the fuel stored in the fuel tank 15 is pumped out from the fuel pump 16 (step S5), regulated by the regulator 17, sent to the injector 5 (step S6), and supplied from the injector 5 to the engine 2. (Step S7).

Thereafter, the air flow meter 14 detects the amount of air taken into the engine 2 (step S8). Steps S5 to S8 are repeated from the air amount detected by the air flow meter 14 until the pump operation determination unit 7b determines that the intake is completed, and fuel is continuously supplied to the engine 2 and the air flow meter 14 continues to detect the air amount. . When the pump operation determining unit 7b determines that the intake is finished (step S9), the pump control unit 7a issues an instruction to stop the operation of the fuel pump 16 in the fuel tank 15 (step S10), and the operation of the fuel pump 16 is performed. Is terminated (step S11). As a result, the fuel is not pumped out from the fuel pump 16 and is therefore not sent to the injector 5 and is not supplied from the injector 5 to the engine 2.
When the engine 2 continues to drive, the process returns to step S1 and the air flow meter 14 detects the amount of air taken into the engine 2. When the engine 2 has finished driving, the detection of the air amount of the air flow meter 14 is ended (step S12).

  When the control device 7 functions in this way, the pump operation determination unit 7b determines the start of intake and the end of intake, and the pump control unit 7a that controls the operation of the fuel pump based on the determination result Since the fuel pump 16 is operated only when the instruction is issued and the fuel supply is necessary, it is not necessary to always operate the fuel pump 16 even after the engine 2 is started. Further, since the fuel pump is operated only by the air flow meter 14, it is not necessary to provide a crank sensor or the like in order to operate the fuel pump as in the prior art.

  According to the above configuration, the control device 7 that controls the operation of the fuel pump operates the fuel pump 16 based only on the air flow meter 14 without providing a crank sensor or the like for operating the fuel pump as in the prior art. In addition, the fuel pump 16 is operated only when fuel supply is necessary, and it is not always necessary to operate the fuel pump 16 even after the engine 2 is started. it can.

In the present embodiment, if the pump operation determination unit 7b determines that the intake air has ended, whether or not to stop the operation of the fuel pump 16 before issuing an instruction to stop the operation of the fuel pump 16 in the fuel tank 15. The operation of the fuel pump 16 may be continued until it is determined that the operation of the fuel pump 16 is to be stopped.
Here, the flowchart is shown in FIG. Steps similar to those in the flowchart of FIG. 4 are denoted by the same reference numerals and description thereof is omitted.

As shown in FIG. 5, when the pump operation determination unit 7b determines that the intake is finished (step S9), a predetermined time elapses thereafter (step S13), and it is determined whether to stop the operation of the fuel pump 16 or not. Is performed (step S14). If it is determined not to stop the operation of the fuel pump 16, the operation returns to step S5 without stopping the operation of the fuel pump 16, the fuel is supplied to the engine 2, and the air flow meter 14 detects the amount of air.
When it is determined that the operation of the fuel pump 16 is to be stopped, the pump controller 7a issues an instruction to stop the operation of the fuel pump 16 in the fuel tank 15 (step S10), and the operation of the fuel pump 16 is ended (step S10). S11).
Thus, before issuing an instruction to stop the operation of the fuel pump 16 in the fuel tank 15, the operation of the fuel pump 16 is temporarily stopped by determining that the operation of the fuel pump 16 is continued without stopping. Since the operation of the fuel pump 16 is not started again immediately after the operation is performed, useless processes and useless power consumption can be prevented.

  In the present embodiment, the amount of fuel supplied to the engine 2 may be controlled by changing the injection pressure of the fuel injected from the injector 5 in accordance with the amount of air detected by the air flow meter 14. For example, the combustion efficiency of the fuel in the engine 2 is improved by increasing the fuel injection pressure and shortening the injection time when the amount of air taken into the engine 2 increases. However, in this case, it is preferable that the pump controller 7 controls the fuel pressure regulation by the regulator 17.

In the present embodiment, the air flow rate sensor is preferably an air flow meter 14 that can detect the amount of air sucked into the engine 2 as a mass flow rate, but is a sensor that measures the amount of air sucked into the engine 2. I just need it. Examples of the air flow rate sensor that can be used in the present invention include a pressure sensor (intake pressure sensor).
When the throttle valve 12 is closed, the pressure in the intake passage 4 when the engine 2 is started is different from the pressure in the intake passage 4 when the engine 2 is stopped. A pressure sensor is provided to detect the pressure. Accordingly, when the pressure in the state where the engine 2 is started is detected, it is determined that the engine 2 is started and air is sucked, and the fuel pump 16 is operated. On the contrary, when the pressure is detected in a state where the engine 2 is stopped, it is determined that the engine 2 is stopped and air is not sucked, and the fuel pump 16 is stopped. Therefore, even if the air flow meter of this embodiment is replaced with a pressure sensor, the same effect as the present invention can be obtained.

Here, a case where a pressure sensor is used as an air flow rate sensor and a case where an air flow meter is used are compared.
When the pressure sensor is used, the pressure sensor detects the air pressure in the intake passage. Since the throttle valve is closed when the engine is started and stopped, a pressure change occurs in the intake passage before and after the engine is started and stopped, so that the pressure sensor can detect the pressure change. Therefore, it is possible to control the fuel pump to operate based on this pressure change.

  However, after starting the engine and opening the throttle valve, when air with a pressure almost equal to the atmospheric pressure flows in the intake passage and the pressure sensor detects the pressure value, the air pressure actually has the atmospheric pressure. It is difficult to determine whether the air is flowing or whether the amount of air flowing in the intake passage is zero. Therefore, when the engine is stopped with air having a pressure substantially equal to the atmospheric pressure flowing in the intake passage, no pressure change occurs in the intake passage before and after the engine is stopped. It may be difficult to make a decision to stop the operation.

On the other hand, when an air flow meter is used, the air flow meter accurately detects whether or not air is flowing in the intake passage. Therefore, it may be determined to start or stop the fuel pump according to the amount of flowing air. Easy. In addition, unlike the case where a pressure sensor is used, it is not affected by the pressure value of the air flowing in the intake passage.
Therefore, although either a pressure sensor or an air flow meter may be used as the air flow rate sensor, it is preferable to use an air flow meter.

  In the present embodiment, the engine 2 is started by a recoil starter such as a general-purpose engine and is not provided with a starter motor, or is not provided with a crank sensor for detecting crank rotation. . On the other hand, for an engine provided with a starter motor or an engine provided with a crank sensor, it can be determined whether or not the engine is rotating. Therefore, the operation of the fuel pump is started or ended based on the determination.

  For example, in an engine provided with a starter motor, the fuel pump is started after a certain time has elapsed after the starter switch button is pressed, and after a certain time has elapsed after the starter motor is stopped. The fuel pump is stopped. The engine provided with the crank sensor is configured to start the fuel pump based on the rotational position of the crankshaft, and to stop the fuel pump based on the determination that the crank is stopped.

1 is a schematic diagram of an engine control system including a control device for an internal combustion engine in an embodiment of the present invention. 1 is a block diagram of a control device for an internal combustion engine in an embodiment of the present invention. It is a figure which shows an example of the change of the air which changes with operation of an engine. It is a flowchart about the function of the control apparatus of the internal combustion engine in embodiment of this invention. It is another flowchart about the function of the control apparatus of the internal combustion engine in embodiment of this invention.

Explanation of symbols

2 Engine (Internal combustion engine)
4 Intake passage 7 Control device 7a Pump control unit 7b Pump operation determination unit 12 Throttle valve (throttle valve)
14 Air flow meter (air flow sensor)
16 Fuel pump

Claims (3)

Based on a signal from a pump control unit that controls the operation of a fuel pump that supplies fuel to the internal combustion engine and an air flow sensor that is provided in the intake passage of the internal combustion engine and measures the amount of air taken into the intake passage, A pump operation determination unit for determining the start or end of the operation of the fuel pump,
The control apparatus for an internal combustion engine, wherein the pump control unit controls the operation of the fuel pump based on a determination result by the pump operation determination unit.   2. The control apparatus for an internal combustion engine according to claim 1, wherein the air flow rate sensor is provided on a downstream side of a throttle valve provided in the intake passage.   3. The control apparatus for an internal combustion engine according to claim 1, wherein the air flow rate sensor is an air flow meter capable of detecting the air amount as a mass flow rate.

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