JPH0159428B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for an automobile fuel pump that pumps fuel from a fuel tank to an intake system.

For example, the rotational speed of a fuel pump used in an electronically controlled fuel injection engine is regulated to be low in order to suppress vibration and noise. When an engine reaches a very high temperature, steam tends to be generated in the fuel, but conventional fuel pumps are unable to pump fuel containing a large amount of steam, making it difficult for the engine to start smoothly. is being inhibited.

An object of the present invention is to provide a fuel pump control device that can reliably pump fuel even when restarting an engine in a high temperature state.

In order to achieve this object, the fuel pump control device of the present invention includes a first detection means for detecting that the temperature of the engine is higher than a predetermined temperature, a second detection means for detecting the operation of the starter motor, and a first and second detection means for detecting the operation of the starter motor. A fuel pump driving means is provided for increasing the rotational speed of the fuel pump for a predetermined period of time from the start of engine startup when the engine is at a predetermined temperature or higher in response to the output of the second detection means.

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 schematically shows the entirety of an electronically controlled fuel injection engine. Air taken in from an air cleaner 1 is controlled in flow rate by a throttle valve 4 provided in a throttle body 2 and linked to an accelerator pedal 3 in the driver's cab. It is then supplied to the combustion chamber 9 of the engine body 8 via the surge tank 5, intake pipe 6, and intake valve 7. The air-fuel mixture combusted in the combustion chamber 9 is released as exhaust gas through an exhaust valve 10 and an exhaust branch pipe 11. An electromagnetic fuel injection valve 14 is provided in the intake pipe 6 corresponding to each combustion chamber 9. An electronic control unit 15 including a microcomputer controls the throttle valve 2
a throttle switch 16 for detecting the fully closed state of the
Water temperature sensor 18 attached to water jacket 17 of engine body 8, air cleaner 1 and throttle valve 4
An air flow meter 19 is provided between the piston 21 and the piston 21 to detect the intake air flow rate, an intake air temperature sensor 20 is provided to detect the intake air temperature, and the rotation angle of the crankshaft is connected to the piston 21 via a connecting rod 22. A rotation angle sensor 23 that detects the rotation angle of the distributor shaft connected to the crankshaft at 1/2 deceleration, an air-fuel ratio sensor 24 installed in the exhaust branch pipe 11 that detects the oxygen concentration in the exhaust gas, and a driver's cab. Position sensor 2 detects the position of the engine key
Receives input signal from 5th grade. The electronic control unit 15 further receives a primary current signal as a complete explosion signal from the power distributor 33. A fuel pump 31 driven by a DC motor is provided in a fuel passage 29 that connects the fuel tank and the fuel injection valve 14, and pumps the fuel in the fuel tank 30 to the fuel injection valve 14. The electronic control unit 15 calculates the fuel injection amount, fuel injection time, ignition timing, etc. based on input signals from each sensor, and sends electric pulses related to the calculation results to the fuel injection valve 14. The electronic control unit 15 also controls the rotational speed of the fuel pump 31.

FIG. 2 shows in detail the portions related to the rotational speed control of the fuel pump 31. The relay 35 is
It includes a pair of contacts 36, 37, an armature 38, and first and second coils 39, 40, the contact 36 is connected to a DC power source 41, and the first coil 39 is connected to the DC power source 41 and an air flow meter switch 42. The second coil 40 is connected to the starting terminal (ST) 43 of the engine switch. The air flow meter switch 42 is closed when the engine is operating, that is, when air is flowing through the air flow meter 19, and the starting terminal 43 generates a predetermined positive voltage when the engine key is in the starting position. Another relay 45 includes a pair of contacts 46, 47 and 48, 49, an armature 50, and a coil 51, contacts 46, 48 are connected to contact 37 of relay 35, and contact 47 is connected to DC through a resistor 52. Electric motor 53
The contact 49 is connected to the armature 54 of the armature 54.
The coil 51 is connected to the output terminal of the electronic control section 15. DC motor 53 drives fuel pump 31 , and electronic control unit 15 controls energization of coil 51 of relay 45 based on input signals from water temperature sensor 18 , position sensor 25 , and power distributor 33 .

When the engine key is placed in the starting position in the driver's cab, a predetermined positive voltage is generated at the starting terminal 43, energizing current is supplied to the second coil 40 of the relay 35, and the armature 38 contacts the contacts 36 and 37. . When starting by the starting motor is completed and the engine key is moved from the starting position to the ignition position, the second coil 4
0 is discontinued, but after startup, the intake air always passes through the air flow meter 19 in the intake system and the air flow meter switch 42 is closed, so the first coil 39 is energized by the DC power supply 41. The contact between the contacts 36, 37 and the armature 38 is maintained during engine operation.

FIG. 3 is a flowchart regarding the control of the relay 45 by the microcomputer of the electronic control section 15. A brief description of each step is as follows:
It is as follows.

Step 58: Is it starting? 〃 59: Is the cooling water temperature T≧105℃? 〃 60: Energize the coil 51 〃 61: Has more than 30 seconds passed since the start of the engine? In step 58, it is determined whether or not the engine is starting, that is, whether or not the engine key is in the starting position and the starting motor is operating. If the determination result is positive, the step is executed.
Go to 59; if not, end this program. In step 59, it is determined whether the engine cooling water temperature T, which corresponds to the engine temperature, is a predetermined value, for example, 108°C or higher, that is, whether the engine is in a very high temperature state, and the determination result is determined. If the value is positive, the process proceeds to step 60; if not, the program is terminated. In step 60, coil 51 of relay 45 is energized. As a result, the armature 50 of the relay 45 is connected to the contact 4
8 and 49, and the power supply current from the DC power source 41 is supplied to the armature 54 without passing through the resistor 52, so the voltage across the armature 54 increases, and the voltage of the DC motor 53, that is, the fuel pump 31 increases. The rotation speed increases. As a result, the pressure of fuel being pumped from the fuel tank 30 to the fuel injection valve 14 increases, and fuel can be reliably delivered to the fuel injection valve 14 without causing vapor lock, despite the high temperature state of the engine. If the cooling water temperature T is lower than 105℃,
Alternatively, the coil 51 is not energized because step 60 is not executed except during startup.
Therefore, the armature 50 contacts the contacts 46 and 47, and the current feeding the armature 54 flows through the resistor 52, so that the voltage across the armature 54 is maintained at a small value, thereby reducing vibration and noise. Can be suppressed. In step 61, the startup start time,
For example, it is determined whether a predetermined period of time, for example, 30 seconds has elapsed since the first complete explosion was performed and the primary current signal was sent from the power distributor 33 to the electronic control unit 15;
If the determination result is positive, the program is terminated, and if not, step 60 is executed again. Therefore, when the engine is started at a very high temperature, the rotational speed of the fuel pump 31 is maintained at a high speed for 30 seconds from the start of the engine. When the fuel flows through the fuel passage 29 at a sufficient flow rate, the temperature of the fuel within the fuel passage 29 decreases, so even if the rotational speed of the fuel pump 31 is lowered, vapor lock can be prevented from occurring. The time of 30 seconds was selected as the time for the steam in the fuel passage 29 to return to the fuel tank 30 via a return pipe (not shown) together with the fuel that was not injected from the fuel injection valve 14.

As described above, according to the present invention, when the engine is started at a very high temperature and vapor lock is likely to occur, the rotational speed of the fuel pump increases and the fuel pressure is increased, thereby causing vapor lock. It is possible to send fuel to the fuel injection valve and achieve a smooth start without any trouble.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the entire electronically controlled fuel injection engine, Fig. 2 is a detailed view of the part related to the fuel pump control device as an embodiment of the present invention, and Fig. 3 is a diagram showing the control system of the fuel pump in detail. It is a flowchart. 14...Fuel injection valve, 15...Electronic control unit, 1
8...Water temperature sensor, 25...Position sensor, 30...
...Fuel tank, 31...Fuel pump, 45...Relay, 52...Resistor, 53...DC motor.

Claims (1)

[Claims] 1. In a control device for a fuel pump that pressure-feeds fuel in a fuel tank to an intake system, a first detection means detects that the temperature of the engine is higher than a predetermined temperature, a second detection means detects operation of a starter motor, and a second detection means detects operation of a starting motor. The engine is characterized by comprising a fuel pump driving means that increases the rotational speed of the fuel pump for a predetermined period of time from the start of engine startup when the engine is at a predetermined temperature or higher in response to the outputs of the first and second detection means. A fuel pump control device.