JPS61101664A - Control device for fuel pump - Google Patents

Abstract

PURPOSE:To prevent the trouble of an engine by a method wherein the fuel supply of the engine is stopped when an abnormality is detected in a relay in the fuel pump provided with the control relay increasing the delivery capacity of fuel upon high load by increasing the amount of conduction of electricity for the fuel pump. CONSTITUTION:During the operation of the engine, a load (Q/N) is operated in a control circuit 40 by the amount Q of suction air, detected by an airflow meter 12, and the revolving number N of the engine, obtained by the output of a rotating angle sensor 36, and the load is decided whether it is higher than a predetermined value or not. Upon high load operation, in which the decision is YES, the control relay 52 is put ON to increase the amount of conduction of electricity of the fuel pump 44 and increase the delivery capacity of of the pump. On the other hand, in case the control relay 52 is decided by a comparator means that the relay 52 is cut OFF by some abnormality due to the faulty contact of the contacts of the relay or the like, a fuel cut carry out plug is set to carry out fuel cut whereby overheat of an exhaust gas system or the like may be prevented.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a fuel pump control device, and more particularly to an improvement in a fuel pump control device for pressure-feeding fuel to an engine, which is suitable for use in a fuel Ill control engine for an automobile. (Prior art 1) In general, in a fuel-dispensing engine, the amount of fuel supplied to the engine is controlled by controlling the valve opening time of the injector. In order to make a one-to-one correspondence between fuel quantity 1) J and I, it is necessary to keep the injection pressure at the injector constant (directly). That is, the pressure regulator controls the pressure difference between, for example, the pressure of the fuel being supplied to the injector and the pressure of the atmosphere at which fuel injection is performed, so that it is always maintained at a constant pressure. By the way, the atmosphere in which fuel injection is performed, that is, the intake pipe pressure, changes depending on the engine load condition and is relatively high.
The intake pipe pressure is high when the load is high, and the intake pipe pressure is low when the load is relatively low. Therefore, if the pressure of fuel supplied to the injector by the fuel pump is constant, the control action of the pressure regulator will cause
The amount of fuel returned to the fuel tank as excess fuel will increase as the engine load decreases. Therefore, as already proposed by the applicant in Japanese Patent Application No. 58-183883, the load state of the engine is detected, and in a predetermined low load range, the fuel pressure supplied to the injector by the fuel pump is low. It has been proposed to control the fuel pump so that the amount of excess fuel returned from the pressure regulator to the fuel tank is reduced. By controlling the fuel pump in this way, it is possible to eliminate non-stop operation of the fuel pump, reduce the initial noise of the fuel pump in low load ranges such as during idling, improve durability, and improve charge/discharge balance. This has the advantage that it is possible to improve the

Problem to be Solved by the Invention 1 However, when a control relay is configured to increase the amount of electricity supplied to the fuel pump at least during high loads to improve the discharge capacity, contact failure of the contacts of the control relay may occur. If there is malfunction due to misalignment of the terminals of the fuel pump or connector, etc., and if the amount of electricity to the fuel pump remains small despite the high load that should improve the discharge capacity, the discharge capacity will be insufficient and the air-fuel ratio will decrease. This can cause so-called pre-ignition, in which ignition occurs faster than the set ignition timing, completely unknown to the driver, or the engine, catalyst, and other exhaust systems may overheat, and in severe cases, the engine may There was a risk of it breaking down. OBJECT OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the conventional art. It is an object of the present invention to provide a fuel pump control device that does not cause overheating of the engine or exhaust system, and therefore does not cause engine failure. [Means for Solving the Problems] The present invention provides a fuel pump control device, the gist of which is shown in FIG. A control relay for increasing discharge capacity by increasing the flow NM to the fuel pump, a control relay abnormality detection means for detecting malfunction of the control relay, and malfunction of the control relay at least under high load. The above object is achieved by providing fail-safe processing means that stops fuel supply to the engine when detected. Further, in an embodiment of the present invention, the fail-safe processing means also outputs a warning to the driver, so that the driver can take appropriate measures such as stopping high-load operation when the control relay malfunctions. It was designed so that it could be taken. Further, in another embodiment of the present invention, the stoppage of fuel supply by the fail-safe processing means is canceled when the malfunction of the control relay is resolved or when the load is not high. This made it possible to run. [Effect 1] In the present invention, at least under high load, when a malfunction of the control relay, which increases the amount of current supplied to the fuel pump to improve its discharge capacity, is detected, the fuel supply to the engine is stopped. Therefore, a situation where the air-fuel ratio becomes lean due to insufficient discharge capacity of the fuel pump can be avoided. Therefore, pre-ignition and exhaust system overheating will not occur, and the engine will not malfunction. (Example 1) An example of the present invention will be described in detail below with reference to the drawings. As shown in Fig. 2, the fuel split type engine for an automobile of this example is located downstream of an air cleaner (not shown). Air meter 1 installed on the side for detecting the amount of intake air
It is equipped with 2. Near the air 70-meter 12,
An intake air temperature sensor 14 is provided to detect the temperature of intake air. A throttle valve 16 is disposed downstream of the air flow meter 12, and a surge tank 18 is disposed downstream of the throttle valve 16. An intake manifold 20 is connected to the surge tank 18, and an injector 22 is disposed to protrude into the intake manifold 20. The intake manifold 20 is connected to the combustion chamber 10A of the engine body 10, and the engine combustion chamber 10A is connected via an exhaust manifold 24 to a catalytic converter (not shown) filled with a three-way catalyst. Note that 26 is a cooling water temperature sensor for detecting the engine cooling water temperature. The spark plug 28 of the engine main body 10 is connected to a distributator 30, and the distributator 30 is connected to an igniter 32. The de-repeater 30 is provided with a cylinder discrimination sensor 34 and a rotation angle sensor 36, which are composed of a pickup and a signal rotor fixed to the de-repeater shaft. The cylinder discrimination sensor 34 outputs a cylinder discrimination signal to the control circuit 40, for example, every 180 degrees of crank angle for a four-cylinder engine, and every 120 degrees of crank angle for a six-cylinder engine. A crank angle signal is output to the control circuit 40 at every 30'' crank angle. By the way, if the engine in this case is a 6-cylinder engine, the injector 22 has one injector for each cylinder, as shown in detail in FIG. Each injector 22A to 22F is connected to a delivery pipe 42.The delivery pipe 42 is supplied with fuel by a fuel pump 44.Fuel from a tank 46 is supplied via a fuel filter 48. The fuel pressure in the delivery pipe 42 is controlled by a pressure regulator 50 so that the pressure difference between the fuel pressure and the intake pipe pressure in the intake manifold 20, which is the atmosphere in which fuel injection is performed, is always constant. The remaining fuel as a result of the fuel pressure control is returned to the fuel tank 46. As shown in detail in FIG. 4, the control circuit 40 includes a starter signal STA input from a starter (not shown) and the rotation angle sensor. Input interface circuit for taking in rotation angle No. 13 etc. input from 36 (hereinafter referred to as input 17)
/'F circuit) 40A, and an analog-to-digital converter (hereinafter referred to as A
7/'D converter) 40B, and a central processing unit (hereinafter referred to as CPU) for performing various arithmetic processing.
40G and a control relay 52 for controlling the current flowing to the injector 22 and the fuel pump 44 according to the calculation result of the CPU 40C (!lI
It mainly consists of an output interface circuit (hereinafter referred to as output 1, /F circuit) that outputs a signal. The above is the same configuration as the conventional control circuit 40, but in this embodiment, Further, the potential difference between both ends of the control relay 52 is detected using a solenoid resistor 54 for suppressing the Nlf flow to the fuel pump 44. A comparator circuit 40E is provided to detect that the potential difference between both ends is greater than a set value.The output of the comparator circuit 40E is set to 1 when the control relays 5 and 2 are off. ,
It is also input to the CPU 40C. Further, the output of the output I7/'F circuit 40D is the output of the injector 2.
In addition to 2 and the control relay 52, the signal is also input to a warning lamp 56 for notifying the driver of an abnormality. The fail-safe processing procedure in this embodiment will be explained below with reference to FIG. Every time a predetermined period of time 1, for example 50 milliseconds has elapsed, step 110 is entered and it is determined whether the starter signal STA is on. If the determination result is negative, that is, if it is determined that it is not the time to start, the process proceeds to step 112, where the intake air IQ output from the air flow meter 12 is measured by the rotation angle sensor 36.
11 divided by the engine speed N calculated from the output! (
The intake air amount per engine revolution) Q/N is the judgment value Th
It is determined whether or not the above is satisfied. If the determination result is negative, that is, when it is determined that there is no need to increase the discharge capacity of the fuel pump 44, neither at startup nor during high load running, the process proceeds to step 114, and the control relay 52
Turn off and pull. As a result, the communication to the fuel pump 44 is
I is suppressed by the solenoid resistor 54, the durability of the fuel pump 44 is improved, and it is advantageous in terms of charging IIi electricity balance. Next, in step 116, the fuel cut execution flag r C
The routine ends by resetting the UT and allowing normal fuel injection to occur. On the other hand, if the determination result in step 110 or 112 is positive, that is, at the time of starting or during high load running,
When it is determined that it is necessary to increase the discharge capacity of the fuel pump 44, the process proceeds to step 120 and the control relay 52 is turned on. This short-circuits the solenoid resistor 54 and improves the discharge capacity of the fuel pump 44. Next, the process proceeds to step 122, where it is determined whether or not it is time to start. If the determination result is negative, that is, if it is determined that the vehicle is running under a high load, step 124
Then, the battery voltage 10B becomes the judgment value T111~Th2
(for example, 12 to 16 ■). Here, the battery voltage +B is checked only when the battery voltage is within a certain range, by detecting the current between both terminals of the solenoid register 54, and checking the voltage detection accuracy, that is, the control relay This is to reduce the accuracy of malfunction determination of 52. by this,
Misjudgment when the battery voltage is abnormally low, such as during cranking, can be prevented. If the determination result in step 124 is positive,
□That is, when it is determined that an accurate determination is made, the process proceeds to step 126, and it is determined whether the output of the comparator circuit 40E is "1".If the determination result is positive, that is, if the high When the control relay 52 is under load and should normally be on, it is determined that the control relays 5 and 2 are off due to some abnormality such as poor contact or disconnection of the connector terminal. In some cases, the process proceeds to step 128, and the fuel cut execution flag rcl, !T is set so that a fuel cut is executed.This allows the ship to continue running under high load while the discharge capacity of the fuel pump 44 is insufficient. This prevents pre-ignition and overheating of the exhaust system, which could occur if the engine were to run.Next, the process proceeds to step 130, where the warning lamp 56 is turned on to give a warning to the driver, and this routine ends. On the other hand, if the determination result in step 126 is negative,
That is, when the control relay 52 is turned on and is operating normally during high load running, or when it is determined that normal operation has been restored after the defective operation 113, step 1 is performed.
32, the fuel cut execution flag r cu"r is reset. Next, the process proceeds to step 134, where the warning lamp 56 is turned off, and this routine ends. Also, the determination result of step 122 is is positive and it is determined that it is time to start, or when the determination result of step 124 is negative and it is determined that accurate determination cannot be made, this routine is immediately terminated.This embodiment In this system, an abnormality in the control relay 52 is detected only when the battery voltage +B is within a certain range, so an incorrect determination is not made when the voltage is abnormally low, such as during cranking, and the control relay 52 is detected only when the battery voltage +B is within a certain range. 52 has a high accuracy of abnormality detection.In addition, in this embodiment, not only when the malfunction of the control relay 52 is resolved, but also when high load driving is stopped, that is, the intake air IQ/engine rotation per revolution is determined. Since the fuel cut is also canceled when N becomes less than the judgment value Th, evacuation driving is possible.In the above embodiment, the high load state is judged based on the intake air per revolution of the engine. Although the method for determining the high load condition is not limited to this, for example, it is possible to determine the high load state according to the negative pressure in the intake pipe. Although the present invention is applied to a fuel injection type engine for automobiles, it is clear that the scope of application of the present invention is not limited to this and can be similarly applied to general engines. 1. As explained above, according to the present invention, even if there is a malfunction such as a contact failure in the control relay that controls the energizing current of the fuel pump, it will not lead to pre-ignition or overheating of the exhaust system. This has the excellent effect of making it possible to protect the engine body.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the main structure of a fuel pump control device according to the present invention, and FIG. 2 is a block diagram showing a fuel pump control illumination device for an automobile in which the fuel pump control illumination device according to the present invention is adopted. 3 is a sectional view including a partial block diagram, FIG. 3 is a pipe diagram showing the configuration of the fuel system in the embodiment, and FIG. 4 is a fuel system used in the embodiment. A circuit diagram showing the configuration of the control circuit shown in FIG. 5 is also shown in FIG.
2 is a flowchart showing a procedure for executing a failsafe. DESCRIPTION OF SYMBOLS 10... Engine body, 12... Air flow meter, 22.22A-22F... Injector, 36...
...Rotation angle sensor, 40...Control circuit, 40E...
・Comparator circuit, 44... Fuel pump, 52... Control relay, 54... Solenoid register, 56... Warning lamp, Q, -' N... Intake air amount per engine revolution , Th...judgment value, f CUT...fuel cut execution flag.゛ Agent Takaya Ronmatsu Keisuke Yama Figure 4 Figure 5

Claims (3)

[Claims] (1) A fuel pump for pressure-feeding fuel to the engine, a control relay for increasing the amount of electricity supplied to the fuel pump to improve its discharge capacity at least under high loads, and detecting malfunction of the control relay. a control relay abnormality detection means for detecting a malfunction of the control relay; and a fail-safe processing means for stopping fuel supply to the engine when malfunction of the control relay is detected at least under high load. Pump control device. (2) The fuel pump control device according to claim 1, wherein the fail-safe processing means also outputs a warning to the driver. (3) The stoppage of fuel supply by the fail-safe processing means is canceled when the malfunction of the control relay is resolved or when the high load is no longer present. Fuel pump control device.