JPS62135660A - Device for controlling fuel pump for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent shortage in the quantity of fuel supply by controlling the driving force of a fuel pump to be on the high driving force side when the abnormality of microcomputer has occurred in a device in which the driving force of said fuel pump is controlled by said microcomputer in accordance with the operating condition of an engine. CONSTITUTION:When an abnormal condition has occurred in which an H signal as a normal signal at every fixed time (e.g., every 10msec) is not outputted from an ECU 24, the output of a comparator 25 becomes L and a transistor Tr 26 is turned off due to a driving force controlling signal 11. Thereupon, a capacitor 16 is gradually charged and, when the input voltage of a comparator 17 becomes above a reference voltage, the output of the comparator 17 becomes H, turning on a Tr 18 as well as relays 19, 20. Thereby, a Tr 21 is electrified, from a storage battery 15 via relays 14, 20 and turned on, while turning on a relay 22. Accordingly, a high voltage is applied to a fuel pump 2, and a quantity of fuel more than the maximum fuel quantity required by an engine, is fed into a pressure regulator 6.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a fuel pump control device used in an internal combustion engine for a vehicle such as an automobile.

2. Description of the Related Art In general, in internal combustion engines for vehicles, liquid fuel such as gasoline stored in a fuel tank is sent to a fuel injection valve by a fuel pump, and the liquid twist 1' is sent from the fuel injection valve to a separate intake system. We are trying to supply it. Among these, in the case of fuel pumps that require particularly high performance, there are some in which the performance of the fuel pump is controlled by a microcomputer installed in the vehicle in accordance with the fuel required by the engine or the power supply voltage. Furthermore, microcomputers are also used to control the ignition timing and fuel injection timing of internal combustion engines.

In the case where the fuel pump is controlled by a microcomputer, when an abnormality occurs in the computer, the fuel pump is not controlled normally, and the fuel pump performance is controlled to be low when the engine's required twist II-FA is high. was there.

If the fuel pump is controlled by the same microcomputer that controls the ignition timing and fuel injection amount, the ignition timing control and fuel injection will be inconsistent, but in conventional internal combustion engines, the microcomputer controls the ignition timing and fuel injection amount. It has seven functions for injection control, and when an abnormality is detected in the microcomputer, the backup function adjusts the ignition timing and fuel injection based on the output of the engine speed sensor, throttle switch, etc. It is controlled by switching in several stages or by keeping it fixed.

In this case, the backup function is to enable the vehicle to run on its own even if an abnormality occurs in the microcomputer, and it controls the ignition timing by controlling the ignition timing predetermined by the starter signal, idle contact on/off signal, etc. and executes fuel injection control (backup mode).

While the backup function is in operation, the fuel injection time is switched in several steps, for example, and the ignition timing is changed to BTD regardless of the rotation speed.
Fixed to Cloo.

Problems to be Solved by the Invention As described above, with the conventional fuel injection pump control device, there is a high possibility that the performance of the fuel pump will be insufficient when the battery voltage drops due to an abnormality in the microcomputer, and the pressure regulator Pressure regulation becomes impossible, and the amount of fuel injected by the fuel injector decreases below the required injection amount, resulting in a drop in engine output that makes it impossible for the vehicle to run on its own, and the upper limit of exhaust temperature causing melting of the catalyst. Sometimes.

The present invention was made to solve these problems, and it maintains the driving voltage of the fuel pump so that the performance of the fuel pump is high when an abnormality occurs in the output of the microcomputer. The purpose is to ensure the pressure regulating function of the pressure regulator and avoid overlean air-fuel ratio by discharging more fuel from the fuel pump than the maximum fuel amount required by the engine.

Means for Solving the Problems In the fuel pump control device for an internal combustion engine according to the present invention, the driving force of the fuel pump that supplies fuel 1 to the fuel injection valve is controlled by a microcomputer according to the operating state of the internal combustion engine. In an internal combustion engine, an abnormality detecting means detects that a microcomputer outputs an abnormal signal, and when the abnormality detecting means detects an abnormal output signal from the microcomputer, the driving force of the fuel pump is controlled to a high driving force side. and a driving force control means.

According to the present invention, when the abnormality detection means detects that the output of the microcomputer is abnormal, the driving voltage applied to the fuel pump is switched to a high voltage by the driving force control means, and the fuel pressure required by the engine is changed. Since the fuel pump acts on the pressure regulator, the pressure of the fuel can be properly regulated by the pressure regulator, and the appropriate amount of fuel can be injected from the fuel injection valve.

Example Embodiments of the present invention will be described based on the drawings.

In FIG. 1, fuel pumped from a fuel tank 1 by a fuel pump 2 is supplied to fuel injection valves 5a to 5f of each cylinder via a fuel filter 4 through a passage 3. The fuel pressure applied to the fuel injection valves 5a to 5f is controlled by a pressure regulator 6, and when the fuel pressure exceeds a predetermined value, the fuel is returned to the fuel tank 1 through a return passage 7.

The fuel pump controller 10, which controls the fuel pump 2 at high voltage, switches the performance of the fuel pump 2 based on a signal from the auxiliary signal generation circuit 11.

The operation of the auxiliary signal generation circuit 11 will be explained.

When the ignition switch 13 is turned on, the relay 14
is turned on, current from battery 15 is supplied to capacitor 16, and the voltage at terminal A gradually increases.

On the other hand, electronic control unit (ECU)
When a normal signal is output from >24, the terminal E becomes high level (see Figure 2), the input voltage of the comparator 25 becomes greater than the reference voltage O, and the output voltage of the comparator 25 becomes higher than the output terminal J. The voltage becomes high level, turning on the 1H transistor 26, thereby discharging the capacitor 16 and lowering the voltage to the terminal.

At this time, while the input voltage of the comparator 17 is lower than the reference voltage, the voltage at the output terminal B of the comparator 17 becomes low level, turning off the transistor 18 and keeping the arrays 19 and 20 off. When the voltage at the terminal A becomes lower and the reference voltage becomes lower than the input voltage 2.sup.2, the voltage at the output terminal C of the comparator 27 becomes high level, turning on the transistor 28. When the transistor 28 is turned on, the voltage at the terminal E gradually decreases, and the voltage at the terminal E becomes O■
When the voltage at the output terminal of the comparator 25 drops to 11-level, the capacitor 16 is charged by turning off the transistor 26, and the voltage at the terminal A rises again. When the voltage to the terminal exceeds 2■, the output terminal C of the comparator 27 switches to a low level, turning off the transistors 1-28.

For example, when the voltage to the terminal exceeds 4■, the input voltage of the comparator 17 becomes larger than the reference voltage 4■, and the comparator 17
output] becomes high level, which turns on transistor 18, turns on relay 19 and relay 20,
Current from battery 15 is supplied to the base of transistor 21 via relay 14 and relay 20. In other words, the transistor 21 is turned on, and the current supplied from the battery 15 via the relay 14 turns on the relay 22.
A relatively high voltage from the battery 15 is applied to the fuel pump 2 via a relay 22 that bypasses the resistor 23. In this way, when the capacitor 16 is charged and the voltage at the terminal A exceeds 4.times., the Tsuyuel pump controller 10 turns on the relay 22 that bypasses the resistor 23 to drive the fuel pump 2 at a high voltage.

The normal signal output from the ECU 24 is output at regular intervals, for example, every 10 m5ec, if the ECU 24 is operating normally. When a normal signal is output every 10 m5ec, the voltages generated at terminals A to F are as shown in the graph shown in FIG.

Next, FIG. 4 shows a main routine for determining whether or not the ECU 24 is outputting a normal signal.

First, initial settings are made in step 41, and then step 42
At step 43, the random access memory (RAM) is cleared and initial data is set, and at step 43, the counter is counted (immediately incremented by +1.Step 44).
The intake air fftQ, the engine speed N, and the load Q/N are calculated, and these detected data are set in the RAM, and the process proceeds to step 45, where +1 is added to the count value of the counter. When the process proceeds from step 45 to step 46, the ignition timing is calculated in step 46, and this calculated value is set in the RAM.Then, the process proceeds to step 47 and +1 is added to the count value of the counter. When the process proceeds from step 47 to step 48, the fuel injection time is calculated, and the calculated value of this fuel injection time is set in the RAM. Next, in step 49, +1 is added to the count value C of the counter. Next, in step 50, the next required amount of fuel for the engine is calculated from the engine speed N and the fuel injection time, and a signal is output to the transistor 21 so that the performance of the fuel pump can supply the required amount of fuel.

Next, in step 51, it is determined whether the count value of the counter is 4 or not, and if the callan 1-value is C≠4, the process returns to step 43. If the count value is C=4, the process goes from step 51 to step 52, sets the count value of the counter to O, and then goes to step 53, where EC
A normal signal is output from U24. In this way, each time the count value of the counter reaches 4, the ECU 24 outputs a normal signal at regular intervals, and as long as the count value of the counter does not reach 4, the ECU 24 outputs a normal signal. It is designed so that it will not happen.

Next, FIG. 3 shows the voltage generated at terminals A to E when an abnormality occurs in the ECU 24.

If an abnormality occurs in the ECU 24, the ECU 24 will no longer output a high-level signal as a normal signal at regular intervals, for example, every 10 ms, the voltage at the terminal E will remain at a low level, and the output terminal of the comparator 25 will The voltage remains at a low level, keeping transistor 26 off. Then, the content 16 is gradually charged, the voltage at terminal A rises, and the input voltage of the comparator 17 becomes the reference voltage 4V.
, that is, when, for example, 40m5ec has passed since the ECU 24 no longer outputs a normal signal,
Output terminal 2 becomes high level, turning on transistor 18 and turning on one relay and 20. As a result, battery current is supplied from battery 15 to transistor 21 via relays 14 and 20, transistor 21 is turned on, relay 22 is turned on, and high voltage is input to fuel pump 2.

In this way, for example 40 m5 from E CjJ 24
If a normal signal is output within ec, the comparator 17
The voltage at the output terminal B of is maintained at a low level, and by turning off the transistor 18 and keeping the relays 19 and 20 off, a normal relatively low voltage is applied to the fuel pump 2 from the battery 15 via the resistor 23. .

Normal signals are no longer output from the ECU 24, for example 4
When a normal signal is not output for more than 0 m5ec, the voltage at the output terminal B of the comparator 17 becomes high level, the transistor 18 is turned on, and the relays 1 and 20 are turned on. The transistor 21 is turned on, the relay 22 is turned on, and a relatively high voltage is applied from the battery 15 to the fuel pump 2 via the relays 14 and 22, thereby increasing the performance of the fuel pump 2. .

When an abnormality occurs in the ECU 24, the fail-safe function of the FCU 24 switches the fuel injection time, ignition timing, etc. to multi-stage switching or fixed conditions, and drives the fuel pump 2 at high voltage as described above. We are trying to improve its performance.

Therefore, during the period when the failleaf function is operating,
The amount of fuel supplied by the fuel pump 2 tends to decrease due to the fixed fuel injection time, but since the performance of the fuel pump 2 is driven on the high voltage side, the amount of fuel supplied due to insufficient fuel pressure can be reduced. This makes it possible to avoid a decrease in the air-fuel ratio and prevent A-bar lean in the air-fuel ratio. This eliminates the problem of the vehicle not being able to run on its own, and also reliably prevents abnormal increases in exhaust temperature and knocking due to over lean.

Effects of the Invention According to the present invention, when the microcomputer that controls the operating state of the internal combustion engine outputs an abnormal signal, the fuel pump drive voltage is set to a relatively large voltage. Eliminate the shortage of fuel supply due to
It is possible to forcefully send fuel in excess of the maximum fuel amount required by the engine from the fuel pump to the pressure regulator, thereby adjusting the amount of fuel injected from the fuel injection valve to an appropriate value,
It is possible to avoid over lean and ensure stable operating conditions in which excessive exhaust temperature rises, misfires, etc. hardly occur.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram of an embodiment of the present invention, Fig. 2 is a graph showing the normal voltages generated at each terminal in Fig. 1, and Fig. 3 is a graph showing voltages generated at each terminal in Fig. 1. FIG. 4 is a flowchart showing a routine for determining whether the ECU is outputting a normal signal in an embodiment of the present invention. 1...Fuel tank, 2...Fuel pump, 5
(5a to 5f)... Fuel injection valve, 6... Pressure regulator, 10... Fuel bomb controller, 11... Auxiliary signal generation circuit (driving force control means), 13... Ignition switch, 15...Battery power supply, 24...Electronic control unit (E
CU).

Claims (1)

[Claims] An abnormality that detects that the microcomputer has output an abnormal signal in a fuel pump control device for an internal combustion engine in which the driving force of the fuel pump that supplies fuel to the fuel injection valve is controlled by a microcomputer according to the operating state of the internal combustion engine. An internal combustion engine comprising: a detection means; and a driving force control means for controlling the driving force of the fuel pump to a high driving force side when the abnormality detection means detects an abnormal output signal of a microcomputer. fuel pump control device.