JPS635137A - Fuel injection device for diesel engine - Google Patents

Abstract

PURPOSE:To enable stable running of a vehicle even during the failure in operation of a control part, by providing a control part, setting a fuel injection timing and an injection amount, a check means, detecting the failure in operation of the control part, and other control part, controlling a fuel injection timing on particular conditions. CONSTITUTION:A control part 1 having a CPU sets a fuel injection timing and an injection amount. A CPU check circuit 8 controls switching of an output switching relay 9 according to the motion state of the CPU. A control part 17 adjusts a crank angle to a specified value for a fuel injection period by means of the same accel opening. When the failure in operation of the control part 1 having the CPU is detected by means of the check circuit 8, other control part 17 is switched for operation. This constitution enables ensurance of the feed of fuel by mean of injection characteristics, by the use of which stable operation in practicable even during the failure in operation of the control part 1.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to a diesel engine using an electromagnetic spill valve, which enables injection characteristics to be stably operated even when a CPU control unit fails. It relates to a fuel injection device.

[Conventional technology]

A conventional fuel injection device for a diesel engine that controls fuel injection timing and fuel injection amount using an electromagnetic spill valve is configured as shown in FIG. 4, for example. That is, C
The output from the accelerator sensor 22 and the pulse output from the crank angle sensor 23 are input to the control unit 21 including the PU, and fuel injection is performed based on the engine rotation speed calculated from the accelerator sensor output and the crank angle sensor pulse output. The timing and injection amount are required. From this result, a predetermined injection start crank position and injection end crank position are further determined, and the injection start crank position and injection end crank position are detected by the outputs of the crank position sensor 24 and crank angle sensor 23. During the predetermined injection period, when the starting crank position is reached, the electromagnetic spill solenoid 25 is energized, the TM spill valve 26 is closed, and the pressure feeding of fuel is started, and the injection nozzle disposed in the engine 27 is The fuel injection is started from 28, and when a predetermined injection end crank position is reached, the electromagnetic spill valve is opened to end the fuel injection.

[Problem that the invention seeks to solve]

Since the diesel engine fuel injection system using an electromagnetic spill valve has the above-mentioned configuration and operating principle, an electric control circuit is an essential component and it also provides the good fuel injection characteristics necessary for the engine. This requires a controller capable of complex control using a CPU or the like.

By the way, in electronic fuel injection control devices that control the injection amount and injection timing using a conventional control sleeve and timer hydraulic control, fuel injection to a certain extent is possible even if the controller fails, but electromagnetic spill Fuel injection devices using valves do not have such a function.

therefore,! When using a fuel injection system using an M1 spill valve, if the controller fails, the engine will stop. In a vehicle engine, whether or not it can run on its own in the event of a failure is an important issue.
! It is an extremely troublesome problem that the engine stops due to a failure of the controller in the 1-magnetic Spicy spill valve fuel injection system.

Conventionally, Japanese Patent Publication No. 60-502162 discloses a fuel supply system for an internal combustion engine configured to switch the drive of the fuel injection valve to the injection pulse obtained from the ignition device of the internal combustion engine when the control section fails. A control device is proposed. However, such fuel supply AM devices are subject to many restrictions when performing emergency driving by switching the injector drive means in the event of a failure of the control unit, making it impossible to perform stable and safe driving. .

The present invention was made in order to solve the above-mentioned problems in the conventional fuel injection device using an electromagnetic spill valve.
It is an object of the present invention to provide a diesel engine fuel injection device using an electromagnetic spill valve that can supply fuel with fuel injection characteristics that enable stable running even when a control unit including a U is out of order.

[Means and effects for solving the problems] In order to solve the above problems, the present invention provides a fuel injection device for a diesel engine equipped with a control section having a CPU, which includes: a means for checking the CPU of the control section; and another control section that makes the fuel injection period a constant crank angle at the same accelerator opening, and is configured to switch and use the other control section when the checking means detects a failure in the control section having a CPU. It is something to do.

By configuring the diesel engine fuel injection system in this way, even if the control unit including the CPU fails, it is possible to switch to another control unit that maintains the fuel injection period at a constant crank angle with the same accelerator opening. , it is possible to ensure fuel injection by having injection characteristics that allow stable and safe driving, such that the injection amount decreases at high speed rotation.

〔Example〕

Examples will be described below. FIG. 1 is a circuit configuration diagram showing an embodiment of a fuel injection device using an electromagnetic spill valve according to the present invention. In FIG. It receives each detection signal from the crank angle sensor 3 and crank position sensor 4 and sends out an output signal that controls the fuel injection timing and injection amount by the electromagnetic spill valve. In addition, 5.6
7 is a circuit that shapes the waveform of each detection signal from the crank angle sensor 3 and the crank position sensor 4, and 7 is a constant voltage circuit that supplies voltage applied to the accelerator sensor 2.

Reference numeral 8 denotes a CPU check circuit that switches and operates the output switching relay 9 according to the operating state of the CPU. This C
The PU check circuit 8 is configured as follows, for example. In other words, it uses a timer that is activated by a signal output from the CPU at a constant cycle. After activation, the timer has a set time that is longer than the signal cycle of the CPU, and from the time of activation until the set time, the timer is activated by the output switching relay. 9 on the CPU side, and after a set time, on the output side of a control section that does not involve the CPU, which will be described later. When it starts up again after startup, the elapsed time count up to that point is cleared and the elapsed time count starts again. Therefore, if the signal from the CPU is normal, the relay 9 that always switches the output will be on the CPU output side, and the
If the CPU signal is lost due to a failure of the PU, etc., the output cut-off relay 9 is configured to switch.

10 is a counter for counting output pulses from the crank angle sensor 3, and is configured to be started by an output pulse signal from the crank position sensor 4. 11
is a digital comparator that compares the count value of the counter 10 with a predetermined set value. When the count value is greater than the set value, the output is turned ON, and when it is smaller than the set value, the output is turned OFF.
It is assumed to be FF.

12 is the output of the crank angle sensor 3 and the digital comparator 11
A one-shot circuit receives the output of an AND gate 15 which receives the output of the one-shot circuit 12 as an input, and 13 is an integrating circuit that integrates the output of the one-shot circuit 12. 14 is the accelerator sensor 2
is an analog comparator that compares the output of the integrating circuit 13 with the output of the accelerator sensor 2. If the output of the integrating circuit 13 is smaller than the output of the accelerator sensor 2, the output is turned ON, and the output of the integrating circuit 13 is larger than the output of the accelerator sensor 2. If so, turn off the output.
F. Reference numeral 16 denotes an AND gate which receives the output of the analog comparator 14 and the output of the digital comparator 11, and its output terminal is connected to the other contact of the output switching relay 9. Then, the counter 10° digital comparator 11. One-shot circuit 12. Integrating circuit 13
．． With analog comparator 14 and AND gates 15 and 16,
This constitutes an injection control section 17 that does not involve a CPU.

Next, the operation of the fuel injection system using the electromagnetic spill valve configured as described above will be explained. First, if the CPU check circuit 8 determines that the CPU of the control unit 1 is operating normally, the
An output signal for driving the electromagnetic spill valve is sent out by the section 1 via the output switching relay 9.

On the other hand, if the CPU check circuit 8 determines that the CPU of the control unit 1 is malfunctioning, the output switching relay 9 is switched and the output signal to the electromagnetic spill valve is the output signal from the control unit 17 that does not go through the CPU. can be switched to

In the control unit 17, a counter 10 starts with a pulse signal obtained by waveform shaping the detection signal from the crank angle sensor 4, and counts the pulse signal obtained by waveform shaping the detection signal from the crank angle sensor 3. . The count value of the counter 10 is compared with a predetermined set value in the digital comparator 11, and when it becomes larger than the set value, that is, when the counter 10 counts a certain number, the output of the digital comparator 11 is turned ON. As a result, the output gate 16 is opened and an output signal is sent to the electromagnetic spill valve.

Meanwhile, at the same time, the AND gate 15 is opened and the output pulses from the crank angle sensor 3 begin to be sent to the one-shot circuit 12. The output pulse of the one-shot circuit 12 is integrated by the integrating circuit 13 to generate a voltage proportional to the number of pulses from the crank angle sensor 3 after the start of sending the output signal to the electromagnetic spill valve, and the voltage is sent to the analog comparator 14. give. The analog comparator 14 compares this voltage with the accelerator sensor output, and when the integrated voltage value exceeds the accelerator sensor output voltage, closes the output gate 16 and turns off the output signal to the electromagnetic spill valve.

FIG. 2 is a timing chart showing operation waveforms of the control section 17 at the positions indicated by A-G in FIG.

In this way, when the CPU fails, the electromagnetic spill valve is controlled by the output signal from the control unit 17 without going through the CPU, so even when the CPU fails, fuel can be continuously supplied. Moreover, in the fuel injection control by the control unit 17, as described above, the injection timing is constant, the injection period is independent of the rotation speed, and the crank angle is almost the same at the same accelerator opening, so this is controlled over time. Expressed as follows, the injection time becomes shorter as the rotation becomes higher, and injection characteristics as shown in FIG. 3 are obtained.

This characteristic is due to the fact that the injection amount decreases at high rotation speeds.
Stable running is possible, and no abnormal revving occurs.

C Effects of the Invention] As described above based on the embodiments, according to the present invention, in a diesel engine fuel injection system using an electromagnetic spill valve, when the CPU control section 'B' fails, fuel injection is performed at the same accelerator opening. Since the electromagnetic spill valve is configured to be controlled by an output signal from the control unit that does not involve the CPU and has a period of a constant crank angle, fuel can be supplied with injection characteristics that allow stable operation even when the CPU is out of service. can be secured.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram showing an embodiment of a diesel engine fuel injection device according to the present invention, FIG. 2 is a timing chart showing operating waveforms in each part of the device shown in FIG. 1, and FIG. 1 is a diagram showing fuel injection characteristics obtained by the device shown in FIG. 1, and FIG. 4 is a diagram showing an example of the configuration of a fuel injection device using a general electromagnetic spill valve. In the figure, 1 is a CPU control unit, 2 is an accelerator sensor, 3 is a crank angle sensor, 4 is a crank position sensor, 5.6 is a waveform shaping circuit, 8 is a CPU check circuit, 9
is an output switching relay, 10 is a counter, 11 is a digital comparator, 12 is a one-shot circuit, 13 is an integration circuit, 14
15 and 16 are AND gates, and 17 is a control section.

Claims (1)

[Claims] a control unit having a CPU that receives output signals from an accelerator sensor, a crank position sensor, and a crank angle sensor and sets fuel injection timing and injection amount; and a checking means for the CPU of the control unit, and a control unit that injects fuel at the same accelerator opening degree. The diesel engine is characterized in that the diesel engine is characterized in that the diesel engine is equipped with another control section whose period is a constant crank angle, and when the checking means detects a failure of the control section having a CPU, the other control section is switched and used. Engine fuel injection system.