JPS59213935A - Control device for diesel engine - Google Patents

Abstract

PURPOSE:To enable an engine to be safely operated, by performing the decision of abnormality in a speed detection system after elapsed a prescribed time from the change into a starting mode. CONSTITUTION:A microcomputer 7, after being initialized by its stored control program, executes the program for discriminating whether or not an obstruction exists in the engine speed system of a Diesel engine 3. When existence of the obstruction is discriminated, a fuel cut valve 11 is closed. While if no obstruction is discriminated, an injection amount is calculated for its optimum control, and the optimum control of the injection amount of fuel is performed. When the existence of the obstruction in the speed detection system is discriminated, the position of a control sleeve 2a is controlled so that the injection amount may be decreased to 0 instead of its optimum control. In this way, even if the obstruction is caused existing in the speed detection system from the beginning, the abnormality can be detected within a little time at the initial statt, thus safety operation of the engine can be ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for an f easel engine, and more specifically, the present invention relates to a control device for an f easel engine, and more specifically, a diesel engine capable of controlling the start of the engine in response to a failure of a rotation speed sensor of the diesel engine. related to a control device.

Electronically controlled diesel engines, which are configured to adjust the amount of fuel injection based on electrical signals indicating engine speed, accelerator pedal pressure, and other operating parameters, have become widely used; In this case, when a failure occurs in the engine speed sensor, the output signal is the same as when the engine speed is zero, so it is extremely difficult for the control device to distinguish between the two. have. For this reason, as disclosed in Japanese Patent Application Laid-open No. 58-8237, for example, based on the fact that the engine rotational speed has reached a preset rotational speed or less in the small rotational speed region and the starter switch is off, A diesel engine control method has been proposed in which the amount of fuel supplied to the engine is reduced to zero to deal with an abnormality in the engine speed sensor. However, in this proposed control method, in a diesel engine control device having a general configuration in which the starting amount is increased when the key switch is set to 1 at the start position and the engine speed is below a predetermined rotational speed, If the engine speed sensor is malfunctioning from the beginning, an injection amount equivalent to zero engine speed will be supplied during the starting operation, and after starting, the engine rotational speed will increase rapidly, putting the engine in danger. There was a risk that the driver would end up in a dangerous driving situation.

Therefore, an object of the present invention is to provide a diesel engine capable of ensuring safe operation control of the engine even if a failure occurs in the sensor that detects the engine speed. The purpose is to provide a control device.

The present invention provides a control device for a diesel engine that is configured to electronically adjust the fuel injection amount when starting the engine based on at least an electrical signal related to engine speed and an operation signal from a key switch. a first means for determining whether an operating mode of the diesel engine is in a starting mode based on the electrical signal and the operating signal; and a first means for switching the key switch to a starting position in response to the operating signal. a second means for detecting whether a predetermined time (mask time) To has elapsed since the first
third means for supplying a predetermined amount of fuel for starting to the diesel engine when the operating mode of the diesel engine is in the starting mode in response to the output result from the means; and the output of the second means and the electric signal. in response to the above predetermined time T. a fourth means for checking the state of the electrical signal after the period of time has elapsed, and stopping the fuel supply by the third means if the fourth means detects that a malfunction has occurred in the electrical signal; The present invention is characterized in that it is provided with a fifth means for causing. According to this configuration, a predetermined time T elapses after the key switch is set to the start position. Until this period has elapsed, a predetermined amount of fuel for starting is supplied regardless of whether or not there is a failure in the speed detection means that outputs the electrical signal, and after that, the output state of the electrical signal is determined within a predetermined period of time. By checking, it is determined whether the rotation speed sensor is normal or not.
If it is determined that the rotational speed sensor is abnormal, fuel supply is stopped. In this case, the predetermined time To is preferably set to be longer than the time during which the battery voltage drops due to starter drive during the starting operation, and is preferably set to about 0.1 seconds, for example.

Hereinafter, the present invention will be explained in detail with reference to length examples.

FIG. 1 shows a schematic 1113 block diagram of an embodiment of a control device for a diesel engine according to the present invention.

This diesel engine control device l is a device that electronically adjusts the fuel injected and supplied from the distribution type fuel injection cylinder f2 to each cylinder of the diesel engine 3, and is a device that electronically adjusts the fuel that is injected and supplied to each cylinder of the diesel engine 3 at each top dead center timing of the diesel engine 3. A rotating pickup sensor 4 obtains a top dead center pulse signal P consisting of pulses output to the diesel engine 3 in response to the top dead center pulse signal P.
a speed signal generator 5 that outputs a speed signal S1 indicating the engine speed of the engine, and an operating condition detector 6 that outputs detection signals S2 to Sn that indicate the amount of accelerator pedal depression, the cooling water temperature of one engine, and other necessary operating condition parameters, respectively. It is equipped with code 7
The microcomputer is shown by the above-mentioned top dead center/f pulse signal P, the speed signal Sl, the detection signals S2 to Sn, and the operation signal A output from the key switch 8 and indicating the operation position of the key switch 8. is input to the microcomputer 7.

Based on these input signals, the microcomputer 7 has an injection amount control program that is designed to perform optimal injection amount control according to the operating status of the diesel engine 3 at any given time. In this case, a start control program is provided to handle this and ensure safe operation of the diesel engine 3. Control data D indicating the optimal injection amount at that time calculated by the microcomputer 7 is input to the governor circuit 8, and the control sleeve 2a of the distribution type fuel injection pump 2 is positioned at the position necessary to obtain the optimal injection amount. A drive current for driving the actuator 9 connected to the control sleeve 2a so that the control sleeve 2a is controlled is outputted from the governor circuit 8. As a result, control three 7
'2a is controlled by the actuator 9 to a position where the injection amount indicated by the control data D is obtained.

Further, when the startup control program detects that a failure has occurred in the speed detection system as described later, the fuel cut valve 11 disposed between the fuel tank IO and the fuel injection pump 2 is closed. A false drive signal C is output.

FIG. 2 shows a functional diagram showing the above-mentioned control functions by the microcomputer 7. As shown in FIG. The start mode determining means 21 determines whether or not the engine is in the start mode based on the speed signal S0 and the operation signal A. That is, the fact that the speed of the diesel engine 3 is smaller than a predetermined reference speed value set to a value lower than the idling speed and that the key switch 8 is in the start position indicates that the speed signal S and the operation signal A' are If both are detected, it is determined that the diesel engine 3 is in the start mode. The determination result is the optimum injection amount calculation means 2
2 is input.

The speed signal S and detection signals S2 to Sn indicating the operating conditions of the diesel engine 3 are inputted to the optimum injection amount calculation means 22, and in response to these input signals, control is performed to indicate the optimum injection amount at the time. Output data D. When the start mode determining means 21 determines that the engine 3 is in the start mode, the optimum injection amount calculating means 22 outputs data indicating the optimum injection amount for starting at that time. Therefore, the diesel engine 3 is controlled according to the control data D from the optimum injection amount calculation means 22, respectively, at the time of starting and after starting.

A timer means 23 and a failure determination means 24 are further provided so that failures and other abnormalities in the speed detection system can be reliably detected. The operation signal A is input to the timer means 23, and in response to the key switch 8 being switched to the start position, the timer means 23 is started and a predetermined time (mask time) To is measured. . This measurement result is input to the failure determination means 24 to which the speed signal S1 is input.

The failure determination means 24 is a means for determining whether or not there is a failure in the speed detection system based on the state of the speed signal s1, and this determination operation is performed by the timer means 23 after the key switch 8 is switched to the start position. Mask measured at time T. is carried out within a predetermined period of time after . Only if it is determined that there is a fault in the speed detection system within this time, the fuel cut valve 1] is closed by the control signal C, the fuel supply to the fuel injection pump 2 is cut off, and the control signal C is also applied to the optimum injection amount calculating means 22, and control is performed so that the position of the control sleeve 2a is at the zero injection amount position, and the rotation of the diesel engine 3 is stopped.

FIG. 3 shows a flowchart of a control program stored in the microcomputer 7 of the apparatus shown in FIG. This control program consists of step a
After initialization is performed in the fault determination Stella 7ab
In step C, a program is executed to determine whether or not there is a failure in the engine speed detection system of the diesel engine 3. As a result, if it is determined in step C that there is a failure, the fuel cut valve 11 is closed (step C). , zod). On the other hand, if it is determined in step C that there is no failure, calculation for optimal control of the injection amount is performed in the stellar 76e, and optimal control of the fuel injection amount is performed according to the result. In step e, if it is determined in step C that there is a failure 1) in the speed detection system, instead of optimal control, the position of the control sleeve 2a is controlled so that the injection amount becomes zero.

The interrupt program INT is a program that is executed every time each pulse of the top dead center pulse P is input to the microcomputer 7. First, the control of the diesel engine 3 sets the key switch 8 to the start position, and then It is determined in step f whether or not the mask time is within the mask time until the time T0 has elapsed.

If the determination result is YES, the program returns to the main program. If the determination result is NO, the TDC flag is set (step g) and the program returns to the main program.

FIG. 4 shows a detailed flowchart of the failure determination step shown in step b in FIG. In this failure determination step fb, first, in step b1, it is determined whether the engine speed N is 5 Or, p, m or less, and if the determination result is YES, the Stella f
At b2, it is determined whether the key switch 8 is at the start position.

If the determination result in step bl is N9, step C
Proceed to. If the determination result in step b2 is No, the process proceeds to Stella 7'b4, where predetermined initialization such as resetting each flag is executed. Step b3.

After executing b4, the process proceeds to step C.

If the determination results in steps b and b2 are both YES, it is determined that the engine is in the start mode, and in step b5 it is determined whether or not the predetermined mask time has ended based on the mask flag described later. It is determined based on If the determination result in step b5 is NO, the counter CTR
1 is subtracted from the content of , and it is determined whether the result is greater than a predetermined value nJ (step ba). This counter CTR is set to a predetermined value larger than n in step a of the program shown in FIG. After the time T0 has elapsed, the content becomes n. When the contents of the counter CTR-1 become equal to or less than the predetermined number n, the process proceeds to step b7, where a mask flag indicating the end of the mask period is set, and the process proceeds to the next step C. The contents of counter CTR-1 are a predetermined number n,
If it is determined that l:υ is large, the process directly proceeds to step C.

In step b5, when it is confirmed that the mask flag is set and it is determined that the mask time has ended, step b
At step 8, it is determined whether or not the TDC flag is set, and if the TDC flag is set, the process proceeds to step C. This is the case when the engine speed detection system of the diesel engine is normal.

If the TDC flag is still set even after the mask time ends, the determination result in step bs will be No.
In this case, it is determined whether the contents of CTR-1 have become zero (step b9), and if the determination result is YES, it is determined that a failure has occurred in the engine speed detection system, Set a failure flag (step b+o). On the other hand, if the determination result in step b9 is NO, the process proceeds to step C without setting the failure flag. In other words, if the TDC flag is not set, the failure is not determined until the contents of the counter CTR reach zero, and the TD is determined when the contents of the counter CTR reach zero.
If the C flag is not set, a failure flag is sent. This is because the period from when the contents of the counter CTR goes from n to zero is given as a grace period to determine whether or not a failure has occurred in the engine speed detection system, and even if this grace period has just ended, First, the failure flag is set only when the TDC flag is in the reset state.

As can be seen from the above explanation, the time To from when the content of the counter CTR, which has been set to a predetermined initial setting value, begins to be subtracted in response to switching to the start position of the key switch until it reaches n, is shown in Fig. 2. This corresponds to the mask time set by the timer means 23 shown.

According to the present invention, as described above, within the mask time from when the start mode is entered until a predetermined time elapses, the required start is performed regardless of whether or not there is a failure in the speed detection system of the diesel engine. The mode engine is operated, and the presence or absence of a failure in the speed detection system is determined after the mask time has elapsed. Since the abnormality is detected, the required knock-aggregation process is performed, which provides an excellent effect of ensuring safe operation of the engine.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a schematic configuration diagram of an embodiment of a diesel engine control device according to the present invention, FIG. 2 is a functional diagram showing the control function of the microcomputer shown in FIG. 1, and FIG. The figure is a flowchart of a control program stored in the microcomputer shown in Figure 1 to perform control according to the functional diagram shown in Figure 2, and Figure 4 is a flowchart of a control program stored in the microcomputer shown in Figure 3. It is a detailed flowchart of a determination step. DESCRIPTION OF SYMBOLS 1...Diesel engine control device, 2...Fuel injection pump, 3...Diesel engine, 4...Rotating pinoquag sensor, 5...Speed signal generator, 6...Driving east Detector, 7: Microcomputer, 8: Key switch, 8: Governor circuit, 9: Actuator,
DESCRIPTION OF SYMBOLS 11...Fuel cut valve, 21...Start mode discrimination means, 22...Optimum injection amount calculation means, 23...Timer means, 24...Failure discrimination means, A...Operation signal, C ...Control signal, D...Control data, P...Top dead center pulse signal, S, ...Speed signal, S2 to Sn.
...Detection signal.

Claims (1)

[Claims] 1. A diesel engine control configured to electronically adjust the fuel injection amount at the time of starting the diesel engine based on at least an electrical signal related to the engine speed of the diesel engine and an operation signal from a key switch. The apparatus includes: a first means for determining whether the operating mode of the diesel engine is in a starting mode based on the electrical signal and the operating signal; and switching the key switch to a starting position in response to the operating signal. a second means for detecting whether a predetermined time has elapsed since the diesel engine was started; and a second means for starting the diesel engine when the operating mode of the diesel engine is in the starting mode in response to the output result from the first means a third means for supplying a predetermined amount of fuel for the time;
fourth means for checking the state of the electric signal after the predetermined time has elapsed in response to the output of the second means and the electric signal; and a malfunction has occurred in the electric signal in the fourth means. and a fifth means for stopping the fuel supply by the third means when this is detected.