JPH02185645A - Device for controlling engine speed - Google Patents

Abstract

PURPOSE:To suppress the variation in idling engine speed by correcting an intake air quantity in accordance with the detected value of a generator current or the changing condition thereof while detecting the failure of a current detecting means and making the correcting quantity optimum. CONSTITUTION:An engine speed regulator 62 outputs a target intake air quantity Qt according to the deviation between the engine speed of an internal combustion engine 1 detected by an engine speed sensor 42 and the output of a target engine speed generator 5. On the other band, an intake air quantity regulator 120 detects a load current fed from a generator 101 to electric loads 141, 142 and a storage battery 130 by means of a current sensor 110 and calculates an intake air quantity Qe necessary for keeping the engine speed at the target value at the time of applying electric load and both intake air quantities Qt, Qe are added to drive a solenoid valve 8 via a driving device 7, thereby controlling idling engine speed. If the failure of the current sensor 110 is detected by a current-sensor failure detector 160, a fixed current value is given to the intake air quantity regulator 120. Thereby, the variation in idling engine speed can be suppressed to the minimum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an engine speed control device, and more particularly to a control device for maintaining the idle speed of an automobile internal combustion engine at a desired value.

[Prior Art] It is desirable to maintain the idle speed of an automobile internal combustion engine at an optimal value from various aspects such as vibration, noise, and fuel efficiency. Therefore, feedback control of the idle rotation speed has been conventionally employed to increase or decrease the amount of intake air to the engine based on the deviation between the actual engine rotation speed and the target rotation speed so as to reduce this deviation.

However, in such feedback control of the idle speed, there is a delay in detecting the speed and a delay in the response of the control valve that adjusts the amount of intake air, so it is difficult to turn on and off various electrical devices such as the car's headlights and motors. When the engine speed fluctuates due to a sudden increase or decrease in load, it takes time for the speed to settle to the desired value, so a temporary drop or spike in the speed is unavoidable. .

Conventionally, as described in Japanese Patent Application Laid-Open No. 59-155547, for example, the on/off state of each electrical load is detected, and the amount of air that bypasses the throttle valve is determined at the same time as the on state of each electrical load is detected. It has been proposed to suppress the increase in rotational speed fluctuations caused by turning on and off the electric load by increasing the rotational speed by a predetermined amount. According to this proposed control method, the switch signals of the open/close switches connected to each electrical load are input to an ECU (electronic control unit), and when the ECU receives the input of these switch signals, it Correspondingly, the increase value of the intake air amount to keep the engine speed at the desired value is stored in the memory, and the control amount of the control valve that adjusts the intake air amount is corrected to the increase side, and the intake air is immediately started. By adding air volume,
Rapid fluctuations in engine speed due to turning on and off of the electrical load are suppressed.

[Problem to be solved by the invention] The conventional device described above has the following problems.

(1) A large number of electrical loads are installed in a car, and if switch signals are input to the ECU in response to the amount of electrical loads, the number of input points will be large, and it will be expensive in terms of ECU.
It is also disadvantageous in terms of processing capacity of U.

(2) The amount of intake air required for each electrical load is stored in advance, but there are manufacturing variations in the electrical load, and operating temperature and other factors may cause actual engine load. The amount of intake air required is not constant. Therefore, the amount of intake air stored in advance may be too much or too little.

(3) When a plurality of electrical loads are applied, if control is performed by simply summing the amount of intake air required by each electrical load, the control may become excessive. This is because the actual load placed on the engine is determined by the amount of power generated by the generator energized by the engine, and when the generation capacity limit is exceeded, part of the current consumed by the electrical load is supplied from the battery and the load on the engine is increased. This is to prevent this from happening. In the above conventional example, this problem is prevented by setting an upper limit on the control amount, but if the power generation capacity of the generator varies,
Combined with the variations in electrical load described in section ), excess or deficiency of control II actually occurs.

(4) Since there is no means for determining whether a switch input corresponding to an electrical load has failed, an excess or deficiency occurs in the amount of intake air that should correspond to the electrical load in the event of a breakdown. The engine speed changes accordingly, and if the amount of intake air is too large, the engine speed will rise excessively, and if it is too little, the worst possible engine stall may occur.

This invention was made in order to solve the above problems, and by controlling the amount of intake air that is just the right amount in accordance with the amount of electrical load that actually acts as a load on the engine, it is possible to turn on the electrical load.・In addition to increasing the responsiveness of the rotation speed to off and suppressing rotation speed fluctuations, we also installed a device that can control the engine speed to the optimum value even if the means for detecting the electrical load on the engine fails. is intended to provide.

[Means for Solving the Problems] A rotation speed control device according to the present invention detects the rotation speed of an engine, and sets a control amount for intake air amount control in a direction that reduces the deviation between this and a desired rotation speed. Further, the output current of a generator driven by the engine is detected, and the intake air amount adjusting means of the engine is controlled by a control amount corrected by a correction value corresponding to this output current. When a predetermined fixed load is applied or removed, if the current detection value of the current detection means does not show a predetermined value corresponding to the application or removal of the fixed load, it is determined that the current detection means has failed. A failure determination means is provided for prohibiting the correction amount by the correction amount setting means or replacing it with a predetermined value.

[Operation] In this invention, the control room based on the rotation speed deviation is quickly corrected based on the amount of load actually applied to the engine, thereby suppressing rotation speed fluctuations caused by delays in rotation speed feedback control. . Further, when a predetermined fixed load is applied to or removed from the generator, if the detected value of the current detection means does not show a predetermined value corresponding to the fixed load, it is determined that the current detection means has failed and the corresponding one is detected. Fluctuations in engine speed are suppressed by inhibiting the amount of correction generated in response to the current detected by the current detection means or replacing it with a predetermined value.

[Example] Hereinafter, an example of the engine rotation speed control device according to the present invention will be described based on the drawings.

FIG. 1 is an overall configuration diagram of one embodiment. In this embodiment, a throttle valve 3 is provided in the intake passage 2 of the internal combustion engine 1.
is installed. The throttle valve 3 controls the engine speed in accordance with the load. In addition, a bypass passage 91. is provided in the intake passage 2 before and after the throttle valve 3.
92 is provided. Between the bypass passages 91 and 92, a solenoid valve 8 with a linear characteristic whose drive is controlled by the output of the drive device 7 is disposed as an intake air ffi adjustment valve.

On the other hand, the internal combustion engine I is provided with a gear 41 that is interlocked with the rotation of the internal combustion engine 1. The rotation of this gear 41 is detected by a rotation speed sensor 42. The rotation speed sensor 42 detects the rotation of the gear 41 and outputs the engine rotation speed n to the double signal deviation detector 61.

The output n of the target rotation speed setting device 5 is also input to the deviation detector 61 . The deviation detector 61 is the rotation speed sensor 42
Deviation △ between the output n6 and the output nt of the target rotation speed setting device 5
n is calculated and a deviation Δn signal is output to the rotation speed regulator 62.

The target rotation speed setting device 5 is for setting a target value of the no-load rotation speed, and the rotation speed regulator 62 is for setting the target value of the no-load rotation speed.
1, the rotation speed adjustment signal Q is applied in the direction of eliminating the rotation speed deviation Δn by proportional, integral, or differential operation.
, is generated. The output Qt of this rotation speed regulator 62 is sent to the addition 4 summer 50.

The generator 101 is driven by an engine l via a belt 102, and its output i is supplied to a battery 130 and electrical loads 141 and 142.

This electric load -141 has a fixed current consumption value, and a signal indicating that this load is connected to the generator 101 is sent to the current sensor failure determination unit 160.

The output current l of the generator 101 is detected by the current sensor 110, and the failure determiner 160 and the intake air amount regulator! 20 is entered.

The intake air amount regulator 120 generates an intake air amount adjustment signal Q based on the output i of the generator 101 detected by the current sensor 110. Then, the output Q of the intake air amount regulator 120 is converted to the output Qd of the rotation speed regulator 62 by the adder 150.
will be added. The output Q (, of the adder 150 is the drive device 7
The electric signal is converted into an electric signal and applied to the solenoid valve 8, and the amount of air flowing through the bypass passages 91, 92 is increased or decreased by duty control to adjust the intake air amount of the engine.

Next, the operation of the above embodiment will be explained.

The rotation speed regulator 62 adjusts the rotation speed n of the engine l and the target rotation speed n.
Based on the deviation Δn from t, the intake air amount is set in the direction in which the deviation Δn decreases, and this is set as the rotation speed adjustment signal Q1 to the adder! Output to 50. The output Q of the intake air amount regulator 120 is also input to the adder 150 .

The intake ffi adjustment a120 adjusts each electrical load 14 from the generator.
1.142 and eight. The current I supplied to the battery 130 is detected by the current sensor 110;1. It inputs this current value i and outputs the required amount of intake air Q, and its output characteristics are as shown in FIG. The relationship between the current I and the intake air IQ- determines the intake air amount increment required to maintain the engine speed at the target value when the internal combustion engine l is loaded by the generator 101 outputting the current i. For example, Q is determined by experiment, and is calculated using a function of Q,=f(f). As another method, it is possible to calculate Q by a method of storing i in advance and searching a numerical value table by one person.

The output Q"Q*+Q- of the adder 150 is the amount of intake air required by the engine, and is input to the drive device 7 and converted into a duty signal. FIG. 3 shows the characteristics of the drive device 7, and this The above relationship between Q and D is stored in advance. This relationship is based on the characteristics of the solenoid valve 8, and the average opening degree of the solenoid valve 8 is determined in response to a given duty D, so that a predetermined flow rate is achieved. This is what you get. Therefore,
When the solenoid valve 8 is driven with the duty D, the intake air amount of the engine substantially matches the output Q of the adder 150.

The characteristics of the rotational speed of the internal combustion engine controlled in this manner are as shown in FIG. As shown in the figure, when the load current i rapidly increases or decreases due to the opening and closing of the load, the intake air amount Q to compensate for this load and the actual intake air amount Qr of the engine quickly respond as shown by the solid line. Therefore, the rotation speed n does not vary as shown by the solid line. The characteristic shown by the broken line of the rotational speed n is the characteristic when the compensation of the present invention is not performed, and it fluctuates greatly depending on the opening and closing of the load. In the response to the intake air amount Q, what is shown by the dashed line is the surge tank 22 in the intake pipe 2.
is provided, and when this tank volume cannot be ignored, the amount of air actually taken into the internal combustion engine is delayed even if the solenoid valve 8 is controlled. In this case, in the initial stage of the response, there may be excess or deficiency in the amount of intake air, and the rotational speed n may show slight fluctuations as shown by the dashed line.

In order to suppress such fluctuations, it is necessary to speed up the response of the intake IQ, which compensates for the opening and closing of the load.

Next, a case will be described in which the current sensor 110 that detects the load current I of the generator 101 fails.

The feature of this rotational speed control method using the current sensor 110 is that the response speed is fast as described above, but on the other hand, when the sensor 110 fails, the fast response speed causes a problem.

In FIG. 5, the broken line indicates a state in which the minimum detected current value is continuously output when the current sensor 110 fails. In the figure, the solid line indicates the behavior when the sensor 110 is normal. The part (1) in the figure is a point where the load on the generator 101 increases, but when the current sensor 110 is normal, the intake air amount Q quickly increases in response to the increase in the current I, so the rotation The number n does not change. However, when the output of the current sensor 110 shows the minimum value due to a failure, as shown by the broken line, the intake air amount Q, which should correspond to the increase in load, does not change, so the rotation speed n, temporarily decreases. . As a result, a deviation Δn occurs between the target rotation speed and the engine rotation speed, so the rotation speed regulator 62 acts to restore the rotation speed to its original value, but if the load is large, Engine stall may occur due to a delay in the response of feedback control by the rotation speed regulator.

In addition, the point (2) in the figure is a point where the load on the generator 101 has decreased, and in normal conditions, the intake air amount Q rapidly decreases in response to the decrease in the current I, as shown by the solid line. The rotation speed n does not change. However, the current sensor! ! If the sensor output does not change due to a failure in 0, the intake air amount Q does not respond, and therefore the rotational speed n changes as shown by the broken line.
, rises temporarily. In this case as well, since the rotational speed deviation Δn occurs, the rotational speed regulator 62 acts to eventually return the rotational speed to its original value.

In this way, when the current sensor 110 outputs a value that does not correspond to an actual increase or decrease in the electrical load due to a failure, a temporary drop or rise in the rotational speed is unavoidable at the time of the erroneous output.

In order to avoid such problems, the present invention includes a current sensor failure determination device 16 that determines failure of the current sensor 110.
0 is set. Then, using the fixed load 141 whose current consumption value is determined in advance, a signal indicating the operating status of the fixed load 141 is transmitted to the current sensor failure determination unit 160.

Upon receiving this signal, the failure determination 160 determines whether the current sensor 11
If the zero output signal does not show a predetermined change in response to the application or removal of the fixed load 141, it is determined that the sensor 110 has failed, and a failure signal is transmitted to the intake air volume regulator 120 to reduce the electricity of the generator 101. The intake air amount Q corresponding to the load amount is prohibited.

In the above embodiment, when the current sensor 110 fails, the intake air amount Q is prohibited, but as shown by the dashed line in FIG. It may be replaced with a predetermined value corresponding to the average value, and in this case, the fluctuation range of the rotational speed n is smaller than when the intake air amount Q is prohibited.

Further, as shown by the solid line in FIG. 6, the output V of the current sensor 110 is offset by an amount v relative to the detected current value i.
v * (
v * < V +) may be set as the determination level, and when the sensor output is v < v, it is determined that there is a failure.
In that case as well, the same effects as in the above embodiment can be achieved.

[Effects of the Invention] As described above, according to the present invention, the current of the generator is detected, the intake air amount of the engine is corrected according to the current or the state of change of the current, and the malfunction of the current detection means is detected. Since the detection and the correction amount are optimized, the following remarkable effects can be obtained.

(1) Load fluctuations caused by turning on and off the electrical load can always be compensated promptly and accurately, and excellent rotational speed control without rotational fluctuations can be achieved.

(2) Since all electrical loads of the automobile can be detected and controlled by one current sensor, the control device can be simply configured.

(3) Even when multiple electrical loads are applied, the net load on the engine can be detected and appropriate compensation can be performed.

(4) Even when the current sensor fails, fluctuations in engine speed can be suppressed to a minimum.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of an embodiment of an engine speed control device according to the present invention, Fig. 2 is a characteristic diagram of an intake ffi regulator of the embodiment, and Fig. 3 is a characteristic diagram of a drive device of the embodiment. Figure, 4th
FIG. 5, and FIG. 6 are explanatory diagrams of the operation of the apparatus of the same embodiment and its modification. In the figure, 1 is an internal combustion engine, 42 is a rotation sensor, 5 is a target rotation speed setter, 61 is a deviation detector, 62 is a rotation speed regulator, 7 is a drive device, 8 is a solenoid valve, 101 is a generator, 110 is the current sensor, and 120 is the intake! regulator, 130
141 and 142 are electric loads, plate 50 is an adder, and 160 is a current sensor failure determination device.

Claims (1)

[Claims] (1) An intake air amount adjusting means for adjusting the intake air amount of the engine, a rotation speed detection means for detecting the rotation speed of the engine, and a rotation speed detecting means for detecting the rotation speed of the engine, and detecting the deviation based on the deviation between the detected rotation speed and the desired rotation speed. a control amount setting means for setting a control amount of the intake air amount adjusting means in a decreasing direction; a current detection means for detecting an output current of a generator driven by the engine; a correction value setting means for determining a correction amount of intake air necessary to maintain the engine speed at the desired value and setting a correction value for the control amount; and a control amount corrected by the output of the correction value setting means. a control means for controlling the intake air amount adjusting means based on the above, and a current detection value of the current detection means when a predetermined fixed load is applied or removed to the generator; If the current detecting means does not show a corresponding predetermined value, it is determined that the current detecting means has failed, and the correction amount by the correction amount setting means is prohibited or replaced with a predetermined value. Engine speed control device.