JPS6232340B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an engine rotational speed control device that controls the rotational speed of an engine during idling based on the outputs of various sensors that detect engine conditions and the like.

[Conventional technology and its problems]

Conventional engine speed control devices during idle have a configuration in which a mechanical auxiliary air valve is installed in an auxiliary air conduit that bypasses the throttle valve to limit the amount of auxiliary air depending on the engine temperature, and the engine speed is controlled by a program. .

Since this conventional device is program controlled, its only function is to increase the idle speed for an appropriate period after the engine is cold started. For example, if an engine-driven compressor for an automobile air conditioner or other engine-driven control equipment is connected to the engine at idle, a separate auxiliary air conduit and auxiliary Either an air valve was installed to increase the idle rotational speed, or the reduction in rotational speed was ignored and no auxiliary air conduit was installed and no auxiliary air was supplied.

As a result, a system in which an auxiliary air conduit is added separately has a complicated structure, and a system in which an auxiliary air conduit is not additionally installed has problems such as rotational speed fluctuations that cannot be ignored, resulting in engine stall.

[Purpose of the invention]

The present invention has been made in view of the above points, and has a simple configuration that allows control of the idle rotation speed using a control parameter indicating the engine state including at least the warm-up state of the engine, and eliminates the need to provide a control device for each purpose. It is an object of the present invention to provide an engine rotation speed control device that can improve reliability and accurately control the engine rotation speed.

Another object of the present invention is to provide an engine rotational speed control device that can control the rotational speed within a predetermined range even when rotational speed control becomes impossible due to a failure of a rotational speed sensor or the like.

[Structure of the invention]

In order to achieve the above object, the present invention includes an air amount control means for controlling the amount of air taken into the engine, an engine rotation speed detection means for detecting the engine rotation speed, and at least a warm-up state of the engine. an engine condition detector that outputs a signal according to the engine condition; a target rotation speed setting device that sets a target rotation speed during idling according to the signal of the engine condition detector; and the engine rotation speed detection device Comparing means for comparing the engine rotation speed detected by the engine rotation speed and the target rotation speed set by the target rotation speed setting means;
control amount setting means for setting a control amount so that either the engine rotational speed or the target rotational speed disappears based on the comparison result of the comparison means; drive control means for controlling the drive of the air amount control means; and a predetermined upper limit that changes the control amount set by the control amount setting means in response to a signal corresponding to a warm-up state in the engine state detector. The engine rotation speed control device is characterized in that it includes a limiting means for limiting the engine speed to a range between the value and the lower limit value.

[Example] An example of the present invention will be described below based on the drawings. In FIG. 1, an engine 10 is a known four-stroke reciprocating spark ignition engine, which takes in main air through an air cleaner 11, an air flow meter 12, an intake pipe 13, a surge tank 14, and each intake branch pipe 15, and fills it with fuel, e.g. Gasoline is injected and supplied from electromagnetic fuel injection valves 16 provided in each intake branch pipe 15.

The main intake air amount of the engine 10 is regulated by a throttle valve 17 which is arbitrarily operated, while the fuel injection amount is regulated by an electronic fuel control unit 20. The electronic fuel control unit 20 uses a known system that determines the fuel injection amount using the engine rotational speed measured by the distributor 18, which serves as a rotational speed sensor, and the intake air amount measured by the airflow meter 12 as basic parameters. Other warm-up sensor 19, throttle sensor 25
The fuel injection amount is increased/decreased based on the input signals from the various sources.

The air conduits 21, 22 are provided so as to bypass the throttle valve 17, and an air control valve 30 is provided between the two conduits 21, 22. In other words, one end of the conduit 21 is connected to an air inlet 23 provided between the throttle valve 17 and the air flow meter 12, and one end of the conduit 22 is connected to an air outlet 24 provided downstream of the throttle valve 17. It is connected.

The air control valve 30 is basically a diaphragm type control valve, and transmits the displacement of a diaphragm 33 whose outer periphery is wound between housings 31 and 32 to a valve body 35 via a shaft 34, 36 is of the type that opens and closes. diaphragm 33
is rotated by the pressure difference between the chambers 37 and 38, and is biased by a compression coil spring 40 via a spring tray 39, thereby applying a closing force to the valve body 35.

A diaphragm 33 is provided between the housings 31 and 32.
A holding plate 41 is secured together with the holding plate 41, and the shaft 34 is airtightly guided by a sleeve 42 provided on the holding plate 41. Further, a small hole 43 is formed in the holding plate 41, and the atmosphere is introduced into the chamber 37 through this small hole 34.

Note that the valve body 35 is a needle valve, and the valve seat 3
6 is continuously changed with respect to the amount of displacement of the shaft 34.

Furthermore, the air control valve 30 includes an electromagnetic mechanism 50 that indirectly changes the opening degree of the valve body 35.
This electromagnetic mechanism 50 includes an electromagnetic coil 51 wound around a resin bobbin and fixed to the housing 31.
a fixed iron core 52 disposed at the center of the electromagnetic coil 51; a leaf spring 54 made of a magnetic material and fixed to the housing 31 with a pin 53; It is composed of tubes 55 and 56. The leaf spring 54 closes the tube 56 by its own spring force when the electromagnetic coil 51 is not energized, and closes the tube 55 by electromagnetic force when the electromagnetic coil 51 is energized. Here, the tube 55
is open to the atmosphere for conducting atmospheric pressure into the chamber 38, while the pipe 56 is connected to the surge tank 14 via a pipe 57 for conducting negative intake pressure into the chamber 38.

Therefore, the air control valve 30 controls the opening degree of the valve body 35 (that is, the amount of auxiliary air that bypasses the throttle valve 17) depending on the magnitude of the pressure within the chamber 38. The length is determined by the proportion of time that the tube 56 that guides the intake negative pressure is opened, that is, the proportion of time that the electromagnetic coil 51 is energized.

Excitation of the electromagnetic mechanism 50 is controlled by an electronic air control unit 60. This electronic air control unit 60 includes a distributor 18 and a warm-up sensor 19 that detects the engine temperature, that is, the warm-up state.
and an air conditioning switch 28 that turns on and off an electromagnetic clutch 27 that connects a compressor 26 for an air conditioner such as an automobile cooler and a drive shaft of the engine 10, and outputs an engine rotation speed signal, a cooling water temperature signal, and a throttle signal. And an air conditioner on/off signal is input.

Next, the electronic air control unit 60 will be explained in detail with reference to FIG. Reference numeral 100 denotes a D-A conversion circuit, into which an intermittent signal synchronized with engine rotation from an ignition distributor 18 is input, and this signal is passed through a waveform shaping section consisting of resistors 101, 102, 103, 104, a capacitor 106, and a transistor 108. After waveform shaping as shown in FIG. 3A, capacitors 107, 111, diodes 109, 110,
A resistor 105 outputs from terminal B the voltage shown in FIG. 3B, which is a superposition of a voltage proportional to the engine rotational speed and a sawtooth voltage synchronized with the engine rotation (intermittent signal). That is, when the engine rotation speed is high, a sawtooth wave voltage synchronized with the engine rotation with a high variable voltage level is output, and when the engine rotation speed is low, a sawtooth wave voltage synchronized with the engine rotation with a low average voltage level is output. . Reference numeral 200 denotes a function voltage generation circuit, into which the output signal of the warm-up sensor 19 and the on/off signal of the air conditioning switch 28 are input, and the output of the warm-up sensor 19 is sent to a well-known amplifier circuit 20.
1 and becomes a voltage signal corresponding to the engine warm-up state. This voltage signal is outputted via a resistor 202 and a diode 203, and the on/off signal from the air conditioning switch 28 is outputted via a resistor 204 and a diode 205 to a first comparison circuit 300, which will be described later.
A comparison level D of the comparison circuit 300 is given. The first comparison circuit 300 includes resistors 301, 302, 303,
The comparator 304 compares the output voltage of the DA conversion circuit 100 and the function voltage of the function voltage generation circuit 200. As shown in FIG. 4, the output characteristic of the functional voltage generation circuit 200 is as shown in the solid line in FIG. 4 when the air conditioning switch 28 is off; In this case, the output voltage increases as shown by the broken line in FIG. In the first comparison circuit 300, the third
As shown in FIG. C, a signal C is output which is at the "0" level only during the period when the output voltage of the DA converter circuit 100 is lower than the comparison level D, and is at the "1" level only during the period when the output voltage is higher than the comparison level D. That is, the voltage signal (comparison level D) corresponding to the set circuit speed commensurate with the current engine state output from the functional voltage generation circuit 200 and D-A
By comparing the sawtooth wave voltage synchronized with the engine rotation having an average voltage level proportional to the engine rotation speed from the conversion circuit 100, it is possible to determine whether the current engine rotation speed is higher or lower than the set rotation speed. Specifically, when the average voltage level of the sawtooth wave voltage is higher than the comparison level D, the output signal from the first comparison circuit 300 is at the "0" level. The ratio with the "1" level is higher in the "1" level, and it is determined that the current engine rotation speed is higher than the set rotation speed, and conversely, the average voltage level of the sawtooth wave voltage is lower than the comparison level D, the ratio of the output signal from the first comparison circuit 300 to the "0" level and the "1" level is such that the "0" level is higher than the current engine rotation. It is determined that the speed is lower than the set rotational speed. Also, the first comparison circuit 3
The ratio between the "0" level and the "1" level of the signal C from 00 indicates the degree of deviation between the set rotation speed and the current engine rotation speed, and controls the energization to the electromagnetic mechanism 50 described later. This signal C is used to create a control signal. Reference numeral 400 denotes an integrating circuit that charges or discharges a capacitor 401 at a constant current according to the signal C, and includes resistors 402, 403, 404, and a transistor 40 as a constant current charging circuit that operates when the signal C is at the "0" level.
9, resistors 405, 406, 407, a diode 408, and a transistor 410 as a constant current discharge circuit that operates when the signal C is at the "1" level. As shown by the broken line in FIG. 3E, this integrator circuit 400 has a capacitor 401 charged with a constant current while the output signal C of the comparator circuit 300 is at the "0" level, so the output voltage E increases and the output signal increases. When the level is "1", the capacitor 401 is discharged at a constant current, and the output voltage E is lowered. 500
As shown by the solid line in FIG. 3E, the voltage E that outputs the triangular wave voltage F with a constant period and the triangular wave voltage F of the oscillator 500 are input, and the second voltage is compared.
The comparator circuit is composed of a resistor 601 and a comparator 602, and outputs a pulse signal G that is at the "1" level only during a period when the output voltage E of the integrating circuit 400 is greater, as shown in FIG. 3G. 700 is an amplification circuit using an inverting amplifier 701 that inverts and amplifies the signal G of the second comparator 600, and the output after amplification is sent to the air control valve 30.
is supplied to the electromagnetic coil 51 of the electromagnetic mechanism 50.
800 is a voltage control circuit, which includes resistors 801, 802,
803, 804, and diodes 805, 806. Since the resistor 804 is connected to the output of the amplifier circuit 201 that outputs a voltage signal according to the engine warm-up state of the functional voltage generating circuit 200, the resistor 804 is connected to the connection terminal H between the resistors 801 and 802 and
The potential of the connection terminal J between 02 and 803 is
If the values of 1,802,803 are appropriately selected, characteristics depending on the engine temperature, that is, the warm-up state of the engine, can be obtained as shown in FIG. With this configuration, when the potential of the capacitor 401 of the integrating circuit 400 rises and exceeds the potential of the connection end H, the diode 805 becomes conductive, and the potential of the capacitor 401 eventually rises above the potential of the connection end H. I can't do it,
On the other hand, even if the potential drops, it cannot drop below the potential at the connection end J, and thus the voltage amplification of the capacitor 401 can be limited.

Next, the operation of the above-mentioned constituent device will be explained. When the engine 10 is in idle operation with the throttle valve 17 closed, the idle rotation speed is a function of the electronic air control unit 60 and the voltage generation circuit 20.
When the rotation speed is lower than the set rotation speed corresponding to the comparison level D determined by 0, the average voltage level of the sawtooth wave voltage output from the terminal B of the DA conversion circuit 100 is also low, and is lower than the comparison level D. The state will be as follows. Therefore, as shown in the center of FIG. As shown in the center of FIG. 3C, is always at the "0" level, or even if it is at the "1" level, the period of the "1" level is very short. As a result, the output voltage E of the integrating circuit 400 is as shown in FIG. Therefore, in the second comparator circuit 600, the integrated voltage E is larger than the triangular wave voltage F of the oscillator 500 during a period T (when the comparator 602 is "1").
level) increases, and the proportion of time during which the electromagnetic coil 51 of the electromagnetic mechanism 50 of the air control valve 30 is energized increases, which means that the opening degree of the air control valve 30 increases and assists bypassing the throttle valve 17. The amount of air increases, and the amount of fuel injected from the electromagnetic fuel injection valve 16 also increases in accordance with this increase in the amount of air, so the rotational speed of the engine 10 increases. On the other hand, when the engine rotation speed is higher than the set rotation speed, the average voltage level of the sawtooth wave voltage output from terminal B of the D-A conversion circuit 100 is higher than the set rotation speed, as shown on the right side of FIG. 3B. Therefore, the waveform of the sawtooth voltage is always higher than the comparison level D, or is lower than the comparison level D for a short time, and the output signal of the first comparison circuit 300 is always " The period of the “1” level or “0” level is very short, and as a result, the output voltage E of the integrating circuit 400
is decreasing as shown by the broken line on the right side of Figure 3E. Therefore, in the second comparison circuit 600, the oscillator 5
The period T during which the integrated voltage E is greater than the triangular wave voltage F of 00 (that is, the period during which the comparator 602 is at the "1" level) decreases, and the electromagnetic coil 51 of the electromagnetic mechanism 50 of the air control valve 30 is energized. The time ratio decreases, that is, the opening degree of the air control valve 30 decreases, the amount of auxiliary air bypassing the throttle valve 17 decreases, and in response to the decrease in the amount of air, the fuel injection from the electromagnetic fuel injection valve 16 decreases. Since the amount also decreases, the rotational speed of the engine 10 decreases.

In this manner, the engine rotational speed is controlled by the electronic air control unit 60 to a set rotational speed corresponding to the comparison level D determined by the output of the function voltage generation circuit 200 during idle time when the throttle valve 17 is closed. However, the comparison level D that determines the set rotation speed of the lever increases as the engine temperature decreases, as shown by the solid line in FIG. 4, depending on the output of the warm-up sensor 19. Since the speed can be increased, stable idling operation can be maintained.Furthermore, when the air conditioning switch 28, which is connected to and driven by the engine 10 and driven by the compressor 26 of an automobile cooler, etc., the ON signal of this air conditioning switch 28 generates a function voltage. Since the comparison level D is raised by the circuit 200 as shown by the broken line in FIG. If you cause this problem, the problem will disappear. Furthermore, since the pulse signal G that controls the energization of the electromagnetic mechanism 50 is determined by the output voltage E of the integrating circuit 400, the control speed can be increased using the integrating circuit 400 as the engine speed deviates from the set speed. It is possible to converge to the set speed stably and responsively.

For example, when the engine temperature rises and warm-up is completed, the load such as the viscous resistance of engine oil becomes smaller, so the amount of auxiliary air during idling can be reduced. In a case where such warm-up is completed, when depressing the brake pedal to decelerate the car and stop the car, the engine rotation speed becomes lower than the idle setting rotation speed determined by the function voltage generation circuit 200. If you continue to apply the brakes and then release the clutch of the car, the output of the integrating circuit 400 will continue to rise, which means that the opening of the air valve 30 will increase and the amount of auxiliary air will increase all at once, which will cause the car to stop idling, albeit temporarily. Although there is a possibility that the rotational speed becomes abnormally high, in this embodiment, the output of the integrating circuit 400 is
Since the voltage is limited to the upper limit voltage given by the potential of the connection end H by 00, the amount of auxiliary air will not increase beyond the amount determined by this upper limit voltage, so the idle rotation speed will be prevented from becoming abnormally high. In addition,
This upper limit voltage is determined by the engine temperature, and increases as shown in FIG. 5 when the engine temperature is low.

Also, the voltage limiting circuit 800 causes the integrating circuit 40 to
Since the 0 output is limited to within the upper and lower limits, even if a problem occurs with the rotation speed signal from the rotation speed sensor, at least the rotation speed at idle will be within the upper or lower limit depending on the engine temperature. The rotation speed corresponding to the voltage within can be controlled within the range.

In addition, in the above-mentioned embodiment, the air control valve 30
The amount of auxiliary air that bypasses the throttle valve 17 is controlled by, for example, the displacement of the shaft 34 of the air control valve 30.
By controlling the opening degree of 7, it is also possible to control the amount of air during idling operation.

Further, in the above embodiment, an air control valve of a type in which a diaphragm valve is actuated by the electromagnetic mechanism 50 is used, but an electromagnetic air control valve in which a valve body is actuated directly by the electromagnetic force of the electromagnetic mechanism 50 may be used.

Further, although a cooling water temperature sensor is used as the warm-up sensor, an engine oil temperature sensor, a block temperature sensor, a timer using a bimetal and an electric heater, etc. may also be used.

Further, although the warm-up state of the engine and the connection state of the compressor are used as elements of the function voltage, the function voltage may be generated based on other engine operating states.

Further, in the above embodiment, during normal operation other than idling operation in which the throttle valve 17 is opened, it is possible to additionally provide a circuit for maintaining the output voltage of the integrating circuit 400 at a predetermined value depending on the engine temperature. This makes it possible to supply a predetermined amount of auxiliary air depending on the engine temperature during normal operation.

〔Effect of the invention〕

As described above, according to the present invention, the air amount control means for controlling the amount of air taken into the engine;
an engine rotation speed detection means for detecting the engine rotation speed; an engine condition detector for outputting a signal according to the engine condition including at least a warm-up condition of the engine; and an idling target according to the signal of the engine condition detector. target rotational speed setting means for setting a target rotational speed, and comparison means for comparing the engine rotational speed detected by the engine rotational speed detection means and the target rotational speed set by the target rotational speed setting means. a control amount setting means for setting a control amount so as to eliminate a deviation between the engine rotation speed and the target rotation speed based on a comparison result of the comparison means; and a control amount set by the control amount setting means. drive control means for controlling the drive of the air amount control means in accordance with the engine condition; Since the engine speed control device is characterized in that it is equipped with a limiting means for limiting the engine speed to a range between an upper limit value and a lower limit value, This has excellent effects in that it can be appropriately controlled according to the requirements, and the configuration can be simplified by unifying the control devices that were conventionally provided for this purpose. As a result, the degree of freedom in design is improved, and reliability is also improved due to a reduction in the number of parts.

Further, the idle rotation speed is set to a target rotation speed set by the target rotation speed setting means according to a signal from the engine condition detector, that is, a target rotation speed corresponding to the engine condition including at least a warm-up condition of the engine. Since the closed-loop control is performed by comparing the actual rotational speed of the Another great effect is that it is possible to perform stable rotational speed control as intended by the designer in response to changes in conditions.

Furthermore, the control amount set by the control amount setting means is limited by a limiting means so that it does not exceed a range between a predetermined upper limit value and a lower limit value that varies depending on a signal corresponding to the warm-up state of the engine condition detector. Therefore, even if a problem occurs in the rotational speed signal or the like, the rotational speed can be maintained in a state corresponding to the control amount limited by the upper limit value or lower limit value depending on the warm-up state of the engine.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the device of the present invention;
Fig. 2 is an electric circuit diagram showing the electronic air control unit shown in Fig. 1, Fig. 3 is a signal waveform diagram of each part in Fig. 2, and Figs. 4 and 5 are explanations of the operation of the device shown in Fig. 1. FIG. DESCRIPTION OF SYMBOLS 10... Engine, 18... Distributor forming a rotational speed sensor, 26... Compressor, 30... Air control valve, 50... Electromagnetic mechanism, 1
00...A-D conversion circuit, 200...Function voltage generation circuit, 300...First comparison circuit, 400...Integrator circuit, 500...Oscillator, 600...Second comparison circuit, 700...Amplification circuit.

Claims (1)

[Scope of Claims] 1. Air amount control means for controlling the amount of air taken into the engine, engine rotation speed detection means for detecting engine rotation speed, and a signal corresponding to the engine state including at least the warm-up state of the engine. an engine state detector that outputs an engine state detector; a target revolution speed setting means that sets a target revolution speed during idling according to a signal of the engine state detector; a comparison means for comparing the rotational speed and the target rotational speed set by the target rotational speed setting means; and based on the comparison result of the comparison means, the deviation between the engine rotational speed and the target rotational speed is eliminated. a control amount setting means for setting a control amount; a drive control means for controlling the drive of the air amount control means in accordance with the control amount set by the control amount setting means; and limiting means for limiting the controlled amount to a range between a predetermined upper limit value and a lower limit value that changes depending on a signal corresponding to a warm-up state in the engine state detector. . 2. Engine rotation speed control according to claim 1, wherein the air amount control means is provided between a conduit formed to bypass a throttle valve provided in an intake pipe of the engine. Device.