JPS646335B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake air amount control device that controls the rotational speed of an engine by appropriately adjusting the amount of intake air given to the engine depending on whether the engine is idling or not.

Conventionally, a control valve is set in the air passage that bypasses the throttle valve of the engine, and this control valve is operated at idle according to the comparison result between the engine rotation speed and the target rotation speed, and the air passage is disconnected. For example, the technology of feedback control by varying the area so that the engine rotation speed at idle converges to the target rotation speed was developed by Tokuko Showa.
This method is already known from Publication No. 49-40886.

However, conventionally, the engine speed control device described above performs feedback control not only during idling but also during non-idling, that is, during load operation, so when the engine speed is increased due to load operation, the The control valve is operated to close the air passage in an attempt to lower the engine speed. Therefore, during deceleration when the throttle valve is closed and the engine shifts from a load operating state to an idling operating state, the amount of intake air to the engine is insufficient because the air passage is closed. During acceleration, when the engine speed changes from 1 to 2, the air passage closes as the engine speed increases. Therefore, the amount of intake air to the engine cannot be adjusted appropriately depending on the change in operating conditions. It was difficult to follow the engine rotation speed smoothly.

In view of the above points, the present invention uses open loop control for engine load operation, and during this open loop control, a control value (that is, intake air amount) that is larger than during feedback control and corresponding to the engine temperature is provided, Moreover, when the engine accelerates when switching from feedback control to open-loop control, by increasing the intake air amount to the control value for open-loop control described above, a sufficient amount of intake air can be supplied and a smooth acceleration feeling can be obtained. The purpose is to provide a control device.

Furthermore, when the engine decelerates when switching from open loop control to feedback control, the open loop control value is gradually reduced to the normal feedback control value, thereby preventing a significant drop in engine speed during deceleration. An object of the present invention is to provide an intake air amount control device that can smoothly reduce rotation speed.

Therefore, in the present invention, feedback control, which controls the intake air amount of the engine so that the actual rotation speed matches the target rotation speed, and open loop control, which does not perform feedback, are performed depending on the engine operating conditions. In the intake air amount control device that switches and controls the intake air amount, an open loop control value is used as a control value for controlling the actuator that adjusts the intake air amount.
The first means is to set the control value to a value that corresponds to the engine temperature and is larger than the feedback control value, and when the engine accelerates when switching from feedback control to open loop control, the control value is set from the feedback control value to a predetermined open loop control value. and a second means for raising.

Furthermore, the present invention is characterized by comprising a third means for gradually reducing the control value from the predetermined open-loop control value to the feedback control value when the engine decelerates when switching from open-loop control to feedback control. do.

The present invention will be described below with reference to an embodiment shown in the drawings. In FIG. 1, an engine 10 is a known four-cycle 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 supplies 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 an engine rotational speed signal from a distributor serving as a rotational speed sensor and an intake air amount signal measured by the airflow meter 12 as basic parameters. In addition, signals from a warm-up sensor 19, a throttle sensor 25, etc. are inputted, and the amount of fuel injection is increased or decreased based on these signals.

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. Further, 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 the displacement of a diaphragm 33 whose outer periphery is wound between the housings 31 and 32 is transmitted to the valve body 35 via the shaft 34, and the displacement of the diaphragm 33 is transmitted to the valve body 35 via the shaft 34. It is of the type that opens and closes. The diaphragm 33 is
It is displaced 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 valve 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 a sleeve 42 provided on this holding plate 41.
The shaft 34 is guided in an airtight manner.
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 43.

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) according to the magnitude of the pressure within the chamber 38. The length is determined by the proportion of time that the pipe 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 controls the engine operation by controlling the intake air amount of the engine to control the actual engine rotation speed to match the set rotation speed, and the open loop control that does not perform feedback. It switches and controls according to conditions, and includes a distributor 18, a warm-up sensor 19 that detects engine temperature, that is, a warm-up state, a compressor 26 for an air conditioner such as an automobile cooler, and a drive shaft of the engine 10. Air conditioning switch 28 that turns on and off the electromagnetic clutch 27 that lasts
are maintained, and an engine rotational speed signal, a cooling water temperature signal, a throttle signal, and an air conditioner on/off signal are 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 applied voltage synchronized with the engine rotation (intermittent signal). 200 is a function voltage generation circuit,
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 amplified by a known amplification circuit 201 to become a voltage signal corresponding to the engine warm-up state. This voltage signal is passed through the resistor 202 and the diode 203, and the on/off signal from the air conditioning switch 28 is passed through the resistor 202.
4. The signal is output to a first comparison circuit 300 (described later) via the diode 205, and provides a comparison level D of the first comparison circuit 300. The first comparison circuit 300 includes resistors 301, 302, 303, and a comparator 304, and 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 characteristics of the functional voltage generation circuit 200 are as shown in FIG. 4. The lower the engine temperature, the higher the output voltage. In this case, the output voltage increases as shown by the broken line in FIG.
The comparison circuit 300 outputs a signal C that brings the output voltage of the DA conversion circuit 100 to a comparison level.

Reference numeral 400 denotes an integrating circuit, which charges or discharges a capacitor 401 at a constant current according to this signal C, and includes resistors 402, 403, a transistor 409, and a transistor 409 as a constant current charging circuit that operates when the signal C is at the "0" level. It includes resistors 405, 406, 407, a diode 408, and a transistor 410 as a constant current discharge circuit that operates when C is at the "1" level. As shown by the broken line in FIG.
During the level, the capacitor 401 is charged with a constant current, so the output voltage E increases, and when the output signal is at the "1" level, the capacitor 401 is discharged with a constant current, causing the output voltage E to drop. . 50
0 is a known oscillator that outputs a triangular waveform voltage F with a constant period, as shown by the solid line in FIG. 3E. 6
00 is the output voltage E of the integrating circuit 400 and the oscillator 50
A second comparator circuit receives a triangular waveform voltage F of 0 and compares both voltages, and is composed of a resistor 601 and a comparator 602. As shown in FIG. "Outputs the pulse signal G that becomes the level. 700 is this second comparator 6
This amplification circuit uses an inverting amplifier 701 that inverts and amplifies the signal G of 00, and the amplified output is supplied to the electromagnetic coil 51 of the electromagnetic mechanism 50 of the air control valve 30. Reference numeral 800 denotes a switching circuit which switches the integrating circuit 400 between operation and non-operation, and when the integrating circuit 400 is not operating, switches the output voltage E to a predetermined value larger than normal as shown in FIG. Throttle valve 17
It has analog switches 801 and 802 that are turned off (opened) when the switch is closed. Furthermore, this switching circuit 800 is connected to the first comparison circuit 3 via resistors 803, 804, 805 and diodes 807, 808.
04, and is also connected to the base of the transistor 410 via a diode 808. Further, the switch 801 is connected to the capacitor 4 of the function generating circuit 200 and the integrating circuit 400.
01 and resistance circuits 803, 804, 805, 80
Connect via 6.

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 rotational speed is lower than the set rotational speed corresponding to the comparison level D determined by 0, the output of the DA conversion circuit 100 also decreases with respect to this comparison level D. Therefore, as shown in the center part of FIG. 3B, the output of the DA converter circuit 100 is always lower than the comparison level D.
Even if it becomes high, it is only for a short time, and therefore, the output signal of the first comparison circuit 300 is always at the "0" level or "1" level, as shown in the center part of FIG. 3C, but it is at the "1" level. The period is very short, and as a result, the output voltage E of the integrating circuit 400 increases as shown by the broken line in the center of FIG. 3E. Therefore, in the second comparison circuit 600, the period T during which the integrated voltage E is larger than the triangular waveform voltage F of the oscillator 500
(the period during which the comparator 602 is at the "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. This increases the amount of auxiliary air that bypasses the throttle valve 17, increasing the rotational speed of the engine 10. On the other hand, when the engine rotation speed is higher than the set rotation speed during idling operation, the output of the D-A conversion circuit 100 is always higher than the comparison level D that gives the set rotation speed, as shown on the right side of FIG. 3B. Even if it becomes low, it is only for a short time, and the output signal of the first comparison circuit 300 is always "1" as shown on the right side of FIG. 3C.
Even if the level becomes "0" level, the period of "0" level is very short, and as a result, the integration circuit 400
The output voltage E decreases as shown by the broken line on the right side of FIG. 3E. Therefore, in the second comparator circuit 600, the period T during which the integrated voltage E is larger than the triangular wave voltage E of the oscillator 500 (that is, the period during which the comparator 602 is at the “1” level) is reduced, and the electromagnetic mechanism of the air control valve 30 The proportion of time that the electromagnetic coil 51 of 50 is energized decreases, which means that the opening degree of the air control valve 30 decreases, the amount of auxiliary air that bypasses the throttle valve 17 decreases, and the rotational speed of the engine 10 decreases. .

In this manner, the engine rotation speed is controlled by the electronic air control unit 60 at the idle time when the throttle valve 17 is closed (that is, during feedback control) to the set rotation speed corresponding to the comparison level D determined by the output of the function voltage generation circuit 200. Controlled by speed. 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, and the compressor 26 of the automobile cooler is connected to the engine 10 and driven by the air conditioning switch 2.
8 is on, the on signal of the air conditioning switch 28 is input to the function voltage generation circuit 200, and this circuit 200 raises the comparison level D as shown by the broken line in FIG. 4, thus increasing the set circuit speed. This eliminates problems such as impairing the performance of the compressor 26 or causing engine stall.

Next, the throttle valve 17 of the engine 10 is opened, and when the state is shifted from idle operation to load operation (that is, open loop control state), analog switches 801 and 802 of the switching circuit 800 are both closed by a signal from the throttle sensor 25. is turned on (turned on), and the first comparison circuit 3 is turned on by the switch 802.
Since the non-inverting input level D of the comparator 304 of 00 is set to the "0" level, the output of the comparator 304 becomes "1", and the transistor 4 of the integrating circuit 400
09 is cut off, and in order to set the base potential of the transistor 410 to the "0" level via the danode 808, the transistor 410 is also cut off. Therefore, the capacitor 401 of the integrating circuit 400 is
This means that it is cut off from the discharge circuit, and the operation of the integrating circuit is stopped. On the other hand, since the analog switch 801 is also closed at the same time, the function voltage generation circuit 20
The voltage signal corresponding to the engine warm-up state from the amplifier circuit 201 of
5,806, the voltage signal corrected by applying a bias is supplied to the capacitor 401 of the integrating circuit 400. Therefore, the voltage E of the capacitor 401 at this time, as shown by the broken line in FIG. 5, is higher than the normal output range shown in the shaded area in FIG. 5 in which the set rotational speed control is performed during idling, and when the engine is warmed up, that is. It becomes a predetermined value depending on the engine temperature, that is, the electromagnetic coil 5 of the electromagnetic mechanism 50 of the air control valve 300
1 (that is, the amount of auxiliary air supplied by bypassing the throttle valve 17) becomes a predetermined value larger than the time ratio when the set rotation speed is controlled during idle. When the throttle valve 17 is closed and the throttle valve 17 is decelerated and shifted to idle operation from such a load operation state, the switching circuit 80
Since analog switches 801 and 802 of 0 are both opened, the first comparator circuit 300 and the charging/discharging circuit of the integrating circuit 400 restart the operation for controlling the set rotational speed as described above, but the capacitor 401 of the integrating circuit 400 Since the output voltage E of is gradually reduced by the resistor 407 to the normal output range for idle setting rotation speed control, the amount of auxiliary air is also gradually reduced to the amount for idle setting rotation speed control, so immediately after deceleration. The amount of auxiliary air is large, and as a result, it is possible to prevent the negative pressure in the intake pipe 13 downstream of the throttle valve 17 from suddenly increasing immediately after deceleration, and it is possible to cause the engine to function as a so-called dumppot.

Of course, even when shifting from the state where the set rotation speed is controlled during idling to load operation due to engine acceleration, the output voltage E of the capacitor 401 of the integrating circuit 400 gradually changes with the time constant determined by the resistor 806 of the switching command circuit 800. As it increases, it reaches the predetermined value shown by the broken line in FIG. 5, so there is no possibility that the auxiliary air will rise suddenly during acceleration and deteriorate the acceleration feeling or exhaust gas characteristics.

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.

In the above embodiment, an air control valve in which a diaphragm valve is actuated by an 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 also 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.

As described above, according to the present invention, during open-loop control, a control value (in other words, intake air amount) that is larger than during feedback control and corresponds to the engine temperature is given, and during acceleration when switching from feedback control to open-loop control. A smooth acceleration feeling can be obtained by increasing the open loop control value to the above value.

In addition, when the engine decelerates when switching from open-loop control to feedback control, the open-loop control value is gradually lowered to the normal feedback control value, thereby preventing a large drop in rotational speed during deceleration and ensuring smooth control. The rotational speed can be reduced to significantly improve the driving feeling when switching between idling and non-idling driving states.

[Brief explanation of drawings]

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, 30... Air control valve forming an actuator, 100... D-A conversion circuit, 200... Function voltage generation circuit, 300... First comparison Circuit, 400...integrator circuit, 800...switching circuit.

Claims (1)

[Claims] 1. Feedback control in which the actual rotational speed is controlled to match the target rotational speed by controlling the intake air amount of the engine, and open loop control without feedback, depending on the engine operating conditions. In the intake air amount control device that switches and controls the intake air amount, an open loop control value is used as a control value for controlling the actuator that adjusts the intake air amount.
The first means is to set the control value to a value that corresponds to the engine temperature and is larger than the feedback control value, and when the engine accelerates when switching from feedback control to open loop control, the control value is set from the feedback control value to a predetermined open loop control value. An intake air amount control device comprising: second means for raising the intake air amount. 2. The present invention is characterized by comprising a third means for gradually reducing the control value from the predetermined open-loop control value to the feedback control value when the engine decelerates when switching from open-loop control to feedback control. The intake air amount control device according to scope 1.