JPS59206640A - Controller for internal-combustion engine - Google Patents

Abstract

PURPOSE:To heighten the output power of an internal-combustion engine and the efficiency of its operation and normalize its exhaust gas, by using the proportional integration/differentiation or proportional integration control signal of a revolution speed control unit to vary the air fuel ratio of the engine to automatically change its output power characteristic. CONSTITUTION:The buffer circuit 21 of an air fuel ratio controller 20 receives a proportional integration/differentiation (P.I.D.) control signal through a high impedance to prevent the signal from being affected due to the addition of the controller. When the level of the P.I.D. or proportional integration (P.I.) control signal of a revolution speed control unit 10 received as a load detection signal has exceeded the upper limit VH of the prescribed hysteresis width of a hysteresis comparison circuit 23, the air fuel ratio of an engine is dereased. When the level of the signal has become lower than the lower limit VL of the hysteresis width, the air fuel ratio is increased back to the original relatively-high value. The output power of the engine is thus adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for controlling the rotational speed of an internal combustion engine.
, D or P, I control signal.

Generally, in an internal combustion engine, the larger the air-fuel ratio (A/F) is, the more N occupies the exhaust gas.

It is well known that harmful gas components such as X and Co are reduced. However, there is a difference in the output characteristics of an internal combustion engine when operating in a region where the air-fuel ratio is high and a region where the air-fuel ratio is low. This results in a lack of output, resulting in problems such as a drop in rotational speed or stalling of the engine.

For this reason, a potentiometer (linear type, rotary type) is provided inside the throttle section or actuator of the internal combustion engine to detect the throttle opening and reduce the rotational speed or stop the internal combustion engine.

However, this potentiometer places a load on the actuator that operates the throttle, so the capacity of the actuator needs to be increased, and a potentiometer that satisfies high durability (high reliability) is expensive. Furthermore, if the throttle section or actuator section of the internal combustion engine and the control device are separated, there is an inconvenience in terms of wiring.

Therefore, this invention uses P of the rotation control device for load detection.
Ifi
It is an object of the present invention to provide an inexpensive control device for an internal combustion engine that eliminates the above drawbacks, normalizes exhaust gas, realizes highly efficient operation of an internal combustion engine, and has high control accuracy.

In order to achieve the above object, the present invention provides a rotational speed controller P, 1. The D, P, or I control signal is received as a load detection signal, and when the level of this load detection signal exceeds the upper limit of a predetermined hysteresis width of the hysteresis comparison circuit, the air-fuel ratio is decreased, and when it falls below the lower limit of the hysteresis width, the air-fuel ratio is decreased. An air-fuel ratio control device value is provided that returns the fuel ratio to its original relatively high state and adjusts the output of the internal combustion engine.

The present invention will be described in detail below based on an illustrated embodiment. FIG. 1 shows an overall configuration diagram of an internal combustion engine control device according to the present invention, which includes a rotation speed controller 10 and an air-fuel ratio control device M20. As shown in FIG. 2, the rotational speed controller 1O receives a signal from the rotational sensor 6 that detects the rotational speed of the engine 1, and connects a path 12, a differential amplifier circuit 13, and proportional/integral/differential (P, 1.D) Motion or proportional
P, which performs integral (P, I) operation, 1. D (P, I) control device 14, pulse width modulation circuit 15, and driver circuit 16
Tokaraseru. An actuator 2 drives the throttle valve 5 of the engine 1, and is driven by a pulse output from the rotational speed controller 10. The actuator 2 is normally driven with a rectangular wave, the pulse width of which is determined by the rotation speed controller l.
It is changed by the pulse width modulation circuit 15 inside O. As a result, the output of the actuator 2 is adjusted, and the throttle valve 5 is operated via the wire 3. The throttle opening degree is determined by the balance between this actuator output and the outer spring 4. The rotation speed of the engine 1 is detected by the rotation sensor 6, fed back to the rotation speed controller 10, and compared with the value of the rotation speed setting device 7 which is manually operated. At step 17, the level of the sawtooth wave from the reference frequency generation circuit 18 is compared,
This adjusts the engine speed.

The air-fuel ratio control device 20 uses one of the signals generated by the rotational speed controller 10 as a load detection signal, controls the control relay LY2 according to the load state of the engine 1, and also receives signals from the engine start/stop control device 19. The control relay LYI is controlled in response to the start-up completion signal.

The load detection signals include: proportional/integral/differential CP at the front stage of the pulse width modulation circuit 15 of the rotational speed controller 10; D
) control signal or proportional/integral (P.

■) Control signals are used. P.1. D(P.

X) The reason for using the control signal is that the throttle opening, P, 1. D(P.

■) The control signal corresponds to its characteristic curve or l vs. l (l is ■, θ1 (is ■, 8m a x is V m a
This is because the load detection signal is not a rectangular wave but a DC level signal, which has many advantages such as simplifying circuit processing.

The outline and operation of the air-fuel ratio control device 20 will be explained below based on the block diagram of FIG. 2. The circuit configuration of the control device 20 is 4
777 circuit 21, filter circuit 22, hysteresis comparison circuit 23, gate) (AND) circuit 24, timer circuit 2
5.Relay dry l<circuit 26.27.

First, the buffer circuit 21 connects P, 1.
Receives the D signal input section with high impedance, P, I, D
This prevents the control signal from being influenced by the addition of this device. The filter circuit 22 based on the following CI is:
P.1. This is for removing ripples from the D signal.
, 1. The D control signal is converted into a complete DC level signal,
In addition to increasing the detection accuracy of the next-stage hysteresis comparison circuit 23, P, 1. This prevents malfunctions when the D control signal undergoes transient fluctuations (large level fluctuations). The next hysteresis comparison circuit 23 has a certain hysteresis width with an upper limit (1) and a lower limit (2) with respect to the input level, as shown in FIG. 9, although the details will be described later. To explain this using Fig. 5, the load follows the route ■ of the output characteristic I,
When the load increases and exceeds the specified load, the throttle opening reaches ), and the P, I, and D control signals reach ■, determining an overload, and turning on the control relay LY2. , air-fuel ratio variable solenoid valve SV2 for refueling of the fuel supply system
opens, the air-fuel ratio becomes smaller, the engine output characteristic switches to the output characteristic I + IT, and the throttle opening decreases to DI (→ θ8) as shown in route ■.Next, when the load increases further, For example, follow route ■ of output characteristic II. Conversely, when the load decreases according to route ■ and the throttle opening reaches 014, the P, I, and D control signals become ■, and it is determined that the overload has been released. , the control relay LY2 is turned off, the air-fuel ratio variable solenoid valve SV2 is closed, the air-fuel ratio increases and the engine output characteristic changes to II-I, and the throttle opening decreases from θL to 0B as shown in route (2).

After that, if the load increases, the operation follows the route (2), and if the load decreases, the operation follows the characteristic of the route (2). Therefore, in the overall operation, the output is switched according to the hysteresis characteristics shown by the solid line in Figure 5, so there is no shortage of output during overload, and during normal load, exhaust gas is normalized and high efficiency is achieved. Driving becomes possible. However, O
If it is set to A<θL or θB>θH, even if the load is constant, the switching will not occur again when switching the output (route ■ or ■), so it is necessary to set θ to θ8, θo, and θ11. There is. Also, the hysteresis width (ΔθI−θ.

-θ14, Δθ2=θH−θB) settings may be set to optimal values in consideration of both the load fluctuation situation and the output characteristics of the engine.

If a rotation speed controller that operates so that the throttle opening is fully open when the engine is stopped or started is used as the rotation speed controller 1O, the AND circuit 24 at the next stage is of course P, 1.
．． D" control signal output exceeds ■, to prevent erroneous judgment of overload, and to start overload detection after the engine has completed starting. Detection start is provided externally. This is the time when a start completion signal (completion at H level) is input from the engine start/stop control device 19.The timer circuit 25 is used to count the elapsed time after the start of the engine is completed. Close the fuel ratio variable solenoid valve SV1 and open only S'V2 to reduce the air-fuel ratio to improve starting performance. After the same timer setting value T seconds, open the solenoid valve SVl and close only SV2 (stop, start mode) ).

FIG. 6 illustrates a specific circuit configuration of the control device 20. The hysteresis comparison circuit 23 is configured as a switching type hysteresis comparison circuit using a comparison comparator 23i and a switching comparator 232, and the upper and lower limits of the hysteresis width are set by variable resistors VRI and VH2.
Set by.

The resistor R1 in the hysteresis comparator circuit is for current limiting, and the resistor R2 is for current limiting (sinking current of the output transistor of comparator 232). Also, when the diode D1Vo is ■ (when the output transistor of the comparator 232 is off)
In addition, a current flows into the setting variable resistor VRI side, thereby preventing the set value of (2) from being influenced by the set value of (2). When the diode D2 becomes L level (when the output transistor of the comparator 232 is on), current flows from the setting variable resistor VRI side to the output transistor of the comparator 232, and the set value of , ■ are prevented from being affected when they change to the 'vI-+L level. Resistance R
3, since the input impedance of the comparator 231 is large and the operation tends to become unstable, this resistor R3 is inserted to lower the impedance and stabilize the operation.

Finally, based on the detailed circuit diagram of FIG. 6, the operation of the control device will be explained with reference to FIG.

(Stop/Start Mode) First, when the engine is stopped (see FIG. 7) and power is applied to the rotational speed controller 10 and this control device 20, one input terminal of the comparator 231 has ■>■ For, Ml
is applied via D2. On the other hand, the manual input terminal of the comparator 231 receives P from the rotational speed controller 10, 1. The D control signal passes through the filter circuit 22 and is applied as (2). Therefore, when Vc<%, the output (2) of the comparator 231 is at L level. Therefore, one input terminal of the comparator 232 is at L level, and the manual input (reference voltage) is previously set at H level and L level.
Since it is set at an intermediate level, the output (2) of the comparator 232 becomes (2) because it passes through the setting VR2 and the resistor R2 (state 8 when the output transistor of the comparator 232 is off). Next, when the throttle is fully opened when the engine is stopped, P, 1. The level of the D control signal increases with the passage of time after the power is turned on, and eventually exceeds (a state similar to that at the time of overload). Therefore, when % > Vs, it becomes larger than the constant power of the comparator 231, and the output (2) is inverted to H level. Therefore, the single-handed power of the comparator 232 becomes larger than the ten-man power, and the output (2) of the comparator 232 becomes L level (the output transistor of the comparator 232 is in an on state). Then, the output of the comparator 231 has been ■ so far, but since the output ■ of the comparator 232 has become L level, it is switched to ■. From this point on, when %<M, the output ■ of the comparator 231 switches from the H level to the L level again. However, the input 2 of the AND circuit 24 is connected to the engine start/stop control device 19, and the start completion signal from this device is low when the engine is stopped or started.
As mentioned above, even if the input 1 of the AND circuit is at the H level, the output of the AND circuit 24 will be at the L level, and the transistor TR2 of the relay driver circuit 26 will not be turned on, and the control Relay LY2 is not energized. Overload clothes.

On the other hand, the operation of the timer circuit 25 when the engine is stopped and when the engine is started vP (see FIG. 7) is as follows. Under this condition, the startup completion signal is at L level, so the timer circuit 25
The reset input section of is at L level, so counting is about to stop, the timer output is off, and the I/transistor TRI
, control relay LYI is also in the de-energized state F1. However, since the solenoid valve SV2 is opened by the b contact (FIG. 1) of the control relay LYI, the air-fuel ratio is set to a small value. After the engine start is completed, the start completion signal becomes H level, the timer circuit 25 starts counting, and after the time T seconds set in the timer setting VR, the control relay LYI is energized and the a contact of the relay is turned on. , the b contact is turned off, solenoid valve SV1 is open, and SV2 is closed, and the air-fuel ratio is set to a large value (characteristic curve I in FIG. 5).

(Normal mode/overload mode) After the timer circuit 25 time-amps, normally,
The normal mode follows the characteristic curve I in FIG. 5. If there is an overload after that, the output of the comparator 231 and the start-up completion signal are at H level, so the output of the AND circuit 24 becomes H level, the solenoid valve SV2 opens, and the air-fuel ratio becomes lower than the normal mode again. is also set small (characteristic curve II in FIG. 5) to direct the engine output. This solenoid valve S
V2 closes and the air-fuel ratio increases (characteristic curve diagram in Figure 1) because the load decreases and P, 1. D control signal (when l reaches below ■).

Note that the switching type hysteresis comparison circuit 23 does not necessarily need to be constructed from an operational amplifier; for example, the switching comparator 232 can also be constructed using a switching transistor as shown in FIG.

In the above embodiment, a reference voltage (V, . . . , V) switching type hysteresis comparison circuit was used as the hysteresis comparison circuit 23. This is ■■1. Vt is determined by the reference voltage from an external variable resistor, so it is direct.■■.

This is because adjustment is convenient because each of (2) can be set independently. However, a conventional positive feedback hysteresis comparison circuit can also be used.

As described above, the present invention provides P and I of the rotational speed controller.
, D (P, I) Since the air-fuel ratio is automatically switched using the control signal, the output when the engine is loaded is improved, exhaust gas is normalized, and the internal combustion engine is operated with high efficiency. will also be realized. Further, since a potentiometer is not used to detect the load, and the load is detected by electrical means, the engine output can be controlled quickly and accurately.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of a control device for an internal combustion engine according to the present invention;
FIG. 2 is a block diagram of the rotation speed controller and the control device of the internal combustion engine control device of the present invention, FIG. 3 is a diagram showing the load vs. throttle opening characteristic, and FIG. 4 is the load vs. P, 1. D(P,I
) A diagram showing the control signal characteristics, FIG. 5 is a diagram showing the engine output vs. throttle opening characteristic, FIG. 6 is a diagram showing a specific circuit example of the control device in FIG. 2, and FIG. Operation time chart 1 of the control device, FIG. 8 is a diagram showing another circuit example of the switching comparator of the comparison circuit with hysteresis, and FIG. 9 is a diagram showing the hysteresis characteristics of the hysteresis comparison circuit. 1... Engine 10... Rotation speed controller 19.
...Engine start/stop control device 20...Air-fuel ratio control device 21...Buffer circuit 22...Filter circuit 23...Hysteresis comparison circuit 24...AN
D circuit 25...Timer circuit 26.27...Relay driver circuit L Y l, L'Y 2-... Control IJL/-3VI, SV2... Air-fuel ratio variable solenoid valve Fig. 3 9 →・□Person Figure 4 9 Pain J・□Mu

Claims (1)

[Claims] 1. P for controlling the rotational speed of the internal combustion engine, 1. In an internal combustion engine having a rotation speed controller that produces a D or P, I control signal, the P,1. The D, P, or I control signal is received as a load detection signal, and when the level of this load detection signal exceeds the upper limit of a predetermined hysteresis width of the hysteresis comparison circuit, the air-fuel ratio is decreased, and when it falls below the lower limit of the hysteresis width, the air-fuel ratio is decreased. A control device for an internal combustion engine that includes an air-fuel ratio control device that returns the fuel ratio to its original relatively high state and adjusts the output of the internal combustion engine.