JPS6352224B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an engine speed control device.

Conventionally, there has been a tendency to lower the idling speed of automobile engines in order to improve fuel efficiency or reduce exhaust gas. However, there is a limit to reducing the idling speed when considering variations in engine performance and changes over time. Therefore, in recent years, electronic control devices that can accurately and stably control the idling speed over a long period of time have come into use as a new technical means.

An example of a conventional device for controlling the idling speed of an engine will be described below with reference to FIGS. 1 to 3. FIG. 1 is a block diagram showing an example of a conventional device for controlling the idling speed of an engine by changing the stopper position of a throttle valve using a DC motor. In the figure, 1 is an ignition coil, 2
is an ignition coil control device that controls the ignition coil 1;
3 is a period measuring circuit that is connected to the ignition coil 1 and measures the time interval between ignition signals; 4 is a rotation speed calculation circuit that converts the time interval between ignition signals into a number signal having a weight of the actual engine rotation speed N; Reference numeral 5 denotes a target rotation speed calculation circuit that calculates a target idling rotation speed _N0 , and the target rotation speed calculation circuit 5 includes a load switch 51 that detects the engine load of an air compressor, etc., and a temperature sensor 52 that detects the engine cooling water temperature.
The target idling rotation speed N ₀ is calculated based on these detection signals. Reference numeral 6 indicates a deviation which compares the output signals from each of the rotation speed calculation circuit 4 and the target rotation speed calculation circuit 5 and outputs a comparison signal A indicating the magnitude relationship between the two output signals and a rotation speed deviation signal B indicating the deviation. Detection circuit, , 7 receives two types of output signals a and b from the deviation detection circuit 6, and calculates optimal drive time data for the DC motor 121. 8 is a control pulse width calculation circuit that drives the DC motor 121 intermittently. 9 is a pulse width counter that measures the period T and outputs an output signal at regular intervals T. The pulse width counter 9 has a preset counter inside, and the time when the control period counter 8 outputs an output signal. At the same time as presetting the output value of the control pulse width calculation circuit 7, subtraction is started at regular intervals, and this subtraction counting operation is performed until the contents of the preset counter become zero, and the output signal continues to be sent. do. Reference numeral 10 denotes a control signal generation circuit which receives the comparison signal A from the deviation detection circuit 6 and the output signal from the pulse width counter 9 and the switch 123, and generates a forward rotation signal or reverse rotation signal for driving the DC motor 121 in forward or reverse rotation. Output. 11
are the output terminals 101 and 10 of the control signal generation circuit 10
12 is a throttle valve actuator; the actuator 12 is a DC motor 121;
A reduction mechanism 12 that converts rotational motion into linear motion.
2. A switch 123 that detects the fully closed state of the accelerator pedal 14 in the on state, a throttle stopper 124 that is linearly driven by the deceleration mechanism 122, and a cam mechanism 125 that is locked by the throttle stopper 124. It is equipped with Cam mechanism 12
5 is interlocked with a throttle valve 13.

Next, the operation of the above conventional device will be explained. Figure 2 shows the relationship between the rotational speed deviation between the target idling rotational speed _N0 and the actual engine rotational speed N and the drive time data of the DC motor 121, and Figure 3 shows the change in the actual engine rotational speed N and the control signal generation. 3 is a time chart showing forward rotation signals and reverse rotation signals generated by the circuit 10. FIG. First, the time interval between ignition signals measured by the period measurement circuit 3 is converted into an actual rotation speed signal weighted by the rotation speed in the rotation speed calculation circuit 4,
It is input to the deviation detection circuit 6. Further, the target rotational speed calculation circuit 5 calculates a target idling rotational speed N ₀ according to information from the load switch 51 and the temperature sensor 52, and inputs this to the deviation detection circuit 6 as an output signal. As a result, the deviation detection circuit 6 uses the difference between the actual engine rotation speed N and the target idling rotation speed _N0 as the rotation speed deviation signal RO, and the control pulse width calculation circuit 7
At the same time, a comparison signal A indicating the magnitude relationship between N and _N0 is output to the control pulse width calculation circuit 7 and the control signal generation circuit 10. Here, when the comparison signal A is at the "L" level, it indicates the region of N ₀ >N,
When it is at the "H" level, it indicates a region where N ₀ <N. The control pulse width calculation circuit 7 calculates optimal drive time data DTP of the DC motor 121 according to the comparison signal A and the rotation speed deviation signal B, and outputs this to the pulse width counter 9. In FIG. 2, the horizontal axis shows the rotational speed deviation N ₀ -N, the vertical axis shows the drive time data DTP, and forward rotation and reverse rotation indicate the forward rotation drive and reverse rotation drive of the DC motor 121, respectively, and the throttle The opening and closing operations of the valve 13 are shown. ｜N ₀
-N| is within the dead band rotational speed Nd, the drive time data DTP becomes zero and the DC motor 121 is not driven. The pulse width counter 9 converts the drive time data DTP into a pulse width and sends it to the control signal generation circuit 1 as a drive pulse width signal (TP).
Output to 0. The period T at which the pulse width counter 9 generates the drive pulse width signal (TP) is given by the control period counter 8.

Here, when the switch 123 provided in the actuator 12 is turned on, that is, when the accelerator pedal 14 is fully closed, the control signal generation circuit 10 outputs a signal from its output terminals 101 and 102. In this case, the control signal generation circuit 10 guides the drive pulse width signal TP to the output terminal 101 or the output terminal 102 based on the comparison signal A. That is, when the comparison signal A is at L level, since N ₀ >N, the drive pulse width signal TP
is guided to the terminal 101 as a normal rotation signal, and since N ₀ <N when the comparison signal A is at H level, the drive pulse width signal TP is guided to the terminal 102 as a reverse rotation signal. However, |N ₀ −N| is the dead band rotation speed
If it is within Nd, the drive pulse width signal TP is zero and is not output to the output terminals 101 and 102.
The drive circuit 11 drives the DC motor 121 in normal rotation while the signal is being outputted from the output terminal 101, so that the throttle stopper 124 is pushed out, the throttle valve 13 is opened, and the engine speed increases. Further, the drive circuit 11 drives the DC motor 121 in reverse while the signal is being output from the output terminal 102, so the throttle stopper 124 is retracted and the throttle valve 13 is closed.
Engine speed decreases.

Next, the operation until the engine speed becomes stable will be explained using FIG. 3. FIG. 3 shows a state in which the engine load increases before time t ₁ and the engine speed N falls below the target idling speed N ₀ .
The engine rotation speed at time t ₁ is N ₁ , and the drive time data output by the control pulse width calculation circuit 7
The DTP becomes DTP ₁ as shown in Figure 2. Therefore, the pulse width counter 9 calculates the time width TP ₁ from time t ₁
The drive pulse width signal TP is output. Since the engine speed N is less than the target idling speed _N0 , the drive circuit 11 drives the DC motor 1 during the time width _TP1 .
21 in normal rotation, and the throttle stopper 124
Push out. Therefore, the throttle valve 13 opens and the engine speed increases. Next, the engine rotation speed at time t ₂ after a certain period T from time t ₁ is N ₂ . At this time t ₂ , N ₀ >
Since it is N, the DC motor 121 is driven in normal rotation during the time width _TP2 . As a result, the engine speed increases and |N ₀ -N| becomes within Nd before reaching time t ₃ , and the drive signal of the DC motor 121 changes at time t ₃
Thereafter, there is no output, and after this, the DC motor 1 will not output until |N ₀ - N | exceeds Nd due to some disturbance.
21 is not driven. In this way, N becomes N ₀
Can be controlled and maintained in close proximity.

In the conventional device described above, consider a case where a car is traveling down a long downhill slope. in this case,
The accelerator pedal 14 is fully closed, and generally the engine speed N is the target idling speed N ₀
Because of the above, a reverse rotation signal is applied from the drive circuit 11 to the DC motor 121 in order to reduce the engine speed N, and the DC motor 121 is driven in the reverse direction. However, since the vehicle is traveling downhill, the engine speed N hardly decreases even if the slot valve 13 is fully closed. As a result, the intermittent reverse rotation of the DC motor 121 does not stop, the throttle stopper 124 is fully retracted, and the speed reduction mechanism 122 is locked. Once the motor is in a locked state, it often does not return to normal even when the motor is next driven to the normal rotation side, resulting in loss of control.

As a means to eliminate the above-mentioned drawbacks, a switch 1 for detecting the fully closed state of the accelerator pedal 14 is provided.
It has been proposed that the operating characteristics of 23 be as shown in FIG. The horizontal axis in FIG. 4 shows the opening degree of the throttle valve 13, and the vertical axis shows the state of the switch 123. Normally, when the accelerator pedal 14 is depressed, this corresponds to area B, and when the accelerator pedal 14 is not depressed, this corresponds to area A. The opening degree θ ₂ is determined by the switch 123 when the accelerator pedal 14 is released from the depressed state.
is the opening at which throttle stopper 1 is turned on.
It changes depending on the position of 24. Further, although the opening degree θ ₁ cannot occur in the normal usage range, even if the DC motor 121 is driven in reverse up to this opening degree θ ₁ , the deceleration mechanism 122
This is the degree of opening that prevents the valve from falling into a locked state. That is, θ ₁ is the throttle opening between the full return position and the normal idle position of the actuator 12. When the opening degree is less than θ ₁ , the switch 123 is configured to be turned off again. As a result, switch 12
3 is turned on only when the opening degree of the throttle valve 13 is θ ₁ or more and the accelerator pedal 14 is not depressed, and the control signal generation circuit 10 is in a state where it can output an output signal. Therefore, even if the accelerator pedal 14 is continuously driven for a long period of time with the accelerator pedal 14 fully closed as described above, the control signal generation circuit 10 will not output until the opening degree reaches from θ ₂ to θ ₁ . A reverse rotation signal is output from the terminal 102, but when the opening degree θ ₁ is reached, the switch 123 is turned off and the reverse rotation signal is no longer output, so that the deceleration mechanism 123 does not fall into a locked state.

However, if the switch 123 is off from the beginning when the device shown in _FIG . Therefore, there arises an inconvenience that engine speed control is not performed thereafter. Furthermore, even if the accelerator pedal 14 is depressed, if the engine speed N falls below the target idling speed _N0 , the opening degree of the throttle valve 13 remains unchanged, so if this continues, the engine will malfunction. There is also a risk that it may stop.

The present invention has been made in consideration of the above points, and provides an engine speed control device that can always smoothly control the engine speed when the engine speed is equal to or lower than the target idling speed. The purpose is to

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 5 shows an engine speed control device according to this embodiment, but only the parts that are different from the conventional device shown in FIG. 1 are shown, and members 1 to 9 and 11 to 14 are omitted from the illustration. Reference numeral 15 denotes a control signal generation circuit, which is partially different from the control signal generation circuit 10 shown in FIG. 1, but has a function equivalent to that of the control signal generation circuit 10 shown in FIG. Reference numerals 151 and 152 are output terminals corresponding to the output terminals 101 and 102 in FIG. 153 is a NAND to which the output of the switch 123 and the comparison signal A from the deviation detection circuit 6 are input.
104 is a NOT circuit to which the comparison signal A is input; 155 is an AND circuit to which the output of the NAND circuit 153, the output of the NOT circuit 154, and the driving pulse width signal TP from the pulse width counter 9 are input;
Reference numeral 56 denotes an AND circuit which receives the output of the NAND circuit 153, the comparison signal A, and the drive pulse width signal TP, and the output sides of the AND circuits 155 and 156 are connected to output terminals 151 and 152, respectively.

Next, the operation of the above device will be explained. Now, when the switch 123 is on, its output is at the L level, so the output of the NAND circuit 153 is at the H level, and the outputs of the AND circuits 155 and 156 are determined by the comparison signal A and the drive pulse width signal TP. be done.
This is the same as before, and when N ₀ > N, the comparison signal A is at L level, so the drive pulse width signal
TP is output as a normal rotation signal from the output terminal 151 to the drive circuit 11, and the DC motor 121 is driven to rotate in the normal rotation. Further, when N ₀ <N, the drive pulse width signal TP is output from the output terminal 152 as a reverse rotation signal, and the DC motor 121 is driven in the reverse direction.

On the other hand, when the switch 123 is off, N ₀ <N
Since the comparison signal A is at the H level, the output of the NAND circuit 153 is at the L level, and the output terminal 15
No output signal is output from 1,152.
Furthermore, when N ₀ >N, the comparison signal A is at the L level, so the output of the NAND circuit 153 is at the H level regardless of the output of the switch 123, and the drive pulse width signal TP is passed through the AND circuit 155 as a normal rotation signal. It is output from the output terminal 151 and the DC motor 12
1 is driven in normal rotation.

In this way, in this embodiment, when the engine speed N is lower than the target idling speed _N0 , the engine speed is controlled regardless of the state of the switch 123, so the control is performed by turning off the switch 123 as in the conventional case. Never fall into incapacity. In particular, if the switch 123 is provided with operating characteristics as shown in FIG. 4 in order to prevent the actuator 12 from falling into a locked state, the off range of the switch 123 will expand, making it easy to lose control. _N0 >
In the case of N, control is performed unconditionally, so no loss of control occurs.

In addition, in the above embodiment, the actuator 12
is driven by the DC motor 121, but other drive sources may be used. Furthermore, although the throttle valve 13 is selected as the engine speed adjusting means, other means may be selected. Furthermore, a processing device such as an analog circuit or a microcomputer may be used as the control device.

As described above, in the present invention, in the engine speed control device that controls the engine speed on condition that the accelerator pedal is not depressed and the actuator drive device is at a predetermined position or higher, the engine speed is set to the target. If the engine speed has not reached the idling speed, the engine speed is controlled unconditionally, and even if the accelerator pedal is not depressed, control is performed smoothly in the above cases, and the engine speed becomes uncontrollable. Never fall into it.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a conventional device, FIG. 2 is a diagram of the relationship between engine rotation speed deviation and DC motor drive time data according to the conventional technology and the present invention, and FIG. FIG. 4 is a time chart of a forward rotation signal and a reverse rotation signal, FIG. 4 is a diagram showing operating characteristics of a conventional switch and a switch according to the present invention, and FIG. 5 is a diagram showing a main part configuration of an engine speed control device according to the present invention. 4... Rotation speed calculation circuit, 5... Target rotation speed calculation circuit, 6... Deviation detection circuit, 7... Control pulse width calculation circuit, 8... Control period counter, 9... Pulse width counter, 11... Drive circuit, 12... Actuator, 1
3...throttle valve, 14...accelerator pedal,
15...Control signal generation circuit, 123...Switch.
Note that the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1 An engine speed detection means for detecting the engine speed, a setting means for setting a target idling speed, an actuator for driving the engine speed adjustment means, and when the accelerator pedal is not depressed and the drive position of the actuator is a detection means for detecting that the actuator is at a predetermined position or higher at which the lock state does not occur; when the detection means detects that the actuator drive position is at or above the predetermined position when the accelerator pedal is not depressed, and the engine An engine rotational speed control device comprising: a control means for controlling the actuator so that the engine rotational speed becomes the target idling rotational speed when the engine rotational speed is equal to or lower than the target idling rotational speed.