JPS646334B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an engine idle speed control device, and in particular, to a system for preventing a decrease in the engine speed at the start of engine speed control and hunting at the time of braking. The present invention relates to a suitable idle speed control device.

[Conventional technology]

A conventional idle speed control device (hereinafter referred to as an ISC device) has a configuration as shown in FIG. That is, the output terminal of the rotation detection signal of the rotation detector A that detects the rotation speed of the engine I is connected to one input terminal of the comparator B, and in this comparator B, the output terminal of the rotation detection signal is connected to the other input terminal of the comparator B. It is designed to be compared with the target rotation speed RPM input in . The output terminal of this comparator B is connected to a changeover switch C, and the output terminal of this changeover switch C is connected to an arithmetic unit E. This changeover switch C is connected to an idle switch D. A pulse converter F is connected to the output terminal of the arithmetic unit E, and a pulse generator G and an actuator H are connected to the pulse converter F.
This actuator H is connected to the engine I.

The operation of the idle rotation speed control device configured as described above will be explained.

The rotation is detected by the rotation speed detector A, and processing such as digital-to-analog (DA) conversion is performed, and the result is output to one input terminal of the comparator B. In comparator B,
Target rotation speed input to the other input terminal
The RPM and the detection signal from the rotation detector A are compared, and a logic "1" or "0" signal is output depending on their magnitude. The output from the comparator B is input to the arithmetic unit E, which performs processing such as proportional integration. In addition, when the idle state is detected by the idle switch D, the changeover switch C
The output from the comparator B is output to the arithmetic unit E, while the output from the comparator B is switched not to be supplied to the arithmetic unit E when the idle switch D detects that it is not in an idle state. The output of the computing unit E is converted into pulses by a pulse generator G and a pulse converter F, and is supplied to an actuator H. The rotation speed of the engine I is controlled by operating the actuator H. This rotation is detected by the detector A, and the above-described loop is repeated to control the rotation speed to the target rotation speed RPM.

[Problem to be solved by the invention]

FIG. 2 is an explanatory diagram of the result of controlling the rotational speed by the control block of FIG. 1. The ISC rotation speed is the target rotation speed RPM, and what is drawn by line I is, for example, the target rotation from engine constant speed to ISC after deceleration. However, when decelerating from the rotation N shown in Figure 2, the idle switch D turns ON at 0 point.
Therefore, the ISC is already activated at the 0 point, and since the engine speed at the 0 point is naturally high due to the low speed, the ISC actuator is operated in the direction of decreasing rotation. Therefore, by the time point P is reached, the ISC actuator has already overcompensated for the decrease in rotation, and the rotation speed is lower than the target P, as shown by the line in Figure 2. The hatched area cannot be controlled. In addition, there is a time delay indicated by T in reaching the ISC target rotation speed RPM, which has the drawback that it takes time to reach a stable rotation speed.
Incidentally, there are techniques similar to the above-mentioned prior art described in, for example, Japanese Patent Publication No. 55-15623 and Japanese Patent Application Laid-Open No. 55-148933.

An object of the present invention is to provide an idle speed control device that can prevent an excessive drop in engine speed that occurs when the engine speed is not shifted to idle speed control and hunting during control.

[Means to solve the problem]

The idle speed control device according to the present invention that achieves the above object includes a rotation detector that detects the engine speed and outputs a rotation detection signal, and a rotation detector that outputs a detection signal when the engine speed is below the idle speed. A rotary switch that continues to output a detection signal when in an idle state, and an idle switch that continues to output a detection signal when in an idle state.
a logic circuit that becomes conductive only when a detection signal is output from the idle switch and a detection signal is output from the rotation speed switch; and a logic circuit that conducts the engine rotation speed from the rotation detector. It is applied only when the idle speed is idle and compared with the target idle speed M, and an idle speed control command signal is output according to the difference between the two speeds. Drive control of a comparator that gives the target idle rotation speed a hysteresis of rotation speed width (±△M) and an actuator that executes idle rotation speed control based on an idle rotation speed control command signal from the comparator. The invention is characterized by comprising a control means for performing the following.

[Effect]

When the idle switch is turned on and the rotation speed switch is also turned on, that is, after the idle switch is turned on, when the engine rotation speed reaches the idle target rotation speed, the output signal from the rotation detector is passed through a logic circuit to a comparator. given to.

Therefore, since the idle speed control is started when the engine speed has sufficiently decreased, an excessive drop in the engine speed is prevented. Also,
The comparator has hysteresis in the target idle speed, so even if the engine speed crosses the target idle speed during idle speed control, a command signal to turn the idle speed control ON/OFF is output. Stable control is performed without any interference.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 3 is a block diagram showing one embodiment of the present invention.

In Fig. 3, parts with the same symbols as the idle speed control device shown in Fig. 1 are the same circuits.
It has a function.

This embodiment differs from the idle rotation speed control device shown in FIG. The second output terminal L of the logic circuit is not connected to anything, but is an open terminal, and the output terminal of the rotary switch K and the output terminal of the idle switch D are respectively connected to the logic circuit J. The rotation speed switch K is connected to the rotation detector A and the idle switch D, and the reference (target) rotation speed M is input to the other input terminal of the comparator B.

Therefore, the output of the rotation speed switch K and the output of the idle switch D are respectively input to the logic circuit J, and the logic circuit J
And comparator B operates as shown in FIG. That is, first, switch D is OFF,
When the switch K is ON, the output of the logic circuit J is at a low ("L") level, that is, an open loop, that is, the output signal from the rotation detector A is output to the open terminal L of the logic circuit J. Also, idle switch D is ON and rotation speed switch K is ON.
When ON (1), the output signal of the rotation detector A is given to the comparator B via the logic circuit J, and when the output signal reaches the target rotation speed M, "1" is input from the comparator B and the ISC Control takes place. In addition, this rotation speed switch outputs an ON signal and the ISC is activated as described above.
After control starts, rotation speed switch K is turned on.
Moving on to (2), “1” is output from comparator B,
"0", that is, the rotation range in which this ISC control is performed has a hysteresis between ON and OFF as shown in FIG. Therefore, the rotary switch K is turned on.
In case (2), comparator B operates to perform ISC within a predetermined rotation range. To explain this operation using Fig. 6, the ISC operates after the idle switch D is turned on and the rotation speed switch K is turned on. When the detection signal from the rotation detector A becomes the target rotation speed M after being compared with the number M, the ISC control starts, and once the ISC control is started, the target rotation speed M given to the comparator B is ± It has a hysteresis of ΔM. This ±△M can be appropriately selected from the hunting width of the engine during USC.

Therefore, according to this embodiment, as shown in FIG. 5, the ISC is activated when the idle switch D is turned on.
After that, ISC can be started when the rotational speed switch K is turned ON, so ISC is started at point Q, and the drop in rotational speed shown in FIG. 2 can be prevented. Further, according to this embodiment, when the idle switch D is turned ON and the rotation speed switch K is turned ON, and the logic circuit J is turned on, the detection signal of the rotation detector A (corresponding to the RPM on the horizontal axis in FIG. 6) is When the detection signal from the detector A reaches the target rotation speed M of the comparator B, the comparator B outputs "1" and ISC control is applied.
(indicated by ON on the vertical axis in the figure), and once ISC
If the detection signal from rotation detector A does not fall below -△M while the control is being applied, comparator B continues to output "1", and when the detection signal from rotation detector A reaches -△M, the comparator B continues to output "1". As shown by the symbol (left) in Figure 6, comparator B outputs "0" and ISC control is stopped (this is represented by OFF on the vertical axis in Figure 6).
Also, when the detection signal from detector A becomes +△M, it passes through the symbol (right) in Figure 6 and outputs "1" from comparator B.
is output, and the rotational speed is sufficiently controlled within ±ΔM.

〔Effect of the invention〕

As explained above, according to the present invention, when the engine speed reaches the idle target speed,
Since the ISC control command signal is output from the comparator, the engine speed does not drop excessively when shifting to ISC control, and the engine speed can settle to a stable idle speed in a short period of time. In addition, the comparator has hysteresis characteristics, so even if the engine speed crosses the idle target speed, the ISC
Since the control does not turn ON and OFF, ISC control may be canceled due to engine hunting,
Stable without being released or sagging
ISC control becomes possible.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional idle speed control device, FIG. 2 is a diagram showing the control results of FIG. 1, FIG. 3 is a block diagram showing an embodiment of the present invention, and FIG. FIG. 5 is a diagram showing the control of the illustrated logic circuit, FIG. 5 is a characteristic diagram of time and rotational speed of the embodiment illustrated in FIG. 3, and FIG. 6 is a diagram explaining rotational speed control of the embodiment illustrated in FIG. 3. A... Rotation detector, B... Comparator, D... Idle switch, E... Arithmetic unit, F... Pulse converter, H... Actuator, I... Engine, J
...Logic circuit, K...Rotation speed switch.

Claims (1)

[Claims] 1 A rotation detector that detects the engine rotation speed and outputs a rotation detection signal, a rotation switch that continues to output a detection signal when the engine rotation speed is below the idle rotation speed, and a rotation switch that outputs a detection signal when the engine is in an idle state. an idle switch that continues to detect the engine speed; a logic circuit that becomes conductive only when a detection signal is output from the idle switch and a detection signal is output from the rotation speed switch; It is applied only when the logic circuit is in a conductive state and compared with the idle target rotation speed M, and outputs an idle rotation speed control command signal according to the difference between the two rotation speeds. A comparator that makes the idle target rotation speed have a hysteresis of an engine rotation speed width (±△M) larger than a hunting width of , and idle rotation speed control based on an idle rotation speed control command signal from the comparator. 1. An idle rotation speed control device comprising: control means for controlling the drive of an actuator.