JPS6275046A - Driving circuit for idle speed control valve - Google Patents

Abstract

PURPOSE:To suppress fluctuation of flow by executing duty control in such a manner that power conduction is finished upon reaching of the integrated value of current to a target value corresponding with a flow control value after starting power conduction to an electromagnetic coil with predetermined period. CONSTITUTION:On the basis of the operating condition of engine, a microcomputer 18 will set a flow control value of an idle speed control valve and a corresponding target integrated value. Then on the basis of pulse signals from a timer 15 to be produced with predetermined period, a flip-flop 14 is set to bring the output into H-level thus to turn on a transistor 12 and to start conduction of power to an electromagnetic coil 11 to move the valve body in the opening direction. Thereafter, the current flowing through said coil 11 is accumulated on the basis of the terminal voltage of a resistor 16 for detecting the current and upon decision that the accumulated value has reached to a target value, the flip-flop 14 is reset to bring the output into L-level thus to turn off the transistor 12 and to finish power conduction to said coil 11.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an electromagnetic idle speed control that is installed in an auxiliary air passage bypassing the throttle valve of the intake system of an internal combustion engine to control the amount of auxiliary air. This invention relates to a valve drive circuit.

<Prior Art> Conventionally, this type of idle speed control valve has a valve body that is installed in an auxiliary air passage that bypasses the throttle valve of the engine intake system and controls the passage area by the movement position of the valve body, and a valve body that moves the valve body in the closing direction. It is equipped with a return spring that energizes and an electromagnetic coil that moves the valve body in the opening direction when energized, and by duty-controlling the energization to the electromagnetic coil, the movement position of the valve body is controlled and the passage area is controlled. Controlling the idle speed by controlling the amount of auxiliary air (Utility Application No. 10357/1986
(See No. 9).

<Problems to be Solved by the Invention> However, in such conventional idle speed control valves, a flow control value determined based on the engine operating state is converted into a duty signal by a triangular wave generator and a comparator. The desired flow rate is obtained by converting the converted voltage and applying it to the electromagnetic coil, but even if the duty ratio is constant, due to fluctuations in the power supply voltage, changes in coil resistance due to ambient temperature or heat generation in the coil due to energization, etc. There is a problem in that the actual flowing current changes and the flow rate changes, resulting in deterioration of control accuracy.

In view of these conventional problems, the present invention has been devised to suppress variations in flow rate by driving an electromagnetic coil with a drive amount corresponding to a flow rate control value, regardless of fluctuations in power supply voltage or temperature changes in coil resistance. The purpose is to provide a drive circuit for an idle speed control valve that can be used.

Means for Solving the Problems> For this reason, the present invention, as shown in FIG. a current detection means, an integration means for integrating the detected current, a comparison means for comparing the integral value of the detected current with a target integral value corresponding to the flow rate control value, and a comparison means for comparing the integral value of the detected current with a target integral value corresponding to the flow rate control value; Sometimes, an illumination termination means for terminating the energization of the electromagnetic coil is provided,
This constitutes the drive circuit for the idle speed control valve.
be.

<Operation> In the above configuration, i is applied to the electromagnetic coil at a predetermined period.
After starting energization, duty control is performed by detecting and integrating the current flowing through the current coil, and terminating energization when the integrated value reaches a target integrated value corresponding to the flow rate control value. Therefore, even if there are fluctuations in the power supply voltage or temperature changes in the coil resistance, if the flow rate control value is constant, the integral value of the drive current will be constant and there will be no fluctuation in the flow rate.

<Example> The present invention will be explained in detail below.

An example of an idle speed control valve is shown in FIGS. 2 to 4, and this will be explained first.

A valve seat 3 having a cylindrical surface is formed in a housing 2 having a passage 1 forming a part of an auxiliary air passage that bypasses the throttle valve of the engine intake system. section and downstream are connected. A valve body 4 having a cylindrical surface is fixed to one end of a hollow rotor 5 and slides on the valve seat 3, and the rotor 5 is rotatable on a fixed shaft 6 via bearings 7 and 8. is supported by Therefore, the valve body 4 is rotatable around the fixed shaft 6, and as the valve body 4 rotates, the passage area of the opening 3a formed in the valve seat 3 is controlled.

A helical return spring 9 is interposed between the rotor 5 and the housing 2, which rotate together with the valve body 4, and this return spring 9 moves the valve body 4 in the closing direction (counterclockwise in FIG. 3). is energized.

The rotor 5 is made of a magnetic material and has a protrusion 5a.

5b. A yoke (yoke) 10 having protrusions 10a, 10b surrounding these protrusions 5a, 5b.
is fixedly placed. Further, an electromagnetic coil 11 for exciting the yoke 10 is also fixedly arranged. Here, if the electromagnetic coil 11 is energized, the protrusion 1 of the yoke 10
A suction force acts between 0a, 10b and the protrusions 5a, 5b of the rotor 5, and the rotor 5 and therefore the valve body 4 can be rotated in the opening direction (clockwise in FIGS. 3 and 4).

Therefore, by duty-controlling the energization to the electromagnetic coil 11, the torque in the valve opening direction is controlled, and the valve body 4 is brought to a position where this torque and the biasing force of the return spring 9 are balanced.
By controlling the passage area of the opening 3a, the amount of auxiliary air can be controlled thereby, and the idle speed of the engine can be controlled.

Next, a first embodiment of the drive circuit for the idle speed control valve will be described with reference to the circuit diagram of FIG. 5 and the flowchart of FIG. 6.

Referring to FIG. 5, one end of the electromagnetic coil 11 of the idle speed control valve is connected to a power source VB, and a transistor 12 is connected in series to the ground side of the other end. 13 is electromagnetic coil 1
This is a diode connected in parallel to 1 to prevent back electromotive voltage generation.

The transistor 12 is controlled on/off by the output of the flip-flop 14.
The set (S) terminal has a predetermined period T (for example, 2On+
s), a timer 15 is connected as an energization start means for generating a pulse signal. A reset signal is input to the reset (R) terminal of the flip-flop 14 from a microcomputer 18, which will be described later.

Further, a current detection resistor 16 as a current detection means is inserted in series on the ground side of the transistor 12, and the terminal voltage of this resistor 16 is inputted to the microcomputer 18 via an A/D converter 17.

The microcomputer 18 determines the flow rate control value by the idle speed control valve based on the engine operating state detected by various sensors (not shown), and also determines the flow rate control value by the idle speed control valve, and also controls the flip-flop 1 according to the flowchart in FIG.
Perform the reset in step 4.

To explain along the flowchart of FIG. 6, in step 1 (indicated by Sl in the figure, the same applies hereinafter), a target integral value A corresponding to the flow rate control value determined by a separate routine is set.

Next, in step 2, it is determined based on the terminal voltage of the current detection resistor 16 whether or not the 3m current to the electromagnetic coil 11 has started.

Here, the flip-flop 14 is turned on by a pulse signal from the timer 15 that is generated at a predetermined period T, and when its output becomes H level, the transistor 12 is turned on and energization to the electromagnetic coil 11 is started. and,
Proceed from step 2 to step 3.

In step 3, the current i flowing through the electromagnetic coil 11 is read based on the terminal voltage of the current detection resistor 16, and in the next step 4, the current i is integrated. Then, in the next step 5, the integrated value, that is, the integrated value Σi, is compared with the target integrated value A, and when Σl<A, the process returns to steps 3 and 4 to continue detecting and integrating the current i. The portion of step 3.4 corresponds to the integrating means, and the portion of step 5 corresponds to the comparing means.

When it is determined in step 5 that the integral value Σi has reached the target integral value A (Σi≧A), the process proceeds to step 6 and the flip-flop 14 is reset.

As a result, the output of the flip-flop 14 becomes L level, the transistor 12 is turned off, and the electromagnetic coil 1
1 is terminated. This step 6 corresponds to the 11I1I1IlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIiIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIlIl IlIl IlIl IlIl IlIl IlIl IlIl IlIl IlIl IlIl IlIl IlIl IlIl IlIl IlIl IlIl IlIl Il Il Il Il Il Il Il Il Il electric end means portion of this step 6.

After this, in step 7, Σl is cleared for the next integration.

By controlling the on-time of the duty control so that the integral value of the drive current becomes the target integral value corresponding to the flow rate control value, the flow rate can be controlled even if there are fluctuations in the power supply voltage or temperature changes in the coil resistance. If the value is constant, the integral value of the drive current will be constant and there will be no flow rate fluctuation.

Incidentally, the setting of the flip-flop 14 by the timer 15 may be performed by software by the microcomputer 18.

Next, a second embodiment of the drive circuit for the idle speed control valve will be described with reference to FIG.

In this embodiment, an integrating circuit 21 as an integrating means including a resistor 21a and a capacitor 21b is connected to a terminal of a current detecting resistor 16 as a current detecting means. A contact point between the resistor 21a and the capacitor 21b is connected to the + side input terminal of a comparator 22 serving as comparison means and energization termination means. Then, the output terminal of the comparator 22 is connected to the reset (R) terminal of the flip-flop 14, and
It is connected to the heath terminal of the transistor 23 connected in parallel to the capacitor 21b. Note that a flow rate control value determined by a microcomputer (not shown) is connected to one input terminal of the comparator 22 through a D/A converter (not shown).
It is configured such that it is converted into a voltage via the converter and inputted as the target integral value A.

To explain the operation, timer 1 occurs at a predetermined period T.
When the flip-flop 14 is turned on by the pulse signal from the transistor 5 and its output goes to H level, the transistor 12 is turned on, and the electromagnetic coil 11 starts to be energized.

When energization is started, the capacitor 21b of the integrating circuit 21 is charged based on the terminal voltage of the current detection resistor 16 that is generated in response to the current flowing through the electromagnetic coil 11. When the charging voltage of the capacitor 21b corresponding to the integral value of the current reaches the target integral value (voltage) A corresponding to the flow rate control value, the output of the comparator 22 becomes H level and the flip-flop 14 is reset.

As a result, the output of the flip-flop 14 becomes L level, the transistor 12 is turned off, and the electromagnetic coil 1
1 is terminated. At the same time, comparator 2
2 turns on the transistor 23 connected in parallel to the capacitor 21b, and the capacitor 21b is rapidly discharged.

<Effects of the Invention> As explained above, according to the present invention, even if there are fluctuations in the power supply voltage or temperature changes in the coil resistance, as long as the flow rate control value is constant, the integral value of the drive current to the electromagnetic coil is Since the flow rate becomes constant and there is no flow rate fluctuation, it is possible to reduce the flow rate variation and improve control accuracy.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a front sectional view showing an example of an idle speed control valve, FIG. 3 is a side sectional view of the valve body portion of the control valve, and FIG. The figure is a side sectional view of the rotor and yoke portion of the control valve, FIG. 5 is a circuit diagram of the drive circuit showing the first embodiment of the present invention, FIG. FIG. 2 is a circuit diagram of a drive circuit showing a second embodiment.

Claims (1)

[Claims] A valve body that is provided in an auxiliary air passage that bypasses a throttle valve of an engine intake system and controls the passage area by its movement position, and a return spring that biases the valve body in a closing direction.
In an idle speed control valve for an internal combustion engine, which includes a duty-controlled electromagnetic coil that moves a valve body in an opening direction when energized, an energization start means that starts energizing the electromagnetic coil at a predetermined period, and a current flowing through the electromagnetic coil. current detecting means for detecting the detected current, integrating means for integrating the detected current, comparing means for comparing the integral value of the detected current with a target integral value corresponding to the flow rate control value; A drive circuit for an idle speed control valve, comprising an energization termination means for terminating energization to an electromagnetic coil when the energization occurs.