JPH01272222A - Duty control signal forming device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is aimed at controlling the idle speed of an internal combustion engine! ! The present invention relates to a device for forming a duty control signal used in III, etc.

<Prior Art> In an electronically controlled fuel injection type internal combustion engine, an idle control valve is interposed in a passage that bypasses a throttle valve in the intake passage of the engine, and the energization duty of a pulse signal output to the idle control valve during idle is controlled. By controlling this, the opening degree of the idle control valve is controlled, and by controlling the bypass air flow rate, the idle speed of the engine is controlled.

<Problems to be Solved by the Invention> By the way, the duty ratio of the pulse signal output to the idle control valve is calculated by a microcomputer according to the engine operating state, and a pulse wave modulator (hereinafter referred to as PWM) built in the microcomputer is used to calculate the duty ratio of the pulse signal output to the idle control valve. ), a pulse signal with a calculated duty ratio is output.

However, current microcomputers have a built-in PWM with a resolution of 8 bits, but when using a large-capacity idle control valve, it is difficult to handle changes in duty per bit.
There was a problem that the air flow rate changed greatly and the control accuracy became low.

The present invention was made in view of such conventional problems, and uses a microcomputer equipped with a counter having a number of bits larger than the resolution of PWM, and has high resolution by adding an external circuit to this. It is an object of the present invention to provide a duty control signal forming device capable of forming a duty control signal.

<Means for Solving the Problem> A microcomputer that includes a pulse wave modulator that generates a pulse signal with an arbitrarily set period and a counter of a predetermined bit, and a signal that is input to a first input terminal. When the direction is reversed, the output signal is reversed in one direction, and when the signal input to the second input terminal is reversed in one direction, the output signal is reversed in the opposite direction. control duty time calculation means for calculating a time corresponding to a control duty with respect to a period of a pulse signal output from the pulse wave modulator;

counter starting means for starting the counter in synchronization with the reversal of each cycle; and outputting a one-shot pulse signal when the count value of the counter reaches a value corresponding to the time calculated by the control duty time calculating means. a one-shot pulse signal output means arranged in a microcomputer, and inputting the output signal of the pulse wave modulator to the first input terminal of the flip-flop, and inputting the output signal from the one-shot pulse signal output means to the first input terminal of the flip-flop. is input to the second input terminal of the flip-flop, and the output signal from the flip-flop, which has the same period as the pulse signal from the pulse wave modulator and has a set control duty, is output as a control signal. The configuration is as follows.

Function> The pulse wave modulator outputs a pulse signal with a set period to the first input terminal of the flip-flop.

When the duty ratio of the duty control signal to the idle control valve etc. is set by the microcomputer itself, the control duty time calculation means calculates the period of the pulse signal output from the pulse wave modulator.
Calculate the time corresponding to the control duty.

On the other hand, the counter activation means activates the counter in synchronization with the periodic inversion of the signal from the pulse wave modulator.

When the count value of the counter reaches a value corresponding to the time calculated by the control duty time calculation means, the one-shot pulse signal output means:
A one-shot pulse signal is output to the second input terminal of the flip-flop.

In such an operation, the output signal of the flip-flop is inverted in one direction in synchronization with the periodic inversion of the pulse signal from the pulse wave modulator inputted from the first input terminal.

Next, when the one-shot pulse signal output means outputs the one-shot pulse signal to the second input terminal of the flip-flop, the output signal of the flip-flop is inverted in the opposite direction.

Then, the cycle in which the output signal of the flip-flop is again inverted in one direction in synchronization with the inversion of the pulse signal from the pulse wave modulator is repeated.

The output signal of such a flip-flop has the same period as the period of the pulse wave modulator, and the duty ratio has a resolution of the set number of bits that maximizes the number of bits of the counter for the calculated value. The output signal is output to an idle control valve or the like as a duty control signal.

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

In FIG. 1 showing one embodiment, an electromagnetically driven idle control valve 5 is interposed in a bypass passage 4 formed by bypassing a throttle valve 3 in an intake passage 2 of an internal combustion engine 1. The valve opening degree of the valve 5 is controlled by controlling the duty ratio of the duty control signal output to the electromagnetic coil, and the idle rotation speed is brought to the target value by controlling the air flow rate flowing through the bypass passage 4. It is meant to be controlled.

A duty control signal output to the idle control valve 5 is generated by a device according to the present invention, which will be described later.

That is, the microcomputer 11 has a PWM IIA which outputs a pulse signal having an arbitrarily set period and a duty ratio set with a resolution of a predetermined bit (for example, 8 bits), and a pulse signal having a higher bit number (than the resolution of the PWM 11A). For example, a 16-bit) counter 11B is built-in.

On the other hand, a D-type flip-flop 12 is provided, and the flip-flop 12 is connected to a constant voltage VC from the power input terminal.
Enter C to operate.

The output signal from the output terminal PWM of PWMIIA of the microcomputer 11 is transmitted to the flip-flop 12.
is output to the first input terminal CLK of the flip-flop 12 in synchronization with the inversion of the signal from L level to H level.
The output signal of the output terminal page is inverted from H level to L level. The output signal is input to the interrupt terminal Xπ of the microcomputer, and when it is inverted to the L level as described above, it activates the counter 11B as described later.

The value counted by the counter 11B outputs a one-shot pulse signal, and this output signal is input to the second input terminal of the flip-flop 12 at τπ. When the one-shot pulse signal is inverted from the H level to the L level, the output level of the output terminal Q of the flip-flop 12 is inverted from the L level to the H level. Then, the output signal from the flip-flop 12 having such characteristics is inverted via the inverter 13 and output to the idle control valve 5.

Next, a control program executed by the microcomputer 11 will be explained based on FIGS. 2 and 3 and with reference to FIG. 4.

In the routine shown in FIG. 2, in step 1 (denoted as S in the figure), the counter 11B is initialized, and in step 2, PWMIIA is initialized and the period T of the pulse signal output from PWMIIA is set.

Next, in step 3, the duty ratio set according to the engine operating state of the duty control signal to the idle control valve 5 is read, and the duty ratio corresponding to the duty ratio with respect to the period of the pulse signal set in step 2 is read. The control duty time X is calculated. Such calculations are repeated at predetermined intervals to cope with changes in engine operating conditions. That is, the function of step 3 corresponds to the control duty time calculation means.

FIG. 3 shows a routine that is executed each time an interrupt signal inverted to L level is input to the interrupt terminal XVT of the microcomputer 11, and starts counting by the quantator 11B, and also connects the output terminal TH of the one-shot pulse signal. Settings are made so that when the counter 11B counts a value corresponding to the control duty time X, a one-shot pulse signal having a predetermined L level pulse width is output. That is, this routine corresponds to counter starting means and one-shit pulse signal output means.

As a result, when trying to control the duty ratio with a resolution of 10 bits, for example, the counter 11B performs a count every minute unit time obtained by dividing the period T by 2I@, and when the count value is equal to or greater than the control duty time X. When the one-shot pulse signal input terminal T
A one-shot pulse signal is output from A, and the output signal of the flip-flop 12 is inverted from L level to H level.

This signal is sent to the inverter 13 as a duty control signal.
When input to the idle control valve 5 via the PWMII
has the same period as the period of the pulse signal from A, and
Duty control is performed in which the period in which the duty control signal is at the L level is the energization duty period.

FIG. 4 shows the signal level state of each part during the control.

With such a configuration, the pulse signal from the PWMIIA can only provide a duty control signal with an 8-bit resolution, whereas the microcomputer 11
In cooperation with the built-in counter 11B and flip-flop 12, a duty control signal with a resolution of 16 bits is obtained. Therefore, the change in air flow rate due to the change in the opening degree of the idle control valve 5 with respect to the change in the duty ratio per bit can be halved, and even when a large capacity idle control valve 5 is used, good control accuracy can be obtained.

Although this embodiment shows an example in which the application is applied to the opening control of the idle control valve, it is of course applicable to the formation of duty control signals for other control loads, and it is possible to obtain high control accuracy at low cost. It will be done.

<Effects of the Invention> As explained above, according to the present invention, a duty control signal with a resolution exceeding that of the pulse wave modulator can be generated by using a microcomputer incorporating a pulse wave modulator and a counter, and a flip-flop. Therefore, it is possible to improve the control accuracy of the idle control valve opening degree and the like with a low-cost configuration.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention, FIGS. 2 and 3 are flowcharts showing the control routine of the above embodiment, and FIG. 4 shows the signal level state of each part during the control. This is a time chart. 11... Microcomputer 12... Flip-flop patent applicant Japan Electronics Co., Ltd. Representative Patent Attorney Fujio Sasashima Figure 2 Figure 3 Figure 4 Figure 1 (msn.

Claims (1)

[Claims] A microcomputer that includes a pulse wave modulator that generates a pulse signal with an arbitrarily set period, a counter of a predetermined bit, and a signal input to a first input terminal that is inverted in one direction. a flip-flop which has a function of inverting the output signal in one direction when the second input terminal inverts the output signal in one direction and inverting the output signal in the opposite direction when the signal input to the second input terminal inverts in the other direction; control duty time calculation means for calculating a time corresponding to a control duty with respect to the period of the pulse signal output from the pulse wave modulator; and a one-shot pulse signal output for outputting a one-shot pulse signal when the count value of the counter reaches a value corresponding to the time calculated by the control duty time calculation means. and means for inputting the output signal of the pulse wave modulator to the first input terminal of the flip-flop, and inputting the output signal from the one-shot pulse signal output means to the first input terminal of the flip-flop. The output signal from the flip-flop, which has the same period as the pulse signal from the pulse wave modulator and has a set control duty, is output as a control signal. Features: Duty control signal forming device.