JPS6312845A - Throttle opening control device - Google Patents

Abstract

PURPOSE:To improve controllability, by a method wherein, in a device which electrically controls the opening of a throttle by means of a stepping motor and the like, once a control signal from a CPU is held at a latch circuit, it is outputted in synchronism with a hardlike timer output. CONSTITUTION:In a device which drives a throttle valve to control the opening of a throttle valve, located in the suction passage of an internal combustion engine, with the aid of a stepping motor 3 controlled by a control circuit 4 according to a running state, a latch circuit 42, holding a motor output pattern set by a CPU 41, is situated to the control circuit 4. The latch circuit 43 is provided for outputting a motor output pattern to a motor driver circuit 45 in synchronism with the timing of a program timer output outputted from the CPU 41 according to an output from the latch circuit 42. Further, a gate circuit 44 is provided for preventing production of a pattern input, by means of which damage of the motor drive circuit 45 is caused.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for electronically controlling throttle opening, and more particularly to a method of outputting information to a motor of a device controlled using a microcomputer.

[Conventional technology]

Regarding the conventional device of this kind, Japanese Patent Application Laid-Open No. 57-4172
Although there is a system idea as shown in Publication No. 9, no consideration has been given to the specific method of outputting it to the motor.

[Problem that the invention seeks to solve]

Such conventional devices have the disadvantage that when electrically controlling the throttle opening using a motor (particularly a stepping motor) as a power source, a control signal cannot be reliably output to the motor.

An object of the present invention is to provide a method for reliably outputting a control signal to the motor without causing malfunction of the motor when electrically controlling the throttle opening using a motor (particularly a stepping motor) as a power source. It is about providing.

[Means for solving problems]

For a motor that rotates in stages, such as a stepping motor, if the control cycle before moving to the next stage is too short, the motor operation will not respond to the control signal, resulting in so-called step-out (the torque required to keep it in that position) is too short. phenomenon) occurs. In the present invention, the output of a control signal from a microcomputer (hereinafter referred to as CPU) is temporarily held in a latch circuit, etc., and is output to the motor in synchronization with a hardware timer output to ensure the minimum cycle. It is distinctive in that it did so.

〔Example〕

Examples of the present invention will be described below.

FIG. 1 is an example of a functional block diagram of a circuit related to the present invention, and FIG.
Fig. 3 shows an example of a flowchart showing an outline of control, and Fig. 3 shows an example of an output turn diagram of a stepping motor (an example of Wl-2φ control). explain.

In recent years, there has been an increasing trend to electrically (electronically) control the throttle opening for the purpose of improving drivability (preventing surging, improving stumpling, and easing deceleration shock). Normally, when controlling the throttle opening degree electrically, a motor is used as the power source. In addition, when controlling a motor digitally, current is passed through multiphase excitation coils, such as in a so-called stepping motor.

By controlling the non-current flow according to a regular pattern, the motor that rotates the rotor in stages can be easily controlled.
It is suitable due to conditions such as high accuracy.

FIG. 3 is an example of an output pattern of a Wl-2φ excitation stepping motor.

Connect this to the input/output line A of the motor driver circuit in Figure 1.
” In contrast to B c and A′ to D′, if the motor input cover turn is currently located at the position of the sign in Fig. 6, the output of the excitation coils A@ and B@ will be A′ → When a constant current is flowing in the direction of A', B'→■' and the input AC is 1, the current flowing from X' to A' is 40% of that when Ac=0.The rotor is ,
Two-phase coils A' and B' facing each other at an electrical angle of 90°
It is held at the position of the resultant angle of the current vector, and is held at the position shown in Figure 4. Next, when the input cover pattern changes as shown in Fig. 3C, a force acts to fix the rotor at the position shown in Fig. 4C, and in the pattern shown in Fig. 3a, it is fixed at the position shown in Fig. 4a. .

Therefore, by changing the input cover turns one after another as shown in Figure 3, the motor can be moved in the Di direction as shown in Figure 4 by shifting the pattern in the direction of 1) -*Q, and conversely, the b-+a force direction is D2.
rotate in one direction after another. Therefore, in order to control the motor position (throttle opening), the number of changes in the pattern (step number) from the current position, and in order to control the motor rotation speed, it is necessary to change from one pattern to the next. It is sufficient to individually control the period of movement.

As a specific control method, for example, a method as shown in the flowchart of FIG. 2 can be cited.

In other words, run the program with regular interrupts.

Timer ■When an interrupt occurs, the accelerator opening is captured as a digital voltage via the A/D converter shown in Figure 1, and the throttle opening (current position) is captured in the same way.
The rotational direction of the motor and the target number of steps are calculated, and the motor rotational speed is set based on information from various operating state sensors. Accordingly, the above-mentioned pattern is output to the motor driver circuit (6).

However, a problem here arises when the cycle of changing the output pattern of the motor to the next stage is too short. The rise of the current when passing through the excitation coil has a delay characteristic due to the coil's interface, so if the output pattern change period is short, the current will move to the next pattern before it reaches the predetermined value. As a result, sufficient torque cannot be obtained at that position, resulting in a phenomenon in which the rotor movement cannot follow the movement of the output pattern (step-out). For safety reasons, the throttle normally has a return spring that closes the throttle when the motor is no longer energized, and if the above-mentioned step-out occurs, the throttle will be fully closed, which will seriously affect the driving performance of the car. This is an undesirable phenomenon.

In the present invention, as a solution to the above problem, a circuit configuration as shown in FIG. 1 is adopted. In other words, the latch circuit that holds the motor output turn set by the CPU ■42. In accordance with the output of the latch circuit (2), the latch circuit (43, pattern to the motor excitation coil) outputs the motor output pattern to the motor driver circuit 45 in synchronization with the timing of the programmable timer output output from P21 of the CPU. The latch circuit 143 and the driver circuit 4 are connected in front of the motor driver circuit 45, which supplies current as described above in accordance with the above, in order to prevent pattern input that would damage the driver circuit 45.
ROM 49 and RAM 401 .5 for securing a storage area for the gate circuit 44 and the CPU. Its main component is a decoder 402 that separates the address of each element.

) In this configuration, set the motor output pattern and write the pattern to the latch l as shown in FIG.

Pattern output to the latch driver circuit synchronized with the output of the timer ■, setting of an interrupt flag by the output of the timer ■, setting of the next output pattern by the CPU...
By creating a routine that sequentially returns the patterns, the minimum pattern change cycle will be ensured even if the next pattern output timing comes while other tasks are being executed.

In other words, if a circuit different from latch n43 in FIG. 1 is not provided, as shown in FIG. 5, for example, Td
At Te, if a relatively long task is being executed and an interrupt occurs from the timer ■ that determines the output cycle of the motor, the output to the driver circuit for the next output pattern will be determined by the end of that task. It will be done soon afterwards. In this case, the pattern output is as shown by the broken line, and Td'
Since the pattern output that should be output at time T8' is delayed, a phenomenon in which the pattern change cycle becomes shorter as in tg tz occurs, and there is a risk that the motor may step out at this point. On the other hand, if latch ■ is provided, even if the next pattern is interrupted in latch I, no output will be generated until the next timer ■ pulse is input, so the minimum required cycle is always ensured and the motor The minimum necessary torque is always maintained and stable control can be achieved.

In this example, the latch≠742 was used in the previous stage as the output element to the latch ■, but it is possible to use an output port with a similar function in the CPU, and as the timer ■ , it is also possible to use a programmable timer circuit outside the CPU.

〔Effect of the invention〕

According to the present invention, since it is possible to reliably control a motor such as a stepping motor that has a limited starting frequency, it is possible to reliably control the throttle without impairing the drivability of the vehicle.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a flowchart of the embodiment shown in Fig. 1, Fig. 3 is a diagram showing a motor control pattern, and Fig. 4 is a supplementary explanatory diagram of Fig. 3. , FIG. 5 is a time chart. 4...Control circuit, 41...CPU, 42.43...
- Latch circuit, 44... Gate circuit, 45... Driver circuit, 46... Drive circuit, 47... Pulse circuit, 48... A/D circuit,
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Claims (1)

[Claims] 1. The first method of changing the amount of air flowing into the internal combustion engine of a car
A second means as a power source for electrically driving the first means, and a third means for electronically controlling the second means. The third means includes a fourth means for generating a digital output for controlling the second means, a fifth means for holding the output of the fourth means, and a time period. 6th for
and a seventh means for generating an output for driving a motor according to the output of the fifth means in synchronization with the output of the sixth means. Control device.