JPH01227841A - Engine controller - Google Patents

Abstract

PURPOSE:To prevent the braking phenomenon caused by the back electromotive force by mounting a flywheel diode on a motor which drives the output regulation means for an engine and cutting the current through the flywheel diode when the motor current is cut. CONSTITUTION:A throttle valve 1 which is the output regulation means for an engine is driven to be opened and closed by the normal and the reverse revolution of a motor 3. The motor 3 is controlled by a throttle controller 4, a servo controller 5 and a driving circuit 6. Four transistors Tr1 to Tr4 which turns the motor 3 in the normal and the reverse direction are integrated into the driving circuit 6. A flywheel diode and a plurality of relays 17 to 20 are connected in series between the emitter and the connector of each pair of the transistors Tr1 to Tr4. Each of the relays 17 to 20 is controlled by the signal which is the current cutting signal of the CPC 9 in the servo controller 5 amplified by an amplifier 21.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine throttle control device that controls the drive of output adjusting means such as a throttle valve through an electric actuator.

(Prior art) In the engine of a vehicle, output adjustment means such as a throttle valve are generally mechanically connected to the accelerator pedal via a wire, and in that case, the throttle position, that is, the throttle valve opening and the rack position, are determined by the accelerator pedal. It is primarily determined by how firmly the pedal is depressed, that is, how the accelerator is operated. However, in this type of control where there is a unique relationship between the accelerator operation base and the throttle position, that is, an l-to-l correspondence, even when a particularly high output is required, such as during acceleration, the amount of accelerator depression is simply controlled. Therefore, it is difficult to accurately respond to various required driving conditions.

Therefore, we have attempted to achieve engine control that always meets the driver's will by connecting the accelerator pedal and throttle valve via an electric actuator, and operating the actuator with characteristics according to each required driving condition. Various types of embankments have been proposed in the past. For example, in the vehicle accelerator control device described in Japanese Patent Application Laid-Open No. 60-198343, a plurality of functional characteristics between accelerator operation l and throttle valve opening are set, and one of them is set based on the accelerator operation speed. The target throttle valve opening degree is determined in accordance with the selected function characteristics.

By the way, in such an electric throttle valve control device, a direct current motor is driven and controlled by a microcomputer, and the throttle valve is opened and closed thereby.In this case, in order to switch the polarity of the motor, A drive circuit consisting of four transistors, for example in an H-shaped arrangement, is provided.

Furthermore, in such a device that controls a motor via a transistor, a flywheel diode is usually installed between the emitter and collector of the transistor. The flywheel diode works, in part, to increase the responsiveness of motor drive control by bypassing the electrical energy stored in the coils in the motor to the transistor when switching the motor current.

The flywheel diode also serves to protect the transistor by releasing surge voltage generated when switching the motor current to the outside. However, when using a drive circuit with a flywheel diode installed between the emitter and collector of a transistor, if something goes wrong, such as a failure in the control circuit, the motor current is cut and the throttle valve is fully closed. When something is considered indispensable, it causes inconveniences like the one mentioned above. That is, when the motor current is cut off, the motor is forcibly rotated in the fully closed direction by the force of the return spring of the throttle valve.

If a closed circuit is formed by the flywheel diode at this time, a braking phenomenon will occur due to current flowing through the motor due to the back electromotive force, and the return of the throttle valve will be delayed. It is a big problem that even though the throttle valve must be closed quickly in such an abnormal situation, it takes a long time to return to the fully closed state.

(Object of the Invention) The present invention has been made in view of the above-mentioned problems, and is intended to solve the problem in that the engine control device has a flywheel diode installed in the drive circuit of the motor that drives the output adjustment means. The purpose is to prevent braking phenomena caused by electromotive force and ensure responsiveness of throttle control in the event of an abnormality.

(Structure of the Invention) The present invention has found a means to ensure the function of the flywheel diode when the motor current is applied, and to free the motor and avoid the braking phenomenon when the motor current is cut. Its structure is as follows. That is, an engine control device according to the present invention is an engine control device in which an engine output adjustment means is driven by a DC motor, and a flywheel diode is provided between the emitter and the collector of a transistor for switching the polarity of the DC motor. In addition, the present invention is characterized in that a cutting means is provided for cutting the current flowing through the flywheel diode when the motor current is cut.

(Function) When the motor current is applied, the motor rotates in forward and reverse directions by switching the polarity using the transistor, thereby driving the output adjustment means of the engine. At this time, the flywheel diode allows the electrical energy stored in the coil in the motor to flow bypassing the transistor during current switching, thereby improving the responsiveness of motor drive control.

Furthermore, when the motor current is cut, the current flowing through the flywheel diode is cut, so the motor becomes free, and the occurrence of braking due to back electromotive force is suppressed. Therefore, the responsiveness of throttle control at abnormal times is improved.

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

FIG. 1 is an overall diagram of a servo system according to an embodiment of the present invention applied to control of a throttle valve.

In this embodiment, the throttle valve l is connected to a motor 3 (throttle actuator) via a wire 2 (throttle cable), and is driven to open and close by the forward and reverse rotation of the motor 3.

The control system for the motor 3 includes a throttle controller 4, a servo controller 5, and a drive circuit 6.

The throttle controller 4 calculates a target value for the throttle opening based on signals such as the output signal of the accelerator sensor 8 that detects the amount of depression of the accelerator pedal 7, the engine speed, the vehicle speed, the slope, the steering angle, and the water temperature. An abnormal signal is determined and two signals, a throttle valve target opening signal and a motor cut signal, are output to the servo controller 5.

The servo controller 5 is a microprocessor (CPU).
) 9, and an AD converter 10 is installed around the CPU 9.
．． A ROM 11 and a RAM 12 are attached. C.P.
U9 is also provided with a counter 13 for performing pulse conversion (PWM) on the CPU internal value (duty). The reference clock of the counter 13 is a signal from an external crystal oscillator 14 divided by a flip-flop 15, and has a frequency of about 4 MHz. The frequency of the counter 13 is 1/256 of the 4 MHz clock (duty is 8 bits), which is approximately 15 KHz. The servo controller 5 also includes a logic circuit 16 that receives three signals as described below.
The drive circuit 6 is configured to be controlled by the four outputs of the logic circuit 16.

The drive circuit 6 includes four transistors T, 1, T, 2, . T, 3. T
, 4. A flywheel diode and relays 17, 18, 19 are connected between the emitter and collector of each transistor T, 1 to T, 4, respectively.
．． 20 are connected in series. Each of the relays 17 to 20 is controlled by a signal obtained by amplifying a current cut signal from the CPU 9 by an amplifier 21. If the current cut signal is at a high level (1), the output of the amplifier 21 is also high, and at this time the relays 17 to 20 are closed. Further, when the current cut signal becomes low level (0), the output of the amplifier 21 also becomes low, and the relays 17 to 20 are opened.

When both the first transistor T,1 (PNP) and the fourth transistor T,4 (NPN) conduct, the motor 3 rotates in the forward direction, that is, in the throttle valve l opening direction, and the second
When both the transistor T,2 (NPN) and the third transistor (PNP) are conductive, the throttle valve 1 rotates in the opposite direction, that is, in the direction in which the throttle valve 1 is closed.

A position sensor 22 is attached to the motor 3 to detect the actuator position.

The target opening signal of the throttle valve 1 outputted by the throttle controller 4 is analog, and is converted into a digital signal by the AD converter IO and sent to the CPU 9.

Similarly, the output of the position sensor 22, which detects the throttle valve opening degree based on the actuator position, is also AD converted and inputted by the CPU 9. The CPU 9 uses the position sensor 22
The output value (throttle valve opening) is compared with the target opening, and the control (P,1) is made up of three terms: proportional, integral, and differential.

D control) calculates the current value and current direction to be passed through the motor 3. The calculated current value is then converted into an 8-bit duty value, converted into a pulse by the counter 13, and output. The logic circuit 16 contains this pulse-converted duty signal, a current direction signal corresponding to the calculated current direction, and a current cut signal outputted by the CPU in response to the motor cut signal from the throttle controller 4. Three signals are input.

The logic circuit 16 is composed of seven logic elements, and its four output terminals are connected to four transistors T, 1 . T, 2. T.

The bases of 3, T, and 4 are connected to each other.

The first transistors T and l are controlled by a logic circuit that uses an exclusive OR circuit to invert the output of an AND circuit that receives two inputs, a duty signal and a current direction signal. In other words, when both the duty signal and the current direction signal are at high level (1), this transistor T,
1 becomes conductive when the base becomes low level. Also, the fourth
The transistor T, 4 is controlled by the output of an AND circuit that manually inputs a current direction signal and a current cut signal, and when both of these signals are at high level (1), the base becomes high level and conducts. do. Therefore, as long as the current cut signal is high (1) and the current direction signal is high (1), the fourth transistor Tr4 remains on, and the duty signal exclusively controls the rotation of the motor 3 in the opening direction. It will be controlled.

On the other hand, the third transistor T,3 receives the output of an AND circuit which has one input as the duty signal and the other input as a signal obtained by inverting the current direction signal in the exclusive OR circuit. It is controlled by a logic circuit that inverts the signal at . That is, when the duty signal is at a high level (1) and the current direction signal is at a low level (0), the bases of the transistors T, . . . 3 are at a low level and conductive. In addition, the second transistor T
, 2 are controlled by the output of an AND circuit which has one input as the inverted signal of the current direction signal and the other input as the current cut signal. In other words, this transistor T,2
When the current direction signal is at low level (0) and the current cut signal is at high level (1), the base level becomes high level and conducts.

Therefore, as long as the current cut signal is high (1) and the current direction signal is low (0), the second transistor Tr2
remains conductive, and the rotation of the motor in the closing direction is controlled exclusively by the duty signal.

Further, as long as the current cut signal is high (1) in this way, the relays 17 to 20 are closed and the flywheel diode is in a connected state, so that the normal flywheel diode function can be obtained.

When the current cut signal is at low level (0), the fourth and second transistors Tr4. Tr2 is non-conductive, and no current flows through the motor 3. Further, at this time, relays 17 to 20 are opened and the flywheel diode is cut. Therefore, the braking phenomenon is less likely to occur, and the throttle valve I can be fully closed and returned in a short time.

Table 1 shows three signals (DUTY: duty signal, D
IR: current direction signal; MCUT: current cut signal) and the logic of each transistor (Trl, T, 2, Tr3, T, 4).

Table 1 In this way, for the rotation of the motor in the opening direction, the first
and a fourth two transistors Tr1. 1st among Tr4
For the rotation of the motor in the closing direction, two transistors T, 3rd and 2nd.
3. Since the duty of only one of the transistors T, 2 and T, 3 is controlled, reliable duty control is performed without causing the problem of asynchronization between the two transistors. The first and fourth transistors T, 1. Tr4 and third and second transistors T, 3. Since T and 2 are not conductive at the same time, the CPU
Even if the output port goes out of control and the logic of the output port is not compensated for, the drive circuit 6 and motor 3 will not be burnt out due to short circuit. Furthermore, since the drive control of the motor 3 is performed via such a logic circuit 16, the CPU
The burden on software will be reduced.

FIGS. 2 to 7 show flowcharts for executing control in this embodiment.

First, FIG. 2 shows the main routine. The main routine consists of four subroutines S.t.S.4.

Start and initialize first (S.1). Then, the input signal from the position sensor 22 is sampled (S
・2). Then, based on this, a feedback calculation of the current value is performed by Pl and D control (S.3), and then a control is performed to determine whether or not to cut the motor current based on the motor cut signal (S.4).

The first subroutine 5-1 (FIG. 3) starts and first sets each boat as input or output. Next, the timer and PWM for interrupt processing
Initialize the counter.

Next, various registers used in calculations are initialized, and the process returns.

Next, the second input signal sampling subroutine S.2 shown in FIG. 4 will be explained. This subroutine starts, performs A/D conversion of the actuator position signal by the position sensor 22, and stores the data as a value TVOA. Next, the throttle valve target opening signal is A/D converted and the data is stored in a value called TVOT. This allows both analog signals to be converted into A/D
converted.

Next, the third feedback calculation subroutine S
・In 3 (Fig. 5), start, first read the output value TVOA of the position sensor 22, then set the target opening degree T.
Read the VOT value.

Then, the deviation ΔTV between the sensor output value TVOA and TVOT
Calculate O. Further, the current sensor output value TVOA of the position sensor 22 and the previous sensor output value TVOAL are subtracted to calculate the moving speed ΔSPD of the actuator position. Furthermore, the previously calculated deviation ΔTVO is added to the previous integrated value ΣΔTVO to obtain the integrated value ΣΔTVO.

Next, to the value obtained by multiplying the calculated deviation ΔTVO by the feedback constant KP of the proportional term, add the value obtained by multiplying the integrated value ΣΔTVO by the feedback constant Kl of the integral term, and from this, add the value obtained by multiplying the feedback constant Kl of the integral term to the speed ΔSPD calculated earlier. The motor current value FB is obtained by subtracting the product multiplied by the feedback constant KD.

Next, the current direction is determined depending on whether the current value FB is positive. Then, to set the flag for interrupt processing, first, if FB is positive, the current direction flag FDIR, that is, the boat output level flag PDIR that sets the direction of the motor current, is set to 0 (opening direction). shall be. Also, if FB is not positive, FD
Let IR be l (closing direction).

Next, for duty conversion, the absolute value of the current value FB is determined, and the current-duty conversion coefficient K du
The duty value is obtained by multiplying by ty.

Finally, the previous value TVOAL of the sensor output value used for calculating the differential term is updated to the current TVOA.

FIG. 6 shows the fourth current cut subroutine S.4.
It shows. This routine starts and first reads the current cut input from the throttle controller 4. Then, it is determined whether or not the current is to be cut, and if it is determined that the current is to be cut, the CPU 9's current cut port (M
CUT) to low (current cut) to ensure that the transistor does not conduct, and when the current is not cut, set the current cut port to high (current conduction).

This completes the main routine of this embodiment, but apart from this there is a timer interrupt processing routine shown in FIG. This interrupt processing is started at regular intervals (1 to 2a+s), and when started, it first reads the interrupt processing cycle (T I NT) and then sets the next interrupt time. Therefore, the cycle TINT is added to the current time and stored in the interrupt register.

Next, to read the PWM duty (DUTY), read the value DUTY obtained in S.3 of the main routine, and to set the PWM timer, store the value DUTY in the PWM timer register. . In other words, write to the counter. S・1
Since the counter has been initialized, the counter outputs a pulse according to the value of DUTY from the time of writing.

Next, the current direction is determined by looking at the current direction flag PDIR set in S.3 of the main routine. And F
If DIR is 0, the DIR boat is set to high level (in the open direction), and if FDIR is not 0 (1), the DIR boat is set to low level (in the closed direction).

In this embodiment, the output of the position sensor that detects the actuator position is used as the feedback signal, but instead of detecting the actuator position, the output of the throttle sensor that directly detects the throttle position may of course be used as the feedback signal. It is possible.

Further, in the above embodiment, the motor drive circuit is controlled via a logic circuit, but the present invention can also be applied to a device in which the drive circuit is directly controlled by the output of the CPU. It is.

Furthermore, the present invention is applicable not only to throttle valve control but also to engine control using other output adjustment means.

(Effects of the Invention) Since the present invention is configured as described above, the back electromotive force generated when the motor current is cut in an engine control device in which a flywheel diode is provided in the drive circuit of the motor that drives the output adjustment means of the engine can be reduced. Therefore, the responsiveness of throttle control at the time of abnormality can be ensured.

[Brief explanation of the drawing]

FIG. 1 is an overall diagram of an embodiment of the present invention, and FIGS. 2 to 7 are flowcharts for executing control of the embodiment. l: Throttle valve, 3: Motor (actuator), 4
: Throttle controller, 5: Servo controller,
6: Drive circuit, 9: Microprocessor (CPU), 1
7, 18, 19, 20: Relay, 22: Position sensor. Agent Patent Attorney Jun Shinfuji - Figure 6 S-4 Figure 7

Claims (1)

[Claims] (1) In an engine control device in which the output adjustment means of the engine is driven by a DC motor, a flywheel diode is provided between the emitter and collector of a transistor for switching the polarity of the DC motor, and when the motor current is cut, the flywheel diode is An engine control device characterized by being provided with a cutting means for cutting the current flowing through the diode.