JPH0773984B2 - Control circuit of constant-speed traveling device for vehicle - Google Patents

Description

TECHNICAL FIELD The present invention relates to a control circuit for a vehicle constant speed traveling device.

<Prior Art> Generally, various constant speed traveling devices for maintaining a vehicle speed at a predetermined set speed have been known. According to such a constant speed traveling device, by operating the accelerator pedal to operate the set switch when a desired vehicle speed is reached,
An actuator that operates in the same manner as the accelerator pedal operates, and even if the foot is subsequently released from the accelerator pedal, the vehicle speed can be maintained at the set speed.

As an actuator of such a constant speed traveling device, there is an actuator using a motor type actuator which has a relatively compact structure and can be controlled with high accuracy. In the control circuit for accelerating and decelerating by the motor type actuator, it is conceivable that the motor drive circuit is configured using a transistor bridge circuit.

In such a constant-speed traveling device, a watchdog timer circuit is provided as a fail-safe function, and when the CPU as the control means runs out of control, the watchdog timer circuit provides an abnormal output from the watchdog timer circuit. The clutch drive circuit of the magnetic clutch is turned off to prevent the actuator from operating. Therefore, the abnormality of the device can be avoided.

By the way, in the motor drive circuit of the actuator, when the CPU goes out of control, the output of all combinations of logic circuits can be considered as the output of the CPU, so the transistors cause a so-called dead short circuit and the transistors are destroyed. There is a problem with that.

Therefore, in a forward / reverse drive circuit for a motor using a transistor bridge circuit, as disclosed in, for example, Japanese Patent Laid-Open No. 119682/1982, between two transistors which should not be conducted at the same time, one is conducted by the other. It is considered to provide a protection circuit for making the transistor non-conductive to prevent the transistor from being destroyed due to a so-called dead short.

However, since the motor drive current flows through the protection circuit, it is necessary to configure the protection circuit using a large element such as a power transistor, which may cause a problem such as a relatively high cost of parts.

<Problems to be Solved by the Invention> In view of the above-mentioned problems of the prior art, the main object of the present invention is to destroy the transistor constituting the transistor bridge circuit of the actuator drive circuit even when the control means runs away. It is to provide a control circuit for a vehicle constant speed traveling device that does not do so.

<Means for Solving Problems> According to the present invention, such an object is to provide a control means for performing arithmetic control to generate a control signal so as to maintain the vehicle speed at the set vehicle speed, and a vehicle speed control operation based on the control signal. Drive means having an acceleration circuit and a deceleration circuit composed of a transistor bridge circuit for driving a motor actuator for carrying out the above, an abnormality detection means for detecting an abnormality of the control means, the abnormality detection means and the transistor bridge. A transistor provided on the power supply side of the motor for each of the acceleration circuit and the deceleration circuit among the transistor group that is provided between the circuit and receives the abnormality detection output from the abnormality detection means, and that constitutes the transistor bridge circuit. Abnormality that prohibits the input of the control signal from the control means to the base of both and renders both of them non-conductive This is achieved by providing a control circuit for a vehicle constant speed traveling device characterized by having a time transistor control means.

<Operation> In this way, when the control means runs out of control, the abnormal output of the watchdog timer circuit is detected, and the abnormal-time transistor control means causes the power supply connected to the transistor bridge circuit to respond to the abnormal control signal. In order to make two transistors on the power supply side to the motor of the transistor bridge circuit non-conductive so as not to be short-circuited,
A dead short state does not occur between the transistors of the transistor bridge circuit. In particular, when an abnormality occurs, the malfunction of the actuator can be further prevented by disengaging the magnet clutch of the actuator.

<Examples> Hereinafter, preferred examples of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a circuit diagram showing a schematic configuration of a vehicle constant speed traveling device according to the present invention. The control of the constant speed traveling device is performed via the control unit 1, and in the control unit 1, a stabilized power supply circuit 2, an input control circuit 3, an input / output control circuit 4, and an actuator drive circuit 5 as a driving means. A motor current detection circuit 6 and a CPU 7 as a control unit that is connected to these circuits to perform arithmetic processing are provided.

The voltage supplied from the battery 8 as a power source is supplied to the terminal T1 of the control unit 1 through the ignition switch 9, the fuse 10 and the main switch 11. The other end of the main lamp 12 whose one end is grounded is connected between the main switch 11 and the terminal T1.

In the control unit 1, the power supply circuit 2 is connected to the terminal T1, and the voltage stabilized in the power supply circuit 2 is supplied to the CPU 7. As a power source for other circuits of the control unit 1, a power source terminal Vb is provided between the terminal T1 and the power source circuit 2, and a stabilized power source terminal is provided for the power source circuit 2.
Each Vc is provided.

A signal from the vehicle speed sensor 13 is input to the input control circuit 3 via the terminal T2, and signals from the set switch 15 and the resume switch 16 connected to the battery 8 via the common fuse 14 are respectively input to the terminal T3. , T4, and each signal that has passed through the input control circuit 3 is input to the CPU 7.

Furthermore, signals from the contacts S1 and S2 of the brake switch 18 attached to a brake pedal (not shown) are input to the control unit 1 as its control inputs via terminals T5 and T6. The contact S1 is a normally open contact, and is connected between a fuse 17 and a terminal T5, which are provided by branching between the battery 8 and the ignition switch 9.
The contact S2 is a normally closed contact, and the main switch 11 and terminal
It is connected between T1 and terminal T6. Further, as another control input, a signal from a clutch switch 19 attached to a clutch pedal (not shown) is input via a terminal T7. A brake lamp 20 is connected to the terminal T5.

The terminals T8 to T10 of the control unit are connected to the motorized actuator 21, and the terminal T8 is the actuator.
It is connected to a coil 22a of a magnet clutch 22 built in 21 and terminals T9 and T10 are connected to a motor 23, respectively. The actuator 21 drives an accelerator pedal (not shown) through a linkage (not shown) which is integrally operated via the magnet clutch 22 by rotating the motor 23 forward and backward. The terminal T10 is an output terminal for accelerating the vehicle, and a limit switch 24 for preventing overrun of the motor 23 is connected between the terminal T10 and the motor 23. The terminal T9 is an output terminal on the side that decelerates the vehicle. Further, the control unit 1 is grounded via the terminal T11.

In the control unit 1, the terminals T5 to T8 are connected to the CPU 7 via the input / output control circuit 4, respectively. That is, the contact S1 signal of the brake switch 18 from the terminal T5 and the contact S2 signal of the terminal T6 are input to the CPU 7 via the input / output control circuit 4, respectively.

The emitter of the transistor Q1 is connected to the terminal T6, and the collector of the transistor Q1 is connected to the terminal T8. A constant voltage diode ZD is connected between the emitter and collector of the transistor Q1. Transistor
A resistor R1 is connected between the emitter and the base of Q1, and the base of the transistor Q1 is connected to the collector of the transistor Q2 whose emitter is grounded via the resistor R2 and the diode D1. The diode D1 is connected in a direction in which a current flows from the transistors Q1 to Q2. Also, for the input signal of the magnet clutch 22, the collector of the transistor Q1 is connected to the CP via the input / output control circuit 4.
It is connected to U7. The base of transistor Q2 is a resistor
It is grounded via R3 and CPU7 via resistor R4.
It is also connected to the terminal CT1 of. And transistor Q
2 and Q1 turn on or off the coil 22a of the magnet clutch 22 according to the output signal from the CPU 7.

The actuator drive circuit 5 includes a known transistor bridge circuit for rotating the motor 23 in the forward and reverse directions according to the control output signal of the CPU 7. That is, as shown in the figure, the collector of the transistor Q3 is connected to the terminal T10,
It is connected to the collector of the transistor Q4 via the limit switch 24, the motor 23, and the terminal T9, and the current at acceleration flows in this order, and the collector of the transistor Q5 connects the terminal T9, the motor 23, the limit switch 24, and the terminal T10. It is connected to the collector of the transistor Q6 via, and the current during deceleration flows in this order.

As the power supply of this transistor bridge circuit, the emitter of the transistor Q3 is connected to the terminal T6 via the diode D2 to supply a voltage, and the emitter of the transistor Q5 is connected to the power supply terminal Vb via the diode D3. The voltage is supplied. The emitters of the transistors Q4 and Q6 are grounded via the motor current detection circuit 6. This motor current detection circuit 6 is the terminal of CPU7
It is also connected to CT2.

Since the power supply voltage of the acceleration side driving transistor Q3 is supplied from the terminal T6, the voltage to the acceleration side circuit is changed to the brake switch when releasing the constant speed running by the brake operation.
It will be surely shut off by 18.

Diodes D4 and D6 are connected to the transistors Q3 and Q5 with their cathodes to the emitters and their anodes to their collectors, respectively. Is connected towards. A resistor R5 is provided between the emitter and base of each transistor Q3 to Q6.
~ R8 are connected, and the collectors of the transistors Q7 to Q10 are connected to the bases of the transistors Q3 to Q6 via the resistors R9 to R12, respectively. And transistor Q7
The emitters of Q9 and Q9 are grounded, and their bases are also grounded via resistors R13 and R15. Also, the emitters of the transistors Q8 and Q10 are connected to the stabilized power supply terminal Vc, and the bases of each are also resistive.
It is connected to the stabilized power supply terminal Vc via R14 and R16. Further, the bases of the transistors Q7 to Q10 are connected to the signal output terminals CT3 to CT6 of the CPU 7 via the resistors R17 to R20, respectively.

By the way, the anode of the diode D8 is connected to the base of the transistor Q2 for driving the magnet clutch 22 described above, and the cathode of the diode D8 is the collector of the emitter-grounded transistor Q11 that constitutes the watchdog timer circuit 26 described later. Connected with. Further, the cathodes of the diodes D9 and D10, which cooperate with the transistor Q11 and act as transistor control means in abnormal state, are connected to the collector of the transistor Q11, and the anodes of the diodes D9 and 106 are respectively connected to the transistor Q11.
It is connected to the bases of 7 and Q9.

Next, the watchdog timer circuit 26 as an abnormality detecting means
The configuration of is shown below. From the terminal CT7 of the CPU7, for example, a pulse wave of 4Hz is normally output, but in the event of an abnormality the pulse wave is not output and a DC level output of 0V or 5V is output, or according to the reference clock in the CPU7. The generated high-frequency pulse of, for example, 400 kHz is output. The base of a transistor Q12 whose emitter is grounded is connected to the terminal CT7 via a capacitor C1 and a resistor R21. The base of the transistor Q12 is the capacitor C2.
And a resistor R22 in parallel with each other and are grounded. Further, the collector of the transistor Q12 is connected to the base of the transistor Q13. The collector of the transistor Q13 is connected to the stabilized power supply terminal Vc, is also connected to the base via the resistor R23, and the base is grounded via the capacitor C3. The emitter of the transistor Q13 is connected to the base of the transistor Q11 described above.

Next, the operation of the constant speed traveling device thus configured will be described.

When the main switch 11 is turned on with the ignition switch 9 closed, the power supply voltage is supplied to the control unit 1 and the main lamp 12 is turned on. Then, when the set switch 15 is turned on and, for example, the condition that the brake switch 18 and the clutch switch 19 are not operated is satisfied, the signal from the vehicle speed sensor 13 causes the vehicle speed at that time to be set as the set vehicle speed CP.
U7 remembers.

Next, depending on the difference between the set vehicle speed and the actual vehicle speed, the actuator
When driving 21, the CPU 7 outputs a signal for turning on the magnetic clutch 22, and the coil 22a is energized to bring the magnetic clutch 22 into a connected state. And
When accelerating, signals that turn on the transistors Q7 and Q8 are output from the terminals CT3 and CT4, and signals that turn off the transistors Q9 and Q10 are output from the terminals CT5 and CT6. Further, when decelerating, signals opposite to the above are output from the respective terminals. In this way, the motor 23 is rotated in the forward and reverse directions through the actuator drive circuit 5 and is controlled so that the actual vehicle speed and the set vehicle speed substantially match. The resume switch 16 is used to store a new set vehicle speed in the CPU 7 by pressing and releasing it when it is desired to raise the vehicle speed to a desired value.

Further, when the CPU 7 detects that the brake switch 18 or the clutch switch 19 is operated, for example,
The constant-speed running state will be canceled. Furthermore, a deceleration signal is output from the CPU 7 to the actuator drive circuit 5, and the vehicle is decelerated.

In the watchdog timer circuit 26 of the constant-speed traveling device configured in this way, the so-called bandpass filter is configured by the capacitor C1, the resistor R21, the capacitor C2 and the resistor R22, and from the terminal CT7 during normal operation. Output 4
Although it passes a Hz pulse wave, it is configured to block the DC level or high frequency pulse that is output in the event of an abnormality. Therefore, since the transistor Q12 is repeatedly turned on and off during normal operation, by keeping the charging time constant of the capacitor C3 relatively large, the capacitor C3 does not complete charging and the transistor Q12 does not turn on.
11 is held off.

By the way, when the CPU7 is abnormal, the output signals from the output terminals CT3 to CT6 may not be settled. A so-called dead short state occurs, which may cause the transistors Q3 and Q6 to be destroyed.

However, in the event of an abnormality, as described above, terminals CT7 to D
A signal of C level or 400kHz is output, and the transistor Q12 is held in the off state, so the transistor Q13 turns on after the charging of the capacitor C3 is completed and the transistor Q12 turns on.
11 will turn on. When the transistor Q11 is turned on, the bases of the transistors Q2, Q7 and Q9 are grounded through the diodes D8, D9 and D10, so that the terminal CT
Even if the ON signals are output from 1, CT3 and CT5, the respective transistors Q2, Q7 and Q9 are turned off. Therefore, at the time of abnormality, the magnet clutch 22 is disengaged and the actuator 21 is in the non-driving state regardless of the signal output from the CPU 7, so that the malfunction of the actuator 21 can be reliably prevented. Also, transistors Q7 and Q9 for driving the motor 23
Is also turned off, so transistors Q3 and Q6 and Q4 and Q5
Dead short current does not flow between and.

<Effects of the Invention> As described above, according to the present invention, two transistors on the power source side of the motor of the transistor bridge circuit are provided so that the power source of the transistor bridge circuit of the actuator drive circuit is not short-circuited at the time of abnormality. Since a reverse bias is supplied to the transistor due to an abnormal output of the watchdog timer circuit so as to make it non-conductive, the transistor is destroyed even when the control unit outputs a signal for putting the transistors of the drive circuit into a dead short state. Never. Therefore, the extremely simple circuit can prevent the transistors in the transistor bridge circuit from being in a dead short state even when the CPU as the control means runs out of control, and the damage can be minimized. Etc., the effect is extremely large.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of a constant speed traveling device according to the present invention. 1 ... Control unit 2 ... Stabilized power supply circuit 3 ... Input control circuit 4 ... Input / output control circuit 5 ... Actuator drive circuit 6 ... Motor current detection circuit 7 ... CPU, 8 ... Battery 9 ... Ignition switch 10 …… Fuse, 11 …… Main switch 12 …… Main lamp, 13 …… Vehicle speed sensor 14 …… Fuse, 15 …… Set switch 16 …… Resume switch 17 …… Fuse, 18 …… Brake switch 19 ...... Clutch switch 20 …… Brake lamp, 21 …… Actuator 22 …… Magnet clutch 22a …… Coil, 23 …… Motor 24 …… Limit switch 26 …… Watchdog timer circuit

Front Page Continuation (72) Inventor Masahiko Asakura 1-4-1 Chuo, Wako-shi, Saitama, Ltd., Honda R & D Co., Ltd. Inside the Leaf Electric Works (72) Inventor Mitsuru Matsui 1268-1, Hirosawa-cho, Kiryu City, Gunma Prefecture Inside the Mitsuha Electric Works Co., Ltd. (56) Reference JP-A-58-15730 (JP, A) JP-A-59- 96450 (JP, A) JP-A-55-102062 (JP, A) JP-B-48-21389 (JP, B1) JP-B-43-2010 (JP, B1)

Claims (1)

[Claims] 1. An accelerating device comprising control means for performing arithmetic control to generate a control signal so as to maintain the vehicle speed at a set vehicle speed, and a transistor bridge circuit for driving a motor actuator for performing a vehicle speed control operation based on the control signal. Drive means having a circuit and a deceleration circuit, abnormality detection means for detecting abnormality of the control means, and abnormality detection output by the abnormality detection means provided between the abnormality detection means and the transistor bridge circuit In response to this, the input of the control signal from the control means to the base of each transistor on the power supply side of the motor is prohibited for each of the acceleration circuit and the deceleration circuit of the transistor group forming the transistor bridge circuit. A vehicle characterized by having an abnormal transistor control means for making both of them non-conductive. The control circuit of Yojosoku traveling device.