JPS63258229A - Control circuit of constant speed travel device for vehicle - Google Patents

Abstract

PURPOSE:To prevent a dead-short condition among transistors in a drive circuit by making transistors non-alive in an acceleration drive circuit for an actuator, depending upon abnormal output from a watch dog timer circuit, when a control means becomes uncontrollable. CONSTITUTION:At the time of constant speed travel, output signals from output terminals CT3 to CT6 are sometimes not determined when CPU 7 is abnormal. And when an ON-signal is outputted concurrently from the terminals CT3 and CT6, transistors Q3 and Q6 concurrently become alive, thereby causing a dead- short state. In this abnormal state, a transistor Q11 turns ON and a magnet clutch 22 turns OFF. As a result, not only an actuator turns into a non-drive state, but also transistors Q4 and Q7 for an acceleration drive circuit turn OFF, thereby preventing a flow of dead-short currents between the transistors Q3 and Q6, and Q4 and Q5.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a control circuit for a constant speed traveling device for a vehicle.

<Prior Art> In general, various constant speed traveling devices for maintaining the speed of a vehicle at a predetermined set speed are known.

According to such a constant speed traveling device, by operating the set switch when the accelerator pedal is operated and the desired vehicle speed has been reached, an actuator that operates in the same way as the accelerator pedal is activated, and from then on, the foot is removed from the accelerator pedal. The vehicle speed can be maintained at the set speed even if the button is released.

Some actuators for such constant-speed traveling devices use motor-type actuators that have a relatively compact configuration and can be controlled with high precision. In a control circuit that performs acceleration and deceleration using this motor-type actuator, it is conceivable to configure the motor drive circuit using a transistor bridge circuit.

In such a constant speed traveling device, as a fail-safe function, an A-edge dog 91 circuit is provided as an abnormality detection circuit, and when the CPU as a control means goes out of control, the watchdog timer circuit When the abnormal output occurs, the clutch drive circuit is turned off and the magnetic clutch installed on the output shaft of the actuator is disengaged, preventing the actuator from operating. Therefore, abnormalities in the device can be avoided.

By the way, in the motor drive circuit of an actuator, when the CPU goes out of control, all combinations of logic circuits can be output as the CPU output, so a so-called dead short occurs between the transistors and the transistors are destroyed. Then there is a problem.

Therefore, in a motor forward/reverse drive circuit using a transistor bridge circuit, for example, as disclosed in Japanese Patent Laid-Open No. 57-119682, it is necessary to simultaneously It has been considered to provide a protection circuit that renders the other non-conductive to prevent the destruction of the transistor due to a so-called dead short circuit.

However, in the transistor protection circuit described above, since the motor drive current flows through the protection circuit, the protection circuit must be constructed using large elements such as power transistors, and the component cost is relatively high. There is a risk that problems such as

In addition, in the event of an abnormality such as a runaway CPU, there is a possibility that conduction or non-conduction may occur between the transistors of the transistor bridge circuit, such as turning on the actuator acceleration drive circuit, and in that case, the actuator motor will accelerate. It will rotate to the side. Even in this case, since the clutch drive circuit is turned off as described above, malfunction of the actuator can be avoided, but there is a problem in that it is undesirable for the motor to rotate in the acceleration direction.

<Problems to be Solved by the Invention> In view of these problems in the prior art, the main purpose of the present invention is to prevent the transistors of the actuator drive circuit from being destroyed even when the control means goes out of control, and to prevent the actuator from being damaged. It is an object of the present invention to provide a control circuit for a constant speed traveling device for a vehicle that can prevent the vehicle from being driven to the acceleration side.

Means for Solving the Problems According to the present invention, the present invention provides a control means for performing calculation control and generating a control signal to maintain the vehicle speed at a set vehicle speed, and a control means for generating a control signal based on the control signal. A control circuit for a constant speed traveling device for a vehicle having an acceleration and deceleration drive circuit for driving an actuator that performs Provided is a control circuit for a constant speed traveling device for a vehicle, characterized in that the drive transistor of the acceleration drive circuit is made non-conductive and the drive transistor of the deceleration drive circuit is made conductive due to an abnormal output. This is achieved by

<Function> As described above, when the control means goes out of control, the transistors in the drive circuit for accelerating the actuator become non-conductive due to the abnormal output of the watchdog timer circuit, resulting in a dead short between the transistors in the drive circuit. can be prevented from occurring.

Further, since the deceleration drive circuit is turned on, the actuator can be operated to the deceleration side.

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

FIG. 1 is a circuit diagram showing a general configuration of a constant speed traveling device for a vehicle based on the present invention. Control of this constant speed traveling device is performed via a control unit 1, and the control unit 1 includes a stabilizing power supply circuit 2, an input control circuit 3,
, an input/output control circuit 4, an actuator drive circuit 5, a motor current detection circuit 6, and a CPU that is connected to these circuits and performs arithmetic processing.

The terminal T1 of the control unit 1 is supplied with voltage from the battery 8 as a power source.

The power is supplied via the intake switch 9, the fuse 10, and the main switch 11. Also, main switch 1
The main lamp 12 has one end grounded and the other end connected between the main lamp 12 and the terminal T1.

Inside the control unit 1, a power supply circuit 2 is connected to the terminal T1, and a voltage stabilized within the power supply circuit 2 is supplied to the CPU 7.

In addition, for power supply of other circuits of the control unit 1, a power supply terminal vb is provided between the terminal T1 and the power supply circuit 2, and a stabilized power supply terminal VC is provided in the power supply circuit 2, respectively.

The input control circuit 3 receives a signal from the vehicle speed sensor 13 through a terminal T.
Signals from the set switch 15 and the resume switch 16, which are input through the terminal T3 and connected to the battery 8 through 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.

Further, signals from contacts S1 and S2 of a brake switch 18 attached to a brake pedal (not shown) are inputted to the control unit 1 as control inputs through terminals T5 and T6.

The contact S1 is a normally closed contact and is connected between the terminal T5 and a fuse 17 that is branched from between the battery 8 and the ignition switch 9. The contact S2 is a normally closed contact and is connected to the main switch. 11 and terminal T1, and between terminal T6. Further, as another control input, a signal from a clutch switch 19 attached to a clutch pedal (not shown) is input via terminal T7. Note that the brake lamp 20 is connected to the terminal T5.

Terminals T8 to T10 of the control unit are connected to the motor actuator 21, terminal T8 is connected to the coil 22a of the magnetic clutch 22 built in the actuator 21, and terminals T9 and T10 are connected to the motor 21.
3 are connected to each other. This actuator 21
By rotating the motor 23 in the forward and reverse directions, the accelerator pedal, also not shown, is driven via a linkage, not shown, which is integrally operated via the magnetic clutch 22. Note that 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.

Further, the terminal T9 is an output terminal for decelerating the vehicle.

Furthermore, the control unit 1 is grounded via the terminal T11.

In the control unit 1, 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 is transmitted from the terminal T5, and the contact S2 signal is similarly transmitted from the terminal T6.
Each signal is input to the CPU 7 via the input/output control circuit 4.

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. Further, a constant voltage diode ZD is connected between the emitter and collector of the transistor Q1. A resistor R1 is connected between the emitter and base of the transistor Q1, and the base of the transistor Q1 is connected to the collector of the transistor Q2 whose emitter is grounded via a resistor R2 and a diode D1.

Note that the diode D1 is connected in such a direction that current flows from the base of the transistor Q1 to the collector of the transistor Q2. Further, the collector of the transistor Q1 is connected to the CPLJ7 via the input/output control circuit 4 for the human power signal of the magnetic clutch 22.

The base of the transistor Q2 is grounded via a resistor R3, and is also connected to a terminal CT of the CPU7 via a resistor R4.
It is also connected to I. In response to the output signal from the terminal CT1, transistors Q2 and 01 are turned on, and the coil 22a of the magnetic clutch 22 is turned on or off.

The actuator drive circuit 5 includes a known transistor bridge circuit in order to rotate the motor 23 in the forward and reverse directions based on the control output signal of the CPU 7. That is, as clearly shown in the figure, the collector of the transistor Q3 constituting the acceleration drive circuit 25 is connected to the collector of the transistor Q4 via the terminal T10, the limit switch 24, the motor 23, and the terminal T9. The current during acceleration flows in this order, and the collector of the transistor Q5 constituting the deceleration drive circuit 26 is connected to the transistor Q via the terminal T9, the motor 23, the limit switch 24, and the terminal T10.
6, and current during deceleration flows in this order.

As a power source for this 1-plane star bridge circuit, a voltage is supplied from the terminal T6 to the emitter of the transistor Q3 via the diode D2, and a voltage is supplied from the power supply terminal Vb to the emitter of the transistor Q5 via the diode D3. Supplied. Also, transistors Q4 and Q6
The emitters of each are grounded via a motor current detection circuit 6. This motor current detection circuit 6 is CPtJ
It is also connected to the terminal CT2 of No.7.

As described above, since the power supply voltage of the acceleration drive circuit 25 is supplied from the terminal T6, when the constant speed traveling is canceled by brake operation, the voltage to the acceleration drive circuit 25 is supplied by the brake switch 18. It will definitely be blocked.

Transistors Q3 and Q5 have diodes D4 and D6.
are connected to the transistors Q4 and Q6 with their cathodes facing the emitters and their anodes facing the collectors, respectively, and diodes D5 and D7 are connected to the transistors Q4 and Q6, respectively, with their cathodes facing the collectors and their anodes facing the emitters. Resistors R5 to R8 are connected between the emitter and base of each transistor 03 to Q6, respectively, and the collectors of transistors Q7 to Q10 are connected to the base of each transistor 903 to Q6 via resistors R9 to R12, respectively. has been done. The emitters of transistors Q7 and Q9 are grounded, and their bases are also grounded via resistors R13 and R15. Also,
The emitters of the transistors Q8 and QIO are connected to the stabilized power supply terminal VC, and their bases are also connected to the stabilized power supply terminal VC via resistors R14 and R16. Furthermore, the bases of the transistors 07-Q10 are connected to signal output terminals CT3-CT6 of the CPU 7 via resistors R17-R20, respectively.

By the way, the base of the transistor Q2 for driving the magnet J to clutch 22 is connected to the collector of the transistor Q11, whose emitter is grounded, of the watchdog timer circuit 27 as an abnormality detection circuit, via a diode D8. .

Therefore, by turning on transistor Q11, the base of transistor Q2 is grounded via diode D8.

Next, the configuration of the watchdog timer circuit 27 will be shown below. Normally, for example, 4H is output from terminal CT7 of CPU7.
2 pulse waves are output, but in the event of an abnormality, the pulse waves are no longer output and a DC level output of Ov or 5V is output, or for example 400 k l-(Z of A high frequency pulse is output.This terminal CT7 is connected to the bases of transistors Q12 to 1 whose emitters are grounded via a capacitor C1 and a resistor R2'1.The bases of transistors Q12 and C2 are connected to each other. It is grounded via the resistor R22 in parallel. Also, the transistor Q12
The collector of is connected to the base of transistor Q13. The collector of the transistor Q13 is connected to the stabilized power supply terminal Vc, and also connected to the base via a resistor R23, and the base is grounded via a capacitor C3. The emitter of the transistor Q13 is connected to the base of the transistor Q11 described above.

Watchdog timer circuit 27 configured in this way
, capacitor C1, resistor R21, capacitor +
JC2 and resistor R22 constitute a so-called band-pass filter, which passes the 4H2 pulse wave output from terminal CT7 during normal times, but is designed to block DC level or high-frequency pulses output during abnormal conditions. There is. Therefore, since the transistor Q12 repeats on and off normally, by making the charging time constant of the capacitor C3 relatively large, the capacitor C3 will not be fully charged and the transistor Q13 will not be turned on.
- Transistor Qll is kept off. In the event of an abnormality, transistor Q12 is held in the off state, so
After capacitor C3 is fully charged, transistor Q13 is turned on, and transistor Q11 is turned on.

By the way, the base of the transistor Q7 of the acceleration drive circuit 25 and the transistor Q1 of the watchdog timer circuit 27
A diode D9 is connected between the collector of the transistor Q7 and the collector of the transistor Q11 in such a direction that current flows from the base of the transistor Q7 to the collector of the transistor Q11. A diode D10 is connected in the same direction between the base of the transistor Q4 and the collectors of the transistors 1 to Q11.

Further, the base of the transistor Q5 of the deceleration drive circuit 26 is connected to the collector of a 1-transistor Q14 whose emitter is connected to the base of the transistor Q6 via a resistor R24. A transistor Q1 is connected to the power supply terminal Vb.
The emitter of transistor Q1 is connected to
The collector of transistor Q14 and the base of transistor Q14 are connected through a resistor R26. Furthermore, transistor Q
A resistor R27 is connected to the base of the transistor Q15, and a diode D11 is connected between the resistor R27 and the collector of the transistor Q11 in such a direction that current flows toward the collector of the transistor Q11.

In the actuator drive circuit 5 configured in this manner, as described above, in the event of an abnormality, 1 - transistor Q
11 is turned on, and the bases of transistors Q2, Q4, and Q7 are grounded through diodes D9 and D10, so that the terminals CT'l, CT3, and CT4 of CPU7 are grounded.
Irrespective of the output state of , each of the transistors Q2, Q4, and Q7 becomes non-conductive. In addition, the transistor Q11
When turned on, transistors Q1 to Q15 are also turned on and Q14 is turned on, so transistors Q5 and Q are turned on regardless of the output states of terminals CT5 and CT6 of CPU7.
6 becomes conductive. Therefore, when CPtJ7 is abnormal, the magnetic clutch 22 drive transistor Q2 is turned off, the acceleration drive circuit 25 is turned off, and the deceleration drive circuit 26 is turned on.

Next, the operation of the constant speed traveling device configured in this manner will be explained.

By turning on the main switch 11 with the ignition switch 9 closed, 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 the condition is satisfied that, for example, the brake switch 18 and clutch switch 19 are not operated, the CPU 7 stores the vehicle speed at that time as the set vehicle speed based on a signal from the vehicle speed sensor 13. .

Next, when driving the actuator 21 according to the difference between the set vehicle speed and the actual vehicle speed, the CPU 7 outputs a signal to turn on the magnetic clutch 22, and the coil 22
A is energized and the magnetic clutch 22 is brought into a connected state. When accelerating, a signal for turning on transistors Q7 and Q8 is output from terminals CT3 and CT4, and a signal for turning off transistors Q9 and Q10 is output from terminals CT5 and CT6. Furthermore, when decelerating, signals opposite to those described above are output from each terminal.

In this way, the motor 25 is rotated in forward and reverse directions via the actuator drive circuit 5, and controlled so that the actual vehicle speed and the set vehicle speed approximately match.

In addition, when you want to increase the vehicle speed to a desired speed, press and release the resume switch 16 to set the new vehicle speed to the CPU.
This is to be stored in 7.

Further, when the CPU 7 detects that the brake switch 18 or the clutch switch 19 is being operated, for example, the constant speed running state is canceled. At this time,
In order to drive the actuator 21 in the direction of deceleration, C
A deceleration signal is output from the PU 7 to the actuator drive circuit 5, and the vehicle is decelerated.

In the constant speed traveling device configured in this way, C
When PU7 is abnormal, the output signals from output terminals CT3 to CT6 may become unstable. For example, the output signals from terminals CT3 and C
If an on signal is output from transistor T6 at the same time, transistors Q3 and 06 become conductive at the same time, resulting in a so-called dead short condition, which may cause damage to transistors Q3 and Q6.

However, in the event of an abnormality, the transistor Q11 is turned on as described above, the magnetic clutch 22 is turned off, and the 7 actuators 21 are not driven, and the transistors Q7 and Q of the acceleration drive circuit 25 are
Since the transistors Q4 are also in the off state, no dead short current flows between the transistors Q3 and Q6 and between the transistors Q4 and Q5.

Further, since the deceleration drive circuit 26 is turned on and the motor 23 rotates toward the deceleration side, the actuator can be prevented from being driven toward the acceleration side.

In this embodiment, the actuator drive circuit 5 having a transistor bridge circuit is shown, but any transistor drive circuit may be used, and the present invention is not limited to a transistor bridge circuit.

<Effects of the Invention> As described above, according to the present invention, even if a signal that causes the transistors of the actuator drive circuit to dead-short each other during an abnormality is output, the transistors will not be destroyed, so the drive circuit will not be damaged. Not only can damage be minimized, but the effects are extremely large, such as driving the actuator to the deceleration side.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the configuration of a constant speed traveling device based on 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...CPtJ 8...Battery 9・
...Ignition switch 10...Fuse 11...Main switch 1
2... 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 2
2...Magnetic clutch 22a...Coil 23...Motor 24...
Limit switch

Claims (1)

[Scope of Claims] A control means that performs arithmetic control and generates a control signal to maintain the vehicle speed at a set vehicle speed, and an acceleration and deceleration drive circuit that drives an actuator that performs a vehicle speed control operation based on the control signal. A control circuit for a constant speed traveling device for a vehicle, wherein the control circuit has an abnormality detection circuit, and disables a driving transistor of the acceleration driving circuit by an abnormal output of the abnormality detection circuit. A control circuit for a constant speed traveling device for a vehicle, characterized in that a control circuit for a constant speed traveling device for a vehicle is brought into a conductive state and a driving transistor of the deceleration drive circuit is brought into a conductive state.