JPH0755630B2 - Fail-safe device for constant-speed traveling device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fail-safe device for a constant speed traveling device, which controls ON / OFF of power supply to an actuator for constant speed traveling control.

[Conventional technology]

A conventional constant speed traveling device for a vehicle is shown in FIG. In the figure, 1 is a speed signal generating means for generating a signal having a frequency corresponding to the traveling speed of the vehicle, 2 is a command signal input means for generating a command signal for instructing to set a constant speed traveling by an external operation, 3 Is a cancel signal input means for giving an instruction to cancel the constant speed traveling by an external operation. Reference numeral 4 denotes a D flip-flop (hereinafter referred to as D.
It is called FF. ), The D input terminal (D terminal) is pulled up by the power supply through the pull-up resistor 5, the clock input terminal (CL terminal) is connected to the command signal input means 2, and the set terminal (S terminal) is grounded. The reset terminal (R terminal) is connected to the cancel signal input means 3. The normal output terminal (Q terminal) is connected to the base of the transistor 6 whose emitter is grounded. The base of the transistor 8 whose emitter is connected to the DC power supply 7 is connected to the collector of the transistor 6 via the resistor 9. Numerals 10 and 11 are first and second solenoid valves constituting a drive unit of a well-known negative pressure type actuator that drives a throttle valve (not shown) installed in an intake pipe of an engine for constant speed traveling control. When the solenoid valve 10 is turned on, a negative pressure is introduced from an engine negative pressure source (not shown), and when the second solenoid valve 11 is turned on, atmospheric pressure is introduced, and the rest is cut. The first and second solenoid valves 10 and 11 are connected to a diaphragm chamber, and the diaphragm pressed from the diaphragm chamber side by a spring and the throttle valve are connected by a connecting bar, which has a known structure. There is. 10a and 11a are coils of the first and second solenoid valves 10 and 11, one end of each of which is commonly connected to the collector of the transistor 8 and the other ends of which are connected to the collectors of both transistors 12 and 13 whose emitters are grounded. Each is connected. Reference numeral 14 is a microcomputer for controlling constant speed running, which is composed of an input circuit, a CPU, a RAM, a ROM, and an output circuit. The input circuit is connected to the elements 1 to 3, and the output circuit is both transistors. It is connected to each of the 12 and 13 bases.

Next, the operation will be described. In the normal state, the constant speed running is not set, and it is in the cancel state, and D / F / F4
Has been reset. Therefore, since the Q terminal is at "L" level, both transistors 6 and 8 are OFF, and the first and second solenoid valve coils 10a and 11a and the power source 7 are in non-conduction. After that, when a command signal is generated from the command signal input means 2 by the driver's operation, the D / F / F4 inputting this signal to the CL terminal has the D terminal pulled up to "H".
Set because it is a level. Therefore, the Q terminal becomes "H" level, the transistor 6 is turned on, and the transistor 8 is pulled in and the transistor 8 is turned on. When the transistor 8 is turned on, the first and second solenoid valve coils 10a and 11a and the power supply 7 are brought into conduction. On the other hand, the microcomputer 14 enters the constant speed traveling control state when the command signal is input from the command signal input means 2, and both transistors 12 and 13 are set based on the signal input from the speed signal generation means 1.
ON / OFF control. When the transistor 12 is turned on, the first solenoid valve coil 10a is energized, and when the transistor 13 is turned on, the second solenoid valve coil 11a is energized, and the rest is non-energized. The opening of a throttle valve (not shown) is adjusted according to the ON / OFF state of the first and second solenoid valves 10 and 11 to perform constant speed traveling control. The relationship between these states is shown in the table below.

Thereafter, the cancel signal input means 3 is operated by the driver.
When a cancellation signal of "H" level is generated from the S terminal and it is input to the R terminal of DF / F4 because the S terminal is grounded and is at the "L" level, DF / F4 is reset. . As a result, the Q terminal becomes "L" level, and the above-mentioned normal state is established so that the first and second solenoid valve coils 10a and 11a and the power supply 7 are brought out of conduction. Further, the microcomputer 14 that has input the cancel signal cancels the constant speed traveling set, stops the constant speed traveling control, and waits for the next command signal input.

[Means for Solving the Problems]

Since the conventional vehicle constant-speed traveling device is configured as described above, when the microcomputer 14 runs away or fails due to external noise, both transistors 12, 13
There is a risk of locking the output signal that turns ON,
If a cancel signal is generated from the cancel signal input means 3, D / F / F4 are reset and the transistor 8 is turned off.
However, when a command signal is generated from the command signal input means 2, D / F / F4 is set and the first and second solenoid valves 10 and 11 remain in the ON state, which may cause a problem in traveling safety. There was a problem that became.

Further, even if the collector-emitter of both the transistors 12 and 13 is in a conductive state due to a failure, there is a problem in that it becomes a safety problem similarly to the above.

The present invention has been made to solve the above problems, and when there is a failure of the control device for constant speed running or a runaway or a failure of the actuator driving switching element, the power supply to the actuator is turned off. An object of the present invention is to provide a fail-safe device for a constant speed traveling device that can be controlled as it is.

[Means for Solving the Problems]

The fail-safe device for a constant-speed traveling device according to the present invention detects the conduction state of the switching element that controls the actuator by the detection means, and when this detection signal is received during cancellation, the power supply control means receives the command signal. The power supply to the actuator is turned off.

[Work]

The fail-safe device for a constant speed traveling device according to the present invention,
For safety reasons, the power supply to the actuator is supplied by the power supply control means even if the command signal is input when the detection means detects the conduction of the switching element due to a short circuit due to a failure of the switching element or a failure of the control device.
Turn it off.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, the same reference numerals 1 to 4 and 6 to 14 as those in FIG. 2 indicate the same or corresponding portions as those of the conventional apparatus, and the description thereof will be omitted. 15 is
In the AND gate, each input terminal is connected to the connection between the first solenoid valve coil 10a and the collector of the transistor 12 and the connection between the second solenoid valve coil 11a and the collector of the transistor 13, and the output terminal is D -Connected to the D terminal of F / F4. Reference numeral 16 is a pull-up resistor having a high resistance value connected between the emitter and collector of the transistor 8, and the first or second solenoid valves 10 and 11 are not turned on by a current passing through the pull-up resistor. Reference numeral 17 is a power supply control means, which is composed of elements 4, 6, 8, and 9.

Next, the operation will be described. When the constant-speed traveling set is canceled and the vehicle is in the non-constant-speed traveling state, DF, F4 are in the reset state, and the transistor 8 is turned off. At this time, the microcomputer 14 turns off the transistors 12 and 13. Then, both input terminals of the AND gate 15 are connected from the DC power source 7 to the resistor 16 and each solenoid valve coil 10.
AND gate 15 because it is pulled up via a, 11a
An "H" level signal is input to both input terminals.
Therefore, the "H" level signal output from the AND gate 15 is input to the D terminal of D, F, F4 and keeps the D terminal in the "H" level state. Therefore, a command signal is generated from the command signal input means 2 by the driver's operation and D
・ When it is input to the CL terminal of F ・ F4, D ・ F ・ F4 is set and the transistor 8 is turned on. After that, when the cancel signal input means 3 is operated, a cancel signal is generated, and when the cancel signal is input to the R terminal of the D / F / F4 whose S terminal is grounded, the D / F / F4 is reset.

If D / F / F4 is reset, if the microcomputer 14 runs out of control or fails, or the transistor 12,1
When at least one of the transistors 3 fails and the collector-emitter of the transistor 12 or 13 becomes conductive, the "L" level signal is input to the AND gate 15. Therefore, AND
The "L" level output of the gate 15 is given to the D terminals of D, F and F4. Then, at this time, even if a command signal is generated from the command signal input means 2 and is input to the CL terminal of DF / F4, DF / F4 maintains the reset state. As a result, the transistor 8 is OFF, and the first and second solenoid valve coils 10a and 11a are not energized to exceed the threshold current, so that safety is maintained.

Since the other operations of the constant speed traveling control have been described in the conventional example, the description thereof will be omitted.

In the above embodiment, the AND gate was used, but instead of O
An R gate may be used. In this case both transistors 1
Only when both the collector and emitter of 2,13 are conductive, the setting of constant speed running is prohibited.

Further, although the negative pressure type actuator has been described in the above embodiment, the present invention can be applied to a well-known electric motor type actuator in which a DC motor and an electromagnetic clutch are combined, and the voltage on one side of the coil of the electromagnetic clutch is applied to the D voltage via an amplifier. The configuration may be such that the signal is input to the D terminal of F and F, and the same effect as that of the above embodiment is obtained.

〔The invention's effect〕

As described above, according to the present invention, when the actuator control switching element is turned on during the cancellation, the power supply to the actuator is turned off even if the command signal is generated. There is an effect that a highly safe thing can be obtained without runaway.

[Brief description of drawings]

FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional apparatus. In the figure, 2 ... Command signal input means, 3 ... Cancel signal input means, 7 ... Power supply, 10, 11 ... Solenoid valve, 10a, 11a
…… Solenoid valve coil, 12,13 …… Transistor, 15 …… AND
Gate, 16 ... Resistor, 17 ... Power control means. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A command signal input means for generating a command signal for instructing a constant speed traveling set by an external operation, and a cancel signal for generating a cancel signal for instructing a cancellation of the constant speed traveling set by an external operation. Turns on / off the power supply to the signal input means and the constant speed traveling control actuator that drives the throttle valve of the engine in response to the input signals of the command signal and the cancel signal.
Power control means for controlling F, a switching element for controlling ON / OFF of the actuator supplied with the power, and detection means for detecting a conduction state of the switching element, the power control means being the detection means at the time of cancellation. A fail-safe device for a constant-speed traveling device, characterized in that the power supply to the actuator is kept off even if the command signal is input when a detection signal is received from the device.