JPH0529569B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a fail-safe circuit for a constant speed traveling device for an automobile.

BACKGROUND ART A typical prior art is shown in FIG.
An actuator 1 that drives a throttle valve of an internal combustion engine installed in an automobile includes a release valve 2.
By energizing and closing the control valve 3, by controlling the duty of the control valve 3, the opening degree of the throttle valve is controlled using the negative pressure of the intake manifold, thereby allowing the vehicle to run at a constant speed. configured so that it can be carried out. A signal that changes between high and low levels for duty control is applied to the transistor 5 from the output terminal P3 of the processing circuit 4 realized by a microcomputer, etc., so that the control valve 3 is connected to the line. An exciting current flows through the control valve 6 to control the duty of the control valve 3. Transistor 7 remains conductive unless line 6 remains at a high level for a predetermined period of time in detection circuit 13 or longer. When the vehicle is running at a constant speed, the processing circuit 4 applies a low level signal to the transistor 8 from the output terminal P1, so that the transistor 8 is conductive. Therefore, unless a brake operation is performed, the contact 10 of the brake switch 9 is conductive, and the release valve 2 remains energized and closed. When the brake is operated, the contact 11 of the brake switch 9 becomes conductive, and the brake lamp 12 lights up. At this time, the contact 10 is cut off, the release valve 2 opens, and the drive of the throttle valve by the actuator 1 is released. A signal indicating that the state in which current flows through the line 6 and the control valve 3 is energized by the detection circuit 13 has continued for a predetermined time or more is transmitted from the detection circuit 13 to the processing circuit 4.
is applied to input terminal P2 of.

Problems to be solved by the invention In this prior art, the brake switch 9
If the excitation current continues to be supplied to the release valve 2 despite the brake operation due to a failure in the control valve 3, when the transistor 8 is cut off by the processing circuit 4, or when the control valve 3 Even when the detection circuit 13 detects that the transistor 7 remains energized and shuts off the transistor 7,
The release valve 2 remains energized, and therefore the opening of the throttle valve increases to increase speed, and in particular, due to the malfunction of the processing circuit 4, the transistor 5 remains conductive. Alternatively, due to a failure of the transistor 5, the transistor 5 remains conductive, and if the control valve 3 continues to be energized, the speed increasing operation will continue. , the driver was surprised.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a fail-safe circuit for a constant-speed vehicle driving system with significantly improved safety.

Means for Solving the Problems In the present invention, an actuator is provided in association with the throttle valve, and the actuator increases the opening degree of the throttle valve using negative pressure by energizing the control valve. By demagnetizing the release valve, the throttle valve is deactivated, and by energizing the release valve and controlling the duty of the control valve, the throttle valve is driven for constant speed running. In the fail-safe circuit of the constant speed traveling device for an automobile, the first series circuit includes a release valve and a first switching element, the second series circuit includes a control valve and a second switching element, and the first series circuit. a third switching element connected in common and in series with the second series circuit;
A brake switch is connected in series with the switching element and detects and cuts off the brake operation, and a brake switch is connected in series with the first switching element while the second
a control means for duty-controlling the switching element to drive at a constant speed; a detection means for detecting that the control valve has been energized for a predetermined time; This is a fail-safe circuit for a constant speed driving device for an automobile, characterized in that it includes a cutoff means for cutting off a third switching element.

Function According to the present invention, the third switching element is connected commonly and in series to the first and second series circuits. This third switching element shuts off when the second switching element remains conductive for a predetermined time, that is, when the control valve remains energized and speed increasing operation is performed. do. Therefore, both the control valve and the release valve are shut off, and the opening degree of the throttle valve is prevented from increasing. This improves safety. Therefore the first or second series circuit,
Alternatively, even if the brake switch connected in series to the third switching element fails and remains in a conductive state, safety is ensured.

Further, according to the present invention, in order to detect that the control valve remains energized for a predetermined time and to shut off the third switching element, (a) the control valve is energized for a predetermined time; and (b) means for cutting off the first and third switching elements in response to the detection output from the detection means. Therefore, when the control valve is energized for more than a predetermined time as described above and the speed increasing operation continues and remains performed, that is, the duty of the control valve's duty control is maintained at 100%. When this state continues for more than the predetermined time, not only the third switching element but also the first switching element is shut off as described above. As a result, one end of each of the control valve and the release valve is shut off by the third switching element, and the other end of the release valve is shut off by the first switching element, further improving safety. .

Embodiment FIG. 1 is a block diagram of one embodiment of the present invention. The actuator 14 includes a release valve 15.
and a control valve 16 are provided.

FIG. 2 is a sectional view showing the structure related to the actuator 14. A throttle valve 19 is provided in an intake path 18 of an internal combustion engine 17 that drives an automobile. This throttle valve 19 is driven by an actuator 14 for automatic control via a link mechanism 20, and is operated by an accelerator pedal 21.

The release valve 15 is connected in series with a transistor 23, which is a first switching element, and a contact 25 of a brake switch 24, thereby forming a first series circuit 26. A transistor 27, which is a second switching element, is connected in series to the control valve 16.
In this way, the second series circuit 28 is constructed. A first series circuit 26 including a release valve 15 and a control valve 16
The second series circuit 28 including a common line 29
A transistor 30, which is a third switching element, is connected in series to this line 29. A resistor RG is connected in parallel to the transistor 30. For example, the resistance value of this resistor RG is 3.3KΩ
On the other hand, the DC resistance of the solenoids 46 and 55 of the release valve 15 and the control valve 16 (see FIG. 2, which will be described later) is, for example, 68Ω.

The contact 25 of the brake switch 24 is disconnected when the brake pedal is depressed, and is conductive when the brake pedal is not operated.
The brake switch 24 has another contact 32, which is turned on when the brake pedal is depressed and is closed when the brake pedal is not operated. This contact point 32 has a stop lamp 33.
are connected in series.

A capacitor 36 is connected to the anode of the diode 35 to which the cathode of the diode 35 is connected to the line 34 connecting the transistor 27 and the control valve 16, and this capacitor 36 is grounded. A transistor 3 is connected to a connection point 37 between the diode 35 and the capacitor 36 via a resistor 38.
9 bases are connected. A resistor 40 is connected between the base and emitter of the transistor 39. The collector of the transistor 39 is connected to the processing circuit 4
1, and is connected to the input terminal P6 of resistor 4.
2 to the base of transistor 70. The base of this transistor 70 is a resistor 71
grounded via. A connection point 72 between the base of the transistor 70 and the resistors 42 and 71 is connected to the collector of a transistor 73 that constitutes an open collector inverter. The emitter of this transistor 73 is grounded. transistor 73
The base of is connected to the output terminal P5 of the processing circuit 41 and grounded via a resistor 74. A signal from output terminal P4 of processing circuit 41 is connected to the base of transistor 27 via buffer 75. The collector of the transistor 70 is connected to the resistor 7.
5 to the base of the transistor 23. The emitter of transistor 70 is connected to the base of transistor 30. Processing circuits 41 and their associated components are generally designated by the reference numeral 76 as electrical circuits.

A signal from the brake detection element 43 is given to the processing circuit 41 . This brake detection element 43
generates a signal when the brake pedal is depressed to perform a braking action. Processing circuit 41
An alarm lamp 44 is connected to.

Before power-up, the charge on capacitor 36 is discharged from diode 35 through line 34, control valve 16, line 29 and resistor RG, so that node 37 is at a low level.

When the power is turned on and the vehicle is not running at a constant speed, the output terminals P4 and P of the processing circuit 41 are
5 is a high level. This causes transistor 27 to turn off and transistor 73 to conduct.
Due to the conduction of the transistor 73, the transistor 7
0 is cut off, and accordingly transistors 23,3
0 blocks it. In this way, the release valves 15 and 16 are demagnetized.

During the operation of the automobile traveling at a constant speed, the processing circuit 41
keeps the low level signal derived from the output terminal P5, and controls the duty of the output terminal P4. By setting the output terminal P5 to a low level, the transistor 73 is cut off. After turning on the power,
The voltage at node 37 is low, so transistor 39 is conducting. Therefore, transistor 70 becomes conductive, and in response, transistors 23 and 23 become conductive.
30 is conductive. Therefore, the release valve 15 is
When the contact 25 of the brake switch 24 is conductive, it is energized and the valve is closed.
The transistor 27 is the output terminal P4 of the processing circuit 41.
ON and OFF operations are performed according to the duty control signal from the control valve 16, and therefore the control valve 16 is duty-controlled. In this state, the opening degree of the throttle valve 14 is controlled, and the vehicle runs at a constant speed.

Transistor 23 or brake switch 24
When the contact point 25 is closed, the release valve solenoid 46 included in the actuator 14 is demagnetized. Therefore, the release valve 15
The valve body 47 is displaced away from the valve seat 50 around the fulcrum 48 by the spring force of the spring 49. Therefore, the diaphragm chamber 51 of the actuator 14 is open to the atmosphere via the valve hole 52, and the diaphragm 53 remains biased by the spring 54 accordingly.

The solenoid 55 for the control valve 16 is controlled by changing the duty of the excitation current from the transistor 27 described above. When the transistor 27 is cut off and the control valve solenoid 55 is demagnetized, the valve body 56 of the control valve 16
is separated from the valve seat 58 by the spring force of the spring 57, so that the diaphragm chamber 51 is open to the atmosphere via the valve hole 59. This control valve 1
6 is angularly displaceable around a fulcrum 60. When the valve body 56 is separated from the valve seat 58, another
The two valve bodies 61 are seated on the valve seats 62, so that the valve holes 63 are isolated from the diaphragm chamber 51.

The valve hole 63 communicates with the intake path 18 downstream of the throttle valve 19 (that is, closer to the intake valve of the internal combustion engine) and is under negative pressure.

When the transistor 27 becomes conductive, the control valve solenoid 55 is energized. Therefore, the control valve 16
2, the valve body 56 is seated on the valve seat 58, the valve body 61 is separated from the valve seat 62, and the diaphragm chamber 51 becomes under negative pressure. Due to the negative pressure in the diaphragm chamber 51, the diaphragm 53 is displaced to the right in FIG. The opening degree is controlled to be large.

Even if the car is not running at a constant speed, that is, even if the automatic speed control is cancelled, if the actual vehicle speed is higher than a predetermined speed, for example, 40 km/h, the above-mentioned It is possible to return to the selected vehicle speed and start driving.

When the output terminal P4 remains at a low level and the transistor 27 remains conductive due to an abnormal operation of the processing circuit 41 while the automobile is running at a constant speed, or when the transistor 27 remains conductive, or due to a failure of the transistor 27, that transistor When 27 remains conductive, line 34 goes high and control valve 16 remains energized. At this time, the diode 35 is cut off, and the capacitor 36 is connected to the resistor 3.
8,40. When the output voltage at the connection point 37 of the capacitor 36 exceeds a predetermined value, the transistor 39 is turned off for the first time. As a result, the terminal P6 of the processing circuit 41 becomes low level, and the processing circuit 41 detects this and turns on the alarm lamp 44. Processing circuit 41
may be configured to derive high level signals to the output terminals P4 and P5 when the input terminal P6 becomes low level. Further, when the transistor 39 is cut off, the transistor 70 is cut off, and accordingly, the transistors 23 and 30 are cut off. Therefore, both the release valve 15 and the solenoid valve 16 are demagnetized, and the diaphragm chamber 51 becomes at atmospheric pressure. Therefore, the diaphragm chamber 53
4, the throttle valve 19 is displaced to the left as shown by the imaginary line in FIG. 2, and the actuator 14 of the throttle valve 19 releases its drive. In this way, speed increasing operation is prevented from occurring and it is safe. Further, in the case where the excitation current continues to be supplied to the release valve 15 due to a failure of the brake switch 24, if the control valve 16 remains energized, the transistor 30 is cut off as described above. It turns out.

When the transistors 23 and 27 are both destroyed and short-circuited at the same time, the diode 35 is cut off as described above, and the capacitor 36 is charged via the resistors 38 and 40, so that the potential at the connection point 37 increases. , transistor 39 is cut off. This shuts off transistors 70, 23, and 30, making it safe.

In the brake switch 24, the release valve 1
It is assumed that voltage +B is applied to at least one of control valve 5 and control valve 16 and a failure occurs. At this time, since the resistance value of the resistor RG is high, the voltage on the line 34 becomes a relatively high voltage value close to the voltage value +B. This causes diode 35 to shut off, so that capacitor 36 is connected to resistor 3.
8, 40, the voltage at the node 37 becomes high and the transistor 39 is cut off, thereby causing the transistors 70, 23, 30 to be charged as described above.
is blocked and safety is maintained.

Due to the occurrence of some kind of failure, the capacitor 36
is charged and the voltage at the connection point 37 increases, and even if the transistors 39, 70, 23, and 30 are cut off, the charge in the capacitor 36 is transferred to the diode 35, the line 34, and the control valve as time passes. 16, is discharged through line 29 and resistor RG. Therefore, the voltage of the capacitor 36 decreases over time, and the transistor 39 becomes conductive again. Therefore, in the event of an abnormality, the transistors 23 and 30 are once cut off, the release valve 15 and the control valve 16 are demagnetized, and a safe state is established. After the cause of the failure is removed, constant speed driving is resumed. can be done. Therefore, there is no need to cut off the power to the fail-safe device in order to discharge the capacitor 36, and operability is improved.

The processing circuit 41 can determine that the constant speed running operation is interrupted when the terminal P6 becomes high level. It is also possible to determine and display the cause of the interruption of the constant speed driving operation by the operation of the processing circuit 41.

The contact point of the brake switch 24 is the release valve 1.
Instead of being connected in series with the control valve 5, it may be connected in series with the control valve 16.

Effects As described above, according to the present invention, safety is improved. In particular, in the present invention, a third switching element is provided that can commonly shut off the release valve and the control valve, and when the control valve is continuously energized, not only the first switching element but also the third switching element is shut off. Since it was configured as follows, (1) first,
If a processing circuit such as a microcomputer that controls the second switching element fails or malfunctions in the processing circuit, and the first and second switching elements are no longer able to shut off, ( 2) Even if the first and second switching elements have a short failure, or (3) if current continues to flow to the release valve through the brake switch, the current flowing to the release valve and control valve will be shut off reliably. This increases safety as described above.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG.
The figure is a sectional view showing the structure related to the actuator 14, and FIG. 3 is a block diagram of the prior art. 14...actuator, 15...release valve, 1
6... Control valve, 17... Internal combustion engine, 19... Throttle valve, 21... Accelerator pedal, 23, 27, 30,
39, 70, 73...Transistor, 24...Brake switch, 33...Stop lamp, 41...Processing circuit, 43...Brake detection element.

Claims (1)

[Claims] 1. An actuator is provided in association with the throttle valve, and the actuator is configured to increase the opening degree of the throttle valve using negative pressure by energizing the control valve, The throttle valve is deactivated by demagnetizing the release valve, and the throttle valve is driven for constant speed driving by energizing the release valve and controlling the duty of the control valve. The fail-safe circuit of the speed traveling device includes: a first series circuit including a release valve and a first switching element; a second series circuit including a control valve and a second switching element; a first series circuit and a second series circuit; a third switching element commonly connected in series to the first series circuit, the second series circuit, or the third switching element;
A brake switch is connected in series with the switching element and detects and cuts off the brake operation, and a brake switch is connected in series with the first switching element while the second
a control means for duty-controlling the switching element to drive at a constant speed; a detection means for detecting that the control valve has been energized for a predetermined time; 1. A fail-safe circuit for a constant speed driving device for an automobile, comprising a cutoff means for cutting off a third switching element.