JPS6248630B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention automatically controls the opening degree of the throttle valve using a microcomputer so that the actual vehicle speed of the vehicle reaches a preset vehicle speed without pressing the accelerator pedal of the vehicle. This invention relates to an automobile speed control device.

In typical prior art, the automatic control of the throttle valve is released by executing a microcomputer program in response to a so-called cancel signal generated when a speed-reducing operation such as a brake or clutch is performed. In addition, when the microcomputer performs an operation that does not follow the program and goes out of control, such runaway is detected by executing a program for detecting runaway, and the speed of the microcomputer is automatically controlled. The program is configured to initialize and reset the program to its first step.
In such prior art, each of the programs described above is relatively complex, and it is extremely difficult to reliably detect runaways of various patterns using the programs.

Therefore, the applicant filed a patent application No. 55-177544.
We proposed a means to solve this problem. This outline simply prevents the microcomputer from running out of control by resetting the microcomputer when a speed control operation such as a brake is performed.

According to this prior art, when a speed reduction operation is performed, the microcomputer is reset (hereinafter referred to as cancel reset), but if the vehicle has a resume function, the memory for storing the set vehicle speed is cleared. The signal representing the set vehicle speed must be kept stored. This makes it possible to achieve a resume function in which the vehicle runs at a constant speed again at the set vehicle speed stored in the memory.

On the other hand, in such a vehicle speed control device, it is necessary to reset the microcomputer even when the power is turned on (hereinafter referred to as power-on reset), but in this case, the microcomputer included in the microcomputer for storing the set vehicle speed is required. This memory must be cleared as the data in the memory will become unstable, otherwise if the resume switch is operated by mistake after the power is turned on, the vehicle may be controlled at an incorrectly set vehicle speed. become. In particular, if the set vehicle speed data is high, the speed will be increased, which is dangerous. Therefore, in order to ensure safety and achieve the resume function, it is necessary to distinguish between cancel reset and power-on reset.

SUMMARY OF THE INVENTION An object of the present invention is to provide a speed control system for a vehicle that can distinguish between a power-on reset and a cancel reset to achieve a resume function without compromising safety.

The present invention energizes a microcomputer for constant speed driving control from a power source via a power switch,
A speed control for an automobile in which the microcomputer is reset while the memory contents storing the set vehicle speed are retained when constant speed driving control is canceled, and the memory contents are erased when the vehicle speed decreases below a predetermined speed. The device includes: means 59 for deriving a control signal in response to turning on a power switch; and a signal indicating that the actual vehicle speed is below the predetermined speed in response to the control signal from the control signal deriving means 59. and means 58 for controlling the speed of a motor vehicle.

Referring to FIG. 1, an embodiment of the present invention is shown, in which a spark ignition internal combustion engine 1 as a drive source for an automobile is shown.
A throttle valve 3 is provided in the intake path 2 of the engine. The throttle valve 3 is driven by an actuator 5 for automatic control via a link mechanism 4, and is also operated by an accelerator pedal 6. The microcomputer 7 is powered and operated by power from a power supply 8 via a power switch 9 and a line 10. When the vehicle is running with the speed controlled by the operation of the accelerator pedal 6, the microcomputer 7 gives a high level signal to the inverting circuit 11,
Therefore, the low level signal via the amplifier circuit 12 demagnetizes the release valve solenoid 13 included in the actuator 5. Therefore, the valve body 15 of the release valve 14 is displaced away from the valve seat 17 around the fulcrum 70 by the spring force of the spring 16. Therefore, the diaphragm chamber 18 of the actuator 5 is open to the atmosphere via the valve hole 19, and the diaphragm 20 remains biased by the spring 21 accordingly.

When the vehicle is running at the desired actual speed by operating the accelerator pedal 6, when the set switch 22 is operated, the actual vehicle speed is stored in the random access memory M included in the microcomputer 7, and the vehicle is driven at the set vehicle speed. The opening degree of the throttle valve 3 is automatically controlled so that this occurs, and the vehicle continues to travel at the set vehicle speed. More specifically, the set vehicle speed of the automobile is input from the vehicle speed detection means 50 to the input terminal iRQ of the microcomputer 7 via a line 51, a resistor 52, and a buffer 53. The microcomputer 7 has an input terminal iRQ
When the set switch 22 is operated in response to a signal input to the microcomputer 7 when the actual vehicle speed is a predetermined value, for example, 40 km/hour, the output of the set switch 22 is applied to the terminal i2 of the microcomputer 7; The actual vehicle speed is stored in the random access memory M as the set vehicle speed. input terminal
The actual vehicle speed indicated by the signal given to iRQ is 40km/
If the vehicle speed is less than 1 hour, the random access memory M is cleared and the vehicle speed is set to no value. The microcomputer 7 stores the actual vehicle speed of the vehicle at the time the set switch 22 is operated in a random access memory M provided in the microcomputer 7 as a set vehicle speed, and transmits it to the actuator 5 via the inverting circuit 23 and the amplifier circuit 24. Controls the included control valve solenoid 26. The control valve solenoid 26 is controlled by changing the duty of the excitation current. When the output from the microcomputer 7 to the reversing circuit 23 is at a high level and the control valve solenoid 26 is not excited, the valve body 28 of the control valve 27 is separated from the valve seat 30 by the spring force of the spring 29. Therefore, the diaphragm chamber 18
is open to the atmosphere through the valve hole 31. This control valve 27 is angularly displaceable around a fulcrum 32. When the valve body 28 is spaced apart from the valve seat 30,
The other valve body 33 is seated on the valve seat 34, so that the valve hole 35 is located in the diaphragm chamber 18.
I am blocking it. The valve hole 35 communicates with the intake path 2 upstream of the throttle valve 3 and is under negative pressure. When a low level signal is applied to the inverting circuit 23 from the microcomputer 7, the control valve solenoid 26 is energized. Therefore, the control valve 27 is in the state shown in the first diagram, the valve body 28 is seated on the valve seat 30, the valve body 33 is separated from the valve seat 34, and the diaphragm chamber 18 becomes under negative pressure. Due to the negative pressure in the diaphragm chamber 18, the diaphragm 20 is displaced to the right in FIG. 1 against the spring force of the spring 21.
As a result, the opening degree of the throttle valve 3 is controlled by the link mechanism 4.

Even if the vehicle is not running at the set vehicle speed, that is, even if the automatic speed control is cancelled, if the actual vehicle speed is higher than the predetermined vehicle speed, for example, 40 km/hour, by operating the resume switch 36, The output of the resume switch 36 is applied to the terminal i3 of the microcomputer 7, allowing the vehicle to return to the previously set vehicle speed and start traveling. The operation of the actuator 5 according to the operations of the set switch 22 and the resume switch 36 is achieved by the execution of a program by the microcomputer 7.

Microcomputer 7 has reset input terminal 4
has 0. When the reset input terminal 40 becomes low level, the microcomputer 7 is initialized to the first step of the program and enters the reset state. At this time, the inverting circuits 11 and 23
The signal input to is at a high level, so the microcomputer 7 keeps the release valve solenoid 13 and the control valve solenoid 26 demagnetized, and the vehicle can travel by operating the accelerator pedal 6.

A resistor 41 is connected between reset input terminal 40 and line 10. Reset input terminal 4
0 is grounded via a capacitor 42. The reset input terminal 40 is connected to a switch 44 which becomes conductive when a clutch interposed in the transmission means for transmitting power from the internal combustion engine 1 to the wheels is cut off by depressing the clutch pedal, and a switch 44 which is connected when the parking brake is activated. It is grounded to a low level via a switch 45 which is conductive when the voltage is on. In an automobile equipped with a so-called automatic transmission having a torque converter, the switch 44 is configured to conduct when the select lever is in the neutral position. These switches 44 and 45 have a function of being turned on by a speed control operation of the vehicle. A low level signal is applied to the reset input terminal 40 from the line 10 via a switch 46 and an inverting circuit 47. The switch 46 becomes conductive when the brake pedal is depressed and the vehicle is about to stop or has stopped. switch 4
6 is connected to line 10 via resistor 54. Line 51 is connected to line 10 through resistor 55.
connected to.

The vehicle speed detection means 50 is provided in association with the wheels of the automobile, and is realized by a permanent magnet piece that rotates at a rotational speed corresponding to the rotational speed of the wheel, and a reed switch that detects this permanent magnet piece. This vehicle speed detection means 50 may be realized by other configurations. The vehicle speed detection means 50 derives a pulse having a frequency directly proportional to the actual vehicle speed. When the actual vehicle speed is low, the period in which the line 51 remains at a high level becomes longer, and when the actual vehicle speed is high, the period in which the line 51 remains at a high level becomes shorter. .

According to the present invention, immediately after the power switch 9 is turned on, the connection point 5 between the resistor 52 and the buffer 53
6, the low speed equivalent signal from the low speed equivalent signal generating circuit 57 remains applied regardless of the output from the vehicle speed detecting means 50. microcomputer 7
, when the connection point 56 and the input terminal iRQ remain at high level, that is, when the predetermined vehicle speed is 40
When a signal representing less than Km/hour is given, the random access memory M is cleared.

The low-speed equivalent signal generation circuit 57 includes a transistor 58 connected to the line 10 and the connection point 56.
, a capacitor 59, resistors 61 and 62 connected to the connection point 60 of the capacitor 59 to charge the capacitor 59, a diode 63 connected to the connection point 60 to flow the discharge current of the capacitor 59, and A resistor 64 having a low resistance value is connected in series with a diode 63.

Referring to FIG. 2, when power switch 9 is turned on at time t1, the voltage on line 10 becomes high level as shown in FIG. 21. A capacitor 59 included in the low-speed equivalent signal generating circuit 57 is charged via a resistor 61 and via the emitter, base and resistor 62 of a transistor 58, so that the voltage at a node 60 is as shown in FIG. As shown, it gradually increases after time t1. Vehicle speed detection means 50 while the car is running
2, the voltage on line 51 becomes as shown in FIG. After time t1, connection point 6
The voltage at zero is low so transistor 58 remains conductive. Therefore, the voltage at node 56 remains at a high level until time t2, as shown in FIG. 24. microcomputer 7
is reset immediately after time t1 because the reset input terminal 40 is at a low level due to the action of the capacitor 42. Therefore, the microcomputer 7 can execute the program from the first step of the program. At this time, during the period from time t1 to t2, the connection point 56 and the input terminal iRQ remain at a high level, and the time from time t1 to t2 is equivalent to the actual vehicle speed being less than a predetermined value of 40 km/hour. It is a signal.
Therefore, the random access memory M included in the microcomputer 7 is cleared. Therefore, immediately after the power switch 9 is turned on, the vehicle speed is not increased to the set vehicle speed stored in the random access memory M, and safe driving is performed. After time t2, the transistor 58 is cut off, and therefore the vehicle speed detection means 5
The signal on line 51 from 0 is input to the input terminal iRQ of the microcomputer 7. In this manner, the automatic speed control program is executed by operating the set switch 22 and the resume switch 36.

During execution of this program, if the microcomputer 7 goes out of control, the driver depresses the brake pedal or the clutch pedal, causing the switches 46 and 44 to conduct and the reset input terminal 40 to go low. Then,
The microcomputer 7 is reset. This prevents the microcomputer 7 from running out of control. Further, when the parking brake is applied, the reset input terminal 40 remains at a low level, so that the microcomputer 7 does not run out of control.

Assume that a momentary power outage occurs at time t3 until time t4. Power switch 9
remains conductive, so capacitor 5
9 is discharged from the connection point 60 via the diode 63, the resistor 64, the line 10, and the power switch 9. The resistance value of the resistor 64 is small, so the charge on the capacitor 59 is discharged in a very short time, and the voltage at the connection point 60 decreases. In the period from time t4 to time t5, from time t1 to
The same operation as in the period t2 is performed, and the random access memory M is cleared. Therefore, the contents stored in the random access memory M are not undesirably changed due to a momentary power outage, and operational safety is ensured.

As described above, according to the present invention, when constant speed driving control is canceled and when the power is turned on, the microcomputer is reset with the memory contents storing the set vehicle speed retained, and when the power is turned on, the signal indicating the vehicle speed is set to a predetermined speed. Since the memory contents are cleared by suppressing the following, the memory contents can be erased and reset when the power is turned on, and the memory contents can be reset with the memory contents held when constant speed driving control is canceled. Therefore, the resume function can be achieved without compromising safety.

[Brief explanation of the drawing]

FIG. 1 is an overall system diagram of an embodiment of the present invention, and FIG. 2 is a waveform diagram for explaining its operation. 1... Internal combustion engine, 2... Intake path, 3... Throttle valve, 5... Actuator, 6... Accelerator pedal,
7... Microcomputer, 8... Power supply, 9... Power switch, 11, 23, 47... Inverting circuit, 22...
Set switch, 36...Regium switch, 4
0...Reset input terminal, 41...Resistor, 42...Capacitor, 44, 45, 46...Switch, 57...Low speed equivalent signal generation circuit, 58...Transistor, 59
...Capacitor, 61, 62, 64...Resistor, 63...
diode.

Claims (1)

[Scope of Claims] 1. A microcomputer for constant speed driving control is energized from a power source via a power switch, and when constant speed driving control is canceled, the microcomputer is activated while retaining the memory contents for storing the set vehicle speed. When the vehicle speed drops below the specified speed,
The speed control device for an automobile that erases the memory contents includes means 59 for deriving a control signal in response to turning on a power switch; and in response to the control signal from the control signal deriving means 59, the actual vehicle speed is determined. and means 58 for providing a signal indicating that the speed is below the predetermined speed to a microcomputer.