Constant-speed running apparatus with fault monitoring for automobile

• US 5,109,342 A
• Filed: 11/27/1989
• Issued: 04/28/1992
• Est. Priority Date: 01/27/1988
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Kondo, Yasuhiro, Nakano, Shigeru
• Primary Examiner(s): Lall, Parshotam S.
• Assistant Examiner(s): ZANELLI, MICHAEL J
• Application Number:
  US07/439,354
• Time in Patent Office: 883 Days
• Field of Search: 364/426.04, 364/431.07, 364/431.11, 364/551.01, 180/170, 180/178, 180/179, 123/352, 123/349, 123/350, 123/361, 371/62, 371/16.3
• US Class Current: 701/97
• CPC Class Codes: B60K 31/047 the memory being digital

Abstract

A high-safety constant-speed running apparatus for an automobile which periodically provides an OFF signal for a small time having no effect on driving an actuator. The OFF signal is located in a signal controlling the actuator which is outputted from a micro-computer by a control signal OFF device. Presence or absence of this OFF signal is monitored by a control signal monitor, and when the OFF signal is not detected for a predetermined time or more a determination is made that the micro-computer is abnormal, which drives the actuator in the direction of closing a throttle valve through a throttle close control signal output, and thereby closes the throttle valve when the micro-computer is abnormal. This can reliably return the car to operating based on the driver'"'"'s commands.

Claims

1. In a constant-speed running apparatus for an automobile which compares an arbitrarily set car speed with an actual car speed and controls a degree of opening of a throttle valve through an actuator in a manner that both speeds agree with each other, the constant-speed running apparatus comprising:

a driving output means for driving said actuator,

an arithmetic operation means for operating a driving direction and a driving time of said actuator,

a control signal output means for outputting a control signal for the actuator to said driving output means on the basis of the driving direction and the driving time of the actuator operated by said arithmetic operation means,

a control signal OFF means for periodically providing an OFF signal into said control signal for a minute time which is short enough to have no effect on driving said actuator, and

a control signal monitor means which monitors for said OFF signal in said control signal and judges that said arithmetic operation means or said control output means is abnormal when the OFF signal is not detected for a predetermined time or more, to output a control abnormality signal.

2. In a constant-speed running apparatus for an automobile which compares an arbitrarily set car speed with an actual car speed and controls a degree of opening of a throttle valve through an actuator in a manner that said speeds agree with each other, the constant-speed running apparatus comprising:

a driving output means for driving said actuator;

a microcomputer which operates a driving direction and a driving time of said actuator by outputting an appropriate control signal of the actuator to said driving output means, and which rewrites a RAM by timer interrupt processing, and when confirming by main processing that the RAM has been re-written, periodically provides an OFF signal into said control signal for a minute time which is short enough to have no effect on said actuator; and

control signal monitor means which monitors for said OFF signal in said control signal, and when the OFF signal is not detected for at least a predetermined time, determining that the micro-computer is abnormal, and outputting a control abnormality signal.

3. In a constant-speed running apparatus for an automobile which compares an arbitrarily set car speed with an actual car speed, and controls a degree of opening of a throttle valve in a manner that said speeds agree with each other, said constant-speed running apparatus comprising:

an actuator for adjusting a degree of opening of a throttle valve;

a driving output means for driving said actuator;

a micro-computer which operates a driving direction and a driving time of the actuator by outputting a control signal to said driving output means, said microcomputer sending the control signal of the actuator through a throttle open control signal line when said throttle valve is opened and sending the control signal through a throttle close control signal line when the throttle valve is closed, and for periodically providing an OFF signal within said control signal for a minute time which is short enough to make no effect on driving said actuator;

an NPN-type transistor, a base of which is connected to the output of a first NOT gate receiving said control signal through a first resistor, a collector of which is connected to a control power supply through a second resistor and connected to one end of a third resistor, and an emitter of which is connected to a ground of the control power supply;

control signal monitor means having an input connected to the other end of said third resistor comprising a first capacitor, said other end of said third resistor being connected to one end of said first capacitor, the other end of the first capacitor being connected to the ground of the control power supply,

a second NOT gate having an input terminal which is connected to a connection part between the third resistor and said one end of the first capacitor,

a third NOT gate in series with said second NOT gate, having an output which is connected at least to the throttle open control signal line, and thereby when the OFF signal of said control signal is not detected for a predetermined time, the output of said third NOT gate rises and outputs a control abnormality signal;

a throttle close control signal output means which includes a thyristor having a gate which is connected to the output of said third NOT gate through a first diode, a cathode of which is connected to the ground of the control power supply, and an anode of which is connected to said throttle open control signal line through a second diode and is connected to one end of a fourth resistor through a third diode;

a PNP-type transistor, a base of which is connected to another end of said fourth resistor, a collector of which is connected to the throttle close control signal line, and an emitter of which is connected to the control power supply through a fifth resistor, and a sixth resistor for connecting the emitter and the base of said PNP-type transistor, so that said PNP transistor outputs the control signal for driving the actuator in the direction of closing the throttle valve by the control abnormality signal from said control signal monitor means to said driving output means.

4. A method of operating a constant-speed running apparatus for an automobile, comprising the steps of;

comparing an arbitrarily set car speed with an actual car speed;

controlling a degree of opening of a throttle valve through an actuator in a manner that both speeds agree with each other, by controlling a driving direction and a driving time of said actuator, and outputting a control signal for the actuator to said throttle valve on the basis of the driving direction and the driving time of the actuator;

periodically providing an OFF signal into said control signal for a minute time short enough to have no effect on driving said actuator; and

monitoring for said OFF signal in said control signal and determining an abnormality when the OFF signal is not detected for a predetermined time, to output a control abnormality signal.