Antiskid control device

• US 4,855,917 A
• Filed: 05/27/1987
• Issued: 08/08/1989
• Est. Priority Date: 05/30/1986
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Tokico Limited (Hitachi, Ltd.)
• Inventors: Sakuma, Masaru, Nagai, Hideaki, Sawano, Susumu, Funabashi, Tatsuya
• Primary Examiner(s): Chin, Gary
• Application Number:
  US07/054,659
• Time in Patent Office: 804 Days
• Field of Search: 364/426.02, 180/197, 303/95, 303/97, 303/103, 303/105
• US Class Current: 701/80
• CPC Class Codes: B60T 8/172 Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters B60T8/17551 takes precedence
• CPC Class Codes: B60T 8/173 Eliminating or reducing the effect of unwanted signals, e.g. due to vibrations or electrical noise
• CPC Class Codes: B60T 8/17636 Microprocessor-based systems

Abstract

In an antiskid control device comprising detectors for measuring circumferential velocities of a plurality of wheels an actuator for operating a braking oil pressure for each of the wheels and an electric circuit for calculating friction coefficients on the road surfaces, to which the wheels are in contact, calculating aimed wheel circumferential velocities from the friction coefficients on the road surfaces and operating the actuator such that each of the aimed wheel circumferential velocities and each of the measured wheel circumferential velocities coincide with each other, the electrical circuit operates the actuator by setting individual aimed wheel circumferential velocities for the plurality of wheels from a vehicle deceleration calculated from an average value for the friction coefficients on the road surfaces with which a plurality of wheels are in contact, respectively, and the slip ratio for each of the plurality of wheels.

Claims

1. An antiskid control device comprising:

detectors for measuring circumferential velocities of a plurality of respective wheels,

actuator means for providing a braking oil pressure to each of said wheels, and

electric circuit means for calculating frictional coefficients of road surfaces in contact with said wheels respectively based on the measured values from said detectors, for calculating aimed wheel circumferential velocities of the respective wheels based on the calculated frictional coefficients of the road surfaces, and for operating said actuator means such that respective ones of said aimed wheel circumferential velocities coincide with respective ones of the measured wheel circumferential velocities,

said electric circuit means being adapted to operate said actuator means by setting individual aimed wheel circumferential velocities for each of said plurality of wheels based on a vehicle deceleration calculated from an average value for the frictional coefficients of road surfaces with which said plurality of wheels are in contact, respectively, and based on a slip ratio for each of the plurality of wheels.

2. An antiskid control device comprising:

electromagnetic valve means operatively connected to an oil pressure system for controlling braking oil pressure of the oil pressure system so as to facilitate operation of a vehicle brake operatively connected to the oil pressure system, and

a control circuit for operating said electromagnetic valve means,

wherein said control circuit comprises detection means for detecting a wheel circumferential velocity, estimation means for estimating a friction coefficient of a road surface based on the wheel circumferential velocity detected by said detection means, calculation means for calculating an aimed wheel circumferential velocity based on the friction coefficient of the road surface estimated by said estimation means, electromagnetic valve operation means for comparing the aimed wheel circumferential velocity calculated by said calculation means with the wheel circumferential velocity detected by said detection means, and for outputting a signal for operating said electromagnetic valve means so as to reduce the oil pressure of said oil pressure system when the wheel circumferential velocity detected by said detection means goes lower than the aimed wheel circumferential velocity calculated by said calculation means, and control means for interrupting control of the braking oil pressure of the oil pressure system by the electromagnetic valve means so as to decrease the braking oil pressure for a predetermined time in a case where said estimation means estimates the friction coefficient of the road surface to be greater than a predetermined value.

3. An antiskid control device as defined in claim 2, wherein the control means is adapted to decrease the aimed wheel circumferential velocity calculated by the calculation means.

4. An antiskid control device as defined in claim 2, wherein the control means is adapted to interrupt the signal outputted by the electromagnetic valve operation means.

5. In an antiskid control device, comprising:

valve control means responsive to a wheel circumferential velocity signal corresponding to a wheel circumferential velocity of a vehicle and to an estimated road friction signal corresponding to an estimated road friction of a road on which the vehicle is traveling for generating a valve control signal,

road friction estimating means responsive to the wheel circumferential velocity signal for generating the estimated road friction signal, and

valve means connected to an oil pressure system of the vehicle and responsive to the valve control signal and to the estimated road friction signal for controlling braking oil pressure of the oil pressure system so as to facilitate operation of a vehicle brake of the vehicle operatively connected to the oil pressure system;

the improvement comprising valve control modifying means responsive to the estimated road friction signal for generating a valve control modifying signal when the estimated road friction signal indicates that the estimated road friction is not equal to a predetermined value, said valve control means being responsive to said valve control modifying signal for modifying the braking oil pressure of the oil pressure system for a predetermined time.

6. In the device of claim 5, wherein said valve control means lowers the braking oil pressure of the oil pressure system when the estimated road friction is greater than the predetermined value.

7. In the device of claim 5, wherein the valve control means raises the braking oil pressure of the oil pressure system when the estimated road friction is less than the predetermined value.

8. In the device of claim 5, wherein said valve control modifying means comprises:

a timer for generating a timer signal;

a decision section responsive to the timer signal and to the valve control signal for generating a control output; and

a processor section responsive to the control output from the decision section and to the estimated road friction signal from the road friction estimating means for generating said valve control modifying signal.