Anti-skid brake control system based on acceleration detection

• US 5,280,432 A
• Filed: 08/06/1990
• Issued: 01/18/1994
• Est. Priority Date: 08/05/1989
• Status: Expired due to Fees

• Current Assignee: Aisin Seiki Co., Ltd. (Aisin Corp.)
• Original Assignee: Aisin Seiki Co., Ltd. (Aisin Corp.)
• Inventors: Yoshida, Tsuyoshi, Okamoto, Kuniaki, Sakai, Kazunori, Sugitani, Tatsuo, Nakanishi, Nobuyasu, Kuwana, Kazutaka, Ichikawa, Hiroyuki, Kamikado, Masaru
• Primary Examiner(s): Lall, Parshotam S.
• Assistant Examiner(s): PARK, COLLIN
• Application Number:
  US07/562,991
• Time in Patent Office: 1,261 Days
• Field of Search: 364/426.02, 364/426.01, 364/426.03, 303/95, 303/97, 303/100, 303/103, 303/91, 303/93, 303/94, 303/99, 303/109, 180/197
• US Class Current: 701/79
• CPC Class Codes: B60T 8/17616 Microprocessor-based systems
• CPC Class Codes: B60T 8/328 Systems sharing components with other fluid systems onboard the vehicle
• CPC Class Codes: B60T 8/344 Hydraulic systems
• CPC Class Codes: B60T 8/4225 having a fluid actuated expansion unit

Abstract

The anti-skid control system is constructed with a brake fluid pressure source for generating brake fluid pressure at high and low levers, a switching valve feeding either high pressure or low pressure to the wheel cylinders, a wheel velocity detecting device sensing the driving wheel rotating speed, an acceleration detecting device detecting the vehicle acceleration and a first arithmetic operation device for finding the estimated vehicle speed and the wheel rotating acceleration based on the wheel velocity detected by the wheel velocity detecting device and the vehicle body acceleration detected by the acceleration detecting device. A brake fluid pressure controlling device is provided for increasing, decreasing or maintaining the brake fluid pressure in the wheel cylinders, controlling the switching valve on the basis of wheel velocity, estimated vehicle speed, and wheel rotating acceleration. A second arithmetic operation device marks the minimum and maximum values in the wheel velocity after a brake fluid pressure reduction based on the wheel velocity detected by the wheel velocity detecting device calculates the recovery acceleration in the wheel velocity in the shift from the minimum value to the maximum value and compares the recovery acceleration with the set value. A vehicle acceleration correcting device corrects the vehicle body acceleration detected by the acceleration detecting device so as to set the vehicle body acceleration at a smaller value in case the recovery acceleration is less than the set value.

Claims

1. An anti-skid control system for a vehicle having driving wheels, said system comprising:

a brake fluid pressure source for generating high pressure and low pressure;

a switching valve means installed between said pressure source and wheel cylinders of the driving wheels driven by a power source via a speed change gear for selectively feeding either one of said high pressure and said low pressure to said wheel cylinders,

a wheel velocity detecting means for detecting rotating speed of the driving wheels;

an acceleration detecting means for detecting acceleration of the vehicle;

a first arithmetic operation means for calculating an estimated vehicle speed and a rotating acceleration of the wheels by arithmetic operations on the basis of the rotating speed of the driving wheels detected by said wheel velocity detecting means and the acceleration of the vehicle detected by said acceleration detecting means;

a brake fluid pressure controlling means for increasing, decreasing or maintaining the brake fluid pressure in said wheel cylinders by controlling said switching valve means on the basis of said rotating speed of the driving wheels, said estimated vehicle speed and said rotating acceleration of the wheels;

a second arithmetic operation means for calculating a minimum value and a maximum value in said rotating speed of the driving wheels after a reduction of the pressure in the brake fluid on the basis of the rotating speed of the driving wheels detected by said wheel velocity detecting means, calculating a recovery acceleration in said rotating speed of the driving wheels in a shift from said minimum value to said maximum value, and comparing said recovery acceleration with a set value; and

a vehicle acceleration correcting means for correcting the acceleration of the vehicle detected by said acceleration detecting means so as to set said acceleration of the vehicle at a smaller value in case said recovery acceleration is less than the set value.

2. An anti-skid control system as defined in claim 1, wherein the brake fluid pressure controlling means controls the switching valve means in such a manner that said switching valve means reduces the pressure of the brake fluid in the wheel cylinders when the rotating speed of the driving wheels declines to a level below the estimated vehicle speed and controls said switching valve means in such a manner that said switching valve means increases the pressure of the brake fluid in said wheel cylinders when said rotating speed of the driving wheels has exceeded said estimated vehicle speed.

3. An anti-skid control system as defined in claim 2, wherein the brake fluid pressure controlling means controls the switching valve means in such a manner that said switching valve means reduces the pressure of the brake fluid in the wheel cylinders when the rotating speed of the driving wheels is below the estimated vehicle speed while the rotating acceleration of the wheels is less than a prescribed value and controls said switching valve means in such a manner that said switching valve means maintains at the same level the pressure of the brake fluid in said wheel cylinders when said rotating speed of the driving wheels is less than said estimated vehicle speed while said rotating accelerating of said wheels is above the prescribed value, and wherein said brake fluid pressure controlling means further provides a reduction of the pressure in the brake fluid in said wheel cylinders, inhibiting the maintaining of said brake fluid pressure in said wheel cylinders by said switching valve means, when the second arithmetic operation means finds that said recovery acceleration is less than the set value while said rotating speed of the driving wheels is below said estimated vehicle speed and said rotating acceleration of said wheels is in excess of the prescribed value.