Hydraulic dual-circuit brake system for automobiles

• US 4,740,039 A
• Filed: 10/07/1986
• Issued: 04/26/1988
• Est. Priority Date: 04/17/1984
• Status: Expired due to Fees

• Current Assignee: Volkswagen AG
• Original Assignee: Volkswagen AG
• Inventors: Hattwig, Peter
• Primary Examiner(s): Butler, Douglas C.
• Application Number:
  US06/915,869
• Time in Patent Office: 567 Days
• Field of Search: 303/6 C, 303/6 R, 303/111, 303/113-119, 303/61-63, 303/68-69, 303/92, 303/98, 303/89, 303/100, 188/349, 188/151 A, 188/181 A, 188/11, 188/345, 188/353
• US Class Current: 303/9.75
• CPC Class Codes: B60T 8/26 characterised by producing differential braking between front and rear wheels using electrical circuitry or regulation means B60T8/17

Abstract

A hydraulic dual-circuit brake system for automobiles, comprising wheel brakes positioned at the front and rear wheels, a master brake cylinder, brake lines for transmitting brake pressure from the master brake cylinder to the wheel brakes to actuate the latter, a brake pressure regulator device incorporating a hydraulically operated switching off device interposed between the rear wheel brakes and the master brake cylinder, and a brake slip regulation device including a hydraulic unit, sensors for providing a signal output representative of wheel movement behavior, and an electronic anti-skid control and regulating device responsive to the signal output for controlling the hydraulic unit to affect the brake pressure transmitted by the hydraulic unit to the switching off endangered wheel brake. The hydraulically operated locking device of the brake pressure regulator device responds to the brake pressure transmitted by the hydraulic unit to the locking-endangered wheel brakes and modifies the operation of the brake pressure regulator device to affect the brake pressure delivered to the rear wheel brakes by the brake pressure regulator device.

Claims

1. A hydraulic dual circuit brake system for automobiles, in particular passenger cars having front and rear wheels, comprising:

wheel brake means positioned at the front and rear wheels for arresting wheel motion;

a master brake cylinder;

a plurality of brake lines for transmitting brake pressure from the master brake cylinder to the wheel brake means to actuate the latter;

brake pressure regulator means incorporating hydraulically operated switching off means with a hydraulic control inlet for switching off a reducing or limiting function of the brake pressure regulator means, said brake pressure regulator means being interposed between the wheel brake means for the rear wheels and the brake lines for transmitting brake pressure from the master brake cylinder thereto;

brake slip regulation means, including;

hydraulic means interposed between the master brake cylinder and the front and rear wheel brake means;

sensor means at each of said front and rear wheels responsive to wheel movement behavior for providing a sensor signal output representative of the wheel movement behavior; and

electronic anti-skid control and regulating means responsive to the sensor signal output for controlling the hydraulic means to affect the brake pressure transmitted by the hydraulic means on a locking-danger condition of at least one wheel, characterized in that

the hydraulic control inlet of the hydraulically operated switching off means of the brake pressure regulator means is connected to said hydraulic means between said master brake cylinder and the rear wheel brake means and responsive to the brake pressure transmitted by the hydraulic means to the right front wheel brake means when danger of locking is detected by the anti-skid control and regulating means so as to modify the operation of the brake pressure regulator means to affect the brake pressure delivered to the brake means for the rear wheel, the electronic anti-skid control and regulating means being provided so as to control the hydraulic means to lower or maintain constant the brake pressure transmitted to the locking-endangered wheel brake means when the sensor means provides a sensor output signal which indicates that a front wheel is locking-endangered, said hydraulically operated switching off means being responsive to the lower brake pressure by modifying operation of the brake pressure regulator means to increase the brake pressure delivered to the rear wheel brake means.

2. A hydraulic dual-circuit brake system as defined in claim 1, and further comprising a first brake circuit means including the right front wheel brake means and left rear wheel brake means, and a second brake circuit means including the left front wheel brake means and the right rear wheel brake means, the brake force distribution means further including means for independently transmitting brake pressure to the right rear and left rear wheel brake means, and the hydraulically operated switching off means further includes means responsive to the brake pressure transmitted by the hydraulic means to each front wheel brake means for modifying the operation of the brake pressure regulator means to affect the brake pressure delivered to the diagonally opposite rear wheel brake means.