HYDRAULIC VEHICLE BRAKE SYSTEM

摘要

A known hydraulic vehicle brake system (DE 44 45 401 A1) has brake pressure modulation valve systems situated between a dual-circuit main brake cylinder and vehicle wheel brakes. Traction control is ensured by a pump device which is supplied from a reservoir of the main brake cylinder and forces hydraulic fluid into a first pressure chamber between a first piston and a second piston and feeds it to the brake pressure modulation devices connected to said first pressure chamber in order to lead at least a portion of it into the wheel brakes. The pressure in the first pressure chamber displaces the second piston, thereby ensuring that pressure is also applied to the other brake pressure modulation valve devices. The pump device is therefore a high-pressure pump. It is proposed that the pump device should take the form of a low-pressure pump (76), and a first and second return pump (40, 41) should be allocated to the brake pressure modulation valve devices (42, 43, 44, 45); in automatic brake operation, the first pressure chamber (17) should be connected to the first return pump, while the second pressure chamber (18) should be connected on the inlet side to the second return pump. The low-pressure pump (76) generates in automatic brake operation a load pressure for the return pumps (40, 41) significantly lower than a maximum brake pressure, and the return pumps (40, 41) generate the highest predetermined brake pressure and serve in any anti-lock operation to pump hydraulic fluid from the wheel brakes back to the main brake cylinder. Inside the proposed vehicle brake system, the inexpensive low-pressure pump (76) ensures a high level of efficiency of the return pumps (40, 41) in automatic brake operation.