Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Patent
1997-09-29
1999-07-27
Poon, Peter M.
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
3031154, 3031161, 3031191, B60T 834
Patent
active
059278242
DESCRIPTION:
BRIEF SUMMARY
This invention is directed to a brake system and more particularly to a vehicle hydraulic brake system.
BACKGROUND AND PRIOR ART
From FIGS. 1 and 4 of German Patent Application DE 44 45 401 A1, a vehicle hydraulic brake system is known that has a master cylinder which has a housing and in it a bore in which a first piston can be displaced as a function of the depression of a brake pedal. A second piston is disposed displaceably on a side of the first piston remote from the brake pedal. The first and second pistons between them define a first pressure chamber, which communicates with a first connection embodied on the housing and with a second connection. The second piston on a side remote from the first pressure chamber defines a second pressure chamber, which communicates with a third connection embodied on the housing and with a fourth connection. The first piston blocks off the communication between the first connection and the first pressure chamber, and the second piston blocks off the communication between the third connection and the third pressure chamber--in each case when the brake pedal is depressed. A supply container is provided for storing pressure fluid and for communicating with the third connection of the master cylinder. A valve assembly is provided for opening or closing the communication between the first connection of the master cylinder and the supply container. A pump device, which has a suction connection communicating with the supply container and a pressure connection communicating with the second connection of the master cylinder and which aspirates the pressure fluid from the supply container and pumps it to the second connection. A plurality of wheel brake cylinders are provided for associated wheels, in order to brake these wheels, the brake cylinders are divided into a first group of wheel brake cylinders and a second group of wheel brake cylinders; having first brake pressure modulation valve assemblies, which are disposed between the second connection of the master cylinder and the first group of wheel brake cylinders; having second brake pressure modulation valve assemblies, which are disposed between the fourth connection of the master cylinder and the second group of wheel brake cylinders. A control unit, in order to actuate the valve assembly for opening or closing the communication between the first connection of the master cylinder and the supply container an agreement with an operating mode selected from among an opening operating mode and a closing operating mode is provided. The pump device is embodied as a high-pressure pump, whose feed pressure is limited by a pressure limiting valve to a pressure that is at least as high as a maximum brake pressure to be supplied to at least one wheel brake cylinder. As a result, this hydraulic vehicle brake system is capable without actuation of the brake pedal of generating brake pressures for traction control, also known as drive slip control, by conditional braking of at least one drivable wheel. The hydraulic vehicle brake system of FIGS. 1 and 4 have the disadvantage that aside from normal braking by brake pedal actuation, it is arranged for only the traction control mode, and that the high pressure that can be furnished by this pump device requires a first connection on the master cylinder that can withstand this high pressure. Accordingly, it is not possible to use a normal master cylinder with the known connections, in which as connecting elements to the respective supply container merely elastic rubber rings are placed. Instead of the communication via this kind of elastic rubber ring, a screw connection would have to be provided, for instance, which is for instance identical to screw connections for the second connection and the fourth connection. It is advantageous, however, that by means of the second connection the pump device builds up a pressure in the pressure chamber that by means of the second piston also produces a pressure rise in the second pressure chamber and this pressure rise is available through the
REFERENCES:
patent: 5240314 (1993-08-01), Morita
patent: 5401083 (1995-03-01), Altmann et al.
Alaze Norbert
Dzierzawa Guenter
Herderich Hans-Juergen
Herr Johann
Holzmann Roland
Greigg Edwin E.
Greigg Ronald E.
Poon Peter M.
Robert & Bosch GmbH
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