Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Patent
1998-08-14
2000-06-13
Butler, Douglas C.
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
303 10, 3031131, 3031164, 3031132, B60T 832
Patent
active
060740183
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention relates to a hydraulic vehicle brake system with an arrangement for traction control and/or vehicle dynamics control and with two or more brake circuits.
One such vehicle brake system with two brake circuits, known from German Patent DE 42 32 311 C1, has a tandem master cylinder, which by means of a switchover valve downstream of the master cylinder can be disconnected from the other hydraulic elements. The known vehicle brake system also has a brake pressure modulation valve assembly, with a brake pressure buildup valve and a brake pressure reduction valve for brake pressure modulation in each wheel brake cylinder. With a return pump, brake fluid that has flowed out of the wheel brake cylinder is fed in the direction of the master cylinder or back into the wheel brake cylinders.
To enable building up brake pressure when the master cylinder is not actuated, for the sake of traction control, the known vehicle brake system has an intake valve, by which an intake side of the return pump communicates with the master cylinder. However, this has the disadvantage that the intake valve acts as a throttle and thus delays the brake pressure buildup. However, such a delayed brake pressure buildup, for vehicle dynamics control or in other words stabilization of the vehicle, especially in fast cornering, by purposeful braking of individual vehicle wheels to prevent skidding, is unacceptable, since the vehicle is already skidding before the vehicle dynamics control becomes operative.
The known vehicle brake system therefore has a precharge pump, to which brake fluid is aspirated from a supply container of the master cylinder and is carried to the two brake circuits via special hydraulic components, known as plungers. Through the intake valves, the brake fluid, aspirated from the container by the precharge pump, flows to the intake side of the return pump. The plungers are necessary first in order to disconnect the master cylinder hydraulically from the brake circuits when the precharge pump is in operation. Otherwise the brake fluid would flow from the precharge pump through the unactuated master cylinder into the supply container thereof. Second, the plungers are necessary in order to keep the two brake circuits hydraulically separated from one another. The plungers are complicated and hence expensive hydraulic components. Another disadvantage is that the plungers communicate hydraulically with the respectively other brake circuit. If one of the two plungers is defective, this can mean that the two brake circuits communicate with one another hydraulically, which if there is a leak in one brake circuit for instance causes a failure of the entire vehicle brake system. It is critical to disconnect the two brake circuits, from the standpoint of functional safety of the vehicle brake system.
ADVANTAGES OF THE INVENTION
The vehicle brake system according to the invention has an additional pump in each brake circuit for generating brake pressure; this pump is connected directly to the master cylinder. Between an intake side of the additional pump and the master cylinder, there are no hydraulic components that would act as throttles and thereby delay the brake pressure buildup. The invention has the advantage of a rapid brake pressure buildup when the master cylinder is not actuated, which is advantageous at least for the sake of traction control and is indispensable for vehicle dynamics control. Another advantage of connecting the additional pump to the master cylinder is that no additional intake line to a brake fluid container and no additional connection to the brake fluid container is necessary, a connection that would require a modified brake fluid container. Another advantage of the invention is that each vehicle wheel can be braked when the master cylinder is not actuated. This is a necessity for traction control if driven vehicle wheels are assigned to different brake circuits. For vehicle dynamics control, it is always necessary that it be possible to brake each vehicle wheel individually.
REFERENCES:
patent: 4580848 (1986-04-01), Widmer
patent: 4875741 (1989-10-01), Ozawa et al.
patent: 4952002 (1990-08-01), Arikawa et al.
patent: 4969696 (1990-11-01), Yogo et al.
patent: 5046788 (1991-09-01), Lindenman
patent: 5167442 (1992-12-01), Alaze et al.
patent: 5242216 (1993-09-01), Miyawaki et al.
patent: 5261731 (1993-11-01), Yogo et al.
patent: 5277483 (1994-01-01), Yosida et al.
patent: 5393132 (1995-02-01), Yogo et al.
patent: 5441336 (1995-08-01), Takeuchi
Patent Abstracts of Japan, vol. 14, No. 545 (M-1054) Dec. 4, 1990 and JP 02-231256A Sep. 13, 1990.
Breitenbacher Jurgen
Heinsohn Rainer
Kaess Hermann
Klug Andreas
Willmann Karl-Heinz
Butler Douglas C.
Greigg Edwin E.
Greigg Ronald E.
Robert & Bosch GmbH
LandOfFree
Motor vehicle braking system with and traction control and/or mo does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Motor vehicle braking system with and traction control and/or mo, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Motor vehicle braking system with and traction control and/or mo will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2062873