Power plants – Pressure fluid source and motor – Utilizing lubricant – starter motor – cooling fluid – or fluid...
Reexamination Certificate
1999-08-16
2001-10-16
Ryznic, John E. (Department: 3745)
Power plants
Pressure fluid source and motor
Utilizing lubricant, starter motor, cooling fluid, or fluid...
C060S411000, C060S412000
Reexamination Certificate
active
06301883
ABSTRACT:
TECHNICAL FIELD
The technical field of this invention is vehicle brake boosters of the type providing a differential pressure actuator working with a source of vacuum.
BACKGROUND OF THE INVENTION
Power brake assist using differential pressure actuated brake boosters is standard in the motor vehicle industry. These brake boosters have a diaphragm separating a vacuum chamber always open to a source of vacuum, such as created in an engine intake passage, and a working chamber normally provided with vacuum but controlled by valve apparatus responsive to input brake pedal actuation to allow atmospheric air therein and thus provide brake force assist through the diaphragm. In some systems, it is also known to provide a vacuum pump, either in place of the engine vacuum source or as a backup therefor, to provide a normal supplied vacuum.
But such brake boosters, which increase brake assist by decreasing vacuum in the working chamber, reach a limiting assist condition, called run-out, when the working chamber reaches atmospheric pressure. Although such boosters are generally designed so as to rarely reach the run-out condition, engine vacuum is limited and large, heavily loaded vehicles especially may require larger brake assist levels. Potential assist levels may be increased somewhat by the use of multiple diaphragm and chamber designs as are known in the art; but great size and weight penalties may result for assist capacity that is rarely used. It is desirable to provide a brake booster assist supplementing apparatus that provides such occasional greater than normal assist levels without incurring the size and weight penalties of a very large booster.
SUMMARY OF THE INVENTION
The brake booster of this invention provides additional boost capacity without unduly increasing booster size and weight by providing a vacuum pump connected so as to add its additional vacuum capacity to that of the normal vacuum source when activated in response to sensed approaching run-out. The additional vacuum is provided by connecting the vacuum pump in a second conduit between the vacuum source and the booster vacuum chamber in parallel with a first conduit connecting the vacuum source directly with the booster vacuum chamber, with check valve means in the first and second conduits preventing substantial vacuum loss from the vacuum chamber. Approaching run-out is signaled by a sensor responsive to a vacuum level in the working chamber; and control means are responsive to a predetermined low value of the sensed vacuum level in the working chamber to activate the vacuum pump and thus increase the vacuum level in the vacuum chamber over that produced by the vacuum source, whereby a greater pressure differential is available across the booster diaphragm before run-out is encountered. An optional sensor responsive to vacuum level in the vacuum chamber enables the vacuum pump to be additionally used for backup of the vacuum source while still providing the functionality of the invention in most cases. The venting of the vacuum pump to the vacuum source reduces released noise which might otherwise require bulky noise filter apparatus.
REFERENCES:
patent: 2705870 (1955-04-01), Holton
patent: 2844003 (1958-07-01), Ingres
patent: 4024709 (1977-05-01), Erdmann
patent: 4412416 (1983-11-01), Van House
patent: 4738112 (1988-04-01), Nomura et al.
patent: 5961189 (1999-10-01), Lutteke et al.
patent: 57-164854 (A) (1982-10-01), None
Fulks Gary Chris
Goecke Michelle Kay
Haerr Timothy Allen
Poole Douglas E.
Schlangen Timothy M.
Delphi Technologies Inc.
Ryznic John E.
Sigler Robert M.
LandOfFree
Vehicle brake booster with supplemental vacuum assist does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Vehicle brake booster with supplemental vacuum assist, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Vehicle brake booster with supplemental vacuum assist will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2560212