Motors: expansible chamber type – Working member position feedback to motive fluid control – Follower type
Patent
1996-03-08
1998-10-27
Lopez, F. Daniel
Motors: expansible chamber type
Working member position feedback to motive fluid control
Follower type
F15B 910
Patent
active
058264841
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a pneumatic brake booster using first and second sources of air pressure delivering first and second respective and different pressures, this booster comprising a rigid casing divided by at least one leaktight moving partition into at least two chambers, the first of which is connected to the first source, and the second of which can be connected selectively, by means of a valve, to either one of the two sources, it being possible for the moving partition to be urged by a difference in pressure brought about by an actuation of the valve, between the pressures supplied to the chambers, in order to drive along an at least partially cylindrical pneumatic piston sliding in leaktight fashion in the casing and bearing the valve, the inside of this piston and especially the valve being separated from the second source by a purification filter.
Devices of this type, well known in the prior art, are used on a very great number of motor vehicles nowadays.
Despite the traditional nature of the techniques involved, boosters continue to form the subject of substantial research, aiming to optimize their operating characteristics.
Among this research feature especially attempts to reduce both the level of noise of boosters in operation and their response time following actuation, the simultaneous reduction in these two parameters being made tricky by the fact that a booster is all the quieter if the air it lets into the rear chamber is filtered to a greater extent, while it has a response time which is all the shorter if the air it lets in is filtered to a lesser extent.
Moreover, as statistical studies have shown that collisions between vehicles could be avoided in a not insignificant proportion by less hesitant braking on the part of the drivers, the design of current braking systems tends to recognize the need to remedy the effects of any hesitation of the driver at the time of braking.
The invention falls within this context, and its object is to provide a booster which meets the expectations of the public as regards reduction in the level of noise in operation, while offering a response time which is at least as satisfactory as those of boosters of the prior art, in all cases where the need for a short response time is felt, and while offering increased braking safety.
To this end, the booster of the invention is essentially characterized in that it further includes at least one first air intake path formed by a passage which causes the second chamber to communicate with the second source of pressure, avoiding passing through the filter and the valve; shut-off means with selective opening installed on the first air intake path between the second source of pressure and the inside of the piston; and elastic means which are sensitive to a drop in pressure between the inside of the piston and the second source of pressure in order to allow selectively the opening of the shut-off means when this drop in pressure exceeds a given threshold.
According to a possible alternative embodiment, the booster of the invention may further include a second air intake path formed by a passage which causes the second chamber to communicate selectively with the second source of pressure through the valve, avoiding passing through the filter, it being possible for this second air intake path itself permanently to pass through the valve and include a section common to the first and second air intake paths, in which section the shut-off means with selective opening are installed.
In the usual case in which the valve is operated by an operating rod, the booster of the invention is preferably designed so that the filter adopts the shape of a cylinder fitted around the operating rod, and so that the shut-off means comprise a valve seat formed at the internal periphery of the piston and a flexible annular seal closing off a gap between the filter and the valve seat, bearing on the latter, and so that the elastic means comprise a spring pressing the seal onto the valve seat, against a force which can be exerted o
REFERENCES:
patent: 3362298 (1968-01-01), Julow
patent: 4632014 (1986-12-01), Endo
patent: 5090294 (1992-02-01), Endou
Gautier Jean Pierre
Verbo Ulysse
Bosch Systems de Freinage
Lopez F. Daniel
McCormick Jr. Leo H.
LandOfFree
Booster equipped with an adaptive-flowrate direct air inlet does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Booster equipped with an adaptive-flowrate direct air inlet, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Booster equipped with an adaptive-flowrate direct air inlet will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1606070