Motors: expansible chamber type – Working member position feedback to motive fluid control – Follower type
Patent
1996-04-10
1998-07-21
Nguyen, Hoang
Motors: expansible chamber type
Working member position feedback to motive fluid control
Follower type
91376R, F15B 910
Patent
active
057821593
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a pneumatic booster, especially one that can be used for boosting braking in motor vehicles, comprising: a rigid casing divided in leaktight fashion into at least two variable-volume working chambers, the first of which is connected to a first pressure source delivering a first pressure, and the second of which can be connected selectively, by means of a three-way valve, to the first source or to a second pressure source delivering a pressure different from the first; a moving partition separating the two working chambers inside the casing and capable of being urged by a pressure difference established selectively between the two working chambers through the actuation of the three-way valve; a pneumatic piston which can move with the moving partition and which contains the three-way valve, this valve comprising a tubular shutter, a first end of which is selectively applied to a first seat in order selectively to prevent and to allow a flow of air between the second pressure source and the second chamber; an operating rod also housed in the piston, able to move in a first axial direction and controlling the actuation of the three-way valve by means of a plunger capable of moving the first end of the tubular shutter away from the first seat; a push rod which can move in the first axial direction and can receive, in order to transmit it on, an output force oriented in this first axial direction; and reaction means interposed between the operating rod and push rod in order to apply to the operating rod a reaction which increases with the output force.
BACKGROUND OF THE INVENTION
Devices of this type which are well known in the prior art are applied to very many motor vehicles these days to boost braking.
Despite their traditional nature, these devices continue to be the subject of substantial research aimed at optimizing their operating characteristics and especially at reducing their response time without major impact on their cost.
SUMMARY OF THE INVENTION
The specific object of the present invention is to provide a booster which meets these requirements.
To this end, the booster of the invention is essentially characterized in that the shutter has a freedom of movement with respect to the plunger in the first axial direction and is urged elastically against the plunger in a direction which is the opposite of the first axial direction, and in that the first end of the shutter is connected to a mass which can be set in motion by a movement of the plunger in the first axial direction in order to push the first end of the tubular shutter back away from the plunger and thus increase the flow of air between the second pressure source and the second chamber.
Further features and advantages of the invention will emerge clearly from the description thereof given hereafter by way of non-limiting indication with reference to the appended drawings, in which
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic sectional view of a pneumatically boosted braking system using a conventional booster;
FIG. 2 is a sectional part view of a booster known from the patent U.S. Pat. No. 5,233,907, liable to benefit from the characteristics of the invention and given by way of example; and
FIG. 3 is a sectional part view of a detail of the booster of FIG. 2, identified by the reference III of this figure, and modified to incorporate the characteristics of the invention.
DETAILED DESCRIPTION OF THE DRAWINGS
In the traditional fashion, a pneumatically boosted braking system comprises a pneumatic booster 1 and a master cylinder 2.
The booster comprises a rigid casing 3, a moving partition 4, a pneumatic piston 5, a three-way valve 7, an operating rod 10, a push rod 13, and reaction means interposed between the operating rod 10 and push rod 13, for example a reaction disk 12.
The moving partition 4 divides the internal volume of the rigid casing 3 in leaktight fashion into two working chambers 3a and 3b of complementary and variable volume.
The first working chamber 3a is connected to a
REFERENCES:
patent: 4885979 (1989-12-01), Macht et al.
patent: 5176063 (1993-01-01), Levrai et al.
patent: 5214995 (1993-06-01), Gautier
patent: 5493948 (1996-02-01), Gautier et al.
patent: 5601008 (1997-02-01), Miwa et al.
Gautier Jean Pierre
Verbo Ulysse
Bosch Systems de Freinage
Comstock Warren
McCormick Jr. Leo H.
Nguyen Hoang
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