Pneumatic servomotor with dynamically variable mechanical reacti

Details Pneumatic servomotor with dynamically variable mechanical reacti Pneumatic servomotor with dynamically variable mechanical reacti

1999-02-26

2000-08-29

Lopez, F. Daniel

Motors: expansible chamber type

Working member position feedback to motive fluid control

Follower type

F15B 902

Patent

active

061091634

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to a pneumatic brake booster.
More specifically, the invention relates to a booster comprising: a rigid casing; a moving partition delimiting, in leaktight fashion, a front chamber and a rear chamber inside the casing, the front chamber in operation being connected to a first source of pressure delivering a first pressure; a pneumatic piston slidably mounted in an opening of the casing and moving with the moving partition; a three-way valve housed in the pneumatic piston and capable selectively of adopting a state of rest and an actuating state, in which states the rear chamber is respectively connected to the first source of pressure and to a second source of pressure which delivers a second pressure which, relative to the first pressure, has a difference capable of making a boost force acting in a first axial direction appear on the moving partition; a plunger housed in the pneumatic piston and able to move between a first and a second extreme position, for which positions the first valve is respectively in its state of rest and in its actuating state; an operating rod capable of receiving an input force acting in the first axial direction in order to move the plunger between its first and its second extreme positions; a push rod capable of transmitting at least part of the input and boost forces; and reaction means inserted between the plunger and the push rod for exerting on the plunger, against the action of the input force, a reaction which increases with the boost force, these reaction means comprising a first, a second and a third bearing face and a number of balls trapped between these three bearing faces, the first bearing face consisting of a projecting and at least partially conical surface of the plunger, the second bearing face consisting of a re-entrant and at least partially conical surface of the piston, and the third bearing face consisting of a surface which is at least partially perpendicular to the first axial direction of a plate secured to the push rod.
Devices of this type are known from the prior art, as illustrated, for example, by patents FR-1,515,403, U.S. Pat. No. 3,470,697, and FR-2,030,679.
Current research into improving braking in emergency situations has led to renewed interest in these devices in the public domain, that the invention sets out to improve with a view to allowing a decrease in the reaction force as a function of the rate of actuation of the brake.
To this end, the booster of the invention is essentially characterized in that the first bearing face has at least a first and a second slope, the second of which follows on from the first in a second axial direction which is the opposite of the first axial direction, and in that the first and second slopes make, with the second axial direction, a first and a second respective angle which are different and non-zero, the second of which is smaller than the first.
Thanks to these features, the reaction that the booster puts up against the input force actuating it adopts an intensity which depends on the rate of actuation of the brake.
The booster of the invention may further comprise an elastic washer, the axial bulk of which is all the smaller, the higher the crushing force to which it is subjected, this washer being inserted between the pneumatic piston and the push rod so as to form between the second and third bearing faces a space which decreases as the boost force increases.
Thanks to these features, the booster of the invention may have a response curve similar to that of current boosters, which use an elastomer disc by way of reaction member.
Other 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:
FIG. 1 is a sectional view of a known booster of the prior art (FR-1,515,403);
FIG. 2 is a sectional view of the front part of the plunger of a booster in accordance with the invention;
FIG. 3 is a perspective view of the front part of the plunger o

REFERENCES:
patent: 3470697 (1969-10-01), Pech et al.

Affiliated with

Also associated with

Rating

Pneumatic servomotor with dynamically variable mechanical reacti does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Pneumatic servomotor with dynamically variable mechanical reacti, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pneumatic servomotor with dynamically variable mechanical reacti will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1237668