Motors: expansible chamber type – Working member position feedback to motive fluid control – Follower type
Patent
1993-10-08
1996-01-30
Lopez, F. Daniel
Motors: expansible chamber type
Working member position feedback to motive fluid control
Follower type
F15B 910
Patent
active
054873258
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to a brake servo booster, primarily for use in providing power assistance in the actuation of a brake master cylinder of a vehicle hydraulic braking system capable of operating in a traction control mode, the booster being of the general kind in which the supply of air to a servo piston, usually in the form of a diaphragm assembly, is controlled by a valve mechanism which includes a reciprocable valve element operatively connected to a force input member actuated by a driver-operated control.
For the traction control mode, the booster is actuated automatically to apply the brakes without intervention by the driver and the connection between the force input member and the booster valve element must be such as to allow this to happen without significantly affecting the position of the brake pedal. An object of the invention is to provide a simple and convenient form of connection for this purpose.
According to the invention, the force input member of a booster includes two parts of which a first one is connected, in use, to the driver-operated control, and the second one to the valve element, the arrangement being such that operating force applied to the control member is transmitted through both of said first and second parts of the input member to the valve element, whilst operation of the booster in the traction control mode is permitted by the second part of the force input member moving relative to the first part.
In a preferred arrangement, the first and second parts of the force input member are telescoped together with one of the parts slidingly housed within a bore of the other part.
Typically, the valve element is housed within a hub connected to the servo piston, and the hub carries abutment means which engages a housing part of the booster to set the retracted position of the first part of the input member and thereby of the control member.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described, by way of example, with reference to the accompanying drawings in which:
FIG. 1 is a side view, partly in longitudinal cross-section, illustrating part of one form of the booster of the invention;
FIG. 2 is a view in longitudinal cross-section of part of the brake servo booster of FIG. 1 in a first operative condition; and
FIG. 3 is a view similar to FIG. 2 illustrating the booster in an alternative operative condition and in a traction control mode.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1 of the drawings, there is illustrated therein part of a brake servo booster of the invention having a housing 100 composed of a pair of shells 200 and 300 joined together at 400 in fluid-tight manner. The interior of the housing is divided by a diaphragm assembly 500 into two chambers A and B, the diaphragm assembly being carried by a hub 600 which would normally be urged by a return spring 700 to the right, as seen in the drawing. The hub 600 acts upon a force output rod 800 arranged to actuate a master cylinder (not shown) in conventional manner. The action of the rod is controlled by an arrangement of valves contained within a housing portion 900 of the booster and operated by a force input rod 5 connected to a driver-operated pedal (not shown).
As can be seen from FIGS. 2 and 3, the hub 600 contains a valve control piston 3 which is allowed limited axial movement within the hub and to which is crimped, or otherwise secured a ball end 4 of the force input rod. A reaction disc 6 is interposed between the left hand end of the piston 3 and the force output rod 800. The extreme right hand end portion of the piston 3 forms a valve seat 3A and the hub 2 forms a further valve seat 2A, both seats being arranged to cooperate with a popper valve assembly 7, in conventional manner. Part of the hub 2 is surrounded in spaced relationship by a relatively thin gauge sleeve 8 of which a closed end 9 lies beyond the right hand end of the hub 2 and is engaged by a flange 12B of the rod part 12. The opposite end of the sleeve is formed
REFERENCES:
patent: 3175235 (1965-03-01), Randol
patent: 3719123 (1973-03-01), Cripe
patent: 5096268 (1992-03-01), Schiel et al.
Bayliss John P.
Byrnes Sean
Lopez F. Daniel
Lucas Industries
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