US 4,886,085 AGranted

Vacuum check valve and method of control

AssigneeGeneral Motors Corporation

InventorJames W. Miller

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Abstract

A value opening air flow control ring requires the poppet to travel a controlled distance off the poppet seat to obtain substantially unrestricted air flow, the restricted flow occurring during air flow pulsations which acts to inhibit valve pulsations and resulting valve noises generated by pulsations from the vacuum source. The control ring also causes directional air flow past the poppet, particularly in the early part of the valve opening sequence while the restricted flow is occurring, causing a side bias on the poppet which decreases as the poppet moves toward its fully open position, the side bias being substantially eliminated by the time the poppet reaches its fully open position. The side bias action is reversed in the valve closing movement from the fully open position. The side bias further inhibits valve pulsations which might otherwise occur as the valve tends to move from the closed position to the open position and vice versa in response to vacuum source air flow pulsations.

In a vacuum check valve assembly for a vacuum powered brake booster having:

a housing having a valve chamber formed therein, an inlet opening adapted to be connected to a vacuum powered brake booster, an outlet opening adapted to be connected to a source of vacuum pressure;
and a check valve in said valve chamber having a normal closed position preventing vacuum communication between said outlet opening and said inlet opening and an open position permitting vacuum communication between said outlet opening and said inlet opening;
said check valve having an axially guided disc including a disc body having a center and an annular rubberlike valve portion on the outer peripheral part of said disc body which sealingly engages said housing when said valve is in the normal closed position and is spaced from said housing to permit air to flow therepast when said valve is in the open position;
the improvement comprising;
an air flow control ring positioned radially outward of at least an axially extending part of the outer periphery of said rubberlike valve portion and extending from the housing surface sealingly engaged by said annular rubberlike valve portion when said valve in the normal closed position so that restricted air flow between said ring and said valve portion outer periphery occurs as said disc body and said valve portion move in the valve opening direction for a predetermined initial distance, said ring axially terminating so that substantially unrestricted air flow is permitted between said housing and said valve portion as said valve approaches the fully open position;
said ring and said valve portion permitting radially directed increased air flow therebetween primarily at a selected circumferential location of said ring and said valve portion during the valve initial opening stages, said radially directed air flow circumferential location expanding circumferentially and the directed air flow therefore decreasing relative to the air flow around the other circumferential locations of said valve portion toward said outlet as the air flow becomes less restricted with additional valve opening movement until substantially unrestricted air flow occurs, said directed air flow then being substantially dissipated, said restrictive air flow during the initial valve opening stages inhibiting valve pulsations which may otherwise occur as the vacuum source air pulsation cycling frequency and force tends to excite said valve in a pulsating manner.

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Abstract

Claims7