Patent ID: 6070950
Filing Date: 2000-06-06
Classification: B60T

Abstract:
A braking valve for interposition between a source of hydraulic pressure and a brake circuit of an automobile vehicle and comprising:a housing provided with a least one bore;a hydraulic piston sliding in said bore and defining therein first and second pressure chambers sealed from each other by means of an elastic annular seal surrounding said piston said first and second pressure chambers being capable of communicating selectively with each other through a one way valve installed in a passage in said piston, said first and second chambers being connected in use respectively to the source of hydraulic pressure and to the brake circuit; anda tappet acting on the one way valve in a direction such as to enable it to open when a relatively low pressure exists in said second chamber, whereas said piston slides axially in said bore under the influence of an increase in pressure in said second chamber in a direction such as to enable said one way valve to close, characterised: in that said annular seal is fitted without axial clearance in a groove which is formed in said piston, said annular seal comprising a first bearing surface having a first circular ring shape on a side adjacent said first chamber, a second bearing surface having a second circular ring shape on a side adjacent said second chamber, and a cylindrical bottom surface connecting said first and second bearing surfaces, said groove thus presenting a rectangular cross section; and in that said seal presents a circumference which is at least partially cylindrical and which makes contact between said seal and said bore; in that said seal presents an annular zone which has a circular ring shape facing said second bearing surface by means of which said seal lies flat on the second bearing surface; in that said seal presents at least relative to said first bearing surface and to said cylindrical bottom surface recesses communicating with said first chamber to enable any pressure existing in said first chamber to deform said seal radially by urging in that said seal against said bore, said seal being symmetrical relative to a medium plane; and in that said first and second bearing surfaces of said groove have different external radiuses and in that said annular zone presents an internal radius which is greater than an external radius of said first bearing surface and less than an external radius of said second bearing surface.