Seat for automotive vehicles

Claim 1

A hydraulic pneumatic seat support for vehicles, comprising a telescopic shortenable support comprising a hydraulic cylinder with a support piston, and a pressure chamber in the hydraulic cylinder containing a hydraulic fluid the volume of which is variable, an auxiliary cylinder operatively communicating with said pressure chamber of said hydraulic cylinder, an auxiliary piston slidably disposed in said auxiliary cylinder, a screw spindle abuttingly connected to said auxiliary piston for mechanically and forcibly shifting said auxiliary piston, a hydraulic accumulator having an entrance side in front thereof operatively communicating with said pressure chamber of said hydraulic cylinder, a cylindrical housing and formed with an inwardly directed annular wall constituting a valve abutment, a return valve including a plate having central bore and having a diameter smaller than that of said cylindrical housing and movably disposed therein with a front side thereof adjacent said valve abutment and arranged at said entrance side of said hydraulic accumulator and said central bore and the space between the periphery of said plate and said cylindrical housing forming throttles defining two different sizes cross sections operatively disposed so that when said support piston is shifted in said hydraulic cylinder so as to reduce the volume of said pressure chamber, there is caused a movement of said plate away from said valve abutment and a streaming thereby opening the larger of said throttle cross sections constituting said space between said periphery of said plate and said cylindrical housing which then communicates said hydraulic accumulator with said hydraulic cylinder, and when said support piston return shifts so as to increase the volume of said pressure chamber, said plate is moved against said valve abutment thereby causing a streaming opening the smaller of said throttle cross sections, the latter constituting said central bore, a sleeve member having a longitudinal opening therein and disposed in said housing spaced from the wall of said housing and having an abutment surface adjacent the rear side of sAid plate, spring means biasing said plate toward said valve abutment, and said sleeve member having a bore through its wall which is substantially smaller than said longitudinal opening, whereby when said support piston is shifted with a predetermined pressure in said hydraulic cylinder reducing the volume of said pressure chamber, there is caused a movement of said plate against said abutment surface causing a streaming through said space between said periphery of said plate and said bore through said wall of said sleeve, as well as through a second path constituting said central bore of said plate and said longitudinal opening of said sleeve, said central bore communicating with said longitudinal opening.