Hydropneumatic suspension and damping devices having level regulation for use in motor vehicles

Claim 1

In a hydraulic pneumatic suspension and damping device for leveling a vehicle the combination comprising; means adapted to be connected to a sprung mass, means adapted to be connected to an unsprung mass; and elongated hollow piston rod having one end connected to one of said means and the opposite end connected to a piston; means defining a low-pressure hydraulic reservoir in direct communication with the interior of said hollow piston rod, a damper tube located in spaced surrounding telescoping relationship with said piston rod and supportingly receiving said piston for reciprocation therein, means defining a first gas spring in surrounding relationship to said damper tube, means defining a hydraulic fluid regulating space around said first gas spring in communication with said damper tube at one end of said piston; flow through apertures in said piston communicating said damper tube on opposite ends of said piston; means including said piston rod for defining a damper space therebetween; means for defining a second gas spring aground said damper tube; means defining a high-pressure reservoir for hydraulic fluid around said second gas spring, first one way check valve means communicating said damper space with said high-pressure reservoir; first aperture means defining a restricted fluid path between said high-pressure reservoir and said damper space; a first slide valve concentrically disposed around said piston rod at one end thereof; a first control spring for biasing said first slide valve in a direction to close said one way check valve means and to open said aperture means; a damping control spring surrounding said piston rod having one end thereof supported on said first slide valve for moving it in opposition to the biasing action of said first control spring; means including a second one way check valve and a bore for communicating said low-pressure reservoir with said damper space for drawing hydraulic fluid from said low-pressure reservoir into said damper space during normal road movements when said piston is in a predetermined midposition within said damper tube wherein the sprung and unsprung masseS are at a desired height relationship; a second slide valve concentrically disposed around said piston rod adjacent said piston; means on said second valve in engagement with the opposite end of said damping control spring; second aperture means through said piston rod communicating said low-pressure reservoir with said damper space normally closed by said second slide valve when the sprung and unsprung masses are at a desired height relationship; a second control spring in engagement with said second slide valve and operative in response to unloading of the vehicle to cause said second slide valve to be shifted by said damping control spring in a direction to block unrestricted flow through said bore between said damper space and said lowpressure reservoir and to open said second aperture means for causing flow of hydraulic fluid into said low-pressure reservoir to return said piston to the midposition; said first slide valve control spring and said damping control spring cooperating when the vehicle is loaded to cause said first slide valve to move to close said first one way check valve and to communicate said damper space with said high-pressure space through said first aperture means for slowly bleeding hydraulic fluid from said high-pressure reservoir into said damper space, across said damper piston and into said hydraulic fluid regulating space to cause the pressure on said damper piston to shift to return it to the midposition within said damper tube.