Active suspension actuator with real time damping

#The present invention relates generally to an active suspension system for a vehicle. In particular, the present invention is concerned with an electrically controlled hydraulic actuator used to mount a vehicle road wheel assembly. The actuator actively controls the plane of the vehicle and concurrently provides real time damping of the wheel assembly.

#Electrically controlled hydraulic dampers (shock absorbers and struts) for vehicular suspension systems are well-known. Many controllable shock absorbers utilize an electric solenoid or motor-driven member to select different damping characteristics. Various designs have been disclosed which provided real time damping of a wheel assembly.

#Hydraulic actuators for active ride control are utilized to control the body attitude of a vehicle. In many systems, an electric controller sends fluid to or receives fluid from a pressurized actuator to resist compression and perform rebound.

#FIGS. 1A and 1B are a longitudinal sectional view of a preferred embodiment of the present hydraulic actuator mounted between a schematically illustrated vehicle body and a partially illustrated suspension control arm.

#FIG. 2 is an exploded elevational view of a piston and rod subassembly removed from the actuator of FIG. 1 for purposes of clarity of illustration.

#A hydraulic actuator is indicated generally at 10 in FIGS. 1A and 1B. The actuator 10 is an assembly including a piston and rod subassembly 12, a piston tube subassembly 14, a body subassembly 16 and a solenoid valve subassembly 18. The actuator 10 is designed for use in a vehicular suspension system and is supplied with hydraulic fluid from a pressurized source, e.g., a hydraulic accumulator 19.

#The piston and rod subassembly 12, removed from the actuator 10 for purposes of clarity of illustration in FIG. 2, includes a hollow piston rod 20 having a damping piston 22 mounted to an externally threaded neck 24 at the lower end of the piston rod 20. The damping piston 22 is a generally cylindrical member having a stepped central bore. A large diameter portion 26 (FIG. 1B) of the central bore includes internal threads for receiving the threaded neck 24 of the piston rod 20. An annular seat 28 is formed at the intersection of the large diameter portion 26 with an intermediate diameter portion 30 of the central bore. A lower end surface of the piston rod 20 rests on the seat 28 when the damping piston 22 is threaded to the piston rod 20. A central passage 32 in the neck 24 provides a fluid path between the interior of the hollow piston rod 20 and the intermediate diameter portion 30 of the central bore. A transfer port 34 is formed as a slot or groove on an outer circumference of the damping piston 22 terminating in a radial channel to provide a fluid path from the intermediate diameter portion 30 to an area surrounding the damping piston 22.

#A compression control channel 36 is formed in the damping piston 22 between the transfer port 34 and an upper end surface of the damping piston 22. An intake valve disc 38 and associated intake valve spring 40 are concentrically mounted about the neck 24 of the piston rod 20 and control fluid flow through the compression control channel 36 as described below.