A damper control device feeds back a pressure within an extension-side chamber to control an extension-side solenoid valve that adjusts the pressure within the extension-side chamber, and feeds back a pressure within a compression-side chamber to control a compression-side solenoid valve that adjusts the pressure within the compression-side chamber. The damper control device performs a compression-side reduction correction which reduces a compression-side current supplied to the compression-side solenoid valve during extension of a damper, and performs an extension-side reduction correction which reduces an extension-side current supplied to the extension-side solenoid valve during contraction of the damper.

Disclosed herein are active hydraulic cylinders for use in active vehicle suspension systems, and methods for assembling active hydraulic cylinders for use in an active vehicle suspension system. In particular, in certain embodiments a manifold may encircle a portion of an outer tube of a twin tube assembly. The manifold may mechanically and fluidly couple a pump assembly to the twin tube assembly. In certain embodiments, the manifold may be welded onto the outer tube.

The invention relates to a vehicle seat or to a vehicle cabin having a suspension apparatus comprising a top end part and a bottom end part, which can be deflected relative to the top end part, which are connected to each other in a spring-loaded manner by means of a suspension element, and having a dampening apparatus for dampening vibrations having effect on at least one of the two end parts wherein the dampening apparatus and a distance leveling apparatus for adjusting a distance between the top end part and the bottom end part have an actuator fluid element controlled by common pressure stages.

The suspension comprises a mechanical spring interposed between an unsprung mass (UM) and a sprung mass (SM) of the vehicle, a shock-absorber interposed between the unsprung mass (UM) and the sprung mass (SM), in parallel with the mechanical spring, a hydraulic linear actuator, an accumulator, a tank (T) containing an incompressible working fluid and a hydraulic circuit for hydraulically connecting, the hydraulic linear actuator, the accumulator and the tank (T) with each other. A single reversible pump (P) is arranged along the third hydraulic line. A reversible electric motor (M) drives the pump (P) in either direction, and a plurality of valves (V.sub.1, V.sub.2, V.sub.3, V.sub.4, V.sub.5, V.sub.S) control the flow of the working fluid between the accumulator, the tank (T) and the hydraulic linear actuator.

An active suspension system 1 for a vehicle. The suspension system 1 comprises a hydraulic actuator 4 for connection to the vehicle, an accumulator 30 arranged to provide fluid to the actuator 4 and a spool valve 16. The spool valve 16 comprises a spool 18 mounted for movement between a first position in which the flow of fluid from the accumulator 30 to the actuator 4 is prevented and a second position in which fluid can flow from the accumulator 30 to the actuator 4 via the spool 18 thereby causing movement of the actuator 4.

A vehicle height adjustment device includes a cylinder, a piston, a rod, a spring, an adjustor, a storage chamber, and a passage switch unit. The piston divides a space inside the cylinder. The rod has one end in the axial direction holding the piston and has the other end supported at a vehicle wheel side. The spring has one end in the axial direction supported at the body side and has the other end supported at the wheel side. The adjustor includes an accommodation chamber of fluid and supports the one end of the spring to adjust a length of the spring in accordance with an amount of the fluid in the accommodation chamber. The passage switch unit closes an opening of the cylinder and includes first and second communication passages to switch a passage for the fluid in accordance with a movement of the piston.

A hydraulic suspension system for a motor vehicle having at least a pair of road engaging wheels. The suspension system includes, a hydraulic cylinder coupled with the each of the pair of road engaging wheels, the hydraulic cylinder defining a cap end volume and a rod end volume separated by a piston. A hydraulic supply circuit for the hydraulic cylinder includes, a high pressure hydraulic source, a low pressure hydraulic drain, a pair of hydraulic sub circuits each coupled to one of the hydraulic cylinder cap and rod end volumes. Each hydraulic sub circuit includes, a proportional supply flow valve coupled with the high pressure hydraulic source and one of the cylinder volumes, a return flow control proportional valve coupled with the low pressure hydraulic drain and the one cylinder volume, and an accumulator coupled to the associated hydraulic cylinder volume through an accumulator fill control proportional valve.

A vehicle and a height adjustment system for the vehicle are disclosed. A valve includes a member movable between a first position operating first and second piston mechanisms to raise an end of the vehicle to a first height, a second position operating the first and second piston mechanisms to lower the end of the vehicle to a second height and a third position maintaining the end of the vehicle at one of the first height and the second height. A first fluid line extends between the first piston mechanism and the valve to fluidly connect the first piston mechanism and the valve. Additionally, a second fluid line extends between the second piston mechanism and the valve to fluidly connect the second piston mechanism and the valve. The first fluid line and the second fluid line are fluidly connected to the valve independently of each other.

A control valve device for a regulation of damping characteristics, in particular of shock absorbers, includes a valve slide and a hydraulic fail-safe unit which is configured, in a de-energized operation state, to provide a fail-safe damping characteristic of the valve slide, the damping hardness of which in a rebound direction lies between a minimally possible rebound damping hardness and a maximally possible rebound damping hardness, and the damping hardness of which in a compression direction lies between a minimally possible compression damping hardness and a maximally possible compression damping hardness.

The suspension includes a hydraulic actuator and a supply hydraulic circuit connected to the hydraulic actuator to supply a compression chamber and an extension chamber of the hydraulic actuator with a working fluid. The supply hydraulic circuit includes a hydraulic pump, a high-pressure line connected to a delivery port of the hydraulic pump, a low-pressure line connected to a suction port of the hydraulic pump, and a flow control valve connected on one side to the compression chamber and extension chamber of the hydraulic actuator and on the other side to the high-pressure line and low-pressure line. The flow control valve is a rotary spool valve having comprising a spool which is rotatable continuously between a plurality of operating positions.