A hydraulic damper assembly comprises a housing defining a fluid chamber. A piston is slidably disposed in the fluid chamber dividing the fluid chamber into a compression and a rebound chamber. A piston rod couples to the piston for movement between a compression and a rebound stroke. The piston has a compression surface and a rebound surface. The piston defines at least one compression channel, at least one rebound channel, and at least one additional channel. A compression valve covers the at least one compression channel. A rebound valve covers the at least one rebound channel. A proportional bleeding system located between the compression valve and the piston to establish a bleeding flow passage between the at least one rebound chamber and the at least one additional channel for reducing operation harshness of the hydraulic damper assembly. A piston for the hydraulic damper assembly is also disclosed herein.

A shock absorber includes: a shock absorber main body that has an outer tube and a rod movably inserted into the outer tube and can extend and contract; a main passage and a sub passage that communicate in parallel two working chambers provided in the shock absorber main body; a main damping force generation element provided in the main passage; and a sub damping force generation element provided in the sub passage. The main damping force generation element has only a main valve that opens and closes the main passage. The sub damping force generation element has an orifice provided in series with the sub passage, and a sub valve that opens and closes the sub passage and has a valve opening pressure lower than that of the main valve.

The hydraulic shock absorber includes: a first cylinder containing fluid; a piston body including extension-side oil paths permitting flow of oil along with relative movement of the piston rod in the axial direction of the first cylinder; and an extension-side damping valve configured to open and close the extension-side oil paths of the piston body. The extension-side damping valve includes: a valve plate configured to close the extension-side oil paths by covering them and open them by deforming under pressure of oil; and a preload member configured to apply a preload to the valve plate. The preload member includes: a ring-shaped portion; and axis alignment portions configured to protrude from an outer periphery of the ring-shaped portion and contact the piston body to thereby perform axis alignment.

A shock absorber including a piston (3) slidably fitted in a cylinder having hydraulic oil sealed therein. A flow of hydraulic oil, induced in a passage (10) and a sub-passage (29) by sliding movement of the piston in the cylinder in response to the stroke of a piston rod, is controlled by an extension main valve (14) and a compression sub-valve (15) incorporated in the extension main valve, thereby generating a damping force. The amount of deflection of a sub-disk (30) constituting the compression sub-valve when the sub-disk is opened is limited by restricting portions (21). The sub-disk is provided with communicating holes (31) to reduce a differential pressure acting on the sub-disk when opened and also to relax the concentration of stress in the sub-disk, thereby improving the durability of the sub-disk.

A shock absorber for a vehicle includes a pressure tube that defines a fluid chamber and a piston disposed within the fluid chamber. The piston divides the fluid chamber into an upper working chamber and a lower working chamber, and defines a compression passage and a rebound passage. A valve disc assembly of the shock absorber engages the piston and controls the flow of fluid between the upper and lower working chambers. The valve disc assembly includes a check disc and an orifice disc. The check disc is disposed between the piston and the orifice disc. The orifice disc defines an orifice, and the check disc prohibits the flow of fluid through the orifice as the fluid flows in a first direction and permits the flow of fluid through the orifice as the fluid flows in a second direction opposite of the first direction.

A method for operating a controllable shock absorber may involve damping movement of a valve body by loading the valve body with a back pressure on an outflow side. Further, the controllable shock absorber may include a cylinder tube, a piston within the cylinder tube that divides the cylinder tube into two working spaces and includes a couple fluid leadthroughs connecting the working spaces, and first and second valve assemblies for damping piston movement in first and second actuating directions that are disposed on the leadthroughs. Each valve assembly may have a pilot control chamber and a valve plate that is either seated on or spaced apart from a valve seat in closed and open valve positions. Each valve plate can be prestressed closed by pressure loading the pilot control chamber. The pressures of the pilot control chambers can be set by a pilot control valve that comprises a movable valve body. As a result, an outflow cross section between the pilot control chambers and the working spaces can be set. The valve body may be loaded on an outflow side with a back pressure, as a result of which movement of the valve body is damped.”

An electronically controlled internal damper includes: a main passage formed by a working fluid flowing through a main piston; a pilot passage formed by a working fluid as much as a predetermined amount discharged from a first pilot chamber and a second pilot chamber so as to maintain internal pressures of the first pilot chamber and the second pilot chamber to a predetermined level when pressures of the first pilot chamber and the second pilot chamber are increased beyond the predetermined level; and a bypass passage formed by a working fluid passing through the compression retainer and the rebound retainer symmetrically disposed above and under the main piston and a plurality of holes formed transversely to a vertical length direction of a spool rod. Accordingly, the electronically controlled internal damper is capable of implementing damping performance in both a soft mode and a hard mode with a relatively simple structure and increasing sealing performance while reducing rigidity.

A shock absorber according to the present invention includes: a cylinder; a rod movably inserted into the cylinder; an extension side chamber (operation chamber) and a compression side chamber (operation chamber) provided in the cylinder; a valve disc that is provided to be movable in the axial direction on the outer circumference of the rod and has an annular valve seat and a port which is opened on the inner circumference of the annular valve seat and causes the extension side chamber (operation chamber) and the compression side chamber (operation chamber) to communicate with each other; and an annular leaf valve that opens and closes the port.

A damping valve for a vibration damper includes a damping valve body with separate passage channels. The outlet orifices of the passage channels for a flow direction are connected to one another via a groove, which is covered by at least one valve disk and is bounded radially by at least one annular web on the radially inner side with respect to the center axis (A) of the damping valve and at least one annular web on the radially outer side with respect to the center axis (A) of the damping valve. The radially outer web has at least one first portion in which the support is configured as area support for the valve disk, and the radially outer web has at least one second portion in which the support is configured as line support for the valve disk.

Provided is a shock absorber for a railway vehicle, in which an eccentric disk is disposed on a rear surface of a valve disk to set a supporting force for an initial opening position of the valve disk to a relatively low value and continuously open the valve disk from the initial opening position of the valve disk during strokes, thereby controlling a damping force in a low speed section and realizing a soft damping force.