End-stop control valves for providing progessive damping forces in vibration dampers

An end-stop control valve comprising:

• a piston that is configured to move longitudinally within a damper tube, wherein an entirety of the piston is radially spaced apart from an inner wall of the damper tube such that hydraulic fluid can flow around the piston when the piston is not engaged with a catch piston, the piston including:
• passages that extend from a first longitudinal side of the piston to a second longitudinal side of the piston, and
• a valve seat disposed at the second longitudinal side of the piston;
• a valve disc stack-up that covers the passages at the second longitudinal side of the piston, wherein a radially outer portion of the valve disc stack-up is supported on the valve seat of the piston;
• the catch piston with which the piston is configured to engage during an end-of-stroke damping event, the catch piston being movable longitudinally within the damper tube and being disposed on the inner wall of the damper tube;
• a piston band that is disposed on the piston and at least partially surrounds the piston, wherein the piston band is configured to engage the catch piston during the end-of-stroke damping event,
• wherein the piston and the catch piston are configured such that prior to engagement of a contact surface of the piston with a contact surface of the catch piston during the end-of-stroke damping event, a pocket for hydraulic fluid that extends annularly is formed longitudinally between the contact surface of the piston and the contact surface of the catch piston and radially between a first segment of the piston and a sidewall of the catch piston.

A vibration damper comprising:

• a damper tube that extends along a longitudinal axis and includes an inner wall;
• a piston rod that extends into the damper tube and is configured to move longitudinally within the damper tube;
• a main piston secured on the piston rod that separates the damper tube into a first working chamber and a second working chamber;
• an end-stop control valve disposed on a longitudinal side of the main piston, either in the first working chamber or in the second working chamber, the end-stop control valve comprising:
• a piston that is secured on the piston rod and is configured to move longitudinally within the damper tube, wherein a radially outermost portion of the piston is spaced radially apart from the inner wall of the damper tube such that hydraulic fluid can flow between the piston and the inner wall of the damper tube outside of an end-of-stroke damping event,
• a valve disc stack-up disposed longitudinally alongside the piston, the valve disc stack-up also being secured on the piston rod,
• a catch piston with which the piston is configured to engage during the end-of-stroke damping event, the catch piston being disposed on the inner wall of the damper tube in a longitudinally movable manner, wherein the piston and the catch piston are configured such that as a contact surface of the piston approaches a contact surface of the catch piston during the end-of-stroke damping event, a pocket for hydraulic fluid is formed longitudinally and radially between the piston and the catch piston, and
• a spring disc that is secured on the piston rod and is configured to move longitudinally within the damper tube with the piston and the piston rod, wherein as the end-of-stroke damping event begins the spring disc is configured to engage a valve seat of the catch piston before the contact surface of the piston engages the contact surface of the catch piston.