Shock absorber with pressure-controlled damping
A damper includes a pressure-sensitive damping control circuit that selectively permits fluid flow from a first chamber to a second chamber. A piston varies a volume of the first chamber. A blow-off piston is movable between a closed position, wherein fluid flow through the control circuit is substantially prevented, and an open position, wherein fluid flow through the control circuit is permitted. The damper also includes a first source of pressure. A fluid pressure created by compression of the damper applies an opening force to the blow-off piston moving the blow-off piston in a direction toward the open position against a resistance force provided by the first source of pressure. The resistance force exceeds the opening force until the pressure created by forces tending to insert the piston rod into the first fluid chamber exceeds the pressure in the first source of pressure by a predetermined amount.
1. A pressure-sensitive damper, comprising:
a first cylinder at least partially defining a first fluid chamber, said first fluid chamber containing a damping fluid;
a damping piston for reciprocal motion within said first cylinder;
a piston rod comprising:
a first end connected to said damping piston; and
a second end extending through an end of said first cylinder;
a second cylinder at least partially defining a second fluid chamber in fluid communication with said first cylinder;
a compression damping plate fixed in said second cylinder;
at least one passage in said compression damping plate through which said damping fluid, which is displaced by a movement of said piston rod, flows in a first direction from said first fluid chamber to said second fluid chamber to achieve a first fluid flow;
a gas chamber in communication with said second fluid chamber;
a valve for generating a resistance force to said first fluid flow, wherein said resistance force varies according to an amount of force communicated to said valve by said gas chamber, wherein said valve comprises:
a blow-off piston having a first position in engagement with said at least one passage and a second position removed from said at least one passage;
an intensifier piston comprising:
a first end; and
a second end, wherein a pressure within said gas chamber generates a force on said first end of said intensifier piston and generates an intensified pressure at said second end of said intensifier piston, wherein said intensified pressure is communicated to said blow-off piston to create a first force urging said blow-off piston toward said first position; and
an intermediate chamber, wherein a pressure within said intermediate chamber acts on said intensifier piston, said pressure within said intermediate chamber providing force on said second end of said intensifier piston tending to counteract an amount of said force generated on said first end of said intensifier piston by said pressure within said gas chamber.
2. The pressure-sensitive damper of claim 1 , further comprising:
a by-pass circuit adapted to permit a flow of said damping fluid in said first direction through said compression damping plate without passing through said at least one passage.
3. The pressure-sensitive damper of claim 1 , wherein said pressure within said gas chamber is adjustable.
4. The pressure-sensitive damper of claim 1 , wherein said pressure within said intermediate chamber is adjustable.
5. The pressure-sensitive damper of claim 1 , wherein said gas chamber comprises:
a pressurized, compressible chamber containing compressible fluid.
6. The pressure-sensitive damper of claim 1 , further comprising:
an adjustment mechanism, said adjustment mechanism configured to adjust a pressurization force applied to said intermediate chamber by said intensifier piston, said adjustment mechanism comprising:
an annular chamber with externally-adjustable volume.
7. The pressure-sensitive damper of claim 1 , wherein said blow-off piston is movable in an axial direction between said first position and said second position.