Modified rod guide for cut off shock absorber

Claim 2

In a double direct acting hydraulic shock absorber having a rebound cutoff for controlling the rate of movement of a piston rod with respect to a pressure cylinder the combination comprising: a piston supported within the pressure cylinder to divide it into rebound and compression chambers, means within said piston for controlling fluid flow between said chambers on the opposite sides of said piston, a piston rod connected to said piston including a concentric bore therethrough, a side opening in said piston rod communicating said concentric bore with said rebound chamber, a rod guide including a depending poRtion thereon fitted into the upper end of said pressure cylinder for closing it, said rod guide including an upwardly directed flange thereon defining a seal cavity, a cap for closing the upper end of said seal cavity, a concentric bore through said rod guide including a large diameter entrance portion thereon in communication with said rebound compartment, said rod guide bore further including a smaller diameter bearing surface portion thereon extending from said entrance portion into said seal cavity, said piston rod having the peripheral surface thereof supported by said bearing surface against substantial lateral movement with respect to said pressure cylinder, said entrance portion cooperating with said side opening to produce a first rebound cutoff action, said side opening cooperating with said bearing surface to block flow through said rod at the end of its rebound movement thereby to produce a full rebound cutoff when said piston rod has moved a predetermined distance exteriorly of said pressure cylinder, an annular resilient seal element located within the seal cavity in the upper end thereof, means for spring baising said annular resilient seal element against the outer periphery of said piston rod, a plurality of separate sealing lips on said sealing element to maintain a minumum gripping action on said piston rod during reciprocation thereon into and out of said pressure cylinder, said plurality of sealing lips serving to prevent the escape of hydraulic fluid from said rebound chamber during periods when said rebound chamber is communicated with said compression chamber through said rod, said bearing surface having a lower surface portion and an upper surface portion both located axially outwardly of the upper end of said pressure cylinder, an annular groove located between said upper and lower bearing surface portions and having an inner diameter greater than that of said upper and lower bearing surface portions, said annular groove only communicating with said rebound chamber through a clearance between the outer diameter of said piston rod and the inner diameter of said lower bearing surface portion, said annular groove only communicating with said seal cavity through a clearance between the outer diameter of said piston rod and the inside diameter of said upper bearing surface portion, said annular groove and said clearances between said piston rod and said upper and lower bearing portions preventing fluid trapped between said piston and said rod guide from blowing through said seal cavity and across said multiple lip sealing element upon the occurrence of a maximum predetermined pressure buildup within said rebound chamber which occurs when said rod side opening is completely blocked by said bearing surface.

Claim 3

In a direct double acting hydraulic shock absorber the combination of a pressure cylinder, base valve means communicating one end of said pressure cylinder with a low-pressure reservoir for hydraulic fluid, a rod guide closing the opposite end of said pressure cylinder, a piston located within said pressure cylinder to divide it into first and second variable volume chambers, a piston rod having one end connected to said piston, a concentric bore through said rod guide, the opposite end of said piston rod extending through said concentric bore exteriorly of said pressure cylinder and adapted to be connected to means for reciprocating said piston within said pressure cylinder so as to change the volume of said variable volume chambers on either side thereof, a longitudinal bore through said piston rod, a side opening in said rod communicating said longitudinal bore with one of said chambers, control means within said piston communicating said longitudinal bore with the other of said chambers, said side opening, longitudinal bore and control means defining a serially arranged path for flow of fluid from said first chamber into said second chamber as said piston rod moves exteriorly of said pressure cylinder, said rod guide including a first diameter portiOn thereon defining a bearing surface engageable with said piston rod for supporting it against substantial lateral movement during reciprocation of said piston with respect to said pressure cylinder, said concentric bore further including an entrance bore section from said first chamber for producing a first predetermined rebound cutoff action as said side opening in said rod moves interiorly of said concentric rod guide bore, means defining a seal cavity above said rod guide, a resilient seal element within said cavity encircling said piston rod and being in sealing engagement therewith, said side opening in said rod being blocked by said piston rod bearing surface at the end of a rebound piston rod stroke to cutoff fluid flow through said serially arranged flow path to produce a rapid pressure increase within said first compartment, said bearing surface having a lower surface portion and an upper surface portion both located axially outwardly of the upper end of said pressure cylinder, an annular groove located between said upper and lower bearing surface portions and having an inner diameter greater than that of said upper and lower bearing surface portions, said annular groove only communicating with said rebound chamber through a clearance between the outer diameter of said piston rod and the inner diameter of said lower bearing surface portion, said annular groove only communicating with said seal cavity through a clearance between the outer diameter of said piston rod and the inside diameter of said upper bearing surface portion, said annular groove in said bearing surface and said clearances between said piston rod and said upper and lower bearing portions operative to trap fluid flow along the outer periphery of said piston rod upon the occurrence of a cutoff produced high-pressure level within said first chamber when said side opening is blocked by said bearing surface to prevent high-pressure jet flow of hydraulic flow from said first chamber against said seal element, said side groove and clearance between said piston rod and said bearing surface defining a fluid path for relief of fluid from within said first chamber into said seal cavity during normal shock absorber operation, said resilient sealing element serving to prevent fluid leakage during such normal shock absorber operation.

Claim 4

In a direct double acting hydraulic shock absorber the combination of a pressure cylinder, base valve means communicating one end of said pressure cylinder with a low-pressure reservoir for hydraulic fluid, a rod guide closing the opposite end of said pressure cylinder, a piston located within said pressure cylinder to divide it into first and second variable volume chambers, a piston rod having one end connected to said piston, a concentric bore through said rod guide, the opposite end of said piston rod extending through said concentric bore exteriorly of said pressure cylinder and adapted to be connected to means for reciprocating said piston within said pressure cylinder so as to change the volume of said variable volume chambers on either side thereof, a longitudinal bore through said piston rod, a side opening in said rod communicating said longitudinal bore with one of said chambers, control means within said piston communicating said longitudinal bore with the other of said chambers, said side opening, longitudinal bore and control means defining a serially arranged path for flow of fluid from said first chamber into said second chamber as said piston rod moves exteriorly of said pressure cylinder, said rod guide including a first diameter portiOn thereon defining a bearing surface engageable with said piston rod for supporting it against substantial lateral movement during reciprocation of said piston with respect to said pressure cylinder, said concentric bore further including an entrance bore section from said first chamber for producing a first predetermined rebound cutoff action as said side opening in said rod moves interiorly of said concentric rod guide bore, means defining a seal cavity above said rod guide, a resilient seal element within said cavity encircling said piston rod and being in sealing engagement therewith, said side opening in said rod being blocked by said piston rod bearing surface at the end of a rebound piston rod stroke to cutoff fluid flow through said serially arranged flow path to produce a rapid pressure increase within said first compartment, said bearing surface having a lower surface portion and an upper surface portion both located axially outwardly of the upper end of said pressure cylinder, an annular groove located between said upper and lower bearing surface portions and having an inner diameter greater than that of said upper and lower bearing surface portions, said annular groove only communicating with said rebound chamber through a clearance between the outer diameter of said piston rod and the inner diameter of said lower bearing surface portion, said annular groove only communicating with said seal cavity through a clearance between the outer diameter of said piston rod and the inside diameter of said upper bearing surface portion, said annular groove in said bearing surface and said clearances between said piston rod and said upper and lower bearing portions operative to trap fluid flow along the outer periphery of said piston rod upon the occurrence of a cutoff produced high-pressure level within said first chamber when said side opening is blocked by said bearing surface to prevent high-pressure jet flow of hydraulic flow from said first chamber against said seal element, said side groove and clearance between said piston rod and said bearing surface defining a fluid path for relief of fluid from within said first chamber into said seal cavity during normal shock absorber operation, said resilient sealing element serving to prevent fluid leakage during such normal shock absorber operation.

Claim 5

In a direct acting hydraulic shock absorber the combination of a pressure cylinder, a piston located within said cylinder having the peripheral walls thereof slidably sealingly supported by said pressure cylinder to divide said pressure cylinder into a compression chamber and a rebound chamber, means defining a reservoir communicating with said compression chamber, a piston rod having one end connected to said piston and having the opposite end thereof extending exteriorly of said pressure cylinder through said rebound compartment, a rod guide element closing one end of said pressure cylinder having a concentric bore through which is directed said piston rod, said concentric bore including an entrance portion extending from one end of said rod guide to intersect a smaller diameter bore defining a bearing surface, said bearing surface supportingly engageable with the periphery of said piston rod to control lateral movement thereof during movement of said piston rod into and out of said pressure cylinder, a longitudinal bore through said piston rod, a side opening in said piston rod communicating said longitudinal bore with said rebound chamber, control means within said piston communicating said longitudinal bore with said compression chamber, said side opening, longitudinal bore and said control means being serially communicated to define a path for fluid flow from said rebound compartment into said compression chamber as said piston rod moves exteriorly of said pressure cylinder, a resilient annular seal encircling said piston rod including a plurality of axially spaced lips thereon to seal against fluid leakage from said rebound compartment during low-amplitude movement of said piston rod with respect to said pressure cylinder, said side opening being blocked by said first diameter portion of said bore on a maximum rebound movement of said piston rod to prevent fluid flow from said rebound chamber thereby to cutoff further movement of said piston within said pressure cylinder and to increase the pressure within said rebound chamber, said bearing surface having a lower surface portion and an upper surface portion both located axially outwardly of the upper end of said pressure cylinder, means for sealing against fluid flow during rebound cutoff pressurization of said rebound chamber, said means including an annular groove formed in said smaller diameter portion of said rod guide around said piston rod at a point located between said upper and lower bearing surface portions and having an inner diameter greater than that of said upper and lower bearing surface portions, said annular groove only communicating with said rebound chamber through a clearance between the outer diameter of said piston rod and the inner diameter of said lower bearing surface portion, said annular groove only communicating with said seal cavity through a clearance between the outer diameter of said piston rod and the inside diameter of said upper bearing surface portion, said groove and said clearances between said piston rod and said upper and lower bearing portions preventing high-pressure flow impingement of fluid against said resilient seal element and consequent leakage across said seal.

Claim 6

In a direct acting hydraulic shock absorber the combination of a pressure cylinder, a piston located within said cylinder having the peripheral walls thereof slidably sealingly supported by said pressure cylinder to divide said pressure cylinder into a compression chamber and a rebound chamber, means defining a reservoir communicating with said compression chamber, a piston rod having one end connected to said piston and having the opposite end thereof extending exteriorly of said pressure cylinder through said rebound compartment, a rod guide element closing one end of said pressure cylinder having a concentric bore through which is directed said piston rod, said concentric bore including an entrance portion extending from one end of said rod guide to intersect a smaller diameter bore defining a bearing surface, said bearing surface supportingly engageable with the periphery of said piston rod to control lateral movement thereof during movement of said piston rod into and out of said pressure cylinder, a longitudinal bore through said piston rod, a side opening in said piston rod communicating said longitudinal bore with said rebound chamber, control means within said piston communicating said longitudinal bore with said compression chamber, said side opening, longitudinal bore and said control means being serially communicated to define a path for fluid flow from said rebound compartment into said compression chamber as said piston rod moves exteriorly of said pressure cylinder, a resilient annular seal encircling said piston rod including a plurality of axially spaced lips thereon to seal against fluid leakage from said rebound compartment during low-amplitude movement of said piston rod with respect to said pressure cylinder, said side opening being blocked by said first diameter portion of said bore on a maximum rebound movement of said piston rod to prevent fluid flow from said rebound chamber thereby to cutoff further movement of said piston within said pressure cylinder and to increase the pressure within said rebound chamber, said bearing surface having a lower surface portion and an upper surface portion both located axially outwardly of the upper end of said pressure cylinder, means for sealing against fluid flow during rebound cutoff pressurization of said rebound chamber, said means including an annular groove formed in said smaller diameter portion of said rod guide around said piston rod at a point located between said upper and lower bearing surface portions and having an inner diameter greater than that of said upper and lower bearing surface portions, said annular groove only communicating with said rebound chamber through a clearance between the outer diameter of said piston rod and the inner diameter of said lower bearing surface portion, said annular groove only communicating with said seal cavity through a clearance between the outer diameter of said piston rod and the inside diameter of said upper bearing surface portion, said groove and said clearances between said piston rod and said upper and lower bearing portions preventing high-pressure flow impingement of fluid against said resilient seal element and consequent leakage across said seal.