# US 4,397,452 A · Hydro-mechanical stop for a shock absorber

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- Number: US 4,397,452 A
- Document ID: US4397452A
- Status: Granted
- Kind: A
- Application number: 06/211,485
- Filed: 1980-11-28
- Granted: 1983-08-09
- Earliest claimed: 1980-11-28
- Assignees: Ford Motor Company
- Inventors: Norman G. Fouts
- Web page: https://patentgrep.com/patent/US4397452A

## CPC

- F16F 9/062: {Bi-tubular units}
- F16F 9/49: Stops limiting fluid passage, e.g. hydraulic stops {or elastomeric elements inside the cylinder which contribute to changes in fluid damping (fluid-actuated displacement devices with means for accelerating or decelerating the stroke F15B15/22)}
- F16F: SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION

## Abstract

A hydro-mechanical compression and rebound stop 22 for a suspension strut 10 in which a tubular sleeve 30 is coaxially mounted about a piston rod 18 and is positioned by a coil spring 26 which has its other end seated against a fixed annular seat 24. An abutment ring 50 engages the bottom end of the sleeve 30 to force the sleeve through the annular seat 24 against the bias of the spring and to cause a hydraulic restricted hydraulic flow therethrough. Upon rebound, the abutment ring 50 compresses an elastomeric sleeve 48 against a rod guide 43 at the top end of the working cylinder 12.

## Claims

### Claim 1

A hydraulic shock absorber characterized by:
a working cylinder;
a piston rod and a piston mounted thereon sized to be slideably received within said working cylinder and dividing said cylinder into jounce and rebound chambers;
an end closure closng one end of said working cylinder and having an opening to slideably receive said piston rod;
said piston having flow control means constructed to provide a restrictive fluid passage for the controlled flow of hydraulic fluid from one of said chambers to the other of said chambers when said piston is moved in said working cylinder to thereby create a dampening force;
an annular member coaxially mounted about said piston rod within said working cylinder;
said annular member having a flow control means constructed to provide a restricted fluid passage for the controlled flow of hydraulic fluid therethrough;
said annular member, working cylinder and said end closure defining an annular variable size compression stop chamber above said rebound chamber; and
said piston rod having means constructed to axially move said annular member within said working cylinder after a predetermined amount of compression stroke of said piston to increase the volume of said compression stop chamber and to provide hydraulic fluid to flow through the flow control means of said annular member to said compression stop chamber to create a dampening force near the compression end of the piston stroke.

### Claim 2 (depends on 1)

A shock absorber as defined in claim 1 further characterized by:
spring means biasing said annular member to a first position; and
said means constructed to axially move said annular member comprising an butment engageable with said annular member for moving said annular member to a second position such that said annular member is forced to move toward the second position against said bias.

### Claim 3 (depends on 2)

A shock absorber as defined in claim 2 further characterized by:
said annular member being a tubular sleeve with an axial length of over one-half the total travel distance of said piston between its full rebound and full compression positions; and
said abutment causing said sleeve to move over one-half its axial length against the bias of said spring means.

### Claim 4 (depends on 3)

A shock absorber as defined in claim 3 further characterized by:
an internal rebound bumper coaxially mounted about said piston rod within said working cylinder and extending above said annular member;
said abutment engageable with said rebound bumper when said piston is in a full rebound position; and
said bumper being compressible between said abutment and said end closure of said working cylinder.

### Claim 5 (depends on 4)

A shock absorber as defined in claim 4 further characterized by:
said shock absorber incorporated in a suspension strut assembly having an upper mounting assembly; and
an external jounce bumper coaxially mounted about said piston rod externally of said working cylinder and compressible between said end closure and said mounting assembly of said strut.

### Claim 6 (depends on 4)

A shock absorber as defined in claim 4 further characterized by:
said internal rebound bumper positioned above the upper end of said sleeve;
said abutment on said piston rod spaced from said piston a distance greater than the axial length of said sleeve; and
said abutment engageable with a lower end of said sleeve.

### Claim 7 (depends on 3)

A shock absorber as defined in claim 3 wherein said spring means comprises:
a spring seat formed on said annular member;
a spring seat fixedly mounted on said working cylinder;
a spring coaxially mounted about said piston rod and seated between said seats; and
said annular member biased by said spring to said first position.

### Claim 8 (depends on 7)

A shock absorber as defined in claim 7 further characterized by:
said spring seat fixedly mounted on said working cylinder situated below said upper end of said sleeve; and
said spring being compressed by said abutment and forming a rigid stop for said piston when said spring is fully compressed between said seat on said sleeve and said seat of said working cylinder.

### Claim 9 (depends on 8)

A shock absorber as defined in claim 8 wherein:
said sleeve, said working cylinder, and said spring seat fixedly mounted on said working cylinder forming a variable size spring chamber for housing said spring; and
said spring chamber has restrictive flow means in communication with one of said rebound chambers and said compression stop chamber.

### Claim 10 (depends on 9)

A shock absorber as defined in claim 9 wherein:
said restrictive flow means of said spring chamber is constructed to gradually restrict the flow of liquid therethrough.

### Claim 11 (depends on 10)

A shock absorber as defined in claim 10 wherein said restrictive flow means of said spring chamber includes:
said spring seat fixed to said working cylinder being annular in shape with a depending cylindrical wall;
said sleeve having its lower end tapered to fit through said cylindrical wall with an initial clearance;
said sleeve above said tapered end sized such that said sleeve extends through said cylindrical wall forming a restrictive clearance therebetween;
said spring seat on said sleeve forming a restricted clearance with said working cylinder; and
said flow control means of said sleeve in the proximity of said tapered end.

### Claim 12 (depends on 2)

A shock absorber as defined in claim 2 further characterized by:
an internal rebound bumper coaxially mounted about said piston rod within said working cylinder and extending above said annular member;
said abutment engageable with said rebound bumper when said piston is in a full rebound position; and
said bumper being compressible between said abutment and said end closure of said working cylinder.

### Claim 13 (depends on 12)

A shock absorber as defined in claim 12 wherein said spring means comprises:
said annular member forming a spring seat thereon;
a spring seat fixedly mounted on said working cylinder;
a spring coaxially mounted about said piston rod and seated between said seats; and
said annular member biased by said spring to a first position.

### Claim 14 (depends on 13)

A shock absorber as defined in claim 13 further characterized by:
said spring seat fixedly mounted on said working cylinder situated below said upper end of said annular member; and
said spring being compressed by said abutment and forming a rigid stop for said piston when said spring is fully compressed between said seat on said annular member and said seat of said working cylinder.

### Claim 15 (depends on 14)

A shock absorber as defined in claim 14 further characterized by:
said shock absorber incorporated in a suspension strut assembly having an upper mounting assembly; and
an external jounce bumper coaxially mounted about said piston rod externally of said working cylinder and compressible between said end closure and said mounting assembly.

### Claim 16 (depends on 2)

A shock absorber as defined in claim 2 wherein said spring means comprises:
a spring seat formed on said annular member;
a spring coaxially mounted about said piston rod and seated between said piston rod and seated between said seats; and
said annular member biased by said spring to said first position.

### Claim 17 (depends on 16)

A shock absorber as defined in claim 16 further characterized by:
said spring seat fixedly mounted on said working cylinder situated below an upper end of said annular member; and
said spring being compressed by said abutment and forming a rigid stop for said piston when said spring is fully compressed between said seat on said annular member and said seat of said working cylinder.

### Claim 18 (depends on 1)

A shock absorber as defined in claim 1 further characterized by:
said shock absorber incorporated in a suspension strut assembly having an upper mounting assembly;
an external jounce bumper coaxially mounted about said piston rod externally of said working cylinder and compressible between said end closure and said mounting assembly.

### Claim 19

A hydraulic shock absorber characterized by:
a working cylinder;
a piston rod and piston mounted thereon sized to be slideably received within said working cylinder and dividing said cylinder into jounce and rebound chambers with said jounce chamber defined below said piston and said rebound chamber defined above said piston;
said piston having fluid flow control means constructed to provide a restrictive fluid passage for the control of hydraulic fluid from one of said chambers when said piston is moved between said chambers to create a dampening force;
a moveable member mounted above said piston with said moveable member defining, in part, a compression stop chamber;
said moveable member having fluid flow control means constructed to provide a restricted fluid passage for the control of hydraulic fluid therethrough; and
said piston rod having a means constructed to axially move said movable member only after a predetermined amount of compression stroke of said piston to provide hydraulic fluid to flow through the flow control means of said movable member to create dampening force near compression end of the piston stroke.

### Claim 20 (depends on 19)

A shock absorber as defined in claim 19 further characterized by:
said movable member defining a border of said compression stop chamber and constructed to increase the size of said compression stop chamber when said movable member is axially displaced from a first position to a second position.