# US 12,005,755 B2 · Methods and apparatus for controlling a fluid damper

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- Number: US 12,005,755 B2
- Document ID: US12005755B2
- Status: Granted
- Kind: B2
- Application number: 17/697,288
- Filed: 2022-03-17
- Published: 2022-09-08
- Granted: 2024-06-11
- Earliest claimed: 2009-10-13
- Assignees: Fox Factory, Inc.
- Applicants: Fox Factory, Inc.
- Inventors: John Marking
- Web page: https://patentgrep.com/patent/US12005755B2

## CPC

- B60G 17/08: Characteristics of fluid dampers (adjusting fluid dampers in general F16F9/44 - F16F9/53)
- B60G 15/12: and fluid damper
- F16F 9/061: {Mono-tubular units}
- F16F 9/066: {Units characterised by the partition, baffle or like element (F16F9/068, F16F9/08 take precedence)}
- F16F 9/53: Means for adjusting damping characteristics by varying fluid viscosity, e.g. electromagnetically {(F16F13/30 takes precedence; brakes comprising a medium with electrically or magnetically controlled friction F16D57/002; electrorheological fluids per se C10M171/001; magnetorheological fluids per se H01F1/447)}
- F16F 9/535: {Magnetorheological [MR] fluid dampers (springs comprising magnetorheological [MR] elastomers F16F1/361)}
- B60G 15/062: {the spring being arranged around the damper (B60G15/061, B60G15/067, B60G15/07 take precedence)}
- B60G 2202/24: Fluid damper
- B60G 2206/41: Dampers
- B60G 2500/10: Damping action or damper
- B60G 2600/22: Magnetic elements
- B60G 2800/162: Reducing road induced vibrations
- F16F 2222/06: Magnetic or electromagnetic
- F16F 2224/045: magnetorheological
- F16F 2228/066: Variable stiffness
- B60G: VEHICLE SUSPENSION ARRANGEMENTS (air-cushion vehicles B60V; {cycle suspensions B62K25/00})
- F16F: SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION

## Abstract

A spring for a suspension is described. The spring includes: a spring chamber divided into at least a primary portion and a secondary portion, and a fluid flow path coupled with and between the primary portion and the secondary portion. The fluid flow path includes a bypass mechanism, wherein the bypass mechanism is configured for automatically providing resistance within the fluid flow path in response to a compressed condition of the suspension.

## Claims

### Claim 1

A damper comprising:
a damper body having a longitudinal axis and at least partially defining a fluid chamber containing damping fluid;
a piston rod, movable along the longitudinal axis of, and within, said damper body, wherein during a compression stroke, a portion of said piston rod moves into said damper body at least partially within a first portion of said fluid chamber;
an enclosed fluid chamber disposed within said damper, said enclosed fluid chamber at least partially bounded by a first movable member separating said first portion of said fluid chamber from said enclosed fluid chamber;
a gas-filled chamber coupled with said fluid chamber;
said enclosed fluid chamber having a variable rheology fluid disposed therein, said enclosed fluid chamber at least partially displaceable by said damping fluid wherein movement of said enclosed fluid chamber causes a volume change in said gas-filled chamber; and
a magnet disposed within said enclosed fluid chamber, said magnet configured to provide a magnetic field which affects said variable rheology fluid, wherein said magnet selectively produces said magnetic field within said enclosed fluid chamber to bring about a change in said rheology fluid, wherein a portion of said rheology fluid travels through an orifice in said magnet when said enclosed fluid chamber is displaced, and wherein said orifice of said magnet is coated with an abrasion resistant material.

### Claim 2 (depends on 1)

The damper of claim 1 wherein said magnet is an electromagnet.

### Claim 3 (depends on 2)

The damper of claim 2 wherein said electromagnet is remotely actuatable.

### Claim 4 (depends on 3)

The damper of claim 3 further comprising:
a logic/control unit coupled with said electromagnet for controlling operation of said electromagnet.

### Claim 5 (depends on 4)

The damper of claim 4 wherein said logic/control unit controls said electromagnet based upon an input provided from a vehicle to which said damper is coupled.

### Claim 6 (depends on 5)

The damper of claim 5 wherein said input is selected from the group consisting of: wheel speed, damper piston velocity, and piston rod position.

### Claim 7 (depends on 1)

The damper of claim 1, wherein said first movable member comprises a flexible end-wall permitting said enclosed fluid chamber to be displaced relative to said magnet.

### Claim 8 (depends on 1)

The damper of claim 1, wherein said rod includes a valve assembly configured to control flow of said damping fluid.

### Claim 9 (depends on 1)

The damper of claim 1, wherein said variable rheology fluid comprises a magneto-resistive (MR) fluid.

### Claim 10 (depends on 1)

The damper of claim 1, wherein said gas-filled chamber is filled with a pressurized gas.