IP Verse

Electronically Controlled Sway Bar Damping Link

Patent No. US10981429 (titled "Electronically Controlled Sway Bar Damping Link") was filed by Fox Factory Inc on Sep 27, 2018.

What is this patent about?

’429 is related to the field of vehicle suspension systems, specifically addressing the reduction of body roll using a sway bar. Traditional sway bar systems passively resist body roll, transferring forces between the heavily loaded and lesser-loaded sides of the suspension. These passive systems offer a fixed compromise between comfort and handling, which is not ideal for all driving conditions.

The underlying idea behind ’429 is to actively control the stiffness of the sway bar system by incorporating an electronically controlled damper link . This link replaces the conventional end link connecting the sway bar to the vehicle's suspension. By adjusting the damping characteristics of this link, the resistance to body roll can be dynamically altered, providing a more adaptable suspension system.

The claims of ’429 focus on a sway bar system comprising a sway bar with a first and second end, a first electronically controlled damper link coupled to the first end and configured to be coupled to a first location on the vehicle, and a second link coupled to the second end and configured to be coupled to a second location on the vehicle. The first link includes a damper cylinder, damping piston, shaft, fluid reserve cylinder with a fluid reservoir, gas chamber, and internal floating piston, and a valve. The ratio of the damper cylinder volume to the valve's flow area is adjustable , enabling electronic control of the damping characteristics.

In practice, the electronically controlled damper link functions as a variable stiffness connection between the sway bar and the vehicle. The damper link contains a piston-cylinder arrangement with a remotely adjustable valve that controls the flow of damping fluid. By adjusting this valve, the resistance to movement of the piston is altered, effectively changing the stiffness of the link. This allows the system to transition between a soft, compliant setting for comfortable cruising and a stiff, responsive setting for improved handling during cornering or high-speed maneuvers.

Unlike passive sway bar systems with fixed stiffness, ’429 allows for real-time adjustments based on driving conditions or driver preferences. The system can use sensor data such as vehicle speed, steering angle, and accelerometer readings to automatically adjust the damping characteristics of the electronically controlled damper link. This adaptive behavior provides a significant improvement in both comfort and handling compared to traditional sway bar designs, offering a more versatile and optimized driving experience. The system can even be locked out completely, effectively disabling the sway bar for specific off-road situations.

How does this patent fit in bigger picture?

Technical landscape at the time

In the late 2010s when ’429 was filed, at a time when vehicle suspension systems commonly relied on a combination of passive and semi-active components to manage ride comfort and handling, electronically controlled systems were increasingly being integrated to allow for real-time adjustments to damping characteristics. This was at a time when microcontrollers were sufficiently powerful and cost-effective to enable complex control algorithms for suspension systems, and when sensors were becoming more prevalent for monitoring vehicle dynamics and road conditions.

Novelty and Inventive Step

The application was initially filed on 09/27/2018. A non-final rejection was issued. Claims 1, 12, 21 and 26 were objected to, and claims 1-2, 4-11, 13-14, 16-28 were rejected under 35 U.S.C. 102 and 103. The prosecution record does NOT describe the technical reasoning or specific claim changes that led to allowance.

Claims

This patent includes 28 claims, with independent claims numbered 1, 12, 26, and 28. The independent claims generally focus on a sway bar system that incorporates electronically controlled damper links. The dependent claims generally elaborate on the specific features, configurations, and components of the sway bar system and its links.

Key Claim Terms New

Definitions of key terms used in the patent claims.

Term (Source)Support for SpecificationInterpretation
Damper cylinder volume
(Claim 1, Claim 26)		“Examples of such an active valve are described and shown in U.S. Pat. Nos. 9,120,362; 8,627,932; 8,857,580; 9,033,122; and 9,239,090 which are incorporated herein, in their entirety, by reference.”The volume of the damper cylinder within the first link.
Electronically controlled damper link
(Claim 12, Claim 26, Claim 28)		“In some embodiments of the present invention, the damping characteristic of at least one damper is obtained by controlling a remotely adjustable active valve (may also be referred to as a remotely adjustable electronic valve or, more concisely, as just an active valve) of the damper, wherein the remotely adjustable active valve utilizes a relatively small solenoid (using relatively low amounts of power) to generate relatively large damping forces.”A link coupled to the sway bar that incorporates damping functionality and whose damping characteristics can be adjusted electronically.
Flow area of said valve
(Claim 1, Claim 26)		“In some embodiments of the present invention, the damping characteristic of at least one damper is obtained by controlling a remotely adjustable active valve (may also be referred to as a remotely adjustable electronic valve or, more concisely, as just an active valve) of the damper, wherein the remotely adjustable active valve utilizes a relatively small solenoid (using relatively low amounts of power) to generate relatively large damping forces.”The cross-sectional area of the valve that controls the flow of fluid between the damper cylinder and the fluid reserve cylinder.
Internal floating piston
(Claim 1, Claim 26)		“Examples of such an active valve are described and shown in U.S. Pat. Nos. 9,120,362; 8,627,932; 8,857,580; 9,033,122; and 9,239,090 which are incorporated herein, in their entirety, by reference.”A piston located within the fluid reserve cylinder that separates the fluid reservoir chamber and the gas chamber.
Operational damping characteristics
(Claim 1, Claim 12, Claim 26, Claim 28)		“In some embodiments of the present invention, the damping characteristic of at least one damper is obtained by controlling a remotely adjustable active valve (may also be referred to as a remotely adjustable electronic valve or, more concisely, as just an active valve) of the damper, wherein the remotely adjustable active valve utilizes a relatively small solenoid (using relatively low amounts of power) to generate relatively large damping forces.”The damping properties of the first link, which are electronically controlled or adjustable.

Litigation Cases New

US Latest litigation cases involving this patent.

Case NumberFiling DateTitle
5:25-cv-01910Jul 25, 2025Fox Factory, Inc. V. Suspension Direct, Inc.

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US10981429

FOX FACTORY INC
Application Number
US16144875
Filing Date
Sep 27, 2018
Status
Granted
Expiry Date
Mar 10, 2039
External Links
Slate, USPTO, Google Patents