Active Suspension Accumulator Tuning for Rough Ride Mitigation
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Solution Overview
Problem
Active vehicle suspension systems face issues due to pump inertia leading to undesirably high stiffness during certain driving conditions, particularly at high frequencies and low accelerations, resulting in a rough ride experience.
Innovation Solution
Incorporating two separate accumulators and bypass valves in the suspension system to bypass pump inertia, allowing fluid flow without passing through the hydraulic pump, and using compliant mechanisms to maintain desired stiffness across a wide range of input frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a hydraulic pump is used in the active suspension system to control fluid flow between chambers, then active suspension control is achieved, but pump inertia causes undesirably high stiffness during certain driving conditions
Solution Approach 1:
The patent introduces bypass valves as intermediary components that allow fluid to flow between compression and extension chambers without passing through the hydraulic pump. This mediator enables the system to maintain active control capability while avoiding the harmful pump inertia effect during specific operating conditions, thereby resolving the contradiction between achieving automation and eliminating harmful factors.
2Power
If the suspension system uses a hydraulic pump for fluid flow control, then active force application is achieved, but high frequency inputs result in undesirably high observed stiffness
Solution Approach 1:
The bypass valves are designed to dynamically respond to operating conditions, automatically opening or closing based on the frequency and magnitude of suspension inputs. This dynamic behavior allows the system to maintain high active force application capability at low frequencies while automatically bypassing the pump at high frequencies to prevent excessive stiffness, thus resolving the contradiction between power and harmful factors.
3Extent of automation
If the suspension system operates with pump inertia, then active control is maintained, but the ride experience becomes rough during low acceleration conditions
Solution Approach 1:
The bypass valves serve as intermediaries that selectively route fluid flow away from the pump during low acceleration conditions, eliminating the rough ride experience caused by pump inertia while preserving active control during other operating conditions. This resolves the contradiction between maintaining automation and ensuring ease of operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively mitigates the rough ride problem by ensuring the suspension system remains soft and responsive, providing a comfortable ride experience under various driving conditions.
Implementation Method 1
a first accumulator in direct fluid communication with the compression chamber and arranged to accommodate fluid displaced from the compression chamber during compression of the suspension system component
Implementation Method 2
a second accumulator in direct fluid communication with the extension chamber and arranged to accommodate fluid displaced from the extension chamber during extension of the suspension system component
Implementation Method 3
a piston (107) slidably received in a hydraulic cylinder (103), thereby dividing at least a portion of the hydraulic cylinder into a compression chamber (111) and an extension chamber (109)
Data Source
Figure 1
Figure 2a~2c
Figure 3
AI summary
Presented herein, inter alia, are suspension system components having tuned accumulator sizing and/or stiffness. Such suspension system components are envisioned for use in a distributed active suspension system of a vehicle. In particular, through appropriate sizing of accumulators of a suspension system component of a vehicle, ride quality of the vehicle may be improved and so called "rough ride" issues may be precluded. Alternatively or additionally, various valves or alternative compliant mechanisms may be included in the suspension system component, so that desirable performance may be obtained for a range of operating conditions.