Active Wheel Damper Orifice Control for High Force, Low Noise
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Solution Overview
Problem
Existing active chassis damping systems for motor vehicles face challenges in achieving both dynamic and acoustic advantages under highly dynamic loads, with existing systems often compromising on force gradient and noise levels.
Innovation Solution
The damping system incorporates a double-acting hydraulic cylinder and piston with a hydraulic pump and unit, featuring a maximum hydraulic oil flow of 3 L/min between hydraulic chambers, and includes a controllable orifice to control the flow and achieve a preferred force-speed characteristic curve slope of 50,000 to 250,000 N-s/m.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the hydraulic pump conveys a large volume of hydraulic oil between hydraulic chambers, then the dynamic response and force gradient of the damper are improved, but the noise level increases due to high-velocity fluid flow
Solution Approach 1:
The hydraulic circuit is segmented into multiple parallel flow paths with different orifice sizes. The controllable orifice divides the hydraulic flow into controlled streams, allowing the system to achieve high force gradient when needed while maintaining low noise levels during normal operation by distributing flow through multiple smaller passages rather than one large high-velocity flow path.
Solution Approach 2:
The system dynamically adjusts the orifice cross-section based on operating conditions. The controllable orifice can change its opening size to optimize the balance between force gradient and noise generation. During high-demand situations, the orifice opens wider to provide rapid fluid transfer and high force gradient, while during normal operation it restricts flow to minimize noise from fluid turbulence and cavitation.
2Productivity
If the damper allows high flow of hydraulic oil between chambers for rapid response, then the productivity and dynamic performance are improved, but the manufacturing precision deteriorates due to difficulty in controlling leakage flow
Solution Approach 1:
The system replaces reliance on mechanical tolerances and passive sealing with an active controllable orifice mechanism. Instead of depending on precise manufacturing tolerances to control leakage flow, the invention uses a controllable orifice with adjustable cross-section that can be precisely controlled through actuation, providing superior flow control accuracy independent of manufacturing variations.
Solution Approach 2:
The system changes the flow control parameter from fixed geometric restrictions (orifice size determined by manufacturing tolerances) to a dynamically adjustable parameter (controllable orifice cross-section). This allows the leakage flow rate to be precisely controlled and adjusted based on operational requirements, achieving both high dynamic response and precise flow control.
3Object-generated harmful factors
If the orifice cross-section is reduced to limit hydraulic oil flow to 3 L/min, then the noise level and force gradient are improved, but the speed of piston movement decreases
Solution Approach 1:
The hydraulic flow path is segmented into multiple parallel channels through the controllable orifice structure. By dividing the flow into several smaller streams rather than one restricted flow path, the system maintains lower flow velocity and noise levels while still achieving adequate total flow capacity for acceptable piston movement speed.
Solution Approach 2:
The orifice cross-section is made dynamically adjustable rather than fixed. During normal operation, the orifice is restricted to maintain low noise levels and optimal force gradient. When rapid piston movement is required, the orifice can be opened wider to increase flow capacity and piston speed, providing dynamic optimization of the speed-noise-tradoff.
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
This design enables the damping system to provide both advantageous dynamic properties, such as a high force gradient, and advantageous acoustic properties, such as low noise levels, while maintaining efficient operation under dynamic loads.
Implementation Method 1
the damper comprises at least one orifice, the cross-section of which is sized such that the flow of hydraulic oil across the piston or along the same in both directions of operation of the piston of the damper is at most 3 L/min
Implementation Method 2
The hydraulic pump and the hydraulic unit cooperate with hydraulic chambers of the hydraulic cylinder such that, depending on the direction of conveyance of the hydraulic pump, movement of the piston in a first direction of actuation or in a second direction of actuation can be provided
Implementation Method 3
The damper is formed from a double-acting hydraulic cylinder and a piston movable in a reciprocating manner within said cylinder
Data Source
AI summary
A damping system of an active chassis for one wheel of a motor vehicle. The system includes a double-acting hydraulic cylinder and a damper having a piston, which damper is couplable to a wheel suspension system for the wheel. The system also includes a hydraulic pump, and a hydraulic unit having a hydraulic reservoir and valves. The hydraulic pump and the hydraulic unit cooperate with hydraulic chambers of the hydraulic cylinder such that, depending on the direction of conveyance of the hydraulic pump, a movement of the piston in a first direction of actuation or in a second direction of actuation can be provided. The damper includes the hydraulic cylinder and the piston is designed such that, in the region of the damper, a flow of hydraulic oil via the piston or along the piston of the damper is at most 3 L/min.