External Steering Damper for Power Steering NVH Control
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Solution Overview
Problem
Power steering assemblies in vehicles experience internal lash, leading to undesirable noise, vibration, and harshness due to resonance frequencies, with existing mechanical and software solutions either increasing friction or being limited in effectiveness.
Innovation Solution
Incorporating a damper with pivot connections to the steering linkage and a structural member, housed in a damper housing, which is external to the ball nut, to reduce noise, vibration, and harshness without increasing friction, using hydraulic, pneumatic, magnetorheological, or electronic damping technologies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If mechanical means are used to reduce lash in the ball nut, then noise, vibration, and harshness are reduced, but friction in the ball nut increases
Solution Approach 1:
The invention extracts the damping function from the ball nut assembly by introducing a separate damper connected to the steering linkage. This external damper absorbs vibrations and reduces noise without requiring modifications to the ball nut that would increase friction, thereby resolving the contradiction between reducing harmful vibrations and maintaining low friction.
Solution Approach 2:
The damper acts as an intermediary element between the steering linkage and the vehicle body. It mediates the transmission of vibrations by absorbing and dissipating energy, reducing noise and harshness without directly affecting the friction characteristics of the ball nut, thus resolving the technical contradiction.
2Object-affected harmful factors
If software control means are used to reduce lash, then some noise, vibration, and harshness are reduced, but the reduction is limited in effectiveness
Solution Approach 1:
The invention replaces software-based control with a physical mechanical damping system. The damper provides direct mechanical resistance to vibrations and lash, offering more reliable and effective reduction of noise and harshness compared to software control alone, thereby improving the reliability of the solution.
3Object-affected harmful factors
If the damper is connected externally to the steering linkage, then noise, vibration, and harshness are reduced without increasing ball nut friction, but the device complexity increases
Solution Approach 1:
The invention segments the power steering system by separating the damping function from the steering mechanism. The damper is implemented as an independent component with its own mounting points, allowing it to be added without modifying the ball nut or steering linkage structure, thus minimizing the increase in overall device complexity while achieving the desired vibration reduction.
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
Effectively reduces noise, vibration, and harshness in power steering assemblies by damping resonance frequencies without increasing friction in the ball nut, enhancing the overall performance and quiet operation of the system.
Implementation Method 1
a damper, a first connection between the damper and the steering linkage, and a second connection between the damper and a ground surface
Implementation Method 2
Certain frequencies of vibration from suspension components of the vehicle, or from other sources, can excite the power steering assembly into a resonance frequency because of the lash
Data Source
AI summary
A steering member has a rack portion and a screw portion. The steering member is in a steering housing and operatively connected to a tie rod. A pinion is operatively connected between the rack portion and a steering wheel. A ball nut is operatively connected to the screw portion. A power source is operatively connected to the ball nut. The power source drives the ball nut to effect linear movement of the steering member upon rotation of the steering wheel. A damper has a first connection to the tie rod and a second connection to a ground surface. The ground surface is fixed relative to the steering member. The damper is external to the ball nut.