Closed Center Steering System with Electric Motor Feedback
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Solution Overview
Problem
Existing integral hydraulic power steering systems in vehicles lack effective resistance and feedback mechanisms, leading to an easy-turning steering wheel that can result in a lack of steering 'feel' for the driver, especially when hydraulic fluid pressure is lost.
Innovation Solution
A steering apparatus with a closed center valve and an electric motor connected to the steering wheel, which provides resistance and feedback by modulating the force applied to the steering wheel through a controller that uses sensors to adjust the motor's torque based on steering wheel position and vehicle conditions, and includes an accumulator for enhanced steering performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic fluid pressure is lost, then the steering wheel becomes too easy to turn, but the driver loses steering 'feel' and control
Solution Approach 1:
The electric motor is controlled by a controller that receives signals from sensors detecting steering wheel position and vehicle conditions. The controller dynamically adjusts the electric motor's torque output to provide appropriate resistance to the steering wheel, creating a feedback loop that maintains steering feel and control during hydraulic pressure loss while preventing excessive resistance during normal operation.
2Ease of operation
If the electric motor provides constant resistance to the steering wheel, then steering 'feel' is improved, but the steering wheel becomes difficult to turn during normal operation
Solution Approach 1:
The electric motor's torque output is dynamically adjusted based on real-time steering wheel position and vehicle conditions detected by sensors. The controller modulates the resistance provided by the electric motor, making it variable rather than constant, which allows the system to provide appropriate steering feel during normal operation and enhanced resistance during hydraulic pressure loss.
3Measurement precision
If the closed center valve blocks hydraulic fluid flow during centering, then steering precision is improved, but the system lacks feedback resistance to the driver
Solution Approach 1:
The electric motor is integrated with the steering wheel assembly and works in conjunction with the closed center valve. While the closed center valve provides precise steering control by blocking hydraulic fluid flow during centering, the electric motor simultaneously provides feedback resistance to the steering wheel, combining positional precision with tactile feedback.
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 provides a robust steering system with improved 'feel' and resistance, ensuring precise control of steerable wheels even during hydraulic fluid pressure loss, by dynamically adjusting the steering force and resistance based on real-time vehicle data.
Implementation Method 1
an electric motor operatively connected to the steering wheel. When the electric motor is activated, it resists rotation of the steering wheel
Implementation Method 2
The closed center valve has a closed position blocking the flow of hydraulic fluid to the fluid motor from the fluid source when no turning of the steerable wheels is underway
Implementation Method 3
The closed center valve has an open position allowing the flow of hydraulic fluid from the fluid source to the fluid motor to effect turning of the steerable wheels
Implementation Method 4
an accumulator for storing high pressure fluid. When the valve is in the open position, hydraulic fluid can flow from the accumulator to the fluid motor
Data Source
AI summary
A steering apparatus (10) includes a hydraulic power steering gear (130) for turning the steerable wheels (15) of a vehicle. The steering gear (130) includes a closed center valve (150). An electric motor (18) is operatively connected with the steering wheel (12). When activated, the motor (18) resists rotation of the steering wheel (12) to provide steering feel to the vehicle driver and to modulate force applied to the steering wheel (12) upon initial opening of the closed center valve (150).