Hydro-Mechanical Flow Control for Power Steering Energy Efficiency
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Solution Overview
Problem
Conventional power assist steering systems waste energy by maintaining high hydraulic fluid flow and pressure when low steering assist is required, leading to increased torque demand on the engine and reduced fuel efficiency.
Innovation Solution
An electronic pressure control system that uses a hydro-mechanical flow control device with an electro-hydraulic valve to divert excess fluid back to the pump inlet, reducing pressure and flow when low steering assist is needed, utilizing data from vehicle sensors to optimize fluid distribution and minimize parasitic losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pump provides high outlet flow at high pressure to ensure sufficient steering assist, then the steering assist performance is improved, but the torque required to drive the pump increases and fuel efficiency decreases
Solution Approach 1:
The patent applies dynamics by making the flow control device adjustable rather than fixed. The electro-hydraulic valve allows dynamic control of the by-pass orifice opening based on real-time steering demands, enabling the system to transition from high flow/high pressure (when steering assist is needed) to low flow/low pressure (when steering assist is not needed), thus resolving the contradiction between steering performance and energy consumption
Solution Approach 2:
The patent changes the parameters of the flow control device by using an electro-hydraulic valve to vary the opening of the by-pass orifice. This allows continuous adjustment of fluid flow and pressure parameters to match actual steering requirements, preventing unnecessary energy consumption while maintaining sufficient steering assist performance when needed
2Quantity of substance
If the pump provides high output flow when the vehicle is moving at high speed, then the steering system has sufficient flow available, but the pressure increases and parasitic losses increase
Solution Approach 1:
The patent extracts excess fluid flow from the high-pressure circuit by providing a dedicated by-pass orifice that diverts surplus fluid back to the reservoir. The electro-hydraulic valve controls this extraction process, removing only the excess flow while maintaining the minimum required flow for steering assist, thereby reducing parasitic losses associated with circulating high volumes of fluid at high pressure
3Stability of the object's composition
If a by-pass orifice is used to regulate flow to the steering assist valve, then constant flow is maintained, but the pump operates at high pressure even when low steering assist is required
Solution Approach 1:
The patent implements feedback by using the electro-hydraulic valve to sense steering demands and adjust the by-pass orifice opening accordingly. The system continuously monitors steering assist requirements and modulates the by-pass opening to maintain stable flow to the steering assist valve while preventing excessive pressure buildup, thus resolving the contradiction between flow stability and pressure 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
This solution reduces energy losses and improves fuel efficiency by minimizing pump pressure and torque demand during low steering assist conditions, maintaining regulated flow to the steering valve while reducing backpressure on the pump.
Implementation Method 1
An electro-hydraulic valve is connected to the supply side of the hydro-mechanical flow control device and reacts to the electronic monitoring of pressure and other vehicle data to alter the counter-balancing forces within the hydro-mechanical flow control device
Implementation Method 2
A hydro-mechanical flow control device, containing a spring biased spool is connected to both the output of the pump and the input to the steering system
Implementation Method 3
A hydraulic pump is driven by the engine or other power source of the vehicle and provides an output of steering fluid to the steering system under pressure
Data Source
AI summary
An electronic control unit monitors pressure conditions present at the input to the steering system and other vehicle data signals and then provides override control of a hydro-mechanical flow control device. An electro-hydraulic valve is connected to the supply side of the hydro-mechanical flow control device and reacts to the electronic monitoring of pressure and other vehicle data to alter the counter-balancing forces within the hydro-mechanical flow control device. This causes a by-pass diversion of steering fluid to the source by the hydro-mechanical flow control device and thereby relieves backpressure on the pump when relatively little steering assist is required to be provided by the steering system. The control of steering fluid diversion at such times results in a significant reduction in parasitic losses within the steering system and improves the operating and fuel efficiency of the vehicle.