Dual-Pump Power Steering Fluid Supply System
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Solution Overview
Problem
Existing power steering systems with fixed displacement pumps provide excess flow and pressure at highway speeds, leading to inefficiencies and increased power consumption, as they are sized for maximum flow at engine idle.
Innovation Solution
A dual-pump system where a first pump continuously supplies fluid to the power steering motor assembly, and a second vane pump engages only when the flow is below a predetermined value, with a valve controlling communication between the pumps to manage fluid flow and pressure based on vehicle operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed displacement power steering pump is sized to provide maximum rated flow at engine idle, then sufficient flow is available for dry parking maneuvers, but excess flow and pressure are generated at highway speeds leading to increased power consumption
Solution Approach 1:
The pump is segmented into two independent pumping elements (first pump and second pump) that can operate independently. The first pump provides continuous flow while the second pump engages only when additional flow is needed, allowing the system to deliver appropriate flow levels for different operating conditions without wasting energy on excessive flow generation.
Solution Approach 2:
The pump system transitions from a fixed displacement design to a dynamic variable displacement system where the second pump's engagement and disengagement is controlled by a valve based on real-time flow conditions. This dynamic adjustment allows the system to adapt its output to match actual steering demands, reducing power consumption when full flow is not required.
2Reliability
If a fixed displacement power steering pump provides maximum flow continuously, then steering requirements are always met, but flow control valves must divert excess flow leading to system inefficiency
Solution Approach 1:
The pump output is segmented into two independent streams from the first and second pumps. This segmentation eliminates the need for a single high-capacity pump that must divert excess flow, as each pump can be sized and controlled to provide flow only when needed, thereby eliminating energy loss through flow diversion.
Solution Approach 2:
The first pump provides continuous useful action by always supplying baseline flow to the power steering motor. The second pump supplements this continuous action only when additional flow is required, ensuring that all pump output is useful and no flow needs to be diverted or wasted.
3Quantity of substance
If a single high-capacity pump is used to meet maximum steering demands, then sufficient flow is available at all speeds, but the pump operates inefficiently at low flow conditions
Solution Approach 1:
The single high-capacity pump is segmented into two separate pumps with different capacity levels. The first pump handles baseline flow requirements efficiently, while the second pump provides additional capacity only when needed. This segmentation allows each pump to operate in its efficient range rather than forcing a single pump to operate inefficiently across all flow conditions.
Solution Approach 2:
The system changes the operational parameters by using two pumps with different displacement levels rather than one pump operating at variable efficiency. The second pump is engaged/disengaged based on flow demand, effectively changing the system's total flow capacity parameter to match actual needs and maintain high efficiency across all operating conditions.
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
Optimizes fluid supply to the power steering motor, reducing excess flow and pressure at high speeds, thereby enhancing efficiency and reducing power consumption by ensuring only the necessary flow is delivered during varying driving conditions.
Implementation Method 1
A first pump driven by an engine of the vehicle supplies fluid under pressure to the power steering motor assembly through a supply conduit
Implementation Method 2
A valve which is in fluid communication with the slits has a first condition in which fluid under pressure is supplied to the slits. The valve has a second condition in which the slits are in fluid communication with a reservoir
Data Source
AI summary
An apparatus for use in turning steerable vehicle wheels includes a first pump driven by an engine of the vehicle to supply fluid under pressure to a power steering motor assembly through a supply conduit. A second pump driven by the engine of the vehicle supplies fluid under pressure to the power steering motor assembly when the flow of fluid in the supply conduit is below a predetermined value. The second pump is inactive when the flow of fluid in the supply conduit is above the predetermined value. The second pump has vanes located in slits. A valve which is in fluid communication with the slits has a first condition in which fluid under pressure is supplied to the slits. The valve has a second condition in which the slits are in fluid communication with a reservoir.