Hydraulic Steering Unit Load Sensing Pressure Control
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Solution Overview
Problem
Current hydraulic steering units consume excessive energy when steering a vehicle, particularly due to inefficiencies in fluid flow and pressure management during directional changes.
Innovation Solution
A hydraulic steering unit with a load sensing port that signals pressure to the outside, utilizing a measuring motor and bridge arrangement with variable orifices to control fluid supply, minimizing dead band and enabling dynamic load sensing, and incorporating a pressure relief valve and copying valve for efficient pressure management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional hydraulic steering unit supplies hydraulic fluid continuously to ensure steering responsiveness, then steering responsiveness is improved, but energy consumption increases
Solution Approach 1:
The bridge arrangement with variable orifices dynamically adjusts the flow paths based on steering demands. The orifices vary their opening degrees according to the position of the measuring motor, enabling the system to transition between different flow states (neutral, left steering, right steering) and minimizing unnecessary fluid flow when no steering input is detected
Solution Approach 2:
The measuring motor provides feedback on the steering wheel position, which controls the bridge arrangement to adjust the orifice openings accordingly. This feedback mechanism ensures that hydraulic fluid is supplied only when and where needed, eliminating continuous fluid supply and reducing energy consumption while maintaining steering responsiveness
2Force
If hydraulic fluid is supplied at high pressure to ensure steering force, then steering force is improved, but energy consumption increases
Solution Approach 1:
The system changes the pressure parameter dynamically based on steering demands. The load sensing port detects the actual pressure needed for steering, and the bridge arrangement adjusts the orifice openings to supply fluid at the appropriate pressure level, avoiding unnecessary high-pressure supply when steering force is not required
Solution Approach 2:
The variable orifices in the bridge arrangement dynamically adjust the pressure characteristics of the hydraulic fluid flow based on the steering position detected by the measuring motor, ensuring optimal pressure is supplied only when needed
3Use of energy by moving object
If a bridge arrangement with variable orifices is used to control fluid flow, then energy efficiency is improved, but device complexity increases
Solution Approach 1:
The bridge arrangement with variable orifices performs multiple functions simultaneously: it controls fluid flow direction, regulates pressure, and enables neutral positioning. The measuring motor serves both as a steering actuator and as a sensor for bridge arrangement control, reducing the need for separate components
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 reduces energy consumption by ensuring only the necessary pressure and amount of hydraulic fluid are supplied, minimizing dead band during steering direction changes and maintaining efficient fluid flow, thereby optimizing energy use.
Implementation Method 1
a load sensing port is provided, the load sensing port signaling a pressure in the steering unit to the outside
Implementation Method 2
The measuring motor is driven by the fluid flowing from the pressure port to the working port arrangement
Implementation Method 3
a pressure relief valve is arranged in a flow path between a point upstream the bridge arrangement and the tank port. This pressure relief valve can be used to avoid a too high pressure at the load sensing port
Data Source
AI summary
A hydraulic steering unit (1) is described comprising a supply port arrangement having a pressure port (P) connected to a main flow path (2) and a tank port (T) connected to a tank flow path (3), a working port arrangement having a left working port (L) connected to a left working flow path (4) and a right working port (R) connected to a right working flow path (5), a bridge arrangement (21) of variable orifices (A2L, A3L, A2R, A3R) having a first left orifice (A2L) connected to the main flow path (2) and to the left working flow path (4), a first right orifice (A3R) connected to the main flow path (2) and to the right working flow path (5), a second left orifice (A3L) connected to the left working flow path (4) and to the tank flow path (3), and a second right orifice (A3R) connected to the right working flow path (5) and to the tank flow path (3). Such a steering unit allows steering a vehicle with low energy consumption. To this end a load sensing port (LS) is provided, the load sensing port (LS) signaling a pressure in the steering unit (1) to the outside.