Electrohydraulic Steering Pump Heating Using Drive Waste Heat
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Solution Overview
Problem
Existing hydraulic power steering systems in heavy commercial vehicles require continuous hydraulic fluid circulation, which is inefficient and not suitable for vehicles without internal combustion engines or for automated driving scenarios, necessitating a solution that decouples the system from the engine and provides efficient heating of hydraulic oil.
Innovation Solution
An electro-hydraulic power steering device with a bidirectional hydraulic pump, heat exchanger unit, and switchable valve, which uses waste heat from the drive system to heat the hydraulic oil, allowing intermittent operation and preheating, suitable for vehicles without internal combustion engines or for automated driving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If continuous hydraulic fluid circulation is used to maintain hydraulic oil temperature, then the steering unit remains warm, but the system is inefficient and unsuitable for vehicles without internal combustion engines
Solution Approach 1:
The patent implements periodic action by using the waste heat from the drive unit intermittently to heat the hydraulic oil only when needed, rather than continuous circulation. The heat exchanger activates periodically based on temperature sensors detecting when hydraulic oil temperature drops below threshold values, eliminating energy waste during normal operation while maintaining temperature when required.
Solution Approach 2:
The patent converts the harmful waste heat from the drive unit into a beneficial heating source for the hydraulic oil. The heat exchanger captures thermal energy that would otherwise be lost to the environment and transfers it to the hydraulic fluid, turning an energy waste product into a useful heating mechanism that maintains operational temperature without additional energy consumption.
2Temperature
If the hydraulic pump is continuously driven to ensure hydraulic oil circulation, then the steering unit remains warm, but the system complexity increases and is not suitable for on-demand operation
Solution Approach 1:
The system implements self-service through temperature sensors that automatically detect when hydraulic oil temperature falls below threshold values and trigger the heat exchanger activation. The drive unit's waste heat automatically serves the heating function without requiring external control systems or complex operational management, enabling on-demand temperature maintenance with minimal system complexity.
3Productivity
If waste heat from the drive is used to heat the hydraulic oil, then preheating is possible for intermittent operation, but additional components are required
Solution Approach 1:
The patent merges the heating function with the existing drive unit by integrating a heat exchanger that utilizes waste heat already generated by the drive. Instead of adding a separate heating system, the design combines thermal energy recovery with the primary power source, achieving preheating capability while minimizing additional components through functional integration.
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 system operates efficiently on demand, heats the hydraulic oil using waste heat, ensuring consistent performance and steering feel, and is compact, suitable for electrified and automated vehicles.
Implementation Method 1
The heat exchanger unit is designed to transfer heat generated during operation of the drive to at least one of the working lines in order to heat the hydraulic oil flowing through the working line
Data Source
Figure 1~2
AI summary
The invention relates to an electrohydraulic power steering device (105) for a vehicle (100), comprising a hydraulic pump (110), a drive (115), a first working line (120), a second working line (125), and a heat transfer unit (130). The hydraulic pump (110) is designed, in a first rotation direction, to pump a hydraulic oil to a first pump output (135) of the hydraulic pump (110) and, in a second rotation direction, to pump said oil to a second pump output (140) of the hydraulic pump (110). The drive (115) is coupled to the hydraulic pump (110) and is designed to drive the hydraulic pump (110) optionally in the first rotation direction or second rotation direction. The first working line (120) is shaped to connect the first pump output (135) fluidically to a first working chamber (145), the first working chamber (145) being suitable for moving a piston (160), which is couplable to a steering bar (150) of a steering system (155), in a first direction (165). The heat transfer unit (130) is designed to transfer heat (180) that is generated during operation of the drive (115) to at least one of the working lines (120, 125) in order to heat the hydraulic oil flowing through the working line (120, 125).