Electrohydraulic Steering Pump Waste-Heat Oil Warming
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Solution Overview
Problem
Hydraulic power steering systems in heavy utility vehicles are permanently heated due to constant hydraulic oil circulation, leading to inefficiencies and the need for a decoupling from the internal combustion engine or electric motor, especially in vehicles without such engines.
Innovation Solution
An electrohydraulic power steering device with a bidirectional hydraulic pump, heat exchanger unit, and heating device to heat hydraulic oil using waste heat from the drive, ensuring continuous operation and uniform temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the hydraulic pump operates discontinuously according to power-on-demand principle, then energy consumption is reduced, but the hydraulic oil temperature drops below optimal operating range
Solution Approach 1:
The patent converts the waste heat generated by the electric motor during operation into a beneficial heating source for the hydraulic oil. The heat exchanger unit captures thermal energy that would otherwise be lost and transfers it to the hydraulic circuit, maintaining optimal oil temperature without requiring continuous pump operation or additional energy consumption.
Solution Approach 2:
The heat exchanger unit acts as an intermediary between the electric motor and the hydraulic system. It transfers thermal energy from the motor to the hydraulic oil through a thermal coupling, enabling temperature maintenance without direct mechanical connection or continuous hydraulic flow.
2Temperature
If the hydraulic pump is permanently driven to maintain oil temperature, then hydraulic oil temperature remains adequate, but energy consumption increases continuously
Solution Approach 1:
Instead of continuously pumping hydraulic oil to maintain temperature (which wastes energy), the system captures and utilizes the waste heat naturally generated by the electric motor during its operation. This converts a harmful byproduct (waste heat) into a useful resource for temperature maintenance.
Solution Approach 2:
The electric motor serves dual purposes: it drives the hydraulic pump during steering operations and simultaneously heats the hydraulic oil through its waste heat. The system essentially self-regulates temperature using the thermal energy already present in the motor during normal operation.
3Temperature
If waste heat from the drive is utilized to heat hydraulic oil, then hydraulic oil temperature is maintained, but device complexity increases due to heat exchanger unit
Solution Approach 1:
The heat exchanger unit serves multiple functions: it transfers waste heat from the motor to the hydraulic system, acts as a thermal coupling element, and can be integrated into existing motor mounting structures. This multi-functionality justifies the added component by providing temperature control without requiring separate heating systems.
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 maintains hydraulic oil temperature, ensuring consistent performance and efficient operation in vehicles without internal combustion engines, supporting automated driving and power-on-demand steering.
Implementation Method 1
The heat exchanger unit is configured to transfer heat, which is generated during the 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
AI summary
An electrohydraulic power steering device for a vehicle includes a hydraulic pump, a drive, a first working line, a second working line, and a heat exchanger. The hydraulic pump is designed, in a first rotation direction, to pump a hydraulic oil to a first pump output of the hydraulic pump and, in a second rotation direction, to pump said oil to a second pump output of the hydraulic pump. The drive is coupled to the hydraulic pump and is designed to drive the hydraulic pump selectively in the first rotation direction or second rotation direction. The first working line is shaped to connect the first pump output fluidically to a first working chamber, the first working chamber being suitable for moving a piston, which is couplable to a steering bar of a steering system, in a first direction. The heat exchanger is designed to transfer heat that is 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.