Liquid Cooling Assembly for Electric Motor Generator Unit
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Solution Overview
Problem
Existing liquid cooling systems for electric motor-generator units in agricultural vehicles do not effectively compensate for temperature-related changes in coolant viscosity, leading to inefficient cooling and increased frictional forces between the stator and rotor.
Innovation Solution
A control device adjusts the pressure and volume flow of the coolant based on detected operating temperature variables, setting lower and upper limits to maintain optimal cooling performance by accounting for viscosity changes, thereby minimizing frictional forces and ensuring adequate lubrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the pressure or volume flow of cooling liquid supplied to the air gap is increased to improve cooling performance, then the cooling capacity is improved, but the frictional forces or shearing forces between stator and rotor increase, reducing efficiency
Solution Approach 1:
The system dynamically adjusts the cooling liquid supply pressure and volume flow based on real-time temperature measurements from multiple sensors. The control unit continuously modifies operating parameters to match actual cooling requirements, avoiding constant high-flow operation that causes frictional losses while ensuring adequate cooling when temperatures rise.
Solution Approach 2:
The control unit changes physical parameters of the cooling liquid supply system (pressure and volume flow) based on detected temperature conditions. By adjusting these parameters dynamically rather than maintaining fixed high values, the system achieves effective cooling while minimizing energy losses from frictional forces in the air gap.
2Loss of energy
If the volume flow of coolant is reduced to minimize frictional forces, then efficiency is improved, but cooling performance becomes insufficient, leading to overheating
Solution Approach 1:
Multiple temperature sensors positioned at different locations within the motor-generator unit provide continuous feedback to the control unit. This feedback mechanism allows the system to detect temperature rises early and increase coolant flow accordingly, preventing overheating while maintaining low flow rates during normal operation to minimize frictional losses.
Solution Approach 2:
The control unit periodically monitors temperature conditions and adjusts coolant flow in response to actual thermal conditions. Rather than maintaining constant high flow, the system applies cooling only when and where needed based on periodic temperature measurements, reducing overall frictional losses while ensuring cooling performance when required.
3Device complexity
If the coolant supply system uses a fixed pressure determined by the vehicle's central hydraulic system, then system simplicity is maintained, but the ability to optimize cooling efficiency is limited
Solution Approach 1:
The control unit leverages the existing vehicle hydraulic system's central pressure supply for coolant, eliminating the need for a dedicated pump system. This multi-functional approach uses the vehicle's existing hydraulic infrastructure for cooling purposes, maintaining system simplicity while the control unit optimizes flow distribution to improve cooling efficiency and reduce energy losses.
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 approach optimizes the cooling performance/efficiency ratio by dynamically adjusting coolant supply to match the actual cooling requirements of the motor-generator unit, reducing unnecessary frictional forces and preventing flooding of the air gap.
Implementation Method 1
pressurized cooling liquid can be conducted from the outside, among other things through a magnetic air gap running between the stator and rotor
Implementation Method 2
The cooling liquid located in the air gap leads to the occurrence of efficiency-reducing shearing or frictional forces between the stator and rotor, these increasing with the pressure or volume flow of the cooling liquid supplied
Implementation Method 3
the control unit specifying a lower and/or upper limit value dependent on the actual value of the operating temperature variable in order to limit the pressure and/or volume flow of the coolant supplied in such a way that a temperature-related change in viscosity of the coolant supplied is compensated
Data Source
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AI summary
Arrangement (10) for liquid cooling of an electric motor-generator unit, comprising an electric motor-generator unit (12) having a magnetic air gap (40) extending between a stator (16) and a rotor (30), wherein the air gap (40) can be supplied with coolant from the outside for cooling the electric motor-generator unit (12). A control device (66) adjusts the pressure (p) and/or volume flow rate (Q) of the supplied coolant as a function of a detected actual value (Tist) of an operating temperature parameter of the electric motor-generator unit (12).