Cooling Oil Circuit Pressure Control for Hydraulic Element Flow
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Solution Overview
Problem
Existing methods for controlling and regulating cooling oil circuits in motor vehicles are computationally expensive and prone to non-convergence due to the use of non-linear systems of equations, which require significant memory and computational resources, and often fail to accurately determine the required volume flow for hydraulic elements like electric machines and transmissions.
Innovation Solution
A cooling method that determines the pressure requirement of hydraulic elements using an approach function based on volume flow requirements, iteratively minimizes an objective function to converge to zero, and uses an approach function to calculate the required volume flow of the oil pump, eliminating the need for maps and reducing computational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If non-linear systems of equations with characteristic maps are used to model the cooling oil circuit, then the model can represent the hydraulic system accurately, but the computational effort increases significantly and the solution may not converge
Solution Approach 1:
The patent transforms the non-linear system of equations into a linear system by changing the mathematical representation parameters. Instead of using non-linear characteristic maps that require iterative numerical solutions, the invention uses a linearized model where flow rates and pressures can be calculated directly through matrix operations, eliminating convergence issues and reducing computational complexity
Solution Approach 2:
The patent replaces the traditional mechanical/physical modeling approach (non-linear hydraulic equations with characteristic maps) with a mathematical substitution approach (linear system representation using node and mesh rules). This substitution allows the use of efficient linear algebra methods instead of computationally intensive non-linear solvers
2Reliability
If non-linear approaches with characteristic maps are used to determine hydraulic parameters, then the model can capture complex hydraulic behavior, but the memory requirements and computational resources increase
Solution Approach 1:
The patent changes the parameter representation from non-linear characteristic maps requiring large memory storage to linear system parameters that can be stored in compact matrices. This parameter transformation maintains the ability to represent hydraulic behavior while significantly reducing memory requirements and computational resource usage
3Measurement precision
If iterative numerical methods are used to solve the non-linear system of equations, then a solution can be obtained, but the solution may not converge and considerable computational effort is required
Solution Approach 1:
The patent substitutes the iterative numerical solution method with a direct linear system solution. By representing the hydraulic circuit as a linear system of equations based on node and mesh rules, the invention eliminates the need for iterative convergence, guaranteeing a reliable solution through direct matrix computation
Data Source
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Figure 3
AI summary
The present disclosure relates to a cooling method for a hydraulic element of a cooling oil circuit (2) of a motor vehicle (1), wherein the cooling oil circuit (2) is configured for cooling an electric machine and a transmission, wherein the cooling oil circuit (2) comprises an oil pump (M), and wherein the electric machine can be coupled into the transmission, the cooling method comprising: determining (11; 21) a pressure requirement of the hydraulic element based on a function taking into account a volume flow requirement of the hydraulic element as a function of a residual pressure valve parameter; determining (12; 22) an actual pressure at the hydraulic element as a function of the residual pressure valve parameter; determining (13; 23) an objective function based on a difference between the pressure requirement and the actual pressure; and minimizing (14;24) the objective function such that the objective function converges to zero in an iterative procedure to determine a required volume flow rate of the oil pump for cooling the hydraulic element.;