Compressor Thermal Control via Gradient Cooling Function
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Solution Overview
Problem
Existing methods for controlling compressor operation in motor vehicles are imprecise due to their failure to account for the thermodynamic properties of the compressor, leading to potential thermal damage and reduced operational reliability, especially in small compressors with limited installation space and high thermal stress.
Innovation Solution
Determining the cooling function based on a temperature gradient between spatially distinct locations on the compressor, allowing for precise calculation of cooling rates and enabling faster or slower compressor reactivation depending on heat distribution, thus avoiding thermal damage and enhancing operational reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature sensor is installed to directly measure compressor temperature, then temperature measurement precision is improved, but device complexity and installation difficulty increase due to restricted installation space and high cost
Solution Approach 1:
The patent uses an intermediary approach by introducing a thermal model that calculates compressor temperature based on measurable parameters (electrical power consumption, operating time, ambient temperature) rather than directly measuring temperature with a sensor. This mediator model bridges the gap between available measurements and the desired temperature information, avoiding the need for complex temperature sensor installation in the restricted compressor space.
Solution Approach 2:
The patent replaces the mechanical/physical temperature sensing system with a computational thermal model. Instead of using physical temperature sensors that require installation space and calibration, the system substitutes a software-based thermal model that computes temperature from electrical and environmental parameters, thereby eliminating the mechanical sensing complexity.
2Ease of operation
If duty cycle methods are used to control compressor operation, then ease of operation is improved, but measurement precision of thermal load deteriorates because thermodynamic properties of the compressor are not considered
Solution Approach 1:
The patent transforms the control approach by changing the parameters used for thermal load assessment. Instead of relying solely on operational parameters (duty cycle, operating time), the system incorporates thermodynamic parameters specific to the compressor (electrical power consumption, ambient temperature, thermal model characteristics). This parameter transformation enables precise thermal load measurement while maintaining ease of operation through automated control.
Solution Approach 2:
The patent implements a feedback mechanism where the thermal model continuously calculates compressor temperature based on current operating conditions, and this temperature information feeds back to the control system to adjust the duty cycle. This closed-loop feedback ensures that the compressor operates within safe thermal limits while automatically adapting to changing conditions, combining precision with ease of operation.
3Device complexity
If linear temperature estimation methods are used, then device complexity is reduced, but measurement precision deteriorates because linear relationships do not reflect actual non-linear temperature changes
Solution Approach 1:
The patent addresses the non-linear nature of temperature changes by implementing a dynamic thermal model that adapts to varying operating conditions. The model accounts for the fact that temperature changes are greater with large temperature differences than with small ones, using dynamic calculation methods rather than static linear relationships. This dynamic approach maintains measurement precision without significantly increasing device complexity, as the complexity is managed through software algorithms.
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 method increases the speed and accuracy of compressor control, allowing for quicker reactivation and improved operational reliability by accurately assessing cooling rates, reducing the risk of thermal damage and enhancing the level control system's availability.
Implementation Method 1
determining the cooling function based on a temperature gradient between spatially distinct locations on the compressor
Implementation Method 2
the compressor will cool down after it has been switched off by dissipating heat to the environment
Data Source
AI summary
In a method for controlling the operation of a compressor, the compressor is switched off by a controller for preventing thermal damage if an estimated temperature value calculated by the controller exceeds an upper threshold value. For this purpose the controller calculates a cooling function as a state variable utilizing the estimated temperature value, said cooling function representing the chronological course of the cooling of the compressor. According to the invention the controller determines the cooling function based on at least one first and one second estimated temperature value which are associated with points of the compressor that are at spatial distances to each other, the determination being such that the cooling function is determined based on the temperature difference between the first and the second estimated temperature value.