Coolant Compressor Start-Up Control to Prevent Pressure Peaks
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Solution Overview
Problem
Existing vehicle air-conditioning systems face challenges in preventing uncontrolled pressure peaks during the start-up phase of the coolant compressor, which can lead to component damage due to undetected internal leakage or defective behavior, and fail to diagnose unsuccessful compressor starts effectively.
Innovation Solution
A method that monitors the start-up behavior of the coolant compressor by increasing the actuation signal over time, limiting it when pressure thresholds are exceeded, and terminating the start-up phase if conditions are not met, allowing for early detection of defective behavior and preventing pressure peaks, with optional self-diagnosis capabilities for the compressor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the actuation signal is continuously increased to maximum value during start-up phase, then the coolant mass flow and pressure increase quickly, but pressure peaks occur that can exceed permissible system limits and cause component damage
Solution Approach 1:
The control method applies preliminary action by implementing a staged actuation signal increase with predefined thresholds (first threshold leading to second threshold). Before reaching maximum actuation, the system prepares by progressively increasing the signal in controlled steps, allowing pressure buildup to be managed in advance rather than occurring abruptly. This preliminary staged approach prevents sudden pressure peaks while still achieving the desired coolant mass flow increase.
2Reliability
If the actuation signal is raised continuously during start-up, then the control deviation is reduced, but defective compressor behavior (internal leakage) remains undetected and causes uncontrolled pressure buildup
Solution Approach 1:
The control method implements feedback by continuously monitoring the high pressure value during the start-up phase and comparing it against expected pressure development. When the actuation signal reaches the first threshold and high pressure does not increase as expected, the system detects this deviation and responds by limiting further actuation signal increase. This feedback mechanism enables detection of compressor defects (such as internal leakage) that would otherwise remain undetected during normal start-up procedures.
3Object-affected harmful factors
If the actuation signal is limited at thresholds, then pressure peaks are prevented, but the start-up phase duration is extended
Solution Approach 1:
The control method applies dynamics by making the actuation signal increase rate adaptive rather than fixed. The system dynamically adjusts the signal increase based on monitored high pressure values and predefined thresholds. When pressure development is normal, the signal can increase more quickly; when pressure deviates from expected values, the increase rate is reduced or paused. This dynamic adjustment optimizes the balance between preventing pressure peaks and minimizing start-up time.
Data Source
AI summary
A method for operating a cooling circuit. It is provided that a) the actuation signal ST of the coolant compressor is provided so as to increase over time from a minimum value (STmin) in order to generate a start-up phase of the coolant compressor, b) a control signal maximum value (STmax) and a control signal threshold (STSW) are provided, where STSW<STmax, c) the actuation signal (ST) is limited to the control signal maximum value (STmax) if the actuation signal (ST) reaches the control signal threshold (STSW) and the measured high and/or low-pressure value (PHD, PND) satisfies a condition.