Intermittent Clutch Start Control to Prevent Compressor Slugging
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Solution Overview
Problem
Air conditioning systems in vehicles experience noise and component stress due to liquid slugging, where refrigerant and lubricant pool in low areas and cause vibration and clutch failure upon compressor startup after a period of inactivity.
Innovation Solution
An apparatus with a microcontroller and switching transistor circuit intermittently grounds the compressor clutch for a predetermined period upon startup, allowing the system to purge liquid refrigerant and lubricant, preventing slugging and reducing wear and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the compressor is operated continuously after a period of inactivity, then the A/C system can maintain cooling function, but liquid refrigerant and lubricant pool in low areas causing slugging, vibration, noise, and component stress
Solution Approach 1:
The patent applies preliminary action by implementing an intermittent operation mode before continuous operation. The controller causes the compressor to operate intermittently for a predetermined period (e.g., 1-5 minutes) after system startup or periods of inactivity. This preliminary intermittent operation purges liquid refrigerant and lubricant from the compressor before normal continuous operation begins, preventing liquid slugging and associated harmful effects while maintaining system reliability.
2Reliability
If the compressor is intermittently started to purge liquid, then slugging and component stress are reduced, but wear and noise are generated during the purging cycles
Solution Approach 1:
The patent applies periodic action by implementing controlled intermittent operation cycles. The controller activates the compressor in periodic on/off cycles during the purging phase, allowing liquid to be expelled during active periods while minimizing wear and noise during off periods. This periodic operation continues for a predetermined time until liquid slugging is eliminated, then transitions to continuous operation, thereby reducing overall component stress while managing wear and noise generation.
3Reliability
If the clutch is operated intermittently to discharge liquids, then liquid removal is achieved, but additional control complexity and potential clutch wear are introduced
Solution Approach 1:
The patent applies feedback by implementing a controller that monitors system conditions and automatically adjusts clutch operation. The controller receives inputs regarding system state (such as runtime since last operation, temperature conditions, and pressure differentials) and uses this feedback to determine when intermittent purging is necessary and how long to continue intermittent operation. This feedback-based control achieves effective liquid discharge while minimizing unnecessary clutch cycling and reducing control complexity compared to fixed-timer 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 solution effectively reduces compressor wear and noise by ensuring the system purges liquid refrigerant and lubricant before continuous operation, preventing slugging and extending component lifespan.
Implementation Method 1
a starting controller for a compressor, such as used in a vehicle, which causes the magnetic clutch driving the compressor to be intermittently engaged
Data Source
AI summary
A switch (10, 200) is provided for installation in the air conditioning (A/C) system (12) in a vehicle (16) for intermittently operating the clutch (20) in the A/C system (12) each time the control (44) in the A/C system (12) provides power to operate the clutch (20) to prevent slugging. This turns the compressor (14) a few turns each time the clutch (20) is energized during intermittent operation to purge liquid refrigerant and lubricant from the compressor (14) to prevent slugging. The switch (10, 200) can be installed in existing vehicles by connecting the switch (10, 200) in the wiring harness (18) of the A/C system (12) to the power lead (38) from the control (44) to the clutch (20) and between the ground lead (40) from the clutch (20) and a ground. The switch (10, 200) can include a microcontroller (52) for controlling the operation of a power transistor (70) to intermittently ground the clutch to provide the intermittent operation. A battery (202) can be provided to power the microcontroller (52) for a set period of time after an initial intermittent operation. This prevents additional intermittent operation for the set period of time.