A/C Compressor Clutch Override Using Manifold Vacuum Feedback
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Solution Overview
Problem
Automotive air-conditioning systems face inefficiencies and safety issues when operating under high engine loads, particularly during prolonged inclines, as existing systems require manual adjustments and may lead to passenger compartment warming and safety hazards if defrost is needed.
Innovation Solution
A device that senses engine intake manifold vacuum to automatically control the compressor clutch, disengaging it during high engine loads and re-engaging when conditions allow, using a switching circuit to maintain an average pressure reading and adjust operation based on engine load conditions, ensuring efficient engine operation and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the compressor clutch is disengaged during high engine loads to improve engine efficiency, then engine fuel economy is improved, but the passenger compartment may become warmer than desired and safety issues can arise if defrost is required
Solution Approach 1:
The system dynamically changes the compressor operation parameters based on engine load conditions. When high engine load is detected (manifold pressure above threshold), the clutch is disengaged to improve fuel economy. When low load is detected (manifold pressure below threshold), the clutch is re-engaged to maintain passenger comfort and defrost functionality. This parameter-based control resolves the contradiction by adapting system behavior to operating conditions.
Solution Approach 2:
The system continuously monitors manifold pressure as feedback from the engine operating conditions and uses this information to control clutch engagement. The feedback loop ensures that the compressor is disengaged only when truly needed for fuel economy and re-engaged when comfort and safety requirements return, thus resolving the contradiction between fuel efficiency and reliability.
2Adaptability or versatility
If a manual adjustment mechanism is provided to allow operators to adjust the disengagement threshold, then adaptability to different operating conditions is improved, but the complexity of operation increases and may create safety hazards
Solution Approach 1:
The system performs the threshold adjustment function automatically without requiring operator intervention. The microprocessor continuously monitors manifold pressure and autonomously determines when to engage or disengage the clutch based on predetermined thresholds. This self-service approach eliminates the need for manual adjustments, thereby maintaining adaptability while removing operational complexity and safety hazards associated with manual intervention.
3Reliability
If the compressor clutch is allowed to re-engage once manifold pressure drops below threshold, then passenger comfort is maintained, but the system may not account for prolonged high load conditions such as long inclines
Solution Approach 1:
The system dynamically adapts to prolonged high load conditions by continuously monitoring manifold pressure over time. Rather than using a static threshold, the system evaluates the duration and persistence of high pressure conditions. If high load persists for extended periods (such as during long inclines), the system maintains clutch disengagement longer than a simple threshold-based system would, thus optimizing engine efficiency while eventually re-engaging when conditions warrant to maintain comfort.
Data Source
AI summary
Methods and devices that use an engine load condition of a vehicle, for example, the vehicle's engine intake manifold or plenum vacuum, to promote the efficiency of the engine. The methods and devices are operable to control the compressor of the vehicle's air-conditioning system, enabling the compressor to be shut off when the vehicle is under relatively high loads. The methods and devices operate by sensing a parameter indicative of an engine load condition of the vehicle, determining a difference between a reading of the parameter and an average based on multiple readings of the parameter, and then engaging and disengaging the compressor clutch depending on whether the reading of the parameter is above or below the average of the parameter. The compressor clutch is engaged if the engine operates under a high load for a duration that is dependent on the average of the parameter.