Vehicle AC Compressor Control for Low Refrigerant Flow Noise
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Solution Overview
Problem
Variable capacity swash plate type compressors in vehicle air conditioners face issues with refrigerant flow rate, leading to noise and deteriorated workability due to insufficient refrigerant discharge, especially when the compressor enters a low flow rate state.
Innovation Solution
A method is implemented to monitor vehicle speed and accelerating rate, determining if the compressor is in a low flow rate state, and adjusting the ECV duty to a predetermined value to prevent the compressor from entering this state, thereby maintaining optimal refrigerant flow and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the compressor operates with low ECV duty to reduce energy consumption, then fuel efficiency is improved, but refrigerant flow rate decreases causing noise and deteriorated workability
Solution Approach 1:
The control method performs preliminary detection of low flow rate states by monitoring vehicle speed and accelerating rate before noise occurs. When the compressor is operating at low ECV duty and the vehicle is in deceleration or idle state, the controller predicts the low flow rate condition and increases ECV duty in advance, preventing noise and workability deterioration while maintaining fuel efficiency during normal operation
Solution Approach 2:
The system continuously monitors vehicle speed and accelerating rate to detect low flow rate conditions, providing feedback to the controller. When low flow rate is detected, the controller increases ECV duty to restore proper refrigerant flow, creating a closed-loop control system that balances fuel efficiency with compressor reliability
2Reliability
If the ECV duty is increased to maintain refrigerant flow rate, then compressor workability is improved, but engine RPM becomes unstable due to excessive torque change
Solution Approach 1:
Instead of making large ECV duty changes, the control method applies partial action by increasing ECV duty by a predetermined small amount (e.g., 5-10%) only when low flow rate conditions are detected. This gradual adjustment maintains compressor workability and prevents noise while minimizing torque changes that could destabilize engine RPM
Solution Approach 2:
The controller continuously monitors vehicle speed and accelerating rate at predetermined intervals, applying ECV duty adjustments periodically only when necessary. This periodic monitoring and adjustment approach maintains engine RPM stability by avoiding continuous ECV duty changes while ensuring compressor reliability when needed
3Use of energy by moving object
If the compressor discharge capacity is reduced to match low vehicle speed, then energy consumption decreases, but refrigerant flow rate becomes insufficient causing noise
Solution Approach 1:
The control method applies preliminary anti-action by detecting low flow rate conditions through vehicle speed and accelerating rate monitoring before noise occurs. When the vehicle is in deceleration or idle state with low ECV duty, the controller increases ECV duty in advance to prevent the harmful noise effect, counteracting the tendency toward insufficient refrigerant flow before it becomes problematic
Data Source
AI summary
The present invention relates to a method for controlling the operation of a compressor for preventing noise that occurs in case of the shortage of refrigerant flow caused by less discharge capacity of the compressor of an air conditioner for a vehicle. The compressor includes a cylinder bore for compressing a refrigerant, a piston inserted into the cylinder bore, a swash plate having a controllable slope with respect to a drive shaft, and a control valve for controlling the slope of the swash plate. The discharge capacity of the compressor is increased if it is determined that vehicle speed and accelerating rate satisfy predetermined conditions. If a low flow rate state of refrigerant of the compressor is predicted, the ECV duty is increased to prevent the compressor from entering the low flow rate state, thereby improving the workability of the compressor and solving the noise problem.