Vehicle HVAC Compressor Startup Using Coolant Temperature
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Solution Overview
Problem
Existing air conditioning devices for vehicles face challenges in preventing negative suction pressure in compressors, leading to increased costs due to the need for additional pressure sensors and inefficient timing mechanisms that fail to address the issue effectively.
Innovation Solution
An air conditioning device configuration that includes a first water-refrigerant heat exchanger, a compressor, a heater core, a temperature sensor, and a controller, which determines whether to operate the compressor based on coolant temperature to prevent negative suction pressure without the need for additional pressure sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pressure sensor is added at the suction side of the compressor to prevent negative pressure, then the reliability of the compressor is improved, but the manufacturing cost increases
Solution Approach 1:
The patent introduces a standby timer as an intermediary device that mediates between the engine start signal and the compressor start signal. The timer delays the compressor start by a predetermined period, ensuring the compressor only starts when the coolant temperature is sufficiently high to prevent negative suction pressure. This intermediary timing mechanism eliminates the need for expensive pressure sensors while maintaining compressor reliability.
Solution Approach 2:
The system utilizes the existing coolant temperature condition (naturally rising after engine start) to self-regulate compressor startup timing. By making the compressor startup dependent on the naturally increasing coolant temperature over time, the system automatically prevents negative pressure conditions without requiring additional sensing devices or complex control mechanisms.
2Reliability
If a predetermined standby time is provided after engine start before compressor drive to prevent negative pressure, then the compressor reliability is improved, but the effectiveness of the countermeasure deteriorates because the timing cannot be optimized according to engine heat generation
Solution Approach 1:
The patent transforms the static, fixed standby time approach into a dynamic, adaptive timing mechanism. The compressor startup timing is dynamically adjusted based on the actual coolant temperature condition, which varies with engine heat generation. The control unit continuously monitors coolant temperature and determines the optimal startup moment, making the system adaptable to different operating conditions rather than relying on a predetermined fixed delay.
Solution Approach 2:
The system implements feedback control by using the coolant temperature condition as a real-time indicator to determine compressor startup timing. The control unit receives feedback about the current thermal state of the system and adjusts the compressor startup decision accordingly. This feedback mechanism ensures the compressor starts at the most appropriate moment for each specific operating condition, maximizing the effectiveness of the negative pressure prevention measure.
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 configuration effectively prevents negative suction pressure in compressors, reducing costs and improving efficiency by utilizing existing temperature sensors to manage compressor operation.
Implementation Method 1
a first water-refrigerant heat exchanger which performs a heat exchange between a coolant and a low-temperature and low-pressure refrigerant, and vaporizes the refrigerant
Implementation Method 2
vaporizes the refrigerant
Implementation Method 3
a compressor which compresses the refrigerant fed from the first water-refrigerant heat exchanger, to a high-temperature and high-pressure refrigerant
Implementation Method 4
a heater core which heats an interior of a vehicle by using heat of the high-temperature and high-pressure refrigerant discharged by a compressor
Data Source
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AI summary
This air conditioning device for vehicle includes a first water-refrigerant heat exchanger which performs a heat exchange between a coolant and a low-temperature and low-pressure refrigerant, and vaporizes the refrigerant, a compressor which compresses the refrigerant fed from the first water-refrigerant heat exchanger, to a high-temperature and high-pressure refrigerant, and discharges the refrigerant, a heater core which heats an interior of a vehicle by using heat of the high-temperature and high-pressure refrigerant discharged by the compressor, a temperature sensor which detects a temperature of the coolant circulating in the first water-refrigerant heat exchanger and a cooling path of a heat generating component of the vehicle, the temperature being detected when the coolant flows in the first water-refrigerant heat exchanger, and a controller which determines whether or not to permit driving of the compressor, based on the temperature detected by the temperature sensor.