Automotive TXV Bleed Passage for Reduced Compressor Hiss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Automotive air conditioning systems with thermal expansion valves experience undesirable hissing noise due to rapid valve opening and cycling, which existing solutions attempt to mitigate by reducing valve size, adding screens, or delaying opening, but these methods either limit system performance or increase complexity and cost.
Innovation Solution
A bleed passage with a check valve is introduced in the expansion valve to bleed refrigerant to the evaporator after the compressor shuts off, reducing the initial refrigerant flow rate and hiss noise, while a check valve prevents charge migration and maintains system efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the valve opening size is reduced, then the hiss noise is reduced, but the cool-down performance of the system is limited
Solution Approach 1:
The invention divides the single valve opening into two separate openings: a main valve aperture for high-capacity refrigerant flow during normal operation, and a restricted aperture for controlled delayed opening. This segmentation allows the system to maintain high cool-down performance through the main aperture while using the restricted aperture to control the timing of valve opening, thereby reducing hiss noise during compressor startup and cycling.
2Object-generated harmful factors
If screens are added at the TXV inlets and outlets, then the hiss noise is reduced, but the device complexity and cost increase
Solution Approach 1:
The invention extracts and eliminates the need for screens by implementing a restricted aperture within the valve body structure itself. Instead of adding screens as separate components at the inlets and outlets, the restricted aperture is integrated into the valve's internal geometry, providing hiss noise reduction through controlled flow restriction while maintaining simplicity in device structure and reducing overall complexity.
3Object-generated harmful factors
If a sequence valve is added in series with the TXV, then the hiss noise is reduced, but the device complexity and cost increase
Solution Approach 1:
The invention merges the function of the sequence valve with the existing TXV structure by incorporating the restricted aperture directly into the valve body. This integration combines the flow control functions of both the main valve and the sequence-valve-like restricted opening into a single unified component, eliminating the need for a separate sequence valve in series and thereby reducing device complexity and cost while maintaining the delayed opening function to reduce hiss noise.
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 hiss noise during compressor cycling by priming the system for lower superheat and minimizing charge migration, achieving a compact and cost-effective mechanism that maintains system performance without adding significant complexity.
Implementation Method 1
A check valve is placed in the bleed passage for substantially blocking refrigerant flow in the direction from the outlet to the inlet at all times
Implementation Method 2
The bleed passage is adapted to bleed refrigerant to the evaporator immediately after the compressor shuts off to prime the air conditioning system for a lower superheat when the compressor turns on
Data Source
AI summary
An expansion valve for an air conditioning system circulates refrigerant through a fixed-displacement compressor, a condenser, and an evaporator. An inlet is provided for receiving refrigerant liquefied in the condenser. An outlet of the expansion valve supplies refrigerant to the evaporator. A valve element controls flow of refrigerant between the inlet and the outlet, wherein the valve element is normally closed. A control assembly is coupled to the valve element and is responsive to at least one temperature or pressure in the air conditioning system to open the valve element to variably meter the refrigerant to the evaporator. A bleed passage bypasses the valve element to conduct refrigerant between the inlet and the outlet. The bleed passage is adapted to bleed refrigerant to the evaporator immediately after the compressor shuts off to prime the air conditioning system for a lower superheat when the compressor turns on, and the bleed path has a flow capacity substantially smaller than the flow capacity of the main valve aperture.