Refrigeration cycle device
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Solution Overview
Problem
The existing refrigerant cycle apparatuses face challenges in meeting the closed valve leakage rate specifications for safety cutoff valves, particularly for gas-side cutoff valves, which increases manufacturing and purchase costs due to larger diameters and higher leakage rates compared to liquid-side cutoff valves, as per the Japan Refrigeration and Air Conditioning Industry Association's guidelines.
Innovation Solution
A refrigerant cycle apparatus is designed with a gas-side cutoff valve and a liquid-side cutoff valve, where the cutoff leakage rate at the gas-side valve is made higher than the liquid-side valve, allowing for reduced manufacturing costs while maintaining safety by optimizing the valve clearance and leakage rates within specified limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gas-side cutoff valve diameter is increased to meet safety specifications, then the closed valve leakage rate decreases, but the manufacturing cost and purchase cost increase
Solution Approach 1:
The patent changes the physical parameters of the gas-side cutoff valve, specifically allowing the valve diameter to be smaller than conventional designs and the valve clearance to be within 0.02mm to 0.05mm. By optimizing these parameters, the valve achieves adequate leakage control without requiring oversized components, thereby reducing manufacturing cost while maintaining reliability
Solution Approach 2:
The patent applies different clearance specifications to different valve regions. The valve clearance is precisely controlled at the seal portion (0.02mm to 0.05mm) to ensure low leakage, while other parts of the valve can have standard tolerances. This localized precision approach reduces overall manufacturing complexity and cost compared to uniformly high-precision manufacturing
2Reliability
If the gas-side cutoff valve diameter is increased to meet safety specifications, then the closed valve leakage rate decreases, but the purchase cost increases
Solution Approach 1:
The patent optimizes the valve diameter parameter to be smaller than conventional gas-side cutoff valves while compensating with optimized clearance parameters. This parameter optimization results in a more compact, cost-effective valve design that meets leakage requirements without the premium cost of oversized valves
3Reliability
If the valve clearance is reduced to meet leakage specifications, then the closed valve leakage rate decreases, but the manufacturing cost increases
Solution Approach 1:
The patent establishes an optimal clearance range (0.02mm to 0.05mm) that balances leakage performance with manufacturability. This parameter specification avoids the need for ultra-precise clearance control while ensuring adequate sealing, thereby reducing manufacturing precision requirements and associated costs
Solution Approach 2:
The patent applies partial precision to the critical seal portion rather than requiring excessive precision throughout the entire valve. By focusing clearance control only where it matters for sealing (the valve seat and seal portion), the design achieves adequate leakage control without the prohibitive cost of comprehensive high-precision manufacturing
Data Source
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AI summary
Excessive specifications of a cutoff valve of a refrigerant cycle apparatus lead to an increase in manufacturing cost. An air conditioner (1) that circulates a flammable refrigerant in a refrigerant circuit (10) includes a liquid-side cutoff valve (71a) and a gas-side cutoff valve (68a) that are put into a cutoff state when refrigerant leakage is detected to suppress the refrigerant leakage into a predetermined space. In a case where fluid is air at 20°C and a differential pressure between upstream and downstream of each of the liquid-side cutoff valve (71a) and the gas-side cutoff valve (68a) is 1 MPa, a cutoff leakage rate at the liquid-side cutoff valve (71a) in the cutoff state is higher than 300 (cm3/min), and a cutoff leakage rate at the gas-side cutoff valve (68a) in the cutoff state is lower than 300 × R (cm3/min), the cutoff leakage rate being an air leakage rate. Here, R = (ρmd × Vmd × Ad)/(Cr × (2 × ΔPr/ρ1r)0.5 × Av × ρ1rl + Av × (2/(λ + 1))((λ + 1)/2(λ - 1)) × (λ × P1r × ρ1rg)0.5) or R = 1, and R is determined based on at least one of a tolerable average concentration, a leakage height, or the type of the refrigerant.