The present invention relates to improved fittings for air conditioning systems, and in particular to fittings that provide low leakage rates.
Modern air conditioning systems, such as those used on automotive vehicles, are typically provided with one or more access fittings used to charge, reclaim and service the refrigerant within the system. Such access fittings preferably provide extremely low leakage rates when closed, but they can be opened easily when needed for routine service operations.
One prior-art approach to air conditioner access fittings is to use a spring-loaded valve core that provides an elastomer-to-metal seal. Such fittings are disclosed in the following U.S. patents: Gilbert U.S. Pat. No. 4,979,721 (assigned to the assignee of the present invention), Manz U.S. Pat. No. 5,080,132, Hale U.S. Pat. No. 5,010,743, Starr U.S. Pat. No. 4,753,267, Mullins U.S. Pat. No. 3,996,745, and Rawlins U.S. Pat. No. 3,645,496.
Although such access fittings have been found suitable for a wide variety of applications, the minimum leakage rate of refrigerant is limited by the rate at which refrigerant diffuses through the elastomeric sealing element of the valve core. Access fittings such as those described in the above-identified Gilbert patent include a quick release shoulder on an exterior surface of the valve body.
Metal-to-metal valves are known to the art, as described for example in Mitchell U.S. Pat. No. 5,915,402 and Taylor U.S. Pat. No. 4,932,434. However, these metal-to-metal valves are not illustrated as adapted for use with quick connect couplers, and thus they are not well suited for use as refrigerant access fittings intended for use with quick connect couplers.