It is common in refrigeration systems, such as air conditioning units, to employ a service valve block in the suction line between the evaporator and compressor, and between the condenser and the evaporator. These service valve blocks typically include inlet and outlet conduits, a shutoff valve fitting controlling flow between the inlet and outlet conduits, and a charging/evacuation fitting to permit charging, evacuation and/or testing of the system.
A typical service valve block 10 is illustrated in FIG. 1, and includes a conduit 12 which can be connected to, for instance, the compressor, and a conduit 14 which can be connected to the evaporator, and a shut-off valve fitting 16 for controlling flow between the conduits 12,14. The service block 10 further includes a charging/evacuation fitting 18 to permit charging, evacuation, and testing of the system with which the service block is used.
As can be seen in FIGS. 1 and 2, the fitting 18 includes a body 20 having one end fixed to a housing 22 of the service block 10, and having an interior flow passage communicating with the interior of the housing. A Schrader valve assembly 24 is removably secured within the body 20, such as by threading, for controlling flow through the body 20. The exterior surface of the body 20 is threaded to permit connection of a closure cap 26 thereto when the fitting 18 is not in use, and to permit connection to an internally threaded fluid line when the cap 26 is removed to allow introduction or removal of fluids from the system through the fluid line. The Schrader valve assembly 24 includes a valve housing 28 through which the fluid flows, and which is externally threaded so that the valve assembly can be replaced when needed by simply unscrewing the valve assembly from the body and replacing the defective valve assembly with a new valve assembly. A spring biased valve stem and valve head 29 are provided within the housing for controlling flow therethrough. The valve head 29, which has a seal thereon and which is normally biased into sealed engagement with the housing 28 to prevent flow through the body 20, is actuated away from housing 28 by the valve stem in order to allow fluid to flow through the body.
Although the fitting 18 is generally adequate to permit the introduction and/or removal of fluids from the system, the flow area and thus flow rate provided by the fitting 18 is limited. In particular, the fluid must flow through the relatively small area of the housing 28, which restricts the amount of flow that can flow through the fitting. While it would be possible to increase the size of the housing 28 as well as increasing the size of the flow passage of the body 20, such increases are limited by mechanical constraints, as well as the fact that the size of valve fitting bodies are generally standardized to allow interchangeable use of valve fittings 18 on service valve blocks 10. Further, the seal on the valve head of the Schrader valve increases the size of the valve head 29 and thereby reduces the amount of fluid flow through the fitting 18. Further, while the threads on the exterior surface of the body 20 permit connection with a fluid line, the fluid line must be threaded onto the body, which can be difficult and time consuming, as well as leaving open the possibility of damaging the threads on the body which could require that the fitting be replaced.
What is needed then is an improved valved fitting for use on a service valve block which has a higher flow area, and thus higher flow rate, than conventional fittings with Schrader valve assemblies, and which is designed to permit fast and easy connection with a fluid line, while retaining many of the features of conventional fittings, such as the ability to replace the valve assembly.