Air conditioner access and service fittings

[0002] The present invention relates to improved fittings for air conditioning systems, and in particular to fittings that provide low leakage rates.

[0003] Modem 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.

[0004] 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.

[0005] 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.

[0006] 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.

[0007] The present invention is directed to a low leakage air conditioner access valve that is well suited for use with quick connect couplers.

[0008] The preferred embodiment described below combines a twist-to-open valve that provides an extremely low leakage, metal-to-metal seal. A valve core is disposed in a central bore in the twist-to-open valve, and refrigerant cannot pass through the access fitting until the twist-toopen valve is opened by rotating it relative to the valve body, and the valve core is opened by depressing the valve core stem. The valve body defines an annular external quick release shoulder, and the disclosed access fitting is used with a service fitting that includes a quick release mechanism to engage the quick release shoulder, a wrench to engage the twist-toopen valve, and a valve core depressor to depress the valve core stem.

[0009] The foregoing paragraphs have been provided by way of introduction, and they are not intended to limit the scope of the following claims.

[0010] FIG. 1 is a cross sectional view of an air conditioner access fitting mated with an air conditioner service fitting that incorporate preferred embodiments of this invention.

[0011] FIG. 2 is a schematic cross sectional view of the fittings of FIG. 1 prior to being made together.

[0012] FIG. 3 is a schematic cross sectional view showing the fittings of FIG. 1 in a mated configuration, with the twist-to-open valve in an open position and the valve core in a closed position.

[0013] FIG. 4 is a schematic cross sectional view corresponding to FIG. 2, except that both the twist-to-open valve and the valve core are shown in the open position.

[0014] Turning now to the drawings, FIG. 1 shows an access fitting 10 mated with a service fitting 100. The access fitting 10 includes a valve body 12 that defines a stepped, partially threaded bore 18 and a cross bore 30. The cross bore 30 receives air conditioner lines 14, 16, which can be secured to the valve body 12 in any convenient manner, as for example by brazing. The cross bore 30 interconnects the air conditioner lines 14, 16, and the cross bore 30 provides fluid communication between the air conditioner lines 14, 16 and the bore 18.

[0015] The bore 18 defines a set of internal threads 20 as well as an annular valve seat 22 that extends around the bore 18. The valve body 12 forms a recess 24 adjacent to an internal annular chamfer 26. The exterior surface of the valve body 14 forms a conventional quick release shoulder 28.

[0016] A twist-toopen valve 40 is mounted in the bore 18 of the valve body 12. The twist-to-open valve 40 defines a set of external threads 42 configured to mate with the internal threads 20. The end of the twist-to-open valve 40 closest to the cross bore 30 forms a frusto-conical valve element 44 configured to mate with the valve seat 22 when the twist-to-open valve 40 is in the closed position shown in FIG. 1. The twist-to-open valve 40 can be moved from the closed position of FIG. 1 to an opened position as shown in FIGS. 3 and 4 by rotating the twist-to-open valve 40 relative to the valve body 12 in an opening direction.

[0017] The twist-to-open valve 40 defines a second stepped bore 46 and a cross bore 48. When the twist-to-open valve 40 is in the opened position of FIGS. 3 and 4, the cross bore 30, the bore 18, the cross bore 48 and the second bore 46 cooperate to form a fluid path. This fluid path is closed in a substantially zero leakage manner when the twist-to-open valve 40 is positioned to the closed position of FIG. 1, with the valve element 44 in sealing, metal-to-metal contact with the valve seat 22. A portion of the second bore 46 is formed with a set of internal threads 58. An O-ring 50 is mounted around the twist-to-open valve 40 to seal against the valve body 12 and to prevent the leakage of refrigerant between the twist-to-open valve 40 and the valve body 12 when the twist-to-open valve 40 is open.

[0018] The twist-to-open valve 40 also defines an external groove 52 and an end portion 54. The end portion 54 defines a set of wrench flats 56, which may be conventional, hexagonally arranged wrench flats. The end portion 54 also defines a cylindrical sealing surface 57.

[0019] A locking element 60 is mounted in the groove 52 of the twist-to-open valve 40. This locking element 60 in this preferred embodiment is a split ring sized to fit within the groove 52. The chamfer 26 assists in compressing the split ring on assembly of the twist-to-open valve 40 into the valve body 12. A shoulder 53 acts as a stop that prevents the locking element 60 and thereby the twist-to-open valve 40 from moving out of the valve body 12 once assembled. In this way, inadvertent disassembly of the twist-to-pen valve 40 from the valve body 12 is prevented.

[0020] A valve core 70 is installed in the second bore 46. The valve core 70 may be substantially conventional, and the valve core 70 includes an elastomeric sealing element 72 connected to a stem 74. A spring 76 biases the sealing element 72 to a closed position.

[0021] As shown in FIG. 1, the access fitting 10 is preferably used with the service fitting 100. The service fitting 100 includes a generally cylindrical housing 102 that defines a recess 104 that opens out at one end of the housing 102.

[0022] The housing 102 supports a quick connect mechanism 106 that can be conventional. The quick connect mechanism 106 shown in FIG. 1 includes an array of balls 108 that are radially positioned by a collar 110. The collar 110 is mounted to slide axially along the housing 102, and is biased to the position of FIG. 1 by a spring 112. When the collar 110 is shifted to the right as shown in FIG. 1, the balls 108 are permitted to move radially outwardly to pass over the quick release shoulder 28 of the valve body 12. When the collar 110 is released, the spring 112 restores the collar 110 to the position of FIG. 1, where the collar 110 prevents the balls 108 from moving radially outwardly and thereby retains the housing 100 on the valve body 12. The collar 110 is prevented from moving excessively to the left as shown in FIG. 1 by a split ring 114. A passageway 116 extends through one side of the housing 102 and is provided to introduce refrigerant into the recess 104 or to remove refrigerant from the recess 104. The passageway 116 can be connected to a conventional refrigerant supply, pump, or tank (not shown).

[0023] A wrench 120 is mounted in the recess 104 for axial movement in the recess 104 as controlled by a first actuator 122. The wrench 120 includes wrench flats 123 configured to engage the wrench flats 56 described above.

[0024] An O-ring 124 is mounted to the wrench 120 to seal against the sealing surface 57, and a bore 126 transmits refrigerant between the passageway 116 and the second bore 46. An O-ring 125 is mounted to the wrench 120 to seal against the housing 102.

[0025] In this embodiment, the first actuator 122 takes the form of a handle that is secured to an exposed end of the wrench. The wrench is threaded to the housing 102 as shown in FIG. 1 such that rotation of the first actuator 122 rotates the wrench flats 123 and simultaneously moves the wrench 120 axially in the recess 104.

[0026] The service fitting 100 also includes a valve core depressor 130 that in this embodiment takes the form of an elongated pin. The valve core depressor 130 is sealed in a bore of the wrench 120 by an O-ring 132. The valve core depressor 130 is threaded to the wrench 120, and a portion of the valve core depressor 130 extends beyond the first actuator 122 and is mounted to a second actuator 136. By manually rotating the second actuator 136, the valve core depressor 130 can be moved axially relative to the wrench 120, either to the left as shown in FIG. 1 to depress the stem 74 and open the valve core 70, or to the right as shown in FIG. 1 to allow the stem 74 to move to the right to close the valve core 70.

[0027] FIG. 2 shows the fittings 10, 100 prior to mating. The collar 110 has been moved to the right, and the fitting 10 can be moved in the direction of the arrow 150 to move the fitting 10 into the recess 104.

[0028] FIG. 3 provides a cross sectional view of the mated access fitting 10 and service fitting 100. Note that the balls 108 are received behind the quick release shoulder 28, thereby locking the access fitting 10 in the service fitting 100. In FIG. 2, the first actuator 122 has been rotated to rotate the wrench 120 and the twist-to-open valve 40 to open the metal-to-metal seal formed between the valve element 44 and the valve seat 22. Even though this metal-to-metal seal has been opened, refrigerant is not free to flow between the air conditioner lines 14, 16 and the passageway 116, because the valve core 70 remains closed.

[0029] In FIG. 4, the second actuator 136 has been used to move the valve core depressor 130 to the left, thereby opening the valve core 70. In FIG. 4, both the metal-to-metal seal associated with the twist-to-open valve 40 and the seal associated with the valve core 70 are opened, and refrigerant is free to flow in either direction between the air conditioner lines 14, 16 and the passageway 116. Once the desired service procedure has been completed, the actuators 136, 122 can be used to close the valve core 70 and to close the twist-to-open valve 40, respectively. Then the service fitting 100 can be removed from the access fitting 10 by manipulating the quick release mechanism 106 in the conventional manner.

[0030] The preferred embodiments described above provide a number of important advantages. The metal-to-metal seal provided by the twist-to-open valve 40 provides a substantially zero leakage rate in service. The leakage rate is not limited by the diffusion rate of refrigerant through elastomeric seals commonly used for system access valves in the past. This zero leakage feature is increasingly important as worldwide demand increases for reduced atmospheric emissions from motor vehicles and industrial equipment.

[0031] The twist-to-open and close actuation of the valve 40 provides high closure force on the metal sealing surfaces with minimal effort.

[0032] The redundant valve core 70 provides an important safety feature, assuring that service technicians do not inadvertently open the access fitting 10, releasing refrigerant into the atmosphere and creating a potential safety hazard. Access to the air conditioner system requires both that the twist-to-open valve be twisted to open it and that the valve core 70 be depressed. This is a combination of actions that is unlikely to be inadvertently accomplished simultaneously.

[0033] The lock ring provides an important safety feature. This ring prevents the valve 40 from being fully unscrewed from the valve body 12 in the event a service technician improperly over-rotates the valve 40. If the valve 40 were fully unscrewed from the valve body 12, there would be an uncontrolled release of refrigerant and the possible release of the fitting as a projectile. The locking element substantially eliminates this risk.

[0034] The service fitting provides the important advantage that mechanisms are provided for rotating the twist-to-open valve 40 and for depressing the valve core 70, all without interrupting the operation of the conventional quick connect mechanism.

[0035] The access fitting 10 is well suited for use with next-generation air conditioning systems utilizing carbon dioxide as the refrigerant. Such systems have high requirements for emission integrity and very high operating pressure and temperature. This access fitting is of course suitable for use with air conditioner systems that use other refrigerants. The access fitting can be used on either the high pressure side or the low pressure side of an air conditioner system.

[0036] Of course, many changes and modifications can be made to the preferred embodiments described above. In one alternative embodiment, the redundant valve core 70 is not provided. Zero leakage is provided by the metal-to-metal seal.

[0037] The wrench flats described above can be either internal or external wrench flats, and other out-of-round surfaces can be used. Thus, the term “wrench flat” is intended broadly to encompass any out-of-round surface (internal or external) that can be used to apply torques to the valve body 12 or the twist-to-open valve 40, and is not restricted to the specific form described above.

[0038] The actuators described above are manual handles. These handles can take any desired shape or configuration. Also, actuators suitable for use with this invention include motorized actuators including rotary motors, solenoids, hydraulic cylinders, and the like. Thus, the term “actuator” is intended broadly to encompass any manual or motorized device for imparting movement along the desired axis. Linear movement is encompassed as well as rotary movement.

[0039] The term “service fitting” is intended broadly to encompass a fitting used for any air conditioner service operation, including refrigerant charging, reclaiming and service.

[0040] The term “air conditioner system” is intended broadly to encompass any refrigerant system, and is not limited to air conditioner systems for vehicles.

[0041] Materials for the access filling 10 and the service filting 100 can be chosen as appropriate for the particular application. For example, the materials of Table 1 have been found suitable.

[0042] The foregoing detailed description has described only a few of the many forms that this invention can take. For this reason, this detailed description is intended only by way of illustration, and not by way of limitation. It is only the following claims, including all equivalents, that are intended to define the scope of this invention.