DOUBLE FUNCTION SERVICE COUPLING
Field of the Invention The present invention relates to a service coupling for use to direct refrigerant from a refrigerant supply source to a refrigeration system through a loading gate that is normally attached to the refrigeration system and in communication with the refrigerant system. that. The service coupling can also be used to evacuate refrigerant from a refrigeration system. Description of Related Matter Traditional refrigerants, such as chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons
(HCFCs), are strictly regulated due to their contribution to the depletion of ozone in the atmosphere. The search for new and environmentally benign refrigerants to replace existing CFCs and HCFCs led to the introduction of idrofluorocarbons (HFCs), such as R134a. However, HFCs still exhibit a global warming potential
(GWP) relatively high and higher usage costs compared to natural refrigerants, such as carbon dioxide and ammonia. These concerns have stimulated calls for research into alternative refrigeration systems that employ refrigerants other than HFCs. The automotive air conditioning industry has already begun to focus on the challenges of replacing HFCs, through the development of refrigeration systems that use carbon dioxide as a refrigerant. Service couplings or adapters used to direct refrigerant from a refrigerant supply source to a refrigeration system by a "charge" inlet or gate in the refrigeration system are well known in the art. A known service coupling employs one or more features that allow a "quick connection" to the load gate of the cooling system. Once connected, a service valve on the service coupling links and operates a gate valve on the loading gate to open a refrigerant flow path between the load gate and the service coupling. The service valve is typically moved into engagement with the gate valve by a knob capable of being turned which is threadably connected to the service coupling. Conventional service couplings, such as those used to service automotive air conditioning systems with R134a, are generally designed to operate at pressures up to approximately 100 psi (6.9 bar). However, refrigeration systems that use carbon dioxide as a refrigerant typically operate at considerably higher pressures than typical refrigeration systems based on R134a, ie greater than 100 psi (6.9 bars). Because of these relatively high pressures, service couplings suffer from various limitations that generally prevent their use in cooling systems that employ carbon dioxide. One limitation is that the relatively high refrigerant pressure places a considerable load on the service valve, thereby requiring an excessive amount of torque to turn the knob. Another limitation is that the "quick connect" characteristics of the service coupling become virtually inoperative due to the pressurized refrigerant trapped between the service coupling and the loading gate before disconnection. This trapped pressure also causes an undesirable and violent disconnection of the load gate service coupling. Still another limitation is that the flow rate of refrigerant through the conventional service coupling during the evacuation of a refrigeration system is relatively high. In a refrigeration system that uses carbon dioxide as a refrigerant, a relatively high evacuation flow rate can cause explosive decompression of seals, ie the undesirable, rapid expansion of gaseous refrigerant trapped in a seal. A relatively high evacuation flow rate can also lead to the formation of "dry ice" in the load gate or service coupling, which can prevent the re-seal of the service and gate valves and allow the valve to escape. refrigerant. Accordingly, an improved service coupling is required to charge and evacuate relatively high pressure refrigerant systems, such as those employing carbon dioxide. SUMMARY OF THE INVENTION A service coupling is provided for connecting a refrigerant supply source to a refrigeration system having a loading gate that includes a gate valve capable of axial displacement. The service coupling includes a body portion having a central passageway extending along an axis from an axis of adjustment to an outlet end and a lateral gate positioned between the ends, which provides communication between the way of travel. central passage and coolant source. An axially movable valve housing is disposed in the central passageway. The valve housing extends from a first end positioned between the side gate and the outlet end and a second end positioned close to the adjustment end. The valve housing includes at least one pressure balance passage extending therethrough from the first end to the second end, and a service valve sealedly linked within the valve housing. An actuator is provided to move the valve housing from a rearward position toward the adjustment end to a forward position toward the exit end. The axial movement of the valve housing to the forward position causes the service valve to stop at and disengage the sealing link gate valve in the loading gate and the sealing linkage service valve in the valve housing to open a flow path of refrigerant. The axial movement of the valve housing to the forward position also creates a gap between the second end of the valve housing and the body portion. The gap is provided in communication with the refrigerant flow path by the at least one passage extending through the valve housing, such that the pressure is substantially balanced on either side of the valve housing. The pressure balance on either side of the valve housing results in that only a minimum amount of force is required to move the valve housing within the central passageway. In another embodiment of the present invention, the service coupling is provided with at least one bleeding passage for venting pressurized refrigerant trapped between the service coupling and the loading gate before disconnection. The movement of the valve housing to the forward position seals the bleeding passage, while the movement of the valve housing to the rear position closes the flow path and allows the residual refrigerant trapped between the loading gate and the service coupling be released through the passage of unsealed bleeding. In still another embodiment of the present invention, the side gate is provided with a coupling member for connecting the service coupling to a coolant supply / drainage system. The coupling member includes a check valve or restrictor that is configured to restrict the flow of refrigerant through the side gate in a first direction and to allow substantially unrestricted coolant flow through the side gate in a second opposite direction. to the first address. In another embodiment of the invention, the load gate may include either a push type valve or a screw type valve. The valve body is an arrow having additional functionality and the valve housing comprises a safety sleeve which works in combination with the body portion rigidly positioned on the valve. The service coupling will operate in an operationally equivalent manner with any type of valve. Among other advantages, the novel design of the service coupling of the invention allows to open a flow path of refrigerant between the loading gate of a relatively high pressure system and the service coupling, with minimum effort. Another advantage is that the refrigerant trapped between the loading gate and the service coupling is automatically vented after closing the service valve and the gate valve, allowing an easy and relatively non-violent disconnection of the service coupling from the valve. load gate. Still another advantage is that the flow rate of the refrigerant being evacuated from the cooling system is easily controlled by the check valve to minimize the occurrence of explosive decompression or the formation of dry ice. Various additional aspects and advantages of this invention will be apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings. Brief Description of the Drawings Figure 1 is a cross-sectional view of a service coupling according to a preferred embodiment of the present invention attached to a loading gate of a cooling system. Figure 2 is a cross-sectional view, similar to Figure 1, showing the relative position of the parts in an open position after actuation of a service valve and a gate valve.
Figure 3 is a cross-sectional view, similar to Figure 1, showing the relative position of the parts in a closed position during disconnection of the load gate service coupling. Fig. 4 is a cross-sectional view of a coupling member, taken along lines 4-4 of Fig. 3. Fig. 5 is a partial sectional view, amplified, of the loading gate of the Figs. 1-3. Figure 6 is a cross-sectional view of an alternate embodiment of the present invention, showing the service coupling attached to the loading gate with the service valve and the gate valve in the open position. Figure 7 is a cross-sectional view of the service coupling of Figure 6, showing the service valve and the gate valve in the closed position. Figure 8 is a cross-sectional view of another alternate embodiment of the present invention, showing the service coupling attached to the loading gate with the service valve and the gate valve in the open position. Fig. 9 is an enlarged, cross-sectional view of yet another alternate embodiment of the present invention, showing the relative position of a locking sleeve, a pin and a valve housing during disconnection of the gate service coupling of cargo. Figure 10 discloses an embodiment of a dual-function service coupling for use with either a push type or screw type loading gate, showing the service coupling in an unlinked state. Figure 10A is an amplified potion of the service coupling of Figure 10. Figure 10B is an amplified portion of the service coupling of Figure 10. Figure 11 discloses the embodiment of Figure 10 with the knob in the state linked, without being connected to the loading gate. Figure 12 discloses the embodiment of Figure 10, with the service coupling linking the loading gate. Figure 13 discloses the embodiment of Figure 10, with the service coupling linking the loading gate and the knob in the linked state to allow fluid flow. Figure 14 is an alternative embodiment of a dual-function service coupling. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to Figure 1, a service coupling 20 is provided to be attached to the loading gate 22, which functions as an inlet for the refrigerant being introduced to a cooling system. to which the load gate 22 is connected. When attached, the service coupling 20 and the load gate 22 exhibit a common longitudinal axis AA. The loading gate 22 can be of a conventional type and, by itself, does not form part of the present invention. However, a general understanding of the loading gate 22 will help explain the operation of the service coupling 20. The loading gate 22 includes a body 24 having a central passage 26 extending therethrough from an inlet end 28 at an outlet end 30. As illustrated in Figure 5, the central passage 26 includes a cylindrical valve seat, of reduced diameter 32, and internal threads 34 for linking a sealing polymer element 36 and external threads 38, respectively, of a valve core 40. Referring still to FIG. 5, the valve core 40 includes a core body 42 within which a gate valve 4 is disposed in a slidable manner. A first end 46 of the gate valve 44 extends outwardly beyond the core body 42 and a second end 48 of the gate valve 44 is connected to a sealing member 50. A compression spring 52 extends between a annular lip 54 of the gate valve 44 and a radial shoulder 56 in the core body 42 to deformably urge the gate valve 44 toward the inlet end 28 and to cause the sealing member 50 to seally bond the core body 42. The movement of the gate valve 44 towards the outlet end 30 (on the left, as seen in Fig. 5) disconnects the sealing member 50 from the core body 42, thereby opening the valve core 40 (as shown in Fig. 2) to allow the flow of refrigerant through the gate of the valve. load 22. Referring to Figure 1, the service coupling 20 includes a body portion 58 extending from an adjustment end 60 to an exit end 62. A central passage 64 extends from the adjustment end 60 to the outlet end 62 and communicates with the side supply hose gate 66 formed in the body portion 58 between the adjusting end 60 and the exit end 62. Externally arranged threads 68 are formed in the body portion 58 adjacent the adjustment end 60. A knob capable of rotating 70 is disposed at the adjustment end 60 and includes internal threads 72 which are engaged with the threads 68 and an enlarged grip portion 74 extending axially beyond the adjustment end 60. The central passage 64 of the body portion 58 is provided with a first internal diameter 76 in the vicinity of the adjustment end 60, a second internal diameter 78 in the vicinity of the exit end 62 and an enlarged annular channel. 80 aligned with the side gate 66. Positioned within the central passage 64 is a valve housing 82 sized to be loosely received but slidable inwardly of the first internal diameter 76. The valve housing 82 includes a generally cylindrical body 84, which has a common central axis with the axis AA, and an adjustment post 86 projecting outwardly of the body 84 along the axis AA. The body 84 includes an internal cavity 88 within which a shoulder 90 and internal threads 92 extend inwardly. A plurality of flow holes 94 are disposed through the body 84 and intersect the cavity 88 at a substantially right angle with respect to the body. of the AA axis. Body 84 also includes at least one pressure balance passage 96 (showing phantom line in Figures 1-3), which extends from one end of body 84 to the other. The passage 96 is disposed between the flow holes 94 such that the passage 96 and the flow holes 94 do not intersect. The valve housing 82 is connected to the knob 70 for movement therewith, when the knob 70 is screwed in and out of the body portion 58. In a preferred embodiment, a portion of the adjusting post 86 extends through the a hole 98 in the body portion 58 and an axially aligned hole 100 in the knob 70. A pair of sheaves 102 is provided on the adjusting post 86 on each side of the knob 70. During the manufacture of the service coupling 20, a distal end 104 of the adjusting post 86 is engaged or otherwise deformed to prevent the sheaves 102 and the knob 70 from slipping out of the adjusting post 86 during rotation. The rollers 102 slide against the knob 70, allowing the knob 70 to rotate freely with respect to the adjusting post 86. The rotation of the knob 70, and its axial movement resulting from the inter-engagement of the threads 68 and 72, cause the valve housing 82 (1) moves axially to a rearward position toward the adjusting end 60 (to the right in Figures 1-3) upon rotation of the knob 70 in a first predetermined direction, and ( 2) moves to a forward position towards the exit end 62 upon rotation of the knob 70 in the opposite direction. Excessive retraction of the valve housing 82 towards the adjustment end 60 is prevented by the stop of the valve housing 82 with a shoulder 106 formed in the body portion 58 between the first internal diameter 76 and the hole 98. Depending on the diameters external of the loading gate 22 and the valve housing 82, a body portion 58 can optionally be divided into two or more sections to facilitate the assembly of the service coupling 20. As illustrated in figures 1-3, the body portion 58 is preferably divided into a first section 108 that includes the first internal diameter 76 and a second section 110 that includes the second internal diameter 78. The second section 110 includes an internally threaded portion 112 that is threaded on an externally threaded portion 114 of the first section 108 during assembly. In the embodiment illustrated in Figures 1-3, because the outer diameter of the valve housing 82 is larger than the second internal diameter 78, the valve housing 82 is assembled in a first section 108 before securing the second section 110 to the first section 108. However, in an alternate embodiment of the present invention (not shown), the valve housing 82 may exhibit an external diameter that is smaller than the second internal diameter 78, allowing the Body portion 58 is manufactured as a single member. Received within the cavity 88 of the valve housing 82 are a sealing member 116 and a service valve 118 which is biased against the sealing member 116 by means of a member capable of compressing resiliently 120, such as a spring. compression. The sealing member 116, which is preferably made of a polymeric material, such as EPDM or PTFE rubber, abuts on the inwardly directed shoulder 90. The sealing member 116 is preferably a flat, annular gasket, as illustrated in FIG. 1-3, or alternatively, may be a ring at 0. The service valve 118 includes a generally conical seat 122 extending therefrom sealingly attaching the sealing member 116 to substantially prevent the flow of refrigerant. through the service coupling 20. One end of the member capable of being resiliently compressed 120 abuts on a shoulder 124 of the seat 122 and the other end abuts on an internal wall 126 of the cavity 88. A valve detent 128 is also received in the cavity 88, to secure the sealing member 116, the service valve 118, and the member capable of being resiliently compressed 120 within the cavity 88 of the valve housing 82. valve retainer 128 preferably includes a guide portion 130, through which the service valve 118 extends, and a cylindrical base portion 132 having external threads 134 that engage internal threads 92 in the cavity 88. The portion guide 132 is a generally rectangular member having a width large enough to hold the service valve 118, but sufficiently narrow to allow passage of coolant, as illustrated in Figure 2. The base portion 132 of the valve retainer 128 it abuts on the sealing member 116 to maintain the sealing member 116 against the shoulder 90. Referring to FIGS. 6 and 7, an alternate embodiment of the valve housing 82 is shown in detail. In this embodiment, the service valve 118, sealing member 116 and valve retainer 128 comprise a valve core assembly 138. Valve core assembly 138 can be susta substantially similar to the valve core 40 described above in the loading gate 22, but is not necessarily limited thereto. Accordingly, other valve core assembly designs, such as those commonly found in rods, may also be suitable for use in the present invention. Employing the valve core assembly 183 in place of the individual components 116, 118 and 128 advantageously eliminates one or more manufacturing steps and allows easy replacement of worn or damaged seals. Referring again to Figure 1, an annular sealing element 140 is disposed in a first outwardly directed slit 142, positioned in an inner wall of the bore 98, to substantially prevent the escape of refrigerant when the valve housing 82 is moved. to the forward position towards the exit end 62. Similarly, a pair of annular sealing elements 144 is provided in the body portion 58 on the side of the fitting end and the outlet end side of the side gate 66. The sealing elements 144 abut in the valve housing 82 and substantially prevent the passage of refrigerant between the body portion 58 and the valve housing 82. The sealing elements 140 and 144 may be a typical rubber O-ring or a "spring-loaded" cup, PTFE, as It is known in the field. The body portion 58, and more particularly the second section 110, preferably includes an inwardly directed shoulder 148 against which an annular sealing member 150 is maintained, such as an O-ring. The sealing member 150 links in a sealed manner the loading gate 22 when received in the service coupling 20 to seal against the coolant leakage between the loading gate 22 and the service coupling 20. The sealing member 150 is restrained against substantial axial movement within the passage 64 through the shoulder 148 and an elastic adjusting ring 152 which is received within an outward facing groove 154 in the first internal diameter 76. Referring now to Figure 3, the side gate 66 is preferably provided with a coupling member 156 for connecting the service coupling 20 to a coolant source (not shown). In a preferred embodiment, an outer end 158 of the coupling member 156 is configured to mate with a female coupling 160 that is attached to an attachment 161 of a service hose or other conduits, to transfer refrigerant from a conventional supply system / coolant evacuation. The design of the coupling member 156 illustrated in Figures 2 and 3 is not intended to limit the scope of the invention, and may include other configurations, such as a conventional female threaded adapter. A check valve or restrictor 162 is arranged within the coupling member 156 to regulate the flow rate of refrigerant exiting the loading gate 22 through the service coupling 20. Referring to Figure 4, the restrictor 162 includes an axial capillary duct 166 having a predetermined diameter corresponding to the desired coolant flow rate. The restrictor 162 is provided with a plurality of radial fins 168 that cooperate with an inner surface 170 of the coupling member 156 to create a plurality of flow channels 172 (best observed in Figure 4) for the free flow of refrigerant. A gap 174 (best observed in Figure 3), which is defined between a tapered surface 176 of the coupling member 156 and a shoulder 178 of the female coupling 160, allows a limited degree of axial movement of the restrictor 162. As illustrated in FIG. 2, when the flow of refrigerant is entering the service coupling 20 from the refrigerant supply / discharge system, the restrictor 162 is forced against the tapered surface 176, allowing a substantially unrestricted flow of refrigerant through the channels of the refrigerant. flow 172. Alternatively, when the flow of refrigerant is entering the service coupling 20 from the loading gate 22, the restrictor 162 is forced against the shoulder 178, thereby restricting the flow of refrigerant through the capillary 166. Referring again to FIG. 1, a service coupling 20 is preferably connected to the loading gate 22 by a plurality of b. stop waves 180 located within radial holes 182 defined in the wall of the body portion 58 adjacent to the exit end 62. An annular closure sleeve 184 surrounds the body portion 58 adjacent the exit end 62 and is axially slidable in she. The closure sleeve 184 is provided with an inwardly facing flange 186 having a conical cam surface 188 that flares outwardly thereof in a direction toward the exit end 62. A resilient member 190, such as a compression spring or the like, biases the closure sleeve 184 towards the exit end 62. Extending radially outwardly from the flange 186 is a shoulder 192 cooperating with an outwardly directed flange 194 in the body portion 58 to define a chamber 196 within which the resilient member 190 is positioned to deformably urge the sleeve 184 toward the exit end 62. The area of the body portion 58 adjacent the flange 194 is preferably provided with a slit. inwardly facing annular 198 in which a retaining ring 200 is placed. The retaining ring 200 abuts both the flange 194 and a shoulder 202 on the closure sleeve 184, as shown in Figure 1, to prevent the removal of the closure sleeve 184 from the body portion 58. Alternatively, or in combination with a retaining ring 200, a second retaining ring 204 may be disposed in a slit. ura 206 near the outlet end 68, which also functions to prevent removal of the closure sleeve 184 from the body portion 58. The service engagement 20 is preferably provided with a interlock sleeve 208 to prevent accidental release of the coupling. of service 20 of the loading gate 22 when the refrigerant flow path is open. Referring to Figures 1-3, the interlock sleeve 208 is a generally cylindrical member having an internal diameter 210 that is slightly larger than the outer diameter 212 of the body portion 58. The interlock sleeve 208 is provided with a channel 214 having a width slightly larger than the diameter of coupling member 156. A first end 216 of the interlock sleeve 208 links the closure sleeve 184 and a second end 218 of the interlock sleeve 208 links the knob 70. Referring to FIG. Fig. 2, when the knob 70 has been rotated to a position that causes the service valve 118 and the gate valve 44 to open, the interlock sleeve 208 abuts the closure sleeve 184 to prevent the closure sleeve 184 is retracted to a position to be released by the loading gate 22. On the other hand, as illustrated in FIG. 3, when the knob 70 is rotated to a position that closes the service valve 118 and gate valve 44, the interlock sleeve 208 can be slid over the body portion 58 to a position that allows the closure sleeve 184 to release the loading gate 22. In operation, when the service coupling is disengaged from the loading gate 22, the closure sleeve 184 will be in its non-retracted or forward position shown in Fig. 2 and maintained in such position by means of the biasing force of the resilient member 190. The service coupling 20 is connected to the loading gate 20 by retracting the closure sleeve 184, as shown in FIG. 3, which allows the stop balls 180 to move outwardly by linking the service coupling 20 to the load gate 22. By linking the service coupling 20 the loading gate 22, the entrance end 28 of the loading gate 22 will enter the outlet end 62 of the service coupling 20 and will bond in a manner the sealing member 150 is sealed. Additional axial movement of the loading gate 22 towards the adjusting end 60 causes the stop balls 180 to go over a shoulder 220 in the loading gate 22 until the stop balls 180 are radially in line with a slit 222 of the loading gate 22. The stop balls 180 are forced radially inward as a result of urging the closure sleeve 184 towards the exit end 62 in response to urging the resilient member 190 and the action of the conical cam surface 62 which forces the stop balls 180 radially inward. The stop balls 180 link one side of the shoulder 220 that is further removed from the inlet end 28 of the loading gate to secure the service coupling 20 to the loading gate 22. With the service coupling 20 and the loading gate 22 linked in this way, as illustrated in Figure 1, it should be noted that there is no refrigerant flow through the joined parts. In this way, inside the loading gate 22, the sealing member 50 is sealedly connected to the core body 42, and inside the service coupling 20, the service valve 118 is sealedly linked to the member. Sealing 116. Prior to opening the service valve 118 and the gate valve 44, the service coupling 20 is pressurized by the service hose or other conduit that is attached to the refrigerant supply / discharge system. Sealing members 144 on each side of the side gate 66 prevent refrigerant from passing between the body portion 58 and the valve housing 82. Accordingly, there is no pressing force acting axially on the valve assembly 82 which inhibits the rotation of the valve. the knob 70 to open the service coupling 20. To open the service coupling 20 and the loading gate 22 to the coolant flow through the side gate 66, the knob 70 is rotated in a first predetermined direction, causing the knob 70 moves axially to the position shown in Figure 2. Such rotation of the knob 70 does not cause substantial rotation of the valve housing 82 as a result of the resistance of the friction to such rotation by virtue of which the valve housing 82 is in contact with the sealing members 140 and 144. The axial movement of the valve housing 82 from the position of FIG. 1 to the position of FIG. ura 2 causes the service valve 118 to directly link the gate valve 44. Once the service valve 118 makes contact with the gate valve 44, there is some resistance to additional axial movement of the valves 118, 44, due to pressure in the cooling system acting against the gate valve 44. However, this resistance is generally not significant due to the relatively small diameter of the gate valve 44. Referring to Fig. 2, when starting to open the valves 118 and 44, a first cavity 224, which is formed between the loading gate 22 and the valve housing 82, is rapidly filled with pressurized refrigerant. Virtually simultaneously, the passage 96 allows a second cavity or recess 226, formed between the valve housing 82 and the shoulder 106, to reach the same pressure. The substantially balanced pressure on each side of the valve housing 82 results in only a minimum axial force being applied (generally the combined biasing force of the compression valve springs) to the knob 70. Accordingly, an acceptable amount of torque is all that is required to rotate the knob 70. The complete rotation of the knob 70 in the first predetermined direction causes the service valve 118 and the gate valve 44 to be driven to the fully retracted or "open" positions. , allowing full flow of refrigerant. Depending on the biasing force exerted against both the service valve 118 and the gate valve 44, it is possible that the service valve 118 is not driven to the fully "open" position. To ensure that the service valve 118 is fully actuated, a pin 228 can be provided through the portion of the service valve 118 that extends outwardly beyond the valve housing 82. During the insertion of the loading gate 22 in the service coupling 20, the inlet end 28 of the loading gate 22 will link the pin 228 and operate the service valve 118 to the fully "open" position shown in figure 2. In order of disconnecting the service coupling 20 from the loading gate 22, it is simply necessary to turn the knob 70 to close the valves 118, 44 and manually retract the sleeve 184 to the position shown in Figure 3. This retraction moves the shoulder 188 of the closure sleeve 184 out of engagement with the stop balls 180 and thereby aligns the stop balls 180 with the cylindrical wall enlarged 182, allowing the stop balls 180 to move radially outwardly to disengage them from the shoulder 220 of the loading gate 22. However, manual retraction of the closure sleeve 184 is made difficult, if not impossible, by the pressure of the refrigerant trapped in the first cavity 224. The trapped refrigerant exerts an axial force on the loading gate 22, which is re-directed to the closing sleeve 184 by the stop balls 180. Therefore, it is necessary to vent the pressure trapped in the first cavity 224 before disconnecting the service coupling 20. To reduce the pressure in the first cavity 22, a pressure bleeding passage 230 is provided between the first cavity 224 and the outside of the service coupling 20. In a preferred embodiment of the present invention, the pressure bleeding passage 230 extends between the channel 96 and an outer surface of the adjustment post 96, as illustrated in FIGS. and 3. When the valve housing 82 is moved to the forward position towards the outlet end 62, the pressure bleeding passage 230 assists the longitudinal channels 96 to provide the first cavity 224 in communication with the second cavity 226, as is shown in Figure 1. When the valve housing 82 is moved to the rearward position toward the adjustment end 60, the pressure bleeding passage 230 extends beyond the sealing member 142, as shown in Figure 3. , allowing the pressure in the first cavity 224 to be ventilated to the environment. The release of refrigerant to the environment is extremely small, as is characteristic of conventional service couplings. In an alternate embodiment, as illustrated in FIG. 8, a pressure bleed passage 230 'or 230"may be provided through the adjustment post 86, such that the pressure in the second cavity 226 is ventilated to the environment when the valve housing 82 is moved to the rear position, alternatively, or in combination with the bleeding passage configurations illustrated in FIGS. 1 and 8, at least one bleeding passage 232 can be provided directly through the body portion 58 for venting the pressure in the first cavity 224 to the environment, as illustrated in Figures 6 and 7. In this embodiment, an additional sealing member 234 is required in the body portion 58 downstream of the passageway. of pressure bleeding 232 for sealing against the valve housing 82, when the valve housing 82 is moved to the forward position When the valve housing 82 is retracted to the rear position towards the adjustment end 60, as shown in FIG. 7, the sealing member 234 is disengaged from the valve housing 82, allowing the pressure trapped in the first cavity 224 to escape through the bleeding passage 232. Referring to FIG. Figure 8, another alternate embodiment of the present invention is shown in detail. In this embodiment, the service coupling 20 is provided with a nut capable of rotating 236 instead of a locking sleeve 184 capable of retracting, to secure the service coupling 20 to the loading gate 22. The nut 236 is provided with an internally threaded surface 238 that engages an externally threaded surface 240 of the loading gate 22. The nut 236 also includes an anchor portion 241 that links an inwardly directed slot 242 in the body portion 58. The anchor portion 241 allows the nut 236 to rotate with respect to the body portion 58, but prevents axial movement therein. To prevent accidental release of the loading gate 22, the interlock sleeve 208 may be provided with an internally hinged surface that links an externally hinged surface (neither of which is shown) to the nut 236 as the interlock sleeve 208 moves forward due to the rotation of the knob 70. Referring to Figure 9, an alternate embodiment of the present invention is shown in detail. In this embodiment, the service coupling 20 does not include a interlock sleeve 208 to prevent accidental release of the loading gate 22. Instead, a radially movable pin 244 is provided in the body portion 58 that is extends radially outwardly when the valve housing 82 is driven towards the outlet end 62 to prevent the closure sleeve 184 from sliding to a position that releases the loading gate 22. As illustrated in Figure 9, an inner end 246 of the pin 244 is provided with a beveled head portion 248. The coolant leak is substantially prevented by the use of at least one sealing member 250, such as an O-ring, between the pin 240 and the body portion 58. The valve housing 82 is provided with a beveled end 252 that connects the head portion 248 as the valve housing 82 moves to a forward position toward the exit end 62. This bonding, either alone or in combination with the refrigerant pressure present between the valve housing 82 and the body portion 58 due to the opening of the service valve 118 and the gate valve 44, causes the pin 244 to move outward until a portion of the pin 224 protrudes from the body portion 58. The protruding portion of the pin 244 engages and prevents accidental retraction of the closure sleeve 184 when the valves 118 and 44 are opened. Once the valve housing 82 is moved to a rearward position toward the adjustment end 60 and the valves 118 and 44 are closed, the closure sleeve 184 can be retracted, causing the pin 244 to be pushed toward the body portion. 58. An alternative, additional embodiment of the present invention, with a double function service coupling 20 ', is disclosed in Figures 10-14. In the embodiments discussed above, the male load gate 22 'includes a push pin type valve 44. However, in some circumstances it is desirable to incorporate a screw type valve, as described below. Also, in the embodiments discussed above, the "valve assembly" consists of a valve housing 82 that is axially moved by direct connection to the knob 70. The housing 82 contains the spring loaded valve 118 with the dowel pin 228 that is opened by thrust action by the body of the male service gate and in turn opens the male service gate valve by pushing action. The embodiment discussed below differs in that the "valve assembly" consists of an arrow that is moved axially by direct connection to the knob. A spring-loaded safety sleeve worked in conjunction with the arrow to carry out the function of the valve. The safety sleeve is opened when it contacts the end of the male service hatch, while the male service gate valve is opened by thrusting by the shaft. Follow a more detailed description. The common actuator is the knob. A more detailed description of the embodiment now follows, including specific numbers of elements based on the included figures. The screw type valve 302 includes the use of mating threads 303, 304 between the inner peripheral surface of the gate 22 'and an outer peripheral surface of the valve, for retaining the valve within the loading gate. The threads 303, 304 are threaded in a first direction (eg, on the left) while the threads associated with the arrow are threaded in the opposite direction (eg, on the right). A retaining ring 305 is also illustrated to prevent accidental uncoupling of the valve 302 from the gate 221 if the valve 302 continues to be unscrewed from the gate 22 'with an end bevel of the threads 304 linking the ring 305. A peripheral surface internal 306 of valve 302 and an outer peripheral surface 307 on a nose portion 356 of an arrow 350 are hexagonal, mating traction elements, which may be considered "Alien", "Torx" or any other suitable design. When the hexagonal drive engages, the non-circular male and female elements 306, 307 allow rotational movement of the valve 302 with respect to the gate 22 'via the threads 303, 304, to cause longitudinal movement of the valve 302 within of gate 22 'along axis AA. The coupling 20 'is designed to work in an operationally equivalent manner where the thrust pin valve 44 or screw type valve 302 is incorporated in the load gate 22'. Therefore, a service technician does not need to know or know what type of load gate valve is incorporated in the system. For purposes of discussion, portions of both types of valves are illustrated in the loading gate 22 'of the figures of the drawings, but as a practical matter, one or the other of the valves will typically be incorporated in the loading gate. The numbers of the elements previously introduced are incorporated in the coupling 20 'to the extent that it is practical and have the same purpose discussed above, unless otherwise indicated. As best seen in Figures 10, 10A and 10B, the service coupling 20 'includes a body portion 58' extending from an adjustment end 60 to an exit end 62 and held rigidly in position. Once again, the body portion 58 'includes two sections 108' and 110, where the section 110 is essentially identical to the one discussed above. Section 108 'has several differences, however. First, it is somewhat "J" shaped in cross section, with a radially outer leg, extending longitudinally 308, defined between an internal surface defined by an internal diameter 76 and an external surface defined by an external diameter 212. The leg 308 includes at least one flow hole 94 extending therethrough between the outer and inner surfaces, with radial slits 310 disposed on each side of the holes 94 toward the inner surface, with radial slits 310 disposed on each side of the holes 94 towards the inner surface, which are adapted to receive annular seal elements AB. Although elastomeric O-rings are shown, it may be necessary to use other types of seals, such as the "spring-loaded" cup, PTFE, discussed above, particularly for a C02 application to eliminate explosive decompression. A frame 312 connects the leg 308 to a shorter, radially inner leg 314, which ends at an end 316 separated longitudinally away from both slits. In a three-dimensional manner, the elements 308 and 314 are generally cylindrical, the element 314 being radially inward of the element 308, the weft 312 being disposed therebetween. In this way, the two legs 308, 314 and the frame 312 define a cavity 312, ending within the cavity 318. A resilient member 322, such as a spring, is retained within the cavity 318 with a first end that links the weft 312 and a second end extending longitudinally out of the cavity. A safety sleeve 324 acting as the valve housing is disposed adjacent the end 316 of the leg 314 and in face contact with the inner surface of the leg 308 outside the cavity 318. A radially external surface 326 links the elements of sealed A and B. The safety sleeve 324 is defined between a first end 328 and a second end 330, one or more bleeding holes 332 extending longitudinally through the safety sleeve between the two ends 328, 330. The second end 330 is in selective contact with the end 316 of the leg 314 of the body portion and is in constant contact with the spring 322, and is biased towards a closed position and towards the loading gate 221, as described further below. The safety sleeve 324 also includes one or more flow holes 334 extending from the outer surface 326 and ending in an internal radial surface 336. The flow holes 334 do not intersect the bleeding holes 332. The safety sleeve 324 has a portion of thin nose 338 adjacent the first end 328. A transition zone including an angled bevel 340 and an apex 342 with a longitudinally extending flat surface is disposed between the nose portion 338 and the flow holes 334. Preferably, the apex 342 includes an inner diameter smaller than inner radial surface 336. When end 330 of safety sleeve 324 is in contact with end 316 of leg 314 of the body portion, selective interaction between bevel 340 and apex 342 in combination with the sealing element D limits the backward movement of an arrow 350. The radially internal surfaces of the sleeve 324 adjacent the second end 330 and the adjacent end 316 of the leg 314 include a slit 343 adapted to retain the sealing elements C and F, respectively. The sealing elements C and F are disposed on each side of the interface point between the safety sleeve 324 and the leg 314 in part to prevent the flow of fluid into the cavity 318 when the safety sleeve links the leg to seal the cavity , with the exception of the bleeding holes 332. Additional features of the sealing elements are discussed further below in combination with the functional position of the service coupling 20 '. A longitudinally extending arrow 350 acts as a service valve 118, but includes additional functionality as well. It is received in an inner passageway defined by the safety sleeve 324 radially inward from the pressure balancing passage 328. The arrow 350 extends between a first end 352 and a second end 354. The hexagonal member 307 is disposed in a outer surface of the arrow 350 adjacent the first end 352, and adapted to mate with the corresponding complementary hexagonal member 306 of the valve 302 to open and close the loading gate 22 'when this type of valve is included, as discussed in FIG. more detail later. When a push pin type valve 44 is used, the first end 352 links the valve to open and close the valve, as also discussed in more detail below. The arrow 350 includes a nose portion 356 adjacent the first end 352, having an outer diameter with a transition zone defined by an angled bevel 358 and an apex 360 adjacent the hexagonal member 307. The apex 360 has an outer diameter greater than diameter of nose portion 356 and a flat portion extending longitudinally. A slit 362 is disposed adjacent the transition zone, with an abruptly angled shoulder, generally perpendicular 364 adjacent the apex 360 defining one of the walls of the slit. A sealing member D is disposed against the shoulder 364. Typically, the sealing member D is attached to the shoulder 364. However, a slit-like arrangement can also be used. The relative diameters of the apex 334 and 360, respectively, as well as the relative longitudinal positions of the transition zones of the safety sleeve 324 and the arrow 350, respectively, result in selective bonding of the sealing member D against the bevel 340., as discussed in more detail later. The arrow 350 threadably links the leg 314 of the section 1081 of the valve body adjacent the frame 312, using threads 370, 372, which are threaded opposite the threads 303, 304 to allow longitudinal movement of the arrow with respect to the valve body 58 '. As best seen in Figure 10B, disposed between the threads 370, 372 and the arrow end 354 are one or more circumferentially spaced, outwardly extending traction pins 374, disposed within mating holes within the arrow 350. The traction pins 374 are adapted to link traction slots 376 disposed within a knob capable of rotating 70 '. Positioned between and extending from the traction pins 374 and the arrow end 354, an arrow sleeve 378 is pinned or otherwise secured to the arrow 350, and includes a front slit 380 with a generally perpendicular, angled front wall. abruptly 382, a substantially angled ramp 384 forming the rear wall of the front slit, an apex 386 with a flat portion extending longitudinally adjacent the ramp 382 and a shoulder 388 having a shallower angle than the ramp 384 adjacent to the other longitudinal end of the apex, and ending in a rear slot 390 having an abruptly angled, generally perpendicular wall 392 at the end opposite the slot. The arrow 350 may include the elements directly included, rather than relying on the use of the arrow sleeve 378. The knob 70 'includes a simple retaining ring groove 394, adapted to receive a retaining ring 396 such that when it moves longitudinally the , knob between a linked position and a disengaged position, the retaining ring 396 is moved between the front slit 380 and the rear slit 390, as discussed in more detail below. The arrow sleeve 378 is included in the illustrated embodiment to allow flexibility in sizing the retaining ring that controls torsion, but may not be needed. An internal radial surface 392 of the knob 70 'includes two longitudinally disposed slits 393 adapted to retain the sealing members G and H. The members G and H selectively link the external surface of the section leg 308 of the body portion. 58 'and are defined by the diameter 212 in part to provide a fluid proof seal when the vent hole 320 is disposed therebetween. A longitudinally inner end 398 of the knob 70 'includes an optional bevel 400, such that when the knob 70' is in its fully retracted orientation, the ventilation holes 320 are open to the outside environment. Figure 10 shows the dual function service coupling 20 'in a disconnected orientation with the knob 70' fully retracted. Seals A through D work in conjunction to prevent leakage of the pressure supply hose gate 66, regardless of the position of the knob 70 '. Prior to attachment to the loading gate 22 ', the coupling 20' is often pressurized through the supply hose 450 which is attached to the service equipment. The seals A and B on each side of the flow holes 94 are sealing on the same diameter and prevent leakage between the safety sleeve 324 and the body portion 58 '. The seals C and D prevent leakage between the arrow 350 and the safety sleeve 324. This sealing arrangement results in the safety sleeve 324 being substantially pressure balanced, such that only the biasing force of the resilient member 322 is acting. to keep the safety sleeve sealed with seal D in a closed position. Such orientation minimizes the rotational force required to rotate knob 701. In the position of Figure 10 or 11, the other four seals E to H are not pressurized. In Figure 10, the knob 70 'is fully retracted with the knob retaining ring 396 placed in the rear slot 390 of the arrow sleeve 358, which in turn is rigidly connected to the arrow 350. The traction pin 374 retained in the arrow 350 and, optionally all the way through it, is disengaged from the corresponding traction slots 376 in the knob 70 '. In this way, the knob 70 'can be rotated freely. The vent hole 320 is uncovered, allowing any trapped pressure to escape when the knob 70 'is moved to the position shown after service. The release sleeve 184 can be retracted to allow connection or disconnection to the male load gate 220, as discussed above. Figure 11 discloses the functionality of the safety sleeve 324. In the drawing, the knob 70 'is advanced from its disengaged position, but the valve is still closed as in Figure 10. The loading gate 22' is not connected to the coupling. twenty'. The vent hole 320 is closed, and sealed between sealing elements G and H received in slits 393 in an inner circumferential surface of the knob 70 '. The retaining ring 396 is disposed in the front groove 380 and the retaining pins are received within the traction grooves 376. However, no undesirable pressure release has taken place. This is because the safety sleeve 324 is loaded by the spring 322 to a closed position and will always remain in its closed position, as illustrated, regardless of the position of the knob 70 ', when it is not secured to the gate. load 22 '. In Figure 12, the coupling 20 'is shown connected to the loading gate 22'. During this connection, the hexagonal elements 306, 307 are linked, if applicable, such that a rotation of the arrow 350 clockwise results in a longitudinal movement of the valve 302 toward the end 328 of the sleeve of the valve. safety 324. In the case of thrust pin valve 44, nose portion 356 of arrow 350 includes a bevel 452 adapted to link end 454 of valve 44 when arrow 350 has been advanced sufficiently to link and move valve 44 to the left in the figure of the drawing. In the drawing figure, insufficient longitudinal feed has resulted in mutual bonding. The knob 70 'has been pushed forward, longitudinally, with minimal effort, until the retaining ring 396 travels in the low angled shoulder 388 out of the slot 390, on the apex 386 and towards the front slit
380. During this movement, the traction pin 374 links a mating traction slot 376 in the knob 70 'such that any rotation of the knob in the clockwise direction will rotate and advance the arrow 350 due to the pairing linkage of the knob. the threads 370, 372 between the arrow 350 and the body portion 58 '. Further, by pushing the knob 70 'forward, the vent hole 320 is sealed, as discussed with respect to Figure 11. Figure 13 shows the coupling 20' in the joined and open position. The interlock sleeve 208 operates in combination with the closure sleeve 184, as discussed above. Compared to FIG. 12, the knob 70 'has now been turned clockwise to cause the arrow 350 to advance towards the secured gate 22'. If the coupling 20 'is attached to the screw-type valve 302, the screw will be rotated and loosened about three (3) turns, until one or more crossed pins 456, extending radially outwardly from the arrow 350, and just adjacent to the bevel 358, link the end 28 of the gate 221. Because the threads 303 are on the left when the corresponding arrow threads 370, 372 are on the right hand side, the valve 302 will pull back as the arrow 350 advances, giving as a result an increased bonding of the hexagonal traction. On the other hand, if the coupling 20 'is attached to the thrust pin valve 44, the bevel 452 of the arrow 350 will move the end 454 of the valve 44 to an open position. The process works as follows: by turning the knob 70 'clockwise from the position shown in Fig. 12 to the position shown in Fig. 13, the safety sleeve 324 initially moves with the arrow until the end 328 makes contact with the end 28 of the gate 22, and the bevel 452 on the arrow links the end 454 of the valve 44. At this point, the continued advancement of the arrow 350 to the left results in the sleeve 324 moves from its closed position to an open position against the force of resilient member 322, causing seal D to disengage the seal in safety sleeve 324 and, at approximately the same time, arrow 350 opens by thrusting action the valve in the gate 22 '. This releases pressure to the cavity 458. The pressure in the cavity 458 is free to pass through the pressure balancing hole (s) 332 in the safety sleeve 324 and, consequently, the cavity 318 rapidly generally reaches the same pressure. (with the limited exception of a small area at the end 354 of arrow 350). The end 28 does not block the bleeding holes 332. The cross pins 456 selectively link the end 28 to limit the displacement of the arrow 350. The balanced pressure means that only a minimum force is required to turn the knob 70 '. In the open orientation, seal E prevents leakage between body portion 58 'and male load gate 221. Seal F prevents leakage between body portion 58' and arrow 350. Seals G and H prevent leaks between the external diameter 212 of the body portion 58 'and the knob 70'. The seals G and H are positioned on either side of the bleed hole 320 to provide pressure balance, to minimize the effort required to move the knob 70 '. Seals A to D are pressurized from all sides, but do not perform any necessary sealing function. After service, the knob 70 'is turned counterclockwise to close the valves. If attached to the screw type valve 302, arrow 350 will turn the knob until the screw valve is seated properly. Additional rotation of knob 701 will apply a predetermined torque value to the screw, as follows. The linking feature of the knob 70 'is in the form of a "sawtooth", with at least two teeth that link the traction pin 374 through the arrow 350. When the knob 70' is rotated in the direction counterclockwise, the pin 374 travels at the angle defined by the sawtooth with a cam effect. This tends to force the pin 374 out of engagement with the knob 70 '. Resisting this action is the retaining ring 396 retained in the front slot 380 of the arrow sleeve 358. At a predetermined torque value, the retaining ring 396 is forced to the relatively high angle of the ramp 384 and on the apex 386 by then. travel down the shoulder 388 towards the rear slit 390. This allows the knob 70 'to move backward relative to the arrow 350, again discovering the vent hole 320. The knob 70' is free to rotate. If the loading gate 22 'includes a push pin valve 44, the arrow 350 retracts until the safety sleeve 324 makes contact with the body 58' via the bond between the sealing member D retained in the groove. 362 of the arrow 350 and the bevel 340 of the safety sleeve 324. Additional rotation of the knob 70 'disengages the knob of the arrow 350, as discussed above for the threaded type valve.
The bleed hole 332 connects between the cavities 458 and 318 and allows the trapped pressure to be released between the loading gate 22 'and the service coupling 20' when the knob 70 'discovers the ventilation hole 320. An alternative embodiment of the coupling 20 'is illustrated in Figure 14, where the vent hole 320' is disposed within the interior of the arrow 350 'more than as shown in Figures 10-13. A vent hole seal 460 slides from the arrow 350 'when the knob 70' moves back to the retracted position to allow atmospheric release of pressure. Although certain preferred embodiments of the present invention have been described, the invention is not limited to the illustrations described and shown herein, which are believed to be merely illustrative of the best ways of bringing the invention into practice. A person skilled in the art will realize that certain modifications and variations will fall within the teachings of this invention, and that such variations and modifications are within their spirit and scope, as defined by the claims.