CA1087412A - High side pressure limiting thermostatic expansion valve - Google Patents
High side pressure limiting thermostatic expansion valveInfo
- Publication number
- CA1087412A CA1087412A CA270,000A CA270000A CA1087412A CA 1087412 A CA1087412 A CA 1087412A CA 270000 A CA270000 A CA 270000A CA 1087412 A CA1087412 A CA 1087412A
- Authority
- CA
- Canada
- Prior art keywords
- pressure
- valve
- expansion valve
- thermostatic expansion
- throttling valve
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60H—ARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES
- B60H1/00—Heating, cooling or ventilating [HVAC] devices
- B60H1/00485—Valves for air-conditioning devices, e.g. thermostatic valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B41/00—Fluid-circulation arrangements
- F25B41/30—Expansion means; Dispositions thereof
- F25B41/31—Expansion valves
- F25B41/325—Expansion valves having two or more valve members
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B41/00—Fluid-circulation arrangements
- F25B41/30—Expansion means; Dispositions thereof
- F25B41/31—Expansion valves
- F25B41/33—Expansion valves with the valve member being actuated by the fluid pressure, e.g. by the pressure of the refrigerant
- F25B41/335—Expansion valves with the valve member being actuated by the fluid pressure, e.g. by the pressure of the refrigerant via diaphragms
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2341/00—Details of ejectors not being used as compression device; Details of flow restrictors or expansion valves
- F25B2341/06—Details of flow restrictors or expansion valves
- F25B2341/068—Expansion valves combined with a sensor
- F25B2341/0683—Expansion valves combined with a sensor the sensor is disposed in the suction line and influenced by the temperature or the pressure of the suction gas
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Fluid Mechanics (AREA)
- Temperature-Responsive Valves (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
In all forms the expansion valve regulates the flow in accordance with the pressure in the diaphragm head chamber as affected by the sensed temperature. To prevent excessive inlet pressure a plug valve operated by a piston modulates the flow which reduces the flow through the system and thus reduces the output of the compressor causing the high side pressure to drop. The piston is exposed to the inlet (high side) pressure and to the outlet (evaporator) pressure (which remains relatively constant) or to a substantially fixed pressure.
In all forms the expansion valve regulates the flow in accordance with the pressure in the diaphragm head chamber as affected by the sensed temperature. To prevent excessive inlet pressure a plug valve operated by a piston modulates the flow which reduces the flow through the system and thus reduces the output of the compressor causing the high side pressure to drop. The piston is exposed to the inlet (high side) pressure and to the outlet (evaporator) pressure (which remains relatively constant) or to a substantially fixed pressure.
Description
BACKGROUND OF T~ INVENTION
In au~omotive air conditioning sys~ems conditions may arise causlng the "low side" (compressor intake) pressure to rise to excessive levels which can damage the compressor.
To guard against this condition thermostatic expansion valves have been provided with a low side pressure limit feature.
Excessive "high side" (compressor output) pressure can also cause compressor damage. Normally the high side and low side pressures tend to rise together and the low side pressure limit will protect the compressor from overload. There are some conditions, however, when the high side pressure is excessive while the low side pressure is normal. To protect against compressor overload in such cases the system is usually provided with a pressure switch responding to exces-sive high side pressure to disconnect the compressor clutch.
This stops all cooling, causes compressor belt wear, requires additional wiring and conduit connections, and causes a momentary drag on engine performance which can be felt in small engine cars when the clutch re-engages.
SU~D~ARY OF THE IN~E~TION
:
The object of this invention is to protect against excessive high side pressure in an automotive air condition-ing system by modulating or throttling the flow to the thermostatic expansion valve when the pressure rises to excessive levels. When the flow to the thermostatic expan sion valve is reduced, flow to and from the compressor is reduced causing the high side pressure to fall.
In au~omotive air conditioning sys~ems conditions may arise causlng the "low side" (compressor intake) pressure to rise to excessive levels which can damage the compressor.
To guard against this condition thermostatic expansion valves have been provided with a low side pressure limit feature.
Excessive "high side" (compressor output) pressure can also cause compressor damage. Normally the high side and low side pressures tend to rise together and the low side pressure limit will protect the compressor from overload. There are some conditions, however, when the high side pressure is excessive while the low side pressure is normal. To protect against compressor overload in such cases the system is usually provided with a pressure switch responding to exces-sive high side pressure to disconnect the compressor clutch.
This stops all cooling, causes compressor belt wear, requires additional wiring and conduit connections, and causes a momentary drag on engine performance which can be felt in small engine cars when the clutch re-engages.
SU~D~ARY OF THE IN~E~TION
:
The object of this invention is to protect against excessive high side pressure in an automotive air condition-ing system by modulating or throttling the flow to the thermostatic expansion valve when the pressure rises to excessive levels. When the flow to the thermostatic expan sion valve is reduced, flow to and from the compressor is reduced causing the high side pressure to fall.
2.
74~:
The evaporator pressure (thermostatic expansion valve outlet pressure~ is relatively uniform within 207 kPa in an automotive air conditioning system (during operation) and the high side pressure is subject to much greater variation. ~n a comparative basis the evaporator pressure ma~ be considered uniform. With this in mind I provide a -throttling valve responsive to the difference between high side pressure and evaporator pressure to throttle flow to the thermostatic expansion valve and the system~ If desire~, the throttling valve can be made responsive to the difference between high side pressure and either atmospheric pressure or a fixed pressure. In all cases the throttling action starves the system and causes reduction in compressor outpu~
which causes the high side pressure to fall back to the desired range. By incorporating this valve in the thermo- -static expansion valve no additional system connections are - ~ required. Since the compressor continues to operate, cooling continues and engine performance is unaffected. In the illustrated embodiments the throttling is upstream o~ the thermostatic expansion valve but it could be downstream. And the throttling valve could be separate from the thermostatic -expansion valve but this would be more costly to build and install. The concept is shown in connection with two types `
of thermostatic expansion valves and from this it should be clear that the invention is not limited to a particular type of thermostatic expansion valve.
Broadly speaking, the present invention provides, in an automotive air conditioning system having a compressor ~;~
delivering refrigerant to a thermostatic expansion valve -~
which regulates flow to an evaporator in accordance with the ~;
control temperature, the refrigerant flowing back to the compressor from the evaporator, the improvement comprising, a throttling valve mounted in the thermostatic expan~ion ~ 3 ~
. ., .,, . . . . .. ... . . . . .. ... ~ . ............... . . . .. . . . .
.
411 ~
valve body in series with the thermostatic expansion valve, piston means connected to the throttling valve with one side exposed to pressure upstream of both valves and its other side exposed to pressure downstream of both valves to actuate the throttling valve to reauce or interrupt refrigerant flow and thereby reduce pressure upstream of both valves when the pressure upstream of both valves is abnormally high.
DESCRIPTION OF THE DRAWINGS
... . . . .. . .. ... ..
].0 Fig, 1 is a vertical section through a thermostatic expansion valve in a schematic air conditioning system.
Fig. 2 is another modification.
3a ~
.;.. ~ ,., :
Fig. 3 is a section on line 3--3 in Fig. 1.
Fig. 4 is similar to Fig. 3 but shows an arrangement in which the throttling valve is actuated in response to high side pressure.
Fig. 5 shows another variant in which changes in atmospheric pressure have no effect.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The lower portion of vaLve body 10 is provided with inlet 12 and outlet 14 separated by a partition through which port 16 is provided to supply refrigerant to the space below the partition. Ball-type valve 18 cooperates with seat 20 to control flow from the inlet to the outlet. The ball is centered on cage 22 which is urged in the valve closing direc-tion by spring 24 compressed between the cage and carrier 26 threaded into the end of the valve body and adjustable to change the spring force. The end of the valve body i~ sealed by cap nut 28 and an O-ring.
Va~ve 18 is actuated by push pin 30 which, in turn, is actuated by diaphragm rider pin 32 fixed to diaphragm pad 34 and having an end proiection projecting through the pad and diaphragm 36 ~o communicate with head chamber 38. Pin 30 has a close sliding fit in bore 40 to minimize leakage along this portion since any such leakage would constitute a bypass.
In the upper portion of the valve body there is a return conduit including inlet 42 connected to the outlet of the evaporator E while outlet 44 is connected to the inlet of compressor C. It will be appreciated that, as usual, the out-put of the compressor is fed into condenser K and thence to receiver R which is conducted to the inlet 12 of the valve body 10. Pressure within the return conduit can communicate 4.
~ ~ ~7 ~
with chamber 46 below the diaphragm through por~ 48 in ~he upper wall of the valve body. From this it will be clear that the tolerance between diaphragm rider pin 32 and the upper wall is not of great concern since a little leakage here wilL hurt nothing. Diaphragm 36 is mounted between domed head 54 and support cup 50 threaded in~o the upper end of the valve body and sealed with respect thereto by means of O-ring 52. Head chamber 38 is charged with a temperature responsive charge through capillary tube 56 which is then seaLed off.
It will be noted that rider pin 32 is provided with a blind hole 58 which terminates approximately at the mid-point of the ret~rn flow path through the upper portion of the val~e body. The blind hole, in effect, provides a small temperature sensing chamber 60 inside the rider pin and located in the system return path. Pin chamber 60 will always be col.der than head ch~mber 38 and, therefore, the refrigerant charge will tend to condense in chamber 60 and the control poin~ will be at ~his point which is ideally ~it-uated. Since there is not much mass involved in the riderpin the response of the valve as thus far described would be quite rapid and subject to fluctuation on any transient tem-perature changes. This, of course, would result in hunting.
To damp out the hunting effect low conductivity sleeve 62 is mounted over the rider pin where the pin passes through the return flow path. This sleeve can wel~ be Delrin which, in " \ ~ addition to low thermal conductivity, provides a self-lubricating factor to insure free mo~ement of the rider 32.
The thickness determines the degree of damping.
In order to make the valve mountable in all positions capil1ary restrictor 64 is fitted in the upper end 5.
~ ~7 ~ 2 of the rider pin. This, then, provides a very small capillary hole connecting rider pin chamber 60 to head cham-ber 38. This is adequate for transfer of pressure changes but wilL minimize migration of any condensed rerigerant charge in chamber 60 to the head chamber should the valve be mounted upside down. Without this restrictor there could be such migration wi~h the result tha~ the liquid refrigerant migrating to the head chamber (which is warmer) would flash to a gas ,~increasing the presswre) and ~hen promp~ly be recondensed in chamber 60. This, of course, would induc~
hunting in the system. With the restrictor the hunting is minimized.
As described to this point the thermostatic expansion va~ve is the same as in U.S. Patent 3,537,645. The present arrangement differs in provision of throttling valve 66 in cross bore 68 and carried by piston 70 in bore 72. The end of bore 72 is cLosed by co~er 74 secured to body 10 by screws 76 and sealed by 0-ring 78. The cover 74 provides a seat for compressed spring 80 which urges the piston towards the inLet with the maximum travel determined by plug valve 66 engaging the end of the bore 68. Conduit 82 leads from bore 72 to outlet 14 so the "back" of piston 70 is exposed to the outlet (evaporator) pressure while the face of the piston senses inlet ~high side~ pressure. When the pressure differ-ential can overcome the spring load, the piston will move to move the plug valYe across the inlet. This throttles flow to the thermostatic expansion valve and the system causing reduced fLow to and from the compressor which causes the high side pressure to drop.
In the second modification (Fig. 2) the thermostatic expansion valve configuration is more of the 6.
"normaL" type and the throttling valve is coaxial with theexpansion valve. Thus the thermos~atic expansion valve body 84 has an inLe~ 86 (provided with strainer 88) leading to central partition 90. The valve body is provided with bore 92 intersecting the inlet and communicating wi~h the outlet 94. Valve 96 normally con~rols flow -Erom the inlet to the outlet since the central aperture 98 is normally closed by piston 100 biased upwardly by spring 102 carried in cup 104 Eixed on the valve support 106. Adjustable seat 108 threaded in outlet 94 determines the load applied to spring 110 urging the val~e 96 to its seat. Valve 96 is actuated by diaphragm 112 through push pin(s) 114. The diaphragm is fixed between upper and lower head stampings 116~118 which are welded together. Outlet pressure acts on the underside of the dia-phragm through the clearance around the push pins. The space above the diaphragm is connected to ~he conventional feeler bulb 120 by capillary tube 122 and this closed system is charged with a temperature responsive charge. Operation of the thermostatic expansion valve is con~entional.
Piston 1~0 is provided with a stem projec~ing through bore 98 with a plug valve 124 threaded on its upper end and normally not restricting fLow. Inlet ~high side) pressure acts on the top of the plug/stem. Outlet pressure (evaporator pressure) acts on the bottom of the piston 100.
When the pressure differential exceeds the force of spring lQ2, the piston moves down relative to the expansion valve 96 (which will be open) and the chamfered lower end oE plug 124 will cooperate with the seat to throttle flow and reduce the high side pressure as in the first embodiment.
In Fig. 4 the throttling valve 166 is moun~ed in -~ cross bore L68 and carried by piston 170 in bore 172 in a . .. , .. . . ., " . . . - --. ~, . , ~ . - , . - ... . ~
~ ~ ~ 7 ~ ~
ma~ner similar ~o the first embodiment. In this case, however, the valve is to respond to the difference between high side pressure and atmospheric pressure. Therefore, piston 170 is carried by bellows 174 which is sealed to shoulder 176 in cylinder 178 threaded into the valve body 10.
The end of the cylinder 178 is closed by disc 180. The disc is ported a~ 182 to expose the interior of the bellows to atmospheric pressure. Compressed spring 184 seats on the disc and the piston 170 to establish the desired pre-load.
With this arrangement the high side pressure is opposed by the spring force and atmospheric pressure. The total oppos-ing force is generally considered as referenced from atmospheric pressure which is more constant than evaporator pressure~ Therefore, the pressure at which the valve starts to throttle is more definite.
Fig. 5 shows the manner in which the high side pressure alone determines ~he response pressure . . . . i.e.
the effect of atmospheric variation is e~iminated. This is done by changing the end disc in cylinder 178 to a non-vented disc 186 having a eapillary tube 188 which is used to evacu-ate the interior of the bellows 174 and is then sealed.
Thereore, the high side pressure is opposed only by the fixed force (pressure) of the spring 184 and the response pressure is fixed.
As mentioned above, the throttling valve can, if d~sired, be located downstream of the thermostatic expansion valve by suitable porting inside the valve body. In some cases this can be advantageous in that the throttling valve is then controlling a 2-phase (liquid and vapor) refrigerant and it is easier to close off flow. Where inadequa~e closure : ., . - . ~.......... . . . - . . .-. . .. . . . . . - . . .
~ 2 is obtained upstream, the extra cost (by reason of porting and seals) of locating the valve downstream can be justified.
8`~
74~:
The evaporator pressure (thermostatic expansion valve outlet pressure~ is relatively uniform within 207 kPa in an automotive air conditioning system (during operation) and the high side pressure is subject to much greater variation. ~n a comparative basis the evaporator pressure ma~ be considered uniform. With this in mind I provide a -throttling valve responsive to the difference between high side pressure and evaporator pressure to throttle flow to the thermostatic expansion valve and the system~ If desire~, the throttling valve can be made responsive to the difference between high side pressure and either atmospheric pressure or a fixed pressure. In all cases the throttling action starves the system and causes reduction in compressor outpu~
which causes the high side pressure to fall back to the desired range. By incorporating this valve in the thermo- -static expansion valve no additional system connections are - ~ required. Since the compressor continues to operate, cooling continues and engine performance is unaffected. In the illustrated embodiments the throttling is upstream o~ the thermostatic expansion valve but it could be downstream. And the throttling valve could be separate from the thermostatic -expansion valve but this would be more costly to build and install. The concept is shown in connection with two types `
of thermostatic expansion valves and from this it should be clear that the invention is not limited to a particular type of thermostatic expansion valve.
Broadly speaking, the present invention provides, in an automotive air conditioning system having a compressor ~;~
delivering refrigerant to a thermostatic expansion valve -~
which regulates flow to an evaporator in accordance with the ~;
control temperature, the refrigerant flowing back to the compressor from the evaporator, the improvement comprising, a throttling valve mounted in the thermostatic expan~ion ~ 3 ~
. ., .,, . . . . .. ... . . . . .. ... ~ . ............... . . . .. . . . .
.
411 ~
valve body in series with the thermostatic expansion valve, piston means connected to the throttling valve with one side exposed to pressure upstream of both valves and its other side exposed to pressure downstream of both valves to actuate the throttling valve to reauce or interrupt refrigerant flow and thereby reduce pressure upstream of both valves when the pressure upstream of both valves is abnormally high.
DESCRIPTION OF THE DRAWINGS
... . . . .. . .. ... ..
].0 Fig, 1 is a vertical section through a thermostatic expansion valve in a schematic air conditioning system.
Fig. 2 is another modification.
3a ~
.;.. ~ ,., :
Fig. 3 is a section on line 3--3 in Fig. 1.
Fig. 4 is similar to Fig. 3 but shows an arrangement in which the throttling valve is actuated in response to high side pressure.
Fig. 5 shows another variant in which changes in atmospheric pressure have no effect.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The lower portion of vaLve body 10 is provided with inlet 12 and outlet 14 separated by a partition through which port 16 is provided to supply refrigerant to the space below the partition. Ball-type valve 18 cooperates with seat 20 to control flow from the inlet to the outlet. The ball is centered on cage 22 which is urged in the valve closing direc-tion by spring 24 compressed between the cage and carrier 26 threaded into the end of the valve body and adjustable to change the spring force. The end of the valve body i~ sealed by cap nut 28 and an O-ring.
Va~ve 18 is actuated by push pin 30 which, in turn, is actuated by diaphragm rider pin 32 fixed to diaphragm pad 34 and having an end proiection projecting through the pad and diaphragm 36 ~o communicate with head chamber 38. Pin 30 has a close sliding fit in bore 40 to minimize leakage along this portion since any such leakage would constitute a bypass.
In the upper portion of the valve body there is a return conduit including inlet 42 connected to the outlet of the evaporator E while outlet 44 is connected to the inlet of compressor C. It will be appreciated that, as usual, the out-put of the compressor is fed into condenser K and thence to receiver R which is conducted to the inlet 12 of the valve body 10. Pressure within the return conduit can communicate 4.
~ ~ ~7 ~
with chamber 46 below the diaphragm through por~ 48 in ~he upper wall of the valve body. From this it will be clear that the tolerance between diaphragm rider pin 32 and the upper wall is not of great concern since a little leakage here wilL hurt nothing. Diaphragm 36 is mounted between domed head 54 and support cup 50 threaded in~o the upper end of the valve body and sealed with respect thereto by means of O-ring 52. Head chamber 38 is charged with a temperature responsive charge through capillary tube 56 which is then seaLed off.
It will be noted that rider pin 32 is provided with a blind hole 58 which terminates approximately at the mid-point of the ret~rn flow path through the upper portion of the val~e body. The blind hole, in effect, provides a small temperature sensing chamber 60 inside the rider pin and located in the system return path. Pin chamber 60 will always be col.der than head ch~mber 38 and, therefore, the refrigerant charge will tend to condense in chamber 60 and the control poin~ will be at ~his point which is ideally ~it-uated. Since there is not much mass involved in the riderpin the response of the valve as thus far described would be quite rapid and subject to fluctuation on any transient tem-perature changes. This, of course, would result in hunting.
To damp out the hunting effect low conductivity sleeve 62 is mounted over the rider pin where the pin passes through the return flow path. This sleeve can wel~ be Delrin which, in " \ ~ addition to low thermal conductivity, provides a self-lubricating factor to insure free mo~ement of the rider 32.
The thickness determines the degree of damping.
In order to make the valve mountable in all positions capil1ary restrictor 64 is fitted in the upper end 5.
~ ~7 ~ 2 of the rider pin. This, then, provides a very small capillary hole connecting rider pin chamber 60 to head cham-ber 38. This is adequate for transfer of pressure changes but wilL minimize migration of any condensed rerigerant charge in chamber 60 to the head chamber should the valve be mounted upside down. Without this restrictor there could be such migration wi~h the result tha~ the liquid refrigerant migrating to the head chamber (which is warmer) would flash to a gas ,~increasing the presswre) and ~hen promp~ly be recondensed in chamber 60. This, of course, would induc~
hunting in the system. With the restrictor the hunting is minimized.
As described to this point the thermostatic expansion va~ve is the same as in U.S. Patent 3,537,645. The present arrangement differs in provision of throttling valve 66 in cross bore 68 and carried by piston 70 in bore 72. The end of bore 72 is cLosed by co~er 74 secured to body 10 by screws 76 and sealed by 0-ring 78. The cover 74 provides a seat for compressed spring 80 which urges the piston towards the inLet with the maximum travel determined by plug valve 66 engaging the end of the bore 68. Conduit 82 leads from bore 72 to outlet 14 so the "back" of piston 70 is exposed to the outlet (evaporator) pressure while the face of the piston senses inlet ~high side~ pressure. When the pressure differ-ential can overcome the spring load, the piston will move to move the plug valYe across the inlet. This throttles flow to the thermostatic expansion valve and the system causing reduced fLow to and from the compressor which causes the high side pressure to drop.
In the second modification (Fig. 2) the thermostatic expansion valve configuration is more of the 6.
"normaL" type and the throttling valve is coaxial with theexpansion valve. Thus the thermos~atic expansion valve body 84 has an inLe~ 86 (provided with strainer 88) leading to central partition 90. The valve body is provided with bore 92 intersecting the inlet and communicating wi~h the outlet 94. Valve 96 normally con~rols flow -Erom the inlet to the outlet since the central aperture 98 is normally closed by piston 100 biased upwardly by spring 102 carried in cup 104 Eixed on the valve support 106. Adjustable seat 108 threaded in outlet 94 determines the load applied to spring 110 urging the val~e 96 to its seat. Valve 96 is actuated by diaphragm 112 through push pin(s) 114. The diaphragm is fixed between upper and lower head stampings 116~118 which are welded together. Outlet pressure acts on the underside of the dia-phragm through the clearance around the push pins. The space above the diaphragm is connected to ~he conventional feeler bulb 120 by capillary tube 122 and this closed system is charged with a temperature responsive charge. Operation of the thermostatic expansion valve is con~entional.
Piston 1~0 is provided with a stem projec~ing through bore 98 with a plug valve 124 threaded on its upper end and normally not restricting fLow. Inlet ~high side) pressure acts on the top of the plug/stem. Outlet pressure (evaporator pressure) acts on the bottom of the piston 100.
When the pressure differential exceeds the force of spring lQ2, the piston moves down relative to the expansion valve 96 (which will be open) and the chamfered lower end oE plug 124 will cooperate with the seat to throttle flow and reduce the high side pressure as in the first embodiment.
In Fig. 4 the throttling valve 166 is moun~ed in -~ cross bore L68 and carried by piston 170 in bore 172 in a . .. , .. . . ., " . . . - --. ~, . , ~ . - , . - ... . ~
~ ~ ~ 7 ~ ~
ma~ner similar ~o the first embodiment. In this case, however, the valve is to respond to the difference between high side pressure and atmospheric pressure. Therefore, piston 170 is carried by bellows 174 which is sealed to shoulder 176 in cylinder 178 threaded into the valve body 10.
The end of the cylinder 178 is closed by disc 180. The disc is ported a~ 182 to expose the interior of the bellows to atmospheric pressure. Compressed spring 184 seats on the disc and the piston 170 to establish the desired pre-load.
With this arrangement the high side pressure is opposed by the spring force and atmospheric pressure. The total oppos-ing force is generally considered as referenced from atmospheric pressure which is more constant than evaporator pressure~ Therefore, the pressure at which the valve starts to throttle is more definite.
Fig. 5 shows the manner in which the high side pressure alone determines ~he response pressure . . . . i.e.
the effect of atmospheric variation is e~iminated. This is done by changing the end disc in cylinder 178 to a non-vented disc 186 having a eapillary tube 188 which is used to evacu-ate the interior of the bellows 174 and is then sealed.
Thereore, the high side pressure is opposed only by the fixed force (pressure) of the spring 184 and the response pressure is fixed.
As mentioned above, the throttling valve can, if d~sired, be located downstream of the thermostatic expansion valve by suitable porting inside the valve body. In some cases this can be advantageous in that the throttling valve is then controlling a 2-phase (liquid and vapor) refrigerant and it is easier to close off flow. Where inadequa~e closure : ., . - . ~.......... . . . - . . .-. . .. . . . . . - . . .
~ 2 is obtained upstream, the extra cost (by reason of porting and seals) of locating the valve downstream can be justified.
8`~
Claims (3)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In an automotive air conditioning system having a compressor delivering refrigerant to a thermostatic expansion valve which regulates flow to an evaporator in accordance with the control temperature, the refrigerant flowing back to the compressor from the evaporator, the improvement comprising, a throttling valve mounted in the thermostatic expansion valve body in series with the thermostatic expansion valve, piston means connected to the throttling valve with one side exposed to pressure upstream of both valves and its other side exposed to pressure down-stream of both valves to actuate the throttling valve to reduce or interrupt refrigerant flow and thereby reduce pressure upstream of both valves when the pressure upstream of both valves is abnormally high.
2. The construction according to Claim 1 in which the throttling valve is mounted in and regulates flow through the thermostatic expansion valve inlet and one side of the piston means is exposed to the pressure in said inlet and said other side of the piston means is ported to the thermostatic expansion valve outlet, and including a spring biasing the throttling valve to its open position to establish the pressure at which the throttling valve will begin to throttle.
3. The construction according to Claim 1 in which the throttling valve is coaxial with and upstream of the thermostatic expansion valve, said piston means including a stem means guided in the body and in the thermostatic expansion valve, and a spring biasing the throttling valve to its open position to establish the pressure at which the throttling valve will begin to throttle.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US66377476A | 1976-03-04 | 1976-03-04 | |
| US663,774 | 1976-03-04 | ||
| US69612176A | 1976-06-14 | 1976-06-14 | |
| US696,121 | 1976-06-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1087412A true CA1087412A (en) | 1980-10-14 |
Family
ID=27098816
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA270,000A Expired CA1087412A (en) | 1976-03-04 | 1977-01-19 | High side pressure limiting thermostatic expansion valve |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS52118651A (en) |
| CA (1) | CA1087412A (en) |
| DE (1) | DE2709534A1 (en) |
| IT (1) | IT1085516B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5924299A (en) * | 1996-11-12 | 1999-07-20 | Valeo Climatisation | Monobloc component for a refrigerant fluid circuit, in particular for air conditioning the cabin of a motor vehicle |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3743285A1 (en) * | 1987-12-19 | 1989-06-29 | Sueddeutsche Kuehler Behr | DEVICE FOR CONTROLLING THE EXPANSION VALVE OF THE REFRIGERATION DEVICE IN A MOTOR VEHICLE AIR CONDITIONING |
| DE3829101A1 (en) * | 1988-08-27 | 1990-03-01 | Sueddeutsche Kuehler Behr | THERMOSTATIC EXPANSION VALVE |
| JP3372439B2 (en) * | 1996-10-11 | 2003-02-04 | 株式会社不二工機 | Expansion valve |
| JP2007139209A (en) * | 2005-11-14 | 2007-06-07 | Denso Corp | Pressure control valve for refrigerating cycle |
| JP6149237B2 (en) | 2013-04-24 | 2017-06-21 | 株式会社テージーケー | Vehicle air conditioner and expansion valve |
-
1977
- 1977-01-19 CA CA270,000A patent/CA1087412A/en not_active Expired
- 1977-02-26 JP JP2078877A patent/JPS52118651A/en active Pending
- 1977-03-03 IT IT7720876A patent/IT1085516B/en active
- 1977-03-04 DE DE19772709534 patent/DE2709534A1/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5924299A (en) * | 1996-11-12 | 1999-07-20 | Valeo Climatisation | Monobloc component for a refrigerant fluid circuit, in particular for air conditioning the cabin of a motor vehicle |
Also Published As
| Publication number | Publication date |
|---|---|
| DE2709534A1 (en) | 1977-09-08 |
| JPS52118651A (en) | 1977-10-05 |
| IT1085516B (en) | 1985-05-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |