|Publication number||USRE40399 E1|
|Application number||US 10/387,037|
|Publication date||24 Jun 2008|
|Filing date||12 Mar 2003|
|Priority date||19 Mar 1999|
|Also published as||US6210120|
|Publication number||10387037, 387037, US RE40399 E1, US RE40399E1, US-E1-RE40399, USRE40399 E1, USRE40399E1|
|Inventors||Jason J. Hugenroth, Thomas R. Barito|
|Original Assignee||Scroll Technologies|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (5), Referenced by (2), Classifications (12), Legal Events (4)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This invention relates to a scroll compressor with a vent to protect a refrigerant system during a low charge situation.
Compressors are utilized to compress a refrigerant in a air conditioning, refrigeration or heat pump systems, in a refrigerant cycle, the refrigerant leaving the compressor typically passes to a condenser, and from the condenser to an expansion device. From the expansion device the refrigerant is passed to a evaporator, and then to the compressor. During this cycle through the system, a working fluid is cooled, as known.
At times, a refrigerant system may lose charge, or refrigerant mass, such as by leakage. When this happens, the liquid which typically passes through the expansion device could be a gas. When gas approaches the expansion device, the flow may be choked at the expansion device. This could result in significant reduction in the mass flow rate through the system.
The reduction of refrigerant flow causes the compressor to draw the suction side pressure to abnormally low levels. Abnormally low suction pressure levels can cause the compressor to see undesirably high pressure ratios. The combined effect of the high pressure ratios and the low mass flow rate will cause the compressor to run at abnormally high temperatures, which could damage the compressor.
Motors in the compressor are typically provided with a protection device which will shut the compressor motor down in the event of an unusually high temperature. However, by the time the motor senses this unusually high temperature through low charge as described above, damage could already have occurred in the compressor.
One type of compressor is a Scroll compressor. Scroll compressors are becoming widely utilized in refrigerant compression applications. A scroll compressor consists of a first scroll member having a base and a generally spiral wrap extending from the base. This first scroll member has its wrap interfitting with the wrap of the second scroll member to define compression chambers. The first scroll member is driven to orbit relative to the second scroll member, and entrapped fluid in the chambers is compressed to compress an entrapped fluid.
In the disclosed embodiment of this invention, a compressor is provided with a vent that passes a heated entrapped fluid from a compression chamber to the suction chamber in the event of conditions which evidence a low charge. The compressor is of the hermetically sealed type wherein the suction fluid is passed over the motor to cool the motor. The motor is exposed to the entrapped fluid. The hot entrapped fluid will not cool the motor, but instead heats the motor. This will trip the protection device for the motor, and allow the motor to stop the system, until the low charge situation can be corrected.
In disclosed embodiments of this invention, the vents are incorporated into a Scroll compressor. The vents are preferably placed in the base of the non-driven scroll member. In one embodiment, the vent includes a valve housing at the tap to the compression chamber, and having a valve for selectively closing the tap. The valve is normally spring-biased to a position at which flow is allowed to pass from the compression chamber to the suction chamber. Thus, the valve tends to allow the entrapped fluid to enter the suction chamber, and contact the motor.
The valve is exposed to the entrapped fluid on a side of the valve opposite to the spring bias. The spring bias side of the valve is exposed to suction pressure. In the low charge situation described above, the pressure differential between the suction pressure and pressure at the entrapped fluid is relatively small. This relatively small difference in pressure is not enough to overcome the force of the spring. Thus, the spring will bias the valve to the open position and the heated fluid is allowed to pass from the compression chamber to the suction chamber.
On the other hand, during normal operation, the pressure at the entrapped fluid is significantly higher than the pressure in the suction chamber. Thus, the fluid in the compression chamber is able to overcome the spring force and move the valve to a closed position.
In a second embodiment, a magnetic force holds the valve at its open position allowing flow from the compression chamber to the suction chamber. If compressor operation is proper, and there is a significant pressure differential between suction and the compression chamber, the valve is driven away from its open position by the pressure in the compression chamber and moves to the closed position.
In another embodiment, the spring-biased embodiment is provided with a bi-metal disc which snaps between two positions due to the temperature. If the compressor is included in a heat pump, there are times when the pressure change between suction and the compression chamber might be relatively small. In particular, when the compressor is in a heat pump mode with a low ambient temperature, the suction pressure may become very low, as described above. This could occur at temperatures on the order of −20° F. In these situations it would not be desirable for the motor to stop.
The compressor running in the heat pump situation described above remains relatively cool. The bi-metal disc has a non-heated position which holds the valve at its closed position whenever a very low temperature is experienced. Thus, during the heat pump operation described above the bi-metal disc holds the valve closed, and there is no venting. On the other hand, at almost all normal operating temperatures, the bi-metal disc will not prevent the valve from moving. Thus, during the loss of charge situation described above, the compressor quickly heats. The bi-metal disc will be at its normal position allowing valve movement. The spring force then causes the valve to move to its open position. In this way, the bi-metal disc allows the system to be incorporated into a compressor utilized in a heat pump.
In a further embodiment, a spool valve is provided with a closure valve. The spool valve sees suction pressure on one side and the entrapped pressure on another side. A spring tends to bias the closure valve to an open position allowing the entrapped pressure to move into the suction chamber. Discharge pressure is also provided at one small surface on the valve. If the pressure differential between suction and the compression chamber become small, the spring opens the closure valve, and allows flow from the compression chamber, and further from the discharge chamber into the suction chamber.
In further embodiments, the valve moves to open a tap between discharge and suction when the pressure difference between suction and the compression chamber is small. Again, a small pressure difference between suction and intermediate is indicative of loss of charge. Thus, the heated gas from the discharge chamber is communicated into the suction chamber, which in turn contacts the motor.
With regard to any of the above embodiments, a heated entrapped gas is passed into a chamber which communicates with the motor. This heats the motor, causing the motor's heat protection circuit to trip and stop motor operation.
While the disclosed embodiments all show the vent in the base of the orbiting scroll, it should be understood that the vent could be located in other locations within the compressor housing. As examples, the vent could be located within the orbiting scroll, or the crank case. Further the vent could be located in a location other than the base of the scroll members.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.
A refrigerant system 15 is schematically illustrated in
As described above, in a loss of charge situation, the liquid which typically leaves the condenser C could still be gaseous. The gas creates a choked flow condition at the expansion device EX, thus limiting mass flow. This could then lead to a problem at the compressor.
As mentioned above, if a low charge situation occurs, there could be undesirably high pressure ratios and undesirable heat encountered in the compression chambers, such as chamber 26. A vent 36 is provided to vent the heated fluid from the chamber 26 into the suction chambers 28, 32. The heated fluid communicates with the motor 30, and the protection device 34 will stop motor operation. This allows the system to be shut down in a low charge situation without damage to the compressor.
A stop surface 50 provides a valve seat 51. A spring 52 biases a valve 54 downwardly toward end wall 43. In the position illustrated in
However, if the pressure in the chamber 26 becomes low, spring 96 moves the closure piston 94 to the left from the illustrated position. Pressure in the entrapped chamber 26 communicates through passage 92 to chamber 90. The fluid can then pass into the suction chamber 28. Also, the pressure from tap 98, combined with the force from the chamber 90, causes the spool valve 88 to move to the left from the illustrated position. Gas from the discharge chamber may then pass through port 98, into port 82, and to the suction chamber 28. Again, this heated gas communicates with the motor, and causes the motor protection device to shut down.
In addition, the
Alternately, when there is a proper charge, the pressure at tap 116 is sufficiently greater than the pressure at tap 122 to cause the piston 120 to move upwardly and close any communication between the tap 114 and the tap 122.
The embodiment shown in
In general, specific embodiments have been illustrated for allowing a venting of an entrapped gas to the suction chamber in the event that conditions indicate the compressor may be running at a low charge condition. While the embodiments all show the venting device in the non-orbiting scroll, it is possible the vent could be positioned elsewhere. The vent could be in the orbiting scroll, the crankcase, or other locations. Further, it may be valuable to include such a vent in a compressor type other than a scroll compressor. Again, this invention extends beyond the specific embodiments.
In addition, although in the preferred embodiment the heated gas from the compression chamber does shut down the motor, the venting itself will also serve to relieve detrimental affects of the low charge situation. Thus, in some applications, the venting could be utilized without exposing the motor to the heated gas from the compression chamber, or without the motor protection feature.
A worker of ordinary skill in this art would recognize that many modifications come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.
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|US5169294||6 Dec 1991||8 Dec 1992||Carrier Corporation||Pressure ratio responsive unloader|
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|US5707210||13 Oct 1995||13 Jan 1998||Copeland Corporation||Scroll machine with overheating protection|
|US6132179 *||27 Aug 1998||17 Oct 2000||Sanden Corporation||Scroll type compressor enabling a soft start with a simple structure|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US7559750 *||14 Jul 2009||Lg Electronics Inc.||Overheating protection apparatus of scroll compressor|
|US20050135940 *||17 Dec 2004||23 Jun 2005||Lg Electronics Inc.||Overheating protection apparatus of scroll compressor|
|U.S. Classification||417/32, 417/26, 417/310|
|International Classification||F04C28/28, F04B49/10, F04C28/06, F04C18/02|
|Cooperative Classification||F04C18/0215, F04C28/28, F04C28/06|
|European Classification||F04C28/06, F04C28/28|
|30 Sep 2008||FPAY||Fee payment|
Year of fee payment: 8
|11 Nov 2008||CC||Certificate of correction|
|12 Nov 2012||REMI||Maintenance fee reminder mailed|
|3 Apr 2013||LAPS||Lapse for failure to pay maintenance fees|