Pumps – Condition responsive control of pump drive motor – Responsive to pump or pump fluid temperature
Patent
1994-12-09
1996-06-18
Bertsch, Richard A.
Pumps
Condition responsive control of pump drive motor
Responsive to pump or pump fluid temperature
417292, 417310, 62126, 236 93R, F04B 4910
Patent
active
055271588
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to scroll-type machinery, and more particularly to scroll compressors having unique means for protecting the machine from overheating.
BACKGROUND AND SUMMARY OF THE INVENTION
A typical scroll machine has an orbiting scroll member having a spiral wrap on one face thereof, a non-orbiting scroll member having a spiral wrap on one face thereof with said wraps being entermeshed with one another, and means for causing said orbiting scroll member to orbit about an axis with respect to said non-orbiting scroll member, whereby said wraps will create pockets of progressively decreasing volume from a suction zone to a discharge zone.
It has been discovered that one of the unique features of scroll machines is that excessive high temperature discharge gas conditions (which result from the high pressure ratios caused by many different field-encountered problems) can be solved by providing means to cause a high-side to low-side leak during these conditions.
It is therefore one of the primary objects of the present invention to provide an improved mode of temperature protection which is extremely simple in construction, utilizing a simple temperature responsive valve, and which is easy to install and inspect, and which effectively provides the control desired. The valve of the present invention has been discovered to be particularly good at providing pressure relief and hence high temperature protection, particularly in motor-compressors where suction gas is used to cool the motor. This is because the valve will create a leak from the high side to the low side at discharge temperatures which are significantly higher than those for which the machine was designed. This leakage of discharge fluid which is directed towards the motor disposed in the lower portion of the shell which is on the suction side of the compressor essentially causes the machine to cease any significant pumping, and the resulting heat build-up of the motor components and lack of flow of relatively cool suction gas will cause the standard motor protector to trip and shut the machine down. The present invention therefore provides protection from excessive discharge temperatures which could result from (a) loss of working fluid charge, or (b) a blocked condenser fan in a refrigeration system, or (c) a low pressure condition or a blocked suction condition or (d) an excess discharge pressure condition for any reason whatever. All of these desirable conditions will cause a scroll machine to function at a pressure ratio much greater than that which is designed into the machine in terms of its predetermined fixed volume ratio, and this will in turn cause excessive discharge temperatures.
These and other objects and advantages will become more apparent when viewed in light of the accompanying drawings and following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partial vertical sectional view through line 1--1 of FIG. 2 of a scroll machine embodying the principles of the present invention;
FIG. 2 is a top plan view partially in cross section of the scroll machine shown in FIG. 1;
FIG. 3 is a partial vertical sectional view through the scroll machine along line 3--3 of FIG. 2;
FIG. 4 is a partial vertical sectional view through the scroll machine in the direction of arrow 4 in FIG. 2;
FIG. 5 is an enlarged vertical section view of a second embodiment of the present invention showing the thermally responsive valve in its open state;
FIG. 6 is a top plan view of the embodiment of FIG. 5;
FIG. 7 is an enlarged vertical sectional view of a third embodiment of the present invention; and
FIG. 8 is a top plan view of the embodiment of FIG. 7.
FIG. 9 is an enlarged vertical sectional view of a thermally responsive valve forming a part of the invention and shown in its normally closed state.
FIG. 10 is a fragmentary view similar to that of FIG. 9 showing a possible modification of the apparatus of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
While the present invention is suitable for
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Caillat Jean-Luc
Kulkarni Sunil S.
Ramsey Jeffery D.
Bertsch Richard A.
Copeland Corporation
Thai Xuan M.
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