US 3204389 A
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Description (OCR text may contain errors)
Sept. 7, 19 65 o. GRAHAM 3,204,389
LIQUID SEPARATOR Filed April 4, 1965 INVENTOR. $4227? 0, 57 4/ 147 United States Patent 3,204,389 LHQUID SEPARATOR Frank 0. Graham, Detroit, Mich, assignor to Temprite Products Corporation, Birmingham, Mich, a corporation of Michigan Filed Apr. 4, 196$,Ser. No. 270,608 4 Claims. (Cl. 55-219) The present invention relates generally to refrigeration systems and more particularly to the provision in such a system of a novel oil separator incorporating a unique float valve having dampening action.
As is well known, most refrigeration systems utilize a conventional piston-type compressor in which lubrication of the compressor parts is achieved through the use of oil normally supplied from the compressor crankcase or a suitable reservoir. In actual practice, a certain proportion of this oil eventually leaks past the piston and into the compression chamber of the compressor, whereupon it is atomized and becomes entrained in the gaseous refrigerant as it is compressed. This gradual but continuous loss of oil is extremely undesirable for a number of reasons. For example, the compressor will burn out if it loses too much oil; the expansion valve will become gummed up and not function properly; oil will get into the condenser and evaporator and cause a substantial decrease in the rate of heat transfer and hence efliciency while increasing power consumption; and the presence of oil in the refrigerant itself alters its true boiling and condensing points, thus further reducing refrigeration ef- To eliminate this problem an oil separator may be inserted in the refrigerant line between the compressor and the condenser. The oil thus separated from the refrigerant may then be filtered and forced back to the compressor crankcase by the high pressure of the refrigerant in the oil separator. The provision of an oil separator not only eliminates all the aforesaid problems but also serves to provide the compressor with a constant supply of clean oil, thus further increasing its life, and to muffle to some extent the sound of the system.
One type of oil separator which has been found to be ideally suited for this application is one which mechanically separates the oil from the compressed gaseous refrigerant by coalescing the entrained oil and allowing it to gravity flow or drip into a sump or reservoir in the separator. The flow of oil from the separator sump to the compressor may be controlled by a float valve which is responsive to the oil level in the sump to open the valve when the sump level reaches a predetermined height, whereupon the oil will be forced back to the compressor crankcase under the influence of the high pressure of the refrigerant in the separator.
It has been found, however, that in refrigeration systems which are subject to severe vibrations and sudden or abrupt physical movements, such as those encountered on trucks, buses, planes, trains, and other mobile equipment, the resultant sloshing of the oil in the separator sump causes the float valve therein to continually and needlessly pound against its seat. As a consequence, the valve does not operate effectively and both it and its seat wear out extremely fast, at which time the entire valve becomes totally ineffective.
It is therefore an object of the present invention to provide in combination with a refrigeration system an oil separator having a float valve therein provided with unique dampening means to prevent excessive wear of the valve components, as well as ineffective operation of the valve, when the system is subject to vibrations and abrupt physical movements, such as encountered on mobile equipment.
It is a further object of this invention to provide a novel 3,204,389 Patented Sept. 7, 1965 oil separator in which is provided a unique float valve having dampening means for preventing the injurious effects of vibrations and abrupt physical movements of the separator.
Another object resides in the provision of an extremely simple and inexpensive float control valve having novel dampening action. A related object resides in the provision of such a valve wherein dampening is achieved by a fluid dash pot utilizing the same fluid as is being controlled.
These and other objects of the present invention will become apparent from consideration of the specification, taken in connection with the accompanying drawings in which there is illustrated a single embodiment of the present invention, by way of example, and wherein:
FIGURE 1 is a diagrammatic view illustrating an entire refrigeration system having an oil separator, shown partly in section, incorporating the principles of the present invention; and
FIGURE 2 is an enlarged sectional view of the oil separator float valve.
Referring first to FIGURE 1, the refrigeration system is conventional and comprises a compressor 10 having inlet and outlet fluid lines 12 and 14 respectively, and a pulley or the like 16 adapted to be engaged by a suitable driving source to power the compressor. The gaseous refrigerant compressed by the compressor flows through fluid line 14 to an oil separator 18 comprising cylindrical side walls 20, a bottom wall 22, an upper mounting flange 24 having a plurality of equally spaced threaded openings therethrough, a cover 26 and a plurality of machine screws or the like 28 securing the cover to the mounting flange to form a leakproof pressure-resistant seal.
In the embodiment illustrated, cover 26 is provided with several threaded openings in which are tightly secured fittings 30, 32 and 34 respectively. Fluid line 14 communicates with the upwardly and outwardly projecting portion of fitting 32 and secured to the lower or inward portion of the fitting is a generally cylindrical separator screen 36 disposed wholly within the separator and having its lower end pinched closed and sealed, as at 37. The lower portion of fitting 34 is provided with a similar but shorter separator screen 38 having a sealed end 39 and the upward projecting portion of the fitting is in fluid communication with a fluid line 41 for carrying compressed gaseous refrigerant from which the entrained oil has been removed out of the oil separator. The crankcase of the compressor is maintained in fluid communica tion with the oil separator by means of a fluid line 40 extending from the compressor to the upwardly or outwardly projecting portion of fitting 30. The lower inside end of the oil separator defines a sump 44 for collecting the separated oil, and a fluid line 42 extends from the lower inner portion of fitting 30 to a point below the level of oil in sump 44. The passage of fluid from sump 44 through fluid lines 42 and 40 to the compressor crankcase is regulated by means of a float valve indicated generally at 46.
From the oil separator the compressed gaseous refrig erant passes through fluid line 41 to a condenser 43 wherein it is cooled and condensed. The condensed refrigerant passes from condenser 43 through a fluid line 45 and an expansion valve 44 into an evaporator 49. As the condensed refrigerant passes through the evaporator it evaporates and absorbs heat from the surrounding medium to cool the latter, after which the evaporated refrigerant passes into fluid line 12 which carries it back to the inlet of the compressor. Aflixed to evaporator discharge line 12 is a bulb 51 containing a thermo-responsive fluid which is communicated through a fluid line 53 to the expansion valve to control the latter. The refrigway 54, bushing 52 serving as a valve seat.
the gaseous flow from separator screen 36 toward separator screen 38 which serves to further coalesce and separate any remaining entrained oil in the refrigerant stream. Screens 36 and 38, which may be several layers thick, also may act to some extent as mechanical filters.
,As oil is removed, it collects in sump 44 thus gradually increasing the level thereof. When the level reaches a predetermined point float valve 46 opens to allow oil in the sump to be forced by the high pressure refrigerant in the oil separator through lines 42 and 40 to the compressor crankcase. If foreign matter was originally present in this oil it will for the most part be removed by the filtering action of screen 36 or it will simply drop to the bottom of sump 44 under the influence of gravity so that the oil returning to the compressor will be cleaned. Since the inlet of fluid line 42 is disposed below the normal level of oil in the sump there is no chance of refrigerant escaping through fluid lines 42 and 40 to the crankcase of the compressor. The arrangement of the oil separator components may of course be rearranged, depending on the application contemplated.
The details of construction of the float valve are best illustrated in FIGURE 2. The lower end of fluid line 42 is sealingly positioned within one end of a valve housing 48 having a longitudinally extending bore therethrough communicating with line 42. This longitudinal bore has a first relatively small diameter portion 50 having a valve I seat bushing 52 therein through which extends a passage way 54 communicating with fluid line 42. Adjacent portion 50 the longitudinal housing bore has a slightly enlarged portion 56 and adjacent it a further enlarged portion 58, a shoulder 59 being defined therebetween. The upper end of bore portion 56 is placed in fluid communication with the sump by means of a plurality of radially pivotally supporting the mounting arm or lever 66 of a suitable float 68. On the opposite side of pivot pin 64 .from float 68 mounting arm 66 is provided with an- .other pin 70 pivotally supporting for vertical reciprocation a valve element 72. The two pivots should have 'suflicientbacklash so they will not bind as the valve element reciprocates.
This tendency to bind is further reduced by positioning pivots 64 and 70 substantially along a line perpendicular to the axis of the valve element when the latter is centered in its normal range of travel.
Valve element 72 is provided with a conical upper portion 74 adapted to operate as a needle valve for passage- The intermediate portion 76 of valve element 72 is of a diameter slightly less than that of bore portion 56 and the lower end portion 78 is of a diameter slightly less than that of bore portion 58, a shoulder 80 being defined between portions 76 land 78 of the valve element. The valve element is also constructed so that shoulder 80 will be spaced axially from shoulder 59 of the valve housing when the valve is closed, as shown in FIGURE 2. Thus, there is defined a chamber 82 between the valve element and housing and shoulders 59 and 80.
Chamber 82 is positioned below the norm-a1 liquid level in sump 44 and therefore is always maintained full of the separated liquid by virtue of the clearance between the valve'element and the hOuSing. This chamber therefore acts as a dash pot or dampening device for resisting sudden reciprocations of the valve element. Consequently, when float 68 tends to bob up and down unnecessarily, such as due to sloshing or shifting of the liquid in the sump, a frequent occurrence in mobile applications, this motion is restrained by the dash pot to reduce the hammering of conical needle valve portion 74 upon the valve seat which would otherwise occur. On the contrary, the dash pot function of chamber 82 prevents the transmission of relatively high frequency changes in the fluid level to the needle valve and allows the valve to operate only upon the occurrence of relatively large and slow changes in the liquidlevel. As a consequence, valve life is greatly increased and the operating effectiveness of the valve is greatly improved. In addition, wear on the pivot pins and other moving parts is minimized. I
Although the clearance between the valve element and housing is shown to be relatively large in FIGURE 2, for purposes of illustration, it is in fact quite small, for example in the order of .0005 inch for a valve element having a large diameter of approximately 7 inch. The acutal clearance used will of course depend on the size of the valve and the degree of dampening desired. For a given dampening action larger valves Will have a greater clearance, and for a given size valve a smaller clearance will give greater dampening action. In addition, if desired the valve parts may be rearranged to function in a normally open manner rather than normally closed, as illustrated, depending on the specific application contemplated. Also the valve need not function as a needle valve, but may operate according to any other common valve principle.
Thus there is disclosed in the above description and in the drawings an exemplary embodiment of the invention which fully and effectively accomplishes the objects thereof. However, it will be apparent that variations in the details of construction may be indulged in without departing from the sphere of the invention herein described, or the scope of the appended claims.
What is claimed is:
1. A float valve responsive to the liquid level in a reservoir subject to relatively abrupt physical movements, comprising: a valve housing, a valve bore, a valve seat having a passage therethrough communicating with said valve bore, a valve element slidably positioned with- V in said bore and having a needle valve thereon adapted to below the level of liquid in the reservoir and said bore being slightly larger than said valve element whereby said dash pot is in fluid communication with the liquid in the reservoir, and a float operatively connected to said valve element opening and closing said passage in said valve bore in responsive to changes of the liquid level in the reservoir.
2. A liquid separator comprising: an enclosed casing; inlet and outlet passages extending through said casing; separation means inside said casing for removing a liquid from a gaseous fluid entering said casing through said inlet passage; a reservoir in said casing for collecting liquid removed by said separator means; a liquid passage extending through said casing for removing liquid from said reservoir; a valve operatively associated with said liquid passage for controlling the flow of liquid therethrough, said valve being disposed below the normal liquid level in said reservoir and including a housing having a bore therein; a valve seat in said bore; a valve element slidably positioned within said bore having valve means cooperable with said valve seat; dampening means operatively associated with said valve element for reducing the operating sensitivity thereof to changes in said level due primarily to abrupt movement of said separator and to severe vibrations, said dampening means including an annular chamber defined by a shoulder in said bore and a facing shoulder on said valve element, and means for communicating liquid in said reservoir to said annular chamber; a radially extending passageway in said housing for communicating liquid in said reservoir to a point in said bore between said valve seat and said annular chamber; and a float operatively connected to said valve element for operating the latter in response to the level of liquid collected in said reservoir.
3. A liquid separator comprising an enclosed casing, inlet and outlet passages extending through said casing, separation means inside said casing for removing a liquid from a gaseous fluid entering said casing through said inlet passage, a reservoir in the bottom of said casing for collecting liquid removed by said separator means, a liquid conduit extending through the top of said casing and downwardly to a point below the normal liquid level in said reservoir for removing liquid therefrom, a valve operatively associated with the lower end of said conduit below said normal liquid level for controlling the flow of liquid through said conduit, said valve including a housing having a bore therein and a valve element slidably positioned within said bore, a float operatively connected to said valve element for operating the latter in response to the level of liquid collected in said reservoir and dampening means operatively associated with said valve element for reducing the operating sensitivity thereof to changes in said level due primarily to abrupt movement of said separator and to severe vibrations, said dampening means comprising a dash pot including an annular chamber defined by a shoulder in said bore and a facing shoulder on said valve element, the clearance between said valve element and said bore on each side of said annular chamber being suitable to provide for fluid dampening of movements of said valve element, and means for communicating liquid in said reservoir to said annular chamber.
4. A liquid separator comprising an enclosed casing, inlet and outlet passages extending through said casing, separation means inside said casing for removing a liquid from a gaseous fluid entering said casing through said inlet passage, a reservoir in said casing for collecting liquid removed by said separator means, a liquid passage extending through said casing for removing liquid from said reservoir, a valve operatively associated with said liquid passage for controlling the flow of liquid therethrough, said valve including a housing having a bore therein and a valve element slidably positioned within said bore, float means including an arm pivotally mounted on said housing and pivotally engaging said valve element for operating the latter in response to the level of liquid collected in said reservoir, and liquid dampening means operatively associated with said valve element for reducing the operating sensitivity thereof to changes in said level due primarily to abrupt movement of said separator and to severe vibrations, said dampening means comprising a dash pot including an annular chamber defined by a shoulder in said bore and a facing shoulder on said valve element, the clearance between said valve element and said bore on each side of said annular chamber being suitable to provide for fluid dampening of movements of said valve element, and means for communicating liquid in said reserevoir to said annular chamber.
References Cited by the Examiner UNITED STATES PATENTS 610,862 9/98 Helling 137398 XR 864,262 8/07 Robertshaw et a1 l37435 1,280,765 10/18 Kramer 6247O XR 1,627,020 5/27 Dougherty 251-48 XR 2,064,156 12/36 Firth 137435 2,190,138 2/40 Smith et a]. 55-219 2,760,596 8/56 Kellie 137-397 XR HARRY B. THGRNTON, Primary Examiner.
MEYER PERLIN, Examiner.