US2713969A - Compressor unloader - Google Patents

Description

F, 5. LA FLAME ET AL 2,713,969

COMPRESSOR UNLOADER July 26, 1955 2 Sheets-Sheet 1 Filed June 8, 1951 July 26, 1955 LA FLAME ET AL COMPRESSOR UNLOADER 2 Sheets-Sheet 2 Filed June 8, 1951 [RI/shirts fran/iZILafZame euui Earl I'Huficzc'ker f WW). 21m

United COMPRESSOR UNLOADER Application June 8, 1951, Serial No. 230,506

Claims. (Cl. 230-138) This invention relates, in general, to refrigerating apparatus and has particular reference to an improved mechanism for unloading a refrigerant compressor which, for example, is advantageously adaptable for employment in refrigerating systems of a type wherein a refrigerating medium is circulated through a closed system and is successively compressed in a gaseous state, condensed into a liquid and then expanded by evaporation by a relatively high pressure.

Otherwise stated, the invention is embodied in a simple and inexpensive means for unloading a refrigerant compressor.

More specifically stated, it is an object and accomplishment of the invention to provide an improved mechanism permitting a balance of pressures within the cot pression chamber so as to unload the compressor and provide a more efficient and effective operation particularly at the start of the motor in the running cycle.

A further object and accomplishment of the invention is to provide an improved arrangement in which the unloading mechanism of a compressor is operated by lubricant normally supplied to the compressor bearings and employed in the instant invention as a liquid seal during the running cycle, said sealing arrangement being broken during the off cycle whereby the compressor will be unloaded.

An ancillary object and accomplishment of the invention is to provide a more efiicient refrigerating system having incorporated therein a new and improved compressor unloader which is adapted to be economically manufactured and which is designed so as to permit the manufacture and assembly thereof in accordance with present day large scale mass production manufacturing methods of construction.

The invention seeks, as a final object and accomplishment, to provide a refrigerating system which includes ates Patent a compressor unloader particularly characterized by a design arrangement to more advantageously and satisfac- 1 It is preferred to accomplish the various objects of this invention and to practice the same substantially as hereinafter more fully described, and as more particularly pointed out in the appended claims.

Embodiments of the invention are illustrated in the accompanying drawings forming a part hereof and where- Fig. 1 is a sectional view of a refrigerant compressor having incorporated therein a compressor unloader embodying the features of the present invention, this view being taken substantially on the plane of the line 1-1 in Fig. 3;

2,713,969 Patented July 26, 1955 Fig. 2 is a fragmentary sectional view of a portion of the compressor depicted in Fig. 1 and being taken substantially on the plane of the line 22 in Fig. 3;

Fig. 3 is a plan view of a portion of the compressor depicted in Fig. 1 and being taken substantially on the plane of the line 3-3 in Fig. l; and

Fig. 4 diagrammatically illustrates a refrigerating systern incorporating the compressor and the compressor unloader embodying the features of this invention.

The drawings are to be understood to be more or less of a schematic character for the purpose of illustrating and disclosing typical or preferred forms of the improvements contemplated herein and in the drawings like reference characters identify the same parts in the several views.

As one possible example of advantageous employment of the refrigerant compressor unit having incorporated therein the compressor unloader embodying the features of the present invention, reference is made to the drawings, particularly Fig. 4, wherein there is illustrated the refrigerant compressor unit and designated in its en- 'rety by the letter A as being adjunctively employed, for example, with a conventional refrigerating system designated in its entirety by the letter B.

The illustrated refrigerating system B may comprise the motor compressor unit A, herein shown as being of the hermetically sealed type, and a directly connected condenser. After undergoing compression, the hot refrigerant flows through a discharge line 12 and through the convolutions of a first condenser 13 which is aircooled in the conventional manner, this extraction of heat being effective toreduce in some degree both the pressure and the temperature of the refrigrant, although both are quite high compared to the normal atmospheric conditions. After the mixed vapors and liquid refrigerant are discharged from the first condenser 13, they will flow through a conduit 14 into the head of the compressor A to lubricate the parts of the compressor and to cool the motor windings whereupon the refrigerant will pass out of the head 15 and through the conduit 16 to a second condenser 17. Fan blades 31a act as a separator for the Freon and oil and, because the oil droplets are heavier, they will remain in the compressor housing and eventually return to the oil reservoir.

After the mixed vapors and the liquid refrigerant are discharged from the condenser 17, they will flow through a conduit 10 into a valving device 19, which in this particular case is illustrated as a capillary tube or restrictor, which is connected to an evaporator 20. It is notable that the refrigerant is throttled in passing the restrictor 19 and thereafter will be expanded at the discharge side of the restrictor and will be further expanded in the evaporator 20 so that it will become quite cooled and is, therefore, capable of absorbing heat from the food storage compartment of the refrigerator (not shown) and from the contents thereof. After making its circuitous path through the evaporator, the expanded and expended refrigerant is then returned to the compressor unit A by means of a suction line 21, thus completing the closed circuit.

Sufiice it to say, since the invention is not particularly concerned with the precise construction of the entire refrigerating system as illustrated and/or its associated parts, they will not be further described in detail, and it is deemed suflicient for all'intentions and purposes herein contained to show only portions adjacent to and cooperating with the compressor unloader contemplated herein.

It is to be understood that details of construction of such refrigerating systems with which the refrigerant motor compressor unit and the compressor unloader'contemplated herein may advantageously be employed,

and/or their associated parts, may be modified to suit particular conditions or to satisfy the engineering'genius of various manufacturers, and we do not wish to be limited to the construction of these elements as set forth except where such construction particularly concerns the invention contemplated herein.

Having thus described, by way of example, a possible adaptation of the motor compressor unit and the compressor unloader and having described the general environment surrounding the adaptation, the specific construction and function of the parts of the motor compressor and the compressor unloader will now be described in detail.

Attention is now invited to Figs. 1 and 3 wherein there is shown the compressor construction embodying the features of this invention. It can be seen that reference numeraldesignates a conventional sealed casing which encloses a motor 31 and a rotary compressor 32. In accordance with the construction of this invention the motor drives the compressor through the centrally disposed drive shaft 35 which is journalled at the lower end portions thereof in a stationary support or bearing element 36. The rotary compressor comprises the conventional When the motor stops and the flow of oil into the cup discontinues, the level of lubricant within the cup 45 will gradually decrease due to the leakage of the lubricant through the bleed hole 65 until the level reaches the normal level of the lubricant disposed in the reservoir and as defined by the line 55. The drop of the lubricant level in the cup-like element 45 will unseal the v margins of the slot 42 and adjacent the sides of the blade cylindrical element 37 defining a centrally disposed compression chamber 38, said cylindrical element being disposed between the motor support bracket 39 and the end plate 40. I

A divided blade 41 is disposed in a slot 42 and is slidably supported therein and serves the conventional purpose of compressing refrigerant within the compression chamber 38. The divider blade 41 is biased inwardly by a spring 43, the outer end 44 of which abuts against a cup-shaped bracket 45 and the inner end 46 thereof being arranged engage Outer d portions 47 of the divider blade 41. a

The shaft 16 is provided with the usual eccentric portion 50 which cooperates with an impeller 51 to produce a pumping action. The compressor is provided with an inlet 52 and an outlet 53 in accordance with the usual 11- practice.

In Fig. 1 it can be seen that the lower portion of the casing 30 serves as an oil reservoir from which oil is supplied to-the bearing surfaces. In connection with this invention, it is particularly notable that the oil level indicated-by the line 55 is substantially below the top of the divider blade 41. The importance of maintaining this oil level will be apparent as the description proceeds.

The end plate 40 is provided with an oil inlet passage 58' from whence'lubricant is pumped to the bearing surfaces by' spiral oil feed grooves 59 provided on the peripheral surfaces of the eccentric 50 and the shaft 35, as shown; Thus, in Figs. 1 and 2, it can be seen that the oil will be pumped up through the spiral passages 59 and discharged adjacent the upper portions of the bearing block 60 as indicated by the arrows. to lubricate the various elements with which the lubricant comes in contact and thereafter being discharged so that a substantial portion thereof will be disposed in the cup-shaped bracket 45. While the compressor motor is running the flow of oil into the cup 45. as indicated will continue until the cup overflows the open top 61 which, it is important to understand, is substantially above the top of the divider 41 so that all of the regions adjacent the opening in the cylindrical element 37 through which the divider blade reciprocates is completely submerged in the lubricant contained in the cup-like bracket 45. Because of this there is.provided a liquid seal which, in effect, prevents leakage of the high pressure refrigerant to the low pres- ;sure side of the compression chamber 38 through the margins defined by the slot 42.

Particular attention is directed to a'relatively small bleed hole 65 (Fig. 2) disposed in the lower wall of the cup-like bracket and which permits oil to drain from the cup at a given rate which is less than the rate at which oil is fed into the cup during normal operation of the compressor. a

41 to permit a balance of pressures within the chamber 38 thereby to unload the compressor. This results in complete unloading of the compressor and the compressor will remain unloaded until the motor has been brought up to speed and long enough to replenish the supply of lubricant to the cup-like bracket 45 so that the level of the lubricant within the cup will rise to a point above the top of the divider blade 41 which will cause the sealing arrangement adjacent the outer portions of the blade 41 to take effect.

In connection with the teachings of this invention, it is important to note that the refrigerant will enter the motor compressor housing 30 via a conduit 70 which is connected to the suction line 21 and constitutes a part of the low side of the refrigerating system. In Figs. 1 and 3 it can be seen thatthe conduit 70 opens into a chamber 71 disposed in the cylindrical element 37, said chamber having at the lower portions thereof a spring pressed valve 72 adapted to open responsive to pressures of the refrigerant flowing from the chamber 71 into the inlet 52 of the compression chamber 38. The refrigerant is compressed in the compression chamber responsive to oscillation of the impeller 51 and thereafter is forced outwardly of the compression chamber 38 via the outlet 53 and into a conduit 75 having a connection 76 to the conduit 12. Disposed adjacent the outlet 52 there is provided a flap valve 77 which opens intermittently responsive to pressures emanating frorn'the compressed refrigerant from the compression chamber 38.

It is important to note that the relative disposition of the parts, that is to say, the impeller 51 and the valves 72 and 77 are shown in their position of rest when the motor is not running. Due to certain phenomena it has been found that the impeller 51 seeks the position of rest as shown when the motor is not running. Thus, when the motor is not running, compressed gases will remain in the chamber 80 defined by portions of the blade 41 and the engagement point 81 of the periphery of the impeller 51 with the wall of the compression chamber 38. As an example, the pressures in this defined chamber 80 are of the order of to pounds. Moreover, this chamber 80 constitutes a portion of the high side of the refrigerating system. I

Attention is now directed to a chamber 85 defined by portions of the blade 41 and thepoint of contact 81 of the periphery of the impeller 51 with the wall of the compression chamber 38. The pressures in chamber 85 are of the order of 15 to 25 pounds and constitute a portion of the low side of the refrigerating system. Moreover, it is important to note that the remainder of the areas disposed within the casing 30 are subjected to the high pressures of the refrigerant in the high pressure side. This is true because the refrigerant, after leaving the compressor, re-enters the head of the casing 30 via the conduit 14 where it is contained within the casing 30 to lubricate the parts and cool the motor windings and leaves the casing via the conduit 16.

In a condition as hereinbefore described, it can be seen that the pressures in the chambers 80 and 85 are unbalanced. This unbalanced condition results in an undue load being placed upon the motor at the start of the running cycle. This invention seeks to overcome this deficiency and effect a balancing of pressures in the chambers 80 and 85. Since the divider 41, during operation of the compressor, effectively seals off the chamber 80 from the chamber 85 the undesirable unbalanced condigarages V tion would prevail unless this seal between the chambers 80 and 85 could be broken.

As long as the level of oil in the cup-like bracket is well above the top of the divider 41 and portions adjacent the divider are submerged in the oil, there is provided an effective sealed relationship between the chambers 80 and 85; however, when the level of oil in the cup 45 is lowered below the top of the divider the sealed relationship is broken and the high pressure gases may then flow into the chamber 85 and become balanced with the pressure prevailing in the chamber 80 and in the remainder of the high pressure side of the refrigerating system. Immediately upon stopping the motor of the compressor the pressure of the refrigerant disposed in the chamber 71 will discontinue and by virtue of the spring pressure against the valve 72, the valve 72 will close and thus seal off the chamber 85 and prevent back charges of refrigerant from entering the suction line. Therefore, when the seal adjacent the divider is broken the pressures in the chamber 85 and adjacent the valve will'be balanced with the pressures of the refrigerant in the chamber 80. The balancing of the pressures in the chambers and permits an easy start of the motor thereby to effectively increase the life thereof.

In summary of the operation of the device, it may be stated that as the compressor is started, oil is picked up from the oil reservoir by the oil grooves 59 and is forced by the eccentric journal 50 through an oil passage and this oil is moved upwardly along the oil grooves disposed on the periphery of the shaft 35 and the spillage therefrom is trapped in the cup-like bracket 45 to a level well above the top of the blade 41. During the running cycle the cup-like bracket 45 will remain full and the excess will overflow therefrom, the oil contained in the cup-like bracket 45 providing a liquid seal of the blade against leakage of high pressure gas. During the off cycle the oil will drain from the cup-like bracket 45 via the bleed hole 65 and seek the normal oil level in the reservoir whereupon the seal across the blade is broken and the high pressure gas will be free to leak into the chamber 85 to form a balance of pressures in the charmbers 80 and 85.

Thus, it can be seen that we have provided a relatively simple means for unloading a compressor, said means being foolproof in operation and having no moving parts requiring adjustment, replacement or repair.

The instant compressor unloader being formed of simple parts and readily available materials, lends itself to mass production manufacturing principles, thus affording a substantial saving in the manufacturing cost.

From the foregoing disclosure, it may be observed that we have provided an improved compressor and compressor unloader which efiiciently fulfills the objects thereof as hereinbefore stated and which provides numerous advantages which may be summarized as follows:

1. Structurally simple, efficient and durable;

2. Economical to manufacture and readily adaptable to mass production manufacturing principles; and

3. The provision of a compressor unloader having no moving parts and yet permitting a balance of pressures within the compression chamber of the compressor so as to effectively unload the compressor and provide a more efficient and effective operation particularly at the start of the motor in the running cycle, this being accomplished by employing the lubricant normally supplied to the compressor bearings as a liquid seal adjacent the divider during the running cycle.

While we have illustrated preferred embodiments of our invention, many modifications may be made without departing from the spirit of the invention, and we do not wish to be limited to the precise details of construction set forth but wish to avail ourselves of all changes within the scope of the appended claims.

We claim:

1. A sealed unit containing a fluid compressor and a d motor for operating said compressor, said compressor including a stationary member having a compression chamber therein and inlet and outlet ports communicating with said chamber, a cylindrical member arranged within said compression chamber and rotatable therein by said motor, means adapted to cause fluid to be compressed between said members including a blade slidably mounted in a slot formed in said stationary member and cooperating with both of said members to define low and high pressure sides within the compression chamber, an oil reservoir having a normal oil level below a radial edge of said blade, means for supplying lubricant to operating parts of said unit, means including a cup-shaped bracket disposed exteriorly of said stationary member and-disposed adjacent said blade and adapted to receive lubricant during operation of the motor to a level to submerge said blade to provide a liquid seal between said blade and said slot to prevent leakage of discharge pressure gases from said high pressure side through said slot, said oil in said cup-shaped bracket being subjected to discharge pressure gas in said sealed unit during operation of said compressor, bleed hole means in said cupshaped bracket effective to lower the oil level in said cupshaped bracket to the normal oil level in the oil reservoir during inoperation of the motor to break the liquid seal thereby to permit leakage of discharge pressure gases into the low side of the compression chamber to balance the pressures and unload the compressor, and means including a spring one end of which being in engagement with portions of said cup-shaped bracket and the other end of which being in engagement with said blade to exert a force in a direction tending to urge said blade toward said rotatable member arranged in said compression chamber.

2. A sealed unit containing a compressor including a member having a compression chamber therein and provided with inlet and outlet ports communicating with said chamber, a rotor within said chamber, a motor for driving said rotor, a blade slidably mounted in said chamber intermediate said ports and defining low and high pressure sides within the compression chamber, a biasing means exerting at all times a force in a direction tending to move said blade toward said rotor, an oil reservoir having a normal oil level below a radial edge of said blade, a pump effective during operation of said compressor for circulating oil to operating parts thereof, a separate cup-shaped container defining a bracket for said biasing means and disposed adjacent said blade and adapted to receive pumped oil during operation of the compressor to a level to submerge said blade to provide a liquid seal along said blade to prevent leakage of discharge pressure gases from said high pressure side out wardly along said blade, said oil in said cup-shaped container being subjected to discharge pressure gas in said sealed unit during operation of said compressor, and bleed hole means in a lower wall of said cup-shaped container effective to lower the oil level in said cup-shaped container to the normal oil level in the oil reservoir during inoperation of the compressor and thereby to break the liquid seal and thereby to permit leakage of discharge pressure gases into the low side of the compression chamber to balance the pressures and unload the compressor.

3. A compression chamber provided with inlet and outlet ports comunicating with said chamber, a blade slidably mounted in said chamber intermediate said ports and defining low and high pressure sides within the compression chamber, means defining an oil reservoir having a normal level of oil only partially submerging said blade, a separate cup-shaped container disposed adjacent said blade and adapted to receive pumped oil during operation of the compressor to a level to submerge said blade to provide a liquid seal along said blade to prevent leakage of discharge pressure gases from said high pressure side outwardly along said blade, said oil in said cup-shaped container being subjected to compressor discharge pressure, and means forming a part of said cup-shaped container effective to lower the oil level in said cup-shaped container during inoperation of the compressor to break the liquid'seal thereby to permit leakage of discharge pressure gases into the low side of the compression chamber to balance the pressures therein.

4. The combination of a compressor and a compressor unloader; said compressor including a member having a compression chamber therein and provided with inlet and outlet ports communicating with said chamber, a rotor within said chamber, a motor for driving said rotor, a blade slidably mounted in said chamber intermediate said ports and defining low and high pressure sides within the compression chamber, a biasing means exerting at all times a force in a direction tending to. move said blade toward said rotor, an oil reservoir having a normal oil level only partially submerging said blade, and a pump effective during operation of said compressor for circulating oil to operating parts thereof; and said compressor unloader comprising means including a separate cup-shaped container defining a bracket for said biasing means and disposed exteriorly of said compression chamber and adjacent said blade and adapted to receive pumped oil during operation of the compressor to a level to submerge said blade to provide a liquid seal around the blade to prevent leakage of discharge pressure gases from said high pressure side outwardly along said blade, said oil in said cup-shaped containerbeing subjected to discharge pressure gas, and means forming a part of said cup-shaped container effective to lower the oil level in said cupshaped container to the normal oil level in the oil reservoir during inoperation of the compressor thereby to break the liquid seal thereby to permit leakage of discharge pressure gases into the low side of the compression chamber to balance the pressures and unload the compressor.

5. In a compressor comprising a member having a compression chamber therein and provided with inlet and outlet ports communicating with said chamber, a rotor within said chamber, a motor for driving said rotor, a blade slidably mounted in said chamber intermediate said ports and defining low and high pressure sides within the compression chamber, a biasing means exerting at all times a force in a direction tending to move said blade toward said rotor, an oil reservoir having a normal oil level only partially submerging said blade, and a pump efiective during operation of said compressor for circulating oil to operating parts thereof, those improve ments comprising means including a separate cup-shaped container disposed adjacent said blade and adapted to receive pumped oil during operation of the compressor to a level to submerge said blade to provide a liquid seal to prevent leakage of discharge pressure gases from said high pressure side outwardly along said blade, said oil in said cup-shaped container being subjected to discharge pressure gases, and bleed hole means in said cup-shaped container effective to lower the oil level in said cupshaped container to the normal oil level in the oil reservoir during inoperation of the compressor thereby to break the liquid seal thereby to permit leakage of discharge pressure gases into the low side of the compression chamber to balance the pressures and unload the cornpressor.-

References Cited in the file of this patent UNITED STATES PATENTS

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