US3499600A

US3499600A - Rotary compressor

Info

Publication number: US3499600A
Application number: US714948A
Authority: US
Inventors: Ralph Mcgregor
Original assignee: Whirlpool Corp
Current assignee: Whirlpool Corp
Priority date: 1968-03-21
Filing date: 1968-03-21
Publication date: 1970-03-10
Anticipated expiration: 1987-03-10

Description

March 10,1970 R MCGVIREVGORIV "33199300 T ROTARY- COMPRESSOR Filed March 2;, 196g 2 Shets-Sheet -1 FIGI V v I H98" Flee FIG? ROUND CYL. CONTOURED CYL. r i vENTOR RALPH M5GREG0R BY ,/W:%M.

' ATTORNEY-S.

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50235 2. mohom 20E 82520 DEGREES FROM CONTACT POINT E El United States Patent 3,499,600 ROTARY COMPRESSOR Ralph McGregor, Evansville, Ind., assignor to Whirlpool Corporation, a corporation of Delaware Filed Mar. 21, 1968, Ser. No. 714,948 Int. Cl. F04c 17/00, 29/02, 3/00 US. Cl. 230153 6 Claims ABSTRACT OF THE DISCLOSURE A rotary compressor having a rotor provided with a diametrical slot. A single blade is slidably positioned in the slot and has opposite arcuate end portions slidably engaging the wall defining the cylinder chamber. The compressor includes a centrifugal pump for pumping oil upwardly through the rotor shaft to lubricate the rotor in the cylinder. An electric motor is disposed within the compressor housing for driving the rotor and the centrifugal pumping means.

This invention relates to compressors and in particular to rotary compressors.

In one form of rotary compressor, the rotor is provided with a diametric slot in which is received a single :blade having ends slidably engageable with the walls of the cylinder chamber. The rotor is eccentrically rotated in the chamber and, thus, the blades serve to compress gas therein and deliver it through an outlet substantially at the point of closest disposition of the rotor to the chamber wall. The present invention comprehends an improved blade structure having an improved sliding' engagement with the chamber wall throughout 360 rotation of the rotor, and an improved pumping means for delivering oil to the rotor to lubricate the same in the cylinder.

Thus, a principal feature of the present invention is the provision of a new and improved rotary compressor structure.

Another feature of the invention is the provision of a new and improved single blade structure for use in a rotary compressor. 2

A further feature of the invention is the provision of such a single blade rotary compressor structure wherein the blade is provided with opposite arcuate tips each having a center of curvature on the longitudinal centerline of the blade with the chamber defining a wall which is tangent to and in contact with the blade tips for substantially all rotational positions of the rotor.

A yet further feature of the invention is the provision of such a rotary compressor including new and improved means for lubricating the rotor.

Another feature. of the invention isthe provision of such a rotary compressor wherein the lubricating means includes means defining an open oil passage to the rotor,

means defining an oil sump in the housing, and means for pumping oil from the sump through the passage to lubricate the rotor in the cylinder.

A yet further feature of the invention is the provision of such a rotary compressor wherein the pumping means FIGURE 2 is a horizontal section taken substantially along the line 2-2 of FIGURE 1;

hFfIGURE 3 is a side elevation of the rotor and attached 8 a t;

FIGURE 4 is a fragmentary enlarged vertical section taken substantially along the line 44 of FIGURE 2;

FIGURE 5 is a fragmentary enlarged vertical section taken substantially along the line 5P5 of FIGURE 2;

'FIGURE 6 is a fragmentary enlarged vertical section taken substantially along the line 6-6 of FIGURE 2; FIGURE 7 is a fragmentary enlarged vertical section taken substantially along the line 7 7 of FIGURE 2;

FIGURE 8 is a diagrammatic fragmentary enlarged horizontal section illustrating the mathematical generation of the cylinder chamber with respect to the rotor and blade;

FIGURE 9 is a graph illustrating an improved characteristic of the rotary compressor hereof;

FIGURE 10 is a plan view of the rotor and compression chamber illustrating the relationships of FIGURE 9; and

FIGURE 11 is a horizontal section taken substantially along the line 11--11 of FIGURE 1.

In the exemplary embodiment of the invention as disclosed in the drawing, a rotary compressor generally designated 10 is shown to comprise a hermetically sealed hon-sing 11, a front head 12, a cylinder 13, and a rear head 14. The cylinder 13 defines a compression chamber 15 in which is rotatably received a rotor 16. Integral with the rotor is a depending shaft 17 rotated about the axis thereof by a conventional electric motor 18 in' the lower portion of housing 11. As shown in FIGURE 3, shaft 17 includes a hollow axial oil passage 19. An oil pickup tube 20 is carried by the shaft 17 to depend from the lower end thereof and to serve as a centrifugal pump for delivering oil, collected in the lower sump portion 21 of the housing, upwardly to the rotor 16 through the oil passage 19. As best seen in FIGURE 2, the rotor 16 within the cylinder 13 is eccentrically disposed therein so as to be most closely juxtaposed to a wall 22 of the chamber 15 at 23. The rotor is provided with a diametric slot 24 in which a single blade 25 is slidably received for longitudinal reciprocable movement relative to slot 24. The blade 25 has a length preselected to cooperate with the configuration of the chamber wall 22 to maintain sliding contact of the blade ends 'with the chamber wall for substantially all rotational positions of the rotor.

More specifically as shown in FIGURE 8, each of the opposite ends 26 of the blade 25 is arcuate having a center of curvature 26a on the longitudinal centerline 27 of the blade. The chamber wall 22 has a contoured configuration causing it to be tangentto and in contact with each of the blade tips for substantially all rotational positions of the rotor, whereby the blade, as a result of the rotation of the rotor in the chamber 15, causes gas therein to be compressed and urged toward an undercut transfer slot 28 of the chamber adjacent point 23. In the illustrated embodiment, the chamber wall defines a curve with respect to x and y axes of a coordinate system with the y axis passing through the point of contact between the rotor and cylinder and the center of the rotor and the x axis passing through the center of the rotor, the curve having coordinates x=r sin 0+ sin (0x), y=r cos 0|p cos (0x), where 0 is the angle between the y axis and the centerline of the blade, x is the angle between the point of contact of the blade with the chamber wall and the longitudinal centerline of the blade with its vertex at the center of curvature of the blade tip, 9

is the radius of curvature of each of the tips, and r is computed from the formula where R is the rotor radius and a is the distance between the rotor and the cylinder wall on the y axis on the side of the rotor opposite its point of contact with the cylinder wall.

The contoured configuration of chamber wall 22 deviates from a round cylinder having a diameter equal to the dimension of the contoured cylinder taken through point 23 and the center of the cylinder as illustrated in FIGURES 4 through 7 and where the dimension b represents the deviation therefrom. The cross-sectional area of chamber adjacent the transfer slot 28 is substantially greater than that of a round cylinder permitting the compressor to handle liquids more readily and effectively minmizing re-expansion of compressed gas in the outlet, thereby causing the discharge pressure to more closely approximate the highest pressure within the compression chamber 15.

By reference to FIGURES 4 through 7 and 10, it may be seen that the greatest absolute deviation from the round cylinder configuration is at the points approximately 90 and 270 away from the point 23. No deviation from the cylindrical configuration obtains at the diametrically opposite point, as illustrated in FIGURES 7 and 10.

Referring to graph of FIGURE 9 and the schematic representation of the rotor and chamber configuration of FIGURE 10, it may be seen that a substantial increase in the cross-sectional area of the chamber is obtained by use of the contoured cylinder wall 22 as compared to a round cylinder wall. There is an approximately increase in the cross-sectional area occurring 10-15 from the contact point 23, and an approximately 11% increase occurring at a point approximately 80 away from the contact point. This is further illustrated in the curves of FIGURE 9 indicating the distance from the rotor to the cylinder wherein the curve illustrating the distance relative to the contoured curve of wall 22 rises substantially faster as it moves away from the contact point than does the curve representing the round cylinder configuration. The angular measurements referred to in the graph of FIGURE 9 are illustrated in FIGURE 10 as being measured from a zero angle at point 23.

As briefly indicated above, the use of the single blade in compressor 10 permits an improved facilitated lubrication of the rotor 16. As shown in FIGURE 3, the shaft 17 is provided with a pair of ports 30 opening from th oil passage 19 into an outwardly opening annular recess 31 in the shaft.

Oil grooves

32 and 33 extend downwardly and upwardly respectively from the recess 31 for conducting lubricating oil therefrom to suitably lubricate the shaft 17. An annular recess 34 is provided in the underside of the rotor 16 for receiving oil from the upper groove 33 to lubricate the lower face of the rotor 16. The rotor is further provided with a pair of holes 35, see FIGURE 2, which receive oil from the groove 34 and permit transfer of oil to the upper face 37 of the rotor 16. The holes also provide a path for oil to reach the surface of blade 25, thereby lubricating the blade. A bore 38, FIGURE 1, in the rear head 14 opens to the upper end of the oil passage 19 to vent vapor which may form in the lubricant as a result of heating dissolved refrigerant within the lubricant. Because of venting such vapors, lubrication is enhanced by precluding vapor pockets which might prevent proper lubrication. The single blade 25 makes possible the use of bore 38 as a vent in that pressure variations between different locations within the compressor have no effect on blade contact with cylinder wall 22. For example, in a two blade compressor as 4 the movement of the blades during their rotation within the cylinder. If the underblade pressure were greater than the cylinder or compression chamber pressure, the blades would be forced against the cylinder wall to create a braking effect and if the underblade pressure were less than the cylinder pressure the blades would tend to be drawn away from the cylinder wall thereby allowing gas to pass by the blade.

With the single blade construction it is obvious that the problem of underblade pressure is obviated. Without the underblade pressure problem it is possible to provide the aforementioned vent. It will be clear also that the pressure within housing 11 is immaterial to the effective operation of a compressor of the type described. Thus the compressor may be operated with either a low or high pressure housing without creating lubrication problems. It will be noted that all surfaces to be lubricated, except the cylinder wall, are in direct communication with the interior of housing 11 and thus at approximately housing pressure. This permits use of a simple centrifugal pump to move lubricant to the surfaces to be lubricated. The pump may best be understood by referring to FIGURES l and 11. The pump comprises oil pickup tube 20 and-a sheet metal vane 20a positioned diametrically within the lower portion of tube 20. Oil enters tube 20 from oil sump 21 through a hole 20b and is carried by centrifugal force up the lower curved wall of tube 20. The oil moves upwardly into the area of vane 20a which precludes slippage of the oil relative to the inner wall of tube 20. The centrifugal force imparted to the oil entering hole 20b and moving up the lower curved wall of tube 20 is sufiicient to cause oil to move upwardly through the paths previously described to lubricate the compressor.

Suflicient lubricant is supplied to cylinder wall 22 by leakage and by being carried through the refrigeration system with refrigerant.

Thus, the lubrication system of compressor 10 eliminates the need for pressure differentials within the compressor to effect lubrication of the moving parts thereof. Rather, a simple centrifugal pumping means may be provided to effect the desired lubrication of the shaft and the rotor. Resultingly, the compressor may be utilized as either a high side or a low side pump.

The vane 25 is effectively accurately positioned at all times within slot 24 by the tangential engagement of the chamber wall 22 therewith. The lubrication of the rotor is substantially simplified as a result of the lack of underblade pressures resulting from the use of the single blade 25. Thus, the oil grooves may be formed at any desired position and arranged to have any desired length along the rotor shaft thereby permitting maximum efiiciency in lubrication of the shaft while yet preventing adverse eifect of the direct communication of the oil passages with the blade slot. Further, the lubrication passages may be vented to eliminate pockets of gas therein further improving the efficiency of lubrication.

While I have shown and described one embodiment of my invention, it is to be understood that it is capable of many modifications. Changes, therefore, in the construc tion and arrangement may be made without departing from the spirit and scope of the invention as defined in the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as folows:

1. In a rotary compressor having a housing, front and rear heads in said housing, a cylinder between said front and rear heads defining a compression chamber opening to said heads, a cylindrical rotor eccentrically positioned in said chamber and defining a diametric slot, a motor for rotatably driving said rotor about its axis, blade means comprising: a one-piece blade positioned in said slot for longitudinal reciprocal sliding movement therein and having integral opposite fixed arcuate tips each having a center of curvature on the longitudinal centerline of said blade, said chamber defining a wall which is tangent to and in contact with said blade tips for substantially all rotational positions of said rotor, whereby said blade causes gas in said cylinder to be compressed toward an outlet at the point of closest disposition of said rotor to said chamber wall, said wall having a contour defined by a curve having coordinates x=r sin 0+, sin (0+x) and y=r cos 0+ cos (0-x) where the y axis passes through the point of contact between the rotor and chamber wall and the center of the rotor and the x axis passes through the center of the rotor perpendicularly to the y axis, 6 is the angle between the y axis and the centerline of the blade, x is the angle between point of contact of the blade with the chamber wall and the longitudinal centerline of the blade with its vertex at the center of curvature of the blade tip, ,0 is the radius of curvature of each of the tips, and r is computed from the formula where R is the rotor radius and a is the distance between the rotor and the cylinder wall on the y axis on the-side of the rotor opposite its point of contact with the cylinder wall.

2. The rotary compressor structure of claim 1 wherein said tips are segmentally cylindrical each having its axis parallel to the rotor axis.

3. In a rotary compressor having a housing, front and rear heads in said housing, a cylinder between said front and rear heads and defining a compression chamber opening to said heads, a cylindrical rotor eccent'rically positioned in said chamber and defining a diametric slot, a motor for rotatably driving said rotor about its axis, and a one-piece blade with fixed tips bearing directly upon the interior of said cylinder positioned in said slot for longitudinal reciprocal sliding movement therein, means for lubricating the rotor comprising: means defining an oil passage through said rotor and openly communicating at one end portion with said diametric slot and the interior of said housing, said passage further having an opposite end portion; means defining an oil sump in said housing; and means for pumping oil from said sump through said passage opposite end to said rotor to lubricate said rotor in said cylinder.

4. The rotary compressor structure of claim 3 wherein said oil pumping means comprises a centrifugal pumping means.

5. The rotary compressor structure of claim 3 including means for venting said oil passage.

6. The rotary compressor structure of claim 3 includ ing means for venting said oil passage comprising a passage in said rear head opening into the interior of said housing, said oil passage including a portion extending through said cylinder opening to said venting passage.

References Cited UNITED STATES PATENTS 1,742,731 1/1930 Shore 230153 1,114,046 10/1914 Roessler 230153 1,719,134 7/1929 Roessler 230153 X 1,719,135 7/1929 Roessler 230-153 X 1,781,073 11/1930 Nielsen 230-153 1,967,033 7/ 1934 Lipman 2.30-153 X 2,233,082 2/1941 Kucher 230153 2,623,365 12/1952 Daniel 230151 X 2,877,946 3/1959 Garrison et a1 230153 3,285,504 11/1966 Smith 230-207 DONLEY I. STOCKING, Primary Examiner W. I. KRAUSS, Assistant Examiner US. 01. X.R.

P0-1D5D UNITED STATES PATENT OFFICE (5/69) CERTIFICATE OF CORRECTION Patent No. 3,499, 600 Dated March 10, 1970 lnve l-( Ralph McGregor It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim 1, column 5, line 7, the equation "x=r sin 6+p sin (6+x)" should read x=r sin 6+p sin (B-x) SIGNED AN'D SEALED JUL 141970 Attcal:

EdwlrdMFletchor, Ir. ull E.' BGH'UYIIER, JR. s officer Oomissioner of Pat-ante