US2999629A

US2999629A - Interchangeable, hermetic and opentype refrigeration compressor

Info

Publication number: US2999629A
Application number: US808401A
Authority: US
Inventors: Soumerai Henri
Original assignee: Worthington Corp
Current assignee: Worthington Corp
Priority date: 1959-04-23
Filing date: 1959-04-23
Publication date: 1961-09-12
Anticipated expiration: 1978-09-12

Description

P 1961 H. SOUMERAI INTERCHANGEABLE, HERMETIC AND OPEN-TYPE REFRIGERATION COMPRESSOR Filed April 23, 1959 3 Sheets-Sheet 1 HENRI SOUMERAI ZNVENTOR. BY M 54 a 5 a FIG.3

p 1961 H. SOUMERAI INTERCHANGEABLE, HERMETIC AND OPEN-TYPE REFRIGERATION COMPRESSOR Filed April 25, 1959 3 Sheets-Sheet 3 HENRI SOUMERAI INVENTOR. M M

FIG.||

Unite This invention relates generally to compressors and more particularly to a refrigeration compressor having interchangeable components adapted to permit operation of the compressor with either hermetic or coupled drive units.

Designs of independent, hermetic type motor-compressor units or coupled (open type) motor-compressor units are known in refrigeration compressor art.

One of the problems in the present art has been to provide a refrigeration design which can be competi- ,tively manufactured wherein common components can be so interchanged that either open or hermetic type operation is available to the ultimate user.

The present invention overcomes this problem by providing la compressor-motor unit wherein the open and hermetic end bell adapters have connecting means and bearing means common to a compressor crankcase and crankshaft design such that the parts are easily interchanged for the desired open or hermetic compressormotor unit.

Accordingly, it is an object of the present invention to provide a compressor adapted to be driven either by a coupled (open type) motor or a hermetically sealed motor by joining the desired end bell adapter to the compressor crankcase and connecting or coupling the motor to the crankshaft in accordance with the desired operation.

It is another object of the present invention to provide an end bell adapter for a coupled (open type) compressor-motor unit which forms a chamber about the shaft seal to permit entering gas to cool the shaft seal during operation of the compressor-motor unit.

It is another object of the present invention to provide an end bell adapter for hermetically mounting the motor to the compressor crankcase which mounts the stator therein and permits altering the size of the stator so that various sizes of motors can be used with the same adapter.

1 Further objects and advantages of the invention will become evident from the following description with reference to the accompanying drawings in which:

FIGURE 1 is a side elevation of an open type motorcompressor unit showing a directly coupled electric motor.

FIGURE 2 is a vertical section taken through an open type compressor unit showing the invention as applied to this type unit.

FIGURE 3 is an end view of the compressor crankcase.

FIGURE 4 is a vertical section specific to the suction inlet adapter for a direct coupled unit.

FIGURE 5 is an end view of the suction inlet adapter. FIGURE 6 is a side elevation of a hermetic type motor-compressor unit.

FIGURE 7 is a vertical section through the bell adapter for a hermetic type motor-compressor unit showing only a fragment of the suction inlet and the compressor crankcase.

FIGURE 8 is a view showing means for modifying the mounting for the stator in a bell adapter for a hermetic type unit.

FIGURE 9 is a view of the end wall of the hermetic adapter shown in FIGURE 7.

tates Patent 4 Patented Sept. 12, 1961 FIGURE 10 is a cross-section taken on line 10-10 of FIGURE 7.

FIGURE 11 shows a longitudinal section of a hermetic adapter having another form of motor mounting means.

FIGURE 12 is a cross-section taken on line 12-12 of FIGURE 11.

Referring to the drawings, FIGURE 1 shows a coinpressor 1 coupled to and driven by a conventional electric motor 2. This type design is known as the open type motor-compressor unit as distinguished from the hermetic type motor-compressor unit shown in FIGURES 6 and 7 of the drawings wherein the electric motor is hermeti cally sealed from the atmosphere.

In the present invention since the compressor crankcase is identical for both types of units, only one crankcase is illustrated, as shown in FIGURE 2 of the drawings. A fragment of this same crankcase is shown for the hermetic type unit in FIGURE 7 of the drawings.

The compressor crankcase shown in FIGURES 2 and 3 of the drawings is a substantially hollow

vessel comprising sidewalls

5 and 6, an arcuate or top section 7 connecting the upper end of the sidewalls with a plurality of cylinder receiving portions 8 formed thereon at angles to each other, a lower or bottom section 9 connecting the lower ends of the sidewalls, and end walls 10 and 11 closing the respective ends of the crankcase.

Longitudinally and transversely in the crankcase and inwardly a spaced distance from the upper arcuate sec tion an arcuate partition 12 is connected so as to form, as shown in FIGURE 2, spaced chambers, delineated by the vertical partition 13 between the arcuate partition 12 and arcuate top section 7 into a suction manifold 14 and the discharge manifold 15. The suction manifold receivesrefrigerant through an arcuate opening 16 formed in the upper section of the end wall 11.

The respective end wall 10 at the discharge manifold end of the compressor crankcase and the end wall 11 having the arcuate opening 16 therein are provided with relatively large bearing mounting openings 17 and 18 in alignment with each other.

In the end wall 10 a bearing 19 is provided which is mounted in a bearing housing element 20 which closes the opening 17. This bearing supports one end of the crankshaft-generally designated 21 and the crankshaft 21 extends through the aligned opening 18 in the opposite end wall where it will be supported by hearing means 22 of substantially identical construction as carried on a'bearing support B formed on the end bell adapter generally designated S for the open type motor-compressor units or B on the end bell adapter H for hermetic units.

The crankshaft is identical for both the open and hermetic type motor-compressor units and as shown in FIGURE 2 extends outward of the bearing in the end wall 11 a predetermined distance such that it can be easily connected or coupled to the specific driving motor for the compressor utilized either for open or hermetic type arrangements.

Open type adapter Where it is desired to provide an open type motorcompressor unit for the above described compressor crankcase, the end bell or suction inlet adapter S as shown in FIGURES 4 and 5 is utilized.

The suction inlet adapter S is a cup-shaped cover-like element having a flange 23 about the periphery which is shaped to fit the suction inlet end of the compressor crankcase to which it is attached by any suitable means such as threaded members 24.

The end bell or suction inlet adapter S in assembled position is mounted about the portion of the crankshaft 21 which extends through the shaft mounting opening 18 for coupling connection to the rotor of the respective driving means and as indicated above the respective adapters which connect to the suction inlet end of the compressor carry thebearing which supports this end. of the crankshaft.

FIGURE 4 shows the end bell or suction inlet adapter having an axially projecting substantially annular bearing support B. The bearing support B has a length such that in assembled position it extends through the opening 18 into the compressor crankcase or sump 25, beyond the oint formed by the flange 23 and the end wall 11 of the compressor crankcase. At the point on the outer surface of the bearing sup- {port B which is in the plane of the arcuate opening 16 in the end wall 11 an annular disc-like element 26 is formed. annular element 26 has a diameter such that it will have a sliding fit with the inner surface of the shaft-receiving opening 18 formed in the end wall 11 when the flange 23 is connected to the end wall and in assembled position will act to center the bearing support relative to the axial line of crankshaft 21. v The depth of the suction inlet adapter further provides an annular chamber 27 adjacent the end Wall of the compressor crankcase. This chamber communicates on one side with the arcuate opening 16 and on the side remote therefrom with a suction inlet passage 28 formed in a boss 29 radially disposed on the suction inlet adapter S. The boss 29 provides means to connect the open-type machine to a conduit (not shown) which in turn connects to the source of refrigerant fluid. I Since the suction inlet passage 28 communicates with the fluid being compressed the fluid is delivered through the suction inlet passage 28, the annular chamber 27 and the arcuate opening 16 to the suction manifold 14 formed in the crankcase which in turn will deliver it through the suction valves (not shown) and the compressor cylinder 30 in a manner well known in the art. 2 .The bearing 22 mounted in the bearing support B receives oil by means of cored passage 31 and annular passage 32 which communicate with the lubrication systern in a manner well known in the art.

Inwardly of the outboard end of the bearing support a shaft-sealing cavity 33 is formed and FIGURE 2 shows a conventional rotary type shaft seal generally designated '34- disposed in this cavity. The shaft seal includes a hardened steel seat 35 formed on a closing member 36 for the shaft seal cavity, a carbon ring 37 in engagement with the seat 35 and a spring 38 which abuts between the carbon ring and a back-up stop ring 39 acts to hold the carbon ring in sealing engagement with the seat. This shaft seal 34 tends to run hot and it is cooled by oil metered through passage 40 andorifice 41 to the shaft-sealing cavity 33 and returned to the crankcase or rings through cored passage 42. The present construction permits of an advantageous result in that the annular chamber 27 permits cool refrigerant fluid to flow about the bearing support B where it acts to precool the oil before it passes to the seal. The construction also tends to prevent liquid slugging and serves to cool the oil returning to the lubrication system.

Hermetic type adapter When it is desired to provide a hermetic type motorcompressor unit for the above described compressor crankcase an end bell adapter H, as shown in FIGURES 7 and i8, is utilized.

The end bell adapter H comprises two parts: an end cover element 51 and a cylindrical section 52. The cylindrical section 52 can have any desired length and when augmented by suitable mounting as shown in FIGURES 7, 8' and ll will provide a versatile means of permitting various sizes and lengths of motors to be utilized and thus provide optimum operating conditions for any type unit.

For any given length of cylindrical section 52 we believe it clear that the same type end cover element 51 can be utilized to provide a complete end bell adapter H.

One form of cylindrical section for a hermetic adapter is shown in FIGURE 7. Another form of cylindrical section is shown in FIGURE 11. This latter form diifers from the form of cylindrical section shown in FIGURE 7 in that a modified means for mounting smaller size motor in 'a standard cylindrical section is shown. "This'is'. in keeping with the broad idea of providing standard and easily interchangeable parts for either the open or hermetic operation desired.

Thurs, referring to FIGURE 7, a cylindrical section 52 is shown as having an end wall 54 closing the end which will be disposed adjacent the suction inlet end of the compressor. crankcase and the end remote therefrom-or the outboard end being open so that the motor unit as hereinafter described can be fitted into the cylindrical section.

About each of the respective ends of the cylindrical section 52,

flanges

55 and 56 are provided for connecting the cylindrical sections to the suction inlet end of the compressor crankcase and the end cover unit 51, respec tively.

FIGURE 7 shows that in the axial line of the cylindrical section 52 a bearing support B' is provided which is substantially identical with bearing support B for the open type adapter. About the bearing support B substantially in line with the joint formed when flange 56 is connected to the compressor crankcase and radially spaced from the bearing support is an annular element 57 which as shown in FIGURE 8 has a sliding fit with the shaft-mounting opening 18 of the compressor in assembled position and thus acts to hold the bearing support on substantially the axial line of the crankshaft.

Radially about the upper portion of the end wall 54 are a plurality of communicating slots 58. These slots permit communication between the motor chamber 59 and the arcuate opening 10 formed in the end wall 11 of the compressor crankcase, and thus will permit flow of refrigerant or other gas through the cylindrical section and passage 16 to the suction manifold 14 as more fully described hereinafter.

In assembled position the crankshaft 21 rotates in a bearing 60 which is held in the bearing support B, and the crankshaft is so sized that it extends into the motor compartment 59 to receive the rotor 61 of the motor which is connected thereto by means of a quill shaft 62 keyed as at '63 to the shaft 21 and held from axial movement by locking washer 64 and threaded member 65, all of which is clearly shown in FIGURE 7 of the drawings.

FIGURES 7 and 9 show that the rotor in turn rotates in a stator 66 which mounts on a plurality of lands 67 between which are cored passages 68. The motor is disposed in the housing so that it abuts a pluralityof shoulders 69 at the end of the lands 67 adjacent the end wall 54 and the stator is held from axial movement by any suitable means such as a set screw (not shown) through the cylindrical section as is well known in the art. p The cored passage 68 and the air gap 70 between the rotor 61 and stator 66, communicate at both ends with the motor compartment so that refrigerant gas can pass around and through the motor to cool the motor and then pass through the communicating passages 57 and arcuate inlet 16 to the suction manifold 14.

Cylinder with modified mounting means for the motor FIGURES 11 and 12 show a cylindrical section 152 with a modified type mounting.

Thus, the lands 167 instead of being formed as integral parts of the cylinder wall will be independent elements mounted on reenforced ribs 168 spaced circumferentially on the inner wall of the cylindrical section 152 so that gas flow passages 169 are formed about the motor stator 170 mounted thereon. Thelands are machined to receive the stator and to form a shoulder as at171 against which the inboard end Another modified form of mounting means FIGURE 8 shows a fragment of a cylindrical section 252 substantially identical with cylindrical section 52 but having a still further modified form of mounting means.

In this form of the cylindrical section an annular member 253 is held in spaced relation with the inner wall of the cyindrical section 252 by circular rib 254. An annular lip or shoulder 255 is formed at the inboard end of the annular member 253 when the inner surface is machined to receive the stator 66 and serves to position the stator in the cylindrical section.

To permit fiow of gas from the outboard to the inboard end of the motor chamber 256 the rib 254 is provided with a plurality of sized slots 257 circumferentially spaced therein.

' End bell or cover Since the

cylindrical sections

52 and 152 are otherwise identical they will receive on their outboard end the end bell or cover 51.

The end bell or cover 51 is a semi-spherical hollow vessel having a flange 71 about its periphery for connect ing the vessel to the outboard flange 55 of the

cylindrical sections

52 or 152.

In assembled position it forms a suction inlet chamber 72 which communicates at one end with a suction inlet passage 73 formed in a boss 74 and with the motor compartment 59.

A sheet metal disc 75 in the suction inlet chamber 72 supports filters 76.

' In assembled position the boss 74 is connected to a source of refrigerant fluid or gas and thus the suction inlet passage 73 receives the refrigerant gas. The gas flows through the suction inlet chamber and thence through the filters into the outboard end of the motor compartment where it passes across the motor compartment through the cored passages 68 and the air gap 70 to the inboard end of the motor compartment. From the motor compartment the gas flows out of the cylindrical section through the communicating passages 57 and arcuate inlet 16 to the suction manifold in the compres sor crankcase. Thereafter the gas is passed through the suction inlet ports (not shown) to cylinders in the conventional manner in which reciprocating compressors are known to operate.

It will be understood that the invention is not to be limited to the specific construction or arrangement of parts shown but that they may be widely modified within the invention defined by the claims.

What is claimed is:

1. An end bell adapter means for an open ended compressor having a crankshaft extending a predetermined distance outwardly of the open end of the compressor comprising, a cylindrical section having at least one end wall with passages therein, and an end cover section, means on said cylindrical section to permit the cylindrical section to be connected to the end cover section at one end and to the open end of the compressor at the other end to provide a hermetically sealed chamber in assembled position, inlet means in said end cover in communication with said chamber, an axially extending bearing means in said end wall, an annular member formed on the bearing means, said annular member disposed in assembled position to seal the crankcase of the compressor and to position the bearing means for rotatably supporting the crankshaft extension.

2. In combination, a compressor, including, a crankcase having a suction manifold formed therein, spaced end walls on said crankcase, at least one of said end :alls having a passage formed therein in communication with said suction manifold, said end walls having openings formed therein in alignment with each other,

6 bearing means in the opening in said end Wall remote [from said communicating passage, crankshaft means having one end rotatably supported in said bearing means and disposed to extend through the crankcase and out through the oppositely aligned opening a predetermined length, a motor connected to said shaft for driving the compressor, end bell adapter means to be connected to said end wall receiving the shaft therethrough to form an inlet chamber with said end wall in assembled position in communication with said suction manifold,- said end bell adapter means having an axially extending bearing means, an annular element formed about said bearing,

means, said annular element in operative engagement with the opening in said last mentioned end wall to seal the crankcase from the suction manifold and to position the bearing means for rotatably supporting the crankshaft extension.

3. The combination as claimed in claim 2 wherein said end bell adapter means includes, seal means on the outboard side of the axially extending bearing means. 1

4. The combination as claimed in claim 2 wherein said end bell adapter means includes, sealing means on the out board side of the axially extending bearing means, and means on said adapter operatively connected to the seal for cooling the seal during operation of the compressor.-

5. The combination as claimed in claim 2 wherein said end bell adapter means includes, sealing means on the outboard side of the axially extending bearing means,- passage means in said bearing means for cooling fluid; said passage means in communication with said sealing means, and an orifice in said passage means to meter the cooling fluid passed to the sealing means.

6. The combination as claimed in claim 2 wherein said axially extending bearing means extends through the chamber to permit fluid in the chamber to pass about the bearing and to cool the bearing, and the end bell adapter means includes, sealing means thereon outboard of the axially extending bearing means, passage means for cooling fluid in the axially extending bearing means, said passage means in communication with said sealing means, and an orifice in said passage means to meter the cooling fluid passed to the sealing means.

7. The combination as claimed in claim 2 wherein said end bell adapter means includes, a cylindrical section and an end cover section, connecting means on said cylindrical section to permit the end bell to be. connected to one end and to connect the cylindrical section-to the end of the compressor having the passage means in com munication with the suction manifold whereby in assembled position a hermetic chamber is formed, and means on said cylindrical section to supportably mount the motor therein in spaced relation to the inner wall of said cylindrical section to provide flow passages about the motor from the outboard to the inboard side thereof.

8. The combination as claimed in claim 2 wherein-said end bell adapter means includes, 'a cylindrical section and an end cover section, connecting means on said cylindrical section to perrm't the end bell to be connected to one end and to connect the cylindrical section to the end of the compressor having the passage means in cornmunication with the suction manifold whereby in assembled position a hermetic chamber is formed, and means including a plurality of lands and downs on the inner wall of said cylindrical section for supportably mounting "said motor, stop means at the inboard end of said lands, said downs to provide passage means from the outboard to the inboard end of the chamber.

9. The combination as claimed in claim 8 wherein the adapter means to permit the motor to be connected for hermetic type operation includes, a cylindrical sec-- tion and an end cover section, connecting means on said cylindrical section to permit said end cover section to be connected to one end and said cylindrical section to be coupled to the compressor at the other end and to form a hermetic chamber therewith in communication with'theend wall having the passage, and means in said cylindrical section to supportably mount the motor.

10, The combination as claimed in claim 9 wherein the Supporting means for the motor comprises a plurality of lands anddowns, and stop means disposed at the inboard endof said lands, said downs to provide passage means about the motor from the outboard end to the inboard end. i Y

=1-1.- The combination as claimed in claim 9 wherein the supporting-means for the motor comprises, an annular platform in the cylindrical section, means holding said annular platform-in spaced relation to the inner wall of the cylindrical section, stop means at the inboard end of'said annular platform, and flow passages formed betweenthe platform and the-inner wall of the cylindrical section to pass fluid from the outboard to the inboard end of the chamber formed therein.

l2.-In combination, a compressor crankcase having a Suction manifold formed therein, an end wall at each end of said crankcase, at least one end wall having a passage in communication with said suction manifold, said end walls having openings in alignment with each other, bearing-means in the opening for one of said end Walls, crankshaft-means having one end supportably carried by said bearing. means and disposed to extend through the aligned opening in the opposite end wall a predetermined length, a motor for driving said compressor, means connecting said motor to the extended end of said crankshaft, at least one adapter means to permit said motor to be coupled to said shaft for open type operation, at least-one adapter means to permit said motor to be connected to said shaft for hermetic type operation, each of said adapters having substantially identical means to permit the adapters to-be independenly and alternately connected to the end of the compressor having the end wall with a passage therein and to form an inlet chamber in assembled position in communication with the passage and the suction manifold, and substantially identical hearing means on each of said adapters to be operatively associated with the aligned opening in the last mentioned end wall to seal the crankcase from the suction manifold and for rotatably supporting the extended end of the crankshaft.

. 13. The combination as claimed in claim 12 wherein the adapter means to permit the motor to be connected for open type operation has a semi-spherical housing, and seal means formed in said housing on the outboard side of the axially extending bearing means.

14. The combination as claimed in claim 12 wherein the adapter means to permit the motor to be connected for open type operation has a semi-spherical housing, said axially extending bearing disposed to extend inwardly through the chamber formed by the adapter in assembled position to permit fluid in said chamber to cool the bearing, seal means formed on said housing on the outboard side of the axially extending bearing means, and means on the axially extending bearing means to pass cooling fluid to said sealing means.

.15. The combination as claimed in claim 12 wherein the adapter means to permit the motor to be connected for open type operation has a semi-spherical housing, said axially extending bearing disposed to extend inwardly through the chamber formed by the adapter in assembled position to permit fluid in said chamber to cool the bearing, seal means formed on said housing on the outboard side'of-the ax ally extending bearing means, and passage means in the bearing means for cooling fluid, said passage means communicating with the seal means, and an orifice in said passage means to meter cooling fluid passed to said sealing means.

: 16. .In combination, a compressor crankcase having a suction manifold formed therein, an end wall at each end of said crankcase, at least one end wall having a passage in cornmunicationwith said suction manifold, said endwallshavingopeningsin alignment with each other,

bearing means in the opening for one of said end walls, crankshaft means having one end supportably carried by said bearing means and disposed to extend through the aligned opening in the opposite'end wall a predetermined length, a motor. for driving said compressor, means connecting said motor to the extended end of said crankshaft, at least one adapter means to permit said motor to be. coupled to said shaft for open type operation, at least one adapter means to permit said motor to be connected to said shaft for hermetic type operation, each of said adapters having substantially identical means to permit the adapters to be independently and alternately con'-' nected to the end of the compressor having the end wall with'a passage therein and to form an inlet chamber in assembled positionin communication with the passage and the suction manifold, and substantially identical bearing means on each of said adapters, a substantially identical annular member formed on each of said hearing means, said annular member to be operatively' as-' sociated with the aligned opening in the last mentioned end wall to seal the crankcase from the suction manifold and to position the bearing means for rotatably sup-, porting the extended end of the crankshaft.

17. An end bell adapter means for a compressor motor unit wherein the crankshaft extends through an opening at the end of the compressor crankcase adjacent the motor comprising, a semi-spherical housing, means in! cluding a flange about the periphery of the open end of the housing to permit the housing to be connected to said compressor to form a chamber in assembled position on the compressor, said housing having an inlet in communication with said chamber, axially extending bearing means on said housing disposed to seal the end of the compressor having the crankshaft extending therethrough, said axially extending bearing means to receive the ex-' tended portion of the crankshaft therethrough to rotatably support the crankshaft extension, means on said housing outboard of the bearing means to provide a seal for said crankshaft extension, and means in said housing to permit cooling fluid to be passed to said sealing means for cooling said seal during the operation of the compressor-motor unit.

18. In an end bell adapter means as claimed in claim 17 wherein said last mentioned means includes, passages in said bearing means for cooling fluid, said passages to communicate with the sealing means, and an orifice in said passages to meter the flow of cooling fluid to the sealing means.

19. An end bell adapter means for a compressor motor unit wherein the crankshaft extends through an opening at the end of the compressor crankcase adjacent the motor comprising, a semi-spherical housing, means including a flange about the periphery of the open end of the housing to permit the housing to be connected to said compressor to form a chamber in assembled position on the compressor, axially extending bearing means on said housing, said bearing means extending through the chamber to be cooled by fluid in said chamber and disposed in assembled position to seal the end of the compressor having the crankshaft extending therethrough and to rotatably support the crankshaft extension, means on said housing outboard of the bearing means to provide a seal for the crankshaft extension, and means in said bearing in communication with said sealing means to permit cooling fluid to be passed to the sealing means during operation of the compressor-motor unit.

29. An end bell adapter means for a compressor motor unit wherein the crankshaft extends through an opening at the end of the compressor crankcase adjacent the motor comprising, a cylindrical section, and an end cover section, means in said cylindrical section for supportably carrying the motor in spaced relation to the inner wall of the cylindrical section to provide passage means from the outboard to the inboard side of the motor, means on said cylindrical section .to permit the cylindrical section to be connected to the end cover section at one end and to the end of the compressor having the shaft extending therethrough at the other end to provide a hermetically sealed chamber for said motor in assembled position, an axially extending bearing means on said cylindrical section, said bearing means disposed in assembled position to seal the crankcase of the compressor and to rotatably support the crankshaft exten- S1011.

21. An end bell adapter means as claimed in claim 20 wherein said means in the cylindrical section for supportably carrying the motor includes a plurality of lands and downs, and shoulder means at the inboard end of said lands, said downs to provide passage means about said motor from the outboard to the inboard end of the chamber.

22. An end bell adapter means as claimed in claim 20 wherein said means in the cylindrical section for sup- 10 portably carrying the motor includes, an annular partition in said cylindrical section, means holding said annular partition in spaced relation to the inner wall of said cylindrical section, stop means on the inboard end of the annular partition, and means providing flow passages from the outboard to the inboard end.

References Cited in the file of this patent UNITED STATES PATENTS 1,107,687 Merralls Aug. 18, 1914 1,565,640 Green Dec. 15,1925 1,761,036 Greenwald June 3, 1930 1,917,760 Geiger July 11, 1933 2,138,093 Feldbush et a1. Nov. 29, 1938 2,466,193 Anderson Apr. 5, 1949 2,752,088 Borgerd et a1. June 26, 1956 2,862,656 Kadison Dec. 2, 1958