US2947468A - Multi-stage centrifugal compressor - Google Patents

Description

D. H. TRYON MULTI-STAGE CENTRIFUGAL COMPRES Aug. 2, 1960 SOR 5 Sheets-Sheet 1 Filed Feb. 21, 1957 INVENTOR. Davao H'Tzwou Y AT TOQM EYs Aug. 2, 1960 D. H. TRYON MULTI-STAGE CENTRIFUGAL COMPRESSOR 5 Sheets-Sheet 2 Filed Feb. 21, 1957 INVENTOR. DAV: H.TQYOM Wmfi V3 Am ATTozuEXs Aug 2, i960 D. H. TRYON MULTI-STAGE CENTRIFUGAL COMPRESSOR 5 Sheets-Sheet 3 Filed Feb. 21, 1957 INVENTOR. Du-Nun H .Twvam AT To QM EYS Ago 196 D. H. TRYON 2,94%48 United States Patent MULTI-STAGE CENTRIFUGAL COMPRESSOR David H. Tryon, Sheridan, Wyo.,assignor of nine and onehalf percent to E. E. Lonabaugh, nine percent to Loyal Kirkland, five percent to G. S. Gwinn, seven percent to Robert Jurosek, and seven percent to Michael G. Jurosek, all of Sheridan, Wyo., five percent to Beverlee Nelson, Los Angeles, Calif., and six percent to Mary E. Krohn and Bud Edgar Krohn, both of Sheridan, Wyo.

Filed Feb. 21, 1957, Ser. No. 641,689 2 Claims. (Cl. 230-119) This invention relates to compressors, and more particularly to a centrifugal compressor of the multi-stage type.

A main object of the invention is to provide a novel and improved multi-stage compressor which is simple in construction, which has a relatively small overall diameter while at the same time having substantial capacity, and which is highly eflicient in operation.

A further object of the invention is to provide an improved multi-stage centrifugal compressor which is relatively inexpensive to manufacture, which is easy to assemble, and which is provided with an eflicient seal system whereby leakage therethrough is minimized.

A still further object of the invention is to provide an improved multi-stage centrifugal compressor which is relatively light in weight, which has high capacity for its weight and size, and which is provided with an axial entry discharge collector that is very eflicient but still does not appreciably increase the overall diameter of the compressor.

A still further object of the invention is to provide an improved multiple-stage compressor provided with radial impellers of the axial-discharge type, whereby the compressor has a high capacity for a given overall diameter, and whereby the cost of manufacture is relatively low for a given capacity of compressor, the compressor being rugged in construction, smooth in operation, and easy to maintain in eflicient operating condition.

Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings, wherein:

Figure 1 is an end elevational view of an improvedmulti-stage compressor constructed in accordance with the present invention.

Figure 2 is another end elevational view of the compressor, taken from the end thereof opposite that shown in Figure 1.

Figure 3 is a longitudinal vertical cross sectional view taken through the compressor on the line 33 of Fig tire 1. t

Figure 4 is a transverse vertical cross sectional View taken on the line 4-4 of Figure 3.

Figure 5 is a fragmentary front elevational view of the .first impeller employed in the compressor of Figures 1 to 4.

Figure 6 is an enlarged cross sectional detail view taken on the line 66 of Figure 5, showing the cross :sectional shape of one of the blades of the first impeller.

Figure 7 is a transverse vertical cross sectional view taken on the line 7-7 of Figure 3.

Figure 8 is a transverse vertical cross sectional view taken on the line 88 of Figure 3.

Figure 9 is an enlarged cross sectional detail view taken L on the line 99 of Figure 8 and showing the cross sectional shape of one of the blades of the second impeller .of the compressor. a

figure 10 is afragmentary longitudinal vertical cross sectional view of one end of a modified form of compressor according to the present invention.

Referring to the drawings, and more particularly to Figures 1 to 9, 11 generally designates an improved multistage compressor according to the present invention. The compressor comprises a first housing member 12, an intermediate housing member 13, and a third housing member 14. The housing members '12, 13 and 14 are secured together in a manner illustrated in Figure 3, namely, by means of interfitting shouldered flanges, such as the interfitting shouldered flanges 15 and 16 on the housing members 12 and 13, and the interfitting shouldered flanges 17 and 18 on the housing members 13 and 14, and by fastening bolts, such as the fastening bolts 19 and 20 engaged through the flanges 15 and 17 and threadedly engaging in the mating flange elements 16 and 18. t g

The housing members 12 and 13 are generally annular in shape at their intermediate portions, and are braced by longitudinally extending radial web elements, such as the web elements 21 and 22 which serve to strengthen the housing members without adding substantially to their weight.

The third housing member 14 comprises agenerally spiral chamber of expanding cross sectional area in a counterclockwise direction, as viewed in Figure 2, which communicates with an outwardly flaring discharge conduit 23 adapted to be connected to a receiving conduit into which the high velocity compressed fluid moving in a counterclockwise direction, as viewed in Figure 2, is discharged from the compressor. The first housing member 12 is formed with a generally annular fluid intake chamber 24 having the intake passage 25 adapted tobe connected to a suitable source of fluid to be compressed, such as through an air or gas intake conduit or register.

The intermediate housing member 13 is surrounded at its bottom portion with the apertured horizontal flange element 26, 26 by means of which the compressormay be secured to a suitable supporting surface. As will be apparent, the intermediate housing member 13 is the only member which is fastened to the supporting surface, whereby the remaining portions of the compressor may be detached from the intermediate housing member 13 without the necessity of removing the intermediate housing member 13 from its support.

As shown in Figure 3, the first housing member 12 is provided with the tapering inner wall 27 leading to the annular outlet passage 28 of the first housing member 12, the housing member being then formed with the flaring impeller chamber 29 in which is mounted the first impeller 30 of the compressor, presently to be described.

Designated generally at 31 is the impeller shaft of the compressor, said shaft being journaled at respective opposite end portions thereof, shown at 32 and 33. for rotation around the axis of the compressor in the proper direction to discharge the compressed gas in a counter' clockwise direction into the spiral chamber 14, as viewed in Figure 2, namely, in a clockwise direction, as viewed in Figures 4, 7 and 8.

The first housing member 12 is formed with a recess 34 in which is secured a generally annular bearing supporting block 35 provide-d with the bearing assembly 36 in which the reduced journal portion 33 of shaft 31 is sealingly and rotatably mounted. Secured to the block 35 around the end of the shaft 31 is a lubricant housing 37, and secured to housing 37 is a lubricant pump 38, for example, a gear pump, the driving shaft 39 of the pump 38 being coupled to the end of shaft 31 by a suitable coupling 40, as is clearly shown in Figure 3. Shaft 39 extends through a suitable sealed bearing 41 and rotates with shaft 31 to operate the gear pump38,

3 The inlet and outlet conduits of gear pump 38 are suitably interconnected with an inlet conduit 42 and an outlet conduit 43 for circulating lubricating oil through the bearing 36 and through the lubricant housing member 37 adjacent thereto.

As shown in Figure 3, a retaining washer 45 is engaged on a reduced end portion of shaft 31 adjacent the journaled portion 33 thereof, said washer being held in place by a lock nut 46 threaded on shaft 31 and rigidly securing the washer 45 in position. Secured in the inner end portion of the recess 34 is the annular oil seal 48 surrounding a shaft portion 49 adjacent to the journaled portion 33 thereof. A 'gas tight annular seal assembly 50 is' provided on the shaft portion 49 adjacent to the annular oil seal assembly 48.

The housing member 12 is formed inwardly adjacent to the oil seal 48 with an annular oil collection cavity 51 wherein excess lubricant may collect, said cavity 51 communicating with a: drain conduit 52 leading to a suitable excess oil collection reservoir.

The shaft 31 comprises an intermediate portion 53 of maximum diameter and respective portions 54 and 55 of reduced diameter on opposite sides of said intermediate portion 53. The first impeller assembly 30 is mounted on and rigidly secured to the reduced shaft portion 54, said first impeller assembly comprising a pair of impeller segments 56 and 57 keyed on the shaft portion 54 in alignment with each other and rigidly secured on said shaft portion by a lock nut 58 threaded on a threaded reduced portion 59 of shaft 31 located outwardly adjacent the shaft portion 54. Suitable keys 60 engage in key ways provided in shaft portion 54 and the impeller sections 56 and 57 to rigidly connect said impeller portions to the shaft portion 54 and to maintain the impeller portions in proper alignment.

The conduit 43 preferably leads to a common oil reservoir connected to the intake conduit 61 of the oil pump 38'. The conduit 52 is also connected to said common oil reservoir through suitable condensate-removing means, not shown, whereby the pressures on the opposite sides of the seal 50 are substantially equalized, minimizing the possibility of oil being drawn out of the bearing housing 37 into the impeller cavity or of vapor orgas leaking into the bearing housing and contaminating the lubricating oil.

Secured on the third housing member 14 around the journal portion 32 of shaft 31 is a gear housing 63 provided with the bearing assembly 64 in which the shaft portion 32 is rotatably mounted. An oil seal 65 is provided on shaft 31, said oil seal surrounding the shaft and being seated in the main wall portion 66 of housing-member 14, as shown in Figure 3. A gas tight seal 67 is provided on a shaft portion'68' adjacent the journal portion 32 of shaft 31, providing a gas tight seal between the shaft and the oil seal 65. An annular lubricant collection cavity 68 is provided in wall 66, and connected through said wall to said cavity is a drain conduit 69 leading through suitable condensate-removing means, not shown, to the lubricant reservoir previously mentioned to which the conduit 52 is connected.

Suitable conduit. means, not shown, connects the interior of the gear housing 63 to the oil pump 38, so that lubricant is. circulated through the gear housing 63 in the same manner as through. the previously mentioned housing 37.

Secured on the end of shaft 31 is a pinion gear 70 which is in meshing engagement with a spur gear 71 mounted on an input shaft 72 journaled at its intermediate portion in the gear housing cover 73 and journaled at its end portion in. a suitable bearing assembly 74 mounted in the gear housing 63. The cover 73 is provided with a bearing assembly 75 rotatably supporting the intermediate portion of the input shaft 72, as shown in Figure 3. As illustrated, the bearing assemblies 74 and 75 maybe ball-bearing units and may be suitably lubricated by passages communicating with the interior of the gear housing 63 arranged to provide circulation of oil to the bearing units.

Thus, oil from an inlet bore 101 passes through a special fitting 102 into arecess1110 and into a bore 103 in input shaft 72. A predetermined tolerance fit between fitting 102 and shaft 72 allows a'certain amount of oil to pass therebetween and thence into the bearing housing and finally through ball bearing 74 into the main gear housing. The remaining amount of oil flows through bore 103 until it reaches radial bores 106 in shaft 72, at which point it passes out of the shaft into the housing area adjacent to an oilseal 107, and thence back through bearing 75.

Lubrication of journal bearing 109 (for shaft portion 32) is provided by an oil input connection 111 which is located between radial fins 112 on the housing casting 63. A bore 114 is provided in said casting, which allows oil trapped between oil seal 65 and bearing 64 to return to housing area 116, Where it is allowed to pass out of said area through an oil return connection at 117.

A minute amount of oil may leak through seal 65, and this is taken care of in the following manner: A slinger ring 118 machined integrally with shaft portion 32 throws the oil into recessed annular chamber 68-where it collects and is drawn out through connection 69 by means of a vacuum or scavenger pump, not shown.

Since the absolute pressure on the impeller side of the seal will be considerably below ambient (14.7 pounds per square inch) when the compressor is operating as a steam vapor compressor on a vacuum type thermocompression distilling plant, it will be necessary that the pump removing the oil from the recess 68 maintain a suction pressure below the pressure existing in the recess. In the event that the pressure behind the impeller is above 14.7 pounds per square inch it will not be necessary to use a vacuum pump to remove the oil from recess 68. A simple drain is all that will be necessary.

Single double-row ball bearing 74 is secured to shaft 72 by means of a snap ring 122. A spacer sleeve 123 is located between bearing 74 and gear 71. The bearing fit between bearing 74 and housing 63 is loose enough to allow axial movement and thus compensate for any misalignment due to unequal thermal expansion of the shaft 72 and housing 63. No thrust loads are carried on this bearing.

Double-row ball bearing is locked on shaft 72 between a shoulder 130 on the shaft and a spacer 125, which is held tightly against the bearing by. the hub of a pulley 126 secured on the shaft. The shaft 72 is secured axially by this bearing, which is locked in place in housing 72 by a snap ring 128.

The first impeller 30 comprises the impeller section 57 and impeller section 56, as above described, rigidly secured on the shaft portion 54. The impeller section 57 is inwardly dished or recessed, as shown at 76 to provide clearance for the sleeve portion 77 of the interstage rotor 78, secured on intermediate shaft portion 53, as will be presently described. The dished recess 76 also reduces the weight of the impeller section 56 without affecting its efficiency.

The impeller sections 57 and 56 are formed with the mating vane elements 79 and 80, the vane element being substantially radial and the vane element 79 being arcuately curved in cross sectional shape, as illustrated in Figures 5 and 6 so as to change the direction of air flow received in the discharge portion 29 of the first housing member 12 from a tangential direction to a more nearly axial direction at the plane wherein the gas or fluid passes from between the vane segments 79 to the spaces between the mating vane segments 80. As above pointed out, the direction of rotation of shaft 31 is such that the impeller 30 rotates clockwise, as viewed inFigure 4. The gas is thus received substantially tangentially between the clockwise-rotating vane elements 79 in Figare 4. The gas is thus received in the intermediate housing member 13 from between the rotating vane segments 80 with a direction of movement which is substantially in the axial direction of the compressor.

As shown in Figure 3, the housing member 13 has an initial annular wall portion 81 defining an intermediate chamber which merges with a flaring annular wall portion 82 defining an outlet chamber. The annular impeller 78 is contained mainly in the convergent portion 81 of housing member 13, except for the sleeve portion 77 thereof which is in abutment with the inner portion of the dished surface 76. As shown, the impeller 78 is annularly recessed, and shown at 83, to lighten its construction. The rim 84 of the impeller 78 is seated in an annular recess formed in the adjacent rim portion of' the impeller section 56, the surfaces of the rim portions of the impeller 78 and the impeller segment 56 being substantially flush at their interengaging portions to provide a smooth contour for the passage of fluid therepast from between the radial vane segments 80. 9 As is clearly shown in Figure 3, the annular passage defined between the flaring discharge wall portion 29 of housing member 12 and the surfaces of the impeller segments 57 and-56 tapers in cross sectional area and is substantially of minimum cross, sectional area at the interengaging rim portions of impeller segment 56 and the intermediate impeller 78. The annular passage defined between the smoothly curved outer surfaces 85 of the intermediate impeller 78 and the annular converging wall 81 increases in cross sectional area toward the juncture of the converging annular wall portion 81 and the flaring wall portion 82, as shown in Figure 3, being of maximum cross sectional area at the end of the impeller 78, shown at 86. 1

The converging annular wall portion 81 is provided with the inwardly projecting stationary baffle vanes 87 whose inner edges are slightly spaced from and closely follow the contoured surface 85 of the intermediate impeller 78. As shown in Figure 7, the baffle vanes 87 are arcuately curved in a transverse vertical plane and also are shaped so that their lower edges 88 diverge toward the outlet chamber at relatively small angles with respect to radial longitudinal planes containing their innermost corners 89 and in a clockwise direction as viewed in Figure 7, which is the same as the direction of rotation of the impeller shaft portion 53 in said figure. The impeller 78 is formed along its contour with spaced grooves 90 defining ribs 91 between the grooves, said grooves 90 thereby forming portions of the conduit spaces defined between adjacent baflle plates 87. As is further shown in Figure 7, the arcuate baflle vanes are inclined inwardly in a generally blockwise direction toward the grooved surface of the impeller, thus conforming with the direction of rotation of the impeller and with the direction of movement of the gas flowing through said conduit spaces toward the outlet chamber.

When the fluid or gas is received between the vanes .87, the direction of the fluid is changed so as to move inwardly toward the axis of the shaft 31, and the velocity of the gas is partially converted into static pressure. In this respect, the action is similar to that provided by the diffuser guide vanes ina conventional centrifugal air compressor with the exception that the fluid flows inward instead of outward through the vanes. Also, because of the arcuate shape and clocckwise inward inclination of the bafilevanes 87, as viewed in Figure 7, the air flow is directed more nearly axially. The impeller 78 serves as a means for guiding the gas or fluid from the first impeller 30 into the portion of the compressor containing the second impeller, designated generally at 92, and also serves as a spacer between the impellers 92 and 30. Furthermore, the use of the intermediate rotor 78 eliminates the need for stationary castings between the first and second impeller stages and also eliminates interstage losses due to leakage through seals.

As shown in Figure 3, the second impeller 92 comprises the impeller segments 93 and 94 which are keyed on the shaft portion 55 and which are rigidly secured thereon by being clamped between the rotor 78 and a lock nut 95 engaged on a threaded reduced shaft portion 96 adjacent the shaft portion 55. As shown in Figures 8 and 9, the vanes of the impeller sections 93 and 94, shown respectively at 97 and 98, extendradially and are substantially flat. The outer edges of the vanes 97 and 98 are slightly spaced from and closely follow the inside con tour of the flaring wall 82 of housing member 13.

As has been previously mentioned, the third housing member 14 is formed with a centrifugal casing of constantly increasing cross sectional area in a clockwise direction, as viewed in Figure 8, which terminates in the outlet portion 23. The annular rim of the impeller segment 94, shown at 99, is received in and is freely rotatable in an annular groove 100 formed in the wall 66 of housing member 14. The rim 99 is thus arranged to provide a substantially continuous surface contour as between the peripheral surface of the impeller section 94 and the adjoining inside surface of the centrifugal casing of the housing member 14.

In operation, the fluid or gas is drawn into the intake portion 25 of the first housing member 12 and flows into the flaring portion 29 of said housing member, being acted upon by the arcuate vanes 79 and the radial vane elements 88', whereby the gas or fluid flow is changed from a tangential direction to a more nearly axial direction at the point where the fluid or gas enters the intermediate housing member 13. As the fluid or gas passes between the bafiie vanes, such as the stationary baffle vane 87, the velocity of the fluid or gas is partially converted into static pressure and the flow is changed in direction so that the fluid or gas flows inwardly toward the axis of the shaft 31. As the fluid or gas discharges from between the stationary bafl le vanes 87, the fluid or gas passes into the flaring portion 82 of housing member 13 and is moved around the interior of housing portion 13 in a clockwise direction, as viewed in Figure 8, by the radial vanes 98, being discharged thence into the centrifugal casing portion of housing member 14 whereby the compressed fluid or gas is then discharged from the flaring end conduit portion 23 of the housing member 14 into the discharge conduit.

In the form of the invention described above the shaft 31 is driven. at a relatively high speed with respect to the speed of the input shaft 72, because of the gear ratio between the spur gear 71 and the pinion gear 70. As shown in Figure 3, the pinion gear 70 is relatively small as compared to the spur gear 71, whereby :a considerable increase in the speed of rotation of shaft 31 is provided with respect to the speed of rotation of the input shaft 72.

Referring now to the form of the invention illustrated in Figure 10, the rotor shaft, designated at 31 is driven directly, being provided at its outer end with an input shaft portion 72. The shaft 31' is provided with the intermediate portion 53' on which is secured the intermediate rotor 78, and with the adjacent shaft portion of smaller diameter on which the other rotors are secured, for example, with the portion 55' adjacent the intermediate shaft portion 53 upon which the impeller assembly 92 is secured. In the form of the invention shown in Figure 10, the third housing member, as shown at 14 has secured thereon the lubricant chamber 63 containing the bearing 64' in which the journal portion 32 of shaft 53" is rotatably mounted. A seal assembly 181' is engaged on the portion 102' of shaft 31' between the journal portion 32' and the wall 66' of housing member 14', said seal assembly comprising an inner seal ring 103 secured on shaft portion 102' and sealed with respect to the wall of the opening in housing portion 66' through which shaft portion 102' extends by a deformable sealing ring 104. An annular sealing member 105' is secured to the ring 103' and wedgingly engaged therewith is another ann'ular sealing member 106' of carbon, or similar sealing material,wedgingly engaged between the ring element 105' and the surface of shaft portion 102'. An annular washer 107' bears on the sealing ring 106' and is biased thereagainst by a plurality of coil springs 108 bearing between the annular end wall of a cylindrical casing 109 secured to ring element 105' and the annular washer 107 As shown in Figure 10, the cylindrical casing of the seal assembly 101' is fastened to the sealing ring segment 105 in any suitable manner, as by the fastening pins 110.

Lubricating oil under pressure is furnished to the lubricant housing 63' from the lubricant pump of the compressor in the same manner as in the previously described form of the invention, asby means of a lubricant intake conduit 111, the lubricant being returned to the pump reservoir by a lubricant return conduit 112 the drain conduit 69 from the lubricant accumulation space 68 being likewise connected through suitable condensate-removing means .to the lubricant return reservoir, as in the previously described form of the invention, whereby the pressures on the opposite sides of the seal assembly are substantially equalized.

While a specific embodiment of an improved multistage centrifugal compressor has been disclosed in the foregoing description, it will be understood that various modifications within the spirit of the invention may occur to those skilled in the art. Therefore, it is intended that no limitations be placed on the invention except as defined by the scope of the appended claims.

What is claimed is:

1. A multi-stage centrifugal fluid compressor comprising a housing having a substantially annular intake chamber, an annular flaring outlet portion communicating with said intake chamber at its smaller end, an annular intermediate chamber connected to the larger end of said outlet portion coaxially with said intake chamber, said intermediate chamber being reduced in diameter at its mid portion and defining an annular flaring outlet chamber, a spiral casing communicating with the larger end of said outlet chamber and increasing in cross sectional area circumferentially therearound, and an outlet conduit connected to the larger end of said spiral casing, a shaft journaled axially in said housing, a first impeller mounted on said shaft in said outlet portion of the intake chamber, said impeller having an annular external surface converging toward the wall of the larger end of said outlet por tion, arcuately curved vane on said first impeller extending substantially tangentially at the smaller end of said outlet portion and extending substantially in an axial direction at the larger end of said outlet portion, fixed baflie plates secured'in said intermediate chamber and extending in a substantially axial direction, a rotor on said shaft in said intermediate portion and having its periphery extending adjacent the inner edges of said baflie plates, said baffle plates being arcuately curved in a transverse vertical plane and being shaped so that their inner edges diverge toward the outlet chamber at relatively small angles with respect to radial longitudinal planes containing their innermost corners and in the direction of rotation of said rotor, said baffle plates being inclined inwardly in the direction of rotation of said rotor, a second impeller on said shaft in said outlet chamber, and radially extending vanes on said second impeller extending adjacent the wall surface of said outlet chamber.

2. In a multi-stage centrifugal fluid compressor, a housing having an annular intake chamber, an annular intermediate chamber tapering substantially in outside diameter along said portion toward said outlet chamben'a rotor element in said intermediate chamber coaxially connected to said first impeller and having an annular periphery formed to define with respect to the interior wall of the intermediate chamber an annular inwardly directed passage communicating with said intake chamber, whereby fluid discharged from said intake chamber is directed inwardly toward the axis of said rotor element and a portion of its velocity energy is converted into static pressure, stationary spaced bafile plates in said intermediate chamber extending adjacent said rotor element, said bafie plates being arcuately curved in a transverse vertical plane and being shaped so that their inner edges diverge toward the outlet chamber at relatively small angles with respect to radial longitudinal planes containing their innermost corners and in the direction of rotation of said rotor element, said baflfle plates being inclined inwardly in the direction of rotation of said rotor element, said rotor element being formed with spaced grooves adjacent the baflle plates defining ribs between the grooves, said grooves forming portions of conduit spaces defined between adjacent baffle plates, said baflle plates and grooves being formed and arranged to guide the fluid in a substantially axial direction through the intermediate chamber toward the outlet chamber, and a second impeller in the outlet chamber coaxially connected to said rotor element, said second impeller having substantially radial vanes formed and arranged to rotate the compressed fluid as it moves from said intermediate chamber into the outlet chamber and to cause said fluid to be further compressed in said outlet chamber.

References Cited in the file of this patent UNITED STATES PATENTS 986,827 Jackson Mar. 14, 1911 1,283,879 Ostenberg Nov. 5, 1918 1,460,428 Moody July 3, 1923 1,629,141 Benson May 17, 1927 2,245,114 Orleans June 10, 1941 2,273,420 Schott Feb. 17, 1942 2,384,265 Sollinger Sept. 4, 1945 2,399,852 Campbell et al May 7, 1946 2,405,284 Birmann Aug. 6, 1946 2,531,411 Davenport Nov. 28, 1950 2,623,357 Birmann Dec. 30, 1952 2,817,027 Ricozzi Dec. 19, 1957 2,819,012 Atkinson Jan. 7, 1958 FOREIGN PATENTS 114,335 Germany Oct. 18, 1900 148,162 Sweden Dec. 21, 1954 282,797 Great Britain Oct. 11, 1928 689,353 Great Britain Mar. 25, 1953 783,448 Great Britain Sept. 25, 1957 1,120,613 France Apr. 23, 1956

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