Pump

Feb. 21, 1967

W. E. COPELAND

PUMP

3,304,875

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Feb. 21, 1967

W, E. COPELAND

3,304,875

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M/E/VTOA&lt;S. Cops/arra'

Feb. 21, 1967

W. E. COPELAND

PUMP

3,304,875

Filed Feb. 23, 1965

Sheets-Sheet 3

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United States Patent Office

3,304,875

Patented Feb. 21, 1967

3,304,875 PUMP

Wayne E. Copeland, Los Angeles, Calif., assignor to Aetna

Chemical Corporation, Burbank, Calif., a corporation _ of California 5

Filed Feb. 23,1965, Ser. No. 434,450

Claims. (Cl. 103—87)

The present invention relates to electric motor-driven centrifugal pumps for use with highly corrosive fluids, and jq it relates more particularly to an improved electric motorpump combination of the above-mentioned type.

The pump to be described is of a molded plastic construction; the pump housing and impeller being formed, for example, of a polycarbonate plastic material. The 15 polycarbonate plastic marketed by the General Electric Company under the trade name “Lexan” is suitable for the purpose. Polycarbonate plastics are advantageous because they are easy to mold; and they are not susceptible to corrosive attack by acids, or the like. Moreover, 20 polycarbonate plastics are capable of operating at high temperatures of the order, for example, of 250° F.

. The pump housing in the embodiment of the invention to be described is made in two parts. These two parts are held together by a multiplicity of bolts, com- 25 posed, for example, of stainless steel. In a constructed embodiment of the invention, twenty-three such bolts were used to assure that there would be no leakage, and to prevent distortion of the plastic material at the higher operating temperatures. 30

As will be described, the pump itself is a centrifugal type, and it is mounted on the drive motor in an improved and simplified manner. The pump shaft is formed, for example, of titanium, and it is inserted into a counterbore in the motor shaft in axial alignment with the motor 35 shaft. The pump shaft is coupled to the motor shaft, for example, by appropriate pins.

The pump shaft extends into the pump housing and into the impeller of the pump. The end of the pump shaft is formed, for example, into a hexagon so as to 40 mate with a hexagon aperture at the 'center of the impeller. This particular coupling, instead of the usual threaded coupling of the prior art pumps, permits the pump accidentally to be driven in reverse without adversely affecting the mechanism due to any decoupling 45 tendencies.

A seal assembly is mounted in the pump housing in the embodiment to be described, and the seal assembly includes a stationary seal mounted on the pump housing and a rotating seal which rotates with the pump shaft and 50 which engages the stationary seal in a sealing relationship. The rotating seal in the embodiment to be described is spring loaded to perform its sealing function, and it is coupled to the impeller by means of axial pins so that it may rotate with the shaft. This particular 55 coupling of the rotating seal provides an inexpensive and practical assembly, without any need to clamp the rotating seal to the pump shaft by set screws, or the like, which is usually impractical due to the nature of the material of the pump shaft. 60

The features of the invention which are believed to be new are set forth with particularity in the claims. The objects and advantages of the invention, however, will become apparent from a consideration of the following description, when the description is taken in conjunction 65 with the drawings, in which:

FIGURE 1 is a perspective view of an improved pumpmotor combination constructed in accordance with the concepts of the invention;

_ FIGURE 2 is a side view of the pump-motor combina- 70 tion of FIGURE 1, and particularly illustrating the manner in which the pump is mounted on the motor;

FIGURE 3 is a fragmentary view, partly in section, and particularly illustrating the manner in which the pump shaft is coupled to the motor drive shaft, and also the manner in which the pump shaft is coupled to the impeller of the pump;

FIGURE 4 is a sectional view of the pump, taken substantially on the line 4—4 of FIGURE 2;

FIGURE 5 is a rear view of the pump, taken along the line 5—5 of FIGURE 4, and on a reduced scale with respect to FIGURE 4;

FIGURE 6 is a view of the pump impeller, taken substantially on the line 6—6 of FIGURE 4, and on a reduced scale with respect to FIGURE 4; and

FIGURE 7 is an exploded view of the pump illustrating its various components.

The pump-motor combination of the present invention, as shown, for example, in FIGURE 1, includes an electric motor 10 which is mounted on an appropriate pedestal 12. The combination also includes a centrifugal pump 14 which is mounted on the motor 10 in a manner to be described.

The pump 14 includes a pump housing which, in turn, comprises a front section 16 and a rear section 18. These sections cooperate to form a pump housing having an essentially cylindrical configuration, as shown.

The pump housing may be formed, for example, of a polycarbonate plastic. For example, as mentioned above, the polycarbonate plastic marketed by the General Electric Company under the trade name “Lexan” has proven to be satisfactory. The two pump housing sections 16 and 18 are held together by a plurality of bolts and screws designated 20. These bolts and screws extend axially through the sections adjacent the periphery thereof, and may be formed of stainless steel. In a constructed embodiment of the invention, for example, twenty-three such bolts were used to hold the two sections 16 and 18 together.

As best shown in FIGURE 7, the pump housing section 16 has an annular taper 22 formed in its inner face, and this taper extends around the section 16 adjacent its periphery. The pump section 18, on the other hand, has an annular groove or channel 24 extending around its inner face adjacent the taper 22.

An O-ring 26 (FIGURE 4) is mounted in the groove 24, and this O-ring is distorted by the taper 22 into sealing relationship when the two housing sections 16 and 18 are bolted together by the bolts 20. The resulting assembly forms an effectively sealed housing for the corrosive fluid which is pumped by the pump.

The section 16 has an inlet port 28 formed in its central portion, and this inlet port receives a suitable pipeline, or the like, which feeds the corrosive fluid to the pump. The section 18, on the other hand, has an outlet port 30 through which the corrosive fluid under pressure is discharged. This latter port may be coupled, likewise, to an appropriate pipeline.

As shown in FIGURE 2, the pump housing section 18 has a plurality of protuberances 32 formed on its rear face. These protuberances support a metal mounting ring 34. The mounting ring 34 is attached to the ends of the protuberances by counter sunk screws 35, for example, which are threaded into the protuberances. The mounting ring 34, in turn, is mounted to the casing of the motor 10 by means, for example, of appropriate bolts 36 which are threaded into the casing.

As best shown in FIGURE 3, the motor 10 includes a drive shaft 40 supported, for example, in a bearing 42.

The drive shaft 40 is counterbored to receive a pump shaft 44. The pump shaft 44 extends into the drive shaft 40 in axial alignment therewith. The pump shaft is composed, for example, of titanium, or other material which is not susceptible to corrosive attack by the

3,304,875 fluids handled by the pump. The pump shaft is affixed to the drive shaft 40 by means, for example, of a pair of mutually perpendicular pins 46 and 48 which extend through the two shafts.

A pump impeller 50 is mounted to the end of the pump shaft 44 remote from the drive shaft 40. The impeller is disposed within the pump 14. The remote end of the pump shaft 44 is formed into a hexagon, for example, so as to mate with a hexagon aperture at the center of the impeller 50. The impeller is held on the pump shaft 40 by means, for example, of a titanium screw 52 and a titanium washer 54. The particular illustrated coupling of the pump shaft 44 to the impeller 50 permits the motor accidentally to be driven in reverse, without any tendency for the pump shaft to be decoupled from the impeller, with resulting damage to the assembly.

The impeller 50, like the pump housing 14, may be formed of a polycarbonate plastic, such as “Lexan.” The impeller, as best shown in FIGURES 4 and 6, is provided with appropriate vanes 52 so that, when the impeller is rotated, it causes the corrosive fluid to be drawn in through the inlet port 28, and by centrifugal action, causes the fluid to be discharged under pressure from the outlet port 30. A plurality of radial vanes 54 are formed on the rear face of the impeller 50. These latter vanes function to drive the corrosive fluid away from the central portion of the impeller, where a seal combination is provided between the shaft and the pump housing 16, as will be described.

The aforesaid seal combination is designated generally as 80. The combination includes a rotating seal which is rotatably supported on the pump shaft 44 in the pump housing 14. Since the titanium shaft is not susceptible to receiving set screws, or the like, the rotating seal may be conveniently coupled to the impeller 50 by a pair of axialty extending pins 82. This permits the rotating seal to rotate with the impeller 50 and with the pump shaft 44.

The rotating seal includes a housing 84 which may be formed, for example, of titanium or a polycarbonate plastic. A plurality of springs, such as the spring 86, are encased within the housing 84. These springs may be formed, for example, of a metal marketed by the Elgin Watch Company and designated by the trade name “Elgiloy.” This metal exhibits resilient characteristics, and is not suspectible to corrosive attack by the fluids handled by the pump.

An annular member 88 is also supported within the housing 84, and this annular member may also be composed of “Elgiloy.” The annular member 88 bears against a further annular member 90 which has a wedge shaped configuration, and which may be composed of Teflon. The member 88 is retained in the housing by means, for example, of a snap ring 92. The wedge shaped annular member 90 bears against a bearing member 94 which may be composed of carbon.

A further bearing member (which may also be composed of carbon) is supported in a stationary manner in the section 18, this latter member being designated 96. The stationary bearing member is supported in a groove in the section 18 by means, for example, of a rubber boot 88. The rotating bearing member 94 is biased against the bearing member 96 and rotates about the latter bearing member as the rotating bearing assembly 80 is rotated.

The above described seal combination 80 provides an adequate and efficient seal for the pump assembly, and one which is not susceptible to attack by the corrosive fluid.

The invention provides, therefore, an improved pumpdrive motor combination for handling corrosive fluids. The pump of the present invention can be constructed on a relatively economical basis, and can be sold for a relatively low price. The pump has been found to per form with a high degree of satisfaction, and to operate satisfactorily in handling highly corrosive fluids.

While a particular embodiment of the invention has been shown and described, modifications may be made. It is intended in the claims to cover all such modifications which fall within the scope of the invention.