US3238881A - Pumps - Google Patents

Description

March 8, 1966 G. CAMAC 3,238,881

PUMPS Filed March 26, 1964 :s Sheets-Sheet 1 3,238,881 PUMPS George Camac, Weston-super-Mare, England, assignor to Speedwell Research Limited, Birmingham, England, a British company Filed Mar. 26, 1964, Ser. No. 354,834 Claims priority, application Great Britain, Feb. 27, 1964, 8,186/64 6 Claims. (Cl. 1031tl3) This invention relates to pumps. The invention has been developed in connection with centrifugal pumps of the kind comprising a pump casing within which is disposed an open impeller which when rotated establishes flow of liquid within the pump casing from an inlet situated at or near the axis of rotation of the impeller towards an outlet spaced radially from the inlet and usually disposed at or near the periphery of the casing. Although developed in connection with such pumps, the invention is not limited thereto.

There is an increasing demand for pumps Whose parts exposed to the liquid flow are made of corrosion resistant material such as titanium. Various proposals have been made for providing a pump casing of titanium which is supported externally by supporting members which may, for example, be made of mild steel. In such pumps, the parts exposed to the liquid flow can be made from cornparatively thin titanium sheet which will withstand the fluid loads and the mechanical loads can be taken by the mild steel supporting members.

It is an object of the present invention to provide a pump whose casing is made of corrosion-resistant material and is supported by external supporting members of material which does not resist corrosion.

The nature of the corrosion-resistant material will depend upon the nature of the liquid being pumped but titanium is a useful example of such material. Similarly, the material for the supporting members will depend on the service for which the pump is intended but in many applications mild steel is satisfactory for this purpose.

Several embodiments of the invention will now be described in detail by way of example with reference to the accompanying drawings, in which:

FIGURE 1 is a vertical section through a centrifugal pump constituting a first embodiment of the invention;

FIGURE 2 is a vertical section on the pump of FIG- URE 1 on the line II-II of that figure;

FIGURE 3 is a plan view of the assembly comprising the clamping ring, front supporting member and circumscribing wall of the pump of FIGURES l and 2;

FIGURE 4 is a detail section showing an alternative way of mounting the pump inlet in the front supporting member of a second embodiment of the invention;

FIGURE 5 is a side elevation of a centrifugal pump constituting a third embodiment of the invention; and

FIGURE 6 is a vertical section through a centrifugal pump constituting a fourth embodiment of the invention.

Referring to FIGURES 1 to 3, the pump which is to be described is a centrifugal pump having a central inlet on the rotary axis of the impeller and a casing having a circular cross section with a tangential outlet. An impeller fixed to the end of an impeller shaft rotates within the casing to accelerate liquid from the inlet to the outlet. The pump which will be described has supporting members of mild steel and easing parts made of titanium.

The pump conmprises a generally circular back plate or supporting member 10 made of mild steel with a central aperture 11 therein. Lying against the inner face of the back plate, i.e., the face exposed to the interior of the pump casing, is a disc 12 of titanium. The disc has a central spigot 13 extending perpendicularly from the 3,238,881 Patented Mar. 8, 1966 ion plane of the disc 12 and received with clearance in the aperture 11 in the back plate. The spigot is made of titanium and is welded to the disc 12 at 14 and is externally threaded. The spigot is threadedly engaged by a stainless steel flanged collar 15 which is internally threaded to mate with the external threads of the spigot. The collar comprises a shank 16 whose internal surface is internally threaded and whose external surface engages the wall of the aperture in the back plate, and a flange 17 which overlies part of the outer surface of the back plate 10 so that when the collar and the spigot are tightened, the back plate 10 is gripped between the disc 12 and the flange 17 of the collar 15 and the disc of titanium is held tightly against the inner face of the back plate.

The front part 18 of the pump casing comprises a spinning of titanium. This spinning comprises a generally cylindrical portion 19 having at one end a peripheral flange 20 extending generally normal to the axis of revolution of the circular wall. At the other end of the circular wall there is a generally frusto-conical front wall 21 which at its centre merges into a hollow cylindrical extension 22 which forms the inlet to the pump. Extending tangentially from the circular wall 13 is a pipe 23 (see FIGURE 2) which constitutes the pump outlet.

The peripheral flange 20 is of the same diameter as the disc 12 of titanium and the flange 20 and the marginal portion 24 of the titanium disc are drilled with six equiangularly spaced holes which, when the pump is assembled, are aligned with six tapped holes 25 in the back plate. A clamping ring 26 overlies the peripheral flange 20 and is also provided with six similar holes and the pump is assembled by passing six threaded pins 27 through the holes and engaging them in the tapped holes 25. The clamping 26 ring has a peripheral rim 28 which embraces the peripheries of the titanium disc 12 and the marginal flange 20' and abuts against the inner surface of the back plate. A rubber gasket 29 is inserted between the peripheral fiange 20 and the marginal portion 24 of the disc and the abutment of the rim of the clamping ring with the back plate prevents over-compression of the rubber gasket.

The front part 18 of the pump is circumscribed by a mild steel, cylindrical protective wall 30. The wall is dimensioned to fit at one end within the central aperture of the clamping ring and is welded to the clamping ring at that end at 3-1. At the other end, the circnmscribing Wall embraces an annular disc 32 of mild steel and is welded thereto at 33. The central extension 22 of the front part which forms the inlet to the pump passes through the central aperture 34 in the annular plate and has, externally of the plate, a titanium flange 35 welded thereto at 36.

Referring now to FIGURES 2 and 3, the outlet pipe 23 is received in a U-shaped slot 37 in the circumscribing wall 30, the clamping ring being cut away at 38 to give entry to the slot. A U-shaped channel 39 of mild steel is welded to the exterior of the circumscribing wall 30 to extend tangentially thereof. The U-shaped channel 39 is of a length corresponding to that of the outlet pipe 23 so that when the front part 18 of the casing is assembled within the housing constituted by the clamping ring 26, the circumscribing wall 30 and the front supporting member 32, the outlet pipe 23 is received within the U-shaped channel 39 as shown in FIGURE 2. At its outer end, the U-shaped channel 39 is provided with a mild steel flange 40 which is welded thereto at 41 and the outlet pipe 23 passes through a central aperture 42 in the flange and has, at the outer surface of the flange 40, a flange 43 of titanium welded thereto.

During manufacture, the front part 118 of the casing is assembled into the abovementioned housing before the titanium flanges and 43 are welded to the ends of the inlet 22 and outlet 23. In one manufacturing sequence, the mild steel flange 46 can be welded to the end of the U-shaped channel 39 on the housing prior to assembly of the casing part 18 into the housing and the outlet pipe 23 can be passed through the central aperture 42 of the flange and the casing part then swung into position so that the inlet 22 will become aligned with and pass through the central aperture in the front supporting member 32. The outlet pipe 23 and the inlet 22 may then be trimmed to size and the titanium flanges 35 and 43 welded in position to overlie the flange at the end of the U-shaped channel and the front supporting member 35 respectively. In an alternative sequence of construction, the front casing part 18 can be assembled into the housing before the flange 40 is welded to the top of the U-shaped channel 39. After assembly, the flange 40 can be dropped over the outlet pipe 23 and then welded at 41 to the U-shaped channel 39. The titanium flanges 35 and 43 are then welded in position as before.

The front casing part 18 and the disc 12 secured to the back plate 10 together define a chamber 44 in which rotates an impeller to accelerate liquid flowing into the inlet 22 and to discharge it through the outlet 23. The back plate '10 ie secured to the flange 45 of an electric motor and by means of a short tube 46 welded to the back plate at 47 and a ring 48 flange welded at 49 to the other end of the tube 46 extension and adapted to be bolted by bolts (not shown) to the flange 45 of the motor. The tube 46 has ventilation 50 to give clearance to such bolts.

A titanium shaft 51 passes with clearance through the apertured spigot 13. At one end, the titanium shaft 5 1 is counterbored and receives the shaft 52 of the electric motor in the counterbore, the shaft 51 and 52 being pinned together by two pins 53. The pump shaft 51 has a portion 54 of reduced diameter extending into the chamber 44 and a sloping shoulder 55 between the portion 54 and the part 56 which receives the shaft 52. The sloping shoulder acts as a thrower to prevent any liquid escaping from the chamber through the gland (to be described hereunder) from entering the motor. Any liquid which does pass the gland drains through a drain opening 56a.

The motor shaft 51 is sealed to the back plate 10 and disc 12 by means of a gland. The gland comprises a flanged ceramic collar 57, secured in a rebate 58 in the spigot 13 by a rubber ring 59, and a graphite ring 60 having a seal face 61 which runs on a seal face 62 provided by the flange 63 of the ceramic ring. The graphite ring 60 is carried by the portion 54 of the pump shaft within the pump chamber 44 and the arrangement is such that the outer peripheral edges of the seal faces 61 and 62 are exposed to the liquid being pumped through the chamber.

The graphite ring is provided with a recess in which is mounted a rubber member 64 of generally U-shaped cross section which contains a spring 65 serving to force one limb of the U against the inner wall of the recess in the graphite ring and to force the other limb of the U against the external surface of the shaft. The base of the U of the rubber member is aligned substantially with a shoulder 66 on the free end of the portion 54.

The shoulder is formed between the circular portion 54 on the shaft and a square 67 at the end of the shaft.

The square 67 leads into a threaded circular portion 68 which is adapted to receive two titanium nuts 69 and a titanium tab washer 70 and the square is adapted to receive an impeller 71 which is located in position by the nut and washer.

The impeller is of the form substantially described in my co-pending application Serial No. 354,883 filed April 26, 1964. The impeller is formed from sheet titanium and has two parallel blades 72 joined by a planar portion 73 one surface of which provides a seating face 74 for seating against the shoulder 66 at the end of the pump shaft.

4. The planar portion has a square aperture to mate with the square 67 and the impeller includes a boss 75 welded to the planar portion 74 and having a square section aperture aligned with the aperture in the planar portion and which receives the square 67 on the shaft.

Each blade 72 projects in two opposite directions from the plane of the seating face as shown in FIGURE 1. The extension of each blade towards the inlet 22 provides a front portion 76 of the blade and the extension of the blade from the plane of the seating face towards the disc 12 provides a rear portion 77 of the blade, the blades are parallel and lie in planes normal to the planes of the seating face. Moreover, the chamfered inner edges 78 of the front portions of the blades lie on a diametral plane 79 of the impeller shaft and the blades are perpendicular to this plane.

The inner edges 80 of the rear portions of the blades, i.e., the edges nearest to the impeller shaft, lie on a circle which is of greater diameter than the gland and the rear portions of the blades sweep out a path around the gland. Considered axially of the pump, the rear portions of the blades extend from the plane of the seating face when the impeller is secured to the shaft to a position adjacent to the titanium disc 12 secured to the back plate of the pump and the front portions of the blades extend from the plane of the seating face to a position adjacent to the front wall 21 of the casing.

The perpendicular spacing between the blades is such that it is somewhat greater than the diameter of the inlet 22.

Viewed in a direction parallel to the lengths of the blades, the impeller is generally of H-section. The bar of the H being the planar portion 74 and the uprights of the H being the blades 72.

The operation of the pump is substantially self evident from the foregoing description, liquid enters the inlet 22 of the pump and into the eye of the impeller 71. As the liquid starts to flow outwardly, it is accelerated by the blades and is discharged through the outlet 23. All those parts of the pump in contact with the liquid, i.e., the front casing part 18, the disc 12 secured to the back plate 10, the impeller 71, the shaft 51 and the securing nuts 69 and washer 70 for the impeller are of titanium. All the parts are made of sheet titanium with the exception of the shaft and the nuts so that the amount of titanium used is maintained at a minimum. However, the mechanical loads are taken by the mild steel supporting members 10, 32 and the circumscribing wall 30. Moreover, the wall 30 protects the casing part 18.

In an alternative arrangement shown in FIGURE 4, the central extension 81 of the front part of the casing 82 is externally threaded at 83 and projects a considerable distance through a front supporting member 84. The latter has a central aperture 85 of diameter greater than the extension 31 forming the inlet and the latter is threadedly engaged by a flanged collar 86, the shank 87 of which is received in the aperture 85 and the flange 88 of which engages the outer surface of the front supporting member 84. By this means, the front part of the casing is positively centered and supported in the front supporting member 84 in a removable manner and the part 89 of the threaded extension outwardly of the flanged collar 86 is available for connection to an internally threaded pipe.

FIGURE 5 shows a pump which is similar in all respects to the pump of FIGURES 1 to 3 except that the circumscribing wall 30 of the latter is omitted as is the U-shaped channel 39 which embraced and protected the outlet pipe. In FIGURE 5 the front mild steel member 90 is loosely mounted on an elongated extension 91 of the front casing part 92. Similarly, the outlet flange 93 is loosely mounted on the end of the outlet pipe 94.

In a further construction shown in FIGURE 6, the pump casing is made somewhat differently although the impeller, and gland arrangements are the same. In this embodiment, the pump back plate 90 is of substantially disc like form and has a peripheral flange 91 lying in the general plane of the back plate but having a thickness less than the remainder of the back plate. The back plate has a central aperture 92 and is made of mild steel. A titanium disc 93 is secured against the inner face of the back plate by means of a spigot and stainless steel flanged collar 95 in a manner similar to that described above. At its periphery, the titanium disc is provided with a first peripheral flange 96 which extends generally perpendicular to the plane of the disc and a second peripheral flange 97 which is parallel to the plane of the disc. The flanges respectively overlie walls 98 and 99 of a step provided around the periphery on the back plate by the flange 91.

The front casing part 100 of the pump comprises a dished member having a cylinder wall 101 which leads by a frusto-conical wall 102 at its front end into a cylindrical extension 103 forming the inlet of the pump. At its rear end, the front casing part 100 is provided with a frusto-conical extension 104 which leads into a short cylindrical part 105. The frusto-conical extension 104 is arranged to overlie the step around the periphery of the disc 90 when the pump casing is assembled and a rubber gasket 106 placed on the step is compressed between the frusto-conical extension 105 and the peripheral flanges 96 and 97. The front casing part 100 is held in position by three thumb screws 107 which engage the outer surface of the frusto-conical extension 104 and are threadedly received in three lugs 108 formed integrally with the back plate and equiangularly spaced around the periphery thereof.

The front portion 100 of the pump casing, the disc 93 and the impeller 109 are all made of titanium so that those parts of the casing which are in contact with the liquid are made of titanium although only sheet titanium is required. The impeller is mounted on a titanium shaft 110 which is provided at its rear end with a titanium disc 111 forming a thrower. The shaft 110 is pinned to the shaft 112 of an electric motor 113. The gland 114 and the method of fixing the impeller 109 on the shaft 110 are the same as in the pump shown in FIGURES 1 to 3.

Operation of the pump of FIGURE 6 is similar to the operation of the pump previously described with reference to FIGURES 1 to 3.

It will be seen that the invention provides means for locating resistant pump parts relative to non-resistant supporting members in an advantageous and simple manner. Moreover, the invention provides pump constructions in which the casing is made from a minimum quantity of titanium or similar resistant metal and is supported in an advantageous manner by mild steel or other non-resistant material.

What I claim is:

1. A pump having a casing which includes a generally flat back supporting member, a flat disc of corrosionresistant sheet metal lying against the inner face of the member, an externally threaded spigot on disc received in an aperture in the supporting member and in internally threaded flanged collar supporting and engaging the spigot, the flange of the collar engaging the outer face of 6 the member so that tightening of the collar on the spigot forces the disc tightly against said one face of the member,

the pump casing also including a front dished member of corrosion-resistant material and having a peripheral flange parallel to the disc, a gasket inserted between the flange and the marginal portion of the disc, a clamping ring having a peripheral ring which embraces the flange and the outer periphery of the disc and abuts the back supporting member to limit the clamping pressure applied to said flange and marginal portion, releasable means securing the clamping ring to the disc and a protective wall circumscribing said front dished member and secured at one end of the clamping ring.

2. A pump according to claim 1, wherein the front dished member has a hollow, central extension which constitutes the pump inlet, the pump including a front supporting member having an aperture therein through which the hollow extension passes and being supported from the other end of said circumscribing wall.

3. A pump according to claim 2 including a pipe of corrosion-resistant material extending tangentially from the front dished member to provide a pump outlet and passing through a U-shaped slot in the circumscribing wall, a U-shaped channel extending outwardly of the circumscribing wall and partially surrounding the pipe and a flange secured to the outer end of the U-shaped channel and having a central aperture through which the pipe passes.

4. A pump having a casing which includes a generally flat back member, a front dished member of corrosionresistant material having a peripheral flange and secured to the back member around the periphery thereof so that the members define a hollow chamber, a clamping ring overlying the peripheral flange of the dished member, means securing the ring, the flange and the back member together, a protective wall circumscribing the front dished member and secured at one end of the clamping ring, a front supporting member supported at the other end of the circumscribing wall, and a hollow central extension of the front dished member which provides a pump inlet, the extension passing through an aperture in the front supporting member.

5. A pump according to claim 4, wherein the extension has a flange secured thereto at the end thereof adjacent the outer surface of the front supporting member.

6. A pump according to claim 4, including a pipe of corrosion-resistant material extending tangentially from the front dished member to provide a pump outlet and passing through a U-shaped slot in the circumscribing wall, a U-shaped channel extending outwardly of the circumscribing wall and partially surrounding the pipe and a flange secured to the outer end of the U-shaped channel and having a central aperture through which the pipe passes.

References Cited by the Examiner UNITED STATES PATENTS 2,291,797 7/1942 Dalzell 103-111 2,963,978 12/1960 Namur 103-111 3,155,045 11/1964 Lown l03114 FOREIGN PATENTS 177,661 2/ 1954 Austria. 1,092,549 11/1954 France. 520,558 3/1955 Italy.

SAMUEL LEVINE, Primary Examiner.

HENRY F. RADUAZO, Examiner.

Claims (1)

1. A PUMP HAVING A CASING WHICH INCLUDES A GENERALLY FLAT BACK SUPPORTING MEMBER, A FLAT DISC OF CORROSIONRESISTANT SHEET METAL LYING AGAINST THE INNER FACE OF THE MEMBER, AN EXTERNALLY THREADED SPIGOT ON DISC RECEIVED IN AN APERTURE IN THE SUPPORTING MEMBER AND IN INTERNALLY THREADED FLANGED COLLAR SUPPORTING AND ENGAGING THE SPIGOT, THE FLANGE OF THE COLLAR ENGAGING THE OUTER FACE OF THE MEMBER SO THAT TIGHTENING OF THE COLLAR ON THE SPIGOT FORCES THE DISC TIGHTLY AGAINST SAID ONE FACE OF THE MEMBER, THE PUMP CASING ALSO INCLUDING A FRONT DISHED MEMBER OF CORROSION-RESISTANT MATERIAL AND HAVING A PERIPHERAL FLANGE PARALLEL TO THE DISC, A GASKET INSERTED BETWEEN THE FLANGE AND THE MARGINAL PORTION OF THE DISC, A CLAMPING RING HAVING A PERIPHERAL RING WHICH EMBRACES THE FLANGE AND THE OUTER PERIPHERY OF THE DISC AND ABUTS THE BACK SUPPORTING MEMBER TO LIMIT THE CLAMPING PRESSURE APPLIED TO SAID FLANGE AND MARGINAL PORTION, RELEASABLE MEANS SECURING THE CLAMPING RING TO THE DISC AND A PROTECTIVE WALL CIRCUMSCRIBING SAID FRONT DISHED MEMBER AND SECURED AT ONE END OF THE CLAMPING RING.

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