US2975715A - Crash truck pumps - Google Patents

Description

D. F. THOMAS El AL 2,975,715

March 21, 1961 CRASH TRUCK PUMPS 5 Sheets-Sheet 1 Filed March 24, 1958 .Lllllll March 21, 1961 D. F. THOMAS EI'AL 2,975,715

CRASH TRUCK PUMPS 3 Sheets-Sheet 2 Filed March 24, 1958 INVENTOR 0a r/a F Thomas lay/s 5. [rd/7s March 21, 1961 D. F. THOMAS EI'AL 2,975,715

CRASH TRUCK PUMPS 3 Sheets-Sheet 3 Filed March 24, l958 BY Qom.a

CRASH TRUCK PUMPS DrividEThomas, St. Paul, and Louis B. Evans, Hastings, Minn., assignors to Waterous Company, St. Paul, Minn, a corporation of Minnesota Filed Mar. 24, 1958, Ser. No. 723,363 7 Claims. or. 103-408) vision of a novel means of mounting impellers on an impeller shaft in a two stage pump. In pumps of this type it is usual practice to have the impeller inlet of both impellers outwardly of the impellers, so that the position of one impeller is reversed relative to the other. As a result, the two impellers are of diflerent construction. In the present pump, the inlet to each impeller is on the same side of the impeller so that both impellers can be of identical form.

A feature of the present invention resides in the provision of a two stage pump having two identical impellers and in which the second stage impeller runs within two wear rings on opposite sides of the impeller while the first stage impeller runswithin a single Wear ring at the inlet side of the impeller. This arrangement is of advantage as it permits the discharge pressure of the first impeller to be communicated to the side of this first stage impeller opposite the inlet side thereof. This pressure exerts a force against the first stage impeller urging it toward the center of the shaft. This same'first stag'edischarge pressure is exerted against the inlet side of thesecond stage impeller creating a force tending to urge this second stage impeller toward the center of the pump. Thus, the pressure against the two impellers is balanced and the thrust against the supportingshaft is equalized.

A feature of the present invention resides in the provision of an impeller arrangement of the type described in which the impellers are spaced by shoulders upon the suporting shaft which may be formed merely by providing an enlarged diameter shaft portion between the two impellers. As the pressure acting upon both impellers tends to urge the impellers toward the center of the pump or against the large diameter shaft portion, no additional fastening means is required for holding the impellers from axial movement on the supporting shaft.

A further advantage of this type of construction resides in the fact that the first stage discharge pressure is imposed directly on both of the stuffing boxes which are located outwardly of the impellers. This arrangement maintains the stutiin'g boxes cool and lubricated and avoids the necessity of providing lantern rings and water lines to the stuffing boxes as is usually necessary in pumps of this type where enact the stulfing boxes is subjected to partial vacuum.

A further'feature of the present invention resides in the provision of a pump ofthe type described including a ates Patent 7 2,975,715 Patented Mar. 21, 1961 These and other objects and novel features of the present invention will be more clearlyand fully set forth in the following specification and claims:

In the drawings forming a part of the specification:

Figure 1 is a top plan view of the crash truck pump showing the general arrangement of parts therein.

Figure 2 is a side elevational view of the pump illustrated in Figure 1.

- including an open ended housing 10 having an attachment flange 11 at the open end designed to accommodate the fly wheel 12 of an internal combustion engine, not

illustrated in the drawings, and having a drive shaft 13.

The housing 10 incldues a partition 14 in spaced parallel relation to the flange 11 which supports a removable mounting plate 15 which acts to normallyclose an aperture 16' in the partition 14. The mounting plate 15 supports a bearing 17 encircling a pump drive shaft 19 provided with a splined end 20 which is engaged in a cooperatively splined socket 21 in the end of the fly Wheel 1 12 and coaxial with the engine shaft 13.

The casing 10 is provided with a closed side 22 having an opening 23 therein axially aligned with the shaft 19. A cup shaped bearing support 24 is attached to the closed end 22 to extend through the opening 23 and the bearing support 24 acts to support a bearing 25 providing a further support for the shaft 19. A tachometer drive gear 26 is mounted on the shaft 19 in the bearing support 24 and drives a worm 27 connected to a tachometer to drive the same.

A chain sprocket 29 is intermediate the bearings 17 and 25. A chain 30 connects the chain sprocket 29 with a cooperable chain sprocket 31 mounted upon the impeller-shaft 32 which is parallel to the shaft 19. A bearing 33 is mounted in the partition wall 14 in a suitable recess therein. The housing wall 22 is provided with a second aperture 34 in axially aligned relation to the bearing 33 and a bearing support 35 is mounted in the recess 34 to support a bearing 36. The bearings 33 and 36 suport an end of the impeller shaft 32 and support the chain sprocket 31 which is keyed or otherwise secured thereto.

A pump mounting plate 37 is secured to the housing wall 22 by suitable means and the mounting plate 37 is connected to the pump housing 39 by suitable connecting webs such as 40. The pump housing 39 is also partially supported by a brace 41 which extends generally parallel to'the impeller shaft 32 and acts to connect the chain drive housing 10 to the pump housing 39. The housing 39 is horizontally split as indicated at 38 (Figure 2) and the two sections bolted or otherwise secured together.

The pump housing 39 is provided with an inlet or suction passage 42 leading to the intake of the first stage. A suction extension fitting 43 is bolted or otherwise secured to the under surface of the housing 39 providing an extension of the suction pasage. A flange 44 is provided at the lower end of the extension 43 for connection with the suction line. The mounting flange 45 at the upper end of the suction extension is secured in surface contact with the undersurface of the pump housing 39 and acts to close certain water passages as will be later de scribed more in detail.

mounted upon the shaft 19 The suction passage 42 communicates with the ring shaped suction chamber 46 which in turn is in communication with the inlet end 47 of the first stage impeller 49. The impeller 49 is mounted upon the impeller shaft 32 and rotates in unison therewith. A partition wall 50 separates the suction chamber 46 from the impeller chamber 51 and a wear ring 52 is mounted within the partition 50. acting to form a running seal with the cylindrical outer portion 53 of the impeller 49. A cylindrical flange 54 is provided on the side of the impeller 49 opposite the inlet side thereof but this flange 54 is free of contact with the housing wall 55. A volute 56 encircles the impeller 49 and is subject to discharge pressure from the impeller 49. As the volute is in communication with the pressure chamber 58 between the impeller 49 and the housing wall 55, the side of the impeller opposite the inlet side is subject to the discharge pressure of the impeller 49.

The impeller shaft 32 is provided with an enlarged diameter central portion 57 which is of somewhat larger diameter than the shaft portion 59 on which the impeller 49 is mounted. As a result, a shoulder 60 is provided between the shaft portions 57 and 59 against which the impeller 49 may abut. As the outer side of the impeller 49 is subject to discharge pressure while the opposite side of this impeller is subject only to partial vacuum a force is created holding the impeller 49 against the shoulder 60, eliminating the need of other fastening means for holding the impeller from axial movement upon the shaft 32.

A manifold 61, a portion of which is illustrated in Figure 4 of the drawings, acts to connect the discharge from the volute 56 to the intake chamber 62 of the second stage of the pump. A second stage impeller 63 is mounted upon the impeller shaft 32 for rotation in unison therewith and has an inlet portion defined within a cylindrical sleeve 64 which runs within a wear ring 65 supported by a partition wall 66 dividing the inlet chamber 62 from the impeller chamber 67. As the inlet chamber 62 is subject to the discharge pressure of the first stage, a force is created against the outer or inlet side of the impeller 63 urging this impeller against the shoulder 69 provided between the enlarged diameter portion 57 of the shaft 32 and the smaller diameter portion 70 thereof upon which the impeller 63 is mounted.

The impeller chamber 67 extends on both sides of the impeller 63 and a wall of the housing is provided with a circular flange 71 which encircles a circular flange 72 on the impeller 63. A wear ring 73 is supported by the flange 71 to provide a running seal with the flange 72 so that the area on opposite sides of the impeller 63 which is subject to the discharge pressure of the second stage is substantially balanced. As a result, the pressure of the discharge from the first stage exerts the same inward force against the impeller 63 as the first stage discharge pressure creates against the outer surface of the impeller 49 thus substantially equalizing the forces on opposite sides of the pump or acting against the impeller shaft 32. As will also be noted, the wall defining the suction chamber 46 is spaced from the shaft 57 as indicated at 74, providing an annular area large enough to permit essentially free flow of fluid to the suction chamber 46. A chamber 68 is formed inwardly of the wear ring 73 which is sealed by the wear ring from the discharge pressure in the impeller chamber 67, and which is subject to first stage suction. Thus, the inner opposed sides of both impellers are subject to first stage suction while the outer sides of 'both impellers are subject to first stage discharge pressure.

A sealing ring compartment 75 is provided upon the wall 55 of the housing 39 and accommodates a series of sealing rings 76 encircling the shaft 32 and held in place by the packing gland 77. A sealing ring chamber'79 is also provided in the end of the housing 39 opposite .4 the chamber and accommodates sealing rings 78 which are held in place by a packing member 81.

This arrangement is of advantage as the inner ends of the sealing ring chambers are both subject to first stage impeller discharge pressure. As a result, a certain amount of fluid is forced along the shaft 32 and into the sealing ring chamber at each end of the pump, maintaining the seals at a relatively low temperature and providing a lubricant for the packing. This arrangement is of advantage as otherwise, lantern rings or seal cages are often provided in the sealing ring chamber and water is applied to the sealing ring chamber through suitable conduits connected with the discharge pressure of one or both impellers.

As may be noted in Figure 4 of the drawings and as will be even more clearly seen in Figure 5 of the draw ings, the housing 39 includes heating water circulation areas 80 in the bottom portion of the pump housing 39, the undersurfaces of which are normally closed by the flange 45 forming a part of the suction extension 43. A cooling water chamber 81 is also preferably provided beneath the chain drive housing 10 and through which the heating water may flow. A partition wall 82 divides the chamber 81 into two compartments connected by a passage 83 at one end of the partition 82. As shown in Figure 4 of the drawings, the lower end of the chain drive case is open, and is provided with an outwardly turned peripheral flange 95. A plate 97 closes the lower open end of the chain case. The cooling water chamber 81 is provided with an open upper end and has a pcripheral flange 96. The plate 97 is bolted or otherwise secured between the flanges 95 and 96, forming a separating wall between the interior of the chain case and the interior of the water chamber. The partition 82 extends upwardly from the bottom of the water chamber 81 into contact with the plate 97.

Heating water for heating the chain drive case and the lower portion of the pump housing may be circulated by means of a suitable pump and source of heated fluid supply through apertures 84 and 85 which are shown in Figure 5 to be closed by plugs 86 and 87 respectively. One of the passages 84 or 85 forms a heated liquid inlet while the other forms a heated liquid outlet. The heating chamber 80 at the base of the pump housing 39 is connected to the heating chamber 81 in the chain drive housing 10 by meaans of a tubular conduit or pipe 88.

In order to complete the support of the impeller shaft 32, the end of the pump housing is provided with an end plate 90 connected to the remainder of the housing by ribs 91 or other suitable means. The plate 98 is provided with an aperture 91 therein designed to accommodate the bearing support 92 which supports the bearing 93 encircling the end of the impeller shaft 32. A cap 94 is mounted to the bearing support 92 to enclose the end of the shaft.

In accordance with the patent statutes, we have described the principles of construction and operation of our improvement in crash truck pumps, and while we have endeavored to set forth the best embodiment thereof,

.we desire to have it understood that changes may be made within the scope of the following claims without departing from the spirit of our invention.

We claim:

1. In a centrifugal pump, a pump housing, an impeller shaft supported in said housing, a pair of axially spaced impellers on said shaft, said housing including volutes encircling said impellers, said housing including an axially extending inlet passage on one side of each impeller, said impellers being arranged with the inlet passages facing the same end of said impeller shaft, said housing including an inlet conduit terminating between said impellers in communication with the inlet passage of one impeller and on the side thereof facing said end of said impeller shaft which is on the side thereof closest the other impeller and said inlet conduit communicating with the said other impeller to first stage discharge pressure, said 4 stantially equal axial pressure against said impellers tending to urge said impellers toward each other on said shaft, liquid seals between said housing and said shaft outwardly of said impellers, the inner ends of said seals being both subjected to first stage discharge pressure.

6. The structure of claim'5 and in which each of said liquid seals includes a series of sealing rings and a packing gland outwardly thereof.

7. In a centrifugal pump, a pump housing, an impeller shaft supported in said housing, a pair of axially spaced impellers on said shaft, said housing including volutes encircling said impellers, said housing having an axially ex- 2. The structure of claim 1 and including shoulder means on said shaft between said impellers against which said impellers are urged by said first stage discharge pressure.

3. The structure of claim 2 and in which said shoulder means comprises the ends of a larger diametershaft portion on said shaft between said impellers.

4. The structure of claim 1 and including sealing means between said inlet passages and said housing, and including a sealing means between the side of said other impeller opposite the discharge passage and said housing.

5. In a centrifugal pump, a pump housing, an impeller shaft supported in said housing, a pair of axially spaced impellers on said shaft, said housing including volutes encircling said impellers, said housing including an axially extending inlet passage on one side of each impeller, said impellers being arranged with the inlet passages facing the same end of said impeller shaft, said housing including an inlet conduit terminating between said impellers in communication with the inlet passage ofone impeller and on the side thereof facing said end of said impeller shaft which is on the side thereof closest the other impeller and said inlet conduit communicating with the side of the other impeller opposite the inlet side thereof, said housingincluding a passage leading from the volute of said one impeller to the side of said other impeller facing said end of said impeller shaft and to the inlet passage of the other impeller subjecting the inlet side of said other impeller to first stage discharge pressure,*said housing including a pressure chamber on the side of said one impeller opposite said inlet passage thereof communicating with the first stage volute and'subjecting said opposite side of said one impeller to firststage discharge pressure, and said housing including a discharge conduit connected to thevolute of said other impeller, first stage discharge pressure on the outer sides of said'impelers providing subtending inlet passage on one side of each impeller, said impellers being arranged with the inlet passages facing the same end of said impeller shaft, said pump housing including a first stage suction chamber on the side of the first stage impeller facing said end of-.said impeller shaft and communicating with the inlet passage of one impeller, said housing having a first stage discharge passage leading from the volute of one said impeller to the inlet side of the other impeller and on the side thereof facing said end of said impeller shaft, said pump housing including a first stage pressure chamber on the side of said one impeller opposite the inlet side, in communication with the first stage volute and at the discharge pressure of the first stage, a wear ring supported by said housing encircling each said inlet passage, a cylindrical flange on the side of said other impeller opposite said inlet passage, of said other impeller, and a wear ring supported by said housing encircling said flange, said wear rings being in sealing "relation to the said other impeller, a discharge conduit '9Q11nected to thevolute of said other impeller, and said housing including a chamber on the side of said other impeller opposite said inlet passage on said other impeller and inwardly of said flange on said other impeller connected to said first stage suction chamber, the impellers being so arranged that the inlet side of said one impeller and said opposite side of said other impeller are subject to first stage suction, while the inlet side of said other impeller and the side of said one impeller op posite the inlet side are subject to first stage'discharge ptreisure, thereby equalizing axial pressure on said impeller s a t.

References Cited in the file of this patent UNITED STATES PATENTS 1,927,543 Doyle Sept. 19, 1933 FOREIGN PATENTS 19,470 Great Britain of 1905 645,921 Great Britain Nov. 8, 1950 739,007 Germany Sept. 8, 1943

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