US3198582A

US3198582A - Screw pump

Info

Publication number: US3198582A
Application number: US223106A
Authority: US
Inventors: Albert A Zalis
Original assignee: Warren Pumps LLC
Current assignee: Warren Pumps LLC
Priority date: 1962-09-12
Filing date: 1962-09-12
Publication date: 1965-08-03
Anticipated expiration: 1982-08-03

Description

Aug. 3, 1965 A. A. ZALIS 3,198,582

SCREW PUMP Filed Sept. 12, 1962 A E A m xmwl 6 25 I2 33 I I7 47 I9 ALBERT A. ZALIS INVENTOR.

w lmwzwgw United States Patent 3,198,582 SCREW PUMP Albert A. Zalis, Warren, Mass, assignor to Warren Pumps, Inc, Warren, Mass, a corporation of Massachusetts Filed Sept. 12, 1962, Ser. No. 223,106 Claims. (ill. 3432-44) This invention relates to a screw pump and, more particularly, to apparatus arranged to produce a change in pressure and flow in materials having a high concentration of solid particles.

There are some materials which, because of the presence of large particles or pieces of solid material, are difficult to pump. For instance, in a paper mill, bulk wood chips have heretofore been handled by chain conveyors and similar handling equipment. A similar situation exists in the grain industries and in handling coal slurries. The problem which is common to all of these industries is that the large solid particles, i.e., the wood chips, kernels of grain, large particles of coal, jam in the actuating parts of the pump. The screw pump is, for many reasons, a very desirable type of pump to use in such applications, but the screw pumps of the prior art have suffered from the deficiency that tough fibrous particles, such as wood chips, have a tendency to jam between the screw surfaces; this may render the pump inoperative or may absorb a considerably higher amount of power in its operation than would otherwise be true. These and other difficulties of the prior art have been obviated in a novel manner by the present invention.

It is, therefore, an outstanding object of the invention to provide a screw pump capable of handling materials having a high concentration of large solid particles.

Another object of this invention is the provision of a screw pump having an axial discharge.

A further object of the present invention is the provision of a screw pump having a novel bearing mounting means for the screw shafts.

It is another object of the instant invention to provide a screw pump having an axial discharge in which the screw shaft bearings are mounted in the axial outlet passage without seriously impeding the flow of material.

It is a further object of the invention .to provide a screw pump having its shaft hearings in the flow of material provided with a seal of unusual effectiveness.

A still further object of this invention is the provision of a screw pump having shaft bearings which lie close to the flow of material and which are provided with means for preventing the entrance of material into the bearing surfaces.

It is a still further object of the present invention to provide a screw pump in which large fibrous particles will not jam between the screw surfaces.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

The character of the invention, however, may be best understood by reference to one of its structural forms, as illustrated by the accompanying drawings in which:

FIG. 1 is a perspective view of a pump embodying the principles of the present invention;

FIG. 2 is a horizontal sectional view of the pump taken on the line 11-11 of FIG. 1; and

FIG. 3 is a vertical sectional view of the invention taken on the line Til-III of FIG. 2.

Referring first to FIG. 1, wherein are best shown the general features of the invention, the screw pump, indicated generally by the reference numeral It is shown as having an elongated body 11 which is formed in four parts, namely, a gear box 12, a bearing portion 13, a main portion 14, and a discharge portion 15. Extending upwardly from the main portion 14 of the body adjacent the bearing portion 13 is an inlet opening 16 surrounded by a flange 17 by which it may be connected to a conduit. The discharge portion 15 is generally tubular; it is provided on its inboard end with a flange 18 by which it is attached to the main portion 14 and at its outboard end with a flange 19 by which it may be attached to a conduit. Extending from the gear box 12 is a drive shaft 21 which is adapted to be attached to a drive motor, not shown. The main body is Supported by two

legs

22 and 23 which extend downwardly from opposite ends of the main portion 14. part of the discharge portion 15 and is connected at its outer end to a source (not shown) of lubricant under pressure.

Referring now to FIGS. 2 and 3, it can be seen that the gear box 12 is provided with a cover 25 from which the drive shaft 21 extends. A ball bearing 26 is carried in the gear box to hold the shaft 21, while a roller bearing 27 mounted in the bearing portion 13 also supports the shaft. A suitable seal 28 is mounted in the cover 25 around the drive shaft 21. Keyed to the drive shaft Within the gear box is a pinion gear 29 which meshes with two

gears

31 and 32. The

gears

31 and 32 are mounted, respectively, on the

shafts

33 and 34 which carry the

main screws

35 and 36 of the pump. The shaft 33 is supported in a bearing 37 located in the gear box 12 and a bearing 38 located in the bearing portion 13, the bearing holding the shaft on either side of the gear 31. The bearing portion 13 is provided with a stufling box 39 which surrounds the shaft 33 as it leaves the bearing portion 13 and enters the main portion 14. Mounted on the shaft 33 under the inlet opening 16 is a special feed screw 41. The feed screw 41 and the main screw 35 are held axially tightly together on the shaft 33 by a pressure nut 42. Similarly, the shaft 34 is provided with a stulfing box 43 and a feed screw 44. The main feed screws rotate in the same direction, as is evident from the drive arrangement in the gear box 12. They are of a special configuration (dictated by the geometry of two screw surfaces which rotate in the same direction) to provide very excellent pumping sealing action. From the nature of such conjuga-te action there is never any instant when two surfaces portion 15 and then decreases in diameter to a circular outlet opening 46. Extending vertically across the largest diameter of the chamber are two

pedestals

47 and 48 associated with the

shafts

33 and 34, respectively. The pedestal 47 consists of an upper portion 49, a central portion 51, and a lower portion. The upper portion 49 and the lower portion are streamlined in the direction ofmaterial fiow; that is to say, they are narrow in the transverse direction and elongated in the axial direction. The upper and lower portions serve to support the central portion 51 which is generally in the form of a hub or cylinder with its axis in the direction of the axes of the shafts. The pedestal 48 is similarly formed.

The central portion 51 is provided with a longitudinal bore 53 in which is mounted a bearing sleeve 54 which carries a reduced portion 55 of the shaft 33. The conduit 24- carrying high pressure lubricant is attached to a pas- A conduit 24 is connected to the upper central a) sage 56 which extends radially inwardly from the upper part of the discharge portion 15 through the upper portion 49 of the pedestal 47 and through the sleeve 54. A cover 57 is bolted to the downstream side of the central portion 51 of the pedestal 47 and covers the ends of the bolt 53, the sleeve 54, and the reduced portion 55 of the shaft.

On the shaft 33 adjacent the pedestal 47 on the upstream side is mounted a sealing ring 58. This ring is provided with a generally frusto-conical outer surface 59 which serves as a transition between the cylindrical surface of the hub of the screw 35 and the outside diameter of the central portion 51 of the pedestal 47. The central portion of the pedestal is provided with an annular axial groove 61 in which lies an annular axial flange 62 formed on the ring 58. The groove and flange fit together very tightly to provide a labyrinth from the main pumping passages into the mating bearing surfaces between the sleeve 54 and the reduced portion 55 of the shaft 33. A taper pin 63 extends through the hub of the main screw 35 and acts as a stop against which the main screw 35 and the feed screw 41 may be tightly pressed by means of the pressure nut 42. The pedestal 48 is provided in its central portion with a similar sealing ring 64 and the hub of the main screw 36 is provided with a taper pin 65. It should be noted that the sealing ring 58 is locked to the shaft 33 by a key 66 so that it rotates with the shaft and is not fixed to the pedestal 47. Furthermore, the inside bore of the ring 58 is the same size as the main part of the shaft 33 and the junction between the main portion of the shaft and the reduced portion 55 lies within the ring. The sleeve 54 is long enough to extend into the ring 58 and abut against the shoulder between the main portion of the shaft 33 and the reduced portion'55.

The operation of the pump will now be readily understood in view of the above description. Material to be pumped enters the pump through the inlet opening 16 from a conduit to which the flange 17 has been bolted. The material flows vertically onto the feed screws 41 which are of a sufiicient coarseness, strength, and lead to cause the material to flow toward the

main screws

35 and 36. The material is picked up by the main screws and flows longitudinally through the body 11, eventually leaving the ends of the

main screws

35 and 36. The material flows into the chamber 45 and flows around the

pedestals

47 and 48, finally leaving through the outlet opening 46 into a conduit which has been bolted to the flange 19. Since the material may contain a liquid of a corrosive nature and since the solids may consist of abrasive particles, it is important that none of this material enter the bearings around the

shafts

33 and 34. At the inlet end of the pump, the

stufling boxes

39 and 43 prevent the material from leaving around the shafts in that direction. Furthermore, the bearing portion 13 is provided with vertical passages so that the shafts are exposed to the atmosphere and any material leaking out of the stuffing box area will fall to the exterior of the pump. It will not be carried into the hearings on which the inlet ends of the shafts are carried. At the exit end, the material is prevented from entering the bearing surface between the reduced portion 55 of the shaft 33 and the bearing sleeve 54 on the upstream side because of the presence of the sealing ring 58. Material would have to enter at the dividing line between the pedestal 47 and the sealing ring 58, go around the labyrinth provided by the flange 62 and the groove 61, reverse its direction to go around the end of the sleeve 54 which lies in the center of the sealing ring, flow radially along the shoulder between the main part of the shaft 33 and the reduced portion 55 before arriving at the bearing surfaces. On the other hand, the lubricant case of a water slurry, the lubricant selected would prob ably be water. In the case where wood chips are being pumped, water could also be used as a lubricant since it would not affect the nature of the chips. On the downstream side there can be no admittance to the hearing because of the solid cover 57 in the case of the pedestal 47 and a similar cover 67 in the case of the pedestal 48. Where the material contains large fibrous particles, such as would be the case when pumping wood chips, the nature of the screws, whereby they rotate in the same direction and have no surfaces which are come together, makes it impossible for such particles to be pinched and to jam the pump. The power which must be transmitted into the pump through the drive shaft 21 is, therefore, much lower than would otherwise be necessary. It will be understood that the cross sectional area of the chamber 45 from one end to the other, that is to say, from its beginning at the end of the

main screws

35 and 36 to its termination at the outlet opening 46, is selected to be substantially the same. In the area of the

pedestals

47 and 43 the cross-sectional area is selected so that when the transverse pedestal area is subtracted from the main area of the chamber the available flow area is substantially the same as the cross-sectional area in the open parts of the passage.

Minor changes may be made in the form and construction of the invention without departing from the material spirit thereof. It is not, however, desired to confine the invention to the exact form herein shown and described, but it is desired to include all such as properly come within the scope claimed.

The invention having been thus described, what is claimed as new and desired to secure by Letters Patent is:

1. A screw pump for materials containing a high concentration of solid particles, comprising (a) an elongated body,

(b) two shafts extending through the body,

(c) means connecting the shafts for rotation in the same direction,

(d) a pumping screw associated with each shaft,

(e) an inlet opening in the body adjacent the screws at one end of the body,

(f) an outlet passage in the body extending coaxially of the screws at the other end of the body,

(g) a pedestal for each shaft extending across the outlet passage, the pedestal being streamlined and without flat surfaces facing upstream in the direction of the axes of the shafts, and

(h) a bearing mounted in each pedestal and carrying one of the shafts.

2. A screw pump for material containing a high concentration of solid particles, comprising (a) an elongated body,

(b) two shafts extending through the body,

(c) means connecting the shafts for rotation in the same direction,

(d) a pumping screw associated with each shaft,

(e) an inlet opening in the body adjacent the screws at one end of the body,

(g) a streamlined pedestal for each shaft extending across the outlet passage,

(h) a bearing mounted in each pedestal and carrying one of the shafts, and

(i) means associated with the bearing to supply it with a lubricant under pressure, which lubricant is com- A patible with the material being pumped.

3. A screw pump for materials containing a high concentration of solid particles, comprising (a) an elongated body,

(b) two shafts extending through the body,

(0) means connecting the shafts for rotation in the same direction,

(d) a pumping screw associated with each shaft,

(e) an inlet opening in the body adjacent the screws at one end of the body,

(g) a streamlined pedestal for each shaft extending across the outlet passage,

(h) a bearing mounted in each pedestal and carrying one of the shafts,

(i) an annular axial groove formed in the pedestal around the bearing, and

(j) a sealing member mounted on a shaft and having an annular ridge which fits tightly in the said annular groove.

4. A screw pump for materials containing a high concentration of solid particles, comprising (a) an elongated body,

(b) two shafts extending through the body,

(c) means connecting the shafts for rotation in the same direction,

(d) a pumping screw associated with each shaft,

(e) an inlet passage in the body extending vertically above the screws at one end of the body,

(f) an outlet passage of generally circular cross-section in the body extending coaxially of the screws at the other end of the body,

(g) two pedestals extending vertically across the outlet passage, the pedestal being streamlined and without flat surfaces facing upstream in the direction of the axes of the shafts,

(h) a bearing mounted in each pedestal and carrying one of the shafts, each pedestal consisting of a central enlarged portion in which the bearing is mounted and two narrow convecting portions extending in opposite directions from the enlarged portion to the surface of the passage,

(i) means associated with the bearing to supply it with a lubricant under pressure, which lubricant is compatible with the material being pumped,

(j) an annular axial groove formed in the enlarged portion of each pedestal around each bearing, and

(k) a sealing member mounted on each shaft and having an annular ridge which fits tightly in the said annular groove.

5. A screw pump for materials containing a high concentration of solid particles, comprising (a) an elongated body having an inlet at one end,

(13) two shafts extending through the body,

(c) means connecting the shafts for rotation in the same direction,

(d) a pumping screw associated with each shaft,

(e) an outlet passage in the body extending coaxially with the screws at the other end of the body, from the discharge end of the screws to an outlet opening in the body,

(f) a streamlined pedestal for each shaft extending across the outlet passage, and

(g) a bearing mounted in the pedestal and carrying one of the shafts, the passage being enlarged in the vicinity of the pedestals so that the unrestricted area at that point is substantially the same as the area of the outlet opening.

References Cited by the Examiner UNITED STATES PATENTS 1,762,708 6/30 Allred 103-89 2,448,745 9/ 48 Struckmann 302-50 2,924,181 2/60 Sonnet 103-128 3,060,512 10/62 Martin et a1.

SAMUEL F. COLEMAN, Primary Examiner.

LAURENCE V. EFNER, Examiner.

Claims

1. A SCREW PUMP FOR MATERIAL CONTAINING A HIGH CONCENTRATION OF SOLID PARTICLES, COMPRISING (A) AN ELONGATED BODY, (B) TWO SHAFTS EXTENDING THROUGH THE BODY, (C) MEANS CONNECTING THE SHAFTS FOR ROTATION IN THE SAME DIRECTION, (D) A PUMPING SCREW ASSOCIATED WITH EACH SHAFT, (E) AN INLET OPENING IN THE BODY ADJACENT THE SCREWS AT ONE END OF THE BODY. (F) AN OUTLET PASSAGE IN THE BODY EXTENDING COAXIALLY OF THE SCREWS AT THE OTHER END OF THE BODY, (G) A PEDESTAL FOR EACH SHAFT EXTENDING ACROSS THE OUTLET PASSAGE, THE PEDESTAL BEING STREAMLINED AND WITHOUT FLAT SURFACES FACING UPSTREAM IN THE DIRECTION OF THE AXES OF THE SHAFTS, AND (H) A BEARING MOUNTED IN EACH PEDESTAL AND CARRYING ONE OF THE SHAFTS.