Rotary positive displacement pump

Patent metadata

Field	Value
Publication number	US-12060882-B2
Application number	US-202117914904-A
Country	US
Kind code	B2
Filing date	Mar 26, 2021
Priority date	Mar 31, 2020
Publication date	Aug 13, 2024
Grant date	Aug 13, 2024

Abstract

A rotary positive displacement pump includes a main body rotationally supporting two parallel, axially extending, shafts with gears in constant mesh condition, such that the shafts rotate in opposite directions. A rotor case body is connected to a front side of the main body and has a stationary interior pumping cavity, fluid product inlet and outlet openings, and two cylindrical rotor case hubs each receiving internally one of the shafts. A pair of rotors each have a rotor wing and a rotor drive element that is mounted torque proof on a rotor seat at an end region of one of the shafts. Each rotor seat pair has an axial abutment surface and a mounting surface. The pump also includes fasteners each engaging a mating section of one of the shafts and exerting an axial clamping force on one of the rotor drive elements against one of the axial abutment surfaces.

First claim

The invention claimed is:

1. A rotary positive displacement pump for pumping a fluid product, the pump having a pump front side and a pump rear side and comprising:
a main body providing rotational support to a pair of parallel, axially extending, shafts with gears in constant mesh condition, such that the pair of shafts are arranged to rotate in opposite directions,
a rotor case body connected to a front side of the main body and having:
a stationary interior pumping cavity defined by an axial rear wall, a circumferential side wall, and a removable front cover,
a fluid product inlet opening,
a fluid product outlet opening, and
a pair of cylindrical rotor case hubs extending from the rear wall, wherein each cylindrical rotor case hub receives internally one of the pair of shafts,

a pair of rotors, each having at least one rotor wing and a rotor drive element that is mounted torque proof on a rotor seat at an end region of one of the pair of shafts,
wherein each of the pair of rotor seats has an axial abutment surface facing in an axial direction towards a front side of the pump and a mounting surface facing radially outwards,
wherein the pump further comprises a pair of fasteners, each being engaged with a mating section at the end region of one of the pair of shafts, and each exerting an axial clamping force on one of the rotor drive elements against the axial abutment surface of one of the rotor seats, and
wherein the axial abutment surface of each rotor seat is located axially outside, towards the pumper front side, of the associated hub.

2. The rotary positive displacement pump according to claim 1 , wherein a mounting portion of each rotor drive element is radially non-overlapping the associated cylindrical rotor case hub.

3. The rotary positive displacement pump according to claim 1 , wherein a mounting portion of each rotor drive element includes an axial abutment surface facing in an axial direction towards a rear side of the pump and a mounting surface facing radially inwards, and wherein the axial abutment surface of each mounting portion is located axially outside, towards the pump front side, of the associated hub.

4. The rotary positive displacement pump according to claim 2 , wherein the mounting portion of each rotor drive element does not extend radially outside of an inner diameter of the associated cylindrical rotor case hub.

5. The rotary positive displacement pump according to claim 3 , wherein each rotor drive element comprises an annular projection extending towards the rear side of the pump, wherein the annular projection comprises the axial abutment surface, and wherein each annular projection is arranged on a portion of the associated shaft.

6. The rotary positive displacement pump according to claim 1 , further comprising a first pair of seal assemblies, each having a first part and a second part with sealing surfaces pressed against each other, and each arranged to prevent fluid product from escaping the stationary pumping cavity and flowing along one of the shafts towards the rear side of the rotor case body.

7. The rotary positive displacement pump according to claim 6 , wherein each cylindrical rotor case hub has a front seal seat facing towards the pump front side of the pump, wherein the front seal seat is located at a front region of each rotor case hub, and wherein each front seal seat has the first part of one of the first pair of seal assemblies mounted therein.

8. The rotary positive displacement pump according to claim 6 , wherein the first part of each first pair of seal assemblies faces, as seen in the radial direction, a circumferential outer surface of a portion of the associated shaft.

9. The rotary positive displacement pump according to claim 6 , wherein each rotor drive element has a rotor seal seat facing towards the rear side of the pump, wherein each rotor seal seat has the second part of one of the first pair of seal assemblies mounted therein.

10. The rotary positive displacement pump according to claim 6 , wherein the rotary positive displacement pump is configured for front-loading of the first pair of seal assemblies.

11. The rotary positive displacement pump according to claim 7 , wherein an exterior diameter of each shaft in an axial region of the front seal seat of each cylindrical rotor case hub, is larger than an exterior diameter of each shaft in an axial region of, and in contact with, a mounting portion of each rotor drive element.

12. The rotary positive displacement pump according to claim 6 , further comprising a second pair of seal assemblies, each having a first part and a second part with sealing surfaces pressed against each other, and each arranged to prevent fluid product from flowing along the shaft towards the rear side of the rotor case body.

13. Method for assembling a rotary positive displacement pump for pumping a fluid product, the pump having a pump front side and a pump rear side, the method comprising:
providing a main body giving rotational support to a pair of parallel, axially extending, shafts with gears in constant mesh condition, such that the pair of shafts are arranged to rotate in opposite directions,
providing a rotor case body having:
a stationary interior pumping cavity defined by an axial rear wall, a circumferential side wall, and a removable front cover,
a fluid product inlet opening,
a fluid product outlet opening, and
a pair of cylindrical rotor case hubs extending from the rear wall, wherein the rotor case body is located on a front side of the main body, and wherein each cylindrical rotor case hub receives internally one of the pair of shafts,

providing a pair of rotors, each having at least one rotor wing and a rotor drive element,
mounting each rotor drive element torque proof on a rotor seat at an end region of one of the pair of shafts, wherein each rotor seat has an axial abutment surface facing in an axial direction towards the pump front side of the pump and a mounting surface facing radially outwards,
mounting a fastener on an end region of each of the pair of shafts,
tightening the pair of fasteners for exerting an axial clamping force on each rotor drive element against the axial abutment surface of one of the rotor seats, wherein the axial abutment surface of each rotor seat is located axially outside, towards the pump front side, of the associated hub, and
mounting the removable front cover on the rotor case body.

14. Method according to claim 13 , further comprising an intermediate step, performed before mounting the rotor drive elements to the shafts, of mounting a first part of a first pair of seal assemblies in a front seal seat of each cylindrical rotor case hub, and mounting a second part of the first pair of seal assemblies in a rotor seal seat of each rotor drive element.

15. Method for providing maintenance to a sealing arrangement of a rotary positive displacement pump having a pump front side and a pump rear side, two parallel axially extending shafts each carrying a rotor having at least one rotor wing and a rotor drive element, and an interior pumping cavity including a pair of cylindrical rotor case hubs each extending towards the pump front side from a rear wall of the interior pumping cavity, wherein each shaft has a rotor seat with an axial abutment surface facing in an axial direction towards the pump front side, the method comprising:
removing a removable front cover of the pump,
removing at least one of the pair of rotors from the associated shaft for enabling access to the sealing arrangement configured for preventing leakage along a gap between the associated shaft and

Assignees

• Alfa Laval Corp Ab

Inventors

• Cargill Simon

Classifications

• F04C15/0026

  Elements specially adapted for sealing of the lateral faces of intermeshing-engagement type machines or pumps, e.g. gear machines or pumps · CPC title

• F04C15/0073

  Couplings between rotors and input or output shafts acting by interengaging or mating parts, i.e. positive coupling of rotor and shaft · CPC title

• F04C2230/604

  Mounting devices for pumps or compressors · CPC title

• F04C2/126

  with radially from the rotor body extending elements, not necessarily co-operating with corresponding recesses in the other rotor, e.g. lobes, Roots type · CPC title

• F04C2230/60

  Assembly methods · CPC title