US20090196768A1

US20090196768A1 - Floating cup pump assembly

Info

Publication number: US20090196768A1
Application number: US12/024,795
Authority: US
Inventors: Bryan E. Nelson; Viral S. Mehta; Kirat Shah
Original assignee: Caterpillar Inc
Current assignee: Caterpillar Inc
Priority date: 2008-02-01
Filing date: 2008-02-01
Publication date: 2009-08-06

Abstract

A pump assembly with a rotor adapted to rotate around a first axis and supporting outwardly projecting piston elements includes at least one drum plate adapted to rotate around a second axis in angled relation to the first axis. The drum plate supports outwardly projecting cup elements such that the cup elements mateably engage distal portions of corresponding piston elements. A curved surface support element is mounted in sliding relation along a rotatable shaft structure and operatively engages the drum plate. A biasing element urges the curved surface support element and drum plate away from the rotor.

Description

TECHNICAL FIELD

This patent disclosure relates generally to pump assemblies and, more particularly, to floating cup pump assemblies utilizing a plurality of piston elements disposed around a first rotating surface and a plurality of complimentary cup elements disposed around a second rotating surface. The piston elements reciprocate within the cup elements during rotation.

BACKGROUND

Pumping devices utilizing a plurality of pistons mounted around a first rotor and a plurality of complimentary cup elements mounted around a swash plate in angled relation to the piston rotor are generally known. One such device is disclosed in United States Patent Application No. 2006/0222516 in the name of Achten having a publication date of Oct. 5, 2006. Embodiments of pumps described in this reference include a rotor having a plurality of pistons projecting away from both sides of the rotor. These embodiments further include a pair of cooperating drum plates supporting an arrangement of cup elements or drum sleeves adapted to house distal portions of the pistons. The rotor supporting the pistons rotates around a first axis of rotation. The drum plates rotate in angled relation to the first axis. The rotor supporting the pistons is rotated in tandem with the drum plates during operation. Due to the angle between the rotor and the drum plates, the pistons are caused to stroke along the length of the corresponding cup elements such that the volume occupied by the piston elements is alternately increased and decreased during a rotational cycle. Thus, fluid introduced into a cup element when the complimentary piston is in a substantially withdrawn position may be pressurized and expelled as the piston is pushed inwardly during the rotational cycle.
The noted reference discloses that the drum plate housing cup elements rotate around a convex centering surface or ball guide that is understood to be integral with a drive shaft. The disclosed pump assembly further incorporates a relatively complex arrangement to control the position of the drum plate relative to an outboard faceplate. Specifically, a plurality of springs is held in a compressed state between a pair of ring structures. One of the ring structures is supported against the curved support surface at a position inboard of the cup springs while the other ring structure is supported against the drum plate at a position outboard of the cup springs. Because the curved support is held in a fixed position integral with the drive shaft, the biasing force of the compressed cup springs is translated across the outboard ring structure to the drum plate thereby urging the drum plate to an outboard position in contact with the faceplate. This arrangement is relatively complex and may be difficult to construct due to the need to hold the cup springs in compressed relation between the ring structures during the assembly process. Accordingly, an alternative construction which provides the desired biasing forces while reducing complexity is desirable.
The foregoing background discussion is intended solely to aid the reader. It is not intended to limit the disclosure, and thus should not be taken to indicate that any particular element of a prior system is unsuitable for use within the disclosed examples, nor is it intended to indicate any element, including solving the motivating problem, to be essential in implementing the examples described herein. The full scope of the implementations and application of the examples described herein are defined by the appended claims.

SUMMARY

The disclosure describes, in one aspect, a pump assembly having a rotor supporting a plurality of outwardly projecting piston elements. The rotor is adapted to rotate about a first axis. The pump assembly further includes at least one drum plate supporting a plurality of outwardly projecting cup elements. The drum plate is adapted to rotate about a second axis in angled relation to the first axis. Cup elements supported at the drum plate are adapted to mateably engage distal portions of corresponding piston elements such that the cup elements circumferentially surround such distal portions of the piston elements. The pump assembly further includes a curved surface support element operatively engaging the drum plate. The curved surface support element is mounted in sliding relation along a rotatable shaft structure. At least one biasing element is disposed between the rotor and the curved surface support element thereby urging the curved surface support element and drum plate away from the rotor.
In another aspect this disclosure describes a method for constructing a pump assembly. This method includes providing a rotor supporting a plurality of outwardly projecting piston elements and further providing at least one drum plate supporting a plurality of outwardly projecting cup elements. The rotor and drum plate are oriented in angled relation such that the rotor is rotatable around a first axis and the drum plate is rotatable around a second axis in angled relation to the first axis. A curved surface support element is provided to operatively engage the drum plate. The curved surface support element is mounted in sliding relation along a rotatable shaft structure at least one biasing element is provided between the rotor and the curved surface port element such that the curved surface support element and the drum plate are urged away from the rotor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cut-away schematic view illustrating components of an exemplary floating cup pump assembly;

FIG. 2 is an exploded schematic assembly view illustrating a curved surface support element relative to a rotatable shaft structure; and

FIG. 3 is a cut-away schematic view illustrating a distal portion of a piston element at the interior of a cooperating cup element.

DETAILED DESCRIPTION

This disclosure relates to a pump assembly incorporating a rotor supporting a plurality of outwardly projecting piston elements and at least one complimentary drum plate supporting a plurality of cup elements adapted to engage portions of corresponding piston elements. The rotor and drum plate are angled relative to one another. During a rotational cycle the pistons move in a reciprocating manner relative to the cup elements. A pressure biased support element is disposed in separable relation to a rotatable shaft structure to translate rotational and biasing forces to the drum plate thereby urging the drum plate away from the rotor.
Reference will now be made to the drawings, wherein like reference numerals designate like elements in the various views. FIG. 1 illustrates a pump assembly 10 adapted to be mounted within a housing (not shown). In this exemplary construction, a rotatable shaft structure 12 extends along a first axis 13. The rotatable shaft structure 12 is adapted for rotation around axis 13 by use of a motor or other external power source. The rotatable shaft structure 12 engages a rotor 14 in the form of a disk or plate structure. Thus, rotation of rotatable shaft structure 12 is translated to rotor 14 such that rotor 14 rotates around the same axis as rotatable shaft structure 12, namely axis 13.
In the exemplary construction illustrated in FIG. 1, rotor 14 supports an arrangement of piston elements 16 projecting away from opposing faces of rotor 14. In this regard, it is to be understood that while piston elements 16 are illustrated as projecting away from both sides of rotor 14, it is likewise contemplated that piston elements 16 may be disposed across a single side of rotor 14 if desired. As shown, piston elements 16 may have a generally frusto-conical configuration such that piston elements 16 taper outwardly as distance increases away from rotor 14. However, other suitable constructions may likewise be utilized as desired.
In the illustrated construction of FIG. 1, pump assembly 10 includes a pair of drum plates 18 disposed on either side of rotor 14. As shown, drum plates 18 support an arrangement of cup elements 20 having acceptance openings projecting towards rotor 14. The cup elements 20 are arranged to house distal portions of complimentary piston elements 16. As best illustrated in FIG. 3, cup elements 20 may have a cross-sectional shape and size substantially corresponding to distal portions of piston elements 16 such that piston rings 22 provide a substantially fluid tight sealing relation between piston elements 16 and interior portions of cup elements 20. In this configuration, cup elements 20 circumferentially surround distal portions of corresponding piston elements 16 such that piston elements 16 cooperate with interior boundary walls of cup elements 20 to define a plurality of variable volume chambers 24. In this regard, it will be understood that piston rings 22 are optional and may be eliminated if an adequate sealing relation is obtained directly between the piston elements 16 and cup elements 20. In the exemplary construction illustrated in FIG. 1, the variable volume chambers 24 are in fluid communication with inlet ports 30 and outlet ports 32 arranged in face plates 34 disposed in outboard relation to drum plates 18. Although the illustrated construction uses a pair of drum plates 18, such a construction is exemplary only. Thus, it is likewise contemplated that a single drum plate 18 disposed on one side of rotor 14 may be utilized if desired.
According to the exemplary construction illustrated in FIG. 1, drum plates 18 are arranged in circumferential relation to rotatable shaft structure 12 and are oriented at an angle relative to rotor 14. Thus, drum plates 18 and cup elements 20 supported thereon are rotatable around axis lines disposed in angled relation to the axis of rotatable shaft structure 12. According to the exemplary construction, drum plates 18 are supported in this angled orientation by curved surface support elements 40 alternatively referred to as “ball guides” which are arranged around rotatable shaft structure 12 outboard from rotor 14. As best illustrated through joint reference to FIGS. 1 and 2, curved surface support elements 40 include a convex exterior support surface 42 adapted to engage a portion of drum plates 18. The curved surface support elements 40 may further include an arrangement of detents 44 to translate rotational movement to the surrounding drum plates 18.
By way of example only, and not limitation, it is contemplated that curved surface support elements 40 may have a substantially unitary construction such that detents 44 are formed integrally with convex exterior support surface 42. Such structures may be formed by casting, powder metallurgy, or other suitable formation techniques using metal alloys or other materials adapted to withstand substantial cyclical stresses. However, it is likewise contemplated that portions of the curved surface support element 40 may be formed separately and thereafter joined together if desired. According to a contemplate practice, the curved surface support elements 40 may be formed separately from components of rotatable shaft structure 12 such that curved surface support elements 40 are non-integral with rotatable shaft structure 12. Curved surface support elements 40 may thereafter be held in separable relationship relative to rotatable shaft structure 12 during operation. That is, curved surface support elements 40 may be subject to nondestructive removal from rotatable shaft structure 12 upon disassembly of pump assembly 10.
FIG. 2 illustrates one exemplary arrangement for operative connection between rotatable shaft structure 12 and a curved surface support element 40. In the illustrated arrangement, rotatable shaft structure 12 includes a splined collar 50 having a pattern of ridges 52 extending longitudinally along a portion of the collar 50. Ridges 52 are adapted to cooperatively engage a pattern of spaced complimentary grooves 54 arranged around an interior portion of curved surface support element 40. Accordingly, curved surface support element 40 may slide over rotatable shaft structure 12 until engaging splined collar 50. At splined collar 50, ridges 52 engage grooves 54 thereby preventing relative rotational movement between curved surface support element 40 and rotatable shaft structure 12. However, curved support element 40 may nonetheless retain the ability to engage in some degree of sliding movement relative to rotatable shaft structure 12. Of course, it is to be understood that the illustrated construction is exemplary only and that any number of other constructions may likewise be utilized. By way of example only, and not limitation, in one such alternative arrangement the interlocking ridges and grooves may be reversed if desired such that ridges are disposed at the interior of curved surface support element 40 with corresponding grooves being located along splined collar 50.
As illustrated, an arrangement of detents 44 may extend away from curved surface support elements 40 for keyed engagement with cooperating slot openings 46 in drum plates 18. As rotatable shaft structure 12 is rotated, the rotational movement is translated to drum plates 18 through curved surface support elements 40. As may be seen through comparison of the upper and lower halves of FIG. 1, due to the tilted arrangement of drum plates 18, the relative position of detents 44 shifts axially along slot openings 46 during the rotational cycle. To accommodate the shifting axial position of detents 44, the slot openings 46 are of a generally elongated configuration such that detents 44 can slide along the length of the slot openings 46. The cross-sectional width of slot openings 46 may substantially correspond to the cross-sectional width of detents 44 so as to maintain good rotational power transfer between curved surface support elements 40 and drum plates 18.
In the exemplary construction curved surface support elements 40 are continuously biased away from rotor 14 by use of an arrangement of biasing elements 60 such as compression springs or the like disposed at positions around rotatable shaft structure 12. In this regard, it will be understood that biasing elements 60 may be of different constructions on each side of rotor 14 as required to conform to the body contours of rotor 14. In operation, biasing elements 60 apply a compression force which operates along a line of force substantially parallel to the axis of rotation of rotatable shaft structure 12. The biasing elements 60 thus assist in maintaining proper spacing between rotor 14 and curved surface support elements 40 while simultaneously urging curved surface support elements 40 away from rotor 14. As shown, biasing elements may operate directly against rotor 14 and curved surface support elements 40 without the need for intermediate ring structures, although such intermediate ring structures may be used if desired.
Force provided by biasing elements 60 is also utilized to maintain pressure between outer wall portions of drum plates 18 and inner wall portions of face plates 34. As will be appreciated, maintaining such pressure may be beneficial in avoiding leakage between those plate structures. In the illustrated construction, drum plates 18 include an angled cheek portion 70 adapted to engage a segment of convex exterior support surface 42. As shown, angled cheek portion 70 is disposed at an outboard position relative to detents 44 substantially along the line of force provided by biasing element 60. In this regard, it is contemplated that the cheek portions 70 may be integral to drum plates 18 or may be formed as separate components. As curved surface support element 40 is urged away from rotor 14, pressure is applied against cheek portion 70. Thus, a portion of the compressive force provided by biasing element 60 is translated across curved surface support element 40 to drum plate 18. Accordingly, both the curved surface support element 40 and drum plate 18 are continuously urged away from rotor 14 and drum plate 18 is pressed against face plate 34. The continuous pressure of drum plate 18 against face plate 34 aids in maintaining a contacting sealing relation between drum plate 18 and face plate 34. Fluid is thereby prevented from leaking between drum plate 18 and face plate 34.
Although pump assembly 10 may be adapted for any number of uses, according to one contemplated practice, a fluid may be introduced through inlet port 30 which is aligned with openings in drum plate 18 at a position where piston elements 16 are in the maximum withdrawn state relative to corresponding cup elements 20. In this orientation, variable volume chamber 24 has its maximum capacity. As rotatable shaft structure 12 rotates, such rotational movement is translated to rotor 14 and drum plates 18. As noted previously, drum plates 18 are held in non-perpendicular angled relation relative to the axis of rotation for rotatable shaft structure 12 and rotor 14. Thus, as rotor 14 and drum plates 18 rotate, piston elements 16 are caused to move in a substantially reciprocating manner within corresponding cup elements 20. As piston elements 16 move further into cup element 20, pressure is applied to fluid retained within variable volume chambers 24 such that it may be expelled at outlet ports 32 at increased pressure if desired. During rotation, curved surface support elements 40 are held around rotatable shaft structure 12 such that the curved surface support elements 40 rotate with rotatable shaft structure 12 while nonetheless being slidable longitudinally relative to rotatable shaft structure 12. Biasing elements 60 continuously urge curved surface support elements 40 outwardly away from rotor 14 so as to maintain curved surface support element 40 at a desired position. The biasing force provided by biasing element 60 is also translated across the curved surface support elements 40 thereby pressing drum plates 18 against outboard face plates 34 to assist in maintaining leak free fluid passages.

INDUSTRIAL APPLICABILITY

The industrial applicability of the pump assembly described herein will be readily appreciated from the foregoing discussion. Pump assemblies consistent with the present disclosure may be used to convey fluids through various systems in an efficient manner while maintaining proper operative relation of the various components. By way of example only, and not limitation, exemplary fluids conveyed by the pump assembly may include cooling fluids, lubricating fluids and the like.
In practice, a pump assembly consistent with this disclosure may be utilized in environments such as industrial equipment, on highway vehicles and the like where substantial durability is required. In such environments, the use of biasing elements operating in conjunction with a slidingly engaged curved support element may tend to dampen vibrations and promote stability of operation. Moreover, in the event of damage, the separable curved support element may be replaced without the need to replace the rotatable shaft structure. Accordingly, maintenance may be substantially simplified.

Claims

1. A pump assembly comprising:

a rotor supporting a plurality of piston elements projecting away from said rotor, wherein said rotor is adapted to rotate around a first axis;

a drum plate supporting a plurality of cup elements, said plurality of cup elements being adapted to mateably engage distal portions of said piston elements such that said cup elements circumferentially surround said distal portions of said piston elements, said drum plate being adapted to rotate around a second axis in angled relation to said first axis;

a curved surface support element operatively engaging said drum plate, said curved surface support element being mounted in sliding relation along a rotatable shaft structure between said rotor and said drum plate; and

at least one biasing element disposed between said rotor and said curved surface support element urging said curved surface support element and said drum plate away from said rotor.

2. The pump assembly as recited in claim 1, wherein said curved surface support element is non-integral with said rotatable shaft structure.

3. The pump assembly as recited in claim 2, wherein said curved surface support element is disposed circumferentially around said rotatable shaft structure.

4. The pump assembly as recited in claim 3, wherein said curved surface support element is held in non-rotatable relation relative to said rotatable shaft structure, such that rotation of said rotatable shaft structure is translated to said curved surface support element.

5. The pump assembly as recited in claim 4, wherein said curved surface support element includes a convex exterior surface portion.

6. The pump assembly as recited in claim 5, wherein said curved surface support element further includes at least one detent projecting radially away from said convex exterior surface portion, said at least one detent being adapted to operatively engage said drum plate such that rotation of said rotatable shaft structure is translated to said drum plate.

7. The pump assembly as recited in claim 6, wherein said at least one detent is integral with said convex exterior surface portion.

8. The pump assembly as recited in claim 6, wherein said convex exterior surface portion operatively engages an angled cheek portion of said drum plate.

9. The pump assembly as recited in claim 6, wherein said curved surface support element includes an interior portion adapted to engage a cooperating splined surface of said rotatable shaft structure.

10. The pump assembly as recited in claim 9, wherein said interior portion of said curved surface support element includes a pattern of grooves, and said cooperating splined surface of said rotatable shaft structure includes a pattern of ridges adapted to engage said grooves.

11. The pump assembly as recited in claim 9, wherein said interior portion of said curved surface support element includes a pattern of ridges, and said cooperating splined surface of said rotatable shaft structure includes a pattern of grooves adapted to engage said ridges.

12. A pump assembly comprising:

a rotor supporting a first plurality of piston elements projecting away from a first side of said rotor and a second plurality of piston elements projecting away from a second side of said rotor, wherein said rotor is adapted to rotate around a first axis;

a first drum plate supporting a first plurality of cup elements, said first plurality of cup elements being adapted to mated engagement with distal portions of said first plurality of piston elements such that said first plurality of cup elements circumferentially surround said distal portions of said first plurality of piston elements, said first drum plate being adapted to rotate around a second axis in angled relation to said first axis;

a second drum plate supporting a second plurality of cup elements, said second plurality of cup elements being adapted for mated engagement with distal portions of said second plurality of piston elements such that said second plurality of cup elements circumferentially surround said distal portions of said second plurality of piston elements, said second drum plate being adapted to rotate around a third axis in angled relation to said first axis;

a first curved surface support element operatively engaging said first drum plate, said first curved surface support element being mounted in sliding relation along a first rotatable shaft structure between said rotor and said first drum plate;

a second curved surface support element operatively engaging said second drum plate, said second curved surface support element being mounted in sliding relation along a second rotatable shaft structure between said rotor and said second drum plate;

at least one biasing element disposed between said rotor and said first curved surface support element urging said first curved surface support element and said first drum plate away from said rotor; and

at least one biasing element disposed between said rotor and said second curved surface support element urging said second curved surface support element and said second drum plate away from said rotor.

13. The pump assembly as recited in claim 12, wherein said first curved surface support element is non-integral with said first rotatable shaft structure and said second curved surface support element is non-integral with said second rotatable shaft structure.

14. The pump assembly as recited in claim 13, wherein said first curved surface support element is disposed circumferentially around said first rotatable shaft structure and said second curved surface support element is disposed circumferentially around said second rotatable shaft structure, said first curved surface support element being held in non-rotatable relation relative to said first rotatable shaft structure such that rotation of said first rotatable shaft structure is translated to said first curved surface support element, and said second curved surface support element being held in non-rotatable relation relative to said second rotatable shaft structure such that rotation of said second rotatable shaft structure is translated to said second curved surface support element.

15. The pump assembly as recited in claim 14, wherein said first curved surface support element includes a first convex exterior surface portion having at least one detent projecting radially away from said first convex exterior surface portion, said at least one detent being integral with said first convex exterior surface portion and adapted to operatively engage said first drum plate such that rotation of said first rotatable shaft structure is translated to said first drum plate, said second curved surface support element including a second convex exterior surface portion having at least one detent projecting radially away from said second convex exterior surface portion, said at least one detent being integral with said second convex exterior surface portion and adapted to operatively engage said second drum plate such that rotation of said second rotatable shaft structure is translated to said second drum plate.

16. The pump assembly as recited in claim 14, wherein said first curved surface support element includes a first interior portion adapted to engage a cooperating splined surface of said first rotatable shaft structure and wherein said second curved surface support element includes a second interior portion adapted to engage a cooperating splined surface of said second rotatable shaft structure.

17. A method of constructing a pump assembly, the method comprising the steps of:

providing a rotor supporting a plurality of outwardly projecting piston elements;

providing at least one drum plate supporting a plurality of outwardly projecting cup elements;

orienting said rotor in angled relation relative to said at least one drum plate such that said cup elements mateably engage distal portions of corresponding piston elements and said cup elements circumferentially surround distal portions of said piston elements and such that said rotor is rotatable around a first axis and said drum plate is rotatable around a second axis in angled relation to said first axis;

providing a curved surface support element operatively engaging said at least one drum plate, said curved surface support element being mounted in sliding relation along a rotatable shaft structure; and

providing at least one biasing element between said rotor and said curved surface support element urging said curved surface support element and said at least one drum plate away from said rotor.

18. The method of constructing a pump assembly as recited in claim 17, wherein said curved surface support element is non-integral with said rotatable shaft structure.

19. The method of constructing a pump assembly as recited in claim 18, wherein said curved surface support element is mounted circumferentially around said rotatable shaft structure, said curved surface support element being held in non-rotatable relation relative to said rotatable shaft structure such that rotation of said rotatable shaft structure is translated to said curved surface support element.

20. The method of constructing a pump assembly as recited in claim 18, wherein said curved surface support element includes an interior portion engaging a cooperating splined surface of said rotatable shaft structure.