PUMPS

Abstract: A pump (10) comprises a hollow cylindrical body (12) open at one end. A central hole (14) is provided through the closed end of the body (12) with a perimeter wall (16) around the hole (14) of the same height as the boundary wall (18) of the body (12). A left hand thread (22) is provided around the wall (16) and a right hand thread (24) is provided on the inside face of the wall (18). First and second components (26, 38) are provided rotatably mounted respectively on the threads (24 and 22). The components (26, 38) comprise a planar base (28, 40) with upstanding blades (36, 42) thereon. The blades (36) on the first component (26) are orientated for pumping when the rotor turns in one direction and the blades (40) on the second component (38) are orientated for pumping in the same direction when the rotor turns in the opposite direction. The first component (26) is provided with an opening (30) through which the second component (38) can slidably pass in an axial direction such that rotation of one of the components (26, 38) causes rotation of the other component, with one component rising relative to the body to an operative position with the blades thereon extending above the body for pumping when the rotor turns in one direction and the other component descending into the body, and vice versa.

Description: P umps This invention concerns improvements in or relating to pumps and particularly but not exclusively reversible centrifugal pumps wherein material is pumped in the same direction irrespective of the direction of rotation of the rotor . Previously reversible pumps have been proposed incorporating blades pivotally mounted on the rotor and movable between first and second positions for respective directions of rotation of the rotor. Such pumps tend not to be wholly efficient as the blade≤ cannot have the optimum shape and/or positioning for pumping in both directions of rotation. According to the present invention there is provided a pump comprising a rotor, a first blade assembly for pumping when the rotor turns in a first direction, and a second blade assembly for pumping in the same direction but when the rotor turns in the opposite direction, each assembly being movable between an operative position extending from the rotor and an inoperative position located within the rotor. The pump may be constructed such that when one blade assembly is in the operative position the other assembly will be in the inoperative position, and when said one assembly is moved towards the inoperative position said other assembly will be moved towards the operative position. The pump may also be constructed such that rotation of the rotor causes the blade assemblies to be urged to provide the respective blade assembly in the operative position and the other assembly in the inoperative position, and a change in direction of rotation will cause the other blade assembly to be urged to the operative position. Means may be provided for damping the movement of the blade assemblies upon approaching the operative and/or inoperative position(s). The first blade assembly may engage with the rotor by a first thread and the second assembly may engage with the rotor by a second opposite handed thread. The first blade assembly may be engagable with the second assembly, such that rotation of one assembly relative to the rotor causes rotation of the other assembly, whereby, when one assembly rises relative to the rotor, the other assembly falls, and vice versa. The first thread may be provided towards the - ~ - periphery of the rotor and the second thread may be provided towards the centre of the rotor. The first and second threads are preferably coaxial. Each blade assembly may comprise a base with a plurality of blade members upstanding therefrom. The second blade assembly preferably slidably fits through the first set in an axial direction. The assemblies may be constructed such that all the blade members locate on a common circle coaxial with the threads. An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:- Fig. 1 is a partially disassembled plan view of a pump according to the invention; Fig. 2 is a diagrammatic plan view of a first component of the pump of fig. 1; Fig. 3 is a sectional view along the line A - A of fig. 2; Fig. 4 is a diagrammatic plan view of a second component of the pump of fig. 1; Fig. 5 is a sectional view along the line B - B of fig. 4; Fig. 6 is a diagrammatic plan view of a cover for the pump of fig. 1; and Fig. 7 is a sectional view along the line C - C of fig. 6. The drawings show a reversible centrifugal pump 10 suitable for use in a robotic swimming pool cleaner. The pump 10 comprises a hollow cylindrical body 12 open at one end. A central hole 14 is provided through the closed end of the body 12. A perimeter wall 16 of the same height as the boundary wall 18 of the body is provided around the hole 14. A sleeve 20 with a left hand thread 22 around its perimeter is mounted around the wall 16. A right hand thread 24 of a similar pitch to the thread 22 is provided on the inside face of the wall 18. A first component 26 is rotatably mounted on the thread 24. The component 26 comprises a planar base 28 with a central shaped opening 30. The opening 30 comprises six equiangular portions, three 32 of a larger diameter interspaced between three 34 of a smaller diameter 34, thereby defining a circular opening with three equispaced recesses 32 extending radially therefrom. An upstanding blade 36 is provided on each portion of the base 28 extending between the recesses 32. The blades 36 are shaped and orientated for optimum pumping when rotated in an anticlockwise direction. A second component 38 is rotatably mounted on the thread 22. The component 38 comprises an annular planar base 40. The base 40 is similarly shaped to the opening 30 and is of a size to slidingly fit therethrough in an axial direction. A similar upstanding blade 42 is provided on each portion of the base 40 corresponding to the recesses 32. The blades 42 are shaped and orientated to provide optimum pumping when rotated in a clockwise direction. The pump 10 also comprises a freely rotatable cover 44 with a central opening 46 the surrounds of which are raised on the upper side of the cover 44. Six openings 48 (only two of which are shown in Fig. 6) are provided in the cover 46 corresponding respectively in position to the blades 36 and 42 and being of a size to permit the respective blade 36,42 to slidably pass therethrough. The components of the pump 10 may be made for example from a plastics material. In use, the pump 10 is mounted on a spindle (not shown) within a suitable casing (also not shown). The pump 10 is operable by rotation of the spindle by the drive motor of the cleaner. When the spindle is driven in a clockwise direction the first component 26 will be urged in an anticlockwise direction up the thread 24 until it reaches the underside of the cover 44. In this condition the blades 36 will extend through the respective openings 48 to pump the fluid, which in this case will be water. Rotation of the component 26 causes rotation of the second component 38 on the thread 22. As the thread 22 is opposite handed to the thread 24 as the blades 36 extend from the body the component 38 will retract within the body 12 until the blades 42 do not extend at all through the openings 48. Upon a change in direction of rotation of the spindle to anticlockwise, caused for example when the cleaner changes its direction of movement, the flow of water will urge the blades 36 and hence component 26 in a clockwise direction, and hence into the body 12. The component 38 will therefore be moved upwardly by rotation of the component 26 such that the pumping action will become provided by the blades 42. There is thus provided a pump which provides an automatic change of blades upon the direction of the rotor being reversed whereby optimum pumping in the same direction can be attained by virtue of the orientation, shape and positioning of the blades. The apparatus is of relatively simple construction and can thus be inexpensively and robustly manufactured, and can run essentially maintenance free. Various modifications may be made without departing from the scope of the invention. For example, the components of the pump may be made of a different material. A different configuration of blades could be provided and obviously curved blades may be used. The shape of the first and second components could be different. Means could be provided for damping between the components and the rotor at extreme raised or lowered positions. Such means could comprise an abutment entering a tapering opening. The motor could be provided with a slow turnaround such that upon a change in direction the components are moved relatively slowly with respect to the rotor. One or more abutments may be provided on the closed end of the body to prevent further downward rotational movement of either the first or second component before the end of the respective thread is reached. Such abutments would prevent locking at the end of the threads or damage thereto. A steep thread may be used such that respective raising or lowering of the components occurs within a single revolution. In such an instance it would be preferable to provide a four start thread. Other methods of raising and lowering the sets of blades could be provided. For example, a cam member could be provided urging one set of blades upwardly in one direction of rotation and the other set when rotated in the other direction. Pivotted levers may also be used such that rotation in one direction causes pivotting to raise one set of blades and rotation in the other direction causes pivotting of the same or a further set of levers to raise the other set of blades. Obviously pumps of this type can be used in many applications other than just swimming pool cleaners.

Claims: C l aims 1. A pump comprising a rotor (10), characterised in that the pump (10) also comprises a first blade assembly (26) for pumping when the rotor (10) turns in a first direction, and a second blade assembly (38) for pumping in the same direction when the rotor (10) turns in the opposite direction, each assembly (26, 38) being movable between an operative position extending from the rotor (10) and an inoperative position located within the rotor (10). 2. A pump according to Claim 1, characterised in that the pump (10) is constructed such that when one blade assembly (26, 38) is in the operative position the other assembly (26, 38) will be in the inoperative position, and when said one assembly (26, 38) is moved towards the inoperative position said other assembly (26, 38) will be moved towards the operative position. 3. A pump according to Claim 2, characterised in that the pump (10) is constructed such that rotation of the rotor (10) causes the blade assemblies (26, 38) to be urged to provide the respective blade assembly (26, 38) in the operative position and the other assembly (26, 38) in the inoperative position, and a change in direction of rotation will cause the other blade assembly (26, 38) to be urged to the operative position. 4. A pump according to Claim 3, characterised in that the first blade assembly (26) engages with the rotor (10) by a first thread (24) and the second assembly (38) engages with the rotor by a second opposite handed thread (22). 5. A pump according to Claim 4, characterised in that the first blade assembly (26) is engagable with the second assembly (38), such that rotation of one assembly (26, 38) relative to the rotor (10) causes rotation of the other assembly (26, 38), whereby, when one assembly (26, 38) rises relative to the rotor (10), the other assembly (26, 38) falls, and vice versa. 6. A pump according to Claims 4 or 5, characterised in that the first thread (24) is provided towards the periphery of the rotor (10) and the second thread (22) is provided towards the centre of the rotor (10). 7. A pump according to Claim 6, characterised in that the first and second threads (24, 22) are coaxial. 8. A pump according to any of the preceding Claims, characterised in that each blade assembly (26, 38) comprises a base (28, 40) with a plurality of blade members (36, 42) upstanding therefrom. 9. A pump according to Claim 8, when dependent on Claim 7, characterised in that the assemblies (26, 38) are constructed such that all the blade members (36, 42) locate on a common circle coaxial with the threads (24, 22). 10. A pump according to any of the preceding Claims, characterised in that the second blade assembly (38) slidably fits through the first assembly (26) in an axial direction. 11. A pump according to any of the preceding claims, characterised in that means is provided for damping the movement of the blade assemblies (26, 38) upon approach¬ ing the operative and/or inoperative position(s).

Inventors: BOOTH RAYMOND IVOR, BOOTH, RAYMOND, IVOR
Applicants: COMPONENTA INTERNATIONAL LIMIT, COMPONENTA INTERNATIONAL LIMITED
Application year: 1991
Main classification: F04D15
IPC codes: F04D15, F04D29