AU2005203515B2 - A drive wheel assembly - Google Patents

Abstract

A DRIVE WHEEL ASSEMBLY Abstract A drive wheel assembly (10) for attachment to the frame (11) of a hospital bed. The wheel assembly (10) being operable to aid a user in moving a hospital bed. The drive 5 wheel assembly (10) includes a driven wheel (12) that is movable between a lowered (drive) position and a raised position. In the lowered position, the wheel (12) is urged into contact with the floor surface (36). '33-0 39'3

Description

S&F Ref: 727459 AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name and Address Medicraft Australia Pty. Limited, of Applicant: an Australian company, ACN 003 109 939, of 72-84 Shepherd Street, Marrickville, New South Wales, 2204, Australia Actual Inventor(s): Peter Giesser Ric Buckley Otton Address for Service: Spruson & Ferguson St Martins Tower Level 35 31 Market Street Sydney NSW 2000 (CCN 3710000177) Invention Title: A drive wheel assembly Associated Provisional Application Details: [33] Country: [31] Appl'n No(s): [32] Application Date: AU 2004904526 10 Aug 2004 The following statement is a full description of this invention, including the best method of performing it known to me/us:- -1 A DRIVE WHEEL ASSEMBLY Technical Field The present invention relates to drive wheel assemblies and more particularly but not exclusively to drive wheel assemblies for attachment to hospital beds to aid in their 5 movement. Background of the Invention Typically hospital beds are provided with wheels and are moved by hospital staff pushing the beds. Frequently to move the bed two hospital staff are required since it is difficult to push and steer the bed at the same time. Still further, considerable effort is to required to propel a hospital bed. The above problem has been addressed by providing some hospital beds with a motor driven wheel. These assemblies are fixed to the bed frame with the wheel in permanent engagement with the floor. These assemblies are reasonably expensive. Object of the Invention 15 It is the object of the present invention to overcome or substantially ameliorate at least one of the above disadvantages. Summary of the Invention There is disclosed herein a drive wheel assembly to be attached to an object, having wheels that support the object on a floor surface, to at least aid in moving the 20 object over the floor surface, said assembly including: a frame to be fixed to the object; a motor attached to the frame; and a wheel operatively associated with the motor and movably mounted on the frame for movement between a retracted position at which the wheel is intended to be 25 clear of the floor surface, and a lowered drive position at which the wheel is intended to engage the floor surface so that upon operation of the motor the wheel assembly at least aids in causing movement of the object over the floor surface, wherein said wheel is driven in a first angular direction, said angular direction being a driving direction, and wherein driving rotation of said wheel in said angular 30 direction urges the wheel into contact with said surface while permitting movement of the wheel in a direction towards said retracted position.

-2 Preferably, said assembly includes a base rotatably supporting the wheel and upon which the motor is mounted, the base being movable relative to the frame to move the motor between the raised and lowered positions thereof. Preferably, said wheel rotates about a rotational axis, and said base is pivotally 5 attached to said frame for angular movement about a pivot axis generally parallel to said rotational axis. Preferably, said base is pivotally attached to said frame by a bracket extending from said pivot axis, which bracket is also pivotally attached to said base for angular movement about a bracket axis, which bracket axis is generally parallel to said pivot axis. 10 Preferably, said base is supported on said frame by a second bracket, said second bracket being pivotally attached to said base for angular movement relative thereto about a second bracket axis, which second axis is parallel to said pivot axis. Preferably, said second bracket is operatively associated with said first bracket so as to be movably guided thereby as said base is moved between the raised and lowered is positions. Preferably, said base is maintained generally horizontal during movement thereof between the raised and lowered positions. Preferably, a force applying member is operatively associated with the frame and said base to urge the base when raised in the raised position and to urge the base when 20 lowered to the lowered position. Preferably, the force applying member is a gas-strut. Brief Description of the Drawings A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings wherein: 25 Figure 1 is a schematic side elevation of a drive wheel assembly for attachment to a hospital bed; Figure 2 is a schematic side elevation of the wheel assembly of Figure 1: Figure 3 is a further schematic side elevation of the wheel assembly of Figure 1; Figure 4 is a schematic isometric view of the wheel assembly of Figure 1; 30 Figure 5 is a further schematic isometric view of the wheel assembly of Figure 1; and -3 Figure 6 is a still further schematic isometric view of the wheel assembly of Figure 1. Detailed Description of the Preferred Embodiment In the accompanying drawings there is schematically depicted a drive wheel 5 assembly 10 for attachment to the frame 11 of a hospital bed, the wheel assembly 10 being operable to aid a user in moving the hospital bed having the frame 11. The drive wheel assembly 10 includes a driven wheel 12 that is movable between a lowered (drive) position as seen in Figure 2 and a raised (inoperative) position as shown in (Figure.3). In the lowered position the wheel 12 is driven to aid a user in moving the bed having the 10 frame 11. The wheel assembly 10 includes a mounting frame 13 that is secured to the bed frame 11 by releasable fasteners, such as clamps so that the wheel assembly 10 may be attached and removed with respect to the bed frame 11. The frame 13 includes a pair of side rails 14 that are of an "L" configuration in transverse cross section so as to be is engaged with the beams 15 of the frame 11. Typically the rails 14 would be secured to the beams 15 by clamps or other means. Extending downwardly from the rails 14 are flanges 16 that are generally vertically oriented. The mounting frame 13 includes the rails 14, flanges 16 as well as transverse brace members 17 that aid in retaining the flanges 16 in a transversely spaced 20 generally parallel and co-extensive relationship. The wheel 12 is mounted on a base 18, which base 18 is supported by a first pair of elongated brackets 19 as well as a second pair of elongated brackets 20. The brackets 19 and 20 are pivotally attached to the base 18 for pivoting movement relative thereto about parallel generally horizontal axes 21 and 22. More particularly, each of the 25 brackets 20 has lower extremity pivotally attached to the base 18 and an upper extremity attached to a sleeve 23 pivotally supported on a shaft 24. The sleeve 23 is pivotable about a generally horizontal axis 25. The brackets 19 extend upwardly from the base 18 and have fixed to their upper extremity a plate 26. Rotatably mounted on each plate 26 is a pair of rollers 27 that 30 engage an associated one of the brackets 20 so as to move therealong. Accordingly the rollers 27 are guided in their movement by rolling contact with the associated bracket 20. This arrangement of the brackets 19 and 20 by guiding contact of the rollers 27 with a -4 bracket 20 maintains the base 18 in a generally horizontal orientation during raising and lowering thereof. Pivotally mounted on each flange 16 is a plate 28 to which there is attached or through which there projects a shaft 29. Pivotally attached to each shaft 29 and extending 5 therefrom is a "gas-strut" 30 that has a piston rod extremity pivotally attached to the adjacent plate 26, such as a supporting axle for one of the rollers 27. Each gas-strut 30 is biased to extend so as to apply a force to its associated plate 26, the force being radial from the associated shaft 29. The gas-strut 30 acts to urge the base 18 to the lowered position however upon 10 the base 18 being raised passed a predetermined raised position the gas-strut 30 then urges the base 18 to the raised position. As the base 18 is raised and lowered each plate 26 pivots angularly about its respective shaft 29 so that in the raised position of the base 18 the gas-struts 30 are oriented generally vertical and therefore act to retain the base 18 in the raised position. When in the lowered position, upward movement of the base 18 15 will occur if an obstacle is encountered. However the wheel 12 will remain in contact with the floor surface 36 due to the strut 30. This is due to the configuration of the brackets 19 and 20. Mounted on the base 18 via a driven axle 31 is the wheel 12. The axle 31 is rotatably supported in bearing blocks 32, with the axle 31 extending to a gear box 33 20 driven by a motor 34. The gear box 33 and motor 34 are also mounted on the base 18. The motor 34 is -an electric motor from which there extends a cable 35 to a hand held controller associated with a carrier containing batteries. A user would operate the hand controller to deliver electric current to the motor 34 from the batteries so that the wheel 12 is caused to rotate and therefore cause movement of the hospital bed frame 11. 25 Typically the controller would deliver electric power to the motor 13 so as to provide for smooth operation. The wheel 12, when engaged with a floor surface 36 over which the hospital bed is to be moved, applies a force to the surface 36 in the direction of the arrow 37 to cause the assembly 10 to move in the direction of the arrow 38. Accordingly there is a force 30 applied to the base 18 (via the axle 31) in the direction of the arrow 39, which force is below the pivot axis 25. Thus the base 18 is urged to pivot downward about the axis 25. Accordingly when a driving force is being provided by the wheel 12, the wheel 12 is urged into contact with the floor surface 36.

-5 To move the base 18 between the raised and lowered positions thereof, there is provided a lever 40 attached to an associated one of the shafts 29, which shaft 29 is attached to its associated plate 28. Angular movement of the handle 40 in the direction of the arrow 41 causes pivoting of the associated plate 28 and therefore the associated gas 5 strut 30. As the associated gas-strut 30 is attached to an associated bracket 19, the base 18 is caused to move upward when the handle 40 is move angularly. Accordingly by a user moving the handle 40, the wheel 12 is moved between a lowered position engaging the floor surface 36, and a raised position clear of the surface 36. The above described preferred embodiment has a number of advantages 10 including being installable in existing beds, has enhanced contact with the surface 36 as the wheel 12 is urged downward when driving, and can negotiate irregularities in the surface 36 by upward movement of the base 18 toward the raised position. A still further advantage is that the wheel in the raised position allows other equipment to be positioned under the bed while the assembly 10 is specifically designed to occupy minimum space is within an existing hospital bed frame. Preferably a battery carrier would be removably attachable to the hospital frame 11, with the hand controller removably attached to the battery carrier, and the carrier removably attached to the cable 35. Preferably the motor 34 would operate on 24 volts, with the voltage provided by 20 the batteries mounted in the above mentioned carrier. A cover 39 is placed over the base 18 to enclose the motor 34, gear box 33 and the majority of the wheel 12. In Figures 5 and 6 the cover 39 is removed.

Claims (9)

1. A drive wheel assembly to be attached to an object, having wheels that support the object on a floor surface, to at least aid in moving the object over the floor surface, said assembly including: 5 a frame to be fixed to the object; a motor attached to the frame; and a wheel operatively associated with the motor and movably mounted on the frame for movement between a retracted position at which the wheel is intended to be clear of the floor surface, and a lowered drive position at which the wheel is intended to 1o engage the floor surface so that upon operation of the motor the wheel assembly at least aids in causing movement of the object over the floor surface, wherein said wheel is driven in a first angular direction, said angular direction being a driving direction, and wherein driving rotation of said wheel in said angular direction urges the wheel into contact with said surface while permitting movement of the is wheel in a direction towards said retracted position.

2. The assembly of claim 1, wherein said assembly includes a base rotatably supporting the wheel and upon which the motor is mounted, the base being movable relative to the frame to move the motor between the raised and lowered positions thereof. 20

3. The assembly of claim 2, wherein said wheel rotates about a rotational axis, and said base is pivotally attached to said frame for angular movement about a pivot axis generally parallel to said rotational axis.

4. The assembly of claim 3, wherein said base is pivotally attached to said frame by a bracket extending from said pivot axis, which bracket is also pivotally 25 attached to said base for angular movement about a bracket axis, which bracket axis is generally parallel to said pivot axis.

5. The assembly of claim 4, wherein said base is supported on said frame by a second bracket, said second bracket being pivotally attached to said base for angular movement relative thereto about a second bracket axis, which second axis is parallel to 30 said pivot axis.

6. The assembly of claim 5, wherein said second bracket is operatively associated with said first bracket so as to be movably guided thereby as said base is moved between the raised and lowered positions. -7

7. The assembly of any one of claims I to 6, said base is maintained generally horizontal during movement thereof between the raised and lowered positions.

8. The assembly of any one of claims 2 to 6, wherein a force applying member is operatively associated with the frame and said base to urge the base when s raised in the raised position and to urge the base when lowered to the lowered position.

9. The assembly of claim 8, wherein the force applying member is a gas strut. Dated 24 August, 2011 Medicraft Australia Pty Limited to Patent Attorneys for the Applicant/Nominated Person SPRUSON & FERGUSON