WO1997035482A1

WO1997035482A1 - A drive element and an articulated drive incorporating same

Info

Publication number: WO1997035482A1
Application number: PCT/AU1997/000193
Authority: WO
Inventors: George Mazak
Original assignee: Faircrest Holdings Pty. Ltd.
Priority date: 1996-03-25
Filing date: 1997-03-25
Publication date: 1997-10-02

Abstract

A drive element (14) in the form of a sphere is machined so as to be provided with a slot (20) on one side and a projection (22) on an opposite side. The slot (20) and projection (22) are disposed in mutually orthogonal planes. An articulated drive (10) can be formed by arranging a plurality of elements (14) along a drive line, with the slots (20) and projections (22) of adjacent elements (14) intermeshing. This intermeshing allows a relative sliding motion between adjacent elements (14). The drive (10) also includes a tube for rotatably constraining the elements (14). The articulated drive (10) can be formed with one or more curves. The elements (14) allow torque to be transferred along a curved drive line because they are able to slide relative to each other as they rotate, there being no mechanical fixing between adjacent elements (14).

Description

Title A DRIVE ELEMENT AND AN ARTICULATED DRIVE INCORPORATING SAME

Field of the Invention

The present invention relates to a drive element and an articulated drive incorporating a plurality of drive elements for transmitting torque along a straight or curved drive line in both clockwise and anticlockwise directions.

Background of the Invention

Transmitting torque between two points in a straight line and in opposite directions (ie. clockwise and anticlockwise) is a very common, and mechanically, very simple thing to do. This is most commonly achieved by coupling a rigid shaft between the two points in question or, if a step up or step down in speed is required, a gear box can also be incorporated. Such torque transmission systems comprising rigid shafts and gear boxes are commonly used in motor vehicles, power tools, household appliances etc.

However, when it is required to transmit torque between two points which are angularly off-set from each other or lie along a curved or bent line, the mechanical system required may be somewhat more complex. Typically one may use rigid shafts provided with meshing bevelled gears so as to provide the required change in direction. Each change in direction will require at least two further bevel gears.

As will be appreciated, the use of bevelled gears or other types of gears generally also requires the use of a gear box, bearings, mountings and support brackets etc. All of this requires considerable space which, in some types of machinery is not readily available. Further, use of such a transmission system can have the undesirable effect of adding substantial weight. An alternate method of transmitting torque between two points along a curved or bent line is by means of universal joints coupled between adjacent rigid shafts. In this instance, the rigid shafts must be supported. Also, there is a limit to the change in direction that can be obtained by the use of each universal joint.

In yet a further alternative, it is known to use a flexible cable housed within a flexible casing to transmit torque between two points lying along a curved path. The cable used in such systems comprises a number of twisted strands. As a result, torque can be transmitted in one direction only that being the direction of the twist of the strands. If torque is transmitted in the opposite direction, the strands unravel rendering the cable inoperable. Cables with strands twisted in opposed directions are also known, however such cables have limited torque transfer characteristics, and under heavy loads still tend to unravel .

Summary of the Invention It is an object of the present invention to provide a drive element and an articulated drive comprising a plurality of such elements for transmitting torque in both a clockwise and anticlockwise direction which attempts to overcome the above-mentioned disadvantages in the prior art.

According to a first aspect of the present invention there is provided an articulated drive for transmitting torque along a drive line in both clockwise and anticlockwise directions, said articulated drive comprising a plurality of intermeshing drive elements disposed along said drive line, said elements being rotatable about said drive line and intermeshing in such a manner that adjacent elements can slide relative to each other so that when any of the elements are disposed along a curve formed in said drive line those elements remain intermeshed and slide relative to each other when torque is imparted to the drive.

Preferably each element comprises first and second meshing means which are relatively disposed so that the first meshing means of any one element can mesh with a second meshing means of a first adjacent element and the second meshing means of said one element can mesh with a first meshing means of a second adjacent element.

Preferably each of said first and second meshing means comprises any one of two mutually complementary first and second structures wherein the second meshing means of the first adjacent element is in the form of the structure complementary to the structure of the first meshing means of said one element, and the first meshing means of the second adjacent element is in the form of the structure complementary to the structure of the second meshing means of said one element.

Preferably both the first and second meshing means of said one element are either in the form of said first structure or said second structure and both the first and second meshing means of the first and second adjacent elements are in the form of the other of the first structure or the second structure.

In an alternate embodiment, the first meshing means of each element is in the form of said first structure and the second meshing means of each element is in the form of said second structure.

Preferably said first structure is in the form of a slot and said second structure is in the form of a projection. Preferably said elements comprise a set of sphere or ball like elements for disposition about said curve in said drive line.

Preferably said elements further comprise a set of elongated elements for disposition along a straight length of said drive line.

Preferably said articulated drive further comprises a tube for rotatably housing said elements.

Preferably said tube is a rigid tube and made to the shape of said drive line.

In an alternate embodiment, said tube is flexible so as to be able to conform to a plurality of different shaped drive lines .

Preferably said tube is further provided with means at one or both ends for controlling the degree of intermeshing between adjacent elements.

In yet a further alternative, said articulated drive further comprises a flexible line threaded through each of said elements so as to retain respective adjacent elements in intermeshing relationship and whereby said drive line can be formed to one of a plurality of different curves or configurations .

Preferably said housing is provided with a coupling at one end for coupling said articulated drive to a torque source or an apparatus to which torque is to be delivered, said coupling rotatably coupled to said housing and adapted to mesh with the element immediately adjacent that one end of the housing. According to another aspect of the present invention there is provided a drive element for transmitting torque between a torque input means and a torque output means, said element provided with a first meshing means for meshing with said torque input means and a second meshing means for meshing with said torque output means said first and second meshing means configured to allow said element to slide relative to said torque input means and to slide relative to said torque output means, whereby, in use, when said element, torque input means and torque output means are restrained to rotate about a curved drive line along which said element, torque input means and torque output means are disposed, said drive element slides relative to both said torque input means and said torque output means as torque is sequentially transferred in either clockwise or anticlockwise directions from said torque input means through said element to said torque output means .

Preferably said first meshing means is one of a slot and a projection formed on one side of said element for meshing with the other of a slot and a projection formed on said torque input means.

Preferably said second meshing means is one of a slot and a projection formed on an opposite side of said element for meshing with the other of a slot and a projection formed on said torque output means.

Preferably said first and second meshing means both comprise a slot or a projection.

In an alternate form, it is preferred that said first meshing means is one of a slot and a projection and the second meshing means is the other of a slot and a projection. Preferably said first and second meshing means are disposed in mutually orthogonal planes .

Brief Description of the Drawings

Embodiments of the present invention will now be described by way of example only, with reference to the accompanying drawings in which:

Figure 1 is an isometric view of a length of the first embodiment of the articulated drive extending along a curved drive line;

Figure 2 is an enlarged top view of the articulated drive shown in Figure 1;

Figure 3 is a photograph of the articulated drive of Figures 1 and 2 within a tubular housing;

Figure 4 is an isometric view of a second embodiment of the articulated drive extending along a drive line having two curves in perpendicular planes; and,

Figure 5 is a representation of a third embodiment of an articulated drive comprising a single drive element.

Detailed Description of Preferred Embodiments As shown in the accompanying drawings with particular reference to Figures 1 and 2 an articulated drive 10 for transmitting torque along a drive line 12 in both clockwise and anti-clockwise directions comprises a plurality of intermeshing drive elements 14 (hereinafter simply referred to as "elements") disposed along the drive line 12. The elements 14 are rotatable about the drive line 12. In this regard, when the drive line is straight or includes a straight length, the rotation axes are coaxial with the drive line. The elements 14 intermesh with one another in such a manner that adjacent elements 14, can slide relative to each other so 'that when any elements are disposed along a curve formed in the drive line 12, such as elements 14A, 14B and 14C, the elements remain intermeshed and slide relative to each other when torque is imparted to the drive. As will be explained in greater detail below, in this embodiment the relative sliding of adjacent elements 14 along a curved part of the drive line 12 is manifested in relative oscillatory motion.

Each element 14 comprises a first meshing means 16 and a second meshing means 18. The meshing means 16 and 18 of each element 14 are arranged so as to mesh with the meshing means of opposite adjacent elements 14. For example, referring to element 14A, it can be seen that the meshing means 16A of that element meshes with the second meshing means 18B of adjacent element 14B and that the second meshing means 18A of element 14A meshes with the first meshing means 16C of opposite adjacent element 14C.

The meshing means 16 and 18 can be any one of two complementary structures such as a slot 20 or a projection 22. In this embodiment, the first meshing means 16 of each element 14 is in the form of a projection 22 and the second meshing means 18 of each element 14 is in the form of the slot 20. Further, the slot 20 and projection 22 of each element 14 are disposed in mutually perpendicular planes.

However, in an alternate embodiment (not shown) , both meshing means 16 and 18 of one element can be of the same structure provided that the first and second meshing means of an adjacent element is of the opposite structure. For example, in the element 14A, the second meshing means 18 can be varied from the slot 20 to a projection 22. In this event, the first meshing means 16C and 16B of elements 14C and 14B would be in the form of slots 20. Thus, in this variation the drive 10 is made up of alternating elements 14 having two slots 20 and two projections 22. Referring to .Figure 3, it can be seen that the elements 14 can be housed in a tube 24. In this case, the tube 24 is a length of bent steel piping. For illustrative purposes, a length of the tube 24 has been cut away. The tube 24 is configured to the shape of the drive line 12. As the elements 14 are held within the tube 24 their respective axes of rotation are fixed. Along curved parts of the drive line 12 the axes of rotation of the elements 14 are thought to be tangential to the drive line 12. Thus, referring to Figure 2, element 14A always rotates about axis 26A when torque is imparted to the drive 10. Similarly, elements 14B and 14C rotate about respective axes 26B and 26C.

As previously mentioned, the instantaneous axes of rotation 26 are tangential to the drive line 12. Therefore, when torque is imparted to the drive 10 and the elements 14 disposed along a curve in the drive line 12 rotate about their axes, and also slide relative to each other. For example, with reference to Figure 2, as element 14A rotates about its axis 26A, the projection 22A will slide along the length of the slot 20B of element 14B. Similarly, projection 22C of element 14C will slide along the slot 20A of element 14A. As the sliding motion continues throughout a complete revolution of any element along a curved portion of the drive line 12, that element in effect oscillates with respect to its adjacent element. It is believed that the oscillatory or sliding motion is in a plane perpendicular to the plane containing the axis of rotation of the element in question.

With elements 14 along a straight portion of the drive line 12, as their respective axes are co-linear with the drive line 12, there will be no sliding motion in the plane perpendicular to that containing the axes of rotation. In order to impart torque to the drive 10 from a torque source, or alternately to impart torque from the drive 10 to another apparatus, couplings 28 (refer Figures 3 and 4) are provided at opposite ends of the drive 10. The couplings 28 essentially comprise a shaft 30 having a reduced diameter portion 32 at one end and a first or second meshing means 16 or 18, as the case may be, at an opposite end. In Figure 4, the coupling 28 on the right hand side is provided with a projection 22 so as to mesh with the slot 20 of an adjacent element 14 whereas the coupling 28 on the left hand side is provided with a slot 20 to mesh with the projection 22 of the element 14 at that end. By providing the stepped down diameter portion 22 the couplings 28 can be rotatably retained within the tube 24 by a suitable nut 34.

The nut 34 together with an adjustable lock nut 36 in combination can also be used in the drive 10 so as to control the spacing or degree of intermeshing between adjacent elements 14. Thus, by screwing down the nuts 34/36 at opposite ends of the tube 24 the couplings 28 can push the elements 14 into closer engagement thereby increasing the degree of intermeshing.

In the embodiment shown in Figure 4, two different sets of elements 14 and 14' are illustrated. The elements 14 are of identical structure and function to those described with reference to Figures 1 - 3. Thus, these elements 14 are essentially in the form of a sphere which are machined so as to produce the slots 20 and projections 22. These elements are ideally suited for location along curved sections of the drive line 12. However, in straight sections of the drive line 12, elements 14' can replace a plurality of elements 14. The elements 14' essentially are elongated tubes or shafts 38 provided at opposite ends with respective meshing means 16 or 18. Again depending on the application and length of the straight section the meshing means 16 and 18^' can be the same or different at the opposite ends of the shaft 38.

In an alternate embodiment, which is not illustrated, the elements 14/14' can be housed within a longitudinally flexible tube so as to be able to be configured to a plurality of different shaped drive lines 12.

In yet a further embodiment, which is not illustrated, drive 10 can include a flexible line which is threaded through each of the elements 14/14' so as to retain respective adjacent elements in an intermeshing relationship.

Arguably the most basic form of an articulated drive 10' incorporating a single element 14 in accordance with the present invention is shown in Figure 5. In this embodiment, the drive 10' comprises a single element 14 disposed between a torque input means 40 and a torque output means 42. The torque input means 40, element 14 and torque output means 42 are restrained to rotate within a tube 24' . The torque input means 40 is in the form of a shaft provided with a projection or tongue 42 at one end for meshing with the slot 20 in the element 14. A stub axle 44 is formed at the opposite end of the shaft 40 to allow connection with a torque generator such aε for example, an electric drill, electric motor or hydraulic motor. The torque output means 42 is also in the form of a shaft provided at one end with a slot 46 which meshes with the projection 22 of the element 14. An opposite end of the torque output means 42 is also provided with a stub axle 48 for connection with a device or mechanism to be driven. The tube 24' can either be rigid or flexible. The central axis of the tube 24' defines a drive line 50 along which the torque input means 40, element 14 and torque output means 42 are disposed. Moreover, when torque is applied to the stub axle 44, each of the torque input means 40, element 14 arid torque output means 42 rotate about the drive line 50.

It will also be appreciated that when torque is applied to the torque input means 40, this torque is transferred by the element 14 to the torque output means 42. The trans er of torque is effected by the intermeshing of the slot 20 with the projection 42 and the intermeshing of the projection 22 with the slot 46.

In effect, the torque input means 40 acts like a portion of another element 14 which includes a projection 22 and the torque output means 42 acts like a half of another element 14 containing a slot 20.

When tube 24' is made of a flexible material, the degree of curve in the drive line 50 can be varied as can a plane in which the drive line 50 exists. In order to increase the radius of curvature of the drive line 50, all that is required is the addition of further elements 14 between the torque input means 40 and torque output means 42, (and of course the lengthening of the tube 24') . It will be easily seen that the addition of extra elements in effect returns one to the embodiments shown in Figures 1, 2, 3 and 4.

From the embodiments described herein, it will be apparent that the crux or essence of the present invention lies in the form of the element 14 and in particular its ability to intermesh with other like elements 14 in a manner to allow relative sliding between adjacent elements. This facilitates the construction of articulated drives 10, 10' which can transmit torque in both clockwise and anticlockwise directions along a curved path or drive line.

From the above description, it will also be apparent that embodiments of the present invention substantially alleviate the deficiencies in the prior art. In particular, it will be apparent that embodiments of the drive 10 do not incorporate or require gears or gearboxes. Further, the drive 10 is able to deliver torque in both clockwise and anticlockwise directions. Also, the drive 10 can be configured to match the space available within a machine or apparatus for providing torque between two points.

Now that embodiments of the invention have been described in detail it will be apparent to those skilled in the relevant arts that numerous modifications and variations may be made without departing from the basic inventive concepts. For example, in the embodiments, the meshing structures between adjacent elements are in the forms of slots 20 and projections 22. However, it is envisaged that other structures can be used to achieve the same effect. In particular, it is envisaged that the meshing structures, be they slots 20 and projections 22 or otherwise, can be relatively disposed at orientations or planes other than perpendicular to each other as illustrated in the present embodiments. Also, more sophisticated means than a nuts 34/36 can be used for retaining couplings 28 in tube 24 and controlling the degree of intermeshing between adjacent elements 14.

All such modifications and variations together with other modifications and variations as would be apparent to those skilled in the relevant art are deemed to be within the scope of the present invention the nature of which is to be determined from the foregoing description of the appended claims .

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:-

1. An articulated drive for transmitting torque along a drive line in both clockwise and anticlockwise directions, said articulated drive comprising a plurality of intermeshing drive elements disposed along said drive line, said elements being rotatable about said drive line and intermeshing in such a manner that adjacent elements can slide relative to each other so that when any of the elements are disposed along a curve formed in said drive line those elements remain intermeshed and slide relative to each other when torque is imparted to the drive.

2. An articulated drive according to claim 1, wherein each element comprises first and second meshing means which are relatively disposed so that the first meshing means of any one element can mesh with a second meshing means of a first adjacent element and the second meshing means of said one element can mesh with a first meshing means of a second adjacent element.

3. An articulated drive according to claim 2, wherein each of said first and second meshing means comprises any one of two mutually complementary first and second structures wherein the second meshing means of the first adjacent element is in the form of the structure complementary to the structure of the first meshing means of said one element, and the first meshing means of the second adjacent element is in the form of the structure complementary to the structure of the second meshing means of said one element.

4. An articulated drive according to claim 3, wherein both the first and second meshing means of said one element are either in the form of said first structure or said second structure and both the first and second meshing means of the first and second adjacent elements are in the form of the .other of the first structure or the second structure.

5. An articulated drive according to claim 3, wherein the first meshing means of each element is in the form of said first structure and the second meshing means of each element is in the form of said second structure.

6. An articulated drive according to claim 3, wherein said first structure is in the form of a slot and said second structure is in the form of a projection.

7. An articulated drive according to claim 6, wherein said elements comprise a set of spheroid-like elements for disposition about said curve in said drive line.

8. An articulated drive according to claim 7, wherein said elements further comprise a set of elongated elements for disposition along a straight length of said drive line.

9. An articulated drive according to claim 1, further comprising a tube for rotatably housing said elements.

10. An articulated drive according to claim 9, wherein said tube is a rigid tube and made to the shape of said drive line.

11. An articulated drive according to claim 9, wherein said tube is flexible so as to be able to conform to a plurality of different shaped drive lines.

12. An articulated drive according to claim 9, wherein said tube is provided with means at one or both ends for controlling the degree of intermeshing between adjacent elements.

13. A drive element for transmitting torque between a torque input means and a torque output means, said element provided with a first meshing means for meshing with said torque input means and a second meshing means for meshing with said torque output means, said first and second meshing means configured to allow said element to slide relative to said torque input means and to slide relative to said torque output means, whereby, in use, when said element, torque input means and torque output means are restrained to rotate about a curved drive line along which said element, torque input means and torque output means are disposed, said drive element slides relative to both said torque input means and said torque output means as torque is sequentially transferred in either clockwise or anticlockwise directions from said torque input means through said element to said torque output means .

14. An element according to claim 13 , wherein said first meshing means is one of a slot and a projection formed on one side of said element for meshing with the other of a slot and a projection formed on said torque input means .

15. An element according to claim 14, wherein said second meshing means iε one of a slot and a projection formed on an opposite side of said element for meshing with the other of a slot and a projection formed on said torque output means .

16. An element according to claim 13 , wherein said first and second meshing means both comprise a slot or a projection.

17. An element according to claim 13, wherein said first meshing means is one of a slot and a projection and the second meshing means is the other of a slot and a projection.

18. An element according to claim 12, wherein said first and second meshing means are disposed in mutually orthogonal planes .

19. An articulated drive comprising: a plurality of drive elements according to claim 13; torque input means; torque output means; adjacent ones of said plurality of elements intermeshing with each other and disposed between said torque input means and torque output means so that a first one of said elements meshes with said torque input means and a last one of said elements meshes with said torque output means, the intermeshing between adjacent ones of said elements and said torque input means and torque output means being such that said elements can slide relative to each other; and, means for restraining said torque input means, torque output means, and plurality of elements to rotate about a drive line defined by said means and along which each of said torque input means, torque output means, and plurality of elements is disposed; whereby, in use, when said drive line includes a curve, and torque is imparted to said torque input means in either a clockwise or anticlockwise direction, torque can be transmitted from said torque input means to said torque output means by said plurality of elements rotating about said drive line and sliding relative to each other.