WO2005012760A1

WO2005012760A1 - Rotary motion transfer device

Info

Publication number: WO2005012760A1
Application number: PCT/AU2004/000928
Authority: WO
Inventors: Barnes Alan
Original assignee: Barnes Alan
Priority date: 2003-07-25
Filing date: 2004-07-26
Publication date: 2005-02-10
Also published as: AU2004202429A1

Abstract

A rotary motion transfer device having a rotary toothed inner gear with outer teeth (10) and a bearing cage with bearings (14) which both eccentrically rotate around the centre of a fixed ring gear having inner teeth (9). Each tooth (10) on the inner gear is always in contact with a tooth (9) on the ring gear, directly or by a ball bearing (14) separating the teeth (9, 10).

Description

TITLE: ROTARY MOTION TRANSFER DEVICE

Field of the Invention

This invention concerns a rotary inner toothed gear and a bearing cage or housing which both eccentrically rotate around the centre of an outer gear having one or two more teeth than the inner gear. Each tooth on the inner gear is always in contact with an outer tooth on the outer gear, directly or by a ball bearing separating the teeth. Refer Figure l and 2.

Geometry

The geometry of the drive relies on three regular polygons, namely an inner, middle and outer polygon, all having sides of identical length. The middle polygon always being an odd sided polygon, the inner polygon having one less side than the middle polygon and the outer polygon has one more side than the middle polygon. By joining a common side of all three polygons, the three centre points of the drive can be found. The displacement points of the centers, allow eccentric motion for the inner gear and ball bearings, based on the displacement from the centre of the outer gear.

The middle polygon marks the intersecting points of the gears teeth from which the shape of the teeth are created. Refer Figure 3. The shape of the inner teeth is created from rotating the reference points of the middle polygon around the centre of the outer polygon, through an angle dictated by the number of sides of the outer polygon divided into 360 and then multiplied by the number of sides from the drawn tooth From these reference points a parabolic curve of the inner teeth is drawn.

The shape of the outer teeth is created from rotating the reference points of the middle polygon around the centre of the inner polygon, through an angle dictated by the number of sides of the inner polygon divided into 360 and then multiplied by the number of sides from the drawn toolh. From these reference points a parabolic curve of the outer teeth is drawn.

Any number of reference points alone the parabolic curve of the teeth can be plotted using the same general formula as described. The diameter of bearings between the teeth can be any size up to the common length of the side of the polygons. The centre of the bearings is always the comer of the middle polygon.

For explanation purposes, consider the distance between the inner and outer polygons centers to be equal to one.

The teeth profile is offset from the comers of the middle polygon an equal distance to accommodate the bearing. Refer Figure 4. If the teeth are offset by a distance of approximately 0.791 (depending on the accuracy on the drawn tooth), the length of the inner, and outer teeth parabolas will be the same. Refer Figure 5.

If the offset distance is one or greater, the inner and outer teeth are able to pass over each other and therefore twice the number of teeth can be used in the gear. This does not change the gear ratio of the gear. Refer Figure 8 and 9. The bearing positions can be maintained by the eccentric drive, using the middle polygons centre point, as in Figure 1 and 2 or by a bearing cage Figure 11. Another is through magnetization or static electricity of either the inner and outer gears or the bearings. Gear Ratio

The gear ratio of the device is based on the number of sides of the inner polygon divided by two. For example: Figures 1 and 2. For every 15 rotations of the eccentric drive shaft, the inner gear will rotate once.

Gear ratio= number of sides of the inner polygon 2 Any gear ratio from two upwards can be devised. Higher gear ratios can be derived by joining two drives together. For example: Joining a 16/15 with a 17/16 drive, fixing the larger outer gear, joining the two inner gears and allowing the smaller out gear to rotate as the output drive, a gear ratio of 16 squared (256:1) is achieved. Gear ratio for large fixed outer gear = Largest outer gear x Smallest inner gear + 1 Largest inner gear - Smallest outer gear

Gear ratio for Small fixed outer gear = Largest outer gear x Smallest inner gear Largest inner gear - Smallest outer gear

Manufacturing of the gear

Both inner and outer gears can be formed by fransforming the bearings into a cutter. By rotating the cutter around its centre point of the middle polygon and at the same time rotating the gear in the same direction around its centre point, it is possible to cut the profile of the teeth for both inner and outer gears.

The Ratio is as follows: Rl = Rotation of Inner Gear = number of sides of outer polygon / 2 R2 = Rotation of Outer Gear = number of sides of inner polygon / 2 Rotation of cutter = Rl + (R2/R2x2+1) Detailed Description with respect to the Drawings

Figure 1. Fifteen toothed inner gear 18 coupled with a sixteen toothed outer gear 13, having a gear ratio of 15 : 1. Tooth profile 9 and 10 are of equal lengt Centre of Outer gear 3. Centre of bearings 2. Centre of inner gear 1. Bearings 14.

Figure 2. Thirty toothed inner gear 18 coupled with a thirty-two toothed outer gear 13, having a gear ratio of 15:1. Tooth profile 9 and 10 are of non-equal length. Bearings 14.

Figure 3. Formation of the teeth parabolas. Points of contact and centre of bearings 15. Out tooth profile 7. Inner tooth profile 8. Centre of outer polygon 3. Centre of middle polygon 2. Centre of inner polygon 1. Inner polygon 4. Middle polygon 5. Outer polygon 6.

Figure 4. . Offset of the teeth to accommodate bearings. Out tooth offset profile 9. Inner tooth offset profile 10. Middle polygon 5. Figure 5. Insertion of bearings. Out tooth offset profile 9. Inner tooth offset profile 10. Bearings 14. Points of contact and centre of bearings 15. Middle polygon 5

Figure 6. Complete Gear. Recesses 11 and 12 to accommodate bearings, Tooth profile 9 and 10 are of equal length. Bearings 14. Middle polygon 5. Outer Gear 13. Inner Gear 18.

Figure 7. Formation of the 30/32 tooth gear. Points of contact and centre of bearings 15. Out tooth profile 7. Inner tooth profile 8. Inner polygon 4. Middle polygon 5. Outer polygon 6.

Figure 8. Offset of the teem (equal to the distance between outer polygon centre and inner polygon centre, to accommodate bearings. Out tooth profile 7. Inner tooth profile 8. Out tooth offset profile 9. Inner tooth offset profile 10. Middle polygon 5.

Figure 9. Insertion of bearings. Out tooth offset profile 9. Inner tooth offset profile 10. Bearings 14. Points of contact and centre of bearings 15. Middle polygon 5.

Figure 10. Complete 30/32 tooth Gear. Recesses 11 and 12 to accommodate bearings, Tooth profile 9 and 10 are of non-equal length Bearings 14. Middle polygon 5. Outer Gear 13. Inner Gear 18.

Figure 11. Bearing showing Caged arrangement for bearings. Outer Gear 13. Inner Gear 1 δ.Bearings 14. Bearing cage 17. The claims, illustrations, and drawings form part of the disclosure of this specification as does the description, claims, illustrations, and drawings of any associated provisional or parent specification or of any priority document, if my, all of which are imported hereinto as part of the record hereof.

Finally it is to be understood that various alterations, modifications, and/or additions may be incorporated into the various constructions and arrangements or parts without departing from the spirit and ambit of the invention.

Dated 31st day of May, 2004 Alan Barnes

Claims

The Claims defining the invention are as Follows:

1. Each tooth on the inner gear is always in contact with an outer tooth on the outer gear, directly or by a ball bearing separating the teeth

2. If the teeth are offset a certain distance from the centre of the ball bearings, the inner tooth parabolic length can equal the outer tooth parabolic length, creating a true rolling action for the gear and no friction losses are encountered.

3. The high degree of contact between the teeth allows i accuracy, precision of movement and minimal backlash

4. Any gear ratio from two upwards can be devised.

5. The gear has 3 centers of rotatioα The oirter gear (outer polygon), the inner gear (inner polygon), and the ball bearing Housing (middle polygon).

6. Three equal side polygons are used to create the gear.

7. The middle polygon marks the intersecting points of the gears teeth from which the shape of the teeth are created.

8. If the offset distance of the tooth is equal to or greater than the distance between centers of the inner and outer polygons, then the inner and outer teeth are able to pass over each other and therefore twice the number of teeth can be used in the gear.