GB2212570A

GB2212570A - Gear mechanism

Info

Publication number: GB2212570A
Application number: GB8726754A
Authority: GB
Inventors: Kok Soon Si-Hoe; Ong Tiong Ee
Original assignee: SI HOE KOK SOON
Current assignee: SI HOE KOK SOON
Priority date: 1987-11-16
Filing date: 1987-11-16
Publication date: 1989-07-26
Anticipated expiration: 2007-11-16
Also published as: GB2212570B; GB8726754D0

Abstract

A gear mechanism comprising a driving crown gear 19 which has teeth extending over a limited arc, preferably less than 180 DEG , the drive gear 19 meshing alternately with pinions 20 and 21 on a shaft 22. The shaft 22 may for instance carry a brush head 26 of a tooth brush so that when an electric motor is incorporated to drive the gearing the tooth brush head will be made to rotate alternately in opposite directions about the axis of the drive shaft. Instead of a crown wheel and pinions bevel drive gears may be used. <IMAGE>

Description

GEAR MECHANISM This invention relates to a gear mechanism.

An object of the invention is to provide a gear mechanism which enables a constant rotation to be converted to an alternately reversing rotary movement.

In accordance 'with the invention the gear mechanism comprises a drive gear having teeth on it which extend only through an arc of less than 180 degrees, the drive gear being adapted, when it is rotated, to alternately mesh with two driven gears, so that as the drive gear rotates the driven gears alternately rotate in opposite directions.

Two driven gears may be located on a single driven shaft so that the driven shaft executes an alternately reversing rotary movement. The drive and driven gears may for instance be bevel gears or the drive gear may be a crown wheel and the driven gears may be pinions, or any other suitable form of gear may be used.

From another aspect the invention relates to a motor-driven toothbrush, comprising a motor, a drive shaft, and a toothbrush head with gearing between the drive shaft and the head, so arranged as to cause the head to execute an alternately reversing rotary movement about its longitudinal axis.

Preferably the head is of bell shaped, domed shaped, or frusto-conical shaped and the reciprocation is about the central longitudinal axis of the head.

Preferably the head is arranged to rotate through an angle between 90 and 120 degrees in one direction and then to rotate through the same angle in the opposite direction in a continuous alternate fashion.

The gear mechanism for achieving this effect in the toothbrush may be as described above.

Preferably the domed shaped, bell shaped, or frusto-conical brush head is secured to the driven shaft through a quick change coupling, to enable it to be removed and replaced easily.

The gearing may be contained within an enclosed housing, preferably of plastic, and the gearing, drive and driven shafts may be attached to a second housing containing a motor and, if the motor is an electric motor, the housing may also contain batteries preferably rechargeable, to drive the motor.

In the accompanying drawings: Figure 1 is an elevation part in section of an electrically driven toothbrush embodying the present invention; Figure 2 is an isometric view showing a drive gear which is incorporated in the toothbrush drive of Figure 1; Figure 3 is an alternative embodiment of the invention using bevel gears instead of the crown wheel and pinion shown in Figure 1; Figure 4 shows a more compact version of the driving gear system of the toothbrush, and shows the toothbrush head formed integrally with one of the gears.

In Figure 1 is shown a housing 10 containing rechargeable batteries 11, 12 which, in conventional fashion, power a motor 13 having an output shaft 14 which, through reduction gearing 15, 16 drives a toothbrush drive shaft 17. The housing has a control switch 18 to enable the motor to be switch on and off by the user.

Drive shaft 17 extends through an extension 18 of the housing 10 and carries a drive gear 19 in the form of a crown gear. This crown gear is of special construction and is illustrated in Figure 2, it will be seen that the crown has teeth which extend at 19' over a limited arc.

considerably less than 180 degrees of arc of the gear.

The extent of the teeth may be as little as 45 to 60 degrees around the gear face.

The drive gear 19 drives alternately to driven pinions 20, 21 carried on a brush shaft 22 mounted in bearings 23, 24 in a plastic gear housing 25. The brush shaft carries a brush head 26 which may be in the domed or frusto-conical, form shown in Figure 1 or may take other forms as illustrated in Figures 3 and 4.

The brush head may be connected to the shaft 22 by an easily detachable coupling device 27, not shown in detail.

As the drive shaft 17 is rotated, gear 19 rotates continuously in one direction and the teeth 19' alternately engage with pinion 20 and 21. During the period of engagement of the teeth with gear 21 it will be driven in one direction, and thus drive the shaft 22 and brush head in that direction, but as the drive gear 19 turns, the teeth 19' will become disengaged from drive pinion 21 and will then engage drive pinion 20, and drive it in the opposite direction. Thus the brush head 26 will alternately rotate in opposite directions.

The angular displacement of the brush head in each direction would depend upon the extent of the teeth 19' around the gear 19 that may be equal to or less than 90 degrees. The arrangement may be such that the total height of the brush and gear mechanism may be 20 mm, the brush having a diameter of 6 mm and the peripheral linear displacement may be up to 4.5 mm.

The following speeds may be used with particular angular displacements of the brush and particular peripheral linear brush displacements: RPM of Shaft Angular Displacement Peripheral Brush of Brush Displacement 600 90 degrees 6 mm 900 100 degrees 8 mm 1200 120 degrees 10 mm Instead of using the crown, gear and pinions shown in Figure 1 the size of the housing may be reduced as shown in Figure 3 by employing a bevel drive gear 28 driving two driven bevel gears 29 and 30. The housing 31 is seemed to be of less depth than the housing shown in Figure 1 and by way of example a different form of domed brush head 32 is shown.

The housing for the gearing may be further reduced in size as shown in Figure 4 in which the housing 33 supports the brush shaft 35 and the gears, again bevel gears 36 and 37 are located on the exterior of the housing 33. The brush 38 may be formed integrally with the gear 37 as a single molding.

All the gears and the housing may be made in plastics materials, the gears themselves preferably being made of nylon.

The alternately reversing rotary action produced is distinct and different from vibrating, reciprocating or arcuating actions in previously proposed brushes. The area of action with a brush of this invention is confined to the area over which the instrument is actually placed which gives superior localisation and control of the brushing action.

The alternately reversing rotary mechanism enables brush bristles to work themselves into grooves and pits in the teeth.

The gear mechanism described may be applied to other machines, for example rotary mixing devices where the gears may be used to drive mixing blades or paddles and to give an efficient agitation effect.

Claims

CLAIMS:-

1. A gear mechanism comprising a drive gear and two driven gears, the drive gear having teeth on it which extend through an arc of less than 1800 and being adapted, when it is rotated, to mesh alternately with the two driven gears, so that as the drive gear rotates the driven gears alternately rotate in opposite directions.

2. A gear mechanism according to claim 1 and in which the two driven gears are located on a single driven shaft so that the driven shaft executes an alternately reversing rotary movement.

3. A gear mechanism according to claim 1 or claim 2 and in which the drive and driven gears are bevel gears.

4. A gear mechanism according to claim 1 or claim 2 and in which the drive gear is a crown wheel and the driven gears are pinions.

5. A motor-driven tooth brush, comprising a motor, a drive shaft, and a tooth brush head with gearing between the drive shaft and the head so arranged as to cause the head to execute an alternately reversing rotary movement about its longitudinal axis.

6. A tooth brush according to claim 5 and in which the head is bell-shaped, dome-shaped, or frusto-conical shaped and the reciprocation is about the central longitudinal axis of the head.

7. A tooth brush according to claim 5 or claim 6 and in which the head is arranged, when driven, to rotate through an angle between 90"and 1200 in one direction and then to rotate through the same angle in the opposite direction in a continuous fashion.

8. A tooth brush according to claim 6 and in which the dome-shaped, bell-shaped, or frusto-conical shaped brush head is secured to the driven shaft for a quick change coupling, to enable it to be removed and replaced easily.

9. A tooth brush according to any of claims 5 to 8 and in which the gearing is contained within an enclosed housing.

10. A tooth brush according to claim 9 and in which the housing is made of plastics material.

11. A tooth brush according to claim 9 and in which the gearing, drive and driven shafts are attached to a second housing containing the motor.

12. A tooth brush according to claim 11 and in which the motor is an electric motor and the housing also contains batteries.

13. A motor driven toothbrush substantially as hereinbefore particularly described and as illustrated in the accompanying drawings.

13. A tooth brush according to claim 12 and in which the batteries are rechargable.

14. A tooth brush according to any of claims 5 to 13 and in which the gearing for the tooth brush is in accordance with any of claims 1 to 4.

15. A motor driven tooth brush comprising a motor, a drive shaft and a tooth brush head with gearing between the drive shaft and the head, the gearing comprising a drive gear and two driven gears, the drive gear having teeth on it which extend only through an arc of less than 1800 and being adapted, when it is rotated, to mesh alternately with the two driven gears so that the drive gear rotates the driven gears and hence rotates the head in alternately reversing rotary movements about its longitudinal axis.

16. A gear mechanism substantially as hereinbefore particularly described and as illustrated in the accompanying drawings.

17. A motor driven tooth brush substantially as hereinbefore particularly described and as illustrated in the accompanying drawings.

Amendments to the claims have been filed as follows CLAIMS:-

1. A motor-driven tooth brush, comprising a motor, a drive shaft, and a tooth brush head with gearing between the drive shaft and the head so arranged as to cause the head to execute an alternately reversing rotary movement about its longitudinal axis, said gearing comprising a drive gear and two driven gears, the drive gear having teeth on it which extend through an arc of less than1800 and being adapted, when it is rotated, to mesh alternately with the two driven gears, so that as the drive gear rotates the driven gears alternately rotate in opposite directions.

2. A toothbrush according to claim 1 and in which the two driven gears are located on a single driven shaft so that the driven shaft executes said alternately reversing rotary movement.

3. A toothbrush according to claim 1 or claim 2 and in which the drive and driven gears are bevel gears.

4. A toothbrush according to claim 1 or claim 2 and in which the drive gear is a crown wheel and the driven gears are pinions.

5. A toothbrush according to any preceding claim and in which the head is bell-shaped, dome-shaped, or frusto-conical shaped and the reciprocation is about the central longitudinal axis of the head.

6. A toothbrush according to any preceding claim and in which the head is arranged, when driven, to rotate through an angle between 900 and 1200 in one direction and then to rotate through the same angle in the opposite direction in a continuous fashion.

7. A toothbrush according to claim 5 and in which the dome-shaped, bell-shaped, or frusto-conical shaped brush head is secured to the driven shaft for a quick change coupling, to enable it to be removed and replaced easily.

8. A toothbrush according to any preceding claim and in which the gearing is contained within an enclosed housing.

9. A toothbrush according to laim 8 and in which the housing is made of plastics material.

10. A toothbrush according to claim 8 and in which the gearing, drive and driven shafts are attached to a second housing containing the motor.

11. A toothbrush according to claim 10 and in which the motor is an electric motor and the housing also contains batteries.

12. A toothbrush according to claim 11 and in which the batteries are rechargable.