GB2587220A

GB2587220A - Actuator gear assembly

Info

Publication number: GB2587220A
Application number: GB1913510.2A
Authority: GB
Inventors: Watzek Michael; Haenni Frédéric
Original assignee: Johnson Electric International AG
Current assignee: Johnson Electric International AG
Priority date: 2019-09-19
Filing date: 2019-09-19
Publication date: 2021-03-24
Also published as: GB201913510D0

Abstract

An actuator gear assembly (30 fig. 3) comprises a gear body 12 having a plurality of gear teeth 14 at a circumference thereof, and a cover (28) in use at least in part positioned adjacent to a major surface 16a of the gear body 12. A noise-damping element 26 is positioned between the gear body 12 and the cover 28. In some embodiments the noise-damping element 26 contacting one or both of the cover 28 and the gear body 12 to reduce noise transmission therebetween. In a further embodiment the gear comprises a well or channel 24 for receiving a noise-damping element. The noise-damping element may be a viscous material such as a grease or oil lubricant, or it may be a non-viscous material such as rubber or foam.

Description

Actuator Gear Assembly The present invention relates to an actuator gear assembly, preferably but not necessarily exclusively for damping noise in an actuator caused by vibrations between the gears and the actuator housing. The invention further relates to an actuator having said actuator gear assembly, in addition to a method of reducing a noise output of an actuator. An actuator gear suitable for the actuator gear assembly is also provided.

In existing actuators, there is a desire to reduce the amount of noise generated, particularly by the gear train. Collisions between adjacent gears, and/or by vibrations transmitted to other components of the actuator can all lead to pathways for noise 10 generation.

In particular, transverse forces on adjacent gears in a gear train can lead to dynamic tilting, due to the forces being applied to later gears in sequence being highly directional. Where tilting occurs, vibrations will be transmitted to contacting parts, leading to noise.

Additionally, where a gear is provided on an axle which may be coupled to the actuator 15 housing for alignment purposes, vibrations can be transferred along the axle, leading to further vibration noises.

The present invention seeks to provide an actuator gear arrangement which reduces the effect of vibrationally-induced noise.

According to a first aspect of the invention, there is provided an actuator gear assembly comprising: a gear body having a plurality of gear teeth at a circumference thereof; a cover that in use is at least in part positioned adjacent to a major surface of the gear body; and a noise-damping element positioned between the gear body and the cover, the noise-damping element contacting both the cover and the gear body to reduce noise transmission therebetween.

Vibrations in the gear train of an actuator are one of the primary sources of noise for actuators in general. By inhibiting the vibrational transmission between a cover for the gear and the gear body itself, noise from the actuator can be significantly reduced.

Preferably, the noise-damping element may comprise a viscous material. Said viscous material may be grease or oil.

An advantage of using a viscous material as the noise-damping element is that the viscous shear layer can be readily utilised to obviate clattering noises from the gear train which might be caused by vibrational transmission between the gear body and the actuator housing.

Additionally, or alternatively, the noise-damping element may comprise a non-fluid material, and the non-fluid material may be any one of: rubber, elastic, elastomer, polymer, ceramic, foam, sponge, matting, or felt.

A noise-damping element formed from a non-fluid material is less likely to migrate from the relevant interface area, and therefore require less maintenance than an assembly utilising viscous material.

In one embodiment, the noise-damping element may comprise a non-fluid material in combination with a viscous material.

A combination of the various types of noise-damping element may advantageously introduce the beneficial features of both arrangements, particularly where the proportion 15 of viscous material is higher than might otherwise be expected to allow for a continual viscous shear layer to be utilised.

Optionally, the noise-damping element may be positioned on or at the major surface of the gear body.

A noise-damping element on the major surface of the gear body close to the cover assists 20 with the maintenance of uniform rotation of the gear. Without this element, the gear can dynamically tilt under the application of force from adjacent gears, which can otherwise increase noise generation.

The actuator gear assembly may further comprise an axle to which the gear body is mounted, and wherein the noise-damping element is positioned at an interface between 25 the axle and the gear body.

An axle is a moving part which would usually be a primary source of vibrational noise as it rotates. The noise-damping element of the present invention significantly obviates this issue.

The cover may include an integrated bearing for the axle.

An integrated bearing allows for the cover to extend into the region of the noise-damping element at or adjacent to the axle, further improving the noise reduction capabilities thereof.

In one preferable embodiment, the axle may be press-fit and/or snap-fit engagable with 5 the bearing.

A press-fit and/or snap-fit bearing improves the simplicity of assembly of the actuator, and may also simplify insertion of, for instance, a viscous noise-damping element to be made more straightforward.

Preferably, the gear body may include a well in the major surface at or adjacent to the 10 interface between the axle and the gear body, the noise-damping element being received in the well. Said well may be a labyrinthine well.

A well formed in the gear body provides a suitable reservoir for a viscous noise-damping element, so that the noise damping material does not become spread and lost through the gear train, thereby mitigating its usefulness. A labyrinthine formation may assist in 15 this regard.

Optionally, the integrated bearing may in-use extend at least in part into the well.

The extension of the bearing into the well allows for it to also receive a lubricating and therefore vibration damping effect, which in turn improves the noise damping capabilities.

The actuator gear assembly may further comprise at least one channel in the cover or 20 gear body for receiving the noise-damping element.

A channel provides similar reservoir capacity for noise-damping elements for the major surface of the gear as the well does for the axle, thereby preventing immediate displacement of the viscous material.

Preferably, a plurality of said noise-damping elements may be provided. A first said 25 noise-damping element may be radially spaced inwardly of a second said noise-damping element.

Having more than one noise-damping element allows for different sources of vibrational noise to be counteracted. Specifically, vibrational noise from gear to housing vibrations can be reduced, as can noise caused by dynamic tilting of the gear.

In a preferable embodiment of the invention, the noise-damping element may be formed as a complete annulus.

By providing a complete ring of noise-damping element around the major surface of the gear, there is less likelihood of slippage of the gear, or clattering noises arising from the 5 motion of a tilted gear.

According to a second aspect of the invention, there is provided an actuator comprising: a motor; and an actuator gear assembly in accordance with the first aspect of the invention, wherein the gear body is drivable by the motor.

An actuator having the actuator gear assembly of the present invention will produce less 10 noise than normal, and may therefore be more appropriate for use in a wider range of contexts.

Optionally, the cover may be an actuator housing of the actuator.

Utilising the existing actuator housing of the actuator as the cover of the actuator gear assembly reduces the number of component parts required to assemble the actuator.

According to a third aspect of the invention, there is provided a method of reducing a noise output of an actuator, the method comprising the steps of: a] providing a cover for a gear of the actuator, wherein the cover is in use positioned adjacent to a major surface of the gear body; and b] providing a noise-damping element between the cover and the gear body to inhibit noise generated by dynamic tilting and/or vibration of the gear.

During step b], the noise-damping element may be provided at an interface between an axle and the gear body to inhibit noise generated by vibration of the gear.

Additionally, or alternatively, during step b], the noise-damping element may be provided between the cover and the major surface of the gear to inhibit noise generated by dynamic tilting of the gear.

By providing a means of reducing the noise produced by an actuator utilising one or more noise-damping elements, particularly using a viscous material such as a grease in comparatively high quantities, a quieter actuator operation can be produced.

According to a fourth aspect of the invention, there is provided an actuator gear comprising: a gear body having a plurality of gear teeth at a circumference thereof; and a central axle or axle receiver; wherein the gear body includes a noise-damping-elementreceiving well or channel in a major surface thereof.

A, preferably central well, on an actuator gear can be utilised as a reservoir of noise-damping material which will not otherwise migrate from the critical area, that is, the area 5 at or adjacent to the axle.

Preferably, the noise-damping-element-receiving well or channel may be at or adjacent to an interface between the axle or axle receiver and the gear body.

The actuator gear may further comprise a noise-damping-element-receiving well or channel which is radially-outwardly spaced from the noise-damping-element-receiving 10 well.

Additionally, a further well or channel which provides inhibition of the tilting motion of a gear which can otherwise lead to noise vibrations leads to further improvements to the quieter operation of an actuator.

According to a fifth aspect of the invention, there is provided an actuator gear assembly comprising: a gear body having a plurality of gear teeth at a circumference thereof; a cover that in use is at least in part positioned adjacent to a major surface of the gear body; and a noise-damping element positioned between the gear body and the cover, the noise-damping element contacting at least one of the cover and the gear body to reduce noise transmission therebetween.

The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows an isometric representation of a gear of a first embodiment of actuator gear assembly in accordance with the first aspect of the invention; Figure 2 shows an isometric representation of a gear of a second embodiment of 25 actuator gear assembly in accordance with the first aspect of the invention; Figure 3 shows an isometric representation of the actuator gear assembly of Figure 1, inclusive of a cover; Figure 4 shows a vertical cross-section through the actuator gear assembly of Figure 2, inclusive of a cover; Figure 5 shows a plan view of one embodiment of a gear train of an actuator in accordance with the second aspect of the invention; and Figure 6 shows a view of an actuator housing of the actuator of Figure 5 which forms the cover of the actuator gear assembly.

Referring to Figure 1, there is indicated an actuator gear, referenced globally at 10, which is used as part of an actuator gear assembly in an actuator. The actuator gear 10 comprises a gear body 12 having a plurality of gear teeth 14 positioned around a circumference thereof, and upper and lower major surfaces 16a, 16b of the gear body 12.

The actuator gear 10 here includes an integrated pinion 18 which depends from the lower major surface 16b, and may include either an axle 20 or axle receiver 22 for receiving an axle 20 about which the actuator gear 10 is rotatable. The axle 20 may be provided as an integrally formed axle 20. Preferably, at least the gear body 12 is formed from a rigid plastics material, though other gear construction materials will be apparent to the skilled person.

A well 24 is provided at an interface between the axle 20 or axle receiver 22 and the gear body 12, formed here as a stepped recess into the upper major surface 16a. The well 24 is preferably a noise-damping-element-receiving well, suitable for receiving a volume of noise damping material therein. It may be desirable that the well 24 is formed as a labyrinthine well. Preferably, this may be formed as a viscous material, such as grease or oil, but could alternatively be formed as a non-fluid material, such as rubber, elastic, elastomer, polymer, ceramic, foam, sponge, matting, or felt, for instance. Porous materials may feasibly work well in this context. This would provide a frictional damping for the gear body 12 at or adjacent to the axle 20 or axle receiver 22. In another embodiment, the noise damping material could be a combination of a viscous material and a non-fluid material, for example a rubber ring element which is heavily lubricated with grease. Noise damping here refers to the capacity of the material to absorb, dissipate, damp or attenuate noises arises from the actuator, particularly but not necessarily exclusively vibrational noises.

It has been found that a high proportion of viscous material than might otherwise be used to lubricate a movable joint, has a much-improved noise reduction capacity than would otherwise be anticipated by the skilled person.

A second embodiment of the gear 10 is shown in Figure 2. In this arrangement, a further noise-damping element 26 is provided, which is a solid annulus of material, preferably also lubricated with a large proportion of viscous material. For example, the further noise-damping element 26 may be a rubber washer which is coated in grease, which is a thick, 5 oil-like substance suitable for acting as a lubricant, at least on one side. The further noise-damping element 26 is radially-outwardly spaced with respect to the well 24, preferably at or adjacent to a portion of the upper major surface 16a which is proximate the gear teeth 14. The well 24 itself is therefore preferably comparatively small compared with the total radius of the gear 10, preferably having a width or radius which is less than or equal 10 to half of the gear radius, and more preferably less than or equal to a third of the gear radius.

The in-use arrangement of the gear 10 is shown in Figures 3 and 4, respectively corresponding with the embodiments of Figures 1 and 2, in which a cover 28 of the actuator gear assembly 30 is also indicated. Preferably, the cover 28 is part of the actuator housing of the associated actuator, but could alternatively be provided as a separate cover plate provided in the actuator.

The actuator gear 10 is provided so that the upper major surface 16a is at or adjacent to a surface 32 of the cover 28. In a preferred arrangement, the cover includes a, preferably integrated, bearing 34 which may, in-use, project into the well 24 of the actuator gear 10 once engaged with the axle 20. It is preferred that the axle 20 be press-fit and/or snap-fit engagable with the bearing 34. A corresponding opposing bearing may also be provided on an opposite part of the actuator housing.

Any noise damping material in the well 24 therefore provides a buffer between the cover 28 and the interface between the axle 20 or axle receiver 22 and the gear body 12.

During operation of the actuator gear 10, this will advantageously maintain and control the amount of viscous lubrication of the axle 20. The noise-damping element in the well 24 will damp the vibration of the actuator gear 10 as it rotates, as well as preventing the transmission of any vibrations to the cover 28 and/or actuator housing. This in turn limits the generation of noise from the actuator.

In Figure 4, the further noise-damping element 26 is positioned between the cover 28 and the upper major surface 16a of the gear body 12, so as to contact both. This acts as a stabilising element so that tilting of the actuator gear 10 transverse to the axis of the axle 20 is limited during rotation, which may otherwise occur due to the non-uniform forces applied to the gear teeth 14 by adjacent gears in sequence. The further noise-damping element 26 also provides a surface to damp the vibrations generated between the actuator gear 10 and cover 28 by frictional damping as well as the viscous shear layer of the material, where provided.

It is preferred that the any noise-damping element 26 be provided so as to be or to form a complete annulus, since this limits the likelihood of displacement of the noise-damping element 26 during rotation.

Whilst the first and second noise-damping elements are provided in the arrangement of Figure 4, that is, the noise-damping element in the well 24 and the further noise-damping element 26, it will be appreciated that at least some noise damping capabilities may be obtained by only providing a single noise-damping element. This is, as noted, the case for Figure 3.

This is evidenced from the arrangement shown in Figure 5, in which an actuator 136 15 having a gear train 138 is illustrated. Identical or similar features of the gears described will be referenced using identical or similar reference numerals, and further detailed description is omitted for brevity.

Each of the gears 110a, 110b, 110c in the gear train 138 includes a well 124 within which is contained a noise-damping element such as a thick grease 140. This provides lubrication of at least the interface between the axle 120 and the gear body 112 in each case. This is regardless of whether the gear 110b, 110c is in fact engaged with a corresponding cover 128, though it is preferred that the actuator housing 142 be formed so that a cover 128 or cover portion can be provided for each gear 110a, 110b, 110c. The actuator housing 142 also includes a motor 144, adapted to drive the gear train 138 via an output 146.

Additionally, each gear 110a, 110b, 110c may be provided with an outer annular channel 148 on the upper major surface 116a, which is capable of receiving a further noise-damping element, preferably a viscous material such as grease.

Additionally, or alternatively, and as can be seen in Figure 6, the actuator housing 142 30 can be provided in which the cover 128 contains one or more noise-damping-element-receiving channels, grooves or recesses within which a noise-damping element such as thick grease 140 may be provided.

It may be appreciated as well that the cover of the lower gears 110b, 110c may be at least in part formed by the subsequent gear 110a, 110b in sequence; the noise-damping 5 element may inhibit vibration transmission between the major surfaces 116a of adjacent gears 110a, 110b, 110c.

The rotation of the gears is therefore damped by the viscous shear layer of the viscous material 140 for each of the gears 110a, 110b, 110c, which in turn significantly reduces the overall noise generated by the actuator 136.

The outer annular channel 148 on the gears 110a, 110b, 110c is merely one way in which a reservoir of viscous material may be provided for an actuator gear assembly 130. This could, for example, be provided on the cover 128, on or around an integrated bearing 134 thereof. Other possible configurations could include, but are not necessarily limited to; a plurality of concentric channels, grooves or recesses; a spiral channel, groove, or recess; or a plurality of, preferably equi-angularly spaced-apart, channels, grooves or recesses, which may either be linear or arcuate.

It is noted that in the depicted embodiments that the axle is the component of the assembly which connects the gear to the cover. However, it will be appreciated that this need not necessarily be the case, and instead the gear may have an integrated bearing 20 connector, or may be journaled to the cover, such that the axle could be eliminated.

Overall, it is possible to summarise the teachings of the present invention as follows. A noise output of an actuator can be reduced by providing a cover for a gear of the actuator, wherein the cover is in use positioned adjacent to a major surface of the gear body, and then providing a noise-damping element between the cover and the gear body to inhibit noise generated by dynamic tilting and/or vibration of the gear.

It is therefore possible to provide a means of reducing the noise generated by an actuator by the use of one or more noise dampening elements. Preferably, a noise dampening element is provided at or adjacent to the axle or axle receiver of the gear, in order to inhibit vibrational noise transmission to the actuator housing, and a further noise dampening element is provided which is sandwiched between the cover and the major surface of the actuator gear to limit transverse vibrational noise generation.

The words comprises/comprising' and the words 'having/including' when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components, but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

The embodiments described above are provided by way of examples only, and various other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined herein.

Claims

Claims An actuator gear assembly comprising: a gear body having a plurality of gear teeth at a circumference thereof; a cover that in use is at least in part positioned adjacent to a major surface of the gear body; and a noise-damping element positioned between the gear body and the cover, the noise-damping element contacting both the cover and the gear body to reduce noise transmission therebetween.
2. An actuator gear assembly as claimed in claim 1, wherein the noise-damping element comprises a viscous material.
3. An actuator gear assembly as claimed in claim 2, wherein the viscous material is grease or oil. 15
4. An actuator gear assembly as claimed in any one of claims 1 to 3, wherein the noise-damping element comprises a non-fluid material.
5. An actuator gear assembly as claimed in claim 4, wherein the non-fluid material 20 is any one of: rubber, elastic, elastomer, polymer, ceramic, foam, sponge, matting, or felt.
6. An actuator gear assembly as claimed in any one of the preceding claims, wherein the noise-damping element comprises a non-fluid material in combination with 25 a viscous material.
7. An actuator gear assembly as claimed in any one of the preceding claims, wherein the noise-damping element is positioned on or at the major surface of the gear body.
8. An actuator gear assembly as claimed in any one of the preceding claims, further comprising an axle to which the gear body is mounted, and wherein the noise-damping element is positioned at an interface between the axle and the gear body.
9. An actuator gear assembly as claimed in claim 8, wherein the cover includes an integrated bearing for the axle.
10. An actuator gear assembly as claimed in claim 8 or claim 9, wherein the axle is press-fit and/or snap-fit engagable with the bearing.
11. An actuator gear assembly as claimed in any one of claims 8 to 10, wherein the gear body includes a well in the major surface at or adjacent to the interface between the axle and the gear body, the noise-damping element being received in the well.
12. An actuator gear assembly as claimed in claim 11, wherein the well is a labyrinthine well.
13. An actuator gear assembly as claimed in claim 11 or claim 12, when dependent on claim 9, wherein the integrated bearing in-use extends at least in part into the well.
14. An actuator gear assembly as claimed in any one of the preceding claims, further comprising at least one channel in the cover or gear body for receiving the noise-damping element.
15. An actuator gear assembly as claimed in any one of the preceding claims, wherein a plurality of said noise-damping elements is provided.
16. An actuator gear assembly as claimed in claim 15, wherein a first said noise-damping element is radially spaced inwardly of a second said noise-damping element.
17. An actuator gear assembly as claimed in any one of the preceding claims, wherein the noise-damping element is formed as a complete annulus.
18. An actuator comprising: a motor; and an actuator gear assembly as claimed in any one of the preceding claims, wherein the gear body is drivable by the motor.
19. An actuator as claimed in claim 18, wherein the cover is an actuator housing of the actuator.
20. A method of reducing a noise output of an actuator, the method comprising the steps of: a] providing a cover for a gear of the actuator, wherein the cover is in use positioned adjacent to a major surface of the gear body; and b] providing a noise-damping element between the cover and the gear body to inhibit noise generated by dynamic tilting and/or vibration of the gear.
21. A method as claimed in claim 20, wherein, during step b], the noise-damping 5 element is provided at an interface between an axle and the gear body to inhibit noise generated by vibration of the gear.
22. A method as claimed in claim 20 or claim 21, wherein, during step b], the noise-damping element is provided between the cover and the major surface of the gear to 10 inhibit noise generated by dynamic tilting of the gear.
23. An actuator gear comprising: a gear body having a plurality of gear teeth at a circumference thereof; and a central axle or axle receiver; wherein the gear body includes a noise-damping-element-receiving well or channel in a major surface thereof.
24. An actuator gear as claimed in claim 23, wherein the noise-damping-element20 receiving well or channel is at or adjacent to an interface between the axle or axle receiver and the gear body.
25. An actuator gear assembly comprising: a gear body having a plurality of gear teeth at a circumference thereof; a cover that in use is at least in part positioned adjacent to a major surface of the gear body; and a noise-damping element positioned between the gear body and the cover, the noise-damping element contacting at least one of the cover and the gear body to reduce noise transmission therebetween.