Profile modification for planetary gear device gear teeth
11054013 ยท 2021-07-06
Assignee
Inventors
Cpc classification
F16H57/0006
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16H1/28
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16H2055/0893
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16H55/088
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16H57/02
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16H55/0886
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16H55/17
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16H57/082
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
International classification
F16H55/08
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16H55/17
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16H57/02
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16H57/00
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Abstract
A gear tooth for a gear of a planetary gear device may include a profile modification that alters a profile of the gear tooth to reduce wear and noise. Aspects of the profile modification may include a planar surface that connects a tip surface of the gear tooth with a first or second side of the gear tooth. Other aspects of the profile modification may include a curved surface connecting a tip surface of the gear tooth with a first or second side of the gear tooth. The gear tooth may also include non-constant profile width as measured between the first side and the second side in a gear thickness direction extending between the top and bottom surfaces of the gear. Aspects of gear teeth with either or both the profile modification and non-constant profile width may reduce tooth wear and gear noise during operation of the planetary gear device.
Claims
1. A gear tooth for a gear of a planetary gear device, comprising: a tip surface that is formed at an outer extension of the gear tooth in a radial direction; a first surface that extends from an outer surface of a gear body towards the tip surface; a second surface that extends from the outer surface of the gear body towards the tip surface; and a profile modification that extends between the tip surface and at least one of the first surface or the second surface such that the profile modification joins the tip surface and the at least one of the first surface or the second surface, wherein the profile modification comprises a first planar surface that intersects the tip surface and the first surface, wherein the profile modification comprises a second planar surface that intersects the tip surface and the second surface, and wherein the first planar surface and the second planar surface extend the same distance between their intersections with the tip surface and the first surface and second surface, respectively.
2. A gear for a planetary gear device, comprising one or more of the gear tooth according to claim 1.
3. A planetary gear device, comprising a gear housing; an internal gear fixed to, and disposed inside, the gear housing; a carrier rotatably mounted inside the gear housing; a planetary gear rotatably mounted in the carrier on a planetary gear shaft, wherein the planetary gear meshes with the internal gear; and a sun gear disposed inside the carrier, wherein the sun gear meshes with the planetary gear; wherein at least one of the planetary gear, sun gear, and internal gear comprise one or more of the gear tooth according to claim 1.
4. A planetary gear device, comprising a gear housing; an internal gear fixed to, and disposed inside, the gear housing; a carrier rotatably mounted inside the gear housing, wherein the carrier comprises two separable portions that are joined together to form the carrier; a planetary gear rotatably mounted in the carrier on a planetary gear shaft, wherein the planetary gear meshes with the internal gear; and a sun gear disposed inside the carrier, wherein the sun gear meshes with the planetary gear; wherein at least one of the planetary gear, sun gear, and internal gear comprise one or more gear teeth, comprising: a tip surface that is formed at an outer extension of the gear tooth in a radial direction; a first surface that extends from an outer surface of a gear body towards the tip surface; and a second surface that extends from the outer surface of the gear body towards the tip surface, wherein the gear tooth is formed such that a first distance, measured between a first point on the first surface and a corresponding first point on the second surface at a constant gear tooth height, is not constant in a gear thickness direction extending between an upper surface and a lower surface of the gear body.
5. The planetary gear device of claim 4, wherein the sun gear comprises the one or more gear teeth, and wherein the planetary gear comprises one or more of a second gear tooth, comprising: a tip surface that is formed at an outer extension of the second gear tooth in a radial direction; a first surface that extends from an outer surface of a gear body towards the tip surface; a second surface that extends from the outer surface of the gear body towards the tip surface; and a profile modification that extends between the tip surface and at least one of the first surface or the second surface such that the profile modification joins the tip surface and the at least one of the first surface or the second surface.
6. The planetary gear device of claim 4, wherein the planetary gear comprises the one or more gear teeth, and wherein the sun gear further comprises one or more of a second gear tooth, comprising: a tip surface that is formed at an outer extension of the second gear tooth in a radial direction; a first surface that extends from an outer surface of a gear body towards the tip surface; a second surface that extends from the outer surface of the gear body towards the tip surface; and a profile modification that extends between the tip surface and at least one of the first surface or the second surface such that the profile modification joins the tip surface and the at least one of the first surface or the second surface.
7. The planetary gear device of claim 4, wherein a second distance, measured between a second point on the first surface and a corresponding second point on the second surface at the constant gear tooth height, is less than the first distance, wherein the second distance is taken in a portion of the gear tooth located closer to either the upper surface of the gear or the lower surface of the gear than a portion of the gear tooth containing the first distance.
8. The planetary gear device of claim 7, wherein a third distance is measured between a third point on the first surface and a third point on the second surface at the constant gear height, wherein the portion of the gear tooth containing the second distance is closer to the upper surface than the portion of the gear tooth containing the first distance, wherein the portion of the gear tooth containing the third distance is closer to the lower surface than the portion of the gear tooth containing the first distance, and wherein the first distance is greater than the second distance and the third distance.
9. The planetary gear device of claim 8, wherein the first point on the first surface and the corresponding first point on the second surface are located at the intersection between the first surface and the second surface, respectively, with the tip surface, and wherein the first distance is constant in the gear thickness direction.
Description
BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES
(1) The accompanying drawings, which are incorporated herein and form part of the specification, illustrate aspects of the present disclosure and, together with the description, further serve to explain the principles of the disclosure and to enable a person skilled in the relevant art to make and use the disclosure.
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DETAILED DESCRIPTION
(14) The present disclosure will now be described in detail with reference to embodiments thereof as illustrated in the accompanying drawings. References to one aspect, an aspect, an exemplary aspect, etc., indicate that the aspect described may include a particular feature, structure, or characteristic, but every aspect may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same aspect. Further, when a particular feature, structure, or characteristic is described in connection with an aspect, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other aspect whether or not explicitly described.
(15) The gears of a planetary gear device include teeth that mesh to transmit rotational motion between the gears. This meshing is how the rotational motion is transmitted through the planetary gear device between the input and output portions of the planetary gear device. When two gears mesh there is typically only a single gear tooth from each gear that is in contact at any given instant. These individual gear teeth must transmit all of the forces created by the rotational motion between the gears. As the gears rotate, the gear teeth contact each other repeatedly and begin to exhibit wear from the repeated physical contact. Excessive wear of the gear teeth can eventually lead to gear teeth that are too worn to successfully, which may result in reduced power transmission efficiency and, ultimately, mechanical failure of the planetary gear device. Gear teeth also create noise when they mesh because of the physical contact created by the meshing process. Minimizing planetary gear device noise can be desirable in many instances, particularly when a human operator is positioned near the planetary gear device, as is often the case when planetary gear devices are used in manufacturing machinery or vehicles. Techniques such as special lubrication and material selection for gears can mitigate gear tooth wear and noise, but there is still a need for systems and methods of improving gear tooth wear and reducing tooth noise. Aspects of the present disclosure may yield significant improvements to either or both gear tooth wear and noise, improving on the shapes of gear teeth themselves, without relying only on special lubricants or gear material selection.
(16) An aspect of a gear tooth for a gear of a planetary gear device per the present disclosure includes a tip surface that is formed at an outer extension of the gear tooth in a radial direction, a first surface that extend from an outer surface of a gear body towards the tip surface, and a second surface that extend from the outer surface of the gear body towards the tip surface. A profile modification extends between at least one of the first surface and the second surface and the tip surface such that the profile modification joins the tip surface and the at least one of the first surface and the second surface. As will be discussed below, this system provides advantages that address either or both gear tooth wear and noise.
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(18) Also shown in
(19) As shown by the dashed axis line, carrier 10 is inserted into housing 2 such that the axis of carrier 10 and the axis of housing 2 are aligned. As shown in
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(22) Any of the elements of planetary gear device discussed above may be manufactured from an suitable material. For example, elements may be manufactured from suitable metals or plastics. In some aspects, some or all of the elements discussed above are made from synthetic resins including ultrapolymer polyethylene (UHPE), polyphenylene sulfide (PPS), polyarylate (PAR), polyacetal (POM), or polyamide (PA), polycarbonate (PC), polybutylene terephthalate (PBT), polyether sulfone (PES), polyether ether ketone (PEEK), polyacetal (POM). In any specific aspects, one or more of the elements discussed above may be selected because of its strength and wear characteristics relative to its weight and ease of manufacture.
(23) Applications of aspects of planetary gear device include motor vehicles (where the term planetary gearbox is often used), heavy vehicles (e.g., tractors, construction equipment, and excavation equipment), industrial machines, and household equipment, for example. Some aspects of planetary gear device may also be reduced in size and weight, enabling their use in smaller applications. Compact and lightweight aspects of planetary gear device may be used in conjunction with actuators to operate many different mechanisms in vehicles, including, for example, a power back door (PBD), also known as a power liftgate, power rear hatch, or a power trunk lid; parking brakes or emergency brakes; power windows; and electric shutters or electric blinds for installation and use in vehicles or in buildings (e.g., homes and office buildings).
(24) Planetary gear device as shown in
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(27) The profile of the aspect gear tooth 60 shown in
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(30) The aspect of gear tooth 60 in
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(32) As discussed above, the profile of aspects of gear tooth 60 may remain constant in the gear thickness direction. However, some aspects of gear tooth 60 may not have a constant profile. For example,
(33) Varying the profile of gear tooth 60 in the gear width direction, and in particular selectively narrowing the profile may result in less gear noise and wear because of the reduction in surface area of gear tooth 60 that is in contact with other gear teeth.
(34) The aspect of gear tooth 60 shown in
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(36) The modifications to gear tooth 60 discussed above may be applied to any of the gears found in a planetary gear device. For example, these modifications may be applied to planetary gear 20, sun gear 30, or internal gear 4. Furthermore, the modifications may be applied to more than one of these gears. For example, aspects of gear tooth 60 discussed above may be employed on both planetary gear 20 and sun gear 30. In other aspects, only a single gear (e.g., planetary gear 20) in planetary gear device may contain modified gear teeth 60.
(37) The aspects of gear tooth 60 discussed above may be employed across the gears in different combinations. For example, the aspect of gear tooth 60 shown in
(38) Some examples of aspects of planetary gear device with gear teeth 60 according to aspects discussed above may include the following. A planetary gear device including planetary gear 20 with profile modifications 64 as shown, for example, in
(39) The aspects of planetary gear 20 with profile modifications 64 discussed above may provide specific additional benefits for aspects of carrier 10 that include multiple portions as discussed with respect to
(40) It is to be appreciated that the Detailed Description section, and not the Summary and Abstract sections, is intended to be used to interpret the claims. The Summary and Abstract sections may set forth one or more but not all exemplary aspects of the present disclosure as contemplated by the inventor(s), and thus, are not intended to limit the present disclosure and the appended claims in any way.
(41) The foregoing description of the specific aspects will so fully reveal the general nature of the disclosure that others can, by applying knowledge within the skill of the art, readily modify and/or adapt for various applications such specific aspects, without undue experimentation, without departing from the general concept of the present disclosure. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by the skilled artisan in light of the teachings and guidance.
(42) The breadth and scope of the present disclosure should not be limited by any of the above-described exemplary aspects, but should be defined only in accordance with the following claims and their equivalents.