EPICYCLOIDAL GEAR TRAIN

Abstract

The invention relates to a self-locking epicyclic gear train (1) comprising a pinion (2) with at least one helical gear tooth (21), a ring gear (3) with a plurality of helical gear teeth (31), and a plurality of planet gears (4) between the pinion (2) and the ring gear (3). Each planet gear (4) comprises a plurality of helical gear teeth (41) that engage with the teeth (31, 21) of the ring gear (3) and the pinion (2). The helical gear teeth (21, 31, 41) have a helix angle of less than 20°, and the pinion (2) is always in contact with at least one tooth (41) of the ring gear or each planet gear (4). Figure 1

Description

Title of the invention: EPICYCLOIDAL GEAR TRAIN Technical field of the invention

[0001] The invention relates to the field of epicyclic gear trains. More specifically, but not exclusively, this invention also relates to a drive assembly comprising a motor coupled to the pinion of an epicyclic gear train and a tubular motor comprising the assembly. Technical background

[0002] It is known to provide a tubular motor assembly comprising a motor coupled to the pinion of an epicyclic gear train, for example in motorized winding element installations.

[0003] It is also known to use such tubular motor assemblies in motorized shutter installations. EP3470616A1 describes such an installation in which the tubular motor assembly comprises an epicyclic gear train driven by a brushless motor. Summary of the invention

[0004] The invention aims to mitigate the problems observed when using motor assemblies with epicyclic gear trains in applications where reversibility is not desirable (driving the input of the reducer by rotating the output is not desirable). The invention also aims to improve the efficiency of the epicyclic gear train while minimizing the impact on its noise and wear characteristics.

[0005] The invention relates to a self-locking epicyclic gear train comprising: a pinion with at least one helical gear tooth; a crown with a plurality of helical gear teeth; and one or more planet gears between the pinion and the crown, the or each planet gear comprising a plurality of helical gear teeth which engage with the gear teeth of the pinion and the crown.

[0006] The helix angle of the helical gear teeth may be less than 20°.

[0007] In some examples, the or each tooth of the pinion is always in contact with at least one tooth of the or each satellite.

[0008] The invention also relates to a self-locking epicyclic gear train comprising: a pinion with at least one helical gear tooth; a crown gear with a plurality of helical gear teeth; and one or more planet gears between the pinion and the crown gear, the or each planet gear comprising a plurality of helical gear teeth which engage with the teeth of the crown gear and the pinion; wherein the helical gear teeth have a helix angle less than 20° and the pinion is always in contact with at least one tooth of the or each satellite.

[0009] The inventors have discovered that by minimizing the helix angle while maintaining contact between at least one of the teeth of the or each satellite with the pinion, it is possible to improve the efficiency of the self-locking epicyclic gear train, while minimizing the impact on its noise and wear characteristics.

[0010] In particular, the inventors observed, to their great surprise, that this reduction in the helix angle, which increases the efficiency of the gear train, does not significantly reduce the contact surface despite the reduction in the number of teeth in contact.

[0011] The helix angle of the helical gear teeth may be less than or equal to 18°, for example less than or equal to 15°. The helix angle of the helical gear teeth may be at least 8°, for example at least 10°. The helix angle of the helical gear teeth may be between 8° and 18°, for example between 9° and 15°. The helix angle of the helical gear teeth may be between 10° and 12°, for example about 11°.

[0012] More specifically, the helix angle of the helical gear teeth may be between 10° and 12°.

[0013] The pinion and / or crown may comprise or be formed of a metal. The satellite(s) may comprise or be formed of a polymer.

[0014] The tooth(s) of the pinion and / or the teeth of the satellite(s) may be configured so that the coefficient of friction between them is at least 0.10, for example at least 0.11.

[0015] More precisely, the coefficient of friction between the or each tooth of the pinion and the or each tooth of the satellite(s) may be at least 0.11.

[0016] A coefficient of friction of at least 0.11 is preferable to ensure the self-locking function.

[0017] The tooth(s) of the pinion and / or the teeth of the satellite(s) may be configured so that the coefficient of friction between them is between 0.08 and 0.14, preferably between 0.10 and 0.12, for example between 0.11 and 0.12 or approximately 0.11.

[0018] The teeth of the satellite(s) and / or the crown may also be configured so that the coefficient of friction between them is between 0.08 and 0.14, preferably between 0.10 and 0.12, for example approximately 0.11.

[0019] The axial length of the contact surface between the or each tooth of the pinion and the or each tooth of the or each satellite may be at least 20%, for example at least 30%, 35% or 40%, of the value of the diameter of the head of the pinion. The axial length of the contact surface between the or each tooth of the pinion and the or each tooth of the or each satellite may be between 35% and 50%, for example between 40% and 45%, of the value of the diameter of the head of the pinion. In some examples, the axial length of the contact surface between the or each tooth of the pinion and the or each tooth of the or each satellite is approximately 43% of the value of the diameter of the pinion head.

[0020] More precisely, the axial length of the contact surface between the or each tooth of the pinion and the or each tooth of the or each satellite can be at least 35% of the value of the diameter of the head of the pinion.

[0021] The area of ​​the contact surface between the or each tooth of the pinion and the or each tooth of the or each satellite may be at least 0.15 times, for example at least 0.2 times, the axial length L of the contact surface. The area of ​​the contact surface between the or each tooth of the pinion and the or each tooth of the or each satellite may be between 0.2 and 0.3 times, for example between 0.20 and 0.25 times, the axial length L of the contact surface, for example approximately 0.23 times the axial length L of the contact surface.

[0022] More precisely, the area of ​​the contact surface between the or each tooth of the pinion and the or each tooth of the or each satellite can be between 0.2 and 0.3 times the axial length L of the contact surface.

[0023] In some examples, a maximum of two teeth of the or each satellite are in contact with the or each tooth of the pinion at any time.

[0024] The teeth may be profiled such that, in use, rotation of the pinion induces a corresponding rotation of the satellite(s), while rotation of the satellite(s) induces a force which is insufficient to induce a corresponding rotation of the pinion.

[0025] Thus, the invention provides an epicyclic gear train with gear profiles that provide a self-locking function when the output of the reducer is driving. This self-locking function is therefore particularly useful in applications where the output of the reducer may be driving. This may for example be the case when the gear train is coupled to a brushless motor.

[0026] Furthermore, this makes it possible to obtain high reduction ratios.

[0027] The rotation, in use, of the pinion may induce an effective force extending away from the center of the or each satellite, so as to induce a corresponding rotation of the satellite(s). The rotation of the satellite(s) may induce an effective force passing in the vicinity of the center of the pinion, so as not to induce a corresponding rotation of the pinion.

[0028] In some examples, the teeth are profiled such that, in use, rotation of the pinion induces an effective force extending away from the center of the or each satellite, so as to induce a corresponding rotation of the satellite(s), whereas rotation of the satellite(s) induces an effective force passing near the center of the pinion, which is insufficient to induce a corresponding rotation of the pinion so as not to induce a corresponding rotation of the pinion.

[0029] The teeth may be profiled such that the pressure angle common to the or each satellite and the pinion is such that, in use, rotation of the pinion induces a corresponding rotation of the satellite(s), while rotation of the satellite(s) induces a force which is insufficient to induce a corresponding rotation of the pinion.

[0030] The pinion may comprise three or fewer teeth. The pinion may comprise two or fewer teeth.

[0031] The pinion may comprise a single tooth.

[0032] The pressure angle, in particular the apparent pressure angle (also called "transverse pressure angle" in English terminology), common to the or each satellite and the pinion may be between 30° and 60°, for example approximately 35°. The pressure angle, in particular the apparent pressure angle, common to the or each satellite and the pinion may be between 35° and 55°. The pressure angle, in particular the apparent pressure angle, common to the or each satellite and the pinion may be between 35° and 45°. The pressure angle, in particular the apparent pressure angle, common to the or each satellite and the pinion is preferably between 35° and 40°, for example approximately 39°.

[0033] More precisely, the apparent pressure angle common to the or each satellite and to the pinion can be between 35° and 55°.

[0034] The satellite(s) may comprise at least three satellites.

[0035] The satellite(s) may comprise four satellites. The satellite(s) may comprise a plurality of satellites. The plurality of satellites may comprise at least three satellites, for example four satellites.

[0036] The crown may comprise at least one groove, for example to engage in a tubular housing inside which the self-locking epicyclic gear train is to be received.

[0037] The invention also relates to a drive assembly comprising a motor coupled to the pinion of a self-locking epicyclic gear train as described above.

[0038] The motor may comprise a brushless motor.

[0039] The drive assembly may include a first stage formed by the self-locking epicyclic gear train. The drive assembly may include a second stage of epicyclic gear train. The drive assembly may include one or more additional stages of epicyclic gear train. The second stage or additional stages of the epicyclic gear train may not be self-locking.

[0040] The invention also relates to a tubular motor assembly comprising a training set as described above.

[0041] For the avoidance of doubt, all features described herein apply equally to any aspect of the invention.

[0042] Within the scope of the present application, it is expressly provided that the various aspects, embodiments, examples and alternatives set forth in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. In other words, all embodiments and / or features of any embodiment may be combined in any way, unless such features are incompatible.

[0043] For the avoidance of doubt, the terms "may", "and / or", "for example", "for example" and any other similar terms used herein should be interpreted as non-limiting, such that any feature so described need not necessarily be present.

[0044] Indeed, any combination of optional features is expressly contemplated without departing from the scope of the invention, whether or not they are expressly claimed. Brief description of the figures

[0045] Other characteristics and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which reference will be made to the appended drawings in which:

[0046] [Fig.l] [Fig.l] illustrates a gear train according to the invention;

[0047] [Fig.2] [Fig.2] illustrates an exploded view of the gear train of [Fig.l];

[0048] [Fig.3] [Fig.3] illustrates a sectional view of the gear train of Figures 1 and 2, showing the contact forces between the pinion teeth and one of the planet gears;

[0049] [Fig.4] [Fig.4] illustrates one of the satellites of the gear train of figures 1 to 3 indicating the helix angle;

[0050] [Fig.5] [Fig.5] illustrates the pinion with a representation of the contact surface between the pinion tooth and a tooth of one of the satellites in use;

[0051] [Fig.6] [Fig.6] illustrates a pinion of a similar gear train but with a helix angle larger than that of the pinion of [Fig.5], with a representation of the contact surfaces between the pinion tooth and each of three teeth of a satellite;

[0052] [Fig.7] [Fig.7] illustrates a training assembly;

[0053] [Fig.8] [Fig.8] illustrates a tubular motor assembly comprising the assembly training of [Fig.7]. Detailed description of the invention

[0054] Various aspects of various embodiments according to the invention are described in more detail below, with reference to the attached Figures 1 to 8.

[0055] Figures 1 to 3 illustrate an overview of a self-locking epicyclic gear train 1 according to the invention. This gear train comprises a pinion 2 with a helical gear tooth 21, a crown 3 with a plurality of helical gear teeth 31 and four satellites 4 between the pinion and the crown. Each satellite 4 comprises a plurality of helical gear teeth 41 which engage with the teeth 21, 31 of the crown 3 and the pinion 2.

[0056] The gear train is mounted on a carrier 11, which comprises an axle 12 on which the pinion 2 is mounted and a respective axle 14 for each satellite 4. Those skilled in the art will understand that the pinion 2 will comprise a coupling device (not shown) for coupling to a motor in use. The carrier 11 also comprises an output gear 16. The crown 3 comprises four splines 5 for engaging in a tubular housing within which the self-locking epicyclic gear train is to be received.

[0057] In [Fig. 3] is schematically illustrated the application of an effective contact force Fi / 2 of the pinion 2 on a satellite 4, and an inverse force F2 / i of the satellite 4 to the pinion 2. In this example, the pinion 2 and the crown 3 are formed of a metal and the satellites 4 are formed of a polymer. The coefficient of friction, in service, between the gear teeth 21, 41 of the pinion 2 and the satellites 4 is approximately 0.11. The apparent pressure angle common to each satellite 4 and to the pinion 2 is approximately 39°.

[0058] As illustrated, the rotation, in operation, of the pinion 2 induces an effective force Fi / 2 extending at a distance rb2 from the center of each satellite 4, so as to induce a corresponding rotation of the satellites 4. On the other hand, the rotation of the satellites 4 induces an effective force F2 / i passing in the vicinity of the center of the pinion 2, at a distance rbl, so as not to induce a corresponding rotation of the pinion 2.

[0059] The gear teeth of the self-locking epicyclic gear train 1 are therefore profiled in such a way that, in operation, the rotation of the pinion induces a corresponding rotation of the satellites, whereas the rotation of the satellites induces a force which is insufficient to induce a corresponding rotation of the pinion.

[0060] Thus, the invention provides an epicyclic gear train with gear profiles that provide a self-locking function. This makes it possible to obtain high reduction ratios and to prevent the motor from being driven when the output is driving, which can be useful in certain applications, for example when the gear train is coupled to a brushless motor with low cogging (resistant magnetic torque) or even zero cogging.

[0061] According to the invention and as shown in [Fig.4], the helical gear teeth 41 (21,31,41) have a helix angle [3, which is 11° in this example. The in Vendors have observed that this helix angle [3 allows to obtain a contact ratio slightly greater than one, which means that the pinion 2 is always in contact with at least one tooth 41, but at most two teeth 41, of each satellite 4.

[0062] [Fig.5] shows the pinion 2, highlighting the contact surface S between the pinion 2 and one of the satellites 4. The contact surface S has an axial length L which extends over a large part of the width of one side of the tooth 21. The contact surface S also has a surface area corresponding to the region shown in highlighting. In this example of the invention, the diameter of the head of the pinion 2 is 7.5mm, the axial length L is about 3.2mm and the area of ​​the contact surface S is about 0.74mm. The basic train efficiency (fixed satellite carrier) of this arrangement is about 62%.

[0063] [Fig.6] shows a pinion 2' for an epicyclic gear train (not shown) in which the helix angle of the helical gear teeth is 30°, highlighting each of the three contact surfaces Sa, Sb, Sc between the pinion 2' and one of the planet gears. Each contact surface Sa, Sb, Sc has an axial length La, Lb, Lc that extends over a portion of the width of one side of the tooth 21'. The contact surfaces Sa, Sb, Sc provide an aggregate surface area corresponding to the sum of the highlighted regions.

[0064] In this example, the diameter of the head of the pinion 2 is 7.5mm, the axial length aggregated surface area (La + Lb + Lc) is approximately 3.6mm and the area of ​​the aggregated contact surface (Sa + Sb + Sc) is approximately 0.75mm. The basic train efficiency (fixed satellite door) of this arrangement is approximately 57%.

[0065] It is generally desirable to provide the helical gear teeth with a larger helix angle, as this should provide a larger and more spread contact area, which reduces wear and noise in the gear train 1. It is also known that increasing the helix angle also has a negative effect on the efficiency of the gear train, since it increases the axial component of the force transmitted between the gear teeth.

[0066] However, the inventors observed, to their surprise, that a helix angle [3 of 11° used with a self-locking gear profile, as described herein, actually provides a contact area S (see [Fig.5]) comparable to an aggregated contact area Sa, Sb, Sc (see [Fig.6]) of a similar arrangement having a helix angle of 30° which results in a contact ratio of three.

[0067] Those skilled in the art will appreciate that this decrease in helix angle [3] has a considerable impact on the efficiency of the gear train 1. As such, the inventors have determined that the efficiency of the gear train 1 can be significantly improved without substantially adversely affecting the wear and noise of the gear train 1. Although the distribution of the contact surface S is less spread out in the gear train of gears 1 according to the invention, this appears to have a relatively minor impact on wear and noise in many applications.

[0068] The axial length L of the contact surface S between the tooth 21 of the pinion 2 and the tooth 41 of each satellite 4 represents approximately 43% of the value of the diameter of the head of the pinion 2. The inventors have found that this length could be less, for example up to 20%, but preferably greater than 35% and ideally greater than 40%.

[0069] Furthermore, the area of ​​the contact surface S between the tooth 21 of the pinion 2 and the tooth 41 of each satellite 4 represents approximately 0.23 times the axial length L of the contact surface S. The inventors have found that this length could be less, for example up to 0.15 times, but preferably greater than 0.2 times the axial length L of the contact surface.

[0070] As illustrated in [Fig.7], the invention further relates to a drive assembly 100 comprising a motor 10 coupled to the pinion 2 of the self-locking epicyclic gear train 1 described above. The motor 10 comprises a brushless motor in this example. The drive assembly 100 comprises a first stage formed by the self-locking epicyclic gear train 1 and two additional stages of epicyclic gear train 110, 120. The additional stages 110, 120 are not self-locking in this example.

[0071] As illustrated in [Fig.8], the invention also relates to a tubular motor assembly 1000 comprising a drive assembly 100 described above.

[0072] Those skilled in the art will appreciate that several variants of the aforementioned embodiments are possible without departing from the scope of the invention. List of reference signs

[0073] 1 self-locking epicyclic gear train

[0074] 10 engine

[0075] 11 support

[0076] 12 pinion axle

[0077] 14 satellite axle

[0078] 16 output gear

[0079] 100 training set

[0080] 110 additional stage of epicyclic gear train

[0081] 120 additional stage of epicyclic gear train

[0082] 1000 tubular motor

[0083] 2 pinion

[0084] 20 pinion rotation axis

[0085] 21 pinion tooth

[0086] 3 crown

[0087]

[0088]

[0089]

[0090]

[0091]

[0092]

[0093]

[0094]

[0095]

[0096]

[0097]

[0098] 31 crown tooth 4 satellite 41 satellite wheel 5 spline L axial length of contact surface La axial length of contact surface Lb axial length of contact surface Lc axial length of contact surface S contact surface Sa contact surface Sb contact surface Sc contact surface

Claims

Claims

1. A self-locking epicyclic gear train (1) comprising: a pinion (2) with at least one helical gear tooth (21); a ring gear (3) with a plurality of helical gear teeth (31); and one or more planet gears (4) between the pinion (2) and the ring gear (3), the or each planet gear (4) comprising a plurality of helical gear teeth (41) which engage with the teeth (21, 41) of the ring gear (4) and the pinion (2); wherein the helical gear teeth (21, 31, 41) have a helix angle of less than 20° and the pinion (2) is always in contact with at least one tooth (41) of the or each planet gear (4).

2. A self-locking epicyclic gear train according to claim 1, wherein the helix angle of the helical gear teeth (21, 31, 41) is between 10° and 12°.

3. A self-locking epicyclic gear train according to claim 1 or claim 2, wherein the coefficient of friction between the or each tooth (21) of the pinion (2) and the or each tooth (41) of the planet gear(s) (4) is at least 0.

11.

4. Self-locking epicyclic gear train according to any one of the preceding claims, wherein the axial length (L) of the contact surface (S) between the or each tooth (21) of the pinion (2) and the or each tooth (41) of the or each satellite (4) is at least 35% of the value of the diameter of the head of the pinion (2).

5. Self-locking epicyclic gear train according to claim 4, wherein the contact surface (S) between the or each tooth (21) of the pinion (2) and the or each tooth (41) of the or each satellite (4) is between 0.2 and 0.3 times the axial length L of the contact surface (S).

6. A self-locking epicyclic gear train according to any preceding claim, wherein at most two teeth (41) of the or each planet gear (4) are in contact with the or each tooth (21) of the pinion (2) at any time.

7. A self-locking epicyclic gear train according to any preceding claim, wherein the teeth (21,31,41) are profiled such that, in use, rotation of the pinion (2) induces a corresponding rotation of the planet gear(s) (4), while rotation of the planet gear(s) (4) induces a force which is insufficient to induce a corresponding rotation of the pinion (2).

8. A self-locking epicyclic gear train according to claim 7, wherein the teeth (21,31,41) are profiled such that, in use, rotation of the pinion (2) induces an effective force (Fi / 2) extending away from the center of the or each planet gear (4), so as to induce a corresponding rotation of the or each planet gear (4), whereas rotation of the or each planet gear (4) induces an effective force (F2 / i) passing in the vicinity of the center of the pinion (2), which is insufficient to induce a corresponding rotation of the pinion (2) so as not to induce a corresponding rotation of the pinion (2).

9. A self-locking epicyclic gear train according to any preceding claim, wherein the pinion (2) comprises a single tooth (21).

10. A self-locking epicyclic gear train according to any preceding claim, wherein the apparent pressure angle common to the or each satellite (4) and the pinion (2) is between 35° and 55°.

11. A self-locking epicyclic gear train according to any preceding claim, wherein the one or more planet gears (4) comprise at least three planet gears (4).

12. A drive assembly (100) comprising a motor (10) coupled to the pinion (2) of a self-locking epicyclic gear train (1) according to any one of the preceding claims.

13. A drive assembly according to claim 12, wherein the motor (10) comprises a brushless motor.

14. A tubular motor assembly (1000) comprising a drive assembly (100) according to claim 12 or claim 13.

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