Backlash-free planetary gears

Abstract

A planetary gear (1) comprises at least: a first hollow wheel (2) having helical teeth (34) and a second hollow wheel (4) having helical teeth (34), wherein the first hollow wheel (2) and the second hollow wheel (4) are adapted to rotate in a first rotation direction (30) and a second rotation direction (32) opposite to the first rotation direction (30); a first double planetary wheel (6) having a first wheel (14) and a second wheel (16), wherein the helical teeth (34) of the first wheel (14) mesh with the helical teeth (34) of the first hollow wheel (2), and the helical teeth (34) of the second wheel (16) mesh with the helical teeth (34) of the second hollow wheel (4), wherein each helical tooth (34) has a first side surface and a second side surface opposite to the first side surface, the surface normal of the first side surface points to the first rotation direction (30), and the surface normal of the second side surface points to the second rotation direction (32); and a first force-applying component (36) that applies a first force in the first direction, so as to make the first side surface of the helical teeth (34) of the first wheel (14) of the first double planetary wheel (6) contact the second side surface of the helical teeth (34) of the first hollow wheel (2), and make the second side surface of the helical teeth (34) of the second wheel (16) of the first double planetary wheel (6) contact the first side surface of the helical teeth (34) of the second hollow wheel (4), thereby giving the hollow wheels (2, 4) preloads in the first and second rotation directions (30, 32).

Description

Technical Field

[0001] The present invention relates to a planetary gear according to the preamble of technical solution 1, comprising at least a first hollow wheel, a second hollow wheel, and a first double planet. Background Technology

[0002] Planetary gears typically consist of multiple wheels or gears. If the gearings of the wheels of such planetary gear mesh, backlash often exists between the teeth. For gears that rotate in only one direction, this is irrelevant because the teeth of the two meshing gears are in contact from the beginning and continue rotating while maintaining this contact. No further additional contact between the teeth occurs during further operation.

[0003] When wheels change their direction of rotation, i.e., perform forward and backward motion and / or alternating motion (oscillating movement) between the two directions, the backlash between the teeth can cause uneven motion profiles (motion profiles) in the wheels. This can lead to unnecessary wear on the gears. Summary of the Invention

[0004] Therefore, the object of the present invention is to reduce the backlash between the gears of a planetary gear.

[0005] This objective is achieved by the planetary gear according to technical solution 1.

[0006] The planetary gear includes at least a first hollow wheel with helical gearing and a second hollow wheel with helical gearing. The first and second hollow wheels are adapted to rotate in a first rotational direction and a second rotational direction. The planetary gear also includes a first double planetary gear having a first wheel and a second wheel. The helical teeth of the first wheel mesh with the helical teeth of the first hollow wheel, and the helical teeth of the second wheel mesh with the helical teeth of the second hollow wheel.

[0007] Each helical tooth of the hollow gear and the double planetary gear has a first side and a second side facing the opposite direction to the first side. The surface normal of the first side points to a first direction of rotation, and the surface normal of the second side points to a second direction of rotation.

[0008] To minimize the backlash between the helical teeth of each gear and the hollow gear in the first planetary gear set, a first force-applying component is provided. This component applies a first force in a first direction, causing a first side of the helical tooth of the first gear of the first planetary gear set to contact a second side of the helical tooth of the first hollow gear, and causing a second side of the helical tooth of the second gear of the first planetary gear set to contact a first side of the helical tooth of the second hollow gear. This contact imparts a preload to the hollow gear in both a first and a second rotational direction. By pressing the first planetary gear set towards the first hollow gear, the helical teeth of the first planetary gear set contact the helical teeth of the first and second hollow gears. Due to this preload, the contact between the helical teeth of the hollow gear and the helical teeth of each gear in the planetary gear set exists from startup. Furthermore, this contact can be maintained by the first force-applying component maintaining the preload during operation, thereby preventing backlash between the helical teeth.

[0009] The first and second wheels of the first double planetary gear are fixed to each other (or about each other). This fixing allows a first force to be applied to both wheels of the first double planetary gear simultaneously, causing the first side of the helical tooth of the first wheel and the second side of the helical tooth of the second wheel to contact the second side of the helical tooth of the first hollow wheel and the first side of the helical tooth of the second hollow wheel, respectively.

[0010] One of the hollow gears can be implemented as an input gear (as a shaft-driven component) in a typical planetary gear system, while the other hollow gear is used as an output gear. Since the first double planetary gear contacts the first hollow gear via its first gear and the second hollow gear via its second gear, the motion of the hollow gear acting as the input gear is transmitted to the hollow gear acting as the output gear. Furthermore, other combinations are possible. For example, a planetary carrier can also be used as an input component. Moreover, the planetary gear can include a sun gear, or one of the hollow gears can serve as the sun gear.

[0011] If only one double planetary gear is used, the two hollow gears may move relative to each other. To avoid this movement, the planetary gear may include a second double planetary gear having a first gear and a second gear. The helical teeth of the first gear mesh with the helical teeth of the first hollow gear, and the helical teeth of the second gear mesh with the helical teeth of the second hollow gear. The planetary gear may also include a second force-applying component that applies a second force in a second direction opposite to the first direction, so as to cause the second side of the helical teeth of the first gear of the second double planetary gear to contact the first side of the helical teeth of the first hollow gear, and to cause the first side of the helical teeth of the second gear of the second double planetary gear to contact the second side of the helical teeth of the second hollow gear, thereby giving the two hollow gears a preload in the first and second rotational directions.

[0012] By using first and second planetary gears, the stability of the planetary gears is improved. Using a second planetary gear prevents the first planetary gear from moving relative to the first and second hollow gears. For this purpose, the first and second planetary gears can also be connected together by a planetary gear carrier. The planetary gear carrier serves as an input component for transmitting forces from the shaft to the planetary gears, and ultimately to the hollow gears.

[0013] Because the double planetary gears are preloaded (or because of the use of preloaded double planetary gears), backlash between the two hollow gears and the double planetary gears is avoided. Since the preload on the second double planetary gear is in the opposite direction to the preload on the first double planetary gear, backlash between the gear teeth is avoided and further improved. Furthermore, the equal distribution of forces caused by the two double planetary gears also helps to keep the hollow gears in place.

[0014] According to a further embodiment, the planetary gear includes an even number of double planetary gears. A first half of the double planetary gears are preloaded by a first force-applying component, and a second half are preloaded by a second force-applying component. By providing an even number of double planetary gears, the first force and the second force can be equally distributed across all the double planetary gears. Furthermore, the preload in the first rotational direction and the preload in the second rotational direction can also be equally distributed.

[0015] In a preferred embodiment, the first and second halves of the planetary gears are alternately distributed. This can further improve the uniform distribution of the first and second forces, as well as the preload in the first rotational direction and the preload in the second rotational direction.

[0016] According to a further embodiment, the first and second forces are greater than the axial force exerted by the helical gear meshing between the double planetary gear and the hollow gear during rotation. Through this distribution between the first and second forces and the axial force, the elastic behavior of the system can be reduced. This means that movement of the double planetary gear in the first and second directions during the operation of the star gear can be avoided.

[0017] In the planetary gears, the first force and the second force are preferably equal. Furthermore, if the number of double planetary gears used is not even, then the sum of the first forces is preferably equal to the sum of the second forces.

[0018] According to a further embodiment, the force-applying component can be a spring element, a magnetic element, and / or a hydraulic element. Of course, any other type of force-applying component is also possible.

[0019] According to a further embodiment, the planetary gear also includes at least one force-limiting component for allowing the two planetary gears to move in one direction, while movement in other directions can be locked. The force-limiting component can be used to allow the two planetary gears to move only in the directions of the first and second forces, while being locked in other directions.

[0020] The locking element can be composed of a ratchet mechanism, which can be closed by force or by forming a lock. This mechanism can be based on principles such as a self-jamming cam or assymetric teeth.

[0021] Further advantages and preferred embodiments of the present invention will be disclosed in the claims, description, and drawings. It should be noted that those skilled in the art can consider or use the presented features individually, or combine these presented features in other undisclosed ways, without exceeding the scope of protection of the present invention. Attached Figure Description

[0022] In the following description, the present invention will be illustrated by way of specific embodiments shown in the accompanying drawings. The specific embodiments shown in the drawings are merely illustrative and are not intended to limit the scope of protection of the invention. The scope of protection of the invention is defined only by the appended claims.

[0023] Figure 1 This is a top view of the planetary gears;

[0024] Figure 2 for Figure 1 The cross-sectional view of the planetary gear shown.

[0025] Explanation of reference numerals in the attached figures

[0026] 1 Planetary Gear

[0027] 2 First hollow wheel

[0028] 4 Second hollow wheel

[0029] 6 First Double Planetary Gear

[0030] 8 Second Double Planetary Gear

[0031] 10 Third Double Planetary Gear

[0032] 12 Fourth Double Planetary Wheel

[0033] 14 The first wheel of the first double planetary wheel

[0034] 16 The second wheel of the first double planetary wheel

[0035] 18 The first wheel of the second double planetary wheel

[0036] 20 The second wheel of the second double planetary wheel

[0037] 22 The first wheel of the third double planetary wheel

[0038] 24 The second wheel of the third double planetary wheel

[0039] 26 The first wheel of the fourth double planetary wheel

[0040] 28 The second wheel of the fourth double planetary wheel

[0041] 30 First rotation direction

[0042] 32 Second rotation direction

[0043] 34 Helical teeth

[0044] 36 First force-applying component

[0045] 38 Second force-applying component Detailed Implementation

[0046] In the following description, the same or similar functional elements are represented by the same denoting numbers.

[0047] Figure 1 The planetary gear 1 is shown, including a first hollow gear 2 and a second hollow gear 4. Planetary gear 1 also includes a first double planetary gear 6, a second double planetary gear 8, a third double planetary gear 10, and a fourth double planetary gear 12. The double planetary gears 6, 8, 10, and 12 can be coupled together by planetary gear carriers (not shown) that can be disposed between them. Planetary gear 1 may also include only one double planetary gear 6, or any other number of double planetary gears 6, 8, 10, and 12. In addition to the hollow gears, a sun gear (not shown) may be used, or to replace one or all of the two hollow gears.

[0048] exist Figure 1 In the illustrated embodiment, the first hollow wheel 2 is larger than the second hollow wheel 4. The first hollow wheel 2 can serve as an input wheel, and the second hollow wheel 4 can serve as an output wheel. In addition, other embodiments and sizes of the hollow wheels 2 and 4, along with the double planetary gears 6, 8, 10, and 12, are also possible.

[0049] The double planetary gears 6, 8, 10, and 12 each contain two gears 14, 16; 18, 20; 22, 24; and 26, 28. The first gears 14, 18, 22, and 26 are in contact with the first hollow gear 2, and the second gears 16, 20, 24, and 28 are in contact with the second hollow gear 4. Due to this contact between the double planetary gears 6, 8, 10, and 12 and the hollow gears 2 and 4, the movement of the first hollow gear 2 in the first rotational direction 30 or the second rotational direction 32 will be transmitted to the second hollow gear 4, or vice versa. The rotational directions 30 and 32 of the hollow gear 24 are indicated by arrows 30 and 32 in the diagram.

[0050] Figure 2 This shows a cross-sectional view of the double planetary gears 6, 8, 10, and 12 combined with the hollow gears 2 and 4. From... Figure 2As can be seen, hollow gears 2 and 4 and double planetary gears 6, 8, 10, and 12 each have helical gears 34. Each helical gear 34 has a first side surface and a second side surface in the opposite direction to the first side surface. The surface normal of the first side surface points to the first rotation direction 30 of the first and second hollow gears 2 and 4, and the surface normal of the second side surface points to the second rotation direction 32 of the hollow gears 2 and 4.

[0051] When the wheels (hollow wheels 2, 4 and double planetary wheels 6, 8, 10, 12, and wheels 14, 16; 18, 20; 22, 24; 26, 28) change their rotational directions 30, 32, i.e., perform forward and backward motion and / or perform alternating motion (oscillating movement) between the two rotational directions, the backlash between the teeth 34 may cause uneven motion (motion profile / motion curve) of the wheels.

[0052] To reduce the backlash between the helical teeth 34 of the two planetary gears 6, 8, 10, 12 (wheels 14, 16, 18, 20, 22, 24, 26, 28) and the hollow wheels 2, 4, one or more force-exerting elements 36, 38 can be provided. The first force-exerting element 36 applies a first force in a first direction, and the second force-exerting element 38 applies a second force in a second direction opposite to the first direction. The first and second directions are perpendicular to the first and second rotational directions 30, 32.

[0053] exist Figure 1 and 2 In the illustrated embodiment, a first force is applied to the first and fourth planetary gears 6, 12, and a second force is applied to the second and third planetary gears 8, 10. Due to the presence of the first force, the first side of the helical teeth 34 of the first gears 14, 26 of the first and fourth planetary gears 6, 12 contacts the second side of the helical teeth of the first hollow gear 2. Furthermore, the second side of the helical teeth 34 of the second gears 16, 28 of the first and fourth planetary gears 6, 12 contacts the first side of the helical teeth of the second hollow gear 4. This contact imparts a preload to the hollow gears 2, 4 in a first rotational direction 30 and a second rotational direction 32.

[0054] Furthermore, due to the presence of the second force, the second side of the helical teeth 34 of the first gears 18 and 22 of the second and third double planetary gears 8 and 10 contacts the first side of the helical teeth of the first hollow gear 2. Additionally, the first side of the helical teeth 34 of the second gears 20 and 24 of the second and third double planetary gears 8 and 10 contacts the second side of the helical teeth of the second hollow gear 4. This contact imparts a preload to the hollow gears 2 and 4 in the first rotational direction 30 and the second rotational direction 32.

[0055] By pressing the first and fourth planetary gears 6 and 12 towards the first hollow gear 2, the helical teeth 34 of the first and fourth planetary gears 6 and 12 contact the helical teeth of the first and second hollow gears 2 and 4. By pressing the second and third planetary gears 8 and 10 towards the second hollow gear 4, the helical teeth 34 of the second and third planetary gears 8 and 10 contact the helical teeth of the first and second hollow gears 2 and 4.

[0056] Due to this preload, the contact between the helical teeth 34 of the hollow wheels 2 and 4 and the helical teeth 34 of the planetary gears 14, 16, 18, 20, 22, 24, 26, and 28 of the double planetary gears 6, 8, 10, and 12 is present at startup. Furthermore, this contact can be maintained by the force-applying components 36 and 38 maintaining the preload during operation, thus preventing backlash between the helical teeth 34.

[0057] The force-applying components 36 and 38 can be implemented, for example, by springs, magnetic elements, hydraulic elements, or any other type of element capable of applying force to the double planetary gears 6, 8, 10, and 12. In a preferred embodiment, the total amount of the first force applied by the first force-applying component 36 is equal to the total amount of the second force applied by the second force-applying component 38.

[0058] Due to the preload on the hollow wheel of the double planetary gear pair in the first and / or second rotational directions, the backlash between the teeth of the double planetary gear and the hollow wheel can be minimized.

Claims

1. A planetary gear (1), comprising at least: A first hollow gear (2) having helical teeth (34) and a second hollow gear (4) having helical teeth (34), wherein the first hollow gear (2) and the second hollow gear (4) are adapted to rotate in a first rotation direction (30) and a second rotation direction (32); as well as A first double planetary gear (6) having a first gear (14) and a second gear (16), wherein the helical teeth (34) of the first gear (14) mesh with the helical teeth (34) of the first hollow gear (2), and the helical teeth (34) of the second gear (16) mesh with the helical teeth (34) of the second hollow gear (4); Each of the bevel teeth (34) has a first side surface and a second side surface opposite to the first side surface, the surface normal of the first side surface points to the first rotation direction (30), and the surface normal of the second side surface points to the second rotation direction (32); Features: The first force applying member (36) applies a first force only in a first direction, so as to make the first side surface of the helical teeth (34) of the first wheel (14) of the first double planetary wheel (6) contact the second side surface of the helical teeth (34) of the first hollow wheel (2), and make the second side surface of the helical teeth (34) of the second wheel (16) of the first double planetary wheel (6) contact the first side surface of the helical teeth (34) of the second hollow wheel (4), thereby giving the hollow wheels (2, 4) preloads in the first and second rotational directions (30, 32).

2. The planetary gear (1) according to claim 1, characterized in that: The planetary gear (1) comprises a second double planetary gear (8) having a first wheel (18) and a second wheel (20), wherein the helical teeth (34) of the first wheel (18) mesh with the helical teeth (34) of the first hollow wheel (2), and the helical teeth (34) of the second wheel (20) mesh with the helical teeth (34) of the second hollow wheel (4); and The planetary gear (1) comprises a second force applying member (38), which applies a second force in a second direction opposite to the first direction, so as to make the second side surface of the helical teeth (34) of the first wheel (18) of the second double planetary gear (8) contact the first side surface of the helical teeth (34) of the first hollow gear (2), and make the first side surface of the helical teeth (34) of the second wheel (20) of the second double planetary gear (8) contact the second side surface of the helical teeth (34) of the second hollow gear (4), thereby giving the hollow gears (2, 4) preloads in the first and second rotational directions (30, 32).

3. Planetary gear (1) according to any one of the preceding claims, characterized in that: The planetary gear (1) comprises an even number of double planetary wheels (6, 8, 10, 12), wherein a first half of the double planetary wheels (6, 12) are given a preload in a first rotational direction (30), and a second half of the double planetary wheels (8, 10) are given a preload in a second rotational direction (32).

4. The planetary gear (1) according to claim 3, characterized in that: The first half and the second half of the double planetary gears (6, 8, 10, 12) are arranged alternately.

5. The planetary gear (1) according to claim 2, characterized in that: The first force and the second force are greater than the axial force applied by the double planetary gears (6, 8, 10, 12) and the hollow gears (2, 4) due to the meshing of the helical teeth (34) during rotation.

6. The planetary gear (1) according to claim 2, characterized in that: The first force and the second force are equal.

7. The planetary gear (1) according to claim 1 or 2, characterized in that: The first force applying component (36) and the second force applying component (38) are spring elements, pneumatic elements, magnetic elements and / or hydraulic elements.

8. The planetary gear (1) according to claim 1 or 2, characterized in that: The planetary gear (1) further comprises at least one force limiting component for allowing the double planetary gears (6, 8) to move in one direction, wherein in particular the movement in the other direction is locked.

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