JP2004092831A - Planetary gear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a planetary gear generating minimum backlash to the utmost. <P>SOLUTION: The planetary gear having a planetary carrier rotatable around a rotating shaft is furnished with at least one planetary wheel 3, a solar wheel 4 and a ring gear 5 arranged on the planetary carrier. The planetary wheel is arranged movable at least in one radial direction against the rotating shaft of the planetary carrier. The ring gear is formed of two parts on a flat surface perpendicular to the rotating shaft of the planetary carrier to minimize the backlash of this kind of planetary gear. The two halves of the ring gear can rotate in the opposite direction each other, and consequently, the planetary wheel shifts in the radial direction and reduces the backlash in the direction of the solar wheel. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a planetary gear comprising a carrier rotatable about an axis of rotation, at least one planet wheel disposed on the carrier, a sun wheel, and a ring gear. Here, the planet wheels are arranged such that they can move at least radially with respect to the axis of rotation of the carrier.
[0002]
BACKGROUND OF THE INVENTION
A planetary gear of this type is known from German Patent Application DE 195 46 586 and European Patent Application EP 0 779 449. The radial mobility of the planet wheels with respect to the carrier significantly increases the service life in known planetary gears, which is clearly the result of the fact that static overdefinition is avoided. However, the requirement for planetary gears not only for long life but also for no backlash is gradually increasing, especially in certain applications.
[0003]
[Means for Solving the Problems]
It is therefore an object of the present invention to design a planetary gear of the type described above such that backlash occurs as little as possible.
[0004]
For this purpose, the invention provides that the ring gear is formed from two parts on a plane perpendicular to the axis of rotation of the carrier. Here, the two halves of the ring gear can rotate in opposite directions, thereby causing a radial shift of the planet wheel in the direction of the sun wheel to reduce backlash.
[0005]
Planetary gears with split ring gears are known per se. For this purpose, reference is made, for example, to the German patent application DE 37 38 607 A1. Known multi-stage planetary gears also have split ring gears and further have split planet wheels. By rotating the ring gear halves opposite each other by adjusting the screw, the two planet wheels are positioned opposite each other, thereby avoiding possible backlash between the ring gear and the planet wheels. However, its disadvantage is that only one half of the root surface of the sun wheel for one direction of rotation works. If the same power is transmitted by this gear, as transmitted by a conventional planetary gear, the axial total length of the gear is forcibly increased. In contrast, the gears according to the invention are such that only the ring gear is split and the planet wheels are not split. Instead, the planet wheel is supported so that it can move radially, so that when rotating one half of the ring gear, a backlash between the planet wheel and the ring wheel occurs due to a radial shift towards the sun wheel. Not only is the backlash reduced, but also the backlash between the sun and planet wheels. Advantageously, the root surface of the sun wheel traverses the entire axial length of the sun wheel, so that the overall planetary gear does not need to be resized despite the reduction in backlash.
[0006]
According to an embodiment of the present invention, half of the two ring gears can be fixed to each other. For example, this can be accomplished by securing one half of the ring gear to the housing, while the other half of the ring gear is fixed to one half of the fixed ring gear until the desired release from backlash is achieved. On the other hand, it can be rotated by the adjusting screw.
[0007]
In another embodiment, the two halves of the ring gear are spring resiliently positioned tangentially to each other. For this purpose, one half of the ring gear may be fixed again in the housing, while the other half of the ring gear is rotatably arranged with respect to the fixed half of the ring gear, The other half is spring supported on the housing. The strength of the spring is selected by the size of the gear and the torque transmitted.
[0008]
A particularly preferred embodiment provides a combination in which two half of the ring gears are pre-positioned with spring resilience and the half of these ring gears remain relatively fixed. For this embodiment, the two halves of the ring gear can be spring-positioned with respect to each other simply by eliminating the backlash created during idling or under very light loads. The two halves of the spring are then fixedly positioned with one another, for example by means of bar screws, so that the spring does not transmit torque.
[0009]
According to a preferred embodiment, the two halves of the ring gear may be coupled to one another via a gear train, wherein the axial movement of the elements of the gear train causes the two halves of the ring gear to move together. Rotate. Such a gear train, which may for example be a tapered gear, has the advantage that backlash elimination can be adjusted from the front side of the gear. With the gears installed, it is particularly advantageous if the backlash has to be readjusted and the radial accessibility of the gears is not guaranteed.
[0010]
A particularly simple gear train can be realized if at least one of the two halves of the ring gear can move axially with respect to the other half of the ring gear. The axially movable half of the ring gear may then be connected to the axially and tangentially fixed half of the ring gear via a tapered gear, whereby
A movable axial shift of the ring gear results in a mutual rotation of the two halves of the ring gear.
[0011]
Such a connection of the ring gear halves via a gear train is particularly advantageous if the ring gear halves of several gear stages are connected to one another. Then, all gear stages of the planetary gear can be adjusted for backlash free by one single operation of the gear train.
[0012]
A preferred embodiment of the present invention allows two half of the ring gear of the planetary gear to be axially positioned, and the two half of the ring gear are connected tangentially to each other via a spring. This causes the two half ring gears to rotate relative to each other while the two half ring gears are not positioned axially. As mentioned above, the strength of the spring is chosen such that after opening the coupling screw, two halves of the ring gear rotate relative to each other, which causes the planet to radiate until backlash compensation is obtained. Will be shifted. After reaching this backlash compensation, the axial locking screws are locked, so that the two halves of the ring gear can be locked with respect to each other. In the absence of this backlash, the spring does not transmit any load. Therefore, the strength of the spring does not match the torque transmitted by the gear.
[0013]
In particular, a solution which is simple to implement is that the two halves of the ring gear are connected to each other via at least one fastening screw arranged parallel to the axis of rotation passing through them, In at least one of the halves, the screw holes have a backlash tangential to the ring gear so that half of the ring gear may move tangentially with respect to the screw. This means that the screw can be tangentially fixed to one half of the ring gear, and the other half of the ring gear is provided with holes with tangential backlash, which allows two half of the ring gear The two can rotate slightly with respect to each other. Since the backlash to be eliminated by the gear is usually not very large, the dimensional difference between the hole and the outer diameter of the fixing screw is relatively small and sufficient.
[0014]
In a particularly structurally simple manner, springs provided for rotation of one half of the ring gear to one another can be arranged, wherein in the movable half of the ring gear a recess opening for accommodating a compression spring is provided. Provided in the bore, the compression spring is radially supported with respect to the screw.
[0015]
In a multi-stage planetary gear, it is advantageous if both halves of the ring gear are penetrated by fixing screws.
[0016]
It is also advantageous if at least two opposing fixing screws are arranged, especially when higher torques are transmitted by gears.
[0017]
It is advantageous for simple installation and simple manufacture of the ring gear if two half of the ring gear have a centering recess where the two half of the ring gear meshing with the centering collar are joined. The individual halves of each stage ring gear can be stacked in a tower shape, the only degree of freedom remaining is the rotation of the stages in the tangential direction, i.e. this is necessary to adjust the degrees of freedom of the gear. The degree of freedom.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0019]
In the figure, a planetary gear with a planet carrier 2 rotating around a gear axis 1, a planet wheel 3 and a sun wheel 4 is shown. The planet carrier 2 is surrounded by a ring gear 5 whose teeth mesh with the teeth of the planet wheel 3. The ring gear 5 is divided into two halves 5 'and 5''. One half 5 is fixedly connected to the housing 6 and the other half 5 'can be rotated with respect to the first half. As can be seen from FIGS. 1 and 2, the rotation is enabled by an adjusting screw 7 whose thread engages on the one hand a bearing base 8 of the movable half 5 ″ of the ring gear, the other end of which is the ring gear. Is supported by a support block 9 'which is connected to a fixed half 5' of the same.
[0020]
With a radial backlash that allows the planet wheel 3 to move radially between the sun wheel 4 and the ring gear 5, the planet wheel 3 is placed on a mandrel journal 10 of the planet carrier 2. This mobility can be better understood, in particular, from FIG. To achieve this mobility, as shown in FIG. 2, the mandrel journal 10 is preferably formed in an oblong shape, whereby the planet wheels have radial rather than circumferential backlash.
[0021]
Hereinafter, the operation of the present invention will be described.
[0022]
By rotating the adjusting screw 7, the two halves 5 'and 5''of the ring gear rotate in opposite directions. Thereby, the distance of the root surface of the ring gear engaging the planetary wheel is reduced. This reduction in distance, on the one hand, leads to the fact that the backlash between the teeth of the planet wheels and those of the ring gear 5 is reduced. As soon as this backlash is zero, the other rotation of the ring gear halves 5 ′ and 5 ″ will cause the planet to radiate inward in the direction of the sun wheel 4, as the root surfaces contact each other on both sides. The movement of the wheel 3 is performed. This radial shift results in stronger tooth engagement between planet wheel 3 and sun wheel 4 until backlash between planet wheel 3 and sun wheel 4 is minimized. As soon as this state is reached, the adjusting screw 7 is no longer turned and is fixed in this position. This can be done, for example, by a thin nut, not shown here in detail, or other known means. The planetary gears, which are adjusted here to have no backlash, are characterized by the fact that the planetary wheel meshes with and engages with the ring gear across only half of the axial length of the tooth side, whereas the planetary wheel is 4 engages with the entire shaft length, where the highest load occurs. Thus, this kind of reduction in backlash allows maintenance of structures as small as possible.
[0023]
Hereinafter, another embodiment of the gear will be described with reference to FIG. 3 as an example of a multi-stage planetary gear. For clarity, only the differences will be referenced as compared to the above-described embodiment.
[0024]
The multi-stage design of the planetary gear according to FIG. 3 is achieved in that the planet carrier communicates on its rear side to the sun wheel 11, which is formed integrally with the planet carrier 3. The second stage further comprises the planet carrier 12 on its mandrel journal 13 and the planet wheel 14 is supported for radial movement and rotation. The planet wheel 14 is surrounded by a ring gear 15 which is divided into two halves 15 'and 15''.
[0025]
The ring gear halves 5 ′ and 15 ′ are fixedly connected to the housing 6 by, for example, a press sheet or other means ensuring a secure mounting. As in the other embodiments, the movable halves 5 "and 15" are not only rotatable in the circumferential direction but also in the axial direction indicated by the respective arrows. On the front faces facing each other, the ring gear halves 5 ′ (and 15 ′) and 5 ″ (and 15 ″) have a radial engagement 16. If the axially movable halves 5 ″ and 15 ″ move axially towards the fixed halves 5 ′ and 15 ″ of the ring gear, respectively, this radial engagement 16 Rotate 5 ″ and 15 ′, 15 ″ in opposite directions. This movable axial movement of the ring gear is achieved in the embodiment of FIG. 3 by an adjusting screw 7 which engages a thread located in the housing 6. The end remote from the screw head is supported on the front side of the ring gear 15 ″.
[0026]
A plurality of such adjusting screws 7 may be provided around the circumference of the planetary gear housing for more regular power distribution. For clarity, these adjustment screws are not shown.
[0027]
The recess 17 is arranged outside the ring gear 15 ″, and the connecting element 18 engages with the recess. At the other end, the coupling element 18 engages a recess 19 in the half 5 ″ of the ring gear. The coupling element 18 is substantially rigid, but may include a spring 20 that allows for a predetermined amount of backlash compensation.
[0028]
The operation of the embodiment according to FIG. 3 will be described in detail below.
[0029]
The frictional connection of the gears is performed in a known manner. An input shaft (not shown) drives the sun wheel 4. This sun wheel drives the planet carrier 3 that moves the ring gear 5 and thus rotates the set of planet carriers 2. In the second stage, the sun wheel 11, the planet carrier 14 and finally the planet carrier 12 are driven, the latter being connected to the output shaft. As in the embodiment described above, the ring gear halves 5 ', 5 "and 15', 15" are re-engaged to eliminate backlash between the ring gear components, the planet wheel and the sun wheel. Rotated in opposite directions. This rotation is achieved by screwing the adjusting screw 7 into the housing. Due to the support of the adjusting screw 7 on the front side of the ring gear 15, the half 15 '' of the ring gear shifts axially to the left. In this state, the tooth surfaces of the radial meshing 16 in the respective ring gear halves 5 ', 5 "and 15', 15" respectively contact each other. Thus, the axial shift of the ring gear half 15 ″ not only causes the ring gear half 15 ″ to move axially, but also rotates circumferentially with respect to the ring gear half 15 ′. At the same time, the axial movement of the ring gear half 15 ″ is transmitted via the connecting element 18 onto the ring gear half 5 ″. Thus, half 5 ″ of the ring gear moves axially and, due to radial engagement 16, half 5 ″ of the ring gear rotates circumferentially with respect to half 5 ′ of the ring gear. Thus, backlash in each stage of the multi-stage planetary gear can be minimized by one operation. Since the backlash cannot be assumed to be the same at each stage, a spring 20 may be provided on the coupling element 18, as shown in FIG. 3, which compensates for the overload. Such a spring can also be incorporated into the adjusting screw 7 in order to take into account a predetermined life of the root surface.
[0030]
Although not shown, the multi-stage gear also includes other stages that are connected together in a similar manner.
[0031]
4 and 6 show another embodiment of the present invention, and only the differences from the above-described embodiment will be described. Wherever possible, the same reference numbers will be used for the same components.
[0032]
The basic difference from the embodiment described above is that the individual ring gear halves 5 ′, 5 ″ are rotated relative to each other by a spring 20, which are then axially positioned relative to each other by a fixing screw 21. .
[0033]
The configuration of this arrangement is particularly well shown in FIG. Here, two ring gears 5 and 15 are provided, each having half 5 ′ and 5 ″ and 15 ′ and 15 ″ of the ring gear.
[0034]
The two ring gears 5 and 15 are covered by lids 22 and 23 on the front side. Like the ring gears 5 and 15, the lid is penetrated by an axial hole. The holes 24 in the two halves 5 ′ and 15 ′ of the ring gear and the lids 22 and 23 correspond almost exactly to the diameter of the fixing screw 21, and a thread is also provided on the lid 23. The holes 25 in the ring gear halves 5 "and 15" have a large diameter, so that when tightened when the fixing screw is not fixed, two of these ring gear halves will have the other ring gear halves. It can rotate with respect to the halves 5 'and 15'.
[0035]
Furthermore, it can be easily seen from FIG. 5 that, like the ring gear halves 5 ′ and 15 ″, the lids 22 and 23 also have a centering recess 26 and a centering collar 27 respectively,
The centering collar of one half of the ring gear fits into the centering recess of the other half of the ring gear.
[0036]
It can be seen from FIG. 6 that a recess 28 that opens radially in the hole 25 is provided tangentially to the half 5 ″ of the ring gear, in which case the spring 20 formed as a pressing spring is May be inserted. FIG. 6 shows that the spring 20 is supported at the bottom of the recess 28 and is radially supported by a fixing screw 21.
[0037]
The operation of the embodiment according to FIGS.
[0038]
First of all, the entire ring gear of the planetary gear is assembled such that all the teeth in the individual halves of the ring gear are aligned. After assembling the individual planet carriers and the entire planet gear, ie the planet gears, the fixing screw 21 is released. This may cause the spring 20 to rotate the respective halves 5 "and 15" of the ring gear with respect to the fixed halves 5 'and 15 "of the ring gear. This rotation causes the planet gears to move more inward, as in the embodiment described above, which results in a backlash between the planet gears and the sun wheel on the one hand, and a backlash between the ring gears and the planet gears on the other hand. Be minimized. This backlash compensation may be supported in that the gear shaft rotates when the locking screw is released. After the backlash has been minimized by the effect of the pressing spring 20, the fixing screw 21 is tightened again, so that the ring gear halves 5 'and 5 "and 15' and 15" are respectively fixedly arranged with each other. Is done. The gears are now adjusted to have no backlash. If the backlash occurs again during use due to the life of the gear, the backlash due to the life is removed as described above, where the fixing screw is temporarily loosened and then re-tightened.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view showing a planetary gear according to the present invention.
FIG. 2 is a schematic front view showing the planetary gear of FIG.
FIG. 3 is a schematic sectional view showing a multi-stage planetary gear according to an embodiment of the present invention.
FIG. 4 is a schematic side view of a planetary gear according to another embodiment.
FIG. 5 is a partial sectional view of the embodiment according to FIG. 4;
FIG. 6 is a sectional view along the line VI-VI of the gear according to FIG. 5;

Claims (12)

A planetary gear, wherein the planetary gear is rotatable about an axis of rotation (1), a planetary carrier (2), at least one planetary wheel (3) disposed on the planetary carrier (2), a sun wheel (4). And a ring gear (5), the planet wheel (3) being arranged to be movable at least radially with respect to the axis of rotation (1) of the planet carrier (2);
The ring gear (5) is split in two on a plane perpendicular to the axis of rotation (1) of the planet carrier (2), the two halves (5 ', 5'') of the ring gear (5') being opposite to each other The halves (5 ′, 5 ″) radially shift the planet wheels (3) in a direction that can rotate in the direction and the sun wheel (4) reduces backlash. , Planetary gears. The planetary gear according to claim 1, characterized in that the two halves (5 ', 5 ") of the ring gear can be fixed relative to each other. 3. The planetary gear according to claim 1, wherein the two halves of the ring gear are positioned relative to one another in a tangential direction by spring resilience (spring 20). 4. The two halves (5 ′, 5 ″) of the ring gear are connected to one another via a gear train (5 ′, 16, 5 ″) so that the axial movement of the gear train elements (5 ″) is reduced. 4. The planetary gear according to claim 1, wherein the two halves of the ring gear rotate in opposite directions. The planetary gear according to claim 4, characterized in that at least one of the ring gear halves (5 ") is axially movable with respect to the other half (5 ') of the ring gear. A plurality of gear stages are formed on the planetary gear, and gear trains of half (5 ′, 5 ″; 15 ′, 15 ″) of the ring gear in several gear stages are connected to each other, The planetary gear according to claim 4. Two of the ring gear halves (5 ', 5 "; 15', 15") can be axially positioned and two of the ring gear halves are tangential via springs (20) , So that two of the ring gear halves (5 ′, 5 ″; 15 ′, 15 ″) rotate while two of the ring gears are not axially positioned. The planetary gear according to any one of claims 1 to 6, characterized in that: The half (5 ′, 5 ″; 15 ′, 15 ″) of the ring gear is arranged parallel to the rotation axis (1), and the half of the ring gear (5 ′, 5 ″; 15 ′, 15 ″). ) Are connected to each other by at least one of the fixing screws (21) extending axially therethrough, and in at least one of the ring gear halves (5 ", 15") holes (7) for the fixing screw (21). 25) has a backlash in the tangential direction of the ring gear (5, 15) and half of the ring gear (5 ', 5 "; 15', 15") is tangential to the fixing screw (21). The planetary gear according to any one of claims 1 to 7, wherein the planetary gear is movable. A recess (19) opening in a hole (25) for accommodating a pressing spring (20) is provided in the movable half (5 ″, 15 ″) of the ring gear, and this pressing spring is screwed (21). The planetary gear according to any one of claims 1 to 8, characterized in that the planetary gear is supported in the radial direction by (1). The planetary gear is formed with a plurality of steps, and all the halves (5 ′, 5 ″; 15 ′, 15 ″) of the ring gear are passed through the fixing screw (21). Item 10. The planetary gear according to any one of Items 1 to 9. The planetary gear according to claim 1, wherein the two fixing screws are arranged opposite each other. Two of the ring gear halves (5 ′, 5 ″; 15 ′, 15 ″) each have a positioning recess (26) and have a ring gear half (5 ′, 5 ′, 5 ′, 15 '', 15 '') are adjacent to one another.

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