Flexible gear and gear mechanism including such a flexible gear

Abstract

To provide a gear mechanism in which the interference in the engagement of gear teeth and the gear backlash are reduced, the noise phenomenon and the power transmission are improved and the service life is increased.SOLUTION: A flexible gear wheel includes at least two flexible gear wheel disks arranged adjacently to one another in the axial direction. Each gear wheel disk includes at least two toothed segments in the circumferential direction. The toothed segments are connected to one another by way of spring segments.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a gear mechanism comprising a ring gear, a flexible gear disposed within the ring gear, and a wave generator that contacts the flexible gear and deforms the flexible gear so that the flexible gear partially meshes with the ring gear. [Background technology]

[0002] Such gear mechanisms are known and are used, for example, in robotics. For example, US Pat. No. 5,399,433 discloses an adjustment mechanism for adjusting two components: a ring gear, a driving wheel (driver wheel), a wave generator and an elastic spur wheel (spur wheel). The elastic spur wheel consists of several tooth elements of similar construction. Each tooth element has a head region facing the ring gear and a foot region facing the wave generator. The head region of the tooth elements is provided with gear teeth that can be brought into contact with the ring gear. Furthermore, each tooth element has an outwardly opening hole in its head section, which interrupts the gear teeth and is intended to come into contact with a drive pin of the driving wheel. The tooth elements located adjacent to one another are connected to one another by elastic connecting elements. The wave generator is approximately elliptical in shape and the elastic spur wheel is also elliptical in shape, so that oppositely arranged regions of the elastic spur wheel mesh with the ring gear. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2016 / 165684 Summary of the Invention [Problem to be solved by the invention]

[0004] In such gear mechanisms, the central flex gear may tilt toward the ring gear due to bearing problems, resulting in only a portion of the flex gear's width being engaged for torque transmission, instead of the entire width of the flex gear. Furthermore, manufacturing tolerances may cause flank errors, which may lead to the fact that only a portion of the entire width of the flex gear is used. Thus, circumferential runout tolerances and other manufacturing tolerances may cause interference in the engagement due to geometric deviations.

[0005] Starting from this prior art, the above-mentioned gear mechanism or the flexible gear for this gear mechanism, respectively, is further improved to reduce the interference in gear meshing and gear backlash, improve the noise generation phenomenon and power transmission, and extend the service life. [Means for solving the problem]

[0006] For this purpose, according to the invention, the flexible gear has at least two flexible gear discs arranged adjacent to each other in the axial direction, each flexible gear disc having at least two toothed segments connected to each other in the circumferential direction by spring segments.

[0007] In the present invention, axial direction means along the axis of the ring gear. This direction corresponds approximately to the direction of the central axis of the gear mechanism. As a result of the above-mentioned axial segmentation of the flexible gear into individual flexible gear discs, the face width of each individual flexible gear disc corresponds to a maximum of half of the total gear width. The tilt of each individual gear disc towards the ring gear or towards the central axis of the gear mechanism can be compensated by the other flexible gear discs, respectively. This enhances the meshing of the flexible gear over the entire gear face width, thus significantly reducing the possibility of only partial overlap of the gears or edge support. The individual radial flexibility of the individual flexible gear discs allows for a flexible meshing. Thus, the individual flexible gear discs can rotate slightly relative to each other in the circumferential direction, which reduces the tooth backlash to 0°. Thus, the power transmission, noise generation and gear backlash are improved.

[0008] In an advantageous embodiment of the invention, the flex gear discs adjacent to each other in the axial direction can have the same number of teeth and the same tooth geometry, so that a wider flex gear is formed by the flex gear discs adjacent to each other in the axial direction. Since the gear teeth of the flex gear, i.e. the gear teeth of each flex gear disc, are made up of individual areas that can move relative to each other in the axial direction, the interference in the meshing of each flex gear disc can be compensated by the other flex gear discs, and the interference in the meshing of the entire flex gear can be reduced overall, which can reduce the gear backlash and therefore also improve the noise generation phenomenon and extend the service life.

[0009] It may also be advantageous for the flexible gear discs located axially adjacent to one another to be in mutual support contact, which also takes advantage of the fact that the flexible gear discs form the entire gear with a much larger width and the advantages associated with this.

[0010] By ensuring that the flex gear discs which are axially adjacent to one another have the same axial tooth width, the flex gear can be of a particularly simple shape and uniform construction.

[0011] In yet another advantageous embodiment, the flex gear can have more than two, preferably four, axially adjacent flex gear discs. It has been found that a number of four axially adjacent flex gear discs greatly reduces the possibility of partial overlap of the gears or edge supports, which provides the above-mentioned advantages.

[0012] In a particularly advantageous embodiment, the flexible gear discs are constructed as identical parts, so that the flexible gear is formed by four individual gears, i.e. flexible gear discs, of equal shape arranged adjacent to one another in the axial direction, which simplifies production and saves costs, since the flexible gear discs are constructed as identical parts.

[0013] In yet another embodiment, at least one of the toothed segments of each flexible gear disc has a hole, the flexible gear discs are arranged such that the holes are located above and below and the pin elements are located within the holes located above and below, each of the spring segments of the flexible gear discs has a central plane that includes the central axis of the gear mechanism and divides the respective spring segment into two regions of equal length, each hole has a central plane that includes the central axis of the gear mechanism and divides the hole into regions of equal size, the central plane of each spring segment can be at a different distance from the central plane of the hole located adjacent to the central plane on each side of the central plane of the spring segment. In this way, the flexibility of the flexible gear disc and therefore the flexibility of the entire flexible gear can be increased, and sufficient elastic deformation of the flexible gear disc or the flexible gear, respectively, can still be achieved, especially with small diameters of the gear mechanism. The holes in the individual flex gear discs are one above the other and therefore aligned so that pin elements can be easily inserted into the holes and extend through all of the flex gear discs and therefore through the flex gears.

[0014] It is also possible that at least one of the toothed segments of each flexible gear disc has a constriction in the radial direction of the flexible gear and that the spring segment is connected to the toothed segment in the region of this constriction, so that the spring segment can be made even longer and thus the flexibility of the flexible gear disc can be further increased, which is particularly advantageous at small diameters.

[0015] The spring segments must be configured in such a way that they are elastic in the radial direction and rigid in the tangential direction. In this case, the deformation of the flexible gear disc is achieved only in the radial direction. In the tangential direction, the power can be transferred from one toothed segment to the adjacent toothed segment without the flexible gear disc being deformed. As a result, the gear backlash between the input of the gear mechanism and the output of the gear mechanism can be kept as small as possible. This can be made particularly simple by forming the spring segments as webs that connect the adjacent toothed segments to each other.

[0016] To further increase the flexibility of the flexible gear discs and therefore of the entire flexible gear, each flexible gear disc can have at least one first toothed segment with a hole and at least one second toothed segment without a hole, so that the spring segments extending between the toothed segments can be longer and a good combination of flexibility and strength of the toothed segments is obtained. The force of the gear teeth of the at least one second toothed segment, i.e. the toothed segment without a hole, is transmitted to the at least one first toothed segment via the spring segment. The toothed segment with the waist is preferably the second toothed segment and does not have a hole.

[0017] In yet another embodiment, the spring segment is connected to the at least one first toothed segment at the level of a hole in this at least one first toothed segment, so that the forces of the gear teeth of the at least one second toothed segment are better transmitted to the at least one first toothed segment. The flexibility of the flexible gear disc, and therefore of the entire flexible gear, can be further increased if the spring segment is provided with a relief cutout in the area of ​​contact with the at least one first toothed segment.

[0018] Furthermore, each flexible gear disc has a number of toothed segments, in particular at least four. In this case, it is preferable that each flexible gear disc has an even number of toothed segments, with half of these toothed segments, i.e. the first toothed segments, having holes and the other half, i.e. the second toothed segments, having no holes. This allows a good compromise between the flexibility of the flexible gear disc, and therefore the flexibility of the flexible gear, and sufficient strength.

[0019] In a particularly advantageous embodiment, the holes in the first toothed segment are arranged inside the respective toothed segment and have a closed contour. The pin elements arranged in the holes therefore rotate along a closed circumferential contour, so that the contact between the pin elements and the holes in the corresponding toothed segment is never interrupted. This increases the operational smoothness of the gear mechanism. Advantageously, the holes are designed to have an approximately elliptical shape. Furthermore, in this case, the toothed segments can have gear teeth from end to end in the head area facing the ring gear.

[0020] According to yet another embodiment, each toothed segment of the flexible gear disc can be supported at two support points on the wave generator. In this case, the foot area of ​​the toothed segment facing the wave generator is formed concavely so that this foot area is in contact with the wave generator only at the two support points. The area of ​​the toothed segment formed between the two support points is curved away from the wave generator due to the concave shape of the foot area of ​​the toothed segment, so that no contact is made between the toothed segment and the wave generator here. The angle between the two support points is preferably about 170°. In this way, the alignment of the toothed segment perpendicular to the outer contour of the wave generator can be improved.

[0021] In yet another embodiment, the wave generator comprises at least one cam in contact with the flexible gear, the cam being suitably configured so that in the area where the toothed segments contact the ring gear, the toothed segments deform and form sections of an ideal gear having a constant radius and rotating about an axis at a constant distance from the central axis of the gear mechanism.

[0022] In a simple embodiment, the pin elements can be configured as bolts connected to the output shaft. As a result, the movement of the flex gear is converted via the bolts into a uniform rotational movement of the output. Preferably, a sleeve is arranged on each bolt, forming a sliding bearing with associated advantages. Alternatively, an elastic sleeve or an elastic O-ring can be arranged on each bolt. Alternatively, in a variant of this configuration, the associated hole can be configured to have a circular cross section. In an alternative configuration, the pin elements are configured to be fixed and the ring gear is configured to rotate. In this case, the ring gear is driven by meshing with the flex gear and therefore acts as the output element in this variant.

[0023] In another preferred embodiment, the flex gear disk of the flex gear is formed from a metal or metallic glass.Furthermore, the ring gear which meshes with the flex gear is also preferably formed from a metal or metallic glass.

[0024] In a preferred embodiment, the flexible gear disc has a thickness of about 1.5 mm, a flexible gear having, for example, two flexible gear discs positioned adjacent to each other in the axial direction has a thickness of about 3 mm, and a flexible gear having, for example, four flexible gear discs positioned adjacent to each other in the axial direction has a thickness of about 6 mm.

[0025] In other preferred embodiments, the flexible gear disc has a thickness of about 3 mm, a flexible gear having, for example, two flexible gear discs positioned adjacent to each other in the axial direction has a thickness of about 6 mm, and a flexible gear having, for example, four flexible gear discs positioned adjacent to each other in the axial direction has a thickness of about 12 mm.

[0026] Furthermore, the present invention also relates to a flexible gear for the above-mentioned gear mechanism, in which the flexible gear comprises at least two, preferably four, flexible gear discs positioned adjacent to each other in the axial direction, each flexible gear disc having at least two toothed segments in the circumferential direction, the at least two toothed segments being connected to each other by a spring segment.

[0027] The flexible gear thus comprises several individual gears, i.e. several individual flexible gear discs, which are located axially adjacent to one another. As a result of this axial segmentation of the flexible gear into individual flexible gear discs, the tooth width of one individual flexible gear disc corresponds to a maximum of half the tooth width of the total gear. The inclination of the individual flexible gear discs, and thus the inclination of the gear tooth areas of the individual flexible gear discs, relative to the axis of the ring gear or the central axis of the gear mechanism, can be compensated by the other flexible gear discs, respectively. This increases the meshing of this flexible gear over the entire width of the flexible gear, thus significantly reducing the possibility of only partial overlap of the gears or edge supports. The individual radial flexibility of the individual flexible gear discs allows for a flexible meshing. The individual flexible gear discs thus rotate slightly relative to one another in the circumferential direction, which allows the gear backlash to be reduced to 0°. Power transmission, noise generation and backlash are thus improved.

[0028] In an advantageous embodiment of the flexible gear, at least one of the toothed segments of each flexible gear disc has a hole for receiving a pin element, the flexible gear discs are arranged so that the holes are located one above the other, each of the spring segments has a central plane that includes the central axis of the gear mechanism and divides each spring segment into two areas of equal length, each hole has a central plane that includes the central axis of the gear mechanism and divides the hole into areas of equal size, and the central plane of each spring segment can be at a different distance from the central plane of the hole located adjacent to each side of the central plane of the spring segment. Since the holes in the individual flexible gear discs are located one above the other and therefore coincide with each other, the pin element can be easily inserted and extended through the entire flexible gear according to all the flexible gear discs. In this way, the flexibility of the flexible gear can be increased, so that even if the diameter of the gear mechanism is small, sufficient elastic deformation of the gears can still be achieved.

[0029] In a further preferred embodiment of the flex gear, the flex gear disc is made from a metal or a metallic glass.

[0030] In a preferred embodiment of the flex gear, the flex gear disc has a thickness of about 1.5 mm, a flex gear having, for example, two flex gear discs positioned adjacent to each other in the axial direction has a thickness of about 3 mm, and a flex gear having, for example, four flex gear discs positioned adjacent to each other in the axial direction has a thickness of about 6 mm.

[0031] In further preferred embodiments of the flexible gear, the flexible gear disc has a thickness of approximately 3 mm, a flexible gear having, for example, two flexible gear discs positioned adjacent to each other in the axial direction has a thickness of approximately 6 mm, and a flexible gear having, for example, four flexible gear discs positioned adjacent to each other in the axial direction has a thickness of approximately 12 mm.

[0032] The present invention will be described in detail below with reference to the drawings. [Brief description of the drawings]

[0033] [Figure 1] FIG. 1 is a plan view showing a gear mechanism according to the present invention. [Diagram 2] FIG. 2 is a perspective view showing a flex gear of the gear mechanism of FIG. [Diagram 3] FIG. 3 is a front view of the flex gear disc of the flex gear of FIG. 2; [Figure 4] FIG. 4 is a partial front view showing details of the flex gear disc of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] In the following description, it is to be understood that like elements are designated by like reference numerals. When a reference numeral is included in a drawing that has not been described in detail in the description of the associated drawing, reference is made to the description of the drawing described above or below.

[0035] One embodiment of the gear mechanism 1 of the present invention is shown in Figure 1. The gear mechanism 1 has a housing 10 in which a wave generator 2, a flex gear 6, and a fixed ring gear 9 are arranged. The cover of the housing 10 has been removed to allow the inside of the gear mechanism to be seen. The gear mechanism 1 is generally disk-shaped with a central axis M. The central axis M coincides with the central axis of the ring gear 9.

[0036] The wave generator 2 comprises a base body 3 with a substantially elliptical cross section. Due to this substantially elliptical cross section, two cams 30 are formed on the base body 3 and therefore on the wave generator 2. Also arranged on the base body 3 are rolling elements 4 surrounded by a deformable sleeve 5. The wave generator 2 is arranged in a flex gear 6. The flex gear 6 is therefore in contact with the base body 3 via the deformable sleeve 5 and the rolling elements 4. The elliptical shape of the base body 3 of the wave generator 2 is transmitted to the flex gear 6 via the rolling elements 4 and the deformable sleeve 5, so that the flex gear 6 is deformed into an elliptical shape and thus comes into contact with the ring gear 9 in two meshing regions.

[0037] The flex gear 6 comprises several toothed segments 7.1 and 7.2 which are connected to one another by flexible spring segments 8. The flex gear 6 is provided with external teeth 14 and the fixed ring gear 9 is provided with internal teeth 15. Due to the elliptical deformation of the flex gear 6 caused by the wave generator 2, the external teeth 14 of the flex gear 6 mesh with the internal teeth 15 of the ring gear 9 in oppositely arranged regions, i.e. in the meshing regions.

[0038] In the embodiment shown, the flex gear 6 has 12 toothed segments 7.1, 7.2, which are divided into 6 first toothed segments 7.1 and 6 second toothed segments 7.2. Each of the first toothed segments 7.1 has a hole 17 that is configured as an end-to-end opening inside the respective first toothed segment 7.1. A respective bolt 12 of the pin element 11 is inserted in each hole 17. Each bolt 12 is surrounded by a sleeve 13, forming a sliding bearing. The bolts 12 are connected to the output shaft. The hole 17 is somewhat larger than the sleeve 13. As a result, the bolts 12 can rotate along the hole 17. In the illustrated case, the hole 17 has an elliptical cross section. The cross sections of the bolts 12 and the sleeve 13 are circular. The diameter of the hole 17 is slightly larger than the outer diameter of the sleeve 13.

[0039] The wave generator 2 is preferably connected to a drive shaft, the rotation of which rotates the wave generator 2. This rotational motion is transmitted to the flex gear 6. The external teeth 14 of the flex gear 6 thus run along the internal teeth 15 of the ring gear 9. The spring segments 8 arranged between the toothed segments 7.1 and 7.2 allow a flexible or elastic deformation of the flex gear 6. The motion of the flex gear 6 is converted into a uniform rotational motion of the output via the bolt 12. However, the bolt can also be connected to the housing and therefore fixed. In this case the ring gear acts as the output.

[0040] FIG. 2 shows the flex gear 6 of FIG. 1 in perspective (oblique view). The flex gear 6 is configured in the axial direction, i.e. in the direction of the central axis M, in the form of a segmentation. This means that the flex gear 6 is divided into several flex gear discs arranged axially adjacent to one another. In the illustrated embodiment, the flex gear 6 has four flex gear discs 6.1, 6.2, 6.3 and 6.4. However, it is also possible for the flex gear to have more or fewer flex gear discs. The flex gear discs 6.1 to 6.4 are configured as identical parts and are therefore identical to one another. The structure of these flex gear discs is explained in more detail below with reference to FIG. 3.

[0041] Figure 3 shows a front view of a single flex gear disc 6.1. The other flex gear discs 6.2-6.4 are formed identically to that of Figure 3. Therefore, the following description applies to all flex gear discs 6.1-6.4.

[0042] The flexible gear disc 6.1 is formed as an individual gear and has a first toothed segment 7.1 and a second toothed segment 7.2. The first toothed segments 7.1 and the second toothed segments 7.2 are arranged alternately and are connected to one another by respective spring segments 8. In the illustrated embodiment, the flexible gear disc 6.1 has 12 toothed segments 7.1, 7.2. Every other toothed segment, i.e. the first toothed segment, has a hole 17. In the illustrated case, the holes 17 have an oval shape. However, the holes can also be circular. All the first toothed segments 7.1 are configured identically to one another. The second toothed segments 7.2 are arranged between the first toothed segments 7.1. These second toothed segments 7.2 do not have holes. Adjacent toothed segments 7.1, 7.2 are connected to one another by spring segments 8. The spring segments 8 are configured as arc-shaped webs extending along a circular line, the centre of which in this construction lies on the central axis M of the gear mechanism 1 .

[0043] The shape of the first toothed segment 7.1 and the second toothed segment 7.2 will be explained in more detail below: Each of the first toothed segments 7.1 has a foot region 18, which is brought into contact with the wave generator 2. Starting from the foot region 18, a trunk region 19 extends radially outwards, in which a hole 17 is formed. The hole 17 therefore has a closed contour in the interior of the toothed segment 7.1. The bolt 12 or the sleeve 13, respectively, rotates along this closed contour. As a result, the contact of the bolt 12 or the sleeve 13 with the hole 17 is never interrupted, which increases the sliding of the gear mechanism 1. A head region 20 adjoins the trunk region 19 in the radial direction. The external teeth 14 are formed on the outward circumferential surface of the head region 20 of each first toothed segment 7.1. Since the hole 17 is arranged in the interior of the first toothed segment 7.1, the external teeth 14 extend over the entire outward circumferential surface of the first toothed segment 7.1. If we now consider the width of the first toothed segment 7.1 in the circumferential direction U of the flexible gear disc 6.1, this first toothed segment 7.1 has a first width in the foot region 18, which tapers in the body region and increases again towards the outside, so that the first toothed segment 7.1 has its maximum width at the outer periphery.

[0044] The second toothed segment 7.2 also has a foot region 21 which is in contact with the wave generator 2. A body region 22 which transitions into a head region 23 adjoins this foot region 21 radially and outwardly in the case of this second toothed segment 7.2 as well. This second toothed segment 7.2 does not have a hole. Instead, this second toothed segment 7.2 is significantly constricted in the body region 22 and therefore has a waist 24. In this case too, the external teeth 14 are formed on the outward circumferential surface of the head region 23 of the second toothed segment 7.2.

[0045] Each of the first and second toothed segments 7.1 and 7.2 is connected to the adjacent toothed segment 7.2 and toothed segment 7.1, respectively, by a spring segment 8. The spring segments 8 are configured as arc-shaped webs lying on a circular line in the circumferential direction of the flexible gear disc 6.1. The spring segments 8 are connected to the first toothed segment 7.1 approximately at the level of the center of the hole 17. The connection between the spring segment 8 and the second toothed segment 7.2 is made at the level of the waist 24. As can be clearly seen in FIG. 3, the flexible gear disc 6.1 is made in one piece.

[0046] The second toothed segment 7.2, which has no hole, ensures that the force of the gear tooth is transmitted via the spring segment 8 to the first toothed segment 7.1, which has a hole 17. In this way, the spring segments 8 can be made large, which increases their flexibility and still ensures that sufficient elastic deformations are achieved even with small diameters of the gear mechanism 1. The shape of the spring segments 8 shown ensures that they are as inelastic as possible in the tangential direction, but only in the radial direction.

[0047] Each of the spring segments 8 is aligned along a central plane M that includes the central axis M of the gear mechanism 1 and divides each of the spring segments 8 into two regions of equal length. FS Since the spring segments 8 are formed of webs in the shape of a circular arc, this length corresponds to the length of the arc. Each of the holes 17 also has a central plane M which includes the central axis of the gear mechanism 1 and divides each hole 17 into two regions of equal size. A The spring segments 8 between the toothed segments 7.1 and 7.2 are formed asymmetrically, and the central plane M of each spring segment 8 is FS is the center plane M of the two adjacent holes 17. A Therefore, the central plane M of each spring segment is at a different distance from FS and two central planes M arranged adjacent to it. A The distance between can be expressed as angles of different magnitudes.

[0048] The detail III in FIG. 3 is shown enlarged in FIG. 4. In FIG. 4, the first toothed segment 7.1 and the second toothed segment 7.2 are shown. As mentioned above, the first toothed segment 7.1 has a foot region 18, a body region 19 and a head region 20. The hole 17 is located in the body region 19 of the first toothed segment 7.1. The external teeth 14 are formed in the head region 20. The second toothed segment 7.2 also has a foot region 21, a body region 22 with a waist 24 and a head region 23. The external teeth 14 are formed on the outward circumferential surface of the head region 23. Both the foot region 21 of the second toothed segment 7.2 and the foot region 18 of the first toothed segment 7.1 have concave recesses so that each of the toothed segments 7.1 and 7.2 is supported on the wave generator 2 with two support points. This improves the alignment of the toothed segments 7.1 and 7.2 perpendicular to the outer contour of the wave generator 2. The concave recess has an opening angle β of approximately 170°.

[0049] The spring segments 8 are connected to the first toothed segment 7.1 approximately at the level of the bore 17. The spring segments 8 have a relief cut 25 in the area where they transition to the first toothed segment 7.1, which makes it possible to increase the flexibility of the flex gear 6 in the transition area from the spring segments 8 to the first toothed segment 7.1.

[0050] The spring segment 8 is connected to the second toothed segment 7.2 at the level of the waist 24. This second toothed segment 7.2 has a very small width in this region, so that the flexibility provided here is sufficient. The toothed segments 7.1 and 7.2, which are located adjacent to each other, are arranged at a distance from each other both in the head region and in the foot region.

[0051] As is clear from FIG. 4, the first toothed segment 7.1 may have a different number of teeth than the second toothed segment 7.2. The number of teeth of the flex gear 6 is therefore not an integer multiple of the number of the toothed segments 7.1 and 7.2. The number of the toothed segments 7.1 and 7.2 is therefore not determined by the number of teeth of all the flex gears 6. The number and / or arrangement of the teeth in the toothed segments 7.1 and 7.2 is therefore not necessarily uniform. In order to ensure that all the teeth in the toothed segments 7.1 and 7.2 have the same shape, the geometry of the wave generator 2, i.e. the cross-sectional shape of an ellipse with two cams arranged opposite each other, can be selected so that a constant radius extends in the region of the higher elevations over the angle of the tooth meshing. By ensuring that all the toothed segments 7.1 and 7.2 are located in this section, i.e. within this angle, an ideal gear with a constant radius and rotating about an axis is obtained. This axis is located at a distance from the central axis M of the gear train 1. The distance in this case has a length ratio smaller than 10% compared to the radius of the ring gear. The only boundary condition is that the distance between two external teeth located on adjacent gear train elements 7.1 and 7.2 is an integer multiple of the tooth width in this region. At present, this tooth width is defined as twice the distance between two adjacent teeth of the external toothing 14.

[0052] In the following, the structure of the flexible gear 6 will be explained in detail again with reference to FIG. 2. The flexible gear has four flexible gear discs 6.1, 6.2, 6.3 and 6.4. The four flexible gear discs 6.1-6.4 are constructed as individual gears as already explained with reference to FIGS. 3 and 4. The flexible gear discs 6.1-6.4 are arranged in the axial direction so that their front faces are in contact with each other. The flexible gear discs 6.1-6.4 are also aligned in the circumferential direction so that the second toothed segments 7.2 of all the flexible gear discs 6.1-6.4 are located one above the other. Accordingly, the first toothed segments 7.1 of all the flexible gear discs 6.1-6.4 are also located one above the other. Accordingly, the holes 17 of all the flexible gear discs 6.1-6.4 are also approximately coincident and extend in the axial direction M over the entire width B of the flexible gear 6. The sleeves 13 are placed in the holes 17, and the bolts 12 are inserted in these sleeves. The flexible gear discs 6.1-6.4 are thus first supported in the teeth of the ring gear and then respectively on the bolts 12 or on the pin elements 11. In this way, torque transmission is possible.

[0053] Each of the flex gear discs 6.1 to 6.4 can be individually tilted slightly perpendicularly to the central axis M. As a result, tilts of one flex gear disc relative to the central axis M or to the axis of the ring gear, e.g. due to bearing problems, can be compensated by the other flex gear discs respectively. Flank errors of the individual flex gear discs, e.g. caused by manufacturing tolerances, can also be compensated by the other flex gear discs.

[0054] Each of the flexible gear discs 6.1-6.4 can be slightly offset from one another in the circumferential direction, allowing flexible engagement of the tooth engagement areas of the individual flexible gear discs with the teeth of the ring gear, thereby reducing backlash to 0°. [Explanation of symbols]

[0055] 1 → Gear mechanism 2 → Wave generator 3→Substrate 4 → Rolling element 5 → Deformable sleeve 6 → Flexible gear 6.1 → Gear disc 6.2 → Gear disc 6.3 → Gear disc 6.4 → Gear disc 7.1 → 1st toothed segment 7.2 → 2nd toothed segment 8 → Spring segment 9 → Ring gear 10 → Housing 11 → Pin element 12 → Bolt 13 → Sleeve 14 → Outer teeth 15 → Inner teeth 17 → Hole 18 → Foot area of ​​the first toothed segment 19 → Body area of ​​the first toothed segment 20 → Head area of ​​the first toothed segment 21 → Foot area of ​​the second toothed segment 22 → Body area of ​​the second toothed segment 23 → Head area of ​​second toothed segment 24 → Waist 25 → Relief cut-out section M → central axis of the gear mechanism U → Circumferential direction B → Width of flexible gear M FS → Center plane of spring segment M A → Hole center plane β → opening angle

Claims

1. A gear mechanism (1) comprising a ring gear (9), a flexible gear (6) arranged in the ring gear (9), and a wave generator (2) in contact with the flexible gear (6) and deforming the flexible gear (6) so that the flexible gear partially meshes with the ring gear (9), the flexible gear (6) having at least two flexible gear discs (6.1, 6.2, 6.3, 6.4) arranged adjacent to each other in the axial direction, wherein each flexible gear disc (6.1, 6.2, 6.3, 6.4) has at least two toothed segments (7.1, 7.2) connected to each other in the circumferential direction (U) by a spring segment (8), and the gear teeth (14) of the flexible gear (6), i.e. the gear teeth of each flexible gear disc (6.1, 6.2, 6.3, 6.4), consist of individual areas which can move relative to each other in the axial direction.

2. 2. The gear mechanism (1) according to claim 1, characterized in that the flexible gear discs (6.1, 6.2, 6.3, 6.4) located adjacent to each other in the axial direction have the same number of teeth and the same tooth geometry.

3. 3. A gear mechanism (1) according to claim 1 or 2, characterized in that the flexible gear discs (6.1, 6.2, 6.3, 6.4) which are axially adjacent to each other are in contact with and support each other.

4. The gear mechanism (1) according to any one of claims 1 to 3, characterized in that the flexible gear discs (6.1, 6.2, 6.3, 6.4) located adjacent to each other in the axial direction have the same face width in the axial direction.

5. A gear mechanism (1) according to any one of claims 1 to 4, characterized in that the flexible gear (6) has more than two, preferably four, flexible gear discs (6.1, 6.2, 6.3, 6.4) positioned adjacent to one another in the axial direction.

6. The gear mechanism (1) according to any one of the preceding claims, characterized in that the flexible gear discs (6.1, 6.2, 6.3, 6.4) are constructed as one and the same part.

7. A gear mechanism (1) according to claim 6, characterized in that at least one (7.1) of the toothed segments of each flexible gear disc (6.1, 6.2, 6.3, 6.4) has a hole (17), the flexible gear discs (6.1, 6.2, 6.3, 6.4) are arranged such that the holes (17) are arranged side by side along the central axis (M) of the gear mechanism (1) and that pin elements (11) are arranged in the holes (17) arranged side by side along the central axis (M) of the gear mechanism (1), and each of the spring segments (8) of the flexible gear discs is arranged in a central plane (M) which includes the central axis (M) of the gear mechanism (1) and divides each of the spring segments (8) into two regions of equal length. FS ), and each hole (17) has a central plane (M A ), and this central plane (M A ) includes the central axis (M) of the gear mechanism (1) and divides the hole (17) into equal sized areas, and the central plane (M FS ) is the central plane (M FS ) on each side of this central plane (M FS The central plane (M) of the hole (17) located adjacent to A ) at different distances from each other.

8. A gear mechanism (1) according to any one of claims 1 to 7, characterized in that at least one of the toothed segments (7.1, 7.2) of each flexible gear disc (6.1, 6.2, 6.3, 6.4) has a constriction (24) in the radial direction of the flexible gear (6), and the spring segment (8) is connected to the toothed segment (7.2) in the area of ​​the constriction (24).

9. 9. A gear mechanism (1) according to any one of claims 1 to 8, characterized in that the spring segments (8) are configured so as to be radially elastic and tangentially rigid, preferably in that the spring segments (8) are formed as webs connecting adjacent toothed segments (7.1, 7.2).

10. A gear mechanism (1) according to any one of claims 7 to 9, characterized in that each flexible gear disc (6.1, 6.2, 6.3, 6.4) comprises at least one first toothed segment (7.1) provided with a hole (17) and at least one second toothed segment (7.2) provided with no hole.

11. A gear mechanism (1) according to any one of claims 7 to 10, characterized in that the spring segment (8) is connected to at least one first toothed segment (7.1) at the level of a hole (17) in said at least one first toothed segment (7.1).

12. 12. A gear mechanism (1) according to any one of claims 1 to 11, characterized in that each flexible gear disc (6.1, 6.2, 6.3, 6.4) has a plurality of toothed segments (7.1, 7.2), in particular at least four toothed segments (7.1, 7.2).

13. 13. The gear mechanism (1) according to any one of claims 1 to 12, characterized in that the holes (17) in the first toothed segment (7.1) are arranged inside the respective toothed segment (7.1) and have a closed contour.

14. A flexible gear (6) for a gear mechanism (1) according to any one of claims 1 to 13, comprising at least two, preferably four, flexible gear discs (6.1, 6.2, 6.3, 6.4) positioned adjacent to one another in the axial direction, each flexible gear disc (6.1, 6.2, 6.3, 6.4) comprising at least two toothed segments (7.1, 7.2) in the circumferential direction, the at least two toothed segments being connected to one another by a spring segment (8).

15. A flexible gear (6) according to claim 14, wherein at least one (7.1) of the toothed segments of each flexible gear disc (6.1, 6.2, 6.3, 6.4) has a hole (17) for receiving a pin element, the flexible gear discs (6.1, 6.2, 6.3, 6.4) are arranged such that the holes (17) of the flexible gear discs (6.1, 6.2, 6.3, 6.4) are positioned side by side in a direction along a central axis (M) of the gear mechanism (1), and each of the spring segments (8) is aligned with a central plane (M FS ), and this central plane (M FS ) contains the central axis (M) of the gear mechanism (1) and divides each of the spring segments (8) into two regions of equal length, and each hole (17) is aligned with the central plane (M A ), and this central plane (M A ) contains the central axis (M) of the gear mechanism (1) and divides the hole (17) into equal sized areas, and the central plane (M) of each spring segment (8) FS ) is the central plane (M FS ) on each side of this central plane (M FS The central plane (M) of the hole (17) located adjacent to A ) at different distances from each other.

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