WO2006034921A1 - Eccentric gearbox comprising a cycloidal lantern gearing - Google Patents

Abstract

The invention relates to an eccentric gearbox (10), and to a method for producing the same, said gearbox comprising a cycloidal lantern gearing, and used to regulate two parts of a motor vehicle which are arranged in such a way that they can be displaced in relation to each other. The inventive gearbox comprises an eccentric gear (16) which is eccentrically driven by a rotary drive (12) and partially engages in an inner ring (20, 22), said inner ring comprising essentially at least semicylindrical tooth elements (24, 28, 52) that engage in the outer gearing (18, 42) of the eccentric gear (16). The inventive gearbox also comprises an output element (34) that is coupled to be eccentric gear by means of driving elements (30). No rotatable transmission elements, such as roller bearings or bearing sleeves, are arranged between the eccentric gear (16) and the inner ring (20,22) and/or between the eccentric gear (16) and the output element (34).

Description

 ECCENTRIC TRANSMISSION WITH CYCLOIDIC TRUNK TOOTH TRIM

State of the art

The invention relates to an eccentric gear and a method for producing such, in particular with a cycloid Triebstock- toothing for adjusting two relatively movably arranged parts in the motor vehicle according to the preamble of the independent claims.

With DE 459 025 is a transmission or reduction gear for attachment to a

Electric motor has become known, which is designed as an eccentric gear in the manner of a cyclo-transmission. On a driving shaft, two eccentrics are arranged offset by 180 °, which put two eccentric discs in an eccentric motion via rolling bearings. The eccentric discs have as external teeth, for example. A closed wave-shaped curve, which cooperates with rotatably mounted on bolts rollers, which are arranged on a housing forming a ring gear. On the eccentric further Mitnehmerbolzen are arranged on which rotatable rectangular sliding shoes are mounted. These shoes engage in two mutually perpendicular Mitnehmerführungen a driver to transmit the torque to an output shaft. Such a rotatable mounting of the outer rollers and the driver elements has a large volume and a high weight of the transmission result so that it is not suitable for mass production in adjusting drives in the motor vehicle. Advantages of the invention

The eccentric gear according to the invention, and its production method, with the characterizing features of the independent claims have the advantage that the costly production and assembly of bearing sleeves or bearings between the

Eccentric and the ring gear and between the eccentric and the output element deleted. By the manufacturing method according to the invention and the material pairing, the sliding friction occurring then is reduced so that the efficiency is only marginally worse than the rolling friction in transmissions with rotatable bearing elements. By the materials used and manufacturing process very light gearbox can be made with considerable reduction in the number of parts in low-cost mass production.

The measures listed in the dependent claims, advantageous refinements and improvements of the specified in the independent claims

Characteristics. Has the ring gear as internal teeth on toothed elements, which are at least semi-cylindrical in shape of a cycloidal drive gearing, the internal teeth with the pericyloidal external teeth always forms a concave-concave contact (in contrast to the epicycloid external teeth), whereby a lower Hertzian pressure and a better film formation occurs when engaging the two gears. This increases the efficiency of the transmission, or the precision requirements are reduced in the manufacture of the transmission. In addition, as a result, the production cost and the variety of parts of the transmission is significantly reduced.

If the outer toothing has no undercut, only semicylindrical elements are sufficient for engagement of the outer tooth elements. These can be easily formed in one piece with the surrounding the eccentric gear housing. This allows a very cost-effective production of the gear housing with integrated internal toothing by injection molding - optionally with corresponding cylindrical inserts.

Due to the simultaneous engagement of many toothed elements in the external teeth a uniform load distribution on the eccentric takes place, whereby the friction on the tooth flanks and on the driver elements is reduced. Will the Toothed elements additionally made of a more wear-resistant material, as the teeth, despite the storage without rotary elements a long life and high efficiency of the transmission can be achieved.

Will the external teeth in contrast to a conventional "intertwined

Pericycloids "formed without undercut, learns the eccentric only force components toward its center or in the tangential direction, but no forces away from the center .Thus, a vibration load of the eccentric is avoided, which significantly increases its life, or lighter materials and allows the production of noise Due to the formation of an at least approximately pericycloid outer toothing of the eccentric wheel, the tangential component for the actual torque transmission becomes significantly larger than, for example, an epicyclic toothing. whereby the entire eccentric gear by eliminating rotatable

Bearing elements can be constructed much cheaper. The pericycloid external toothing allows a greater tooth depth, whereby the eccentricity of the transmission can be selected larger.

It is particularly favorable to design the pericyloidal external toothing in such a way that, at the moment of the emergence or entry of the external tooth elements into or out of the external toothing, the normal force on the tooth flank has an angle between 0 and 40 ° relative to the tangential direction towards the center of the eccentric wheel. Particularly advantageous is the choice of this angle between 0 and 20 °, since in this case the force acting on the eccentric almost exclusively as tangential components for

Moment transfer is used.

In a further embodiment, the eccentric wheel is designed to be elastic, so that the outer toothing can adapt to the tooth elements within certain limits when engaging in the outer tooth elements. As a result, there are always several tooth elements in the

Engagement with the external teeth, whereby a better stiffening of the transmission under load and a good load capacity of the eccentric and the toothing is achieved.

If several eccentric arranged on an axis, which are rotated together with the corresponding eccentrics against each other, can by the - A -

More uniform engagement of the respective external teeth in the inner ring, the radial forces are reduced to the transmission, whereby its efficiency is increased.

By producing the eccentric wheel by means of injection molding, stamping or sintering, it is also possible to form mathematically complicated curve shapes, such as the pericyloidal external toothing without undercut, cost-effectively for mass production, as it is possible to dispense with a machining process. In this manufacturing process material pairings can be used, which allow a direct rotation elements-free engagement of the external teeth in the non-rotatably mounted on the inner ring tooth elements.

Preferably, the eccentric wheel is made of inexpensive plastic or light metal, whereby the weight of the transmission is substantially reduced. In addition, by a suitable choice of the tooth elements of the inner ring, for example. Steel reduces the friction and thus the efficiency and wear can be optimized.

If the toothed elements are produced integrally with the transmission housing in one production step, the injection molding process can be used for this purpose, for example. The tooth elements are molded directly into the interior of the inner ring for interaction with the pericycloid external toothing without undercut as a half cylinder. When using plastic or aluminum, the material of the eccentric can be tuned again according to optimized friction.

If steel bolts are required for higher loads than external tooth elements, the inner ring can be produced in a process-favorable manner as an injection-molded part with steel inserts.

Alternatively, the tooth elements can be manufactured by a stamped-deep-drawing process, wherein the inner ring is advantageously integrally formed with the gear housing. This method is suitable for particularly large moments to be transmitted, since the component can be produced from a sheet steel. Thus, such a high-load cycloid transmission can be made very compact, whereby the transmission according to the invention is suitable for an application for adjusting moving parts in the motor vehicle. drawings

In the drawings, various exemplary embodiments of a device according to the invention are shown and explained in more detail in the following description. Show it

Figure 1 is a schematic representation of an eccentric gear according to the invention, Figure 2 is a section through a further exemplary embodiment of an eccentric, Figure 3 is a cross-section of a cycloid drive train toothing according to Figure 1 Figure 4 schematically an inventive eccentric, which meshes with corresponding outer bolt and

Figure 5 shows a detail of a toothing according to the invention and a section of a toothing according to the prior art.

Description of the exemplary embodiments

In Figure 1 is shown schematically as an eccentric 10, the principle of operation of a so-called cycloid gear in which two eccentrics 14 are arranged on a drive shaft 12. On the eccentrics 14 each eccentric 16 are rotatably mounted, which are also referred to as cam 16. The eccentric 16 has an outer toothing 18, which formed with an inner ring 20 as

Ring gear 22 meshes. The inner ring 20 consists of annularly arranged toothed elements 24, which are designed here as non-rotatable outer bolts 28. Due to the difference in the number of teeth between the outer teeth 18 and the inner ring 20, the eccentric 16 engages only in sections in the inner ring 20, whereby a corresponding reduction is realized. The torque is using

Driving elements 30, which engage in circular receptacles 32 of the eccentric 16, transferred to an abrasive element 34. The driving elements 30 are formed here as a rotationally fixed driving bolts 38 of the output element 34, which are guided directly, directly in the receptacles 32 slidably. The eccentric 16 each have a circular recess 15 in which the eccentric 14 are mounted directly sliding, such that the

Exzenterräder 16 rotatably perform a tumbling motion about the drive shaft 12. Between the eccentric wheels 16 and the other transmission components 20, 34 and no rotatable bearing elements are arranged so that the eccentric 16 only directly slidingly with the transmission components 14, 20, 34 cooperate. In Figure 2, a further exemplary embodiment of an eccentric gear 10 according to the invention is shown in section, in which between each of the eccentric 16 and the eccentric 14 and between the Exzenterrrad 16 and the output element 34 rotatable bearing elements are arranged. On the drive shaft 12 with the eccentrics 14 formed thereon, two eccentric wheels 16 are mounted, which are arranged rotated by 180 ° from each other. Both eccentric wheels 16 have a pericycloid outer toothing 18 which mesh with the ring gear formed as a housing 44. On the ring gear 22, the outer bolts 28 are secured against rotation by means of fixing elements 46 and supported by a ring 21 on the housing 44. The toothed elements 24 designed as outer bolts 28 engage directly in the sliding

External teeth 18 a, without further rotatable elements 26 between the eccentric 16 and the ring gear 22 are arranged. The outer toothing 18 is in this case designed as a pericycloidal curve 42 without undercut, as will be explained in more detail in FIGS. 3 to 5. In the upper half of the picture, the external toothing 18 of the right eccentric wheel 16 is in maximum engagement with the

Tooth elements 24, while the outer teeth 18 of the left eccentric 16 rotates exactly past the tooth elements 24. The output element 34 has rotatably mounted driving bolts 38 which engage in circular receptacles 32 of the two axially adjacent eccentric 16 - in the sense of a parallel-pin transmission -. Due to the plurality of offset eccentric wheels 16, the torque is transmitted more uniformly to the output member 34, since the respective external gears 18 are engaged with different portions of the ring gear 22. In the upper half of Figure 2, the driving elements 30 are mounted by means of rotary sleeves 36 or bearings 37 in the receptacles 32, so that the driving bolts 38 roll therein. In the lower half of Figure 2 are the

Mitnahmebolzen 38 directly guided in the receptacles 32 slidably, since no additional bearing elements 36, 37 are arranged. In the exemplary embodiment, the outer pins 28 are made of steel and the eccentric discs 16 made of brass, whereby the friction of the "rotating elements-free toothing" is reduced.

In further variations of the embodiment, the eccentric wheels 16 are injection molded from plastic, or stamped from metal, or sintered. When using plastic for the eccentric 16 is between this and the eccentric 14, a roller bearing or a bearing bush 48, for example. Inserted from sintered material. The outer bolts 28 are either integral with the housing as an injection molded part, or designed as metal inserts in the injection-molded housing. Due to the design of the eccentric wheel 16 as a plastic disc, this is elastically formed within certain limits, so that the external toothing 18 adapts to the shape of the outer tooth elements 24 and thereby the number of engaged tooth elements 24 is increased.

Figure 3 describes a gearbox with cycloid drive-tooth system according to a view according to III-III of Figure 1. The two mutually rotated eccentric 16 arranged mesh with their external teeth 18 with the rotatably connected to the inner ring 20 tooth elements 24, here as a cylindrical outer bolt

28 are formed. The outer toothing 18 is formed as a closed cycloidal curve, which partially engages directly sliding in the outer tooth elements 24. The engaging portions of the two eccentric wheels 16 are opposite each other, so that the concentricity of the transmission is increased. In Figure 3, normal forces 68 are shown, the stationary outer pins 28 on tooth flanks 64 of the

External teeth 18 act. Likewise, the driving elements 30 rotatably connected to the driven element 30 exert a counterforce 69 on the eccentric wheels 16, which, together with the normal forces 68, form a resultant force 80 which acts on the eccentric wheel 16. In Figure 3, the outer teeth 18 have relatively shallow tooth gaps 50, whereby the resultant force 80 is relatively large. Will for the

External toothing 18 uses a pericycloid waveform 42 without undercut, the force 80 is minimized, whereby the friction load of the inventive "rotating element-free" teeth 18, 24 is significantly reduced.

FIG. 4 shows an inventive toothing 18, 28 of a transmission 10 according to FIG

2 shown in cross section. The inner ring 20 is shown only schematically and has, for example, fifty-one tooth elements 24, which are formed as Triebstock- toothing with at least semi-cylindrical outer bolt 28. The eccentric 16 has an outer toothing 18 which is formed as a pericyclic curve 42 without undercut, which has fifty tooth gaps 50 in the embodiment. The pericycloid

External gearing 42 has relatively deep tooth spaces 50 as compared to involute gearing or an epicycloidal cam shape, thereby achieving a high gear ratio (here eg i = -50) without the risk of "slipping" at high torques to be transmitted Since the interaction with a pericycloid external teeth 42 without undercut as Toothed elements 24 only half cylinders are required, the outer pins 28 may be formed as integrally formed with the ring gear 22 half cylinder 52, or as non-rotatably mounted in the ring gear 22 outer bolt 28.

FIG. 5 shows a section of a pericyklidoid according to the invention

Curve 42 without undercut, in engagement with an outer pin 28. For comparison, according to the prior art, a pericycloid outer toothing is shown with a lower section 62, in which the tooth shape of the outer toothing has a waist 63. The use of the term pericylo-loid refers to the choice of technically meaningful / realizable curve parameters and is defined in more detail below. A pericycloid curve 42 is constructed by rolling a larger pitch circle around the base circle around a smaller fixed base circle (base circle is completely inside the pitch circle). In this case, a fixed point on the rolling circle describes a convoluted cycloidal trajectory in which, in a complete run, the rolling circle covers one or more points of the trajectory of the trajectory point. From the pericycloid curve, the curved, epicycloidic curve is to be distinguished, which results from the rolling of a rolling circle on the outer circumference of a base circle (rolling circle is completely outside the base circle).

In Figure 5, the two outer pins 28 are each shown at the entrance or exit (66) in or out of the outer teeth 18, immediately at the beginning or at the end of the contact between the outer bolt and the tooth flank 64 of the outer teeth 18. In the pericyclic curve Undercut 62 acts at this time due to the undercut a normal force 68 on the tooth flank 64, which is a tangential component

70 and one, the eccentric 16 from the center 67 wegziehende radial component 72 ,. When the outer bolt 28 penetrates deeper into the tooth gap 50 of the outer toothing 62 as it passes through the waist 63 (not shown), a radial component indicative of the center point occurs instead of the radial component 72 facing away from the center 67, whereby the eccentric wheel 16 is exposed to constant vibration loading.

In the case of the pericycloid curve 42 without undercut, the normal force 68 at the exit point 66 always has only components 70, 74 which are oriented tangentially to the center 67, or radially to the center 67. In the illustrated in Figure 4 Curve 42 without undercut, the normal force 68 exclusively a tangential component 70 without radial components 72 or 74. This case defines an exit angle 76 of 0 ° between the tangential direction 71 and the normal force 68. According to the invention, the tooth flank 64 of the pericycloidal curve 42 is formed without undercut such that the normal force 68 at the entrance or exit

Exit point 66 of the tooth elements 24 forms an exit angle 76 in the range of 0 to 40 °, in particular from 0 to 20 °. If the exit angle 76 is approximately 0 °, occurs at the time of entry or exit 66 of the tooth elements 24 only a minimal sliding friction between tooth flank 64 and outer bolt 28, so that the entire, acting from the tooth element 24 on the tooth flank 64 normal force 68 for

Torque transmission is used.

It should be noted that, with regard to the exemplary embodiments shown in the figures and the description, a variety of possible combinations of the individual features are possible with one another. Thus, for example, the concrete shape of the

External teeth 18 and the specific configuration of the tooth elements 24 are varied according to the gear application, which can be easily produced in series by the manufacturing process according to the invention even complicated waveforms. According to the invention, rotatable bearing elements 36, 37, 48 can be arranged in each case between the eccentric wheel 16 and the eccentric 14 and / or the output element 34, but preferably, due to the inventive design of the external toothing 18, such additional bearing elements are dispensed with. By a suitable choice of material pairing between the moving parts, in particular a plastic-metal combination, the sliding friction between these moving parts can be further reduced. The ring gear 22 of the transmission 10 may, for example, be arranged in a cavity of a motor drive, whereby a very compact adjustment for adjusting movable parts in the motor vehicle can be realized.

Claims

claims First eccentric gear (10), in particular with a cycloid drive-tooth, for adjusting two relatively movably arranged parts in the motor vehicle, with one of a rotary drive (12) driven eccentrically Eccentric (16) which meshes in sections with an inner ring (20, 22) on the rotatably toothed elements (24, 28, 52) are arranged, which engage in the external toothing (18, 42) of the eccentric (16), and an output element (34) which is coupled by means of entrainment elements (30) with the eccentric wheel (16), characterized in that the eccentric wheel (16) and the inner ring (20,22) and / or the Eccentric (16) and the driven element (34) rotatable element-free - that is, without arrangement of rotatable transmission elements such as rolling bearings or bearing sleeves - intermesh. 2. eccentric gear (10) according to claim 1, characterized in that the Tooth elements (24, 28, 52) are formed as substantially at least semi-cylindrical outer bolt (28). 3. eccentric gear (10) according to any one of claims 1 or 2, characterized in that the inner ring (20, 22) as a gear housing (44) is formed, wherein the at least semi-cylindrical tooth elements (24, 28, 52) integral with the transmission housing ( 44) are formed. 4. eccentric gear (10) according to any one of the preceding claims, characterized in that a plurality of the at least semi-cylindrical tooth elements (24, 28, 52) at the same time slide directly into the outer toothing (18), wherein the tooth elements (24, 28, 52) and the outer toothing (18) made of a material of different hardness. 5. Eccentric gear (10) according to one of the preceding claims, characterized in that the external toothing of the eccentric wheel (16) tooth flanks (64), to which the engaging tooth elements (24, 28, 52) of the ring gear (22, 20) a Normal force (68) exerting exclusively components (74) to the center (67) of the eccentric wheel (16) and / or tangential components (70) and, in particular, has no components (72) radially away from the center (67). 6. eccentric gear (10) according to any one of the preceding claims, characterized in that at the outlet and / or entry (66) of the tooth elements (24, 28, 52) from the external toothing (18), the normal force (68) an exit angle (76) between 0 ° and 40 ° - in particular between 0 ° and 20 ° - with respect to the tangential direction (71), towards the center (67) of the eccentric wheel (16). 7. eccentric gear (10) according to any one of the preceding claims, characterized in that the eccentric (16) at least in the region of the external toothing (18) for adaptation to the at least haϊbzylinderförmige tooth elements (24, 28, 52) is elastically deformable. 8. eccentric gear (10) according to any one of the preceding claims, characterized in that the eccentric (16) has a plurality of round receptacles (32) in which as driving pins (38) formed driving elements (30) of the output element (34) are guided directly sliding , 9. eccentric gear (10) according to any one of the preceding claims, characterized by a plurality of tangentially uniformly rotated against each other arranged eccentric wheels (16) with recesses 15, which are guided directly sliding on eccentrics (14). 10. Method for producing an eccentric drive (10) with a cycloidal Triebstock- toothing for adjusting two relatively movably arranged parts in the motor vehicle, in particular according to one of the preceding claims, with one of a rotary drive (12) eccentrically driven eccentric wheel (16) which engages in sections in an inner ring (20, 22), in the substantially at least halbzylinderformige tooth elements (24, 28, 52) which engage in the external toothing (18) of the eccentric wheel (16) and an output element (34) which is coupled by means of entrainment elements (30) with the eccentric wheel (16), characterized in that the eccentric wheel (16) by means of injection molding or punched or sintered and molded with the External toothing (18) directly, directly into the relative to the inner ring (20, 22) rotationally fixed tooth elements (24, 28, 52) is inserted. 11. The method according to claim 10, characterized in that the eccentric wheel (16) made of plastic, light metal or a metal alloy is produced. 12. The method according to any one of claims 10 or 11, characterized in that the substantially at least semi-cylindrical tooth elements (24, 28, 52) together with the gear housing (44) are integrally formed by injection molding, in particular made of plastic or light metal. 13. The method according to any one of the preceding claims, characterized in that the substantially at least semi-cylindrical tooth elements (24, 28, 52) as inserts, in particular steel bolts (28), are encapsulated with the inner ring. 14. The method according to any one of the preceding claims, characterized in that in the gear housing (44) integrated, substantially at least semi-cylindrical tooth elements (24, 28, 52) by means of a combined stamping thermoforming process - in particular steel - are produced.