(19) United States (12) Patent Application Publication (10) Pub

US 20070034034A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2007/0034034 A1 Bessey (43) Pub. Date: Feb. 15, 2007

(54) TRANSMISSION ELEMENT FOR A ZERO (30) Foreign Application Priority Data BACKLASH TRANSMISSION, ESPECIALLY FOR PRECISION MECHANICS Jul. 26, 2005 (DE) ...... 10 2005 036 127.7

Publication Classi?cation (75) Inventor: Reiner Bessey, Schonaich (DE) (51) Int_ CL F16H 55/18 (2006.01) Correspondence Addressl (52) us. Cl...... 74/409 GUDRUN E. HUCKETT DRAUDT LONSSTR. 53 (57) ABSTRACT WUPPERTAL 42289 (DE) A transmission element for a Zero backlash transmission With at least tWo transmission paths that are tensioned relative to one another has a ?rst transmission part and a (73) Assignee; ])R_ FRITZ FAULHABER GMBH & second transmission part that are elastically tensionable C0_ KG’ Schonaich (DE) relative to one another. At least one torsion spring element for increasing the elasticity is provided. The torsion spring (21) App1_ NQ; 11/456,592 element transmits torque between the ?rst and second trans mission parts and the ?rst and second transmission parts are (22) Filed: Jul. 11, 2006 rotatable relative to one another.

15 Patent Application Publication Feb. 15, 2007 Sheet 1 0f 2 US 2007/0034034 A1

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15 US 2007/0034034 A1 Feb. 15, 2007

TRANSMISSION ELEMENT FOR A ZERO [0010] FIG. 1 an axial section of a transmission element BACKLASH TRANSMISSION, ESPECIALLY FOR according to the invention; PRECISION MECHANICS [0011] FIG. 2A a torsion spring element of the transmis BACKGROUND OF THE INVENTION sion element of the present invention in a top vieW; [0001] The invention relates to a transmission element for [0012] FIG. 2B a torsion spring element of the transmis a transmission that is free of backlash, especially for preci sion element of the present invention in a side vieW; sion mechanics, Wherein the transmission has at least tWo [0013] FIG. 3 an end vieW and a schematic illustration a transmission paths that are tensioned relative to one another. part of a transmission into Which the transmission element [0002] In precision mechanics, spur gear units are knoWn according to the invention has been installed. for poWer transmission and for position control; in the spur gear units the backlash Within the transmission is minimized DESCRIPTION OF PREFERRED EMBODIMENT by different technical measures. One possibility resides in [0014] FIGS. 1 and 2 shoW a transmission element 1 that that tWo parallel self-contained transmission paths are pro is to be mounted in a transmission as illustrated in an vided that are tensioned relative to one another. Depending exemplary fashion in FIG. 3. This transmission is a spur gear on the rotational direction, the movements and torque are unit With tWo transmission paths. TWo spur gears 3 of this then transmitted through the ?rst or the second transmission transmission are illustrated betWeen Which a pinion 15 of a path. The tensioning is possible because of the elasticity of drive shaft of a motor is arranged. The motor is connected the transmission paths. Constructive tolerances and the pitch to the transmission so that the transmission is driven by it. of the teeth hoWever do not alloW for a process-safe ten The pinion 15 meshes With the spur gears 3. sioning of the transmissions. [0015] This transmission has Zero backlash or is at least [0003] In a knoWn Zero backlash transmission (German substantially free of backlash and is advantageously used in patent application 100 36 937 A1) a rigid stepped planetary precision mechanics. The transmission element 1 has a gear and a rotationally elastic and pretensioned stepped pinion 4 on Which concentrically the spur gear 3 is mounted. planetary gear are provided. Such a transmission con?gu The pinion 4 and the spur gear 3 are arranged relative to one ration is constructively complex and leads to relatively large another so as to be free of play in the radial direction. The siZe transmission units. transmission element 1 is mounted at the drive side of the [0004] In another Zero backlash transmission (German transmission in one of the transmission paths and ensures patent 25 38 460 C3) a tensioning device is provided With Zero backlash, at least hoWever a transmission substantially Which a gearWheel is connected to the output shaft of a step free of backlash. The transmission element 1 forms Within motor. The tensioning device has a cam disk and a folloWer the spur gear unit an intermediate gear 5. disk in Which at angular spacings slotted holes are provided [0016] On one end of the pinion 4, a disk 6 is ?xedly that are engaged by axially extending bolts of the cam disk. mounted and arranged coaxially to the pinion 4. The disk 6 Within the slotted holes pressure springs act on these bolts can be ?xedly attached to the pinion 4 by force-locking, by so that bracing of the gear unit is achieved. This transmission fusing or by positive locking. The disk 6 has a circumfer is also constructively complex and is comprised of a plu entially extending rim 7 that is pointing toWard the spur gear rality of components. 3 so that a receptacle 8 is radially outWardly delimited by it. SUMMARY OF THE INVENTION In this receptacle a torsion spring element 2 is mounted With Which torque is transmitted from the disk 6 onto the pinion [0005] It is an object of the invention to con?gure a 4 and onto the spur gear 3. The torsion spring element 2 is transmission element of the aforementioned kind in such a embodied as a partial ring (FIG. 2A) that extends across Way that a simple construction is combined With a compact more than 270 degrees and Whose tWo ends 9, 10 are angled con?guration. at a right angle in opposite directions relative to one another [0006] This object is solved for the transmission element (FIG. 2B). With these ends 9, 10 the torsion spring element of the aforementioned kind in accordance With the invention 2 engages axial recesses or bores of the spur gear 3 and of the elasticity of one of the tWo transmission paths of the the disk 6. In FIG. 1, the axial bore 11 of the spur gear 3 is transmission is increased so that a process-safe tensioning of shoWn; the end 9 of the torsion spring element 2 engages the tWo transmission paths is ensured. positively the bore. The disk 6 is provided With a corre sponding bore that is engaged by the other end 10. In the [0007] Advantageously, for increasing this elasticity at mounted state, the bottom of the disk 6 faces the drive motor. least one torsion spring element is provided With Which tWo transmission parts are tensioned relative to one another. The [0017] The torsion spring element 2 is positioned in the torsion spring element can be arranged in a space-saving receptacle 8 of the disk 6 and has minimal spacing from the Way Within the transmission element and can still ensure a radial bottom 12 of the receptacle 8. The spur gear 3 is reliable tensioning of the tWo transmission paths relative to provided at the end face facing the disk 6 With a central one another. recess 13 having the same diameter as the receptacle 8 of the disk 6. The disk 6 is positioned With the angled circumfer [0008] Further features of the invention result from the ential rim 7 against the end face of the rim 14 of the spur dependent claims, the description, and the draWing. gear 3 that radially delimits the recess 13. In this Way, the BRIEF DESCRIPTION OF THE DRAWINGS torsion spring element 2 is protected betWeen the disk 6 and the spur gear 3. [0009] The invention Will be explained in more detail in the folloWing With the aid of one embodiment illustrated in [0018] The inner diameter of the torsion spring element 2 the draWing. It is shoWn in: is slightly greater than the outer diameter of the pinion 4 in US 2007/0034034 Al Feb. 15, 2007

the area of the torsion spring element 2. In this Way it is 3. The transmission element according to claim 2, com ensured that the torsion spring element 2 can contract prising at least one torsion spring element for increasing the slightly elastically Without touching the exterior of the elasticity. pinion 4. 4. The transmission element according to claim 3, Wherein the torsion spring element transmits torque betWeen [0019] In the mounted position, the torsion spring element the ?rst and second transmission parts and the ?rst and 2 is elastically pretensioned in the circumferential direction second transmission parts are rotatable relative to one so that the spur gear 3 and, by means of the disk 6, the pinion another. 4 are tensioned relative to one another. BetWeen the spur 5. The transmission element according to claim 2, gear 3 and the pinion 4 there is therefore Zero backlash. As Wherein the ?rst transmission part is a gear Wheel that is a result of the torsion spring element 2, the spur gear 3 and supported on the second transmission part. the pinion 4 can rotate to a limited extent elastically relative 6. The transmission element according to claim 2, to one another. Wherein the second transmission part is a pinion. [0020] The torsion spring element 2 has advantageously a 7. The transmission element according to claim 2, round cross-section. It can be comprised of steel, of a Wherein the ?rst transmission part is a gear Wheel and the non-iron material, or of plastic material. The torsion spring second transmission part is a pinion and Wherein the gear element 2 takes up axially and radially only minimal space Wheel and the pinion are coaxially positioned relative to one so that the transmission element 1 and thus the intermediate another. gear 5 are of a very compact con?guration. The Zero 8. The transmission element according to claim 7, backlash transmission element 1 is con?gured as a precision Wherein the gear Wheel and the pinion are arranged radially mechanics component in that the tensioning element is Without play relative to one another. directly integrated in the form of the torsion spring element 9. The transmission element according to claim 3, further 2. Once the transmission element 1 is mounted in the spur comprising a disk, Wherein the torsion spring element con gear unit, an optimal performance is provided With only a nects the disk and the ?rst transmission part to one another. minimal number of components for realiZing the Zero back 10. The transmission element according to claim 9, lash spur gear unit. By means of the Zero backlash trans Wherein the disk is rotationally ?xedly connected to the mission element 1 tWo parallel transmission paths can be second transmission part. realiZed Within one housing Wherein these paths are ten 11. The transmission element according to claim 9, sioned relative to one another. Wherein the disk is coaxial to the second transmission part. [0021] The torsion spring element 2 must not be a separate 12. The transmission element according to claim 9, component but can also be generated by means of an Wherein the disk is force-locked, fused, or positively con intentionally rotary-elastic con?guration of the intermediate nected to the second transmission part. gear 5. For example, it is possible to con?gure the spur gear 13. The transmission element according to claim 9, 3 itself to have torsion spring properties. Wherein the torsion spring element is positioned betWeen the disk and the ?rst transmission part. [0022] The intermediate gear 5 has a greater elasticity than 14. The transmission element according to claim 9, a conventional intermediate gear. The elasticity of the entire Wherein the disk has an end face provided With a ?rst recess, transmission path in Which the intermediate gear 5 is Wherein the torsion spring element engages the recess. mounted is thus of greater elasticity in comparison to 15. The transmission element according to claim 14, conventional transmission paths. The intermediate gear 5 is Wherein the ?rst transmission part has an end face With a advantageously mounted at a location Where a relatively second recess, Wherein the torsion spring element engages minimal torque is acting. In general, this Will be the motor the recess. side input of the Zero backlash gear. The torque that is 16. The transmission element according to claim 15, transmitted at this location is advantageously less than the Wherein the ?rst and second recesses form a closed chamber torque With Which the transmission element 1 is tensioned for the torsion spring element. by the torsion spring element 2. 17. The transmission element according to claim 3, [0023] The speci?cation incorporates by reference the Wherein the torsion spring element is a partial ring With ends entire disclosure of German priority document 10 2005 036 angled in opposite directions. 127.7 having a ?ling date of Jul. 26, 2005. 18. The transmission element according to clean 17, further comprising a disk, Wherein the torsion spring ele [0024] While speci?c embodiments of the invention have ment connects the disk and the ?rst transmission part to one been shoWn and described in detail to illustrate the inventive another, Wherein the ends of the torsion spring element principles, it Will be understood that the invention may be engage openings of the ?rst transmission part and of the embodied otherWise Without departing from such principles. disk. 19. The transmission element according to claim 3, Wherein an inner diameter of the torsion spring element is What is claimed is: greater than an outer diameter of a portion of the second 1. A transmission element for a Zero backlash transmis transmission part Where the torsion spring element is sion comprising at least tWo transmission paths that are arranged. tensioned relative to one another, Wherein an elasticity of 20. The transmission element according to claim 3, one of the tWo transmission paths is increased. Wherein the torsion spring element is made from steel. 2. The transmission element according to claim 1, com 21. The transmission element according to claim 3, prising a ?rst transmission part and a second transmission Wherein the torsion spring element is comprised of non-iron part that are elastically tensionable relative to one another. material. US 2007/0034034 A1 Feb. 15, 2007 3

22. The transmission element according to claim 3, 24. The transmission element according to claim 2, Wherein the torsion spring element is comprised of plastic whfxeln the ?rst transm1ss1on Part 15 Con?gured as a tor 51011 material~ spring element. . ~ ~ ~ 25. The transm1ss1on element according to cla1m 2, 23. The transmission element according to claim 3, com- Wherein the transmission element is an intermediate gear of prising a common housing in Which the transmission ele- the transm1ss1on ment and the torsion spring element are arranged. * * * * *