Toothed belt comprising running surfaces provided on opposite sides and having tooth systems, the helix angles of the tooth systems being oriented in opposite directions, and associated toothed belt gear

Abstract

The invention relates to a toothed belt (10a, 10b) with two mutually oppositely arranged running surfaces (2, 4), wherein, on the running surfaces (2, 4), there are arranged toothings (12, 14) arranged obliquely with respect to the axial direction (X), wherein the obliquity is defined in each case by helix angles (16, 18) between the axial direction (X) and the direction of the tooth flanks of the respective toothings (12, 14). It is provided that the helix angle (16) of the first toothing (12) is oriented oppositely to the helix angle (18) of the second toothing (14).

Claims

1. A toothed belt comprising; two mutually oppositely arranged running surfaces, wherein, on the running surfaces there are arranged teeth arranged obliquely with respect to the axial direction (X), wherein the obliquity is defined in each case by helix angles between the axial direction (X) and the direction of the tooth flanks of the respective teeth, and wherein a first helix angle of a first toothing is oriented opposite to a second helix angle of a second toothing; at least one first toothed-belt pulley, which is in engagement with the first toothing of the toothed belt, and at least one second toothed-belt pulley, which is in engagement with the second toothing of the toothed belt, and wherein a helix angle of the toothing of the toothed-belt pulleys in each case corresponds to the helix angle of the teeth of the toothed belt; the at least one second toothed-belt pulley is arranged so as to be situated directly opposite the at least one first toothed-belt pulley; and the spacing between the at least one first toothed-belt pulley and the at least one second toothed-belt pulley is smaller than the thickness of the toothed belt arranged between the at least one first toothed-belt pulley and the at least one second toothed-belt pulley.

2. The toothed belt as claimed in claim 1, wherein the first helix angle of the first toothing and the second helix angle of the second toothing have an equal or different magnitude of helix angle.

3. The toothed belt as claimed in claim 2, wherein the first helix angle and the second helix angle each have an angle value between >0 degrees and 20 degrees.

4. The toothed belt as claimed in claim 3 wherein the first helix angle and the second helix angle each have an angle value of from 2 degrees to 10 degrees.

5. The toothed belt as claimed in claim 4, wherein the first helix angle and the second helix angle each have an angle value of 5 degrees.

6. The toothed belt as claimed in claim 1, wherein the teeth of the toothed belt are of similar or non-similar design in particular with regard to tooth height, tooth pitch (tooth spacing Z) and tooth shape.

7. The toothed-belt transmission as claimed in claim 1, wherein the at least one first toothed-belt pulley has an external toothing and the at least one second toothed-belt pulley as an internal gear has an internal toothing, wherein respective helix angle of the teeth of the respective toothed-belt pulley corresponds to the helix angle of the respective toothing of the toothed belt which engages into the teeth of the respective toothed-belt pulley.

8. The toothed-belt transmission as claimed in claim 7, wherein the first toothed-belt pulleys are arranged rotatably in planet carriers of a planetary transmission relative to one another, and wherein the planet carriers with the first toothed-belt pulleys are arranged in the second toothed-belt pulleys designed as internal gears and are thus formed as planetary transmissions.

9. A toothed belt comprising: two mutually oppositely arranged running surfaces, wherein, on the running surfaces there are arranged teeth arranged obliquely with respect to the axial direction (X), wherein the obliquity is defined in each case by helix angles between the axial direction (X) and the direction of the tooth flanks of the respective teeth, and wherein a first helix angle of a first toothing is oriented opposite to a second helix angle of a second toothing; at least one first toothed-belt pulley, which is in engagement with the first toothing of the toothed belt, and at least one second toothed-belt pulley, which is in engagement with the second toothing of the toothed belt, and wherein a helix angle of the toothing of the toothed-belt pulleys in each case corresponds to the helix angle of the teeth of the toothed belt; a transmission arrangement comprising at least the toothed belt and having two planetary transmissions, wherein the first toothed-belt pulleys of the first planetary transmission are, with the first toothed-belt pulleys of the second planetary transmission, arranged in each case pairwise on a shaft rotatably in the planet carriers, and the drive of the shafts and of the toothed-belt pulleys arranged on the shafts is performed via the rotatable planet carriers, wherein a second toothed-belt pulley of the first planetary transmission is arranged so as to be static, and a second toothed-belt pulley of the second planetary transmission is arranged so as to be rotatable relative to the second toothed-belt pulley of the first planetary transmission, wherein the second rotatable toothed-belt pulley of the second planetary transmission forms the output of the transmission arrangement, and wherein the toothed belts are arranged as damping elements between the first toothed-belt pulleys and the second toothed-belt pulleys.

10. The transmission arrangement as claimed in claim 9, wherein the first toothed-belt pulleys of the first planetary transmission and, correspondingly thereto, the toothing of the second toothed-belt pulley have a different diameter and/or a different tooth pitch than the first toothed-belt pulleys of the second planetary transmission and the corresponding toothing of the second toothed-belt pulley, whereby a transmission ratio of the transmission arrangement between the drive and the output is adjustable.

11. The transmission arrangement as claimed in claim 9, wherein the toothed belt and the toothed-belt pulleys of the first planetary transmission have an opposite helix angle in relation to the helix angle of the toothed belt of the toothed-belt pulleys of the second planetary transmission.

12. The use of a transmission arrangement as claimed in claim 9 as a steering transmission, a servo steering transmission, a differential transmission, or a force feedback actuator of a steer-by-wire steering system.

Description

(1) The invention will be discussed below in exemplary embodiments on the basis of the associated drawings, in which:

(2) FIG. 1 shows a toothed belt in a perspective illustration with two mutually oppositely arranged toothings,

(3) FIG. 2 shows a detail of a toothed belt with two mutually oppositely arranged toothings in a view from the first, inner toothing,

(4) FIG. 3 shows a longitudinal section through a toothed-belt transmission with a toothed belt and with a first toothed-belt pulley and a second toothed-belt pulley,

(5) FIG. 4 shows a toothed-belt transmission in a perspective illustration, having three first toothed-belt pulleys which are in engagement with the first, inner toothing of the toothed belt and having a second toothed-belt pulley which is in the form of an internal gear and which is in engagement with the second, outer toothing of the toothed belt,

(6) FIG. 5 shows a toothed-belt transmission in the form of a planetary transmission, having three first toothed-belt pulleys and one second toothed-belt pulley in the form of an internal gear, which toothed-belt pulleys are in engagement with the inner toothing and outer toothing, respectively, of the toothed belt, wherein the three first toothed-belt pulleys are arranged positionally fixedly relative to one another in a planet carrier,

(7) FIG. 6 is a detail illustration from FIG. 5 with a first toothed-belt pulley, with a second toothed-belt pulley in the form of an internal gear, and with a toothed belt,

(8) FIG. 7 shows a transmission arrangement, comprising two planetary transmissions as per FIG. 5, in a perspective illustration,

(9) FIG. 8 shows a transmission arrangement, comprising two planetary transmissions as per FIG. 5, in a sectional illustration, and

(10) FIG. 9 shows a transmission arrangement formed with two planetary transmissions as per FIG. 5, with in each case three first toothed-belt pulley pairs, arranged in in each case one planet carrier, in an exploded illustration.

(11) FIG. 1 shows a toothed belt 10a with two mutually oppositely arranged toothings 12, 14 in a perspective illustration. Here, the toothings 12, 14 are arranged on the two mutually oppositely arranged running surfaces 2, 4 of the toothed belt 10a.

(12) The first toothing 12 of the toothed belt 10a is in engagement with the external toothing of a first toothed-belt pulley (not illustrated), which is arranged below the toothed belt 10a. The second toothing 14 of the toothed belt 10a is in turn in engagement with the toothing of a second toothed-belt pulley (not illustrated) which is arranged above the toothed belt 10a and which, in FIG. 3, is formed as a spur gear and, in FIGS. 4 to 8, is formed as an internal gear, as will be discussed below.

(13) Accordingly, the first toothing 12 of the toothed belt 10a corresponds with a toothing of the first toothed-belt pulley and the second toothing 14 of the toothed belt 10a corresponds with a toothing of the second toothed-belt pulley.

(14) The advantage of the helical toothing in transmissions, as is also the case here in toothed-belt transmissions, consists in that increased running smoothness is attained, and accordingly the noise emissions of the transmission are reduced. The toothed-belt transmission furthermore allows play-free transmission.

(15) Owing to the oppositely oriented obliquities of the two mutually oppositely arranged toothings 12, 14, the transverse forces Q (see also FIG. 2) acting in an axial direction X on the toothed belt 10a advantageously cancel one another out.

(16) The oppositely acting transverse forces Q result from the oppositely oblique tooth flanks of the teeth of the toothed belt 10a with respect to the axial direction X, wherein the axial direction X is oriented orthogonally with respect to the running direction L of the toothed belt 10a.

(17) Thus, the toothed belt 10a is not moved in the axial direction X during operation, as occurs in the case of an identically oriented obliquity of toothed belts 10a that are toothed on both sides, in the case of which the tooth flanks of the teeth of the toothed belt 10a are not oppositely oblique with respect to the axial direction X of the toothed belt 10a.

(18) It is thus advantageously the case that no rim disks arranged laterally with respect to the toothed belt 10a on the toothed-belt pulleys are required for preventing the migration of the toothed belt 10a in the axial direction X. It is thus the case that rim disks are not illustrated in any of the figures.

(19) Accordingly, there is advantageously also no wear of the toothed belt 10a against the rim disks, such as would otherwise occur. The friction and thus the mechanical losses are also advantageously reduced by means of the solution provided. It is thus also possible for the transmission temperatures to be reduced, and accordingly for the thermal loads on the components of the associated transmission to be reduced. It may thus also be the case that a cooling arrangement of the transmission can be omitted or dimensioned to be smaller.

(20) FIG. 2 shows the toothed belt 10a illustrated in FIG. 1 from the side which is assigned to the first running surface 2 of the first toothing 12.

(21) Arranged opposite the first toothing 12 is the second toothing 14, which is not visible in FIG. 2.

(22) The helix angle 16 of the second toothing 14 is, in relation to the axial direction X, oriented oppositely to the helix angle 18 of the first toothing 12.

(23) In the case of an equal magnitude of the two helix angles 16, 18, as is provided, the helix angle 18 of the second toothing 14 arises from a “mirroring” of the helix angle 16 of the first toothing 12 about imaginary mirror axes, which are oriented either in the X direction X or else oriented with the running direction L.

(24) The mirroring about an imaginary mirror axis in the running direction L as per FIG. 2 becomes clear if one shifts the L axis lying outside the toothed belt to one of the points of intersection of the two helix angles 16, 18.

(25) In the case of equal forces on both toothings 12, 14, the transverse forces Q, acting in the axial direction X, of the two toothings 12, 14 cancel one another out. Here, the transverse forces Q result from the obliquity of the tooth flanks of the toothings 12, 14 in relation to the axial direction X, oriented orthogonally with respect to the running direction L, of the toothed belt 10a.

(26) FIG. 3 illustrates a longitudinal section through a toothed-belt transmission 20 with a toothed belt 10a known from FIGS. 1 and 2 and with a first toothed-belt pulley 22a and a second toothed-belt pulley 25.

(27) Here, both toothed-belt pulleys 22a, 25 have an external toothing.

(28) The first toothed-belt pulley 22a is arranged opposite the second toothed-belt pulley 25, wherein the toothed belt 10a runs between the two toothed-belt pulleys 22a, 25 formed as spur gears 22a, 25.

(29) The toothed belt 10a is equipped with the first toothing 12 and the second toothing 14, wherein the first toothing 12 is in engagement with the toothing of the first toothed-belt pulley 22a, and the second toothing 14 is in engagement with the toothing of the second toothed-belt pulley 25.

(30) Owing to the oblique profile of the toothings 12, 14 of the toothed belt 10a, these are only partly visible in the section, and are partly concealed by the toothings of the two toothed-belt pulleys 22a, 25.

(31) The transmission of the torques between first toothed-belt pulley 22a and second toothed-belt pulley 25 is performed by the toothed belt 10a. Here, the toothed belt 10a is not subject to tensile load, and thus advantageously has a damping action between the first toothed-belt pulley 22a and the second toothed-belt pulley 25. Furthermore, with this arrangement, a play-free toothed-belt transmission 20 is realized. The noise emissions of the toothed-belt transmission 20 are thus advantageously considerably reduced.

(32) The first toothing 12 and the second toothing 14 have an oppositely oriented helix angle, such that the transverse forces Q, which act in the axial direction X, owing to the tooth flanks, which run obliquely with respect to the axial direction X, of the toothed belt 10a and of the toothed-belt pulleys 22a, 25 cancel one another out.

(33) There is thus no need for lateral guidance of the toothed belt 10a, for example by means of rim disks (not illustrated) arranged laterally on the toothed-belt pulleys 22a, 25.

(34) The omission of the rim disks also has the advantage in particular that the assembly of a toothed-belt transmission 20, 32, 34 (see FIGS. 4 to 6) or of a transmission arrangement 100 (see FIGS. 7 to 9), which will be discussed in more detail further below, is made easier, in particular because it is easier to carry out the arrangement of the toothed belt 10a in the toothed-belt transmission 20, 32, 34, or of the toothed belt 10a, 10b in the transmission arrangement 100 discussed by way of example, on the toothed-belt pulleys 22a, 22b, 22c; 24a, 24b, 24c.

(35) FIG. 4 shows, in a perspective illustration, a toothed-belt transmission 20 with three first toothed-belt pulleys 22a, 22b, 22c, which are in engagement with the first, inner toothing 12 of the toothed belt 10a, and with one second toothed-belt pulley 26, which is formed as an internal gear 26 and which is in engagement with the second, outer toothing 14 of the toothed belt 10a.

(36) Here, the toothings of the three first toothed-belt pulleys 22a, 22b, 22c are in each case arranged directly opposite the toothing of the second toothed-belt pulley 26, such that the forces from the internally situated first toothed-belt pulleys 22a, 22b, 22c are transmitted via the first toothing 12 and the second toothing 14 of the toothed belt 10a to the second toothed-belt pulley 26.

(37) Here, the toothed belt 10a is not subject to tensile load, and in particular has a damping action between the first toothed-belt pulleys 22a, 22b, 22c and the second toothed-belt pulley 26. By means of the toothed belt 10a, the transmission can advantageously be realized without play.

(38) The illustrated toothed-belt transmission 20 is based on the toothed belt 10a shown in FIG. 1 and FIG. 2 with oppositely oriented helix angles of the first 12 and second toothing 14. Accordingly, the advantages of the toothed belt 10a also apply to the illustrated toothed-belt transmission 20.

(39) FIGS. 5 and 6 show the toothed-belt transmission 20 illustrated in FIG. 4, wherein FIG. 6 shows a detail illustration from FIG. 5. The toothed-belt transmission 20 comprises the three first toothed-belt pulleys 22a, 22b, 22c and the second toothed-belt pulley 26 formed as an internal gear 26, which toothed-belt pulleys are in each case in engagement with the internal toothing 12 and the external toothing 14, respectively, of the toothed belt 10a.

(40) Here, the three first toothed-belt pulleys 22a, 22b, 22c are rotatably mounted by means of a toothed-belt shaft 36 in a planet carrier 30, and are thus arranged in a positionally fixed manner relative to one another. Accordingly, this toothed-belt transmission 20 is formed as a planetary transmission 32. The force is transmitted from the three first toothed-belt pulleys 22a, 22b, 22c by means of the first toothing 12 and the second toothing 14 of the toothed belt 10a to the second toothed-belt pulley 26. The above-mentioned advantages therefore apply to the illustrated planetary transmission.

(41) Here, it may preferably be provided that the spacing between the first toothed-belt pulleys 22a, 22b, 22c and the second toothed-belt pulley 26 is smaller than the thickness of the toothed belt 10a.

(42) Correspondingly, the intermediate space between the first toothed-belt pulleys 22a, 22b, 22c and the second toothed-belt pulley 26 have an undersize in relation to the toothed belt 10a arranged in between.

(43) The elastic toothed belt 10a is thus compressed. A contact pressure is thus attained which reduces the noise emissions and the wear of the toothed-belt transmission 40 yet further.

(44) In FIG. 6, it is in particular also possible to see the helical toothing of toothed belt 10a and first toothed-belt pulley 22a and second toothed-belt pulley 26.

(45) FIG. 7 illustrates a further preferred design variant, which shows, in a perspective illustration, a transmission arrangement 100 which comprises two planetary transmissions 32, 34.

(46) These planetary transmissions 32, 34 have already been shown and described in conjunction with FIGS. 5 and 6.

(47) FIG. 8 shows the transmission arrangement 100 illustrated in FIG. 7 in a longitudinal sectional illustration.

(48) Here, the planetary transmissions 32, 34 are preferably integrated into a transmission arrangement 100 formed as a steering transmission.

(49) In one possible embodiment, a transmission arrangement 100 is formed which comprises two toothed-belt transmissions 32, 34 which, as already discussed, are formed as planetary transmissions 32, 34.

(50) The first toothed-belt pulleys 22a, 22b, 22c of the first planetary transmission 32 with the first toothed-belt pulleys 24a, 24b, 24c of the second planetary transmission 34 are arranged in each case pairwise on in each case one shaft 36 rotatably in the planet carriers 30.

(51) The drive 44 (see FIGS. 7 and 8 viewed together) of the shafts 36 and of the toothed-belt pulleys 22a, 22b, 22c; 24a, 24b, 24c arranged on the shafts 36 is performed via the rotatable planet carriers 30.

(52) It is provided here that a second toothed-belt pulley 26, formed as an internal gear, of the first planetary transmission 32 is arranged so as to be static, and a second toothed-belt pulley 28, likewise formed as an internal gear, of the second planetary transmission 34 is arranged so as to be rotatable relative to the second toothed-belt pulley 26 of the first planetary transmission 32.

(53) The second toothed-belt pulley 28 of the second planetary transmission 34 forms the output 46 of the transmission arrangement 100, wherein the second toothed-belt pulley 28 is operatively connected to a steering-wheel-side shaft (not illustrated).

(54) According to the invention, it is furthermore provided that the toothed belts 10A, 10B according to the invention are arranged as damping elements between the first toothed-belt pulleys 22a, 22b, 22c; 24a, 24b, 24c and the second toothed-belt pulleys 26, 28.

(55) By means of the first toothed-belt pulleys 22a, 22b, 22c, situated and thus connected pairwise on a toothed-belt pulley shaft 36, of the first planetary transmission 32 with the first toothed-belt pulleys 24a, 24b, 24c of a second planetary transmission 34, both planetary transmissions 32, 34 are driven by means of the drive 44.

(56) In other words, the pairwise connection of the first toothed-belt pulleys 22a, 22b, 22c of the first planetary transmission 32 to the first toothed-belt pulleys 24a, 24b, 24c of the second planetary transmission 34 is realized in each case by the arrangement of the toothed-belt pulleys 22a, 22b, 22c; 24a, 24b, 24c on three toothed-belt pulley shafts 36, wherein the three toothed-belt pulley shafts 36 are mounted by means of bearings 40 at both sides in the planet carriers 30.

(57) The two planet carriers 30, which are of disk-like form, are fixedly attached by way of their arms at both sides to a hollow shaft 48 (see FIG. 5) which is driven at the motor side, such that the hollow shaft 48 sets the planet carriers in rotation.

(58) The above-mentioned advantageous effects of the mutually oppositely oriented helix angles 16 of the first toothing 12 on the inner side in relation to the helix angle 18 of the second toothing 14 on the outer side of the toothed belts 10a, 10b as damping elements are analogously also attained in the case of this transmission arrangement 100.

(59) Furthermore, the first toothed-belt pulleys 22a-24a, 22b-24b, 22c-24c arranged pairwise on a shaft 36 are toothed with opposite orientation, whereby, with the arrangement of two toothed belts 10A, 10B, the effect is realized that the transverse forces Q acting in the axial direction X on the toothed belts 10a, 10b cancel one another out.

(60) Accordingly, it is also the case that no transverse forces Q act on the toothed-belt pulley pairs 22a-24a, 22b-24b, 22c-24c. The axial load on the bearings 40 and on the planet carriers 30 is thus advantageously considerably reduced.

(61) Owing to the opposite orientation of the obliquity of the toothings of the two coupled-together planetary transmissions 32, 34, use is accordingly made of different toothed belts, as illustrated in the figures.

(62) For illustrative purposes, FIG. 9 shows individual components of the transmission arrangement 100, specifically the toothed-belt pulley pairs 22a-24a, 22b-24b, 22c-24c of the two planetary transmissions 32, 34, as per FIGS. 5 to 8 viewed together, in an exploded illustration.

(63) It is illustrated in particular that the first toothed-belt pulleys 22a, 22b, 22c of the first planetary transmission 32 have a larger diameter than the first toothed-belt pulleys 24a, 24b, 24c of the second planetary transmission 34.

(64) In each case two first toothed-belt pulleys 22a-24a, 22b-24b, 22c-24c are arranged pairwise on a shaft 36, wherein these are arranged by means of bearings 40 and suitable fastening elements 42 in the planet carriers 30.

(65) With the different diameters and/or different toothing pitch of the first toothed-belt pulleys 22a, 22b, 22c of the first planetary transmission 32 in relation to the first toothed-belt pulleys 24a, 24b, 24c of the second planetary transmission 34, it is possible here for the transmission ratio of the transmission arrangement 100, in particular of a steering transmission, to be predefined.

LIST OF REFERENCE DESIGNATIONS

(66) 10a First toothed belt 10b Second toothed belt 2 First running surface of the toothed belt 4 Second running surface of the toothed belt 12 First toothing, inner toothing 14 Second toothing, outer toothing 16 Helix angle of the first toothing 18 Helix angle of the second toothing 20 Toothed-belt transmission 22a, 22b, 22c First toothed-belt pulley with external toothing (spur gear) in internal gear 26 24a, 24b, 24c First toothed-belt pulley with external toothing (spur gear) in internal gear 28 25 Second toothed-belt pulley with external toothing (spur gear) 26 Second toothed-belt pulley with internal toothing (fixed internal gear) 28 Second toothed-belt pulley with internal toothing (rotating internal gear) 30 Planet carrier 32 First planetary transmission, toothed-belt transmission 34 Second planetary transmission, toothed-belt transmission 36 Shaft, toothed-belt pulley shaft 40 Bearing 42 Fastening element 44 Drive 46 Output 48 Drive shaft 100 Transmission arrangement X Axial direction L Running direction Q Transverse force B Toothed-belt width Z Tooth spacing