Gear for use in a gear transmission, gear pairing of a gear transmission and gear transmission with such a gear pair

Abstract

A toothed gear for use in a gearing, comprising a base body that forms a ring gear with a number of first teeth having a first deformability and a number of second teeth having a second deformability, wherein the second deformability is greater than the first deformability and to a gear pair of a gearing, comprising such a toothed gear and at least one further toothed gear which can be made to mesh or is in mesh with the toothed gear. The invention relates moreover to a gearing with such a gear pair.

Claims

1. A toothed gear for use in a gearing, comprising: a base body having a longitudinal axis and forming a ring gear, with the ring gear comprising: a plurality of first teeth having a first deformability, a plurality of second teeth having a second deformability, wherein the second deformability is greater than the first deformability, wherein the second teeth disposed on a circular sector-shaped common carrier that is disposed within a circular sector-shaped opening of the ring gear and having an oversize compared to the first teeth, and wherein the second teeth have the oversize only in a circumferential direction.

2. The toothed gear as in claim 1, wherein the ring gear in a region of the second teeth within the common carrier is free of interruptions in the circumferential direction.

3. The toothed gear as in claim 1, wherein the common carrier comprises a circular sector shaped cutout or a cavity along the longitudinal axis.

4. The toothed gear as in claim 3, wherein the common carrier comprises a cut, starting from the cutout or the cavity and extending radially outwardly, or a slit, starting from the cutout or the cavity and extending radially outwardly.

5. The toothed gear as in claim 4, wherein the common carrier has an axial distance in the direction of the longitudinal axis and/or a circumferential distance from the first teeth.

6. The toothed gear as in claim 1, wherein the second teeth have a tooth profile with a tooth tip modification.

7. The toothed gear as in claim 1, wherein the second teeth comprise a radially outwardly extending groove or a radially outwardly extending gap.

8. The toothed gear as in claim 1, wherein the second teeth toothed-gear is comprised of a technical thermoplastic or a high-performance thermoplastic, and wherein the toothed gear has a modulus of elasticity of 1000 to 3500 MPa.

9. The toothed gear as in claim 8, wherein the technical thermoplastic or the high-performance thermoplastic is self-reinforcing or fiber-reinforced, wherein the fiber component is up to 35%.

10. The toothed gear as in claim 8, wherein the first teeth toothed gear has a modulus of elasticity between 6000 and 13000 MPa where the technical thermoplastic or the high-performance thermoplastic is self-reinforcing or fiber-reinforced.

11. The toothed gear as in claim 1 wherein: the first teeth are comprised of a first technical thermoplastic or a first high-performance thermoplastic, the second teeth are comprised of a second technical thermoplastic or a high-performance thermoplastic, wherein the second technical thermoplastic or the second high-performance thermoplastic has a lower modulus of elasticity and/or a lower thermal coefficient of expansion than the first technical thermoplastic or the first high-performance thermoplastic.

12. The toothed gear as in claim 1, wherein one tooth of the second teeth has an oversize only in the counterclockwise circumferential direction and two of the second teeth have an oversize only in the clockwise circumferential direction.

13. The toothed gear as in claim 1, wherein the second teeth are asymmetric with each second tooth being oversized in the counterclockwise circumferential direction or oversized in the clockwise circumferential direction.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) Exemplary embodiments of the application will be explained in the following in greater detail with reference to the attached drawing. Therein depict:

(2) FIG. 1A to 1C a first embodiment example of a gear pair in conjunction with different views,

(3) FIG. 2 a second embodiment example of a toothed gear according to the application in conjunction with a fundamental sectional representation,

(4) FIG. 3 a third embodiment example of a toothed gear according to the application in conjunction with a fundamental sectional representation,

(5) FIGS. 4A and 4B a fourth embodiment example of a gear pair according to the application in conjunction with different views,

(6) FIG. 4C an isolated perspective representation of a toothed gear of the gear pair according to the fourth embodiment example,

(7) FIG. 5A to 5C a fifth embodiment example of a gear pair according to the application in conjunction with different views,

(8) FIG. 5D an isolated representation, not to scale, of a representation of a toothed gear of a gear pair according to the fifth embodiment example,

(9) FIG. 6 an isolated top view of a sixth embodiment example of a gear pair according to the application, wherein the proposed toothed gear is only partially shown,

(10) FIGS. 7A and 7B a basic representation of tooth profiles, in which the [seventh] proposed gear pair can be applied,

(11) FIG. 8A a basic representation of a gearing with a [seventh] proposed gear pair,

(12) FIG. 8B an isolated representation, not to scale, of a toothed gear of the gear pair according to the seventh embodiment example.

DETAILED DESCRIPTION

(13) In FIGS. 1A to 1C is depicted a first embodiment example of a gear pair 10.sub.1 according to the disclosure with reference to several different views. FIG. 1A shows herein a perspective view while FIG. 1B is a bottom view and FIG. 1C is a sectional representation along the section plane X-X defined in FIG. 1B. The gear pair 10.sub.1 comprises a toothed gear 12.sub.1 according to a first embodiment example, and a further toothed gear 14, wherein the toothed gear 12.sub.1 and the further toothed gear 14 are in mesh. In the first embodiment example the toothed gear 12.sub.1 and the further toothed gear 14 are implemented as spur gears with straight-cut toothing.

(14) The toothed gear 12.sub.1 comprises a base body 16 (see FIG. 1C) which forms a ring gear 18. The ring gear 18 comprises a number of first teeth 20 and a number of second teeth 22. In the first embodiment example the number of first teeth 20 and that of second teeth 22 is identical, however it can also differ (see FIGS. 4 to 6). The first teeth 20 as well as also the second teeth 22 are disposed uniformly distributed over the entire circumference of the proposed toothed gear 12.sub.1. In the region of the first teeth 20 the ring gear 18 is circumferentially closed without interruption.

(15) As is especially evident in FIG. 1C, the base body 16 forms a cylindrical hub section 24. The second teeth 22 comprise rod-shaped connection webs 26 with which the second teeth 22 are connected to the hub section 24. The connection webs 26 start from the hub section 24 and extend substantially radially outwardly. In the first embodiment example each second tooth 22 in each instance comprises one connection web 26 such that the number of connection webs 26 is equal to the number of second teeth 22.

(16) The first teeth 20 are connected with the hub section 24 across a disk-shaped connection section 28 formed by the hub section 24, wherein the connection section 28 comprises an annular cavity 30. The annular cavity [30] serves primarily for the technical molding optimization of the toothed gear 12.sub.1, for example in order to avoid the formation of shrinkage voids during the production of the toothed gear 12.sub.1 according to the disclosure. In addition, material can be saved in this manner.

(17) The first teeth 20 have a first deformability v1 and the second teeth 22 have a second deformability v2. Due to the geometric shaping and/or the selection of the material parameters of the first teeth 20 and of the second teeth 22, the second deformability v2 is greater than the first deformability v1.

(18) The proposed toothed gear 12.sub.1 has a longitudinal axis L (cf. FIG. 1C) about which the toothed gear 12.sub.1 in the operationally ready state is rotatable. Referred to the longitudinal axis L, the second teeth 22 are disposed on the hub section 24 such that they are offset with respect to the first teeth 20 and such that a distance AA is formed in the axial direction between the first teeth 20 and the second teeth 22. The first width B1 is herein greater than the second width B2.

(19) Between two adjacent connection webs 26 there remains a radially outwardly increasing distance AS (see FIG. 1A) such that the ring gear 18 in the region of the second teeth 22 is not closed in the circumferential direction, in contrast to the region of the first teeth 20.

(20) In the first embodiment example the toothed gear 12.sub.1 is fabricated of a technical thermoplastic or a high-performance thermoplastic. Examples of such thermoplastics are POM (polyoxymethylene), PA (polyimide), PK (polyketone), PPA (polyphthalamide), PEEK (polyetheretherketone) or PPS (polyphenylsulfide). In the entire toothed gear 12.sub.1 obtains a modulus of elasticity E of 1000 to 3500 MPa. Depending on the utilized thermoplastic and the desired modulus of elasticity E, the thermoplastic can be self-reinforcing or fiber-reinforced. In this case the toothed gear 12.sub.1 can be regionally equipped with different moduli of elasticity E. For example, the entire toothed gear 12.sub.1, except for the connection webs 26 and the second teeth 22, can be fabricated with a self-reinforcing or fiber-reinforced thermoplastic such that the connection webs 26 and the second teeth 22 have the increased second deformability v2, while the toothed gear 12.sub.1 in the remaining region has the decreased first deformability v1.

(21) It is especially evident in FIG. 1B that the second teeth 22 are disposed with respect to the first teeth 20 such that an oversize in the circumferential direction is attained. In the first embodiment example the second teeth 22 are shaped such that, with respect to the representation in FIG. 1B, a one-sided oversize compared to the first teeth 20 in the clockwise direction results, wherein the toothed gear 12.sub.1 can also be shaped such that the one-sided oversize in the clockwise direction results. Based thereon, it is apparent that the oversize can be provided by the disposition alone of the second teeth 22, with respect to the first teeth 20, alone. A one-sided oversize can suffice to attain the desired effects onto the circumferential backlash. It is therefore not mandatory that the tooth flanks have a bilateral thickening.

(22) In FIG. 2 is shown a second embodiment example of the toothed gear 12.sub.2 based on a sectional representation oriented along the section plane X-X of FIG. 1B. The fundamental structure of the toothed gear 12.sub.2 according to the second embodiment example resembles the structure of toothed gear 12.sub.1 according to the first embodiment example such that in the following only their differences will be discussed. The hub section 24, the connection section 28 and the first teeth 20 are fabricated of a first technical thermoplastic or a first high-performance thermoplastic, whereas the second teeth 22 and the connection webs 26 are comprised of a second technical thermoplastic or a second high-performance thermoplastic. The first technical thermoplastic or the first high-performance thermoplastic have herein a first modulus of elasticity E1 and the second technical thermoplastic or the second high-performance thermoplastic have a second modulus of elasticity E2, wherein the first modulus of elasticity E1 is higher than the second modulus of elasticity E2.

(23) Alternatively or cumulatively, the first technical thermoplastic or the first high-performance thermoplastic has a first thermal coefficient of expansion 1 and the second technical thermoplastic or the second high-performance thermoplastic has a thermal coefficient of expansion 2, wherein the first thermal coefficient of expansion 1 is higher than the second thermal coefficient of expansion 2.

(24) In addition, on the connection webs 26 a number of fins 32 is disposed which fins, starting at the hub section 24, extend substantially radially outwardly.

(25) In FIG. 3 a third embodiment example of the toothed gear 12.sub.3 is shown also based on a sectional representation oriented along the sectional plane X-X of FIG. 1B. In the third embodiment example the second width B2 of the connection web 26 is changed such that, starting from the hub section 24, it decreases radially outwardly.

(26) In FIGS. 4A and 4B a fourth embodiment example of the gear pair 10.sub.4 according to the disclosure is depicted by means of a perspective representation and a bottom view, respectively, which comprises a toothed gear 12.sub.4 according to a fourth embodiment example. In FIG. 4C the toothed gear 12.sub.4 shown in isolation based on a perspective representation. In the fourth embodiment example the second teeth 22 are disposed in a circular sector-shaped region S uniformly distributed in the circumferential direction. The ring gear 18 consequently comprises only the second teeth 22 in the circular sector-shaped region S and which teeth are not distributed over the entire circumference.

(27) In FIG. 4B is evident that the second teeth 22 are shaped as they are also in the first embodiment example such that they provide a one-sided oversize compared to the first teeth 20. In reference to the representation in FIG. 4B, the oversize is disposed counterclockwise compared to the first teeth 20. An oversize compared to the first teeth 20 in the clockwise direction is also conceivable.

(28) As is in particular evident in FIG. 4C, the first width B1 of the first teeth 20 within the circular sector-shaped in the region S is less than [such width] outside [of S]. The circular sector-shaped region S is delimited in the circumferential direction by the first teeth 20 which have the greater first width B1. Again, there remains an axial distance AA between the first teeth 20 and the second teeth 22. As was the case in the three previously described embodiment examples, there remains between two adjacent connection webs 26 a radially increasing distance AS such that the ring gear 18 is not closed within the second teeth 22 in the circular sector-shaped region S.

(29) In FIGS. 5A to 5C a fifth embodiment example of the gear pair 10.sub.5 with a toothed gear 12.sub.5 according to a fifth embodiment example is shown based on several different representations, wherein FIG. 5A is a perspective view, FIG. 5B a bottom view and FIG. 5C a top view. In FIG. 5D the toothed gear 12.sub.5 according to the fifth embodiment example is depicted not-to-scale in isolation based on a side view. In the fifth embodiment example the second teeth 22 are disposed on a common carrier 36 that is disposed within a circular sector-shaped region S. The first teeth 20 have in the fifth embodiment example also within the circular sector-shaped region S a lesser first width B1 than outside of S. The circular sector-shaped region S is again delimited in the circumferential direction by the first teeth 20 which have the greater first width B1.

(30) The common carrier 36 comprises a cutout 38 or a cavity, in particular for the purpose of increasing the second deformability v2 and to decrease the formation of shrinkage voids. The common carrier 36 can be developed as a separate structural part and be slid onto the hub section 24. In particular when the common carrier 36 is developed as a separate structural part, it lends itself to fabricate the common carrier 36 of the already cited second technical thermoplastic or the second high-performance thermoplastic. Overall three second teeth 22 are disposed on the common carrier 36 which, however, in contrast to the second teeth 22 of toothed gears 12, mesh without interruption. In principle, it would suffice to provide only one second tooth 22 in order to attain the effect according to the disclosure, which will be discussed in greater detail further down.

(31) In FIGS. 5B and 5C is evident that there is also only a one-sided oversize provided in the fifth embodiment example 10.sub.5. In reference to FIG. 5B, the second teeth 22 are shaped such that, in reference to the first teeth 20, they provide one oversize in the counterclockwise direction and two oversizes in the clockwise direction. Other combinations of the orientation of the oversize in reference to the clockwise direction are also feasible.

(32) As is evident in FIG. 5D, the second teeth 22 disposed on the common carrier 36 have along the longitudinal axis L an axial distance AA and in the circumferential direction on both sides a circumferential distance AU. However, it is equally feasible to dispose the common carrier 36 in the axial direction in front or behind the first teeth 20 such that it is not necessary to provide the circular sector-shaped region S.

(33) In FIG. 6 is depicted a sixth embodiment example of the gear pair 10.sub.6 based on a top view, which to a large extent resembles the gear pair 10.sub.5 according to the fifth embodiment example. For reasons of representation, only the common carrier 36 of toothed gear 12.sub.6 of the sixth embodiment example is therefore shown. Starting from the cavity or from the cutout 38, the common carrier 36 comprises a split 40 that can also be shaped as a cut. The common carrier 36 is hereby specifically and purposefully weakened such that it, and consequently also the second teeth 22, has an increased second deformability v2. In particular the central one of the second teeth 22 acquires hereby an increased radial mobility.

(34) In FIGS. 7A and 7B a first tooth 20 with a first tooth profile 42.sub.1, and, respectively, a second tooth 22 with a second tooth profile 42.sub.2 are shown in conjunction with a fundamental view. The first tooth profile 42.sub.1, depicted in FIG. 7A, defines an involute toothing system. The second tooth profile 42.sub.2, based also on the involute toothing system depicted in FIG. 7A, however has a tip modification 44 such that it tapers outwardly and is more pointed than the first tooth profile 42.sub.1 shown in FIG. 7A. Alternatively or additionally, the second tooth 22 can have an increased tooth thickness in particular at least at one of the tooth flanks.

(35) The second tooth 22 provided with the second tooth profile 42.sub.2, furthermore, comprises a radially outwardly extending groove or an also radially outwardly extending gap 46, which completely extends axially through the second tooth 22. The second deformability v2 can hereby be increased. The first tooth 20 as well as also the second tooth 22 extend symmetrically with reference to a center line M. In particular with reference to the FIGS. 1A, 4A and 4C, it becomes apparent that the second tooth profile 42, with reference to the center line M, does not mandatorily need to be structured symmetrically in order to be able to attain the effect according to the disclosure.

(36) In FIG. 8A a gearing 48 is shown in conjunction with a fundamental sectional representation, which comprises a gear pair 10.sub.7 according to a seventh embodiment example. In the depicted gearing 48 the toothed gear 12.sub.7 is connected to a drive shaft 50, whereas the further toothed gear 14 is connected to an output shaft 52. The drive shaft 50 is connected with a torque source 51, for example with an electric motor.

(37) The drive shaft 50 and the output shaft 52 are supported in a housing 54 that encompasses a hollow volume 56 in which the toothed gear 12.sub.7 and the further toothed gear 14 are disposed such that they are in mesh. The toothed gear 12.sub.7 is herein fabricated of the cited technical thermoplastic or the high-performance thermoplastic, whereas the further toothed gear 14 is fabricated of a metal. The further toothed gear 14 can however also be fabricated of synthetic material. In FIG. 8B the toothed gear 12.sub.7 according to the seventh embodiment example is shown in conjunction with a fundamental plan side view which is utilized in the gearing 48 depicted in FIG. 8A. In contrast to the previously introduced embodiments examples, the toothed gear 12.sub.7 according to the seventh embodiment example has a helical toothing 58 with a helix angle that is up to 15 and in particular between 1 and 19. The further toothed gear 14 has a correspondingly shaped helical toothing (not shown).

(38) The gearing 48 is operated in the following manner: in the resting position which, for reasons of representation, is now shown in FIG. 8A, the first teeth 20 as well as also the second teeth 22 of toothed gear 12.sub.7 are in mesh with the further toothed gear 14. In the resting position the toothed gear 12.sub.7 and the toothed gear 14 have each a starting temperature, for example ambient temperature, which, depending on the application, is at the lower edge of the operating temperature range of the gearing 48.

(39) Due to the increased second deformability v2, the second teeth 22 can be equipped with an oversize compared to the first teeth 20, which can be expressed, for example, by an increased tooth thickness. The second teeth 22 ensure at a large operating temperature range, for example at temperatures near the lower end of the operating temperature range, a lower circumferential backlash, while the first teeth 20 at temperatures near the upper end of the operating temperature range keep the circumferential backlash low. During operation of the gearing 48, which is started in particular with the activation of the torque source 51, the toothed gear 12.sub.1 and the further toothed gear 14 become heated. The heating of toothed gear 12.sub.1 and of the second [sic: further] toothed gear 14, however, can also be brought about through external effects occurring during operation, for example when a thermal process using water vapor in the immediate surroundings of the gearing 48 is carried out. There are also applications in which the gearing 48 cools due to the effects occurring during operation, for example during refrigeration processes carried out in the immediate surrounding or when the gearing 48 is moved during operation into colder surroundings such as can be the case, for example, with passenger cars or airplanes.

(40) However, in the following, the case is considered that the gearing 48 becomes heated during operation. As stated, the meshing of the first teeth 20 at the starting temperature, which conventionally is at the lower end of the operating temperature range, is not optimal. However, the meshing of the first teeth 20 improves with increasing temperature to reach its optimum, for example, at the upper end of the operating temperature range. Due to the increased second deformability v2 of the second teeth 22, the oversize of the second teeth 22 does not lead to the jamming of the toothed gears in mesh when the upper end of the operating temperature range is reached.

LIST OF REFERENCE SYMBOLS

(41) 10 Gear pair 10.sub.1-10.sub.6 First to sixth embodiment example of the gear pair 12 Toothed gear 12.sub.1-12.sub.6 First to sixth embodiment example of the toothed gear 14 Further toothed gear 16 Base body 18 Ring gear 20 First teeth 22 Second teeth 24 Hub section 26 Connection web 28 Connection section 30 Annular cavity 32 Fins 36 Common carrier 38 Cutout 40 Split 42 Tooth profile 42.sub.1 First tooth profile 42.sub.2 Second tooth profile 44 Tip modification 46 Gap 48 Gearing 50 Drive shaft 51 Torque source 52 Drive [sic: Output] shaft 54 Housing 56 Hollow volume 58 Helical toothing AA Axial distance AS Distance between two second teeth AU Circumferential distance B Width B1 First width B2 Second width E Modulus of elasticity E1 First modulus of elasticity E2 Second modulus of elasticity L Longitudinal axis M Center line S Circular sector-shaped region v1 First deformability v2 Second deformability 1 First thermal coefficient of expansion 2 Second thermal coefficient of expansion Helical angle