Gearwheel for an Electric Vehicle Transmission

Abstract

A gearwheel (20) for a gear step in an electric vehicle transmission (18) includes a gearwheel carrier and a toothed ring (30) having an external toothing (42). The toothed ring is rotationally fixable to the gearwheel carrier. The gearwheel carrier is formed by a first partial carrier (38) and a second partial carrier (40) that are at least partially axially spaced apart and extend from the toothed ring radially inward. An axial spacing of the two partial carriers is greater, at least partially, than an axial length of the toothed ring.

Claims

1-15: (canceled)

16. A gearwheel (20) for a gear step in an electric vehicle transmission (18), comprising: a gearwheel carrier; and a toothed ring (30) having an external toothing (42), the toothed ring rotationally fixable to the gearwheel carrier, wherein the gearwheel carrier is formed by a first partial carrier (38) and a second partial carrier (40) that are at least partially axially spaced apart and extend from the toothed ring radially inward, and wherein at least a portion of an axial spacing (D) between the first and second partial carriers (38, 40) is greater than an axial length of the toothed ring.

17. The gearwheel (20) of claim 16, wherein the first partial carrier (38) is formed by at least one section of a first housing section of a housing (36) for a transmission component (24), and the second partial carrier (40) is formed by at least one section of a second housing section of the housing (36) for the transmission component (24).

18. The gearwheel (20) of claim 17, wherein the housing (36) of the transmission component (24) defines a radial area between the transmission component and the toothed ring (30) such that a gearwheel diameter is greater than a radial length of the transmission component.

19. The gearwheel (20) of claim 17, wherein a ratio of a radial length of the housing (36) of the transmission component (24) with respect to a radial length of the transmission component is greater than two.

20. The gearwheel (20) of claim 17, wherein the transmission component (24) comprises a differential, and the housing (36) of the differential is formed from housing sections that are symmetrical.

21. The gearwheel (20) of claim 16, wherein the toothed ring (30) is connected to the gearwheel carrier in one or more of a form-locking, friction-locking, and force-locking manner.

22. The gearwheel (20) of claim 21, wherein the toothed ring (30) is connected to the gearwheel carrier by one or more of bonding, screwing, pressing, and welding the toothed ring to the gearwheel carrier.

23. The gearwheel (20) of claim 16, wherein one or both of the first partial carrier (38) and the second partial carrier (40) comprises a reinforcement in the form of a support grid arranged at the one or both of the first and second partial carriers (38, 40) in order to counteract axial loads acting upon the gearwheel during an operation of the electric vehicle transmission (18), the reinforcement having one or both of a honeycomb pattern and a waffle pattern.

24. The gearwheel (20) of claim 16, wherein one or more of: the external toothing (42) has a module in the range from one millimeter to one and eight-tenths millimeters; the external toothing has helical teeth having a helix angle β (beta) in the range from five degrees to forty-five degrees; the toothed ring (30) has an outer diameter in the range from twenty-six centimeters to thirty-four centimeters; the external toothing has a tooth depth in the range from one millimeter to two and a half millimeters; and the toothed ring is made of metal.

25. The gearwheel (20) of claim 16, wherein one or more of: the external toothing (42) has a module of one and fifty-one hundredths millimeters; the external toothing has helical teeth having a helix angle β (beta) in the range from twenty degrees to thirty degrees; the toothed ring (30) has an outer diameter in the range from twenty-six centimeters to thirty-one and forty-eight hundredths centimeters; the external toothing has a tooth depth of one and a half millimeters; and the toothed ring is made of case hardened steel.

26. The gearwheel (20) of claim 16, wherein: the external toothing has a spur gear tooth system or a bevel gear cutting; and the external toothing comprises an involute gearing.

27. The gearwheel (20) of claim 26, wherein the involute gearing has an addendum modification.

28. The gearwheel (20) of claim 16, wherein one or both of: the first partial carrier (38) has a profile in a radial direction that differs from the second partial carrier (40); and the first partial carrier has a wall thickness that differs from the second partial carrier.

29. The toothed ring (30) for the gearwheel (20) of claim 16, wherein an outer diameter of the toothed ring has a ratio with respect to a shaft diameter of a shaft for the gearwheel in the range from six to seven and seven-tenths.

30. An electric vehicle transmission (18) for an electric vehicle (10), comprising: a gearwheel arrangement with the gearwheel (20) of claim 16; and a pinion (26) in engagement with the gearwheel, the pinion drivingly connectable to an electric prime mover (22), wherein a center distance between a center of the pinion and a center of the gearwheel is in the range from fourteen and a half centimeters and twenty centimeters.

31. The electric vehicle transmission (18) of claim 30, wherein the center distance between the center of the pinion and the center of the gearwheel is in the range from seventeen and a half centimeters and eighteen centimeters.

32. The electric vehicle transmission (18) of claim 30, wherein the electric vehicle transmission has a single gear step established by the gearwheel arrangement.

33. The electric vehicle transmission (18) of claim 30, wherein the gearwheel arrangement is configured for forming a ratio greater than five and a half.

34. The electric vehicle transmission (18) of claim 30, wherein the gearwheel arrangement is configured for forming a ratio greater than eight.

35. An electric vehicle (10), comprising: the electric vehicle transmission (18) of claim 30; a differential, wherein the toothed ring (30) is rotationally fixed to a housing (36) of the differential in order to form the gearwheel (20); and an electric prime mover (22), wherein the pinion (26) is arranged, in a rotationally fixed manner, at an output shaft (28) of the electric prime mover and is in engagement with the gearwheel in order to multiply an input power of the electric prime mover.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Example aspects of the invention are described and explained in greater detail in the following with reference to a few selected exemplary embodiments in conjunction with the attached drawings, in which:

[0036] FIG. 1 shows a schematic of an electric vehicle with an electric vehicle transmission having a gearwheel according to example aspects of the present invention;

[0037] FIG. 2 shows a schematic of a gearwheel according to the invention in a first example embodiment;

[0038] FIG. 3 shows a schematic of a gearwheel according to the invention in a second example embodiment;

[0039] FIG. 4 shows a schematic of a gearwheel according to the invention in a third example embodiment;

[0040] FIG. 5 shows a diagrammatic top view of a toothed ring of a gearwheel according to example aspects of the invention;

[0041] FIG. 6 shows a diagrammatic sectioning of a toothed ring of a gearwheel according to example aspects of the invention; and

[0042] FIG. 7 shows a schematic of a gearwheel according to the invention in a fourth example embodiment.

DETAILED DESCRIPTION

[0043] Reference will now be made to embodiments of the invention, one or more examples of which are shown in the drawings. Each embodiment is provided by way of explanation of the invention, and not as a limitation of the invention. For example, features illustrated or described as part of one embodiment can be combined with another embodiment to yield still another embodiment. It is intended that the present invention include these and other modifications and variations to the embodiments described herein.

[0044] In FIG. 1, an electric vehicle 10 with driving wheels 12, a drive shaft 14 operatively connected to the driving wheels 12, and a drive train 16 is diagrammatically shown. The figure corresponds to a top view. The relevant components are represented enlarged and not true to scale. The drive train 16 includes an electric vehicle transmission 18 with a gearwheel pair having a gearwheel 20 according to the present application, an electric prime mover 22, and a transmission component 24. In the represented example, the transmission component 24 is a differential. The electric prime mover 22 is operatively connected to a pinion 26, which is arranged, in a rotationally fixed manner, at an output shaft 28 of the electric prime mover. The pinion 26 is in engagement with the gearwheel 20, which is formed by a toothed ring 30, which is arranged at the transmission component 24. The toothed ring 30 is rotationally fixed to a housing of the transmission component 24. By the transmission component 24, which includes a differential, a drive force can be transferred to the driving wheels 12. The pinion 26, the gearwheel 20, and the transmission component 24 can be accommodated in a transmission housing 32.

[0045] FIG. 2 shows a schematic of a gearwheel 20 according to the present application in a first example embodiment. The gearwheel 20 includes a toothed ring 30, which is rotationally fixed at a housing 36 by a screw 34 in this example. The housing 36 has a first housing section and a second housing section and is arranged at the input shaft 14. The first housing section is utilized as a first partial carrier 38 and the second housing section is utilized as a second partial carrier 40 of the gearwheel 20. In this example, the gearwheel 20 is designed as a spur gear. The toothed ring 30 therefore has an external toothing 42 in the form of a spur gear tooth system. The transmission component 24, which includes a differential, is accommodated in the housing 36 in a cavity 44 provided therefor. For the sake of clarity, the representation of a transmission housing and of bearings was omitted. The housing 36 has, in addition to the cavity 44 for the transmission component 24, a further section extending radially outward, in order to be able to select the outer diameter of the gearwheel 20 independently, in particular greater than a radial extension of the transmission component. In this example, the first housing section or the first partial carrier 38 is designed symmetrically to the second housing section or the second partial carrier 40. If the transmission component is a differential, the first housing section is also referred to as a differential case and the second housing section is also referred to as a differential cover.

[0046] It is understood that an asymmetrical design can also be provided, depending on the demand for installation space and geometry of the drive train 16. The external toothing 42 can be designed in the form of a helical gearing. High forces are exerted upon the gearwheel 20 in the axial direction during operation. The symmetrical configuration of the first housing section and of the second housing section results in a consistent durability of the gearwheel 20 regardless of the direction of rotation.

[0047] Moreover, it can also be provided to adapt the radial profile of the first partial carrier 38 and/or of the second partial carrier 40 according to a preferred direction of rotation of the gearwheel 20, in order to be able to better support the arising axial loads. A weight-optimized gearwheel carrier in the form of the first partial carrier 38 and the second partial carrier 40 can be provided. For example, the wall thickness can be varied, preferably reduced, when a lower axial load is to be expected. It can also be provided to provide a profile for at least one of the two partial carriers 38, 40 that is essentially straight in the radial direction. For example, in order to oppose the resultant axial force for a direction of rotation, in which the electric vehicle 10 is accelerated, a partial carrier 38, 40, in the form of a housing section, that is as long as possible in order to be able to better counteract the axial force.

[0048] In FIG. 2, the first partial carrier 38 is arranged at a radially outer end adjacent to the second partial carrier 40, wherein, offset with respect thereto, the toothed ring 30 is screwed onto the housing 36. It is understood that the toothed ring can also be welded or bonded onto the housing 36, and/or pressed together with the housing 36. In general, any force-fit connection, frictional connection, and/or positive engagement is conceivable, in order to rotationally fix the toothed ring 30 to the housing.

[0049] In the following, the differences between the individual embodiments are to be discussed. Identical reference characters refer to identical features and are not explained once more.

[0050] In FIG. 3, a schematic of a gearwheel 20 according to the present application is shown in a second example embodiment. Here, the toothed ring 30 is arranged between the first partial carrier 38 (first housing section) and the second partial carrier 40 (second housing section). The toothed ring 30 can be supported at the two axial ends by the first partial carrier 38 and the second partial carrier 40. Preferably, the screw 34 can be smaller-dimensioned, since less force is transmitted via the screw 34 during the operation of the electric vehicle transmission 18. The toothed ring 30 is situated partially on the first partial carrier 38 and the second partial carrier 40. Preferably, a better part of the force is transmitted directly into the first partial carrier 38 and/or the second partial carrier 40. Similarly to the screw, the press-fit, clamping, bonded, and/or welded connection between the toothed ring 30 and the housing 36 can also be smaller-dimensioned. Preferably, weight can be further saved as a result.

[0051] In the example embodiments according to FIGS. 2 and 3, an external toothing 42 in the form of a spur gear tooth system is provided. An electric prime mover 22 is arranged essentially in parallel to the input shaft 14. The arrangement according to FIGS. 2 and 3 corresponds to the schematic in FIG. 1.

[0052] In FIG. 4, a schematic of a gearwheel 20 according to the invention is shown in a third example embodiment. Here, the toothed ring 30 of the gearwheel 20 has an external toothing 42 in the form of a bevel gear cutting. As a result, the electric prime mover 22 can be arranged essentially perpendicularly to the input shaft 14. It is understood that, in this example embodiment as well, the toothed ring 30 can be arranged next to the housing 36 as shown in FIG. 4 or, similarly to the embodiment shown in FIG. 3, between the two partial carriers 38, 40.

[0053] In FIG. 5, a diagrammatic top view of a toothed ring 30 according to example aspects of the invention is shown. The toothed ring 30 has an external toothing 42 in the form of a spur gear tooth system in this example. A fastening section 48 is located between a toothed-ring inner side 46 and the external toothing 42, in order to connect the toothed ring 30 to the housing 36. In this example, bore holes 50 are provided for this purpose, in order to make it possible to screw on the toothed ring 30. The fastening section 48 can also have a bonding, press-fit, clamping, and/or welding surface, however, in order to fasten the toothed ring 30 at the housing 36.

[0054] In FIG. 6, a sectioning of the toothed ring 30 according to FIG. 5 is shown. The cut edge extends through the centers of two radially opposed bore holes 50. The toothed ring 30 shown in FIGS. 5 and 6 has a helical-cut spur gear tooth system. It is understood that the toothed ring 30 can also have a bevel gear cutting. Preferably, the toothing has a module of one and fifty-three hundredths millimeters (1.53) mm, wherein the helix angle β is twenty-five degrees (25°). The outer diameter of the toothed ring 30 is thirty-one and forty-eight hundredths centimeters (31.48 cm). The depth of the external toothing is one and a half millimeters (1.5 mm). The toothed ring 30 is provided for a gearwheel that can be arranged at a shaft (not shown) having a diameter in the range from four and a half centimeters (4.5 cm) to five centimeters (5 cm).

[0055] The toothed ring 30 is formed from case hardened steel, wherein the hardening process can be advantageously carried out due to the provision of a toothed ring 30 that is mounted onto a housing 36. A toothed ring has a smaller radial distance than a gearwheel, and so a distortion in a hardening process is less than is the case with a gearwheel.

[0056] In FIG. 7, a schematic of a gearwheel 20 according to the invention is shown in a fourth example embodiment. The gearwheel essentially corresponds to the gearwheel 20 shown in FIG. 3. In the represented example, the first partial carrier 38 is reinforced by a reinforcement 52 in the form of a disk, which has a waffle pattern and/or a honeycomb pattern. It is understood that the reinforcement can also be arranged on the second partial carrier 40 or on both partial carriers 38, 40. This disk can be bonded onto at least one of the partial carriers 38, 40, i.e., welded or integrally formed with one of the partial carriers 38, 40. It is also conceivable to crimp or press such a disk into a partial carrier 38, 40.

[0057] In general, any known production possibility is conceivable, in order to provide a weight-optimized reinforcement, in particular in the form of a disk having an appropriate pattern.

[0058] In the represented examples, it can also be provided to at least partially provide recesses in at least one of the partial carriers 38, 40, in order to obtain a sufficient rigidity or durability in combination with a weight reduction.

[0059] The invention was comprehensively described and explained with reference to the drawings and the description. The description and the explanation are to be understood as an example and are not to be understood as limiting. The invention is not limited to the disclosed embodiments. Other embodiments or variations result for a person skilled in the art within the scope of the utilization of the present invention and within the scope of a precise analysis of the drawings, the disclosure, and the following claims.

[0060] In the claims, the words “comprise” and “comprising” do not rule out the presence of further elements or steps. The indefinite article “a” does not rule out the presence of a plurality. The mere mention of a few measures in multiple various dependent claims is not to be understood to mean that a combination of these measures cannot also be advantageously utilized. Reference numbers in the claims are not to be understood as limiting.

[0061] Modifications and variations can be made to the embodiments illustrated or described herein without departing from the scope and spirit of the invention as set forth in the appended claims. In the claims, reference characters corresponding to elements recited in the detailed description and the drawings may be recited. Such reference characters are enclosed within parentheses and are provided as an aid for reference to example embodiments described in the detailed description and the drawings. Such reference characters are provided for convenience only and have no effect on the scope of the claims. In particular, such reference characters are not intended to limit the claims to the particular example embodiments described in the detailed description and the drawings.

REFERENCE CHARACTERS

[0062] 10 electric vehicle [0063] 12 driving wheels [0064] 14 drive shaft [0065] 16 drive train [0066] 18 electric vehicle transmission [0067] 20 gearwheel [0068] 22 electric prime mover [0069] 24 transmission component [0070] 26 pinion [0071] 28 output shaft of the electric prime mover [0072] 30 toothed ring [0073] 32 transmission housing [0074] 34 screw [0075] 36 housing [0076] 38 first partial carrier [0077] 40 second partial carrier [0078] 42 external toothing [0079] 44 cavity for housing component [0080] 46 toothed ring inner side [0081] 48 fastening section [0082] 50 bore hole [0083] 52 reinforcing means [0084] D axial spacing