Gearwheel Arrangement for Electric Vehicle Transmissions

Abstract

A gearwheel arrangement (16) for establishing a gear step in an electric vehicle transmission (17) includes a pinion (22) and an output gearwheel (23). The pinion (22) and the output gearwheel (23) are configured as spur gears and are meshed with each other in order to effect a transmission of a drive power of an electric machine (18). A ratio of a gearwheel diameter to a module of the output gearwheel (23) is in the range from 140 to 350. An electric vehicle transmission (17) with such a gearwheel arrangement (16) and a drive train (15) for an electric vehicle (10) with an electric machine (18), a differential (20), and such an electric vehicle transmission (17) are also provided.

Claims

1-9. (canceled)

10. A gearwheel arrangement (16) for establishing a gear step in an electric vehicle transmission (17), comprising: a pinion (22) as spur gear; and an output gearwheel (23), wherein the pinion (22) and the output gearwheel (23) are configured as spur gears that are meshed with each other in order to effect a transmission of a drive power of an electric machine (18), wherein a ratio of a gearwheel diameter with respect to a module of the output gearwheel (23) is no less than 140 and no greater than 350, and wherein the pinion (22) and the output gearwheel (23) have a module no less than 1.0 mm and no greater than 1.8 mm.

11. The gearwheel arrangement (16) of claim 10, wherein the ratio of the gearwheel diameter with respect to the module of the output gearwheel (23) is no less than 205 and no greater than 230.

12. The gearwheel arrangement (16) of claim 10, wherein the module of the pinion (22) and the output gearwheel (23) is equal to 1.51 mm.

13. The gearwheel arrangement (16) of claim 10, wherein the ratio of the gear step is greater than 5.5.

14. The gearwheel arrangement (16) of claim 10, wherein the ratio of the gear step is equal to 8.9.

15. The gearwheel arrangement (16) of claim 10, wherein the pinion (22) and the output gearwheel (23) have a pressure angle no less than 20° and no greater than 28°.

16. The gearwheel arrangement (16) of claim 15, wherein the pressure angle of the pinion (22) and the output gearwheel (23) is equal to 24°.

17. The gearwheel arrangement (16) of claim 10, wherein: one or both of the pinion (22) and the output gearwheel (23) have a tooth depth no less than 1.0 mm and no greater than 2.5 mm; one or both of the pinion (22) and the output gearwheel (23) are made of metal; and/or one or both of the pinion (22) and the output gearwheel (23) have an involute profile.

18. The gearwheel arrangement (16) of claim 10, wherein: one or both of the pinion (22) and the output gearwheel (23) have a tooth depth of 1.5 mm; one or both of the pinion (22) and the output gearwheel (23) are made of case hardened steel; and/or one or both of the pinion (22) and the output gearwheel (23) have an addendum modification.

19. The gearwheel arrangement (16) of claim 10, wherein: the pinion (22) has a diameter no less than 3.0 cm and no greater than 6.2 cm; and/or the output gearwheel (23) has a diameter no less than 26 cm and no greater than 34 cm.

20. The gearwheel arrangement (16) of claim 10, wherein: the pinion (22) has a diameter of 3.5 cm; and/or the output gearwheel (23) has a diameter of 31.48 cm.

21. The gearwheel arrangement (16) of claim 10, wherein a center distance between a center of the pinion (22) and a center of the output gearwheel (23) is no less than 14.50 cm and no greater than 20.00 cm.

22. The gearwheel arrangement (16) of claim 10, wherein a center distance between a center of the pinion (22) and a center of the output gearwheel (23) is no less than 17.50 cm and no greater than 18.00 cm.

23. The gearwheel arrangement (16) of claim 10, further comprising an input shaft and an output shaft, wherein: the pinion (22) is arranged at the input shaft; the output gearwheel (23) is arranged at the output shaft; the input and output shafts are each mounted at shaft bearings in bearing sleeves; and a spacing distance of the bearing sleeves is predefined by a holding fixture in order to limit a drifting apart of the gearwheel arrangement (16).

24. An electric vehicle transmission (17), comprising the gearwheel arrangement (16) of claim 10, wherein the electric vehicle transmission (17) has a single gear step established by the gearwheel arrangement (16).

25. A drive train (15) for an electric vehicle (10), comprising an electric machine (18), a differential (20) and the electric vehicle transmission (17) of claim 24, wherein: the pinion (22) is arranged at an output shaft of the electric machine (18) in a rotationally fixed manner; and the output gearwheel (23) is arranged at an output shaft (14) or a differential (20) of the drive train (15) in a rotationally fixed manner in order to establish a drive force-transmission path from the electric machine (18) via the gear stage to the output shaft (14) or the differential (20).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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:

[0027] FIG. 1 shows a schematic of an electric vehicle with an electric vehicle transmission with a gearwheel arrangement according to an example embodiment of the present invention;

[0028] FIG. 2 shows a gearwheel arrangement with a gearwheel and a pinion;

[0029] FIG. 3 shows a schematic of a drive train with a gearwheel arrangement according to an example embodiment of the present invention;

[0030] FIG. 4 shows a schematic of a drive train with a gearwheel arrangement according to an example embodiment of the present invention; and

[0031] FIG. 5 shows a diagrammatic axial view of two teeth of a tooth system of a gearwheel according to an example embodiment of the invention.

DETAILED DESCRIPTION

[0032] 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.

[0033] In FIG. 1, an electric vehicle 10 with driving wheels 12, a drive axle 14 operatively connected with the driving wheels 12, and a drive train 15 is diagrammatically shown. The schematic view of FIG. 1 corresponds to an aerial view of a sectional view. The relevant components are represented enlarged.

[0034] The drive train 15 includes an electric vehicle transmission 17 with a gearwheel arrangement 16 according to example aspects of the present invention, an electric machine 18, and a differential 20. The electric machine 18 is operatively connected with a pinion 22, which is in engagement with an output gearwheel 23, wherein the output gearwheel 23 is connected, at the gearwheel base 24, with the differential 20 in a rotationally fixed manner. By the differential 20, a drive force can be further transmitted to the driving wheels 12. The pinion 22, the output gearwheel 23, and the differential 20 can be accommodated in a transmission housing 26.

[0035] During an acceleration process in a driving operation, input power is made available in the drive train 15 by the electric machine 18 and is guided to the driving wheels 12, in order to accelerate the electric vehicle 10. Therefore, a power transmission path from the electric machine 18 via the pinion 22 and the output gearwheel 23 of the gearwheel arrangement 16 and the differential 20 to the driving wheels 12 is made available. The power transmission path can provide the driving wheels 12 with input power from the electric machine 18.

[0036] In a coasting operation, i.e., when the electric vehicle 10 is to be decelerated, at least a portion of the kinetic energy of the electric vehicle 10 can be made available to the electric machine 18 via the power transmission path in the drive train 15. The electric machine 18 is driven for recuperation via the power transmission path. The electric machine 18 is utilized as a generator and converts the kinetic energy of the electric vehicle 10 into electrical energy. The converted energy can be stored in batteries, capacitors, or other storing energy units (not shown here) and supplied to the electric machine 18 again as necessary, i.e., when the electric vehicle 10 is to be accelerated.

[0037] In a sailing operation, i.e., when the electric vehicle 10 is to be neither accelerated nor decelerated, essentially no power is transmitted through the power transmission path.

[0038] FIG. 2 shows a gearwheel arrangement 16 in the electric vehicle transmission 17 with the pinion 22 and the output gearwheel 23. The output gearwheel 23 has a gearwheel outer side 28, a carrier 30, a gearwheel base 24, and an outer toothing 32 at the outer side 28. The pinion 22 is arranged between the electric machine 18 and the output gearwheel 23. The pinion 22 can also be referred to as an input pinion.

[0039] Such a gearwheel arrangement 16 can be provided, for example, in an electric vehicle transmission 17, in which high ratios of up to ten (10) can be implemented using only one gearwheel pair 22, 23. Ratios of this type are advantageous, since modern electric machines can be operated with up to twenty-thousand (20,000) revolutions per minute. In this case, both a driving condition, in which the pinion 22 is driven by the electric machine 18, as well as a coasting condition, in which the pinion 22 is driven by the output gearwheel 23, preferably for the recuperation of energy, can be provided.

[0040] In the example shown, the output gearwheel 23 has a ratio of a gearwheel diameter with respect to a module in the range of approximately two hundred, eight and a half (208.5). As a result, a high ratio can be achieved using only one gearwheel pair 22, 23 by the gearwheel arrangement 16. Such small modules contribute, in particular, to ensuring that few losses occur in the gearwheel arrangement 16. In the gearwheel arrangement 16, the pinion 22 and the output gearwheel 23 have a module of one and fifty-one hundredths millimeter (1.51 mm). The ratio i_Stufe of the gear step achieved by the gearwheel arrangement 16 is eight and nine-tenths (8.9). It is understood that other ratios can also be implemented by the gearwheel arrangement 16 according to example aspects of the invention. The pressure angle between the pinion 22 and the output gearwheel 23 is twenty-four degrees (24°). This pressure angle is to be understood as an example. It is understood that the gearwheel arrangement 16 can also have other pressure angles, in particular pressure angles of approximately seventeen and a half (17.5°), as is common in vehicle transmissions. A diameter of the pinion 22 is approximately three and a half (3.5 cm). The output gearwheel 23 has a diameter of approximately thirty-one and forty-eight hundredths centimeter (31.48 cm). It is understood that the gearwheel diameters were selected for this example embodiment and other gearwheel diameters are also conceivable. The center distance between a center of the pinion 22 and a center of the output gearwheel 23 is approximately seventeen and a half centimeters (17.5 cm). It is understood that other center distances can also be selected, in particular center distances of less than ten centimeters (10.0 cm), as is common in the motor vehicle sector and the electric vehicle sector.

[0041] The aforementioned ranges and sizes are to be understood as examples for the embodiment shown in FIG. 2. Consequently, it is understood that variations result for a person skilled in the art during the utilization of the present invention.

[0042] FIG. 3 shows a schematic of a drive train 15 with a gearwheel arrangement 16 according to example aspects of the present invention. Drive force is made available by an electric machine 18. The pinion 22 is rotationally fixed to an output shaft of the electric machine 18 and is in intermeshing engagement with the output gearwheel 23. The pinion 22 and the output gearwheel 23 form the gearwheel arrangement 16 according to example aspects of the invention. In this example, the output shaft of the electric machine 18 can also be considered to be an input shaft of the gearwheel arrangement 16. The output gearwheel 23 is arranged at a power transmission shaft 34 in a rotationally fixed manner. The power transmission shaft 34 transmits the input power from the gearwheel 23 to the differential 20, wherein the differential 20 then transmits the input power via the drive axle 14 onto the driving wheels 12. In this example, the power transmission shaft 34 can also be considered to be an output shaft of the gearwheel arrangement 16. It is understood that a type of all-wheel drive can also be provided, wherein the power transmission shaft 34 (power transmission axle) additionally drives a further differential, in order to drive two further wheels 12 of the electric vehicle 10.

[0043] FIG. 4 shows a schematic of a drive train 15 with a gearwheel arrangement 16 according to example aspects of the present invention. Identical reference characters relate to identical features as in FIG. 3. In the example embodiment shown in FIG. 4, the pinion 22 is also rotationally fixed to an output shaft of the electric machine 18 and is in intermeshing engagement with the output gearwheel 23. The differential 20 is connected to the output gearwheel 23 in a rotationally fixed manner in such a way that input power is supplied to the differential 20 by the output gearwheel 23, wherein the differential 20 distributes the input power to the driving wheels 12 via the drive axle 14. In this example, the drive axle 14 can also be considered to be an output shaft of the gearwheel arrangement 16. In this compact example embodiment, as compared to the embodiment shown in FIG. 3, the power transmission shaft 34 can therefore be omitted, and so the example configuration according to FIG. 4 is more compact and, preferably, also more lightweight than the configuration in the example embodiment shown in FIG. 3.

[0044] In the two example embodiments according to FIGS. 3 and 4, a holding fixture can also be provided, which, for example, is bolted onto the transmission housing 26 or cast into the transmission housing 26, wherein shaft bearings are accommodated in the holding fixture, in order to establish a maximum spacing distance of the shaft bearings and, thereby, of the transmission shafts, i.e., of the input shaft and the output shaft of the gearwheel arrangement 16. As a result, a movement apart from each other or a drifting apart of the gearwheels of the gearwheel arrangement 16, in particular in the case of a temperature increase during the operation of the drive train 15, can be thwarted. It is understood that the holding fixture can also be mounted in or at the transmission housing 26 in other ways.

[0045] In FIG. 5, two teeth 36 of the outer toothing 32 of an output gearwheel 23 and/or of a pinion 22 of a gearwheel arrangement 16 according to example aspects of the present invention are shown. In this example embodiment, the teeth 36 have a slight addendum modification and have a module of one and fifty-one hundredths millimeter (1.51 mm). The tooth depth, i.e., the distance between the tooth root 38 and the tooth tip 40, is one and a half millimeter (1.5 mm). In this example, spur teeth were selected. This means, a helix angle β (beta) is zero degrees (0°). In this toothing, the teeth extend straight-lined in the axial direction. In the present example, a transverse contact ratio ε.sub.α (epsilon_alpha) is one and a half (1.5) or less. It is understood that other tooth geometries and tooth depths can also be provided, for example, in the range from one millimeter (1.0 mm) to two and a half millimeters (2.5 mm). The gearwheel 23 and/or the pinion 22 therefore have/has a small tooth depth in relation to their/its diameter, in particular for the sector of motor vehicle transmissions.

[0046] Example aspects of the invention were 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.

[0047] 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. A single element or a single unit can carry out the functions of several of the units mentioned in the claims. 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.

[0048] 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

[0049] 10 electric vehicle [0050] 12 driving wheel [0051] 14 drive axle [0052] 15 drive train [0053] 16 gearwheel arrangement [0054] 17 electric vehicle transmission [0055] 18 electric machine [0056] 20 differential [0057] 22 pinion [0058] 23 output gearwheel [0059] 24 gearwheel base [0060] 26 transmission housing [0061] 28 gearwheel outer side [0062] 30 carrier [0063] 32 outer toothing [0064] 34 power transmission shaft [0065] 36 tooth [0066] 38 tooth root [0067] 40 tooth tip