TRANSMISSION WITH A PARKING LOCK OF AN ELECTRICALLY POWERED VEHICLE

Description

Technical field

[0001] The invention relates to a transmission with a parking lock of an electrically driven vehicle, wherein the parking lock comprises a parking lock gear to which a pawl is assigned and which is received on a shaft. State of the art

[0002] DE 10 2011 016 584 A1 discloses a ratchet wheel that is connected in a rotationally fixed manner to an axle section. The ratchet wheel includes an axle section designed as a torsion damper, which extends at least on one side from a plane spanned by the ratchet wheel, which at least partially forms a rotational axis of the ratchet wheel. A region that is rotatable relative to the shaft is formed between the ratchet wheel and the connecting section. This region has a longitudinal extent that is, in particular, greater than the longitudinal extent of the connecting section by a factor of more than 1.5. A shaft is designed, at least partially, as a hollow shaft that essentially completely accommodates said section.

[0003] DE 10 2007 062 349 A1 discloses a parking lock device in a transmission, wherein the parking lock gear has teeth on its radially outer circumference. This interacts with a parking lock pawl, which can be brought into engagement with the external toothing of the parking lock gear. The parking lock gear is designed as a spoked gear. This makes it a torsionally flexible component. The parking lock gear comprises an inner ring, which is connected in a rotationally fixed manner to a transmission shaft, and a stiffer outer ring, which is provided with external toothing. The outer ring and the inner ring are connected to one another via spokes, wherein the spokes are made of a flexible material.

[0004] DE 10 2009 030 005 A1 discloses a locking mechanism, in particular a parking lock for a transmission shaft of a motor vehicle. The ratchet wheel comprises a plurality of ratchet teeth and recesses arranged between the ratchet teeth. The ratchet wheel has damping elements that serve to dampen the forces acting on the ratchet teeth when the locking mechanism is actuated. The damping elements are arranged in particular in the U-shaped recesses between the ratchet teeth.

[0005] DE 10 2019 217 973 A1 discloses a parking lock for a vehicle. The parking lock comprises a parking lock gear with a pawl associated therewith. The pawl is actuated via a cam gear mounted on a shaft of an actuator by means of a torsion spring element.

[0006] DE 10 2019 209 470 A1 discloses a transmission with a parking lock of an electrically powered vehicle. The parking lock comprises a parking lock gear, which is associated with a pawl and is mounted on a shaft. The parking lock gear is mounted at its seat on the shaft via a damping element, which, in conjunction with a disc spring element acting in the axial direction of the shaft, acts as a torsional damper.

[0007] DE 10 2019 205 608 A1 discloses a parking lock for an electric machine. The parking lock comprises a parking lock gear, which is associated with a pawl and is mounted on a shaft. The parking lock gear has a toothing on its inner circumference for a positive connection to the shaft.

[0008] DE 10 2019 205 602 A1 discloses a parking lock device for an electric machine. The parking lock device comprises a parking lock gear, which is associated with a pawl and is mounted on a shaft. The parking lock gear is provided with helical gearing on its end face, which engages with a corresponding helical gearing on the end face of a second shaft arranged coaxially with the first shaft. The parking lock gear is supported axially on the first shaft via a spring element.

[0009] In some of the state-of-the-art solutions for parking locks, torsional flexibility is achieved by, for example, mounting a rotor shaft and a torsion shaft one inside the other and bonding them together on one side. This means that a considerably larger mass must be set in rotation, which naturally requires greater forces. Furthermore, the torsional stiffness or torsional flexibility can only be adjusted to a limited extent. With regard to variance when installing in different installation positions, care must be taken to ensure that differently configured rotor shafts with a different bearing arrangement are installed. This naturally means considerably more effort in terms of development, design, production, assembly and logistics. Description of the invention

[0010] According to the invention, a transmission with a parking lock of an electrically driven vehicle is proposed, wherein the parking lock comprises a parking lock gear, to which a pawl is assigned and which is received on a shaft, wherein the parking lock gear comprises a torsion spring integrated at its seat on the shaft. According to the invention, the torsion spring is designed as a torsion sleeve between the parking lock gear and the shaft, wherein the torsion sleeve has a slot running in its longitudinal direction. The torsional flexibility of the torsion sleeve can advantageously be adjusted by the number of slots, the slot length of the slots in

[0011] Longitudinally, adjust the slot width of the slots and the distances of the slots from the end faces of the torsion sleeve.

[0012] This solution allows for a very compact unit between the parking lock gear and a shaft, which is particularly characterized by its circumferential torsional flexibility. This prevents the resulting shock loads from being directly coupled to an electrical machine when the pawl abruptly engages the outer circumference of the parking lock gear. Consequently, the resulting mechanical load peaks are significantly reduced, as they are dampened. This allows for more efficient dimensioning of the mechanical components, as lower maximum forces need to be considered.

[0013] There is a force flow from the parking lock gear via the torsion spring designed as a torsion sleeve directly into the shaft. In a further advantageous embodiment of the solution proposed according to the invention, the torsion spring designed as a torsion sleeve is supported on the one hand by a jacket surface of the shaft and on the other hand by a bushing serving as a plain bearing on the shaft.

[0014] In the solution proposed by the invention, specifically due to the design of the torsion sleeve, the shaft can rotate relative to the parking lock gear when force is applied to it. This dampens mechanical load peaks.

[0015] The torsion spring forms a spring-damper system with the shaft. While the spring component slows down the jerky movement, vibrations in the spring component are prevented from building up through damping caused by friction between the two components, the torsion spring and the shaft.

[0016] In one possible embodiment, the parking lock gear is joined to the torsion spring designed as a torsion sleeve at a first joint and the torsion spring designed as a torsion sleeve is joined to the shaft in a force-fitting or material-fitting manner at the second joint.

[0017] The above-mentioned design variant results in a force flow through the parking lock gear, torsion sleeve via the first and second joints directly into the shaft.

[0018] The shaft can be designed as a hollow shaft, in particular as a shaft formed by high-pressure internal forming.

[0019] In an advantageous design of the parking lock, the wall thickness of the torsion spring designed as a torsion sleeve is less than the wall thickness of the shaft. Advantages of the invention

[0020] In the solution proposed according to the invention, a torsion spring in the form of a torsion sleeve is implemented at the seat of the parking lock gear on a shaft. The torsion sleeve, which is relatively short in the axial direction, is a cost-effective and space-saving component that features radial guidance and is characterized by a low installation weight. The solution proposed according to the invention makes it possible to prevent the transmission of sudden mechanical load peaks in the transmission, for example, in the drive train of an electric machine.

[0021] With the solution proposed by the invention, the torsional flexibility and thus the torsional stiffness can also be influenced by the wall thickness differences between the torsion spring on the one hand and the shaft on the other. The wall thickness of the torsion spring, which is designed as a torsion sleeve, is always smaller than the wall thickness of the shaft supporting the torsion spring.

[0022] Furthermore, there is the possibility of using identical parts with regard to a variety of e-axle modules in electrified drive trains for electric vehicles. Short description of the drawings

[0023] Embodiments of the invention are explained in more detail with reference to the drawings and the following description.

[0024] They show: Figure 1 shows a combination of a parking lock and a transmission, not according to the invention, which serves only as an explanation, in which a parking lock gear is arranged on a sleeve-shaped support by means of a torsion spring designed as a meander sleeve, Figure 2 shows a representation of the force flow that occurs in the parking lock according to Figure 1, Figure 3 is a perspective view of a torsion spring designed as a meander sleeve, which is received on a sleeve-shaped support and does not fall within the scope of protection of claim 1, Figure 4 is an alternating arrangement of meander sleeves and sleeve-shaped supports arranged between them, such an arrangement not falling within the scope of protection of claim 1, Figure 5 is an embodiment variant of a transmission according to the invention with a parking lock, wherein the parking lock gear is received on a torsion sleeve, which in turn is supported by a bush serving as a plain bearing and on the other hand by the casing of a shaft, and Figure 6 is a perspective view of the torsion spring designed as a torsion sleeve on Figure 5 with slots extending in the axial direction. Embodiments of the invention

[0025] In the following description, identical or similar elements are designated by the same reference numerals, whereby a repeated description of these elements is omitted in individual cases. Figures 1 to 4 represent objects which do not fall within the scope of protection of claim 1 and which Figures 5 and 6 provide the

[0026] The subject matter of the invention is only shown schematically.

[0027] Figure 1 A parking lock 34 can be removed. In Figure 1An electrical machine 10 is schematically indicated, which comprises a stationary stator 14 and a rotor 12 received on a shaft 16. The shaft 16 has a cavity 20 and is designed symmetrically to its axis of symmetry 18. The shaft 16 is designed as a hollow shaft, wherein the cavity 20 can be manufactured by machining; alternatively, it is possible to manufacture the shaft 16 by means of high-pressure internal forming, i.e., to produce it in a non-machining manner.

[0028] Figure 1 shows further that a toothed section 26 is formed on the shaft 16, which meshes with the toothing of a gear wheel 24 of a gear 22, shown only schematically. The gear 22 can be designed with one or more stages, which, however, is of secondary importance in the above context. From the illustration according to Figure 1It is further apparent that the shaft 16 is mounted in a housing (not shown in detail here) by means of a first bearing 28, a second bearing 30, and a third bearing 32. The bearings 28, 30, 32 are, for example, rolling bearings, such as roller and cylindrical roller bearings, tapered roller bearings, or the like.

[0029] Parking barrier 34, which is in Figure 1 is indicated schematically, comprises, in addition to a parking lock gear 40, a pawl 44 associated with its external toothing 42. The pawl 44, in turn, is movable about a pivot axis 46. The parking lock gear 40 is mounted in its seat 41 on a sleeve-shaped support 48 by means of a torsion spring 35.

[0030] In the Figure 1 the torsion spring 35 is designed as a meander sleeve 36 and comprises at least one meander-shaped web 92, as shown in the perspective top view of the torsion spring 35 according to Figure 3 shown.

[0031] Figure 2 shows the course of a force flow 56 through the arrangement of parking lock gear 40, torsion spring 35, sleeve-shaped carrier 48 into the shaft 16. In the illustration according to Figure 2 the sleeve-shaped carrier 48 and the shaft 16 are one component.

[0032] The force flow 56 runs, for example starting from the pawl 44 according to Figure 1 blocked parking lock gear 40 via a first joint 50 into the torsion spring 35, here designed as a meander sleeve 36 or meander tube 36. Via a second joint 52, the force flow 56 runs either directly into the shaft 16 or in a sleeve-shaped carrier 48 mounted thereon in a rotationally fixed manner, as shown in Figure 1 From the sectional view according to Figure 2 It also follows that a multi-spline profile 66 is provided on the shaft 16, which is symmetrical to its axis of symmetry 18.

[0033] Figure 3shows a perspective view of the torsion spring 35, here designed as a meander sleeve 36 or meander tube 36. From the perspective representation according to Figure 3 It can be seen that the torsion spring 35 is characterized by at least one meandering web 92. Between the sides of the webs, in this essentially sleeve-shaped component, there remain free spaces 62 into which the meandering webs 92 deflect under torsional stress and in this way convert mechanical energy into deformation energy, i.e., have a damping effect. The parking lock gear 40 is provided on its outer circumference with external teeth 42, which essentially consist of an alternating sequence of teeth 58 and tooth gaps 60. In the area of ​​its seat 41, the parking lock gear 40 has the aforementioned torsion spring 35 designed as a meandering sleeve 36.

[0034] The information related to Figure 2The joints 50 and 52 mentioned are designed in particular as material-locking joints, ie as welds, so that the force flow 56 in the Figure 2 can be guided in the manner described.

[0035] Out of Figure 3 It can be seen that a wall thickness 86 of a sleeve-shaped support 48 or the wall thickness 84 of a shaft 16 is larger than a wall thickness 82 of the torsion spring 35, designed here as a meander tube 36 or meander sleeve 36.

[0036] Figure 4shows a parking lock 34, in which an alternating arrangement 64 of sleeve-shaped supports 48 on the one hand and meandering sleeves 36 on the other hand is shown. In the parking lock 34 proposed here, the pawl 44 engages the external toothing 42 of the parking lock gear 40, so that the shaft 16 comes to an immediate standstill. In order to dampen the forces occurring on the shaft 16 and thus on the electric machine 10, a torsionally soft mounting of the parking lock gear 40 is realized by the torsion spring 35, designed here as a meandering sleeve 36 or meandering tube 36. This torsion softness is achieved via the at least one meandering web 92 according to Figure 3achieved. When force is applied, the at least one meander-shaped web 92 of the meander sleeve 36 or the meander tube 36 is displaced in the circumferential direction, so that the support-shaped sleeve 48 and the parking lock gear 40 can rotate relative to one another. The pivot point is the central axis, i.e. the axis of symmetry 18 of the shaft 16. The parking lock 34 comprises a spring and a damping element. Any possible oscillation of the spring element can be dampened via the damping element. In the present solution, the torsion spring 35, designed as a meander sleeve 36 or meander tube 36, acts as a spring, while the damping between this and the sleeve-shaped support 48 is generated by the friction between the two essentially tubular or sleeve-shaped components.

[0037] Figure 5shows an embodiment of the combination of transmission and parking lock 34 proposed according to the invention. Figure 5 the shaft 16 is designed as a hollow shaft with a cavity 20, formed by means of high-pressure internal forming, wherein the shaft 16 is designed symmetrically to the axis of symmetry 18. The shaft 16 according to the illustration in Figure 5 is also mounted in the first bearing 28, the second bearing 30 and the third bearing 32 and has a gear wheel 24 mounted on its circumference in a rotationally fixed manner as well as the rotor 12 of the electrical machine 10, not shown in detail here.

[0038] How Figure 5can also be removed, a torsion spring 35, designed as a torsion sleeve 38, is installed on the shaft 16. The torsion sleeve 38 is inserted coaxially to the shaft 16. The torsion sleeve 38 is also supported by a bushing 70, which serves as a plain bearing. The bushing 70 has an end face 72. The torsion spring 35, designed as a torsion sleeve 38, is joined on both sides with a material fit. The first joint 50 is located between the parking lock gear 40 and the torsion sleeve 38; the second joint 52 is located between an end face of the torsion sleeve 38 and a shoulder in the casing of the shaft 16. Optionally, the torsion sleeve 38 can also be pressed or shrunk onto the shaft 16; the same applies to the parking lock gear 40 of the parking lock 34.

[0039] The torsion sleeve 38 has a lower resistance and area moment of inertia compared to those of the shaft 16, which leads to a higher torsion. This is achieved by a smaller wall thickness 82 of the torsion spring 35, designed as a torsion sleeve 38, compared to the wall thickness 84 of the shaft 16. While the sleeve-shaped carrier 48 according to Figure 1 is completely supported by the shaft 16, the torsion spring 35 designed as a torsion sleeve 38 is as shown in Figure 5 supported on the one hand by the outer surface of the shaft 16 and on the other hand by the bushing 70 serving as a plain bearing.

[0040] From the representation according to Figure 6 , which refers to the design according to Figure 5, it follows that the torsion sleeve 38 can be provided with slots 74. This allows the torsional flexibility or torsional stiffness of the torsion sleeve 38 serving as the torsion spring 35 to be adjusted in a defined manner. The torsional flexibility or torsional stiffness of the Figure 6 The torsion sleeve 38 shown in perspective can be influenced by a slot length 78 of the slot 74 in the longitudinal direction 76 as well as by a slot width 80 in which the slots 74 are made in the circumference of the torsion sleeve 38. The wall thickness 82 of the torsion sleeve 38 is less than the already mentioned wall thickness 86 of the sleeve-shaped support 48 according to Figure 1 or the wall thickness 84 of the shaft 16 as shown in Figure 5. Furthermore, the torsional flexibility or torsional stiffness of the torsion sleeve 38 can also be preset by selecting a distance 90 between the respective end faces 88 of the torsion sleeve 38 and the ends of the slots 74 extending in the longitudinal direction 76, as well as by their number.

[0041] The invention is not limited to the Figures 5 and 6 The invention is not limited to the embodiment described and the aspects highlighted therein. Rather, numerous modifications are possible within the scope specified by the claims.

Claims

1. Transmission (22) with a parking lock (34) of an electrically driven vehicle, wherein the parking lock (34) comprises a parking lock wheel (40), to which a locking pawl (44) is assigned and which is mounted on a shaft (16), wherein the parking lock wheel (40) comprises a torsion spring (35) integrated on its seat (41) on the shaft (16), characterized in that the torsion spring (35) is designed as a torsion sleeve (38) between the parking lock wheel (40) and the shaft (16), wherein the torsion sleeve (38) has a slot pattern (74) which extends in its longitudinal direction (76).

2. Transmission (22) with a parking lock (34) according to Claim 1, characterized in that the torsion spring (35) formed as a torsion sleeve (38) is supported on the shaft (16) firstly by a shell surface of the shaft (16) and secondly by a bush (70) serving as a plain bearing.

3. Transmission (22) with a parking lock (34) according to Claims 1 or 2, characterized in that the torsion sleeve (38) is designed such that, when force is applied to the parking lock wheel (40), the shaft (16) can be rotated relative to the parking lock wheel (40).

4. Transmission (22) with a parking lock (34) according to Claim 1 or 2, characterized in that the parking lock wheel (40) with the torsion spring (35) formed as a torsion sleeve (38) is joined to the shaft (16) in a force-fit or integrally joined connection at a first joining point (50) and the torsion spring (35) formed as a torsion sleeve (38) is joined to the shaft (16) in a force-fit or material-fit connection at a second joining point (52).

5. Transmission (22) with a parking lock (34) according to Claims 1 to 4, characterized in that the shaft (16) is designed as a hollow shaft, in particular as a shaft reshaped by high-pressure internal reshaping.

6. Transmission (22) with a parking lock (34) according to Claims 1 to 5, characterized in that a wall thickness (82) of the torsion spring (35) formed as a torsion sleeve (38) is less than a wall thickness (84) of the shaft (16).