Transmission apparatus

Abstract

The invention relates to a transmission apparatus (2) comprising a transmission arrangement (6) that comprises at least two transmission shafts (9, 10, 12), gears (14, 16, 18, 20) operationally connecting the transmission shafts (9, 10, 12) and a transmission housing (22) that accommodates the transmission shafts (9, 10, 12) and gears (14, 16, 18, 20), wherein the transmission housing (22) comprises an opening (32) that is adapted to provide access to one of the transmission shafts (9, 10, 12). The transmission apparatus (2) further comprises a park lock arrangement (34), wherein the park lock arrangement (34) comprises an auxiliary shaft (36), a park lock device (38) arranged to lock the auxiliary shaft (36) for achieving a park lock function, and a park lock housing (40) that supports the auxiliary shaft (36). The park lock housing (40) is adapted to be removably connected to the transmission housing (22) for closing the transmission housing opening (32). Further, said one of the transmission shafts (9, 10, 12) and the auxiliary shaft (36) are adapted for being rotationally rigidly connected to each other via the transmission housing opening (32). Further, the park lock housing (40) and the auxiliary shaft (36) are adapted to be movable in unison for achieving a connection and / or disconnection of the park lock housing (40) and the transmission housing (22).

Description

[0001]Transmission apparatus TECHNICAL FIELD The invention relates to a transmission apparatus. Especially, the invention relates to a transmission apparatus for a vehicle drive system and especially for a vehicle electric drive system. Although many different electric powertrain architectures exist, the most common one is a purely electric axle drive (e-drive) that consists of the main components power electronics unit, electric machine (EM) and transmission, also called gearbox or reducer. A parking lock might be required due to considerations regarding the vehicle’s safety: in redundancy with the vehicle’s parking brake, the parking lock prevents vehicle movement while parking by mechanically locking the drivetrain. This function is typically achieved by mounting a parking lock wheel to a shaft inside the transmission and a mechanically or electrically actuated pawl, which connects the parking lock wheel to the transmission housing when the parking lock is engaged. That way, an interlocking connection between the transmission housing and the shaft is made and any rotation of the drivetrain is prevented. When the vehicle comes into a halt, the driver operates a parking actuator to a parking state, whereby the drive wheels of the vehicle are locked and the vehicle is reliably maintained in the halted state. In order to integrate the parking lock into the e-drive, various mounting positions inside the e-drive are eligible. The designs of shafts, gear wheels and / or bearings of the transmission are affected by the parking lock integration. Normally, the parking lock is arranged on the input shaft or on an intermediate shaft in the transmission. There is a desire in some applications to provide the parking lock as an option to a transmission base unit. More specifically, it is desired that the parking lock device is mounted with a minimum change of the shape and size of an existing transmission. Especially, it is desired to integrate the parking lock while still the overall transmission having a compact size and a short length in the axial direction of the transmission. Further, if the basic shape and size of the transmission are maintained unchanged, the basic transmission can be used in common for manufacturing a variety of kinds of vehicles irrespective of whether the parking lock device is provided, making it possible to decrease the cost for the production or assembling. PRIOR ART EP 2003031 discloses an automatic transmission, wherein a parking lock device is arranged at a rear portion of the automatic transmission, and works to lock an output shaft of the automatic transmission and the drive wheels by fixing a parking gear to the output shaft or to a rotary shaft coupled to the output shaft and by bringing a parking pawl attached to the housing of the automatic transmission into mesh with the parking gear. More specifically, a first coupling member is fitted to a rear end portion of the output shaft of the transmission, a second coupling member having an extended shaft portion formed in the same shape as the rear end portion of the output shaft of the transmission is integrally coupled thereto, and a continuously indented portion is formed along the outer circumferential portion of either the first coupling member or the second coupling member so as to use either one of them as a parking gear. In a basic transmission design (without the parking lock device), the transmission housing is formed in two housing portions with a split plane perpendicular to the axial direction of the transmission. The housing portions are joined by means of a bolt connection. What requires the change when the parking lock device is to be added is that a housing rear end portion is removed and an auxiliary housing portion is connected to a front portion of the housing. The auxiliary housing portion being extended in the axial direction relative to the original rear housing portion in order to accommodate the first coupling member, the second coupling member and the parking lock device. SUMMARY A first object of the invention is to achieve a transmission apparatus that creates conditions for a modular parking lock and provides for a facilitated servicing of the parking lock. The object is achieved by a transmission apparatus according to claim 1. Thus, it is achieved by a transmission apparatus comprising - a transmission arrangement that comprises at least two transmission shafts, gears operationally connecting the transmission shafts and a transmission housing that accommodates the transmission shafts and gears, wherein the transmission housing comprises an opening that is adapted to provide access to one of the transmission shafts, - a park lock arrangement, wherein the park lock arrangement comprises an auxiliary shaft, a park lock device arranged to lock the auxiliary shaft for achieving a park lock function, and a park lock housing that supports the auxiliary shaft, - wherein the park lock housing is adapted to be removably connected to the transmission housing for closing the transmission housing opening, and - wherein said one of the transmission shafts and the auxiliary shaft are rotationally rigidly connected to each other and extending through the transmission housing opening, - wherein the park lock housing and the auxiliary shaft are adapted to be movable in unison for achieving a connection and / or disconnection of the park lock housing and the transmission housing. It provides for a modular parking lock concept in that the transmission housing opening may be covered by a plain lid in production instead of the park lock housing (and the auxiliary shaft and possibly the park lock device) in case there is no desire to provide a parking lock function. Accordingly, the transmission apparatus may be arranged with a basic design irrespective of whether the parking lock device is integrated or not. Thus, the basic transmission apparatus can be used in common for manufacturing a variety of kinds of vehicles irrespective of whether the parking lock device is required or not. The feature that “said one of the transmission shafts and the auxiliary shaft are rotationally rigidly connected to each other” means that the transmission shaft and the auxiliary shaft simultaneously move at the same rotational speed. Further, the feature that “said one of the transmission shafts and the auxiliary shaft extending through the transmission housing opening” means that at least one portion of the auxiliary shaft extends through the transmission housing opening in a connected state. Further, thanks to the design that the park lock housing and the auxiliary shaft are adapted to be movable in unison creates conditions for a facilitated access to the parking lock device. The feature that “the park lock housing and the auxiliary shaft are adapted to be movable in unison” is achieved by means of the auxiliary shaft being supported by the park lock housing. Accordingly, the auxiliary shaft is connected to the park lock housing in a way that they may be moved in unison. In other words, the auxiliary shaft is connected to the park lock housing so that it is non-movable relative to the park lock housing in its axial direction. Thus, during assembly and / or disassembly, an axial movement of the park lock housing relative to the transmission housing would automatically move the auxiliary shaft into engagement with, or out of engagement with said one of the transmission shafts. More specifically, the auxiliary shaft is rotationally supported by the park lock housing. More specifically, one end of the auxiliary shaft may be journalled in the park lock housing by means of a bearing. Further, integration of the parking lock device in this way causes a limited increase in an overall length of the transmission apparatus. A vehicle has only a limited space for arranging the transmission apparatus. Therefore, the parking lock device must be constituted as compactly as possible and it is, particularly, desired that the parking lock device has a reduced size in the axial direction of the transmission apparatus. According to one embodiment example, a first end of the auxiliary shaft is journalled in the park lock housing by means of a bearing. The bearing may be formed by a ball bearing. Further, the ball bearing comprises two radially spaced rings (or “races”) and a plurality of circumferentially spaced balls arranged between the two bearing rings. An outer bearing ring may be press fitted in a correspondingly shaped recess in the park lock housing. According to an alternative, a bearing retainer plate may be arranged to secure the outer bearing ring to the park lock housing. Further, an inner bearing ring may be press fitted around the auxiliary shaft. It creates further conditions for the park lock housing and the auxiliary shaft being adapted to be movable in unison. According to one further embodiment example, the park lock housing comprises a wall that forms a closed end in a direction of a rotational axis of the auxiliary shaft distant from said one of the transmission shafts. In other words, the closed end is arranged at the end of the auxiliary shaft that is furthest away from the transmission housing. Accordingly, the park lock housing does not comprise a through-opening for receipt of the auxiliary shaft. In other words, the auxiliary shaft is not extending through the park lock housing to an opposite side of the park lock housing relative to the park lock device. According to one further embodiment example, the first end of the auxiliary shaft is journalled in the wall that forms the closed end of the park lock housing. According to one further embodiment example, the wall that forms the closed end of the park lock housing is adapted to transfer loads during operation. In other words, the wall that forms the closed end of the park lock housing has a certain rigidity for transferring loads during operation. According to one example, the wall that forms the closed end of the park lock housing has a structure (material and / or thickness) substantially commensurate with a structure of the transmission housing. According to one further embodiment example, a second end of the auxiliary shaft opposite the first end of the auxiliary shaft and a first end of said one of the transmission shafts are provided with complimentary shaped engagement means for providing a rotationally fixed engagement. It creates conditions for operationally coupling the park lock device to said one of the transmission shafts. According to one further embodiment example, the first end of said one of the transmission shafts and the second end of the auxiliary shaft are provided with complimentary shaped engagement means in the form of splines. It creates conditions for a facilitated coupling and decoupling of the auxiliary shaft to said one of the transmission shafts by means of an axial movement of the auxiliary shaft relative to said one of the transmission shafts. In other words, the park lock arrangement may be docked to its operational state by a relative axial movement by means of engagement of the splines. According to one further embodiment example, the second end of the auxiliary shaft projects out from the park lock housing via an opening opposite the closed end. It createsfurther conditions for a facilitated assembly in that the second end of the auxiliary shaftmay be viewed by an operator (service technician) as it engages the rotational engagement means of the first end of said one of the transmission shafts. According to one further embodiment example, the transmission housing opening is arranged and sized to provide axial access to the first end of said one of the transmission shafts. It creates further conditions for a facilitated assembly. According to one example, the first end of said one of the transmission shafts is exposed via the transmission housing opening. According to one further example, the first end of said one of the transmission shafts is adjacent the transmission housing opening. According to one further example, said one of the transmission shafts is arranged in the transmission housing so that a rotational axis of the transmission shaft has a direction through the transmission housing opening. According to one further embodiment example, the transmission arrangement and the park lock arrangement are adapted for achieving the rotationally fixed engagement of the complimentary shaped engagement means when the park lock housing and the transmission housing are in a connected state and disengagement of the complimentary shaped engagement means when the park lock housing and the transmission housing are in a disconnected state and removed from each other. In other words, releasing the park lock housing and the transmission housing and withdrawing the park lock housing from the transmission housing simultaneously creates disassembly of the auxiliary shaft from said one of the transmission shafts and removal of the auxiliary shaft from said one of the transmission shafts. On the other hand, properly mating the park lock housing to the transmission housing creates conditions for simultaneously operationally engaging the auxiliary shaft to said one of the transmission shafts. According to one further embodiment example, the park lock device comprises a park lock wheel rotationally rigidly attached to the auxiliary shaft, wherein the park lock wheel comprises a plurality of circumferentially spaced recesses in its radially outer circumference, wherein the park lock device further comprises a park lock pawl, which is arranged to engage with one of the recesses so that the park lock wheel is blocked from rotation when the park lock device is engaged. According to one further embodiment example, the park lock pawl is mounted in the park lock housing. Accordingly, the park lock pawl may be moved in unison with the park lock housing as it is moved relative to the transmission housing to and from its operational state. According to one further embodiment example, the park lock housing accommodates the park lock device. Accordingly, the park lock device may be moved in unison with the park lock housing as it is moved relative to the transmission housing to and from its operational state. According to one further embodiment example, the park lock arrangement is adapted to be movable as one single unit for achieving the removable connection of the park lock housing and the transmission housing. According to one further embodiment example, the transmission arrangement comprises an output shaft that extends through a further opening of the transmission housing, that is separate from said transmission housing opening. Accordingly, the parklock arrangement may be disassembled from the transmission housing without removing the output shaft. According to one further embodiment example, said first-mentioned transmission housing opening is displaced in a direction transverse to a rotational axis of the output shaft. In other words, said first-mentioned transmission housing opening is spaced from the rotational axis of the output shaft in a direction transverse to the rotational axis of the output shaft. Accordingly, said first-mentioned transmission housing opening is spaced from the rotational axis of the output shaft in a direction perpendicular to the rotational axis of the output shaft. In other words, the first-mentioned transmission housing opening is arranged so that the rotational axis of the output shaft does not coincide with the first- mentioned transmission housing opening. According to one further embodiment example, the park lock housing comprises a connection surface, wherein the transmission housing comprises a connection surface circumscribing the transmission housing opening, and wherein the connection surfaces are adapted for mating in the connected state of the park lock housing and the transmission housing. According to one further embodiment example, each one of the connection surfaces comprises a set of spaced holes for receiving bolts, wherein the park lock housing and the transmission housing are arranged in a way that the holes align in a connected state of the park lock housing and the transmission housing for achieving a bolt connection between the park lock housing and the transmission housing. In other words, the park lock arrangement provides for a bolt-on solution. According to one further embodiment example, the transmission arrangement comprises an input shaft, an output shaft and an intermediate shaft that are connected by means of gears, wherein said one of the transmission shafts is formed by the intermediate shaft. According to one further embodiment example, the transmission housing comprises two housing parts and an internal chamber of the transmission housing defined by the connection surfaces has a first circumferential size at a split plane of the two housing parts, wherein the transmission housing opening has a second circumferential size that is significantly smaller than the first circumferential size. According to one further embodiment example, a seal is arranged between said one of the transmission shafts and the transmission housing so that an internal chamber in the transmission housing may be fluidly separate from an internal chamber in the park lock housing in the connected state of the park lock housing and the transmission housing. Further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples. In the drawings: Fig. 1 is a view in cross section of a transmission apparatus according to a first embodiment that comprises a park lock arrangement according to a first embodiment, Fig. 2 is an enlarged view of a portion of the transmission apparatus according to fig.1 showing the park lock arrangement in more detail, Fig.3 is a perspective view of the park lock arrangement according to fig 2, Fig. 4 is an enlarged view of a portion of the transmission apparatus according to fig.2, wherein the park lock arrangement is replaced by a lid, Fig.5 is a perspective view of the lid according to fig 4, Fig.6 shows a transmission apparatus according to a second embodiment that comprises a park lock arrangement according to a first embodiment, Fig. 7 shows a transmission apparatus according to a third embodiment that comprises a park lock arrangement according to a third embodiment, Fig.8 shows a park lock arrangement according to a fourth embodiment, Fig.9 is a perspective view of the park lock arrangement according to fig 8, Fig. 10a is a schematic view of the transmission apparatus according to a fourth embodiment, wherein the park lock arrangement is coupled to a layshaft by means of internal splines in an end of the layshaft, Fig. 10b is an alternative to fig.10a, wherein the park lock arrangement is coupled to the layshaft by means of external splines on an end of the layshaft, Fig. 11a is a schematic view of a transmission apparatus according to an alternative layout relative to fig. 10a, wherein the park lock arrangement is shown in four different alternative positions coupled to a layshaft and an input shaft by means of internal splines in an end of the shaft, Fig. 11b is an alternative to fig.11a, wherein the park lock arrangement is shown in four different alternative positions coupled to a layshaft and an input shaft by means of external splines on an end of the shaft, Fig.12a is a schematic view of a transmission apparatus according to a further alternative layout relative to fig. 10a, wherein the park lock arrangement is shown in two different alternative positions coupled to a layshaft and an input shaft by means of internal splines in an end of the shaft, and Fig. 12b is an alternative to fig. 12a, wherein the park lock arrangement is shown in two different alternative positions coupled to a layshaft and an input shaft by means of external splines on an end of the shaft. DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS Fig. 1 is a view in cross section of a transmission apparatus 2 according to a first embodiment for a vehicle. The transmission apparatus 2 is formed by an Electrical Drive Unit (EDU). The transmission apparatus 2 comprises a source of motive power in the form of an electrical motor 4. The transmission apparatus 2 further comprises a transmission arrangement 6 comprising a rotor shaft 8 that is operationally connected to the electrical motor 4. The transmission arrangement 6 further comprises an input shaft 9 that is operationally connected to the rotor shaft 8. The transmission arrangement 6 further comprises an output shaft 10 arranged in parallel with the input shaft 9. The transmission arrangement 6 further comprises a differential 11 associated to the output shaft 10 for allowing wheels (not shown) at each end of the output shaft 10 to rotate at different speeds while cornering. The transmission arrangement 6 further comprises an intermediate shaft 12 that is operationally connected to each one of the input shaft 9 and the output shaft 10 by means of engaging gears 14, 16; 18, 20. The gears 14, 16; 18, 20 are fixed to the respective shaft and rotate in mesh at all times to achieve a speed-change gear to thereby reduce the speed. The intermediate shaft may alternatively be called countershaft or layshaft. The transmission arrangement 6 further comprises a transmission housing 22 that accommodates the transmission shafts 9, 10, 12 and the associated gears 14, 16; 18, 20. The transmission housing 22 comprises two housing parts 24, 26. Each housing part 24, 26 defines the transmission housing 22 radially outwards. The transmission housing 22 defines an internal chamber 28. The two housing parts 24, 26 define a split plane 30. Each one of the two housing parts 24, 26 comprises a connection surface 25, 27 extending continuously in a circumferential direction around the transmission housing 22, wherein the connection surfaces 25, 27 are adapted for mating in a connected state of the housing parts 24, 26. More specifically, an interface between the connection surfaces 25, 27 extend perpendicularly relative to an axis of rotation of the input shaft 9. Further, each one of the two housing parts 24, 26 comprises a set of circumferentially spaced holes extending in parallel with the axis of rotation of the input shaft 9 through the connection surfaces 25, 27 for receiving bolts 31, wherein the housing parts 24, 26 are arranged in a way that the holes align in a connected state of the housing parts 24, 26 for achieving a bolt connection between the housing parts 24, 26. In other words, the connection surfaces 25, 27 are arranged at a radial periphery of the transmission housing 22. More specifically, the connection surfaces 25, 27 define an internal chamber 28 with a first circumferential size at the split plane 30. The transmission housing 22 comprises an opening 32 that is adapted to provide access to the intermediate shaft 12. More specifically, the transmission housing opening 32 has a second circumferential size that is significantly smaller than the first circumferential size associated to the split plane 30 of the two housing parts 24, 26. More specifically, the transmission housing opening 32 extends in a flat plane in parallel with the split plane 30 of the two housing parts 24, 26. The park lock housing 40 is adapted to be removably connected to the transmission housing 24 for closing the transmission housing opening 32. More specifically, the park lock housing 40 defines an opening 43 with a shape and size corresponding to the shape and size of the transmission housing opening 32. The transmission housing opening 32 extends in a plane transverse to and more particularly perpendicularly to a rotational axis of one of the transmission shafts 9, 10, 12. Likewise, the park lock housing opening 43 extends in a plane transverse to and more particularly perpendicularly to a rotational axis of the auxiliary shaft 12. The transmission housing opening 32 is arranged so that a rotational axis of the intermediate shafts 12 coincides with the transmission housing opening 32. Likewise, the park lock housing opening 43 is arranged so that a rotational axis of the auxiliary shaft 36 coincides with the park lock housing opening 43. Further, the park lock housing 40 comprises a circumferentially continuous connection surface 54 circumscribing and defining the park lock housing opening 43, wherein the transmission housing 24 comprises a corresponding circumferentially continuous connection surface 56 circumscribing and defining the transmission housing opening 32. The connection surfaces 54, 56 are adapted for mating in the connected state of the park lock housing 40 and the transmission housing 24. The connection surfaces 54, 56 of the housing part 24 and the park lock housing 40 define a split plane 57. More specifically, an interface between the connection surfaces 54, 56 extend perpendicularly relative to an axis of rotation of the intermediate shaft 12. Further, each one of the connection surfaces 54, 56 comprises a set of circumferentially spaced holes for receiving bolts 58, 60, see fig. 2, wherein the park lock housing 40 and the transmission housing 24 are arranged in a way that the holes align in a connected state of the park lock housing 40 and the transmission housing 22 for achieving a bolt connection between the park lock housing 22 and the transmission housing 40. The park lock housing 40 further comprises a wall 41 that forms a closed end in a direction of a rotational axis of the auxiliary shaft 36. More specifically, the wall 41 that forms the closed end of the park lock housing 40 is adapted to transfer loads during operation. The transmission apparatus 2 further comprises a park lock arrangement 34 according to a first embodiment. The park lock arrangement 34 comprises an auxiliary shaft 36, a park lock device 38 arranged to lock the auxiliary shaft for achieving a park lock function, and a park lock housing 40 that supports the auxiliary shaft 36. The auxiliary shaft 36 is formed in a one-piece unit. More specifically, a first end 42 of the auxiliary shaft 36 is journalled in the park lock housing 40 by means of a bearing 44. More specifically, the first end 42 of the auxiliary shaft 36 is journalled in the wall 41 that forms the closed end of the park lock housing 40. The bearing 44 is formed by a ball bearing. Further, the ball bearing 44 comprises two radially spaced rings (or “races”) 46, 48 and a plurality of circumferentially spaced balls 50 arranged between the two bearing rings 46, 48. An outer bearing ring 46 is press fitted in a correspondingly shaped recess 52 in the park lock housing 40. Further,an inner bearing ring 48 is press fitted around the first end 42 of the auxiliary shaft 36.Further, the transmission housing part 24 comprises a housing portion 35 defining the transmission housing part 24 in parallel with an axis of rotation of the intermediate shaft 12, wherein the housing portion 35 defines an opening for receipt of the auxiliary shaft 36. The transmission housing opening has a circular shape with a somewhat larger size relative to an external size of the auxiliary shaft 36. The transmission housing opening and the intermediate shaft 12 are arranged in a coaxial relationship. The intermediate shaft 12 and the auxiliary shaft 36 are adapted for being rotationally rigidly connected to each other in a coaxial relationship. The intermediate shaft 12 and / or the auxiliary shaft 36 are arranged to extend through the transmission housing opening 32 in a rotationally rigidly connected state. More specifically, a second end 62 of the auxiliary shaft 36 opposite the first end 42 of the auxiliary shaft 36 and a first end 64 of the intermediate shaft 12 are provided with complimentary shaped engagement means 66, 68 for providing a rotationally fixed engagement. More specifically, the first end 64 of the intermediate shaft 12 and the second end 42 of the auxiliary shaft 36 are provided with complimentary shaped engagement means in the form of splines 66, 68, see also fig.3. More specifically, the first end 64 of the intermediate shaft 12 has a hollow section provided with internal splines and the second end 42 of the auxiliary shaft 36 is provided with external splines. More specifically, the first end 64 of the intermediate shaft 12 has a circular-cylindrical opening coaxial with an axis of rotation of the intermediate shaft 12, wherein the circular-cylindrical opening is provided with the internal splines. Further, the second end 42 of the auxiliary shaft 36 is provided with splines formed along an outer circumferential portion. Further, the second end 42 of the auxiliary shaft 36 projects out from the park lock housing 40 with regard to the split plane 57 defined by the connection surfaces 54, 56 of the housing part 24 and the park lock housing 40. Further, the transmission housing opening 32 is arranged and sized to provide axial access to the first end 64 of the intermediate shaft 12. Further, the first end 64 of the intermediate shaft 12 is exposed via the transmission housing opening 32. Further, the first end 64 of the intermediate shaft 12 is adjacent the transmission housing opening 32. Further, the intermediate shaft 12 is arranged in the transmission housing 22 so that a rotational axis of the intermediate shaft 12 has a direction through the transmission housing opening 32. The park lock device 38 comprises a park lock wheel 70 (or parking gear) rotationally rigidly attached to the auxiliary shaft 36, wherein the park lock wheel 70 comprises a plurality of circumferentially spaced recesses 72 (see fig. 3) in its radially outer circumference. The park lock device 38 further comprises a park lock pawl 74, which is arranged to engage with one of the recesses 72 so that the park lock wheel 70 is blocked from rotation when the park lock device 38 is engaged. The park lock pawl 74 is mounted in the park lock housing 40. More specifically, the park lock pawl 74 is pivotably arranged around an axis at a first end 76 of the park lock pawl 74, wherein an engagement projection 80 of the park lock pawl 74, adapted for engagement with one of the recesses 72, is provided at a second end 78 of the park lock pawl 74 that is opposite the first end 76. The park lock device 38 further comprises an actuator 82 adapted to push the park lock pawl 74 against the park lock wheel 70 for engagement. In other words, the park lock pawl 74 is brought into mesh with the park lock wheel 70. The park lock housing 40 accommodates the park lock device 38. The output shaft 10 extends through a further opening 13 of the transmission housing 22, that is separate from said transmission housing opening 32. More specifically, said transmission housing opening 32 is displaced in a direction transverse to a rotational axis of the output shaft 10. In other words, said transmission housing opening 32 is spaced from the rotational axis of the output shaft 10 in a direction perpendicular to the rotational axis of the output shaft 10. Fig. 2 is an enlarged view of a portion of the transmission apparatus 2 according to fig.1 showing the park lock arrangement 34 in more detail. The auxiliary shaft 36 comprises an intermediate section 84 between the first end 42 and the second end 62. The intermediate section 84 has a larger diameter than an adjacent section 86 of the first end 42 of the auxiliary shaft 36. More specifically, the auxiliary shaft 36 has a stepwise transition between the intermediate section 84 and the adjacent section 86 of the first end 42. The step on the auxiliary shaft 36 acts as end stop for a press fit of the ball bearing 44. Further, the auxiliary shaft 36 is arranged relative to the ball bearing 44 in a way that the intermediate section 84 is in contact with a first axial surface of the inner bearing ring 48 by means of the stepwise transition. Further, the ball bearing 44 is arranged relative to the park lock housing 40 in a way that a second axial surface of the inner bearing ring 48 opposite the first axial surface is arranged in contact with an inner surface of the park lock housing 40. Fig.3 is a perspective view of the park lock arrangement 34 according to fig 2. The park lock housing 40 and the auxiliary shaft 36 are adapted to be movable in unison for achieving an assembly and / or disassembly of the park lock housing 40 and the transmission housing 22. More specifically, the transmission arrangement 6 and the park lock arrangement 34 are adapted for achieving the rotationally fixed engagement of the complimentary shaped engagement means 66, 68 when the park lock housing 40 and the transmission housing 22 are in a connected state (or assembled state) and disengagement of the complimentary shaped engagement means 66, 68 when the park lock housing 40 and the transmission housing 22 are in a disconnected state (or disassembled state). In other words, the park lock arrangement 34 is adapted to be movable as one single unit for achieving the removable connection of the park lock housing 40 and the transmission housing 22. In other words, the park lock housing 40 is adapted to be removably connected to the transmission housing 22 in a way that the park lock housing opening 43 aligns with the transmission housing opening 32 in the connected state. Fig.4 is an enlarged view of a portion of the transmission apparatus 2 according to fig.2, wherein the park lock arrangement 34 is replaced by a lid 88. The lid 88 is adapted to seal the transmission housing 22 by closing the transmission housing opening 32. Thus, the lid 88 comprises a connection surface 90 that corresponds to the connection surface 54 of the park lock housing 40 for engagement with the connection surface 56 of the transmission housing part 24. Further, the lid 88 is adapted to be rigidly connected to the transmission housing part 24 via the bolts 58, 60. The lid 88 has a generally flat configuration. Fig.5 is a perspective view of the lid 88 according to fig 4. Fig. 6 shows a transmission apparatus 102 according to a second embodiment that comprises a park lock arrangement 134 according to a second embodiment. For ease of presentation, only the main differences in relation to the first embodiment in fig.2 will be described. The transmission apparatus 102 comprises a transmission housing 122 that in turn comprises two housing parts 124, 126. The transmission housing 122 comprises an opening 132 that is adapted to provide access to the intermediate shaft 112. More specifically, the transmission housing part 124 comprises a housing portion 135 that defines a transmission housing opening. The transmission housing opening has a circular shape with a somewhat larger size relative to an external size of the intermediate shaft 112. More specifically, the transmission housing opening and the intermediate shaft 112 are arranged in a coaxial relationship. The transmission apparatus 102 comprises a seal 103 arranged between the housing portion 135 that defines the transmission housing opening and the intermediate shaft 112. Accordingly, an internal chamber 128 in the transmission housing 122 may be fluidly separate from an internal chamber 137 in the park lock housing 140 in the connected state of the park lock housing 140 and the transmission housing 122. The park lock housing 140 has a slightly larger axial extension relative to the park lock housing 40 in the first embodiment. It creates conditions for avoiding oil flowing out of the transmission housing 122. In this case, the park lock arrangement 134 could have its own sump. For servicing this arrangement 134, a park lock oil sump would need to be drained. Fig. 7 shows a transmission apparatus 202 according to a third embodiment that comprises a park lock arrangement 234 according to a third embodiment. For ease of presentation, only the main differences in relation to the first embodiment in fig.2 will be described. The park lock arrangement 234 comprises a ball bearing 244 adapted for journalling the intermediate shaft 212 in the park lock housing 240. The ball bearing 244 comprises two radially spaced rings 246, 248. An inner bearing ring 246 may be press fitted to the auxiliary shaft 236. An outer bearing ring 246 may be loosely fitted in a correspondingly shaped recess 252 in the park lock housing 240. The park lock arrangement 234 comprises a bearing retainer plate 201 that is secured to an inner surface of the park lock housing 240 by means of a bolt connection 203, wherein the bearing retainer plate 201 is adapted to contact a first axial surface of the outer bearing ring 248 for securing the ball bearing 244 in relation to the park lock housing 240. The auxiliary shaft may be assembled by the following consecutive steps: 1) press fit the park lock wheel 270 on the auxiliary shaft 236 till end stop.2) press fit the bearing 244 on the auxiliary shaft 236 till end stop. 3) slide the auxiliary shaft 236 on the park lock housing 240. 4) Position the bearing retainer plate 201 and tight it with bolts to the park lock housing 240. According to this embodiment, oil needs to be drained before opening the park lock housing 240. The auxiliary shaft 236 and the park lock wheel 270 are easily removed when removing the park lock housing 240. Park lock pawl 274 would be supported on the transmission housing. Fig. 8 shows a park lock arrangement 334 according to a fourth embodiment. Fig.9 is a perspective view of the park lock arrangement 334 according to fig 8. For ease of presentation, only the main differences in relation to the second embodiment in fig.6 will be described. The park lock arrangement 334 comprises a first park lock housing part 340 similar to the park lock housing 140 in the second embodiment in fig.6 and a second park lock housing part 341. More specifically, the second park lock housing part 341 has a generally flat extension. The second park lock housing part 341 comprises an opening 332 that is adapted to house the auxiliary shaft 336. More specifically, the second park lock housing part 341 comprises a housing portion 335 defining the transmission housing opening 332. The transmission housing opening 332 has a circular shape with a somewhat larger size relative to an external size of the auxiliary shaft 336. More specifically, the transmission housing opening 332 and the auxiliary shaft 336 are arranged in a coaxial relationship. Further, the park lock arrangement 334 comprises a seal 303 arranged between the housing portion 342 that defines the transmission housing opening 332 and the auxiliary shaft 336. Accordingly, an internal chamber 337 in the park lock housing 340 may be fluidly separate from an internal chamber in the transmission housing in the connected state of the park lock housing 340 and the transmission housing. Further, the first park lock housing part 340 and the second park lock housing part 341 have complimentary shaped circumferentially continuous connection surfaces 343, 345 adapted for mating with each other. Further, the second park lock housing part 341 and the has a further circumferentially continuous connection surface 325 facing in an opposite direction relative to the first-mentioned continuous connection surface 345 adapted for mating with a complimentary shaped circumferentially continuous connection surface of the transmission housing. The second park lock housing part 341 will be arranged between the first park lock housing part 340 and the transmission housing in a sandwiched state when the park lock arrangement 334 is attached to the transmission housing by means of a bolt connection, see bolts 358, 360. The park lock arrangement 334 is closed totally by mean of the second park lock housing part 341 sandwiched between the park lock housing 340 and the transmission housing, this will mean that the park lock arrangement 334 doesn’t need to be drained for servicing. Fig. 10a is a schematic view of the transmission apparatus 402 according to a fourth embodiment. The transmission apparatus 402 comprises an electrical motor 404. The transmission apparatus 402 further comprises a transmission arrangement 406 comprising an input shaft 408 that is operationally connected to the electrical motor 404. The transmission arrangement 406 further comprises an output shaft 410 arranged in parallel with the input shaft 408 in a concentric relationship. The transmission arrangement 406 further comprises a differential 411. The transmission arrangement 406 further comprises an intermediate shaft 412 that is operationally connected to each one of the input shaft 408 and the output shaft 410 by means of engaging gears. The transmission apparatus 402 further comprises a park lock arrangement 434 that comprises an auxiliary shaft 436 (in a similar way as has been described for the previous embodiments). The auxiliary shaft 436 is connected to the intermediate shaft 412 by means of a spline connection 466, 468. More specifically, internal splines 466 are provided in an end of the intermediate shaft 412 and complimentary shaped external splines 468 are provided in an end of the auxiliary shaft 436. Fig. 10b is an alternative to fig. 10a and discloses a transmission apparatus 502 according to a fourth embodiment. For ease of presentation, only the main differences in relation to the second embodiment in fig.6 will be described. The transmission apparatus 502 comprises a transmission arrangement 506 and a park lock arrangement 534. The transmission arrangement 506 comprises an intermediate shaft 512. The park lock arrangement 534 that comprises an auxiliary shaft 536. The auxiliary shaft 536 is connected to the intermediate shaft 512 by means of a spline connection 566, 568. More specifically, external splines 566 are provided in an end of the intermediate shaft 512 and complimentary shaped external splines 568 are provided in an end of the auxiliary shaft 536. Fig. 11a is a schematic view of a transmission apparatus 602 according to an alternative layout relative to fig. 10a. The transmission apparatus 602 comprises an electrical motor 604. The transmission apparatus 602 further comprises a transmission arrangement 606 comprising an input shaft 608 and an output shaft 610 arranged in parallel with the input shaft 608 in a non-concentric relationship. The transmission arrangement 606 further comprises an intermediate shaft 612 that is operationally connected to each one of the input shaft 608 and the output shaft 610 by means of engaging gears. The transmission apparatus 602 further comprises a park lock arrangement 634 that comprises an auxiliary shaft 636 (in a similar way as has been described for the previous embodiments). The auxiliary shaft 636 is connected to the input shaft 608 by means of a spline connection 666, 668. More specifically, internal splines 666 are provided in a first end of the input shaft 608 and complimentary shaped external splines 668 are provided in an end of the auxiliary shaft 636. More specifically, the park lock arrangement 634, 634’, 634’’, 634’’’ is shown in four different alternative positions in fig. 11a. According to a first alternative, the park lock arrangement 634’ is arranged on an opposite side of the electrical motor 604 relative to the park lock arrangement 634 and connected to a second end of the input shaft 608 by means of a similar spline connection (as described above). According to a second alternative, the park lock arrangement 634’’ is operatively connected to a first end of the intermediate shaft 612 by means of a similar spline connection (as described above). According to a third alternative, the park lock arrangement 634’’’ is operatively connected to a second end of the intermediate shaft 612 by means of a similar spline connection (as described above). Fig. 11b is a schematic view of a transmission apparatus 702 according to an alternative layout relative to an alternative to fig.11a, wherein the park lock arrangement 734, 734’, 734’’, 734’’’ is shown in the same four different alternative positions as described above with regard to fig. 11a. The transmission apparatus 702 differs from the transmission apparatus 602 according to fig. 11a in that the spline connection 766, 768 comprises internal splines 766 are provided in a first end of the shaft 708 and complimentary shaped external splines 768 are provided in an end of the auxiliary shaft 736. Fig. 12a is a schematic view of a transmission apparatus 802 according to a further alternative layout relative to fig. 10a. The transmission apparatus 802 comprises an electrical motor 804. The transmission apparatus 802 further comprises a transmission arrangement 806 comprising an input shaft 808 that is operationally connected to the electrical motor 804. The transmission arrangement 806 further comprises an output shaft 810 arranged in parallel with the input shaft 808 in a non-concentric relationship. The transmission arrangement 406 further comprises a differential 811. The transmission arrangement 806 further comprises an intermediate shaft 812. The transmission arrangement 806 further comprises a planetary gear 814 that is operationally connected between the input shaft 808 and the intermediate shaft 812. The input shaft 808 and the intermediate shaft 812 are arranged in a coaxial relationship. The intermediate shaft 812 is further operationally connected to the output shaft 810 by means of engaging gears. The transmission apparatus 802 further comprises a park lock arrangement 834 that comprises an auxiliary shaft 836 (in a similar way as has been described for the previous embodiments). The auxiliary shaft 836 is connected to the intermediate shaft 812 by means of a spline connection 866, 868. More specifically, internal splines 866 are provided in an end of the intermediate shaft 812 that is opposite the planetary gear 814 and complimentary shaped external splines 868 are provided in an end of the auxiliary shaft 836. The park lock arrangement 834’ is also shown in an alternative position in fig.12a. More specifically, the park lock arrangement 834’ is operatively connected to an end of the input shaft 808 that is opposite the planetary gear 814 by means of a similar spline connection (as described above). Fig. 12b is a schematic view of a transmission apparatus 902 according to an alternative layout relative to an alternative to fig.12a, wherein the park lock arrangement 934, 934’, is shown in the same two alternative positions as described above with regard to fig. 12a. The transmission apparatus 902 differs from the transmission apparatus 802 according to fig. 12a in that the spline connection 966, 968 comprises external splines 966 provided in a first end of the shaft 912 and complimentary shaped internal splines 968 are provided in an end of the auxiliary shaft 936. It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.

Claims

CLAIMS 1. A transmission apparatus (2) comprising - a transmission arrangement (6) that comprises at least two transmission shafts (9, 10, 12), gears (14, 16; 18, 20) operationally connecting the transmission shafts (9, 10, 12) and a transmission housing (22, 122) that accommodates the transmission shafts (9, 10, 12) and gears (14, 16; 18, 20), wherein the transmission housing (22, 122) comprises an opening (32) that is adapted to provide access to one of the transmission shafts (9, 10, 12), - a park lock arrangement (34), wherein the park lock arrangement (34) comprises an auxiliary shaft (36), a park lock device (38) arranged to lock the auxiliary shaft (36) for achieving a park lock function, and a park lock housing (40, 140) that supports the auxiliary shaft (36), - wherein the park lock housing (40, 140) is adapted to be removably connected to the transmission housing (22, 122) for closing the transmission housing opening (32), and - wherein said one of the transmission shafts (9, 10, 12) and the auxiliary shaft (36) are rotationally rigidly connected to each other and extending through the transmission housing opening (32), and - wherein the park lock housing (40, 140) and the auxiliary shaft (36) are adapted to be movable in unison for achieving a connection and / or disconnection of the park lock housing (40, 140) and the transmission housing (22, 122).

2. A transmission apparatus according to claim 1, wherein a first end (42) of the auxiliary shaft (36) is journalled in the park lock housing (40, 140) by means of a bearing (44).

3. A transmission apparatus according to claim 2, wherein the park lock housing (40) comprises a wall (41) that forms a closed end in a direction of a rotational axis of the auxiliary shaft (36) distant from said one of the transmission shafts (9, 10, 12).

4. A transmission apparatus according to claim 3, wherein the first end (42) of the auxiliary shaft (36) is journalled in the wall (41) that forms the closed end of the park lock housing (40).

5. A transmission apparatus according to claim 3 or 4, wherein the wall (41) that forms the closed end of the park lock housing (40) is adapted to transfer loads during operation.

6. A transmission apparatus according to any one of claims 2-5, wherein a second end (62) of the auxiliary shaft (36) opposite the first end (42) of the auxiliary shaft (36) and a first end (64) of said one of the transmission shafts (8, 10, 12) are provided with complimentary shaped engagement means (66, 68) for providing a rotationally fixed engagement.

7. A transmission apparatus according to claim 6, wherein the first end (64) of said one of the transmission shafts (9, 10, 12) and the second end (62) of the auxiliary shaft (36) are provided with complimentary shaped engagement means (66, 68) in the form of splines.

8. A transmission apparatus according to claim 6 or 7, wherein the second end (62) of the auxiliary shaft (36) projects out from the park lock housing (40, 140).

9. A transmission apparatus according to any one of claims 6-8, wherein the transmission housing opening (32) is arranged and sized to provide axial access to the first end (64) of said one of the transmission shafts (9, 10, 12).

10. A transmission apparatus according to claim 9, wherein the transmission arrangement (6) and the park lock arrangement (34) are adapted for achieving the rotationally fixed engagement of the complimentary shaped engagement means (66, 68) when the park lock housing (40, 140) and the transmission housing (22, 122) are in a connected state and disengagement of the complimentary shaped engagement means (66, 68) when the park lock housing (40, 140) and the transmission housing (22, 122) are in a disconnected state.

11. A transmission apparatus according to any preceding claim, wherein the park lock arrangement (34) comprises a park lock device (38), which comprises a park lock wheel (70) rotationally rigidly attached to the auxiliary shaft (36), wherein the park lock wheel (70) comprises a plurality of circumferentially spaced recesses (72) in its radially outer circumference, wherein the park lock device (38) further comprises a park lock pawl (74), which is arranged to engage with one of the recesses (72) so that the park lock wheel (70) is blocked from rotation when the park lock device (38) is engaged.

12. A transmission apparatus according to claim 11, wherein the park lock pawl (74) is mounted in the park lock housing (40, 140).

13. A transmission apparatus according to any preceding claim, wherein the park lock housing (40, 140) accommodates the park lock device (38).

14. A transmission apparatus according to any preceding claim, wherein the park lock arrangement (34) is adapted to be movable as one single unit for achieving the removable connection of the park lock housing (40, 140) and the transmission housing (22).

15. A transmission apparatus according to any preceding claim, wherein the transmission arrangement (6) comprises an output shaft (10) that extends through a further opening (13) of the transmission housing (22, 122), that is separate from said transmission housing opening (32).

16. A transmission apparatus according to claim 15, wherein said transmission housing opening (32) is displaced in a direction transverse to a rotational axis of the output shaft (10).

17. A transmission apparatus according to any preceding claim, wherein the park lock housing (40, 140) comprises a connection surface (54), wherein the transmission housing (22, 122) comprises a connection surface (56) circumscribing the transmission housing opening (32), and wherein the connection surfaces (54, 56) are adapted for mating in the connected state of the park lock housing (40, 140) and the transmission housing (22, 122).

18. A transmission apparatus according to claim 17, wherein each one of the connection surfaces (54, 56) comprises a set of spaced holes for receiving bolts (58, 60), wherein the park lock housing (40, 140) and the transmission housing (22, 122) are arranged in a way that the holes align in a connected state of the park lock housing (40, 140) and the transmission housing (22, 122) for achieving a bolt connection between the park lock housing (40, 140) and the transmission housing (22, 122).

19. A transmission apparatus according to any preceding claim, wherein the transmission arrangement (6) comprises an input shaft (9), an output shaft (10) and a layshaft (12) that are connected by means of the gears (14, 16; 18, 20), wherein said one of the transmission shafts is formed by the layshaft (12).

20. A transmission apparatus according to any preceding claim, wherein the transmission housing (22, 122) comprises two housing parts (24, 26; 124, 126) and an internal chamber (28) of the transmission housing (22, 122) has a first circumferential size at a split plane of the two housing parts (24, 26; 124, 126), wherein the transmission housing opening (32) has a second circumferential size that is significantly smaller than the first circumferential size of the internal chamber (28) of the transmission housing (22, 122).

21. A transmission apparatus according to any preceding claim, wherein a seal (103) is arranged between said one of the transmission shafts (9, 10, 12) and the transmission housing (122) so that an internal chamber (128) in the transmission housing (122) may be fluidly separate from an internal chamber (137) in the park lock housing (140) in the connected state of the park lock housing (140) and the transmission housing (122).

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