Bottom-bracket transmission for a micromobility vehicle

Abstract

The invention relates to a bottom-bracket transmission with a planetary gear set design for a micromobility vehicle (1), comprising at least one shift element. Each shift element has a shift ring (3) with an outer toothing (4), said shift ring being paired with a shift pawl (5) for blocking or releasing the shift element shift ring (3) paired with the transmission component. At least one rotatably mounted shift drum (7) for actuating the paired shift pawl (5) is arranged axially parallel to a central transmission rotational axis (6), and a shift actuator (8) is arranged in the interior of the shift drum (7), which is at least partly designed as a hollow shaft. The invention additionally relates to a micromobility vehicle (1) comprising the bottom-bracket transmission.

Description

[0001] Bottom bracket transmission for a micromobility vehicle. The present invention relates to a bottom bracket transmission in a planetary gear set design for a micromobility vehicle with at least one shifting element for shifting a gear ratio. Each shifting element has a shifting ring with external teeth, to which a shifting pawl is assigned for locking and releasing the shifting ring of the shifting element assigned to a transmission component, and at least one rotatably mounted shift drum for actuating the assigned shifting pawl is arranged axially parallel to a central transmission rotation axis. The invention further relates to a micromobility vehicle with the bottom bracket transmission.For example, from the publication DE 102019220044 A1, a bottom bracket transmission in planetary gearset design for a bicycle or a pedelec is known, comprising an arrangement for actuating at least one brake shifting element, which has a plurality of planetary gear sets for implementing different gear ratios. Several brake shifting elements are assigned to the bottom bracket transmission, each of which has a brake ring associated with a transmission component, which can be locked or released via a brake pawl in order to engage a predetermined, assigned gear ratio. Each brake pawl is actuated by a rotatably mounted shift drum, which is arranged approximately axially parallel to a central rotational axis of the bottom bracket transmission. A Bowden cable is provided for the rotational actuation of the shift drum.For this purpose, a rotationally fixed pin or the like is attached to the shift drum outside the housing, to which one end of the Bowden cable is connected, while the other end of the Bowden cable is arranged, for example, on a handlebar of the bicycle or pedelec, to be actuated by the operator, so that the shift drum can be actuated via the Bowden cable in order to select a desired gear ratio. The present invention is based on the object of proposing a bottom bracket gear and a micromobility vehicle with the bottom bracket gear, in which a particularly simple and space-neutral actuation of the shift drum is provided. This object is achieved according to the invention by the features of patent claims 1 and 10, respectively. Advantageous and claimed developments emerge from the subclaims and the description as well as the drawings.Accordingly, a bottom bracket transmission in planetary gearset design for a micromobility vehicle with at least one shifting element is proposed, wherein each shifting element has a shifting ring with external teeth or the like, to which a shifting pawl is assigned for locking and releasing the shifting ring of the shifting element assigned to a transmission component, and wherein at least one rotatably mounted shift drum for actuating the assigned shift pawl is arranged axially parallel to a central transmission rotation axis. In order to provide the actuation of the shift drum with the simplest possible design and with the lowest possible installation space, it is provided that a shift actuator for actuating the shift drum is arranged inside the shift drum, which is designed at least in sections as a hollow shaft.In this way, the actuation in the form of a shift actuator is integrated into the shift drum in a space-neutral manner by making the shift drum at least partially hollow, so that at least part of the actuator unit is arranged radially inward or radially nested in the shift drum, thereby significantly reducing the axial space requirement in the transmission housing and thus not exceeding the specified axial width of the transmission housing between the pedal cranks of the micromobility vehicle. A micromobility vehicle is understood to be a vehicle that can be operated using human power and / or an electric drive system, whereby the micromobility vehicle always has a bottom bracket. For example, micromobility vehicles include bicycles, pedelecs, S-pedelecs, cargo bikes, velomobiles, and e-bikes.A structurally simple embodiment of the torque transmission between the preferably electromechanical shift actuator and the shift drum can be achieved within the scope of the invention via a drive pinion of the shift actuator, which engages with an internal toothing or the like as a driving profile inside the shift drum. In addition to the structurally simple design, the torque transmission in the interior of the shift drum results in an overall very compact design in the transmission housing. In order to achieve optimal actuation of the shift drum by the electromechanical shift actuator in the proposed bottom bracket transmission, it is provided within the scope of the invention that the electromechanical shift actuator has an integrated reduction gear in addition to an electric motor or servomotor or the like.With the help of the reduction gear, the required rotation of the shift drum for actuating the shift pawls can be achieved by the electromechanical shift actuator. The fact that the shift actuator and the shift drum are arranged coaxially, almost radially, nested within one another results in the advantage that the shift drum with the shift actuator can be accommodated in the transmission housing almost axially parallel to the transmission rotation axis in a space-saving manner, so that the axial installation space required can be reduced to a minimum. For structurally simple and space-efficient torque support between the shift actuator and the transmission housing, it can be provided within the scope of the invention that the shift actuator is held in the shift drum and fastened to the transmission housing via a support sleeve or the like for torque support. Various arrangements are conceivable with regard to the structural design of the support sleeve used.A particularly space-saving and sufficiently stable design provides that the support sleeve has an approximately hollow-cylindrical or cylindrical receiving area for receiving the shift actuator, wherein a first end of the receiving area assigned to the drive pinion of the shift actuator has a through-opening or recess or the like for the axial passage of the drive pinion and wherein a second end of the receiving area has a fastening flange for connecting the support sleeve to the transmission housing. Accordingly, the shift actuator and its housing are received in the support sleeve for torque support in such a way that the rotating drive pinion protrudes axially from the support sleeve in order to be positively connected to the driving toothing of the shift drum, whereby in addition to torque support, torque transmission between the shift actuator and the shift drum is also ensured. In order to ensure position and / orIn order to implement rotation angle detection on the shift drum in a way that is as space-neutral as possible, the invention provides for an angle sensor or the like for rotation angle position detection to be arranged on one end face of the shift drum in a radially inner region of the shift drum. For example, the angle sensor can be attached to the shift drum via a press connection, by gluing or the like. For this purpose, the shift drum is also designed to be hollow in this region in order to arrange the components of the carrier in a nested manner radially inward. Preferably, an angle sensor facing the angle sensor of the shift drum is arranged on the gearbox housing side. The arrangement of the angle sensor fixed to the housing significantly simplifies signal transmission from the angle sensor in the proposed bottom bracket gearbox. Brake switching elements are preferably provided as switching elements in the bottom bracket gearbox.Such a brake shifting element has a brake ring that can only be locked in one direction of rotation via a brake pawl, whereby the brake pawl is actuated via the shift drum. By locking a brake ring assigned to a transmission component, the associated gear ratio in the bottom bracket transmission is then engaged. A further aspect of the present invention claims a micromobility vehicle with the above-described bottom bracket transmission, which results in the advantages already described and others. The present invention is further explained below with reference to the drawings.5 shows a schematic individual part view of a support sleeve for a shift actuator of the bottom bracket gear. Figures 1 and 2 show various views of a bottom bracket gear according to the invention in planetary gear set design, using a micromobility vehicle 1 as an example. The bottom bracket gear comprises a plurality of planetary gear sets 2 arranged coaxially to a central gear rotation axis 6 in a gear housing orBottom bracket shell 12 for implementing various gear ratios with a plurality of shifting elements, designed, for example, as brake shifting elements, wherein each shifting element or brake shifting element has a shifting ring or brake ring 3 with external teeth 4, to which a shifting pawl or brake pawl 5 is assigned for locking or releasing the brake ring 3 of the brake shifting element assigned to a transmission component of the planetary gear sets 2. The brake ring 3 is arranged coaxially to the transmission rotation axis 6 of the planetary gear sets 2. For actuating a plurality of brake pawls 5, a rotatably mounted shift drum 7 is provided, which is arranged axially parallel to the central transmission rotation axis 6. The shift drum 7 is assigned to an oil sump 24 of the bottom bracket transmission for better oil supply.Because the shift drum 7 is at least partially immersed in the oil located in the oil sump 24, the shift drum 7 and the surrounding components are supplied with oil, which is particularly indicated in Figure 1. In order to realize actuation of the shift drum 7 with as little installation space as possible, an electromechanical shift actuator 8 is arranged inside the shift drum 7, which is at least partially designed as a hollow shaft. Accordingly, a radially nested design of the shift drum 7 and the electromechanical shift actuator 8 is provided. Because the shift drum 7 is partially hollow on the inside, the shift actuator 8, consisting of an electric servomotor and a reduction gear, can be accommodated as a unit nested radially on the inside of the shift drum 7 in order to minimize the necessary axial width between the pedal cranks of the bottom bracket gear.For torque transmission, a drive pinion 9 of the shift actuator 8 engages with an internal toothing 10 as a driving profile in the inner region of the shift drum 7. The shift actuator 8 and the shift drum 7 are arranged coaxially to one another. For torque support, the shift actuator 8 is held in the shift drum 7 via a support sleeve 11 and fastened to a gearbox housing or bottom bracket shell 12 of the bottom bracket gearbox. From the individual part views of the shift drum according to Figures 3 and 4 and of the support sleeve 11 according to Figure 5, it is clear that the support sleeve 11 has an approximately hollow-cylindrical receiving area 23 for receiving the shift actuator 8. The receiving area 23 is assigned to a first receiving space 13 inside the shift drum 7.The receiving area 23 has, at a first end assigned to the drive pinion 9 of the shift actuator 8, a through-opening 14 for axially passing through the drive pinion 9, while a second end of the receiving area 12 has a fastening flange 15 for fastening the support sleeve 11 to the transmission housing 12. The drive pinion 9 is assigned to a second receiving space 16 inside the shift drum 7, which, viewed axially, adjoins the first receiving space 13, wherein the second receiving space 16 is assigned the internal toothing 10 as a driving profile of the shift drum 7, with which the drive pinion 9 is positively connected. Viewed axially, a third receiving space 17 inside the shift drum 7 adjoins the second receiving space 16, wherein an angle sensor 18 for position detection on the shift drum 7 is assigned to the third receiving space 17.The rotary angle sensor 18 for shift drum position detection is attached to the front of the shift drum 7 directly opposite the shift actuator 8 via a press connection or by adhesive. Directly opposite the rotary angle sensor 18, in the area of ​​a housing cover 19 of the transmission housing 12, a corresponding rotary angle sensor 20 is arranged fixed to the housing in order to sense the angular position of the shift drum 7. The rotary angle sensor 20 arranged on the transmission housing side is preferably attached to the outside of a thin wall of the housing cover 19. The housing cover 19 is preferably made of aluminum or plastic, so that the sensor signal can be detected directly by the rotary angle sensor 20 arranged in the dry area through the non-ferromagnetic wall. The electric servomotor of the shift actuator 8 is preferably a BLDC motor with Hall sensing. The control is carried out via a 3-stage cascade PI controller.The position controller uses both the absolute angle information from the shift drum rotation angle detection and the rotor position information from the internally installed Hall sensors of the shift actuator 8, thereby achieving increased accuracy. As can be seen in particular from Figures 3 and 4, several shift gates 25 are provided on the outer circumference of the shift drum 7. The shift gates 25 are designed differently with regard to their elevations and depressions, or peaks and valleys, over the circumferential area. Each shift gate 25 of the shift drum 7 is assigned to a brake pawl 5 for actuating it or for shifting a predetermined gear ratio. The shift drum 7 is mounted radially in the transmission housing 12 via a first deep groove ball bearing 21 and a second deep groove ball bearing 22.In particular, it can be seen from Figure 2 that the second deep groove ball bearing 22 assigned to the shift actuator 8 has a press fit with the shift drum 7 and, in addition to providing radial guidance, also serves to axially guide the shift drum 7. This second deep groove ball bearing 22 is frictionally connected to the shift drum 7 via its inner ring via the press fit and is axially guided via its outer ring between the transmission housing 12 and the support sleeve 11. This results in a particularly short tolerance chain in the radial direction and, at the same time, in the axial direction at the air gap between the rotary angle sensor 18 on the shift drum 7 and the rotary angle sensor 20 on the housing cover 19, thereby increasing the precision of the shifting process.

[0002] Reference numeral 1 Micromobility vehicle 2 Planetary gear set 3 Shift ring or brake ring 4 External toothing 5 Shift pawl or brake pawl 6 Central transmission rotation axis 7 Shift drum 8 Shift actuator 9 Drive pinion of the shift actuator 10 Internal toothing as driving profile of the shift drum 11 Support sleeve 12 Gearbox housing or bottom bracket housing 13 First receiving space inside the shift drum 14 Through opening in the receiving area of ​​the support sleeve 15 Fastening flange of the support sleeve 16 Second receiving space inside the shift drum 17 Third receiving space inside the shift drum 18 Angle sensor 19 Housing cover 20 Angle sensor 21 First deep groove ball bearing 22 Second deep groove ball bearing 23 Support sleeve receiving area 24 Oil sump in the gearbox housing 25 Shift gate

Claims

Claims 1. A bottom bracket transmission in planetary gear set design for a micromobility vehicle (1) with at least one switching element, wherein each switching element has a switching ring (3) with external teeth (4), to which a pawl (5) for locking or releasing the switching ring (3) of the switching element associated with a transmission component is assigned, and wherein at least one rotatably mounted switching drum (7) for actuating the associated pawl (5) is arranged parallel to a central transmission rotation axis (6), characterized in that a switching actuator (8) is arranged inside the switching drum (7), which is designed at least partially as a hollow shaft.

2. A bottom bracket transmission according to claim 1, characterized in that the electromechanical switching actuator (8) engages via a drive pinion (9) with internal teeth (10) as drive profiles inside the switching drum (7). 3.Bottom bracket gearbox according to one of the preceding claims, characterized in that the switching actuator (8) comprises an electric motor and an integrated reduction gearbox.

4. Bottom bracket gearbox according to one of the preceding claims, characterized in that the switching actuator (8) and the switching drum (7) are arranged coaxially to each other.

5. Bottom bracket gearbox according to one of the preceding claims, characterized in that the switching actuator (8) is held in the switching drum (7) by a support sleeve (11) for torque support and is attached to a gearbox housing (12).

6. Bottom bracket gearbox according to claim 5, characterized in that the support sleeve (11) has an approximately hollow cylindrical receiving area (23) for receiving the switching actuator (8), wherein a first end of the receiving area (23) associated with the drive pinion (9) has a through-opening (14) for axially guiding the drive pinion (9) and wherein a second end of the The receiving area (23) has a mounting flange (15) for connecting the support sleeve (11) to the gearbox housing (12).

7. Bottom bracket gearbox according to one of the preceding claims, characterized in that a rotary encoder (18) for position detection is arranged on an end face of the shift drum (7) in a radially inner area.

8. Bottom bracket gearbox according to claim 7, characterized in that a rotary encoder (20) facing the rotary encoder (18) on the shift drum (7) is arranged on the gearbox housing side.

9. Bottom bracket gearbox according to one of the preceding claims, characterized in that at least one brake switching element with a brake ring (3) that can be locked in only one direction of rotation via a brake pawl (5) is provided as a switching element.

10. Micromobility vehicle (1) with a bottom bracket gearbox according to one of the preceding claims.

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