MEANS OF TRANSPORT THAT CAN BE SIMULTANEOUSLY DRIVEN ELECTROMOTIVELY AND BY HUMAN MUSCULAR POWER

Abstract

A means of transport, in particular a pedelec, which can be driven by means of drive energy produced electromotively and by human muscular power, comprising a drive unit in which an electric drive motor and a harmonic drive transmission are nested one inside the other, thereby saving space.

Claims

1-15. (canceled)

16. A means of transport, in particular a pedelec, that can be simultaneously driven electromotively and by human muscular power, with a drive unit, said drive unit comprising: an input shaft for transmitting drive energy generated from human muscular power; an output shaft for delivering drive energy to a travel unit; a harmonic drive transmission arranged around a rotation axis and having a wave generator, a flexspline and a ring gear; an electric drive motor arranged around the rotation axis and having a stator and a rotor, wherein drive energy of the electric drive motor can be transmitted to the output shaft via the harmonic drive transmission, wherein the flexspline is configured as a sleeve extending in the direction of the rotation axis, which is connected on one axial side to a rotary bearing and toward the other axial side has an engagement region for the wave generator, wherein a sleeve cavity is provided between the rotary bearing and the wave generator, as seen in the direction of the rotation axis, and wherein the electric drive motor is arranged in an axial direction of the rotation axis at least partially, preferably completely, in the sleeve cavity of the flexspline of the harmonic drive transmission, in particular with respect to the axial extent of its rotor and/or stator along the rotation axis.

17. The means of transport according to claim 16, wherein the wave generator, the flexspline and the ring gear of the harmonic drive transmission are arranged overlapping one another in a gearing plane perpendicular to the rotation axis, and the flexspline, in particular the sleeve of the flexspline, is mounted rotatably with respect to a counter bearing in a bearing plane perpendicular to the rotation axis, wherein the electric drive motor is arranged between the gearing plane and the bearing plane.

18. The means of transport according to claim 16, wherein a speed and/or rotation angle sensor, in particular a Hall sensor, is provided at the electric drive motor, wherein the speed and/or rotation angle sensor is arranged in particular in the sleeve cavity of the flexspline.

19. The means of transport according to claim 16, wherein a rotary bearing for the output shaft and a rotary bearing for the input shaft are arranged in a common shaft bearing plane perpendicular to the rotation axis.

20. The means of transport according to claim 16, wherein the electric drive motor and the harmonic drive transmission are arranged coaxially to one other around the rotation axis.

21. The means of transport according to claim 16, wherein the input shaft is connected to the output shaft in a co-rotating manner at least in one direction of rotation, and the energy provided through human muscular power is transmitted to the output shaft.

22. The means of transport according to claim 16, wherein the flexspline of the harmonic drive transmission is mounted on a stationary housing part via a freewheel.

23. The means of transport according to claim 22, wherein the freewheel is switchable or the flexspline and the stationary housing part can be connected in a co-rotating manner by a separate clutch unit, so that the electric drive motor can be operated as a generator which receives drive energy from the ring gear and converts it into electrical energy.

24. The means of transport according to claim 22, wherein a rotary bearing is arranged between a counter bearing and the flexspline of the harmonic drive transmission in a bearing plane perpendicular to the rotation axis such that it overlaps with a freewheel.

25. The means of transport according to claim 16, wherein the wave generator, the flexspline and the ring gear of the harmonic drive transmission are arranged in a gearing plane perpendicular to the rotation axis together with a rotary bearing for the rotor of the electric drive motor, in particular with respect to a counter bearing.

26. The means of transport according to claim 16, wherein in a direction along the rotation axis, the shaft bearing plane, the gearing plane of the harmonic drive transmission, the bearing plane of the flexspline of the harmonic drive transmission and, in particular, also an electronics bearing plane are arranged in succession.

27. The means of transport according to claim 16, wherein the drive unit is configured as a center drive unit, in particular wherein the rotation axis is arranged coaxially with a pedaling axis, or that the drive unit is configured as a hub drive unit, in particular wherein the rotation axis is arranged coaxially with a wheel axis.

28. The means of transport according to claim 16, wherein the maximum extent of the drive unit along the rotation axis is not more than 100 mm, preferably not more than 85 mm, more preferably not more than 70 mm, in particular, for example, not more than 60 mm.

29. The means of transport according to claim 16, wherein a control unit for controlling the electric drive motor is provided, which comprises at least one of the following features: it is arranged together with a rotary bearing for a crankshaft in the electronics bearing plane perpendicular to the rotation axis; it is connected to a rotation angle and/or speed and/or torque sensor at the input shaft; it is connected to a travel speed sensor; it is connected to a speed and/or rotation angle sensor, in particular a Hall sensor, at the electric drive motor; it is connected to an amperemeter for the electric drive motor; it controls the speeds and torques of the electric drive motor such that the drive energy, including the energy obtained from human muscular power, at the output shaft corresponds to the energy requirement of the drive unit; it controls the speed of the electric drive motor in proportion to the travel speed; depending on the direction of rotation of a shaft driven by human muscular power, the control unit activates a drive support function or a brake function; it is connected to a suspension travel sensor of the means of transport and at least partially compensates a pedal kickback caused by compression of a suspension of the means of transport by controlling the electric drive motor; it is connected to a display unit which is visible from the outside through a viewing window in the drive unit; it brings the input shaft into a starting position by controlling the electric drive motor.

30. The means of transport according to claim 16, comprising at least one of the following features: the means of transport is configured as a single-, double- or triple-track vehicle, in particular an electric bicycle, pedelec, e-bike, cargo bike or transport bike; the means of transport comprises a frame, in particular with a top tube and/or down tube; the means of transport comprises an electrical energy storage device, in particular arranged in the top tube and/or down tube; the means of transport comprises a front wheel and a rear wheel; the front wheel is steerable; the means of transport comprises pedals which are rotatable about a pedaling axis via crank arms and which are in particular connected to the input shaft in a co-rotating manner.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The invention will be explained in more detail below by reference to the embodiment examples shown in the figures. In the schematic figures:

[0034] FIG. 1: is a side view of a means of transport with a center drive unit;

[0035] FIG. 2: is a side view of a means of transport with a hub drive unit

[0036] FIG. 3: is an external view, in particular a top view, of the center drive unit;

[0037] FIG. 4: is an external view, in particular a top view, of the hub drive unit;

[0038] FIG. 5: shows a cross-section through a harmonic transmission;

[0039] FIG. 6: is a cross-sectional view along the rotation axis through a drive unit configured as a center drive unit.

[0040] Like parts, or parts acting in a like manner, are designated by like reference numerals. Recurring parts are not designated separately in each figure.

DETAILED DESCRIPTION

[0041] FIGS. 1 and 2 each show a means of transport F, more specifically a bicycle, in particular a pedelec. It can be driven simultaneously by electric motors and human muscle power, especially such that the drive from human muscular power is supported by an electric motor. In a known manner, the means of locomotion F comprises a frame 73 and two travel units 72, more specifically a front wheel and a rear wheel. The pedal axis 65 is located at the center and at the lower end of the frame 73. The wheel axle 66 is located at the connection point of the frame 73 with the rear wheel. FIG. 1 shows an embodiment in which the drive unit 1 is configured as a center drive unit and lies on the pedal axis 65. Human muscle power is applied directly to the drive unit 1 via the crankshaft. The transmission output of the drive unit 1 is configured as a traction means gearwheel 10 (see FIGS. 3 and 6) and is connected to the rear wheel hub 2 via a traction means 3, for example a chain. In the embodiment shown in FIG. 2, the drive unit 1 is configured as a hub drive unit and is arranged on the wheel axle 66. In this case, the transmission output of the drive unit 1 is configured as a hub housing, the rotational movement of which is transmitted to the rear wheel via the spokes 59 (see FIG. 4). Via the traction means 3, the drive unit 1 is connected to the bottom bracket 4, through which human muscle power is applied to the drive unit 1.

[0042] FIGS. 3 and 4 each show a top view of the drive unit 1 from the outside. FIG. 3 shows the drive unit 1 as a center drive unit. The rotation axis 9 of the drive unit 1 lies on the pedaling axis 65 about which the crank arms 5 and the pedals 6 of the means of transport F rotate during a pedaling motion by an operator. The traction means gearwheel 10 serves to transmit the rotational movement to the rear wheel hub 2. The width of the drive unit 1 is designated with B1. The distance between the crank arms 5 is designated with B2. To allow comfortable pedaling with the pedals 6 which is adapted to the human anatomy, the distance B2 of the crank arms 5 should be between 140 and 180 mm. The width B1 of the drive unit 1 must therefore be correspondingly smaller. In addition, FIG. 3 shows the control unit 42, which is integrated into the drive unit 1. The control unit 42 is connected to a plurality of sensors to detect the operating state of the drive unit 1 and the means of transport F, as will be explained in more detail below. Moreover, the control unit 42 is connected to a display unit 70, for example a luminous display, which can be viewed from outside the drive unit 1. For example, the display unit 70 is arranged behind a viewing window in the outer housing of the drive unit 1. The display unit 70 can therefore be viewed by an operator seated on the means of locomotion F by glancing downward. FIG. 4 shows an embodiment in which the drive unit 1 is configured as a hub drive unit. The rotation axis 9 of the drive unit 1 is therefore located on the wheel axis 66 about which the rear wheel rotates when the means of transport F is in motion. A rotation originating from the pedals 6 is transmitted to the drive unit 1 via the traction means gearwheel 10. While the drive unit 1 as a center drive unit is passed through by a rotating crankshaft 32 (see FIG. 6), as a hub drive unit it is passed through by a stationary axle body 11 around which the rear wheel rotates. A part of the hub housing that rotates around the axle body 11 and is connected to the spokes 59 in a co-rotating manner serves as the transmission output and thus as the output shaft 12. The spokes 59 in turn transmit the rotational movement to the rest of the rear wheel.

[0043] FIG. 5 shows a cross-section through a harmonic gearing, more specifically the harmonic drive transmission 18, as used in the invention. The harmonic drive gearing 18 is arranged around the rotation axis 9 and comprises a wave generator 20, a rotary bearing 21, in particular a (grooved) ball bearing, a flexspline 19 and a ring gear 14. The ring gear 14 and the wave generator 20 are configured as rigid components, while the flexspline 19 is flexible or elastic. The wave generator 20 is oval and the flexspline 19 is mounted on the wave generator 20 via the rotary bearing 21 such that the flexspline 19 adapts to the oval shape of the wave generator 20 due to its elasticity. The ring gear 14 has an internal toothing and the flexspline 19 has a complementary external toothing, with the flexspline 19 typically having fewer teeth than the ring gear 14. Due to the oval shape of the wave generator 20, the external toothing of the flexspline 19 is pressed into the internal toothing of the ring gear 14 along the major axis of the wave generator 20. At the same time, the elastic deformation of the flexspline 19 causes its external toothing along the minor axis of the wave generator 20 to disengage from the internal toothing of the ring gear 14. When the wave generator 20 rotates, the flexspline 19 rotates in the opposite direction of rotation with a reduction ratio of i=z.sub.H/(z.sub.H?z.sub.F), where z.sub.H is the number of teeth of the ring gear 14 and z.sub.F is the number of teeth of the flexspline 19. When the flexspline 19 is retained, the ring gear 14 rotates at the corresponding reduced speed in the same direction as the wave generator 20. Such harmonic transmissions 18 are summation-type transmissions and are known in the prior art, and are therefore not explained in more detail here.

[0044] FIG. 6 shows a cross-section through the drive unit 1 configured as a center drive unit along the rotation axis 9 or the pedaling axis 65. The pedaling axis 65 is defined by the crankshaft 32, which is drivable by an operator via the pedals 6 and which passes through the drive unit 1 along the rotation axis 9. The crankshaft 32 is in co-rotating connection with the input shaft 33, through which the drive energy applied by the operator is introduced into the transmission of the drive unit 1. The transmission output is formed by the output shaft 12, which is connected to the traction means gearwheel 10, in this case the chainring, in a co-rotating manner. The drive unit 1 has two sources of drive energy or drive power: Firstly human muscle power via the input shaft 33 and secondly the electric drive motor 27. The electric drive motor 27 is integrated into the drive train of the drive unit 1 via the harmonic drive transmission 18.

[0045] When an operator rotates the crankshaft 32 by pedaling with the pedals 6, he thereby rotates the input shaft 33. The input shaft 33 is connected to the output shaft 12 via a freewheel 36. The freewheel 36 is configured such that it engages when the input shaft 33 rotates in the forward direction of travel and establishes a co-rotating connection between the input shaft 33 and the output shaft 12. During a rotation in reverse direction, on the other hand, the freewheel 36 rotates freely. Through the connection between the input shaft 33 and the output shaft 12, the drive energy introduced by the operator through pedaling with the pedals 6 is transmitted to the output shaft 12, and thus to the traction means gearwheel 10, at a one-to-one ratio. Furthermore, the output shaft 12 is connected to the ring gear 14 in a co-rotating manner.

[0046] The electric drive motor 27 comprises a stator 28 with stator windings 29 and a rotor 31 with permanent magnets 30. The stator 28 is arranged on a stationary counter bearing 43. The rotor 31 of the electric drive motor 27 is connected to the wave generator 20 of the harmonic drive transmission 18 in a co-rotating manner, in particular integrally. Therefore, the electric drive motor 27 drives the wave generator 20 of the harmonic drive gearing 18. The rotation of the wave generator 20 transmits the drive energy of the electric drive motor 27 to the flexspline 19. The flexspline 19 is supported on a stationary housing part 56 via a freewheel 37. The drive energy is transmitted to the ring gear 14 of the harmonic drive transmission 18 via the flexspline 19. The ring gear 14 of the harmonic drive gearing 18 is connected to the output shaft 12 in a co-rotating manner. In the ring gear 14 or the output shaft 12, the drive energy or drive power of the electric drive motor 27 and the human muscle power introduced via the crankshaft 32 are summed and transmitted to the traction means gearwheel 10. The electric drive motor 27 is configured to be operable to supply the main part of the drive energy or drive power for traveling operation of the means of transport F. To drive the ring gear 14 in the forward direction of travel, the wave generator 20 must likewise be rotated in the forward direction of travel. This results in an opposite direction of rotation of the flexspline 19, i.e., in the reverse direction. Therefore, in order for the drive energy to be transmitted from the wave generator 20 to the ring gear 14, the flexspline 19 must be supported in the reverse direction against a stationary housing part. Thus, the freewheel 37 is configured to establish a co-rotating connection between the flexspline 19 and the stationary housing part 56 when the flexspline 19 is rotated in reverse direction. A reverse rotation of the flexspline 19 is thereby prevented, so that all of the drive energy applied to the wave generator 20 by the electric drive motor 27 is transferred to the ring gear 14 and is available to drive the means of transport F.

[0047] If, on the other hand, the electric drive motor 27 is not operated or is operated only more slowly than the ring gear 14 is rotated, for example, by the operator through human muscle power, the output shaft 12 rotates the ring gear 14 and, through its meshing with the flexspline 19, also rotates the flexspline 19 in the forward direction of travel. However, in the direction of rotation of the flexspline 19 corresponding to the forward direction of travel, the freewheel 37 allows free rotation, whereby, in interaction with the rotary bearing 21 between the flexspline 19 and the wave generator 20, no drive energy is transmitted to the wave generator 20 and thus to the rotor 31 of the electric drive motor 27. Therefore, the electric drive motor 27 does not have to be dragged along by the rider when pedaling by pure muscle power, allowing for easy, comfortable pedaling with the pedals 6.

[0048] According to a preferred embodiment of the invention, the freewheel 37 is configured as a switchable freewheel 37. This means that it can be controlled by the control unit 42 such that it establishes a co-rotating connection between the flexspline 19 and the stationary housing part 56 in both directions of rotation. Alternatively, this co-rotating connection can be achieved by a separate clutch unit not shown. If the flexspline 19 is blocked in this manner also in a forward direction of rotation, drive energy is transmitted from the ring gear 14 to the wave generator 20 and thus to the rotor 31 of the electric drive motor 27. It is therefore then possible to operate the electric drive motor 27 as a generator, converting rotational energy from the ring gear 14 into electrical energy that can be fed into a battery, for example. By operating the electric drive motor 27 as a generator, the means of transport F is decelerated, so that this operation mode can also be used as a brake.

[0049] The present invention is characterized by a particularly narrow structure along the rotation axis 9. For this purpose, the drive unit 1 comprises a number of structural features, which are discussed below. Firstly, the invention utilizes a harmonic gearing, more specifically the harmonic drive transmission 18, in which the ring gear 14 is used as the gearing output. Due to this configuration, only a small amount of installation space is required in an axial direction of the rotation axis 9.

[0050] In addition, the flexspline 19 of the harmonic drive transmission 18 is configured with a sleeve 63. The sleeve 64 is a cylindrical extension of the flexspline 19 from its region of engagement with the ring gear 14 in the axial direction of the rotation axis 9. The sleeve 63 is located in the center of the drive unit 1 as seen axially along the rotation axis 9. At its axial end opposite the region of engagement with the ring gear 14, the sleeve 63 is mounted on a stationary housing part, for example the counter bearing 43, via a rotary bearing 45. The flexspline 19 extends, in other words, as seen in the axial direction of the rotation axis 9, from a gearing plane E1 arranged perpendicular to the rotation axis 9, in which the components of the harmonic drive transmission 18, wave generator 20, rotary bearing 21, flexspline 19 and ring gear 14 overlap in radial direction of the rotation axis 9, to a bearing plane E2, in which the flexspline 19 overlaps with the rotary bearing 45 in radial direction of the rotation axis 9. The flexspline 19 has a sleeve cavity 69 inside its hollow-cylindrical body. In order not to leave any installation space unused here, in the embodiment examples of the invention shown, the electric drive motor 27 is arranged in the sleeve cavity 69 of the flexspline 19 of the harmonic drive transmission 18. In particular, the electric drive motor 27 is arranged over the entire axial extent of its stator 28 with the stator windings 29 as well as the rotor 31 with the permanent magnets 30 inside the flexspline 19, in particular in the sleeve cavity 69. Furthermore, the electric drive motor 27 is arranged between the gearing plane El and the bearing plane E2.

[0051] Another key idea of the present invention is to make the drive unit 1 particularly narrow in the axial direction of the rotation axis 9 by arranging various rotary bearings at a same height as other components in the axial direction of the rotation axis 9. The individual components of the drive unit 1 are therefore nested within each other as seen in the axial direction of the rotation axis 9, as are the electric motor 27 and the harmonic drive transmission 18 due to the arrangement in the sleeve cavity 69. For example, it is envisaged that the rotary bearing 46, for example a ball bearing, for the rotor 31 of the electric drive motor 27 is arranged opposite a stationary counter bearing 43 together with the harmonic drive transmission 18 in the gearing plane E1. For example, the rotary bearing 46 overlaps the other components of the harmonic drive gearing 18, such as the wave generator 20, the rotary bearing 21, the flexspline 19, and the ring gear 14, over its entire axial extent in the direction of the rotation axis 9. In this way, the rotary bearing 46 does not need to be formed in axial succession with these components of the harmonic drive transmission 18, which reduces the overall extent of the drive unit 1.

[0052] Another implementation of this key idea can be found in the bearing plane E2. In the bearing plane E2 of the flexspline 19, viewed in radial direction of the rotation axis 9, there is an overlap between the rotary bearing 45, via which the flexspline 19 is mounted on the stationary counter bearing 43, and the freewheel 37 between the flexspline 19 and the stationary housing part 56. This also reduces the overall axial extent of the drive unit 1.

[0053] The rotary bearings 49 and 50, both also preferably ball bearings, are also arranged in a common shaft bearing plane E3 perpendicular to the rotation axis 9. The rotary bearing 49 is arranged between the input shaft 33 and the output shaft 12, and supports them rotatably relative to each other. The rotary bearing 50 is arranged between the output shaft 12 and a stationary housing part 57. The rotary bearings 49, 50 are of identical configuration (except for the necessary difference in diameter), lie concentrically around the rotation axis 9 and, viewed in radial direction of the rotation axis 9, overlap in particular completely.

[0054] A further rotary bearing 44 between the crankshaft 32 and a stationary housing part 56 is located in a further electronics bearing plane E4 arranged perpendicular to the rotation axis 9, in which the rotary bearing 44 at least partially overlaps with the control unit 42 in radial direction of the rotation axis 9. This means that the control unit 42 is not merely attached to the outside of the drive unit 1, but is nested with gearing elements of the drive unit 1, which again saves axial extent. To the outside, the control unit 42 is covered by a housing cover 55.

[0055] The control unit 42 is configured to control the electric drive motor 27. In order to be able to perform the respective control functions, the control unit 42 requires various measured values regarding the current operating state of the drive unit 1 and the means of transport F. For example, the control unit 42 is connected to the suspension travel sensor 67 and the travel speed sensor 68 shown in FIGS. 1 and 2, both of which are arranged on the rear wheel. In addition, the control unit 42 is connected to an amperemeter 71, via which the control unit 42 measures the amperage in the electric drive motor 27. In addition, the control unit 42 is connected to a Hall sensor 38 at the electric drive motor 27 via a printed circuit board 39. Both the circuit board 39 and the Hall sensor 38 are also arranged in the sleeve cavity 69 together with the electric drive motor 27. This sensor 38 can be used to determine the speed and rotation angle position of the electric drive motor 27. Another sensor unit 51, 52 connected to the control unit 42 has a stationary part 52 at the stationary housing, for example the counter bearing 43, and a part 51 rotating with the input shaft 33. The sensor unit 51, 52 determines, for example, the torque applied by human muscle power to the crankshaft 32 and thus the input shaft 33, as well as the rotation angle position. The speed of the crankshaft 32 and thus of the input shaft 33 can likewise be determined via the time derivative of the rotation angle position. The stationary part 52 of the sensor unit 51, 52 is fastened to the counter bearing 43, in particular by means of a fastening nut 53, in particular in a region in which the counter bearing 43 is mounted relative to the crankshaft 32 via a rotary bearing 54, in particular a needle bearing.

[0056] The embodiment example of the drive unit 1 shown in FIG. 6 is configured as a center drive unit and is therefore arranged at the pedaling axis 65. However, the means of transport F according to the invention may also be configured with a drive unit 1 configured as a hub drive unit. Such a drive unit 1 is then configured such that its rotation axis 9 is coaxial with the wheel axis 66, in particular of the rear wheel. This configuration of the drive unit 1 is for the most part similar to the drive unit 1 configured as a center drive unit. Therefore, only the differences will be briefly discussed. In particular, when the drive unit 1 is configured as a hub drive unit, there is no crankshaft 32 passing through the drive unit 1. Instead, the drive unit 1 is passed through by a stationary, static axle body 11, which comprises, for example, the counter bearing 43 as well as various stationary housing parts 56. The input shaft 33 is not moved directly by the pedals 6 or the crankshaft 32, but the pedal movement is transmitted to the input shaft 33 via the traction means 3 and the traction means gearwheel 10. Further, the output shaft 12 is not connected to the traction means gearwheel 10, but is formed by a rotating hub housing connected to the ring gear 14 in a co-rotating manner. The spokes 59 of the rear wheel are arranged on the hub housing. Moreover, a brake disc is also typically arranged on the hub housing. Otherwise, the embodiment of the drive unit 1 as a hub drive unit corresponds to that as a center drive unit, and thus reference is made to the above discussion to avoid repetition.

[0057] All in all, the invention makes it possible to provide a particularly compact drive unit 1 in terms of its axial extent along the rotation axis 9. In addition, the drive unit 1 according to the invention can be used to represent a plurality of control functions desired in modern means of transport F, such as pedelecs.