DE102019123288A1 - Gear shift for an electromotive auxiliary bicycle drive - Google Patents

Abstract

The invention relates to a gear shift for an electromotive auxiliary bicycle drive (12), in which torque contributions from a crankshaft (14) and a drive shaft (35) drive a traction mechanism wheel (28) superimposed on one another, with several gear stages, comprising: one of the two torque contributions Central shaft (40), which is equipped with a pinion (43) per gear stage, the respective pinion (43) each with a coupling wheel (48) axially displaceable on the central shaft (40) by means of a shift fork (49) for at least two gear stages in Clutch engagement can be brought. At least two or more of the gear steps are each equipped with a motorized clutch assembly (52).

Description

The invention relates to a gear shift for an electric motor-driven bicycle auxiliary drive.

DE 10 2016 014 066 B3 describes a gear shift for an electromotive auxiliary bicycle drive, in which torque contributions from a crankshaft and a drive shaft drive a traction mechanism wheel superimposed on one another. Here, a central shaft acted upon by the two torque contributions is equipped with one pinion per gear step. To change gears, a claw wheel is brought into engagement with the respective pinion. This claw wheel, in turn, is operated by means of a shift fork. For this purpose, the selector forks are each supported by a bolt in a thread-like setting in a selector shaft. By turning this selector shaft, for example by means of a servomotor, the selector forks are moved linearly and thus the claws of the respective claw wheels engage and disengage from the respective pinion.

The disadvantage of the solution described above is that all shiftable gears are controlled simultaneously by guiding all shift forks in a common shift shaft. Separate control of the individual aisles is not possible. Due to the limited angular range of the selector shaft, the number of gears is limited. To shift the gears, a defined axial movement of the claw wheels is necessary, which results in a large gradient within the link of the selector shaft. Therefore, when shifting under high loads, a high torque is required on the shift shaft. This results in very high surface requirements for the setting of the selector shaft. Furthermore, the bearing concept of the selector forks and the selector shaft take up a large amount of space.

The invention is based on the object of providing a small-sized and structurally simple gear shift for an electromotive auxiliary bicycle drive, in which a separate control of the individual gear steps is possible.

This object is achieved by a gear shift with the features of claim 1. Advantageous embodiments are described in the subclaims.

The gear shift according to the invention for an electromotive auxiliary bicycle drive, in which the torque contributions of a crankshaft and a drive shaft drive a traction gear wheel superimposed on each other, with several gear stages has a central shaft acted upon by the two torque contributions, which is equipped with a pinion per gear stage, for at least two Gear stages the respective pinion can be brought into clutch engagement with a coupling wheel axially displaceable on the central shaft by means of a shift fork. At least two or more of the gear steps are each equipped with a motorized clutch assembly.

In this way, separate control of the individual gear steps is possible. Depending on requirements, the respective motorized clutch assembly can be actuated independently of the other clutch assembly or assemblies. In addition, the previously required common selector shaft is no longer required, which leads to a simplified and compact design.

A motorized clutch assembly is understood here to mean an assembly that can operate the respective shift fork with the aid of a motor, so that this shift fork can then bring the coupling wheel into clutch engagement or clutch disengagement. The use of a servo motor has proven to be particularly advantageous. In principle, however, other motor types can also be used.

In an advantageous embodiment, each of the motorized clutch assemblies also has a reduction gear arranged between the respective motor and the respective shift fork. In this way, the speed made available by the motor (in particular by a servomotor) can be adapted to the desired movement of the shift fork.

In a further advantageous embodiment, the clutch assembly between the reduction gear and the shift fork has a threaded spindle for actuating the respective shift fork. The use of a threaded spindle instead of the shift shaft with its shift gate ensures lower shifting torques, which in turn enables shifting even under high loads. In addition, the operating point of the gearshift can be set more flexibly compared to solutions with a conventional selector shaft, as this - unlike the gradient of the shift gate in the selector shaft - is not specified by a specific angular range.

In a further advantageous embodiment, the threaded spindle is received in a sleeve of the shift fork and is in threaded engagement with a threaded nut of the shift fork. In this way, a particularly compact design can be achieved. The switching precision can be increased by supporting or mounting the threaded spindle with slide bearings within the sleeve of the shift fork. Instead of plain bearings, the support can also take place by means of roller bearings.

If an output shaft of the motor of the coupling assembly and the threaded spindle are arranged axially parallel to one another, the space requirement of the coupling assembly can be further reduced and the ease of assembly can be increased. However, other arrangements are also possible.

The reduction gear of the motorized clutch assembly is advantageously designed as a multi-stage gear, in particular the first gear stage following the motor of the clutch assembly is designed as a worm gear and the second gear stage following this first gear stage is designed as a bevel gear. Although the configuration as a multi-stage transmission is an advantageous embodiment, a single-stage transmission is also conceivable. Furthermore, worm gears and bevel gears have proven to be particularly advantageous, but other types of gears are also conceivable, such as, for example, a spur gear, a planetary gear or a belt drive.

In further advantageous embodiments, the respective shift fork can engage in a groove running along the face of the respective coupling wheel and / or the coupling wheels are each designed as a claw wheel, which is equipped with claws for engaging the respective pinion.

Not all gears need to be equipped with a motorized clutch assembly. Rather, individual gear steps can be formed by a pinion that is non-rotatably connected to the central shaft without a clutch. In particular, the pinion for the lowest gear can be non-rotatably connected to the central shaft without a clutch.

• 1 eine schematische und vereinfachte Darstellung einer Dreigangschaltung für einen elektromotorischen Fahrrad-Zusatzantrieb;
• 2 eine Schaltgabel mit motorisierter Kupplungsbaugruppe in perspektivischer Ansicht; und
• 3 die Schaltgabel und motorisierte Kupplungsbaugruppe aus 2 in einer Schnittansicht.

Additional developments and modifications of the solution according to the invention emerge from the further claims and, also taking into account their advantages, from the following description of a preferred implementation example for this invention, outlined with an abstraction of the essential functionality. Show it:

• 1 a schematic and simplified representation of a three-speed gearshift for an electromotive auxiliary bicycle drive;
• 2 a shift fork with motorized clutch assembly in perspective view; and
• 3rd the shift fork and motorized clutch assembly 2 in a sectional view.

In the in 1 embodiment shown takes over a stable housing 11 of the additional electromotive drive 12th , as on a bicycle frame (not shown), the inclusion of a bottom bracket 13th for the two-sided out of the housing 11 protruding crankshaft 14th with their pedals (not shown) for muscle propulsion of the bicycle.

The speed of the crankshaft 14th that rotates with a spur gear 16 is equipped, is by means of a transmission gear 15th raised.

The transmission gear 15th drives a coupling wheel 25th including its central shaft 40 at. If it is the transmission gear 15th is a planetary gear, then its ring gear is preferably with the spur gear 16 engaged while the sun with the coupling wheel 25th and the central shaft 40 is coaxially in a rigid rotary connection. The planet carrier of this planetary gear is then preferably stopped via a support arm, acting on a measuring mechanism fixed to the housing 42 (not shown in detail).

The casing 11 It also houses a preferably high-speed electromotive drive motor 31 . Its speed is if necessary by means of a drive motor reduction gear 32 degraded. This can in particular be a spur gear or a transmission with a traction device such as a chain, a toothed belt or a profile belt. Also a planetary gearbox with directly on the drive shaft 35 of the drive motor 31 Sitting in the sun can be part of this drive motor reduction gear 32 be.

Both the transmission gear 15th as well as the drive motor reduction gear 32 are on the output side in engagement with the coupling wheel 25th ; so here the torque contributions from the crankshaft 14th and from the drive shaft 35 each other for turning the central shaft 40 are superimposed.

The central shaft 40 is with a spur toothed pinion 43 non-rotatably equipped. Than this pinion 43 can basically also use the coupling wheel 25th to serve; especially if it is designed as a planetary sun, so that only one of the transmission gears 15th or drive motor reduction gears 32 with the spur teeth of the coupling wheel 25th combs. In the interest of a clearer description of the invention, however, a separate coupling wheel is described below at that point as sketched 25th opposite axially offset pinion 43 assumed that - like the coupling wheel 25th - non-rotatably with the central shaft 40 connected or connectable to operation.

In a first gear the torque transmission from the coupling wheel 25th on a traction mechanism wheel 28 combs a pinion 43.1 relatively small Diameter with a relatively large drive wheel 26.1 , with which a hollow shaft 27 is equipped. The hollow shaft 27 is by means of roller bearings 44 concentric on the crankshaft 14th stored. Axially against the drive wheel 26th is shifted on the hollow shaft 27 the aforementioned traction mechanism wheel 28 non-rotatably arranged. This is used in a conventional manner to drive one of the surrounding housings 11 opposite the rear wheel mounted offset on the bicycle frame (not shown) via a traction device 29 , for example via a chain, a toothed belt or a profile belt.

Insofar a changeable translation between central shaft 40 and hollow shaft 27 is present, it is a gear shift 45 . Since their first gear is not the largest, it is between the drive wheel 26.1 and its hollow shaft 27 a freewheel 56 intended.

A second pinion is available for second gear with its higher spur gear ratio 43 in engagement with another drive wheel 26.2 . Between the drive wheel 26.2 and its hollow shaft 27 there is also a freewheel 56 .

This further, second pinion 43 rests by means of a roller bearing 61 on the central shaft 40 . It is therefore not in rotary connection with the central shaft 40 , but it can be done by means of a clutch wheel, namely a claw wheel 48.2 , coupled to it in a rotationally fixed manner (and also separated from it again); which is hereinafter referred to as reversing the clutch engagement.

Such a claw wheel 48.2 is along the central shaft 40 axially displaceable, but rotates with it. The claw wheel, which is preferably used here, faces in front of an axial end face 48.2 claws oriented parallel to the axis 47 on. For their axial displacement, for positive engagement in the axially adjacent pinion 43 , is radial to the central shaft 40 extending shift fork 49.2 (in 1 only shown schematically) provided. Its U-like edged fork opening engages centripetally in a groove 60 one that is around the claw wheel 48.2 running along the forehead. The shift fork is located at the end opposite the fork opening 49.2 with the interposition of a servomotor reduction gear 50.2 with a servo motor 51.2 in operative connection.

The servo motor reduction gear 50.2 and the servo motor 51.2 form a motorized clutch assembly 52.2 for a second course. By controlling the servo motor 51.2 can the shift fork 49.2 actuated and in this way the clutch claws of the claw wheel 48.2 in engagement with the pinion 43 or be brought to grips with this.

This is how it is with the pairing of wheels 43.2-26.2 the second gear of the gearshift 45 enableable. There is a third pair of wheels for a third gear 43.3 - 26.3 with its own motorized clutch assembly 52.3 with another servo motor reduction gear 50.3 and another servo motor 51.3 provided via a shift fork 49.3 an axial displacement of a claw wheel 48.3 undertakes.

The motorized clutch assembly 52.2 , 52.3 as well as the shift forks 49.2 and 49.3 for the second and third gear are each designed essentially identically and are described in more detail in the following figures.

The corresponding control of the servomotors 51.2 , 51.3 takes place from one, including the torque contribution of the drive motor 31 retrieving, central, in the surrounding housing 11 integrated control circuit 58 according to an evaluation of the measuring unit 42 recorded torque curve on the crankshaft 14th in order to always pedal with the same muscle power as possible with an adapted and therefore comfortable cadence.

2 and 3rd show one embodiment of a motorized clutch assembly 52 that act as a clutch assembly 52.2 and 52.3 in 1 can serve and with the respective shift fork 49.2 or. 49.3 is in operative connection.

The clutch assembly 52 has a servo motor 51 on, the non-rotatable in the housing 11 is stored. The output shaft (in 2 not shown and in 1 not provided with a separate reference number) of the servo motor 51 goes into a snail 71 a worm gear 72 over. The snail 71 is in engagement with a corresponding worm wheel 73 . The worm gear 72 thus forms a first gear stage of the reduction gear 50 . On the as a straight pin 74 (see. 3rd ) formed axis of the worm wheel 73 is a first bevel gear 75 arranged. This first bevel gear 75 meshes with a second bevel gear 76 and together with this forms a bevel gear 77 . The bevel gear 77 thus provides a second gear stage of the reduction gear 50 represent.

The second bevel gear is used to dampen vibrations 76 with a damping element 78 provided, the ring between an inner part 79 of the bevel gear 76 and an outer part 80 of the bevel gear 76 is arranged.

As the output shaft of the bevel gear 77 serves a threaded spindle 81 that rotatably with the second bevel gear 76 connected is. The lead screw 81 has a thread in a partial area, especially a trapezoidal thread (in 3rd not provided with a separate reference symbol). A bearing of the threaded spindle 81 in the casing 11 takes place through a first roller bearing 82 and a second roller bearing 83 .

The threaded spindle is used from a functional point of view 81 to operate the shift fork 49 . To this end, the shift fork 49 a sleeve 84 on through which the threaded spindle 81 is led. One in the sleeve 84 trained threaded nut 85 is in thread engagement with the thread of the threaded spindle 81 . By operating the servo motor 51 This results in a pivoting of the U-like edged fork opening of the shift fork 49 (i.e. the in 2 The end of the shift fork located in the lower part of the picture 49 ) and an engagement and extension of the claws 47 of the respective claw wheels 48 in or out of the respective pinion 43 .

The lead screw 81 is also about a first plain bearing 86 and a second plain bearing 87 inside the sleeve 84 supported. A clasp 88 secures the position of the threaded nut 85 inside the sleeve 85 . One on the shift fork 49 attached magnet 89 also serves a sensor, not shown in detail, for determining the shift fork position or for gear recognition.

The gear shift shown thus has a central shaft 40 on that with a pinion 43 is equipped for each gear step, whereby for two gear steps the respective pinion ( 43 .2, 43.3 ) each with one by means of a shift fork 49 axially on the central shaft 40 sliding claw wheel 48 can be brought into clutch engagement. Each of these two gear steps comes with a motorized clutch assembly 52 fitted. The motorized clutch assembly 52 each has a servo motor 51 to operate the respective shift fork 49 , one between the servo motor 51 and the respective shift fork arranged reduction gear 50 as well as a threaded spindle 81 on. The reduction gear is a two-stage gear with a worm gear 72 as first gear and a bevel gear 77 designed as a second gear. The lead screw 81 comes in a sleeve 84 the shift fork 49 recorded and stands with one in the sleeve 84 trained threaded nut 85 in thread engagement. The output shaft of the servo motor 51 is axially parallel to the threaded spindle 81 arranged.

List of reference symbols

11

Casing

12th

Additional drive

13th

Bottom bracket

14th

crankshaft

15th

Transmission gear

16

Spur gear

25th

Coupling wheel

26, 26.1, 26.2, 26.3

Driving wheel

27

Hollow shaft

28

Traction gear

29

Traction means

31

Drive motor

32

Drive motor reduction gear

35

drive shaft

40

Central shaft

42

Measuring mechanism

43, 43.1, 43.2, 43.3

pinion

44

roller bearing

45

Gear shift

47

Claws

48, 48.2, 48.3

Claw wheel

49, 49.2, 49.3

Shift fork

50, 50.2, 50.3

Reduction gear

51, 51.2, 51.3

Servo motor

52, 52.2, 52.3

Clutch assembly

56

Freewheel

58

Control circuit

60

Groove

71

slug

72

Worm gear

73

Worm gear

74

Straight pin

75

First bevel gear

76

Second bevel gear

77

Bevel gears

78

Damping element

79

Inner part of the bevel gear

80

Outer part of the bevel gear

81

Threaded spindle

82

First roller bearing

83

Second roller bearing

84

Sleeve

85

Threaded nut

86

First plain bearing

87

Second plain bearing

88

Clasp

89

magnet

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102016014066 B3 [0002]

Claims (11)

Gear shift for an electromotive auxiliary bicycle drive (12), in which torque contributions from a crankshaft (14) and a drive shaft (35) drive a traction mechanism wheel (28) superimposed on one another, with several gear stages, comprising: a central shaft (40) acted upon by the two torque contributions , which is equipped with a pinion (43) per gear step, whereby for at least two gear steps the respective pinion (43) can be brought into clutch engagement with a coupling wheel (48) which can be moved axially on the central shaft (40) by means of a shift fork (49), characterized in that at least two or more of the gear steps are each equipped with a motorized clutch assembly (52). Gear shift after Claim 1 , the motorized clutch assembly (52) each having a servo motor (51) for actuating the respective shift fork (49). Gear shift after Claim 2 wherein the motorized clutch assembly (52) further comprises a reduction gear (50) arranged between the servomotor (51) and the respective shift fork. Gear shift after Claim 1 wherein the clutch assembly (52) furthermore has a threaded spindle (81) between the reduction gear (50) and the respective shift fork (49) for actuating the respective shift fork (49). Gear shift after Claim 4 , wherein the threaded spindle (81) is arranged within the respective shift fork (49). Gear shift according to one of the Claims 4 or 5 , the threaded spindle (81) being received in a sleeve (84) of the shift fork (49) and in threaded engagement with the shift fork (49), in particular with a threaded nut (85) of the shift fork (49). Gear shift according to one of the Claims 4 to 6th , wherein the threaded spindle (81) is supported by plain bearings (86, 87) or roller bearings. Gear shift according to one of the Claims 4 to 7th , wherein an output shaft of the servomotor (51) and the threaded spindle (81) are arranged axially parallel to one another. Gear shift according to one of the preceding claims, wherein the reduction gear (50) is designed as a multi-stage gear. Gear shift according to one of the preceding claims, wherein at least one gear stage of the reduction gear (50) is designed as a worm gear (72). Gear shift according to one of the preceding claims, wherein at least one gear stage of the reduction gear (50) is designed as a bevel gear (77).

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