Electric Bicycle Drive Unit Mounting Arrangement

Description

[0001] The invention relates to an electric bicycle drive unit mounting arrangement for mounting an electric mid-motor drive unit to a bicycle frame of an electric bicycle.

[0002] In this context, an electric bicycle is understood to mean any type of bicycle that has a supporting electric drive unit that supplements the human drive power introduced into the pedal crank by a rider with a corresponding electric motor drive power, if desired. The present invention relates to a fastening arrangement for a so-called mid-motor drive unit, which both rotatably supports the pedal crankshaft and has an output element, for example at least one chainring that drives a rear wheel of the electric bicycle. With a mid-motor drive unit, very high mechanical forces can act on the drive unit for short periods of time, which must be transmitted to the bicycle frame via the fastening arrangement.

[0003] From DE 10 2016 112 778 A1 and DE 10 2017 201 617 A1, which disclose all features of the preamble of independent claim 1, fastening arrangements are known in which the bicycle frame has two parallel vertical frame flanges, to which corresponding vertical housing flanges of the drive unit housing are fixed. Although this fastening arrangement has a high degree of mechanical stability, it also transmits the structure-borne sound of the drive unit housing to the bicycle frame. However, the acoustic properties of electric bicycle drive units are increasingly becoming the focus of end consumers' purchasing decisions.

[0004] From the subsequently published documents WO 2022 / 043182 A1 and DE 10 2020 200385 A1, a fixation of a drive unit to a bicycle frame-side drive mount with damping means is known.

[0005] From JP 2016-64721 A, the suspension of an internal combustion engine on a motorcycle frame is known, in which one end of the internal combustion engine is held on the motorcycle frame via a separate bracket, wherein a rubber sleeve is provided between the lower end of the bracket and the internal combustion engine in order to dampen the vibration transmission.

[0006] Against this background, the object of the invention is to provide a stable electric bicycle drive unit mounting arrangement with improved acoustic properties.

[0007] This object is achieved according to the invention with an electric bicycle drive unit fastening arrangement having the features of claim 1.

[0008] The electric bicycle drive unit fastening arrangement according to the invention allows the electric mid-motor drive unit to be mounted in a floating manner on a drive mount of a bicycle frame, thus completely avoiding a rigid connection between the drive unit housing and the bicycle frame. The drive mount of the bicycle frame has two parallel, frame-fixed, and essentially vertical frame flanges. The drive unit housing has two parallel and essentially vertical housing flanges, which, when the drive unit is mounted, are each arranged proximally, i.e., inside, of the frame flanges. The left housing flange is attached to the left frame flange, and the right housing flange is attached to the right frame flange. The drive unit is thus attached to the bicycle frame by two flange pairs, each flange pair consisting of a frame flange and the associated housing flange.The frame flange and / or the housing flange do not necessarily have to be formed by a web positioned vertically in a vertical plane. In particular, the housing flange can also be formed by a flange surface of the housing body that does not protrude vertically from the embedded part of the drive housing.

[0009] Both flange pairs each have at least one rubber mount, through which the frame flange is connected to the associated housing flange in a floating, rubber-elastic manner, so that the two housing flanges do not directly contact the corresponding frame flanges. A clearance gap of at least 0.3 mm is formed between the housing flange and the frame flange. In this case, a rubber mount does not necessarily mean a mount made of rubber, but rather a rubber-elastic mount that creates a non-rigid and exclusively elastic connection, significantly reducing structure-borne sound transmission compared to a rigid connection.

[0010] The rubber sleeve is arranged in a substantially cylindrical annular gap between a rigid outer sleeve and a rigid inner sleeve. The composite of the rigid outer sleeve, the rubber sleeve, and the rigid inner sleeve can be provided as a prefabricated component, wherein the rubber sleeve is bonded with its outer peripheral surface to the inner peripheral surface of the outer sleeve and with its inner peripheral surface to the outer peripheral surface of the inner sleeve, preferably by material bonding, for example by vulcanization. Alternatively, and particularly preferably additionally, a positive connection of the respective interface pairs can also be provided. The outer sleeve and / or the inner sleeve are preferably made of metal.

[0011] Even under higher pedaling and drive forces, this ensures that there is no direct mechanical contact between the metal drive housing and the metal bicycle frame. This prevents the transmission of structure-borne noise from the drive housing to the bicycle frame. Overall, structure-borne noise emissions are therefore significantly reduced, significantly improving the acoustic properties of the electric bicycle.

[0012] The rubber bearing preferably has a substantially ring- or cylindrical-shaped rubber sleeve, through which the pedaling and drive forces occurring at the drive unit are transmitted essentially in a radial direction. Sufficient dimensioning of the rubber sleeve is easily achieved by appropriately designing the sleeve length, the sleeve diameter, and the radial material thickness of the rubber sleeve. In this way, even very high forces can be transmitted without the drive unit moving significantly relative to the bicycle frame. In particular, this reliably ensures that the housing flange does not strike the corresponding frame flange.

[0013] Preferably, the outer sleeve of the sleeve assembly sits in a through-bore of the housing flange. In this way, the sleeve assembly can be inserted from the proximal direction, i.e., from the center of the drive unit, distally into the respective through-bore of the housing flange, so that it can be secured to the respective distal frame flange using a suitable fastening device, such as a screw bolt.

[0014] Preferably, the inner sleeve is fastened directly to the associated frame flange in a force-fitting and / or form-fitting manner. For example, the inner sleeve can have an internal thread into which an external thread of a screw bolt is screwed, which is inserted from the distal direction into a corresponding bolt opening in the frame flange. In this way, the drive unit can be mounted to the bicycle frame by screwing a screw bolt, for example a threaded screw, into the inner sleeve from the distal direction exclusively on both flange pairs.

[0015] Preferably, the rubber sleeve has a spacer collar at its distal longitudinal end, which is arranged axially between the outer sleeve and the corresponding frame flange. The spacer collar ensures a constant minimum gap between the frame flange and the associated housing flange, specifically on both sides, and specifically with respect to both flange pairs on the left and right. This ensures that, even under heavy mechanical loads, no direct contact, even in a punctiform or brief manner, can occur between the frame flange and the associated housing flange.

[0016] Preferably, form-locking structures are provided on the inside of the outer sleeve and on the outside of the inner sleeve, which engage with complementary form-locking structures on the outside and inside of the rubber sleeve. The rubber sleeve is thus practically non-rotatably interlocked with the inner sleeve and the outer sleeve via form-locking structures. This is particularly important when the sleeve assembly is fixed to the frame flange and / or the housing flange via a threaded connection, which exerts a torque on the sleeve assembly during assembly.

[0017] Preferably, the outer sleeve has an anti-rotation structure at its proximal longitudinal end, which supports the outer sleeve against rotation on the drive unit housing. The anti-rotation structure is particularly necessary when the corresponding inner sleeve of the sleeve assembly is mounted to the frame flange via a threaded bolt or screw. The anti-rotation structure prevents the sleeve assembly from rotating along with the screwing movement during assembly.

[0018] In the following, an initial example of the invention is explained in more detail with reference to the drawings. They show: Figure 1 a vertical section II of an electric bicycle drive unit mounting arrangement with a mid-engine drive unit mounted on a bicycle frame-side drive mount, Figure 2a horizontal section II-II of the electric bicycle drive unit mounting arrangement of the Figure 1 , Figure 3 the left fastening arrangement III including a 3-part sleeve assembly of the Figure 2 in enlarged view, and Figure 4 an outer sleeve and an inner sleeve of the sleeve assembly of the Figure 3 .

[0019] In the Figure 1 An electric bicycle 10 with a bicycle frame 20 and a mid-engine drive unit 30 is shown schematically in vertical section. The drive unit 30 is designed purely as a support and supports the human drive power of a rider during riding.

[0020] In the present case, only a short section of a frame down tube and a drive mount 21 are shown of the electric bicycle 10. The drive unit 30 has a closed drive unit housing 34 in which an electric drive motor 32 and a transmission 31 are arranged. The transmission 31 can have a fixed gear ratio, can be a manual transmission, or can be a continuously variable transmission. Furthermore, a transversely extending output shaft 35, which in this case also represents the bottom bracket shaft, is mounted in the drive unit housing 34. In principle, however, the output shaft and the bottom bracket shaft can also be provided separately from one another, for example, arranged concentrically to one another. A left and a right pedal crank 36 are provided at the two longitudinal ends of the output shaft 35, and pedal pedals 37 are provided at each of the ends.An output element 38 designed as a gear with more than 20 teeth is provided on the output shaft 35 in a rotationally fixed manner, which drives a rear wheel pinion of a rear wheel of the bicycle 10 via a chain drive.

[0021] In the Figure 1-3 Two fastening arrangements 50 are shown, by means of which the drive unit 30 is floatingly attached to the drive mount 21 of the bicycle frame 20. The drive mount 21 has two parallel frame flanges 211, 212, fixed to the frame and each arranged in a vertical plane, so that a clamp-like mount is formed, open at the bottom and U-shaped in cross-section. Attached to the two frame flanges 211, 212 are parallel housing flanges 41, 42 of the drive housing 34, which also stand in a vertical plane and protrude vertically upward from the closed drive housing 34.

[0022] In principle, however, the housing flanges can also be integrated into the actual drive housing 34.

[0023] The left frame flange 211 is elastically attached to the left housing flange 41 by a rubber bearing 80, and the right frame flange 212 is elastically attached to the right housing flange 42 by an identical rubber bearing 80. The two housing flanges 41, 42 each have a cylindrical through-bore 49 into which a sleeve assembly 60 is inserted from the proximal direction. The sleeve assembly 60 essentially consists of a rigid outer sleeve 90 formed by a metal sleeve body 92, a rigid inner sleeve 70 formed by a metal sleeve body 72, and a substantially cylindrical, elastic rubber sleeve 82 essentially forming the rubber bearing 80. The rubber sleeve 82 fills a cylindrical annular gap 100 between the substantially cylindrical inner peripheral surface of the outer sleeve 90 and the substantially cylindrical outer peripheral surface of the inner sleeve 70.The rubber sleeve 82 is bonded or vulcanized to the outer sleeve 90 and the inner sleeve 70.

[0024] The outer sleeve outer body is substantially cylindrical on its outer peripheral surface 99 and is clamped with its outer peripheral surface 99 into the cylindrical inner peripheral surface of the through hole 49.

[0025] In the Figure 4 the sleeve assembly 60 is shown without the rubber sleeve 82. In particular, in the Figure 4It is clearly visible that the outer sleeve 90 has, on the outside at its proximal longitudinal end, a stop ring flange 94 which is located in a radial plane and which has an anti-rotation structure 98 in the form of two chord-shaped linear flattenings 98', the chord lines of which are parallel to each other. The outer sleeve 90 and thus the entire sleeve assembly 60 is rotationally blocked in the pre-assembled state on the drive unit 30 and in the final assembled state, since the flattening 98' in cooperation with a corresponding flat counter surface 34' of the drive unit housing 34 creates a rotational positive connection, as for example in the Figure 1 is recognizable.

[0026] On the inside of the outer sleeve sleeve body 92, three form-locking pockets 96 are provided on each of the two longitudinal ends of the sleeve body 92, which rotationally correspond to similar form-locking webs 74 on the outside of the inner sleeve sleeve body 72. The total of six form-locking pockets 96 and a total of six form-locking webs 74 engage with corresponding complementary form-locking webs and pockets of the rubber sleeve 82 in a form-locking manner, so that in this way a reliable, rotationally fixed connection between the inner sleeve 70 and the outer sleeve 90 is ensured even at high torques during assembly.

[0027] The inner sleeve 70 has an internal thread 76 on the inside, into which an external thread 56 of a screw bolt 52 is screwed from the proximal end. The screw bolt 52 has a cylindrical threaded shaft 54 and a bolt head 56. The associated frame flange 211, 212 has a stepped through-bore 27 through which the screw bolt 52 is inserted during assembly and screwed with its threaded shaft 54, which has the external thread 56, into the inner sleeve internal thread 76. In this way, the inner sleeve 70 is non-positively fastened to the frame flange 211, 212.

[0028] As particularly in the Figure 3As can be seen, the rubber sleeve 82 has at its distal longitudinal end a spacer collar 88 which projects radially outwards in a radial plane and which, in the assembled state and only in the region of the outer sleeve 90, fills an axial gap 58 between the distal end face 43 of the outer sleeve 90 and the proximal flange face 23 of the associated frame flange 211, 212. The spacer collar 88 thereby ensures, in the static case, a clearance gap x of approximately 1.0 mm between the housing flange 41, 42 and the associated corresponding frame flange 211, 212. Since at least one fastening arrangement 50 is provided on both the left and right, the drive unit 30 is thus centered in a floating manner between the two frame flanges 211, 212.

[0029] In the dynamic case, i.e., during operation, this always ensures a minimal clearance gap that is always large enough to prevent the housing flanges 41, 42 from striking the associated frame flanges 211, 212. This prevents the transmission of structure-borne noise from the drive unit housing 34 to the bicycle frame 20, so that the overall noise emissions caused by the drive unit 30 are reduced compared to a mounting arrangement with a rigid connection of the drive unit to the bicycle frame.

Claims

1. An electric bicycle drive unit mounting arrangement (50) by which an electric mid-motor drive unit (30) is floatingly mounted to a drive receptacle (21) of a bicycle frame (20), the mid-motor drive unit (30) having a drive unit housing (34) in which an output shaft extending in the transverse direction is mounted and which has a bottom bracket shaft, the drive receptacle (21) having two mutually parallel frame-fixed and vertical frame flanges (211, 212), a drive unit housing (34) having two mutually parallel and vertical housing flanges (41, 42), one housing flange (41) being mounted to the one frame flange (211) and the other housing flange (42) being mounted to the other frame flange (212) and each defining a flange pairing, and the housing flanges (41, 42) each being arranged proximally of the frame flanges (211, 212) so that a clamp-like drive receptacle (21) is defined which is downwardly open and U-shaped in cross-section, characterized in that both flange pairings each have at least one rubber bearing (80) by which the frame flange (211, 212) is floatingly and rubber-elastically connected to the associated housing flange (41, 42) so that the housing flanges (41, 42) each do not rest directly against the corresponding frame flanges (211, 212) but are spaced apart from the corresponding frame flanges (211, 212) by a spacing gap (58) having a gap dimension X of at least 0.3 mm, and the rubber sleeve (82) is arranged in a substantially cylindrical annular gap (100) between a rigid outer sleeve (90) and a rigid inner sleeve (70).

2. The electric bicycle drive unit mounting arrangement (50) according to claim 1, wherein the rubber bearing (80) has a substantially annular or cylindrical rubber sleeve (82).

3. The electric bicycle drive unit mounting arrangement (50) according to one of the preceding claims, wherein the outer sleeve (90) is seated in a through bore (49) of the housing flange (41, 42).

4. The electric bicycle drive unit mounting arrangement (50) according to one of the preceding claims, wherein the inner sleeve (70) is rigidly mounted directly to the frame flange (211, 212) in a force-fitting and / or form-fitting manner.

5. The electric bicycle drive unit mounting arrangement (50) according to claim 4, wherein the inner sleeve (70) has an internal thread (76) into which an external thread (56) of a screw bolt (52) is screwed, which is inserted from the distal direction into a bolt opening (27) of the frame flange (211, 212).

6. The electric bicycle drive unit mounting arrangement (50) according to one of the preceding claims, wherein the rubber sleeve (82) has a spacing collar (88) which is arranged axially between the outer sleeve (90) and the corresponding frame flange (211, 212).

7. The electric bicycle drive unit mounting arrangement (50) according to one of the preceding claims, wherein form-fitting structures are provided on the inner side of the outer sleeve (90) and on the outer side of the inner sleeve (70), which form-fitting structures engage in a form-fitting manner with complementary form-fitting structures on the outer side and the inner side of the rubber sleeve (82).

8. The electric bicycle drive unit mounting arrangement (50) according to one of the preceding claims, wherein the outer sleeve (90) has at its proximal longitudinal end a rotation-preventing structure (98) by means of which the outer sleeve (90) is supported in a rotation-preventing manner on the drive unit housing (34).