Drive assembly for bicycle
By adopting the tributary liberal wheel mechanism and sensor equipment in the free wheel mechanism of the bicycle, the problem of inaccurate detection deformation is solved, the accurate measurement and control of the driving torque is realized, and the impact of interference parameters is reduced.
Patent Information
- Application Number
- CN202410990372.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-07-27
- Filing Date
- 2024-07-23
- Publication Date
- 2025-01-28
AI Technical Summary
In the free wheel mechanism of the bicycle, the detected deformation is inaccurate, resulting in inaccurate transmission of the driving force, especially in the locked state, where there are interference parameters such as radial forces.
Adopt the spiny paw -type free wheel mechanism, through the meshing part of the first and second rings and the embedded mechanism of the pawns, realize the transfer of torque, and install the sensor equipment on the first ring to detect the deformation to determine the driving force of the transmission. Essence
Through the design and the use of sensors, the deformation of the liberal liberal wheel mechanism can accurately detect the deformation, thereby accurately measured and control the driving moment of the transmitting, and reduce the impact of interference parameters.
Smart Images
Figure CN119370244A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a drive assembly for a bicycle. In addition, the present invention also relates to a bicycle. Background Art
[0002] It is known that in bicycles, freewheel mechanisms are provided. This allows, for example, the pedal crankshaft to be decoupled from the driven running wheel. The bicycle can thus roll without the respective pedals of the bicycle rotating with it. In electric assisted bicycles, the freewheel mechanism can be used, for example, to also decouple the drive motor. In contrast, in the locked state, the freewheel mechanism connects the two shafts to each other in a rotationally fixed manner, in order, for example, to enable the transmission of driving force.
[0003] By detecting the deformation of components of the freewheel mechanism, the transmitted drive force can be detected, for example, in order to control the drive. However, depending on the design of the freewheel mechanism and the relative positioning of the two shafts when connected to one another, interfering variables may occur. For example, in the locked state, radial forces may act in the freewheel mechanism, which cause the deformation of the freewheel mechanism to be dependent on the locked state position. Accordingly, the detected deformation can only correspond inaccurately to the transmitted drive force. Summary of the invention
[0004] A first aspect relates to a drive assembly for a bicycle. The drive assembly may, for example, have a transmission, a pedal crankshaft, a running wheel and respective force transmission elements to the running wheel. The drive assembly may have a drive motor, which is, for example, configured as an electric motor. The drive assembly may be configured for a bicycle configured as an electric power-assisted bicycle. The drive assembly may be configured to transmit a driving force from a cyclist and optionally from a drive motor to the running wheel.
[0005] The drive assembly has a ratchet freewheel mechanism. The ratchet freewheel mechanism is also called a locked ratchet freewheel mechanism. The freewheel mechanism can, for example, transmit torque only in one direction of rotation, wherein the freewheel mechanism is then in its locked state. On the other hand, in the event of a relative reversal of the direction of rotation, the connection is automatically released, so that the freewheel mechanism is then in its released state. The ratchet freewheel mechanism can, for example, be configured to disconnect a drive (such as a pedal crank shaft) from a driven end. The ratchet freewheel mechanism can, for example, also disconnect the pedal crank shaft from the drive motor or disconnect the drive motor from the pedal crank shaft. The ratchet freewheel mechanism can also be configured to change the gear in the transmission of the drive assembly.
[0006] The pawl freewheel mechanism has at least one first ring and a second ring. The two rings can be permanently connected to the shaft of the drive assembly in a rotationally fixed manner. The first ring has a toothing. The toothing can extend radially inwardly or outwardly along the circumference of the first ring, for example. The pawl freewheel mechanism has at least one pawl movably supported on the second ring. The pawl can also be called a locking pawl. The pawl engages with the toothing of the first ring in the locked state. The pawl can be preloaded by a spring, for example, in terms of the engagement. In the released state, the engagement of the pawl with the toothing is cancelled. In the locked state, the two rings are connected to each other in a rotationally fixed manner via the engagement. In the released state, the pawl slides on the toothing, for example, and allows the two rings to rotate relative to each other. The pawl can, for example, allow the two rings to rotate relative to each other in one direction of rotation, and prohibit rotation in the opposite direction of rotation from the engagement of the pawl with the toothing. The rings can also each have a non-annular partial area. The pawl and the toothing can be arranged on the sides of the two rings facing each other. The two rings can be arranged coaxially with each other. The two rings can be arranged in the same axial region. The two rings can be supported so as to be rotatable about the central axis.
[0007] The drive assembly has a sensor device, which is configured to detect the deformation of the first ring of the pawl freewheel mechanism due to the applied driving force. In the locked state, the driving force can be transmitted to the second ring, or in the locked state, it can be transmitted from the second ring to the first ring. The driving force can be introduced into the drive assembly, for example, by the cyclist at the respective pedals. The detected deformation can, for example, allow conclusions about the transmitted torque to be provided. Therefore, it can be possible to perform power measurement, automatic control of the gear shift of the bicycle, and alternatively or additionally control the drive motor. Control can also be directly dependent on the detected deformation. The sensor device can, for example, have at least one sensor. The sensor device can, for example, be configured to determine the deformation by resistive, magnetic, optical or also acoustic means. The sensor device can, for example, have one or more strain gauges fastened to the first ring. The sensor device can have an evaluation device to evaluate the respective sensor signals. If multiple sensors are provided, their sensor signals can, for example, be fused into a single measured value.
[0008] The first ring has at least one meshing area and a toothless area in the peripheral direction. In this way, the relative position of the engagement of the pawl and the meshing part relative to the measurement part of the deformation on the first ring can be predetermined. In this way, interference parameters caused by the relative positioning of the two rings when the pawl and the meshing part are engaged can be avoided when measuring the deformation. For example, the engagement will cause radial forces. In addition, when the first ring is hollow, the measurement part can be realized, for example, not on the central axis of the first ring. If a continuous meshing part is provided, the radial force will affect the deformation differently depending on the angle of the engagement of the pawl and the meshing part relative to the measurement part. Therefore, the calculation of the applied torque based on the detected deformation may be extremely inaccurate, because it is highly related to the positioning.
[0009] The measuring position can correspond to the positioning of the sensor of the sensor device at the first ring, for example. The first ring can have, for example, only a single meshing area with only a single tooth, so that the engagement position is always oriented in accordance with the measuring position. However, multiple meshing areas can also be provided. Alternatively or additionally, multiple teeth can also be provided in the respective meshing areas. Then, for example, a faster engagement and thus a locking of the pawl-type freewheel mechanism can be achieved in the corresponding rotation direction. The meshing area can form a meshing portion. However, the first ring can also have multiple meshing areas, which together form a meshing portion. If multiple pawls are provided, these pawls can be in engagement at the same time, so that the load on the component can still be kept very small. Nevertheless, due to the toothless area, the possible changes in the orientation of the respective engagement relative to the respective deformation measurement position can still be very small, so that the influence of interference parameters (such as radial forces) can be very small. The relative orientation of the engagement of the pawl and the meshing portion relative to the sensor can, for example, be within a predetermined angle range relative to the respective sensor of the sensor device.
[0010] A plurality of meshing regions can be provided, and alternatively or additionally a plurality of toothless regions can be provided. For example, toothless regions can be arranged between each meshing region in the peripheral direction. The respective meshing regions can be spaced apart from each other in the peripheral direction, for example, respectively by toothless regions. Each meshing region has at least one tooth, which is configured to engage with a pawl. If a plurality of teeth are provided in each meshing region, these teeth can exist side by side in the peripheral direction and, for example, directly adjacent to each other. The meshing region and the toothless region extend, for example, outside or inside in the peripheral direction at the first ring. The respective pawl and the alternative or additional meshing region can be constructed in a consistent manner. The respective pawl and the alternative or additional meshing region can be arranged equally, particularly symmetrically. The respective following embodiments for only one meshing region and alternatively or additionally only one pawl are also applicable to multiple meshing regions or pawls (if they can be used).
[0011] In one embodiment of the drive assembly, it can be provided that the first ring has at least one first meshing area and a second meshing area. The two meshing areas can be spaced apart from each other in the peripheral direction by a first toothless area and a second toothless area. Each meshing area can thus form a separate meshing section of the meshing portion. For example, two pawls can be provided, which in the locked state are respectively engaged with one of the two meshing areas. In this way, a high torque transmission can be achieved in a compact structural form. The two meshing areas can be arranged oppositely at the periphery of the first ring. In this way, a symmetrical force introduction can be achieved.
[0012] In one embodiment of the drive assembly, it can be provided that the drive assembly has at least two pawls. However, the drive assembly can also have three or more pawls. These pawls can be arranged, for example, at a distance from each other, on the inside or outside of the second ring. The angular extension of the respective meshing area can be greater than or equal to the angular distance between the two pawls. If three or more pawls are provided, the angular extension of the respective meshing area can be greater than or equal to the maximum angular distance between the two pawls. The pawls can be arranged equally along the periphery of the second ring. The angular extension of the meshing area can be the angle between the first end of the meshing area in the peripheral direction and the second end of the meshing area in the peripheral direction starting from the center point or the rotation axis of the first ring. The angular distance between the two pawls can be the angle between the first pawl and the second pawl adjacent thereto in the peripheral direction starting from the center point or the rotation axis of the second ring. It can be measured, for example, from the bearing point or the engagement point of the two pawls. For example, for the angular distance between the two pawls, the same position in each pawl can be used as the starting point. For example, if the respective bearing points, about which two adjacent pawls are mounted so as to be rotatable, are spaced 25° apart along the circumference of the second ring, the engagement region can also extend at least 25° along the circumference of the first ring. This makes it possible for the engagement of the pawls and thus also the locked state to be independent of the positioning of the two rings relative to one another and thus predictable for the cyclist. If the engagement region is, for example, shorter than the spacing between the pawls, then the first ring must be rotated further or shorter, depending on the positioning, until the respective pawls engage.
[0013] In one embodiment of the drive assembly, it can be provided that the sensor device is configured to detect the deformation of the first ring in the region where the torque applied by the cyclist at the pedal of the bicycle drive has been accumulated. Thus, the detected deformation is particularly suitable for the control of the drive train and is alternatively or additionally suitable for power detection. For example, for this reason, the respective sensors are arranged at the first ring, for example, axially arranged in the region of the second ring and on which the pawl is arranged. For example, all the torques from the two pedals of the bicycle can be accumulated at the first ring. If the pedal crankshaft constitutes the first ring, the torque introduced can be accumulated, for example, axially in the region of the second ring or the pawl. For example, the torque from the two pedals can be accumulated for the first time at the lead-out end of the pedal crankshaft. Alternatively or additionally, the sensor device is configured to detect the deformation of the first ring in the region where the torque applied by the cyclist at the pedal of the bicycle drive has not been superimposed with the driving torque of the drive motor. Therefore, the drive motor can be easily controlled, for example, by relying on the driving force of the cyclist.
[0014] In one embodiment of the drive assembly, it can be provided that the sensor device is designed to detect a deformation of the first ring in at least one area adjacent to at least one of the meshing areas. The detection area can be adjacent, for example, radially and alternatively or additionally in the peripheral direction. For example, the detection area can be in the same peripheral area as the closest meshing area. The detection area can be defined, for example, by the arrangement of strain gauges or by the orientation of an optional deformation sensor. By means of adjacent detection, the deformation can be particularly strong and therefore also the measurement signal.
[0015] In one embodiment of the drive assembly, it can be provided that the sensor device is configured to detect a deformation of the first ring in at least one area opposite to at least one of the meshing areas. The detection area can, for example, be in a peripheral area different from the closest meshing area. For example, the detection area can be in a peripheral area between two closest meshing areas. For example, the detection area can be arranged adjacent to a toothless area. For example, the detection area can be in the same peripheral area as the closest toothless area. As a result, the measurement can be subjected to fewer interfering signals, such as radial forces caused by the engagement of the pawl.
[0016] It can also be provided that the deformation of the first ring is detected in at least one first area opposite to at least one of the meshing areas and in a second area adjacent to at least one of the meshing areas. This makes it easy to filter interference signals. For example, a sensor of the sensor device can be arranged in each detection area.
[0017] In one embodiment of the drive assembly, it can be provided that the sensor device has at least one strain gauge as a sensor, which is arranged on the first ring. Deformations in specific areas can be detected particularly easily with the strain gauge. In addition, the strain gauge can also be easily integrated into the drive assembly. It is also possible to arrange two or more strain gauges, for example, at different areas of the first ring. The respective strain gauge can be fastened, for example, to the end side of the first ring.
[0018] In one embodiment of the drive assembly, it can be provided that the sensor device is designed to determine the drive torque transmitted by the pawl freewheel mechanism as a function of the deformation. For this purpose, the sensor device can have an evaluation device, which is designed to calculate the drive torque as a function of the detected deformation. In this case, a plurality of measured deformations, for example in different regions, can also be taken into account. The transmitted drive torque can be used particularly well as a control variable for other functions of the drive assembly or of the bicycle as a whole.
[0019] In one embodiment of the drive assembly, it can be provided that the drive assembly has more pawls than engagement areas. This allows the freewheel to be locked quickly when the direction of rotation changes. In addition, the engagement area can be very small and nevertheless ensure a fast and position-independent engagement of the pawl. With a very small engagement area, the engagement of the pawl with the tooth relative to the position of the sensor will be very similar at each engagement of the pawl freewheel mechanism. For example, a multiple of the number of engagement areas can be provided as the number of pawls.
[0020] In one embodiment of the drive assembly, it can be provided that the respective meshing area has a large number of teeth, which are arranged side by side in the peripheral direction. As a result, the number of ratchets can be small and nevertheless a fast and position-independent engagement of the ratchets is ensured. Alternatively, all or only some of the meshing areas can have only one tooth.
[0021] In one embodiment of the drive assembly, it can be provided that the first ring is left open in the respective toothless region. This allows, for example, the first ring to extend radially less far in the toothless region than in the meshing region. The radial extension can be measured, for example, to the tooth base. The first ring can be thinner in the toothless region, for example. Deformations can thus occur more strongly in the meshing region, where they can be detected particularly well.
[0022] In one embodiment of the drive assembly, it can be provided that the first ring is designed as an inner ring and the second ring is designed as an outer ring. The second ring can be arranged radially outwardly relative to the first ring. The toothing can then be arranged radially outwardly on the first ring. This allows particularly cost-effective and simple production. The respective pawl can, for example, be supported radially inwardly on the second ring.
[0023] In one embodiment of the drive assembly, it can be provided that the first ring is designed as an outer ring and the second ring is designed as an inner ring. The first ring can be arranged radially outwardly relative to the second ring. The meshing portion can then be arranged radially inwardly on the first ring. The respective pawl can, for example, be supported radially outwardly on the second ring. This can simplify the installation of the pawl.
[0024] A second aspect of the invention relates to a bicycle having a drive assembly according to the first aspect and a pedal crank shaft on which pedals are mounted, the pedals being designed to introduce drive forces into the drive assembly by the cyclist. The pedals are, for example, rotatably mounted on pedal cranks, which are permanently connected to the pedal crank shaft in a rotationally fixed manner. The respective advantages and further features are apparent from the description of the first aspect, wherein the design of the first aspect can also form the design of the second aspect and vice versa. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 It is explained how different engagement positions in the pawl freewheel mechanism can change the detection of the transmitted drive torque;
[0026] Figure 2 A first embodiment of a drive assembly for a bicycle is illustrated;
[0027] Figure 3 A second embodiment of a drive assembly for a bicycle is illustrated;
[0028] Figure 4 A third embodiment of a drive assembly for a bicycle is illustrated. DETAILED DESCRIPTION
[0029] Figure 1 A pawl freewheel mechanism with an inner ring 10 and an outer ring 12 is shown in detail. On the inner ring 10, a radial outer toothing with respective teeth extends along the entire circumference of the inner ring 10. The respective pawl 14 is rotatably supported on the inner side of the outer ring 12. In the locked state of the pawl freewheel mechanism, the respective pawl 14 engages with the nearest tooth of the teeth of the inner ring 10. This state is Figure 1 1 is illustrated with two possible relative positionings of the two rings 10 , 12 . Furthermore, a strain sensor 16 is shown which is fastened eccentrically to the end face of the inner ring 10 and by means of which the drive torque transmitted via the pawl freewheel in the locked state is measured.
[0030] The first relative positioning of the two rings 10, 12 and thus only the pawl 14 shown relative to the strain sensor 16 corresponds to the pawl 14 being positioned in a Figure 1This results in an orientation of the engagement of the pawl 14 relative to the strain sensor 16, which is illustrated by the arrow 18. The second relative positioning of the two rings 10, 12 and thus only the pawl 14 shown relative to the strain sensor 16 corresponds to the pawl 14 in Figure 1 This results in a changed orientation of the engagement of the pawl 14 relative to the strain sensor 16, which is indicated by the arrow 20. The angular spacing between the two arrows 18, 20 is indicated by the arrow 22 and corresponds to the extension of the two teeth of the toothing of the inner ring 10 in the circumferential direction.
[0031] The transmitted drive torque corresponds to a deformation or twisting of the inner ring 10 in the circumferential direction. The strain sensor 16 is designed as a strain gauge, which can only detect deformations along the axis. However, the transmitted drive torque also causes radial forces at the meshing. Depending on the relative positioning of the meshing and the strain sensor 16 to one another, the component of this radial force along the measuring axis of the strain sensor 16 is different. Therefore, interference variables are generated during the measurement, which are related to the relative positioning of the two rings 10, 12 to one another.
[0032] This effect is Figure 2 The first embodiment of the drive assembly for a bicycle is shown to be reduced. The drive assembly has a pawl freewheel mechanism 50. The pawl freewheel mechanism 50 has a hollow first ring 52 with a toothing and a hollow second ring 54, the first ring having a toothing, and the second ring having a plurality of pawls 56 movably supported thereon. The pawl freewheel mechanism 50 is in a locked state, in which two of the pawls 56 are in engagement with the toothing of the first ring 52. The first ring 52 is designed as an inner ring and the toothing is arranged radially on the outside at the periphery. The second ring 54 is designed as an outer ring, wherein the pawls 56 protrude radially inward from the second ring 54 to the toothing. The two rings 52, 54 are arranged coaxially. The pawls 56 are spring-prestressed with respect to the toothing.
[0033] The drive assembly has a sensor device which is designed to detect the deformation of the first ring 52 of the pawl freewheel mechanism 50 due to the applied drive force. The drive torque transmitted via the pawl freewheel mechanism 50 in the locked state can thus be measured. For this purpose, the sensor device has two sensors 58 which are designed as strain gauges.
[0034] The meshing of the first ring 52 has a first meshing area 60 and a second meshing area 62, which are spaced apart from one another in the circumferential direction by a first toothless area 64 and a second toothless area 66. As a result, variations in the relative positioning of the engagement of the pawl 56 with respect to the sensor 58 are limited to the extension in the circumferential direction of the meshing areas 60, 62. As a result, a possible influence of the relative positioning on the detected deformation can be limited compared to a continuously meshing inner ring.
[0035] The angular extension of the respective meshing regions 60, 62 is greater than or equal to the angular distance between two adjacent pawls in the pawl 56. Each of the meshing regions 60, 62 has a plurality of teeth arranged side by side in the circumferential direction. As a result, despite the presence of toothless regions 64, 66, the locking properties of the pawl freewheel mechanism 50 are independent of the positioning. The pawls 56 are arranged evenly distributed on the circumference of the second ring 54. The meshing regions 60, 62 are arranged on opposite sides of the first ring 52. The meshing regions 60, 62 are constructed identically. The toothless regions 64, 66 are constructed identically. This results in a symmetrical structure.
[0036] The sensor device of the first embodiment is designed to detect deformations of the first ring 52 in two areas opposite the meshing areas 60, 62. These areas correspond to the positioning of the sensor 58. The sensor 58 is arranged in the same peripheral area as the respectively adjacent toothless areas 64, 66.
[0037] Figure 3 A second embodiment of a drive assembly is shown which is similar to the first embodiment. Only the differences are explained.
[0038] In the second embodiment, the first ring 52 is left hollow in the region of the two toothless regions 64, 66. The sensor 58 is now arranged adjacent to the meshing regions 60, 62 and is therefore arranged in the same peripheral region as the respectively adjacent meshing region 60 or 62. The sensor device is therefore now designed to detect deformations of the first ring 52 in two regions respectively adjacent to at least one of the meshing regions 60, 62.
[0039] Figure 4 A third embodiment of a drive assembly is shown which is similar to the first embodiment. Only the differences are explained.
[0040] In the third embodiment, the number of pawls 56 is reduced. Instead of eight pawls 56, only four pawls 56 are provided. As a result, the pawl freewheel mechanism 50 is more cost-effective. In order to still achieve a positioning-independent locking characteristic of the pawl freewheel mechanism 50, the two meshing areas 60, 62 have a greater extension in the peripheral direction and therefore also have more teeth than in the first embodiment. The angular extension of the respective meshing areas 60, 62 is still greater than or equal to the angular distance between two adjacent pawls of the pawl 56. Therefore, the influence of interference variables on the measurement of the transmitted drive torque in the third embodiment is greater than the influence of interference variables or the influence of the relative positioning of the two rings 52, 54 in the first embodiment.
[0041] Reference numerals list
[0042] 10 Inner Ring
[0043] 12 Outer Ring
[0044] 14 pawls
[0045] 16 Strain Sensors
[0046] 18 Arrow
[0047] 20 arrows
[0048] 22 Arrows
[0049] 50 pawl free wheel mechanism
[0050] 52 First Ring
[0051] 54 Second Ring
[0052] 56 pawl
[0053] 58 Sensors
[0054] 60 meshing area
[0055] 62 meshing area
[0056] 64 toothless area
[0057] 66 toothless area
Claims
1. A drive assembly for a bicycle, the drive assembly comprising: a pawl-type freewheel mechanism (50), the pawl-type freewheel mechanism having a first ring (52) and a second ring (54), the first ring having a toothing portion, the second ring having at least one pawl (56) movably supported thereon, wherein: The pawl (56) engages with the meshing portion in a locked state; a sensor device is configured to detect deformation of a first ring (52) of the pawl-type freewheel mechanism (50) due to an applied driving force, wherein the first ring (52) has at least one meshing area (60, 62) and a toothless area (64, 66) in a circumferential direction.
2. The drive assembly according to claim 1, characterized in that: The first ring (52) has at least a first meshing area (60) and a second meshing area (62), which are spaced apart from one another in the peripheral direction by a first toothless area (64) and a second toothless area (66).
3. The drive assembly according to claim 1 or 2, characterized in that: The drive assembly has at least two pawls (56), wherein the angular extension of the respective engagement region (60, 62) is greater than or equal to the angular distance between the two pawls (56).
4. A drive assembly according to any one of the preceding claims, characterised in that The sensor device is designed to detect a deformation of the first ring (52) in a region in which a torque introduced by a cyclist at a pedal of a bicycle drive is already accumulated.
5. A drive assembly according to any one of the preceding claims, characterised in that The sensor device is designed to detect a deformation of the first ring (52) in at least one area adjacent to at least one of the meshing areas (60, 62).
6. A drive assembly according to any one of the preceding claims, characterised in that The sensor device is designed to detect a deformation of the first ring (52) in at least one region opposite at least one of the meshing regions (60, 62).
7. A drive assembly according to any one of the preceding claims, characterised in that The sensor device has at least one strain gauge as a sensor (58), which is arranged on the first ring (52).
8. A drive assembly according to any one of the preceding claims, characterised in that The sensor device is designed to determine a drive torque transmitted by the pawl freewheel (50) as a function of the deformation.
9. A drive assembly according to any one of the preceding claims, characterised in that The drive assembly has a greater number of pawls (56) than engagement areas (60, 62).
10. A drive assembly according to any one of the preceding claims, characterised in that The respective toothing region (60, 62) has a plurality of teeth which are arranged adjacent to one another in the circumferential direction.
11. A drive assembly according to any one of the preceding claims, characterised in that The first ring (52) is left hollow in the respective toothless region (64, 66).
12. A drive assembly according to any one of the preceding claims, characterised in that The first ring (52) is designed as an inner ring, and the second ring (54) is designed as an outer ring.
13. The drive assembly according to any one of claims 1 to 11, characterized in that: The first ring is configured as an outer ring, and the second ring is configured as an inner ring.
14. A bicycle having a drive assembly according to any one of the preceding claims and a pedal crankshaft having a pedal mounted on the pedal crankshaft, the pedal being designed to introduce a driving force into the drive assembly by a cyclist.