TWM675131U - Wheel power mechanism and electric assisted bicycle - Google Patents

Abstract

(無)

Description

Wheel power mechanism and electric power-assisted bicycle

The present disclosure relates to a power mechanism and a bicycle, and more particularly to a wheel power mechanism and an electric power-assisted bicycle.

In recent years, with the prevalence of environmental protection and exercise, bicycle usage has increased significantly. However, ordinary bicycles are propelled by human pedaling, so it is difficult for users to bear the physical load on uphill sections.

In response to this, some have developed electric-assisted bicycles that can be equipped with a wheel drive mechanism including an electric motor to provide assistance when the user pedals, thereby reducing the burden on the user. The wheel drive mechanism may include a hub housing, an electric motor, a freehub, and a clutch. In one drive mode, the motor drives the clutch to rotate the hub housing. In another drive mode, the freehub drives the hub housing, and an axial clutch structure is included between the freehub and the hub housing, allowing them to engage and disengage when there is a difference in their rotational speeds.

However, the conventional axial clutch structure includes a pawl, which is easily affected by eccentricity and causes unstable engagement between the freewheel base and the hub shell, so there is still room for improvement.

To solve the above problems, the present disclosure provides a wheel power mechanism and an electric power-assisted bicycle, which can improve the stability of the engagement between the freehub and the hub shell through structural configuration.

According to one embodiment of the present disclosure, a wheel power mechanism is provided, comprising a center shaft, a freewheel body, an axial clutch structure, and a hub shell. The center shaft has an axis. The freewheel body is mounted on one end of the center shaft. The axial clutch structure comprises a first axial ratchet and a second axial ratchet. The first axial ratchet is movably mounted on the center shaft along the axis and is rotationally coupled to the freewheel body. The first axial ratchet comprises a plurality of first face teeth. The second axial ratchet is mounted on the center shaft and comprises a plurality of second face teeth corresponding to the plurality of first face teeth. The hub shell is mounted on the center shaft and is rotationally coupled to the second axial ratchet. The plurality of first face teeth mesh with the plurality of second face teeth, and a rotational force is transmitted to the hub housing via the freehub, the first axial ratchet, and the second axial ratchet, causing the hub housing to rotate. When a hub rotational speed of the hub housing is greater than a freehub rotational speed of the freehub, the plurality of first face teeth and the plurality of second face teeth disengage from each other, causing the first axial ratchet and the second axial ratchet to become uncoupled.

The wheel drive mechanism according to the aforementioned embodiment may further include a motor rotor and a clutch. The motor rotor is mounted on a central axle and positioned within the hub housing. The clutch connects the motor rotor and the hub housing. Power from the motor rotor is transmitted to the hub housing via the clutch, causing the hub housing to rotate.

According to the wheel power mechanism of the aforementioned embodiment, the freewheel base may include a freewheel base tube, a freewheel base bearing, and a plurality of recesses. The freewheel base tube surrounds the center shaft. The freewheel base bearing is sleeved on the center shaft and located inside the freewheel base tube. The aforementioned plurality of recesses are arranged at one end of the freewheel base tube. The first axial ratchet includes a plurality of first radial protrusions that engage with the aforementioned plurality of recesses, and the axial clutch structure further includes an elastic member, which is sleeved on the center shaft and located inside the freewheel base tube, and the elastic member abuts between the first axial ratchet and the freewheel base bearing.

In the wheel power mechanism according to the aforementioned embodiment, the length of each recess may be greater than the length of each first radial tooth. When the first axial ratchet is pushed toward the freewheel base bearing by the second axial ratchet, each first radial tooth slides within each recess.

The wheel power mechanism according to the aforementioned embodiment may further include a connecting ring, which is sleeved on the central axis and locked to the hub shell. The connecting ring includes a plurality of grooves. The second axial ratchet is located in the connecting ring and includes a plurality of second radial protrusions that engage with the aforementioned plurality of grooves.

According to another embodiment of the present disclosure, an electric power-assisted bicycle is provided, comprising a frame and two wheels. The two wheels are mounted on the frame, and one of the wheels comprises a wheel power mechanism according to the aforementioned embodiment.

The electric-assisted bicycle according to the aforementioned embodiment may further include a motor rotor and a clutch. The motor rotor is mounted on the central axle and positioned within the hub housing. The clutch connects the motor rotor and the hub housing. Power from the motor rotor is transmitted to the hub housing via the clutch, causing the hub housing to rotate.

In the electric power-assisted bicycle according to the aforementioned embodiment, the freewheel base may include a freewheel base tube, a freewheel base bearing, and a plurality of recesses. The freewheel base tube surrounds a central axis. The freewheel base bearing is sleeved on the central axis and located within the freewheel base tube. The aforementioned plurality of recesses are disposed at one end of the freewheel base tube. The first axial ratchet includes a plurality of first radial protrusions that engage with the aforementioned plurality of recesses, and the axial clutch structure further includes an elastic member that is sleeved on the central axis and located within the freewheel base tube, and the elastic member abuts between the first axial ratchet and the freewheel base bearing.

In the electric power-assisted bicycle according to the aforementioned embodiment, the length of each recess may be greater than the length of each first radial tooth. When the first axial ratchet is pushed toward the freewheel base bearing by the second axial ratchet, each first radial tooth slides within each recess.

The electric power-assisted bicycle according to the above embodiment may further include a connecting ring, which is sleeved on the central axis and locked to the hub shell. The connecting ring includes a plurality of grooves. The second axial ratchet is located in the connecting ring and includes a plurality of second radial teeth that engage with the aforementioned plurality of grooves.

The following describes embodiments of the present disclosure with reference to the accompanying drawings. For clarity, numerous practical details are included in the following description. However, the reader should understand that these practical details should not be construed as limiting the present disclosure. In other words, these practical details are not essential to some embodiments of the present disclosure. Furthermore, to simplify the drawings, some commonly used structures and components are depicted in simplified schematic form; and repeated components may be represented using the same or similar numbers.

Furthermore, terms such as "first," "second," and "third" are used herein to describe different elements or components and do not limit the elements/components themselves. Therefore, a first element/component may also be referred to as a second element/component. Furthermore, the combinations of elements/components/mechanisms/modules described herein are not generally known, conventional, or familiar in the art. Whether or not a component/component/mechanism/module is known should not be used to determine whether its combination is easily accomplished by one of ordinary skill in the art.

Referring to Figures 1 and 2, Figure 1 illustrates a perspective view of a wheel drive mechanism 100 according to an embodiment of the present disclosure, while Figure 2 illustrates an exploded view of the wheel drive mechanism 100 of the embodiment of Figure 1. The wheel drive mechanism 100 includes a center shaft 110, a freewheel body 120, an axial clutch structure 130, and a hub shell 140.

The center shaft 110 has an axis X1 (shown in FIG. 3 ). The freehub body 120 is mounted on one end of the center shaft 110. The axial clutch structure 130 includes a first axial ratchet 131 and a second axial ratchet 132. The first axial ratchet 131 is movably mounted on the center shaft 110 along the axis X1 and is rotationally coupled to the freehub body 120. The first axial ratchet 131 includes a plurality of first face teeth 1311. The second axial ratchet 132 is mounted on the center shaft 110 and includes a plurality of second face teeth 1321 corresponding to the plurality of first face teeth 1311. The hub housing 140 is mounted on the center shaft 110 and is rotationally coupled to the second axial ratchet 132. The plurality of first face teeth 1311 and the plurality of second face teeth 1321 engage with each other, and a rotational force is transmitted to the hub housing 140 via the freewheel base 120, the first axial ratchet 131, and the second axial ratchet 132, causing the hub housing 140 to rotate. When a hub rotational speed of the hub housing 140 is greater than a freewheel base rotational speed of the freewheel base 120, the plurality of first face teeth 1311 and the plurality of second face teeth 1321 disengage from each other, causing the first axial ratchet 131 and the second axial ratchet 132 to become uncoupled.

Thus, the coordination between the first face teeth 1311 and the second face teeth 1321 can avoid the problem of unstable engagement caused by eccentricity, and the larger contact area can reduce stress concentration, thereby improving the stability and service life of the wheel power mechanism 100.

The central shaft 110 can be a hollow rod or a solid rod. The wheel drive mechanism 100 can further include two fixing sleeves 191 and 192, which are respectively mounted on the two ends of the central shaft 110. The fixing sleeves 191 and 192 can be respectively fixed to the two fixing portions of the rear fork of an electric power-assisted bicycle (such as the electric power-assisted bicycle 200 in Figure 5). When necessary, the central shaft 110 can be withdrawn along the axis X1, allowing the fixing sleeves 191 and 192 to drive the rear fork to separate from the other components of the wheel drive mechanism 100, thereby facilitating maintenance or replacement.

Please refer to Figures 3 and 4, together with Figure 2. Figure 3 illustrates a partial cross-sectional schematic diagram of the wheel drive mechanism 100 of the embodiment of Figure 1, and Figure 4 illustrates another partial cross-sectional schematic diagram of the wheel drive mechanism 100 of the embodiment of Figure 1. The hub housing 140 is hollow and cylindrical and is connected to the spokes, which in turn are connected to the rims, upon which the tires are mounted. The wheel power mechanism 100 may further include a connecting ring 160 and a protrusion 150. The connecting ring 160 is mounted on the center axle 110 and positioned within the hub shell 140. It is locked to an end plate 141 of the hub shell 140 facing the freewheel body 120. The connecting ring 160 is an annular plate and includes an axle hole and a plurality of grooves 161. The axle hole is configured to receive the center axle 110, and the grooves 161 may be formed around the wall of the axle hole. The protrusion 150 may be mounted on the center axle 110 and extend through the axle hole.

The freewheel body 120 can be positioned along axis X1 between one of the end plates 141 and a fixed portion of the hub housing 140. The freewheel body 120 is rotated by the chain. Specifically, the freewheel body 120 can include a freewheel body tube 121, a freewheel body bearing 122, and a plurality of recesses 123. The freewheel body tube 121 can surround the center shaft 110. The freewheel body bearing 122 is sleeved around the center shaft 110 and positioned within the freewheel body tube 121. The plurality of recesses 123 are provided at one end of the freewheel body tube 121.

As shown in Figure 3, the protrusion 150 is located between the inner circumference of the freewheel base tube 121 and the outer circumference of the center shaft 110. Two freewheel base bearings 122 are spaced apart within the freewheel base tube 121 to support it. The recesses 123 are located closer to the end plate 141 than the freewheel base bearings 122. Each recess 123 is formed by reducing the radial thickness of the freewheel base tube 121.

The first axial ratchet 131 can be housed within the freehub body tube 121 and adjacent to the end plate 141. The first axial ratchet 131 can include a plurality of first radial teeth 1312 that engage with the plurality of recesses 123. Specifically, the first axial ratchet 131 can include a first annular body (not shown). The first face teeth 1311 can be located on a surface of the first annular body facing the end plate 141, and the first radial teeth 1312 can be located on the outer circumference of the first annular body. The first radial teeth 1312 can protrude into and engage with the recesses 123, thereby rotationally coupling with the freehub body 120.

Furthermore, the recess length D1 of each recess 123 can be greater than the tooth length D2 of each first radial tooth 1312. Therefore, when the first axial ratchet 131 is pushed toward the freewheel base bearing 122 by the second axial ratchet 132, each first radial tooth 1312 can slide within each recess 123. Specifically, the first axial ratchet 131 is movably received within the freewheel base tube 121 and rotationally coupled thereto through engagement between the first radial teeth 1312 and the recess 123. The first axial ratchet 131 can be pushed and moved along the axis X1 between an engaged position and a disengaged position. Therefore, by configuring the recess length D1 to be greater than the protruding tooth length D2, the first axial ratchet 131 can be guided to move relative to the freewheel base 120. Regardless of whether the first axial ratchet 131 is in the engaged position or the disengaged position, it can be rotationally linked to the freewheel base 120.

The second axial ratchet 132 is located within the connecting ring 160 and has a structure similar to that of the first axial ratchet 131. Therefore, the second axial ratchet 132 includes a second annular body (not shown) and a plurality of second radial teeth 1322. The second face teeth 1321 can be located on a surface of the second annular body facing the first axial ratchet 131, and the second radial teeth 1322 can be located on the outer circumference of the second annular body. Specifically, the second axial ratchet 132 can be located in the axial hole of the connecting ring 160, so that the second radial protrusion 1322 can protrude into the groove 161 and engage with the groove 161, thereby limiting the second axial ratchet 132 and the connecting ring 160, and indirectly limiting the hub shell 140.

The axial clutch structure 130 may further include an elastic member 133. The elastic member 133 is sleeved around the center shaft 110 and positioned within the freehub body tube 121. The elastic member 133 abuts between the first axial ratchet 131 and the freehub body bearing 122. In other words, the elastic member 133 pushes the first axial ratchet 131 toward the second axial ratchet 132, causing the first and second axial ratchet 131 and 132 to engage.

The wheel power mechanism 100 may further include a motor rotor (not shown) and a clutch 170. The motor rotor is mounted on the center shaft 110 and located within the hub housing 140. The clutch 170 connects the motor rotor and the hub housing 140. Power from the motor rotor is transmitted to the hub housing 140 via the clutch 170, causing the hub housing 140 to rotate. Specifically, the wheel power mechanism 100 may include a motor 180 mounted on the center shaft 110. The motor 180 may include a motor rotor, a motor stator, and a reduction gear assembly. The reduction gear assembly may connect the motor rotor and the clutch 170. In this way, when the motor stator is energized, the motor rotor rotates, which in turn drives the reduction gear assembly and the hub housing 140. In this embodiment, the clutch 170 may include an outer roller ring, an inner roller ring, and multiple rollers, needle rollers, or ball rollers. The outer roller ring is configured to rotate in a single direction relative to the inner roller ring, thereby enabling the motor rotor and hub housing 140 to rotate in a single direction. Since the structures of the motor 180 and clutch 170 are not the focus of this disclosure, their details will not be described here. The figures also simplify the structures of the motor 180 and clutch 170, but this does not limit this disclosure. In other embodiments, a clutch may also connect the motor rotor and the hub end plate.

As shown in FIG3 , the first axial ratchet 131 is in the engaged position and engages the second axial ratchet 132. The user can pedal to drive the freehub 120, which in turn rotates the connecting ring 160 and the hub housing 140. The bicycle may also be equipped with a pedaling sensor or a torque sensor to sense pedaling and the force applied by the user, thereby driving the motor 180 to provide corresponding assistance. As shown in FIG4 , when the rotational speed of the hub of the hub housing 140 is greater than the rotational speed of the freewheel body 120, the first axial ratchet 131 can be moved to a disengaged position, causing the first face tooth 1311 and the second face tooth 1321 to disengage from each other. In this way, even if the assist force is increased and the hub rotational speed of the hub housing 140 is too fast, it will not affect the user's pedaling to drive the freewheel body 120.

Please refer to FIG. 5 , which illustrates a side view of an electric-assisted bicycle 200 according to another embodiment of the present disclosure. Electric-assisted bicycle 200 may include a frame 210 and two wheels 220 and 230. Wheels 220 and 230 are mounted on frame 210, and wheel 230 includes a wheel drive mechanism 231. The structure of wheel drive mechanism 231 may be similar to wheel drive mechanism 100 shown in FIG. 1 through FIG. 4 , and details thereof will not be repeated here.

Although the present disclosure has been disclosed above with reference to the embodiments, they are not intended to limit the present disclosure. Anyone skilled in the art may make various changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the scope of protection of the present disclosure shall be determined by the scope of the attached patent application.

100, 231: Wheel drive mechanism 110: Center shaft 120: Freewheel body 121: Freewheel body tube 122: Freewheel body bearing 123: Recess 130: Axial clutch structure 131: First axial ratchet 1311: First face tooth 1312: First radial protrusion 132: Second axial ratchet 1321: Second face tooth 1322: Second radial protrusion 133: Elastic member 140: Hub housing 141: End plate 150: Protrusion 160: Connecting ring 161: Groove 170: Clutch 180: Motor 191, 192: Fixing sleeve 200: Electric power-assisted bicycle 210: Frame 220,230: Wheel D1: Recess length D2: Tooth length X1: Axis

Figure 1 is a schematic three-dimensional diagram of a wheel power mechanism according to an embodiment of the present disclosure; Figure 2 is an exploded schematic diagram of the wheel power mechanism of the embodiment of Figure 1; Figure 3 is a schematic cross-sectional diagram of a portion of the wheel power mechanism of the embodiment of Figure 1; Figure 4 is a schematic cross-sectional diagram of another portion of the wheel power mechanism of the embodiment of Figure 1; and Figure 5 is a schematic side view of an electric power-assisted bicycle according to another embodiment of the present disclosure.

100: Wheel power mechanism

110: Center axis

120: Tower Base

130: Axial clutch structure

131: First axial ratchet

1311: First tooth

1312: First radial tooth

132: Second axial ratchet

1321: Second tooth

1322: Second radial tooth

133: Elastic parts

140: Hub housing

141: End Plate

150: Protrusion

191,192: Fixed sleeve

Claims (10)

A wheel drive mechanism includes: a center shaft having an axis; a freehub mounted on one end of the center shaft; an axial clutch structure including: a first axial ratchet movably mounted on the center shaft along the axis and rotationally coupled to the freehub, the first axial ratchet including a plurality of first teeth; and a second axial ratchet mounted on the center shaft and including a plurality of second teeth corresponding to the first teeth; and a hub housing mounted on the center shaft and rotationally coupled to the second axial ratchet. The first face teeth engage with the second face teeth, and a rotational force is transmitted to the hub housing via the freehub, the first axial ratchet, and the second axial ratchet, causing the hub housing to rotate. When a hub rotational speed of the hub housing is greater than a freehub rotational speed of the freehub, the first face teeth and the second face teeth disengage from each other, causing the first axial ratchet and the second axial ratchet to stop coupling. The wheel power mechanism as described in claim 1 further includes: a motor rotor, which is mounted on the central axis and located inside the hub shell; and a clutch, which connects the motor rotor and the hub shell; wherein a power of the motor rotor is transmitted to the hub shell through the clutch, causing the hub shell to rotate. A wheel power mechanism as described in claim 1, wherein the freewheel base includes: a freewheel base tube portion, which surrounds the center shaft; a freewheel base bearing, which is sleeved on the center shaft and located in the freewheel base tube portion; and a plurality of recesses, which are arranged at one end of the freewheel base tube portion; wherein the first axial ratchet includes a plurality of first radial protrusions that engage with the recesses, and the axial clutch structure further includes an elastic member, which is sleeved on the center shaft and located in the freewheel base tube portion, and the elastic member abuts between the first axial ratchet and the freewheel base bearing. As described in claim 3, the wheel power mechanism, wherein the length of each of the recesses is greater than the length of each of the first radial teeth, and when the first axial ratchet is pushed by the second axial ratchet to move toward the tower base bearing, each of the first radial teeth slides in each of the recesses. The wheel power mechanism as described in claim 1 further includes a connecting ring, which is sleeved on the central axis and locked with the hub shell, the connecting ring includes a plurality of grooves, and the second axial ratchet is located in the connecting ring and includes a plurality of second radial teeth that engage with the grooves. An electric power-assisted bicycle comprises: a frame; and two wheels, disposed on the frame, one of the wheels comprising a wheel power mechanism as described in claim 1. The electric power-assisted bicycle as described in claim 6 further includes: a motor rotor mounted on the central axis and located inside the hub shell; and a clutch connecting the motor rotor and the hub shell; wherein a power of the motor rotor is transmitted to the hub shell through the clutch, causing the hub shell to rotate. An electric power-assisted bicycle as described in claim 7, wherein the freewheel base comprises: a freewheel base tube portion surrounding the center shaft; a freewheel base bearing sleeved on the center shaft and located in the freewheel base tube portion; and a plurality of recesses provided at one end of the freewheel base tube portion; wherein the first axial ratchet comprises a plurality of first radial protrusions engaged with the recesses, and the axial clutch structure further comprises an elastic member sleeved on the center shaft and located in the freewheel base tube portion, and the elastic member abuts between the first axial ratchet and the freewheel base bearing. As described in claim 8, the electric power-assisted bicycle, wherein the length of each of the recesses is greater than the length of each of the first radial teeth, and when the first axial ratchet is pushed by the second axial ratchet to move toward the tower base bearing, each of the first radial teeth slides in each of the recesses. The electric power-assisted bicycle as described in claim 6 further includes a connecting ring, which is sleeved on the central axis and locked with the hub shell, the connecting ring includes a plurality of grooves, and the second axial ratchet is located in the connecting ring and includes a plurality of second radial teeth that engage with the grooves.