Patent Application
20110061490
1. Field of the Invention
The present invention relates to a hub and, more particularly, to a ratchet hub for a bicycle.
2. Description of the Related Art
A conventional hub for a bicycle in accordance with the prior art shown in
In assembly, the hub body 60 is connected to a wheel (not shown) of the bicycle, the shaft 70 is connected to a frame (not shown) of the bicycle, the freewheel 51 of the drive seat 50 meshes with and is driven by a chain (not shown) which is driven by a chainwheel (not shown) which is driven by a pedal (not shown) that is pedalled by a rider.
In operation, when the pedal is pedalled by the rider to move forward, the chainwheel is driven by the pedal to drive the chain which drives the freewheel 51 of the drive seat 50 so as to rotate the drive seat 50 forward relative to the shaft 70, so that each of the pawl members 53 is rotatable forward with the support base 52 of the drive seat 50. At this time, each of the pawl members 53 meshes with the oneway ratchet teeth 611 of the ratchet wheel 61 so that the ratchet wheel 61 is driven by the pawl members 53 to drive the hub body 60 to rotate relative to the shaft 70 so as to move the wheel forward. On the contrary, when the pedal is pedalled by the rider to move backward, the chainwheel is driven by the pedal to drive the chain which drives the freewheel 51 of the drive seat 50 so as to rotate the drive seat 50 backward relative to the shaft 70, so that each of the pawl members 53 is rotatable backward with the support base 52 of the drive seat 50. At this time, each of the pawl members 53 passes by the oneway ratchet teeth 611 of the ratchet wheel 61 so that the ratchet wheel 61 is released from the oneway ratchet teeth 611 of the ratchet wheel 61. Thus, the ratchet wheel 61 together with the hub body 60 is not driven by the drive seat 50, and the drive seat 50 idles in the backward direction.
However, when each of the pawl members 53 passes by the oneway ratchet teeth 611 of the ratchet wheel 61 during the backward rotation of the drive seat 50, each of the pawl members 53 touches the oneway ratchet teeth 611 of the ratchet wheel 61 to produce noise due to the friction, thereby easily causing an uncomfortable sensation to the rider. In addition, when the hub body 60 is rotated in the backward direction (e.g., when the wheel is rotated backward), the ratchet wheel 61 is also rotated in the backward direction. At this time, each of the pawl members 53 meshes with the oneway ratchet teeth 611 of the ratchet wheel 61 so that the ratchet wheel 61 drives each of the pawl members 53 to drive the drive seat 50 to rotate relative to the shaft 70 in the backward direction. Thus, the pedal is driven by the drive seat 50 to rotate backward so that the rider is easily hit and hurt by the pedal, thereby causing danger to the rider.
In accordance with the present invention, there is provided a hub for a bicycle, comprising a shaft, a hub body rotatably mounted on the shaft, a ratchet wheel secured in the hub body to drive the hub body to rotate relative to the shaft and having an inner wall provided with a plurality of oneway ratchet teeth, a drive seat rotatably mounted on the shaft and having an end face provided with a plurality of drive blocks each having a surface provided with an oblique driving slot, a support ring secured on the drive seat and protruding from the drive blocks, a rotation ring mounted on the support ring and having a periphery provided with a plurality of receiving slots, a plurality of pawl members each pivotally mounted in a respective one of the receiving slots of the rotation ring to releasably mesh with the oneway ratchet teeth of the ratchet wheel and each having a side provided with a guide post which is movable in the driving slot of a respective one of the drive blocks, a stop bushing mounted on the shaft, a limit ring mounted on the stop bushing and attached to the rotation ring to rotate in concert with the rotation ring and a damper mounted on the stop bushing and pressing the limit ring to damp a rotation movement of the rotation ring.
The primary objective of the present invention is to provide a normally closed bicycle hub that will not drive the pedal and will not produce noise when the hub is rotated in the backward direction.
According to the primary objective of the present invention, when the drive seat is rotated backward by the pedal, each of the pawl members is retracted into the respective receiving slot of the rotation ring to disengage the oneway ratchet teeth of the ratchet wheel, so that each of the pawl members is spaced from and will not touch the ratchet wheel when the pedal is driven backward to prevent from producing a noise when the pedal is driven backward.
According to another objective of the present invention, each of the pawl members is separated from the ratchet wheel when the pedal is driven backward so that the hub body is separated from the drive seat, and a backward rotation of the hub body will not drive the drive seat and the pedal to prevent the pedal from being driven backward when the hub body is rotated backward and to protect a rider's safety.
Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.
Referring to the drawings and initially to
The drive seat 10 has an inner portion provided with a stepped shaft hole 11 rotatably mounted on the shaft 12 by at least one bearing 101. The end face of the drive seat 10 is provided with a plurality of elongate limit grooves 131 located between the drive blocks 13 respectively. The drive seat 10 has an annular outer surface provided with a plurality of axially extending fixing channels 16 for mounting at least one freewheel (not shown). The driving slot 14 of each of the drive blocks 13 has an outer side 142 and an inner side 141, wherein the inner side 141 is located between the outer side 142 and the shaft 12, and the outer side 142 is located between the inner side 210 and the oneway ratchet teeth 42 of the ratchet wheel 43.
Thus, the drive seat 10 is rotatable between a first position as shown in
The rotation ring 21 has an inner portion provided with a through hole 211 rotatably mounted on the support ring 15. Each of the receiving slots 212 of the rotation ring 21 has an oblique shape and has an end provided with a pivot hole 213. The rotation ring 21 is provided with a plurality of positioning pieces 216 directed toward the limit ring 30. The rotation ring 21 is provided with a plurality of limit ribs 214 movable in the limit grooves 131 of the drive seat 10 respectively and limited between the drive blocks 13 of the drive seat 10 respectively. The rotation ring 21 has an outer surface provided with an annular retaining groove 215 to retain the elastic member 23. The retaining groove 215 of the rotation ring 21 has a bottom wall provided with a fixing hole 217.
Each of the pawl members 22 has a first end provided with an enlarged pivot fulcrum 221 pivotally mounted in the pivot hole 213 of the respective receiving slot 212 of the rotation ring 21 and a second end provided with a locking detent 224 which is movable with the guide post 222 to mesh with or detach from the oneway ratchet teeth 42 of the ratchet wheel 43. The second end of each of the pawl members 22 is provided with the guide post 222. Each of the pawl members 22 has an outer surface provided with an elongate limit groove 223 to receive the elastic member 23.
The elastic member 23 has a substantially C-shaped profile and has a side provided with an opening 231. The elastic member 23 has an end provided with a bent fixing portion 232 inserted into the fixing hole 217 of the rotation ring 21 to fix the elastic member 23 onto the rotation ring 21.
The limit ring 30 has an inner portion provided with a stepped receiving hole 31 mounted on the stop bushing 121 to receive the damper 33. The limit ring 30 abuts the rotation ring 21 and has a periphery provided with a plurality of positioning recesses 32 to fix the positioning pieces 216 of the rotation ring 21 so that the limit ring 30 is rotatable in concert with the rotation ring 21. The limit ring 30 is located between the support ring 15 and the stop bushing 121.
The damper 33 is secured in the receiving hole 31 of the limit ring 30 and is located between the limit ring 30 and the stop bushing 121. The damper 33 is made of a resilient material and has an inner wall 330 closely fit onto the stop bushing 121 and an outer wall 332 pressing the limit ring 30 to provide a damping force to a rotation movement of the limit ring 30.
The hub body 40 has an inner portion provided with a stepped receiving space 41 rotatably mounted on the shaft 12 by a bearing 401. The receiving space 41 of the hub body 40 receives the drive blocks 13 of the drive seat 10, the rotation ring 21, the limit ring 30 and the stop bushing 121. The ratchet wheel 43 is secured in the receiving space 41 of the hub body 40 and surrounds the rotation ring 21 and the pawl members 22.
The stop bushing 121 is inserted into the shaft hole 11 of the drive seat 10. The stop bushing 121 is located between the bearing 101 of the drive seat 10 and the bearing 401 of the hub body 40 so that the stop bushing 121 is located between the drive seat 10 and the hub body 40.
In assembly, the hub body 40 is connected to a wheel (not shown) of the bicycle, the shaft 12 is connected to a frame (not shown) of the bicycle, and the freewheel on the drive seat 10 meshes with and is driven by a chain (not shown) which is driven by a chainwheel (not shown) which is driven by a pedal (not shown) that is pedalled by a rider. Thus, each of the pawl members 22 is initially pressed inward by the elastic member 23 to disengage the oneway ratchet teeth 42 of the ratchet wheel 43, so that the ratchet wheel 43 is released from and non-rotatable with the drive seat 10 at a normal state. At this time, the guide post 222 of each of the pawl members 22 is located at the inner side 141 of the driving slot 14 of the respective drive block 13 as shown in
In operation, referring to
On the contrary, when the pedal is pedalled by the rider to move backward, the chainwheel is driven by the pedal to drive the chain which drives the freewheel of the drive seat 10 so as to rotate the drive seat 10 backward relative to the shaft 12, so that the drive seat 10 is rotated backward relative to the shaft 12, and the drive blocks 13 of the drive seat 10 are also rotated backward relative to the shaft 12 as shown in
Thus, when the drive seat 10 is rotated backward by the pedal, each of the pawl members 22 is retracted into the respective receiving slot 212 of the rotation ring 21, and the locking detent 224 of each of the pawl members 22 disengages the oneway ratchet teeth 42 of the ratchet wheel 43 constantly, so that each of the pawl members 22 will not touch the ratchet wheel 43 when the pedal is driven backward to prevent from producing a noise when the pedal is driven backward. In addition, each of the pawl members 22 is separated from the ratchet wheel 43 when the pedal is driven backward so that the hub body 40 is separated from the drive seat 10, and a backward rotation of the hub body 40 will not drive the drive seat 10 and the pedal to prevent the pedal from being driven when the hub body 40 is rotated backward.
Referring to
Referring to
Accordingly, when the drive seat 10 is rotated backward by the pedal, each of the pawl members 22 is retracted into the respective receiving slot 212 of the rotation ring 21 to disengage the oneway ratchet teeth 42 of the ratchet wheel 43, so that each of the pawl members 22 is spaced from and will not touch the ratchet wheel 43 when the pedal is driven backward to prevent from producing a noise when the pedal is driven backward. In addition, each of the pawl members 22 is separated from the ratchet wheel 43 when the pedal is driven backward so that the hub body 40 is separated from the drive seat 10, and a backward rotation of the hub body 40 will not drive the drive seat 10 and the pedal to prevent the pedal from being driven backward when the hub body 40 is rotated backward and to protect a rider's safety.
Although the invention has been explained in relation to its preferred embodiment(s) as mentioned above, it is to be understood that many other possible modifications and variations can be made without departing from the scope of the present invention. It is, therefore, contemplated that the appended claim or claims will cover such modifications and variations that fall within the true scope of the invention.
