JP2005324603A - Transmission for bicycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a built-in type transmission for a bicycle having simple structure and mounted on various kinds of bicycles in a versatile manner. <P>SOLUTION: A low speed rotating body 1 fixed to a crankshaft 51 rotated by tread force of a pedal and middle speed rotating body 2 and high speed rotating body 3 freely rotatable in relation to the crankshaft 51 are successively arranged side by side. This transmission is provided with a fixing member 6 which does not rotate in relation to a frame 53. A bevel gear 11 journaled to the low speed rotating body 1 is engaged with the high speed rotating body 3 and the fixing member 6. A bevel gear 14 journaled to the middle speed rotating body 2 is engaged with the high speed rotating body 3 and the low speed rotating body 1. Ratchet pawls 21, 22 and 23 are provided on each of outer peripheral parts of the low speed rotating body 1, the middle speed rotating body 2 and the high speed rotating body 3. According to advancing and retreating of a switching member 25 operable from the outside, a transmission is performed by switching engagement/disengagement of the rachet pawls 23 and 22 and a ratchet tooth 24 at the inside of a sprocket 4. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a transmission provided on a crankshaft portion of a bicycle using a bevel gear mechanism.

  In general, as a bicycle transmission that adjusts the pedal depression load according to the gradient of the road surface on which it travels, sports bicycles are equipped with exterior types that change chains on multiple stages of sprockets. In many cases, bicycles for street riding are equipped with an interior type using a planetary gear mechanism that can perform a shifting operation easily and smoothly.

  As this interior transmission, the following Patent Document 1 includes a gear case incorporated in a frame and a crankshaft that is rotatable by a pedaling force of a pedal, a rotatable rotating body is provided, and a sprocket is fixed to one side thereof, A plurality of planetary gears are pivotally supported on a carrier that rotates integrally with the crankshaft, and rotatable sun gears are engaged with the inner sides of the planetary gears. A ratchet mechanism that absorbs the rotational speed difference between the carrier and the driven rotating body is provided by meshing the internal gear provided on the body, and the switching operation of the one-way clutch that allows / blocks the rotation of the sun gear at each stage is performed. Thus, there is described a gear that changes speed by switching an internal gear that is accelerated with respect to the crankshaft.

  In Patent Document 2 below, a sprocket and a large-diameter sun gear are integrally formed on one side and the other side so as to be rotatable with respect to a gear case fixed to a frame and a crankshaft rotating by a pedaling force. The planetary gear is supported by a carrier that rotates integrally with the crankshaft, and a small-diameter sun gear that can rotate relative to the crankshaft is engaged inside the large-diameter step of the planetary gear. The planetary gear is meshed with the large-diameter sun gear inside the small-diameter step, and the planetary gear is meshed with the internal gear on the outside of each planetary gear to absorb the difference in rotational speed between the small-diameter sun gear and the driven rotor. A ratchet mechanism is provided to change the speed of the sun gear that is accelerated relative to the crankshaft by switching the one-way clutch that allows / blocks rotation of the internal gear of each stage relative to the gear case. Umono have been described.

JP-A-6-263081 JP-A-6-298153

  However, the transmission as described above has a problem that the structure is complicated because a large number of parts constituting a one-way clutch corresponding to the ratchet mechanism, the sun gear or the internal gear of each stage are required.

  Further, since the sprocket for hanging the chain is located on the side of the gear case, there is a problem that it cannot be attached later to a bicycle without a transmission.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an internal bicycle transmission that has a simple structure and is universally attached to various bicycles.

  In order to solve the above-mentioned problems, the present invention sequentially arranges a low-speed rotating body fixed to a crankshaft that is rotated by a pedaling force, a medium-speed rotating body that can freely rotate with respect to the crankshaft, and a high-speed rotating body. A fixing member that does not rotate with respect to the frame, a bevel gear whose axis is orthogonal to the crankshaft is axially attached to the low-speed rotating body, and the bevel gear is engaged with an annular bevel tooth formed on the high-speed rotating body and the fixing member. Also, a bevel gear whose axis is perpendicular to the crankshaft is axially attached to the medium-speed rotating body, and this bevel gear is meshed with an annular bevel formed on a high-speed rotating body and a low-speed rotating body. The ratchet pawl is provided on the outer periphery of the body and the high-speed rotating body, the ratchet teeth that engage with the ratchet pawl are formed inside the driven annulus integrated with the sprocket, and a switching member that can be operated from the outside is provided. , This cut The advance and retreat motions of the member, than it was to shift by switching engaging and disengaging the ratchet pawl and the ratchet teeth of the high speed rotation body and the medium-speed rotating body.

  In the bicycle transmission according to the present invention, the low-speed rotator, the medium-speed rotator, and the high-speed rotator are always rotating, and the ratchet pawls of the high-speed rotator and the medium-speed rotator are driven by the switching member. Because the gears are engaged with and disengaged from the ratchet teeth, there is no need to provide multi-stage planetary gears, sun gears and internal gears to switch their transmission paths, simplifying the structure and reducing manufacturing costs, Reliability is improved, and it is compact and compatible with various bicycles.

  A bicycle transmission according to an embodiment of the present invention will be described below with reference to FIGS.

  As shown in FIGS. 1 to 4, the transmission includes a disk-shaped low-speed rotating body 1, a medium-speed rotating body 2, and a high-speed rotating body around a crankshaft 51 that is rotated by a pedal effort when attached to a bicycle. The rotating body 3 is configured to be sequentially arranged from the crank arm 52 side to the frame 53 side.

  The boss portion on the inner peripheral side of the low-speed rotating body 1 extends toward the frame 53 side, and the high-speed rotating body 3 has an intermediate portion and an inner peripheral portion entering the low-speed rotating body 1 side in a stepped manner. The low-speed rotator 1 is fixed to the crankshaft 51 via the boss portion of the crank arm 52, and the medium-speed rotator 2 and the high-speed rotator 3 are freely rotatable with respect to the crankshaft 51. .

  On the outer peripheral side of the low-speed rotating body 1, the medium-speed rotating body 2, and the high-speed rotating body 3, a driven ring 5 integrated with the sprocket 4 is provided on the inner diameter side of the sprocket 4 to which the chain is hooked. Is held rotatably with respect to the low-speed rotating body 1 and the high-speed rotating body 3 through a bearing sandwiched between peripheral flanges. A fixing member 6 that does not rotate is provided on the frame 53 side.

  Two bevel gears 11 whose axis is orthogonal to the crankshaft 51 are attached to the boss portion on the inner peripheral side of the low-speed rotating body 1 so as to face each other. The bevel gear 11 is connected to the inner peripheral portion of the high-speed rotating body 3. It meshes with annular bevel teeth 12 and 13 respectively formed on the end wall portion of the fixing member 6.

  Two bevel gears 14 whose axis is orthogonal to the crankshaft 51 are also attached to the inner peripheral portion of the medium-speed rotating body 2 so as to face each other. The bevel gear 14 is connected to the intermediate portion of the high-speed rotating body 3 and the low-speed rotating body. 1 is engaged with annular bevel teeth 15 and 16 respectively formed in the intermediate portion.

  Four ratchet claws 21, 22, and 23 are provided on the outer peripheral portions of the low-speed rotator 1, the medium-speed rotator 2, and the high-speed rotator 3, and the tips of these ratchet claws 21, 22, and 23 are driven. It engages with ratchet teeth 24 formed on the inner diameter side of the ring body 5.

  A switching member 25 that moves forward and backward with respect to the ratchet claws 23, 22 is provided on the medium-speed rotating body 2 side of the high-speed rotating body 3, and its leg portion protrudes to the inner peripheral side through the through hole of the high-speed rotating body 3. ing. The switching member 25 is biased by a spring in a direction away from the ratchet claw 23, and the annular portion 26 provided at the tip of the switching member 25 is inclined toward the ratchet claw 23.

  A switching screw 27 having a large lead is engraved on the outer periphery of the fixing member 6, and a switching ring 28 that is screwed to the switching screw 27 is operated by a wire operation from an operation lever attached near the handle or the pedal. , And moves in the axial direction of the crankshaft 51 to advance and retract the switching member 25.

  In such a transmission, when the crankshaft 51 is rotated, the low-speed rotating body 1 rotates at the same speed as the crankshaft 51, and the high-speed rotating body 3 is rotated by 2 of the crankshaft 51 by the action of the bevel gear 11. The medium-speed rotating body 2 rotates at a speed that is 1.5 times the speed of the crankshaft 51 by the action of the bevel gear 14.

  As shown in FIG. 1, when the switching member 25 is in the most retracted position, the switching member 25 is separated from the ratchet claw 23 of the high-speed rotating body 3, so that the ratchet claw 23 biased in the protruding direction The engaged state with the ratchet teeth 24 is maintained, and the rotation of the high speed rotating body 3 is transmitted to the sprocket 4 via the ratchet pawl 23.

  At this time, relative rotation of the medium-speed rotating body 2 and the low-speed rotating body 1 and the driven ring body 5 is allowed by the sliding operation of the ratchet pawls 22 and 21 with respect to the ratchet teeth 24. Therefore, the medium-speed rotating body 2 and the low-speed rotating body 2 The body 1 rotates at a specific speed lower than that of the high-speed rotating body 3 regardless of the transmission of power.

  On the other hand, as shown in FIG. 5, when the switching ring 28 is rotated by one step and the switching member 25 is advanced to the intermediate position as shown in FIG. 5, the switching member 25 presses the ratchet pawl 23 of the high-speed rotating body 3. Since the engagement between the ratchet pawl 23 and the ratchet teeth 24 is released, the rotation transmission from the high-speed rotating body 3 is interrupted, and the rotation of the medium-speed rotating body 2 is sprocket 4 via the ratchet pawl 22. Is transmitted to.

  Further, as shown in FIG. 6, when the switching ring 28 is rotated in two stages and the switching member 25 is pushed to the most advanced position, the annular portion 26 of the switching member 25 presses the ratchet pawl 22 of the medium speed rotating body 2. Since the engagement between the ratchet pawl 22 and the ratchet teeth 24 is released, the rotation transmission from the medium speed rotating body 2 is also cut off, and the rotation of the crankshaft 51 causes the ratchet pawl 21 of the low speed rotating body 1 to rotate. Is transmitted to the sprocket 4 without being increased in speed.

  Since the switching member 25 rotates at the same speed as the high-speed rotating body 3, a difference in rotational speed occurs between the switching member 25 and the medium-speed rotating body 2. Therefore, the ratchet pawl 22 of the medium speed rotator 2 can be pressed in any phase.

  When the reverse speed change operation is performed from this state, the switching ring 28 is reversely rotated by the biasing force of the spring, and the switching member 25 is retracted away from the ratchet pawls 22, 23. Since the ratchet teeth 24 are engaged again, the rotation of the crankshaft 51 is accelerated.

A longitudinal side view showing a high-speed transmission state of a transmission according to an embodiment of the present invention The figure which shows the meshing state of a high-speed rotary body same as the above from the crank arm side The figure which shows the meshing state of a medium speed rotary body same as the above from the flame | frame side The figure which shows the meshing state of a low-speed rotary body same as the above from the flame | frame side Longitudinal side view showing the medium speed transmission state of the above transmission Longitudinal side view showing the low-speed transmission state of the transmission as above

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Low speed rotary body 2 Medium speed rotary body 3 High speed rotary body 4 Sprocket 5 Driven ring body 6 Fixing member 11 Bevel gears 12 and 13 Annular bevel teeth 14 Bevel gears 15 and 16 Annular bevel teeth 21, 22, 23 Ratchet claw 24 Ratchet teeth 25 switching member 26 annular portion 27 switching screw 28 switching ring 51 crankshaft 52 crank arm 53 frame

Claims (1)

  A low-speed rotating body fixed to a crankshaft rotating by a pedal depression force, a medium-speed rotating body that can freely rotate with respect to the crankshaft, and a high-speed rotating body are sequentially arranged, and a fixing member that does not rotate with respect to the frame is provided. A bevel gear whose axis is perpendicular to the crankshaft is axially attached to the low-speed rotating body, and the bevel gear is engaged with an annular bevel formed on the high-speed rotating body and a fixed member. A bevel gear that is orthogonal to each other is axially attached, and this bevel gear is meshed with an annular bevel tooth formed on a high-speed rotating body and a low-speed rotating body, and ratchet claws are attached to the outer periphery of the low-speed rotating body, medium-speed rotating body, and high-speed rotating body. The ratchet teeth that engage with these ratchet claws are formed inside the driven annulus integrated with the sprocket, and a switching member that can be operated from the outside is provided. Body and inside Bicycle transmission apparatus adapted to shift by switching engaging and disengaging the ratchet pawl and the ratchet teeth of the rotating body.

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