JP4648928B2 - Bicycle gear crank device - Google Patents

Description

  The present invention relates to a bicycle gear crank apparatus.

  A bicycle gear crank device includes a crankshaft rotatably supported on a hanger portion of a bicycle frame, a crank arm attached to a left end portion of the crankshaft, and a gear crank attached to a right end portion of the crankshaft. It consists of The gear crank is an integrated right crank arm and front gear. A pedal is attached to the tip of each crank arm. In this configuration, the front gear can be rotated around the crankshaft when the occupant applies pedaling force to the left and right pedals. The rotation of the front gear is transmitted to the rear gear through a chain wound around the front gear, and the rear wheel of the bicycle is rotated.

  Conventionally, this type of bicycle gear crank apparatus generally has the configuration shown in Patent Document 1. That is, the crankshaft is rotatably supported by the left and right bearings with respect to the hanger pipe or a member integral therewith, and the left crank arm and the right gear crank are cranks supported by the hanger pipe as described above. It was attached to both ends of the shaft.

JP 2006-160139 A

  The above-described conventional bicycle gear crank apparatus has the following problems.

  First, the crank arm or gear crank is attached to the crankshaft by fitting the boss provided on the crankshaft to the shaft end of the crankshaft. As a result, the rotation axis of the front gear does not always coincide with the center of the front gear. This means that a state in which the front gear rotates with slight eccentricity can appear, which may adversely affect the driving force transmission efficiency of the bicycle gear crank device.

  Second, the position of the bearing for supporting the crankshaft on the hanger pipe in the crankshaft direction and the position in the crankshaft direction of the mounting portion of the crank arm or gear crank with respect to the crankshaft are largely separated from each other. The strong bending stress is concentrated near the bearing support part of the crankshaft. Therefore, the required strength of the crankshaft becomes very large, and the crankshaft may be expensive in terms of materials or disadvantageous in terms of weight.

  The present invention has been conceived under such circumstances. The present invention can reduce an error generated between the center of the front gear and the rotational axis of the front gear, and can reduce the concentration of bending stress on the crankshaft caused by the pedaling force of the occupant. It is an object of the present invention to provide a gear crank device for use.

  In order to solve the above problems, the present invention employs the following technical means.

  That is, the bicycle gear crank device provided by the present invention is rotatably supported by a bicycle hanger pipe, and has an intermediate portion and a first portion extending in a tapered diameter manner through a step portion at one end of the intermediate portion. And a crankshaft having a second small diameter portion extending in a taper-reduced shape through a step portion on the other end side of the intermediate portion, and the first small diameter portion of the crankshaft, A bicycle gear crank apparatus comprising: a gear crank in which a front gear and a crank arm are integrated; and a crank arm attached to the second small diameter portion of the crankshaft, wherein the gear crank is The central through hole of the first boss portion formed in this is fitted to the first small diameter portion of the crankshaft by fitting the central through hole with the first small diameter portion of the crankshaft so as not to be relatively rotatable. The first bearing is interposed between the outer peripheral surface of the first boss portion and the inner peripheral surface of the hanger pipe, and the first small diameter portion of the crankshaft and the first The fitting portion of the boss portion with the central through hole overlaps the axial direction of the crankshaft with respect to the first bearing, and the crank arm extends through the center of the second boss portion formed on the crankshaft. A hole is attached to the second small diameter portion of the crankshaft by fitting the hole to the second small diameter portion of the crankshaft so as not to rotate relative to the outer peripheral surface of the second boss portion. A second bearing is interposed between the inner peripheral surface of the hanger pipe and a fitting portion between the second small diameter portion of the crankshaft and the central through hole of the second boss portion is Axis of the crankshaft relative to the second bearing It overlaps the direction, and the outer peripheral surface of the first boss portion, characterized in that it has a central axis which is coincident with the center of the front gear.

  In the above configuration, one end of the crankshaft is not supported on the hanger pipe via the bearing, but the gear crank is supported on the hanger pipe via the first bearing. Therefore, the gear crank can be rotatably supported with respect to the hanger pipe without being affected by the manufacturing error of the shaft end portion of the crankshaft or the manufacturing error of the hole of the first boss portion of the gear crank. As a result, the rotational axis of the front gear can be made to coincide with the center of the front gear, and it is possible to prevent a situation in which the front gear rotates with a slight eccentricity.

  In the above configuration, the outer peripheral surface of the first boss portion has a central axis that coincides with the center of the front gear.

  In the gear crank, when the front gear or the first boss portion is formed integrally, it is easy to make the center of the front gear coincide with the central axis of the outer peripheral surface of the first boss portion. In this case, the front gear can be accurately rotated about its center as the rotation axis.

  In the above configuration, the gear crank is configured such that a center through hole of the first boss portion of the gear crank is fitted to the first small diameter portion of the crankshaft so as not to be relatively rotatable. The fitting portion between the first small diameter portion of the crankshaft and the central through hole of the first boss portion is attached to the first bearing with respect to the first bearing. They overlap in the axial direction of the crankshaft.

  According to such a configuration, the bending moment caused by the pedaling force of the occupant is received by the crankshaft through the first boss portion of the gear crank and partly received by the hanger pipe via the first bearing. Can also be received. Therefore, the bending stress acting on the crankshaft can be reduced. As a result, the required strength of the crankshaft can be reduced and the weight thereof can be reduced.

  In the above configuration, a crank arm is attached to the second small diameter portion of the crankshaft, and a second boss portion is formed on the crank arm. A second bearing is interposed between the outer peripheral surface of the part and the hanger pipe.

  The crank arm is configured such that a central through hole of the second boss portion of the crank arm is fitted to the second small diameter portion of the crank shaft in a relatively non-rotatable manner, thereby allowing the second crank shaft to be rotated. The fitting portion between the second small diameter portion of the crankshaft and the central through hole of the second boss portion of the crank arm is connected to the crankshaft with respect to the second bearing. Overlapping in the axial direction of the shaft.

  In such a configuration, the other end of the crankshaft is not supported by the hanger pipe via the bearing, but the crank arm itself is supported by the hanger pipe via the second bearing. In addition, a bending moment caused by the occupant's pedaling force can be received by the crankshaft via the second boss portion of the crank arm, and can also be received by the hanger pipe via the second bearing. . Therefore, the bending stress acting on the crankshaft can be reduced. As a result, the required strength of the crankshaft can be further reduced and the weight thereof can be reduced.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the drawings.

1 to 3 show a bicycle crankset equipment according to a reference example of the present invention. The rotation gear crank device 10A includes a crankshaft 200 rotatably supported on a bicycle hanger portion 100, a gear crank 300 attached to the right end portion of the crankshaft 200, and a left end portion of the crankshaft 200. And a crank arm 400 attached thereto. The gear crank 300 is obtained by integrating the crank arm 320 and the front gear 500.

  The crankshaft 200 has an intermediate portion 210 having a uniform outer diameter, a spline-like large-diameter portion 210a at the left end, and a small-diameter portion 220 at the right end, and has a generally hollow cylindrical shape. The small-diameter portion 220 at the right end protrudes in a taper-diameter shape toward the right via the step portion 221, and has a deformed cross-sectional shape having a spline-like outer periphery as shown in FIG. A screw hole 222 penetrating in the axial direction is formed.

  The gear crank 300 is integrally formed with a boss portion 310 located at the center, a crank arm 320 extending radially from the boss portion 310, and a plurality of gear support stays 330 extending radially from the boss portion 310. In addition, two gears 500 are supported on the gear support stay 330. The boss portion 310 protrudes inward with respect to the gear support stay 330 and includes a central through hole 311. The boss portion 310 has a small-diameter cylindrical portion 313 that protrudes inward via a step portion 312, and the outer diameter of the small-diameter cylindrical portion 313 is the same as the outer diameter of the axial intermediate portion 210 of the crankshaft 200. It is made to correspond. Further, the central through hole 311 of the boss portion 310 includes an inward flange 311a formed at an axially intermediate portion, a counterbore portion 311b outside the inward flange 311a, and a crankshaft receiving portion 311c inside the inward flange 311a. And. The crankshaft receiving portion 311c is inwardly expanded in a tapered shape to the same extent as the small diameter portion 220 so as to receive and fit the small diameter portion 220 of the crankshaft 200 so as not to be relatively rotatable. A spline-like deformed hole corresponding to the outer peripheral shape of the small-diameter portion 220 is formed.

  The crankshaft 200 and the gear crank 300 are configured to fit the crankshaft receiving portion 311c into the small diameter portion 220 and screw the bolt 340 inserted into the central through hole 311 from the outer end thereof into the screw hole 222. In this way, they can be integrated. At this time, the small-diameter portion 220 and the crankshaft receiving portion 311c are fitted in a tapered shape and are spline-fitted at the same time, so that the contact surface pressure of the fitting portion can be significantly increased. As a result, the crankshaft 200 and the gear crank 300 are integrated with each other so as not to rotate relative to each other and with extremely high connection strength.

In the rotating gear crank device 10A , the hanger portion 100 is constituted by a hanger pipe 110 itself. The crankshaft 200 is rotatably supported by the hanger pipe 100 in a state where the gear crank 300 is integrated at one end (right end) thereof. In bicycle gear crank apparatus 10A this, the left end portion of the crank shaft 200, by interposing a second bearing 60B between the inner peripheral surface of the outer peripheral surface Hangapaipu 110 of the crankshaft 200, Although directly supported by the hanger pipe 110, the right end portion, that is, the side to which the gear crank 300 is connected is the outer peripheral surface of the small-diameter cylindrical portion 313 in the boss portion 310 of the gear crank 300 and the inner periphery of the hanger pipe 110. By interposing the first bearing 60 </ b> A between the surface and the surface, it is indirectly supported by the hanger pipe 110. As shown in FIGS. 1 and 3, the small-diameter cylindrical portion 313 on which the first bearing 60A is seated has a crankshaft receiving portion 311c formed in the axial direction, and a small-diameter portion of the crankshaft 200 is formed on the crankshaft receiving portion 311c. 220 is fitted. Thus, the mutual fitting part of the crankshaft 200 and the gear crank 300 becomes the shape which overlapped with the axial direction of the crankshaft 200 with respect to the 1st bearing 60A. In this bicycle gear crank apparatus 10A , both the first bearing 60A and the second bearing 60B are configured such that a plurality of balls 63 are interposed between an outer ring 61 and an inner ring 62 so as to allow rolling. Commercially available rolling ball bearings are used.

A crank arm 400 is attached to the left end portion of the crankshaft 200. The crank arm 400 includes a boss portion 410 and an arm portion 420 extending from the boss portion 410 in the radial direction. The crank arm 400 extends in a direction opposite to the crank arm 320 of the gear crank 300 by 180 ° in the assembled state. The crank arm 400 is also fitted so that the central through hole 411 of the boss portion 410 is not rotatable relative to the left end portion of the crankshaft 200. In this bicycle gear crank apparatus 10A , the left end portion of the crankshaft 200 is the spline-shaped large diameter portion 210a as described above, and the central through hole 411 of the boss portion 410 of the crank arm 400 is used as a corresponding spline hole. By mutually fitting them, the crank arm 400 is connected to the left end portion of the crankshaft 200 so as not to be relatively rotatable.

  The bicycle gear crank apparatus 10A having the above-described configuration can be assembled as follows.

  The first bearing 60 </ b> A and the second bearing 60 </ b> B are press-fitted and attached to the hanger pipe 110 at predetermined positions in the axial direction of the hanger pipe 110. The crankshaft 200 is inserted into the boss portion 410 of the crank arm 400 from the left, and the spline hole 411 and the spline-shaped large diameter portion 210a are fitted. In this state, the crankshaft 200 is inserted from the left side of the hanger pipe 110, and the boss portion 310 of the gear crank 300 is inserted from the right side of the hanger pipe 110, and the small diameter portion 220 of the crankshaft 200 and the boss portion of the gear crank 300 are inserted. The crankshaft receiving portion 313c of the portion 310 is spline fitted as described above. At that time, the first bearing 60A is seated on the outer peripheral surface of the small-diameter cylindrical portion 313 of the boss portion 310, and the crank arm 400 and the crank arm 320 of the gear crank 300 are adjusted to extend in opposite directions by 180 °. To do. Then, a bolt 340 inserted from the right side into the central through hole 311 of the boss portion 310 is screwed into the screw hole 222 of the small diameter portion 220 of the crankshaft 200.

  Next, the operation of the bicycle gear crank apparatus having the above configuration will be described.

  In the bicycle gear crank apparatus 10A having the above-described configuration, the gear crank 300 is rotatably supported with respect to the hanger part 100 via the first bearing 60A in the small diameter cylindrical part 313 of the boss part 310. It is relatively easy to process the center of the small diameter cylindrical portion 313 so as to coincide with the center of the front gear 500. Accordingly, the rotational axis of the front gear 500 can be made coincident with the center of the front gear 500, and it is possible to prevent a situation in which the front gear rotates with a slight eccentricity as in the prior art. A driving state can be realized.

  The fitting portion between the boss portion 310 of the gear crank 300 and the small diameter portion 220 of the crankshaft 200 is positioned so as to overlap in the axial direction of the first bearing 60A and the crankshaft 200. With such a configuration, a part of bending moment acting on the gear crank 300 due to the occupant's pedaling force can be received by the crankshaft 200 via the boss portion 310 of the gear crank 300. The part can also be received by the hanger part 100 via the first bearing 60A. Thereby, the bending stress acting on the crankshaft 200 can be reduced, and as a result, the required strength of the crankshaft 200 can be reduced and the weight thereof can be reduced.

Figure 4 shows an embodiment of a bicycle crankset device according to the present invention. This bicycle gear crank device 10B differs from the bicycle gear crank device 10A according to the reference example described above in the support structure for the hanger portion 100 at the left end portion of the crankshaft 200, that is, the right end portion of the crankshaft 200, that is, The support structure on the side that supports the gear crank 300 is the same as that of the bicycle gear crank apparatus 10A . Hereinafter, the support structure at the left end portion of the crankshaft 200 will be described, and the support structure at the right end portion of the crankshaft 200 will be denoted by the same reference numerals as those of the bicycle gear crank apparatus 10A, and description thereof will be omitted.

  A small diameter portion 230 similar to the right end portion is formed at the left end portion of the crankshaft 200. That is, the small-diameter portion 230 protrudes in a taper-reduced shape toward the left via the step portion 231, and has a deformed cross-sectional shape having a spline-like outer periphery as shown in FIG. And the screw hole 232 penetrated to an axial direction is formed.

On the other hand, the boss portion 410 of the crank arm 400 is formed with a small-diameter cylindrical portion 413 that protrudes inward via a step portion 412, and the outer diameter of the small-diameter cylindrical portion 413 is the small-diameter cylindrical portion of the gear crank 300. It corresponds to the outer diameter of 313. Further, the central through hole 411 of the boss portion 410 has an inward flange 411a formed at an axially intermediate portion, a counterbore portion 411b outside the inward flange 411a, and a crankshaft receiving portion 411c inside the inward flange 411a. And. The crankshaft receiving portion 411c is inwardly expanded in a taper shape to the same extent as the small diameter portion 230 so as to receive and fit the small diameter portion 230 of the crankshaft 200 so as not to be relatively rotatable. It forms a spline-like deformed hole corresponding to the outer peripheral shape of the small-diameter portion 230. The left end portion of the crankshaft 200 and the crank arm 400 are configured to fit the crankshaft receiving portion 411 c into the small diameter portion 230 and to insert the bolt 440 inserted into the central through hole 411 from the outer end portion into the screw hole 232. It can be integrated by screwing to The second bearing 60 </ b> B is interposed between the outer peripheral surface of the small-diameter cylindrical portion 413 of the boss portion 410 of the crank arm 400 and the hanger pipe 110. That is, in this embodiment, the connection between the left end and the crank arm 400 at the right end of the crank shaft 200 connecting structure similar is the gear crank 300 of the crank shaft 200 definitive in bicycle gear crank apparatus 10A described above Adopted in the structure.

  According to such a configuration, a part of the bending moment acting on the crank arm 400 due to the pedaling force of the occupant can be received by the crankshaft 200 via the boss portion 410 of the crank arm 400, and A part of the hanger 100 can be received by the second bearing 60B. As a result, the bending stress acting on the left end portion of the crankshaft 200 can be reduced, and as a result, the required strength of the crankshaft 200 can be reduced and the weight can be further reduced.

5 and 6 show a bicycle crankset equipment according to another reference example of the present invention. The bicycle gear crank apparatus 10C compares the bicycle crankset device 10B according to the implementation embodiments described above, the hanger portion 100, a Hangapaipu 110, bearing support member 120 screwed to opposite ends of the Hangapaipu 110 The difference is that the first bearing 60A and the second bearing 60B are interposed on the inner periphery of the bearing support member 120. Since the other points are the same as those of the bicycle gear crank apparatus 10B , the same members or portions are denoted by the same reference numerals, and detailed description thereof is omitted.

  In this configuration, female threaded portions 111 are formed on the inner periphery of both end portions of a relatively small diameter hanger pipe 110, while the bearing support member 120 is a male threaded portion that can be screwed onto the female threaded portion 111 on the outer periphery. A cylindrical portion 122 formed with 121 and a large-diameter cylindrical portion 123 integrally connected to the outer end portion of the cylindrical portion 122, and by screwing the male screw portion 121 into the female screw portion 111, The first and second bearings 60 </ b> A and 60 </ b> B are held on the inner periphery of the large-diameter cylindrical portion 123.

  Even in such a configuration, since the bending moment acting on the gear crank 300 or the crank arm 400 due to the pedaling force of the occupant can be dispersed and received in the hanger portion 100 and the crankshaft 200, the crankshaft 200 The required strength can be reduced to reduce the weight. Further, as shown in FIG. 5, the position of the first bearing 60A in the crankshaft direction can be made closer to the position of the front gear 500 in the crankshaft direction, so that the transmission efficiency of the driving force can be improved. it can.

  Of course, the scope of the present invention is not limited to the above-described embodiment, and all modifications within the scope of matters described in the claims are all included in the scope of the present invention.

  In the embodiment, commercially available rolling ball bearings are used as the first and second bearings. However, the present invention is not limited to this. Of course, so-called cup and cone type bearings may be employed.

  Of course, the gear crank may be provided with a single front gear in addition to a plurality of front gears.

It is sectional drawing of the gear crank apparatus for bicycles which concerns on the reference example of this invention. It is a side view of the gear crank apparatus for bicycles of FIG. It is the III-III sectional view taken on the line of FIG. 1 and FIG. It is sectional drawing of the gear crank apparatus for bicycles concerning one Embodiment of this invention. It is sectional drawing of the gear crank apparatus for bicycles which concerns on the other reference example of this invention. FIG. 6 is a sectional view taken along line VI-VI in FIG. 5.

10A, 10B, 10C Bicycle gear crank device 100 Hanger portion 110 Hanger pipe 120 Bearing support member 200 Crankshaft 210 Intermediate portion 220, 230 Small diameter portion 222, 232 Screw hole 300 Gear crank 310 Boss portion 311 Central through hole 311c Crankshaft receiving portion 313 Small diameter cylindrical portion 400 Crank arm 410 Boss portion 411 Central through hole 411c Crankshaft receiving portion 413 Small diameter cylindrical portion 500 Front gear 60A First bearing 60B Second bearing

Claims (1)

Is rotatably supported on the bicycle hanger pipe Rutotomoni, intermediate portion, a first small diameter portion extending in a tapered reduced径状via a step portion on one end side of the intermediate portion, and, on the other end of the intermediate section A crankshaft having a second small diameter portion extending in a taper-reduced shape through a stepped portion, and a gear crank attached to the first small diameter portion of the crankshaft, in which a front gear and a crank arm are integrated; A crank arm for a bicycle comprising a crank arm attached to the second small diameter portion of the crankshaft ,
The gear crank is configured such that a central through hole of a first boss portion formed in the gear crank is fitted to the first small diameter portion of the crankshaft so as not to be relatively rotatable, thereby the first small diameter of the crankshaft. Attached to the
A first bearing is interposed between the outer peripheral surface of the first boss portion and the inner peripheral surface of the hanger pipe, and the first small diameter portion of the crankshaft and the first boss portion The fitting portion with the central through hole overlaps the axial direction of the crankshaft with respect to the first bearing,
The crank arm is configured such that a central through hole of a second boss portion formed on the crank arm is fitted to the second small diameter portion of the crank shaft so as not to be relatively rotatable, thereby allowing the second shaft of the crank shaft to be rotated. It is attached to the small diameter part,
A second bearing is interposed between the outer peripheral surface of the second boss portion and the inner peripheral surface of the hanger pipe, and the second small diameter portion of the crankshaft and the second boss portion The fitting portion with the central through hole overlaps with the second bearing in the axial direction of the crankshaft, and
The bicycle gear crank device, wherein an outer peripheral surface of the first boss portion has a central axis line that coincides with a center of the front gear .

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