JP4022454B2 - Bicycle gear crank and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a bicycle gear crank, and more particularly to a multistage bicycle gear crank having three or more gears arranged side by side.
[0002]
[Prior art]
The bicycle includes a gear crank as a front gear and a free wheel as a rear gear, and an endless chain is wound between the gear crank gear and the free wheel gear to form a drive mechanism. A pedal is attached to the crank arm of the gear crank. When the pedal is depressed and the gear crank is rotated in the forward direction, this rotation is transmitted as a forward rotation to the free wheel through the endless chain, and the rear wheel rotates in the forward direction and the bicycle moves forward.
[0003]
Most modern bicycles are equipped with a transmission, and when this transmission is used as an exterior transmission, the freewheel is usually configured in a multistage system, and in some cases, the gear crank is also configured in a multistage system. There are things to do. A rear derailleur is provided adjacent to the freewheel to forcibly change the chain on the freewheel gear to another gear, while on the other hand, adjacent to the multistage gear crank. A front derailleur is provided to forcibly change the chain to another gear. As a result, it is possible to perform gear shifting with the number of gears of the multi-stage gear crank multiplied by the number of gears of the multi-stage freewheel.
[0004]
In such a multi-stage gear crank, an outer gear is used as a maximum diameter gear, and a plurality of gears having smaller diameters are arranged side by side on the inner side (for example, see Patent Document 1). And these several gears are united and are supported by the boss | hub part formed in the base end part of a crank arm. The boss portion is fitted and fixed to one end of a crankshaft rotatably supported by the hanger portion of the bicycle frame.
[0005]
[Patent Document 1]
JP-A-9-86471 [0006]
[Problems to be solved by the invention]
By the way, when the bicycle is driven, a considerable force acts on each part of the multistage gear crank. In addition to the driving force in the circumferential direction of the gear, there is also a force acting in the plate thickness direction of the gear due to the driving force because the gears are arranged in the crankshaft direction. Each gear of the gear crank needs to have a predetermined rigidity or more with respect to the force in the gear thickness direction. Therefore, in the gear crank disclosed in the above-mentioned JP-A-9-86471, In order to increase the support rigidity of the gear, a reinforcing member is provided for connecting the outer end of the boss portion of the crank arm to the peripheral portion of the outer gear.
[0007]
In addition, in order to increase the support rigidity of each gear of the gear crank, there is a structure in which a plurality of stays extending radially from the boss portion are provided on the crank arm side and each gear is supported via this stay. If it does, there exists a problem that the weight of a crank arm will increase.
[0008]
Furthermore, each gear to be provided on this type of multi-stage gear crank is generally donut-shaped, but it is usually made by stamping separately from different material plates and pressing. is there. If it does so, there also exists a problem that the material board applicable to the inner side of a donut shape will be wasted.
[0009]
The present invention has been conceived under the circumstances described above, reduces the waste of the material plate, and maintains the rigidity of each gear in a state where a plurality of gears are integrated to a predetermined level or more. It is an object of the present invention to provide a new bicycle gear crank that can be used.
[0010]
DISCLOSURE OF THE INVENTION
In order to solve the above problems, the present invention employs the following technical means.
[0011]
The bicycle gear crank provided by the first aspect of the present invention is a gear obtained by integrating three gears of an outer gear, an intermediate gear having a smaller diameter than the outer gear, and an inner gear having a smaller diameter than the intermediate gear in parallel. In the bicycle gear crank that forms a set and the gear set is fixedly supported on the boss portion of the crank arm, the inner gear has a form in which teeth are formed on the entire circumference thereof , and the outer gear is A mounting piece for mounting to the intermediate gear is formed in a radially inwardly extending shape, and when the outer gear is overlapped with the inner gear and the center thereof, the inter-tooth portion of the inner gear is mounted on the mounting piece. And the outer gear is positioned radially outward from the inward projection on the mounting piece. Oite is characterized in that it is connected to the outer side surface of the intermediate gear.
[0012]
When the outer gear and the inner gear overlaid their center each other, inward projection of the outer gear it can just fit into the interdental portion of the teeth formed on the entire circumference of the inner gear. This means that the said outer gear and the inner gear can be cut conveniently from a single material plate. To form a gullet punched portions of the inner gear is of the above inward projection of the outer gear.
[0013]
Thus, the outer gear, intermediate gear, and the inner gear of two of the outer gear and the inner gear in a multi-stage gear crank formed gear is of being conveniently obtained from a single material plate, to save material, Cost can be reduced.
[0014]
Further, inward projection formed on the outer gear, the force to the position radially outward of the inward projection when connected to the side surface of the intermediate gear, trying to peel off from the intermediate gear adjacent the outer gear in the thickness direction thereof Can be received on the side surface of the intermediate gear as a reaction force. Thus, the rigidity is increased with respect to a force to displace the outer gear in the thickness direction. As a result, the rigidity of the gear set in the bicycle gear crank can be increased.
[0017]
In a preferred embodiment, the intermediate gear has its center hole fixedly fitted to the boss portion of the crank arm, and the inner gear is connected to the inner side surface of the intermediate gear.
[0018]
In this way, the gear set can be conveniently supported on the boss portion of the crank arm via the intermediate gear without the need to provide a separate gear support member.
[0019]
Further, in a preferred embodiment, the inner gear has a center hole fixed to the boss portion of the crank arm together with the center hole of the intermediate gear.
[0020]
In this way, since the inner gear and the intermediate gear are doubled and supported by the boss portion of the crank arm, the support rigidity of the gear set with respect to the crank arm is conveniently increased.
[0021]
Method of manufacturing a bicycle gear crank provided by the second aspect of the present invention is the first bicycle gear crank of the manufacturing method according to the aspect of the present invention, the above outer gear and the inner gear, It is characterized by being cut out from one material plate.
[0023]
The significance of the second aspect will be easily understood from the significance described above for the first aspect of the present invention. Incidentally, that the A Utagia and the inner gear is cut from a sheet of material plates, it does not mean that constitutes the gear crank with a set itself the gear cut out of the same material plate. In the actual production of a gear crank, a large number of gears of various sizes are prepared as parts, and these are combined. Naturally, the gears combined in this way are not necessarily cut out from the same material plate. However, a number of A Utagia has the same shape, a large number of i N'nagia is're the same shape.
[0024]
Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the drawings.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings. 1 is a front view of a bicycle gear crank 1 according to an embodiment of the present invention, FIG. 2 is a side view thereof, FIG. 3 is a rear view thereof, and FIG. 4 is a line IV-IV in FIG. FIG. 5 is an explanatory view of material removal.
[0026]
The bicycle gear crank 1, as clearly shown in FIGS. 2, 3 and 4, and A Utagia 10, a small-diameter intermediate gear 20 than this, the diameter of Lee N'nagia 30 further than this intermediate gear 20 The gear set 2 formed by juxtaposing the three gears in the thickness direction is fixed to the outer peripheral portion of the boss portion 41 of the crank arm 40 in a fitting manner.
[0027]
The outer gear 10 is formed by press-punching and press-molding from a material plate having a predetermined plate thickness, and a ring portion 12 having a large number of teeth 11 on the outer periphery, and extends from the inner periphery of the ring portion 12 at equal intervals 4. The mounting piece 13 of the location is provided. As shown in FIG. 4, each mounting piece 13 is biased in a stepped manner toward the inner side, and is attached to connect to the intermediate gear 20 adjacent to the inner side via the bolt 3. A hole 15 is formed. As clearly shown in FIG. 1, an inward projection 14 having a predetermined shape is extended on the inner side of the mounting piece 13. As will be described later, the inward projection 14 corresponds to the shape of the interdental portion 33 of the outer peripheral tooth 31 of the inner gear 30. The inward projection 14 is also positioned at the innermost peripheral portion of the outer gear 10. Furthermore, in this embodiment, a mounting hole 16 for mounting the chain dropout prevention cover 50 with the bolt 4 is formed in the outer peripheral ring portion 12 of the outer gear 10.
[0028]
The intermediate gear 20 is also formed by press-punching and press-molding from a material plate having a predetermined thickness. A large number of teeth 21 are formed on the outer periphery, and the intermediate gear 20 is fitted on the outer periphery of the boss portion 41 of the crank arm 40. A power center hole 22 is provided. The intermediate gear 20 also has four decorative holes 23 punched out to reduce weight, so that the outer ring portion 12 and the inner ring portion are connected by four stays 24. . As shown in the figure, the four stays 24 are biased in a stepped manner toward the inner side from the intermediate portion in the radial direction, and provided on the mounting piece 13 of the outer gear 10. A mounting hole 25 for connecting and fixing the outer gear 10 with the bolt 3 is formed so as to correspond to the mounting position 15 in the radial direction, and further radially inward than the mounting hole 25, A mounting hole 26 for connecting and fixing the inner gear 30 to be adjacent to the inner side of the intermediate gear 20 with the bolt 5 is provided.
[0029]
The inner gear 30 is also formed by press-punching and press-molding from a material plate having a predetermined thickness. A large number of teeth 31 are formed on the entire outer periphery, and as shown in FIG. The inner part is biased toward the outer side, and has a center hole 32 to be fitted over the outer periphery of the boss part 41 of the crank arm 40. The radial position of the inter-tooth portion 33 in the inner gear 30 corresponds to the radial position of the inward projection 14 formed on the mounting piece 13 of the outer gear 10. The inner gear 30 is also reduced in weight by punching the decorative hole 34. An attachment hole 35 for connecting the inner gear 30 to the intermediate gear 20 via the bolt 5 is provided in correspondence with the attachment hole 26 of the intermediate gear 20.
[0030]
The outer gear 10, the intermediate gear 20, and the inner gear 30 are connected to each other by the bolt 3 and the intermediate gear 20 and the inner gear 30 by the bolt 5, as best shown in FIG. Thus, they are integrated into a gear set 2. A chain drop prevention cover 50 is attached to the outer side surface of the outer gear 10 with a bolt 4. The connection between the gears 10, 20, and 30 is not limited to bolts, and caulking members may be used.
[0031]
The gear set 2 has an inner side end of the boss portion 41 in a state where the center holes 22 and 32 of the intermediate gear 20 and the inner gear 30 are fitted to the outer periphery of the boss portion 41 with respect to the boss portion 41 of the crank arm 40. It is fixed and supported by caulking the part.
[0032]
As described above, the inward projection 14 in the outer gear 10 has a shape corresponding to the inter-tooth portion 33 in the inner gear 30, and the radial position of the inward projection 14 is the inter-tooth portion of the inner gear 30. This corresponds to 33 radial positions. This means that when the outer gear 10 and the inner gear 30 are overlapped with each other in the center, the inward projection 14 and the interdental portion 33 can fit into each other as shown in FIG. means. In the outer gear 10, the inward projection 14 is located at the radially innermost side of the outer gear 10, so that the inward projection 14 of the outer gear 10 and the inter-tooth portion 33 of the inner gear 30 as shown in FIG. 5. And the gears 10 and 30 do not overlap each other. This means that the outer gear 10 and the inner gear 30 can be obtained by punching from one material plate, as can be understood from FIG.
[0033]
Therefore, in the bicycle gear crank 1 of the present invention, at least two of the plurality of gears arranged side by side are obtained from one material plate. As a result, the material is saved and the cost is reduced. Can be planned.
[0034]
In the mounting piece 13 of the outer gear 10, the vicinity of the inward projection 14 located radially outward is connected to the gear adjacent to the inner side. Therefore, if a force for peeling off the outer gear 10 from the intermediate gear 20 is applied, a part of this force extends radially inward from the bolt 3 by the inward projection 14 with the bolt 3 as a fulcrum. Is effectively received by the side surface of the intermediate gear 20. This means that the mounting rigidity with respect to the external force in the thickness direction of the outer gear 10 is increased.
[0035]
As described above, according to the present invention, not only can the material be saved, but also the excellent advantage of being able to conveniently increase the support rigidity of the gear in the assembled state is provided.
[0036]
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.
[0037]
The present invention is not intended that will be limited to the embodiments provided with three gears, can of course apply in the case of juxtaposed four or more gears. Of the four or more gears, the selected gear is the first gear, and any one of the smaller gears is the second gear. The first gear and the second gear are connected to the inward projection 14 and the teeth. By adopting the configuration with the portion 33, it is only necessary to cut out from one material plate.
[0038]
In the embodiment, the center holes 22 and 32 of both the intermediate gear 20 and the inner gear 30 are fitted and fixed to the boss portion 41 of the crank arm 40, but only the center hole of one of the gears is the boss of the crank arm 40. You may make it fit and fix to the part 41. FIG.
[Brief description of the drawings]
FIG. 1 is a front view of a bicycle gear crank according to an embodiment of the present invention.
2 is a side view of the bicycle gear crank shown in FIG. 1. FIG.
FIG. 3 is a rear view of the bicycle gear crank shown in FIG. 1;
4 is a cross-sectional view taken along line IV-IV in FIG.
FIG. 5 is an explanatory diagram of material removal for cutting out a predetermined gear in manufacturing the bicycle gear crank shown in FIG. 1;
[Explanation of symbols]
1 Bicycle gear crank 2 Gear set 10 Outer gear (first gear)
11 tooth 12 ring part 13 mounting piece 14 inward projection 20 intermediate gear 21 tooth 22 center hole 23 decoration hole 30 inner gear (second gear)
33 Interdental part 40 Crank arm 41 Boss part

Claims (4)

Three gears, an outer gear, an intermediate gear with a smaller diameter and an inner gear with a smaller diameter than this intermediate gear, are integrated in parallel to form a gear set, and this gear set is fixedly supported on the boss of the crank arm. In the bicycle gear crank,
The inner gear has a form in which teeth are formed on the entire circumference thereof, and the outer gear has a mounting piece for mounting on the intermediate gear formed in a radially inward extending shape. the fitting piece, when the outer gear of repeating the inner gear and their center, Ri Contact comprise inward projection that can fit into the interdental portion of the inner gear, and,
The bicycle gear crank, wherein the outer gear is connected to an outer side surface of the intermediate gear at a position radially outward from the inward projection of the mounting piece . 2. The bicycle gear according to claim 1 , wherein a center hole of the intermediate gear is fitted and fixed to a boss portion of the crank arm, and the inner gear is connected to an inner side surface of the intermediate gear. crank. The bicycle gear crank according to claim 2 , wherein a center hole of the inner gear is fitted and fixed to a boss portion of the crank arm together with a center hole of the intermediate gear. The method of manufacturing a bicycle gear crank according to any one of claims 1 to 3 , wherein the outer gear and the inner gear are cut out from a single material plate. Production method.

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