JPH0137991Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of a gear crank device for a bicycle.

In a bicycle gear crank device that conventionally consists of a crankshaft, a pair of left and right crank arms, and a chain gear, the crank arm can be removed from the end of the crankshaft, and the chain gear can also be removed from the crankshaft and crank arm. There is a model. According to this, the left and right crank arms can be made into the same shape and can be used in common, and the chain gear can be freely replaced with one with a different diameter and number of teeth, or with a single or double one. It has the advantage that the crank arm and chain gear can be packed separately and transported in a small volume.

However, the above-mentioned conventional device has the drawback that the operations for attaching and detaching the chain gear are complicated and time-consuming, and are not easy operations.

Furthermore, since chain gears are generally thin, they have the disadvantage that they cannot be firmly fixed and are easily deformed.

This invention was made to solve the above-mentioned difficulties, and its features include: a crankshaft 6 having arm fitting parts 7 and 8 at both ends in the axial direction; A pair of crank arms 3 with boss parts 32 and 33 removably fitted together
0, 31; and a chain gear 21 provided inside the boss portion 33 of one crank arm 31 in the axial direction;
A bicycle gear crank device consisting of a chain gear 21 with a large number of uneven grooves 23 on the inner periphery of a shaft hole 22.
is formed and protrudes axially inward from the inner end surface of the boss portion 33 of one crank arm 31, and
A gear receiving part 40 whose outer diameter is smaller than the outer diameter of the boss part 33 is integrally formed with the boss part 33, and a large number of protrusions 18 along the axial direction are formed on the outer periphery of the gear receiving part 40. The chain gear 21 is fitted into the gear receiving portion 40 via the concavo-convex strips 23 and the convex strips 18 in an axially removable manner and non-rotatable relative to the shaft center, and the inner end surface of the boss portion 33 is connected to the chain gear 21. In the gear contact surface 41 that faces the outer surface of the chain gear and extends outward in the axial radial direction at right angles to the axial direction, the central portion of the chain gear 21 is more radially outer than the central portion. A ring-shaped gear reinforcing plate 24 is formed as a bulging portion 51 that bulges outward in the axial direction. It is fixedly integrated with the side surface, and the concave and convex strips 23 and the convex strips 1
8, it is fitted into the gear receiving part 40 so that it can be freely inserted and removed in the axial direction and cannot be rotated relative to the shaft center. A single fitting groove 19 is formed by arranging the fitting grooves 19 in parallel along the outer periphery, and the axially inner side surface of the notch of each protrusion 18 forming the fitting groove 19 extends outward in the axial radial direction. The chain gear 21 has a slope 20 that moves inward in the axial direction as it moves
The bulging portion 51 is located axially outward from the inner surface of the
Inside the space 50 axially inward from the inner surface of the
A retaining ring 25 that is elastically expandable and deformable in the radial direction of the shaft and biased in the radial direction is positioned between the inclined surface 20 and the inner surface of the bulged portion 51. The chain gear 21 and the gear reinforcing plate 24 are clamped and fixed between the retaining ring 25 and the gear contact surface 41, and one crank arm 31 is fitted to the axially outer side of the arm fitting part 8. A screw 10 is formed in the crank arm 31, and a nut 37 screwed into the screw 10 fixes the crank arm 31 to prevent it from coming out from the arm fitting portion 8.

An embodiment of this invented bicycle gear crank device will be described below with reference to the drawings.

In the drawing, 1 is a hanger pipe, and at both ends of the hanger pipe 1 in the axial direction there are left and right hanger bowls 2,
3 are fitted by press-fitting or screwing. Each hanger bowl 2, 3 is formed with a ball receiving surface 4, 5 facing outward in the axial direction.

Reference numeral 6 denotes a crankshaft that is loosely inserted into the hanger pipe 1 and the hanger bowls 2 and 3. At both left and right ends of the crankshaft 6 are arm fitting portions 7 and 8 for fitting the crank arms, and the respective fitting portions 7, Screws 9 and 10 located axially outside of 8 are formed.

Further, a large diameter portion 11 is provided on the axially inner side of the right arm fitting portion 8, and a ball receiving surface 12 opposite to the ball receiving surface 5 of the right hanger bowl 3 is formed inside the large diameter portion 11. has been done. Also, the left arm fitting part 7
A screw 13 is provided on the inner side in the axial direction. A ball pushing body 15 is screwed onto this screw 13. This ball pushing body 15 has the above-mentioned hanger bowl 2.
A ball receiving surface 14 is formed opposite to the ball receiving surface 4 of. The ball 16 interposed between the ball receiving surface 14 of the ball pushing body 15 and the ball receiving surface 4 of the hanger bowl 2, and the ball receiving surface 12 of the large diameter portion 11 and the ball receiving surface 5 of the hanger bowl 3. The crankshaft 6 is supported rotatably with respect to the hanger pipe 1 by the balls 17 interposed therebetween.

Reference numerals 30 and 31 denote a pair of left and right crank arms, and the arm fitting portions 7,
8 and is unrotatably fitted. By tightening the tightening nuts 36, 37 screwed onto the screws 9, 10, the crank arms 30, 31 fitted to both ends of the crankshaft 6 are fixed to prevent them from coming off.

A gear receiving portion 40 protrudes axially inward from the inner end surface of the boss portion 33 of one crank arm 31 and has an outer diameter smaller than the outer diameter of the boss portion 33.
is formed integrally with the boss portion 33.
A large number of protrusions 18 are formed on the outer periphery of the gear receiving portion 40 along the axial direction.

21 is a chain gear, a shaft hole 22 is opened in the center of this gear 21, and an uneven strip 23 is formed on the inner circumference of the shaft hole 22. And chain gear 2
1 is a gear receiving portion 40 with its concave and convex line 23 and the convex line 1
8, and is fitted (spline fitting) so as to be freely insertable and removable in the axial direction and non-rotatably relative to the center of the shaft.

The inner end surface of the boss portion 33 of one crank arm 31 is a gear contact surface 41 that faces the outer surface of the chain gear 21 and extends outward in the radial direction at right angles to the axial direction.

Further, the central portion of the chain gear 21 is formed as a bulging portion 51 that bulges outward in the axial direction with respect to a portion radially outward from the central portion. A ring-shaped gear reinforcing plate 24 having a larger diameter than the gear abutting surface 41 is fixedly integrated with the outer surface of the bulging portion 51 . This gear reinforcing plate 24 has an uneven strip 23 formed on its inner periphery, and is fitted into the gear receiving portion 40 via the uneven strip 23 and the above-mentioned protruding strip 18 so that it can be inserted into and removed from the gear receiving portion 40 in the axial direction and cannot rotate relative to the shaft center. are combined.

A midway portion in the axial direction of the protrusion 18 is cut out, and the cutout portions are arranged in parallel along the outer periphery of the gear receiving portion 40, thereby forming an integral fitting groove 19. Convex strips 1 forming the fitting grooves 19
The axially inner side surface of the notch 8 is a slope 20 that moves axially inward as it moves outward in the radial direction.

A C-shaped retaining ring 25 is fitted in a wedge shape between this slope 20 and the inner surface of the bulging portion 51 of the chain gear 21. This retaining ring 25 is formed of a spring material, and is capable of expanding and contracting in the radial direction of the shaft and is biased in the radial direction by the spring action.
The open ends 26 and 27 have tool insertion holes 28 and 29. As a result, the retaining ring 25 and the gear contact surface 4
1, a chain gear 21 and a gear reinforcing plate 24 are clamped and fixed. Further, the slope 20 and the retaining ring 25 are located inside the space 50 axially outward from the inner surface of the chain gear 21 and axially inner than the inner surface of the bulged portion 51 .

In the figure, reference numerals 38 and 39 indicate a pair of left and right dust caps. The left dust cap 38 is fitted and fixed to the outer periphery of the ball pusher 15, and the right dust cap 39 is fitted to the outer periphery of the large diameter portion 11. It is fitted.

In the above embodiment, when attaching the chain gear 21 to the crankshaft 6, first insert the shaft hole 22 of the chain gear 21 into the gear receiving part 40 of the crank arm 31, and then connect the uneven strip 23 on the inner circumference of the shaft hole 22 to the gear receiving part. 40, and the outer surface of the gear reinforcing plate 24 is brought into contact with the gear contact surface 41. Due to the fitting via the concavo-convex strips 23 and the convex strips 18, the chain gear 21 cannot rotate relative to the gear receiving portion 40. Next, a tool such as pliers is engaged with the tool insertion holes 28 and 29 of the retaining ring 25, and when the retaining ring 25 is expanded in the radial direction of the shaft and fitted into the fitting groove 19, the retaining ring 25 is is wedged between the inner surface of the bulging portion 51 of the chain gear 21 and the slope 20 due to the spring action of contraction. As a result, the chain gear 21 and the gear reinforcing plate 24 are connected to the retaining ring 25.
The gear receiving portion 4 is strongly held between the gear contact surface 41 and the
It is fixed in a state where it cannot be pulled out from 0. Next, the crank arm 31 is fitted into the arm fitting part 8 of the crankshaft 6, and the tightening nut 37 is screwed into the screw 10.
The arm 31 is fixed to the arm fitting portion 8 in a rotation-preventing manner.

To remove the chain gear 21 from the crankshaft 6 and crank arm 31, first remove the tightening nut 37 from the screw 10 and pull out the crank arm 31 from the arm fitting portion 8. Next, the retaining ring 25 is enlarged and removed from the fitting groove 19, and the chain gear 21 is moved axially inward and the gear receiving portion 40 is removed.
It's about extracting more.

According to the bicycle gear crank device according to the present invention, attachment and detachment of the chain gear 21 are performed by axially inserting and removing the crank arm 31 from the crankshaft 6 and axially inserting and removing the chain gear 21 from the crank arm 31. Removal can be accomplished only by attaching and detaching the nut 37 and the retaining ring 25, which is extremely easy to work with.

A gear reinforcing plate 24 having a larger diameter than the abutting surface 41 is fitted between the chain gear 21 and the contact surface 41 via the uneven strips 23 and the protruding strips 18, and the gear reinforcing plate 24 is fixed to the chain gear 21. It is integrated. As a result, the supporting area of the chain gear 21 by the crank arm 37 increases by an amount corresponding to the thickness of the gear reinforcing plate 24, and even if the chain gear 21 is thin, it is difficult to swing in the axial direction.
It is firmly fixed.

Furthermore, since the central portion of the chain gear is formed as a bulging portion 51, this bulging portion 51 functions as a reinforcing rib, increasing the strength of the central portion of the chain gear 21, and furthermore, the bulging portion 51 functions as a reinforcing rib. 51
Since the gear reinforcing plate 24 is fixedly integrated with the outer surface of the chain gear 21, the strength of the central portion of the chain gear 21 can be extremely increased. Therefore, the connection strength of the chain gear 21 and the gear reinforcing plate 24 to the crankshaft 6 can be extremely increased.

Further, since the retaining ring 25 and the slope 19 are located inside the space 50 which is axially outer than the inner surface of the chain gear and axially inward than the inner surface of the bulging portion 51, It is difficult for something, such as a chain that has come off the chain gear 21, to get caught on the ring 25 or the slope 19, and the retaining ring 25 is prevented from accidentally coming off from the fitting groove 19.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional front view of this invented device, Fig. 2 is an enlarged sectional view of the main part, and Fig. 3 is a -
The enlarged line sectional view and FIG. 4 are vertical sectional front views of the chain gear and the boss portion of the crank arm. 7, 8...Arm fitting part, 6...Crankshaft,
32, 33... Boss part, 30, 31... Crank arm, 21... Chain gear, 40... Gear receiving part, 18... Concave and convex strip, 41... Gear contact surface (inner end surface of boss part 33), 19 ...Fitting groove, 20...Slope, 25...Retaining ring.

Claims (1)

[Scope of utility model registration request] a crankshaft 6 having arm fitting portions 7, 8 at both ends in the axial direction; a pair of crank arms 30, 31 having boss portions 32, 33 that are removably fitted into the arm fitting portions 7, 8; and; a chain gear 21 provided on the axially inner side of the boss portion 33 of one crank arm 31; and a bicycle gear crank device comprising: a chain gear 21 provided inside the boss portion 33 of one crank arm 31 in the axial direction; A gear receiving part 40 that projects axially inward from the inner end surface of the boss part 33 of one crank arm 31 and has an outer diameter smaller than the outer diameter of the boss part 33 is integrated with the boss part 33. A large number of protrusions 18 are formed along the axial direction on the outer periphery of the gear receiving part 40, and the chain gear 21 can be inserted into and removed from the gear receiving part 40 in the axial direction via the concavo-convex threads 23 and the protrusions 18. The inner end surface of the boss portion 33 serves as a gear contact surface 41 that faces the outer surface of the chain gear 21 and extends outward in the radial direction at right angles to the axial direction. In the case where the center part of the chain gear 21 is
A bulging portion 51 bulges outward in the axial direction from the center portion to the radially outer portion, and the gear contact surface 4
A ring-shaped gear reinforcing plate 24 having a diameter larger than 1 and having a concavo-convex strip 23 formed on the inner circumference is fixedly integrated with the outer surface of the bulge 51, and the concave-convex strip 23 and the convex strip 18 are connected to each other. It is fitted into the gear receiving part 40 through the axially removable and non-rotatably relative to the shaft center, and the axial midway part of each protrusion 18 is notched, and each notched part is connected to the outer periphery of the gear receiving part 40. A single fitting groove 19 is formed by being arranged in parallel along the fitting groove 19, and the axially inner side surface of the notch of each protrusion 18 forming the fitting groove 19 moves outward in the axial radial direction. Accordingly, the slope 20 moves inward in the axial direction, and is axially outward from the inner surface of the chain gear 21,
A space 50 axially inward from the inner surface of the bulging portion 51
Inside, there is a slope 20 and a retaining ring 25 which is elastically expandable and deformable in the radial direction of the shaft and biased in the radial direction.
is positioned, and the retaining ring 25 is fitted in a wedge shape between the slope 20 and the inner surface of the bulged portion 51, and the chain gear 21 is fitted between the retaining ring 25 and the gear contact surface 41.
A screw 10 is formed on the axially outer side of the arm fitting portion 8 to which the gear reinforcing plate 24 is clamped and fixed, and one crank arm 31 is fitted. A bicycle gear crank device characterized in that an arm 31 is fixed to prevent it from coming off from an arm fitting portion 8.