JP2009166672A - Crank device of power-assisted bicycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crank device of a power-assisted bicycle which is capable of reducing the weight of its structure by eliminating the use of any metallic bearing, eliminating any direct contact of metals with each other in the support of a crank shaft, and solving a problem attributable to metal powder, and favorable in cost. <P>SOLUTION: In the crank device of the power-assisted bicycle comprising a shaft hole member 2 and a crank shaft 3 to be rotatably inserted in the shaft hole member 2, two recessed grooves 4, 5 are formed with a space in the axial direction in one of parts to be stored in the shaft hole member 2 out of an inner circumferential surface of the shaft hole member 2 or an outer circumferential surface of the crank shaft 3, ring members 6, 7 brought into slide contact with members on the counter side are fitted in the recessed grooves 4, 5, and lubricating oil 8 is sealed in a space between the ring members 6, 7 in the shaft hole member 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a crank device for an electric bicycle, and more particularly to a device for rotatably supporting a crankshaft.

An electric bicycle has a crankshaft inserted into a shaft hole member (hanger lug) that is rotatably supported by the vehicle body, and the crankshaft is rotatably supported. The power is transmitted to a sprocket mounted on the shaft hole member via a one-way clutch attached to the crankshaft, and it is possible to travel manually by transmitting the rotational power to the rear wheels via a chain. In addition, the electric bicycle can be electrically driven by transmitting the power of the electric motor to a sprocket mounted on the shaft hole member and transmitting the rotational power to the rear wheels via the chain.
When the crankshaft is rotated in the direction opposite to the traveling direction, the rotational power of the crankshaft is cut by the one-way clutch, so that the position adjustment of the pedal can be facilitated.

  In the conventional crank device, a crankshaft is rotatably inserted into a shaft hole member provided in a vehicle body, and the crankshaft is rotatably supported by a bearing incorporated in the shaft hole member. A lubricating oil is filled for lubrication of the bearing, and a seal member for preventing leakage of the lubricating oil is provided at the positions of both end portions of the shaft hole member (see Patent Document 1).

JP-A-10-147281

By the way, since the conventional crank apparatus uses a metal bearing for supporting the crankshaft, the support for the crankshaft has an excessively strong structure.
Further, since the bearing and the seal member of the lubricating oil are used in combination, there is a problem that not only the structure is complicated and the assembly takes time but also the cost is high.
As a means for solving such a problem, it is conceivable to directly support the crankshaft by the shaft hole member and omit the bearing. However, if the crankshaft is directly supported by the shaft hole member, the metal is directly connected to each other. Due to the contact, metal powder due to wear is generated with long-term use, and such metal powder is harmful to the magnetostrictive sensor disposed in the vicinity of the crank device, resulting in a malfunction of the magnetostrictive sensor.
Accordingly, the present invention eliminates the use of metal bearings and simplifies the structure, eliminates the occurrence of direct metal-to-metal contact with the crankshaft support, and solves the problems caused by metal powder. It is an object of the present invention to provide a crank device for an electric bicycle that is also advantageous.

In order to solve the above-mentioned problems, the present invention provides a crank device for an electric bicycle comprising a shaft hole member and a crank shaft that is rotatably inserted into the shaft hole member. A ring member that has two grooves formed in an axial direction on one of the outer peripheral surfaces of the shaft hole member, and that slides against the mating member in the groove. And a configuration in which lubricating oil is sealed in a gap between the ring members inside the shaft hole member.
The two grooved grooves may be formed on either the inner peripheral surface of the shaft hole member or the outer peripheral surface of the crankshaft, and the ring member fitted in the groove is lubricated to fill the internal gap of the shaft hole member. The oil is sealed so that the oil does not leak to the outside, and the lubricating oil filled in the internal clearance of the shaft hole member forms an oil film, preventing direct contact between the metal of the shaft hole member and the crankshaft. Will be reduced.

In the above configuration, the ring member may be formed of a lubricious resin or rubber. Examples of the lubricating resin or rubber include nitrile rubber and fluororubber, and resins having the same effect as these. By making the ring member self-lubricating, sliding between the ring member and the mating member can be performed. The wear resistance of the contacting portion can be improved.
The ring member may be fitted in the concave groove with a tightening margin of 20% to 40%. The setting of the shrinkage rate of 20% or more and 40% or less is a range in which leakage of the lubricating oil enclosed between the ring members on both sides can be surely prevented, and when the shrinkage rate is 20% or less, the ring member The contact force between the mating member and the mating member is reduced, the effect of preventing leakage of the lubricating oil is reduced, and if the shrinkage rate is 40% or more, the O-ring member contracts too much, and the ring member and the mating member The generation of resistance at the sliding contact portion of the member increases.
The lubricating oil may be a low chemical grease with low chemical attack on the ring member, a low dusting grease containing lithium stearate, or a conductive grease containing a conductive material.

According to this invention, the crankshaft that is rotatably inserted into the shaft hole member is fitted into the groove formed in one of the inner peripheral surface of the shaft hole member or the outer peripheral surface of the crankshaft, and the shaft hole member Since the lubricating oil filled in the internal gap is sealed, even if the crankshaft is rotatably supported by the shaft hole member, the oil film of the lubricating oil can suppress the occurrence of direct metal-to-metal contact. Can solve the problem.
Further, by supporting the crankshaft with the shaft hole member, it is possible to omit a conventional metal bearing and seal member, and it is advantageous in terms of cost by slimming the structure of the crank device.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows a crank device 1 of an electric bicycle according to a first embodiment. As shown in FIG. 1, a crankshaft 3 is rotatably inserted into a shaft hole member 2, and an inner periphery of the shaft hole member 2 is shown. Two concave grooves 4 and 5 are formed on the surface at intervals in the axial direction, and ring members 6 and 7 for supporting the crankshaft 3 are fitted into the both concave grooves 4 and 5. The lubricating oil 8 is filled in the bearing gap between the ring members 6 and 7.

  2 shows the crank device 1 and its periphery. As shown in FIG. 2, the shaft hole member 2 is rotatably supported by the vehicle body 9 of the electric bicycle. One end of the shaft hole member 2 is fitted with a reduction gear drive gear 10 connected to an electric motor (not shown), and the other end is fitted with a sprocket 11. Therefore, when the electric motor is operated, the power is transmitted to the sprocket 11 and the chain 12 is rotated, so that electric running can be performed.

  A pedal (not shown) is attached to the crankshaft 3 via cranks 13 and 14 at both ends, and a one-way clutch 15 is attached to a position near one end. The one-way clutch 15 transmits the rotational power of the crankshaft 3 to the drive gear 10 when the crankshaft 3 is rotated in the traveling direction, while the passenger travels the crankshaft 3 by adjusting the position of the pedal. When rotating in the direction opposite to the direction, the rotational power of the crankshaft 3 is cut off so that it is not transmitted to the drive gear 10. Therefore, when the crankshaft 3 is rotated in the traveling direction, the rotational power of the crankshaft 3 is transmitted to the sprocket 11 via the drive gear 10 and rotates the chain 12, so that it can travel manually. On the other hand, when the crankshaft 3 is rotated in the reverse direction, the crankshaft 3 is idled and the rotational power is not transmitted to the sprocket 11, so that the position adjustment of the pedal can be facilitated.

The ring members 6, 7 have a sealing function for sealing the lubricating oil 8 filled in the bearing gap between the ring members 6, 7, and the inner peripheral surface of the ring members 6, 7 is stored in the concave grooves 4, 5. 3 is in sliding contact with the outer peripheral surface.
The ring members 6 and 7 are formed of a lubricious resin or rubber, and examples of the lubricious resin or rubber include nitrile rubber and fluororubber, and resins having the same effect as these. By providing such a property, it is possible to improve the wear resistance of the portion where the ring members 6 and 7 and the crankshaft 3 are in sliding contact with each other.

The ring members 6 and 7 are fitted into the concave grooves 4 and 5 with a tightening allowance of 20% to 40%, and are attached to the shaft hole member 2 so as not to rotate.
The setting of the shrinkage rate 20% or more and 40% or less of the ring members 6 and 7 is a range in which leakage of the lubricating oil 8 enclosed in the bearing gap between the ring members 6 and 7 on both sides can be reliably prevented. When the shrinkage rate is 20% or less, the adhesion force of the sliding contact portion between the ring members 6 and 7 and the crankshaft 3 is reduced, the effect of preventing leakage of the lubricating oil 8 is reduced, and the shrinkage rate is 40% or more. In this case, the ring members 6 and 7 contract too much, and the generation of resistance at the sliding contact portion between the ring members 6 and 7 and the crankshaft 3 increases.

  The lubricating oil 8 forms an oil film between the inner peripheral surface of the shaft hole member 2 and the outer peripheral surface of the crankshaft 3, and wear occurs so that the shaft hole member 2 and the crankshaft 3 do not come into direct metal contact. Is suppressed.

  Since the ring members 6 and 7 are made of a lubricious resin or rubber, a low chemical grease having a low chemical attack on the resin or rubber material is used as the lubricating oil 8, and the ring member 6 is used. , 7 are preferably made difficult to change, and examples of the low chemical grease include synthetic oils such as polyalphaolefins and mineral oils.

As the lubricating oil 8, a low dusting grease containing lithium stearate or a conductive grease containing a conductive material such as carbon black can be used.
As described above, when low dust generation grease is used, the low dust generation component of the grease can suppress the influence on peripheral electronic devices such as the control circuit of the motor that can be placed on the electric bicycle, and the conductive grease can be used. When used, when static electricity is charged in the shaft hole member 2 or the crankshaft 3, the static electricity can be released, and the electrolytic corrosion damage between the shaft hole member 2 and the crankshaft 3 can be prevented.

  Here, in the gap between the inner peripheral surface of the shaft hole member 2 and the outer peripheral surface of the crankshaft 3, for example, the crankshaft 3 has an h5 tolerance, a shaft hole member so that an oil film by the enclosed lubricating oil 8 can be reliably formed. 3 is preferably finished to a tolerance of about G6.

  The crank device 1 of the first embodiment is configured as described above, and the crankshaft 3 is rotatably supported by the shaft hole member 2, and the ring members 6, 7 on both sides are inside the shaft hole member 2. It becomes a seal of the lubricating oil 8 filled in the bearing gap between the ring members 6 and 7 on both sides, and the oil film formation by the lubricating oil 8 eliminates the occurrence of direct contact between the shaft hole member 2 and the crankshaft 3 metal. Thus, generation of wear powder due to contact between metals can be suppressed, and the magnetostrictive sensor in the vicinity of the crank device 1 can be prevented from malfunctioning due to such metal wear powder.

  Further, by forming an oil film with the lubricating oil 8 filled in the bearing gap, even if the crankshaft 3 is supported by the shaft hole member 2, the generation of wear powder due to contact between metals can be suppressed. Even if the members are omitted, the sliding bearing can be configured, and this makes the structure of the crank device slim, which is advantageous in terms of cost.

Next, FIG.1 (b) has shown the crank apparatus of 2nd Embodiment. The same parts as those in the first embodiment will be described using the same reference numerals.
In the crank device according to the second embodiment, concave grooves 22 and 23 are formed at positions near both ends of a portion of the outer peripheral surface of the crankshaft 20 that is accommodated in the shaft hole member 21, and both concave grooves 22 and 23 are formed. The ring members 24 and 25 are fitted and attached to each other, the outer periphery of the ring members 24 and 25 is brought into sliding contact with the inner peripheral surface of the shaft hole member 21, and the bearing gap between the ring members 24 and 25 on both sides inside the shaft hole member 21. The lubricating oil 8 filled in is sealed.
As described above, when the ring members 24 and 25 are fitted and attached to the concave grooves 22 and 23 provided on the outer peripheral surface of the crankshaft 20, the ring members 24 and 25 also rotate integrally when the crankshaft 20 rotates. However, the sliding of the inner peripheral surface of the shaft hole member 21 allows the sealing of the lubricating oil 8 to be maintained.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the crank apparatus of embodiment of this invention, (a) is sectional drawing which shows the crank apparatus of 1st Embodiment which inserted the ring member in the ditch | groove formed in the internal peripheral surface of a shaft hole member. (B) is sectional drawing which shows the crank apparatus of 2nd Embodiment which inserted the ring member in the ditch | groove formed in the outer peripheral surface of a crankshaft. Sectional drawing which shows the crank apparatus of 1st Embodiment, and its peripheral member

Explanation of symbols

2 Shaft hole member 3 Crankshaft 4, 5 Two grooves 6, 7 Ring member 8 Lubricating oil

Claims (6)

  In a crank device for an electric bicycle comprising a shaft hole member (2) and a crankshaft (3) rotatably inserted in the shaft hole member (2), the inner peripheral surface of the shaft hole member (2) or the crankshaft Two grooves (4, 5) are formed in one of the portions of the outer peripheral surface of (3) that fit in the shaft hole member (2) with an interval in the axial direction. 5) A ring member (6, 7) that is in sliding contact with the mating member is fitted into 5), and lubricating oil is inserted into the gap between the ring members (6, 7) inside the shaft hole member (2). A crank device for an electric bicycle characterized by enclosing (8).   The crank device for an electric bicycle according to claim 1, wherein the ring members (6, 7) are made of a lubricious resin or rubber.   The electric bicycle according to claim 1 or 2, wherein the ring member (6, 7) is fitted in the concave groove (4, 5) with a tightening margin of 20% to 40%. Crank device.   The crank of an electric bicycle according to any one of claims 1 to 3, wherein the lubricating oil (8) is a low chemical grease having a low chemical attack on the ring members (6, 7). apparatus.   The crank device for an electric bicycle according to any one of claims 1 to 4, wherein the lubricating oil (8) is a low dusting grease containing lithium stearate.   The crank device for an electric bicycle according to any one of claims 1 to 5, wherein the lubricating oil (8) is a conductive grease containing a conductive material.

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