JPH0389060A - Change tooth type sprocket - Google Patents

Abstract

PURPOSE:To minimize the pitch of teeth and make the diameter of a sprocket small by forming protrusions, expanded on the peripheral sides, at the peripheral part of a sprocket body, and fitting change pieces, with teeth formed at the peripheral parts, at the protrusions through grooves so as to be connected. CONSTITUTION:Protrusions 5 expanded on the peripheral sides are formed at the peripheral part of a sprocket body 1 circumferentially at the specified pitch. Grooves 9a formed at the inner peripheral parts are fitted into the protrusions 5 so as to fit many change pieces 8. A tooth 10 protruding radially outward is formed at the peripheral part of the change piece 8. The change piece 8 is fitted at the protrusion 5 through the groove 9a so as to be connected. The pitch of teeth is thus minimized as well as the diameter of the sprocket can be made small.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a tooth-changeable sprocket in which teeth on the outer periphery are removably attached to a sprocket body.

(Prior Art) As a conventional technology, there is a structure described in Japanese Patent Publication No. 61-28862.

That is, as shown in FIG. 11, dovetail groove-shaped notches 32 whose width is narrower on the outer circumferential side are formed at equal pitches in the circumferential direction on the outer circumference of the disc-shaped sprocket main body 31.

33 is a plate-shaped replacement piece that fits into the notch 32.

As shown in FIGS. 11 and 12, this replacement piece 33 consists of a pair of divided pieces 33a having the same shape and divided in the thickness direction.
are stacked on top of each other and connected with pins, and each divided piece 33
a has step-shaped flanges 33b formed on both left and right edges and a bottom edge to engage with the left and right peripheral walls and the bottom wall of the notch 32, and teeth portions 34 at both left and right ends protruding outward in the radial direction on the outer periphery. , the intermediate portion forms a valley portion 35 recessed in the axial direction.

The replacement piece 33 is constructed by overlapping the pair of divided pieces 33a from both sides at the notch 32 of the sprocket body 31, and engaging the flanges 33b with the left and right peripheral walls and the bottom wall of the notch 32, so that the two pieces are separated. Some have a structure in which they are fixed to the sprocket body 31 by connecting with a pin.

(Problems to be Solved by the Invention) In the above-mentioned conventional device, a notch 32 recessed in the axial direction is formed on the outer circumference of the sprocket body 31 so that the replacement piece 33 is fitted and locked to the sprocket body 31. Therefore, there was a drawback that it was difficult to reduce the pitch of the teeth or reduce the diameter of the sprocket.

The object of the present invention is to obtain a new tooth-replaceable sprocket that eliminates the above-mentioned drawbacks.

(Means for Solving the Problems) In order to achieve the above object, the present invention is configured as follows.

That is, protrusions that widen on the outer periphery of the sprocket body are formed at a predetermined pitch in the circumferential direction on the outer periphery of the sprocket body, and a large number of replacement pieces are attached to the protrusions by fitting grooves formed on the inner periphery. , and teeth projecting radially outward are formed on the outer periphery of the replacement piece.

Furthermore, protrusions that widen on the outer circumferential side are formed at a predetermined pitch in the circumferential direction on the outer circumference of the sprocket body.

In addition, a recessed portion recessed in the axial direction is formed in the circumferentially intermediate portion of each protrusion, and a number of replacement pieces are attached to the protrusion by fitting grooves formed on the inner circumference, and the replacement pieces are The outer peripheral portion is configured to have teeth whose circumferential ends protrude radially outward, and a circumferential center portion which is recessed in the axial direction.

Further, the replacement piece is divided in the thickness direction and has a groove formed in the inner peripheral portion of the divided surface to fit with the projection.

(Function) Since the present invention has the above configuration, each replacement piece is
The sprocket protrudes radially outward from the outer periphery of the sprocket body, and teeth are formed in this portion. Further, since the replacement piece engages with the sprocket body through the protrusion and groove that widen on the outer circumferential side, the replacement piece engages firmly against a radially outward load.

In addition, teeth are formed along the outer shape of the protrusion where the circumferential middle part of each protrusion is recessed in the axial direction, and the number of teeth increases and the thickness of the replacement piece becomes thinner. This results in a reduction in the amount of material used to form the structure.

Further, when the replacement piece is connected and divided in the thickness direction, the replacement piece is connected to and detached from the sprocket body.

(Example) Embodiments of the present invention will be described below based on the drawings.

In the drawings, FIGS. 5 to 7 show the first embodiment of the present invention, the first construction drawing is a partial front view, FIGS. 2 and 3 are sectional views along FIG. 4 is a partially sectional side view of one of the replacement pieces, and FIGS.

In FIG. 1, reference numeral 1 denotes a tooth-replaceable sprocket, in which a large number of replacement pieces 8 each having teeth 10 are attached to the outer periphery of a sprocket body 2. As shown in FIG.

The sprocket main body 2 is formed by integrally molding a large-diameter, disc-shaped hub 4 on the outer periphery of a boss 3 that fits on the shaft.

The hub 4 is made of 5S41 material and integrally has a large number of protrusions 5 projecting radially outward on its outer periphery. The protrusions 5 are formed of a set of a first protrusion 5a and a second protrusion 5b whose outer peripheral side expands in the circumferential direction, and for example, 11 sets are formed at equal intervals in the circumferential direction.

6 and 7 are equal-width recesses and expanding recesses formed on the outer periphery of the hub 4 by the projections 5, and the equal-width recesses 6 have approximately equal convergence toward the outer periphery between the respective projections 5. Also, the expansion recess 7
is formed between each first protrusion 5a and second protrusion 5b so that the width gradually increases toward the outer periphery.

Replacement pieces 8 are attached to each of the projections 5, respectively.

This replacement piece 8 is made of stainless steel v! It is made of fR (SUS2), and has two teeth 1o protruding outward in the radial direction on the outer periphery, that is, a first tooth 10a and a second tooth lOb, and one trough 11 recessed in the axial direction between them. has. Note that the pitch between the first teeth 10a and the second teeth 10b is half the pitch of the chain 12.

As shown in FIGS. 2 and 3, the replacement piece 8 is made by connecting a pair of divided pieces 9, which are both formed in the same shape, so as to be divisible in the thickness direction. The inner periphery of the dividing surface 9 has a groove 9a that fits into the aforementioned protrusion 5 and the outer periphery of the hub 4. In this case, as shown in FIG. 1, the first tooth 10a and the second tooth 10b are made to correspond to the above-mentioned I-th protrusion 5a and second protrusion 5b, and the first tooth 10a and the second tooth 10b are made to correspond to each other. The groove 9a on the inner peripheral portion is made deep to allow the first projection 5a and the second projection 5b to fit therein.

Further, as shown in FIGS. 4 to 7, the divided piece 9 has a screw shaft 9b protruding toward the opposite side in the thickness direction and a screw hole 9C penetrating in the thickness direction formed at both ends in the circumferential direction. The two divided pieces 9 are made to face each other, and as shown in FIG. 3 and FIG.
The nuts 8d are screwed onto each screw shaft 9b and tightened.

As a result, the opposed divided pieces 9 are connected in the thickness direction, and the groove 98 holds the protrusion 5 and the outer periphery of the hub 4 to form the replacement piece 8. In this case, the opposing divided pieces 9, 9 are slightly shifted in the circumferential direction, and the step portions 8a, 8a are
These stepped portions 8a engage the circumferentially adjacent replacement pieces 8 in a staggered manner as shown in FIG.

As a result, eleven first teeth 10a (first
tooth group) and 11 second teeth 10b (second tooth group), which are also arranged at substantially equal pitches to the pitch of the chain 12.
A total of 22 teeth 10 are arranged alternately and at regular intervals in the circumferential direction.

Next, the manner of use of the above embodiment will be explained.

First, as shown in FIG.
When the replaceable sprocket 1 is rotated by meshing with the valley portion 11a on the power transmission side of a.

Each first tooth 10a meshes with the chain 12 once every time the tooth-changing sprocket 1 rotates upward.

On the other hand, each second tooth 10b does not mesh with the chain 12 and rotates idly.

For this reason, when the first tooth 10a comes into contact with the chain 12, the coating on the contact portion is peeled off, and the first tooth 10a is gradually worn and corroded.

However, since the second tooth 10b is protected by the film, the initial state will be maintained. Then, when the wear of the first tooth 10a reaches a predetermined value, the chain 12 is reattached to the valley portion 11b on the power transmission side of the second tooth 10b.

Then, the second tooth 10b meshes with the chain 12 once every rotation of the replaceable sprocket 1, and the first tooth 10a does not mesh with the chain 12.
You will end up idling. Thereby, use of the replaceable sprocket l can be continued until the second teeth 10b are worn out.

In addition, since the replacement piece 8 is engaged with the sprocket body 2 by the protrusion 5 whose outer peripheral side expands and the groove 9a,
It is firmly engaged against radially outward loads and will not fall off.

In addition, if a specific tooth YO is damaged during use or each tooth 10 is worn out, replace the corresponding replacement piece 8 or all the replacement pieces 8 with new ones to make the tooth 10 new. .

Note that the present invention may be implemented as shown in FIGS. 8 to 10.

First, FIG. 8 shows a second embodiment, in which each protrusion 5 (first protrusion 5a, second protrusion 5b) is formed in the same manner as in FIG.
) A curved piece 13 projecting outward in the radial direction is formed at the intermediate portion between the two, and a fastening gap 14 is formed between this curved piece 13 and each projection 5.

Then, a replacement piece 15 consisting of a pair of divided pieces that can be separated in the thickness direction is attached to the projection 5.

The replacement piece 15 has two teeth 16 and 17 formed on its outer periphery, and a groove 18 that fits closely with the protrusion 5 on the inner periphery of the divided surface and fits into the peripheral wall of the gap 14. The divided pieces facing each other at the gap 14 are integrally connected by bolts and nuts 19.

Further, FIG. 9 shows a third embodiment, in which the hub 4
Fan-shaped protrusions 20 whose outer circumferential side is wider are formed at a predetermined pitch in the circumferential direction on the outer periphery of the holder, and a replacement piece 21 consisting of a pair of divided pieces that can be separated in the thickness direction is attached to each of these protrusions 20.

The replacement piece 21 has a trough 22 formed by recessing the outer peripheral part of the circumferential center facing the protrusion 20 in the axial direction, and extends both circumferential end parts exposed left and right from each protrusion 20 radially outward. Half teeth 23a and 23b are formed by protruding from the hub 4, and a groove 24 is formed on the inner periphery of the divided surface to fit closely with the protrusion 20 and to fit into the outer periphery of the hub 4. .

Both circumferential ends of the replacement piece 21 fitted into each protrusion 20 are brought close to each other, and - teeth 23 are formed by the teeth 23a and 23b of the two adjacent replacement pieces. Note that 25 is a bolt/nut that connects the pair of divided pieces in the thickness direction.

Further, FIG. 10 shows a fourth embodiment, in which fan-shaped projections 26 similar to those shown in FIG. A replacement piece 2-7 consisting of a pair of split pieces that can be separated in the horizontal direction is attached.

The replacement piece 27 has teeth 28 formed by protruding the outer peripheral part of the circumferential center facing the protrusion 26 radially outward, and both circumferential end parts exposed left and right from each protrusion 26 radially inward. Further, a groove 29 is formed on the inner periphery of the dividing surface to closely fit with the protrusion 26 and to fit on the outer periphery of the hub 4.

Then, both ends in the circumferential direction of the replacement piece 27 fitted into each projection 26 are brought close to each other, and - number of valleys 30 are formed by the adjacent ends.

(Effects of the Invention) As is clear from the above description, the present invention forms a protrusion that expands on the outer circumference side on the outer circumference of the sprocket body, and inserts a replacement piece having teeth on the outer circumference into the protrusion through a groove. Since the replacement piece can be firmly engaged with the sprocket body, it is also possible to reduce the tooth pitch and increase the number of teeth, or when the sprocket body has a small diameter. Replacement pieces can be easily installed.

In addition, since the teeth are formed along the outer shape of the protrusion whose circumferential middle part is recessed in the axial direction, the number of teeth increases and the thickness of the replacement piece becomes thinner, making it difficult to use the material that forms the replacement piece. reduced and cheaper.

Further, since the replacement piece is connected and divided in the thickness direction and connected to and detached from the sprocket body, it is possible to easily replace the replacement piece.

[Brief explanation of drawings]

FIG. 1 is a partial front view showing an embodiment of the present invention, FIGS. 2 and 3 are sectional views of the same, and FIG. 4 is a partial sectional side view of one of the replacement pieces. Figures 5 to 7 are the V
-V to ■-■ cross-sectional views, Figures 8 to 10 are respectively 2nd
FIG. 10 is a partial front view showing a conventional example, and FIG. 12 is a plan view thereof. 1: Replaceable sprocket, 2: Replaceable sprocket body, 3: Boss, 4: Hub, 5: Protrusion, 5a: First protrusion, 5
b: Second protrusion, 6: Equal width recess, 7: Expanding recess, 8: Replacement piece, 8a: Step, 9: Divided piece, 9a: Groove, 9b: Screw shaft, 9c: Screw hole, 9d: Nut , 10: tooth, 10a:
lth tooth (first tooth group), 10b: second tooth (second tooth group), : valley, 12: chain. Applicant Hisashi Matsumoto Figure 0 Figure 2 Figure 2 Figure 2 Figure Procedure Amendment (Method) % Formula % 1. Indication of the Case 1999 Patent Application No. 74489 2. Name of the invention Interchangeable sprocket 3. Relationship with the person making the amendment Patent applicant address: King of 547 Horinouchi, Kikuyo-cho, Ogasa-gun, Shizuoka Name: Asahi Chick Co., Ltd. Representative: Ichinosuke Oka 4, Agent 6゜7゜August 28, 1990 (Delivery date) Subject of amendment (1) Contents of amendment 1 in the brief explanation of the drawings section of the specification, page 14, line I2 of the specification: “... 10th
The phrase ``The figure is conventional'' has been corrected to ``...Figure 11 is conventional.''

Claims (1)

[Claims] 1. Protrusions that widen on the outer circumferential side of the sprocket body are formed at a predetermined pitch in the circumferential direction, and grooves formed on the inner circumferential part are fitted into the protrusions to form a large number of protrusions. 1. A tooth-replaceable sprocket, characterized in that a replacement piece is attached, and teeth projecting radially outward are formed on the outer periphery of the replacement piece. 2. On the outer periphery of the sprocket body, protrusions that widen on the outer periphery side are formed at a predetermined pitch in the circumferential direction, and a recess that is concave in the axial direction is formed in the circumferential middle part of each protrusion, and the inner periphery is A large number of replacement pieces are attached by fitting grooves formed in the part, and each of the replacement pieces has teeth on the outer periphery that protrude radially outward at both circumferential ends, and teeth that protrude radially outward at both ends in the circumferential direction, and teeth that protrude radially outward in the circumferential center part. A tooth-replaceable sprocket characterized by forming a concave valley. 3. The replaceable tooth type sprocket according to claim 2, wherein the replacement piece is divided in the thickness direction, and a groove that fits into the protrusion is formed on the inner peripheral part of the divided surface.