sprocket

Abstract

To provide a sprocket that not only reduces impact and impact noise caused by contact and seating when a chain and a sprocket engage, but also allows easy setting of conditions when fixing a cushion ring to a side surface of a sprocket body.SOLUTION: A sprocket 100 comprises: a sprocket body 101 having a plurality of teeth formed on its peripheral surface; and a cushion ring 120 provided on at least one side of the sprocket body 101, and having an outer peripheral surface in contact with a link plate of a chain. The cushion ring 120 is fixed to the sprocket body 101 without using an adhesive layer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a sprocket having a plurality of teeth formed on the circumferential surface of a sprocket body and meshing with pins, bushes or rollers of a chain, and having a cushion ring on the side surface of the sprocket body, the outer peripheral surface of which contacts a link plate of the chain.

Background Art

[0002] Conventionally, a chain transmission device that hangs a chain on at least two sprockets on the driving side and the driven side to transmit power has been widely used, and it is desired to reduce the noise level in any application.

[0003] In particular, the impact sound caused by the contact and seating of the pin, bush or roller and the teeth of the sprocket when the chain starts to mesh with the sprocket is a major factor in noise, and reducing this has become an issue for the chain transmission device.

[0004] In addition, the impact at the start of meshing between the pin, bush or roller and the teeth of the sprocket is a factor in vibration, and there are also problems such as causing damage and wear of the chain and sprocket and reducing durability.

[0005] In order to reduce the impact and impact sound caused by contact and seating when the chain and sprocket mesh, a sprocket is known that has a plurality of teeth formed on the circumferential surface of the sprocket body and meshing with pins, bushes or rollers of the chain, and has a cushion ring on the side surface of the sprocket body, the outer peripheral surface of which contacts a link plate of the chain (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

[0007] Incidentally, cushion rings are generally made of thermosetting resins such as cross-linked rubber, but setting the conditions for fixing such rubber cushion rings to the side of the metal sprocket body is difficult. Specifically, first, the surface of the material to be attached is cleaned to remove foreign matter, and then surface treatment is performed by sandblasting or the like. After that, vulcanizing adhesive is applied to the sprocket body, and the cushion ring is fixed by vulcanization molding using a mold while heating, but setting the pre-treatment for applying the adhesive, the bonding treatment itself, and the process control during the vulcanization molding process are difficult. In addition, when removing the mold and deburring is performed, burrs tend to form between the molds (or between the mold and other structures) when using thermosetting resins for vulcanization molding, so the deburring process is also complicated. Therefore, it can be said that the manufacturing process for cushion rings made of thermosetting resins such as rubber is complicated.

[0008] Furthermore, because thermosetting resins like rubber cannot be reused, the entire runner section, including the spool and gate, hardens, leading to an increase in waste materials.

[0009] This invention was made based on the circumstances described above, and its purpose is not only to reduce the impact and noise caused by contact and seating when the chain and sprocket mesh, but also to provide a sprocket that simplifies the setting of conditions when fixing the cushion ring to the side of the sprocket body. [Means for solving the problem]

[0010] To solve the above problems, the present invention provides a sprocket comprising a sprocket body having a plurality of teeth formed on its circumferential surface, and a cushion ring provided on at least one side surface of the sprocket body with its circumferential surface in contact with a link plate of a chain, wherein the cushion ring is fixed to the sprocket body without an adhesive layer. The cushion ring is made of thermoplastic resin, and a side recess is formed on the side of the sprocket body, which is concave relative to the side surface, and the thermoplastic resin is filled into the side recess, and the side recess is a through hole that penetrates both sides of the sprocket body.It is characterized by the following:

[0011] In the present invention, since the cushioning ring is fixed to the sprocket body without an adhesive layer, contact, impact, and noise caused by seating are reduced when the chain and sprocket mesh, and the conditions for fixing the cushioning ring to the side of the sprocket body are simplified. Furthermore, it is preferable that the cushion ring is made of thermoplastic resin. Being made of thermoplastic resin makes it possible to fix it to the sprocket body without using an adhesive. Preferably, a recess is formed on the side surface of the sprocket body, which is concave relative to the side surface, and the thermoplastic resin is filled into the recess. The formation of the recess allows the cushion ring to be firmly fixed, thereby enhancing the vibration damping effect. Preferably, the side recess is a through hole that penetrates both sides of the sprocket body. The formation of the through hole allows the cushion ring to be firmly fixed, thereby enhancing the vibration damping effect.

[0015] Preferably, the cushion rings are provided on both sides of the sprocket body, and through holes are formed that penetrate the sides, with each cushion ring connected to the others by the thermoplastic resin filled in the through holes. By connecting each cushion ring to the others with the thermoplastic resin filled in the through holes, the cushion rings are firmly fixed, and the vibration damping effect can be enhanced.

[0016] It is preferable that multiple through holes are formed. By forming multiple through holes, the cushion ring can be more firmly fixed, and the vibration damping effect can be enhanced.

[0017] Preferably, the through-hole is formed in the same phase as the gate hole formed in the mold for injecting thermoplastic resin into the mold. By forming the through-hole in the same phase as the gate hole, thermoplastic resin can be preferably filled into the through-hole as well, and in particular when cushion rings are provided on both sides of the sprocket body, it is possible to efficiently and preferably allow the thermoplastic resin to flow to the back side.

[0018] The thermoplastic resin is particularly preferably a polyester resin.

[0019] On the outer peripheral surface of the boss portion continuously formed on the sprocket body, a concave portion on the boss portion side that is concave with respect to the outer peripheral surface is formed, and it is preferable that the thermoplastic resin is filled in the concave portion on the boss portion side. By filling the thermoplastic resin in the concave portion on the boss portion side, the cushion ring can be firmly fixed and the vibration damping effect can be enhanced.

[0020] It is preferable to continuously provide the concave portion on the boss portion side and the concave portion on the side surface side. By filling the thermoplastic resin in the concave portion on the side surface side and the concave portion on the boss portion side, the cushion ring can be fixed more firmly and the vibration damping effect can be enhanced.

Advantages of the Invention

[0021] The sprocket of the present invention not only reduces the impact and striking sound during the engagement and seating of the chain and the sprocket, but also fixes the cushion ring to the side surface of the sprocket body without an adhesive layer, so the manufacturing is easy.

Brief Description of the Drawings

[0022] [Figure 1] It is a perspective view showing the outline of the configuration of the sprocket of the present invention. [Figure 2] It is an exploded perspective view showing the relationship between the sprocket body shown in FIG. 1 and the cushion ring. [Figure 3] It is a front view of the sprocket body shown in FIG. 1. [Figure 4] (1)(2) It is a cross-sectional view near the through-hole of the sprocket in the molding process. [Figure 5] It is a perspective view showing another sprocket body. [Figure 6] (1) It is a perspective view showing another sprocket body, (2) It is a front view showing another sprocket body. [Figure 7] It is a perspective view showing another sprocket.

Embodiments for Carrying out the Invention

[0023] Hereinafter, embodiments of the sprocket of the present invention will be described with reference to the drawings. In this embodiment, when describing the same components by distinguishing them based on their position, they will be distinguished by letters of the alphabet.

[0024] As shown in Figures 1 to 4, the sprocket 100, which is the first embodiment of the present invention, comprises a sprocket body 101 having teeth 110 with a plurality of tooth tips 111 and tooth roots 112 formed on its circumferential surface, cushion rings 120 (120A, 120B) provided on each side 102 of the sprocket body 101, the cylindrical outer surface of which contacts the link plate of the chain, and a boss portion 103 extending from the sprocket body 101.

[0025] The cushion ring 120 is fixed in close contact with the side surface 102 without the need for an adhesive layer. The cushion ring 120 is also fixed in close contact with the outer circumferential surface 104 of the boss portion 103 of the sprocket body 101. The sprocket body 101 in this embodiment may be made of any material such as steel or other metals, ceramics, resin, etc., or a composite material thereof.

[0026] In this embodiment, the cushion ring 120 is made of a thermoplastic resin. A thermoplastic resin with high creep strength and rubber elasticity is preferred. Using a thermoplastic resin makes it possible to recycle the runner portion up to the spool and gate, contributing to resource conservation. In this invention, "resin" includes rubber and elastomers. Such a thermoplastic resin is preferably one with a high heat resistance temperature (e.g., 100°C or higher), excellent oil resistance (volume change rate after oil resistance test) (e.g., 50% or less, preferably 30% or less), and low compression set (e.g., 80% or less). For example, a polyester-based resin, particularly a polyester-based elastomer, is preferred as such a thermoplastic resin. Such a polyester-based elastomer is polybutylene terephthalate (PBT: (C) 12 H 12It is preferable to use a thermoplastic elastomer made of O4)n) and polyester, or a thermoplastic elastomer made of acrylic rubber and polyolefin or polyester. In this embodiment, a thermoplastic elastomer made of acrylic rubber and polyester (product name NOFALIOY® TZ660, manufactured by NOF Corporation) is used. This thermoplastic elastomer has a heat resistance temperature of 150°C or higher, an oil resistance (after immersion in IRM903 oil at 150°C for 72 hours) of 10% or less, and a 25% compression set (150°C, 24 hours) of 60% or less, so it can be used more preferably.

[0027] Conventionally, rubber cushion rings were fixed to the sprocket body by blasting and applying adhesive to the sprocket body, followed by molding and vulcanization. However, in this embodiment, since the cushion ring 120 is formed using a thermoplastic resin, which has a higher shrinkage rate than rubber, the cushion ring 120 can be fixed to the sprocket body 101 without using adhesive. Therefore, pre-treatment for applying adhesive and bonding treatment are unnecessary. Furthermore, by forming the cushion ring 120 using a thermoplastic resin, cushioning properties can be obtained over a longer period than when rubber is used, thereby reducing noise and vibration.

[0028] Furthermore, by using a thermoplastic resin as the material for the cushion ring 120, material recycling is possible, which is not possible with thermosetting resins such as rubber. Moreover, thermoplastic resins have the advantage of being less prone to deformation because they possess temperature dependence, heat aging resistance that can withstand the harsh conditions inside the engine, and oil resistance, making them a preferable choice.

[0029] Furthermore, while the molding and vulcanization process when using rubber is time-consuming, in this embodiment, as described later, the process is shortened because it is formed by injection molding, and there is no need to set complex process conditions for molding and vulcanization. In addition, when using rubber, a lot of burrs are generated between the molds during the molding and vulcanization process, but when forming the cushion ring 120 using thermoplastic resin, the generation of burrs can be suppressed because it is formed by injection molding, and the time required to remove burrs is short.

[0030] Each side surface 102 of the sprocket body 101 has a through hole 130 that penetrates through the side surface 102. In this embodiment, these through holes 130 are used when forming the cushion ring 120, and will be described in more detail later.

[0031] The through-holes 130 are circular in shape when viewed from the front. In this embodiment, five through-holes 130 are formed. The shape and number of through-holes are not particularly limited, but as will be described later, they can be set according to the type of thermoplastic resin that makes up the cushion ring 120. For example, if the heated thermoplastic resin has low fluidity (high viscosity), the hole diameter may be made larger to facilitate the flow of the thermoplastic resin into the mold 200B. Alternatively, the through-holes 130 may be made larger to form a larger connecting portion 121 (described later), thereby firmly connecting the cushion ring 120A and the cushion ring 120B.

[0032] Here, we will describe the process of forming cushion rings 120 on both sides 102 of the sprocket body 101.

[0033] First, the molding process is performed. The molding process is an injection molding process of thermoplastic resin. As shown in Figure 4(1), in the molding process, molds 200A and 200B, which are configured to conform to the desired shape of the cushion ring 120, are installed on each of the side surfaces 102 of the sprocket body 101. The mold 200 is open on the side surfaces 102 and on the outer circumferential surface 104 of the boss portion 103. In addition, a gate hole 201 is formed in mold 200A. This gate hole 201 is in the same phase position as the through hole 130. That is, the through hole 130 and the gate hole 201 are provided in the sprocket body 101 so that they face each other when viewed from the front.

[0034] Then, the heated and melted thermoplastic resin E is injected into the gate hole 201 within the mold 200A. At this time, since the mold 200B does not have a gate hole 201, the thermoplastic resin does not flow directly into the mold 200B. However, the thermoplastic resin E flows into the mold 200B from the mold 200A side through the through hole 130. By providing the through hole 130 in this way, the thermoplastic resin E can be injected into the mold 200 from only one side, and the inside of the mold 200 can be filled with thermoplastic resin E.

[0035] Furthermore, in this embodiment, each through-hole 130 is formed facing each gate hole 201, so that the thermoplastic resin E flowing in from the gate hole 201 can easily flow from the mold 200A side through the through-hole 130 to the mold 200B side. In this embodiment, each through-hole 130 is formed facing each gate hole 201, but this is not the only way. If at least one through-hole 130 is provided, it is not necessary to directly inject the molten thermoplastic resin E into the mold 200B side. Also, if at least one through-hole 130 faces the gate hole 201, it is preferable because the thermoplastic resin E can easily flow from the mold 200A side through the through-hole 130 to the mold 200B side.

[0036] In this way, the molten thermoplastic resin E flows into the mold 200 and is cooled, causing the thermoplastic resin to solidify, thereby forming the cushion ring 120 fixed to the sprocket body 101. After the cushion ring 120 is formed, the mold 200 is removed, any burrs are removed, and the cushion ring 120 made of thermoplastic resin can be formed and fixed to the sprocket body 101 at the same time as shown in Figure 4(2). Thus, in this embodiment, through holes 130 are provided so that cushion rings 120 can be formed simultaneously on each side 102 of the sprocket body 101.

[0037] Furthermore, as thermoplastic resin E flows from mold 200A to mold 200B through the through holes 130, the thermoplastic resin E that constitutes the cushion ring 120 is filled into each through hole 130 during the formation of the cushion ring 120, thereby forming a connecting portion 121 within the through hole 130. Both ends of this connecting portion 121 are integrally connected to the cushion ring 120 provided on the side surface 102. In other words, the cushion ring 120A and the cushion ring 120B are connected by this connecting portion 121. By connecting the cushion ring 120A and the cushion ring 120B through the connecting portion 121 formed within the through holes 130, the cushion ring 120 is more firmly fixed to the sprocket body 101. This further reduces noise and vibration.

[0038] Furthermore, when removing the mold 200, the thermoplastic resin solidified at the gate hole 201 is cut, and at this time, a cut mark along the shape of the gate hole 201 remains as a protrusion on the surface of the cushion ring 120A. This protrusion can be used for alignment when attaching the sprocket 100 of this embodiment to, for example, a crankshaft or the like.

[0039] The present invention is not limited to the embodiments described above. For example, although the cushion rings 120 are provided on both sides of the sprocket body 101, the invention is not limited to this and only needs to be provided on at least one side 102. In this case, the through holes 130 function as air holes during injection molding. Furthermore, materials other than thermoplastic resin may be used as long as the cushion rings 120 can be fixed to the side 102 of the sprocket body 101 without an adhesive layer.

[0040] Furthermore, in order to enhance the vibration damping effect of the cushion ring 120, a recess 301 that is concave relative to the outer surface 104 of the boss portion 103 may be provided, as shown in Figure 5. By providing the recess 301 in this way, the cushion ring 120 is formed by fitting into the recess 301, so it is fixed more firmly, vibration is suppressed and the vibration damping effect can be enhanced. In the modified example shown in Figure 5, the recesses 301 shown in the figure are facing each other, but they may be provided offset so that they do not face each other. Also, multiple recesses 301 may be provided. Similarly, a side recess (side recess) that is concave relative to the side surface 102 may be formed on the side surface 102 of the sprocket body 101, and thermoplastic resin may be filled into this side recess. In this case as well, the cushion ring 120 is formed by fitting into the side recess, so it is fixed more firmly, its thickness is increased, vibration is suppressed and the vibration damping effect can be enhanced. Alternatively, for example, only one cushion ring 120 may be provided, and only a side recess may be provided on the side surface 102 of the sprocket body 101, without providing a through hole 130.

[0041] Furthermore, in order to enhance the vibration damping effect of the cushion ring 120, the recess 301 and the through hole 130 shown in Figure 5 may be provided in a continuous manner. In the modified examples shown in Figures 6 and 7, a through groove 302 is formed in the sprocket body 101. The through groove 302 is provided across the outer circumferential surface 104 and flange portion 105 of the boss portion 103 on both sides of the sprocket body 101. More specifically, the through groove 302 consists of a groove portion 303 formed on the outer circumferential surface 104 of the boss portion 103, which is concave relative to the outer circumferential surface 104; a hole portion 304 that is continuous from the groove portion 303 and penetrates the sprocket body 101; and a notch portion 305 that is continuous from the groove portion 303 and formed in the flange portion 105, which is concave relative to the flange portion 105. In the modified examples shown in Figures 6 and 7, three through grooves 302 are provided in the sprocket body 101, but the invention is not limited to this.

[0042] When the through groove 302 is formed in this manner, as shown in Figure 7, thermoplastic resin is also filled into the through groove 302 to form the cushion ring 120. In this case, the through hole 130 can be made larger than in the case shown in Figure 5 above, and as a result the cushion ring 120 is more firmly fixed to the sprocket body 101, thereby improving the vibration damping effect. In the modified examples shown in Figures 6 and 7, the through groove 302 has a hole 304, but it may be a side recess as described above instead of a hole penetrating the sprocket body 101.

[0043] The embodiments and modifications described above are provided to facilitate understanding of the present invention and are not intended to limit it. Accordingly, each element disclosed in the above embodiments and modifications is intended to include all design changes and equivalents that fall within the technical scope of the present invention. [Explanation of Symbols]

[0044] 100 sprocket 101 Sprocket body 102 Side view 103 Boss Section 104 Outer surface 110 teeth 111 Tooth tip 112 Root of tooth 120 Cushion Rings 121 Connection part 130 Through hole 200 molds 201 Gate Hole 301 Recess 302 Through groove E Thermoplastic resin

Claims

1. A sprocket having a sprocket body with multiple teeth formed on its circumferential surface, and a cushion ring provided on at least one side of the sprocket body, the outer surface of which contacts the link plate of the chain, The cushioning ring is fixed to the sprocket body without an adhesive layer. The cushion ring is made of thermoplastic resin. A side recess is formed on the side surface of the sprocket body, and the thermoplastic resin is filled into the side recess. The sprocket is characterized in that the side recess is a through hole that penetrates both sides of the sprocket body.

2. The cushion ring is provided on both sides of the sprocket body, and the through hole is formed therethrough through the side, The sprocket according to claim 1, characterized in that each cushioning ring is connected to one another by the thermoplastic resin filled in the through hole.

3. The sprocket according to claim 1, characterized in that a plurality of through holes are formed.

4. The sprocket according to claim 1, characterized in that the thermoplastic resin is a polyester resin.

5. The sprocket according to claim 1, characterized in that a boss-side recess, which is concave with respect to the outer circumferential surface of the boss portion formed continuously with the sprocket body, is formed thereon, and the thermoplastic resin is filled into the boss-side recess.

6. The sprocket according to claim 5, characterized in that the boss-side recess and the side-side recess are provided in a continuous manner.

Images