Sprocket and power transmission device

Abstract

To realize a sprocket capable of engaging with a chain of a spiral structure in which a plurality of links is connected in a spiral manner.SOLUTION: A sprocket 10 comprises: a plurality of first sprocket teeth 12a that engages with links 120, 130 of a chain 110; and a plurality of second sprocket teeth 14a spaced apart from the first sprocket teeth 12a in an extension direction of a rotational center line C0 of the sprocket 10 and engaging with the links 120, 130. Each of the first sprocket teeth 12a includes a first contact part that is in contact with the links 120, 130 on a forward rotation direction R1 side of the sprocket 10, and also includes a first relief part that avoids contact with the links 120, 130 on a reverse rotation direction R2 side. Each of the second sprocket teeth 14a includes a second contact part that is in contact with the links 120, 130 on the reverse rotation direction R2 side of the sprocket 10, and also includes a second relief part that avoids contact with the links 120, 130 on the forward rotation direction R1 side.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present disclosure relates to a sprocket and a power transmission device. [Background technology]

[0002] For example, various types of chains that engage with sprockets are known, such as roller chains and silent chains. Meanwhile, a new chain, a spiral chain, is described in Patent Document 1. In the spiral chain described in Patent Document 1, a plurality of links are rotatably connected in series to form a spiral link assembly that extends in a spiral shape. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent application No. 2023-064977 Summary of the Invention [Problem to be solved by the invention]

[0004] However, a sprocket suitable for a chain having a spiral structure in which a plurality of links are connected in a spiral shape, as described in Patent Document 1, has not yet been proposed.

[0005] Therefore, an object of the present disclosure is to realize a sprocket that can engage with a chain having a spiral structure in which multiple links are connected in a spiral shape. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, according to one aspect of the present disclosure, A sprocket that can be engaged with a spiral chain having a plurality of links connected in a spiral shape, a first plurality of sprocket teeth engaging the links of the chain; a plurality of second sprocket teeth spaced apart from the first sprocket teeth along a centerline of rotation of the sprocket and adapted to engage the links of the chain; Each of the first sprocket teeth has a first contact portion on a forward rotation side of the sprocket that contacts the link of the chain, and a first relief portion on a reverse rotation side of the sprocket that avoids contact with the link of the chain, A sprocket is provided in which each of the second sprocket teeth has a second contact portion on the reverse direction side of the sprocket that contacts the link of the chain, and a second relief portion on the forward direction side that avoids contact with the link of the chain.

[0007] According to another aspect of the present disclosure, A chain having a spiral structure in which a plurality of links are connected in a spiral shape; a sprocket engageable with the chain; The chain is a first plurality of sprocket teeth engaging the links of the chain; a plurality of second sprocket teeth spaced apart from the first sprocket teeth along a centerline of rotation of the sprocket and adapted to engage the links of the chain; Each of the first sprocket teeth has a first contact portion on a forward rotation side of the sprocket that contacts the link of the chain, and a first relief portion on a reverse rotation side of the sprocket that avoids contact with the link of the chain, A power transmission device is provided in which each of the second sprocket teeth has a second contact portion on the reverse direction side of the sprocket that contacts the link of the chain, and a second relief portion on the forward direction side that avoids contact with the link of the chain. Effect of the Invention

[0008] According to the present disclosure, it is possible to realize a sprocket that can engage with a chain having a spiral structure in which a plurality of links are connected in a spiral shape. [Brief description of the drawings]

[0009] [Figure 1A] FIG. 1 is a right-front perspective view of a sprocket with an example chain engaged therewith, in accordance with one embodiment of the present disclosure; [Figure 1B] FIG. 1 is a left-front perspective view of a sprocket with an example chain engaged therewith, in accordance with one embodiment of the present disclosure; [Diagram 2] FIG. 1 is a perspective view of a portion of an example chain. [Diagram 3] Top view of an example chain section [Figure 4] FIG. 2 is an exploded perspective view of a portion of an example chain. [Figure 5A] FIG. 1 is a perspective view of a number of first links in an example chain connected together; [Figure 5B] FIG. 1 is a front view of a plurality of first links (first spiral link connectors) in an example chain connected together; [Figure 5C] FIG. 1 is an exploded perspective view of a plurality of first links in an example chain; [Figure 6A] FIG. 1 is a perspective view of a plurality of second links in an example chain connected together; [Figure 6B] FIG. 1 is a front view of a plurality of second links (second spiral link connections) in an example chain connected together; [Figure 6C] FIG. 1 is an exploded perspective view of a plurality of second links in an example chain; [Figure 7] FIG. 1 is a perspective view of a first and second helical link assembly forming a double helix structure in an example chain; [Figure 8] FIG. 1 is a perspective view showing a first and a second link in an example chain connected via a connecting member; [Figure 9] FIG. 1 is an exploded perspective view illustrating the connection of a plurality of first and second links via a plurality of connecting members in an example chain; [Figure 10A] A cross-section of an example chain taken along line S1-S1 shown in Figure 2. [Figure 10B]A cross-section of an example chain taken along line S2-S2 shown in Figure 2. [Figure 11A] FIG. 1 is a perspective view of a portion of an example chain bending to one side in the width direction; [Figure 11B] FIG. 13 is a perspective view showing a portion of an example chain bending to the other side in the width direction; [Figure 11C] FIG. 1 is a perspective view of a portion of an example chain bending to one side in the thickness direction; [Figure 11D] FIG. 13 is a perspective view of a portion of an example chain bending in the other direction in the thickness direction; [Figure 12A] Right front perspective view of the sprocket [Figure 12B] Left front perspective view of the sprocket [Figure 13A] Right side view of sprocket [Figure 13B] Left side view of sprocket [Figure 14] Front view of sprocket [Figure 15A] Exploded perspective view of a sprocket [Figure 15B] FIG. 15B is an exploded perspective view of the sprocket, taken from a different angle than that of FIG. 15A. [Figure 16A] FIG. 1 is a right side view of a sprocket with an example chain engaged therewith; [Figure 16B] FIG. 1 is a left side view of a sprocket with an example chain engaged therewith; [Figure 17] FIG. 1 is a perspective view showing contact between first and second links and first and second sprocket teeth for one cycle of an example chain; [Figure 18] FIG. 1 is a partial cross-sectional view of an example sprocket engaged with a chain. [Figure 19A] FIG. 13 is a right-front perspective view of an alternative embodiment sprocket with an alternative chain engaged therewith; [Figure 19B] FIG. 13 is a left front perspective view of an alternative embodiment sprocket with an alternative chain engaged therewith; [Figure 20] FIG. 1 is a perspective view of a portion of a chain according to another embodiment; [Figure 21] FIG. 13 is an exploded perspective view of a portion of a chain according to another embodiment of the present invention; [Figure 22A]FIG. 11 is a front view of a plurality of first links (first spiral link connectors) connected to each other in a chain according to another embodiment of the present invention; [Figure 22B] FIG. 13 is a front view of a plurality of second links (second spiral link connectors) connected to each other in a chain according to another embodiment of the present invention; [Figure 23A] 20 is a cross-sectional view of another example of a chain taken along the line S3-S3 shown in FIG. [Figure 23B] 20 is a cross-sectional view of another example of a chain taken along the line S4-S4 shown in FIG. [Figure 24A] FIG. 13 is a right-front perspective view of yet another embodiment of a sprocket with yet another example chain engaged therewith; [Figure 24B] FIG. 13 is a left front perspective view of yet another embodiment of a sprocket with yet another example chain engaged therewith; [Diagram 25] FIG. 13 is a perspective view of a portion of a further example of a chain; [Figure 26] FIG. 13 is an exploded perspective view of a portion of a further example of a chain. [Figure 27A] FIG. 13 is a front view of a plurality of first links (first spiral link connectors) connected to each other in a chain according to another embodiment of the present invention; [Figure 27B] FIG. 13 is a front view of a plurality of second links (second spiral link connectors) connected to each other in a chain according to another embodiment of the present invention. [Figure 28] FIG. 13 is an exploded perspective view illustrating the connection of a plurality of first and second links via a plurality of connecting members in a chain according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] A sprocket according to one embodiment of the present disclosure is a sprocket capable of engaging with a spiral chain in which a number of links are connected in a spiral shape, and includes a number of first sprocket teeth that engage with the links of the chain, and a number of second sprocket teeth that are spaced apart from the first sprocket teeth in the direction of extension of the center line of rotation of the sprocket and engage with the links of the chain, each of the first sprocket teeth having a first contact portion on the forward rotation direction side of the sprocket that contacts the link of the chain, and a first relief portion on the reverse rotation direction side that avoids contact with the link of the chain, and each of the second sprocket teeth having a second contact portion on the reverse rotation direction side of the sprocket that contacts the link of the chain, and a second relief portion on the forward rotation direction side that avoids contact with the link of the chain.

[0011] According to this aspect, it is possible to realize a sprocket that can be engaged with a chain having a spiral structure in which a plurality of links are connected in a spiral shape.

[0012] For example, the first contact portion may be a flat surface facing in the forward rotation direction and outwardly of the sprocket, and the second contact portion may be a flat surface facing in the reverse rotation direction and outwardly.

[0013] For example, the sprocket may have a guide member that faces the chain in the extension direction of the rotation center line when the chain is engaged with the sprocket and guides the chain.

[0014] For example, the sprocket may have a first rotating body including a disk-shaped first main body portion and a plurality of the first sprocket teeth arranged along the outer periphery of the first main body portion, a second rotating body including a disk-shaped second main body portion and a plurality of the second sprocket teeth arranged along the outer periphery of the second main body portion, and a spacer arranged between the first rotating body and the second rotating body to space the first sprocket teeth and the second sprocket teeth from each other in the direction of extension of the rotation center line.

[0015] For example, the chain may include a plurality of first links rotatably connected to each other to form a first spiral link assembly extending in a spiral, a plurality of second links rotatably connected to each other to form a second spiral link assembly extending in a spiral, and a plurality of connecting members connecting corresponding first links and second links, respectively, to connect the first and second spiral link assembly to form a double spiral structure, wherein the plurality of first sprocket teeth alternately contact the first links and the second links, and the plurality of second sprocket teeth alternately contact the first links and the second links.

[0016] For example, the sprocket may have markers that indicate the spiral direction of the chain as it engages the first and second sprocket teeth.

[0017] A power transmission device of another embodiment of the present disclosure includes a chain having a spiral structure in which a number of links are connected in a spiral shape, and a sprocket engageable with the chain, wherein the chain includes a number of first sprocket teeth that engage with the links of the chain, and a number of second sprocket teeth that are spaced apart from the first sprocket teeth in the direction of extension of the center line of rotation of the sprocket and engage with the links of the chain, each of the first sprocket teeth has a first contact portion on the forward rotation direction side of the sprocket that contacts the link of the chain, and a first relief portion on the reverse rotation direction side that avoids contact with the link of the chain, and each of the second sprocket teeth has a second contact portion on the reverse rotation direction side of the sprocket that contacts the link of the chain, and a second relief portion on the forward rotation direction side that avoids contact with the link of the chain.

[0018] According to this aspect, it is possible to realize a power transmission device having a chain with a spiral structure in which a plurality of links are connected in a spiral shape, and a sprocket with which the chain can be engaged.

[0019] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings.

[0020] 1A and 1B are right and left front perspective views of a sprocket with an example chain engaged therewith in accordance with one embodiment of the present disclosure.

[0021] The XYZ Cartesian coordinate system shown in the figure is for the purpose of facilitating understanding of the embodiment of the present disclosure, and is not intended to limit the embodiment of the present disclosure. The X-axis direction indicates the extension direction of the rotation center line of the sprocket, and the Y-axis direction and the Z-axis direction indicate the radial directions of the sprocket.

[0022] 1A and 1B, a sprocket 10 according to the present embodiment is configured to be engageable with a chain 110 having a spiral structure. This constitutes a power transmission device including the sprocket 10 and the chain 110. Before describing the specific configuration of the sprocket 10, the characteristics of the chain 110 that engages with the sprocket 10 will be described first.

[0023] Fig. 2 is a perspective view of a portion of an example chain. Fig. 3 is a top view of a portion of the example chain. Fig. 4 is an exploded perspective view of the example chain. Note that the UVW Cartesian coordinate system shown in the figures is for facilitating understanding of the embodiment of the present disclosure, and does not limit the embodiment of the present disclosure. The U-axis direction indicates the width direction of the chain, the V-axis direction indicates the thickness direction of the chain, and the W-axis direction indicates the extension direction of the chain.

[0024] In this specification, the extending direction of the chain (W-axis direction) is the direction in which the chain moves when the chain is used. When the chain moves along a straight path, the extending direction of the chain corresponds to the extending direction of the straight path. When the chain moves along a curved path, the extending direction of the chain corresponds to the tangent direction of the curved path. In addition, in some drawings, the traveling direction (forward direction) of the chain is indicated by a white arrow FD to facilitate understanding of the embodiments of the present disclosure.

[0025] As shown in FIGS. 2 to 4, the chain 110 has a plurality of first links 120 and a plurality of second links .

[0026] Fig. 5A is a perspective view of multiple first links in an example chain in a connected state, Fig. 5B is a front view of multiple first links (first spiral link connections) in an example chain in a connected state, and Fig. 5C is an exploded perspective view of multiple first links in an example chain.

[0027] 5A to 5C, in an example of a chain 110, a plurality of first links 120 have the same shape. Also, the first links 120 extend in the extension direction (W-axis direction) of the chain 110, and are bent when viewed in the extension direction of the chain 110. That is, the first links 120 have an L-shape when viewed in the extension direction of the chain 110.

[0028] 4 and 5A to 5C, the first links 120 are connected in series. That is, one side of each of the first links 120 in the extension direction (W-axis direction) of the chain 110 is connected to the other side of the other first links 120, and the other side is connected to one side of the other first links 120. A specific connection method will be described later in detail.

[0029] Furthermore, each of the first links 120 rotates about first and second rotation center lines C1 and C2. Specifically, each of the first links 120 is connected to one of the first links 120 so as to be rotatable about the first rotation center line C1, and is connected to the other of the first links 120 so as to be rotatable about the second rotation center line C2.

[0030] The first and second rotation center lines C1 and C2 extend in different directions. Specifically, the first and second rotation center lines C1 and C2 intersect when viewed in the extension direction (W-axis direction) of the chain 110. In one example of the chain 110, the extension direction (U-axis direction) of the first and second rotation center lines C1 and C2 (V-axis direction) intersect at an angle of substantially 90 degrees when viewed in the extension direction of the chain 110.

[0031] When such a plurality of first links 120 are connected in series to other first links 120 so as to be rotatable about first and second rotation center lines C1, C2, a first spiral link assembly 140 extending in a spiral shape is formed, as shown in Fig. 4. The first spiral link assembly 140 is a deformable link assembly having a plurality of first rotation center lines C1 and a plurality of second rotation center lines C2 arranged alternately in the extension direction of the chain 110 (W-axis direction).

[0032] In this specification, the term "spiral" refers to a three-dimensional curve that goes around a reference line extending in one direction and proceeds in the extension direction of the reference line. In this disclosure, the reference line of the spiral corresponds to a line that extends in the extension direction (W-axis direction) of the chain 110 and passes through the cross-sectional shape of the chain 110 perpendicular to the extension direction (i.e., a line that is located within the outline of the cross-sectional shape when viewed in the extension direction).

[0033] As described above, in the example chain 110, the multiple first links 120 have the same shape, and the first and second rotation center lines C1, C2 are substantially perpendicular to each other when viewed in the extension direction (W-axis direction) of the chain 110. Therefore, as shown in Fig. 5A, four consecutive first links 120 correspond to one period (one pitch) of the first spiral link connector 140. Moreover, the four consecutive first links 120, i.e., the first spiral link connector 140, has a substantially square outline when viewed in the extension direction (W-axis direction) of the chain 110, as shown in Fig. 5B.

[0034] Fig. 6A is a perspective view of a plurality of second links in an example chain in a connected state, Fig. 6B is a front view of a plurality of second links (a second spiral link connection body) in an example chain in a connected state, and Fig. 6C is an exploded perspective view of a plurality of second links in an example chain.

[0035] As shown in Figures 6A to 6C, in the example chain 110, the multiple second links 130 have the same shape. Furthermore, the first links 120 and the second links 130 have the same shape. That is, the example chain 110 is composed of one type of link. Therefore, the second links 130 also extend in the extension direction (W-axis direction) of the chain 110, but are bent when viewed in the extension direction of the chain 110. That is, the second links 130 also have an L-shape when viewed in the extension direction of the chain 110.

[0036] 4 and 6A to 6C, the second links 130 are connected in series. That is, each of the second links 130 is connected to the other side of another second link 130 at one side in the extension direction (W-axis direction) of the chain 110, and is connected to the one side of another second link 130 at the other side. The specific connection method will be described in detail later.

[0037] Furthermore, each of the second links 130 is rotatably connected to the other second link 130 connected to one side about a third rotation center line C3, while being rotatably connected to the other second link 130 connected to the other side about a fourth rotation center line C4.

[0038] The third rotation center line C3 and the fourth rotation center line C4 extend in different directions. Specifically, the third rotation center line C3 and the fourth rotation center line C4 intersect when viewed in the extension direction (W-axis direction) of the chain 110. The extension direction of the third rotation center line C3 (U-axis direction) and the extension direction of the fourth rotation center line C4 (V-axis direction) intersect at an angle of substantially 90 degrees when viewed in the extension direction of the chain 110.

[0039] When each of the multiple second links 130 is connected in series to other second links 130 so as to be rotatable about the third and fourth rotation center lines C3, C4, a second spiral link assembly 150 extending in a spiral shape is formed, as shown in Fig. 4. The second spiral link assembly 150 is a deformable link assembly having multiple third rotation center lines C3 and multiple fourth rotation center lines C4 arranged alternately in the extension direction of the chain 110 (W-axis direction).

[0040] As described above, in the example chain 110, the second links 130 have the same shape, and the third and fourth rotation center lines C3, C4 are substantially perpendicular to each other when viewed in the extension direction (W-axis direction) of the chain 110. Therefore, as shown in Fig. 6A, four consecutive second links 130 correspond to one period of the second spiral link assembly 150. Moreover, the four consecutive second links 130, i.e., the second spiral link assembly 150, has a substantially square outline when viewed in the extension direction (W-axis direction) of the chain 110, as shown in Fig. 6B.

[0041] A first spiral link assembly 140 formed from a plurality of first links 120 and a second spiral link assembly 150 formed from a plurality of second links 130 are connected by a connecting member to form the chain 110. Specifically, the first spiral link assembly 140 and the second spiral link assembly 150 are connected to form a double spiral structure.

[0042] FIG. 7 is a perspective view of an example chain showing first and second helical link connections forming a double helix structure.

[0043] As shown in FIG. 7, the first spiral link connector 140 and the second spiral link connector 150 form a double spiral structure without being in direct contact with each other.

[0044] Specifically, the first rotation center line C1 of the first link 120 forming the first spiral link assembly 140 and the third rotation center line C3 of the second link 130 forming the second spiral link assembly 150 are aligned on the same straight line. Also, the second rotation center line C2 of the first link 120 and the fourth rotation center line C4 of the second link 130 are aligned on the same straight line. This allows the first spiral link assembly 140 and the second spiral link assembly 150 to form a double spiral structure without coming into direct contact with each other. Strictly speaking, it is only necessary that the first spiral link assembly 140 and the second spiral link assembly 150 do not come into direct contact with each other at least when the chain 110 extends linearly. Otherwise, the chain 110 cannot be bent.

[0045] The first spiral link connector 140 and the second spiral link connector 150 are connected via a connecting member.

[0046] Fig. 8 is a perspective view showing first and second links in an example chain connected via a connecting member. Fig. 9 is an exploded perspective view for explaining the connection of a plurality of first and second links via a plurality of connecting members in the example chain. Fig. 10A is a cross-sectional view of the example chain taken along line S1-S1 shown in Fig. 2. Fig. 10B is a cross-sectional view of the example chain taken along line S2-S2 shown in Fig. 2.

[0047] 8 to 10B, an example of a chain 110 has first and second pins 160, 162 as connecting members. A first link 120 in the first spiral link connector 140 and a second link 130 in the second spiral link connector 150 are connected to each other via the first and second pins 160, 162.

[0048] The first pin 160 rotatably supports the first link 120 while rotatably supporting the second link 130. Specifically, the first pin 160 supports the first link 120 at one of the base end and the tip end so that the first link 120 is rotatable about a first rotation center line C1. The first pin 160 supports the second link 130 at the other of the base end and the tip end so that the second link 130 is rotatable about a third rotation center line C3. Due to such support by the first pin 160, the first rotation center line C1 of the first link 120 and the third rotation center line C3 of the second link 130 are positioned on the same straight line.

[0049] Further, the first pin 160 supports each of the two consecutive first links 120 so as to be rotatable about the first rotation center line C1. As a result, each of the two consecutive first links 120 is connected to each other so as to be rotatable about the first rotation center line C1. At the same time, the first pin 160 supports each of the two consecutive second links 130 so as to be rotatable about the third rotation center line C3. As a result, each of the two consecutive second links 130 is connected to each other so as to be rotatable about the third rotation center line C3. That is, the first pin 160 supports the two first links 120 and the two second links 130 so as to be rotatable.

[0050] The second pin 162 also rotatably supports the first link 120 and the second link 130. Specifically, the second pin 162 supports the first link 120 at one of the base end and the tip end so that the first link 120 is rotatable about the second rotation center line C2. The second pin 162 also supports the second link 130 at the other of the second base end and the tip end so that the second link 130 is rotatable about the fourth rotation center line C4. Due to such support by the second pin 162, the second rotation center line C2 of the first link 120 and the fourth rotation center line C4 of the second link 130 are positioned on the same straight line.

[0051] Further, the second pin 162 supports each of the two consecutive first links 120 so as to be rotatable about the second rotation center line C2. As a result, each of the two consecutive first links 120 is connected to each other so as to be rotatable about the second rotation center line C2. At the same time, the second pin 162 supports each of the two consecutive second links 130 so as to be rotatable about the fourth rotation center line C4. As a result, each of the two consecutive second links 130 is connected to each other so as to be rotatable about the fourth rotation center line C4. That is, the second pin 162 supports the two first links 120 and the two second links 130 so as to be rotatable.

[0052] In the exemplary chain 110, the first and second pins 160, 162 have the same shape.

[0053] In order to be rotatably supported by the first and second pins 160, 162, the first and second links 120, 130 are each formed with two through holes 120a, 130a into which the first and second pins 160, 162 are inserted, as shown in Fig. 9. In the first link 120, one through hole 120a penetrates in the extension direction of the first rotation center line C1, and the other through hole 120a penetrates in the extension direction of the second rotation center line C2. In the second link 130, one through hole 130a penetrates in the extension direction of the third rotation center line C3, and the other through hole 130a penetrates in the extension direction of the fourth rotation center line C4. By inserting the first and second pins 160, 162 into such through hole 120a, the first pin 160 supports the first link 120 rotatably about the first rotation center line C1, and the second pin 162 supports the first link 120 rotatably about the second rotation center line C2. Similarly, by inserting the first and second pins 160, 162 into the through hole 130a, the first pin 160 supports the second link 130 rotatably about the third rotation center line C3, and the second pin 162 supports the second link 130 rotatably about the fourth rotation center line C4.

[0054] A retaining ring 164 is attached to the tip of the first and second pins 160, 162 to prevent the first and second pins 160, 162 from falling off the first and second links 120, 130. In an example of a chain 110, as shown in Figs. 10A and 10B, a roller 166 is attached to each of the first and second pins 160, 162 via a bush 168. The roller 166 and the bush 168 may both be provided or may be omitted as necessary. Only the roller 166 may be provided as necessary. Furthermore, the method of preventing the first and second pins 160, 162 from falling off the first and second links 120, 130 is not limited to the use of the retaining ring 164, and a split pin, for example, may be used. Furthermore, the first and second pins 160, 162 and the first and second links 120, 130 may be joined by, for example, crimping without using any other parts.

[0055] In addition, in the example chain 110, each of the multiple first and second pins 160, 162 rotatably supports each of the two first links 120 and the two second links 130. Alternatively, the first and second pins 160, 162 may be provided integrally with the first link 120 and the second link 130.

[0056] 10A and 10B, each of the first links 120 includes an inner portion disposed on the inner side of the other first link 120 connected to one of the first links 120, and an outer portion disposed on the outer side of the other first link 120 connected to the other of the first links 120. Similarly, each of the second links 130 includes an inner portion disposed on the inner side of the other second link 130 connected to one of the first links 120, and an outer portion disposed on the outer side of the other second link 130 connected to the other of the second links 130. For example, a bush 168 may be integrally provided on the inner portion of the first link 120 and the inner portion of the second link 130, and the first and second pins 160, 162 may be integrally provided on the outer portion of the first link 120 and the outer portion of the second link 130 while passing through the bush 168. That is, with the bush 168 supported non-rotatably on the inner portions of the first and second links 120, 130, respectively, the first and second pins 160, 162, which are non-rotatably supported on the outer portions of the first and second links 120, 130, respectively, are rotatably supported on the bush 168.

[0057] An example of a method for integrally providing the first and second pins 160, 162 to the first and second links 120, 130, respectively, is "tight fit." To briefly explain "tight fit," first, through holes are provided in the first and second links 120, 130. The first and second pins 160, 162 are press-fitted into these through holes. As a result, the first and second pins 160, 162 are supported in the through holes so that they cannot rotate.

[0058] 11A to 11D are perspective views showing a portion of an example chain bending in different directions.

[0059] As shown in Figures 11A and 11B, when the first link 120 (120A) rotates to one side or the other in the width direction (X-axis direction) around the second rotation center line C2 (C2A), the corresponding second link 130 (130A) rotates in the same direction around a fourth rotation center line C4 (C4A) that is collinear with the second rotation center line C2 (C2A).

[0060] In this specification, a "correspondence" is said to exist between a first link and a second link when the relative position of one link with respect to the other link is maintained substantially constant, i.e., when one link cannot move relative to the other link. In an example chain 110, as shown in Fig. 8, a first link 120 and a second link 130 supported by common first and second pins 160, 162 are in a correspondence relationship.

[0061] Also, as shown in Figures 11C and 11D, when the first link 120 (120B) rotates in one direction or the other in the thickness direction (Y-axis direction) around the first rotation center line C1 (C1B), the corresponding second link 130 (130B) rotates around a third rotation center line C3 (C3B) that is located on the same straight line as the first rotation center line C1 (C1B).

[0062] In this way, the first link 120 and the corresponding second link 130 rotate synchronously, so that the chain 110 can bend in the width direction (X-axis direction) and thickness direction (Y-axis direction) when viewed in the extension direction (Z-axis direction). That is, the chain 110 can bend in four directions when viewed in the extension direction. This allows the chain 110 to freely change its traveling direction. As a result, the chain 110 can move along a straight path as well as a complex path that bends in a complex manner, that is, it can be wound around the sprocket 10. In addition, the chain 110 has a spiral structure, that is, a periodic structure, so that the sprocket 10 can engage with the chain 110 from four directions.

[0063] In order to engage with a chain 110 having such a spiral structure, the sprocket 10 according to the present embodiment has the following features.

[0064] Figures 12A and 12B are right and left front perspective views of the sprocket. Figures 13A and 13B are right and left side views of the sprocket. Figure 14 is a front view of the sprocket. Figures 15A and 15B are exploded perspective views of the sprocket as viewed from different viewpoints. Figures 12A to 14 show a shaft DS that connects a power source such as a motor (not shown) to the sprocket 10 and drives the sprocket 10 to rotate. The sprocket 10 may be connected to a load via the shaft DS instead of the power source.

[0065] As shown in Figures 12A to 15B, the sprocket 10 of this embodiment has a disk-shaped first rotating body 12 having first sprocket teeth 12a and a disk-shaped second rotating body 14 having second sprocket teeth 14a.

[0066] Specifically, the first rotating body 12 includes a disk-shaped first main body portion 12b that rotates about the rotation center line C0 of the sprocket 10, and a plurality of first sprocket teeth 12a provided at intervals along the outer periphery of the first main body portion 12b. The second rotating body 14 includes a disk-shaped second main body portion 14b that rotates about the rotation center line C0, and a plurality of second sprocket teeth 14a provided at intervals along the outer periphery of the second main body portion 14b.

[0067] Additionally, the first sprocket tooth 12a and the second sprocket tooth 14a are located at different positions in the direction (X-axis direction) of the rotation center line C0 of the sprocket 10. In other words, the first sprocket tooth 12a and the second sprocket tooth 14a are spaced apart from each other in the direction of the rotation center line C0.

[0068] In this embodiment, the sprocket 10 includes a cylindrical spacer 16 that is disposed between the first main body portion 12b of the first rotating body 12 and the second main body portion 14b of the second rotating body 14 to separate the first rotating body 12 and the second rotating body 14. The spacer 16 separates the first sprocket teeth 12a and the second sprocket teeth 14a from each other in the direction of the rotation center line C0 of the sprocket 10. The first rotating body 12 and the second rotating body 14 are fixed to the spacer 16 via, for example, screws (not shown).

[0069] Furthermore, in this embodiment, the sprocket 10 includes an annular guide member 18 that guides the chain 110 engaged with the sprocket 10, as will be described in detail later.

[0070] In the present embodiment, the sprocket 10 is made up of a plurality of parts, but it may also be made as a single part. Also, any one of the first rotating body 12, the second rotating body 14, the spacer 16, and the guide member 18 may be integrated into a single part.

[0071] The first rotating body 12, the second rotating body 14, and the spacer 16 each have a through hole 12c, 14c, 16a through which a shaft DS connected to a power source such as a motor (not shown) is inserted. When the shaft DS rotates, the first and second rotating bodies 12, 14, i.e., the first and second sprocket teeth 12a, 14a, rotate synchronously.

[0072] First and second sprocket teeth 12 a , 14 a of the sprocket 10 engage first and second links 120 , 130 of the spiral chain 110 .

[0073] Figures 16A and 16B are right and left side views of an example sprocket with a chain engaged therewith, with all components omitted from Figures 16A and 16B except for guide member 18 of sprocket 10 and first and second links 120, 130 of chain 110.

[0074] 16A and 16B, the sprocket 10 engages with the chain 110 so that the width direction (U-axis direction) of the chain 110 and the extension direction (X-axis direction) of the rotation center line C0 of the sprocket 10 are parallel. Since the chain 110 has a periodic structure, it is also possible for the sprocket 10 to engage with the chain 110 so that the height direction (V-axis direction) of the chain 110 and the extension direction (X-axis direction) of the rotation center line C0 of the sprocket 10 are parallel.

[0075] 16A, the first links 120 and the second links 130 of the chain 110 alternately contact the multiple first sprocket teeth 12a of the sprocket 10. In other words, the first sprocket teeth 12a contacting the first links 120 and the first sprocket teeth 12a contacting the second links 130 alternately line up in the rotational direction of the sprocket 10.

[0076] Strictly speaking, in this embodiment, the first sprocket teeth 12a contact some of the first links 120 and some of the second links 130 of the chain 110.

[0077] FIG. 17 is a perspective view showing contact between the first and second links and the first and second sprocket teeth in one cycle of an example chain.

[0078] As shown in Figure 17 and Figures 5A to 6C, the first sprocket teeth 12a come into contact with a first link 120 (120C) that has a portion between the first sprocket teeth 12a in one cycle of four consecutive first links 120. Similarly, the first sprocket teeth 12a come into contact with a second link 130 (130C) that has a portion between the first sprocket teeth 12a in one cycle of four consecutive second links 130.

[0079] 16A and 17, each of the multiple first sprocket teeth 12a of the sprocket 10 has a first contact portion 12d that contacts the first and second links 120, 130 of the chain 110 in the forward rotation direction R1 of the sprocket 10. In this embodiment, the first contact portion 12d is a flat surface that faces in the forward rotation direction 1 and outward from the sprocket 10.

[0080] 16A and 17, first contact portions 12d of each of the multiple first sprocket teeth 12a of sprocket 10 contact rear end faces 120b, 130b of first and second links 120, 130 of the advancing chain 110. In this specification, the direction of the chain 110 moving in accordance with the forward rotation direction R1 of sprocket 10 is defined as a forward direction FD.

[0081] On the other hand, as shown in FIG. 16A, each of the first sprocket teeth 12a of the sprocket 10 does not contact the first and second links 120, 130 of the chain 110 in the reverse direction R2 of the sprocket 10 (i.e., the direction opposite to the forward direction R1). For example, the first sprocket tooth 12a that contacts the first link 120 in the forward direction R1 does not contact the second link 130 in the reverse direction R2. For this reason, each of the first sprocket teeth 12a has a first relief portion 12e on the reverse direction R2 side to avoid contact with the first and second links 120, 130. In the case of this embodiment, the first relief portion 12e is a relief surface. Therefore, each of the first sprocket teeth 12a does not contact both the first link 120 and the second link 130 at the same time, that is, it is not sandwiched between the first link 120 and the second link 130. The reason why the first sprocket tooth 12a has such a first recess 12e will be described later.

[0082] 16B, the first links 120 and the second links 130 of the chain 110 alternately contact the multiple second sprocket teeth 14a of the sprocket 10. In other words, the second sprocket teeth 14a contacting the first links 120 and the second sprocket teeth 14a contacting the second links 130 alternately line up in the rotational direction of the sprocket 10.

[0083] Strictly speaking, in this embodiment, the second sprocket teeth 14a contact some of the first links 120 and some of the second links 130 of the chain 110.

[0084] 16B and 17, the second sprocket teeth 14a contact the first links 120 (120D) that have portions between the second sprocket teeth 14a in one cycle of four consecutive first links 120. Similarly, the second sprocket teeth 14a contact the second links 130 (130D) that have portions between the second sprocket teeth 14a in one cycle of four consecutive second links 130.

[0085] 16B and 17, each of the multiple second sprocket teeth 14a of the sprocket 10 has a second contact portion 14d that contacts the first and second links 120, 130 of the chain 110 in the reverse direction R2 of the sprocket 10. In this embodiment, the second contact portion 14d is a flat surface that faces in the reverse direction R2 and outward from the sprocket 10.

[0086] Also, as shown in FIG. 16B, the second contact portions 14d of each of the plurality of second sprocket teeth 14a of the sprocket 10 contact the front end faces 120c, 130c of the first and second links 120, 130 of the advancing chain 110.

[0087] On the other hand, as shown in FIG. 16B, each of the second sprocket teeth 14a of the sprocket 10 does not contact the first and second links 120, 130 of the chain 110 in the forward rotation direction R1 of the sprocket 10 (i.e., the direction opposite to the reverse direction R2). For example, the second sprocket tooth 14a that contacts the second link 130 in the reverse direction R2 does not contact the first link 120 in the forward rotation direction R1. For this reason, each of the second sprocket teeth 14a has a second relief portion 14e on the forward rotation direction R1 side to avoid contact with the first and second links 120, 130. In the case of this embodiment, the second relief portion 14e is a relief surface. Therefore, each of the second sprocket teeth 14a does not contact both the first link 120 and the second link 130 at the same time, that is, it is not sandwiched between the first link 120 and the second link 130. The reason why the second sprocket teeth 14a are provided with the second relief portions 14e will be described later.

[0088] Here, the reason why the first and second sprocket teeth 12a, 14a have the first and second relief portions 12e, 14e on different rotational direction sides as shown in Figures 16A and 16B will be explained. For this purpose, Comparative Examples 1 and 2 different from this embodiment will be presented.

[0089] Unlike the present embodiment, a case in which first and second relief portions 12e, 14e are provided on the same side (e.g., the forward rotation direction R1 side) of first and second sprocket teeth 12a, 14a, respectively, is given as Comparative Example 1. In the case of Comparative Example 1, chain 110 attached to sprocket 10 wobbles in its extending direction, resulting in a decrease in the efficiency of power transmission between sprocket 10 and chain 110.

[0090] Also, unlike this embodiment, a case in which the first and second sprocket teeth 12a, 14a do not have the first and second relief portions 12e, 14e, respectively, will be presented as Comparative Example 2. In the case of Comparative Example 2, the first and second sprocket teeth 12a, 14a each simultaneously contact both the first and second links 120, 130 of the chain 110 in the rotational direction of the sprocket 10. In other words, the first and second sprocket teeth 12a, 14a are sandwiched between the first and second links 120, 130, respectively.

[0091] The chain 110 that engages the sprocket is a deformable spiral structure, so that any slight bending changes the distance between the first link 120 and the second link 130. This is similar to how a coil spring changes its pitch when it bends.

[0092] For example, as shown in Figures 16A and 16B, when the first and second links 120, 130 rotate even slightly around the rotation center lines C2, C4 extending in the radial direction of the sprocket 10 (for example, when tension is applied to the chain 110), the first link 120 and the second link 130, which are continuous in the rotation direction of the sprocket 10, approach each other. In the case of Comparative Example 2, which does not have the first and second relief portions 12e, 14e, the first link 120 and the second link 130 that are close to each other may continue to hold the first sprocket tooth 12a therebetween with a strong force. As a result, in the case of Comparative Example 2, the chain 110 does not move away from the sprocket 10 smoothly, and the power transmission efficiency between the sprocket 10 and the chain 110 may decrease. Furthermore, the first and second links 120, 130 of the chain 110 just before engaging with the sprocket 10 may ride up onto the first and second sprocket teeth 12a, 14a, causing the chain 110 to come off the sprocket 10.

[0093] Considering such Comparative Examples 1 and 2, in the present embodiment, as shown in Figs. 16A and 16B, the first sprocket tooth 12a has a first clearance 12e on the reverse direction R2 side, and the second sprocket tooth 14a has a second clearance 14e on the forward direction R1 side. That is, each of the first sprocket teeth 12a contacts the portion of the first and second links 120, 130 (120C, 130C) located therebetween only in the forward direction R1. Also, each of the second sprocket teeth 14a contacts the portion of the first and second links 120, 130 (120D, 130D) located therebetween only in the reverse direction R2. This allows the chain 110 to engage with the sprocket 10 without rattling in the extension direction. Also, the chain 110 with a deformable spiral structure can be smoothly separated from the sprocket 10 and is less likely to come off the sprocket 10.

[0094] In this embodiment, as shown in Figure 16A, the first sprocket tooth 12a of the sprocket 10 does not contact the first and second links 120, 130 of the chain 110 over the "entire" portion on the forward rotation direction R1 side. Also, as shown in Figure 16B, the second sprocket tooth 14a does not contact the first and second links 120, 130 over the "entire" portion on the reverse rotation direction R2 side.

[0095] Specifically, the forward rotation direction R1 side portion (i.e., first contact portion 12d) of the tooth tip side portion (outer peripheral portion) of the first sprocket tooth 12a contacts the first and second links 120, 130, while the forward rotation direction R1 side portion of the tooth base portion (center side portion) does not contact the first and second links 120, 130. That is, a clearance portion 12f is provided on the forward rotation direction R1 side of the tooth base portion of the first sprocket tooth 12a to avoid contact with the first and second links 120, 130. Also, the reverse direction R2 side portion (i.e., second contact portion 14d) of the tooth tip side portion of the second sprocket tooth 14a contacts the first and second links 120, 130, while the reverse direction R2 side portion of the tooth base portion does not contact the first and second links 120, 130. That is, a recess 14f for avoiding contact with the first and second links 120, 130 is provided on the reverse rotation direction R2 side of the tooth base of the second sprocket tooth 14a.

[0096] In this embodiment, as shown in FIG. 16A, the tooth root portion of the sprocket 10 (first rotating body 12) located between two adjacent first sprocket teeth 12a is also not in contact with the first and second links 120, 130. That is, the tooth root portion of the sprocket 10 located between two adjacent first sprocket teeth 12a is also provided with a clearance portion 12g that avoids contact with the first and second links 120, 130. Similarly, as shown in FIG. 16B, the tooth root portion of the sprocket 10 (second rotating body 14) located between two adjacent second sprocket teeth 14a is also provided with a clearance portion 14g that avoids contact with the first and second links 120, 130.

[0097] The escape portions 12f, 12g, 14f, and 14g provided in the forward direction R1 side portion of the root portion of the first sprocket tooth 12a, the bottom portion between two adjacent first sprocket teeth 12a, the reverse direction R2 side portion of the root portion of the second sprocket tooth 14a, and the bottom portion between two adjacent second sprocket teeth 14a, respectively, allow the spiral chain 110 to move away from the sprocket 10 smoothly and are less likely to come off the sprocket 10.

[0098] The detailed shapes of the first and second recesses 12e, 14e and the recesses 12f, 12g, 14f, 14g are determined taking into consideration the shapes of the first and second links 120, 130, as well as the change in the rotational direction of the sprocket 10, the interchange of tensioned and slackened portions of the chain due to the change in rotational direction, gravity acting on the chain, and the like.

[0099] As described above, the first contact portion 12d of the first sprocket tooth 12a facing the forward rotation direction R1 and the second contact portion 14d of the second sprocket tooth 14a facing the reverse rotation direction R2 allow the chain 110 to engage with the sprocket 10 without being displaced in its extending direction (without rattling). On the other hand, the displacement of the chain 110 in the extending direction of the rotation center line C0 of the sprocket 10 (X-axis direction) is suppressed by the first rotating body 12 and the guide member 18.

[0100] FIG. 18 is a partial cross-sectional view of an example sprocket engaged with a chain.

[0101] FIG. 18 shows four consecutive first links 120 (120C-120F) for one cycle. As described above and as shown in FIG. 17, the first sprocket tooth 12a contacts the first link 120 (120C) in the reverse direction R2 of the sprocket 10. The second sprocket tooth 14a contacts another first link 120 (120D) in the forward direction R1. That is, these two first links 120 (120C, 120D) are driven by the first and second sprocket teeth 12a, 14a.

[0102] The remaining two first links 120 (120E, 120F) are guided by the first rotating body 12 and the guide member 18 of the sprocket 10. Specifically, as shown in FIG. 18, one of the first links 120 (120E) is located between the first rotating body 12 and the second rotating body 14, and faces the inner surface 12h of the first rotating body 12 in the extension direction of the rotation center line C0 of the sprocket 10 (X-axis direction). The other first link 120 (120F) faces the inner surface 18a of the guide member 18 attached to the outer surface of the second rotating body 14 in the extension direction of the rotation center line C0. Therefore, the first spiral link connecting body 140 formed from the multiple first links 120 is guided by the inner surface 12h of the first rotating body 12 and the inner surface 18a of the guide member 18, and moves between them. Therefore, the first spiral link connection body 140 is prevented from being displaced in the direction in which the rotation center line C0 extends. As a result, the first link 120 (120C, 120D) is prevented from coming off the first and second contact portions 12d, 14d of the first and second sprocket teeth 12a, 14a.

[0103] Similarly, the second links 130 (130E, 130F) are also guided by the first rotating body 12 and the guide member 18 of the sprocket 10. Therefore, the second spiral link assembly 150 formed from the multiple second links 130 moves between the inner surface 12h of the first rotating body 12 and the inner surface 18a of the guide member 18, and displacement in the extension direction of the rotation center line C0 (X-axis direction) is suppressed. As a result, the second links (130C, 130D) are suppressed from falling off the first and second contact portions 12d, 14d of the first and second sprocket teeth 12a, 14a.

[0104] Since the chain 110 has a helical structure, the helical direction that can be engaged with the sprocket 10 is uniquely determined. In this embodiment, as shown in Figs. 1A and 1B, the chain 110 needs to be engaged with the sprocket 10 so that the first and second helical link structures 140, 150 extend forward while rotating clockwise as viewed from the front. If the chain 110 with a double helical structure is regarded as a twisted wire, the first and second helical link connectors 140, 150 of the chain 110 engaged with the sprocket 10 are S-twisted when viewed in the direction of extension of the rotation center line C0 of the sprocket 10. As shown in Figs. 13B and 16B, a marker 14h indicating a helical direction that can be engaged with the sprocket 10 is formed on the outer surface of the second rotating body 14. The marker indicating the helical direction may be provided on another member, for example, the outer surface of the first rotating body 12, in addition to or instead of the second rotating body 14. Such markers 14h enable a user to properly attach the chain 110 to the sprocket 10.

[0105] According to the present embodiment as described above, it is possible to realize a sprocket that can be engaged with a chain having a spiral structure in which a plurality of links are connected in a spiral shape.

[0106] It should be noted that the chain that can be engaged with the sprocket according to the embodiment of the present disclosure is not limited to the example chain 110 shown in FIGS. 2 to 11D.

[0107] 19A and 19B are left and right front perspective views of an alternative embodiment of a sprocket with an alternative chain engaged therewith.

[0108] 19A and 19B, a sprocket 210 according to another embodiment has a different shape for the first and second sprocket teeth, but is substantially the same in function as the sprocket 10 according to the above-described embodiment. Therefore, a detailed description of the configuration of the sprocket 210 according to another embodiment will be omitted, and a description will be given of another example of a chain 310 that engages with the sprocket 210.

[0109] In the case of the example chain 110 shown in Figs. 2 to 11D, the first links 120 forming the first spiral link assembly 140 are of one type. Also, the second links 130 forming the second spiral link assembly 150 are of one type. In contrast, in the chain 310 of the other example, the first links forming the first spiral link assembly are of multiple types of links with different shapes, and the second links forming the second spiral link assembly are of multiple types of links with different shapes. In other respects, the chain 310 of the other example is almost the same as the chain 110 of the example.

[0110] Fig. 20 is a perspective view of a portion of a chain of another example. Fig. 21 is an exploded perspective view of a portion of the chain of another example. Figs. 22A and 22B are front views of a plurality of first and second links (first and second spiral link connectors) connected to each other in the chain of another example. Figs. 23A and 23B are cross-sectional views of the chain of another example taken along lines S3-S3 and S4-S4, respectively, shown in Fig. 20.

[0111] 20 to 23B, in another example of chain 310, first spiral link assembly 340 is formed from a plurality of types of first links 320, 322 having different shapes. Also, second spiral link assembly 350 is formed from a plurality of types of second links 330, 332 having different shapes.

[0112] 21 and 22A, first link 322 is smaller than first link 320. Moreover, first link 322, which is relatively small, is entirely disposed inside first link 320. Moreover, first links 320, 322 are alternately connected to form first spiral link connection body 340.

[0113] 21 and 22B, second link 332 is smaller than second link 330. Moreover, second link 332, which is relatively small, is entirely disposed inside second link 330. Moreover, second links 330, 332 are alternately connected to form second spiral link assembly 350.

[0114] In the case of the chain 310 of the alternative example, the first link 320 and the second link 330 have the same shape, and the first link 322 and the second link 332 have the same shape. In other words, the chain 310 of the alternative example is composed of two types of links.

[0115] Also, as shown in Figures 23A and 23B, the first links 320, 322 and the second links 330, 332 are connected to and supported by the first and second pins 360, 362 so that the first rotation center line C1 and the third rotation center line C3 are positioned on the same line, while the second rotation center line C2 and the fourth rotation center line C4 are positioned on the same line.

[0116] 19A and 19B, the first sprocket tooth 212a of the sprocket 210 contacts the first and second links 320, 330 of the alternative chain 310 only in the forward direction R1, and the second sprocket tooth 214a contacts the first and second links 322, 332 only in the reverse direction R2.

[0117] 24A and 24B are left and right front perspective views of yet another embodiment of a sprocket with yet another example chain engaged therewith.

[0118] 24A and 24B, a sprocket 410 according to yet another embodiment is substantially identical in function to the sprocket 10 according to the above-described embodiment, except that the number, size, shape, etc. of the first and second sprocket teeth are different. Therefore, a detailed description of the configuration of the sprocket 410 according to the another embodiment will be omitted, and a description will be given of a further example of a chain 510 that engages with the sprocket 410.

[0119] In the chain 110 of the example, each of the first links 120 has a first rotation center line C1 and a second rotation center line C2 that are perpendicular to each other, as shown in FIG. 5B. Also, each of the second links 130 has a third rotation center line C3 and a fourth rotation center line C4 that are perpendicular to each other, as shown in FIG. 6B. In contrast, in a chain 510 of another example shown in FIG. 24A and FIG. 24B, the first and second rotation center lines in each of the first links intersect at an angle other than 90 degrees, and the third and fourth rotation center lines in each of the second links also intersect at an angle other than 90 degrees. The rest of the chain 110 is almost the same as the chain 110 of the example. Therefore, the chain 510 of the further example will be described focusing on this difference.

[0120] Fig. 25 is a perspective view of a portion of a chain of yet another example. Fig. 26 is an exploded perspective view of a portion of a chain of yet another example. Figs. 27A and 27B are front views of a plurality of first and second links (first and second spiral link connectors) connected to each other in a chain of yet another example. Fig. 28 is an exploded perspective view for explaining the connection of a plurality of first and second links via a plurality of connecting members in a chain of yet another example.

[0121] As shown in Figs. 25 to 28, in a further example of a chain 510, a first spiral link assembly 540 is formed by connecting a plurality of first links 520 having the same shape. Also, a second spiral link assembly 550 is formed by connecting a plurality of second links 530 having the same shape. In the further example of the chain 510, the first and second links 520, 530 have the same shape. That is, the further example of the chain 510 is composed of one type of link.

[0122] As shown in Fig. 26 and Fig. 27A, each of the first links 520 rotates around first and second rotation center lines C1 and C2. Specifically, each of the first links 520 rotates around the first rotation center line C1 relative to the other first link 520 connected to one of the first links, and rotates around the second rotation center line C2 relative to the other first link 520 connected to the other of the first links. As shown in Fig. 27A, the first rotation center line C1 and the second rotation center line C2 intersect at an angle of substantially 60 degrees when viewed in the extension direction (W-axis direction) of the chain 510.

[0123] According to such first links 520, six consecutive first links 520 correspond to one period of the first spiral link assembly 540.

[0124] As shown in Fig. 26 and Fig. 27B, each of the second links 530 rotates around the third and fourth rotation center lines C3 and C4. Specifically, each of the second links 530 rotates around the third rotation center line C3 relative to the other second link 530 connected to one of the second links, and rotates around the fourth rotation center line C4 relative to the other second link 530 connected to the other of the second links. As shown in Fig. 27B, the third rotation center line C3 and the fourth rotation center line C4 intersect at an angle of substantially 60 degrees when viewed in the extension direction (W-axis direction) of the chain 510.

[0125] According to such second links 530, six consecutive second links 530 correspond to one period of the second spiral link assembly 550.

[0126] Also, as shown in FIG. 28, the first link 520 and the second link 530 are connected to and supported by the first and second pins 560, 562 so that the first rotation center line C1 and the third rotation center line C3 are positioned on the same line, while the second rotation center line C2 and the fourth rotation center line C4 are positioned on the same line.

[0127] Furthermore, the chain 510 of this further example can bend in six directions when viewed in the extending direction of the chain 510 (W-axis direction).

[0128] 24A and 24B, in yet another example chain 510, the first sprocket tooth 412a of the sprocket 410 contacts the first and second links 520, 530 only in the forward direction R1, and the second sprocket tooth 414a contacts the first and second links 320, 330 only in the reverse direction R2.

[0129] Supplementally, the angle at which the first and second rotation center lines intersect and the angle at which the third and fourth rotation center lines intersect when viewed in the extending direction of the chain are not limited to 90 degrees or 60 degrees, and may be any angle. However, it is preferable that these angles be angles whose integer multiples equal 360 degrees. In other words, it is preferable that one period of the first and second spiral link assembly is formed by an integer number of first and second links. This makes it easier to design a corresponding sprocket.

[0130] In the case of the sprocket 10 of the above embodiment, the first and second contact portions 12d, 14d of the first and second sprocket teeth 12a, 14a are flat. The first and second links of the chain that contact the flat first and second contact portions 12d, 14d are also flat. However, the embodiment of the present disclosure is not limited to this. For example, the first and second contact portions of the sprocket may be curved. In this case, the first and second links of the chain that contact the curved first and second contact portions may also be curved. For example, the first and second contact portions may have a shape in which a recess (e.g., a groove) is provided at the center in the extension direction of the rotation centerline of the sprocket. In this case, the first and second links that contact the first and second contact portions are provided with a protrusion (e.g., a ridge that engages with the recess) that is provided. The recesses of the first and second contact portions engage with the protrusions of the first and second links, thereby suppressing displacement of the chain relative to the sprocket in the direction of the center line of rotation of the chain. In this case, the guide member can be omitted.

[0131] Furthermore, in the case of the above-mentioned embodiment, as shown in Figs. 16A and 16B, in the sprocket 10, the forward rotation direction R1 side portion of the root portion (inner peripheral portion) of the first sprocket tooth 12a, the tooth root portion between two adjacent first sprocket teeth 12a, the reverse direction R2 side portion of the root portion of the second sprocket tooth 14a, and the tooth root portion between two adjacent second sprocket teeth 14a are provided with relief portions 12f, 12g, 14f, and 14g to avoid contact with the first and second links 120 and 130 of the chain 10. However, the embodiment of the present disclosure is not limited to this. These sprocket parts may come into contact depending on the shape of the links of the spiral chain. In other words, even if the links come into contact with these sprocket parts, relief portions may not be provided in these sprocket parts as long as the links have a shape that allows the chain to smoothly engage and disengage with the sprocket.

[0132] In other words, the sprocket according to an embodiment of the present disclosure is, in a broad sense, a sprocket capable of engaging with a chain having a spiral structure in which a number of links are connected in a spiral shape, and includes a number of first sprocket teeth that engage with the links of the chain, and a number of second sprocket teeth that are spaced apart from the first sprocket teeth in the direction of extension of the center line of rotation of the sprocket and engage with the links of the chain, each of the first sprocket teeth having a first contact portion on the forward rotation direction side of the sprocket that contacts the link of the chain, and a first relief portion on the reverse rotation direction side that avoids contact with the link of the chain, and each of the second sprocket teeth having a second contact portion on the reverse rotation direction side of the sprocket that contacts the link of the chain, and a second relief portion on the forward rotation direction side that avoids contact with the link of the chain. [Industrial Applicability]

[0133] The present disclosure is applicable to sprockets that engage a spiral chain having a plurality of links connected in a spiral configuration. [Explanation of symbols]

[0134] 10 Sprockets 12a 1st sprocket tooth 14a Second sprocket tooth 110 Chain (Example Chain) 120 Links (First Link) 130 Links (Second Link) C0 rotation centerline R1 Forward rotation direction R2 Reverse direction

Claims

1. A sprocket that can be engaged with a spiral chain having a plurality of links connected in a spiral shape, a first plurality of sprocket teeth engaging the links of the chain; a plurality of second sprocket teeth spaced apart from the first sprocket teeth along a centerline of rotation of the sprocket and adapted to engage the links of the chain; each of the first sprocket teeth has a first contact portion on a forward rotation direction side of the sprocket that contacts the link of the chain, and a first relief portion on a reverse rotation direction side of the sprocket that avoids contact with the link of the chain; a sprocket, wherein each of the second sprocket teeth has a second contact portion on the reverse direction side of the sprocket that contacts the link of the chain, and a second relief portion on the forward direction side that avoids contact with the link of the chain.

2. The first contact portion is a plane facing the forward rotation direction and the outer side of the sprocket, 2. The sprocket according to claim 1, wherein said second contact portion is a planar surface facing in said reverse direction and said outward direction.

3. 2. The sprocket according to claim 1, further comprising a guide member that faces the chain in a direction in which the rotation center line extends and guides the chain when the chain is engaged with the sprocket.

4. a first rotor including a disk-shaped first body portion and a plurality of the first sprocket teeth provided along an outer periphery of the first body portion; a second rotor including a disk-shaped second main body portion and a plurality of the second sprocket teeth provided along an outer periphery of the second main body portion; 2. The sprocket according to claim 1, further comprising: a spacer disposed between said first rotating body and said second rotating body, said spacer spacing said first sprocket teeth and said second sprocket teeth from each other in an extension direction of said rotational center line.

5. the chain includes a plurality of first links that are rotatably connected to each other to form a first spiral link assembly that extends in a spiral shape; a plurality of second links pivotally connected to each other to form a second spiral link assembly extending in a spiral shape; a plurality of connecting members connecting the first and second spiral link combinations by connecting the corresponding first links and second links, respectively, to form a double spiral structure; the plurality of first sprocket teeth alternately contact the first link and the second link; The sprocket of claim 1 , wherein said plurality of second sprocket teeth alternately contact said first link and said second link.

6. 2. The sprocket of claim 1, further comprising a marker indicating a spiral direction of said chain as it engages said first and second sprocket teeth.

7. A chain having a spiral structure in which a plurality of links are connected in a spiral shape; a sprocket engageable with the chain; The chain is a first plurality of sprocket teeth engaging the links of the chain; a plurality of second sprocket teeth spaced apart from the first sprocket teeth along a centerline of rotation of the sprocket and adapted to engage the links of the chain; each of the first sprocket teeth has a first contact portion on a forward rotation side of the sprocket that contacts the link of the chain, and a first relief portion on a reverse rotation side of the sprocket that avoids contact with the link of the chain; a second sprocket tooth having a second contact portion on the reverse direction side of the sprocket that contacts the link of the chain, and a second relief portion on the forward direction side of the sprocket that avoids contact with the link of the chain.

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