JP2010242946A - Transmission belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission belt in which durabilities of a ring and elements are increased and assembling work is easy in a transmission belt in which a plurality of platy elements are faced with one another to be annularly arranged and two rings are fitted into recesses of these elements to annularly fasten the belt. <P>SOLUTION: Both of two rings R are formed so that the widths of the rings get narrower as coming closer from radial central portions of the two rings R to inner circumferential sides or outer circumferential sides of the rings R or as coming closer from the radial central portion of the ring R to the inner circumferential side and outer circumferential side of the ring R. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a transmission belt configured by arranging a large number of plate-like elements facing each other in an annular shape, and assembling these elements into an endless annular ring and binding them in an annular shape.

  Generally, as a transmission that is used when power is transmitted between a plurality of rotating members, a stepped transmission that can change the gear ratio stepwise, and the gear ratio changes continuously, that is, steplessly. There are known continuously variable transmissions, and belt-type continuously variable transmissions, toroidal-type continuously variable transmissions, and the like are known as the latter continuously variable transmission. Of these, the belt-type continuously variable transmission is a transmission that uses two sets of pulleys, a driving pulley and a driven pulley, and a transmission belt wound around these pulleys to change the gear ratio steplessly. is there. As a power transmission belt used in such a belt-type continuously variable transmission, for example, a large number of plate pieces called elements or blocks are arranged in an annular shape by overlapping each other in the plate thickness direction. A belt formed into an endless ring shape is known by binding the ring in a ring shape with a ring or band or carrier called a carrier.

  When the driving pulley is driven in a state in which such a belt is wound around two sets of pulleys on the driving side and the driven side, the frictional force of the contact portion between the element and the driving pulley is applied to the element, and Then, a compressive force is applied in the element stacking direction applied to the element from the driving pulley, that is, in the thickness direction of the element, according to the torque of the driving pulley. Then, the compressive force transmitted to the element in contact with the driving pulley is transmitted to the element in contact with the driven pulley via the element not wound around the pulley. When a compressive force is transmitted to the element in contact with the driven pulley, the driven pulley is rotated in accordance with the frictional force of the contact portion between the element and the driven pulley and the transmitted compressive force. Torque is generated. In this way, power is transmitted between the driving pulley and the driven pulley via the belt.

  An example of the belt as described above is described in Patent Document 1. The high load transmission belt described in Patent Document 1 is a transmission belt including a center belt and a block that reinforces side pressure resistance. Specifically, the high load transmission belt has a locking portion (a retaining portion) at the upper end. Left and right of the two belt side portions and the block (element) formed by the connecting member that connects them at the lower end, and the fitting groove (concave portion) opened between the two locking portions of the element And two endless carriers (rings) fitted so as not to be detached from the element by the retaining portion. Also, a fitting convex part is provided on one surface in the thickness direction of the element and a fitting concave part that fits the convex part is provided on the other surface, and elements adjacent to each other are fitted with the fitting convex part. The elements are arranged so as to be aligned even when the belt is running by fitting the joint recess. Furthermore, the element which adjoins mutually fits the convex part for fitting, and the recessed part for fitting, and the operation | work which twists and assembles two rings is made easy.

JP 2008-051222 A

  In the transmission belt described in Patent Document 1, the left and right belt side portions are formed with a retaining portion for locking the ring and the element at both ends, and formed between the left and right belt side portions. The transmission belt is configured by fitting two rings into the recessed portion and assembling them so that the two rings are locked by the retaining portion. Further, as shown in FIG. 6, the two rings R2 are configured so that a cross section perpendicular to the circumferential direction of the ring is rectangular, that is, a shape having right angles at the four corners. The inner surface composed of the stop portions 101 and 102 has a shape in which the planes are connected at right angles.

  When a transmission belt is configured by assembling two rings in the concave portion of the element as in the transmission belt described in Patent Document 1, it is necessary to partially overlap the two rows of rings with each other. In this case, for example, as shown in FIG. 7, the four corners of the ring R3 interfere with each other or interfere with the protrusion 104 provided in the recess 103 of the element E3, that is, edge contact occurs. , There is a possibility of hindering the assembly.

  In addition, when the edge of the ring R3 occurs with respect to the corner portion of the recess 103 of the element E3, the stress generated in the element E3 increases, which may cause a decrease in the durability of the element E3. . As a countermeasure against this, for example, as shown in FIG. 8, it is conceivable to provide corner relief portions 107 and 108 at portions where the edges 105 and 106 of the inner circumferential surface of the two rows of rings R4 are in contact with the element E4. However, in that case, the strength and rigidity of the portion where the corner relief portions 107 and 108 are provided may be lowered.

  The present invention has been made paying attention to the technical problem described above, and when a transmission belt is constructed by assembling two rings and an element formed with a recess for accommodating the two rings in parallel. Furthermore, it is an object of the present invention to provide a transmission belt that can improve the assembly and durability of the transmission belt by preventing the rings from facing each other.

  In order to achieve the above-mentioned object, the invention according to claim 1 is arranged such that a large number of elements formed with recesses for accommodating two rings are arranged in a ring shape, and the recesses in a plurality of element rows arranged in the ring shape. In the transmission belt in which the two rings are fitted to each other, the width of each of the two rings is narrower from the central portion in the radial direction of the two rings toward the inner peripheral side or the outer peripheral side of the ring. Alternatively, the transmission belt is characterized in that the width is narrowed from the central portion in the radial direction of the ring toward the inner peripheral side and the outer peripheral side.

  According to a second aspect of the present invention, a concave portion for accommodating two rings is formed, and the two rings are engaged with the open end sides of the left and right inner wall surfaces in the concave portion to prevent the left and right sides from being separated. A number of elements formed with retaining portions are arranged in an annular shape so that the opening end side is on the outer peripheral side, and the two elements are arranged on the inner peripheral side of the left and right retaining portions in the row of the annularly arranged elements. In the transmission belt to which the two rings are fitted and assembled, the width of each of the two rings is narrower from the central portion in the radial direction of the two rings toward the inner peripheral side or the outer peripheral side of the ring. Alternatively, the transmission belt is characterized in that the width is narrowed from the central portion in the radial direction of the ring toward the inner peripheral side and the outer peripheral side.

  Further, the invention of claim 3 is the invention of claim 2, wherein the recess faces the inner peripheral surface of each inner wall surface and each retaining portion and / or the inner peripheral surface of the two rings. The transmission belt is characterized in that the surface is formed so as to be connected by a curved surface.

  Therefore, according to the first and second aspects of the present invention, the two rings have the ring width narrowed from the central layer in the radial direction toward the inner circumferential direction and / or toward the outer circumferential direction. By forming the two rings, it is possible to reduce the stress received by the concave portion of the element from the two rings or the stress received by the two rings from the concave portion of the element. This also improves the durability of the two rings and elements.

  According to a third aspect of the present invention, the recess provided in the element includes a surface facing the inner peripheral surface of the two rings, a surface facing the side surface of the two rings, and / or the two. Since the surface facing the side surface of the ring and the surface facing the outer peripheral surface of the two rings are connected by a curved surface, the stress received by the two rings from the concave portion and the retaining portion of the element can be reduced. This improves the durability of the two rings. Further, the stress received by the concave portion and the retaining portion of the element from the two rings can be reduced. This improves the durability of the element.

It is a schematic diagram which shows the structure of the transmission belt made into object by this invention, Comprising: It is a front view of the transmission belt. It is a schematic diagram which shows the structure of the transmission belt made into object by this invention, Comprising: It is a partial sectional side view of the element which comprises the transmission belt. It is a schematic diagram for demonstrating the state which piled up the state which comprises the transmission belt made into object by this invention, and the state paralleled. It is a schematic diagram which shows the other structural example of the transmission belt made into object by this invention, Comprising: It is a front view of the transmission belt. It is a schematic diagram for demonstrating the state which piled up the state which comprised the ring which comprises the power transmission belt of the other structural example made into object by this invention, and the parallel state. It is a schematic diagram which shows an example of a structure of the power transmission belt by a prior art, Comprising: It is a front view of the power transmission belt. It is a schematic diagram for demonstrating the state in which the ring which comprises the transmission belt by a prior art was piled up, and the state put in parallel. It is a schematic diagram which shows the structure of the power transmission belt for demonstrating an example of a countermeasure of the subject of a prior art, and is a front view of the power transmission belt.

(Configuration example of transmission belt)
Next, the present invention will be specifically described with reference to the drawings. First, the configuration of the transmission belt targeted by the present invention will be described with reference to FIGS. 1 to 3, the transmission belt B is wound around a driving side (input shaft) pulley and a driven side (output shaft) pulley of a belt type continuously variable transmission, and transmits power between these pulleys. An example of a belt is shown. The transmission belt B includes an endless annular ring R and a large number of elements E formed in a plate shape.

  The element E is made of, for example, a metal plate-like member, and a main body (base) in which the left and right side surfaces 1 and 2 in the width direction (x-axis direction in FIG. 1) are formed as tapered inclined surfaces. Both side surfaces 1 and 2 which have a portion 3 and are inclined in taper form friction with a belt winding groove (V-shaped groove) 4a of a pulley 4 which is a driving pulley or a driven pulley of a belt type continuously variable transmission. Torque is transmitted by contact.

  At both left and right ends in the width direction of the main body 3 (x-axis direction in FIG. 1), a part of the main body 3 and above the element E in the vertical direction (y-axis direction in FIGS. 1 and 2) Left and right column parts 5 and 6 are formed respectively. Accordingly, the upper end surface 3a which is the upper edge portion in FIGS. 1 and 2 of the main body portion 3, and the left and right inner wall surfaces 5a and 6a facing the center in the width direction of the main body portion 3 of both pillar portions 5 and 6; Thus, a recess 7 is formed which is open on the upper side of the element E (upper side in FIG. 1), that is, on the outer peripheral side of the transmission belt B.

  The concave portion 7 is a portion for inserting and accommodating an endless annular ring R for binding the elements E arranged in an annular shape in close contact with each other, so that the upper end surface 3a is located inside the ring R. It is a saddle surface 3a on which the circumferential surface is placed in contact.

The left and right tip surfaces 8a are respectively provided at the open ends of the left and right inner wall surfaces 5a, 6a of the recess 7 (the outer end of the transmission belt B in the recess 7). 9a are formed on the left and right retaining portions 8 and 9 extending toward the center in the width direction of the concave portion 7 (x-axis direction in FIG. 1). Therefore, as shown in FIG. 3, the opening width of the recess 7 is defined by the distance W ₁ between the opposing tip surfaces 8 a and 9 a on the opening end side of the recess 7. Then, the bottom surface 7a (i.e. saddle face (upper end face) 3a) of the recess 7 side, both the distal end surface 8a, and has a wide opening width _{W 2} than the distance (opening width) _{W 1} between 9a.

  In addition, the inner wall surfaces 5a and 6a of the column portions 5 and 6 are connected by a curved surface forming an arc surface with a straight line passing through one point in the recess 7 as a central axis from the bottom surface 7a of the recess 7. That is, the curved surface portions 5b and 6b are provided by chamfering (filleting) so that the inner corners are rounded from the bottom surface 7a of the concave portion 7 to the inner wall surfaces 5a and 6a of the column portions 5 and 6. Further, the retaining portions 8, 9 have retaining portion inner wall surfaces 8 b, 9 b facing the bottom surface 7 a of the recess 7. The retaining wall inner wall surfaces 8b and 9b are connected to the inner wall surfaces 5a and 6a of the column portions 5 and 6 by curved surfaces forming arcuate surfaces with a straight line passing through one point in the recess 7 as a central axis. That is, the curved surface portions 5c and 6c are provided by being filleted from the inner wall surfaces 5a and 6a of the column portions 5 and 6 to the retaining wall inner wall surfaces 8b and 9b.

  The element E constitutes a transmission belt B by being bound by the ring R divided in two rows as described above in an annular arrangement, and in this state, each pulley on the drive side and the driven side 4 is wound around. Therefore, in the state of being wound around the pulley 4, each element E needs to expand in a fan shape with respect to the center of the pulley 4 and be in close contact with each other. The portion on the center side in the annular arrangement state is formed thin.

  Specifically, the lower portion from a predetermined position on one surface of the main body 3 (for example, the left surface in FIG. 2), in this configuration example, the lower portion from the saddle surface 3a is scraped off. Thinned. Therefore, when each element E is arranged in an annular shape and expands into a fan shape and comes into contact, it comes into contact with another adjacent element E at the boundary portion where the plate thickness changes. In other words, when the boundary portion where the plate thickness changes as described above expands in a fan shape with respect to the center of the pulley 4 in a state where each element E constitutes the transmission belt B together with the ring R and is wound around the pulley 4. As a fulcrum. That is, the edge of the boundary portion is a so-called rocking edge 12.

  In FIG. 2, the portion below the locking edge 12 is thinned in a tapered shape with respect to the thick portion above the locking edge 12 of the element E (the outer peripheral side in an annular arrangement). However, it is also possible to configure the lower portion of the locking edge 12 in a stepped shape from the locking edge 12 toward the lower end.

  Further, a boss portion 10 and a hole portion 11 for determining the relative position of each element E are formed at the central portion in the width direction of the main body portion 3 of the element E. Specifically, a frustoconical boss portion 10 that is convex on one surface side of the main body 3 (in the example of FIG. 2, the surface side with the locking edge 12) is formed. And the bottomed cylindrical hole part 11 which loosely fits the boss | hub part 10 in the adjacent element E (free fitting) is formed in the surface on the opposite side to this boss | hub part 10. As shown in FIG.

  Therefore, when the elements E are stacked and arranged in the plate thickness direction, the boss portions 10 and the hole portions 11 of the adjacent elements E are fitted to each other. The relative position in the horizontal direction and the vertical direction can be determined. For example, when the transmission belt B configured using the element E is wound around a pulley and operated, the transmission belt B can be prevented from rattling and the transmission belt B can be stably driven. it can.

  Here, the ring R which constitutes the transmission belt B together with the element E is a so-called laminated ring formed by laminating a plurality of metal annular strips in the radial direction, for example. Internally, it is constituted by two split rings 13 and split rings 14 arranged in parallel in two rows. Each of these split rings 13 and 14 is formed of two metal laminated rings having the same shape, size, material, and strength, for example.

Further, each of the split rings 13 and 14 includes a plurality of the metallic annular strips in the radial direction so that the width becomes narrower toward the outer peripheral side of the ring R in the thickness direction (y-axis direction in FIG. 1). It is formed by laminating. Further, each of the split rings 13 and 14 includes a plurality of the metal annular strips in the radial direction so that the width becomes narrower toward the inner peripheral side of the ring R in the thickness direction (y-axis direction in FIG. 1). It is formed by laminating sheets. That is, the radial side surfaces of the split rings 13 and 14 are provided with a predetermined gap (clearance) along the surface formed by the inner wall surfaces 5a and 6a of the element E, the curved surface portions 5b and 6b, and the curved surface portions 5c and 6c. Thus, the split ring side surfaces 13a and 13b and the split ring side surfaces 14a and 14b are configured. Then, the width dimension D _{1 of} the ring R (dimension in the x-axis direction in FIG. 3) D ₁ , that is, the total width dimension D ₁ when the divided rings 13 and 14 are arranged in parallel is the opening width W of the recess 7 of the element E. longer than _1, the shape and dimensions of the respective parts are formed is set to a value within a range shorter than the opening width W _2.

  Therefore, in a state where the ring R is housed inside the recess 7 of the element E, the left and right retaining portions 8 and 9 lock the ring R, thereby preventing the ring R from being detached from the recess 7 of the element E. Is done. Specifically, when the ring R accommodated in the concave portion 7 is to be detached from the concave portion 7, the outer peripheral surfaces 13 a and 14 a of the ring R and the inner wall surfaces 8 b and 9 b of the retaining portions 8 and 9 formed in the concave portion 7. And the ring R from the recess 7 is prevented from coming off. Further, the radial side surface portion of the ring R is provided with a predetermined gap (clearance) along the surface formed by the inner wall surfaces 5a, 6a, the curved surface portions 5b, 6b, and the curved surface portions 5c, 6c of the element E. Side surfaces 13a and 13b and split ring side surfaces 14a and 14b are configured.

  This clearance increases from the central layer of the metal annular strip forming the ring R toward the outer peripheral side and the inner peripheral side of the transmission belt B (or the radial direction of the ring R). As a result, the contact between the innermost layer ring of the ring R and the column portion 6 and the contact between the outermost layer ring of the ring R and the column portion 6 are reduced. Further, the concave portion 7 of the element E has the curved surfaces 5b and 5c and the curved surfaces 6b and 6c, and the ring R is narrowed from the central layer in the radial direction toward the inner peripheral side and the outer peripheral side. Since the contact surface between the recess 7 and the ring R becomes wider, the inner wall surfaces 5a and 6a, the curved surface portions 5b and 6b, and the curved surface portions 5c and 6c of the element E are separated from the radial side surface portions of the divided rings 13 and 14, respectively. The stress received is dispersed. This also reduces the contact between the split rings 13 and 14. From these things, durability of the ring R and the element E can be improved.

  And the transmission belt B is comprised by assembling the element E comprised as mentioned above and the ring R divided | segmented into 2 rows. That is, by inserting two rows of rings R into the recesses 7 of a large number of elements E arranged in an annular shape, specifically, on the inner peripheral side of both retaining portions 8 and 9 of the recesses 7, the element E And the ring R are assembled to form an endless annular transmission belt B.

  4 and 5 show other configuration examples of the transmission belt B. FIG. The transmission belt B1 shown in FIGS. 4 and 5 has substantially the same shape as the transmission belt B shown in FIGS. 1 to 3 except for characteristic parts. Are denoted by the same reference numerals, and description thereof is omitted. Hereinafter, only the characteristic part of the transmission belt B1 will be described. The transmission belt B1 is composed of an element E1 and a ring R1. The element E1 has a shape in which the element E has the curved surface portions 5b and 6b and the curved surface portions 5c and 6c in the concave portion 7, whereas the concave portion 7 is disconnected from the bottom surface 7a and the inner wall surface 5a of the column portion 5. The three planes of the stoppers 8 and 9 are connected at a substantially right angle. On the other hand, the ring R1 has a configuration in which the above-described ring R is narrowed from the radial center layer toward the inner peripheral side and the outer peripheral side, whereas the ring R1 is formed from the radial outer peripheral side. The width is narrower toward the inner periphery. Although not shown, the ring R1 may have a configuration in which the width is narrowed from the radially inner periphery toward the outer periphery.

(Example of assembly of transmission belt)
An example of assembly of the transmission belt B according to the present invention will be described with reference to the drawings. As shown in FIG. 3, the transmission belt B according to the present invention has the width of the ring R in a parallel state in which two rings R are arranged in parallel in the width direction (that is, the width of the split ring 13 and the width of the split ring 14. total) D ₁ is such that is narrower than wide and the opening width W ₂ than the opening width W ₁ of the recess 7 of the element E, the shape and dimensions of the split ring 13 and 14 are set. Then, by setting the two rings R so as to overlap each other in the radial direction, the width of the ring R can be made narrower than the opening width W ₁ . The shape and dimensions are set.

That is, the opening width W ₁ is smaller than the width D ₁ of the ring R in the recess 7 of the element E, and as the opening width W ₂ is wider than the width L ₁ of the ring R, elements E and ring R is formed It has been, and in part of the overlapping state of the ring R, and is configured such that the width of the ring R is narrower than the opening width W ₁ of the element E. Therefore, by the overlapping state of a portion of the circumference direction of the ring R, the tip surface 8a of the stopper portion 8, 9 leaves the portion of the overlapping state of the right and left, 9a between, ie, the portion of the opening width W ₂ So that two rows of rings R can be fitted into the recesses 7.

  After the end faces 13b and 14b of the two rings R are separated from each other in this way, the circumferential lengths of the two rings R are maintained while the end faces 13b and 14b of the two rings are separated from each other. A portion in the direction is overlaid. Thereafter, the overlapped portion of the ring R is fitted into the inner peripheral sides of the left and right retaining portions 8 and 9 in the concave portion 7 of the element E.

  Then, the overlapped portion of the ring R is passed between the front end surfaces 8a and 9a of the left and right retaining portions 8 and 9, and then into the recess 7, specifically, the left and right retaining portions 8 in the recess 7. , 9 are fitted on the inner peripheral side, and the overlapped portion of the ring R fitted in the recess 7 is returned to the parallel state. By returning the ring R fitted in the recess 7 to the parallel state, the ring R is locked in the recess 7 by the both retaining portions 8 and 9, and the ring R is prevented from being detached from the recess 7. In other words, the ring R is fitted into the recess 7 and engaged. That is, the element E and the ring R are assembled.

  As described above, after the end surfaces of the two overlapping rings 13 and 14 are separated from each other and a predetermined part in the circumferential direction of the ring R is put in an overlapping state in this state, the element E and the ring The operation of assembling R is repeatedly executed while being sequentially moved in the circumferential direction of the ring R. When the ring R is fitted into the recesses 7 of all desired elements E, the overlapping state of the rings R is canceled. That is, the entire ring R is brought into a parallel state. As a result, the ring R in which the two split rings 13 and 14 are arranged in parallel is engaged with the recesses 7 of all the elements E, that is, all the elements E and the rings R are assembled, and the transmission belt B Assembling is completed.

  As described above, according to the method for assembling the transmission belt B according to the present invention, the element E in which the two split rings 13 and 14 and the recess 7 for accommodating the two split rings 13 and 14 in parallel are formed. First, when a part in the circumferential direction of the two split rings 13 and 14 is overlapped with each other in the radial direction, the two split rings 13 and 14 are overlapped with the parallel portion. The end faces 13b and 14b on the side facing the width direction of the two split rings 13 and 14 at the overlapping start point that becomes the boundary with the portion to be formed are separated from each other. Thereafter, a part of the two split rings 13 and 14 are overlapped with the end faces 13b and 14b being separated. In this way, the ring R is overlapped, so that the width of the ring R at that portion is shortened and the opening width of the recess 7 is narrowed by the left and right retaining portions 8 and 9 of the element E. Two rings R can be fitted into the inner peripheral side of the retaining portions 8 and 9 by passing through.

  When performing the above-described series of assembling operations, the two split rings 13 and 14 become narrower from the center layer in the thickness direction (y-axis direction in FIG. 5) toward the inner peripheral side and the outer peripheral side. By being comprised in this, the operation | work which makes the end surfaces 13b and 14b of the two division | segmentation rings 13 and 14 mutually overlap from the part of a parallel state can be performed easily. That is, since the movable range of each of the two split rings in the width direction of the ring R is wide, the operation of shifting one of the two split rings 13 and 14 can be easily performed. In other words, in the overlapping state of the ring R, when the split ring 13 and the split ring 14 face each other at the side portions, the split rings 13 and 14 are located on the inner peripheral side and the outer peripheral side from the radial center layer. Since the width is narrowed toward the center, contact between the side surfaces of the split rings 13 and 14 facing each other can be reduced during superposition as shown in FIG. For this reason, it can be easily assembled.

  When the two rings R are put into an overlapping state, first, the end faces 13b and 14b on the side facing the width direction of the two rings R at the overlapping starting point are separated from each other. When the two rings R are overlapped with each other, the end faces 13b and 14b of the two rings R are rubbed with each other at the overlapping starting point, or edge contact occurs and the end faces 13b and 14b are damaged. As a result, it is possible to avoid a decrease in durability of the transmission belt B. The above assembly example can also be applied to the assembly of the transmission belt B1, which is another configuration example shown in FIGS.

  The present invention is not limited to the specific examples described above. That is, in the above-described specific example, the transmission belt targeted by the present invention is used in a belt-type continuously variable transmission, but the transmission belt targeted by the present invention is a belt-type continuously variable transmission. The present invention can be applied not only to a transmission but also to a transmission belt of another winding transmission device including a belt and a pulley.

  Further, in the elements E and E1 constituting the transmission belt targeted by the present invention, the recess 7 that is an opening for accommodating the split rings 13, 14, and 15, 16 opens to the outer peripheral side of the transmission belts B and B1. The divided rings 13, 14 and 15, 16 constituting the transmission belt targeted by the present invention have a configuration in which openings for receiving the element rings are provided on both side surfaces of the element. Can also be assembled. As a result, when the split ring comes into contact with the opening of the element, the line contact state changes to the surface contact state, so that the durability of the split ring and the element, and consequently the durability of the transmission belt, is improved.

  R, R1 ... ring, 7 ... recess, E, E1 ... element, B, B1 ... transmission belt, 8, 9 ... retaining part.

Claims (3)

A transmission belt in which a large number of elements formed with recesses for accommodating two rings are arranged in a ring shape, and the two rings are fitted into the recesses in a plurality of element arrays arranged in the ring shape,
Each of the two rings has a width that is narrower from the central portion in the radial direction of the two rings toward the inner peripheral side or outer peripheral side of the ring, or from the central portion in the radial direction of the ring. A power transmission belt, wherein the transmission belt is formed so that the width becomes narrower toward an inner peripheral side and an outer peripheral side. A plurality of recesses for accommodating the two rings are formed, and left and right retaining portions for preventing the detachment by engaging the two rings on the opening end sides of the left and right inner wall surfaces in the recesses are formed. Are arranged in a ring shape so that the opening end side is on the outer peripheral side, and the two rings are fitted and assembled on the inner peripheral side of the left and right retaining portions in the row of elements arranged in the ring shape. In the belt,
Each of the two rings has a width that is narrower from the central portion in the radial direction of the two rings toward the inner peripheral side or outer peripheral side of the ring, or from the central portion in the radial direction of the ring. A power transmission belt, wherein the transmission belt is formed so that the width becomes narrower toward an inner peripheral side and an outer peripheral side.   The concave portion is formed such that the inner wall surface and the inner peripheral surface of each retaining portion and / or the surface facing the inner peripheral surface of the two rings are connected by a curved surface. The transmission belt according to claim 2.

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