JP2009257487A - Power transmission chain and power transmission device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power transmission chain and a power transmission device which can unify circumferential length and stabilize transmission ratio. <P>SOLUTION: Rolling contact surface of a pin 14 comprises a plurality of partitions wherein respective partitions are predefined involute shape. Basic circle radii Rb of involute shape of each partitions are adapted to temporarily decrease, namely, to satisfy larger Rb on section which contact diameter of a pulley with the pin 14 is on small side and smaller Rb on section which the contact diameter of the pulley with the pin 14 is on large side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a power transmission chain, and more particularly to a power transmission chain and a power transmission device suitable for a continuously variable transmission (CVT) of a vehicle such as an automobile.

  As a power transmission chain for a continuously variable transmission, Patent Document 1 corresponds to a plurality of links having front and rear insertion portions through which pins are inserted, a front insertion portion of one link, and a rear insertion portion of another link. In this way, a plurality of first pins and a plurality of second pins arranged before and after connecting the links arranged in the chain width direction are provided. Bending in the vertical direction is possible, and one of the first pin and the second pin is fixed to the front insertion portion of one link and movably fitted to the rear insertion portion of the other link, The other has been proposed that is movably fitted in the front insertion part of one link and fixed to the rear insertion part of another link.

  The power transmission chain is spanned between pulleys of a continuously variable transmission that includes a pair of pulleys each including a fixed sheave and a movable sheave to constitute a power transmission device, and includes at least a first pin and a second pin. As both end faces come into contact with the sheave surface of the pulley, the power is transmitted by frictional force, and the contact diameter between the pin and the pulley changes according to the change in the distance between the sheave surfaces of the fixed sheave and the movable sheave. This has the advantage that the continuously variable transmission can be performed with smooth movement by changing the gear ratio of the continuously variable transmission.

In Patent Document 1, the locus of the contact position between the first pin and the second pin is an involute of a circle, and the rolling contact surface of the first pin has an involute shape having a base circle of radius Rb and center M in cross section. The rolling contact surface of the second pin is a flat surface (the cross-sectional shape is a straight line). As a result, when each link moves from the straight portion of the chain to the curved portion or from the curved portion to the straight portion, the rolling contact surface of the first insertion pin is fixed to the fixed second pin at the front insertion portion. The second pin moves while being in rolling contact with the rolling contact surface of the second pin (including some sliding contact), and in the rear insertion portion, the second pin is in contact with the first pin, and the rolling contact surface is in contact with the first pin. It is supposed to move while rolling on the surface (including some sliding contact).
JP 2005-233275 A

  According to the power transmission chain of Patent Document 1, the diameter of the pin in contact with the pulley changes, and the distance between the contact positions of adjacent pins changes accordingly. The change in the distance between the contact positions of the adjacent pins is the same as the change in the circumference, which may cause an unstable transmission ratio.

  An object of the present invention is to provide a power transmission chain and a power transmission device that can make the circumference uniform and stabilize the speed ratio.

  The power transmission chain according to the present invention includes a plurality of links having front and rear insertion portions through which pins are inserted, and links arranged in the chain width direction so that a front insertion portion of one link and a rear insertion portion of another link correspond to each other. A plurality of first pins and a plurality of second pins arranged before and after connecting each other, the rolling contact surface of one of the pins being a flat surface, and the rolling contact surface of the other pin being a predetermined curved surface The first pin and the second pin are in rolling contact with each other, so that the links can be bent in the longitudinal direction. The first pin and the second pin can be bent between the pulleys of the continuously variable transmission. The power of the continuously variable transmission is changed by changing the contact diameter between the pin and the pulley while transmitting the power by the frictional force because the both end surfaces of at least one of the first pin and the second pin are in contact with the sheave surface of the pulley. Change In the power transmission chain, the predetermined curved surface is composed of a plurality of sections each having a predetermined involute shape, and the basic circle radius of the involute shape of each section is large on the side where the contact diameter between the pin and the pulley is small, This is characterized in that the contact diameter between the pin and the pulley is small and is small.

  Conventionally, the rolling contact surface shape of a curved pin is one involute having a radius Rb and a center circle with a center M. On the other hand, in this invention, the rolling contact surface shape of the pin is formed by a plurality of sections each having an involute shape. The basic circle radius of the involute shape of each section is large on the side where the contact diameter between the pin and the pulley is small, and small on the side where the contact diameter between the pin and the pulley is large, that is, the contact position is the outer diameter from the inner diameter side of the chain. It is assumed that the base circle radius of the involute shape is temporarily reduced as it moves to the side.

  The pitch length (distance between contact positions of adjacent pins) is constant in the chain linear part, but is different in the chain curve part where the pin contacts the pulley, and the diameter of the pin contacting the pulley is different. If they are different, the distance between the contact positions of adjacent pins (hereinafter referred to as “true pitch”) also takes a different value. In the case of one involute shape as in the prior art, when the pin / pulley contact diameter is minimum, the true pitch is first increased and the maximum pitch is increased as the pin / pulley contact diameter is increased. It becomes small gradually after becoming.

  The difference between the true pitch corresponding to the minimum pin / pulley contact diameter and the maximum true pitch is small when the basic circle radius is large, and is large when the basic circle radius is small. On the other hand, the difference between the true pitch corresponding to the maximum pin / pulley contact diameter and the maximum true pitch is large when the basic circle radius is large, and small when the basic circle radius is small. Yes. The change (variation) in the true pitch is a variation in the circumference of the chain, so it is preferable to keep it small. The involute-shaped basic circle radius of multiple sections is on the side where the contact diameter between the pin and pulley is small. Large and small on the side where the contact diameter between the pin and the pulley is large, so that variations in the true pitch can be suppressed. Adjacent sections are tangent (smoothly connected).

  The larger the number of sections, the more the change in the true pitch can be suppressed. However, by setting the number to 3 or more, a practically sufficient effect can be obtained. The basic circle radius Rb of each section is preferably within a range of 30 ≦ Rb ≦ 80. Specifically, the involute basic circle radius Rb of the rolling contact surface of the pin may be 70-60-50, 70-65-60-50, etc. in order from the bottom.

  In order to obtain an appropriate base circle radius, the true pitch is substantially constant (preferably, constant) by determining how the true pitch changes as the pin / pulley contact diameter increases for a plurality of base circle radii. However, the basic circle radius may be reduced temporarily so that a slight difference is allowed.

  The shape of the rolling contact surface used in one chain is not limited to one type, and there are two types (one having a relatively large curvature and one having a relatively small curvature as a whole). May be. For example, the rolling contact surface of one pin can be 70-60-50 in the order of Rb from the bottom, and the rolling contact surface of the other pin can be 60-50-40 in the order of the Rb from the bottom.

  Preferably, in the power transmission chain, one of the first pin and the second pin is fixed to the front insertion portion of one link and movably fitted to the rear insertion portion of the other link, and the other is , Movably fitted in the front insertion portion of one link and fixed to the rear insertion portion of the other link, and further, a link row composed of a plurality of links having the same phase in the width direction in the traveling direction (front-rear direction) The three link units are arranged in parallel to form one link unit, and a plurality of link units composed of the three link rows are connected in the traveling direction.

  In this power transmission chain, at least one of the first pin and the second pin comes into contact with the pulley to transmit power by frictional force. In a chain in which one of the pins contacts the pulley, one of the first pin and the second pin is a pin that contacts the pulley when the chain is used in a continuously variable transmission ( In the following, the pin is referred to as “first pin” or “pin”, and the other is referred to as the pin that does not contact the pulley (interpiece or strip). "Peace").

  For example, the link is made of spring steel or carbon tool steel. The material of the link is not limited to spring steel or carbon tool steel, and may of course be other steel such as bearing steel. In the link, the front and rear insertion portions may be independent through holes (links with columns), and the front and rear insertion portions may be one through holes (links without columns). Appropriate steel such as bearing steel is used as the material of the pin.

  The pin is fixed to the front and rear insertion portion by, for example, fitting and fixing between the inner edge of the insertion portion and the outer peripheral surface of the pin by mechanical press-fitting. Alternatively, shrink fitting or cold fitting may be used. The first pin and the second pin are fitted to one insertion portion so as to face each other in the length direction of the chain, and either one of them is fitted and fixed to the peripheral surface of the insertion portion of the link. The fitting and fixing is preferably performed at the edges (upper and lower edges) of the portion orthogonal to the length direction of the insertion portion. By applying pre-tension after the fitting and fixing, an appropriate residual compressive stress is applied to the pin fixing portion (pin press-fitting portion) of the link evenly and accurately.

  In this specification, one end side in the length direction of the link is front and the other end side is rear, but this front and rear are for convenience, and the length direction of the link always coincides with the front and rear direction. It doesn't mean that.

  In the above power transmission chain, one of the pins (interpiece) is shorter than the other pin (pin), the end surface of the longer pin contacts the conical sheave surface of the pulley of the continuously variable transmission, It is preferable that power is transmitted by the frictional force due to this contact. Each pulley includes a fixed sheave having a conical sheave surface and a movable sheave having a conical sheave surface facing the sheave surface of the fixed sheave. The chain is sandwiched between the sheave surfaces of both sheaves, and the movable sheave. Is moved by a hydraulic actuator, the distance between sheave surfaces of the continuously variable transmission, that is, the wrapping radius of the chain is changed, and a continuously variable transmission can be performed with a smooth movement.

  The power transmission device according to the present invention includes a first pulley having a conical sheave surface, a second pulley having a conical sheave surface, and power transmission spanned between the first and second pulleys. And a power transmission chain as described above.

  This power transmission device is suitable for use as a continuously variable transmission such as an automobile.

  According to the power transmission chain and the power transmission device of the present invention, the change in the distance between the contact positions of the adjacent pins (the true pitch) due to the change in the pin / pulley contact diameter is suppressed, and the change in the chain circumference is thereby reduced. Thus, when used in a continuously variable transmission, the gear ratio of the continuously variable transmission can be stabilized.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, the top and bottom refer to the top and bottom of FIG.

  1 and 2 show the basic structure of a power transmission chain according to the present invention. The power transmission chain (1) is a front-rear insertion portion (12) (13) provided at a predetermined interval in the chain length direction. ) And a plurality of pins (first pin) (14) and an interpiece (second pin) for connecting the links (11) arranged in the chain width direction so as to be bendable in the length direction. (15). The interpiece (15) is shorter than the pin (14), and the pin (14) is wider in the front-rear direction than the interpiece (15). The pin (14) is opposed to the front side in a state of being arranged on the rear side.

  In the chain (1), three link rows composed of a plurality of links having the same phase in the width direction are arranged in the traveling direction (front-rear direction) to form one link unit, and the link unit composed of the three rows of link rows is the traveling direction. Are connected to each other.

  As shown in FIG. 2, the front insertion part (12) of each link (11) includes a pin movable part (16) to which the pin (14) is movably fitted and an interpiece to which the interpiece (15) is fixed. The rear insertion part (13) is composed of a fixed part (17), and the inter-piece movable part (19) in which the pin fixed part (18) to which the pin (14) is fixed and the inter-piece (15) are movably fitted together Consists of.

  Each pin (14) is wider in the front-rear direction than the interpiece (15), and the upper and lower edges of the interpiece (15) have protruding edges (15a) extending to the respective pins (14) side. ) (15b).

  In FIG. 2, the portions indicated by reference signs A and B are lines (points in the cross section) where the pin (14) and the interpiece (15) are in contact with each other in the straight portion of the chain (1), and the distance between AB. Is the pitch.

  When connecting the links (11) aligned in the chain width direction, the links (11) so that the front insertion part (12) of one link (11) and the rear insertion part (13) of the other link (11) correspond to each other ( 11) are overlapped with each other, the pin (14) is fixed to the rear insertion part (13) of one link (11) and movably fitted to the front insertion part (12) of the other link (11), The interpiece (15) is movably fitted to the rear insertion portion (13) of one link (11) and fixed to the front insertion portion (12) of the other link (11). The pins (14) and the interpiece (15) are relatively rolled and brought into contact with each other, whereby the links (11) can be bent in the length direction (front-rear direction).

  At the boundary between the pin fixing part (18) of the link (11) and the interpiece movable part (19), the upper and lower concave arcuate guide parts (19a) (19b) of the interpiece movable part (19) are connected. Upper and lower convex arc-shaped holding portions (18a) and (18b) for holding the pin (14) fixed to the pin fixing portion (18) are provided. Similarly, at the boundary between the interpiece fixing part (17) and the pin movable part (16), the upper and lower concave arcuate guide parts (16a) and (16b) of the pin movable part (16) are connected to the interpiece fixed part. Upper and lower convex arc-shaped holding portions (17a) and (17b) for holding the interpiece (15) fixed to the portion (17) are provided.

  The locus of the contact position between the pin (14) and the interpiece (15) with respect to the pin (14) is an involute of the circle, and in this embodiment, the rolling contact surface (14a) of the pin (14) However, the cross section has an involute shape having a basic circle with a radius Rb and a center M, and the rolling contact surface (15c) of the interpiece (15) is a flat surface (the cross-sectional shape is a straight line). As a result, when each link (11) moves from the straight portion of the chain (1) to the curved portion or from the curved portion to the straight portion, the pin (14) is fixed in the front insertion portion (12). The rolling contact surface (14a) of the piece (15) moves in the pin movable part (16) while being in rolling contact (including some sliding contact) with the rolling contact surface (15c) of the interpiece (15). In the rear insertion part (13), the rolling contact surface (15c) of the interpiece (15) is in contact with the pin (14) in contact with the pin (14) fixed in the interpiece movable part (19). It moves with rolling contact (including some sliding contact) on the surface (14a).

  This power transmission chain (1) holds the required number of pins (14) and interpieces (15) vertically on the assembly jig, and then press-fits one or several links (11) one by one. It is manufactured by doing. This press-fitting is performed between the upper and lower edges of the pin (14) and the interpiece (15) and the upper and lower edges of the pin fixing part (18) and the interpiece fixing part (17). It is set to 0.005 mm to 0.1 mm. In this way, tension is applied (pre-tensioned) to the assembled chain (1).

  The power transmission chain is used in the CVT. At this time, as shown in FIG. 6, each cone of the fixed sheave (2a) and the movable sheave (2b) of the pulley (2) having the pulley shaft (2e). The end surface of the pin (14) is in contact with the conical sheave surface (2c) (2d) of the pulley (2) while the end surface of the interpiece (15) is not in contact with the cylindrical sheave surface (2c) (2d). Power is transmitted by frictional force due to contact. As described above, the pin (14) and the interpiece (15) are guided by the movable parts (16) and (19) to move in rolling contact with each other, so that the sheave surfaces (2c) (2d) of the pulley (2) On the other hand, the pin (14) hardly rotates, the friction loss is reduced, and a high power transmission rate is secured. When the movable sheave (2b) of the drive pulley (2) at the position indicated by the solid line is moved closer to or away from the fixed sheave (2a), the winding diameter of the chain (1) is indicated by a chain line in the figure. As shown, it is large when approaching and small when separating. In the driven pulley, although not shown, when the movable sheave moves in the opposite direction to the movable sheave (2b) of the drive pulley (2) and the winding diameter of the drive pulley (2) increases, the driven pulley is wound. When the diameter is reduced and the winding diameter of the drive pulley (2) is reduced, the winding diameter of the driven pulley is increased. As a result, a U / D state in which the winding diameter of the drive pulley (2) is minimum and the winding diameter of the driven pulley is maximum is obtained based on the state (initial value) where the gear ratio is 1: 1. In addition, an O / D state can be obtained in which the winding diameter of the drive pulley (2) is maximum and the winding diameter of the driven pulley is minimum.

  Conventionally, the shape of the rolling contact surface (14a) of the pin (14) is one involute having a radius Rb and a base circle of the center M. As shown in FIG. 5, the true pitch in this case is small when the pin / pulley contact diameter is minimum, and first increases as the pin / pulley contact diameter increases, and then gradually increases. Becomes smaller. When the pin / pulley contact diameter is small, the true pitch change is large, and when the pin / pulley contact diameter is large, the true pitch change is small. In addition, the change in the true pitch when the pin / pulley contact diameter is small is smaller when the basic circle radius Rb is larger than when the basic circle radius Rb is small. The change in the true pitch when is large is smaller when the basic circle radius Rb is smaller than when the basic circle radius Rb is large.

  Since the change (variation) in the true pitch is a variation in the circumference of the chain, it is preferable to keep it small.

  Therefore, based on the above knowledge, in the power transmission chain (1) according to the present invention, as shown in FIG. 3, the rolling contact surface (14a) of the pin (14) has a plurality of shapes (three in the illustrated example). It is formed from the involute shape of the section, and the basic circle radius of each section is temporarily changed from the contact position on the side where the pin / pulley contact diameter is small to the contact position on the side where the pin / pulley contact diameter is large. That is, Rb is large when the pin / pulley contact diameter is small, Rb is large when the pin / pulley contact diameter is larger, and Rb is small when the pin / pulley contact diameter is large. Adjacent sections are tangent (smoothly connected).

  In order to obtain an appropriate base circle radius, in the same manner as in FIG. 3, it is determined for a plurality of base circle radii how the true pitch changes as the pin / pulley contact diameter increases, as shown in FIG. In addition, it is only necessary to connect the basic circle radii such that the true pitch is constant.

  Thus, according to the power transmission chain (1) of the present invention, the rolling contact movement between the pin (14) and the interpiece (15) causes the sheave surface (2c) (2d) of the pulley (2) to move. The involute-shaped characteristics that prevent the pin (14) from almost rotating are maintained, the friction loss is reduced, a high power transmission rate is ensured, and the change in the true pitch is suppressed. When this is used, the transmission ratio of the continuously variable transmission can be further stabilized.

FIG. 1 is a plan view showing a part of one embodiment of a power transmission chain according to the present invention. FIG. 2 is an enlarged side view of the link and the pin. FIG. 3 is a view showing the pin contact surface shape of the power transmission chain according to the present invention. FIG. 4 is a view for explaining the procedure for obtaining the pin contact surface shape of the power transmission chain according to the present invention. FIG. 5 is a diagram showing the relationship between the pin / pulley contact diameter and the true pitch. FIG. 6 is a front view showing a state in which the power transmission chain is attached to the pulley.

Explanation of symbols

(1) Power transmission chain
(2) Pulley
(2c) (2d) Conical sheave surface
(11) Link
(12) Front insertion part
(13) Rear insertion part
(14) Pin (1st pin)
(14a) Rolling contact surface
(15) Interpiece (2nd pin)

Claims (2)

A plurality of links having front and rear insertion portions through which pins are inserted, and a plurality of links arranged before and after connecting links aligned in the chain width direction so that a front insertion portion of one link and a rear insertion portion of another link correspond to each other. A first pin and a plurality of second pins, the rolling contact surface of one of the pins being a flat surface, and the rolling contact surface of the other pin being a predetermined curved surface, The two pins are relatively in rolling contact with each other so that the links can be bent in the longitudinal direction. The links are spanned between the pulleys of the continuously variable transmission, and at least one of the first pin and the second pin. In the power transmission chain that changes the gear ratio of the continuously variable transmission by changing the contact diameter between the pin and the pulley as well as transmitting the power by friction force by contacting one end surface with the sheave surface of the pulley,
The predetermined curved surface consists of a plurality of sections each having a predetermined involute shape, and the basic circle radius of the involute shape of each section is large on the side where the contact diameter between the pin and the pulley is small, and the contact diameter between the pin and the pulley A power transmission chain characterized by being small on the large side.   A power transmission chain comprising: a first pulley having a conical surface sheave surface; a second pulley having a conical surface sheave surface; and a power transmission chain spanned between the first and second pulleys. The power transmission device according to claim 1.

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