JP2007113727A - Power transmitting chain and power transmission device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power transmitting chain and a power transmission device, in which the lifetime of a chain is prolonged by taking into account the fact that a specified link often receives large force and by improving the durability. <P>SOLUTION: The power transmitting chain is provided with a plurality of the links, a plurality of pins, and a plurality of inter pieces. The maximum main stress value of the link is made to be equal to or more than the elasticity limit and equal to or less than the plasticity limit, and fatigue durability performance is improved, and with the usage of it, pretension is imparted so that the maximum main stress value generated in the first and second links from the outer side of the links arranged along the chain width direction is made to be the value. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  As a continuously variable transmission for an automobile, as shown in FIG. 6, a drive pulley (2) provided on the engine side having a fixed sheave (2a) and a movable sheave (2b), a fixed sheave (3b) and a movable sheave (3a) and a driven pulley (3) provided on the drive wheel side and an endless power transmission chain (1) spanned between them, and a movable sheave (2b) (3a) by a hydraulic actuator The chain (1) is clamped with hydraulic pressure by moving it toward and away from the fixed sheave (2a) (3b), and this clamping force makes contact between the pulley (2) (3) and the chain (1). It is known that a load is generated and torque is transmitted by the frictional force of the contact portion.

As a power transmission chain, in Patent Document 1, 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 correspond to the chain width direction. A plurality of first pins and a plurality of second pins that connect the links arranged in a row so as to be bendable in the length direction, and are fixed to the front insertion portion of one link and movable to the rear insertion portion of another link The first pin that is fitted and the second pin that is movably fitted to the front insertion portion of one link and fixed to the rear insertion portion of the other link are relatively rolled and moved in contact with each other. Those that can be bent in the length direction have been proposed.
JP 2005-233275 A

  In this type of power transmission chain, the durability of the link is particularly important. In addition, the force received by each link of a plurality of links constituting one chain differs depending on the arrangement position, and the outermost link in the width direction is a torque caused by friction between the sheave surface of the pulley and the end surface of the pin. In the transmission type, the pin is pulled in the direction of travel of the chain by frictional force, so a bending moment is generated and the pin is deformed with respect to its axial direction. It is disadvantaged.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a power transmission chain and a power transmission device in which the life of a chain is improved by considering that a specific link is easily subjected to a large force and improving its durability.

  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 are provided, and the first pin and the second pin are relatively rolled and brought into contact with each other, whereby the links can be bent in the length direction. In the power transmission chain, a tension is applied to the chain in advance so that the maximum principal stress value of a predetermined link among the links arranged in the chain width direction is not less than the elastic limit of the link and not more than the plastic limit. It is.

  In this type of power transmission chain, when a fatigue endurance test is performed, a link arranged at a specific position (usually the outermost link in the chain width direction or the innermost link) There is a tendency for fatigue to progress first. The “predetermined link arranged in the chain width direction” means a link in which fatigue progresses earlier in this tendency.

  The pre-tension applied to the link and the maximum principal stress are almost linear, but the life of the link is greater than when the maximum principal stress is less than the elastic limit stress because the maximum principal stress is greater than or equal to the elastic limit stress. Greatly improved. For example, a link loaded with a pretension so as to have a maximum principal stress not less than the elastic limit stress and not more than the plastic limit (elastic limit value × 1.04) is less than the elastic limit stress (elastic limit value × 0.97). The service life is significantly improved (4 times or more) compared to a link loaded with a pretension so as to have the maximum principal stress. That is, fatigue durability performance can be improved by plastically deforming the link with pretension and applying residual compressive stress inside the link.

  On the other hand, the force received by the link differs depending on the arrangement position in the width direction. In a chain in which at least one of the first pin and the second pin contacts the pulley and transmits power by frictional force, the outer link (especially the outermost link) The link and the link on the inner side of the pin are susceptible to a large force due to the deformation of the pin in the axial direction, which is disadvantageous in terms of fatigue life. Therefore, by applying pretension to the chain so that the maximum principal stress is equal to or greater than the elastic limit stress for the two links on the outside, the fatigue life of the link is greatly improved. To improve.

  Specifically, the pre-tension to be applied has a maximum principal stress value of elastic limit value × 1.01-1.09, more preferably a maximum principal stress value of elastic limit value × 1.02-1. The size may be 06, or the tension corresponding to the elastic limit × 1.01-1.20, more preferably the tension corresponding to the elastic limit × 1.05-1.15.

  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 ( The other pin is referred to as a “pin” (hereinafter referred to as an “interpiece”), and the other pin is referred to as an interpiece or strip (hereinafter referred to as “interpiece”).

  Due to the chain mechanism in which at least one of the first pin and the second pin is in contact with the pulley and transmits power by frictional force, the link extending in the width direction tends to have a relative extension amount of the outer link. (A disadvantage for fatigue life). On the other hand, the number of links arranged in the width direction is not all the same, but the number of links in each link row is made large and small, for example, two link rows with 8 links and 9 links. It is preferable to configure a chain by arranging a plurality of link units with one row as one unit (link unit). In this case, each link in the eight link rows has a relatively large amount of elongation (disadvantageous in fatigue life) compared to each link in the nine link rows.

  Therefore, the fatigue life of the chain can be significantly improved by setting the pre-tension so that the maximum principal stress value of the link which is disadvantageous to the fatigue life is not less than the elastic limit of the link and not more than the plastic limit.

  One of the first pin and the second pin may be press-fitted and fixed to the front and rear insertion portion of the link, and both may not be fixed (movably fitted). Further, the first pin and the second pin may have different cross-sectional shapes or the same shape. Furthermore, the first pin and the second pin may be the same length, both may be in contact with the sheave surface, and may be of different lengths so that only the longer one is in contact with the sheave surface. Also good. Moreover, as for a link, the front-and-rear insertion part may be an independent through-hole (link with a pillar), respectively, and the front-rear insertion part may be a single through-hole (link without a pillar).

  For example, the first pin and the second pin are formed in a required curved surface so that either one of the contact surfaces is a flat surface and the other contact surface can be relatively rolled and moved. Moreover, you may make it each contact surface form a required curved surface for the 1st pin and the 2nd pin. In any case, the contact surface shape of each pin is formed in two types (for example, one having a relatively large curvature and one having a relatively small curvature), so that the pins having different trajectories of rolling contact movement are formed. There may be two types of sets. The locus of the contact position between the first pin and the second pin is, for example, a circle involute.

  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.

  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. Appropriate steel such as bearing steel is used as the material of the pin.

  When the pin is fixed to the front and rear insertion portion, the pin is fixed to the front and rear insertion portion, for example, by fitting and fixing the inner edge of the insertion portion and the outer peripheral surface of the pin by mechanical press-fitting. It may be a fit or a cold fit. 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. This 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.

  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 in any of the above.

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

  According to the power transmission chain and the power transmission device of the present invention, the maximum principal stress value of a predetermined link (link in which fatigue progresses first) among the links arranged in the chain width direction is greater than the elastic limit of the link and is plastic. By preloading the chain with the tension below the limit, the elongation is larger than other links and the internal stress is increased. As a result, the life of the chain is improved.

  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.

  FIGS. 1 and 2 show a part of a power transmission chain according to the present invention. The power transmission chain (1) has front and rear insertion parts (12) (13) provided at predetermined intervals 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).

  As shown in FIG. 3, in the front insertion part (12), the pin fixing part (12a) to which the pin (14) (shown by a solid line) is fixed and the interpiece (15) (shown by a two-dot chain line) are movable. The inter-piece movable part (12b) can be fitted to the rear insertion part (13), and the pin insertion part (13a) and the inter-piece (13) to which the pin (14) (indicated by a two-dot chain line) can be movably fitted. 15) It consists of an interpiece fixing part (13b) to which (shown by a solid line) is fixed. When connecting the links (11) arranged in the chain width direction, the front insertion part (12) of one link (11) and the rear insertion part (13) of the other link (11) correspond to each other. The links (11) are overlapped, and the pin (14) is fixed to the front insertion part (12) of one link (11) and movably fitted to the rear insertion part (13) of the other link (11) The interpiece (15) is movably fitted to the front insertion part (12) of one link (11) and fixed to the rear insertion part (13) 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).

  The locus of the contact position between the pin (14) and the interpiece (15) relative to the pin (14) is an involute of the circle.In this embodiment, the contact surface (14a) of the pin (14) is The cross section has an involute shape having a basic circle with a radius Rb and a center M, and the contact surface (15a) 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 part of the chain (1) to the arc part or from the arc part to the straight part, the interpiece (15) is movable in the front insertion part (12). The contact surface (15a) moves to the contact surface (14a) of the pin (14) while rolling (including some sliding contact) against the pin (14) in the fixed state in the part (12b) In the insertion part (13), the contact surface (14a) rolls against the contact surface (15a) of the interpiece (15) against the interpiece (15) with the pin (14) fixed (slightly sliding contact) The pin movable part (13a) is moved. In FIG. 3, 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). Is the pitch.

  Chain (1) consists of three link rows (R1), (R2), and (R3) that are composed of multiple links in the same direction in the width direction. A plurality of link units composed of link rows (R1), (R2), and (R3) are connected in the traveling direction. In this embodiment, the link row (R1) having nine links and the two link rows (R2) (R3) having eight links are used as one link unit.

  In the above embodiment, the front insertion portion (12) and the rear insertion portion (13) are independent through holes, but the through holes for obtaining these insertion portions (12) (13). Although not shown in the figure, in order to relieve stress concentration at the hole edge, the front and rear insertion parts (12) and (13) are communicated with each other by a communication part so that the entire front and rear is formed as one through hole. Good.

  This power transmission chain (1) holds the required number of pins (14) and interpieces (15) vertically on the table, and then press-fits one or several links (11) one by one. It is manufactured by going. 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 (12a) and the interpiece fixing part (13b). It is set to 0.005 mm to 0.1 mm. Thus, pretension is applied to the assembled chain (1).

  FIG. 4 shows the pre-tension of two types of links ((A) and (B)) made of SUJ2 (high carbon chrome bearing steel), subjected to austempering as heat treatment, and having a hardness of HRC45. The relationship with the maximum principal stress generated in the link is obtained. The elastic limit of this link is about 1270 MPa, and the corresponding tension is about 2.2 kN in (A) and about 2.8 kN in (B).

  Regarding fatigue endurance performance, the life of (A) provided with a pretension exceeding the elastic limit is 38.8 hours, and the life of (B) provided with a pretension exceeding the elastic limit is 40 hours or more. On the other hand, the lifetimes of (A) and (B) with a pretension less than the elastic limit were both less than 10 hours.

  For this reason, the pre-tension is set so that the maximum principal stress value generated in the link (especially the pin press-fit portion) is greater than the elastic limit of the link and less than the plastic limit. It can be seen that residual compressive stress is applied to) and the life of the link can be improved. That is, the present invention is particularly effective in the press-fit type chain in which the pins (including the interpiece) (14) (15) and the link (11) are press-fitted and fixed. In the above embodiment in which the link row (R1) with nine links and the two link rows (R2) (R3) with eight links are one link unit, the number of links (11) is as follows. There is a tendency that the outermost link of the eight link rows (R2) and (R3), which are relatively few, and the link (11) on the inner side of the link row (R3) are more fatigued earlier than the other links (11). Therefore, among the links (11) arranged in the chain width direction of these link rows (R2) (R3), the maximum principal stress value of the links (11) from the outside to the second one from the outside is not less than the elastic limit of the link (11) and By preloading the chain (1) with a pretension that is less than the plastic limit, the fatigue progression of these links (11) is suppressed, and the fatigue durability of the chain (1) can be greatly improved. it can.

  This power transmission chain (1) is used in the CVT shown in FIG. 5. At this time, for example, the interpiece (second pin) (15) is made shorter than the pin (first pin) (14). The end surface of the pin (14) is not in contact with the conical sheave surfaces (2c) and (2d) of the fixed sheave (2a) and the movable sheave (2b) of the pulley (2). Contact is made with the conical sheave surfaces (2c) and (2d) of the pulley (2), and power is transmitted by the frictional force caused by the contact. As described above, since the pin (14) and the interpiece (15) are in rolling contact, the pin (14) hardly rotates relative to the sheave surfaces (2c) (2d) of the pulley (2). Thus, friction loss is reduced and a high power transmission rate is secured.

  The pre-tension condition can be applied to a chain in which the lengths of the first pin and the second pin are substantially equal, both of which are in contact with the sheave surface. The present invention can be applied to a chain in which both are movably fitted to the front and rear insertion portions and various other types of power transmission chains.

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 perspective view of the same. FIG. 3 is an enlarged side view of the link. FIG. 4 is a graph showing the relationship between pretension and maximum principal stress and the relationship between elastic limit stress and wear. FIG. 5 is a front view showing a state in which the power transmission chain is attached to the pulley. FIG. 6 is a perspective view showing an example of a continuously variable transmission in which the power transmission chain according to the present invention is used.

Explanation of symbols

(1) Power transmission chain
(2) (3) Pulley
(2a) (3b) Fixed sheave
(2b) (3a) Movable sheave
(2c) (2d) Conical sheave surface
(11) Link
(12) Front insertion part
(13) Rear insertion part
(14) Pin (1st pin)
(15) Interpiece (2nd pin)
(R1) (R2) (R3) Link string

Claims (5)

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. In the power transmission chain provided with the first pin and the plurality of second pins, the first pin and the second pin are relatively in rolling contact with each other, so that the links can be bent in the longitudinal direction.
A power transmission chain, wherein a tension is applied to the chain in advance so that a maximum principal stress value of a predetermined link among the links arranged in the chain width direction is not less than the elastic limit of the link and not more than the plastic limit.   2. The power transmission chain according to claim 1, wherein a tension is applied to the chain in advance so that the maximum principal stress value of the links from the outside to the second one of the links arranged in the chain width direction is not less than the elastic limit of the link and not more than the plastic limit.   The power transmission chain includes first, second, and third link rows each having a plurality of links arranged in the chain width direction, and at least one link of the first, second, and third link rows. The maximum principal stress value of the links from the outside to the second link in the chain width direction of the link row where the number of links in the row is smaller than any other link row and the number of links is relatively small The power transmission chain according to claim 2, wherein a tension is applied to the chain in advance so that the tension is greater than the elastic limit of the link and less than the plastic limit.   One of the first pin and the second pin is fixed to the front insertion portion of one link and is movably fitted to the rear insertion portion of the other link, and the other is the front insertion portion of the one link. The power transmission chain according to any one of claims 1 to 3, wherein the power transmission chain is movably fitted to the rear and fixed to a rear insertion portion of another link.   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. A power transmission device according to claim 1.

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