JP6812890B2 - Chain of continuously variable transmission - Google Patents

Description

The present invention relates to a chain of a chain type continuously variable transmission, and more particularly to a chain structure.

A continuously variable transmission is known which includes two pulleys having conical surfaces which are opposed to each other and whose distances can be changed from each other, and a flexible endless member is wound around these two pulleys. The rotation of one pulley is transmitted to the other pulley by the flexible endless member. At this time, by changing the distance of the conical surface, the winding radius of the flexible endless member with respect to the pulley is changed, and the gear ratio can be changed. A chain used as a flexible endless member of a continuously variable transmission is disclosed in Patent Document 1 below.

This chain is formed by arranging a plurality of chain elements in the circumferential direction of the chain and connecting them. Each chain element has a plate-shaped link with an opening and pins and interpieces that penetrate the opening at both ends of the link, respectively. The links are arranged along the circumferential direction of the chain, and a plurality of links are arranged in the width direction. The pins penetrate the links arranged in the width direction. Both ends of the pin abut on the conical surface of the pulley. Adjacent chain elements are connected by passing the pins of one element of the adjacent chain element through the opening of the other element. Power is transmitted between the chain elements via the contact surfaces between the pins. The pins that come into contact roll into contact with each other on the contact surface, and the chain is allowed to bend.

Further, Patent Document 1 below describes suppression of vibration of a linear portion of a chain wound around two pulleys. The first cause of this vibration is that the pin located at the boundary between the linear part of the chain and the arcuate part in the pulley moves up and down when the arc moves with the rotation of the pulley. Secondly, it is mentioned that the subsequent chain is lifted by making an angle between the adjacent chain elements (see paragraph 0032). It is described that vibration is suppressed by suppressing the lifting of the chain at the initial stage of bending of the chain, that is, when the angle between the chain elements is small, and by allowing the chain to be lifted after the angle between the chain elements becomes large. (See paragraph 0041).

The action of lifting the succeeding chain is caused by the position of the contact point between the pins moving between when the chain is linear and when the chain is bent. A couple is generated by the difference in the contact point position of the pin between the linear state and the bent state, and this couple lifts the succeeding chain (see paragraphs 0025 to 0028).

Japanese Patent No. 5951427

The chain is repeatedly bent, and the contact points between the pins move each time. This movement causes fluctuations in the stress distribution of the link, which may result in a large portion of the stress amplitude.

An object of the present invention is to reduce the stress amplitude while suppressing the vibration of the chain.

The chain of the continuously variable transmission of the present invention is wound around and orbits by two pulleys having conical surfaces that are opposed to each other and whose distances can be changed from each other. The chain is a flexible endless member in which a plurality of chain elements are connected. Each chain element includes a link unit composed of a plurality of plate-shaped links having openings and two pins penetrating the links. The links constituting the link unit are arranged one by one along the circumferential direction of the chain and arranged in the width direction of the chain. Two pins are arranged so as to penetrate the links arranged in the width direction. More specifically, the two pins each penetrate the opening of the link at both ends of the link. A pin of one element of an adjacent chain element in the circumferential direction of the chain is passed through the opening of the link of the other element, whereby the adjacent chain elements are connected to each other.

The pins of adjacent chain elements come into contact with each other on their sides, and the tension acting on the chain is transmitted. When the chain bends, the pins that come into contact and transmit tension come into rolling contact with each other. That is, as the chain bends, the contact points between the pins move continuously. The shape of the contact surface of the pin is such that the contact point moves to the outside of the chain as the chain bends. This movement of the contact point acts on the subsequent chain element with a couple that lifts its trailing end, that is, moves it out of the chain.

The amount of movement of the contact point when the chain is bent is determined by the shape of the contact surface of the pin. The contact surface has two opposing surfaces, and the relative relationship between these surfaces determines the amount of movement. One contact surface can be a flat surface and the other can be a curved surface. Further, both of the two contact surfaces can be curved surfaces, and in this case, the curvature of the other curved surface when one is a flat surface is assigned to the two curved surfaces, so that the combination of the flat surface and the curved surface is used. The same effect as can be obtained. The relative shape of this contact surface in the cross section orthogonal to the chain width direction is referred to as a relative action curve.

The relative action curve is between the start point, which is the pin contact point when the chain extends linearly, the pin contact point, which is the pin contact point when the chain has the minimum winding radius, and the start point and the end point. It has a certain boundary point, the section from the start point to the boundary point matches the tentative relative action curve described later, and the section from the boundary point to the end point is the rate of increase of the movement amount of the contact point with respect to the angle between adjacent elements. The rate of increase in a certain contact point movement decreases as the angle between adjacent elements increases.

The tentative relative action curve consists of a tentative start point that coincides with the start point of the relative action curve and a tentative end point that is in the range of 0.35 to 0.7 times the pin dimension from the tentative start point to the outside in the chain thickness direction in the chain thickness direction. And, the tentative start point and the tentative end point coincide with the tentative start point and the tentative end point when the tentative relative action curve has an involute shape, and further, the tentative relative action curve has a tentative contact point movement amount increase rate. The shape is smaller when the angle between adjacent elements is smaller and larger when the angle between adjacent elements is larger than when the relative action curve has an involute shape.

The boundary point of the relative action curve is located in a range in which the contact point movement amount increase rate is larger than that in the case where the false relative action curve has an involute shape.

Since the tentative action curve has the above shape, the lifting effect is suppressed when the bending of the chain is small, and the lifting effect is increased when the bending of the chain is large, from the start point to the boundary point of the relative action curve. As a result, vibration of the string portion between the pulleys of the chain is suppressed. Beyond the boundary point of the relative action curve, the rate of increase in the amount of contact point movement is reduced, the amount of contact point movement is suppressed, and thus the stress fluctuation of the link is suppressed.

When the bending of the chain is small, the lifting effect is suppressed, and when the bending of the chain is large, the lifting effect is increased, so that the vibration of the string part of the chain is suppressed, and when the bending of the chain is further increased, the movement amount of the contact point is suppressed. By doing so, the stress fluctuation of the link is suppressed.

It is a figure which shows the main part of the chain type continuously variable transmission. It is the figure which looked at the chain from the width direction. It is a perspective view for demonstrating the structure of a chain. It is the figure which looked at the chain from the thickness direction. It is explanatory drawing about the force which lifts a chain element. It is explanatory drawing about the displacement of the chain chord part when there is no lifting effect. It is explanatory drawing about the displacement of the chain chord part when there is no lifting effect. It is explanatory drawing about the displacement of the chain chord part when there is a lifting effect. It is explanatory drawing about the displacement of the chain chord part when there is a lifting effect. It is explanatory drawing about the displacement of the chain chord part at the time of having a lifting effect and suppressing the lifting effect when the angle between adjacent elements is small. It is explanatory drawing about the displacement of the chain chord part at the time of having a lifting effect and suppressing the lifting effect when the angle between adjacent elements is small. It is a figure which shows the contact surface of a pin. It is a figure which shows the dimensional relationship of a pin. It is a figure which shows the example of the tentative action curve which represents the contact surface of a pin. It is a figure which shows the specific example of the tentative action curve. It is a figure which shows the movement amount of the contact point with respect to the angle between adjacent elements in a tentative action curve. It is a figure which shows the relationship between the winding diameter and the displacement of a chain chord part in a tentative action curve. It is a figure which shows the movement amount of the contact point with respect to the angle between adjacent elements in various action curves. It is a figure which shows the relationship between the winding diameter and the displacement of a chain chord part in various action curves.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Device overview]
FIG. 1 shows a main part of the chain type continuously variable transmission 10. The chain type continuously variable transmission 10 has two pulleys 12 and 14 and a chain 16 wound around these pulleys. One of the two pulleys is referred to as an input pulley 12, and the other is referred to as an output pulley 14. The input pulley 12 has a fixed sheave 20 fixed to the input shaft 18 and a movable sheave 22 that can slide and move along the input shaft 18 on the input shaft 18. The facing surfaces of the fixed sheave 20 and the moving sheave 22 have a substantially conical side surface shape. These surfaces are referred to as substantially conical surfaces 24 and 26. A V-shaped groove is formed by the substantially conical surfaces 24 and 26, and the chain 16 is located in the groove so that the side surface is sandwiched between the substantially conical surfaces 24 and 26. Like the input pulley 12, the output pulley 14 also has a fixed sheave 30 fixed to the output shaft 28 and a movable sheave 32 that can slide and move along the output shaft 28. The facing surfaces of the fixed sheave 30 and the moving sheave 32 have a substantially conical side surface shape. These surfaces are referred to as substantially conical surfaces 34 and 36. A V-shaped groove is formed by the substantially conical surfaces 34 and 36, and the chain 16 is located in the groove so that the side surface is sandwiched between the substantially conical surfaces 34 and 36.

The arrangement of the fixed sheave and the moving sheave of the input pulley 12 and the output pulley 14 is reversed. That is, in the input pulley 12, the moving sheave 22 is on the right side in FIG. 1, whereas in the output pulley 14, the moving sheave 32 is arranged on the left side. By sliding the moving sheaves 22, 32, the distances of the substantially conical surfaces 24, 34, 26, 36 facing each other change, and the width of the V-shaped groove formed by these substantially conical surfaces changes. The change in the groove width changes the winding radius of the chain. That is, when the moving sheaves 22 and 32 are separated from the fixed sheaves 20 and 30, the groove width is widened, the chain 16 is moved to a deep position in the groove, and the winding radius is reduced. On the contrary, when the moving sheaves 22 and 32 approach the fixed sheaves 20 and 30, the groove width becomes narrower, the chain 16 moves to a shallow position of the groove, and the winding radius becomes larger. By reversing the change in the winding radius between the input pulley 12 and the output pulley 14, the chain 16 is prevented from sagging. As the moving sheaves 22 and 32 slide, the width of the V-shaped groove changes continuously, and the winding radius also changes continuously. As a result, the gear ratio in the transmission from the input shaft 18 to the output shaft 28 can be continuously changed.

2 to 4 are diagrams showing details of the structure of the chain 16. In the following description, the direction along the extending direction of the chain 16 is the circumferential direction, the direction orthogonal to the circumferential direction, the direction parallel to the input shaft 18 and the output shaft 28 is the width direction, and the direction orthogonal to the circumferential direction and the width direction is the thickness. It is written as the direction. FIG. 2 is a view of a part of the chain 16 viewed from the width direction, FIG. 3 is a view showing a part of the chain 16 extracted and disassembled, and FIG. 4 is a view of a part of the chain 16 viewed from the outer peripheral side in the thickness direction. Is.

In FIG. 2, the left-right direction is the circumferential direction, the vertical direction is the thickness direction, and the direction penetrating the paper surface is the width direction. Further, the upper side is the outer side of the chain 16. The chain 16 is formed by combining a plate-shaped link 40 having openings 38a and 38b and rod-shaped pins 42a and 42b. The individual links 40 have the same shape including the thickness, and the rod-shaped pins 42a and 42b have the same shape. The links 40 are arranged in a predetermined pattern in the width direction (see FIG. 4), and two pins 42a and 42b penetrate the openings 38a and 38b at both ends of the link. Both ends of the two pins 42a and 42b, or both ends of any one of the pins, abut on the substantially conical surfaces 24, 26, 34, 36 of the input and output pulleys 12, 14. The pair of the two pins 42a and 42b and the link penetrated through the pins is referred to as a chain element 44 (see FIG. 3).

FIG. 3 shows the two chain elements 44-1 and 44-2 in a partially omitted state. The subscripts "-1", "-2", and "-3" are used to distinguish the chain element and the links and pins belonging to the chain element from other elements. The chain element 44-2 is composed of a plurality of links 40-2 and two pins 42a-2 and 42b-2 penetrating the links 40-2. The two pins 42a-2 and 42b-2 are press-fitted or fixedly positioned at the openings 38a-1 and 38b-1 at both ends of the link 40-2, respectively. Similarly, the chain element 44-1 is also composed of a plurality of links 40-1 and two pins 42a-1 and 42b-1 penetrating the links 40-1. Further, a plurality of links 40 belonging to one chain element constitute the link unit 46.

The connection of the adjacent chain elements 44-1 and 44-2 is achieved by passing the pins 42a and 42b through the openings 38a and 38b of the links 40 on the opposite sides of each other. As shown in FIG. 3, the pin 42b-2 of the left chain element 44-2 is arranged in the opening 38a-1 so as to be located on the right side of the pin 42a-1 of the right chain element 44-1. .. Conversely, the pin 42a-1 of the right chain element 44-1 is arranged in the opening 38b-2 so as to be located to the left of the pin 42b-2 of the left chain element 44-2. The two pins 42b-1 and 42a-2 come into contact with each other on their side surfaces, and the tension of the chain 16 is transmitted. When the chain 16 bends, adjacent pins, such as pins 42b-1 and 42a-2, move so as to roll on each other's contact surfaces, allowing bending.

FIG. 4 is a diagram showing an example of the arrangement pattern of the link 40. The individual links 40 belong to one column, and these columns are referred to as the first column, the second column, and so on from the lower side in the figure. In the example shown in FIG. 4, the link 40 in the first column belongs to the first link unit 46-1, the link 40 in the second column belongs to the second link unit 46-2, and the link in the third column belongs to the link 40. 40 belongs to the third link unit 46-3.

[Chain lifting effect]
FIG. 5 is a diagram showing a portion where the chain 16 starts to enter the pulley. The chain 16 moves to the right along the arrow A in the figure. The pin 42a-1 of the chain element 44-1 is sandwiched by the pulley 12 (or 14), and starts a circular motion integrated with the pulley. The chain element 44-2 following the chain element 44-1 and the subsequent chain element 44-3 have not yet entered the pulley and belong to a linear portion passed between the pulleys. Hereinafter, a portion of the chain 16 in which both pulleys are in circular motion will be referred to as an arc portion, and a linear portion passed between the pulleys will be referred to as a string portion. Further, although the pulley 12 will be described below for simplicity, the same applies to the pulley 14.

In most of the chain elements that belong to the chord portion, the adjacent chain elements 44 are located along a straight line and have no relative angle. However, when the chain element 44 belongs to the arc portion, an angle is formed with the following element. In FIG. 5, the preceding chain element 44-1 belongs to the arc portion and is relatively angled with the following chain element 44-2. Hereinafter, this angle will be referred to as "angle between adjacent elements". As will be described in detail later, among the chain elements belonging to the straight line portion, those located near the boundary with the arc portion may have an angle between the adjacent chain elements. However, only in the explanation with respect to FIG. 5, it is assumed that the chain elements 44-2 and 44-3 are located on a straight line.

When two adjacent chain elements 44 are located on a straight line, the contact point C between the pins is located inside (lower side in FIG. 5) in the thickness direction of the chain. As shown in FIG. 5, the contact point C between the pin 42a-2 of the preceding chain element 44-2 and the pin 42b-3 of the succeeding chain element 44-3 is at the position of the lower point C1. When the preceding chain element begins to enter the pulley, the angle between adjacent elements increases, and the contact point C gradually moves upward accordingly. The preceding chain element 44 completely belongs to the arc portion when the rear pin 42a is sandwiched between the pulleys. This state is the chain element 44-1 of FIG. 5, and the contact point C between the pin 42a-1 of the preceding chain element and the pin 42b-2 of the succeeding chain element at that time is the position of the point C2. .. The contact point between the pins is actually a range having a region instead of a point due to deformation due to the contact pressure of the pins. Here, it is described as an ideal state in which the pins are in perfect rigid body and point contact.

In this way, when the positions of the two contact points C belonging to one chain element (for example, 44-2) are displaced in the thickness direction, a couple is generated by the tension T acting on the chain element. This couple produces a force F that lifts the rear end of the chain element. This couple or lifting force increases as the distance between the contact points C1 and C2 in the thickness direction increases. Therefore, the couple or lifting force increases as the preceding chain element 44 enters the arc portion from the chord portion.

[Displacement of the string part of the chain]
Next, the displacement of the chord portion of the chain 16 will be described. 6 and 7 are explanatory views of the displacement of the chain when the couple for lifting the rear end of the chain element is not generated, that is, when there is no lifting effect. FIG. 6 shows a state immediately after the pin 42a-1 behind the preceding chain element 44-1 is sandwiched by the pulley 12. When the pin is indicated by a black circle (for example, pin 42a-1), it means that it is sandwiched by the pulley 12, and when it is indicated by a white circle with a diagonal line (for example, pin 42a-2), it means that it is not sandwiched by the pulley 12. Represents. Subsequent chain elements 44-2, 44-3 extend rearward from pin 42a-1 at the same height as this pin. FIG. 7 shows a state when the chain 16 advances and the pin 42a-1 comes to the highest position (the highest position in the figure) of the pulley. Also at this time, the following chain elements 44-2 and 44-3 extend rearward from the pin 42a-1 at the same height as this pin. The chain is displaced between the states shown in FIGS. 6 and 7, that is, with the displacement amount d1.

8 and 9 are diagrams for explaining the lifting effect of the chain 16. FIG. 8 shows a state immediately before the chain element 44-2 is completely inserted into the pulley 12, that is, a state immediately before the pin 42a-2 of the chain element 44-2 is pinched by the pulley 12. The chain element 44-2 and the chain element 44-1 preceding the chain element 44-2 form an angle θ1 (angle between adjacent elements). As a result, the above-mentioned couple acts on the chain element 44-2 to exert a lifting force. As a result, the pin 42a-2 is located higher than the pin 42a-1 of the preceding chain element 44-1. Since the chain element 44-2 is lifted, an angle θ2 is also provided between the chain element 44-2 and the subsequent chain element 44-3. Therefore, a couple that lifts the chain element 44-3 also acts. Furthermore, a couple also acts on the subsequent chain element 44-4. In this way, a couple acts not only on the chain element 44-2 immediately before the pulley enters, but also on the chain element (for example, 44-3, 44-4) following the chain element 44-2.

FIG. 9 shows a state when the chain element 44a is completely inserted into the pulley 12. After that, the pin 42a-2 is sandwiched by the pulley 12 and moves with the rotation of the pulley 12. During this time, a couple acts on the following chain elements 44-3 and 44-4 that have not entered the pulley, and these elements are lifted. Therefore, the string portion of the chain 16 is lifted to the position indicated by the white circle and the alternate long and short dash line in FIG. The displacement of the string portion at this time is d2 shown in FIG.

Without the lifting effect, as shown in FIGS. 6 and 7, the displacement of the chord portion of the chain 16 is directly controlled by the movement of the pin 42a-1 in the pulley, and the displacement becomes large. However, in the case of FIGS. 8 and 9, not only the position of the pin 42a-2 but also the lifting effect due to the angle between the adjacent elements affects the displacement of the chord portion. Therefore, in the case of FIGS. 8 and 9, the displacement of the chord portion of the chain 16 is not directly controlled by the movement of the pin 42a-2. Even when the pin 42a-2 is near the highest point in the pulley 12 (42a'-2 in FIG. 9), the chain element 44'-3 is lifted, and the upper limit of the displacement of the chord portion is that of the pin 42a'-2. It will be higher than the position. The displacement is reduced by lifting the chain element before it enters the pulley. However, when the pin is near the highest point and the subsequent chain element is lifted, the chord portion becomes higher and acts in the direction of increasing the displacement of the chord portion. If this point is improved, there is a possibility that the displacement of the chord portion can be further suppressed. That is, the couple is made relatively small between the position where the pin enters the pulley 12 and the vicinity of the highest point, and a large couple is generated when the subsequent chain element is just before entering the pulley. Therefore, it can be expected that the displacement of the string portion is suppressed. In other words, this is achieved by keeping the couple small when the angle between adjacent elements is small and increasing the couple as this angle increases.

10 and 11 are diagrams showing an example in which the displacement of the string portion is suppressed as compared with the cases of FIGS. 8 and 9. FIG. 10 shows a state immediately before the chain element 44-2 is completely inserted into the pulley 12, that is, a state immediately before the pin 42a-2 of the chain element 44-2 is pinched by the pulley 12. The chain element 44-2 and the chain element 44-1 preceding the chain element 44-2 form an angle θ4 (angle between adjacent elements). The angle between adjacent elements between the chain element 44-2 and the chain element 44-3 following it is θ5. When the angle is θ4, the chain element 44-2 is lifted so that a relatively large couple acts. As a result, the position where the pin 42a-2 is first sandwiched by the pulley 12 becomes a relatively high position (see FIG. 11). On the other hand, when the angle between adjacent elements is as small as θ5, the couple is made small and the lifting of the chain element 44-3 is suppressed. Even when the pin 42a-2 is near the highest point in the pulley (position of 42a'-2 in FIG. 11), the couple is small and the chain element 44'-3 is not lifted significantly. After the pin 42a-2 has passed the highest point, the position of the pin 42a-2 becomes lower, but the lifting effect becomes larger, and the rear end of the subsequent chain element 44-3 is lifted. As a result, the position of the pin 42a-3 of the succeeding chain element 44-3 is suppressed from being lowered together with the pin 42a-2 of the preceding element, and the chain element 44-3 enters the pulley at a high position. Therefore, the displacement of the chord portion of the chain 16 becomes small as shown by d3 in FIG.

[Action curve]
The relationship between the angle between adjacent elements and the couple can be adjusted by appropriately determining the shape of the contact surface between the pins that come into contact with each other. The shape of this contact surface will be described. The side surface shapes of the pins 42a and 42b are constant in the width direction of the chain 16, and will be described below as shapes in a cross section orthogonal to the width direction. Therefore, the contact surface appears as a line in this cross section. This line is referred to as the action curve.

FIG. 12 shows a coordinate system for representing the shape of the contact surface (action curve). The origin is the contact point between the two pins 42a-1 and 42b-2 when the chain 16 extends linearly. The x-axis represents the extending direction (circumferential direction) of the chain 16, and the y-axis represents the thickness direction. The action curve 50a of the pin 42a-1 is a curve, and the action curve 50b of the pin 42b-2 is a straight line corresponding to the y-axis. The change in the position of the contact point is determined by the interval between the two action curves 50a and 50b, and the curve representing this interval is referred to as a "relative action curve". In the example of FIG. 12, since one action curve 50b is a straight line, the relative action curve is the other action curve 50a itself. When the two action curves are curves, the action curve is defined so that the distance between the points of the same y-coordinate on the two action curves is equal to the distance between the action curve 50a and the y-axis at the same y-coordinate. ..

The action curve of the chain 16 is determined by first determining a tentative action curve and then modifying this tentative action curve. For the sake of distinction, the tentative action curve will be referred to as the "tentative action curve" hereafter, and the modified action curve will be referred to as the "modified action curve".

(Pseudo-action curve)
The tentative action curve is defined between the contact point of the pin when the chain 16 is in a straight line state and the tentative contact point determined from the dimensions of the pin. FIG. 13 is a diagram showing a linear state of the chain 16. The thickness direction of the pin 42a-1 is ta, and the thickness direction of the pin 42b-2 is tb. The contact point (contact point of the action curve) between the pin 42a-1 and the pin 42b-2 in the linear state is the point Cs. This point Cs is referred to as a "temporary starting point". From the temporary start point Cs, a point Ce is set on the outside in the thickness direction at a position 0.35 to 0.70 times the smaller of the thickness direction dimensions ta and tb of the pin. This point Ce is referred to as a "temporary end point". The tentative action curve is defined between the tentative start point Cs and the tentative end point Ce by the same method as the action curve shown in Patent Document 1 above.

FIG. 14 is a diagram showing an example of the tentative action curve 52a. The tentative action curve 52b coincides with the y-axis. As an example of the tentative action curve 52a, when the angle formed by the tangent of the curve and the y-axis is θ, starting from the origin, the radius of curvature r of the curve at the contact point is
The curve is shown. If τ ₁ = 1 in the above equation, the curve becomes an involute curve.

In the following, the pseudo-action curve represented by the equation (1) will be compared with the involute curve (τ ₁ = 1). The variables r and r ₀ in the equation (1) are determined so that the temporary end point Ce does not move even if τ is changed. The variable r ₀ is the radius of curvature of the tentative action curve at the tentative start point Cs (θ = 0). When the chain 16 bends, the contacts of the action curves 52a and 52b move on the y-axis from the origin and reach the temporary end point Ce.

FIG. 15 is a diagram showing the shape of the tentative action curve 52a. Near the origin, the larger the variable τ _{1, the} smaller the slope and the smaller the amount of movement of the contact point.

FIG. 16 is a diagram showing the relationship between the angle θ between adjacent elements and the amount of movement of the contact point when the contact surfaces of the pins 42a-1 and 42b-2 are formed by the tentative action curves 52a and 52b. Since the contact point moves on the y-axis, the amount of movement of the contact point is the y-coordinate of the contact point. According to the above-mentioned method of determining the variable r in the equation (1), when the angle θ between adjacent elements becomes the largest (θmax), the contact point is located at the temporary end point Ce. The larger the variable τ _{1, the} smaller the rate of increase of the movement amount y of the contact point when the angle θ between adjacent elements is small, and the larger the rate of increase when the angle θ is large. In other words, it can be understood that the larger the variable τ _{1, the} smaller the couple that lifts the chain element when the bending of the chain is small, and the larger the couple sharply increases as the bending increases. Further, the curve representing the increase in the amount of movement of the contact point changes smoothly, and is 0 when the angle between adjacent elements θ is 0, and is maximum at the maximum value of θ (θmax).

FIG. 17 shows the displacement d of the chord portion of the chain for the pseudo-action curve 52a in which the variable τ ₁ is different. The horizontal axis is the winding radius of the chain 16 with respect to the pulley 12. When the winding radius is small, the larger the variable τ ₁ , the smaller the displacement d of the chord part, but when the winding radius is large, some reversal is seen. When one pulley (for example, pulley 12) has a small winding radius, the other pulley (for example, pulley 14) has a large winding radius. Therefore, even if the winding radius is small at one end of the range of the possible winding radius, if the winding radius is large at the other end, the effect of partial displacement of the string cannot be expected so much. That is, it is desired that the displacements at both ends are correspondingly small. Although it depends on the range of the winding radius that can be taken, it can be seen that the overall effect is large when τ ₁ = 2.5 to 3.0.

As described above, in the process in which the chain element tries to enter the pulley, when the angle between the adjacent elements is small, the chain element is suppressed from being lifted, and when it becomes large, it is lifted. As a result, the displacement of the chain string portion can be suppressed.

(Modification action curve)
When the distance between the temporary start point Cs and the temporary end point Ce is large, the stress distribution in the link 40 changes significantly. Therefore, a portion having a large stress amplitude is generated in the link 40. From the viewpoint of durability, the stress amplitude is preferably small, and the amount of movement of the contact point is preferably small. In this chain 16, the vibration of the chord portion and the fluctuation of the stress in the link 40 are reduced by modifying the tentative action curve. The start point of the modified action curve is the same as the tentative start point Cs of the tentative action curve, and the end point Cf is closer to the start point Cs than the tentative end point Ce. Since the movement of the contact point is small, the change in the pressure distribution is small and the stress amplitude is small.

The modification action curve 50a is represented by the following equations (2) and (3).

The boundary point between the section represented by the equation (2) and the interval represented by the equation (3) has a tentative contact point movement amount increase rate between the tentative start point Cs and the tentative end point Ce, especially in the tentative relative action curve. The relative action curve is set to be located in a larger range than when it has an involute shape. The angle between adjacent elements corresponding to this boundary point is φ. The modified action curve of the section represented by the equation (2), that is, the section of 0 ≦ θ ≦ φ is the same as the tentative action curve. In the section (φ ≦ θ) represented by the equation (3), the rate of increase in the amount of movement of the contact point decreases as the angle between adjacent elements θ increases. As a result, in the range of 0 ≦ θ ≦ φ, the lifting of the chain is suppressed when the angle between adjacent elements θ is small, and the chain is lifted after it becomes large. Further, in the range of φ ≦ θ, the contact point movement amount y when the modification action curve is adopted is smaller than that in the case of the tentative action curve.

FIG. 18 is a diagram showing the relationship between the angle between adjacent elements θ and the amount of movement of the contact point. The curve S1 has an action curve of an involute curve (τ ₁ = 1), the curve S2 has an action curve of equation (1) and τ ₁ = 2.5, and the curve S4 has an action curve of equation (2). ), And shows the case of τ ₁ = 2.5 and τ ₂ = 1. In the curve S4, the contact point when the angle θ between adjacent elements is the maximum, that is, the winding radius of the chain is the minimum, that is, the end point Cf is set to a value smaller than the provisional end point Ce. The curve S3 shows the case of the action curve of the equation (1) when τ ₁ = 2.5 passes through the end point Cf.

The curve S4 coincides with the curve S1 from the start point Cs (θ = 0) until the angle between adjacent elements θ becomes φ (θ = φ), and when it becomes φ or more (θ ≧ φ), the curve S4 separates from the curve S1. The contact point movement amount y becomes smaller than the curve S1.

FIG. 19 is a diagram showing the chord portion displacement d in each case of the curves S1 to S4. A large winding radius, that is, a chain 16 close to a straight line state indicates that the angle θ between adjacent elements is small. Therefore, in FIG. 19, the right end corresponds to the start point Cs, and the left end corresponds to the end point Cf and the provisional end point. Corresponds to Ce. In the case of the curve S1, the string partial displacement is shown by D1, the string partial displacement of the curve S2 is shown by D2, the string partial displacement of the curve S3 is shown by D3, and the string partial displacement of the curve S4 is shown by D4.

The chord partial displacement D3 in the case of the curve S3 is larger than the chord partial displacement D2 in the case of the curve S2 in almost the entire range of the winding radius. That is, it can be seen that the vibration of the chord portion increases only by reducing the temporary end point Ce of the false action curve to the end point Cf in order to suppress the fluctuation of stress. When the modification action curve is adopted, the chord partial displacement is the chord partial displacement D4 corresponding to the curve S4. The chord partial displacement D4 exceeds the chord partial displacement D2 when the tentative action curve is adopted in the very vicinity of the lower limit of the winding radius, but corresponds to this in most ranges. Considering that the winding radius is rarely used near the lower limit, the vibration of the string portion is considered to be equivalent to that of the tentative action curve.

Therefore, by adopting the modified action curve represented by the equations (2) and (3) as the action curve 50a, it is possible to suppress the stress fluctuation in the link 40 while suppressing the vibration of the string portion.

10 Chain type continuously variable transmission, 12 input pulley, 14 output pulley, 16 chain, 18 input shaft, 20 fixed sheave, 22 moving sheave, 24, 26 substantially conical surface, 28 output shaft, 30 fixed sheave, 32 moving sheave, 34,36 Approximately conical surface, 38a, 38b opening, 40 links, 42a, 42b pins, 44 chain elements, 46 link units, 50a, 50b action curve (modified action curve), 52a, 52b action curve (provisional action curve).

Claims (2)

A chain that is wound and orbits around two pulleys of a continuously variable transmission that have conical surfaces that face each other and have variable distances from each other.
The chain has a link unit in which plate-shaped links having openings are arranged along the circumferential direction of the chain and a plurality of pieces are arranged in the width direction of the chain, and the chains penetrate the openings at both ends of the link. A chain element having at least one of the two pins in contact with the conical surface is connected by passing the pin of one of the adjacent chain elements in the circumferential direction of the chain through the opening of the link of the other element. Formed,
When the chain bends, the contacting pins of adjacent chain elements roll into contact with each other.
When the relative action curve, which is the relative shape of the contact surface between the pins of the adjacent chain elements in the plane orthogonal to the chain width direction, has the angle between the adjacent elements, which is the relative angle between the adjacent chain elements, the pins are attached to each other. The contact point of the is a shape that moves toward the outside of the orbiting chain.
The relative action curve is between the start point, which is the pin contact point when the chain extends linearly, the pin contact point, which is the pin contact point when the chain has the minimum winding radius, and the start point and the end point. It has a certain boundary point, the section from the start point to the boundary point coincides with the tentative relative action curve, and the section from the boundary point to the end point is the contact which is the rate of increase of the movement amount of the contact point with respect to the angle between adjacent elements. The rate of increase in point movement decreases as the angle between adjacent elements increases,
The tentative relative action curve consists of a tentative start point that coincides with the start point of the relative action curve and a tentative end point that is in the range of 0.35 to 0.7 times the pin dimension from the tentative start point to the outside in the chain thickness direction in the chain thickness direction. And, the tentative start point and the tentative end point coincide with the tentative start point and the tentative end point when the tentative relative action curve has an involute shape, and further, the tentative relative action curve has a tentative contact point movement amount increase rate. When the angle between adjacent elements is small, it is smaller than when the relative action curve is involute, and when it is large, it is larger.
The boundary point of the relative action curve is located in a range in which the contact point movement amount increase rate is larger than that in the case where the false relative action curve has an involute shape.
Chain of continuously variable transmission. The chain of the continuously variable transmission according to claim 1.
When the angle between adjacent elements is θ and the angle between adjacent elements at the boundary point of the relative action curve is φ, the radius of curvature r of any point on the relative action curve is
A chain of continuously variable transmissions represented by.