JP5532788B2 - Power transmission device - Google Patents

Description

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

  As a continuously variable transmission (power transmission device) 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), and a fixed sheave ( 3b) and a driven pulley (3) provided on the drive wheel side having a movable sheave (3a) and an endless power transmission chain (1) bridged between the two, and a movable sheave ( 2b) (3a) is moved to and away from the fixed sheave (2a) (3b) to clamp the chain (1) with hydraulic pressure, and this clamping force causes the pulley (2) (3) and the chain (1) It is known that a contact load is generated between the contact portion and the torque is transmitted by the frictional force of the contact portion.

  In such a power transmission device, in general, the sheave surface angle is set to 11 °, for example, and this angle is set over the entire region of the sheave surface. On the other hand, Patent Document 1 proposes a two-stage sheave surface angle.

JP 2002-70966 A

  In this type of power transmission device, the gear ratio changes as the winding transmission member (power transmission chain or belt) moves radially outward or radially inward along the sheave surface of the pulley. Yes. In the process of shifting, the winding transmission member sometimes shifts from a state in which it receives a load to a state in which the load is loosened. At this time, the winding transmission member moves beyond a set maximum diameter, and in some cases, disengages from the pulley. Since there is a possibility, the pulley diameter (the maximum diameter of the sheave surface) is set larger by a predetermined amount than the maximum diameter corresponding to the maximum or minimum speed ratio. This predetermined amount (margin) is preferably small in order to reduce the size of the power transmission device, but it is difficult to reduce it from the viewpoint of ensuring safety, and the winding transmission member is a pulley. Therefore, it is desired to surely prevent it from coming off.

  The objective of this invention is providing the power transmission device which can prevent reliably that a winding transmission member remove | deviates from a pulley.

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 a winding spanned around the first and second pulleys. A power transmission device, wherein the inclination angle of the sheave surface of the pulley is equal to the inclination angle of both surfaces of the winding transmission member in contact with the sheave surface in a normal use range . the outer diameter end portion of the first and second pulleys, and the stop surface exits with an inclination angle nearly perpendicular is formed than the inclination angle of the sheave surfaces in it than the inner diameter side, the winding can belt-driven member and the sheave The coefficient of friction with the surface is μ, 0.08 <μ <0.12, and the inclination angle θ of the retaining surface is set in the range of 0 <θ <4.6 °. It is what.

  The power transmission device may be a chain type (the winding transmission member is a chain), and may be a belt type (the winding transmission member is a belt).

  Preferably, the winding transmission member is arranged in the chain width direction so that the plurality of links having front and rear insertion portions through which the pins are inserted, and the front insertion portion of one link and the rear insertion portion of the other link correspond to each other. A plurality of first pins and a plurality of second pins arranged before and after connecting the links are provided, and the first pins and the second pins are relatively in rolling contact with each other so that the links can be bent in the length direction. Power transmission chain. In such a 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.

  The inclination angle of the sheave surface of the pulley is suitably 8 to 13 °, and is usually 11 °. Correspondingly, both surfaces of the winding transmission member (end surfaces of the pins in the power transmission chain) are also formed to have an inclination angle of 11 °. In the conventional power transmission device, the inclination angle of the sheave surface of the pulley is the same (11 °) over the entire region. However, in the power transmission device according to the present invention, the pulley outside the pulley that is not used in the normal use range is used. An area where the inclination angle of the sheave surface of the pulley is small is provided as a retaining surface for preventing the winding transmission member from coming off the pulley at the radial end, thereby preventing the winding transmission member from coming off. It has been done.

θ <tan ⁻¹ (μ) is a condition for preventing the winding transmission member from moving radially outward by the frictional force acting on the winding transmission member from the sheave surface of the pulley. Since the friction coefficient μ between the member and the pulley is 0.08 to 0.12, if this is used, θ <4.6 ° may be satisfied. The sheave surface of the pulley may be vertical (inclination angle θ = 0 °), and the lower limit value of θ is 0 °.

The inclination angle of the retaining surface is set regardless of the inclination angle of the sheave surface. When the use area of the normal sheave surface is, for example, 12 ° and 10 °, it is radially outside. A retaining surface with θ <tan ⁻¹ (μ) as the third step is formed on the side step.

  Although the length of the retaining surface is not particularly limited, it may be about 1 mm. Therefore, compared with the conventional one, the dimension of the margin part (the part larger than the maximum diameter of the sheave surface in the normal use region) is reduced. can do. Therefore, the pulley can be reduced in size, or the speed ratio can be increased by setting the pulleys to the same size.

  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. For example, the first pin and the second pin are formed as involute curved surfaces in which either one of the contact surfaces is a flat surface and the other contact surface is relatively rollable and movable.

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

  In such a continuously variable transmission, 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. By sandwiching the chain between them and moving the movable sheave by the hydraulic actuator, the distance between sheave surfaces of the continuously variable transmission, that is, the winding radius of the chain is changed.

  According to the power transmission device of the present invention, the retaining surfaces having an inclination angle closer to the vertical than the inclination angle of the sheave surface on the inner diameter side are formed at the outer diameter side ends of the first and second pulleys. Therefore, it is possible to reliably prevent the winding transmission member from coming off the pulley.

FIG. 1 is a plan view showing a part of a power transmission chain used in a power transmission device according to the present invention. FIG. 2 is an enlarged side view of the link of the power transmission chain. FIG. 3 is a front sectional view showing an embodiment of the power transmission device according to the present invention. FIG. 4 is an enlarged front sectional view showing a main part of the power transmission device according to the present invention. FIG. 5 is a diagram for explaining conditions for preventing the winding member from coming off. FIG. 6 is a perspective view showing a conventional power transmission device.

  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.

  FIG. 1 shows a part of a power transmission chain according to the present invention. The power transmission chain (1) has front and rear insertion portions (12) and (13) provided at predetermined intervals in the chain length direction. A plurality of links (11) (21) and a plurality of pins (first pins) (14) and interpieces (first ones) linking the links (11) (21) arranged in the chain width direction so as to be bendable in the length direction 2 pins) (15). The interpiece (15) is made shorter than the pin (14), and both are opposed to each other with the interpiece (15) disposed on the front side and the pin (14) disposed 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. In this embodiment, one link unit includes a link row having nine links and two link rows having eight links.

  In the power transmission chain (1) of the present invention, two types of links (11) and (21) are used: a short link (11) and a long link (21). In the short link (11) and the long link (21), the distance between the lines (points in the cross section) where the pin (14) and the interpiece (15) are in contact in the straight region of the chain (1) (FIG. 2) The distance between the point indicated by symbol A and the point indicated by B) = “pitch length” is different.

  As shown in FIG. 2, the front insertion portion (12) of the short link (11) (the same applies to the long link (12)) includes a pin movable portion (16) and an interpiece to which the pin (14) is movably fitted. It consists of an interpiece fixing part (17) to which (15) is fixed, and the rear insertion part (13) is fitted so that the pin fixing part (18) to which the pin (14) is fixed and the interpiece (15) can be moved. It consists of interpiece movable parts (19) to be matched.

  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).

  When connecting the links (11) (21) arranged in the chain width direction, the front insertion part (12) of one link (11) (21) and the rear insertion part (13) of the other links (11) (21) ) And the links (11) and (21) are overlapped so that the pin (14) is fixed to the rear insertion part (13) of one link (11) (21) and the other link (11) (21) is movably fitted to the front insertion part (12), and the interpiece (15) is movably fitted to the rear insertion part (13) of one link (11) (21) and the other It is fixed to the front insertion part (12) of the links (11) (21). Then, the pin (14) and the interpiece (15) are relatively rolled and brought into contact with each other, whereby the links (11) and (21) can be bent in the length direction (front-rear direction).

  At the boundary between the pin fixing part (18) of the link (11) (21) and the interpiece movable part (19), the upper and lower concave arcuate guide parts (19a) (19b) of the interpiece movable part (19) Are provided with upper and lower convex arc-shaped holding portions (18a) and (18b) for holding the pin (14) fixed to the pin fixing portion (18). 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) Is an involute curve having a base circle of radius Rb and center M in the cross section, 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) (21) moves from the straight region to the curved region of the chain (1) or from the curved region to the straight region, the pin (14) is fixed at the front insertion portion (12). The rolling contact surface (14a) is in contact with the rolling contact surface (15c) of the interpiece (15) while the rolling contact surface (15a) is in contact (including some sliding contact) with respect to the interpiece (15) in the state. In the rear insertion portion (13), the rolling contact surface (15c) is connected to the pin (14) with respect to the pin (14) in a state where the interpiece (15) is fixed in the interpiece movable portion (19). It moves while rolling (including some sliding contact) on the rolling contact surface (14a).

  FIG. 3 shows a power transmission device according to the present invention, in which the power transmission chain (1) is attached to the V-type pulley type CVT shown in FIG. In the power transmission device, as shown in FIG. 3, an interpiece is provided on each of the conical sheave surfaces (2c) and (2d) of the fixed sheave (2a) of the pulley (2) having the pulley shaft (2e) and the movable sheave (2b). In a state where the end surface of (15) is not in contact, the end surface of the drive pin (14) contacts the conical sheave surface (2c) (2d) of the pulley (2), and power is transmitted by the frictional force caused by this contact.

  When the movable sheave (2b) of the drive pulley (2) at the position indicated by the solid line in FIG. 3 is moved toward and away from the fixed sheave (2a), the winding diameter of the drive pulley (2) is as shown in FIG. As indicated by the chain line, it is large when approaching and small when separated. In the driven pulley (3), although not shown in the drawing, 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 When the winding diameter of (3) decreases and the winding diameter of the drive pulley (2) decreases, the winding diameter of the driven pulley (3) increases. As a result, U / D (underdrive) in which the drive pulley (2) has the smallest winding diameter and the driven pulley (3) has the largest winding diameter, based on the state where the transmission ratio is 1: 1. A state is obtained, and an O / D (overdrive) state in which the winding diameter of the drive pulley (2) is maximum and the winding diameter of the driven pulley (3) is minimum is obtained.

  3 and FIG. 4, which is an enlarged view of the main part, the region indicated by reference numeral (2f) is not normally used at the outer diameter side end of each pulley (2) (3) (only one shown). This region (2f) is a chain retaining surface having an inclination angle closer to the vertical than the inclination angle of the sheave surfaces (2c) (2d) located on the inner diameter side thereof.

The inclination angle of the chain retaining surface (2f) is θ <tan ⁻¹ (μ), where μ is the coefficient of friction between the power transmission chain (1) and the sheave surface (2c) (2d) (2f). ing.

FIG. 5 shows the relationship of the force when obtaining the condition of θ <tan ⁻¹ (μ). In FIG. 5, the power transmission chain receives the vertical drag N from the sheave surface (S) of the pulley. When the friction coefficient between the power transmission chain and the pulley is μ, a frictional force μN acts on the power transmission chain from the sheave surface (S). Since α shown in FIG. 5 has a relationship of tan α = μN / N = μ, α = tan ⁻¹ (μ) is satisfied. On the other hand, if the force that the pulley pushes the power transmission chain in the chain width direction (left and right in the figure) is AF, and the force that the pulley pushes the power transmission chain radially outward (upward in the figure) is Fr, When the angle of the sheave surface (S) is θ, Fr / AF = tan (θ−α) is established. Here, if AF> 0 and Fr is related to Fr ≧ 0, the power transmission chain can move radially outward along the sheave surface (S), and if Fr <0, power transmission is possible. The chain cannot move radially outward. Therefore, tan (θ−α) <0, that is, θ−α <0 is a condition for preventing the chain from being lost, and α = tan ⁻¹ (μ) is used, and θ <tan ⁻¹ (μ) is It becomes a condition. μ is a predetermined value depending on the material and contact area of the power transmission chain and pulley, and is usually μ = 0.08 to 0.12. When this value is used, it is possible to reliably prevent the power transmission chain from coming off if θ <4.6 in consideration of some variation.

  Thus, according to the power transmission device of the present invention, since the chain retaining surface (2f) is formed at the outer diameter side end of the pulley, the power transmission chain (1) further moves radially outward. It is prevented. Therefore, for example, the power transmission chain (1) is prevented from interfering with the housing cover, and the pin (14) is prevented from protruding from the pulley and the end surface of the pin (14) is prevented from being prematurely worn by local contact. . In addition, a fail-safe function is provided for such an event that the power transmission chain (1) is disengaged from the pulley and the vehicle cannot start or cannot shift due to the inability to transmit torque.

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

  In the above power transmission chain (1), polygonal vibration occurs due to repeated vertical movement of the pin, which causes noise, but the drive pin (14) and the interpiece (15) are relatively in rolling contact. Because the locus of the contact position between the drive pin (14) and the interpiece (15) with respect to the drive pin (14) is an involute of a circle, both the contact surfaces of the drive pin and the interpiece are Compared with the case of a circular arc surface, vibration can be reduced and noise can be reduced.

  When used in the CVT, the drive pin (14) and the interpiece (15) are guided by the movable parts (16) and (19) as described above to move in rolling contact. ), The drive pin (14) hardly rotates with respect to the sheave surfaces (2c) and (2d), the friction loss is reduced, and a high power transmission rate is secured.

The relationship shown in FIG. 5 is also established by a belt instead of a chain. Even in a belt-type power transmission device (continuously variable transmission) in which the winding transmission member is a belt, θ <tan ⁻¹ (μ) By providing the retaining surface of the belt, it is possible to prevent the belt from coming off the pulley.

(1) Power transmission chain (wound transmission member)
(2) (3) Pulley
(2a) (3b) Fixed sheave
(2b) (3a) Movable sheave
(2c) (2d) Conical sheave surface
(2f) Chain retaining surface

Claims (2)

A first pulley having a conical sheave surface, a second pulley having a conical sheave surface, and a winding transmission member spanned between the first and second pulleys. In the power transmission device formed so that the inclination angle of the sheave surface is equal to the inclination angle of both surfaces of the winding transmission member in contact with the sheave surface in a normal use range ,
The outer diameter end portion of the first and second pulleys, it from stop surface exit having an inclination angle close to the vertical than the inclination angle of the sheave surfaces on the inner diameter side is formed, a winding can belt-driven member The coefficient of friction with the sheave surface is μ, 0.08 <μ <0.12, and the inclination angle θ of the retaining surface is set in the range of 0 <θ <4.6 °. A power transmission device.   The winding transmission member 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 are provided, and the first pins and the second pins are relatively rolled and brought into contact with each other, whereby the links can be bent in the longitudinal direction. The power transmission device according to claim 1, which is a power transmission chain.

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