JP2011069410A - Power transmission device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power transmission device which enables a gear ratio range to be increased by considering elastic elongation of a winding transmission member. <P>SOLUTION: In the power transmission device, an inequality expression Dp+0.5 mm<Ds<Dp+5 mm is satisfied, where Dp (mm) represents the outer diameter of a primary pulley 2 and Ds (mm) is the outer diameter of a secondary pulley 3. <P>COPYRIGHT: (C)2011,JPO&INPIT

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 primary pulley (2) provided on the engine side having a fixed sheave (2a) and a movable sheave (2b), and a fixed sheave ( 3b) and a secondary 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, normally, the primary pulley and the secondary pulley have the same outer diameter, and the gear ratio is configured to change as the winding diameter changes. Patent Document 1 discloses a method for increasing the gear ratio width, but the diameters of the primary pulley and the secondary pulley are the same as in the conventional art.

JP 2008-248935 A

  In this type of power transmission device, as disclosed in Patent Document 1, it is a problem to increase the gear ratio width. However, in consideration of the gear ratio width, a winding transmission member (power) The elastic elongation of the transmission chain or belt) was not considered.

  An object of the present invention is to provide a power transmission device capable of increasing a gear ratio range by taking into account the elastic elongation of a winding transmission member.

  The power transmission device according to the present invention includes a primary pulley composed of a fixed sheave and a movable sheave each having a conical surface sheave surface, a secondary pulley composed of a fixed sheave and a movable sheave each having a conical surface sheave surface, and between the pulleys. An outer diameter of a primary pulley in a power transmission device including a wound transmission member that is wound around, wherein the winding diameter is changed steplessly in accordance with a change in the distance between sheaves of each pulley and stepless speed change is performed. Is Dp (mm) and the outer diameter of the secondary pulley is Ds (mm), and Dp + 0.5 mm <Ds <Dp + 5 mm is satisfied.

  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).

  In the power transmission device, the underdrive (hereinafter referred to as “U / D”) having the maximum speed ratio corresponding to low speed traveling and the overdrive (hereinafter referred to as “O / D”) corresponding to the minimum speed ratio corresponding to high speed traveling. ").) The gear ratio changes. In the U / D state, the winding diameter on the primary pulley side is the smallest and the winding diameter on the secondary pulley side is the maximum, and in the O / D state, the opposite is true.

  The tension applied to the winding transmission member increases during U / D, and therefore the elongation of the winding transmission member also increases during U / D (1.6 to 1.8 times that during O / D).

  The shaft diameter of the pulley is not changed between the primary side and the secondary side. Accordingly, the primary winding side at the U / D and the secondary side at the O / D, which are the minimum diameter, have the same winding diameter (the same contact point).

  The speed ratio width is defined by (speed ratio at U / D) / (speed ratio at O / D). In order to maximize this speed ratio width, it is necessary to make the maximum use of the pulley outer diameter, including the elastic extension of the winding transmission member, and the elastic extension of the winding transmission member during U / D In view of the fact that it is large, it is preferable to make the outer diameter of the secondary pulley larger than the outer diameter of the primary pulley. The relationship between the difference in diameter α and the gear ratio ratio varies depending on the distance between the shafts and the shaft diameter of the pulley, but is not proportional, and has a curve shape (substantially parabolic) having a peak when α is about 3 mm. . Accordingly, α = 0.5 to 5 mm, that is, the outer diameter of the primary pulley is Dp (mm) and the outer diameter of the secondary pulley is Ds (mm), and Dp + 0.5 mm <Ds <Dp + 5 mm is a practically preferable range. . Dp <Ds means that by increasing Ds, the elastic elongation of the winding transmission member during U / D is easily absorbed on the secondary pulley side where the winding diameter is large. I mean.

  Since the pulleys must not interfere with each other, it is necessary that (Dp + Ds) / 2 <the distance between the pulley axes is satisfied.

  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. 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.

  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.

  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, when the outer diameter of the primary pulley is Dp (mm) and the outer diameter of the secondary pulley is Ds (mm), Dp + 0.5 mm <Ds <Dp + 5 mm is satisfied. Considering the elastic elongation of the member, Ds and Dp that increase the gear ratio range are obtained. Therefore, when used in a continuously variable transmission for an automobile, it can contribute to an improvement in actual vehicle fuel consumption.

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. FIG. 3 is a front sectional view showing an embodiment of the power transmission device according to the present invention. FIG. 4 is a side view schematically showing a main part of the power transmission device according to the present invention. FIG. 5 is a graph showing the relationship between α = (Ds−Dp) and the gear ratio range. 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).

  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).

  In the above power transmission chain (1), polygonal vibration is caused by repeated vertical movement of the pin, which causes noise, but the pin (14) and the interpiece (15) are relatively rolled and moved in contact. In addition, since 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, both the contact surfaces of the pin and the interpiece are arcuate surfaces. Compared to the case, vibration can be reduced and noise can be reduced.

  When used in the CVT, the pin (14) and the interpiece (15) are guided by the movable parts (16) and (19) as described above to move in rolling contact with the pulley (2). The 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.

  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 pin (14) contacts the conical sheave surface (2c) (2d) of the pulley (2), and power is transmitted by the frictional force due to this contact.

  When the movable sheave (2b) of the primary 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 primary pulley (2) is as shown in FIG. As indicated by the chain line, it is large when approaching and small when separated. In the secondary pulley (3), although not shown, when the movable sheave moves in the opposite direction to the movable sheave (2b) of the primary pulley (2) and the winding diameter of the primary pulley (2) increases, the secondary pulley When the winding diameter of (3) decreases and the winding diameter of the primary pulley (2) decreases, the winding diameter of the secondary pulley (3) increases. As a result, a U / D state in which the winding diameter of the primary pulley (2) is minimum and the winding diameter of the secondary pulley (3) is maximum is obtained with reference to the state where the gear ratio is 1: 1. In addition, an O / D state in which the winding diameter of the primary pulley (2) is maximum and the winding diameter of the secondary pulley (3) is minimum is obtained.

  In FIG. 4 schematically showing the main part of the power transmission device according to the present invention, the winding diameter of the primary pulley (2) is Rp, the winding diameter of the secondary pulley (3) is Rs, and the primary pulley (2 ) Is ωp, and the angular velocity of the secondary pulley (3) is ωs, the gear ratio γ is γ = ωp / ωs≈Rs / Rp. The figure shows a state close to U / D, and the winding diameter of the secondary pulley (3) decreases during O / D. (Transmission ratio at U / D) / (Transmission ratio at O / D) is the transmission ratio width. If this gear ratio range is large, the range in which the gear ratio can be selected becomes large, and the range for setting the optimum gear ratio in accordance with the state of the vehicle (required torque / vehicle speed) is widened.

  In the conventional power transmission device, the dimensions are set so that the relationship between U / D and O / D is exactly reversed, and the winding diameter of the primary pulley (2) at U / D = The winding diameter of the secondary pulley (3) at O / D and the winding diameter of the primary pulley (2) at O / D = the winding diameter of the secondary pulley (3) at U / D.

  However, the tension applied to the power transmission chain (1) is different between U / D when a large load for driving is applied and O / D when the load torque is reduced due to high speed running. The tension applied to the chain (1) increases during U / D, and therefore the extension of the power transmission chain (1) also increases during U / D (1.6 to 1.8 times that during O / D).

  FIG. 5 shows the relationship between α = (Ds−Dp) and the gear ratio range when this elongation is taken into account. Here, the shaft diameters of the primary pulley (2) and the secondary pulley (3) are the same.

  As can be seen from FIG. 5, the relationship between the diameter difference α between the primary pulley (2) and the secondary pulley (3) and the gear ratio width is the distance between the shafts and the shafts of the primary pulley (2) and the secondary pulley (3). Although it varies depending on the diameter, it is not in a proportional relationship, and has a curve shape (substantially parabolic) having a peak at about 3 mm. Therefore, α = 0.5 to 5 mm, that is, Dp + 0.5 mm <Ds <Dp + 5 mm, where Dp (mm) is the outer diameter of the primary pulley (2) and Ds (mm) is the outer diameter of the secondary pulley (3). This is a preferable range.

  Since the primary pulley (2) and the secondary pulley (3) must not interfere with each other, (Dp + Ds) / 2 <the distance between the shafts of the primary pulley (2) and the secondary pulley (3) needs to be satisfied. is there.

  The relationship shown in FIG. 5 is established not only by the power transmission chain (1) but also by a belt. Even in a belt-type power transmission device (continuously variable transmission) in which the winding transmission member is a belt, Dp + 0. By setting 5 mm <Ds <Dp + 5 mm, the gear ratio range can be increased.

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

Claims (2)

A primary pulley composed of a fixed sheave and a movable sheave each having a conical surface sheave surface, a secondary pulley composed of a fixed sheave and a movable sheave each having a conical surface sheave surface, and a winding transmission member wound between both pulleys In the power transmission device in which the winding diameter is changed steplessly in accordance with the change in the distance between sheaves of each pulley, and stepless speed change is performed.
The outer diameter of the primary pulley is Dp (mm), the outer diameter of the secondary pulley is Ds (mm),
A power transmission device characterized in that Dp + 0.5 mm <Ds <Dp + 5 mm is satisfied.   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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