JP2006322583A - Belt-type continuously variable transmission and method for regulating pressure exerted on belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain contact area as desired between a pulley and a CVT belt by inhibiting occurrence of a phenomenon in which the CVT belt is arched outward. <P>SOLUTION: The CVT belt 5 is passed between a driving pulley 1 and a driven pulley 3. When the belt is being run, a roller 19 is pressed by a hydraulic cylinder 23 to the CVT belt 5 in the part running from the pulley 1 to the pulley 3 thereby to inhibit occurrence of the arching phenomenon in which the CVT belt 5 is displaced in the above stated part so as to bulge out. The press force exerted by the roller 19 on the CVT belt 5 is changed in response to a transmission gear ratio, engine load (input torque), and input revolutions. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a belt-type continuously variable transmission device including a CVT belt wound between a pair of pulleys and a belt pressure adjusting method thereof.

  As a belt-type continuously variable transmission, a plurality of plate-like elements are laminated in the thickness direction to form a ring, and the ring-shaped element is held and assembled by a ring member to form a CVT belt. Some are configured by winding them between pulleys.

  At this time, the pair of pulleys can move in a direction in which the side plates approach and separate from each other so that the groove width can be changed steplessly. By changing the groove width, the winding radius of each pulley of the CVT belt changes As a result, the rotational speed ratio between the driving side and the driven side, that is, the gear ratio changes continuously and continuously.

In addition, as a belt-type continuously variable transmission, there exist some which were described in the following patent documents 1, 2, for example.
JP-A-5-106700 JP 7-103299 A

  By the way, in such a belt-type continuously variable transmission, the CVT belt of the part which moves toward the other driven pulley by the rotation of one driving pulley among the pair of pulleys is orthogonal to the axial direction of the pulley. The so-called bowing phenomenon occurs by displacing in the direction and bulging outward of the belt.

  This is because a large number of stacked elements transmit torque at the belt winding portion, and the component force of the force that the element on the rear side in the movement direction presses the element on the front side is directed outward in the radial direction.

  As a result, the contact area between the pulley and the CVT belt decreases, and there is a problem that slippage occurs between the pulley and the CVT belt, resulting in a decrease in transmission torque.

  Accordingly, an object of the present invention is to maintain a desired contact area between the pulley and the CVT belt by suppressing the bowing phenomenon of the CVT belt.

  In the present invention, a plurality of plate-like elements are laminated in the plate thickness direction to form an annular shape, and the CVT belt, which is formed by holding the annular shape and held by a ring member, is wound between a pair of pulleys. In the belt-type continuously variable transmission, in a direction intersecting the axial direction of the pulley with respect to the CVT belt of the portion of the pair of pulleys that moves toward the other driven pulley by rotation on one driving side, and The most important feature is that a pressing means for pressing the belt toward the inside of the belt against displacement in the belt outer direction is provided.

  According to the present invention, the portion of the CVT belt that moves from the driving pulley toward the driven pulley is pressed toward the inside of the belt in a direction orthogonal to the axial direction of the pulley and against displacement in the belt outward direction. Since the pressing means is provided, it is possible to prevent the bowing phenomenon that the CVT belt is displaced to the outside of the belt, and as a result, the contact area between the pulley and the CVT belt is maintained as desired to prevent slippage between them and the transmission torque is reduced. Can be prevented.

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

  FIG. 1 is an overall configuration diagram showing an outline of a belt-type continuously variable transmission according to an embodiment of the present invention. This belt-type continuously variable transmission includes a driving pulley 1 and a driven pulley 3 constituting a pair of pulleys, and a CVT belt 5 is wound between the pulleys 1 and 3.

  Each of the pulleys 1 and 3 described above can be moved in a direction in which the side plates approach and separate from each other (a direction perpendicular to the paper surface in FIG. 1) so that the groove width can be changed steplessly. The winding radii of the CVT belt 5 around the pulleys 1 and 3 change, whereby the rotation speed ratio between the driving side and the driven side, that is, the gear ratio changes continuously and continuously.

  As shown in detail in FIG. 2, the CVT belt 5 is formed in an annular shape by laminating a plurality of plate-like elements 7 in the plate thickness direction. As shown in FIG. 3 corresponding to the AA arrow view of FIG. 2, the element 7 has a shape in which a head portion 9 on the outer peripheral side and a shoulder portion 11 on the inner peripheral side are connected by a neck portion 13. A ring insertion groove 15 is formed between the head portion 9 and the shoulder portion 11 on both sides of 13.

  As shown in FIG. 4, a band-shaped ring 17 as a ring member is fitted into an annular groove constituted by each ring insertion groove 15 in a state in which a plurality of the elements 7 are stacked, and thereby a plurality of annularly formed elements are formed. The element 7 and the ring 17 are integrated to form the CVT belt 5. 4 shows a state in which the ring 17 is inserted only into the ring insertion groove 15 on the lower side in the drawing, and the insertion of the ring 17 into the ring insertion groove 15 on the upper side is omitted.

  Here, as shown in FIG. 2, the element 7 is provided with a convex portion 9a on the front surface of the head 9 on the front side in the rotational movement direction indicated by the arrow F, and on the back surface on the opposite side, the convex portion 9a is provided. A recess 9b (FIG. 3) into which the portion 9a enters is provided.

  As shown in FIG. 1, the upper side of the CVT belt 5 in FIG. 1, that is, one of the pair of pulleys 1, 3 rotates by one of the driving pulleys 1, and the other of the driven pulleys 3. For the CVT belt 5 that moves toward the belt, the inner side of the belt against displacement in the direction crossing the axial direction of the pulleys 1 and 3 (direction perpendicular to the paper surface in FIG. 1) and in the belt outer direction. A roller 19 is provided as a pressing means for pressing toward the head.

  The roller 19 is rotatably supported by a rotation support shaft 21 extending in a direction orthogonal to the paper surface in FIG. 1, and the rotation support shaft 21 has a piston extending downward from a piston 25 in the hydraulic cylinder 23 at both ends in the axial direction. The rod 27 is connected to the lower end branched into two branches.

  The hydraulic oil is supplied from the oil pump 31 through the pressure regulating valve 33 to the upper hydraulic oil chamber 29 of the hydraulic cylinder 23 in FIG. The pressure regulating valve 33 accommodates a valve body 37 in a cylindrical housing 35 so as to be movable in the left-right direction in FIG. 1, and the valve body 37 is formed in the housing 35 on the left side in FIG. The spring 41 in the chamber 39 is pressed rightward in FIG.

  The first chamber 39 communicates with the oil pump 31 via the oil inlet passage 43, and the oil inlet passage 43 is provided with a solenoid valve 45 that adjusts the hydraulic pressure acting on the first chamber 39. An inlet branch passage 49 branched from the oil inlet passage 43 is connected to the second chamber 47 formed on the right side of the first chamber 39 in FIG.

  Further, the third chamber 51 formed on the right side of the second chamber 47 in FIG. 1 and the hydraulic oil chamber 29 of the hydraulic cylinder 23 communicate with each other through an oil outlet passage 53. The oil outlet passage 53 and the above-described second chamber 47 communicate with each other through an outlet branch passage 55.

  A drain passage 59 is connected to the drain chamber 57 between the first chamber 39 and the second chamber 47.

  The solenoid valve 45 is energized and controlled by an automatic transmission control unit (ATCU) 61 that controls the belt type continuously variable transmission. The ATCU 61 receives signals of a gear ratio, an engine load (input torque to the driving pulley 1), and an input rotational speed to the driving pulley 1, and controls the solenoid valve 45 based on these input values.

  Next, the operation will be described. The driving pulley 1 is rotated by a driving force of an engine (not shown), and the CVT belt 5 transmits the rotational force to the driven pulley 3 to rotate the driven pulley 3 to rotate the axle (not shown).

  By the way, in the CVT belt 5 in such an operation process, the frictional force between the driven pulley 3 and the element 7 is, as shown in FIG. 4, a pulley sheep due to the oil pressure P1 pushing the driven pulley 3 in the axial direction. It is determined by the element pressing force N1 when the angle is α1, the contact area between the element 7 and the driven pulley 3, and the contact radius r1.

  Similarly, the frictional force between the driving pulley 1 and the element 7 is the ring tension T when the oil pressure P2 pushing the driving pulley 1 in the axial direction becomes α2 as the pulley sheep angle. T is the pressing force N2 between the driving pulley 1 and the element 7 when the pulley sheep angle is α2, and is determined by the pressing force N2, the contact area between the element 7 and the driving pulley 1, and the contact radius r2. Is done.

  For this reason, when the transmission gear ratio is low as shown in FIG. 1, the winding radius of the CVT belt 5 is smaller than that of the driven pulley 3, and the contact area with the element 7 and the contact radius are small. An allowable transmission torque of 5 is determined.

  As shown in FIG. 2, the CVT belt 5 is formed by laminating a large number of elements 7. Therefore, as the transmission torque increases, as shown in FIG. On the other hand, the component force M acting on the outer side in the pulley radial direction (the component force of the force P that the element on the rear side in the movement direction pushes the element on the front side and the reaction force Q of the push force P) increases.

  FIG. 5B is an enlarged view of a portion B in FIG.

  Therefore, as shown in FIG. 6, the CVT belt 5 swells outward in the pulley radial direction as the pulley exits in the state of being wound around the driving pulley 1, and the winding radius gradually increases. Further, in the linear portion of the CVT belt 5 during the movement from the driving pulley 1 to the driven pulley 3, a buckling force is exerted by pressing the element on the front side in the moving direction against the element on the rear side.

  Due to these factors, the CVT belt 5 during the movement from the driving pulley 1 to the driven pulley 3 has two points in FIG. It becomes a bowed state as shown by the chain line. As a result, the contact angle corresponding to the circumferential length at which the driving pulley 1 and the CVT belt 5 contact each other is shortened by the angle Δθ from the contact angle θ2 when not displaced, resulting in a decrease in transmission torque.

  6, the hatched portion is the contact range between the CVT belt 5 and the pulleys 1 and 3 at this time. In the range L of the driving pulley 1, the CVT belt 5 is radially outward of the driving pulley 1. However, the side plates on both sides in the axial direction of the driving pulley 1 are not rigidly fixed to the rotation support shaft, and the parallel state between the side plates is broken. The pulley 1 and the CVT belt 5 are in contact with each other.

  In order to suppress the bowing phenomenon of the CVT belt 5 as described above, as shown in FIG. 1, the roller 19 is used and the CVT belt 5 is directed inward of the belt while moving from the driving pulley 1 to the driven pulley 3. And press.

  7A shows a state in which no pressing force is applied to the CVT belt 5 by the roller 19, and FIG. 7B shows a state in which the pressing force is applied to the CVT belt 5 by the roller 19. Show.

  In FIG. 7A, the command voltage to the solenoid valve 45 by the ATCU 61 is zero, and the hydraulic pressure applied to the first chamber 39 in the pressure regulating valve 33 is about the same as the atmospheric pressure. Low pressure hydraulic pressure acts on the third chamber 51 from the oil pump 31 through the second chamber 47 so as to be pressed to the right only by the elastic force and to be balanced with the elastic force, and this hydraulic pressure is applied to the hydraulic oil chamber of the hydraulic cylinder 23. The roller 19 does not press the CVT belt 5 at this time.

  On the other hand, in FIG. 7B, when there is a command voltage to the solenoid valve 45 by the ATCU 61, the oil pressure acting on the first chamber 39 exceeds the atmospheric pressure, and the force obtained by adding this oil pressure and the elastic force of the spring 41 is In order to balance, a higher hydraulic pressure acts on the third chamber 51 from the oil pump 31 through the second chamber 47 than in FIG. 7A, and this higher hydraulic pressure acts on the hydraulic oil chamber 29 of the hydraulic cylinder 23 and the roller 19. Is pressed against the CVT belt 5.

  At this time, in response to a command from the ATCU 61 to the solenoid valve 45, it acts on the hydraulic oil chamber 29 of the hydraulic cylinder 23 as shown in FIG. 8 according to the gear ratio, engine load (input torque), and input rotational speed. Control hydraulic pressure. That is, as the gear ratio (output / input), engine load (input torque), and input rotational speed all increase, the bowing phenomenon becomes more prominent. Therefore, the hydraulic pressure is set higher as these values increase, and the CVT belt Increase the pressing force against 5.

  This prevents the bowing phenomenon as shown in FIG. 6 of the CVT belt 5 that occurs according to the gear ratio, engine load (input torque), and input rotational speed. As a result, the contact angle corresponding to the circumferential length of contact between the drive pulley 1 and the CVT belt 5 is θ2 as shown in FIG. 1 and compared with the contact angle (θ2−Δθ) shown in FIG. The contact area can be maintained as desired to prevent slippage between the driving pulley 1 and the CVT belt 5 and to prevent a reduction in transmission torque.

  In the driven pulley 3 as well, the contact angle corresponding to the circumferential length in contact with the CVT belt 5 is θ1 as shown in FIG. 1 and is larger than the contact angle shown in FIG.

  In this case, in order to suppress the bowing phenomenon, it is not necessary to increase the oil pressure for pushing the pulleys 1 and 3 in the axial direction, and therefore, excessive stress generated in the ring 17 when the oil pressure is increased is prevented. A decrease in durability of the ring 17 can be prevented. Further, when the oil pressure is increased, the friction of an oil pump (not shown) set in the driving pulley 1 is increased and fuel consumption is deteriorated. However, when the CVT belt 5 is pressed by the roller 19 described above, It is not necessary to increase the pressure, and therefore deterioration of fuel consumption can be prevented.

  9 shows the slip ratio between the driving pulley 1 and the CVT belt 5 with respect to the input torque (1−the rotational speed of the driven pulley 5 when the input torque is applied / the rotational speed of the driven pulley 5 when the input torque is zero. ) In comparison with the present embodiment and the prior art. According to this, it can be seen that the permissible torque at the permissible slip ratio S is improved by H in the above-described embodiment as compared with the prior art.

1 is an overall configuration diagram showing an outline of a belt-type continuously variable transmission according to an embodiment of the present invention. It is the schematic which shows the detail of the CVT belt used for the belt-type continuously variable transmission of FIG. FIG. 3 is an AA arrow view of FIG. 2 showing elements that are components of the CVT belt of FIG. 2. FIG. 3 is a partially omitted plan view showing a state in which the CVT belt of FIG. 2 is wound around a pair of pulleys. It is operation | movement explanatory drawing which shows the force which acts on the pulley radial direction to the element in the winding part to the pulley of the CVT belt of FIG. It is explanatory drawing which shows the state in which the bowing phenomenon generate | occur | produced in the CVT belt. (A) is an operation explanatory view of the hydraulic system showing a state in which no pressing force is applied to the CVT belt by a roller, and (b) is a state in which a pressing force is applied to the CVT belt by a roller. FIG. 2 is a correlation diagram of hydraulic pressure supplied to the hydraulic cylinder of FIG. 1, gear ratio, engine load (input torque), and input rotation speed. It is explanatory drawing which shows the slip ratio between the drive side pulley and CVT belt with respect to input torque by comparing this embodiment with the conventional one.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Drive side pulley 3 Driven side pulley 5 CVT belt 7 Element 17 Ring (ring member)
19 Roller (Pressing means)

Claims (4)

  A belt-type continuously variable transmission in which a plurality of plate-like elements are laminated in the plate thickness direction to form an annular shape, and the annularly formed CVT belt is held by a ring member and wound between a pair of pulleys. In the apparatus, with respect to the portion of the CVT belt that moves toward the other driven pulley by the rotation of one driving side of the pair of pulleys, in the direction intersecting the axial direction of the pulley and toward the belt outer side. A belt-type continuously variable transmission comprising a pressing means for pressing the belt toward the inside of the belt against the displacement of the belt.   The pressing means changes the pressing force according to at least one of a gear ratio, an input torque to the driving pulley, and an input rotational speed to the driving pulley. Belt-type continuously variable transmission.   The belt-type continuously variable transmission according to claim 1 or 2, wherein the pressing means is operated by a hydraulic cylinder.   A belt-type continuously variable transmission in which a plurality of plate-like elements are laminated in the plate thickness direction to form an annular shape, and the annularly formed CVT belt is held by a ring member and wound between a pair of pulleys. In the belt pressure adjusting method of the apparatus, a portion of the pair of pulleys that moves toward the other driven pulley by the rotation of one driving side is pressed against the pulley in the axial direction by the pressing means. A belt pressure adjusting method for a belt-type continuously variable transmission, characterized in that the belt-type continuously variable transmission is pressed toward the inside of the belt against the displacement in the crossing direction and the belt outside direction.

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