JP2020026830A - Continuous variable transmission - Google Patents

Abstract

To provide a continuously variable transmission which can suppress the damage of a case and a lock of a pulley shaft even if a belt is broken by managing a clearance between the case and a pulley.SOLUTION: In a state that a winding diameter of a chain belt 6 of a pulley 3 becomes maximum, that is, in a state that a fixed sheave 8 and a movable sheave 9 most approximate each other, an upper end position 6e of the chain belt 6 at the outside in a radial direction is positioned inside an inside diameter of a first cover part 7a of the pulley 3 in the radial direction. Also, in a state that the upper end position 6e of the chain belt 6 contacts with an inner wall of the first cover part 7a in a state that the fixed sheave 8 and the movable sheave 9 most approximate each other, outside diameters of cone faces 11, 12 are set larger than a diameter of a pin lower end 6g of the chain belt 6.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a continuously variable transmission, and more particularly to a continuously variable transmission that uses a chain belt for power transmission.

  BACKGROUND ART Conventionally, a belt-type continuously variable transmission has been known (for example, see Patent Document 1). The belt-type continuously variable transmission has a belt wound around a primary pulley to which power output from a driving force source is input, a secondary pulley connected to an output side of a driving system of the vehicle, and a pair of pulleys. And a case for covering the belt. The primary pulley and the secondary pulley change the winding radius of the belt in accordance with the width of the groove around which the belt is wound. The gear ratio is increased or decreased by increasing the groove width of one pulley to reduce the winding radius of the belt, and thereby narrowing the groove width of the other pulley to increase the winding radius of the belt. In the belt-type continuously variable transmission described in Patent Document 1, a guide rail is provided on a chord portion where a chain belt advances linearly. The guide rail suppresses an impact sound generated when the chain belt hits the case when the chain belt is broken.

  Further, a belt-type continuously variable transmission in which an impact absorbing portion for suppressing a collision between the chain belt and the case when the chain belt is broken is provided on an inner wall of the case is known (for example, see Patent Document 2). ). The shock absorbing portion is provided on the inner wall of the case on the opposite side of the primary pulley from the secondary pulley.

JP 2017-106530 A JP 2017-96417 A

  The belt of the continuously variable transmission described above receives a load directed outward in the radial direction of the pulley due to the clamping force of the pulley. If a chain belt (hereinafter simply referred to as a “belt”) breaks, the broken belt moves radially outward in a range wound around a pulley. At this time, if the gap between the case and the pulley is smaller than the radial thickness of the belt, the broken belt is pressed against the case. To the belt wound around the pulley, a load directed outward in the radial direction due to the pinching pressure of the pulley and a load directed in the traveling direction by rotating the pulley are added. For this reason, the inner surface of the case is rubbed while the belt is strongly pressed against the case, so that the case may be greatly damaged.

  If the gap between the case and the pulley is equal to the thickness of the belt in the radial direction, the broken belt may be caught between the case and the pulley. In such a case, the pulley shaft may be locked. If the gap between the case and the pulley is made larger than the thickness of the belt, the case becomes larger. Conversely, when the case is made smaller, the outer diameter of the pulley is made smaller, which causes a problem that the speed ratio width of the continuously variable transmission is reduced.

  The present invention has been made in view of the technical problem as described above, and by appropriately managing the gap between the case and the pulley, even if the belt is broken, the case may be damaged or damaged. It is an object of the present invention to provide a continuously variable transmission that can suppress locking of a pulley shaft.

In order to achieve the above object, the present invention provides a primary pulley having a fixed sheave to which torque is transmitted from an input shaft and a movable sheave movable in the axial direction of the input shaft with respect to the fixed sheave; A secondary pulley having a fixed sheave for transmitting torque to a shaft and a movable sheave movable in the axial direction of the output shaft with respect to the fixed sheave; a plurality of links; and a plurality of links for annularly connecting the plurality of links. A pin, and both end faces of the pin in the axial direction of the input shaft contact with the pair of cone faces when the pins are wound around pulley grooves formed by cone faces of the fixed sheave and the movable sheave, respectively. A chain belt, and the fixed sheave and the movable sheave are respectively provided on the primary pulley and the secondary pulley. Is a continuously variable transmission that includes a regulating portion that regulates the primary pulley, the secondary pulley, and the chain belt in the axial direction, and a case that houses the primary pulley, the secondary pulley, and the chain belt. And a cover portion that covers all or a part of a wrapped portion around which the chain belt is wrapped around at least one of the secondary pulleys, on a concentric circle centered on the circumference center of the chain belt at the wrapped portion. The minimum inner diameter of the cover portion in the winding portion is “Dcase”, the outer diameter of the cone surface is “Dpully”, and the upper end position of the chain belt and the belt pitch line in the radial direction of the pulley are defined. The length of the belt is “hbu”, and the belt pitch line is in the closest state. The center position in the radial direction of the pins of the chain belt hanged, the length between the belt pitch line in the radial direction and the lower end position of the pins in the chain belt is "hpl", The length of the pin at the belt pitch line in the axial direction is “Lpl”, the diameter at the center position in the radial direction on the cone surface is “Dm”, and the cone of the restricting portion and the fixed sheave in the axial direction. The length between the surface and the center position is "a", the length between the regulating portion and the center position of the cone surface of the movable sheave in the axial direction is "b", and the input shaft When the angle of the cone surface with respect to a direction perpendicular to the direction is defined as “θ”, the following conditional expressions (1) and (2) are satisfied.
Dcase> Dm + (Lpl− (ab)) / tan θ + 2hbu (1)
Dpully> Dcase-2 (hbu + hpl) (2)

  Equation (1) in the present invention indicates that, in a state where the winding diameter of the chain belt around the pulley is the maximum diameter, that is, in a state where the movable sheave and the fixed sheave are closest to each other, the upper end position of the chain belt in the radial direction is set to Is a formula for positioning the inner side of the inner wall of the cover part in the radial direction. Equation (2) indicates that, when the movable sheave and the fixed sheave are closest to each other, the outer diameter of the chain belt is in contact with the inner wall of the cover, and the outer diameter of the cone surface is smaller than the diameter of the chain belt to the lower end of the pin. This is an equation for setting a large diameter.

  According to the present invention, by satisfying the expressions (1) and (2), even if the belt is broken, the chain belt fits between the inner wall of the cover portion and the outer diameter of the cone surface at the winding portion. There is no intrusion. For this reason, even the broken chain belt can be sent out in the traveling direction by the pressing force between the movable sheave and the fixed sheave. This can prevent the case from being damaged or the pulley shaft from locking.

FIG. 1 is an explanatory diagram showing an example of a belt-type continuously variable transmission to which the present invention is applied. FIG. 2 is a sectional view showing the primary pulley.

  Hereinafter, an example of a continuously variable transmission according to the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing an example of a continuously variable transmission to which the present invention is applied. FIG. 2 is a sectional view showing the primary pulley.

  As shown in FIG. 1, the continuously variable transmission 1 includes an input shaft 2, a primary pulley 3, an output shaft 4, a secondary pulley 5, a chain belt (belt) 6, and a case 7. The input shaft 2 is transmitted with torque from a driving force source (not shown). The primary pulley 3 rotates integrally with the input shaft 2. The output shaft 4 transmits torque to an output member such as a drive shaft (not shown). Secondary pulley 5 rotates integrally with output shaft 4. The belt 6 is wound around the pulley groove 3 a of the primary pulley 3 and the pulley groove 5 a of the secondary pulley 5. The case 7 rotatably supports the input shaft 2 and the output shaft 4 and the like, and houses the primary pulley 3, the secondary pulley 5, the belt 6, and the like. The input shaft 2 and the output shaft 4 are arranged in parallel.

  Specifically, the primary pulley 3 is configured by arranging a fixed sheave 8 and a movable sheave 9 so as to face each other as shown in FIG. The fixed sheave 8 is formed integrally with the input shaft 2. The movable sheave 9 is attached to the input shaft 2 by, for example, a spline 10 so that the movable sheave 9 rotates integrally with the input shaft 2 and can move in the axial direction of the input shaft 2. By making the cone surface 11 of the fixed sheave 8 and the cone surface 12 of the movable sheave 9 oppose each other in the axial direction, a V-shaped pulley groove 3a is formed therebetween. The primary pulley 3 is provided with a hydraulic actuator (not shown) for moving the movable sheave 9 in the axial direction.

  The secondary pulley 5 is configured by disposing a fixed sheave (not shown) and a movable sheave so as to face each other. The fixed sheave is formed integrally with the output shaft 4. The movable sheave is attached to the output shaft 4 by, for example, a spline or the like so as to rotate integrally with the output shaft 4 and move in the axial direction of the output shaft 4. By making the cone surface of the fixed sheave and the cove surface of the movable sheave face each other in the axial direction of the output shaft 4, a V-shaped pulley groove 5a is formed therebetween. The secondary pulley 5 is also provided with a hydraulic actuator (not shown) for pressing the movable sheave in the axial direction. Further, the secondary pulley 5 is provided with a return sprink (not shown) for pressing the movable sheave toward the fixed sheave.

  The belt 6 is configured by connecting a plurality of plate-like links (not shown) in a ring shape by, for example, pins (not shown). The pin is fitted into a connection hole formed in the link to connect the links in a ring shape. Both end surfaces in the axial direction of the pin are surfaces that come into contact with a pair of cone surfaces constituting the pulley grooves 3a and 5a and receive clamping force from both axial sides of the pulley shaft (the input shaft 2 or the output shaft 4).

  The continuously variable transmission 1 transmits torque between the input shaft 2 and the output shaft 4 by a belt 6 wound around a primary pulley 3 and a secondary pulley 5. At the same time, the gear ratio is changed by changing the groove widths of the pulley grooves 3a and 5a, respectively. For example, when the hydraulic actuator of the primary pulley 3 is controlled to change the groove width of the pulley groove 3a, the winding diameter of the belt 6 wound around the pulley groove 3a changes. Thereby, the gear ratio changes. In this case, on the secondary pulley 5 side, since the circumferential length of the belt 6 is constant, the groove width of the pulley groove 5a changes in conjunction with the change of the groove width of the pulley groove 3a. Then, in order to suppress the slip between the belt 6 and the secondary pulley 5, the hydraulic actuator of the secondary pulley 5 is controlled to maintain the belt clamping pressure in the pulley groove 5a at an appropriate level. In FIG. 1, the winding diameter of the belt 6 when the speed ratio is low is indicated by a dotted line, and the winding diameter of the belt 6 when the speed ratio is high is indicated by a solid line.

  More specifically, as shown in FIG. 2, the movable sheave 9 is provided with an abutment portion 13 at an inner peripheral portion where the input shaft 2 is inserted. The abutting portion 13 contacts the abutted portion 14 provided on the fixed sheave 8 when the winding diameter of the belt 6 is maximized, that is, when the movable sheave 9 and the fixed sheave 8 are closest to each other. Abut to prevent further access. The contact portion 13 and the contacted portion 14 are examples of a restricting portion in the embodiment of the present invention.

  The continuously variable transmission 1 is suitable for a vehicle mounted on an FF vehicle (front engine / front drive vehicle). For example, when the continuously variable transmission 1 is mounted on an FF vehicle, the input shaft 2 and the output shaft 4 are arranged parallel to the vehicle width direction. That is, the primary pulley 3 and the secondary pulley 5 shown in FIG. 1 are arranged in the front-rear direction of the vehicle. For this reason, in order to achieve compactness in the front-rear direction of the vehicle, the case 7 is referred to as the primary pulley 3 and the secondary pulley 5 (hereinafter, simply referred to as “pulleys 3 and 5” unless it is particularly necessary to distinguish them. Must be placed close to

  In the example shown in FIG. 1, the case 7 includes a first cover 7a and a second cover 7b. The first cover portion 7a covers a part or the entirety of the first winding portion 6a in a range where the belt 6 is in contact (pressed) with the pulley groove 3a. Specifically, the first cover portion 7a is arranged on a concentric circle centered on the circumferential center of the belt 6 in the first winding portion 6a, and is a portion closest to the belt 6. Further, the second cover portion 7b covers a part or the entirety of the second winding portion 6b in a range where the belt 6 comes into contact with (presses against) the pulley groove 5a. The second cover portion 7b is arranged on a concentric circle centered on the circumferential center of the belt 6 in the second winding portion 6b, and is a portion closest to the belt 6.

  Specifically, the position at which the belt 6 enters and leaves the primary pulley 3 changes according to the speed ratio set by the continuously variable transmission 1. For example, the entry position of the belt 6 with respect to the primary pulley 3 is the position P1 when the speed ratio is maximized, and is the position P2 when the speed ratio is minimized. The entry position of the belt 6 with respect to the secondary pulley 5 is the position P3 when the gear ratio is maximized, and is the position P4 when the gear ratio is minimized. The disengagement position of the belt 6 with respect to the primary pulley 3 is a position P5 when the gear ratio is maximized, and is a position P6 when the gear ratio is minimized. The disengagement position of the belt 6 with respect to the secondary pulley 5 is the position P7 when the speed ratio is maximized, and is the position P8 when the speed ratio is minimized.

  In the state where the gear ratio is “1”, the entry position of the belt 6 with respect to the primary pulley 3 is at the position P9, and the entry position of the belt 6 with respect to the secondary pulley 5 is at the position P10. In this case, the separation position of the belt 6 with respect to the primary pulley 3 is at the position P11, and the separation position of the belt 6 with respect to the secondary pulley 5 is at the position P12. That is, the entry position and the separation position of the belt 6 change according to the gear ratio.

  The first winding portion 6a corresponds to a range between the entrance position and the separation position of the belt 6 with respect to the primary pulley 3 in the belt traveling direction. The second winding portion 6b corresponds to a range between a position at which the belt 6 enters and leaves the secondary pulley 5 in the belt traveling direction. For this reason, the first winding portion 6a and the second winding portion 6b change according to the gear ratio. FIG. 1 shows the first winding portion 6a and the second winding portion 6b in a state where the gear ratio is “1”. In the present invention, the first cover portion 7a may be a portion that covers a part or the entirety of the first winding portion 6a. Further, the second cover portion 7b may be a portion that covers a part or the whole of the second winding portion 6b.

  The case 7 includes a third cover 7c that covers a part or all of the first chord 6c of the belt 6, and a fourth cover 7d that covers a part or all of the second chord 6d. Here, the chord portions 6c and 6d are portions of the belt 6 that are not wound around (not in contact with) the pulleys 3 and 5, that is, portions where the belt 6 advances linearly between the pulleys 3 and 5. The first chord portion 6c is on the tight side when, for example, the primary pulley 3 rotates in the forward direction (counterclockwise) in the driving state (torque transmitting state). The second chord portion 6d is on the loose side when, for example, the primary pulley 3 rotates in the forward direction while being driven.

  In the first wrapping portion 6a and the second wrapping portion 6b, when the case 7 (the first cover portion 7a and the second cover portion 7b) is disposed close to the pulleys 3 and 5, when the belt 6 is broken, The belt 6 receives a load outward in the radial direction due to the pressure between the pulleys 3 and 5. Therefore, the belt 6 may collide with the case 7 and damage the case 7, or the belt 6 may be fitted between the case 7 and the pulley 3.5 to lock the pulley shafts 2 and 4. Therefore, in the first winding portion 6a and the second winding portion 6b, it is necessary to manage gaps between the case 7 and the pulleys 3 and 5, respectively.

  Therefore, an example of the management of the gap between the case 7 and the pulleys 3 and 5 in the first winding portion 6a will be described below. Note that the management of the gap between the case 7 and the primary pulley 3 may be the same as the management of the gap between the case 7 and the secondary pulley 5 in the second winding portion 6b. The management of the gap between the primary pulley 3 and the case 7 in the portion 6a will be described, and the description of the management of the gap between the secondary pulley and the case in the second winding portion 6b will be omitted.

  FIG. 2 is a sectional view showing the primary pulley 3. In FIG. 2, the upper half of the primary pulley 3 with respect to the input shaft 2 is shown, and the lower half is omitted. As shown in FIG. 2, the primary pulley 3 presses the belt 6 in the axial direction with the fixed sheave 8 and the movable sheave 9. The state shown in FIG. 2 is a state in which the fixed sheave 8 and the movable sheave 9 are closest to each other, that is, a state in which the winding diameter of the belt 6 is maximized. In this state, the gap between the inner wall of the first cover portion 7a and the outer diameters 11a and 12a of the cone surfaces 11 and 12 is managed so as to satisfy the following conditional expressions (1) and (2).

Dcase> Dm + (Lpl− (ab)) / tan θ + 2hbu (1)
Dpully> Dcase-2 (hbu + hpl) (2)

  “Dcase” in the above equations (1) and (2) represents the minimum inner diameter of the first cover part 7a. Note that the minimum inner diameter of the first cover portion 7a is the diameter of an inner wall disposed radially outward with respect to the widest portion Lb of the belt 6 in the case 7. The widest part Lb is the widest part of the belt 6 in the axial direction, that is, the length of the pin in the axial direction. “Dpully” in the above equation (2) represents the outer diameter of the cone surface 11 of the fixed sheave 8. The outer diameter of the cone surface 11 of the fixed sheave 8 is the same as the outer diameter of the cone surface 12 of the movable sheave 9. “Hbu” in the above equations (1) and (2) represents the length between the upper end position 6 e of the belt 6 and the belt pitch line 6 f in the radial direction of the primary pulley 3. Here, the belt pitch line 6f represents the center of the pin in the radial direction.

  “Dpl” shown in FIG. 2 represents the diameter of the belt pitch line 6f. “Hpl” in the above equation (2) represents the length between the belt pitch line and the lower end 6 g of the pin of the belt 6 in the radial direction. "Lpl" in the above equation (1) represents the length of the pin at the belt pitch line 6f in the axial direction. “Dm” in the above equation (1) represents the diameter of the cone surface 11 at the center position 11 b in the radial direction. The diameter of the central position 11b of the cone surface 11 is the same as the diameter of the central position 12b of the cone surface 12. “A” in the above formula (1) represents the length between the contact portion (restriction portion) of the contact portion 13 and the contacted portion 14 and the center position 11b of the cone surface 11 in the axial direction. “B” in the above equation (1) represents the length between the contact portion described above and the center position 12 b of the cone surface 12 in the axial direction. “Θ” in the above equation (1) represents an angle of the cone surface 11 with respect to a direction perpendicular to the input shaft 2. The angle θ of the cone surface 11 is the same as the angle of the cone surface 12 with respect to a direction perpendicular to the input shaft 2.

  The above equation (1) is used to position the upper end position 6e on the outer side in the radial direction of the belt 6 inside the inner wall of the first cover portion 7a in the radial direction when the movable sheave 9 and the fixed sheave 8 are closest to each other. It is an expression of. Equation (2) indicates that, when the movable sheave 9 and the fixed sheave 8 are closest to each other, the outer diameters of the cone surfaces 11 and 12 are determined by contacting the upper end position 6e of the belt 6 with the inner wall of the first cover 7a. 6 is an equation for setting the diameter to be larger than the diameter up to 6 g of the lower end of the pin.

  According to the present invention, by satisfying the expressions (1) and (2), even if the belt 6 is broken at the first winding portion 6a, the belt 6 is formed between the inner wall of the first cover portion 7a and the cone surface 11. It does not fit between the outer diameter. That is, the belt 6 may not move in the advancing direction due to the pressing force received by the belt 6 at three points at the time of breakage, that is, the belt 6 may be locked. The three points of the pressing force are: the pressing force received from the cone surface 11 of the fixed sheave 8 in the axial direction, the pressing force received from the cone surface 12 of the movable sheave 9 in the axial direction, and the belt 6 broken in the radial direction. And the pressing force that receives the reaction force when the contact is made. When the belt 6 is locked by the three pressing forces, the pulley shaft is locked. By managing the gap between the case 7 and the pulleys 3 and 5 as described above, since at least the pressing force received from the case 7 side is not generated, the broken belt 6 can be slid in the traveling direction of the belt 6. For this reason, locking of the pulley shaft can be prevented.

  Although not shown, the first chord portion 6c and the second chord portion 6d described with reference to FIG. 1 may each include a pair of guide rails. Each guide rail may be arranged at least on the case 7 side of the chords 6c, 6d, that is, on the outside. The guide rail may be rotatably supported by the case 7 so as to follow the inclination of the chord portions 6c and 6d in the traveling direction changing with a change in the gear ratio. When such a guide rail is provided, a gap between the third cover portion 7c of the case 7 and the first chord portion 6c and a gap between the fourth cover portion 7d of the case 7 and the second chord portion 6d are provided. The gap may be set wider than the gap that satisfies the above formulas (1) and (2), that is, the gap between the case 7 and the pulleys 3 and 5 in the winding portion. According to this, it is possible to secure a wide gap that does not lock the rotation of the guide rail. Therefore, if the belt 6 is broken, the guide rail comes into contact with the case 7 so that the belt 6 is pressed to the sheave side. Can be eased.

  DESCRIPTION OF SYMBOLS 1 ... Continuously variable transmission, 2 ... Input shaft, 3 ... Primary pulley, 3a ... Pulley groove, 4 ... Output shaft, 5 ... Secondary pulley, 5a ... Pulley groove, 6 ... Chain belt, 6a ... 1st winding part, 6b: second winding portion, 6c: first string portion, 6d: second string portion, 6e: upper end position, 6f: belt pitch line, 6g: pin lower end, 7: case, 7a: first cover portion, 8 ... fixed sheave, 9 ... movable sheave, 11 ... fixed sheave cone surface, 12 ... movable sheave cone surface.

Claims (1)

A primary pulley having a fixed sheave to which torque is transmitted from the input shaft and a movable sheave movable in the axial direction of the input shaft with respect to the fixed sheave;
A secondary pulley having a fixed sheave for transmitting torque to the output shaft and a movable sheave movable in the axial direction of the output shaft with respect to the fixed sheave;
A plurality of links, and a plurality of pins for connecting the plurality of links in a ring shape, wherein the input at the pins is formed when each of the plurality of links is wound around a pulley groove formed by a cone surface of the fixed sheave and the movable sheave. A chain belt in which both end surfaces in the axial direction of the shaft contact the pair of cone surfaces,
A restrictor provided on each of the primary pulley and the secondary pulley, for restricting the fixed sheave and the movable sheave to a state of closest approach in the axial direction;
A continuously variable transmission including a primary pulley, a case storing the secondary pulley and the chain belt,
The case may be configured such that at least one of the primary pulley and the secondary pulley and the whole or a part of the winding part around which the chain belt is wound are concentric circles around the circumference center of the chain belt at the winding part. It has a cover part to cover on,
The minimum inner diameter of the cover part in the winding part is “Dcase”,
The outer diameter of the pair of cone surfaces is "Dpully",
The length between the upper end position of the chain belt and the belt pitch line in the radial direction of the pulley is defined as “hbu”, wherein the belt pitch line is the chain belt wound in the closest state. At the radial center of the pin at
The length between the belt pitch line and the lower end position of the pin in the chain belt in the radial direction is "hpl",
The length of the pin at the belt pitch line in the axial direction is "Lpl",
The diameter at the center of the cone surface is "Dm",
The length between the regulating portion and the central position of the cone surface of the fixed sheave in the axial direction is `` a '',
The length between the regulating portion and the central position of the cone surface of the movable sheave in the axial direction is "b",
A continuously variable transmission that satisfies the following conditional expressions (1) and (2) when an angle of the cone surface with respect to a direction perpendicular to the input shaft is “θ”.

Dcase> Dm + (Lpl− (ab)) / tan θ + 2hbu (1)
Dpully> Dcase-2 (hbu + hpl) (2)

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