JP2017053373A - Continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve power transmission efficiency in a continuously variable transmission.SOLUTION: A continuously variable transmission is equipped with a first ball 20 and a second ball 30 tiltably provided between an input shaft 10 and an output shaft 12; a first disc 40 and a second disc 42 which have friction surfaces capable of transmitting power between the input shaft 10, the first ball 20, and the second ball 30; and a third disc 44 and a second disc 46 which have friction surfaces capable of transmitting power between the output shaft 12, the first ball 20, and the second ball 30. Thrust which the first ball 20 and the second ball 30 receive from the first to forth discs 40, 42, 44, and 46 is cancelled at a contact E between the first ball 20 and the second ball 30.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a continuously variable transmission (CVT) used in an automobile driven by an engine.

  Conventionally, this type of continuously variable transmission includes a power roller that is in contact with a curved surface formed in a toroidal shape between an input disk and an output disk that are arranged to face each other, and the power roller is supported by a trunnion and tilts. There is known one that obtains a stepless speed ratio (speed ratio) (see, for example, Patent Document 1).

However, the toroidal curved surface formed on the input disk and the output disk in the toroidal-type continuously variable transmission provided with the power roller in contact with the curved surface formed in the toroidal shape of the input disk and the output disk arranged opposite to each other. It is also related to the fact that a power roller is installed on the outside in the radial direction and the same outer surface on the inside in the radial direction of the power roller is in contact with both the input disk and the output disk to transmit power, so that a large thrust acts on the transmission of these power There were the following problems.
That is, since the input disk and the output disk rotate in opposite directions, the bearing loss that receives the thrust acting between the two is large, and the power transmission efficiency is lowered accordingly.
Furthermore, the bearing loss that supports the radial thrust acting on the power roller is large, and the power transmission efficiency is reduced.

JP 2013-213563 A

The problem to be solved is that the input shaft and the output shaft rotate in opposite directions, and the loss of each bearing receiving each thrust of the input disk, output disk and power roller is large, and the power transmission efficiency is low. Is a point.
The object of the present invention is to avoid the use of bearings between members that rotate in reverse from each other, and to prevent thrust acting on the power roller from being received by the roller support bearing, thereby greatly reducing the rotation loss of each support bearing. There is to make it.

  The continuously variable transmission of the present invention is a pair of an input shaft, an output shaft arranged in parallel with the input shaft, a case, a stator that can be locked to the case, and a pair of input and output shafts, A first ball shaft and a second ball shaft that are tiltably provided on the stator, and two first and second balls that are rotatably supported by the first ball shaft and the second ball shaft, respectively, and are in contact with each other. A first disk having a friction surface in which the input shaft and the rotation direction are integral and in contact with the first ball and capable of transmitting power; a second disk having a friction surface in contact with the second ball and capable of transmitting power; and an output shaft And a third disk having a friction surface capable of transmitting power in contact with the first ball, and a fourth disk having a friction surface capable of transmitting power in contact with the second ball. 1st ball from disk and 2nd disk The thrust acting on the second ball and the thrust acting on the first ball and the second ball from the third disk and the fourth disk are canceled by the contact points of the first ball and the second ball. .

  The continuously variable transmission according to the present invention rotates when the first ball and the second ball are in contact with each other, and the first ball is moved continuously between the input shaft and the auxiliary shaft via the first to fourth disks. The thrust that the second ball receives from the first to fourth disks cancels out at the contact point between the first ball and the second ball.

Therefore, the continuously variable transmission according to the present invention corresponds to the gap between the input shaft and the output shaft of the conventional example, the output shaft, the first roller, and the second roller rotate in the same direction, and the power roller of the conventional example. Since the thrusts acting on the two balls corresponding to each other are canceled out, the loss of each support bearing can be reduced and the power transmission efficiency can be improved.

FIG. 3 shows a main part of the continuously variable transmission according to the first embodiment of the present invention, and is a cross-sectional view taken along line AA in FIG. 2. It is sectional drawing along the BB line in FIG. It is sectional drawing which shows the operation state in the continuously variable transmission of FIG.

  Hereinafter, a continuously variable transmission according to an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows a main part of a continuously variable transmission according to Embodiment 1 of the present invention, and is a cross-sectional view taken along line AA of FIG. FIG. 2 is a cross-sectional view taken along line BB in FIG. 1 excluding the case 3 described later.
FIG. 3 is an operation diagram showing a state in which a speed ratio described later is changed from the state of FIG.

The input shaft 10 and the output shaft 12 are parallel to each other and are rotatably supported by the case 3 by bearings 10g, 10j and 12c, 12d, respectively.
In the following description, unless otherwise specified, the expressions “axial direction” and “radial direction” are intended for the input shaft 10.

Between the input shaft 10 and the output shaft 12, a first ball 20 and a second ball 30 are arranged side by side in the axial direction, and both the balls 20 and 30 are in contact with each other at a contact point E. The first ball 20 and the second ball 30 are rotatably supported on the first ball shaft 22 and the second ball shaft 32 by a bearing 22a and a bearing 32a (not shown) similar to the bearing 22a.
Referring to FIG. 2, the first ball shaft 22 and the second ball shaft 32 are fixed to the first trunnion 24 and the second trunnion 34, respectively.
The first ball 20 and the second ball 30 have a gap that can move slightly in the axial direction of the first ball shaft 22 and the second ball shaft 32 with respect to the first trunnion 24 and the second trunnion 34. have.

As shown in FIGS. 1 and 2, the first trunnion 24 and the second trunnion 34 can be tilted by pins 26a and 36a to the first holder 26 and the second holder 36 shown by a two-dot chain line in FIG. 1, respectively. Supported by
The first holder 26 and the second holder 36 are swingably supported by a pin 28a on the stator 28 and 38a indicated by a two-dot chain line in FIG.
Since the pins 26a, 36a and the pins 28a, 38a are slightly separated from each other, the first holder 26 and the second holder 36 are swung so that the first ball 20 and the second ball 30 are axially moved. It is movable.
As shown in FIG. 1, the stator 28 is locked to the case 3 so as to be slightly rotatable (predetermined rotation range), and the rotation center thereof is an extension line between the spherical centers of the first ball 20 and the second ball 30. It is.
2 is a cross section on the first ball 20 side, the cross section on the second ball 30 side is the same as this. Accordingly, the pin 38a corresponds to the pin 28a.

A guide disk 17 is provided between the input shaft 10 and the first ball 20 and the second ball 30. The guide disk 17 is rotatably supported by the pin 18a of the table 18, and although not shown, the table is omitted. 18 is fixed to the case 3.
A first guide groove 17a and a second guide groove 17b are formed in the guide disk 17, and the first and second guide grooves 17a and 17b are respectively provided on the input shaft 10 side of the first ball shaft 22 and the second ball shaft 32. The end portions 22b and 32b are engaged. Note that the end portions 22b and 32b are partially formed into a spherical shape.
The first and second guide grooves 17a and 17b are spiral grooves when viewed from above in FIG. 1, and as seen in FIG. 3, the first ball shaft 22 and the second ball shaft 32 tilt. The guide disk 17 rotates around the pin 18a.
A worm gear 17c that rotates the guide disk 17 is formed on the outer periphery of the guide disk 17 (see FIG. 2).

A first disk 40 is provided on the input shaft 10 via the ball spline 10a so that the rotation direction is integral and the axial direction is movable, and the second disk 42 is provided integrally.
The first disk 40 and the second disk 42 are respectively in contact with the outer surfaces 20a and 30a of the first ball 20 and the second ball 30 to form friction surfaces 40a and 42a capable of transmitting torque.

  The input shaft 10 is provided with a cylinder 10d and a piston 10e. A hydraulic pressure described later is applied to the piston 10e to press the first disk 40 against the first ball 20, and at the same time, the second disk 42 is moved to the second ball. A so-called thrust that is drawn toward the side 30 can be applied to the first ball 20 and the second ball 30, respectively.

On the other hand, a third disk 44 and a fourth disk 46 are integrally provided on the output shaft 12, and, like the first disk 40 and the second disk 42, the outer surfaces 20a of the first ball 20 and the second ball 30, respectively. , 30a, and friction surfaces 44a and 46a capable of transmitting torque are formed.
Therefore, when a thrust is applied to the first disk 40 by the piston 10e, the first disk 40 and the second disk 42 sandwich the two first balls 20 and the second ball 30 in the axial direction. The friction surfaces 40 a and 42 a are pressed against the outer surfaces 20 a and 30 a of the first ball 20 and the second ball 30.

  Here, since the first ball 20 and the second ball 30 can move slightly in the axial direction of the first ball shaft 22 and the second ball shaft 32 as described above, the first ball 20 and the second ball 30 can be moved from the first disk 40 and the second disk 42. The thrust received by the first ball 20 and the second ball 30 causes the first ball 20 and the second ball 30 to move radially outward and be pressed against the third disk 44 and the fourth disk 46.

  That is, the thrust generated by the piston 10e is the friction surfaces 40a, 42a, 44a, 46a of the four first to fourth disks 40, 42, 44, 46, and the two first balls 20 and the second balls 30. The outer surfaces 20a and 30a of each other are pressed against each other, and the thrust acts on the contact point E between the first ball 20 and the second ball 30 to be offset.

The output shaft 12 rotatably supports the first roller 12g and the second roller 12h with bearings 12i and 12j, and the intermediate roller 13 is in contact with the first roller 12g and the second roller 12h.
The intermediate roller 13 is rotatably supported by bearing holders 13c and 13d provided with bearings 13a and 13b. As shown in FIG. 2, the bearing holder 13c is supported so as to be swingable around a pin 13e. In addition, although illustration is abbreviate | omitted, the pin 13e is being fixed to the case 3, and these are the same also on the bearing 13b side.
Therefore, the intermediate roller 13 is movable in the radial direction along with the swinging of the bearing holder 13c.

The input shaft 10 has a first outer surface 10m and a second outer surface 10n.
Between the first outer surface 10m and the second outer surface 10n and the intermediate roller 13 described above, a support ring 50 is provided so as to be inscribed therein.
That is, the inner surface 50 a of the support ring 50 is rotatable in contact with the first outer surface 10 m, the second outer surface 10 n, and the outer surface 13 e of the intermediate roller 13.

As described above, the thrust acting on the first ball 20 and the second ball 30 from the four friction surfaces 40a, 42a, 44a, 46a is offset by the contact point E, but the first to fourth are accompanied by the thrust. The radial force acting on the input shaft 10 and the output shaft 12 from the disks 40, 42, 44, 46 is as follows.
That is, the radial load acting on the input shaft 10 from the first and second disks 40 and 42 acts on the bearings 10g and 10j and the support ring 50 that rotatably support the input shaft 10.

The radial loads acting on the output shaft 12 from the third and fourth disks 44 and 46 are the bearings 12c and 12d that rotatably support the output shaft 12, the first roller 12g, the second roller 12h, and the intermediate It acts on the support ring 50 via the roller 13.
Therefore, some of these radial loads act on the support ring 50 and are canceled out.
At this time, the rotation speeds of the first roller 12g and the second roller 12h rotated by the support ring 50 and the rotation speed of the output shaft 12 are not the same because they vary depending on the speed ratio described later, but the rotation direction is the same.

Here, the load ratio of the radial load acting on the bearings 10g and 10j and the bearings 12c and 12d that rotatably support the input shaft 10 and the output shaft 12 is the rigidity, thermal expansion, and dimensional accuracy of the support ring 50 and the case 3. It depends on.
That is, if the dimensional accuracy is set to the same level, the rigidity of the support ring 50 is increased, and the thermal expansion coefficient of the case 3 is larger than that of the support ring 50, the bearings 10g and 10j are obtained when the temperature of the case 3 is high. The burden ratio of the radial load acting on the bearings 12c and 12d is reduced.

  Further, for example, if one of the bearings 10g and 10j or the bearings 12c and 12d is configured to be swingably supported by the case 3 like the bearing holder 13c, all of the radial load acts on the support ring 50. Therefore, the load of the radial load acting on the bearings 10g and 10j and the bearings 12c and 12d can be reduced to 0 (zero).

As described above, the stator 28 is locked to the case 3 so as to be able to rotate, but this is driven by the rotation of the control shaft 28c.
That is, a planetary gear 70 is provided between the control shaft 28 c and the stator 28. The planetary gear 70 includes a sun gear 28n formed on the control shaft 28c, a ring gear 70a connected to the stator 28, and a plurality of pinions 74 rotatably supported by the carrier 72 between the ring gear 70a and the sun gear 28n. is there.
A driving gear 76 is formed integrally with the carrier 72, and a first control gear 78 a meshed with the driving gear 76 is rotatably supported by the case 3.

The first control gear 78a can drive the worm gear 17c of the guide disk 17 by rotating the drive pinion 80 via the driven gear 78b as shown in FIG.
That is, by rotating the control shaft 28c, the guide disk 17 is driven via the first control gear 78a and the like, and the stator 28 can be driven by the reaction torque acting on the ring gear 70a. .

Next, the operation of the continuously variable transmission according to the first embodiment shown in FIGS. 1 and 2 will be described with reference to FIG.
Although not shown, the continuously variable transmission shown in FIG. 1 can include a hydraulic pump and a controller, and the following operations may be performed based on instructions from the controller. In addition, the continuously variable transmission of the first embodiment uses an appropriate hydraulic oil that also serves as a lubricant.
The rotation direction in the following description indicates a case when viewed from the left side in FIG. 1 or when viewed from the input shaft 10 side.

  When the input shaft 10 rotates and a hydraulic pressure corresponding to the torque is supplied to the cylinder 10d, the piston 10e pushes the first disk 40 toward the first ball 20 and pulls the second disk 42 toward the second ball 30. As described above, the contact surfaces of the four third and fourth disks 44 and 46 are also combined, and the friction surfaces 40a, 42a, 44a, and 46a, and the outer surfaces of the two first balls 20 and the second balls 30 are combined. 20a and 30a are pressed against each other.

Thus, when the input shaft 10 is rotated clockwise, the first disk 40 rotates the first ball 20 clockwise, and the second disk 42 rotates the second ball 30 counterclockwise.
The first and second balls 20 and 30 rotate the output shaft 12 counterclockwise via the third and fourth disks 44 and 46. Note that, although not involved in power transmission, the support ring 50 rotates clockwise.

  Here, as shown in FIG. 3, the contact point between the first disk 40 and the first ball 20 is F, the contact point between the second disk 42 and the second ball 30 is G, and the contact point between the third disk 44 and the first ball 20. Is H, and the contact point between the fourth disk 46 and the second ball 30 is I. Strictly speaking, it is difficult to specify the position of each contact point. However, as shown in the drawing, the vicinity of the center of each contact portion will be described as a contact point.

The distance between the contact F and the center of the input shaft 10 is R1, the distance between the contact F and the center of the first ball shaft 22 is R2, the distance between the contact H and the center of the first ball shaft 22 is R3, and the contact H And the center of the output shaft 12 is defined as R4. The contact points I and G are regarded as symmetrical with the contact points F and H with the contact point E between the first and second balls 20 and 30 as the center, and the description thereof is omitted.
As a result, the rotational speed ratio between the input shaft 10 and the output shaft 12 (the speed of the input shaft 10 / the speed of the output shaft 12) can be defined as R2 / R4 / R1 / R3, assuming that there is no slip at each contact. .
Further, since R1 and R4 can be regarded as being substantially constant, the speed ratio is determined by R2 / R3.

Next, a case where the rotational speed ratio between the input shaft 10 and the output shaft 12 is changed will be described.
In FIG. 1, the first and second ball shafts 22 and 32 are perpendicular to the input shaft 10 and the output shaft 12, and the first ball shaft 22 and the second ball shaft 32 are parallel to each other, and the distance R2 And R3 can be said to have the same value, and the speed ratio in this case is approximately the center value of the speed ratio range described later.
Subsequently, as shown in FIG. 3, when the first ball shaft 22 is tilted counterclockwise and the second ball shaft 32 is tilted in the opposite direction, the aforementioned distances R2 and R3 change from FIG. R3 is smaller than R2. Similarly, the second ball 30 side also changes, but the description is omitted. As a result, in the state of FIG. 3, it changes to the deceleration side compared with FIG.
At this time, it can be seen that the guide disk 17 rotates from the position shown in FIG.

Although illustration is omitted, contrary to FIG. 3, when the first ball shaft 22 is tilted clockwise and the second ball shaft 32 is tilted counterclockwise, it changes to the speed increasing side as compared to FIG.
Also at this time, the guide disk 17 rotates from the position shown in FIGS.
In this way, by tilting the first ball shaft 22 and the second ball shaft 32 symmetrically about the contact point E with the center in FIG. 1, the state from the deceleration side in FIG. The speed ratio can be changed steplessly.

Next, a method for changing the tilt angles of the first ball shaft 22 and the second ball shaft 32 will be described.
As described above, the tilt angle of the first ball shaft 22 and the second ball shaft 32 changes, and the guide disk 17 rotates. Therefore, it is possible to change the tilt angles of the first ball shaft 22 and the second ball shaft 32 by rotating the guide disk 17, and it can be said that it is an effective means particularly when the transmission torque is small.

However, when the transmission torque is large, the tilt angle between the first ball shaft 22 and the second ball shaft 32 is changed by the following method.
That is, as can be seen from FIG. 2, in a steady state where a constant speed ratio is maintained, a line connecting the center of the input shaft 10 and the center of the output shaft 12, and the centers of the first ball shaft 22 and the second ball shaft 32. Although the lines match, it is possible to change the tilt angles of the first ball shaft 22 and the second ball shaft 32 by changing this line.

Specifically, by rotating the control shaft 28c, a torque for rotating the guide disk 17 is given, and the stator 28 is rotated by the reaction torque.
That is, if the transmission torque acting from the input shaft 10 is large, the torque for tilting the first ball shaft 22 and the second ball shaft 32 via the guide disk 17 also increases, but the reaction force causes the stator 28 to slightly move. Can be rotated.
Hereinafter, when the first ball 20 is described, as can be seen with reference to FIG. 2, when the first stator 28 is rotated, the first ball shaft 22 tilts, and the center line thereof is the center of the input shaft 10 and the output shaft 12. Deviates from the line connecting the centers of

As a result, the positional relationship between the center line of the first ball shaft 22 and the contacts F and H as seen in FIG. 2 is shifted. As a result, a couple that tilts the first ball shaft 22 acts at the contact points F and H to tilt them. When the desired speed ratio is reached, the torque applied to the control shaft 28c is reduced, and the stator 28 is returned to the position shown in FIG. As a result, a steady state is obtained in which the speed ratio is changed. The same thing also works on the second ball 30 side that is symmetrically arranged.
At this time, since the guide disk 17 is rotated with the tilt of the first ball shaft 22 and the second ball shaft 32 with respect to the state before the speed ratio is changed, the position in the rotational direction of the control shaft 28c is accordingly increased. Changes. For this reason, the speed ratio can be sensed at the rotational direction position of the control shaft 28c.
At this time, the guide disk 17 has a function of regulating the tilt angles of the ball shafts 22 and 32 so as not to deviate from each other.

The method of rotating the stator 28 is one means, and as another method, for example, the first ball shaft 22 and the second ball shaft 32 are moved in parallel to or from the left and right in FIG. May be.
Although the method for rotating the stator 28 is not shown, it may be moved by hydraulic pressure or by an electric motor.

  Thus, according to the first embodiment, the thrust that presses the friction surfaces 40a, 42a, 44a, 46a and the outer surfaces 20a, 30a of the two first balls 20 and the second balls 30 for power transmission is as follows. , Since they cancel each other at the contact point E between the first ball 20 and the second ball 30, they do not act on the bearings 22a and 32a of the first and second ball shafts 22 and 32, and the bearings 22a and 32a are thrust. There is no loss associated with.

On the other hand, the radial force generated at each of the contacts F, G, H, and I cancels with the support ring 50 receiving part or most of the force as described above. Losses of the bearings 10g and 10j and the bearings 12c and 12d that are rotatably supported can be suppressed to a small value.
In addition, a radial load borne by the support ring 50 acts on the bearings 12i and 12j between the output shaft 12, the first roller 12g, and the second roller 12h, but the output shaft 12 and the first roller 12g Since the rotation direction of the second roller 12h is the same as described above, the loss is significantly reduced compared to the bearing between the input shaft and the output shaft of the conventional example that rotates in the opposite direction, and the power transmission efficiency is correspondingly increased. improves.
Further, since the thrust due to the thrust does not act on the first and second trunnions 24 and 34 and the first and second holders 26 and 36 at all, it is not necessary to make them ruggedly and make them lightweight and at low cost. It is also a merit to be able to.

In the above description, the first roller 12g and the second roller 12h intermediate roller are provided on the output shaft 12 side, and the first outer surface 10m and the second outer surface 10n are formed on the input shaft 10 side. Needless to say.
Further, the guide disk 17 is provided between the input shaft 10 and the first ball 20 and the second ball 30, but the guide disk 17 is provided between the output shaft 12 and the first ball 20 and the second ball 30. It may be provided.
Further, the planetary gear 70 may be connected such that the ring gear 70 a drives the guide disk 17 and the carrier 72 drives the stator 28. That is, it is important to drive the stator 28 with a reaction torque that drives the guide disk 17.

  As described above, in the continuously variable transmission according to the present invention, the first ball 20 and the second ball 30 are provided in pairs between the input shaft 10 and the output shaft 12, and the first shaft on the input shaft 10 side is provided. The first ball receives the thrust received from these four discs 40, 42, 44, 46 between the disc 40, the second disc 42, and the third disc 44, the fourth disc 46 on the output shaft 12 side. Since the point of contact E between the ball 20 and the second ball 30 cancels out, the thrust does not act on the bearing that supports the input shaft 10 and the output shaft 12.

  Further, the loss of the bearings 10g and 10j and the bearings 12c and 12d that support the output shaft 10 and the output shaft 12 can be suppressed to a small value by the support ring 50 or the like. Since the bearings 12i and 12j on which the radial load borne by the support ring 50 acts are between the members rotating in the same direction, there is less loss compared to the conventional example. All of these have the merit of contributing to improvement of power transmission efficiency.

  Based on the general knowledge of those skilled in the art, the continuously variable transmission of the present invention can be driven in reverse rotation in combination with a planetary gear train, or can be provided with a torque converter or the like to smoothly start the vehicle. It can implement in the aspect which added.

  The continuously variable transmission of the present invention can be widely applied to vehicles such as automobiles and bicycles that are particularly required to have high power transmission efficiency, and various rotating machines such as machine equipment and wind power generators.

10 Input shaft 12 Output shaft 14 Secondary shaft 20 First ball 22 First ball shaft 28 Stator 28
30 Second ball 32 Second ball shaft 40 First disk 42 Second disk 44 Third disk 46 Fourth disk 50 Support ring

Claims (4)

An input shaft;
An output shaft arranged parallel to the input shaft;
Case and
A stator that can be locked to the case;
A first ball shaft and a second ball shaft which are disposed between the input shaft and the output shaft and are provided on the stator so as to be tiltable;
Two first balls and second balls that are rotatably supported by the first ball shaft and the second ball shaft, respectively, and in contact with each other;
A first disk having a friction surface in which a rotational direction is integrated with the input shaft and capable of transmitting power in contact with the first ball; and a second disk having a friction surface capable of transmitting power in contact with the second ball;
A third disk having a friction surface capable of transmitting power in contact with the first ball, and a fourth disk having a friction surface capable of transmitting power in contact with the second ball; With
A thrust acting on the first ball and the second ball from the first disk and the second disk, and a thrust acting on the first ball and the second ball from the third disk and the fourth disk. The continuously variable transmission is offset by the contact points of the first ball and the second ball.   2. An intermediate roller that contacts one of an outer surface formed on the input shaft and an outer surface formed on the output shaft is provided, and a support ring that is inscribed on the other of the intermediate roller and the outer surface is provided. The continuously variable transmission described.   A guide disk that rotates as the first ball shaft and the second ball shaft are tilted is provided between one of the input shaft and the output shaft, and the first ball and the second ball. The continuously variable transmission according to claim 1 or 2. A control shaft that rotates the guide disk, and a planetary gear is provided between the control shaft and the guide disk, and the stator can be driven by a reaction torque that the control shaft drives the guide disk. The continuously variable transmission according to claim 3.

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