JP3473187B2 - Toroidal type continuously variable transmission - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a bearing for an input / output shaft of a toroidal type continuously variable transmission used in a vehicle or the like.

[0002]

2. Description of the Related Art As a structure for supporting an input / output shaft of a toroidal type continuously variable transmission, there is known a structure as disclosed in Japanese Patent Laid-Open No. 63-130953.

This will be described below. As shown in FIG. 8, a pair of toroidal input disks 1 are provided.
8. The output disk 20 is arranged coaxially with the input shaft 14, and the change of the inclination angle of the pair of power rollers 22, 22 pressed against the input disk 18 and the output disk 20 can be changed to an arbitrary gear ratio. It can be set steplessly.

The input disk 18 rotates almost integrally with the input shaft 14 via the cam roller 79 and the cam flange 77, and the input shaft 14 is an angular ball bearing provided at the end portion on the base end side (right side in the drawing). 65 and the cam flange 7
It is rotatably supported by a casing 67 by a needle bearing 66 provided at the end on the 7 side.

On the other hand, the output disk 20 is connected to the output gear 26 on the rear surface (right side in the drawing) and is supported so as to be rotatable relative to the input shaft 14, and is disposed between the inner circumference of the output disk 20 and the input shaft 14. A needle bearing 73 interposed in the
It is axially supported by an angular ball bearing 75 interposed between the output gear 26 and the casing 67.

An angular ball bearing 65 that pivotally supports the input shaft 14 and an angular ball bearing 75 that axially supports the output gear 26 are coaxially arranged at a position where they can be brought into and out of contact with each other via a snap ring 9, and the power roller 22 It receives the reaction force of the axial force that it holds.

The pressure for holding the power roller 22 between the input disk 18 and the output disk 20 is generated by the disc spring 70 provided on the base end side of the input shaft 14 and the cam roller 79 provided on the left end side of the input shaft 14. .

The disc spring 70 is interposed between the spacer 68 of the angular ball bearing 65 that supports the input shaft 14 and the loading nut 69 that is fastened to the end of the input shaft 14, and the spacer 68 is shown in the figure. Since the spacer 68 and the input shaft 14 are allowed to be displaced in the axial direction, the input shaft 14 is biased to the right side in the drawing by the reaction force of the disc spring 70, and the power roller 22 is biased to the right side. Get the initial load to clamp.

The cam roller 79 provided at the left end of the input shaft 14 in the drawing generates a thrust force for urging the input disk 18 to the right in the drawing in response to the rotation of the input shaft 14. Therefore, the power roller 22 is sandwiched between the input disk 18 and the output disk 20 by the initial load of the disc spring 70 and the axial thrust generated by the cam roller 79, and rotates without slipping, and the torque from the input disk 18 is output. It is transmitted to 20.

Angular ball bearings 65 and 75, which support the input shaft 14 and the output gear 26, press the outer races against each other through the spacer 9 to support the clamping pressure of the power roller 22 and the radial load. There is.

[0011]

By the way, in the toroidal type continuously variable transmission as described above, in order to prevent the loss of the transmission torque due to the slip of the power roller 22, the power roller 2 is prevented.
2 and the input / output disks 18 and 20 are pressed with a large force to maintain a high contact surface pressure (pressure), and oil having a high pressure-viscosity index α, for example, traction oil is used.

Here, the viscosity η of the oil exponentially increases with respect to the pressure, and is expressed by the following equation (1).

Η = η ₀ × exp (α × P) (1) where η ₀ : viscosity at normal pressure P; contact surface pressure between the pressure power roller 22 and the input / output disks 18, 20 is high pressure such as 1 GPa By setting to, the traction oil becomes semi-solid, and the toroidal type continuously variable transmission uses this phenomenon to prevent the power roller 22 from slipping and ensure torque transmission efficiency. The internal lubrication is also done by this traction oil.

However, in such a conventional toroidal type continuously variable transmission, an angular ball bearing 65 is used as a bearing for the input shaft and the output shaft (output gear).
A spin occurs at 75, and the ball rotates about the normal line between the ball and the contact surface of the groove of the bearing. This spin is
Since as shown in FIG. 11, in the inner ring and the rotary shaft O _A and the rotation axis O _B intersects point C of the ball of the outer ring, the outer ring and the inner ring of the groove and the tangent La from the contact surface of the ball, Lb does not intersect both It rotates around a normal passing through the contact surface of the ball.

Then, as described above, the power roller 22
As mentioned above, the thrust-direction force applied to the angular ball bearing by the reaction force that clamps and presses the ball is extremely large, and the contact surface pressure between the ball and the groove is also very high, for example, exceeding 1 GPa. The oil becomes semi-solid as described above, and when spin of the ball occurs, the loss torque increases, and the loss torque in the angular ball bearing is larger than that in the case where turbine oil is used, as shown in FIG. And the loss torque increases according to the input torque. Therefore, the ratio of the angular ball bearing of the input / output shaft to the total loss torque of the toroidal type continuously variable transmission is extremely large as shown in FIG. There is a problem that efficiency is reduced, and particularly in a high load region, loss torque is further increased and efficiency is further reduced.

Therefore, the present invention has been made in view of the above problems, and an object thereof is to reduce the torque loss due to the bearing of the input / output shaft to improve the efficiency of the toroidal type continuously variable transmission.

[0017]

SUMMARY OF THE INVENTION A first invention is an input disk connected to an input shaft, an output disk connected to an output shaft, and a toroidal shape formed on the facing surfaces of these input / output disks. A power roller sandwiched in the groove,
A toroidal type continuously variable transmission including first and second bearing means for axially supporting the input shaft and the output shaft inside a casing, and traction oil for lubricating the inside of the casing. The second bearing means is a tapered roller bearing.

A second aspect of the present invention is the same as the first aspect, wherein the contact angle of the first bearing means pivotally supporting the input shaft is
It is set to be larger than the contact angle of the second bearing means that supports the output shaft.

A third invention is the first or second invention.
In the invention, the pitch diameter of the taper roller of the second bearing means that pivotally supports the output shaft is set smaller than the pitch diameter of the taper roller of the first bearing means that pivotally supports the input shaft.

The fourth invention is the first to third inventions.
In any one of the inventions described above, the mass of the taper roller of the second bearing means axially supporting the output shaft is set smaller than the mass of the taper roller of the first bearing means axially supporting the input shaft.

[0021]

Therefore, according to the first aspect of the invention, the first and second bearing means are applied with the thrust load according to the clamping pressure of the power roller and the interior of the casing is lubricated with the traction oil. When the pressure on the contact surface of the rolling element of the second bearing means rises, the traction oil becomes semi-solid, but since the first and second bearing means are formed by the tapered roller bearing, spin is not generated in the tapered roller. Instead, the loss torque can be reduced as compared with the case where the angular ball bearing is used.

According to the second aspect of the invention, the rotation speed of the input / output shaft is the highest in the maximum speed range of the vehicle, and at this time the gear ratio is in the speed increasing state. The contact angle of the first bearing means on the input shaft side is set to be larger than the contact angle of the second bearing means on the output shaft side.
In the tapered roller bearing of the bearing means, while reducing the torque loss due to the friction between the tapered roller and the large collar,
The allowable rotation speed of the bearing can be maintained above the maximum rotation speed.

According to the third aspect of the invention, the pitch diameter of the taper roller of the second bearing means is set smaller than the pitch diameter of the taper roller of the first bearing means. It is possible to reduce the centrifugal force applied to the roller bearing and the tapered roller bearing of the second bearing means to reduce the torque loss due to the friction between the tapered roller and the large collar.

According to the fourth aspect of the invention, since the mass of the taper roller of the second bearing means is set to be smaller than the mass of the taper roller of the first bearing means, the output shaft having a higher maximum rotation speed than the input shaft is pivotally supported. By reducing the centrifugal force applied to the second bearing means, it is possible to reduce the torque loss due to the friction between the taper roller and the large collar in the tapered roller bearing of the second bearing means.

[0025]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, a case where the present invention is applied to the toroidal type continuously variable transmission shown in FIG. 8 of the conventional example is shown, in which the input shaft 14 is replaced with the angular ball bearings 65 and 75. The taper roller bearing 1 is provided as the first bearing means for supporting, and the taper roller bearing 2 is provided as the first bearing means for supporting the output gear 26 as the output shaft. Others are the same as those in the conventional example, The same parts are designated by the same reference numerals and the description thereof will be omitted.

Tapered roller bearing 1 on the input shaft side
And the tapered roller bearing 2 on the output shaft side is the outer ring 5,
6 are in contact with each other via a snap ring 9, and the input shaft side tapered roller bearing 1 supports the tapered roller 7 so as to support the thrust load in the direction of the power roller 22.
While the small-diameter portion of is disposed toward the power roller 22,
The output shaft side taper roller bearing 2 is arranged with the small diameter portion of the taper roller 8 facing the disc spring 70 so as to support the thrust load toward the disc spring 70 side.

As shown in FIG. 2, the taper roller bearing 1 on the side of the input shaft 14 has a large diameter portion 7b of the taper roller 7 in sliding contact with a large collar 31 projecting from the inner ring 3 and a small diameter portion 7a. A small collar 7a is provided on the inner ring 3 to prevent the tapered roller 7 from falling off, and the inner diameters of the inner ring raceway surface 30 and the outer ring raceway surface 50 are small on the small diameter portion 7a side.

[0029] with respect to the rotation axis O _A of the input shaft 14 coaxial with the inner ring 3 and the outer ring 5, the rotation axis O _B of the taper roller 7 is inclined at a predetermined angle gamma, the rotation axis O _B Figure 1 It intersects with the rotation axis O _A at a predetermined point C on the power roller 22 side.

Further, the close races L ₁ and L ₂ drawn from the contact surfaces of the outer roller raceway surface 50 and the inner ring raceway surface 30 on which the tapered roller 7 formed in a conical shape rolls and the taper roller 7 also rotate at the point C. It intersects with axis O _A and rotation axis O _B.

The tapered roller bearing 2 on the output shaft side is also constructed in the same manner as on the input shaft side. The operation will be described below.

Outer ring raceway surface 5 on which the taper roller 7 rolls
0 and the close battles L ₁ and L ₂ drawn from the contact surface between the inner ring raceway surface 30 and the taper roller 7 are the rotation axis O of the taper roller 7.
_Since all intersect at the intersection C of the rotation axis O _A of _B with the inner ring 3 and the outer ring 5, the taper roller 7 does not generate spin around the normal line of the contact surface as in the conventional example. The taper roller bearing 2 on the output shaft side is the same although not described in detail.

Therefore, even if the tapered roller bearings 1 and 2 are lubricated with traction oil, the increase in loss torque can be suppressed, and as shown in FIG. 3, the loss torque due to the tapered roller bearings 1 and 2 is an angular ball. It can be reduced compared to the bearing, and the efficiency of the toroidal type continuously variable transmission can be improved.

FIG. 4 shows a second embodiment in which the contact angle φ _i of the input shaft side taper roller bearing 1 is set to be larger than the contact angle φ _o of the output shaft side taper roller bearing 2 and other configurations are the same. This is similar to the first embodiment. Here, the contact angles γi and γo are the taper rollers 7 and 8
In eggplant axis angle perpendicular to the rotation axis O _A line of action and the bearing force, when the tapered roller bearing, the rotation axis O _A of the rotation axis O _B and the bearing of the taper roller is equal to the angle.

As shown in FIG. 5, the loss torque due to the taper roller bearing is mainly due to the friction between the taper roller 7 and the large collar 31, and the loss torque generated by the taper roller 7 and the large collar 31 is as follows. It is represented by.

M = μecos (βFa) (2) where M is the loss torque μ of the taper roller bearing, the coefficient of sliding friction is e, the height β from the bottom of the large collar to the point of action, and the taper. Roller opening angle Fa; axial load Therefore, from the above formula (2), the loss torque M can be made smaller as the opening angle β of the taper roller 7 becomes smaller.

Here, the opening angle β can be expressed by the following equation.

[0038] β = arc tan (Da / dm · sin γi) ... (3) However, Da; the average of the tapered roller diameter dm; rotation axis O _B and the rotation axis O of the bearing of the tapered roller; pitch diameter .gamma.i tapered roller than angle = contact angle the (3) of _a, it is possible to reduce the rotation axis O _B and the rotation axis O _a loss by increasing the angle = contact angle γi torque M, when setting a large γi Since the ratio of the centrifugal force applied to the taper roller 7 to the large collar 31 increases, the allowable rotation speed of the taper roller bearing 1 decreases.

Here, the number of rotations of the input / output shaft of the toroidal type continuously variable transmission becomes highest in the maximum speed range of the vehicle, and the gear ratio of the toroidal type continuously variable transmission is increased in such maximum speed range. In this state, the output disk 20 has a higher rotation speed than the input disk 18, that is, the input shaft side tapered roller bearing 1 has a lower maximum rotation speed than the output shaft side tapered roller bearing 2, and the input / output shaft taper roller If the same bearing is used,
The input shaft side has a margin for the maximum rotation speed.

Therefore, even if the contact angle γi of the tapered roller bearing 1 on the input shaft side is set to a large value, the allowable rotational speed does not fall below the maximum rotational speed, and the contact angle of the tapered roller bearing of the input / output shaft is set to the same value. The torque loss can be reduced and the efficiency of the toroidal-type continuously variable transmission can be improved as compared with the above case.

FIG. 6 shows a third embodiment, in which the pitch diameter dmo of the taper roller 8 of the taper roller bearing 2 on the output shaft side is set smaller than the pitch diameter dmi of the taper roller 7 of the taper roller bearing 1 on the input shaft side. Others are the same as those in the first embodiment.

As shown in the second embodiment, the maximum number of revolutions of the input / output shaft is such that the gear ratio is increasing in the maximum speed region of the vehicle, and the output shaft side taper roller bearing 2 is on the input shaft side. The maximum rotation speed is higher than that of the tapered roller bearing 1.

Therefore, by setting the pitch diameter dmo of the taper roller 8 on the output shaft side smaller than the pitch diameter dmi on the input shaft side, the centrifugal force of the taper roller 8 is reduced to form the inner ring 4 of the taper roller bearing 2. Large spit 3
The torque loss due to friction with No. 1 can be reduced, and the efficiency of the toroidal type continuously variable transmission can be improved.

FIG. 7 shows a fourth embodiment in which the average diameter Db of the taper roller 8 of the taper roller bearing 2 on the output shaft side is set smaller than the average diameter Da of the taper roller 7 of the taper roller bearing 1 on the input shaft side. Others are the same as those in the first embodiment.

As shown in the second embodiment, the maximum rotation speed of the input / output shaft is such that the gear ratio is in an increasing state in the maximum speed range of the vehicle, and the output shaft side taper roller bearing 2 is on the input shaft side. Since the maximum rotation speed is higher than that of the taper roller bearing 1, the mass is reduced by setting the average diameter Db of the taper roller 8 on the output shaft side smaller than the average diameter Da on the input shaft side, and the centrifugal force of the taper roller 8 is reduced. It is possible to reduce the torque loss due to friction with the large collar 31 formed on the inner ring 4 of the tapered roller bearing 2 and improve the efficiency of the toroidal continuously variable transmission.

[0046]

As described above, the first invention is the first invention.
Since the second bearing means is composed of a tapered roller bearing, spin does not occur in the tapered roller, and even if lubrication is performed with traction oil having a high pressure-viscosity index α, compared to the case where an angular ball bearing is used. As a result, the loss torque can be reduced, and the efficiency of the toroidal type continuously variable transmission can be improved.

Further, in the second invention, the contact angle of the first bearing means on the input shaft side is made smaller than the contact angle of the second bearing means on the output shaft side by utilizing the difference in the maximum rotational speeds of the input and output shafts. Because of the large setting, the tapered roller bearing of the first bearing means can reduce the torque loss due to the friction between the tapered roller and the large collar, while maintaining the allowable rotational speed of the bearing at or above the maximum rotational speed of the input shaft. It is possible to improve the efficiency of the toroidal type continuously variable transmission that lubricates the inside.

According to the third aspect of the invention, the pitch diameter of the taper roller of the second bearing means is set smaller than the pitch diameter of the taper roller of the first bearing means by utilizing the difference in the maximum rotational speeds of the input and output shafts. Therefore, the centrifugal force applied to the second bearing means having a higher maximum rotation speed than the input shaft can be reduced, and the torque loss due to the friction between the taper roller and the large collar can be reduced in the tapered roller bearing of the second bearing means, and the traction oil can be used for lubrication. It is possible to improve the efficiency of the toroidal type continuously variable transmission that is performed.

Further, in the fourth aspect of the invention, the mass of the taper roller of the second bearing means is set to be smaller than the mass of the taper roller of the first bearing means by utilizing the difference in the maximum rotational speeds of the input and output shafts. By reducing the centrifugal force applied to the second bearing means that supports the output shaft having the highest rotation speed higher than that of the input shaft, the tapered roller bearing of the second bearing means can reduce the loss torque due to the friction between the tapered roller and the large collar. It is possible to improve the efficiency of the toroidal-type continuously variable transmission that lubricates with traction oil.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a toroidal type continuously variable transmission showing an embodiment of the present invention.

FIG. 2 is a sectional view showing a tapered roller bearing of the same.

FIG. 3 is a graph showing the relationship between axial load and loss torque, where the solid line indicates the present invention and the alternate long and short dash line indicates a conventional example.

FIG. 4 is a graph showing a loss torque of a tapered roller bearing and showing a relationship between the loss torque and a rotation speed.

FIG. 5 is a sectional view of a tapered roller bearing showing a second embodiment.

FIG. 6 is a cross-sectional view of a tapered roller bearing showing a third embodiment.

FIG. 7 is a sectional view of a tapered roller bearing showing a fourth embodiment.

FIG. 8 is a cross-sectional view of essential parts showing a conventional toroidal type continuously variable transmission.

FIG. 9 shows the relationship between the loss torque and angular load of an angular ball bearing due to the difference in lubricating oil, the solid line indicates traction oil, and the alternate long and short dash line indicates turbine oil.

FIG. 10 is a graph showing the relationship between the loss torque and the input torque of the toroidal continuously variable transmission.

FIG. 11 is an explanatory diagram showing a spin state in the angular ball bearing.

[Explanation of symbols]

1 Tapered roller bearing 2 Tapered roller bearing Inner ring 5, 6 outer ring 7, 8 taper roller 30, 50 orbital plane 31 large brim 14 Input axis 18 Input disc 20 output discs 22 Power roller 26 output gears 67 casing

Claims (4)

(57) [Claims] 1. An input disk connected to an input shaft, an output disk connected to an output shaft, a power roller sandwiched between toroidal grooves formed on opposing surfaces of the input and output disks, respectively. A toroidal type continuously variable transmission including first and second bearing means for axially supporting an input shaft and an output shaft inside a casing, and traction oil for lubricating the inside of the casing.
And a toroidal type continuously variable transmission characterized in that the second bearing means is constituted by a tapered roller bearing. 2. The contact angle of the first bearing means pivotally supporting the input shaft is set to be larger than the contact angle of the second bearing means pivotally supporting the output shaft. Toroidal type continuously variable transmission. 3. The pitch diameter of the taper roller of the second bearing means for rotatably supporting the output shaft is the first for rotatably supporting the input shaft.
The toroidal type continuously variable transmission according to claim 1 or 2, wherein the pitch diameter of the tapered roller of the bearing means is set smaller than the pitch diameter. 4. The mass of the taper roller of the second bearing means pivotally supporting the output shaft is set smaller than the mass of the taper roller of the first bearing means pivotally supporting the input shaft. The toroidal type continuously variable transmission according to any one of claims 1 to 3.