JP2002188701A - Toroidal type continuously variable transmission and hole boring method for trunnion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toroidal type continuously variable transmission capable of making the minor axis of an ellipse which is a round hole of a trunnion coincide with the inclined rotation axis direction of the trunnion. SOLUTION: This toroidal type continuously variable transmission is arranged between an input disk and an output disk, supports a power roller with a pivot shaft, and fixes the pivot shaft to a round hole 16 of the trunnion 8 through a solid needle bearing. An outer ring of the solid needle bearing in the inclined rotation axis direction of the trunnion 8 is fit to the round hole 16 of the trunnion 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toroidal type continuously variable transmission used as a transmission for an automobile, for example, and a method of boring a trunnion.

[0002]

2. Description of the Related Art Generally, a variator of a toroidal type continuously variable transmission is configured as shown in FIG. In other words, an input disk 2 and an output disk 3 are rotatably supported on the input shaft 1 connected to a drive source (not shown) such as an engine via a needle bearing. A cam plate 4 is spline-engaged with the input shaft 1 on the rear side of the input disk 2, a roller 5 is interposed between the cam plate 4 and the input disk 2, and the input disk 2 is connected to the output disk 3. There is provided a loading cam type pressing mechanism 6 that presses against the side.

A trunnion 8 swinging about a pivot 7 is provided between the input disk 2 and the output disk 3, and a pivot shaft 9 is provided at the center of the trunnion 8. A power roller 10 is rotatably supported on the pivot shaft 9. The power roller 10 has a traction portion in contact with the input disk 2 and the output disk 3.
And are pivotally connected between them.

[0004] A power roller bearing 11 is provided between the trunnion 8 and the power roller 10. The power roller bearing 11 allows rotation of the power roller 10 while supporting a load applied to the power roller 10 in the thrust direction. Such a power roller bearing 1
One plurality of balls 12 are held by an annular retainer 14 provided between an annular outer ring 13 provided on the trunnion 8 side and the power roller 10 as a rotating unit.

The trunnion 8 of the toroidal type continuously variable transmission has a bag portion 8a provided in the trunnion 8 as shown in, for example, Japanese Patent Application Laid-Open No. H11-153203 and FIG.
A power roller 10 is mounted on the pivot 8
It is stored in a state supported by. The pivot shaft 9 is supported by a circular hole 16 provided on the back surface of the trunnion 8 via a needle bearing 15.

[0006]

SUMMARY OF THE INVENTION However, Japanese Patent Application Laid-Open
Japanese Patent No. 153203 discloses a power roller and a trunnion in which a toroidal-type continuously variable transmission is assembled in advance in a positional relationship after the assembly is completed. Regarding the gap between the outer ring of the needle bearing and the circular hole of the trunnion, Assuming that both parts are machined with precise roundness, that is, the case where the parts are ideally manufactured, after assembly, disassemble and avoid troublesome work such as reassembly. Things.

[0007] However, the trunnion has a complicated shape, and a clamping method for forming a circular hole on the back surface of the trunnion is complicated and not easy. Due to the influence of the clamp, the trunnion circular hole is ideally a perfect circle, but in reality, an elliptical circular hole is formed. This ellipse has a major axis and a minor axis.

For example, as shown in FIG. 6B, the circular hole 16 of the trunnion 8 is ideally a perfect circle 16a, but the ellipse 1 is ideal.
When the major axis direction of 6b coincides with the tilt axis direction A of the trunnion 8, a gap g exists between the outer ring of the needle bearing 15 and the circular hole 16 of the trunnion 8 in the tilt axis direction A.

As described above, when a load is applied to the toroidal type continuously variable transmission in a state where the gap g exists between the outer ring of the needle bearing 15 and the circular hole 16 of the trunnion 8 in the tilt axis direction A, the traction force is increased. B is generated in the vertical direction (direction A of traction tilt axis), and the piston force D
Works in the opposite direction. There is a gap g in the radial needle bearing that supports the power roller 10 and the needle bearing 15 that supports the pivot shaft 9.

For this reason, when a load is applied, the inner ring of the power roller 10 moves in the vertical direction by the sum of these gaps g. A circular hole 16 of the trunnion 8 is formed in an ellipse 16b, and when its major axis direction coincides with the tilt axis direction A, that is, the outer ring of the needle bearing 15 and the trunnion 8
If there is a gap g in the tilt axis direction A of the circular hole 16, the amount of movement in the vertical direction will further increase as shown in FIG.

In such a case, the following problems occur.

When the speed ratio of the toroidal type continuously variable transmission is fixed (without issuing a shift command) and a load is gradually applied, a shift command is issued under the influence of the gap g, elastic deformation and the like. Despite the absence, the toroidal type continuously variable transmission shifts. In this test, since the load was gradually applied, it is considered that the influence of inertia and the like was eliminated as much as possible.
The gear ratio is approximately 1 and the number of rotations is constant at about 2000 rotations, and the oil temperature and the like are controlled at a temperature close to that of actual vehicle running.

When the tilt angle ト ラ of the trunnion 8 is actually measured under such test conditions, the result is as shown in FIG. FIG.
The vertical axis indicates the actual measurement value of the tilt angle ト ラ of the trunnion 8 (that is, the power roller 10), which is set to be 0 degree when the gear ratio is 1: 1. A positive value indicates that the vehicle is tilting to the deceleration side. The abscissa indicates the torque, and the tilt angle ψ first tilts to the deceleration side as the torque increases, and changes to the speed increasing side at 50 Nm or more.

In other words, the vehicle is once stabilized to the deceleration side and then stabilized (slightly increased to the speed increasing side). This test is performed with two rollers having a double cavity. Therefore, the tilt angles の of the four trunnions 8 are measured. Although the tilt angles の of the four trunnions 8 are set such that the initial value is set to zero, only one of the four trunnions 8 has a tilt angle different from the other as shown in F (O N at 200 Nm). . 3 degrees).

[0015] As shown in FIG.
When the zero moves in the vertical direction, side slip occurs in the toroidal type continuously variable transmission, and the power roller 10 shifts. The shift in the low torque region is the sum of these gaps and the like. This is a result of the power roller 10 moving up and down by an amount and tilting. If there is a gap g between the outer ring of the needle bearing 15 and the circular hole 16 of the trunnion 8, this gap g is further added to the amount of vertical movement of the power roller 10. Therefore, the toroidal type continuously variable transmission further shifts in the low torque region.

Conventionally, when the trunnion 8 is strongly clamped so as to withstand drilling, the trunnion 8 is processed into an elliptical shape due to elastic deformation, and furthermore, a clamping method at the time of processing the circular hole 16 of the trunnion 8 has not been considered. An ellipse was formed in the tilt axis direction A. Since the processing of the major axis of the ellipse naturally varies, the outer ring of the needle bearing 15 of the four trunnions 8 and the trunnion 8
In the gap g with the circular hole 16, there was variation. Therefore,
A difference occurs in the amount of vertical movement of each power roller 10,
The degree to which each power roller 10 shifts, that is, the tilt angle ψ
Also makes a difference.

The toroidal type continuously variable transmission used in the test of FIG. 7 is disassembled after the experiment, and the amount of the gap in the tilt axis direction A is measured. The gap g was large. Incidentally, even if it is large, it is a measurement result for a very small gap.

As described above, it is impossible to equalize the gap g with the major axis of the ellipse in the tilting axis direction A in all the trunnions 8, so that the situation where the tilting angles ψ do not match cannot be avoided. . If the tilt angles 不 do not match, there is a problem that the transmission efficiency of the toroidal-type continuously variable transmission deteriorates. In addition, the major axis of the ellipse and the needle bearing 1
If the outer ring of No. 5 is fitted without a gap g, there is an adverse effect that the life of the power roller bearing 15 is shortened by wear powder.

The present invention has been made in view of the above circumstances, and an object thereof is to fit the outer ring of the needle bearing and the circular hole of the trunnion in the direction of the tilt axis of the trunnion without any gap. It is an object of the present invention to provide a toroidal-type continuously variable transmission and a method of boring a trunnion.

[0020]

In order to achieve the above object, according to the present invention, a power roller is supported by a pivot shaft which is arranged between an input disk and an output disk. In the toroidal type continuously variable transmission fixed to the trunnion hole via the solid needle bearing, the outer ring of the solid needle bearing and the trunnion hole are fitted without looseness in the tilt axis direction of the trunnion. It is characterized by the following.

According to a second aspect of the present invention, the hole of the trunnion for fitting the outer ring of the solid needle bearing according to the first aspect has a diameter X in the tilt axis direction of the hole and a diameter in a direction perpendicular to the tilt axis. When Y, X <Y.

According to a third aspect of the invention, there is provided a toroidal stepless step which is disposed between the input disk and the output disk, supports the power roller with a pivot shaft, and fixes the pivot shaft to a trunnion hole via a solid needle bearing. In the method for boring a trunnion in a transmission, the trunnion having a bag portion in which the power roller is housed,
The hole is machined in a state where the bag portion is elastically deformed in a direction of expanding along the tilt axis of the trunnion, and the outer ring of the solid needle bearing and the hole of the trunnion are fitted in the tilt axis direction of the trunnion. Are fitted without any gap.

According to a fourth aspect of the present invention, after the hole of the trunnion of the third aspect is machined, the inner surface thereof is finished.

The trunnion hole has an elliptical shape even though it is machined to a perfect circle by a clamping method. Regarding this elliptical shape, in the hole on the side where the power roller is assembled, the diameter (B) in the direction perpendicular to the tilt axis is larger than the diameter (A) in the direction of the tilt axis. The tilt angles of the book trunnions can be matched. That is, in order to assemble the power roller into the trunnion, the power roller is assembled from the bag portion side of the trunnion. Therefore, in the hole on the side where the power roller is assembled, the diameter in the direction of the tilt axis (A) is smaller than the diameter in the tilt axis direction (A). It is important that the diameter (B) is an elliptical shape having a larger diameter. Incidentally, the specific dimensional difference of the elliptical shape is about 50 μm or less in a major axis−a minor axis.

According to the above construction, the minor axis direction of the ellipse, which is the hole of the trunnion, coincides with the direction of the tilt axis of the trunnion, so that the gap between the hole of the trunnion and the outer ring of the needle bearing in the direction of the tilt axis. When the outer ring of the solid needle bearing and the hole of the trunnion are fitted without play, a toroidal-type continuously variable transmission with high efficiency can be obtained.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a method of clamping a trunnion at the time of machining a circular hole for supporting a solid needle bearing on the back of a trunnion of a toroidal type continuously variable transmission. The structure of the trunnion 8 is basically the same as that of the prior art. Therefore, the same components are denoted by the same reference numerals and description thereof will be omitted.

As shown in FIGS. 1A and 1B, two places 8A and 8B on the back of the trunnion 8 and four places 8 on the pivot 7 are provided.
When C, 8D, 8E and 8F are respectively clamped in the direction of the arrow, the trunnion 8 is elastically deformed as shown in FIG. That is, the trunnion 8 having the bag portion 8a in which the power roller 10 is stored is elastically deformed in a direction in which the bag portion 8a is expanded along the tilt axis direction A of the trunnion 8. In this state, a hole is formed in the straight circular hole 16 supporting the solid needle bearing 15 on the back surface of the trunnion 8 as shown by an arrow a.

After processing, when the clamp is removed, the trunnion 8 is elastically restored as shown in FIG. 2A, and the circular hole 16 is viewed from the side where the power roller 10 is incorporated as shown in FIG. 2B. And an ellipse 16b with respect to an ideal perfect circle 16a. As a result, the minor axis of the ellipse 16b matches the tilt axis direction A, and there is no gap in the tilt axis direction A.

Accordingly, the traction force B acts on the power roller 10, and the trunnion 8 receives the force of the hydraulic pressure of the piston, so that even if the trunnion 8 becomes as shown in FIG. The effect of the gap between the solid needle bearing 15 and the circular hole 16 of the trunnion 10 is eliminated. In this case, there is a gap g in the direction perpendicular to the tilt axis direction A due to the major axis of the ellipse 16b of the circular hole 16.

A test (similar to FIG. 7) in which the speed ratio of the toroidal-type continuously variable transmission is fixed (without issuing a speed change command) and a load is gradually applied using the trunnion 8 having the hole drilled as described above. In this case, the result as shown in FIG. 4 was obtained. As shown in the test results, the minor axis direction of the ellipse 16b, which is the circular hole 16 of the trunnion 8, is set to be the same as the tilt axis direction A of the trunnion 8, and the circular hole 1 of the trunnion 8 in the tilt axis direction A is set.
By eliminating the gap between the inner ring 6 and the outer ring of the solid needle bearing 15, the tilt angles の of all the trunnions 8 match. The efficiency was compared by about 1% when there was a gap and when there was no gap, that is, when the major axis and the minor axis of the ellipse 16b coincided with the tilt axis direction A, respectively.

That is, when the minor axis of the ellipse 16b and the tilting axis direction A are made to coincide with each other, and the outer ring of the solid needle bearing 15 and the circular hole 16 of the trunnion 8 are fitted without gaps, the efficiency is high. A toroidal type continuously variable transmission can be obtained. This means that if the tilt angles ψ
It is considered that the slip ratio and the like at the contact point of the power roller 10 fixed to the trunnion 8 showing the inconsistency are different, and heat is generated to lower the transmission efficiency. Conversely, if the minor axis direction is aligned with the tilt axis direction A and the gap in the tilt axis direction A is eliminated, there is no variation in the amount of movement in the vertical direction. Since the conditions at certain contact points are the same and the slip rates match, an efficient toroidal-type continuously variable transmission can be obtained. Further, since there is no gap between the outer ring of the solid needle bearing 15 and the circular hole 16 of the trunnion 8, the amount of movement of the power roller 10 in the vertical direction is reduced as shown in FIG. That is, the amount of change in the tilt angle ψ can be reduced. As a result, the gear ratio fluctuation of the toroidal type continuously variable transmission can be reduced even when the torque of the engine brake or the like fluctuates, and the control can be easily performed. In a toroidal-type continuously variable transmission (a so-called power split system or geared neutral system) having two modes, a mode in which power flows only to the transmission mechanism and a mode having two power transmission paths, a mode is provided in a toroidal portion which is a transmission mechanism. At the time of change, a large torque fluctuation occurs from the positive torque to the negative torque (or vice versa). Therefore, it is very important to reduce the degree of shift in response to torque fluctuations in order to suppress shift shock, and the present invention is very effective. The power split is described in, for example, JP-A-10-196759.

The ellipse 16 of the circular hole 16 of the trunnion 8
b, when the major axis direction and the tilt axis direction A match,
When the fitting is performed such that the gap in the tilt axis direction A is eliminated, the fitting allowance increases on the short diameter side. When the solid needle bearing 15 is fitted into the circular hole 16 of the trunnion 8, press-fitting is required, and abrasion powder is generated. Then, the abrasion powder due to the press-fitting enters the lubricating oil passage to the power roller 10. Due to the influence of the abrasion powder, sufficient lubricating oil cannot be obtained, lubrication to the power roller bearing 15 cannot be ensured, and durability such as occurrence of seizure may be reduced. It is not possible to eliminate the gap and increase the fitting allowance on the short diameter side.

In the first embodiment, a case has been described in which the finishing of the circular hole 16 of the trunnion 8 is not performed. However, it is more preferable to perform the finishing after the hole processing. In the case of this finishing work, the clamp may be light, so that no elastic deformation of the trunnion 8 occurs. Therefore,
The tilt angles 確 実 of the four trunnions 8 can be surely matched.

Specifically, by performing honing or reaming as a finishing process, a hole having a shape close to a perfect circle is obtained, so that the fitting margin is zero or slightly tight, and the solid needle bearing 15 and the trunnion The eight circular holes 16 have no variation due to the four trunnions 8, and the tilt angles ψ coincide. As a result, a highly efficient toroidal-type continuously variable transmission can be obtained.
The tilt angles の of the four power rollers 10 are matched, the slip ratios of the power transmission points are made uniform, and the contact state is made the same. In other words, in order to make the amount of vertical movement uniform, this needle bearing 1
In addition to making the gap between the outer ring 5 and the circular hole 16 of the trunnion 8 play, it is important to make the sum of the gap amounts in all the bearings uniform.

Although the above description has been made with respect to a double-cavity two-roller, a single-cavity or three-roller can of course be applied.

[0037]

As described above, according to the present invention, the minor axis direction of the ellipse, which is the circular hole of the trunnion, coincides with the direction of the tilt axis of the trunnion, so that the circular hole of the trunnion in the direction of the tilt axis. The gap between the power roller and the outer ring of the solid needle bearing can be eliminated, and there is no variation in the amount of vertical movement of the power roller. There is an effect that an efficient toroidal-type continuously variable transmission can be obtained because they match.

[Brief description of the drawings]

FIG. 1 shows a method of clamping a trunnion when machining a circular hole on the back surface of a trunnion in a toroidal type continuously variable transmission according to a first embodiment of the present invention, where (a) is a longitudinal side view and (b) Is a plan view.

FIGS. 2A and 2B show the same embodiment, in which FIG. 2A is a longitudinal sectional side view of a trunnion, and FIG.

FIG. 3 is a longitudinal side view of the trunnion with a power roller incorporated therein, showing the same embodiment;

FIG. 4 is a graph showing a relationship between a torque and a tilt angle of a trunnion.

FIG. 5 is a longitudinal sectional side view showing a variator section of a conventional toroidal type continuously variable transmission.

FIG. 6 (a) is a longitudinal side view of a conventional trunnion,
(B) is a front view showing a circular hole.

FIG. 7 is a graph showing the relationship between torque and trunnion tilt angle.

[Explanation of symbols]

 Reference numeral 2: input disk 3: output disk 8: trunnion 8a: bag 10: power roller 15: solid needle bearing 16: circular hole

Claims (4)

[Claims] 1. A toroidal type continuously variable transmission which is arranged between an input disk and an output disk, supports a power roller by a pivot shaft, and fixes the pivot shaft to a hole of a trunnion via a solid needle bearing. A toroidal-type continuously variable transmission, wherein an outer ring of the solid needle bearing and a hole of the trunnion are fitted without looseness in a direction of a tilt axis of the trunnion. 2. A trunnion hole for fitting the outer ring of the solid needle bearing, wherein X is a diameter in a tilt axis direction and Y is a diameter in a direction perpendicular to the tilt axis. Y
The toroidal-type continuously variable transmission according to claim 1, wherein 3. A toroidal-type continuously variable transmission which is disposed between an input disk and an output disk, supports a power roller by a pivot shaft, and fixes the pivot shaft to a trunnion hole through a solid needle bearing. In the trunnion hole forming method, the trunnion having a bag portion in which the power roller is stored, the hole is formed in a state where the bag portion is elastically deformed in a direction of expanding along the tilting axis of the trunnion, A hole forming method for a trunnion in a toroidal-type continuously variable transmission, wherein the fitting of the outer ring of the solid needle bearing and the hole of the trunnion in the direction of the tilt axis of the trunnion is fitted without any gap. 4. The method for drilling a trunnion in a toroidal-type continuously variable transmission according to claim 3, further comprising finishing the inner surface of the trunnion after drilling the hole of the trunnion.