JP2005172068A - Toroidal continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toroidal continuously variable transmission having good power transmitting performance without causing the deformation of a retainer or the backlash of rollers. <P>SOLUTION: A loading cam device 11 for transmitting the rotating torque of an input shaft 2 to an input side disc 5a consists of a cam plate 12 fixed to the end of the input shaft 2, a first cam face 13 formed on the input side disc 5a in opposition to the cam plate 12, a second cam face 14 formed on the cam plate 12 in opposition to the first cam plate 13, the plurality of rollers 15 arranged between the second cam face 14 and the first cam face 13, and the retainer 16 for rotatably retaining the rollers 15 in the circumferential direction of the input side disc 5a. The retainer 16 is formed of carburized steel or carbonitrided steel, with its surface carbon concentration being 0.9-1.2 wt%. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a toroidal-type continuously variable transmission used, for example, as a transmission for an automobile.

  In recent years, a double-cavity toroidal continuously variable transmission as shown in FIG. 7 has been developed as a continuously variable transmission used in an automobile. The toroidal continuously variable transmission 1 includes an input shaft 2 connected to a drive source such as an engine, and a power transmission shaft 4 connected to the input shaft 2 through a spline 3 so as to be movable in the axial direction. The input side disks 5a and 5b are rotatably supported at both ends of the power transmission shaft 4. The toroidal-type continuously variable transmission 1 includes output-side disks 6a and 6b facing the input-side disks 5a and 5b, a hollow rotary shaft 7 that rotates integrally with the output-side disks 6a and 6b, and the hollow rotation Gears 8a and 8b for transmitting the rotation of the shaft 7 to the counter shaft 9 are provided. Between the input side disks 5a and 5b and the output side disks 6a and 6b, a plurality of power rollers 10 for adjusting the speed ratio are provided. It is sandwiched so that it can tilt. Furthermore, the toroidal continuously variable transmission 1 includes a loading cam device 11 that transmits the rotational torque of the input shaft 2 to the input side disk 5a. The loading cam device 11 is a cam fixed to the end of the input shaft 2. A plate 12, a first cam surface 13 formed on the input side disk 5 a so as to face the cam plate 12, and a second cam formed on the cam plate 12 so as to face the first cam surface 13 And a plurality of rollers 15 disposed between the second cam surface 14 and the first cam surface 13, and these rollers 15 are rotatably held in the circumferential direction of the input side disk 5a. The retainer 16 is configured.

When such a toroidal continuously variable transmission is used as a transmission for an automobile, the rotational speed of each component constituting the loading cam device is often suddenly changed in order to cope with a sudden change in the running state. . In this case, if the inertial mass of each component constituting the loading cam device is large, it is difficult to change the rotation speed rapidly, and the power transmission by the toroidal continuously variable transmission is difficult to be performed smoothly. Therefore, in order to solve such a problem, it has been proposed to provide a cut portion in a portion of the retainer that is removed from the pocket portion (see Patent Document 1) or to mold the retainer with a synthetic resin (patent). Reference 2).
Japanese Utility Model Publication No. 5-3714 Japanese Utility Model Publication No. 6-14602

However, if a cut-out part is provided in the part of the retainer that is out of the pocket, or if the retainer is molded of synthetic resin, the retainer will be weakened, and the retainer will be deformed by its own weight or the weight of the roller during high-speed rotation. There is a possibility that. In addition, there is a problem that the pocket portion of the retainer is easily worn by contact with the roller, and the backlash of the roller is generated in the pocket portion of the retainer to increase vibration.
The present invention has been made in view of such problems, and provides a toroidal continuously variable transmission that can obtain good power transmission performance without causing deformation of the retainer, rattling of the roller, or the like. Objective.

  In order to achieve the above object, the invention according to claim 1 of the present invention provides a loading cam device for transmitting the rotation of the input shaft to the input side disk, a cam plate fixed to the end of the input shaft, A first cam surface formed on the input side disk facing the cam plate, a second cam surface formed on the cam plate facing the first cam surface, and the second cam A toroidal continuously variable transmission comprising a plurality of rollers disposed between a surface and the first cam surface, and a retainer that rotatably holds these rollers in a circumferential direction of the input side disk; The retainer is made of carburized steel or carbonitrided steel, and the surface carbon concentration of the retainer is 0.9 to 1.2% by weight.

According to a second aspect of the present invention, in the toroidal continuously variable transmission according to the first aspect, the surface nitrogen concentration of the retainer is 0.05 to 0.4% by weight.
In the present invention, the reason for setting the surface carbon concentration of the retainer to 0.9 to 1.2% by weight is as follows.
Since the strength (deformation resistance) of steel used after quenching and tempering is governed by the carbon concentration, if the surface carbon concentration of the retainer is less than 0.9% by weight, the retainer will not be able to support centrifugal force during rotation. Resulting in. On the other hand, if the surface carbon concentration of the retainer exceeds 1.2% by weight, harmful structures such as pro-eutectoid carbides are likely to be generated during heat treatment. Moreover, since the influence of the carbon amount on the strength of the martensite base is saturated when the base carbon amount is about 0.8% by weight, the upper limit of the surface carbon concentration (= base + carbon concentration of carbide) is 1.2% by weight. It was.

In the present invention, the reason why the retainer has a surface nitrogen concentration of 0.05 to 0.4% by weight is as follows.
Since nitrogen greatly affects the wear resistance and toughness of the material, if the retainer surface nitrogen concentration is less than 0.05% by weight, the effect on the wear resistance is not sufficient. On the other hand, when the surface nitrogen concentration of the retainer exceeds 0.4% by weight, the grindability is deteriorated, and the increase in cost cannot be suppressed in order to maintain the accuracy of the product. In addition, the toughness is reduced by the influence of excessively precipitated fine nitride, and anxiety about impact load remains. Therefore, the surface nitrogen concentration of the retainer was set to 0.05 to 0.4% by weight.

According to the toroidal type continuously variable transmission according to the first aspect of the invention, since the mechanical strength of the retainer is increased, it is possible to prevent the retainer from being deformed by its own weight or the weight of the roller during high-speed rotation. .
According to the toroidal type continuously variable transmission according to the second aspect of the invention, the wear resistance of the retainer is improved and wear due to contact with the roller is less likely to occur in the pocket portion of the retainer. It is possible to prevent the rollers from rattling during rotation of the roller.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a view showing a main part of a toroidal type continuously variable transmission according to an embodiment of the present invention. As shown in the figure, the toroidal continuously variable transmission according to one embodiment of the present invention includes a loading cam device 11 that transmits the rotational torque of the input shaft 2 to the input side disk 5a. The cam plate 12 fixed to the end of the input shaft 2, the first cam surface 13 formed on the input side disk 5 a so as to face the cam plate 12, and the first cam surface 13 A second cam surface 14 formed on the cam plate 12, a plurality of rollers 15 arranged between the second cam surface 14 and the first cam surface 13, and these rollers 15 on the input side The retainer 16 is rotatably held in the circumferential direction of the disk 5a.

The retainer 16 is made of carburized steel or carbonitrided steel, and the surface carbon concentration is 0.9 to 1.2% by weight. Further, the surface nitrogen concentration of the retainer 16 is 0.05 to 0.4% by weight.
Thus, when the surface carbon concentration of the retainer 16 made of carburized steel or carbonitrided steel is set to 0.9 to 1.2% by weight, the mechanical strength of the retainer 16 increases. Alternatively, deformation due to the weight of the roller 15 can be prevented. Further, when the surface nitrogen concentration of the retainer 16 is set to 0.05 to 0.4% by weight, the wear resistance of the retainer 16 is improved, and the wear due to contact with the roller 15 causes the pocket portion 17 of the retainer 16 (see FIG. 2). ), The backlash of the roller 15 during the rotation of the retainer 16 can be prevented.
In order to confirm the above-described effect, the present inventor conducted the following experiment. First, test pieces of sample Nos. 1 to 12 shown in Table 1 were produced, and a tensile test was performed using the test pieces of sample Nos. 6 to 12.

  In Table 1, Nos. 1 to 5 are carbonitriding the test piece made of JIS SCM420 under the following carbonitriding conditions to adjust the surface carbon concentration to 1.00 to 1.04% by weight and the surface nitrogen concentration. Is adjusted to 0.05 to 0.50% by weight. Nos. 6 to 12 show test pieces made of JIS SCM420 that were carburized under the following carburizing conditions and the surface carbon concentration was adjusted to 0.59 to 1.28% by weight.

(Carburizing conditions)
Atmospheric gas: Rx gas + enriched gas (CP = 0.6-1.3)
Treatment temperature: selected in the range of 920 to 980 ° C. Treatment time: About 1 to 10 hours depending on the surface carbon concentration Quenching and tempering after carburizing treatment: Available (Quenching (oil cooling) of about 830 to 880 ° C. × 1 hour), 160 to Tempering at 200 ° C for about 2 hours)
(Carbonitriding conditions)
Atmospheric gas: Rx gas + enriched gas + ammonia gas (CP = 0.6-1.3)
Treatment temperature: Select within the range of 830-980 ° C Treatment time: About 1-20 hours depending on the surface carbon concentration and surface nitrogen concentration Quenching and tempering after carbonitriding treatment: Existence (830-880 ° C x 1 hour quenching (oil Cold), tempering at 160-200 ° C. for about 2 hours)

  The test results of the tensile test described above are shown in FIG. In the figure, the horizontal axis represents the surface carbon concentration of each test piece, and the vertical axis represents the case where the test piece of sample No. 9 (surface carbon concentration 0.9% by weight) is normalized with a proof stress of 0.2%. The intensity ratio is shown. Moreover, the broken line in the figure shows the case where the intensity ratio of 0.9% by weight or more is predicted by only the data having a surface carbon concentration of less than 0.9% by weight.

Next, the present inventor made the retainer shown in FIG. 2 from the same steel material as the test pieces of sample Nos. 6 to 11 shown in Table 1, and incorporated this into the loading cam device, and the rotation speed was 10000 min ⁻¹ . Time: A retainer deformation test was performed under the test conditions of 5 hours. Then, after the test, the outer diameter of the portion shown in FIG. 2 was measured, and this was evaluated as the retainer deformation ratio (= the outer diameter after the test / the outer diameter before the test). The evaluation results are shown in FIG.

  As is apparent from the test results shown in FIG. 3, when the surface carbon concentration of the retainer exceeds 0.9% by weight, the difference between the predicted value and the actually measured value increases as the surface carbon concentration increases, and 1.2 wt. Above%, the effect of surface carbon concentration is completely saturated. On the other hand, as is apparent from the test results shown in FIG. 4, when the carbon concentration of the retainer is less than 0.9% by weight, the retainer deformation rate increases rapidly, and deformation due to centrifugal force is likely to occur in the retainer. Therefore, by setting the upper limit of the surface carbon concentration of the retainer to 1.2% by weight and the lower limit to 0.9% by weight, the retainer is prevented from being deformed by its own weight or the weight of the roller during high-speed rotation. I understand that I can do it.

Next, the present inventor produced the retainer shown in FIG. 2 from the same steel material as the test pieces of Sample Nos. 1 to 5 and 9 shown in Table 1, and incorporated this into the loading cam device, and the rotational speed was 6000 min ^−1. Test time: The wear resistance test of the retainer was performed under the test conditions of 6 hours. The test results are shown in FIG. In the figure, the horizontal axis represents the surface nitrogen concentration, and the vertical axis represents No. The wear amount ratio when the wear amount of 9 is 1 is shown.
Moreover, this inventor performed the Charpy impact test based on JISZ2242 using the test piece of sample No.1-5 shown in Table 1, and. The test results are shown in FIG. In the figure, the horizontal axis represents the surface nitrogen concentration, and the vertical axis represents No. 9 shows the impact strength ratio when the impact strength applied to the test piece 9 is 1.

As is apparent from the test results shown in FIG. 5, when the surface nitrogen concentration of the retainer is less than 0.05% by weight, the wear amount ratio increases rapidly. On the other hand, as is apparent from the test results shown in FIG. 6, when the surface nitrogen concentration of the retainer exceeds 0.40% by weight, the impact strength ratio rapidly decreases and the impact resistance of the retainer decreases. Therefore, by setting the lower limit of the surface nitrogen concentration of the retainer to 0.05% by weight and the upper limit to 0.4% by weight, wear due to contact with the roller is less likely to occur in the pocket of the retainer, and the retainer rotates. It can be seen that the backlash of the roller at the time can be prevented.
In the above-described embodiment, the case where the present invention is applied to a double cavity type toroidal continuously variable transmission is illustrated, but the present invention is also applied to a toroidal type continuously variable transmission other than the double cavity type toroidal continuously variable transmission. Of course, it can be applied.

It is a figure which shows the principal part of the toroidal type continuously variable transmission which concerns on one Embodiment of this invention. It is a top view of the retainer shown in FIG. It is a figure which shows the relationship between the surface carbon concentration and intensity | strength of a retainer. It is a figure which shows the relationship between the surface carbon concentration of a retainer, and a deformation rate. It is a figure which shows the relationship between the surface nitrogen concentration of a retainer, and wear amount ratio. It is a figure which shows the relationship between the surface nitrogen concentration of a retainer, and an impact strength ratio. It is a figure which shows schematic structure of a double cavity type toroidal type continuously variable transmission.

Explanation of symbols

2 Input shaft 3 Spline 4 Power transmission shaft 5a, 5b Input side disc 6a, 6b Output side disc 7 Hollow rotary shaft 8a, 8b Gear 9 Counter shaft 10 Power roller 11 Loading cam device 12 Cam plate 13 First cam surface 14 First 2 cam surface 15 Roller 16 Retainer 17 Pocket

Claims (2)

A loading cam device for transmitting the rotational torque of the input shaft to the input side disk, a cam plate fixed to the end of the input shaft, and a first cam surface formed on the input side disk facing the cam plate A second cam surface formed on the cam plate facing the first cam surface, and a plurality of rollers disposed between the second cam surface and the first cam surface In the toroidal continuously variable transmission constituted by a retainer that rotatably holds these rollers in the circumferential direction of the input side disk,
A toroidal continuously variable transmission characterized in that the retainer is made of carburized steel or carbonitrided steel, and the surface carbon concentration of the retainer is 0.9 to 1.2% by weight.   The toroidal continuously variable transmission according to claim 1, wherein the retainer has a surface nitrogen concentration of 0.05 to 0.4 wt%.

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