JP2005172069A - Toroidal continuously variable transmission - Google Patents

Abstract

A toroidal-type continuously variable transmission capable of obtaining good power transmission characteristics without lowering the wear resistance and mechanical strength of a retainer.
A loading cam device (11) for transmitting rotational torque of an input shaft (2) to an input side disk (5a) is fixed to an end of the input shaft (2), and the input side disk (5a) is opposed to the cam plate (12). A first cam surface 13 formed on the cam plate 12, a second cam surface 14 formed on the cam plate 12 so as to face the first cam surface 13, and the second cam surface 14 and the first cam. A plurality of rollers 15 disposed between the surface 13 and a retainer 16 that holds these rollers 15 rotatably in the circumferential direction of the input side disk 5a. The retainer 16 is made of titanium or a titanium alloy having a carbon content of 0.05 to 0.20% by weight and an oxygen content of 0.05 to 0.40% by weight.
[Selection] Figure 1

Description

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

  In recent years, double-cavity toroidal continuously variable transmissions as shown in FIG. 5 have been developed as continuously variable transmissions used in automobiles. 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 may be 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, there has been proposed one in which a retainer of a loading cam device is molded from a synthetic resin to reduce the inertial mass (see Patent Document 1).
Japanese Utility Model Publication No. 6-14602

However, when the retainer is formed of a synthetic resin, there is a problem that the wear resistance and mechanical strength of the retainer are lowered. Further, when the retainer is expanded by the lubricating oil, the gap between the roller and the retainer becomes too small, and the retainer may be abnormally worn.
The present invention has been made paying attention to such problems, and provides a toroidal continuously variable transmission capable of obtaining good power transmission characteristics without deteriorating the wear resistance and mechanical strength of the retainer. The purpose is to do.

  In order to achieve the above object, the present invention provides a loading cam device for transmitting a rotational torque of an input shaft to an input side disk, a cam plate fixed to an end portion of the input shaft, and the cam plate. A first cam surface formed on the input-side disk; a second cam surface formed on the cam plate opposite the first cam surface; the second cam surface and the first cam surface; A toroidal continuously variable transmission comprising a plurality of rollers arranged between the cam surface and a retainer that rotatably holds these rollers in the circumferential direction of the input side disk. It is formed from a titanium alloy.

  In the toroidal continuously variable transmission according to the present invention, the carbon content of the retainer is preferably in the range of 0.05 wt% to 0.2 wt%. Moreover, it is preferable that the oxygen content of a retainer exists in the range of 0.05 weight%-0.4 weight%. Furthermore, it is preferable that the retainer is formed by injection-molding metal powder together with a binder and then sintering the metal powder. Moreover, it is preferable that the average diameter of the micropores formed on the surface of the retainer when the metal powder is sintered is in the range of 2 μm to 30 μm. Furthermore, it is preferable that the area ratio of the micropores formed on the surface of the retainer when the metal powder is sintered is in the range of 2% to 10%.

  According to the toroidal type continuously variable transmission according to the present invention, since the retainer is formed of titanium or a titanium alloy, the inertial mass of the retainer can be reduced without molding the retainer with synthetic resin. Good power transmission characteristics can be obtained without degrading the properties and mechanical strength.

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 formed in a disc shape, and a plurality of pocket portions 17 (see FIG. 2) for holding the roller 15 are formed at equal intervals in the circumferential direction of the retainer 16. . The retainer 16 is made of titanium or a titanium alloy, and the carbon content of the retainer 16 is set in a range of 0.05 wt% to 0.20 wt%. Further, the retainer 16 is formed by injection-molding a metal powder such as a titanium powder or a composition element powder of a titanium alloy together with a binder and then sintering the metal powder. That is, the retainer 16 is molded using a metal powder injection molding method, and the oxygen content of the retainer 16 is set in the range of 0.05 wt% to 0.40 wt%.

  As the titanium powder, gas atomized powder, hydrogenated-dehydrogenated (HDH) powder, or the like can be used. In addition, as a method for obtaining a titanium alloy by the metal powder injection molding method described above, there are a method using an alloy powder and a method using a composition element powder of a titanium alloy (elementary powder mixing method). In this method, since the cost of the alloy powder is high, it is desirable to use the elementary powder mixing method, and there is an advantage that an arbitrary alloy composition can be obtained.

Since, as described above, by forming the retainer 16 of titanium or a titanium alloy, the density of titanium (about 4.5 kg / mm ³⁾ are in the order of about 60% steel (about 7.8 kg / mm ^3), About 40% of the weight can be reduced compared to the retainer made of steel. Therefore, in the above-described embodiment, the inertia mass of the retainer 16 can be reduced without molding the retainer 16 with a synthetic resin, and the followability when the rotational speed or rotational torque of the input shaft 2 fluctuates can be improved. Good power transmission characteristics can be obtained without reducing the wear resistance and mechanical strength of the retainer 16. Further, since there is no volume expansion due to the lubricant as in the case where the retainer 16 is made of synthetic resin, it is possible to prevent abnormal wear from occurring in the pocket portion 17 of the retainer 16 due to contact with the roller 15.

  In this case, when the carbon content of the retainer 16 exceeds 0.20% by weight, the ductility of the retainer 16 is rapidly lowered as shown in FIG. On the other hand, when the carbon content of the retainer 16 is less than 0.05% by weight, the amount of increase in the hardness of the retainer 16 becomes too small as shown in FIG. Therefore, when the retainer 16 is formed from titanium or a titanium alloy, it is preferable to set the carbon content of the retainer 16 within a range of 0.05 wt% to 0.20 wt%.

Further, when the oxygen content of the retainer 16 exceeds 0.40% by weight, the elongation (ductility) of the retainer 16 is rapidly lowered as shown in FIG. On the other hand, when the oxygen content of the retainer 16 is less than 0.05% by weight, the amount of increase in the hardness of the retainer 16 becomes too small as shown in FIG. Therefore, when the retainer 16 is formed from titanium or a titanium alloy, it is preferable to set the oxygen content of the retainer 16 within a range of 0.05 wt% to 0.40 wt%.
2 and 3 perform a tensile test using the test pieces (test pieces using pure titanium powder as the metal powder for injection molding) indicated by numbers 1 to 19 in Table 1, and determine the elongation of each test piece. The result of measuring the amount of increase in hardness is shown.

  In the embodiment described above, a metal powder such as a titanium powder or a titanium alloy composition element powder is injection molded together with a binder, and then the retainer 16 is formed by sintering the metal powder. Since minute pores are formed and the lubricant can be held in the minute pores, seizure can be prevented from occurring in the contact portion between the pocket portion 17 of the retainer 16 and the roller 15. In addition, when manufacturing titanium by a melting method, not only a special melting method has to be used, but there is a concern about an increase in cost, but the metal powder injection molding method can perform near-net shape molding, Since the cutting process can be reduced and the yield of the material is improved, the cost as a product can be reduced. Furthermore, since titanium has a bcc (body-centered cubic lattice) structure with a low self-diffusion coefficient at high temperatures, it has excellent sinterability and is densified by sintering at 1100 ° C or higher. It becomes 98% or more. Moreover, since it densifies by a short time sintering, it can be used conveniently for a metal powder injection molding method.

  In this case, when the average diameter of the micropores exceeds 30 μm, the deformation due to the concentration of contact stress increases as shown in Table 2. On the other hand, when the average diameter of the micropores is less than 2 μm, the amount of lubricant that can be held in one pore is reduced, and as shown in Table 2, the wear resistance and seizure resistance of the retainer 16 are lowered. Therefore, when the retainer 16 is molded by the metal powder injection molding method, it is preferable to set the average diameter of the micropores formed on the surface of the retainer 16 within a range of 2 μm to 30 μm.

  If the area ratio of the micropores exceeds 10%, the individual pores are connected independently and do not function as a lubricant reservoir. Therefore, as shown in Table 2, the pocket portion of the retainer 16 The contact portion between the roller 17 and the roller 15 is easily worn. On the other hand, if the area ratio of the micropores is less than 2%, the number of micropores is insufficient, and the retainer 16 is easily worn as shown in Table 2. Therefore, when the retainer 16 is molded by a metal powder injection molding method, it is preferable to set the area ratio of micropores formed on the surface of the retainer 16 within a range of 2% to 10%.

Table 2 shows the durability test of the toroidal-type continuously variable transmission shown in FIG. 1 under the test conditions of a rotational speed of 6000 min ⁻¹ and a test time of 10 hours using a plurality of retainers having different average pore diameters and area ratios. The test results are shown.
In the above-described embodiment, the case where the present invention is applied to a double-cavity toroidal continuously variable transmission is shown. However, the present invention is not limited to this, and a toroidal-type continuously variable transmission other than the double-cavity type is described. Of course, it is applicable.

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 carbon content of a test piece made from titanium, elongation, and the amount of hardness increase. It is a figure which shows the relationship between oxygen content of a test piece made from titanium, elongation, and the amount of hardness increase. 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 (6)

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, wherein the retainer is made of titanium or a titanium alloy.   The toroidal continuously variable transmission according to claim 1, wherein the retainer has a carbon content set in a range of 0.05 wt% to 0.2 wt%.   The toroidal type continuously variable transmission according to claim 1 or 2, wherein the oxygen content of the retainer is set within a range of 0.05 wt% to 0.4 wt%. .   The toroidal continuously variable transmission according to any one of claims 1 to 3, wherein the retainer is formed by injection molding metal powder together with a binder and then sintering the metal powder.   5. The toroidal continuously variable transmission according to claim 4, wherein an average diameter of micropores formed on the surface of the retainer when the metal powder is sintered is set in a range of 2 to 30 [mu] m.   6. The toroidal stepless device according to claim 4 or 5, wherein an area ratio of micropores formed on the surface of the retainer when the metal powder is sintered is set in a range of 2% to 10%. transmission.

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