Patent Application
20050187065
The present invention claims foreign priority to Japanese patent application no. P. 2004-047835, filed on Feb. 24, 2004, the contents of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a manufacturing method for a variator part of a toroidal-type continuously variable transmission utilized as a transmission of an automobile part or a transmission of an industrial machine or the like, a variator part of a toroidal-type continuously variable transmission and a toroidal-type continuously variable transmission.
2. Description of the Related Art
In recent years, there has been researched to use a toroidal-type continuously variable transmission as a transmission for an automobile (refer to, for example, Japanese Patent Unexamined Publication No. JP-A-11-51140). As shown in
A cam plate 6 is provided to engage with the input shaft 2 by a spline on a back face side of the input disk 3. Further, a roller 7 is interposed between the cam plate 6 and the input disk 3 to constitute a pressing apparatus 8 of a loading cam type for pressing the input disk 3 to a side of the output disk 4.
A trunnion 10 swung centering on a pivot shaft 9 along a direction substantially orthogonal to center axes of the input disk 3 and the output disk 4 is provided between the input disk 3 and the output disk 4. The trunnion 10 is arranged with a displacement shaft 11 extended in a direction substantially orthogonal to the pivot shaft 9 substantially at a center thereof and the power roller 5 is rotatably supported by the displacement shaft 11.
According to the above-described toroidal-type continuously variable transmission 1, rotation of the input shaft 2 is transmitted to the input disk 3 via the pressing apparatus 8. Further, rotation of the input disk 3 is transmitted to the output disk 4 via the power roller 5, further, rotation of the output disk 4 is outputted by an output gear 12 coupled to the output disk 4 by a key. By changing an inclination angle of the power roller 5 by displacing the trunnion 10, the power roller 5 changes positions of being brought into contact with the input disk 3 and the output disk 4, and a desired rotational speed ratio (transmission ratio) is continuously provided between the input shaft 2 and the output gear 12.
As shown in
Further, there are provided a thrust ball bearing 18 for supporting a thrust load applied to the power roller 5 and a thrust needle roller bearing 20 for supporting a thrust load applied to an outer ring 19 constituting the thrust ball bearing 18 in this order from a side of an outer side face of the power roller 5 between the outer side face of the power roller 5 and an inner side face of the middle portion of the trunnion 10. The thrust ball bearing 18 allows the power roller 5 to rotate while supporting the thrust load applied to the power roller 5. Further, the thrust needle roller bearing 20 allows the support shaft portion 15 and the outer ring 19 to swing centering on the support shaft portion 14 while supporting the thrust load applied from the power roller 5 to the outer ring 19.
Therefore, a high face pressure by relative rotational movement which is carried out between a ring-like raceway groove 5a of the outer side face of the power roller 5 constituting an inner ring of the thrust ball bearing 18 and a ring-like raceway groove 19a of the outer ring 19 via a ball 21 is generated at the ring-like raceway groove 19a of the outer ring 19 and a repeated stress is generated at the ring-like raceway groove 19a. Therefore, it is known to form a metal flow along the raceway groove 19a at the ring-like raceway groove 19a of the outer ring 19 of the thrust ball bearing 18 (refer to, for example, U.S. Pat. No. 6,196,946).
According to a manufacturing method described in U.S. Pat. No. 6,196,946, a disk-like material an outer diameter of which is widened is constituted by press-forging a solid cylindrical material a metal flow of which is extended in an axial direction and the metal flow at a surface is extended in an outer peripheral direction. Further, as shown in
Further, there is known a structure of promoting a speed changing characteristic by restraining an inclination of the displacement shaft 11 by constraining the displacement shaft 11 by the outer ring 19 of the thrust ball bearing 18 by integrally forming the displacement shaft 11 with the outer ring 19 of the thrust ball bearing 18 (refer to, for example, U.S. Pat. No. 6,152,850 and Japanese Patent Unexamined Publication No. JP-A-2002-181151). According to the toroidal-type continuously variable transmission described in JP-A-2002-181151. As shown in
Meanwhile, in a related art, in fabricating the variator part 30 integrated in this way, as shown in
Further, it is known that according to the forging material W formed coaxially as shown in
The present invention has been carried out in view of the above-described problem and an object thereof is to provide a manufacturing method for a variator part of a toroidal-type continuously variable transmission in which a displacement shaft and an outer ring of a thrust rolling bearing are integrated at low cost by restraining an increase in fabrication cost by improving yield of a material and shorting machining time while increasing a strength thereof, a variator part of a toroidal-type continuously variable transmission and a toroidal-type continuously variable transmission.
According to a first aspect of the present invention, there is provided a manufacturing method for a variator part of a toroidal-type continuously variable transmission, the toroidal-type continuously variable transmission comprising:
input and output disks;
a trunnion;
a power roller;
a displacement shaft including:
a thrust rolling bearing including an outer ring on which an outer ring raceway is formed, the thrust rolling bearing supporting a thrust load of the power roller while allowing the power roller to rotate,
wherein the variator part is integrally formed with the displacement shaft and the outer ring of the thrust rolling bearing,
the manufacturing method comprising the steps of:
a first step of preparing a lower die including a first hole portion for forming the pivot shaft portion and a ring-like projected portion for forming the outer ring raceway of the outer ring, wherein center lines of the first hole portion and the ring-like projected portion coincide with each other, and an upper die including a second hole portion for forming the support shaft portion, wherein a center line of the second hole portion is eccentric from the center line of the first hole portion by a predetermined value;
a second step of mounting a solid material on the lower die so that a center line of the solid material coincides with the center line of the ring-like projected portion; and
a third step of simultaneously forming the support shaft portion, the outer ring having the outer ring raceway and the pivot shaft portion by pressing the upper die and the lower die so as to approach each other.
According to a second aspect of the present invention as set forth in the first aspect of the present invention, it is preferable that the solid material is formed by forging a cylindrical solid material having a diameter smaller than an inner diameter of the outer ring raceway before the third step.
According to a third aspect of the present invention as set forth in the first aspect of the present invention, it is more preferable that the upper die is pressed to the lower die at the third step.
According to a fourth aspect of the present invention as set forth in the first aspect of the present invention, it is furthermore preferable that the manufacturing method for the variator part of the toroidal-type continuously variable transmission comprising a step of:
a fourth step of machining a finishing margin formed around the variator part in a substantially same shape of the variator part.
According to a fifth aspect of the present invention, there is provide a variator part of a toroidal-type continuously variable transmission, the toroidal-type continuously variable transmission comprising:
an input disk and an output disk;
a trunnion;
a power roller;
a displacement shaft including:
a thrust rolling bearing including an outer ring on which a outer ring raceway is formed, the thrust rolling bearing supporting a thrust load of the power roller while allowing the power roller to rotate;
wherein the variator part is integrally formed with the displacement shaft and the outer ring of the thrust rolling bearing,
wherein the variator part is formed such that
a solid material is mounted on a lower die such that a center line of the solid material coincides with a center line of a ring-like projected portion of a lower die; and
the support shaft portion, the outer ring having the outer ring raceway and the pivot shaft portion of the variator part are simultaneously formed of the solid material by pressing an upper die and the lower die so as to approach each other,
wherein metal flows extends along with the outer ring raceway and a surface of a root portion of the support shaft portion of the displacement shaft.
According to a sixth aspect of the present invention as set forth in the fifth aspect of the present invention, it is suitable that an end of the metal flow is disposed on a side surface of the support shaft portion of the displacement shaft.
According to a seventh aspect of the present invention, there is provided a toroidal-type continuously variable transmission, comprising:
a variator part according to the fifth aspect of the present invention; and
an input and output disks rotatably supported so as to be mutually independent.
According to an eighth aspect of the present invention there is provided a toroidal-type continuously variable transmission, comprising:
input and output disks, which are rotatably supported so as to be mutually independent and have inner surfaces thereof;
a trunnion having a pivot shaft disposed in a direction perpendicular to a center axis of the input and output disks, the trunnion swinging on the pivot shaft;
a displacement shaft including:
a plurality of power rollers pinched between the inner surfaces of the input and output disks and rotatably supported on the pivot shaft portion; and
a thrust rolling bearing provided between an outer surface of the power roller and the inner surface of the trunnion, the thrust rolling bearing including:
wherein the displacement shaft and the outer ring of the thrust rolling bearing are integrated and
metal flows extends along with the outer ring raceway and a surface of a root portion of the support shaft portion of the displacement shaft.
Note that the metal flow means stream line which is generated in metal when the metal is flowed in pressurized such as forging.
According to the manufacturing method for a variator part of a toroidal-type continuously variable transmission of the present invention, the support shaft portion formed on an side opposed to the outer ring raceway of the outer ring is forged by the second hole portion of the upper die having the center line at the position eccentric from the center line of the lower die by the predetermined amount. Therefore, the forging material along a desired product shape can be provided. Thereby, a machining margin in turning the support shaft portion can be made to be necessary minimum and machining time can be shortened.
Further, by forging as described above, at a root portion of the support shaft portion disposed in a direction in which the support shaft portion is eccentric to the pivot shaft portion, a metal flow is formed along a surface thereof. Therefore, even when a stress is applied to the support shaft portion by deforming the outer ring, a strength of the root portion of the support shaft portion can be prevented from being reduced.
Further, forging is carried out by making an outer diameter of the solid material smaller than the inner diameter of the ring-like raceway groove and making the center line of the solid material coincide with the centerline of the ring-like projected portion forming the outer ring raceway of the outer ring of the solid material. Accordingly, an end flow of an end face of the solid material is not extruded into the outer ring raceway of the outer ring and a metal flow along a surface of the outer ring raceway can be provided. Therefore, even when a repeated stress is operated by relative rotational movement of the thrust ball bearing, the stress can be prevented from being reduced at the outer ring raceway.
Further, according to the toroidal-type continuously variable transmission of the present invention, the displacement shaft and the outer ring of the thrust rolling bearing are integrated, metal flows at the outer ring raceway of the outer ring and the root portion of the support shaft portion are extended along surfaces thereof. Accordingly, even when the repeated stress is operated by the relative rotational movement of the thrust ball bearing, the strength can be prevented from being reduced at the outer ring raceway and even when the stress is operated at the support shaft portion by deforming the outer ring, the strength can be prevented from being reduced at the root portion of the support shaft portion.
A manufacturing method for a variator part of a toroidal-type continuously variable transmission, a variator part of a toroidal-type continuously variable transmission and a toroidal-type continuously variable transmission according to the present invention will be explained in details in reference to the drawings as follows. Further a characteristic of the present invention resides in a manufacturing method for a variator part in which a displacement shaft and an outer ring of a thrust rolling bearing are integrated and the variator part. The other structure and operation are similar to those of a toroidal-type continuously variable transmission which has been known in a related art including the above-described structure of the related art. Therefore, an explanation will be omitted or simplified with regard to portions equivalent to those of the structure of the related art and an explanation will be given centering on a characteristic portion of the present invention.
A variator part 40 according to the embodiment of the present invention is integrally formed with a displacement shaft 43 having a support shaft portion 41 swingably supported by the trunnion 10 (refer to
Next, a manufacturing method for the variator part 40 constituted in this way will be explained in reference to
First, as shown in
Next, the solid material W0 cut as described above is heated to a temperature suitable for forging. Further, as shown in
Next, as shown in
Further, final finish forging is carried out by a finish die as shown in
By inserting a portion of a solid material W2 having the outer diameter φd2 extruded in the rough forging step into the first hole portion 71, the solid material W2 is mounted to the lower die 73 in a state of aligning a center line of the solid material W2 and the center line O1 of the lower die 73. Further, by pressing to pressurize the upper die 75 to the lower die 73, the support shaft portion 41, the outer ring 44 having the outer ring raceway 44a and the pivot shaft portion 42 are simultaneously formed.
Thereafter, there is carried out trimming for punching and removing an extra burr portion extruded by finish forging.
According to the forging material W provided in this way, a range in which an end flow Jb is present is disposed on a lower side of an outer periphery defined by a range of points between a and b. As shown in
Further, an end of the metal flow is disposed on a side surface of the support shaft portion of the displacement shaft, which is clearly different from the metal flow as shown in
Further, the provided forging material W is machined to a rough shape having a finishing margin at a necessary portion. Further, when the support shaft portion 41 is machined by turning the material W, by making the center Ca of the support shaft portion 41 coincide with a center of a principal spindle of a lathe, rotating the forging material W and moving a machining tool, the support shaft portion 41 is machined to a desired rough shape. Therefore, the machining margin Ra in turning the support shaft portion 41 becomes Ra≧a and a machining amount of an amount of 2E can be reduced in comparison with that in machining of the related art.
Further, desired surface hardness and mechanical strength are increased by a heat treatment, machining or polishing is carried out at a functionally necessary portion and the final product shape of the variator part 40 is provided.
As described above, according to the embodiment of present invention, forging is carried out by making the outer diameter φd0 of the solid material smaller than the inner diameter φda of the outer ring raceway 44a of the outer ring 44 and making the center line of the solid material coincide with the center line 01 of the ring-like projected portion 72 forming the outer ring raceway and therefore, the end flow Jb of the end face of the solid material is not extruded into the outer ring raceway 44a and the metal flow Ja along the surface of the outer ring raceway 44a can be provided. Therefore, even when the repeated stress is operated by relative rotational movement of the thrust ball bearing, the strength can be prevented from being reduced at the outer ring raceway 44a.
Further, the support shaft portion 41 formed on a side opposed to the outer ring raceway 44a is forged by the second hole portion 74 of the upper die 75 having the center line O2 at the position eccentric from the center line O1 of the lower die 73 by the predetermined amount E and therefore, the forging material W along the desired product shape can be provided. Thereby, the machining margin Ra in turning the support shaft portion 41 can be minimized and machining time can be shortened.
Further, by forging as described above, the metal flow Ja is formed along the surface at the root portion 41a of the support shaft portion 41 disposed in the direction in which the support shaft portion 41 is eccentric to the pivot shaft portion 42. Therefore, even when stress is operated to the support shaft portion 41 by deforming the outer ring 44, the strength can be prevented from being reduced at the root portion 41a of the support shaft portion 41.
Further, the present invention is not limited to the embodiment and the example, mentioned above, but can pertinently be modified or improved.
The variator part of the toroidal-type continuously variable transmission of the present invention is applicable not only to a toroidal-type continuously variable transmission of a single cavity-type but also to that of a double cavity type. Further, although according to the embodiment of the present invention, the variator part is applied to a half toroidal-type continuously variable transmission, the present invention is applicable also to a full toroidal-type continuously variable transmission.
While there has been described in connection with the preferred embodiments of the present invention, it will be obvious to those skilled in the art that various changes and modification may be made therein without departing from the present invention, and it is aimed, therefore, to cover in the appended claim all such changes and modifications as fall within the true spirit and scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| P.2004-047835 | Feb 2004 | JP | national |
