JP3624083B2 - Sungear welded structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a welded structure of a sun gear.
[0002]
[Prior art]
A plurality of rotating elements including a planetary gear are incorporated in an automatic transmission of a vehicle. The sun gear, pinion gear, and ring gear that constitute the planetary gear are connected directly to each other or connected to other rotating elements via a power transmission member. It has come to be obtained.
[0003]
As a power transmission member for connecting the sun gear to other rotating elements, for example, there is a disk-shaped connecting shell formed from a plate material.
This connecting shell is joined to the end of the sun gear by welding. As the welded structure, for example, a projecting portion having the same diameter as the tooth bottom is provided at the end of the sun gear, and this projecting portion is fitted into a through hole provided in the central portion of the connecting shell, along this fitting surface. Some are welded by an electron beam.
However, in this welded structure, if the penetration depth of the weld exceeds the thickness of the connecting shell, spatter will fly to the bottom of the gear of the sun gear, or molten metal will adhere to the pinion gear and hinder engagement. There is a problem.
On the contrary, if the penetration depth is too shallow with respect to the plate thickness, the welding strength may be insufficient.
[0004]
Therefore, as shown in FIG. 4, if the diameter of the projecting portion 19 is formed to be smaller than the root of the tooth 18 of the sun gear 17 and the fitting surface is shifted from the bottom of the tooth, the penetration of the connecting shell Even if the plate thickness is exceeded, it is possible to prevent the tooth bottom from being applied.
However, in this structure, since the diameter of the fitting surface to which the connecting shell 16 is attached to the sun gear 17 is small, the circumference of the weld fitting portion is shortened, and the weld length is reduced and the weld strength is reduced. There was a problem that burrs were generated in the weld fitting part during surface machining.
[0005]
As a countermeasure, Japanese Utility Model Laid-Open No. 5-83523 proposes an annular plate 13 interposed between the connecting shell 16 'and the end face of the tooth 18 of the sun gear 17' as shown in FIG. Yes.
According to this, since the welding penetration does not reach the tooth surface of the sun gear 17 ′ due to the presence of the annular plate 13, the diameter of the fitting surface of the protrusion 19 ′ is the same as the diameter of the tooth bottom of the sun gear 17 ′. The welding strength is ensured.
[0006]
[Problems to be solved by the invention]
However, the conventional sun gear welded structure of FIG. 5 has a problem that the number of parts increases by the amount that the annular plate 13 has to be inserted between the connecting shell 16 ′ and the end face of the sun gear teeth 18.
In addition, other conventional examples including the one shown in FIG. 4 are the same, but there is a problem that burrs are required because the burrs are generated at the end faces of the teeth of the sun gear that contacts the connecting shell. is there.
Therefore, in view of the above-described conventional problems, the present invention can secure a sufficient weld length with the power transmission member without increasing the number of parts and without adversely affecting the tooth surface, and deburring at the time of welding. An object of the present invention is to provide a sungear welding structure that eliminates the need for a sun gear.
[0007]
[Means for Solving the Problems]
For this reason, the present invention is a welding structure of a power transmission member and a sun gear in an automatic transmission, and the sun gear includes a large-diameter portion provided with teeth and a small-diameter portion formed stepwise at one end of the large-diameter portion. The tooth of the large diameter portion is rounded up in the larger diameter direction than the small diameter portion as the root of the tooth is directed toward the one end side, and the power transmission member has a hole aligned with the small diameter portion. It was assumed that it was welded along the fitting part between the hole and the small diameter part.
[0008]
It is desirable that the starting point for raising the bottom of the tooth is on the one end side with respect to the meshing region with the pinion gear, and that the end of the raising is at a position avoiding the stepped end surface at the one end.
Furthermore, the stepped corner portion at the one end of the large diameter portion can be chamfered, and the bottom end of the tooth bottom can be positioned within the chamfer.
Further, the rounded-up portion of the tooth bottom can be formed in an arc shape.
[0009]
[Action]
Since the bottom of the tooth is raised in the larger diameter direction than the small diameter portion as it goes toward the one end on the small diameter side of the large diameter portion, the bottom of the same diameter as the small diameter portion does not appear on the stepped end surface of the large diameter portion. Thereby, even if the welding penetration exceeds the thickness of the power transmission member, the penetration is not exposed to the tooth surface, so that spatter is prevented and adhesion to the tooth surface does not occur.
[0010]
In particular, when the bottom end of the tooth bottom is located at a position avoiding the stepped end surface of the large diameter portion, the burr at the time of tooth surface processing does not appear on the stepped end surface with which the power transmission member abuts.
Then, by chamfering the stepped corner and positioning the bottom end of the root in the chamfer, it is possible to bring the bottom of the bottom up to the limit of one end on the small diameter side, and the shaft length of the sun gear. Can be shortened.
Further, by forming the rounded-up portion of the tooth bottom into an arc shape, for example, the raised portion is formed simply by stopping and pulling up the axial movement of the hob cutter for tooth surface processing.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described by way of examples.
1 and 2 show the configuration of an embodiment in which the present invention is applied to a welded structure with a clutch drum as a power transmission member.
FIG. 1 is a sectional view of an assembly of a clutch drum and a sun gear, and FIG. 2 is a partially enlarged sectional view of the sun gear.
The clutch drum 8 is formed of a plate material, and includes a cylindrical portion 10 and a disc portion 9 each having a spline formed on a peripheral surface thereof. The through hole 15 has a diameter that matches a small diameter portion 7 of the sun gear 1 described later.
The sun gear 1 includes a large-diameter portion 2 having teeth 11 and a small-diameter portion 7 that is stepped at one end of the large-diameter portion. The diameter of the small diameter portion 7 is substantially the same as the root diameter of the general portion 6 of the tooth 11, and the axial length of the small diameter portion 7 is the thickness dimension (plate thickness T) of the disk portion 9 of the clutch drum 8. Is the same.
Further, a chamfered portion 4 is provided at a stepped corner portion between the outer peripheral surface of the large diameter portion 2 and the stepped end surface 3 facing the disc portion 9 of the clutch drum 8.
[0012]
The tooth 11 of the large-diameter portion 2 has a root 12 of the small-diameter portion 7 starting from a point avoiding the meshing region, following the general portion 6 including the meshing region with the pinion gear indicated by phantom lines in FIG. It has the rounding-up part 5 which rounds up toward a certain one end side.
The rounded-up portion 5 has an arc shape, and the end thereof is located in the chamfer 4 of the stepped corner portion of the large diameter portion 2.
The oil hole 14 is for supplying lubricating oil to the surface of each member of the planetary gear.
[0013]
The above-described raised portion 5 is formed by cutting the tooth surface of the general portion 6 with a hob cutter for tooth surface processing, and then stopping the advancement of the hob cutter at the starting point and pulling it in a direction perpendicular to the axis J of the sun gear. The
[0014]
The small-diameter portion 7 of the sun gear 1 formed in this manner is fitted into the through hole 15 of the clutch drum 8, and the disk portion 9 is brought into contact with the stepped end surface 3 of the large-diameter portion 2. The entire circumference is welded by electron beam welding from the direction A shown in FIG.
[0015]
The embodiment is configured as described above, and since the raised portion 5 of the tooth bottom 12 is provided at the end of the large diameter portion 2 on the small diameter portion side, the step of the large diameter portion 2 with which the disk portion 9 of the clutch drum 8 abuts. No tooth surface appears on the attached end surface 3. Therefore, as shown in FIG. 3, even if the welding penetration depth L exceeds the plate thickness T of the clutch drum 8, the penetration W remains within the cross section of the raised portion 5, and between the tooth bottom 12. Since the margin G remains, the sun gear 1 is not exposed to the tooth surface. Therefore, spatter flying and adhesion of molten metal to the tooth surface are prevented.
[0016]
And since the small diameter part 7 has substantially the same diameter as the tooth bottom 12 diameter of the large diameter part general part 6, a sufficient weld length along the fitting surface with the disk part 9 is ensured, if necessary. Further, the diameter of the small diameter portion 7 can be increased.
Further, since the tooth surface does not appear on the stepped end surface 3, the burr at the time of tooth surface processing does not appear on the end surface, so that the deburring operation is unnecessary.
Furthermore, since the rounded-up portion 5 is formed simply by stopping the axial movement of the hob cutter for tooth surface processing and pulling it up, it is easy to manufacture.
[0017]
On the other hand, since the end of the rounded-up portion 5 is located in the chamfer 4 of the stepped corner, the rounded-up portion 5 is brought close to the small diameter portion 7 side, and the shaft length of the sun gear 1 may increase. Absent.
In addition, although the Example demonstrated the example which used the clutch drum 8 as a power transmission member welded with the sun gear 1, this invention is not limited to this, A connecting shell other members similar to a prior art example as a power transmission member And can be applied to the sun gear welding structure.
[0018]
【The invention's effect】
The present invention provides a large-diameter portion having teeth having a rounded-up portion where a root portion is rounded up toward one end side having a small-diameter portion following a general portion including a meshing region with a pinion gear in a sun gear, Since the small-diameter portion formed stepwise is provided at one end of the portion, even if the welding penetration exceeds the thickness of the power transmission member, the margin is left, so it is not exposed to the tooth surface. Therefore, spatter jumping is prevented and tooth root damage is not recognized.
Furthermore, by setting the end of the tooth bottom up at a position that avoids the stepped end surface of the large diameter portion, the burr at the time of tooth surface processing does not appear on the stepped end surface with which the power transmission member abuts. Therefore, the number of parts can be reduced because the number of deburring steps can be eliminated and it is not necessary to insert an annular plate between the side end surfaces of the teeth of the sun gear.
[0019]
By chamfering the stepped corner and positioning the bottom end of the root in the chamfer, it is possible to bring the bottom of the bottom up to the limit of one end on the small diameter side and shorten the sun gear shaft length. . Therefore, the weight of the sun gear and the cost for manufacturing the sun gear can be reduced.
In addition, by making the rounded-up portion of the tooth bottom into an arc shape, for example, the raised portion can be formed simply by stopping the axial movement of the hob cutter for tooth surface processing and pulling it up, making it easy to manufacture the sun gear. .
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of the present invention.
FIG. 2 is a partially enlarged sectional view of a sun gear.
FIG. 3 is a diagram showing penetration of a fitting portion by welding.
FIG. 4 is a sectional view of a conventional sun gear.
FIG. 5 is a cross-sectional view of another conventional sun gear.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Sun gear 2 Large diameter part 3 Stepped end surface 4 Chamfering 5 Round-up part 6 General part 7 Small diameter part 8 Clutch drum 9 Disk part 10 Cylindrical part 11 Tooth 12 Tooth base 13 Annular plate 14 Oil hole 15 Through hole 16, 16 'Connecting Shells 17 and 17 'Sun gear 18 Teeth 19 and 19' Protruding part W Penetration A Welding direction G by electron beam Margin T T Clutch drum plate thickness L Penetration depth

Claims (4)

A welding structure for a power transmission member and a sun gear in an automatic transmission,
The sun gear is composed of a large-diameter portion having teeth and a small-diameter portion that is stepped at one end of the large-diameter portion,
The teeth of the large-diameter portion are rounded up in the larger-diameter direction than the small-diameter portion as the root of the tooth goes to the one end side,
The power transmission member includes a hole aligned with the small diameter portion,
A welded structure of a sun gear characterized by being welded along a fitting portion between a hole and a small diameter portion of the power transmission member. 2. The start-up point of the tooth bottom is located on the one end side with respect to the meshing area with the pinion gear, and the end of the round-up is located at a position avoiding the stepped end surface at the one end. The described sun gear welded structure. 3. The sun gear welded structure according to claim 2, wherein a stepped corner portion at the one end of the large diameter portion is chamfered, and a terminal end of the tooth bottom is located in the chamfer. The welded structure of the sun gear according to claim 1, 2 or 3, wherein a rounded-up portion of the tooth bottom has an arc shape.

Images