JP2017203554A - Differential device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly perform welding by discharging a gas generated in welding to the external by utilizing a recessed portion formed on one side face of a flange as a work window of a differential case bites into a flange of an outer periphery of the differential case.SOLUTION: In a differential device which includes a work window 18 formed on a differential case 2 for inserting a differential mechanism 3 into the differential case 2, and a ring gear 17 press-fitted into an outer peripheral face of a flange 15 formed integrally with an outer peripheral portion of the differential case 2 at its inner peripheral face, and in which the flange 15 and the press-fitting portion of the ring gear 17 are welded 23, a recessed portion 19 is formed on one side face of the flange 15 as the work window 18 bites into the flange 15, and a gas generated in the welding is discharged through the recessed portion 19.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a differential case that accommodates a differential mechanism, a flange that is integrally formed on the outer peripheral portion of the differential case, a work window that is provided in the differential case to enable insertion of the differential mechanism into the differential case, and an outer peripheral surface of the flange And a ring gear whose inner peripheral surface is press-fitted and fitted, and a flange and a press-fitting fitting portion of the ring gear are welded.

  Such a differential device is already known as disclosed in Patent Document 1 below.

WO2013-18223

  In the differential device disclosed in Patent Document 1, when the work window is formed to be large so that the inner surface of the differential case can be easily processed or the differential mechanism can be easily inserted into the differential case, the work window has a flange. A recess may be formed by biting into the side of the film.

  The present invention provides the differential device that can discharge the gas generated during welding to the outside by using the concave portion of the flange formed by the work window biting into the flange, and can perform welding well. The purpose is to provide.

  In order to achieve the above object, the present invention provides a differential case that houses a differential mechanism, a flange that is integrally formed on an outer peripheral portion of the differential case, and the differential mechanism that can be inserted into the differential case. In the differential device comprising a work window provided in the differential case, and a ring gear whose inner peripheral surface is press-fitted and fitted to the outer peripheral surface of the flange, and the flange and the press-fitting fitting portion of the ring gear are welded, A concave portion is formed on one side surface of the flange by the work window biting into the flange, and the first feature is that gas generated during the welding is discharged through the concave portion.

  Further, according to the present invention, in addition to the first feature, a stopper wall capable of abutting against the one side surface of the flange is protruded on an inner peripheral surface of the ring gear made of a helical gear, and the flange and the stopper wall are disposed between the flange wall and the stopper wall. The second feature is that the recess remains in

  Further, in the present invention, in addition to the first or second feature, the third welding is that the welding is performed on a side surface of the flange and the ring gear opposite to the work window. Features.

  According to the first feature, when the work window is formed to be large so as to facilitate the insertion of the differential mechanism into the differential case, the recess is formed on one side of the flange by the work window biting into the flange. Since the gas generated during welding can be discharged to the outside, welding can be performed satisfactorily.

  According to the second feature, during torque transmission, a thrust load acts on the ring gear made of a helical gear, but the thrust load in one direction is supported by the flange via a welded portion between the ring gear and the flange, and is transmitted in the other direction. Since the thrust load is supported by the flange via the stopper wall, the load on the welded portion can be reduced.

  According to the third feature, since one side surface of the flange and hub to be welded is opposite to the work window, spatter generated during welding does not enter the differential case from the work window.

The longitudinal cross-sectional top view of a part of transmission apparatus which accommodates the differential gear of this invention, and it. The top view of the differential case of the said differential gear. FIG. 3 is a sectional view taken along line 3-3 in FIG. 2. FIG. 4 is a view taken in the direction of arrow 4 in FIG. 3 to show the welding procedure for the flange and the ring gear.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  In FIG. 1, a differential device D is accommodated in a mission case 1 of a vehicle. The differential device D includes a differential case 2 and a differential mechanism 3 accommodated in the differential case 2. A first bearing boss 4 and a second bearing boss 5 that are aligned on the same axis X are integrally formed on the right side and the left side of the differential case 2. It is supported by the transmission case 1 through 6 'and supports the right and left axles 7,8.

  The differential mechanism 3 includes a pinion shaft 9 held by the differential case 2 so as to be orthogonal to the axis X, a pair of pinion gears 10 supported by the pinion shaft 9, and spline coupling to the inner ends of the axles 7 and 8. A pair of side gears 11 meshing with the pinion gear 10 is configured, and the back surface of each gear is rotatably supported by the spherical inner surface of the differential case 2.

  The pinion shaft 9 is held by a pair of support holes 12 on the outer peripheral portion of the differential case 2. A pin hole 13 that is orthogonal to one of the support holes 12 and penetrates the outer periphery in the left-right direction is provided on the outer peripheral portion of the differential case 2, and a retaining pin 14 that is press-fitted into the pin hole 13 is provided. By penetrating the pinion shaft 9, the pinion shaft 9 is prevented from coming off from the support hole 12.

  Further, the differential case 2 is integrally formed with an annular flange 15 at an intermediate portion offset from the center C toward the second bearing boss 5, and a ring gear 17 that meshes with the output gear 16 of the transmission is attached to the flange 15. It is done.

  As shown in FIGS. 2 to 4, the spherical inner surface of the differential case 2 is further processed on the peripheral wall of the differential case 2 that is opposed to the diameter line perpendicular to the axis X, and the differential case 2 of the differential mechanism 3 is moved to the differential case 2. A pair of work windows 18 are provided for facilitating the insertion of the windows. These working windows 18 are formed large so as to bite into the flange 15, whereby a recess 19 is formed on the side surface of the flange 15 on the first bearing boss 4 side. As a result, the flange 15 has a pair of thin portions 15b where the concave portions 19 are present and a pair of thick portions 15a where the concave portions 19 are not present.

  As shown in FIGS. 1 and 3, the ring gear 17 includes a rim 17a having a helical tooth group on the outer periphery, a plate-like spoke 17b protruding from the inner peripheral surface of the rim 17a, and an inner periphery of the spoke 17b. An annular hub 17c projecting from the side surface on the second bearing boss 5 side at the end is formed, and an annular stopper wall 22 projecting toward the inner peripheral surface side of the hub 17c is formed integrally with the spoke 17b. The The inner peripheral surface of the hub 17c is press-fitted to the flange 15 from the first bearing boss 4 side. At that time, the stopper wall 22 abuts against the side surface of the flange 15 to regulate the press-fitting depth.

  The concave portion 19 remains between the stopper wall 22 and the flange 15, and a part of the inner peripheral surface of the hub 17 c of the ring gear 17 is exposed to the concave portion 19.

  In the ring gear 17, the rotation center plane P <b> 2 of the spoke 17 b is disposed closer to the first bearing boss 4 than the rotation center plane P <b> 1 of the flange 15. By doing so, the ring gear 17 can be made as close as possible to the center C of the differential case 2 to improve the torque transmission from the ring gear 17 to the differential case 2. Further, the thrust load and radial load acting on the ring gear 17 are shared in a balanced manner between the bearing 6 that supports the first bearing boss 4 on the transmission case 1 and the bearing 6 ′ that supports the second bearing boss 5 on the transmission case 1. Can do.

  In the mission case 1, the position in the left-right direction of the output gear 16 to be meshed with the ring gear 17 may be changed according to the specifications of the transmission. According to the present embodiment, since the rotation center plane P of the spoke 17b is as close as possible to the center C of the differential case 2, when the position of the output gear 16 is changed in either the left or right direction, the position of the spoke 17b It is sufficient that only the rim 17a is extended in either the left or right direction in accordance with the output gear 16 without changing the above, and the specification change of the output gear 16 can be flexibly dealt with.

  In FIG. 4, laser welding 23 is applied to the press-fitting fitting portions of the flange 15 and the hub 17 c from the second bearing boss 5 side over the entire circumference.

  At the time of welding, the pin hole 13 is provided in the center of the thick portion 15a in advance, and the press-fitting portion of the flange 15 and the hub 17c is formed by the diameter line Y of the flange 15 passing through the center of the pin hole 13. Are equally divided into first and second divided regions 24 and 25. Then, the pair of laser torches 26 and 26 ′ are set so that they aim at the two dividing points of the first and second divided regions 24 and 25, respectively, and the laser torch 26, 26 ′ or the differential case 2 is centered on the flange 15. The welding 23 is performed by irradiating the first and second divided regions 24 and 25 with a laser while rotating around the axis in a certain direction. In this way, the welding start point 27 and the welding end point 28 of the adjacent first and second divided regions 24 and 25 are made to coincide with each other at the center of each thick portion 15a.

  At that time, when performing welding 23 on the thin wall portion 15b, the laser output is lowered than when welding the thick wall portion 15a, or the welding speed is made faster than when welding the thick wall portion 15a, The welding depth H2 (see FIG. 3) of the thin portion 15b is made shallower than the welding depth H1 (see FIG. 1) of the thick portion 15a. Alternatively, welding is not performed at the thin portion 15b.

  Next, the operation of this embodiment will be described.

  In the ring gear 17, the rim 17 a is integrally formed with an annular stopper wall 22 protruding toward the inner peripheral surface of the hub 17 c, and the hub 17 c is press-fitted and fitted to the flange 15 of the differential case 2 from the first bearing boss 4 side. At this time, the stopper wall 22 abuts against the side surface of the flange 15 to regulate the press-fitting depth, and welding 23 by laser from the second bearing boss 5 side to the press-fitting fitting portion between the flange 15 and the hub 17 c of the ring gear 17. Therefore, the welding strength of the flange 15 and the hub 17c can be increased while welding of the press-fitting fitting portion of the flange 15 and the hub 17c is performed only on one side of the flange 15 and the hub 17c. The production efficiency can be reduced by increasing the efficiency. In addition, since one side of the flange 15 and the hub 17c to be welded is opposite to the work window 18, there is no fear that spatter generated during welding enters the differential case 2 from the work window 18.

  Further, when the weld 23 is applied to the press-fitting fitting portion, the thick portion 15a of the flange 15 and the ring gear 17 are welded with a predetermined welding depth H1, and the thin portion 15b of the flange 15 and the ring gear 17 are Since welding is performed with a welding depth H2 shallower than the welding depth H1 or not at all, penetration welding at the thin portion 15b can be avoided, and spattering into the differential case 2 can be prevented.

  Further, since the welding start point 27 and the welding end point 28 of the press-fitting fitting portion of the flange 15 and the ring gear 17 are made coincident with each other at the thick portion 15a, the welding start point 27 and the welding end point 28 coincide with each other. Even if the depth is increased, through welding can be avoided.

  Further, the press-fitting fitting portions of the flange 15 and the ring gear 17 are equally divided into a plurality of divided regions 24 and 25 arranged in the circumferential direction, and welding 23 is performed simultaneously on the plurality of divided regions 24 and 25. The difference in the cooling speed of the ring gear 17 can be suppressed as much as possible to eliminate or significantly reduce the bias of the thermal distortion of the ring gear 17 due to welding, thereby preventing the ring gear 17 from tilting. Moreover, since the welding start point 27 of each divided region 24, 25 and the welding end point 28 of the adjacent divided region 24, 25 are made to coincide with each other at the thick wall portion 15a, the flange 15 and the ring gear formed by a plurality of double strike points. The influence of 17 strength reduction can be suppressed, and penetration welding can be avoided at each coincidence point.

  Further, a pin hole 13 into which the retaining pin 14 of the pinion shaft 9 of the differential mechanism 3 is inserted is provided so as to penetrate the outer peripheral part of the differential case 2 corresponding to the thick part 15a. Since the welding start point 27 is set as a reference, not only the welding start point 27 but also the welding end point 28 is inevitably set in the thick portion 15a. Welding can be performed properly without providing special marks.

  Further, the concave portion 19 remains between the flange 15 and the stopper wall 22, and this concave portion 19 contributes to prompting discharge of gas generated during welding of the press-fitting fitting portion to the outside.

  It should be noted that the interval θ between the matching welding start point 27 and welding end point 28 and the thin portion 15b is preferably set to 45 ° or more around the central axis of the flange 15. That is, when the laser output at the thin wall portion 15b is lowered than at the thick wall portion 15a, a sufficient interval θ is provided between the welding start point 27 and the thin wall portion 15b, so that the output is further increased immediately after the start of the laser output. In a stable state, the output can be reduced. As a result, the laser output can be easily managed. Moreover, the thermal distortion of the thin part 15b which arises by the increase in welding heat input by the welding start point 27 and the welding end point 28 being in agreement can be suppressed. Moreover, the strength reduction of the flange 15 and the ring gear 17 can be suppressed by setting the coincidence point between the welding start point 27 and the welding end point 28 at a position away from the thin portion 15b in the circumferential direction.

  During torque transmission between the output gear 16 and the ring gear 17, a lateral thrust load is applied to the ring gear 17 made of a helical gear, and the rightward thrust load is supported by the flange 15 via a weld 23 portion and is directed leftward. Since the thrust load is supported by the flange 15 through the stopper wall 22, the load burden on the weld 23 can be reduced.

  The present invention is not limited to the above embodiment, and various design changes can be made without departing from the scope of the invention. For example, in the above embodiment, the press-fitting portion is equally divided into two divided areas, but can be equally divided into three or more divided areas.

D ... Differential gear 2 ... Differential case 3 ... Differential mechanism 15 ... Flange 17 ... Link gear 18 ... Work window 19 ... Recess 22 ... .... Stopper wall 23 ... welding

Claims (3)

A differential case (2) for accommodating the differential mechanism (3);
A flange (15) integrally formed on the outer periphery of the differential case (2);
A work window (18) provided in the differential case (2) to allow the differential mechanism (3) to be inserted into the differential case (2);
A ring gear (17) whose inner peripheral surface is press-fitted to the outer peripheral surface of the flange (15);
In the differential device in which the press-fitting fitting portions of the flange (15) and the ring gear (17) are welded (23),
On one side of the flange (15), the recess (19) is formed by the work window (18) biting into the flange (15),
The differential device characterized in that the gas generated during the welding (23) is discharged through the recess (19).   A stopper wall (22) capable of abutting against the one side surface of the flange (15) protrudes from an inner peripheral surface of the ring gear (17) made of a helical gear, and the flange (15) and the stopper wall (22 2. The differential device according to claim 1, wherein the recess (19) remains between.   The welding (23) is a welding performed on the side of the flange (15) and the ring gear (17) opposite to the working window (18). Or the differential device of 2.

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