JP2022157364A - Differential device - Google Patents

Abstract

To lock washers for side gears to a differential case with a simple structure, in a differential device which includes the differential case and a differential gear mechanism housed in the differential case, and in which the differential gear mechanism has the pair of side gears rotatably supported by the differential case, and a plurality of pinion gears engaged with both side gears and rotatably supported by the differential case.SOLUTION: A side wall (20s, 20s') at least at one side of a differential case (2) and a back face of a side gear (24) at a side same as the side wall (20s, 20s') are slidably kept into contact with each other through an annular washer (Ws), and concavo-convex engagement portions (to, Wst) engaged with each other in a concave-convex manner to lock the washer (Ws) to the differential case (2), are respectively disposed between a projecting portion (t) disposed on an inner face of the side wall (20s, 20s') and the washer (Ws).SELECTED DRAWING: Figure 1

Description

The present invention comprises a differential, particularly a differential case, and a differential gear mechanism housed in the differential case, wherein the differential gear mechanism comprises a pair of side gears rotatably supported by the differential case, The present invention relates to a differential having a plurality of pinion gears that mesh with each other and are rotatably supported by a differential case.

In the present invention and this specification, the term "axial direction" refers to the direction along the rotation axis (the first axis in the embodiment) of the differential case, and the term "circumferential direction" refers to a virtual Refers to the circumferential direction of a circle.

The above-described differential gear has been conventionally known (see, for example, Patent Literature 1 below). In the differential gear disclosed in Patent Document 1, the pinion gear washer is fixed to the differential case by anti-rotation means provided at the fitting portion between the pinion gear washer and the pinion shaft. not

JP 2018-100705 A

By the way, if the washer for the side gear is fixed to the side wall of the differential case, sliding between the side wall and the washer is eliminated. Although it is convenient, conventionally, no technical means has been proposed to prevent rotation of the side gear washer with a simple structure.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a differential gear in which a side gear washer can be prevented from rotating on a differential case with a simple structure.

In order to achieve the above object, the present invention comprises a differential case and a differential gear mechanism housed in the differential case, wherein the differential gear mechanism comprises a pair of side gears rotatably supported by the differential case. , and a plurality of pinion gears that mesh with both side gears and are rotatably supported by the differential case, wherein the side wall on at least one side of the differential case and the back surface of the side gear on the same side as the side wall are , a ring-shaped washer is slidably abutted therebetween, and between the projection provided on the inner surface of the side wall and the washer, a concave-convex engagement is provided to prevent rotation of the washer. A first feature is that a portion is provided.

In addition to the first feature, the present invention further provides that the projection protrudes axially from the inner surface of the side wall, and the uneven engagement portion includes an engagement recess provided in the projection and the A second feature is that the washer includes a protruding piece that is provided on the washer and engages with the engaging recess so that relative rotation is impossible.

In addition to the second feature, the present invention is characterized in that the protrusion is positioned coaxially with the rotational axis of the differential case, and is located on the inner peripheral portion of the inner surface of the side wall and/or in the middle of the inner peripheral end. A third feature is that the grooves are arranged in the part and extend or are arranged in the circumferential direction.

According to the first feature, the side wall on at least one side of the differential case and the back surface of the side gear are in slidable contact with an annular washer interposed therebetween, and the protrusion provided on the inner surface of the side wall and the washer mutually contact each other. In between, there is provided a concave-convex engaging portion that engages concave and convex with each other to prevent rotation of the washer. Therefore, the washer can be prevented from rotating on the side wall of the differential case by a simple anti-rotation structure including the protrusion on the side wall. can. As a result, with regard to seizure of the side gear washer, it is only necessary to take measures against seizure due to sliding of the back surface of the side gear against the washer, and the degree of freedom in design is increased in taking measures against seizure at specific portions.

According to the second feature, the projection projects axially from the inner surface of the side wall of the differential case, and the uneven engagement portion is an engagement recess provided on the projection and an engagement recess provided on the washer. and a projecting piece that is non-rotatably engaged. In this case, the projection projecting axially from the inner surface of the side wall can increase the rigidity of the side wall by making part of the side wall thicker in the axial direction. Even if the engagement recess is provided in the side wall, the reduction in rigidity of the side wall itself due to the engagement recess can be minimized.

According to the third feature, the protrusions are arranged in the inner peripheral portion of the inner surface of the differential case side wall and/or in the intermediate portion near the inner peripheral end, and extend or are arranged in the circumferential direction. The protruding portion makes it possible to reinforce the peripheral portion of the inner peripheral end of the side wall over a wide range in the circumferential direction. In addition, the protrusion is positioned coaxially with the rotational axis of the differential case, and can hold the washer surrounding the protrusion concentrically. The rear surface of the side gear can be slid in the radial direction without eccentricity. As a result, it is possible to prevent the surface pressure of the sliding surface between the washer and the side gear rear surface from locally increasing.

FIG. 1 is an overall vertical cross-sectional view and an enlarged cross-sectional view of a main part showing a transmission device according to a first embodiment of the present invention. FIG. 2 is an overall cross-sectional view (cross-sectional view taken along the line 2-2 in FIG. 1) of the differential gear, omitting side gears and side gear washers. FIG. 3 is a side view of the first side wall 20s of the differential case viewed from the carrier side (a view taken along line 3-3 in FIG. 1), and FIG. 3(B) is a drawing of the same washer with a solid line. FIG. 4 is a side view of the differential case main body viewed from the carrier side (a view taken along line 4-4 in FIG. 1). FIG. 5 is a side view (view along line 5-5 in FIG. 1) of the first end wall portion 31 of the carrier (that is, the second side wall 20s' of the differential case) viewed from the side of the differential case main body. ) is a drawing without the side gear washer (a drawing corresponding to FIG. 3A), and FIG. 5B is a drawing drawing the same washer with a solid line (a drawing corresponding to FIG. 3B). FIG. 6 is a cross-sectional view of the essential parts of the speed reducer (a cross-sectional view taken along the line 6-6 in FIG. 1). FIG. 7 is an exploded side view for explaining the relative configuration of the opposing surfaces of the differential case main body and the carrier before welding. FIG. 8 is a side view of the carrier end wall portion (that is, the second side wall 20s' of the differential case) according to the second embodiment, viewed from the differential case main body side, and corresponds to FIG. 5(B).

First, a first embodiment will be described with reference to FIGS. 1 to 7. FIG.

In FIG. 1, a transmission device A mounted on a vehicle, for example, an automobile, includes a transmission case 10 fixedly supported on the vehicle body and a single transmission unit U accommodated and supported in the transmission case 10. .

The transmission unit U includes a speed reducer R comprising a planetary gear mechanism that reduces power from a power source (for example, an electric motor mounted on a vehicle) (not shown), and outputs of the speed reducer R to first and second output shafts 51 and 52. A differential device D that distributes and transmits while allowing dynamic rotation is integrated into a unit, and the carrier C of the speed reducer R and the differential device D rotate integrally around the first axis X1. do. The first and second output shafts 51 and 52 interlock and rotate the left and right drive wheels via an interlocking mechanism (not shown).

Next, a specific example of the differential gear D will be described mainly with reference to FIGS. 1 and 2. FIG. The differential gear D includes a differential case 2 that receives rotational force from the speed reducer R, and a differential gear mechanism 21 housed in a mechanism chamber inside the differential case 2 . In particular, the differential gear D of the embodiment is a flat differential case in which the first and second side walls 20s, 20s' of the differential case 2 are formed in a thin disc shape along a virtual plane orthogonal to the rotation axis (first axis X1). Structured.

The differential gear mechanism 21 includes a plurality of (four in the embodiment) pinion shafts 22 having both ends fitted and fixed to the differential case 2 and arranged on a second axis X2 orthogonal to the first axis X1; A plurality of pinion gears 23 each rotatably supported on the pinion shaft 22 and a pair of side gears 24 meshing with the pinion gears 23 and rotatable about the first axis X1 are provided. The four pinion shafts 22 (and thus the pinion gears 23) are arranged at equal intervals in the circumferential direction of the differential case 2, that is, with a phase difference of 90 degrees.

The pinion gears 23 and the side gears 24 are composed of bevel gears, but the type of gears is not limited to bevel gears. The pair of side gears 24 function as output gears of the differential gear mechanism 21. First and second output shafts 51 are provided on the inner peripheral surfaces of cylindrical bosses 24b provided at the center of both side gears 24. , 52 are splined to each other.

The pair of side gears 24 includes the boss portion 24b, a thin disc-shaped thin intermediate portion 24m extending radially outward along the imaginary plane from the central portion of the outer periphery of the boss portion 24b, and the thin intermediate portion 24m. and a gear portion 24g which is integrally connected to the tip portion of the.

The rear surface of the gear portion 24g (that is, the contact surface with the side gear washer Ws described later) is formed in an annular plane parallel to the virtual plane, and axially outward from the outer surface of the thin intermediate portion 24m. protruding to the side. Accordingly, an annular and flat dead space peculiar to the flat differential case structure is formed on the outer surface of the thin intermediate portion 24m.

In the embodiment, for convenience of explanation, the side gear 24 on the left side in FIG. 1 is called the first side gear, and the side gear 24 on the right side is called the second side gear. 1 is called a first side wall 20s, and the right side wall is called a second side wall 20s'.

The differential case 2 includes a differential case main body 20 formed in a generally bowl-like shape with one end open, and a closing wall as a second side wall 20s' coupled to the differential case main body 20 to close the open end. The closing wall is constituted by the first end wall portion 31 of the carrier C in this embodiment. That is, the first end wall portion 31 is part of the carrier C (end wall portion), but also functions as part of the differential case 2 (second side wall 20s').

When the differential gear D is used alone (that is, independently from the speed reducer R), the blocking wall is the second side wall 20s' dedicated to the differential case.

The differential case body 20 includes a case body main portion 20M and a cylindrical body portion 20D that is fitted and fixed (for example, welded) to the outer peripheral edge of the case body main portion 20M. , a cylindrical bearing boss portion 20b, and a thin disc-shaped first side wall 20s integrally connected to the inner end of the bearing boss portion 20b and extending radially outward along the imaginary plane.

A portion of the inner surface of the first side wall 20s corresponding to the gear portion 24g of the first side gear 24 forms a planar side gear support surface 20sf1 parallel to the virtual plane. That is, the side gear support surface 20sf1 rotatably and slidably abuts and supports the rear surface of the gear portion 24g of the first side gear 24 via the annular side gear washer Ws.

As is clear from FIG. 3(B), a plurality of radially inwardly protruding anti-rotation protrusions Wst are integrally formed at intervals in the circumferential direction on the inner peripheral portion of the side gear washer Ws. be done. Note that the number of anti-rotation protrusions Wst to be installed is not limited to that in the embodiment, and at least one may be provided.

1 and 3, the inner surface of the first side wall 20s includes an annular stepped portion 20so formed on the inner peripheral portion thereof so as to be recessed one step outward in the axial direction, and an annular stepped portion 20so. and a plurality of oil grooves extending radially from the inner surface and crossing the side gear support surface 20sf1. 2g, and the outer end of the boss portion 24b of the first side gear 24 is rotatably received in the annular stepped portion 20so.

The projecting portion t is arranged at a position (that is, a position protruding into the dead space) of the first side gear 24 facing the outer surface of the thin intermediate portion 24m retreated axially inward from the rear surface of the gear portion 24g. Therefore, by utilizing the dead space, the projecting portion t can be protruded from the inner surface of the first side wall 20s without difficulty and without widening the differential case 2 in the axial direction, so that the differential case 2 can be flattened in the axial direction. advantage over

As is clear from FIG. 3(A), the inner ends of the plurality of oil grooves 2g bite into the projection t so as to traverse the annular projection t in the radial direction. An engagement recess to is recessed from the convex surface of the protrusion t. As is clear from FIGS. 1 and 3(B), at least a part of the engaging recess to is provided with the anti-rotation protrusion Wst protruding from the inner peripheral portion of the side gear washer Ws. The washer Ws is prevented from rotating with respect to the differential case 2 .

In the embodiment, the oil groove 2g is formed so as to traverse the protrusion t, so that the engagement recess to is formed at the inner end of the groove 2g at the same time as the groove 2g is formed. However, as another embodiment, the engaging recess to is formed in the protrusion t at a position different from the oil groove 2g (that is, independently from the formation of the oil groove 2g). good too. Moreover, the engagement recess to does not necessarily have to cross the protrusion t.

The engaging recess to provided on the protrusion t and the anti-rotation protrusion Wst provided on the inner peripheral portion of the washer Ws are engaged with each other to prevent the washer Ws from rotating in the differential case main body 20. A concave-convex engaging portion is configured. That is, one of the concave-convex engaging portions is the engaging concave portion to, and the other is the projecting piece portion Wst.

The outer peripheral surface of the bearing boss portion 20b is supported by the inner peripheral surface of the mission case 10 via a bearing 26 so as to be rotatable about the first axis X1. A spiral groove 20bg is provided on the inner peripheral surface of the bearing boss portion 20b as necessary. can exert a screw pump action to feed the inside of the differential case 2 . In addition, guide projections for guiding the oil flowing in the mission case 10 to the spiral groove 20bg are provided on the outer end surface of the bearing boss portion 20b as required.

Next, an example of the trunk portion 20D of the differential case main body 20 will be described. The body portion 20D includes a cylindrical outer peripheral wall portion 20c, an annular inner peripheral wall portion 20a surrounding the boss portion 24b of the side gear 24, and an outer peripheral wall portion 20c and an inner peripheral wall portion 20a arranged so as to bypass the pinion gear 23. and an intermediate wall portion 20m integrally connecting between them. In the outer peripheral wall portion 20c, first openings O1 are formed as a plurality of (four in the embodiment) holes arranged at intervals of 90 degrees in the circumferential direction so as to communicate between the inside and outside of the outer peripheral wall portion 20c. The intermediate wall portion 20m faces the radially inner side. A plurality of second openings O2 each capable of accommodating the pinion gear 24 are defined between the outer peripheral wall portion 20c and the inner peripheral wall portion 20a.

A wall portion sandwiched in the circumferential direction between the first openings O1, O1 adjacent in the circumferential direction of the outer peripheral wall portion 20c functions as the pinion gear shaft support portion 20cp. , a first support hole h1 for fitting and supporting the outer end of the pinion shaft 22 is formed. The inner peripheral wall portion 20a has a plurality of second support holes h2 for fitting and supporting the inner end portion of the pinion shaft 22, and the wall portion around the second support holes h2 also functions as a pinion gear shaft support portion. .

The outer end portion of the pinion shaft 22 is fixed to the trunk portion 20D by a retainer pin 28 (see FIG. 1) that traverses the pinion shaft 22 and is inserted into the horizontal hole of the outer peripheral wall portion 20c. The retaining pin 28 is reliably retained in the differential case 2 by engaging with the carrier C welded to the differential case main body 20 . The fixing means for the pinion shaft 22 is not limited to the embodiment, and other fixing means (for example, caulking, bolts, retaining rings, etc.) can be implemented.

Further, instead of welding, other fixing means (for example, bolting, caulking, etc.) may be used as the means for fixing the case body main portion 20M and the trunk portion 20D, or alternatively, the main case body portion 20M and the trunk portion 20M may be fixed together. The part 20D may be integrally formed.

Next, the support structure of the second side gear 24 by the first end wall portion 31 (that is, the second side wall 20s') of the carrier C will be described.

The first end wall portion 31 is formed in a disk shape along the virtual plane, and has an outer surface 31f on the side of the second side gear 24 (that is, corresponds to an inner surface of the second side wall 20s'). has a planar side gear support surface 20sf2 parallel to the virtual plane. The side gear support surface 20sf2 rotatably and slidably abuts and supports the rear surface of the gear portion 24g of the second side gear 24 via the side gear washer Ws.

Further, the outer side surface 31f of the first end wall portion 31 has an annular protrusion t located on the inner peripheral portion thereof and protruding axially inward from the side gear support surface 20sf2, and the outer side surface 31f is formed radially. and a plurality of oil grooves 2g' extending across the side gear support surface 20sf2. Especially, the protrusion t is located at a position facing the outer surface of the thin intermediate portion 24m of the second side gear 24 (that is, in the dead space). position).

Moreover, as is clear from FIG. 5(A), the inner ends of the plurality of oil grooves 2g' bite into a portion of the annular protrusion t (that is, up to the intermediate portion of the radial width of the protrusion t). The biting portion forms an engaging recess to that is recessed from the convex surface of the protrusion t. As is clear from FIG. 5(B), at least a part of the engaging recess to is provided with a detent protrusion Wst protruding radially inward from the inner peripheral portion of the side gear washer Ws. The washer Ws is non-rotatably engaged, thereby preventing rotation of the washer Ws with respect to the carrier C, which also serves as the second side wall 20s'.

Also on the side of the second side wall 20s', the engaging recess to and the anti-rotation protrusion Wst projecting from the inner periphery of the washer Ws are engaged with each other to prevent the washer Ws from rotating. Constructs a concave-convex engaging portion.

In addition, a spiral groove 31g is provided on the inner peripheral surface of the first end wall portion 31 as necessary, and the spiral groove 31g is formed in the speed reducer as the first end wall portion 31 and the second output shaft 52 rotate relative to each other. It is possible to exert a screw pump action to feed the lubricating oil in R into the differential case 2 .

The protrusions t to be provided on the first and second side walls 20s and 20s' are formed on the inner peripheral portion of the inner surface of the side wall 20s' (that is, from the inner peripheral end to the inner peripheral end), such as the protrusion t on the second side wall 20s'. Alternatively, it may be provided in an intermediate portion near the inner peripheral end of the side wall 20s like the protrusion t on the side of the first side wall 20s.

Further, the protrusion t may be formed continuously in an annular shape around the first axis X1 like the protrusion t on the side of the second side wall 20s', for example, or alternatively, the protrusion t may be formed continuously on the first side wall 20s'. They may be arranged in an arc along the circumferential direction like the projections t on the side. Alternatively, it may be formed in an arbitrary shape that does not extend in the circumferential direction.

Next, an example of the speed reducer R will be described mainly with reference to FIGS. 1 and 6. FIG. The speed reducer R includes a sun gear 41 on the input side, a ring gear 42 arranged concentrically with the gear portion 41g of the sun gear 41 and non-rotatably fitted and fixed to the inner periphery of the transmission case 10, and the sun gear 41. and a plurality of (four in the illustrated example) planetary gears P that mesh with the ring gear 42, and a carrier C that supports the plurality of planetary gears P rotatably.

The sun gear 41 is configured by forming a gear portion 41g on the front outer periphery of a cylindrical shaft-shaped sun gear body 41m. The sun gear main body 41m is rotatably supported by the transmission case 10 via bearings (not shown), and the second output shaft 52 loosely extends vertically through the sun gear main body 41m. The outer end (not shown) of the sun gear main body 41m is interlocked and connected to the output side of a power source (for example, an electric motor) (not shown) via an interlocking mechanism (not shown), so that rotational power can be input from the power source. be.

The carrier C includes first and second end wall portions 31 and 32 each formed in a disc shape and arranged axially spaced apart from each other, and a first end wall portion 31 and 32 for integrally connecting the end wall portions 31 and 32 . It includes four pillars 33 extending in the direction along the axis X1 and arranged at equal intervals in the circumferential direction (that is, with a phase difference of 90 degrees). Each pillar 33 is formed in a fan shape in cross section, as shown in FIG.

Four planetary gears P are arranged in the spaces defined between the pillars 33 adjacent in the circumferential direction. It is rotatably supported at both ends via 34 .

Note that the carrier C may be rotatably supported by the transmission case 10 via bearings as required. Reference numeral 31h in FIG. 5 denotes a support hole provided in the first end wall portion 31 for fitting and supporting (for example, press-fitting) the pivot 34, which coincides with the position of the pivot 34 when the speed reducer R is assembled. In the illustrated example, the pivot shaft 34 is shown as a separate part from the gear main body of the planetary gear P, but the pivot 34 may be configured integrally with the gear main body of the planetary gear P. In this case, A pivot 34 is rotatably supported by the first and second end walls 31 and 32 via bearings.

By the way, the body portion 20D of the differential case main body 20 and the carrier C of the speed reducer R are integrally joined at their outer peripheral end portions via a weld portion w. , 4, 5, 7 will be mainly referred to.

Between the facing surfaces of the first end wall portion 31 of the carrier C and the body portion 20D of the differential case main body 20, there is positioned at the outer peripheral end portion thereof to position the carrier C and the differential case main body 20M in the radial direction. and a plurality of abutting portions T arranged adjacent to each other radially inwardly of the spigot fitting portion I for axially positioning the carrier C and the differential case main body 20M. be done.

The spigot fitting portion I is an annular ring formed by protruding one of the opposing surfaces of the outer peripheral ends of the first end wall portion 31 and the body portion 20D (in the embodiment, the outer surface of the body portion 20D). It is composed of a convex portion 20Di and an annular concave portion 31i provided one step backward from the other of them (in the embodiment, the outer side surface 31f of the first end wall portion 31). The radial positioning of the carrier C and the differential case main body 20 is achieved by concentric fitting. Then, welding ( For example, by laser welding), the carrier C and the differential case main body 20 are coupled via the welded portion w.

Before welding, the surfaces to be welded of the first end wall portion 31 and the body portion 20D are opposed to each other and close to each other to the extent that they do not impede the abutment of the abutment portion T (that is, positioning in the axial direction) and the welding work.

Further, in a region adjacent to the radially inner end of the spigot fitting portion I and extending in an annular shape, the opposing surfaces F1 and F2 between the first end wall portion 31 and the body portion 20D are the first opposing surfaces on either side thereof. A surface F1 (in this embodiment, a side surface portion of the outer surface 31f of the first end wall portion 31 adjacent to the radially inner side of the spigot fitting portion I) is formed on the same annular plane parallel to the virtual plane.

On the other hand, a second opposing surface F2 on the other side of either of the opposing surfaces F1 and F2 (in the embodiment, an end surface portion of the outer end surface of the outer peripheral wall portion 20c adjacent to the spigot fitting portion I in the radial direction) has a plurality of bumping convex surfaces F2t that are in close contact with the first opposing surface F1 at intervals in the circumferential direction, and a plurality of concave surfaces F2h sandwiched between the bumping convex surfaces F2t that are adjacent in the circumferential direction. there is Since each concave surface F2h is recessed more than the abutment convex surface F2t, it does not contact the first opposing surface F1, that is, defines an axial gap with the first opposing surface F1.

Thus, the facing surfaces F1 and F2 between the first end wall portion 31 and the body portion 20D on the radially inner side of the spigot fitting portion I (therefore, the weld portion w) are secondly opposed to the first facing surface F1. Only the abutment convex surface F2t of the surface F2 is abutted, and the axial positioning of the differential case main body 20 and the carrier C is achieved by the abutment portion T (that is, the contact portion between the first opposing surface F1 and the abutment convex surface F2t). be. That is, the first and second opposing surfaces F1 and F2 are not abutted over the entire circumference, but abutted only at a plurality of abutting portions T arranged at intervals in the circumferential direction.

7, the circumferential position of the concave surface F2h (therefore, the non-abutting area between the first and second opposing surfaces F1 and F2) is located between the differential case main body 20 and the carrier C (first end It is set to a range that is the same as or slightly wider than the circumferential range of the high-rigidity wall sections H, H' described later in each outer peripheral wall section of the wall section 31). In other words, the circumferential position of the abutting portion T is the same as or slightly smaller than the circumferential ranges of the low-rigidity wall portions L, L' in the differential case main body 20 and the carrier C (first end wall portion 31). set in a narrow range.

The abutment convex surface F2t and concave surface F2h may be provided on the second opposing surface F2 in place of/or in addition to the structure in which they are provided on the first opposing surface F1.

By the way, in each of the outer peripheral wall portions of the differential case main body 20 and the carrier C of the embodiment, as is clear from FIG. Distributed in position. For example, in the case of the differential case main body 20, the wall portion (that is, the pinion gear shaft support portion 20cp) of the outer peripheral wall portion 20c of the body portion 20D that supports the plurality of pinion shafts 22 is thick and sturdy to support the pinion shafts 22 firmly. The wall portion sandwiched between the pinion gear shaft support portions 20cp adjacent in the circumferential direction has a window hole (that is, the first opening O1) opening on the outer peripheral surface thereof and a hollow portion , the low-rigidity wall portion L having lower rigidity than the pinion gear shaft support portion 20cp, that is, the high-rigidity wall portion H, is formed.

On the other hand, the first end wall portion 31 of the carrier C has a plurality of pillars 33 extending integrally therefrom, so that the wall portion corresponding to each pillar 33 is sufficiently reinforced by the pillars 33 and has high rigidity. As for the wall portion H', the wall portion corresponding to the space between the pillar portions 33 adjacent in the circumferential direction does not have sufficient reinforcing effect by the pillar portion 33. A low-rigidity wall portion L' having a rigidity lower than that of the wall portion H' is formed.

Moreover, in the embodiment, as is apparent from FIGS. They are arranged so that a part of them (in the illustrated example, most of them) overlaps when viewed from orthogonal projection planes. That is, the phases of the pinion gear shaft support portion 20cp, which serves as the high-rigidity wall portion H of the differential case body 20, and the wall portion of the first end wall portion 31 corresponding to the column portion 33, which serves as the high-rigidity wall portion H' of the carrier C, match. Alternatively, in the embodiment, the abutting portion T is arranged at a position in the circumferential direction avoiding both of the high-rigidity wall portions H, H'.

Further, in the embodiment, the circumferential range of the non-impacting area (that is, the area of the concave surface F2h) sandwiched between the abutting portions T adjacent in the circumferential direction is the differential case main body at the position corresponding to the non-impacting area. 20 and the first end wall portion 31 are set wider in the circumferential direction than the high-rigidity wall portions H, H' of the outer peripheral wall portions.

Next, the operation of the embodiment will be described.

In the transmission device A, when the sun gear 41 is rotationally driven by an electric motor (not shown), the sun gear 41 and the ring gear 42 are meshed with the respective planetary gears P, and the carrier C is driven while the rotational driving force of the sun gear 41 is reduced. to Then, the rotational driving force transmitted to the differential case main body 20 fixed to the carrier C is distributed by the differential gear mechanism 21 in the differential case main body 20 to the first and second output shafts 51 and 52 while allowing differential rotation. and further transmitted from the first and second output shafts 51 and 52 to the left and right drive wheels.

In this embodiment, between the mutually facing surfaces of the differential case main body 20 and the first end wall portion 31 of the carrier C, a portion other than the welded portion w (that is, the spigot fitting portion I) is provided as described above. A plurality of abutting portions T for axial positioning are arranged between the first and second opposing surfaces F1 and F2 adjacent to the radially inner end. Moreover, the positions of the abutting portions T are in the circumferential direction except at least the circumferential positions of the high-rigidity wall portions H, H' of the respective outer peripheral wall portions of the differential case main body 20 and the carrier C (first end wall portion 31). It is set at a position (in other words, a circumferential position corresponding to at least part of the low-rigidity wall portions L, L').

As a result, even if the welded portion w thermally shrinks after welding and shrinks in the axial direction, there is no concern that the abutting portion T exerts a strong tensioning action against the shrinkage deformation, so the residual stress in the welded portion w can be reduced. It can effectively reduce and effectively prevent the occurrence of delayed fracture. In addition, since the abutting portion T can effectively perform the axial positioning function at the portions corresponding to the low-rigidity wall portions L, L', the carrier C and the differential case main body 20 can be accurately positioned relative to each other during welding.

Moreover, the abutting portion T is disposed at a circumferential position excluding at least the circumferential position of the wall portion (that is, the high-rigidity wall portion H') of the first end wall portion 31 corresponding to the column portion 33. The abutment portion T can be arranged at a position in the circumferential direction of the carrier C that avoids the high-rigidity wall portion H' related to the column portion 33, and the residual stress in the weld portion w can be effectively reduced.

Further, the pinion gear shaft support portion 20cp provided on the outer peripheral wall portion 20c of the differential case main body 20 overlaps at least a portion (large portion in the illustrated example) with the column portion 33 of the carrier C when viewed in a projection plane perpendicular to the first axis X1. The pinion gear shaft support portion 20cp, that is, the high-rigidity wall portion H of the differential case body 20 is in phase with or substantially in phase with the high-rigidity wall portion H' of the carrier C related to the column portion 33. Since the abutting portion T can be arranged at a position in the circumferential direction avoiding the high-rigidity wall portions H and H', the residual stress of the welded portion w can be reduced more effectively.

Furthermore, as is clear from FIG. 7, a plurality of abutting portions T of the embodiment are arranged at intervals in the circumferential direction between the first and second opposing surfaces F1 and F2, and are adjacent to each other in the circumferential direction. The circumferential range of the non-impacting regions (that is, the region of the concave surface F2h) located between the abutting portions T is wider in the circumferential direction than the high-rigidity wall portions H, H' located at positions corresponding to the non-impinging regions. wide range. As a result, the non-impacting region can be expanded beyond the circumferential width of the high-rigidity wall portions H, H', and the circumferential width of the impinging portion T can be reduced to the necessary minimum. Residual stress can be reduced more effectively.

Further, the outer peripheral wall portion 20c of the differential case main body 20 has a hole opening in its outer peripheral surface, that is, the first opening O1. The abutting portion T can be arranged at a portion corresponding to the low-rigidity wall portion L, thereby effectively reducing the residual stress in the welded portion w.

By the way, in the differential gear D of the embodiment, the side walls 20s, 20s' on at least one side (both sides in the illustrated example) of the differential case 2 and the rear surface of the corresponding side gear 24 are slidable with the washer Ws therebetween. However, between the protrusions t on the inner surfaces of the side walls 20s and 20s' and the inner peripheral portion of the washer Ws, there is an uneven engagement portion (that is, a protrusion) that engages unevenly with each other to prevent the washer Ws from rotating in the differential case 2. An engaging recess to of the portion t and a projecting piece portion Wst of the washer Ws are provided. As a result, the washer Ws can be prevented from rotating in the differential case 2 with a simple anti-rotation structure including the projections t of the side walls 20s and 20s'. According to this anti-rotation effect, it is only necessary to take measures against seizure caused by the sliding of the side gear 24 with respect to the washer Ws. have an advantage in application.

Moreover, the projecting portion t projecting inward in the axial direction serves to increase the rigidity of the side walls 20s and 20s' by thickening a portion of the side walls 20s and 20s' in the axial direction and functioning as a reinforcing rib. However, even if the protrusion t (reinforcing rib) is partly provided with the engaging recess to, it is possible to minimize the reduction in rigidity of the side walls 20s and 20s'.

Furthermore, the protrusions t are arranged in the inner peripheral portions of the inner surfaces of the side walls 20s and 20s' or in the intermediate portions near the inner peripheral ends, and extend or are arranged in the circumferential direction. , the peripheral portions of the inner peripheral ends of the side walls 20s, 20s' can be reinforced over a wide range in the circumferential direction. In addition, since the projection t is positioned coaxially with the first axis X1 and concentrically holds the washer Ws surrounding the projection t, the washer Ws and the side gear 24 are arranged coaxially. As a result, the washer Ws and the side gear 24 can be slid in the radial direction without eccentricity. As a result, it is possible to prevent the surface pressure of the sliding surface between the washer Ws and the side gear 24 from locally increasing.

By the way, since the differential gear D of the embodiment has a differential case structure that is flat in the axial direction as described above, the diameter of the side gear 24 can be increased without increasing the size of the differential case 2 in the axial direction. Therefore, it is possible to secure a large sliding area for the side gear washer Ws.

Moreover, in the flat differential case structure of the embodiment, since the washer Ws is prevented from rotating by the side walls 20s and 20s' by the anti-rotation structure, it is possible to pinpoint and efficiently take countermeasures against seizure due to sliding of the side gear 24 against the washer Ws. As a result, the degree of freedom in designing measures against seizure can be increased. For example, if a plurality of oil grooves 2g, 2g' recessed in the inner surfaces of the side walls 20s, 20s' are arranged adjacent to both sides of each pinion gear 23 in the circumferential direction as in the embodiment, the oil grooves 2g, 2g' The fluid oil inside can effectively cool the washer Ws, especially the vicinity of the pinion gear 23 where the surface pressure is high.

In addition, in the flat differential case structure of the embodiment, the rigidity of the flat side walls 20s, 20s' is increased by specially providing the protrusions t projecting axially from the inner surfaces of the side walls 20s, 20s' (that is, reinforcing rib effect). That is, the bending deformation of the side walls 20s, 20s' (therefore, the side gear support surfaces 20sf1, 20sf2) is effectively suppressed. As a result, a sufficient sliding area between the washers Ws on the side gear support surfaces 20sf1 and 20sf2 and the rear surface of the side gear 24 can be secured.

As described above, in the flat differential case structure of the embodiment, the anti-rotation means for the washer Ws is specially provided, and the rigidity of the side walls 20s, 20s' is increased by a part of the anti-rotation means (projections t on the inner surfaces of the side walls 20s, 20s'). By making it possible to achieve (suppression of deformation), it is possible to secure a sufficient sliding area between the washer Ws and the side gear 24 and to improve the cooling performance in the vicinity of the pinion gear 23 where the surface pressure is high. .

A second embodiment is also shown in FIG. In the first embodiment, the anti-rotation protrusion t protruding from the inner surface of the first and second side walls 20s, 20s' of the differential case 2 has a circular ring shape with a constant width in the radial direction. In the embodiment, a portion of the outer peripheral portion of the circular ring-shaped anti-rotation protrusion t' protruding from the inner surface of the first and second side walls 20s, 20s' is cut straight to form a width across flat shape. (ie, a pair of plane portions tf' parallel to each other). Corresponding to the width across flats shape, the corresponding portion of the inner peripheral surface of the side gear washer Ws (that is, the projecting piece portion Wst') is also formed in the same width across flats shape.

The width across flats portion of the inner peripheral surface of the washer Ws, that is, the projecting piece portion Wst' and the projection portion t' having the width across flats shape on the outer periphery form uneven engagement so as to prevent relative rotation of the washer Ws. Rotation of the differential case 2 is reliably prevented. 8 illustrates only the outer surface 31f of the first end wall portion 31 of the carrier C, which also serves as the second side wall 20s' of the differential case 2, and the washer Ws, but the inner surface of the first side wall 20s and the washer Ws are also illustrated. It has a similar form.

Since other configurations of the second embodiment are basically the same as those of the first embodiment, each component of the second embodiment is denoted by the same reference numeral as the corresponding component of the first embodiment. No further description will be given. Therefore, the second embodiment can also exhibit basically the same effect as the first embodiment.

Although not shown, as a modification of the second embodiment, the outer peripheral portion of the anti-rotation protrusion t' provided on the inner surface of the first and second side walls 20s, 20s' is Instead of the shape, it is also possible to implement a modification in which the shape is changed to a polygonal shape (for example, triangular, square, hexagonal, etc.). In this case, the inner peripheral surface of the side gear washer Ws corresponding to the polygonal shape are also formed in a similar polygonal shape. The polygonal portion of the inner peripheral surface of the washer Ws and the protrusion t' of the inner peripheral surface of the side wall 20s, 20s' having a polygonal outer peripheral shape engage with each other in a non-relatively rotatable manner. Rotation of the differential case 2 is reliably prevented.

Although the embodiment of the present invention has been described above, the present invention is not limited to the embodiment, and various design changes are possible without departing from the scope of the invention.

For example, in the above-described embodiment, an electric motor is used as a power source for applying rotational driving force to the input portion (sun gear 41) of the transmission device A, but instead of or in addition to the electric motor, an in-vehicle engine may be used as a power source. may be used as

Further, in the above embodiment, the transmission device A is implemented as a transmission device for a vehicle (for example, an automobile), and the differential device D in the transmission device A distributes and imparts the rotational driving force to the left and right drive wheels of the vehicle. However, in the present invention, the differential device D may be used as a center differential to distribute and impart rotational driving force to the front and rear drive wheels of the vehicle. Alternatively, the transmission device A of the present invention may be implemented as a transmission device in which the speed reducer R and the differential device D are combined in various mechanical devices other than vehicles.

In the above-described embodiment, as a connecting structure between the carrier C and the differential case main body 20, for example, the end wall portion 31, which is a part of the carrier C, also serves as the second side wall 20s' of the differential case 2, and the end wall portion 31 and the differential case body 20 are welded together, but instead of such a joint structure, the second side wall, which is a part of the differential case 2, also serves as the end wall portion of the carrier C, and the second side wall It is also possible to implement a joint structure in which the pillars of the carrier C are welded to each other. Alternatively, the end wall portion 31 of the carrier C and the second side wall 20s' of the differential case body 20 may be constructed separately, and a joint structure may be implemented in which the two are welded together.

In the above-described embodiment, the opposing surfaces of the carrier C and the differential case body 20 are welded continuously over the entire circumference. can be

Further, in the above embodiment, the differential case 2 has a flat differential case structure in which the first and second side walls 20s, 20s' are thin disk-shaped along the virtual plane. A flat differential case structure in which the side walls 20s and 20s' are formed in a tapered shape slightly inclined with respect to the virtual plane may be implemented. Alternatively, a differential case structure in which the first and second side walls 20s, 20s' are curved in a dome shape may be employed.

In the above embodiment, the high-rigidity wall portions H, H' of the outer peripheral wall portions of the differential case main body 20 and the carrier C are aligned in the circumferential direction. It is also possible to implement an embodiment in which the position of ' is offset in the circumferential direction. In this case, the abutting portion T is arranged at a circumferential position excluding at least the circumferential positions of the high-rigidity wall portions H, H'.

Further, in the above embodiment, the carrier C is attached (welded) to the differential case main body 20 of the differential device D, and the differential device D and the planetary gear type reducer R are unitized into the transmission device A. Although the application of the invention has been shown, the invention may be applied to a differential that is separate and independent from the speed reducer.

In the above embodiment, the differential device D and the carrier C are joined by welding. ).

D Differential device P Planetary gear t Protrusion to Engagement recess X1 constituting one of the uneven engagement portions First axis Ws as rotation axis of the differential case Washer Wst Protruding piece 2 forming the other of the concave-convex engaging portions Differential case 20s, 20s' Side wall First and second side walls 21 as a differential gear mechanism 23 as a differential mechanism Pinion gear 24 Side gear

Claims (3)

A differential gear mechanism (21) is provided in the differential case (2), and the differential gear mechanism (21) is a pair rotatably supported by the differential case (2). and a plurality of pinion gears (23) meshing with both side gears (24) and rotatably supported by the differential case (2),
At least one side wall (20s, 20s') of the differential case (2) and the rear surface of the side gear (24) on the same side as the side wall (20s, 20s') are arranged with an annular washer (Ws) therebetween. are in slidable contact,
Between the protrusion (t) provided on the inner surface of the side wall (20s, 20s') and the washer (Ws), there is provided an uneven engaging portion that engages unevenly with each other to prevent rotation of the washer (Ws). (to, Wst, Wst') is provided. The protrusion (t) axially protrudes from the inner surface of the side wall (20s, 20s'),
The uneven engaging portion includes an engaging recess (to) provided in the protrusion (t) and a projecting piece provided in the washer (Ws) and engaged with the engaging recess (to) so as not to rotate relative to each other. 2. A differential as claimed in claim 1, characterized in that it comprises portions (Wst, Wst'). The protrusion (t) is positioned coaxially with the rotation axis (X1) of the differential case (2) and is located on the inner peripheral portion of the inner surface of the side wall (20s, 20s') and/or near the inner peripheral end. 3. A differential as claimed in claim 2, characterized in that it is arranged in the middle of the and extends or is arranged in the circumferential direction.

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