CN212004150U

CN212004150U - Differential gear

Info

Publication number: CN212004150U
Application number: CN202020239881.3U
Authority: CN
Inventors: 关口亚久人; 相根祥吾
Original assignee: Musashi Seimitsu Industry Co Ltd
Current assignee: Musashi Seimitsu Industry Co Ltd
Priority date: 2019-03-07
Filing date: 2020-03-02
Publication date: 2020-11-24
Anticipated expiration: 2030-03-02
Also published as: JP2020143755A; JP7082077B2

Abstract

The utility model provides a differential mechanism. A first recess (81) and second recesses (82, 82 ') are formed in one side surface (8fs) of the flange portion (8f) on the side facing the window (H), the first recess (81) extending in the radial direction of the flange portion (8f) and being capable of avoiding interference with a machining tool (T) when machining the inner surface (8ci), and at least one of the second recesses (82, 82') is located on the opposite side of the first recess (81) with respect to the second axis (X2) when viewed from a projection plane orthogonal to the first axis (X1) and is smaller than the first recess (81).

Description

Differential gear

Technical Field

The utility model relates to a differential mechanism, especially have window structure's differential mechanism on differential mechanism case.

Background

Such a differential is known as disclosed in japanese patent application laid-open No. 2007-10040. The window provided in the differential case disclosed in the above publication is formed in a shape that allows the side gears and the pinion gears to be fitted into the differential case through the window.

However, in order to make the differential case cope with a larger transmission torque from the ring gear while suppressing the outer shape of the differential to a predetermined size, it is necessary to make the diameters of the side gears and the pinion gears larger, and to form the inner space of the differential case accommodating these gears larger by machining (for example, turning). In this case, in order to allow the passage of the machining tool through the window, it is necessary to form a large machining escape groove in the flange portion of the differential case, but the larger the escape groove, the more the weight balance of the differential case is broken, and the disadvantage that the differential is likely to generate rotational vibration is caused.

SUMMERY OF THE UTILITY MODEL

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a differential gear capable of solving the conventional problems with a simple structure.

In order to achieve the above object, a first feature of the present invention is to provide: a differential case having a hollow main body part, which is machined at least in part on an inner surface thereof and is rotatable about a first axis, and a flange part, which is integrally provided so as to protrude from an outer periphery of the main body part; a differential mechanism housed in the main body portion; a window provided in the main body; and a ring gear that meshes with a drive gear connected to a power source and is combined with the flange portion to transmit power from the drive gear to the differential case; the differential mechanism includes: a pair of side gears supported by the main body so as to be rotatable about the first axis; and a pinion gear supported by the main body so as to be rotatable about a second axis orthogonal to the first axis, and meshing with the pair of side gears; the window is formed in a shape capable of fitting the side gear and the pinion gear into the main body through the window, and a first concave portion extending in a radial direction of the flange portion and capable of avoiding interference with a machining tool when machining the inner surface is formed on one side surface of the flange portion facing the window, and at least one second concave portion which is located on an opposite side of the first concave portion with respect to the second axis and is smaller than the first concave portion when viewed from a projection plane orthogonal to the first axis. According to this feature, the differential case can be moved over a wide range by the large first recess and the window without interfering with the working tool. Accordingly, the internal space of the differential case can be easily enlarged by machining, and therefore the side gears and the pinions can be increased in diameter to cope with a large input torque. Further, since at least one second recess portion is disposed on the opposite side of the large first recess portion with the second axis therebetween, the weight balance of the differential case can be improved as compared with a configuration in which only the large first recess portion is provided in the flange portion. Further, since the second recess portion is small, it is possible to effectively suppress a decrease in rigidity due to the provision of the recess portion of the flange portion while improving the weight balance.

A second characteristic of the present invention is that the flange portion has a plurality of bolt holes spaced apart in the circumferential direction, and the plurality of bolt holes are used for fastening respectively the plurality of bolts of the ring gear are inserted through, the first concave portion and the second concave portion are disposed respectively adjacent in the circumferential direction between the bolt holes, the first concave portion is formed by machining, and the second concave portion is formed by casting. According to this feature, the first recess can be made close to the bolt hole within the machining tolerance by forming the first recess in a large size by machining with a small machining tolerance. This enables the first recess to be formed larger. Further, as the machining tolerance of the machined first recess becomes smaller, the contact area between the bolt hole peripheral portion of the flange portion and the ring gear is easily ensured, and the reduction of the bolt axial force in the periphery of the first recess can be prevented. Furthermore, by forming the second recess by casting, costs can be saved, since no machining is required.

A third feature of the present invention is that the flange portion is provided with only one second concave portion, and the second concave portion is located at a symmetrical position with respect to the second axis and the first concave portion when viewed from the projection plane. According to this feature, even if there is only one second recess, the weight balance of the differential case can be easily improved.

A fourth feature of the present invention is that, when viewed from the projection plane, the flange portion has a hole at a symmetrical position with respect to the second axis and the first concave portion. According to this feature, the weight balance of the differential case can be more easily improved by using the holes existing at the above symmetrical positions together with the second recess for weight adjustment.

In the present invention, the phrase "the second concave portion is smaller than the first concave portion" does not necessarily mean that the second concave portion is narrower in width and shallower in depth than the first concave portion, and includes a case where the second concave portion is narrower in width or shallower in depth than the first concave portion. In the present invention, "circumferential direction" and "radial direction" respectively refer to a circumferential direction and a radial direction with reference to the rotation axis (i.e., the first axis) of the differential case.

Drawings

Fig. 1 is a longitudinal sectional view (a sectional view taken along line 1-1 in fig. 2) showing a differential gear and its peripheral devices according to a first embodiment of the present invention.

Fig. 2 is a right side view of the differential shown without illustration of the transmission, the axle, the bearing, and the gears of the differential mechanism.

FIG. 3A is a cross-sectional view (cross-section taken along line 3A-3A of FIG. 4) showing the differential case passing through the center of the case and viewed from the right side in FIG. 1, and FIG. 3B is an enlarged sectional view taken along line 3B-3B of FIG. 3A

Fig. 4 is a sectional view taken along line 4-4 of fig. 3A.

Fig. 5 is a cross-sectional view corresponding to fig. 3A showing a second embodiment of the present invention.

Fig. 6 is a cross-sectional view corresponding to fig. 3A showing a modification of the first embodiment of the present invention.

Fig. 7 is a cross-sectional view corresponding to fig. 3A showing a modification of the second embodiment of the present invention.

Description of the reference symbols

B is bolt

H is window

R is gear ring

T cutting tool as a machining tool

X1 and X2 as the first axis and the second axis

8: differential case

8c main body part

8ci inner surface of the main body part

8f flange part

Bolt hole of 8fh

8fs, first side surface as one side surface of the flange portion facing the window side

8fz positioning hole as hole

10 differential mechanism

20 differential mechanism

22 pinion gear

23 side gear

31 driving gear

81; 82. 82', a first recess; a second recess.

Detailed Description

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

First, a first embodiment is explained with reference to fig. 1 to 4. In fig. 1, a differential 10 is housed in a transmission 9 of a vehicle (for example, an automobile), and the differential 10 distributes and transmits power from a power source (for example, an in-vehicle engine), not shown, to left and

right axles

11 and 12 as a pair of drive shafts. The differential 10 includes a metallic differential case 8 and a differential mechanism 20 built in the differential case 8.

The differential case 8 includes: a hollow body portion 8c formed in a substantially spherical shape and accommodating the differential mechanism 20 therein; first and second bearing bosses 8b1 and 8b2 integrally connected to the right and left side portions of the main body portion 8c and arranged on the first axis X1; a flange portion 8f integrally formed with the outer peripheral portion of the main body portion 8c so as to face radially outward and extending in the circumferential direction around the first axis X1. The first and second bearing bosses 8b1, 8b2 are supported on the outer peripheral side of the bosses 8b1, 8b2 by the transmission case 9 via

bearings

13, 14 so as to be rotatable about the first axis X1.

A flange portion 8f of the differential case 8 is integrally provided on the outer peripheral surface of the main body portion 8c, and is provided in an annular plate shape so as to protrude therefrom, and the ring gear R is detachably coupled to the flange portion 8f by a plurality of bolts B.

The ring gear R has: a rim Ra having a helical gear (helical gear) -shaped tooth portion Rag on the outer periphery; and spokes Rb integrally protruding from the inner peripheral surface of the rim Ra and having a ring plate shape. The tooth Rag meshes with a drive gear 31, and the drive gear 31 is an output portion of a transmission connected to a power source. Thereby, the rotational driving force from the drive gear 31 is transmitted to the main body portion 8c of the differential case 8 via the ring gear R and the flange portion 8 f.

Bolt holes 8fh are provided in the flange portion 8f at equal intervals in the circumferential direction. A plurality of bolt insertion holes Rbh are provided in the spoke Rb corresponding to the bolt holes 8 fh. The plurality of bolts B are screwed into the bolt holes 8fh of the flange portion 8f through the bolt through holes Rbh of the spokes Rb, respectively. In fig. 1, the tooth Rag is shown in a cross section along the tooth direction for the sake of simplicity of illustration.

As shown in fig. 3, a positioning hole 8 fz' is provided at an intermediate position of the circumferentially adjacent bolt hole 8fh of the flange portion 8f (in the present embodiment, an asymmetric position that is not symmetric with respect to the first recess 81 about a second axis X2 described later). The positioning holes 8 fz' position the differential case 8 in the circumferential direction with respect to other components (such as the ring gear R) when assembling or machining the differential 10 by using positioning pins, not shown.

The differential mechanism 20 includes: a shaft 21 that is disposed on a second axis X2 perpendicular to the first axis X1 at the center O of the body 8c and is supported by the body 8 c; a pair of

pinions

22, 22 rotatably supported by the shaft 21; and left and right side gears 23, 23 that mesh with the respective pinion gears 22 and are rotatable about the first axis X1.

In the present embodiment, the inner surface 8ci of the main body 8c is machined into a spherical surface shape by turning with a tool T as a cutting tool of a lathe. The inner surface 8ci of the turned body portion 8c further includes, for example, a pinion supporting surface 8cip facing the back surface of the pinion gear 22 and a side gear supporting surface 8cis facing the back surface of the side gear 23. The tool T is an example of a machining tool (cutting tool).

As shown in fig. 2 to 4, the differential case 8 has a pair of windows H in the side wall of the main body portion 8c on the first bearing boss 8b1 side with respect to the flange portion 8f in the direction along the first axis X1. The pair of windows H are disposed on both sides with the second axis X2 therebetween when viewed from a projection plane (see fig. 2 and 3A) orthogonal to the first axis X1. In other words, the side walls of the main body portion 8c are formed so as to be symmetrically arranged with the first bearing boss 8b1 interposed therebetween on the third axis X3 orthogonal to the first and second axes X1 and X2. In the present specification, in order to avoid redundancy of the following description, the projection plane orthogonal to the first axis X1 is simply referred to as "projection plane".

The window H is a window for allowing turning of the inner surface 8ci of the body portion 8c or fitting of the differential mechanism 20 into the body portion 8c, and is formed in a sufficiently large shape corresponding to the purpose. That is, the window H of the present embodiment is formed to reach the root of the flange portion 8f in the direction along the first axis X1 and to be largely open in the circumferential direction of the body portion 8 c.

In the differential case 8, a first concave portion 81 having a large size and a second concave portion 82 having a smaller size than the first concave portion 81 (more specifically, a smaller width and a smaller depth than the first concave portion 81) are formed on a first side surface 8fs of the flange portion 8f on the side facing the window H (i.e., on the side of the first bearing boss 8b 1), and the first concave portion 81 and the second concave portion 82 are formed to extend in the radial direction of the flange portion 8 f. The first recessed portion 81 is formed in such a size that the tool T, which is a machining tool for turning the inner surface 8ci of the body portion 8c, can pass through during the turning process (i.e., a recess groove for the tool T).

In addition, the second recessed portion 82 is disposed on the opposite side of the first recessed portion 81 with respect to the second axis X2 when viewed from the projection plane, and is aligned on the third axis X3 with the first recessed portion 81. In other words, the first and

second recesses

81 and 82 are located symmetrically with respect to the second axis X2.

The differential case 8 is formed by casting as described later, and each part of the differential case 8 is machined after casting. For example, when turning the inner surface 8ci of the cast differential case 8 (particularly the main body portion 8c), the differential case 8 as a workpiece is attached to a workpiece support portion (not shown) of the lathe so as to be rotatably driven about the third axis X3. The tool T of the lathe is configured to be gradually fed in a direction along the third axis X3 and in a direction orthogonal to the third axis X3. In addition, at the time of turning, the mounting position of the differential case 8 with respect to the lathe is set so that the third axis X3 overlaps with the axes of the first and second

concave portions

81 and 82 when viewed from the projection plane (see fig. 3A).

In the turning step, as described later, the tool T is gradually fed from the outside of the differential case 8 through the window H in the direction along the third axis X3 while the differential case 8 is rotated about the third axis X3. Thus, the tool T first turns the first concave portion 81 into a concave shape having an arc-shaped cross section with respect to the first side surface 8fs of the flange portion 8 f. When the tool T is fed by a predetermined amount in the direction of the third axis X3, the tool T is gradually fed not only in the direction of the third axis X3 but also in the direction orthogonal to the third axis X3, and the inner surface 8ci of the main body portion 8c is turned into a spherical shape.

As described later, the second recessed portion 82 is formed by casting the differential case 8, and is not particularly machined after casting. The second recessed portion 82 does not function as a recess groove for the tool T, as does the first recessed portion 81, but functions as a balance adjustment groove for reducing the weight imbalance of the flange portion 8f (and thus the differential case 8) due to the provision of the first recessed portion 81.

As described above, the plurality of bolts B for fixing the ring gear R to the differential case 8 are screwed into the plurality of bolt holes 8fh of the flange portion 8f arranged at equal intervals in the circumferential direction. The first and

second recesses

81 and 82 are disposed between any 2 circumferentially adjacent bolt holes 8fh (i.e., at positions that do not overlap any bolt hole 8fh when viewed from the projection plane).

Fig. 5 also shows a second embodiment of the invention. That is, in the differential case 8 of the first embodiment, only 1 second recessed portion 82 provided in the flange portion 8f by casting is disposed symmetrically to the first recessed portion 81 about the second axis X2 when viewed from the above projection plane, but in the second embodiment, at least 2 second recessed portions 82 ', 82' smaller than the first recessed portion 81 are formed in the flange portion 8f by casting. The second concave portions 82 'and 82' are disposed on the opposite side of the first concave portion 81 with respect to the second axis X2 when viewed from the projection plane, and are disposed symmetrically with respect to the third axis X3.

In the second embodiment, substantially the same operational effects as those of the first embodiment can be achieved (however, the effect of eliminating only 1 second recess 82). In the second embodiment, by providing a plurality of second recessed portions 82 ', 82' smaller than the first recessed portion 81, it is possible to more reliably eliminate the weight imbalance caused by providing the first recessed portion 81 in the flange portion 8 f.

In the first and second embodiments, the positioning hole 8 fz' provided in the flange portion 8f on the outer periphery of the differential case 8 is in an asymmetric position that is not symmetric with respect to the second axis X2 and the first concave portion 81 when viewed from the projection plane. The utility model discloses in, can also implement following embodiment: when viewed from the projection plane, the positioning hole 8fz is disposed at a symmetrical position symmetrical to the first recess 81 about the second axis X2. The positioning hole 8fz in this modification is an example of the hole of the present invention.

For example, in the modification of the first embodiment shown in fig. 6, the positioning hole 8fz is provided so as to overlap the second recess 82 disposed at a symmetrical position of the flange portion 8f that is symmetrical to the first recess 81 about the second axis X2, and in the modification of the second embodiment shown in fig. 7, the positioning hole 8fz is provided at a circumferentially intermediate position of 2 second recesses 82 of the flange portion 8f that are disposed on the opposite side of the first recess 81 with respect to the second axis X2 (i.e., a position that does not overlap the second recesses 82). The positioning holes 8fz are the same as the positioning holes 8 fz' in the first and second embodiments, and the differential case 8 is positioned in the circumferential direction with respect to other members (e.g., the ring gear R) during assembly and machining of the differential 10 using positioning pins, not shown.

Further, according to the respective modifications of the first and second embodiments, since the flange portion 8f has the positioning hole 8fz at the symmetrical position symmetrical to the first recess 81 with respect to the second axis X2 when viewed from the projection plane, when adjusting and improving the weight balance of the differential case 8 in which the first recess 81 is provided, not only the second recess 82 but also the positioning hole 8fz existing at the symmetrical position is used for the adjustment of the weight balance, whereby the weight balance of the differential case 8 can be more easily improved and adjusted.

Further, since the positioning hole 8fz is used for both the positioning mechanism of the differential case 8 and the adjustment of the weight balance, it is advantageous to simplify the structure of the differential 10 and to save the cost.

In each of the modifications of the first and second embodiments, the positioning hole 8fz is a through hole that penetrates the flange portion 8f in the axial direction, but the positioning hole 8fz may be a blind hole having a bottom. In the above modifications, the positioning hole 8fz as an example of the hole is used for both the positioning of the differential case 8 and the adjustment of the weight balance, but the hole 8fz may be used for only the adjustment of the weight balance of the differential case 8 instead of the positioning of the differential case 8.

While the embodiments of the present invention have been described above, the present invention is not limited to the embodiments, and various design changes can be made without departing from the scope of the present invention.

For example, in the above-described embodiment, the differential 10 is described as a vehicle differential, particularly, as a differential between right and left drive wheels, but in the present invention, the differential 10 may be implemented as a differential between front and rear drive wheels, or as a differential in various mechanical devices other than a vehicle.

In the above embodiment, the first and second

concave portions

81 and 82 have the circular arc-shaped cross section, but may be square grooves having a substantially inverted trapezoidal or U-shaped cross section.

In the embodiment, the bolt hole 8fh is formed as a screw hole, but the bolt hole 8fh may be formed as a simple through hole. In this case, female screws may be formed in the inner peripheral surfaces of the bolt through holes Rbh in the ring gear R, and the bolts B may be screwed into the bolt through holes Rbh through the bolt holes 8fh in the flange portion 8 f.

In the above-described embodiment, the case where the flange portion 8f of the differential case 8 and the ring gear R are joined together by the plurality of bolts B has been exemplified, but in the present invention (which is a feature other than the second one), the flange portion 8f and the ring gear R may be joined together by welding (for example, laser welding, electron beam welding, or the like).

In the above embodiment, the tooth Rag of the ring gear R is shown to be in the form of a helical gear, but the ring gear of the present invention may be other gears (for example, bevel gears, hypoid gears, spur gears, etc.) instead of the helical gear.

Claims

1. A differential mechanism, comprising:

a differential case (8) having a main body portion (8c) and a flange portion (8f), wherein at least a part of an inner surface (8ci) of the main body portion (8c) is machined, the main body portion (8c) is hollow and rotatable about a first axis (X1), and the flange portion (8f) is integrally provided so as to protrude from an outer periphery of the main body portion (8 c);

a differential mechanism (20) housed in the main body portion (8 c);

a window (H) provided in the main body (8 c); and

a ring gear (R) that meshes with a drive gear (31) connected to a power source and that is coupled to the flange portion (8f) to transmit power from the drive gear (31) to the differential case (8);

the differential mechanism (20) has: a pair of side gears (23), the pair of side gears (23) being supported by the main body portion (8c) so as to be rotatable about the first axis (X1); and a pinion gear (22) that is supported by the main body (8c) so as to be rotatable about a second axis (X2) orthogonal to the first axis (X1), and that meshes with the pair of side gears (23);

the window (H) is formed in a shape that enables the side gear (23) and the pinion gear (22) to be fitted into the main body portion (8c) through the window (H),

a first recess (81) and at least one second recess (82, 82 ') are formed in one side surface (8fs) of the flange portion (8f) on the side facing the window (H), the first recess (81) extending in the radial direction of the flange portion (8f) and being capable of avoiding interference with a machining tool (T) when machining the inner surface (8ci), the second recess (82, 82 ') being located on the opposite side of the first recess (81) with respect to the second axis (X2) when viewed from a projection plane orthogonal to the first axis (X1), and the second recess (82, 82 ') being smaller than the first recess (81).

2. The differential of claim 1,

the flange portion (8f) has a plurality of bolt holes (8fh) spaced apart in the circumferential direction, and a plurality of bolts (B) for fastening the ring gear (R) are inserted through the plurality of bolt holes (8fh),

the first and second recesses (81, 82') are respectively arranged between the circumferentially adjacent bolt holes (8fh),

the first recess (81) is formed by machining, and the second recess (82, 82') is formed by casting.

3. The differential of claim 1,

only one second recess (82) is provided in the flange portion (8f),

the second recess (82) is in a symmetrical position with respect to the second axis (X2) to the first recess (81) when viewed from the plane of projection.

4. The differential of claim 2,

only one second recess (82) is provided in the flange portion (8f),

5. The differential of any one of claims 1 to 4,

the flange portion (8f) has a hole (8fz) at a symmetrical position symmetrical to the first recess portion (81) with respect to the second axis (X2) when viewed from the projection plane.