JP2018123881A - Differential device and method of manufacturing differential device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a differential device which enables a differential gear and a differential case to be fixed by welding, can make location accuracy of a tooth surface of the differential gear high, and can achieve improvement of the productivity.SOLUTION: A differential device includes: a differential mechanism 14 allowing differential rotation of a pair of output members; a differential case 10 having a first differential case 11 which houses the differential mechanism 14 and a second differential case 12 which is joined to the first differential case 11 to close the differential mechanism 14; and a differential gear 40 connected to the differential case 10. The second differential case 12 and the differential gear 40 are welded at first welding parts A1, A2, and the first differential case 11 and the second differential case 12 are welded at a second welding part B in a position different from the first welding parts A1, A2.SELECTED DRAWING: Figure 1

Description

  This technique relates to a differential device that allows differential rotation of a pair of output members and a method of manufacturing the same.

  2. Description of the Related Art Conventionally, a differential device is mounted on a vehicle or the like in order to absorb, for example, a difference in rotational speed between left and right wheels during turning, or to absorb a rotational speed difference between a front wheel and a rear wheel (for example, Patent Document 1). , See Patent Document 2). A differential device generally inputs rotation output from a speed change mechanism to a diff ring gear, transmits rotation from the diff ring gear to a differential case containing a differential mechanism, and the differential mechanism absorbs differential rotation of a pair of output members. However, it is configured to transmit rotation to these output members.

  By the way, in the differential apparatus of patent document 1, they are fixed by fastening a diff ring gear and a differential case with a volt | bolt at the time of manufacture. However, in a structure that is fastened with bolts, the fastening portion of the bolts is enlarged due to securing of strength and the like, which hinders compactness and hinders weight reduction. For this reason, as in the differential device described in Patent Document 2, a device that fixes (fixes) a differential ring gear and a differential case by welding has been proposed.

International Publication No. 2016/158059 Japanese Patent Laid-Open No. 2006-98847

  By the way, if the position (including angle and attitude) of the diff ring gear is not maintained with high accuracy with respect to the central axis of the differential device, there is a risk of causing noise and the like. Therefore, in order to increase the positional accuracy of the tooth surface of the diff ring gear, it is necessary to polish the diff ring gear. However, when the differential ring gear and the differential case are welded as in the differential device described in Patent Document 2, thermal distortion due to welding occurs, so the differential ring gear is polished after welding. Since the object to be handled including the differential case is enlarged, it is difficult to handle at the time of polishing work, and the productivity may be deteriorated. On the other hand, if the differential ring gear is polished before welding and then the differential ring gear and the differential case are welded, thermal distortion due to welding occurs, and thus there is a problem that the positional accuracy of the tooth surface of the differential ring gear cannot be maintained with high accuracy.

  Therefore, a differential device and a differential device capable of fixing the differential ring gear and the differential case by welding and improving the productivity while allowing the positional accuracy of the tooth surface of the differential ring gear to be high. An object of the present invention is to provide a manufacturing method.

This differential device
A differential mechanism that allows differential rotation of the pair of output members;
A differential case having a first case that houses the differential mechanism, and a second case that is joined to the first case and traps the differential mechanism;
A differential ring gear coupled to the differential case;
A first welded portion where the second case and the differential ring gear are welded;
A second welded portion where the first case and the second case are welded at a position different from the first welded portion.

In addition, the manufacturing method of the differential device is as follows:
A differential mechanism that allows differential rotation of the pair of output members;
A differential case having a first case that houses the differential mechanism, and a second case that is joined to the first case and traps the differential mechanism;
In a method for manufacturing a differential device comprising a differential ring gear coupled to the differential case,
A first welding step of welding the second case and the diff ring gear;
A polishing step of polishing a tooth surface of the diff ring gear in a state welded to the second case by the first welding step;
A second welding step of welding the diff ring gear and the second case, the tooth surfaces of which are polished by the polishing step, and the first case.

  According to the differential device and the method for manufacturing the differential device, the tooth surface of the diff ring gear is polished with the second case and the diff ring gear welded before the first case housing the differential mechanism is welded to the second case. It becomes possible to do. As a result, the differential ring gear and the differential case can be fixed by welding, and the position accuracy of the tooth surface of the differential ring gear can be made high, while handling during polishing is facilitated and productivity is improved. be able to.

Sectional drawing which shows the differential apparatus which concerns on this Embodiment. The flowchart which shows the manufacturing process of the differential apparatus which concerns on this Embodiment.

  Hereinafter, the differential apparatus according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional view showing a differential device according to the present embodiment, and FIG. 2 is a flowchart showing a manufacturing process of the differential device according to the present embodiment.

[Configuration of differential device]
The differential apparatus 1 according to the present embodiment is provided in an automatic transmission (not shown) in which an engine output shaft such as an FF (front engine / front drive) type is mounted on a vehicle placed horizontally with respect to the vehicle traveling direction. The rotation changed by the transmission mechanism is transmitted from the counter shaft of the transmission mechanism of the automatic transmission to a differential ring gear 40 described later.

  Specifically, as shown in FIG. 1, the differential device 1 includes a diff ring gear 40, a diff case 10 fixed to the diff ring gear 40, and a differential mechanism 14 included in the diff case 10. Configured. The differential ring gear 40 has a tooth surface 41 that meshes with a countershaft (not shown), and the tooth surface 41 is configured such that a tooth bottom 41a that is recessed between a plurality of teeth is located on the innermost side. Has been. Further, the differential ring gear 40 is welded to the outer peripheral side end surface 12a of the second differential case 12 constituting the differential case 10 at the inner peripheral side end surface 40a by first welding portions A1 and A2 which will be described in detail later. 10 and are fixed so as to be integrated.

  The differential case 10 is roughly fixed integrally with the first differential case 11 as a hollow cylindrical first case containing the differential mechanism 14 and welded to the first differential case 11 by the second welding portion B. And a second differential case 12 as a hollow disc-shaped second case for confining the moving mechanism 14. Specifically, the differential case 10 has a peripheral surface 12b facing the inner peripheral side on the side surface of the second differential case 12, and a peripheral surface 11b facing the outer peripheral side at the end portion in the axial direction of the first differential case 11, which will be described in detail later. By being welded at the second welding portion B, the differential case 10 is fixed so as to be integrated.

  Here, in order to include the differential mechanism 14, the first differential case 11 has the following configuration, for example. First, the first differential case 11 has a large opening for assembling the differential mechanism 14 at one end in the axial direction (the peripheral surface 12b side). Further, the large opening side (the peripheral surface 12 b side) of the first differential case 11 is located on the outer side in the axial direction from the gear back surface of the side gear 16 of the differential mechanism 14. Further, the first differential case 11 is configured to have a weight greater than that of the second differential case 12.

  The second differential case 12 has a bearing fitting surface 12c, and a bearing 32 is fitted to the bearing fitting surface 12c. The first differential case 11 has a bearing fitting surface 11c, and a bearing 31 is fitted to the bearing fitting surface 11c. These bearings 31 and 32 are interposed between the case 100 of the automatic transmission, that is, the differential case 10 is rotatably supported with respect to the case 100 of the automatic transmission. Note that an oil passage 101 for supplying lubricating oil is formed in the case 100, supplying the lubricating oil toward the oil receiver 21, and supplying the lubricating oil from the oil receiver 21 to the inside of the differential mechanism 14. It is configured as follows.

  The differential mechanism 14 includes a pinion shaft 18 secured by a pin 19, a pinion gear 17 rotatably supported by the pinion shaft 18, and a side gear 15 as a pair of output members respectively meshed with the pinion gear 17. 16. The side gears 15 and 16 have fitting holes 15H and 16H, respectively, into which drive shafts (not shown) are fitted. That is, the side gears 15 and 16 are connected to the left and right wheels via the drive shafts. The side gears 15 and 16 are rotatably supported while being fitted into support holes 11a formed in the first differential case 11 and support holes 12d formed in the second differential case 12, respectively.

  In the differential device 1 configured as described above, since the diff ring gear 40 is integrally fixed and coupled to the differential case 10, when rotation is input to the diff ring gear 40, the differential case 10 rotates as it is, and the pinion The shaft 18 is also rotated integrally with the differential case 10. The pinion shaft 18 revolves the pinion gear 17 and absorbs the differential rotation while rotating around the pinion shaft 18 when the differential rotation occurs in the side gears 15, 16. Transmit the revolution rotation of. As a result, rotation is transmitted to the left and right wheels via a drive shaft (not shown).

[About welded parts]
The first welded portions A1 and A2 that weld the differential ring gear 40 and the second differential case 12 extend around the center axis CT of the side gears 15 and 16 (that is, the center axis of a drive shaft (not shown)). It is welded and welded from both sides with the diff ring gear 40 in between in the axial direction of the central axis CT. In the present embodiment, the first welds A1 and A2 are welded facing each other across the diff ring gear 40 with the same radial position. This makes it possible to equalize the effect of thermal distortion compared to welding from one side in the axial direction, and the positional accuracy of the tooth surface 41 of the differential ring gear 40 after welding becomes high. The amount of polishing in the polishing step of the tooth surface 41 of the ring gear 40 can be reduced, and productivity can be improved. In addition, the equalization of the influence of a thermal distortion can also be implement | achieved more highly by the order of welding of 1st welding part A1, A2.

  The radial positions of the first welded portions A1 and A2 are separated by a radial distance d1 from the tooth bottom 41a of the tooth surface 41 of the diffring gear 40, and the distance d1 is the above-described bearing fitting. It is longer than the radial distance d2 from the mating surface 12c, that is, the first welded portions A1 and A2 are located farther from the tooth surface 41 of the diff ring gear 40 than the bearing fitting surface 12c. As a result, the tooth surface 41 of the diff ring gear 40 is less susceptible to thermal distortion than the bearing fitting surface 12c when the first welds A1 and A2 are welded, and the positional accuracy of the diff ring gear 40 by welding is improved. . For example, if the influence of thermal strain on the positional accuracy of the tooth surface 41 of the diff ring gear 40 is large, the amount of polishing of the tooth surface 41 in the polishing process described later increases and hinders improvement in productivity, but the effect of thermal strain is small. As a result, the amount of polishing of the tooth surface 41 is reduced, and the productivity is improved. Even if the bearing fitting surface 12c is affected by thermal distortion due to welding, adjustment (so-called shim adjustment) can be performed by shim rings, shim plates, or the like in adjustment when the bearing 32 is assembled. It can be easily avoided that the rotational support accuracy of the differential device 1 is greatly affected.

  The second differential case 12 has an arc portion 12r having a circular arc cross section between the first welded portions A1 and A2 and the bearing fitting surface 12c, and the first welded portion is formed by the arc portion 12r. The influence of the thermal strain on the bearing fitting surface 12c is reduced by absorbing the influence of the thermal strain of A1 and A2. For this reason, the presence of the arc portion 12r makes it possible to reduce the adjustment amount in the adjustment at the time of assembling the bearing 32.

  On the other hand, the second welded portion B for welding the first differential case 11 and the second differential case 12 is welded over the entire circumference around the central axis CT. Further, the radial distance d3 between the second welded portion B and the tooth bottom 41a of the tooth surface 41 of the differential ring gear 40 is greater than the radial distance d1 between the first welded portions A1 and A2 and the tooth bottom 41a. The second welded portion B is longer, that is, at a position farther from the tooth surface 41 of the diffring gear 40 than the first welded portions A1 and A2 in the radial direction of the diffring gear 40. That is, the second welded portion B is located farther from the tooth surface 41 of the diff ring gear 40 than the first welded portions A1 and A2. Thereby, the tooth surface 41 of the differential ring gear 40 has less influence of thermal strain when the second welded portion B is welded than the effect of thermal strain when the first welded portions A1 and A2 are welded. Thus, the positional accuracy of the diff ring gear 40 after the manufacture is improved.

[Differential device manufacturing process]
Next, the manufacturing process of the differential apparatus 1 is demonstrated along FIG. When the differential apparatus 1 is manufactured, first, as a first welding process, the differential ring gear 40 and the second differential case 12 are welded at the above-described first welded portions A1 and A2 (S1). As a result, the differential ring gear 40 and the second differential case 12 are integrally fixed, that is, the relative positional relationship of the tooth surface 41 of the differential ring gear 40 with respect to the differential case 10 is determined.

  Subsequently, as a polishing step, the diff ring gear 40 and the second differential case 12 welded by the first welds A1 and A2 are held by a jig of a polishing machine, and the tooth surface 41 of the diff ring gear 40 is polished by the polishing machine. (S2). At this time, since the first differential case 11 is not yet fixed to the second differential case 12, the integrated part of the second differential case 12 and the differential ring gear 40 is lightweight and compact, and is easy to handle. Thus, for example, conveyance to the polishing machine and an increase in the rotation speed of the polishing machine can be achieved, and productivity can be improved. In addition, even if there is an influence of thermal distortion due to welding of the first welded portions A1 and A2 or a positional shift that occurs during welding, the tooth surface 41 of the diffring gear 40 is adjusted by polishing the tooth surface 41 of the diffring gear 40 and The position of the surface 41 is positioned with high accuracy. As described above, since the influence of thermal strain can be equalized by welding the first welded portions A1 and A2 from both sides in the axial direction, the positional accuracy of the diffring gear 40 with respect to the second differential case 12 is high, and the amount of polishing is increased. Can be reduced.

  Next, as an assembling step, the differential mechanism 14 is assembled to the first differential case 11 (S3). In this assembly, first, the side gear 15 is fitted into the support hole 11a of the first differential case 11, the pinion gear 17 is assembled so as to mesh with the side gear 15, the pinion shaft 18 is inserted into the pinion gear 17, and the first differential case 11 is inserted. The pinion shaft 18 is prevented from coming off from the first differential case 11 by a pin 19 so that the pinion shaft 18 can be rotated relative to the first differential case 11, and the side gear 16 is fitted into the support hole 12d of the second differential case 12. In this state, the first differential case 11 and the second differential case 12 are combined so that the side gear 16 meshes with the pinion gear 17. Thereby, the pin 19 is prevented from being detached by the second differential case 12, and the differential mechanism 14 accommodated in the first differential case 11 is confined by the second differential case 12, and the assembly of the differential mechanism 14 is completed. The assembly of the differential device 1 ends.

  And as a 2nd welding process, the 1st differential case 11 and the 2nd differential case 12 are welded in the 2nd welding part B (S4). As a result, the first differential case 11 and the second differential case 12 are integrally fixed, that is, the manufacturing process of the differential device 1 is completed. At this time, as described above, the second weld B is located farther from the tooth surface 41 of the diff ring gear 40 than the first welds A1 and A2 in the radial direction of the diff ring gear 40. The tooth surface of the diff ring gear 40 in a state where the influence of the thermal strain when the part B is welded is less than the effect of the thermal strain when the first welded parts A1 and A2 are welded. 41 is hardly displaced due to thermal distortion caused by welding of the second welded portion B, and the position accuracy of the differential ring gear 40 with respect to the second differential case 12 is maintained at a high level.

[Summary of this embodiment]
As described above, the differential device (1) according to the present embodiment is
A differential mechanism (14) that allows differential rotation of the pair of output members (15, 16);
A differential case (10) having a first case (11) for housing the differential mechanism (14) and a second case (12) joined to the first case (11) to confine the differential mechanism (14). When,
A differential ring gear (40) coupled to the differential case (10);
A first welded portion (A1, A2) to which the second case (12) and the differential ring gear (40) are welded;
A second welded portion (B) at which the first case (11) and the second case (12) are welded at a position different from the first welded portion (A1, A2).

  Thus, before the first differential case 11 is welded to the second differential case 12, the tooth surface 41 of the differential ring gear 40 can be polished in a state where the second differential case 12 and the differential ring gear 40 are welded. And the differential case 10 can be fixed by welding, and the positional accuracy of the tooth surface 41 of the differential ring gear 40 can be made high, while handling during polishing is facilitated and productivity can be improved. it can.

Further, the differential device (1) according to the present embodiment is
The second welded portion (B) is located farther from the tooth surface (41) of the diffring gear (40) than the first welded portion (A1, A2) in the radial direction of the diffring gear (40). It is in.

  Thereby, the influence of the thermal distortion with respect to the diff ring gear at the time of welding the 2nd welding part B can be decreased, and the positional accuracy of the tooth surface 41 of the diff ring gear 40 can be made high-precision.

Further, the differential device (1) according to the present embodiment is
The second case (12) has a bearing fitting surface (12c) on which the bearing (32) is fitted,
In the first welded portion (A1, A2), the tooth surface (41) of the differential ring gear (40) is farther from the bearing fitting surface (12c).

  That is, when the bearing 32 is fitted to the bearing fitting surface 12c and assembled, the position can be adjusted by adjustment at the time of assembling even if the influence of the thermal strain on the positional accuracy of the bearing fitting surface 12c occurs. However, for example, if the influence of thermal strain on the positional accuracy of the tooth surface 41 of the diff ring gear 40 is large, the amount of polishing increases, which hinders improvement in productivity. Therefore, since the tooth surface 41 of the diff ring gear 40 is farther away from the bearing fitting surface 12c at the position of the first welded portions A1 and A2, the amount of polishing is less than when close and the productivity can be improved. it can.

Further, the differential device (1) according to the present embodiment is
The first welded portions (A1, A2) are welded from both sides in the axial direction of the output member.

  As a result, the effect of thermal strain can be equalized compared to the case of welding from one side in the axial direction, and the positional accuracy of the tooth surface 41 of the differential ring gear 40 after welding becomes high and the amount of polishing is reduced. And productivity can be improved.

And the manufacturing method of the differential apparatus (1) which concerns on this Embodiment is:
A differential mechanism (14) that allows differential rotation of the pair of output members (15, 16);
A differential case (10) having a first case (11) for housing the differential mechanism (14) and a second case (12) joined to the first case (11) to confine the differential mechanism (14). When,
A differential device (1) comprising: a differential ring (40) coupled to the differential case (10);
A first welding step (S1) for welding the second case (12) and the differential ring gear (40);
A polishing step (S2) for polishing a tooth surface (41) of the differential ring gear (40) in a state welded to the second case (12) by the first welding step (S1);
A second welding step (S4) of welding the diff ring gear (40) and the second case (12), the tooth surface (41) of which has been polished by the polishing step (S2), and the first case (11). And).

  As a result, before the first differential case 11 is welded to the second differential case 12, the tooth surface 41 of the differential ring gear 40 is polished in a state where the second differential case 12 and the differential ring gear 40 are welded, so the differential ring gear 40 and the differential case 10 are polished. Can be fixed by welding, and the positional accuracy of the tooth surface 41 of the differential ring gear 40 can be made high, while handling during polishing is facilitated and productivity can be improved.

[Possibility of other embodiments]
In addition, although the differential apparatus 1 which concerns on this Embodiment demonstrated above demonstrated what was suitable for using for FF type vehicles, for example, it is not restricted to this, For example, FR (front engine, front drive) type, etc. It may be a differential device connected to a propeller shaft connected to an automatic transmission when the engine output shaft is in a vehicle placed vertically with respect to the vehicle traveling direction. Further, for example, as in a four-wheel drive vehicle It may be a differential device called a so-called center differential that distributes engine rotation to the front and rear wheels.

  Further, in the present embodiment, a description has been given of what is a differential device mounted on an automatic transmission that shifts the rotation of the engine. However, the differential device is not limited to this, and the differential device includes an engine and a motor / generator. It can also be installed in a vehicle such as a hybrid vehicle or an electric vehicle equipped with only a motor / generator.

  In the present embodiment, the differential mechanism having a pinion gear and a pair of side gears has been described. However, the differential mechanism is not limited to this, and for example, a differential rotation of a pair of output members by a friction plate, a screw, a one-way clutch, or the like. In other words, the differential mechanism may have any structure.

  Further, in the present embodiment, the first welded portions A1 and A2 have been described as being welded facing each other across the diff ring gear 40 with the same radial position, but not limited to this. The first welded portions A1 and A2 may be welded with different diameters from both sides of the diff ring gear 40 with different radial positions. Also in this case, the influence of thermal strain can be equalized as compared with the case of welding from one side in the axial direction. It should be noted that it is also possible to achieve a higher degree of equalization of the influence of thermal strain by the radial positions of the first welded portions A1 and A2 and the order of welding.

DESCRIPTION OF SYMBOLS 1 ... Differential apparatus 10 ... Differential case 11 ... 1st case (1st differential case)
12 ... 2nd case (2nd differential case)
12c ... Bearing fitting surface 14 ... Differential mechanism 15, 16 ... Output member (side gear)
32 ... Bearing 40 ... Differential ring gears A1, A2 ... First weld B ... Second weld S1 ... First welding step S2 ... Polishing step S4 ... Second welding step

Claims (5)

A differential mechanism that allows differential rotation of the pair of output members;
A differential case having a first case that houses the differential mechanism, and a second case that is joined to the first case and traps the differential mechanism;
A differential ring gear coupled to the differential case;
A first welded portion where the second case and the differential ring gear are welded;
A second welded portion where the first case and the second case are welded at a position different from the first welded portion,
Differential device. The second weld is in a position farther from the tooth surface of the diff ring gear than the first weld in the radial direction of the diff ring gear.
The differential device according to claim 1. The second case has a bearing fitting surface on which a bearing is fitted,
The first welded portion is located at a position where the tooth surface of the diff ring gear is farther than the bearing fitting surface.
The differential device according to claim 1. The first welded portion is welded from both sides in the axial direction of the output member.
The differential device according to any one of claims 1 to 3. A differential mechanism that allows differential rotation of the pair of output members;
A differential case having a first case that houses the differential mechanism, and a second case that is joined to the first case and traps the differential mechanism;
In a method for manufacturing a differential device comprising a differential ring gear coupled to the differential case,
A first welding step of welding the second case and the diff ring gear;
A polishing step of polishing a tooth surface of the diff ring gear in a state welded to the second case by the first welding step;
A second welding step of welding the diff ring gear and the second case, the tooth surfaces of which are polished by the polishing step, and the first case;
A method of manufacturing a differential device.

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