JP6187280B2 - Differential gear device and manufacturing method thereof - Google Patents

Description

  A differential gear mechanism comprising: a differential gear mechanism having a plurality of differential gears that mesh with each other; a holding member that holds a rotating shaft of the plurality of differential gears; and an outer peripheral gear fixed to the outer periphery of the holding member. The present invention relates to a gear device and a manufacturing method thereof.

As the differential gear device as described above, for example, devices described in Patent Documents 1 to 3 below are already known.
In the technique of Patent Document 1, the holding member has a first holding member and a second holding member, and the first holding member and the second holding member are coupled by a bolt. Moreover, the 1st holding member and the 1st outer periphery gear are integrally formed, and the 2nd holding member and the 2nd outer periphery gear are integrally formed.
In the technique of Patent Document 2, the holding member has a first holding member and a second holding member, and the first holding member and the second holding member are coupled by welding, and the outer side in the radial direction of the welded portion. In addition, the outer peripheral gear is coupled by welding.
In the technique of Patent Document 3, the holding member has a first holding member and a second holding member, and the first holding member and the second holding member are joined by welding. Further, the first holding member and the outer peripheral gear are integrally formed.

JP 2000-266162 A JP-T-2006-509172 JP 2009-097716 A

However, in the technique of Patent Document 1, since the first holding member and the second holding member are coupled by the bolt, the weight of the device increases by the amount of the fastening mechanism using the bolt.
In the technique of Patent Document 2, the welded portion between the holding members and the welded portion between the holding member and the outer peripheral gear are provided close to each other, and strain caused by welding is concentrated on a part, and the strain amount ( There is a risk that the amount of deformation) increases. As a result, the position (roundness, etc.) of the outer peripheral gear may be deteriorated.
In the technique of Patent Document 3, since the first holding member and the outer peripheral gear are integrally formed, it is necessary to use the same base material for the outer peripheral gear and the first holding member. The base materials of different materials cannot be used according to the characteristics required for each.

  Therefore, a differential gear device that can use different base materials for the outer peripheral gear and the holding member, and can reduce the influence of the distortion of the member due to the coupling while reducing the weight of the coupling portion that couples the members to each other. And realization of the manufacturing method is desired.

A differential gear mechanism having a plurality of differential gears meshing with each other according to the present invention, a holding member that holds a rotating shaft of the plurality of differential gears, and an outer peripheral gear fixed to the outer periphery of the holding member; The differential gear device comprising: the holding member includes a first holding member and a second holding member, and the outer peripheral gear includes a holding member attaching portion attached to the first holding member. In addition, the holding member mounting portion has a tapered portion in which the thickness of the member decreases toward one side of the reference axis direction that is a direction parallel to the rotation axis of the holding member, and the first holding member and the The tapered portion of the outer peripheral gear is welded at the first welded portion, the first holding member and the second holding member are welded at the second welded portion, and the first welded portion and the second welded portion are in the reference axis direction, the differential gear unit Across the center position of the lies in on the opposite side to each other.

According to this characteristic configuration, the outer peripheral gear and the first holding member are separated from each other. Therefore, the outer peripheral gear and the first holding member are made of different base materials according to the required characteristics. be able to. Therefore, it is easy to provide the outer peripheral gear and the first holding member with appropriate characteristics.
Further, since the first holding member and the outer peripheral gear are coupled by welding and the first holding member and the second holding member are coupled by welding, the weight of the coupling portion is reduced as compared with a fastening mechanism using a bolt. Can be made.
Moreover, since the first welded portion and the second welded portion are provided on opposite sides of the center position of the differential gear mechanism in the reference axis direction, the first welded portion and the second welded portion are Can be separated on both sides of the center position. For this reason, the strain generated by welding in the first welded portion and the strain generated by welding in the second welded portion can be dispersed so as not to concentrate, and an increase in strain (deformation amount) can be suppressed. . Further, the second welded portion can be separated from the outer peripheral gear provided on the first welded portion side, and the influence of strain caused by welding in the second welded portion can be hardly transmitted to the tooth surface of the outer peripheral gear . Furthermore, since the first holding member and the tapered portion of the outer peripheral gear are welded, even if distortion (deformation) occurs due to welding, the distortion amount (deformation amount) of the tip portion of the tapered portion of the outer peripheral gear increases. The influence of strain generated by welding in the first welded portion can also be hardly transmitted to the tooth surface of the outer peripheral gear. For this reason, it is possible to suppress the deterioration of the tooth surface position (roundness, etc.) of the outer peripheral gear, and it is possible to suppress the deterioration of the machining accuracy.

  Here, it is preferable that the base material of the outer peripheral gear is a material having higher hardness than the base material of the first holding member.

  According to this configuration, a material having higher hardness is used for the outer peripheral gear where a tooth surface is formed and high hardness is required, and stress is not concentrated as much as the tooth surface, and the first holding member is formed into a complicated shape. In addition, a material with lower hardness is used. Therefore, the base material of the outer peripheral gear and the base material of the first holding member can be made of materials that meet the required characteristics.

  Here, it is preferable that the outer peripheral gear has a carburized layer having a carbon concentration and hardness higher than that of the inside at least on the tooth surface.

  According to this configuration, since the carburized layer is provided on at least the tooth surface, the hardness of the tooth surface can be improved. Further, since the outer peripheral gear is separate from the first holding member, when forming the carburized layer, the outer peripheral gear can be carburized and quenched with a single body. Therefore, it is possible to reduce the manufacturing cost of the carburizing process and the quenching process, such as the need for the carburizing process of the first holding member.

  Here, it is preferable that the first holding member, the second holding member, and the outer peripheral gear are forged parts.

  According to this configuration, since each member is a forged part, welding between the members becomes easier than in the case of a cast part, and the strength of the welded portion can be ensured. In addition, it is easy to reduce the weight by making the thickness of each part thinner than in the case of cast parts while ensuring the necessary strength.

Here, the first holding member includes a first tapered portion in which the thickness of the member decreases from the center position side toward the one side in the reference axis direction, and the first welded portion includes the first tapered portion. It is preferable that it is provided across the tip of the part and the tip of the tapered part of the outer peripheral gear .

Here, it is preferable that the first holding member includes a second tapered portion in which the thickness of the member decreases from the center position side toward the other side in the reference axis direction.
According to this configuration, even if distortion (deformation) occurs due to welding in the second welded portion, the amount of distortion (deformation amount) at the tip of the tapered portion increases, and the base of the tapered portion (the member is thick). The amount of strain decreases toward the side. In this way, the deformation of the tip of the tapered portion absorbs the influence of strain caused by the second welded portion, and the effect of strain caused by the second welded portion is less likely to be transmitted to other parts such as the tooth surface of the outer peripheral gear. be able to.

  Here, the differential gear mechanism is a shaft held by the first holding member, and a first rotation shaft whose axis intersects perpendicularly with a rotation axis of the holding member, and the first rotation shaft. A first bevel gear supported rotatably with respect to the holding member, and a second bevel gear supported rotatably with respect to the holding member and meshing with the first bevel gear, It is preferable that the first welded portion and the second welded portion are provided on opposite sides of the first rotating shaft in the reference axis direction.

According to this configuration, in the differential gear mechanism having the first bevel gear supported by the first rotating shaft and the second bevel gear meshing with the first bevel gear, the first welded portion and the second welded portion are In addition, the differential gear mechanism can be appropriately spaced on both sides of the first rotation shaft at the center position.
In this case, the first welded portion and the second welded portion are the first rotating shaft, the first bevel gear, and the second bevel gear that constitute the differential gear mechanism in the reference axis direction. It is preferable that they are provided on opposite sides with respect to the entire body.

  Here, it is preferable that the second welding portion is provided on a side away from the first rotation shaft in the reference axis direction with respect to a sliding surface between the holding member and the first bevel gear. .

  According to this configuration, since the sliding surface between the holding member and the first bevel gear is provided on the first holding member side, the processing of the sliding surface is facilitated. Moreover, it can suppress that an influence is exerted on a sliding surface by the welding in a 2nd welding part.

  Here, the first holding member has a cutout portion formed so as to avoid a holding portion that holds the rotation shafts of the plurality of differential gears, and the cutout portion is formed from the first welded portion side. It is preferable to open in the direction toward the two welds.

  On the first welding part side of the first holding member, the force acts on the outer peripheral gear, so the strength of the first holding member is necessary, but on the second welding part side, the force acts on the outer peripheral gear. Therefore, the strength of the second holding member can be reduced as compared with the first welded portion side. According to said structure, since the notch is opening in the direction which goes to the 2nd welded part side from the 1st welded part side, it makes it open to the 2nd welded part side which can reduce intensity | strength, and is appropriate. In addition, the weight reduction of the differential gear device can be achieved. At this time, the notch is formed so as to avoid the holding portion that holds the rotating shafts of the plurality of differential gears, so that the strength of the holding portion can be maintained.

Further, according to the present invention, a differential gear mechanism having a plurality of differential gears that mesh with each other, and a member that holds the rotation shafts of the plurality of differential gears, the first holding member and the second holding member, A holding member, and an outer peripheral gear fixed to the outer periphery of the holding member. The outer peripheral gear includes a holding member attaching portion attached to the first holding member, and the holding member attaching portion holds the holding member. The characteristic configuration of the manufacturing method of the differential gear device having a tapered portion in which the thickness of the member decreases toward one side of the reference axis direction, which is a direction parallel to the rotation axis of the member, includes the first holding member and the A first welding step for welding the tapered portion of the outer peripheral gear; a tooth polishing step for polishing a tooth surface of the outer peripheral gear after the first welding step; and a first holding member after the tooth polishing step. Assembling the plurality of differential gears And car assembling process, after the gear assembly step, in the reference axis direction, on the opposite side across the center position of the differential gear mechanism with respect to the welding portion of the first welding step, the first holding And a second welding step of welding the member and the second holding member.

The differential gear device manufactured by this manufacturing method can also obtain the effects of the above-described differential gear device.
In particular, according to the above manufacturing method, since the tooth surface of the outer peripheral gear is polished after the first holding member and the outer peripheral gear are welded in the first welded portion, the teeth distorted by welding in the first welded portion. The surface can be corrected by polishing to improve processing accuracy. In this polishing stage, since the plurality of differential gears are assembled to the first holding member, it is easy to perform polishing and cleaning after polishing.
After that, the second welded portion to which the first holding member and the second holding member are welded is separated from the outer peripheral gear provided on the first welded portion side, so that the influence of strain generated by the second welded portion is affected. This makes it difficult to transmit to the tooth surface of the polished outer peripheral gear. Therefore, it can suppress that the processing precision of an outer periphery gear deteriorates after grinding | polishing.

  Here, it is preferable to perform a carburizing process and a quenching process on at least the tooth surface of the outer peripheral gear before the first welding step.

  According to this configuration, the carburizing process and the quenching process can be performed by the outer peripheral gear alone before the outer peripheral gear is welded to the first holding member, and the carburizing process of the first holding member becomes unnecessary. In addition, the manufacturing cost of the carburizing process and the quenching process can be reduced.

  Here, it is preferable to perform a forging process in which the outer peripheral gear, the first holding member, and the second holding member are formed by forging.

  According to this structure, since each member is shape | molded by forge, the welding between members becomes easier than the case where it shape | molds by casting, and the intensity | strength of a welding part can be ensured. In addition, it is easy to reduce the weight by making the thickness of each part thinner than in the case of casting while ensuring the necessary strength.

It is sectional drawing of the differential gear apparatus which concerns on embodiment of this invention. 1 is a side view of a differential gear device according to an embodiment of the present invention. It is a flowchart which concerns on the manufacturing method of the differential gear apparatus which concerns on embodiment of this invention.

An embodiment of a differential gear device 1 according to the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of the differential gear device 1, and FIG. 2 is a side view of the differential gear device 1.
The differential gear device 1 is fixed to the outer periphery of a differential gear mechanism 3 having a plurality of differential gears 2 that mesh with each other, a holding member CA that holds a rotating shaft 4 of the plurality of differential gears 2, and the holding member CA. Outer peripheral gear RG.
The holding member CA has a first holding member CA1 and a second holding member CA2. The first holding member CA1 and the outer peripheral gear RG are welded at the first welding portion W1. The first holding member CA1 and the second holding member CA2 are welded at the second welding portion W2. The first welded portion W1 and the second welded portion W2 are opposite to each other across the center position C of the differential gear mechanism 3 in the reference axis direction X that is parallel to the rotational axis A of the holding member CA. Is provided.

As described above, the direction parallel to the rotation axis A of the holding member CA and the outer peripheral gear RG that rotates integrally with the holding member CA is defined as the reference axis direction X. In the reference axis direction X, a direction from the second welded portion W2 side to the first welded portion W1 side is defined as a reference axis first direction X1, and is a direction opposite to the reference axis first direction X1, the first welded portion W1. A direction from the side toward the second welded portion W2 side is defined as a reference axis second direction X2.
Hereinafter, the differential gear device 1 according to the present embodiment will be described in detail.

1. Schematic configuration of differential gear device 1 <Differential gear mechanism 3>
The differential gear mechanism 3 is a gear mechanism having a plurality of differential gears 2 that mesh with each other.
In the present embodiment, the differential gear mechanism 3 is a differential gear mechanism using a pinion gear PG and a side gear SG which are bevel gears meshing with each other.
Specifically, the differential gear mechanism 3 includes a pinion rotation axis PS that is an axis held by the holding member CA and whose axis intersects perpendicularly to the rotation axis A of the holding member CA, and the pinion rotation axis PS. The pinion gear PG is rotatably supported with respect to the holding member CA, and the side gear SG is rotatably supported with respect to the holding member CA and meshes with the pinion gear PG.
Here, the pinion gear PG corresponds to the “first bevel gear” in the present invention, the side gear SG corresponds to the “second bevel gear” in the present invention, and the pinion rotation shaft PS corresponds to the “first rotation in the present invention”. Corresponds to “axis”.

  In the present embodiment, the differential gear mechanism 3 includes a pair of first side gear SG1 and second side gear SG2 that are arranged with tooth surfaces facing each other on both sides of the reference axis direction X across the pinion rotation shaft PS. A pair of first pinion gears PG1 and second pinion gears that mesh with both side gears SG1 and SG2 and have tooth surfaces facing each other on both sides in the axial direction of the pinion rotation shaft PS across the rotation axis A of the holding member CA. It has PG2. Each side gear SG1, SG2 is arranged coaxially with the rotational axis A of the holding member CA. Each of the side gears SG <b> 1 and SG <b> 2 includes a cylindrical rotation shaft portion 50 that is rotatably supported by the holding member CA, and a conical bevel gear portion 51 that is fixed to the rotation shaft portion 50.

  Each of the pinion gears PG1, PG2 is configured to rotate (revolve) together with the holding member CA and to rotate (rotate) around the pinion rotation axis PS. Each pinion gear PG1, PG2 meshes with both of the two side gears SG1, SG2 on both sides of the reference axis direction X. When the holding member CA rotates, the two side gears SG1 and SG2 on both sides of the reference axis direction X rotate via the pinion gears PG1 and PG2 that rotate together with the holding member CA. Here, the pinion gears PG1 and PG2 rotate (rotate) around the pinion rotation axis PS, thereby causing the two side gears SG1 and SG2 to perform a differential operation.

The holding member CA is rotatably supported with respect to a case member (not shown) that is a non-rotating member. The outer peripheral gear RG is coupled to rotate integrally with the holding member CA. The outer peripheral gear RG is meshed with an output gear (not shown) connected to a driving force source. Each of the side gears SG1 and SG2 is coupled so as to rotate integrally with an axle (not shown) connected to the wheels.
The differential gear device 1 transmits the rotation and torque transmitted from the output gear of the driving force source to the outer peripheral gear RG to the holding member CA, and the holding member CA holds the rotation and torque transmitted to the holding member CA. Through the pinion gears PG1 and PG2, it is distributed and transmitted to the two side gears SG1 and SG2 on both sides of the reference axis direction X. The rotation and torque transmitted to the side gears SG1 and SG2 are transmitted to the wheels via the axles.

2. Detailed configuration of differential gear device 1 <materials of each member>
The holding member CA has a first holding member CA1 and a second holding member CA2.
The first holding member CA1 and the outer peripheral gear RG are welded at the first welded portion W1, and the first holding member CA1 and the second holding member CA2 are welded at the second welded portion W2.
The first holding member CA1, the second holding member CA2, and the outer peripheral gear RG are forged parts formed by plastic deformation by forging, and can be easily welded to each other as compared with a cast part having a high carbon concentration. It has become.

  Since the first holding member CA1 is a forged part and has a higher strength per unit mass than a cast part, the first holding member CA1 can be reduced in weight and size. In the present embodiment, as shown in FIG. 2, the first holding member CA <b> 1 has a notch 31 formed so as to avoid the holding portion 26 that holds the rotating shaft 4 of the plurality of differential gears 2. The notch 31 opens in a direction (reference axis second direction X2) from the first welded portion W1 side toward the second welded portion W2 side. In the present embodiment, the notch 31 is a reference for the gear mounting portion 21 that supports the outer peripheral gear RG at a circumferential position where the holding portion 26 (through hole in this example) that holds the pinion rotation shaft PS is not provided. It extends in the reference axis second direction X2 from the end on the second axial direction X2 side, and opens at the end on the second reference axis X2 side. The notch 31 extends to the reference axis first direction X1 side with respect to the holding part 26 that holds the pinion rotation axis PS.

  The outer peripheral gear RG and the first holding member CA1 are separated from each other so that materials suitable for the required characteristics can be used. Since the tooth surface 65 is formed on the outer peripheral gear RG and stress is concentrated, high hardness is required. The first holding member CA1 is required to be compared with the outer peripheral gear RG because the stress is not concentrated as much as the tooth surface 65, such as supporting each bevel gear with a sliding surface, and it is necessary to plastically deform into a complicated shape. Hardness is low. Therefore, the base material of the outer peripheral gear RG is a material having higher hardness than the base material of the first holding member CA1.

  Further, since the second holding member CA2 holds the second side gear SG2, the hardness required is lower than that of the first holding member CA1 that holds the pinion gears PG1, PG2 and the outer peripheral gear RG in addition to the first side gear SG1. Therefore, the hardness of the base material of the second holding member CA2 is the same as or lower than the hardness of the base material of the first side gear SG1.

  As the base material of the outer peripheral gear RG, chromium molybdenum steel (for example, SCM420H of Japanese Industrial Standard (JIS)) or the like is used. Carbon steel (for example, Japanese Industrial Standards (JIS) S45C, S35C) or the like is used as the first holding member CA1. As the second holding member CA2, carbon steel (for example, Japanese Industrial Standards (JIS) S35C, S15C) or the like is used.

  The outer peripheral gear RG has a carburized layer having a carbon concentration and hardness higher than that of the inner portion at least on the tooth surface 65. Such a carburized layer is formed by a carburizing process and a quenching process. Since the outer peripheral gear RG is separate from the first holding member CA1, the carburizing process and the quenching process can be performed only on the outer peripheral gear RG.

<Arrangement configuration relating to welds W1 and W2>
The first welded portion W1 and the second welded portion W2 are provided on opposite sides of the center position C of the differential gear mechanism 3 in the reference axis direction X. In the present embodiment, the pinion rotation shaft PS is disposed at the center position C of the differential gear mechanism 3. And the 1st welding part W1 and the 2nd welding part W2 are provided in the mutually opposite side in the reference | standard axis direction X on both sides of pinion rotating shaft PS.

  The first holding member CA1 extends across both sides of the reference axis direction X of the pinion rotation shaft PS. The outer peripheral gear RG and the first welded portion W1 thereof are arranged on the reference axis first direction X1 side with respect to the pinion rotation axis PS. The second holding member CA2 and the second welded portion W2 thereof are disposed on the reference axis second direction X2 side with respect to the pinion rotation axis PS.

The first holding member CA1 holds the pinion rotation shaft PS, the pinion gears PG1 and PG2, and the first side gear SG1. The second holding member CA2 holds the second side gear SG2.
The first holding member CA1 includes a pinion gear support portion 27 extending in the reference axis direction X so as to cover the radially outer sides of the pinion gears PG1 and PG2. Here, the radially outer side is the radially outer side with respect to the rotation axis A of the holding member CA. In the present embodiment, the radially inner surface of the pinion gear support portion 27 is in contact with the radially outer surface (surface opposite to the tooth surface) of the pinion gears PG1 and PG2, and slides with the pinion gears PG1 and PG2. It becomes the sliding surface 22 to do. In the present embodiment, the radially outer surfaces of the pinion gears PG1, PG2 have a spherical shape that protrudes radially outward, and the sliding surface 22 of the first holding member CA1 has a corresponding spherical shape. Accordingly, the sliding surface 22 contacts the entire radially outer surface of the pinion gears PG1, PG2.

  The first holding member CA1 includes a side gear support portion 28 that rotatably supports the first side gear SG1 on the reference axis first direction X1 side with respect to the pinion gear support portion 27. In the present embodiment, the side gear support portion 28 includes an annular plate-like gear support wall portion 24 that extends radially inward from an end of the pinion gear support portion 27 on the reference axis first direction X1 side, and the gear support wall. And a cylindrical gear support boss portion 25 extending from the radially inner end of the portion 24 toward the reference axis first direction X1 side. A sliding surface in which the surface of the gear support wall portion 24 on the reference axis second direction X2 side slides with the surface of the first side gear SG1 on the reference axis first direction X1 side (surface opposite to the tooth surface) of the bevel gear portion 51. It is a moving surface. The inner peripheral surface of the gear support boss portion 25 rotatably supports the outer peripheral surface of the rotary shaft portion 50 of the first side gear SG1. The outer peripheral surface of the gear support boss portion 25 is rotatably supported by a case that is a non-rotating member via a bearing (not shown). The outer peripheral surface of the axle is splined to the inner peripheral surface of the rotation shaft portion 50 of the first side gear SG1 (not shown).

  The end of the pinion gear support 27 on the reference axis second direction X2 side is an end extension 23 that opens toward the reference axis second direction X2, and is held by the end extension 23 in the second direction. A member CA2 is attached.

  The second holding member CA2 includes an annular plate-like gear support wall 40 extending radially inward from a portion attached to the end extension 23 of the first holding member CA1, and the gear support wall 40. And a cylindrical gear support boss 41 extending from the radially inner end to the reference axis second direction X2 side. A surface on the reference axis first direction X1 side of the gear support wall 40 slides on a reference axis second direction X2 side surface (surface opposite to the tooth surface) of the bevel gear portion 51 of the second side gear SG2. It is a moving surface. The inner peripheral surface of the gear support boss portion 41 rotatably supports the outer peripheral surface of the rotary shaft portion 50 of the second side gear SG2. The outer peripheral surface of the gear support boss 41 is rotatably supported by a case that is a non-rotating member via a bearing (not shown). The outer peripheral surface of the axle is splined to the inner peripheral surface of the rotation shaft portion 50 of the second side gear SG2 (not shown).

<Arrangement configuration of second weld W2>
The distortion of the member caused by welding in the second welded portion W2 is caused by the tooth surface 65 of the outer peripheral gear RG, the support portions of the pinion gears PG1 and PG2 in the first holding member CA1, and the first side gear SG1 in the first holding member CA1. The second welded portion W2 is disposed as far as possible from the outer peripheral gear RG or the like so as not to affect the support portion or the like as much as possible. Since the tooth surface 65 of the outer peripheral gear RG and the support portion of each gear are arranged on the reference axis first direction X1 side with respect to the pinion rotation axis PS or around the pinion rotation axis PS, the second welding portion W2 is attached. The pinion rotation axis PS may be arranged as far as possible from the reference axis second direction X2 side.

  In the present embodiment, the second welded portion W2 is on the side away from the pinion rotation axis PS in the reference axis direction X (reference axis second direction X2 side) with respect to the sliding surface 22 between the holding member CA and the pinion gears PG1 and PG2. ). The second holding member CA2 and the pinion gears PG1 and PG2 are not in contact with each other, and the second holding member CA2 does not include the sliding surface 22 with the pinion gears PG1 and PG2. The first holding member CA1 includes a sliding surface 22 with the pinion gears PG1 and PG2.

The pinion gear support portion 27 extends toward the reference axis second direction X2 side with respect to the sliding surface 22 with the pinion gears PG1 and PG2, and the extension portion extends to an end portion to which the second holding member CA2 is attached. Part 23. The inner peripheral surface of the end extension 23 is formed in an intermittent cylindrical shape provided with the notch 31, and the gear support wall of the second holding member CA <b> 2 is formed on the inner peripheral surface of the end extension 23. The outer peripheral surface of the part 40 is fitted. The second welded portion W2 is formed at an end portion on the reference axis second direction X2 side in a contact portion between the inner peripheral surface of the end extension portion 23 and the outer peripheral surface of the gear support wall portion 40. That is, the second welded portion W2 is provided at the end on the reference axis second direction X2 side in the pinion gear support portion 27 that extends to the reference axis second direction X2 side with respect to the sliding surface 22.
Thus, the first holding member CA1 extends to the reference axis second direction X2 side with respect to the sliding surface 22 in order to separate the second welding portion W2 from the pinion rotation axis PS as much as possible to the reference axis second direction X2 side. It is configured to issue.

Further, the first holding member CA1 includes a tapered portion 20 in which the thickness of the member decreases along the reference axial direction X from the center position C side toward the second welding portion W2 with the second holding member CA2. Yes.
In the present embodiment, the end extending portion 23 is a tapered portion 20. That is, the end extension 23 is formed such that the thickness of the radial member decreases as it goes in the second reference axis direction X2. For this reason, the end part extension part 23 becomes easy to deform | transform as it goes to the reference axis second direction X2. The second welded portion W2 is provided at the distal end portion (the end portion on the reference axis second direction X2 side) of the tapered portion 20 in which the thickness of the member is reduced.

  Even if distortion (deformation) occurs due to welding in the second welded portion W2, the amount of distortion (deformation amount) at the tip of the tapered portion 20 increases, and the root of the tapered portion 20 (reference axis first direction X1 side). As it goes, the amount of strain decreases. In this way, by deforming the tip portion of the tapered portion 20, it is possible to absorb the influence of distortion due to welding and prevent the influence of the distortion from being transmitted to the reference shaft first direction X <b> 1 side of the tapered portion 20.

<Arrangement configuration of first weld W1>
The first holding member CA1 includes a gear attachment portion 21 to which the outer peripheral gear RG is attached on the reference axis first direction X1 side with respect to the pinion rotation axis PS. In the present embodiment, the gear attachment portion 21 extends from the portion on the reference axis first direction X1 side with respect to the pinion rotation axis PS in the pinion gear support portion 27 to the radially outer side and the reference axis first direction X1 side. . The gear attachment portion 21 includes an attachment fitting surface 29 on which the outer peripheral gear RG is fitted. In the present embodiment, the mounting fitting surface 29 is a cylindrical outer peripheral surface provided on the radially outer side of the gear mounting portion 21 and is disposed coaxially with the rotational axis A of the holding member CA. .

  The outer peripheral gear RG includes a holding member attaching portion 63 attached to the first holding member CA1. The holding member attachment portion 63 includes a gear fitting surface 60 that is fitted to the attachment fitting surface 29 of the gear attachment portion 21. In the present embodiment, the gear fitting surface 60 is a cylindrical inner peripheral surface provided on the radially inner side of the holding member mounting portion 63 and is arranged coaxially with the rotation axis A of the holding member CA. ing. Further, the holding member mounting portion 63 protrudes radially inward on the reference axis second direction X2 side with respect to the gear fitting surface 60 and is in a cylindrical shape that contacts the surface of the gear mounting portion 21 on the reference axis second direction X2 side. The flange part 61 is provided.

  The first welded portion W1 is formed at the end portion on the reference axis first direction X1 side in the contact portion between the attachment fitting surface 29 and the gear fitting surface 60. That is, the first welding portion W1 is provided at the end on the reference axis first direction X1 side in the gear mounting portion 21 extending from the pinion gear support portion 27 in the reference axis first direction X1. Thus, the first welded portion W1 is separated as much as possible from the support portions of the pinion gears PG1 and PG2, the support portion of the first side gear SG1 and the second welded portion W2 in the first holding member CA1, and the weld in the first welded portion W1. The distortion of the member caused by the above can be prevented from affecting these as much as possible.

  In this embodiment, the gear attachment part 21 is provided with the taper part 30 from which the thickness of a member reduces as it goes to the reference axis 1st direction X1 in which the 1st welding part W1 was provided. Moreover, the holding member attaching part 63 also includes a tapered part 62 in which the thickness of the member decreases as it goes in the reference axis first direction X1 where the first welded part W1 is provided. For this reason, the gear attachment portion 21 and the holding member attachment portion 63 are easily deformed as they go in the reference axis first direction X1. The first welded portion W1 is provided at the tip end portions (end portions on the reference axis first direction X1 side) of the tapered portions 30 and 62 whose thickness is reduced.

  Even if distortion (deformation) is caused by welding in the first welded portion W1, the amount of distortion (deformation amount) at the tip of the tapered portions 30 and 62 becomes large, and the root of the tapered portions 30 and 62 (second direction of the reference axis) The strain amount decreases toward the X2 side). In this way, by deforming the tip portions of the tapered portions 30 and 62, the influence of strain due to welding is absorbed, and the influence of the strain can be prevented from being transmitted to the reference axis second direction X2 side of the tapered portions 30 and 62. .

  The outer peripheral gear RG has a tooth portion 64 that forms a tooth surface 65. In the present embodiment, the tooth portion 64 extends radially outward from the holding member attachment portion 63 and is formed in a cylindrical shape. The tooth portion 64 is arranged coaxially with the rotation axis A of the holding member CA. The tooth surface 65 is formed on the outer peripheral surface of the tooth portion 64.

3. Manufacturing Method of Differential Gear Device 1 As shown in FIG. 3, the differential gear device 1 includes a first welding process # 03, a tooth polishing process # 04, a gear assembly process # 05, a second welding process # 06, and the like. It is produced by the manufacturing method provided with.
In the first welding step # 03, the first holding member CA1 and the outer peripheral gear RG are welded. In the tooth polishing step # 04, the tooth surface 65 of the outer peripheral gear RG is polished after the first welding step # 03. In the gear assembly step # 05, after the tooth polishing step # 04, the plurality of differential gears 2 are assembled to the first holding member CA1. In the second welding step # 06, after the gear assembling step # 05, the welded portion (first welding step # 03) in the reference axial direction X, which is a direction parallel to the rotational axis A of the holding member CA. The first holding member CA1 and the second holding member CA2 are welded on the opposite side (reference axis second direction X2 side) across the center position C of the differential gear mechanism 3 with respect to the portion W1).

  In the present embodiment, the manufacturing method of the differential gear device 1 includes a forging process # 01 in which the outer peripheral gear RG, the first holding member CA1, and the second holding member CA2 are formed by forging before the first welding process # 03. It has. Further, in the manufacturing method of the differential gear device 1, the carburizing process and the quenching process are performed on at least the tooth surface 65 of the outer peripheral gear RG after the forging process # 01 and before the first welding process # 03. A carburizing and quenching process # 02 is provided.

  In the forging process # 01, as described above, the base material for the outer peripheral gear RG that matches the characteristics required for each of the outer peripheral gear RG, the first holding member CA1, and the second holding member CA2, the first A base material for the holding member CA1 and a base material for the second holding member CA2 are prepared. Thereafter, each base material is plastically deformed by forging to form each member. After forging, portions that require machining accuracy, such as the tooth surface 65 of the outer peripheral gear RG and the fitting surfaces and sliding surfaces of each member, are formed by cutting.

  In the carburizing and quenching processing step # 02, carburizing and quenching are performed on the outer peripheral gear RG to form a carburized layer having a carbon concentration and hardness higher than that of the inside on at least the tooth surface 65 of the outer peripheral gear RG.

  In the first welding step # 03, after the outer peripheral gear RG is assembled to the first holding member CA1, the first holding member CA1 and the outer peripheral gear RG are welded at the first welding portion W1. In this embodiment, after fitting the attachment fitting surface 29 of the first holding member CA1 and the gear fitting surface 60 of the outer peripheral gear RG, the laser beam of the laser welding machine is emitted from the reference axis first direction X1 side. Irradiation is performed toward the contact portion between the attachment fitting surface 29 and the gear fitting surface 60. And the edge part by the side of the reference axis 1st direction X1 in the contact part of the attachment fitting surface 29 and the gear fitting surface 60 is welded, and the 1st welding part W1 is formed. At the time of this welding, after attaching the first holding member CA1 to the support mechanism of the welding apparatus, the first holding member CA1 is rotated or the laser welding machine is moved in the circumferential direction so that the contact portion is circumferentially moved. Weld to. As the welding machine, in addition to laser welding, electron beam welding, friction stir welding, plasma welding, TIG welding, or the like may be used.

  In the tooth polishing step # 04, the tooth surface 65 of the outer peripheral gear RG is polished in order to correct distortion or the like caused by welding in the first weld W1. At this time, the fitting surface, the sliding surface, and the like of the first holding member CA1 may be polished to correct distortion due to welding. In addition, after the polishing, the outer peripheral gear RG and the first holding member CA1 are cleaned in order to remove chips generated by the polishing.

  In the gear assembly step # 05, after the tooth polishing step # 04, the plurality of differential gears 2 are assembled to the first holding member CA1. In the present embodiment, first, the first side gear SG1 is inserted into the first holding member CA1 through the opening on the reference axis second direction X2 side of the first holding member CA1 (end extension portion 23) and assembled. . Thereafter, the pinion gears PG1 and PG2 are inserted into the first holding member CA1 through the opening of the first holding member CA1, and then disposed, and then the pinion rotation shaft PS is connected to the through hole of the first holding member CA1 and the pinion gears PG1 and PG2. After that, the pinion rotation shaft PS is fixed to the first holding member CA1 by caulking or the like. And 2nd side gear SG2 is inserted and arrange | positioned in 1st holding member CA1 from the opening part of 1st holding member CA1.

  In the second welding step # 06, after the second holding member CA2 is assembled to the first holding member CA1, in the reference axis direction X, the first welding part W1 is disposed on the opposite side across the pinion rotation axis PS. In the second welding part W2, the first holding member CA1 and the second holding member CA2 are welded. In this embodiment, after fitting the inner peripheral surface of the end extension 23 of the first holding member CA1 and the outer peripheral surface of the gear support wall portion 40 of the second holding member CA2, the laser of the laser welding machine is used. The light beam is irradiated from the reference axis second direction X2 side toward the contact portion between the inner peripheral surface of the end extension portion 23 and the outer peripheral surface of the gear support wall portion 40. Then, the end on the reference axis second direction X2 side at the contact portion between the inner peripheral surface of the end extension 23 and the outer peripheral surface of the gear support wall 40 is welded to form the second weld W2. Is done. At the time of this welding, after attaching the first holding member CA1 to the support mechanism of the welding apparatus, the first holding member CA1 is rotated or the laser welding machine is moved in the circumferential direction so that the contact portion is circumferentially moved. Weld to. As the welding machine, in addition to laser welding, electron beam welding, friction stir welding, plasma welding, TIG welding, or the like may be used.

[Other Embodiments]
Finally, other embodiments of the present invention will be described. Note that the configuration of each embodiment described below is not limited to being applied independently, and can be applied in combination with the configuration of other embodiments as long as no contradiction arises.

(1) In the above embodiment, the case where the base material of the outer peripheral gear RG is made of a material having higher hardness than the base material of the first holding member CA1 has been described as an example. However, the embodiment of the present invention is not limited to this. That is, the base material of the outer peripheral gear RG may be the same material as the base material of the first holding member CA1 or a material having a lower hardness.

(2) In the above embodiment, the case where the outer peripheral gear RG has a carburized layer having a higher carbon concentration and hardness than the inside at least on the tooth surface 65 has been described as an example. However, the embodiment of the present invention is not limited to this. That is, the outer peripheral gear RG may have a carburized layer in a portion other than the tooth surface 65 or may not have a carburized layer on the tooth surface 65.

(3) In the above embodiment, the first holding member CA1, the second holding member CA2, and the outer peripheral gear RG have been described as an example of a forged part. However, the embodiment of the present invention is not limited to this. That is, one or more of the first holding member CA1, the second holding member CA2, and the outer peripheral gear RG may be a part formed by a method other than forging, for example, casting or cutting.

(4) In said embodiment, 1st holding member CA1 is equipped with the taper part 20 from which the thickness of a member reduces as it goes to the 2nd welding part W2 from the center position C side along the reference-axis direction X. An example has been described. However, the embodiment of the present invention is not limited to this. That is, the first holding member CA1 does not include the tapered portion 20, and is configured such that the thickness of the member does not change from the center position C side toward the second welded portion W2 along the reference axis direction X. On the contrary, the thickness of the member may be increased.

(5) In the above embodiment, the outer peripheral surface of the second holding member CA2 is fitted to the inner peripheral surface of the end portion (end portion extending portion 23) on the reference axis second direction X2 side of the first holding member CA1. And the case where the edge part by the side of the reference axis 2nd direction X2 in the contact part of an inner peripheral surface and an outer peripheral surface was welded was demonstrated as an example. However, the embodiment of the present invention is not limited to this. That is, the second welded portion W2 only needs to be provided on the side opposite to the first welded portion W1 across the center position C of the differential gear mechanism 3 in the reference axis direction X. In a state where the end surface on the reference axis first direction X1 side of the second holding member CA2 is in contact with the end surface on the reference axis second direction X2 side of the member CA1, the end portion on the radially outer side in the contact portion between the end surfaces is welded. And may be the second weld W2.

(6) In the above embodiment, the first welded portion W1 is formed at the end on the reference axis first direction X1 side in the contact portion between the attachment fitting surface 29 and the gear fitting surface 60. Described as an example. However, the embodiment of the present invention is not limited to this. That is, the first welded portion W1 only needs to be provided on the side opposite to the second welded portion W2 across the center position C of the differential gear mechanism 3 in the reference axis direction X. The portion W1 may be formed at the end portion on the reference axis second direction X2 side in the contact portion between the attachment fitting surface 29 and the gear fitting surface 60.

(7) In the above embodiment, the second welded portion W2 is on the side away from the pinion rotation axis PS in the reference axis direction X with respect to the sliding surface 22 between the holding member CA and the pinion gears PG1 and PG2 (reference axis first The case where it is provided on the two directions X2 side) has been described as an example. However, the embodiment of the present invention is not limited to this. That is, the second welded portion W2 only needs to be provided on the side opposite to the first welded portion W1 across the center position C of the differential gear mechanism 3 in the reference axis direction X. For example, the holding member CA And the pinion gear PG1, PG2 may be provided at a position overlapping with the portion on the reference axis second direction X2 side with respect to the pinion rotation axis PS on the sliding surface 22 in the radial direction. In this case, the second holding member CA2 also includes a sliding surface 22 with the pinion gears PG1 and PG2, and the contact portion between the first holding member CA1 and the second holding member CA2 is the first holding member CA1. You may be located between the sliding surface 22 and the sliding surface 22 of 2nd holding member CA2.

(8) In the above embodiment, the case where the first holding member CA1 has the notch 31 has been described as an example. However, the embodiment of the present invention is not limited to this. That is, the first holding member CA1 may not have the notch portion 31.

(9) In the above embodiment, the case where the notches 31 are provided at two locations in the circumferential direction has been described as an example. However, the embodiment of the present invention is not limited to this. That is, the cutout portion 31 may be provided in any number of one or more in the circumferential direction.

(10) In the above embodiment, the first holding member CA1 and the outer peripheral gear RG are joined by welding at the first welded portion W1, and the first holding member CA1 and the second holding member CA2 are joined by welding. The case where it couple | bonds with the welding part W2 was demonstrated as an example. However, the embodiment of the present invention is not limited to this. That is, the first holding member CA1 and the outer peripheral gear RG may be coupled by a method other than welding, for example, press fitting, shrink fitting, caulking, or the like. Further, when press-fitting or shrink-fitting, the press-fitting portion may be formed in a spline shape.
Even in this case, the second welded portion W2 that is the coupling portion between the first holding member CA1 and the second holding member CA2 can be separated from the outer peripheral gear RG, and the strain generated by welding in the second welded portion W2 can be reduced. The influence can be made difficult to be transmitted to the tooth surface 65 of the outer peripheral gear RG, the deterioration of the accuracy of the position (roundness etc.) of the tooth surface 65 of the outer peripheral gear RG can be suppressed, and the processing accuracy in the subsequent processing is deteriorated. It is possible to obtain the same effect as that of the above-described embodiment that it can be suppressed.

  The present invention includes a differential gear mechanism having a plurality of differential gears that mesh with each other, a holding member that holds a rotating shaft of the plurality of differential gears, and an outer peripheral gear fixed to the outer periphery of the holding member. It can utilize suitably for the provided differential gear apparatus and its manufacturing method.

1: differential gear device 2: differential gear 3: differential gear mechanism 4: rotating shaft 20 of the differential gear: taper portion 21: gear mounting portion 22: sliding surface 23 between the holding member and the pinion gear 23: end extension Protruding portion 24: Gear support wall portion 27: Pinion gear support portion 29: Mounting fitting surface 31: Notch portion 65: Tooth surface A of outer peripheral gear A: Rotational axis C of holding member C: Center position CA of differential gear mechanism: Holding Member CA1: First holding member CA2: Second holding member PG: Pinion gear (first bevel gear)
PG1: First pinion gear PG2: Second pinion gear PS: Pinion rotation shaft (first rotation shaft)
RG: outer peripheral gear SG: side gear (second bevel gear)
SG1: First side gear SG2: Second side gear W1: First welded portion W2: Second welded portion X: Reference axis direction X1: Reference axis first direction X2: Reference axis second direction

Claims (13)

A differential gear mechanism comprising: a differential gear mechanism having a plurality of differential gears that mesh with each other; a holding member that holds a rotating shaft of the plurality of differential gears; and an outer peripheral gear fixed to the outer periphery of the holding member. A gear device,
The holding member has a first holding member and a second holding member,
The outer peripheral gear includes a holding member attaching portion that is attached to the first holding member, and is a member toward the holding member attaching portion toward one side in a reference axis direction that is a direction parallel to the rotation axis of the holding member. Has a tapered portion that decreases in thickness,
The first holding member and the tapered portion of the outer peripheral gear are welded at a first welded portion;
The first holding member and the second holding member are welded at a second weld,
Wherein the first weld and the second weld portion in the reference axis direction, the sides of the center position of the differential gear mechanism, a differential gear device on the opposite side to each other.   The differential gear device according to claim 1, wherein the base material of the outer peripheral gear is made of a material having higher hardness than the base material of the first holding member.   3. The differential gear device according to claim 1, wherein the outer peripheral gear has a carburized layer having a carbon concentration and hardness higher than that of the inside at least on a tooth surface.   The differential gear device according to any one of claims 1 to 3, wherein the first holding member, the second holding member, and the outer peripheral gear are forged parts. The first holding member includes a first tapered portion in which the thickness of the member decreases from the center position side toward one side in the reference axis direction,
5. The differential gear according to claim 1, wherein the first welded portion is provided across a distal end portion of the first tapered portion and a distal end portion of the tapered portion of the outer peripheral gear. apparatus. Wherein the first holding member, wherein the pre-Symbol center position side in any one of the reference axis direction of the other side a second tapering portion whose thickness is reduced member from claim 1, comprising a toward the 5 Differential gear unit. The differential gear mechanism is a shaft that is held by the first holding member, the axis of which is perpendicular to the rotation axis of the holding member, and the holding member by the first rotating shaft. has a first bevel gear which is rotatably supported and is rotatably supported with respect to the holding member and the second bevel gear together meshing with said first bevel gear, a relative,
Wherein the first weld and the second weld portion in the reference axis direction, across the first rotation axis, according to any one of claims 1 to 6 on the opposite side to each other Differential gear unit. The first welded portion and the second welded portion are, in the reference axis direction, the first rotating shaft, the first bevel gear, and the body portion of the second bevel gear constituting the differential gear mechanism. The differential gear device according to claim 7, wherein the differential gear device is provided on opposite sides of the whole. The second weld, the relative sliding surfaces of the holding member and the first bevel gear, according to claim 7 or 8 is provided on the side away from the first rotation axis in the reference axis direction Differential gear unit. The first holding member has a cutout portion formed so as to avoid a holding portion that holds the rotation shafts of the plurality of differential gears, and the cutout portion extends from the first welded portion side to the second welded portion. The differential gear device according to any one of claims 1 to 9 , wherein the differential gear device opens in a direction toward the side. A differential gear mechanism having a plurality of differential gears meshing with each other; a holding member having a first holding member and a second holding member, each of which holds a rotation shaft of the plurality of differential gears; An outer peripheral gear fixed to the outer periphery of the member, and the outer peripheral gear includes a holding member attachment portion attached to the first holding member, and is parallel to the rotation axis of the holding member on the holding member attachment portion. A method for manufacturing a differential gear device having a tapered portion in which the thickness of a member decreases toward one side of a reference axis direction that is a different direction ,
A first welding step of welding the first holding member and the tapered portion of the outer peripheral gear;
A tooth polishing step for polishing the tooth surface of the outer peripheral gear after the first welding step;
After the tooth polishing step, a gear assembly step for assembling the plurality of differential gears to the first holding member;
After the gear assembly step, in the reference axis direction, the opposite side across the center position of the differential gear mechanism, the second holding said first holding member with respect to the welding portion of the first welding process The manufacturing method of the differential gear apparatus which performs the 2nd welding process of welding a member. The method for manufacturing a differential gear device according to claim 11 , wherein carburizing treatment and quenching treatment are performed on at least a tooth surface of the outer peripheral gear before the first welding step. The manufacturing method of the differential gear apparatus of Claim 11 or 12 which performs the forge molding process which shape | molds the said outer periphery gear, said 1st holding member, and said 2nd holding member by forge.

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