Element connection structure

Abstract

Element connection structure for a differential device comprising: a ring gear (30, 130, 230, 235) including a helical gear portion (31, 131, 231, 234) extending in a rotation axis direction; a differential case (10, 110, 210, 215) rotating with the ring gear (30, 130, 230, 235); and a first connecting portion (31, 132, 212, 236) arranged at a first position on a rear side portion corresponding to one end (31a, 131a) of a rotation axis of the ring gear (30, 130, 230, 235) and connecting the differential case (10, 110, 210, 215) and the ring gear (30, 130, 230, 235) and a second connecting portion (12, 112, 213, 237) arranged at a second position on a rear side portion corresponding to another end (31b, 131b) in the rotation axis direction of the ring gear (30, 130, 230, 235) and connecting the differential case (10, 110, 210, 215) and the ring gear (30, 130, 230, 235); wherein the first connecting portion (31, 132, 212, 236) and the second connecting portion (12, 112, 213, 237) are spaced apart from each other with a cavity (40) therebetween, and wherein the ring gear (30, 130, 230, 235) including the first connecting portion (31, 132, 212, 236) has an L-shape in a cross-section along the rotation axis, and wherein the first connecting portion (31, 132, 212, 236) is formed integrally with the ring gear (30, 130, 230, 235) and the second connecting portion is formed integrally with the differential case (10, 110, 210, 215); and wherein a first end of the first connecting portion (31, 132, 212, 236) on one side of the differential housing (10, 110, 210, 215) and a portion of the differential housing (10, 110, 210, 215) opposite the first end are connected to each other, and a second end of the second connecting portion on one side of the ring gear (30, 130, 230, 235) and a portion of the ring gear (30, 130, 230, 235) opposite the second end are connected to each other, and wherein the ring gear (30, 130, 230, 235) and the differential case (10, 110, 210, 215) are welded together at the first position and the second position.

Description

Technical area

[0001] The present invention relates to an element connection structure for a differential device, and more particularly to a connection structure between a ring gear and a differential case that rotates with the ring gear. background

[0002] Conventionally, a differential device is known that includes a ring gear and a differential case that rotates with the ring gear. This type of differential device is disclosed, for example, in WO 2011 / 089706 A1.

[0003] WO 2011 / 089706 A1 discloses a welded structure between elements, namely a differential case included in a differential device of a vehicle, and a ring gear connected to the differential case. In the cross-sectional structure of this welded structure, a single-flange connecting portion protrudes (radially inward) from a center surface along the rotational axis on the rear side of the ring gear opposite a tooth portion thereof toward the differential case. These elements are welded together, while the distal end of the connecting portion abuts against the gear connecting portion of the opposite differential case.

[0004] The ring gear is formed of a helical gear with a helical tooth track having a predetermined helix angle. Accordingly, a thrust load in the direction of the rotation axis of the ring gear is continuously applied to the ring gear while the ring gear is engaged with an output gear that transmits torque from the internal combustion engine. As a result, due to the thrust load continuously applied to the ring gear, the ring gear is sometimes tilted in the direction of the rotation axis around a portion welded to the differential case as a fulcrum (the ring gear swings), and thus deformed. In conventional cases, the connecting portion on the back of the ring gear is formed to have a certain thickness level in the direction of the rotation axis of the ring gear to prevent such deformation.

[0005] Furthermore, DE 10 2015 224 050 A1 discloses a differential gear that distributes torque transmitted to a differential case to a pair of output shafts by means of a differential mechanism housed in the differential case. The drive element and the cover parts that comprise the differential case are connected by welding and press-fitting. Distortion caused by welding and press-fitting can be suppressed, which in turn increases the assembly accuracy of the differential gear. Summary of the inventionProblem to be solved by the invention

[0006] In the welded structure between a differential case and a ring gear in the differential case disclosed in WO 2011 / 089706, it appears necessary for the connecting portion of the ring gear to have an increased thickness and a stable structure in order to prevent tilting deformation of the ring gear formed of a helical gear due to the thrust load applied to the ring gear. Accordingly, if the connecting portion has an increased thickness, the weight of the differential device including the ring gear is increased.

[0007] The present invention has been made to solve the above problem, and an object of the present invention is to provide an element connection structure for a differential device which can suppress tilting deformation in the direction of the rotation axis due to a thrust load while suppressing an increase in weight. Means to solve the problem

[0008] To achieve the above object, an element connection structure for a differential device according to an object of the present invention includes: a ring gear including a helical gear portion extending in a rotation axis direction; a differential case rotating with the ring gear; and a first connection portion disposed at a first position on a back side portion corresponding to one end of a rotation axis of the ring gear and connecting the differential case and the ring gear; and a second connection portion disposed at a second position on a back side portion corresponding to another end in the rotation axis direction of the ring gear and connecting the differential case and the ring gear. The first connection portion and the second connection portion are spaced apart from each other with a cavity therebetween.

[0009] As described above, in the element connection structure for a differential device according to one object of the present invention, the ring gear and the differential case are connected to each other at the first position on a back portion corresponding to one end of the rotation axis of the ring gear including the helical gear portion, and at the second position on a back portion corresponding to the other end in the rotation axis direction of the ring gear. Accordingly, the ring gear can be connected to the differential case at two locations, namely, the first position on a back portion corresponding to one end and the second position on a back portion corresponding to the other end of the rotation axis. Therefore, it is possible to ensure the rigidity of the element connection structure at two locations where strength is required, namely, the first position and the second position.Thus, even in the case where the area between the first position and the second position is a cavity (lightening portion), tilting deformation of the ring gear in the rotational axis direction due to the thrust load applied to the ring gear (helical gear) can be suppressed. As a result, it is possible to suppress tilting deformation of the ring gear in the rotational axis direction due to the thrust load while simultaneously suppressing weight increase by providing the cavity portion (lightening portion). Effects of the invention

[0010] According to the present invention, as described above, it is possible to suppress tilting deformation of a ring gear in a rotational axis direction due to a thrust load while simultaneously suppressing weight increase. Brief Description of the Figures Fig. 1 schematically illustrates the configuration of a vehicle-mounted differential device and the parts therearound according to a first embodiment of the present invention. Fig. 2 is a cross-sectional view illustrating a connection structure between a differential case and a ring gear included in the differential device according to the first embodiment of the present invention. Fig. 3 is a partial cross-sectional view illustrating a connection structure between a differential case and a ring gear included in the differential device according to a modification of the first embodiment of the present invention. Fig. 4 is a partial cross-sectional view illustrating a connection structure between a differential case and a ring gear included in the differential device according to a second embodiment of the present invention. Fig. 5 is a partial cross-sectional view illustrating a connection structure between a differential case and a ring gear included in the differential device according to a modification of the second embodiment of the present invention. Fig. 6 is a partial cross-sectional view illustrating a connection structure between a differential case and a ring gear included in the differential device according to a third embodiment of the present invention. Embodiments of the invention

[0011] Embodiments of the present invention will be described below with reference to the drawings. First embodiment

[0012] The configuration of the differential device 100 according to a first embodiment will be described with reference to Fig. 1 and Fig. 2 described. General configuration of the vehicle and the differential device

[0013] As in Fig. As illustrated in Fig. 1, the differential device 100 according to the first embodiment of the present invention has a function of transmitting a driving force (torque) of an internal combustion engine 2 mounted on a vehicle 1 to right and left drive wheels (tires) 5a and 5b. The differential device 100 is a mechanical element part provided for generating a peripheral speed difference between a cornering inside (e.g., the drive wheel 5b) and a cornering outside (e.g., the drive wheel 5a) so that the vehicle 1 corners smoothly. In the vehicle 1, the driving force of the internal combustion engine 2 (a crankshaft 2a) is transmitted from the differential device 100 to the right and left drive wheels 5a and 5b via a transmission 3.

[0014] The differential device 100 includes a differential case 10, a pair of pinion gears 21 and 22, bevel gears 25 and 26, and a ring gear 30. The differential case 10 includes a gear receiving portion 10a that receives the four gears described above. The pinion gears 21 and 22 and the bevel gears 25 and 26 are received in the gear receiving portion 10a. The ring gear 30 (described below) is connected to a Y2-side peripheral portion (around an outer peripheral surface 11) of the differential case 10. Thus, the differential case 10 is configured to be rotated together with the ring gear 30 about a Y-axis (a rotation axis 102). The differential case 10 is rotatably supported on a support member 6 fixed to one side of a vehicle body 1a via bearing members (tapered roller bearings) 7.

[0015] A pinion shaft 23 is arranged parallel to an X-axis direction and fixed to the differential case 10 so as to extend through the gear receiving portion 10a. The pinion gears 21 and 22 are rotatably fixed to the pinion shaft 23 in a manner such that respective tooth portions oppose each other with a predetermined distance therebetween in the X-axis direction. The bevel gears 25 and 26 are arranged in the gear receiving portion 10a so as to oppose each other with a predetermined distance therebetween in the Y-axis direction perpendicular to an alignment direction of the pinion gears 21 and 22. Accordingly, the tooth portions of the pinion gears 21 and 22 and the bevel gears 25 and 26 are meshed with each other.The drive gear 5a on the Y1 side is connected to a drive shaft 9a, which is coupled to the bevel gear 25 via a constant velocity joint (not shown), while the drive gear 5b on the Y2 side is connected to a drive shaft 9b, which is coupled to the bevel gear 26 via a constant velocity joint (not shown). The Y-axis direction is an example of a "rotation axis direction" in the appended claims.

[0016] With this configuration, the driving force from the transmission 3 is transmitted to the right and left drive wheels 5a and 5b via the ring gear 30 (the differential case 10), the pinion shaft 23, the pinion gears 21 and 22, the bevel gears 25 and 26, and the drive shafts 9a and 9b. In the case where the vehicle 1 moves forward (not shown), the pinion gears 21 and 22 rotate widely around the Y-axis together with the ring gear 30 (the differential case 10). The tooth surfaces of the pinion gears 21 and 22 press and rotate the bevel gears 25 and 26 at the same peripheral speed, so that the drive wheels 5a and 5b are rotated at the same peripheral speed. Meanwhile, in the case where the vehicle 1 turns left, for example (see Fig. 1) about the Y-axis while individually rotating around the pinion shaft 23, so that the bevel gear 25 on the outer gear side (the Y1 side) rotates faster than the bevel gear 26 on the inner gear side (the Y2 side). Consequently, the drive gear 5a rotates faster than the drive gear 5b, so that the vehicle 1 turns smoothly (without resistance) to the left.

[0017] In the vehicle 1, the internal combustion engine 2 is transversely mounted so that the crankshaft 2a (indicated by dashed lines) extends in the Y-axis direction. The transmission 3 employs a multi-speed gear mechanism that changes the reduction ratio stepwise and has a rotation axis 101 parallel to the Y-axis direction (indicated by a one-dot chain line). Accordingly, an output gear (helical gear) 3a of the transmission 3 and the ring gear 30 of the differential device 100 are meshed with each other, while the rotation axis 101 of the output gear 3a and the rotation axis 102 of the ring gear 30 are arranged parallel to each other. The output gear 3a is a spur gear formed by a helical gear having a helical tooth track having a predetermined helix angle with respect to the rotation axis 101.It should be noted that the vehicle 1 is a front-wheel drive (FF) automobile in which the internal combustion engine 2 and the transmission 3 are mounted at the front in an engine compartment 1b and the front wheels (the drive wheels 5a and 5b) are driven. Internal structure of the differential device

[0018] As in Fig. As illustrated in FIG. 2, the ring gear 30 is a helical gear that can mesh with the output gear 3a. That is, the ring gear 30 includes a helical gear portion 31 extending in the rotation axis direction (the Y-axis direction) and having a helical gear track having a predetermined inclination angle with respect to the rotation axis 102 (indicated by a one-dot chain line). The ring gear 30 is formed circumferentially around the rotation axis 102. In the differential device 100, a thrust load F1 or F2 in the rotation axis direction of the ring gear 30 is continuously applied to the ring gear 30 while the ring gear 30 is meshed with the output gear (helical gear) 3a of the transmission 3. In this case, one of the thrust loads F1 and F2 is generated in the ring gear 30 in accordance with the traveling direction (the rotation direction of the ring gear 30) of the vehicle 1.

[0019] The ring gear 30 includes a support portion 32 extending radially inward on the back side of the helical gear portion 31. The support portion 32 is formed integrally with the ring gear 30 and is formed circumferentially (in a flange shape) on the back side (the radially inner side) of the helical gear portion 31 around the rotation axis 102. Accordingly, the ring gear 30 has a cross section along the rotation axis 102 (a cross section in the direction perpendicular to the paper surface in Fig. 2) an L-shape. Furthermore, the ring gear 30 includes a support end 32a disposed at a rear portion corresponding to one end 31a (on the Y1 side) of the rotation axis 102, and a connecting end 32b disposed at a rear portion corresponding to another end 31b (on the Y2 side) of the rotation axis 102. The support end 32a and the connecting end 32b are formed circumferentially around the rotation axis 102. Note that Fig. 2 only the connecting structure between the differential case 10 and the ring gear 30 and not the pinion gears 21 and 22 or the bevel gears 25 and 26 (see Fig. 1). The support portion 32 and the support end 32a are examples of a "first connecting portion" and a "first end" in the appended claims, respectively.

[0020] The differential case 10 includes a support portion 12 extending radially outward from the outer peripheral surface 11. The support portion 12 is formed integrally with the differential case 10 and is formed circumferentially (in a flange shape) on the outer peripheral surface 11 around the rotation axis 102. A support end 12b is provided at the distal end of the support portion 12, and a gear connecting portion 11a is provided on the outer peripheral surface 11 at the base portion of the support portion 12. The support portion 12 and the support end 12b are examples of a "second connecting portion" and a "second end" in the appended claims, respectively.

[0021] In the first embodiment, the ring gear 30 and the differential case 10 are welded (connected) to each other at a connection position P1 on a back side portion corresponding to one end 31a of the rotation axis 102 of the ring gear 30 including the helical gear portion 31, and a connection position P2 on a back side portion corresponding to the other end 31b in the rotation axis direction (the Y-axis direction) of the ring gear 30. That is, the support end 32a of the support portion 32 on the differential case 10 side and the gear connecting portion 11a on the outer peripheral surface 11 of the differential case 10, which faces the support end 32a, are welded to each other. Meanwhile, the support end 12b of the support portion 12 on the side of the ring gear 30 and the connecting end 32b opposite the support end 12b on the back of the other end 31b of the ring gear 30 are welded together.Thus, the support portion 32 and the support portion 12 are spaced apart by a cavity 40 therebetween. The connection positions P1 and P2 are examples of a "first position" and a "second position" in the appended claims, respectively.

[0022] The connection positions P1 and P2 are located in the same positions (in the overlapping positions) as one end 31a (the Y1 side) and the other end 31b (the Y2 side) of the rotation axis 102 of the ring gear 30 as viewed from the radial direction of the ring gear 30 (the X-axis direction). Each of the connection positions P1 and P2 further extends in the circumferential direction around the rotation axis 102 of the ring gear 30. That is, welding portions (welds) between the ring gear 30 and the differential case 10 are formed at two locations (the connection positions P1 and P2) in the circumferential direction (in an arc shape) around the rotation axis 102. Accordingly, the cavity 40 extends circumferentially around the rotation axis 102. The welding areas W between the ring gear 30 and the differential case 10 further extend at two locations (the connection positions P1 and P2) in the rotation axis direction (the Y-axis direction) of the ring gear 30.In this case, the welding areas W extend for a predetermined distance at the support end 32a and the gear connecting portion 11a (the connecting end 32b and the support end 12b) which are opposed to each other along the direction parallel to the rotation axis 102.

[0023] Furthermore, in the first embodiment, the connection position P1 between the support end 32a and the differential case 10 and the connection position P2 between the support end 12b and the ring gear 30 are different from each other in the radial direction of the ring gear 30. That is, the connection position P1 is located adjacent to the rotation axis 102 in the radial direction, and the connection position P2 is located on an outer side of the connection position P1 in the radial direction.

[0024] In the differential device 100, although the thrust load F1 or F2 is applied to the ring gear 30 while the ring gear 30 is engaged with the output gear 3a of the transmission 3, the ring gear 30 and the differential case 10 are welded together at two locations, namely the connection position P1 corresponding to one end 31a of the ring gear 30 and the connection position P2 corresponding to the other end 31b of the ring gear 30. Accordingly, although the cavity 40 is provided in the area between the support portion 32 and the support portion 12, which is not effectively utilized, it is possible to ensure the rigidity of the element connection structure at two locations where strength is required, namely the connection positions P1 and P2, so that tilting deformation of the ring gear 30 in the rotation axis direction due to the thrust load F1 or F2 is suppressed.In this way, the element connection structure for the differential device 100 of the first embodiment is configured. Effects of the first embodiment

[0025] According to the first embodiment, the following effects can be achieved.

[0026] In the first embodiment, as described above, the ring gear 30 and the differential case 10 are connected to each other at the connection position P1 on a back portion corresponding to one end 31a of the rotation axis 102 of the ring gear 30 including the helical gear portion 31, and the connection position P2 on a back portion corresponding to the other end 31b in the rotation axis direction (the Y-axis direction) of the ring gear 30. Accordingly, the ring gear 30 can be connected to the differential case 10 at two locations, namely, the connection position P1 on a back portion corresponding to one end 31a and the connection position P2 on a back portion corresponding to the other end 31b of the rotation axis 102. Therefore, it is possible to ensure the rigidity of the element connection structure at two locations where strength is required, namely, the connection positions P1 and P2.Thus, even in the case where the area between the connecting position P1 and the connecting position P2 is the cavity 40 (lightening portion), tilting deformation of the ring gear 30 in the rotational axis direction due to the thrust load F1 or F2 applied to the ring gear 30 formed of a helical gear can be suppressed. As a result, it is possible to obtain the differential device 100 capable of suppressing tilting deformation of the ring gear 30 in the rotational axis direction due to the thrust load F1 or F2 while suppressing weight increase by providing the cavity 40 (a lightening portion) (while simultaneously realizing weight reduction).

[0027] Furthermore, in the first embodiment, both connection positions P1 and P2 extend circumferentially around the rotation axis 102 of the ring gear 30. Accordingly, the ring gear 30 can be circumferentially connected to the differential case 10 at the connection positions P1 and P2 arranged in the circumferential direction, so that tilting deformation of the rotating ring gear 30 in the rotation axis direction can be more effectively suppressed. In this case, the cavity 40 (a lightening portion) can be formed between the connection position P1 and the connection position P2 in the circumferential direction, so that it is possible to maintain an appropriate weight distribution around the rotation axis 102 of the rotating ring gear 30. As a result, it is possible to reduce the weight of the differential device 100 and suppress the occurrence of vibration and the like due to uneven weight.

[0028] Furthermore, in the first embodiment, the differential device 100 is formed by welding the ring gear 30 and the differential case 10 together at the connection positions P1 and P2. Therefore, unlike the case where the ring gear 30 and the differential case 10 are fastened with, for example, a plurality of bolt members, the weight of the differential device 100 can be reliably reduced because a plurality of bolt members are not used.

[0029] Furthermore, in the first embodiment, the connection positions P1 and P2 are respectively located at the same positions as (at the overlapping positions) one end 31a and the other end 31b of the rotation axis 102 of the ring gear 30 as viewed from the radial direction of the ring gear 30. Accordingly, the differential case 10 and the ring gear 30 do not need to have such a cross-sectional shape that the connection positions are located on the outer side of the ring gear 30 in the width direction along the Y-axis direction, so it is possible to reduce the weight of the differential device 100 without adversely affecting the mountability of the differential device 100 to the vehicle body 1a.

[0030] Furthermore, in the first embodiment, the ring gear 30 is provided with the support portion 32 located at the connection position P1 and connecting the differential case 10 and the ring gear 30, while the differential case 10 is provided with the support portion 12 located at the connection position P2 and connecting the differential case 10 and the ring gear 30. The support portion 32 and the support portion 12 are spaced apart from each other with the cavity 40 therebetween. Accordingly, the differential case 10 and the ring gear 30 can be connected to each other with the support portion 32 interposed at the connection position P1 and the support portion 12 interposed at the connection position P2. Furthermore, since the cavity 40 is provided between the support portion 32 and the support portion 12, it is possible to reliably suppress an increase in the weight of the differential device 100.

[0031] Furthermore, in the first embodiment, the support portion 32 is formed integrally with the ring gear 30, and the support portion 12 is formed integrally with the differential case 10. The support end 32a of the support portion 32 on the differential case 10 side and the gear connecting portion 11a of the differential case 10 opposite the support end 32a are connected to each other, while the support end 12b of the support portion 12 on the ring gear 30 side and the connecting end 32b on the rear side of the ring gear 30 opposite the support end 12b are connected to each other. Accordingly, it is possible to connect only two members, namely the ring gear 30 including the support portion 32 and the differential case 10 including the support portion 12, so that the two members face each other in the radial direction of the ring gear 30.This simplifies the connection structure, making it possible to prevent an increase in the number of components of the differential device 100.

[0032] Furthermore, in the first embodiment, the connection position P1 between the support end 32a and the differential case 10 and the connection position P2 between the support end 32b and the ring gear 30 are different in the radial direction of the ring gear 30. Accordingly, the differential case 10 and the ring gear 30 have an asymmetric cross-sectional shape along the rotation axis 102 (the Y-axis direction), which allows the assembler to connect (weld) the ring gear 30 without an error in the connection direction (the welding direction) with respect to the differential case 10.

[0033] Furthermore, in the first embodiment, the ring gear 30 including the support portion 32 is formed to have an L-shape in a cross section along the rotation axis 102. Accordingly, the connection position P1 (the support end 32a) on a back side portion corresponding to the one end 31a of the ring gear 30 is prevented from protruding outward (the arrow Y1 direction) with respect to the one end 31a, so that it is possible to prevent the ring gear 30 from being enlarged.

[0034] Furthermore, in the first embodiment, the welding portions W between the ring gear 30 and the differential case 10 extend in the rotation axis direction (the Y-axis direction) of the ring gear 30. Accordingly, the welding portions extend for a predetermined distance at the support end 32a and the gear connecting portion 11a (the connecting end 32b and the support end 12b), which oppose each other along the direction parallel to the rotation axis 102. Moreover, the welding portions W can be arranged around the rotation axis 102. Thus, it is possible to reliably ensure the connection strength between the ring gear 30 and the differential case 10 at the connection positions P1 and P2. Modification of the first embodiment

[0035] Next, a modification of the first embodiment will be described with reference to Fig. 1 and Fig. 3. In the modification of the first embodiment, an example will be described in which a connecting structure in a differential device 150 is formed by using a ring gear 130 and a differential case 110 having shapes different from those of the first embodiment. In the drawings, the same elements as those of the first embodiment are denoted by the same reference numerals.

[0036] In the differential device 150 according to the modification of the first embodiment, as shown in Fig. 3, the ring gear 130 is welded to an outer peripheral surface 111 of the differential case 110.

[0037] The ring gear 130 integrally includes a support portion 132 extending radially inward from the back side of a helical gear portion 131. The support portion 132 extends radially inward from a back side portion corresponding to one end 131a (on the Y2 side) of a rotation axis 102 of the ring gear 130, and the ring gear 130 has an L-shape in cross section as viewed along the rotation direction. Furthermore, the ring gear 130 includes a connecting end 132a disposed at a back side portion corresponding to another end 131b (on the Y1 side) of the rotation axis, and a support end 132b disposed at a back side portion corresponding to one end 131a of the rotation axis 102. Note that Fig. 3 only the connecting structure between the differential case 110 and the ring gear 130 and not the pinion gears 21 and 22 or the bevel gears 25 and 26 (see Fig. 1). The support portion 132 and the support end 132b are examples of a "first connecting portion" and a "first end" in the appended claims, respectively.

[0038] The differential case 110 includes a support portion 112 extending radially outward from the outer peripheral surface 111. A support end 112a is provided at the distal end of the support portion 112, and a gear connecting portion 111b is provided on the outer peripheral surface 111 at the base portion of the support portion 112. The support portion 112 and the support end 112a are examples of a "second connecting portion" and a "second end" in the appended claims, respectively.

[0039] With this configuration, in the modification of the first embodiment, the ring gear 130 and the differential case 110 are welded (joined) to each other at a joining position P1 at a rear side portion corresponding to one end 131a (on the Y2 side) of the rotation axis 102 of the ring gear 130 including the helical gear portion 131, and at a joining position P2 at a rear side portion corresponding to the other end 131b (on the Y1 side) in the rotation axis direction (the Y-axis direction) of the ring gear 130. That is, the supporting end 132b of the supporting portion 132 on the differential case 110 side and the tooth connecting portion 111b opposite the supporting end 132b on the outer peripheral surface 111 of the differential case 110 are welded to each other.Meanwhile, the supporting end 112a of the supporting portion 112 on the ring gear 130 side and the connecting end 132a opposite the supporting end 112a on the back of the other end 131b of the ring gear 130 are welded together. The supporting portion 132 and the supporting portion 112 are spaced apart from each other with a circumferential cavity 40 therebetween. The other characteristics of the differential device 150 are the same as those of the first embodiment. Effects of the modification of the first embodiment

[0040] In the modification of the first embodiment, the support portion 132 is formed integrally with the ring gear 130, and the support portion 112 is formed integrally with the differential case 110. The support end 132b of the support portion 132 on the differential case 110 side and the gear connecting portion 111b opposite the support end 132b on the outer peripheral surface 111 of the differential case 110 are welded together, while the support end 112a of the support portion 112 on the ring gear 130 side and the connecting end 132a opposite the support end 112a on the back of the ring gear 130 are welded together. Accordingly, it is possible to connect only two members, namely the ring gear 130 including the support portion 132 and the differential case 110 including the support portion 112, so that the two members face each other in the radial direction of the ring gear 130.Therefore, the connection structure is simplified, making it possible to suppress an increase in the number of components of the differential device 150. The other effects are the same as those of the first embodiment. Second embodiment

[0041] Next, a second embodiment will be described with reference to Fig. 1 and Fig. 4. In the second embodiment, an example will be described in which a connecting structure in a differential device 200 is formed by using a ring gear 230 and a differential case 210 having different shapes from those of the first embodiment. In the drawings, the same elements as those of the first embodiment are denoted by the same reference numerals.

[0042] In the differential device 200 according to the second embodiment, as shown in Fig. 4 illustrates that the ring gear 230 is welded to the differential housing 210.

[0043] The ring gear 230 includes only one gear portion 232 including a helical gear portion 231. Note that the ring gear 230 includes a connecting end 232a located at a rear portion corresponding to one end 231a (on the Y1 side), and a connecting end 232b located at a rear portion corresponding to another end 231b (on the Y2 side). The connecting ends 232a and 232b are circumferentially arranged at a rear portion of the gear portion 232 with a predetermined distance therebetween in the Y-axis direction.

[0044] Meanwhile, the differential case 210 includes a pair of support portions 212 and 213 extending radially outward from an outer peripheral surface 211. A support end 212a is provided at the distal end of the support portion 212, and a support end 213b is provided at the distal end of the support portion 213. Note that Fig. 4 only the connecting structure between the differential case 210 and the ring gear 230 and not the pinion gears 21 and 22 or the bevel gears 25 and 26 (see Fig. 1). The support portions 212 and 213 are examples of a "first connecting portion" and a "second connecting portion" in the appended claims, respectively. The support end 212a and the support end 213b are examples of a "first end" and a "second end" in the appended claims, respectively.

[0045] With this configuration, in the second embodiment, the ring gear 230 and the differential case 210 are welded (joined) to each other at a joining position P1 at a rear side portion corresponding to one end 231a of the rotation axis 102 of the ring gear 230 including the helical gear portion 231, and at a joining position P2 at a rear side portion corresponding to the other end 231b in the rotation axis direction (the Y-axis direction) of the ring gear 230. That is, the support ends 212a and 213b of the support portions 212 and 213 on the opposite side of the differential case 210 and the joining ends 232a and 232b on the gear portion 232 of the ring gear 230 opposite the support ends 212a and 213b are welded to each other. The support portion 212 and the support portion 213 are spaced apart from each other with a circumferential cavity 40 therebetween.The other characteristics of the differential device 200 are the same as those of the first embodiment. Effects of the second embodiment

[0046] In the second embodiment, as described above, the support portions 212 and 213 are formed integrally with the differential case 210, and the support ends 212a and 213b of the support portions 212 and 213 on the opposite side of the differential case 210 and the connecting ends 232a and 232b on the gear portion 232 of the ring gear 230, opposite the support ends 212a and 213b, are welded together. Accordingly, it is possible to form a simple connecting structure with only two members, namely, the differential case 210 integrally including the support portions 212 and 213 and the ring gear 230, and thus suppress an increase in the number of components of the differential device 200. The other effects are the same as those of the first embodiment. Modification of the second embodiment

[0047] Next, a modification of the second embodiment will be described with reference to Fig. 1 and Fig. 5. In the modification of the second embodiment, an example will be described in which a connecting structure in a differential device 250 is formed by using a ring gear 235 and a differential case 215 having shapes different from those of the second embodiment. In the drawings, the same elements as those of the first embodiment are denoted by the same reference numerals.

[0048] In the differential device 250 according to the modification of the second embodiment, as shown in Fig. 5 illustrates that the ring gear 235 is welded to the differential housing 215.

[0049] The ring gear 235 integrally includes a support portion 236 and a support portion 237 extending radially inward on the back side of the helical gear portion 234. A support end 236a is provided at the distal end of the support portion 236, and a support end 237b is provided at the distal end of the support portion 237. Note that Fig. 5 only the connecting structure between the differential case 215 and the ring gear 235 and not the pinion gears 21 and 22 or the bevel gears 25 and 26 (see Fig. 1). Support portions 236 and 237 are examples of a "first connecting portion" and a "second connecting portion," respectively, in the appended claims. Support ends 236a and 237b are examples of a "first end" and a "second end," respectively, in the appended claims.

[0050] Meanwhile, the differential case 213 includes only one outer peripheral surface 216. Note that gear connecting portions 216a and 216b are arranged on the outer peripheral surface 216 with a predetermined distance therebetween in the Y-axis direction. The gear connecting portions 216a and 216b are arranged circumferentially on the outer peripheral surface 216 with a predetermined distance therebetween in the Y-axis direction.

[0051] With this configuration, in the modification of the second embodiment, the ring gear 235 and the differential case 215 are welded (joined) to each other at a joining position P1 at a back side portion corresponding to one end 235a (on the Y1 side) of the rotation axis 102 of the ring gear 235 including the helical gear portion 236, and at a joining position P2 at a back side portion corresponding to the other end 235b (on the Y2 side) in the rotation axis direction (the Y-axis direction) of the ring gear 235. That is, the support ends 236a and 237b of the support portions 236 and 237 on the opposite side of the ring gear 235 and the gear connecting portions 216a and 216b opposite the support ends 236a and 237b on the outer peripheral surface 216 of the differential case 215 are welded together.The support portion 236 and the support portion 237 are spaced apart from each other with a circumferential cavity 40 therebetween. The other characteristics of the differential device 250 are the same as those of the first embodiment. Effects of the modification of the second embodiment

[0052] In the modification of the second embodiment, the support portions 236 and 237 are integrally formed using the ring gear 235, and the support ends 236a and 237b of the support portions 236 and 237 on the opposite side of the ring gear 235 and the gear connecting portions 216a and 216b on the outer peripheral surface 216 of the differential case 215, which are opposite to the support ends 236a and 237b, are welded together. Accordingly, it is possible to form a simple connecting structure with only two members, namely, the ring gear 235 integrally including the support portions 236 and 237 and the differential case 215, and thus suppress an increase in the number of components of the differential device 250. The other effects are the same as those of the first embodiment. Third embodiment

[0053] Next, a third embodiment will be described with reference to Fig. 1 and Fig. 6. In the third embodiment, an example will be described in which a ring gear 230 and a differential case 215 are connected to each other by inserting connecting members provided separately. In the drawings, the same elements as those of the first embodiment are denoted by the same reference numerals.

[0054] In a differential device 300 according to the third embodiment, as shown in Fig. 6, the ring gear 230 is connected to the differential case 215.

[0055] The ring gear 230 includes only one gear portion 232 including a helical gear portion 231. That is, the ring gear 230 includes a connecting end 232a disposed at a rear portion corresponding to one end 231a, and a connecting end 232b disposed at a rear portion corresponding to another end 231b. The differential case 215 includes only one outer peripheral surface 216. That is, gear connecting portions 216a and 216b are disposed on an outer peripheral surface with a predetermined distance therebetween in the Y-axis direction. Note that Fig. 6 only the connecting structure between the differential case 215 and the ring gear 230 and not the pinion gears 21 and 22 or the bevel gears 25 and 26 (see Fig. 1) is illustrated.

[0056] In the third embodiment, the differential case 215 and the ring gear 230 are connected to each other via support members 51 and 52. That is, the connecting end 232a and an outer end 51a of the support member 21 are welded (connected) at a connecting position P1 on a back side portion corresponding to one end 231a of the rotation axis 102 of the ring gear 230 including the helical gear portion 231, while the connecting end 232b and an outer end 52b of the support member 52 are welded (connected) at a connecting position P2 on a back side portion corresponding to the other end 231b of the rotation axis 102 of the ring gear 230.An inner end 51c of the support member 51 and the gear connecting portion 216a on the outer peripheral surface 216 of the differential case 215 are welded (connected) at the connecting position P1, while an inner end 52d of the support member 52 and the gear connecting portion 216b on the outer peripheral surface 216 of the differential case 215 are welded (connected) at the connecting position P2. The support members 51 and 52 are substantially the same members and have substantially the same shape. Each of the support members 51 and 52 is formed in a circular ring shape. The support members 51 and 52 are examples of a "first connecting portion" and a "second connecting portion" in the appended claims, respectively. The outer end 51a and the inner end 51c are examples of "opposite ends" in the appended claims, and the outer end 52b and the inner end 52d are examples of "opposite ends" in the appended claims.

[0057] Accordingly, in the welded structure between the differential case 215 and the ring gear 230 in the differential device 300, these members are joined together via the support members 51 and 52 at two locations on the radial inner and outer sides at the joining position P1 and at two locations on the radial inner and outer sides at the joining position P2, that is, at a total of four welding regions W. The four welding regions W are formed in the circumferential direction. The other characteristics of the differential device 300 are the same as those of the first embodiment. Effects of the third embodiment

[0058] In the third embodiment, as described above, the support members 51 and 52 are provided separately from the ring gear 230 and the differential case 215. The ring gear 230 and the differential case 215 are connected to each other via the outer end 51a and the inner end 51c of the support member 51 and via the outer end 52b and the inner end 52d of the support member 52. Accordingly, although the universal ring gear 230 and the differential case 215 are used without a radially extending projection such as a support portion, unlike the differential devices 100 (150, 200, 250) of the above-described first and second embodiments, it is possible to form the differential device 300 using the support members 51 and 52 spaced apart from each other with a cavity 40 therebetween.According to the differential device 300, it is possible to suppress tilting deformation of the ring gear 230 in the rotation axis direction due to the thrust load F1 or F2 while simultaneously suppressing weight increase. The other effects are the same as those of the first embodiment. Modifications

[0059] The embodiments disclosed thus far are to be considered in all respects as illustrative and not restrictive. The scope of the invention is indicated by the appended claims rather than by the foregoing description of the embodiments, and all variations (modifications) which come within the meaning and range of equivalents thereof are intended to be embraced therein.

[0060] For example, in the first to third embodiments, the connection positions P1 and P2 are located at the same positions from the radial perspective as (at the overlapping positions) one end 31a (131a, 231a, 235a) and the other end 31b (131b, 231b, 235b) of the ring gear 30 (130, 230, 235). However, the present invention is not limited to this. For example, the connection positions P1 and P2 may be located at positions slightly shifted inward from one end 31a and the other end 31b of the ring gear 30 along the rotation axis 102.

[0061] Furthermore, in the first to third embodiments, the welding portions (weld seams) W between the ring gear 30 (130, 230, 235) and the differential case 10 (110, 210, 215) extend in the rotational axis direction (the Y-axis direction) of the ring gear 30. However, the present invention is not limited to this. For example, the ring gear 30 and the differential case 10 may be welded at the joining positions P1 and P2 so that the welding portions (weld seams) W extend in the radial direction of the ring gear 30. Alternatively, the welding portions W may extend in the direction intersecting (inclined to) the rotational axis direction and the radial direction.

[0062] Further, in the first to third embodiments, the present invention is applied to the differential device 100 (150, 200, 250) of the front-wheel drive (FF) vehicle 1. However, the present invention is not limited thereto. That is, the present invention can be applied to a differential device 100 of a rear-wheel drive (RR (Rear Engine, Rear Wheel Drive)) vehicle 1 in which an engine 2 and a transmission 3 are mounted in an engine compartment at the rear and the rear wheels are driven. When the ring gear 30 and the output gear 3a of the transmission 3 are helical gears that mesh with each other, the engine 2 (the crankshaft 2a) can be mounted in either the transverse direction or the vertical direction.

[0063] Furthermore, in the first to third embodiments, the differential device 100 is connected to the output gear 3a of the transmission 3 having a multi-speed power transmission mechanism. However, the present invention is not limited to this. The present invention can be applied to a differential device 100 connected to an output gear 3a of a continuously variable transmission (CVT) that continuously changes the speed ratio using a mechanism other than gears.

[0064] Furthermore, in the first to third embodiments, the present invention is applied to the differential device 100 (150, 200, 250) of the vehicle 1 having the internal combustion engine (internal combustion engine) 2 mounted thereon. However, the present invention is not limited thereto. The present invention can be applied to a differential device 100 of a hybrid vehicle that uses both an internal combustion engine 2 and an electric motor. Description of reference numbers 1 vehicle 2 combustion engine 3 gearboxes 3a Output gear 10, 110, 210, 215 differential housing 11, 111, 211, 216 outer peripheral surface 11a, 111b, 216a, 216b Gear connecting section 12, 112, 213, 237 Support section (second connecting section) 12b, 112a, 213b, 237b Supporting ends (second end) 30, 130, 230, 235 ring gear 31, 131, 231, 234 helical gear section 31a, 131a an end 31b, 131b other end 31, 132, 212, 236 support section (first connecting section) 32a, 132b, 212a, 236a Supporting ends (first end) 32b, 132a, 232a, 232b connection end 40 cavity 51 Support element (first connecting section) 51a, 52b outer end (opposite ends) 51c, 52d inner end (opposite ends) 52 Support element (second connecting section) 100, 150, 200, 250, 300 differential housing 101, 102 rotation axis F1, F2 thrust load P1 connection position (first position) P2 connection position (second position) W welding area

Claims

[1] Element connection structure for a differential device comprising: a ring gear (30, 130, 230, 235) including a helical gear portion (31, 131, 231, 234) extending in a rotation axis direction; a differential case (10, 110, 210, 215) rotating with the ring gear (30, 130, 230, 235); and a first connecting portion (31, 132, 212, 236) arranged at a first position on a rear side portion corresponding to one end (31a, 131a) of a rotation axis of the ring gear (30, 130, 230, 235) and connecting the differential case (10, 110, 210, 215) and the ring gear (30, 130, 230, 235) and a second connecting portion (12, 112, 213, 237) arranged at a second position on a rear side portion corresponding to another end (31b, 131b) in the rotation axis direction of the ring gear (30, 130, 230, 235) and connecting the differential case (10, 110, 210, 215) and the ring gear (30, 130, 230, 235); wherein the first connecting portion (31, 132, 212, 236) and the second connecting portion (12, 112, 213, 237) are spaced apart from each other with a cavity (40) therebetween, and wherein the ring gear (30, 130, 230, 235) including the first connecting portion (31, 132, 212, 236) has an L-shape in a cross-section along the rotation axis, and wherein the first connecting portion (31, 132, 212, 236) is formed integrally with the ring gear (30, 130, 230, 235) and the second connecting portion is formed integrally with the differential case (10, 110, 210, 215); and wherein a first end of the first connecting portion (31, 132, 212, 236) on one side of the differential housing (10, 110, 210, 215) and a portion of the differential housing (10, 110, 210, 215) opposite the first end are connected to each other, and a second end of the second connecting portion on one side of the ring gear (30, 130, 230, 235) and a portion of the ring gear (30, 130, 230, 235) opposite the second end are connected to each other, and wherein the ring gear (30, 130, 230, 235) and the differential case (10, 110, 210, 215) are welded together at the first position and the second position. [2] The element connection structure for a differential device according to claim 1, wherein the cavity (40) is defined by the first connection portion (31, 132, 212, 236), the second connection portion (12, 112, 213, 237), the ring gear (30, 130, 230, 235), and the differential case (10, 110, 210, 215). [3] The element connection structure for a differential device according to claim 1 or 2, wherein each of the first position and the second position extends circumferentially around the rotation axis of the ring gear (30, 130, 230, 235). [4] The element connection structure for a differential device according to any one of claims 1 to 3, wherein the first position and the second position are respectively located at the same positions as one end and the other end of the rotation axis of the ring gear (30, 130, 230, 235) as viewed from a radial direction of the ring gear (30, 130, 230, 235). [5] The element connection structure for a differential device according to any one of claims 1 to 4, wherein a connection position between the first end and the differential case (10, 110, 210, 215) and a connection position between the second end and the ring gear (30, 130, 230, 235) are different from each other in a radial direction of the ring gear (30, 130, 230, 235). [6] An element connection structure for a differential device according to any one of claims 1 to 4, wherein: the first connecting portion (31, 132, 212, 236) and the second connecting portion (12, 112, 213, 237) are formed integrally with the differential case (10, 110, 210, 215) and the ring gear (30, 130, 230, 235); and Ends of the first connecting portion (31, 132, 212, 236) and the second connecting portion (12, 112, 213, 237) on an opposite side of one of the differential case (10, 110, 210, 215) and the ring gear (30, 130, 230, 235) and portions of the other of the ring gear (30, 130, 230, 235) and the differential case (10, 110, 210, 215) opposite the ends are connected to one another. [7] The element connection structure for a differential device according to any one of claims 1 to 4, wherein the first connection portion (51) and the second connection portion (52) are provided separately from the ring gear (30, 130, 230, 235) and the differential case (10, 110, 210, 215), and the ring gear (30, 130, 230, 235) and the differential case (10, 110, 210, 215) are connected to each other via opposite ends of each of the first connection portion (51) and the second connection portion (52).

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