differential

Abstract

The present invention relates to a differential device, which comprises: a protrusion provided on a side of a differential case rotatable about a first axis; an oil introduction channel provided on the protrusion and capable of introducing lubricating oil from the outside of the differential case to a half-shaft gear support surface on the inner surface of the differential case; and a window formed on the differential case in such a manner that the inside and the outside of the differential case are communicated, wherein the inner surface (Ci) of the differential case (C) has an oil guide portion (50), the oil guide portion being axially located between the half-shaft gear support surface and at least a portion of the peripheral edge portion of the window in the circumferential direction, and at least a portion of the oil guide portion protruding from the inner surface toward the first axis (X1), and the oil guide portion guides at least a portion of the oil flowing from the half-shaft gear support surface (S1, S2) on the inner surface toward the window (18) in a manner that bypasses the window (18). Therefore, since the oil is introduced into the differential case from the oil inlet channel of the protrusion via the half-shaft gear support surface, the proportion of oil flowing axially on the inner surface of the differential case via the half-shaft gear support surface increases. In this case, the oil can also be effectively suppressed from flowing out of the window.

Description

Technical Field

[0001] The present invention relates to a differential device, and in particular to a differential device comprising a differential case, a pair of half-shaft gears, a plurality of pinion gears, a protrusion, and a window, wherein the differential case is rotatable about a first axis; the pair of half-shaft gears are supported on the differential case in a manner that allows them to freely rotate about the first axis; the plurality of pinion gears are supported on the differential case in a manner that allows them to freely rotate about at least one second axis that is orthogonal to the first axis, and the plurality of pinion gears are respectively engaged with the pair of half-shaft gears; the protrusion is protruding from a side portion of the differential case on at least one side in the axial direction along the first axis; and the window is formed on the differential case in a manner that allows the interior and exterior of the differential case to communicate. Background Art

[0002] Patent Document 1 discloses that the differential device described above is a conventionally known differential device.

[0003] In addition, in the differential device in which the half-shaft gears and the pinion gears are housed in the differential case in a manner that allows them to rotate freely, the following oil introduction structure is also a well-known structure. The oil introduction structure is provided with an oil introduction channel on the raised portion of the differential case, and the oil introduction channel can introduce oil from the outside of the differential case into the oil groove on the half-shaft gear support surface.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2008-128265 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] In the differential device of patent document 1, in order to prevent the oil introduced into the differential case from flowing toward the window side of the differential case and out of the window under the action of the centrifugal force generated by the rotation of the differential case, lubricating oil retaining lips are protruded from the peripheral edge portions of the window located on the front and rear sides in the rotation direction of the differential case.

[0009] The lip structure described above can prevent oil flowing in the rotational direction on the inner surface of the differential case from flowing out of the window, but cannot prevent oil flowing in the axial direction on the inner surface of the differential case from flowing out of the window.

[0010] Therefore, if the above-mentioned conventionally known oil introduction structure is applied to the differential device of patent document 1, the following problem will arise: the proportion of oil introduced into the differential case through the half-shaft gear support surface and flowing axially along the inner surface of the case increases, causing the oil to easily flow out of the differential case through the window.

[0011] The present invention is proposed in view of the above-mentioned situation, and aims to provide a differential device that can solve the above-mentioned problems with a simple structure.

[0012] Solutions to the problem

[0013] In order to achieve the above-mentioned purpose, the present invention relates to a differential device, the first feature of which is that it comprises: a differential case, the differential case being rotatable about a first axis; a pair of side gears, the pair of side gears being supported on the differential case in a manner that allows them to freely rotate about the first axis; a plurality of pinion gears, the plurality of pinion gears being supported on the differential case in a manner that allows them to freely rotate about at least one second axis orthogonal to the first axis, and respectively meshing with the pair of side gears; a raised portion, the raised portion being protruded from a side portion of the differential case on at least one side in an axial direction along the first axis; and an oil inlet passage, the oil inlet passage being provided on the raised portion and being capable of introducing lubricating oil from the outside of the differential case. The gear train is connected to the differential case through a guide rail and a gearbox, and the guide rail is connected to the differential case through a guide rail. The guide rail is connected to the differential case through a guide rail. The guide rail is connected to the differential case through a guide rail.

[0014] In addition, the second feature of the present invention is that, based on the first feature, a pinion lubricating oil groove is recessed on the pinion support surface, the pinion support surface is arranged on the inner surface of the differential case, and the back side of the pinion is supported so that it can rotate freely, and the pinion lubricating oil groove is open toward the inner surface of the differential case at the outer periphery of the pinion support surface.

[0015] In addition, the third feature of the present invention is that, based on the second feature, the side gear support surface is formed as a flat surface in an annular shape orthogonal to the first axis, the inner surface of the differential case has an expanded inner surface portion, and the expanded inner surface portion includes an inner surface bottom, the expanded inner surface portion connects a pair of the side gear support surfaces to each other, and the expanded inner surface portion is expanded in diameter compared with each side gear support surface, the inner surface bottom is located on the side farthest from the first axis in the expanded inner surface portion, and a weir is provided on the inner surface of the differential case between the inner surface bottom and the window, the weir protruding toward the first axis side more than the inner surface bottom, the weir forms at least a part of the oil guide portion, and the pinion lubricating oil groove opens toward the inner surface bottom.

[0016] In addition, the fourth feature of the present invention is that, on the basis of the first feature, a pinion support surface is formed on a support platform protruding from the inner surface of the differential case, the pinion support surface supports the back of the pinion so that it can rotate freely, and the pinion lubricating oil groove recessed in the pinion support surface has an opening portion opening at the outer periphery of the support platform, the inner surface of the differential case has an inner diameter changing portion and an auxiliary weir, the inner diameter changing portion is formed by expanding the axial range from the half-shaft gear support surface on one axial side to at least the opening portion toward the other axial side, the auxiliary weir is protruding from the inner surface of the inner diameter changing portion, and extends toward the window from a portion of the outer periphery of the support platform that is closer to the other axial side than the opening portion.

[0017] Effects of the Invention

[0018] According to the first feature of the present invention, the inner surface of the differential case rotating around the first axis has an oil guide portion, the oil guide portion is axially located between the half-shaft gear support surface and at least a portion of the peripheral edge portion of the window in the circumferential direction, and at least a portion of the oil guide portion protrudes from the inner surface toward the first axis side, and the oil guide portion guides at least a portion of the oil flowing from the half-shaft gear support surface toward the window on the inner surface in a manner that bypasses the window. Therefore, since the oil inlet channel of the protruding portion introduces the oil into the differential case via the half-shaft gear support surface, the proportion of the oil flowing axially through the half-shaft gear support surface and on the inner surface of the differential case increases. In this case, the oil flowing axially can also be guided in a manner that bypasses the window by the above-mentioned oil guide portion, thereby suppressing the oil from flowing out of the window, and thus the oil can be retained on the inner surface of the differential case.

[0019] In addition, according to the second feature of the present invention, a pinion lubricating oil groove is recessed in the pinion supporting surface provided on the inner surface of the differential case, and the pinion lubricating oil groove is open toward the inner surface of the differential case at the outer periphery of the pinion supporting surface. Therefore, the oil retained on the inner surface of the differential case can be effectively supplied to the pinion lubricating oil groove through the above-mentioned oil guide portion, thereby enabling the pinion supporting surface to be efficiently lubricated.

[0020] In addition, according to the third feature of the present invention, the half-shaft gear support surface is formed as a flat surface in an annular shape orthogonal to the first axis, the inner surface of the differential case has an expanded inner surface portion, and the expanded inner surface portion includes an inner surface bottom, the expanded inner surface portion connects a pair of half-shaft gear support surfaces to each other, and the expanded inner surface portion is expanded compared to each half-shaft gear support surface, and the inner surface bottom is located on the side farthest from the first axis in the expanded inner surface portion. As a result, oil introduced from the oil inlet portion through the side gear support surface is centrifugally forced to flow through the expanded inner surface portion and tend to accumulate at the bottom of the expanded inner surface portion. However, because the side gear support surface is an annular, flat surface extending radially outward, a wider axially expanded area (i.e., deeper radially outward) of the differential case inner surface is ensured compared to structures in which the side gear support surface itself gradually expands from its inner circumference to its outer circumference (e.g., differential case structures in which the side gear support surface is spherical or tapered), allowing a larger amount of oil to accumulate at the bottom of the expanded inner surface portion. Furthermore, a weir protruding toward the first axis from the inner surface bottom and the window is provided on the inner surface of the differential case, with the pinion gear lubricating oil groove opening toward this inner surface bottom. This allows the large amount of oil accumulated at the inner surface bottom to be adequately supplied to the pinion gear lubricating oil groove, effectively lubricating the pinion gear support surface.

[0021] In addition, according to the fourth feature of the present invention, a pinion support surface that supports the back of the pinion so that it can rotate freely is formed on the support platform protruding from the inner surface of the differential case, and the pinion lubricating oil groove recessed on the pinion support surface has an opening portion that opens on the outer periphery of the support platform. The inner surface of the differential case has an inner diameter changing portion and an auxiliary weir. The inner diameter changing portion is formed by expanding the axial range from the half-shaft gear support surface on one axial side to at least the opening portion toward the other axial side. The auxiliary weir is protruding from the inner surface of the inner diameter changing portion and extends toward the window from a portion of the outer periphery of the support platform that is closer to the other axial side than the opening portion. Therefore, in the case where the oil introduced from the oil inlet portion through the half-shaft gear support surface on one axial side is subjected to centrifugal force and flows toward the other axial side in the above-mentioned inner diameter change portion, since the auxiliary weir extends from a portion of the outer periphery of the support platform that is closer to the other axial side than the opening portion toward the window, the oil flowing through the inner diameter change portion between the opening portion and the window can also be captured by the auxiliary weir, so that the captured oil can be efficiently guided to the opening portion and the oil can be fully supplied to the pinion gear lubricating oil groove, thereby effectively lubricating the pinion gear support surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a longitudinal sectional view showing a differential device and its peripheral devices according to a first embodiment of the present invention (along the Figure 2 1-1 line cross-sectional view).

[0023] Figure 2 The differential mechanism and output shaft are omitted in the figure. Figure 1 Cross-sectional view of line 2-2.

[0024] Figure 3 It is from Figure 2 The present invention is a perspective view viewed in the direction indicated by arrow 3, and is a diagram showing an example of the flow of oil on the inner surface of the differential case.

[0025] Figure 4 (A) is Figure 1 An enlarged cross-sectional view of the line 4A-4A; Figure 4 (B) shows a first modification of the oil guide portion. Figure 4 (A) a cross-sectional view of the same form; Figure 4 (C) shows a second modification of the oil guide portion. Figure 4 (A) Cross-sectional view of the same form.

[0026] Figure 5 This is a cross-sectional view showing the main part of the differential case of the second embodiment (with Figure 2 corresponding figure).

[0027] Figure 6 It is from Figure 5 The present invention is a perspective view viewed in the direction indicated by arrow 6, and is a diagram showing an example of the flow of oil on the inner surface of the differential case.

[0028] Figure 7 This is a cross-sectional view showing the main part of the third embodiment (with Figure 2 corresponding figure).

[0029] Figure 8 It is from Figure 7 The present invention is a perspective view viewed in the direction indicated by arrow 8, and is a diagram showing an example of the flow of oil on the inner surface of the differential case.

[0030] Figure 9 is a schematic diagram of a modified example of the auxiliary weir observed in a direction diverging from the center of the differential case, wherein: Figure 9 (A) is a diagram showing a first modification in which the auxiliary weir is separated from the main guide weir; Figure 9 (B) is a diagram showing a second modified example in which the auxiliary weir is extended in the rotation direction of the differential case and connected to the main guide weir in the structure in which the pinion gear lubricating oil grooves are arranged in the same direction as the third embodiment; Figure 9 (C) is shown in Figure 9 FIG. 2 (B) shows a third modification example in which an auxiliary weir extends axially from the outer periphery of the pinion support surface.

[0031] Description of Reference Signs

[0032] C...Differential case

[0033] Ci...Inner surface of the differential case

[0034] Cb1, Cb2 ... bearing bosses as bosses

[0035] D...differential device

[0036] Gp... Pinion lubrication groove

[0037] Gpi...Opening of the pinion oil groove

[0038] P1…1st pinion support surface as the pinion support surface

[0039] P2…Second pinion support surface as the pinion support surface

[0040] S1…1st side gear support surface as the side gear support surface

[0041] S2…Second side gear support surface as the side gear support surface

[0042] X1…1st axis

[0043] X2…Second axis

[0044] 15, 16...Spiral grooves serving as oil inlet channels

[0045] 18...Window

[0046] 19...support platform

[0047] 22... small gear

[0048] 23... side shaft gear

[0049] 30... As the gap for the oil inlet channel

[0050] 40...Expanded inner surface

[0051] 40o... bottom of inner surface

[0052] 41 ... the first expanded inner surface portion as the inner diameter changing portion

[0053] 50... Main guide weir as oil guide

[0054] 52……The second weir as a weir

[0055] 54, 541, 542…Auxiliary weir DETAILED DESCRIPTION

[0056] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0057] First, refer to Figures 1 to 4 The first embodiment will be described. Figure 1 In the present invention, a differential device D is housed within a transmission 10 of a vehicle (e.g., an automobile). The differential device D distributes and transmits power from a power source (not shown) (e.g., an onboard engine, motor, etc.) to a pair of left and right output shafts 11 and 12. The differential device D includes a differential case C rotatable about a first axis X1 and a differential mechanism 20 incorporated within the differential case C. Furthermore, the left and right output shafts 11 and 12 are interlockingly coupled to left and right drive wheels (not shown), respectively.

[0058] In this specification and the present invention, the “axial direction” refers to a direction along the first axis X1 , and the “radial direction” refers to a radial direction of a circle having the first axis X1 as a center line.

[0059] The differential case C is formed into a first case half C1, which is roughly bowl-shaped, and a second case half C2, which is lid-shaped and closes the open end of the first case half C1. Flanges Cf1 and Cf2 are connected to the outer peripheries of the first and second case halves C1 and C2, respectively. These flanges Cf1 and Cf2 overlap with the inner flange Rb of the ring gear R and are detachably connected by a plurality of bolts 36. Furthermore, an annular concave and convex engaging portion 37 is formed on the mating surfaces of the first and second case halves C1 and C2, and fits concentrically with each other.

[0060] The teeth Ra of the ring gear R mesh with a drive gear 9, which is, for example, the output of a transmission connected to a power source. Thus, the rotational drive force from the power source is transmitted to the differential case C via the ring gear R. The ring gear R can be either a helical gear or a spur gear.

[0061] Furthermore, an internal space 17 is defined between the first case half C1 and the second case half C2. This internal space 17 functions as a mechanism chamber for housing the differential mechanism 20. In particular, a pair of windows 18 are formed in the trunk of the first case half C1, facing each other with the first axis X1 interposed therebetween. These windows 18 communicate with the interior and exterior of the differential case C. These windows 18 function not only as oil inlets and outlets but also as work windows for inserting and exiting tools, jigs, or fingers when machining the inner surface Ci of the differential case C or assembling the differential mechanism 20 therein. In the embodiment, these windows 18 are formed into a circumferentially elongated oval shape.

[0062] A cylindrical first bearing projection Cb1 and a cylindrical second bearing projection Cb2 are integrally formed on the axially outer sides of the first and second case halves C1 and C2, respectively. The first and second bearing projections Cb1 and Cb2 extend in opposite directions along the same axis. These first and second bearing projections Cb1 and Cb2 are examples of projections, and are supported on the transmission case 10 at their outer circumferences via bearings 13 and 14, respectively, for free rotation about the first axis X1.

[0063] In addition, the left and right output shafts 11 and 12 are respectively rotatably fitted and supported on the inner circumferential surface of the first bearing protrusion Cb1 and the inner circumferential surface of the second bearing protrusion Cb2 via the hollow shaft portion 23j of the side gear 23 described later, and at least one (two in the embodiment) lubricating oil introduction spiral groove 15, 16 is recessed on the inner circumferential surface of the first bearing protrusion Cb1 and the inner circumferential surface of the second bearing protrusion Cb2 (see FIG. Figure 1) Furthermore, the spiral direction of the spiral groove 15 of the first bearing protrusion Cb1 and the spiral direction of the spiral groove 16 of the second bearing protrusion Cb2 are opposite to each other.

[0064] These spiral grooves 15 and 16 provide a suction function and serve as an example of an oil introduction passage. Specifically, when the vehicle turns, as the differential mechanism 20 rotates differentially, the first and second bearing projections Cb1 and Cb2 rotate relative to the hollow shafts 23j of the left and right side gears 23. These spiral grooves 15 and 16 then draw lubricating oil from outside the differential case C into the inner surface Ci of the differential case C (particularly, the side gear support surfaces S1 and S2 described below). Guide projections g1 and g2 are provided on the outer ends of the first and second bearing projections Cb1 and Cb2, respectively. These guide projections g1 and g2 guide lubricating oil that scatters and flows around the differential case C of the transmission 10 to the upstream ends of the spiral grooves 15 and 16.

[0065] The differential mechanism 20 includes a pinion shaft 21, a pair of pinions 22, 22, and a pair of side gears 23, 23. The pinion shaft 21 is arranged on the second axis X2 and is supported on the differential case C, wherein the second axis X2 is an axis that is orthogonal to the first axis X1 at the center of the differential case C; the pair of pinions 22, 22 are engaged with and supported on the pinion shaft 21 in a manner that allows them to rotate freely; the pair of side gears 23, 23 are respectively engaged with each pinion 22 and are supported on the differential case C in a manner that allows them to rotate freely around the first axis X1.

[0066] In this embodiment, both ends of the pinion shaft 21 are engaged with pinion shaft support holes 25 provided in the trunk portion of the first case half C1, and are fixed to the differential case C by inserting fixing pins 24 attached to the trunk portion. The method for fixing the pinion shaft 21 is not limited to that described in the embodiment, and various fixing methods (e.g., riveting, screwing, etc.) may be used.

[0067] The pair of side gears 23 , 23 function as output gears of the differential mechanism 20 , and the front end portions of the pair of output shafts 11 , 12 are spline-fitted to the inner circumferences of the side gears 23 , 23 , respectively.

[0068] Each side gear 23 includes a large-diameter side gear body 23m with teeth, and a hollow shaft 23j integrally formed at the center of the back surface of the side gear body 23m. The back surface of one side gear 23 is rotatably supported, via a side gear washer Ws, on a first side gear support surface S1 connected to the inner end of the first bearing boss Cb1 on the inner surface Ci1 of the first case half C1. The back surface of the other side gear 23 is rotatably supported, via a side gear washer Ws, on a second side gear support surface S2 connected to the inner end of the second bearing boss Cb2 on the inner surface Ci2 of the second case half C2.

[0069] In this embodiment, the first side gear support surface S1 and the second side gear support surface S2 are respectively formed by annular planes perpendicular to the first axis X1. However, instead of the above planes, a conical surface or a spherical surface (see FIG. Figure 7 and Figure 8 A portion of the side gear 23 (of the third embodiment) forms a first side gear support surface S1 and a second side gear support surface S2. Furthermore, a pair of side gear lubricating oil grooves Gs are recessed on the first side gear support surface S1 and the second side gear support surface S2, respectively, extending transversely across the side gear support surfaces S1 and S2. Each pair of side gear lubricating oil grooves Gs communicates with the downstream ends of the spiral grooves 15 and 16, respectively. Furthermore, the side gear spacer Ws may be omitted. In this case, the back surface of the side gear 23 is directly supported on the first side gear support surface S1 and the second side gear support surface S2 in a rotatable and slidable manner.

[0070] Furthermore, the inner surface Ci of the differential case C includes an expanded diameter inner surface portion 40. The expanded diameter inner surface portion 40 connects the pair of side gear support surfaces S1 and S2 and is larger in diameter than the side gear support surfaces S1 and S2. The expanded diameter inner surface portion 40 includes a first expanded diameter inner surface portion 41 and a second expanded diameter inner surface portion 42. The first expanded diameter inner surface portion 41 is an annular portion corresponding to the outer circumference of the inner surface Ci1 of the first case half C1 and has a larger width in the axial direction. The second expanded diameter inner surface portion 42 is an annular portion corresponding to the outer circumference of the inner surface Ci2 of the second case half C2 and has a smaller width in the axial direction.

[0071] The first expanded diameter inner surface portion 41 includes a sharply expanded diameter inner surface portion 41a and a gently expanded diameter inner surface portion 41b. The sharply expanded diameter inner surface portion 41a expands at a steep inclination as it moves from the outer peripheral end of the first side gear support surface S1 toward the second side gear support surface S2 (i.e., the rate of increase in inner diameter is large), while the gently expanded diameter inner surface portion 41b expands at a gently inclination as it moves from the sharply expanded diameter inner surface portion 41a toward the open end of the first case half C1 (i.e., the rate of increase in inner diameter is small). Furthermore, the first expanded diameter inner surface portion 41 is an example of the inner diameter varying portion of the present invention (particularly the fourth feature), which is formed by expanding the diameter of the area from the first side gear support surface S1 on one axial side to at least the opening Gpi of the pinion gear lubricating oil groove Gp (in this embodiment, to the open end of the first case half C1) toward the other axial side.

[0072] On the other hand, the second expanded diameter inner surface portion 42 is formed solely by a rapidly expanded diameter inner surface portion that expands at a steeper inclination (i.e., with a greater rate of increase in inner diameter) as it moves from the outer peripheral end of the second side gear support surface S2 toward the open end of the second case half C2. Furthermore, the second expanded diameter inner surface portion 42 and the rapidly expanded diameter inner surface portion 41a may be portions of a spherical surface or may be tapered surfaces.

[0073] Due to the relationship between the above-mentioned expansion shapes of the first expansion inner surface portion 41 and the second expansion inner surface portion 42, the connection portion between the first expansion inner surface portion 41 and the second expansion inner surface portion 42 and its peripheral portion are formed into the deepest (i.e., the most radially concave) annular concave shape in the expansion inner surface portion 40. Moreover, this concave shape forms the inner surface bottom 40o. The oil introduced into the expansion inner surface portion 40 via the side gear support surfaces S1 and S2 propagates and flows in the first expansion inner surface portion 41 and the second expansion inner surface portion 42 when the differential case C rotates, and is gathered at the inner surface bottom 40o due to the action of centrifugal force. In this embodiment, as shown in FIG. Figure 2 、 Figure 3 As shown, the concave surface is formed into a shallow depression.

[0074] Furthermore, the back of each pinion 22 is supported by a pair of opposing support platforms 19. These support platforms 19 are concentrically positioned with the pinion shaft 21 and project from the expanded inner surface portion 40 (more specifically, the first expanded inner surface portion 41) of the differential case inner surface Ci. Specifically, the opposing top surfaces of the two support platforms 19 are formed from spherically recessed concave surfaces, thereby forming a first pinion support surface P1 and a second pinion support surface P2, which serve as pinion support surfaces. The back of each pinion 22 is supported by a pinion washer Wp in a manner that allows for rotational sliding contact with and support of each pinion support surface P1 or P2. Alternatively, the pinion washer Wp may be omitted, in which case the back of the pinion 22 is directly supported by the first and second pinion support surfaces P1 and P2, allowing for rotational sliding contact.

[0075] A pinion lubricating oil groove Gp is ​​provided on each of the first gear support surface P1 and the second pinion support surface P2. Figure 2 ) when observed, the pinion lubricating oil groove Gp extends in a straight line perpendicular to the first axis X1. Both ends of each pinion lubricating oil groove Gp function as openings Gp directly opening on the outer peripheral surface of the support 19. Figure 3 As shown, the opening Gp opens toward the inner surface bottom 40 o of the expanded diameter inner surface portion 40 .

[0076] Alternatively, the support platform 19 may not be provided protrudingly on the inner surface Ci of the differential case C, and a portion of the inner surface Ci may be used as the pinion support surface. In this case, the inner surface Ci of the differential case C near the outer periphery of the pinion support surface is slightly recessed relative to the pinion support surface. Thus, the end of the pinion lubricating oil groove Gp opens toward the inner surface Ci of the differential case C at the outer periphery of the pinion support surfaces P1 and P2 via this recessed portion.

[0077] In addition, on the projection plane perpendicular to the second axis X2 (see Figure 2 ), the pinion lubricating oil grooves Gp of each of the first pinion support surface P1 and the second pinion support surface P2 are arranged at positions axially symmetrical with respect to the first axis X1. Furthermore, in the embodiment, an example is shown in which the first pinion support surface P1 and the second pinion support surface P2 are formed as spherical concave surfaces. However, the first pinion support surface P1 and the second pinion support surface P2 may also be formed as tapered surfaces, or may be formed as flat surfaces orthogonal to the second axis X2.

[0078] Furthermore, a main guide weir 50 is provided protrudingly on the inner surface Ci of the differential case C. The main guide weir 50 guides at least a portion of the oil flowing from the first side gear support surface S1 and the second side gear support surface S2 on the inner surface Ci toward the window 18, thereby bypassing the window 18 and guiding it toward the pinion gear support surfaces P1 and P2. This main guide weir 50 forms the oil guide portion of the present invention. In the present embodiment, the main guide weir 50 is formed so as to extend along the circumference of the window 18, completely surrounding the window 18, and protrude radially inward (i.e., toward the side closer to the first axis X1) from the first expanded diameter inner surface portion 41 of the inner surface Ci.

[0079] In addition, in particular, the main guide weir 50 of the first embodiment has a first weir 51, a second weir 52, and a pair of third weirs 53. The first weir 51 is axially located between the first side gear support surface S1 on the side of the first case half C1 and the peripheral portion of the window 18 and extends along the circumferential direction of the window 18; the second weir 52 is axially located between the second side gear support surface S2 on the side of the second case half C2 and the peripheral portion of the window 18 and extends along the circumferential direction of the window 18; the pair of third weirs 53 are respectively located between the pinion support surface P1 and the peripheral portion of the window 18, and between the pinion support surface P2 and the peripheral portion of the window 18 in the circumferential direction of the differential case C, and each extends along the circumferential direction of the window 18.

[0080] The third weir 53 integrally connects the first and second weirs 51, 52 at their respective circumferential ends on one side. Furthermore, the first and second weirs 51, 52 are integrally connected at their respective circumferential ends on the other side. The connection between the third weir 53 and the first and second weirs 51, 52 is formed in an arcuate shape along the curved portion of the corresponding peripheral edge of the window 18. Furthermore, the second weir 52 is located between the inner surface bottom 40o and the window 18 at the first expanded diameter inner surface portion 41 of the differential case C, and is formed to protrude radially inward (i.e., toward the first axis X1) beyond the inner surface bottom 40o.

[0081] Next, the operation of the first embodiment will be described. When a vehicle equipped with the differential device D of this embodiment is traveling, the rotational driving force from the power source is transmitted from the ring gear R to the differential case C. This force is then distributed to the left and right output shafts 11 and 12 via the differential mechanism 20 of the differential device D, allowing for differential rotation of the left and right output shafts 11 and 12. In this state, the differential mechanism 20 does not perform differential rotation when the vehicle is traveling straight ahead. Specifically, the first and second bearing bosses Cb1 and Cb2 of the differential case C and the left and right side gears 23 (and, consequently, the output shafts 11 and 12) do not rotate relative to each other but rotate forward.

[0082] In contrast, when the vehicle turns, the left and right drive wheels have different turning radii, causing the differential mechanism 20 to rotate differentially, resulting in relative rotation between the first and second bearing bosses Cb1 and Cb2 and the left and right side gears 23. This relative rotation allows the spiral grooves 15 and 16 to exert a suction action. Consequently, oil located outside the differential case C (particularly near the outer ends of the bearing bosses Cb1 and Cb2) and guided into the spiral grooves 15 and 16 by the guide protrusions g1 and g2 flows through the spiral grooves 15 and 16 onto the side gear support surfaces S1 and S2 within the differential case C, particularly into the side gear lubricating oil groove Gs, thereby lubricating the side gear support surfaces S1 and S2, respectively. The oil that lubricates the first side gear support surface S1 and the second side gear support surface S2 flows out in a scattered manner from any position of the outer edge of each of the first side gear support surface S1 and the second side gear support surface S2 under the action of the centrifugal force generated by the rotation of the differential case C, and propagates and flows in the first expanded diameter inner surface portion 41 and the second expanded diameter inner surface portion 42.

[0083] Furthermore, the oil flowing out of the side gear support surfaces S1 and S2 propagates generally axially along the expanded diameter inner surface portion 40 of the differential case C (specifically, the first expanded diameter inner surface portion 41 and the second expanded diameter inner surface portion 42), and ultimately converges under the action of centrifugal force at the inner surface bottom 40o at the radially outermost portion of the expanded diameter inner surface portion 40. Furthermore, the opening Gpi of the pinion gear lubricating oil groove Gp faces this inner surface bottom 40o. Therefore, the oil accumulated at the inner surface bottom 40o is fully supplied to the pinion gear lubricating oil groove Gp, effectively lubricating the pinion gear support surfaces P1 and P2.

[0084] In addition, particularly in the embodiment, oil is introduced into the differential case C from the spiral grooves 15 and 16 serving as the oil introduction passages via the side gear support surfaces S1 and S2. As a result, a large proportion of the oil flows from the side gear support surfaces S1 and S2 in the axial direction (in the direction toward the window 18) on the expanded diameter inner surface portion 40. However, a main guide weir 50 is provided on the inner surface Ci of the differential case C. The main guide weir 50 guides at least a portion of the oil flowing from the side gear support surfaces S1 and S2 toward the window 18 via the expanded diameter inner surface portion 40 (specifically, the first expanded diameter inner surface portion 41 and the second expanded diameter inner surface portion 42) of the inner surface Ci of the differential case C so as to bypass the window 18. Therefore, the first weir 51 and the second weir 52 of the main guide weir 50, particularly those located between the side gear support surfaces S1 and S2 and the windows 18, can guide the oil flowing axially from the side gear support surfaces S1 and S2 on the expanded diameter inner surface portion 40 so that the oil bypasses the windows 18 and collects at the inner surface bottom 40o, thereby suppressing the oil from flowing out of the windows 18. Consequently, the oil that has already lubricated the first and second side gear support surfaces S1 and S2 can be reused to lubricate other lubricated parts within the differential case C, thereby improving the lubrication efficiency of various parts within the differential case C.

[0085] In addition, a pinion lubricating oil groove Gp is ​​recessed on the pinion support surfaces P1 and P2 provided at the inner surface Ci of the differential case C of the embodiment. The pinion lubricating oil groove Gp is ​​open toward the inner surface Ci of the differential case C at the outer periphery of the pinion support surfaces P1 and P2. Therefore, as described above, the oil guided by the main guide weir 50 in a manner bypassing the window 18 can be effectively supplied to the pinion lubricating oil groove Gp, thereby enabling the pinion support surfaces P1 and P2 to be efficiently lubricated.

[0086] Furthermore, the third weir 53 in the main guide weir 50, particularly the one located between the pinion support surfaces P1, P2 and the window 18, not only does not hinder the flow of oil that flows from the first side gear support surface S1 on one axial side, bypassing the window 18, and toward the second side gear support surface S2 on the other axial side, but also serves to prevent the oil that flows from the pinion support surfaces P1, P2 toward the window 18 and in the circumferential direction from flowing out of the window 18.

[0087] Furthermore, the side gear support surfaces S1 and S2 of the embodiment are formed as annular flat surfaces orthogonal to the first axis X1, and the inner surface Ci of the differential case C has an expanded inner surface portion 40 that connects a pair of side gear support surfaces S1 and S2 to each other and is expanded in diameter compared to each side gear support surface S1 and S2, and the expanded inner surface portion 40 includes an inner surface bottom 40o, and the oil flowing in the expanded inner surface portion 40 is gathered to the inner surface bottom 40o under the action of centrifugal force. Therefore, because the oil introduced from the spiral grooves 15 and 16 via the side gear support surfaces S1 and S2 is propagated and flows within the expanded inner surface portion 40 due to centrifugal force, the oil tends to accumulate at the radially outer inner surface bottom 40o of the expanded inner surface portion 40. However, because the side gear support surfaces S1 and S2 are annular flat surfaces extending radially outward, this allows the expanded diameter region (i.e., the radially outermost depth) of the inner surface Ci of the differential case C to be maintained over a wider axial range than in a differential case structure in which the side gear support surfaces S1 and S2 themselves gradually expand from their inner circumferential ends toward their outer circumferential ends (e.g., a differential case structure in which the side gear support surfaces S1 and S2 are spherical or tapered). Furthermore, a larger amount of oil can be accumulated at the deepest recessed inner surface bottom 40o of this region.

[0088] Moreover, a main guide weir 50 (more specifically, a second weir 52) is protruded at the inner surface Ci of the differential case C between the inner surface bottom 40o and the window 18. The main guide weir 50 (more specifically, the second weir 52) protrudes toward the first axis X1 side (i.e., radially inward) than the inner surface bottom 40o, and the pinion lubricating oil groove Gp opens toward the inner surface bottom 40o. Therefore, a large amount of oil accumulated in the inner surface bottom 40o can be fully supplied to the pinion lubricating oil groove Gp, thereby efficiently lubricating the pinion support surfaces P1 and P2.

[0089] also, Figure 5 as well as Figure 6 A second embodiment of the present invention is shown. In the first embodiment, the main guide weir 50 is shown as extending continuously around the window 18. In the second embodiment, a discontinuous region exists in a portion of the main guide weir 50 (the portion corresponding to the third weir 53 in the first embodiment).

[0090] Specifically, in the second embodiment, an auxiliary weir 54 is provided protruding from the first expanded diameter inner surface portion 41, in place of the third weir 53 of the first embodiment. This auxiliary weir 54 extends toward the window 18 from a portion of the outer periphery of the support base 19 that is axially closer to the second side gear support surface S2 than the opening Gpi of the pinion gear lubricating oil groove Gp, and smoothly connects to the first weir 51. Furthermore, both ends of the second weir 52 are connected to the outer periphery of the support base 19.

[0091] Furthermore, in the second embodiment, the two pinion gear lubricating oil grooves Gp are respectively arranged on the pinion gear support surfaces P1 and P2 so as to be parallel to each other with the second axis X2 interposed therebetween.

[0092] As described above, the first expanded inner surface portion 41 of the inner surface Ci of the differential case C forms the inner diameter variation portion of the present invention (particularly the fourth feature). This inner diameter variation portion is formed by increasing the diameter of the axial range from one axial side (in the embodiment, from the first side gear support surface S1) to at least the opening Gpi (in the embodiment, to the open end of the first case half C1) toward the other axial side. Furthermore, the auxiliary weir 54 functions to capture a portion of the oil flowing from the first side gear support surface S1 toward the second side gear support surface S2 on the first expanded inner surface portion 41, serving as the inner diameter variation portion, and guide it to the opening Gpi.

[0093] According to this second embodiment, oil introduced into the differential case C from the spiral groove 15 via the corresponding first side gear support surface S1 is subjected to the centrifugal force generated by the rotation of the differential case C and flows along the first expanded diameter inner surface portion 41 (inner diameter varying portion) toward the second side gear support surface S2. At this time, the auxiliary weir 54 captures a portion of this oil and guides it toward the opening Gpi. In this case, the auxiliary weir 54 extends from a portion of the outer periphery of the support base 19 axially closer to the second side gear support surface S2 than the opening Gpi toward the window 18. Therefore, even though the auxiliary weir 54 is oriented so that the oil flowing along the first expanded diameter inner surface portion 41 (inner diameter varying portion) toward the second side gear support surface S2 does not directly flow into the opening Gpi, the auxiliary weir 54 can still capture the oil flowing between the opening Gpi and the window 18. Furthermore, the oil captured by the auxiliary weir 54 tends to flow from the captured portion further along the first expanded diameter inner surface portion 41 (inner diameter varying portion) toward the second side gear support surface S2. Therefore, by extending the auxiliary weir 54 axially toward the first side gear support surface S1 (i.e., upstream in the direction of oil propagation and flow of the first expanded diameter inner surface portion 41), the oil captured by the auxiliary weir 54 is efficiently guided through the auxiliary weir 54 to the opening portion Gpi located toward the second side gear support surface S2 (i.e., downstream in the direction of oil propagation and flow of the first expanded diameter inner surface portion 41). As a result, the oil captured by the auxiliary weir 54 can be efficiently guided to the opening portion Gpi and sufficiently supplied to the pinion gear lubricating oil groove Gp, thereby effectively lubricating the pinion gear support surfaces P1 and P2. Furthermore, in the second embodiment, the auxiliary weir 54 is connected to the first weir 51 . Therefore, the oil captured by the first weir 51 can be guided to the opening Gpi, and the oil can be supplied to the pinion gear lubricating oil groove Gp more efficiently.

[0094] The remaining configuration of the second embodiment is substantially the same as that of the first embodiment. Therefore, the components of the second embodiment are denoted by the same reference numerals as their corresponding components of the first embodiment, and detailed descriptions of these components will be omitted. Furthermore, in the second embodiment, by providing the main guide weir 50 (particularly the first weir 51 or the second weir 52), substantially equivalent functions and effects to those of the first embodiment can be achieved.

[0095] In addition, Figure 7 and Figure 8 , a third embodiment of the present invention is shown. While in the first and second embodiments, the differential case C is divisible into a first case half C1 and a second case half C2, in the third embodiment, the differential case C is formed as a seamless, one-piece case with a spherical inner surface Ci. Furthermore, a pair of large windows 18 are provided in the body of the differential case C, allowing the side gears 23 and pinion gears 22 to be assembled within the differential case C. Furthermore, a flange Cf for securing the ring gear R is integrally formed protruding from the outer periphery of the differential case C on one side of the windows 18, along the first axis X1.

[0096] Furthermore, the left and right side gears 23 have a short boss portion 23b integrally provided at the center of the back surface of the side gear body 23m with teeth, instead of the long hollow shaft portion 23j shown in the first and second embodiments. In addition, the inner surface Ci of the differential case C has annular recesses 31, 32, half-shaft gear support surfaces S1, S2, and pinion support surfaces P1, P2. The annular recesses 31, 32 are respectively connected to the inner ends of the inner circumferential surfaces of the first bearing protrusion Cb1 and the inner ends of the inner circumferential surfaces of the second bearing protrusion Cb2, and accommodate the protrusion 23b; the half-shaft gear support surfaces S1, S2 are annular spherical and are respectively connected to the outer circumferential ends of the annular recesses 31, 32 and support the spherical back of the half-shaft gear 23 directly or via the half-shaft gear gasket Ws in a manner that allows for rotation and sliding; the pinion support surfaces P1, P2 are annular spherical and are each connected to the inner open end of the pinion shaft support hole 25, and support the spherical back of the pinion 22 directly or via the pinion gasket in a manner that allows for rotation and sliding.

[0097] Furthermore, the output shafts 11 and 12 are directly engaged with the inner circumferential surfaces of the first and second bearing bosses Cb1 and Cb2, respectively. A gap 30 is provided at these engaged portions, large enough to allow lubricating oil to flow in. This gap 30 forms an oil inlet passage that guides lubricating oil from outside the differential case C to the first and second side gear support surfaces S1 and S2 (particularly, the side gear lubricating oil grooves Gs). Although not shown, the outer ends of the first and second bearing bosses Cb1 and Cb2 of the third embodiment may also be provided with guide projections g1 and g2, similar to those of the first embodiment, for guiding lubricating oil. Furthermore, instead of the gap 30, the inner circumferential surfaces of the first and second bearing bosses Cb1 and Cb2 may also be provided with oil inlet passages, similar to those of the first embodiment, namely, spiral grooves 15 and 16.

[0098] Furthermore, in the third embodiment, the pinion gear lubricating oil groove Gp and the side gear lubricating oil groove Gs are also recessed in the inner surface Ci of the differential case C. In particular, unlike the first and second embodiments, the projection plane perpendicular to the second axis X2 (see FIG. Figure 7 ), the pinion gear lubricating oil groove Gp extends parallel to the first axis X1. Furthermore, the pinion gear lubricating oil groove Gp and the side gear lubricating oil groove Gs are formed into grooves arranged on an arc centered on the spherical center CX passing through the differential case inner surface Ci and the specific axis X3 of the window 18.

[0099] In addition, a main guide weir 50 serving as an oil guide portion is protruded from the inner surface Ci of the differential case C. The main guide weir 50 serving as the oil guide portion guides at least a portion of the oil flowing from the first side gear support surface S1 and the second side gear support surface S2 toward the window 18 on the inner surface Ci to the pinion support surfaces P1 and P2 in a manner that bypasses the window 18.

[0100] The main guide weir 50 of the third embodiment is formed by a pair of weir-forming steps 60. These steps 60 protrude radially inward, that is, toward the side closer to the first axis X1, from the inner surface Ci of the differential case C, and are interposed between the pinion support surfaces P1 and P2 and the window 18. The weir-forming steps 60 extend around the periphery of the window 18 substantially along the first axis X1, with both ends of the weir-forming steps 60 reaching near the first and second side gear support surfaces S1 and S2.

[0101] The outer peripheral surface of the weir-forming platform 60 forms a stepped surface between it and the inner surface Ci. Among these stepped surfaces, in particular, a first stepped surface 61 formed in an arcuate shape along the outer periphery of the first side gear support surface S1 functions as a first weir, guiding at least a portion of the oil flowing out of the outer periphery of the first side gear support surface S1 to the pinion gear support surfaces P1 and P2, bypassing the window 18. Furthermore, a second stepped surface 62 formed in an arcuate shape along the outer periphery of the second side gear support surface S2 functions as a second weir, guiding at least a portion of the oil flowing out of the outer periphery of the second side gear support surface S2 to the pinion gear support surfaces P1 and P2, bypassing the window 18. Furthermore, a third stepped surface 63 extending in an arcuate shape between the pinion gear support surfaces P1 and P2 and the window 18 functions as a third weir, preventing oil flowing between the pinion gear support surfaces P1 and P2 and the window 18 from flowing out of the window 18.

[0102] Furthermore, the outer peripheral surface of the weir-forming platform 60, particularly the first to third stepped surfaces 61 to 63, can guide at least a portion of the oil flowing from the side gear support surfaces S1 and S2 toward the windows 18 on the inner surface Ci of the differential case C to the pinion gear support surfaces P1 and P2 so as to bypass the windows 18, thereby contributing to suppressing the outflow of oil from the windows 18. Furthermore, in the third embodiment, the first to third stepped surfaces 61 to 63 of the weir-forming platform 60, which function as the first to third weirs, constitute the main guide weir 50.

[0103] Furthermore, in the third embodiment, the area forming the top surface of the weir forming platform 60 in the inner surface Ci of the differential case C, the area forming the rotating sliding surface of the side gear support surfaces S1 and S2 relative to the side gear 23, and the area forming the rotating sliding surface of the pinion support surfaces P1 and P2 relative to the pinion 22 are machined as the same spherical surface, and the other areas, that is, the area surrounded by the weir forming platform 60, the pinion support surfaces P1 and P2 and the side gear support surfaces S1 and S2 in the inner surface Ci, the pinion lubricating oil groove Gp and the side gear lubricating oil groove Gs are formed as non-machined surfaces that are lower (i.e., radially outward) than the above-mentioned machined surfaces. In the case of manufacturing the differential case C by mold forming such as casting, the non-machined surface is an unmachined casting surface that is directly placed without subsequent processing after casting. Figure 8 The non-machined surface is indicated by dots.

[0104] For example, after the mold is formed, while the differential case blank is rotated around a specific axis X3, the above-mentioned machining is performed on the inner surface Ci of the differential case C using a machining tool (such as a turning tool) that passes through the window 18 and is delivered to the inside of the differential case blank along the specific axis X3.

[0105] Alternatively, the inner surface Ci1 of the first case half Cb1 in the first and second embodiments may be subjected to the same machining method as in the third embodiment. In this case, the inner surface Ci1 of the first case half Cb1 in the first and second embodiments includes the region serving as the top surface of the main guide weir 50 and the region serving as the rotational sliding surface of the pinion gear support surfaces P1 and P2 relative to the pinion gear 22 as a uniformly spherical machined surface, and the region serving as the rotational sliding surface of the side gear support surfaces S1 and S2 relative to the side gear 23 as a flat machined surface. The remaining regions, namely, the region of the inner surface Ci surrounded by the main guide weir 50, the pinion gear support surfaces P1 and P2, and the side gear support surfaces S1 and S2, as well as the pinion gear lubricating oil groove Gp and the side gear lubricating oil groove Gs, are non-machined surfaces located lower (i.e., radially outward) than the aforementioned machined surfaces.

[0106] The remaining configuration of the third embodiment is substantially the same as that of the first embodiment. Therefore, the components of the third embodiment are denoted by the same reference numerals as those of the corresponding components of the first embodiment, and detailed descriptions of these components will be omitted. Furthermore, the third embodiment can also achieve substantially the same functions and effects as the first embodiment.

[0107] In addition, Figure 9 Schematic diagram of a modified example of the auxiliary weir 54 illustrated in the second embodiment, viewed in a direction diverging from the center of the differential case C, is shown.

[0108] That is, in Figure 9 In the first modified example shown in FIG. 1 (A), a folded portion 541a is formed. The folded portion 541a is formed by extending an auxiliary weir 541 from a portion of the outer circumference of the support base 19, axially closer to the second side gear support surface S2 than the opening Gpi of the pinion gear lubricating oil groove Gp, toward the window 18 and in the circumferential direction of the differential case C (i.e., in the direction following the rotational direction), with the extended end being bent into an L-shape axially toward the first side gear support surface S1. A gap 55 is formed between the folded portion 541a and the main guide weir 50. According to this first modified example, oil flowing axially from the first side gear support surface S1 between the opening Gpi of the pinion gear lubricating oil groove Gp and the window 18 (in other words, at a position offset from the opening Gpi in the circumferential direction) can be effectively captured by the auxiliary weir 541 and efficiently guided to the opening Gpi, thereby improving the lubrication performance of the pinion gear support surfaces P1 and P2.

[0109] In addition, Figure 9In the second modified example shown in FIG. 1 (B), the auxiliary weir 542 extends from a portion of the outer circumference of the support base 19 axially closer to the second side gear support surface S2 than the opening Gpi of the pinion gear lubricating oil groove Gp, along the circumferential direction of the differential case C and slightly inclined toward the first side gear support surface S1, toward the window 18. The extended end of the auxiliary weir 542 is connected to the main guide weir 50. According to this second modified example, a portion (the first weir 51) of the main guide weir 50 extends continuously with the auxiliary weir 542, also functioning as an auxiliary weir. Therefore, oil flowing axially from the first side gear support surface S1 toward the window 18 can be effectively captured and efficiently guided to the opening Gpi, thereby improving the lubrication performance of the pinion gear support surfaces P1 and P2.

[0110] In addition, Figure 9 In the third modification shown in (C), the other auxiliary weir 543 is formed from Figure 9 In the second modification (B), the outer peripheral portion of the support base 19 extends axially toward the first side gear support surface S1, starting from a location located opposite the auxiliary weir 542 across the opening Gpi. According to this third modification, the axially extending auxiliary weir 543 effectively captures oil that flows along the auxiliary weir 542 and attempts to pass directly through the opening Gpi, and / or oil that flows circumferentially at a position slightly offset from the auxiliary weir 542, and guides it toward the opening Gpi, thereby improving lubrication performance on the pinion support surfaces P1 and P2.

[0111] The embodiment of the present invention and its modified examples have been described above. However, the present invention is not limited to the above-described embodiment and its modified examples, and various design changes can be made without departing from the spirit and scope of the present invention.

[0112] For example, in the above embodiment, an example is shown in which the differential device D is applied to a differential device for an automobile. However, the differential device D in the present invention can also be applied to vehicles other than automobiles and various mechanical devices other than vehicles.

[0113] In the above embodiment, the main guide weir 50 is exemplified as the oil guide portion for guiding the oil flowing from the side gear support surfaces S1 and S2 toward the window on the inner surface of the differential case in a detour. Figure 4 (A) schematically shows the main guide weir 50 protruding from the inner surface Ci of the differential case C toward the radial inner side (the side close to the first axis X1), but Figure 4As shown in (B), at least a portion of the oil guide portion may be formed by the inner wall of the groove on the side of the window 18 in the groove recessed on the inner surface Ci of the differential case C. In this case, a portion of the oil that flows toward the window 18 is caused to detour and be retained at the inner wall of the groove on the side of the window 18. This increases the amount of oil retained on the inner surface Ci of the differential case C, thereby suppressing the outflow of oil from the window 18. In addition, as at least a portion of the oil guide portion, or as Figure 4 As shown in (C), a weir 50 may be provided on the inner surface Ci of the differential case C, and a folded portion 50a protruding toward the opposite side of the window 18 may be integrally connected to the weir 50. In this case, a high blocking effect can be exerted on the oil tending toward the window 18.

[0114] In addition, in the above-mentioned embodiment, as an oil introduction channel for introducing oil from the outside of the differential case C into the half-shaft gear support surfaces S1 and S2, spiral grooves 15 and 16 capable of exerting a suction effect are respectively provided on the inner peripheral surface of the first bearing protrusion Cb1 of the differential case C and the inner peripheral surface of the second bearing protrusion Cb2 of the differential case C (the first embodiment and the second embodiment), and an oil introduction channel formed by the gap 30 at the fitting portion between the bearing protrusions Cb1, Cb2 and the output shafts 11, 12 (the third embodiment) are illustrated. However, the oil introduction channel is not limited to the above-mentioned embodiment, and for example, it can also be a linear groove recessed on the inner peripheral surface of the bearing protrusions Cb1, Cb2.

[0115] Furthermore, in the above embodiment, an example is shown in which bearing projections Cb1 and Cb2, serving as raised portions, are connected to both axially opposite sides of the differential case C, and each bearing projection Cb1 and Cb2 is provided with an oil introduction passage (the spiral grooves 15 and 16 or the gap 30). However, in the present invention, an oil introduction passage may be provided only on the bearing projection on one axial side. Alternatively, a bearing projection serving as a raised portion may be connected to only one axially opposite side of the differential case C, and an oil introduction passage may be provided on the bearing projection.

[0116] Furthermore, in the above-described embodiment, the height of the main guide weir 50 and / or the auxiliary weirs 54, 541-543 (i.e., the height at which they protrude radially inward (on the side closer to the first axis X1) from the inner surface Ci of the differential case C) may be substantially uniform over the entire longitudinal direction, or may have locally varying heights (height differences). In the latter case, for example, the height of the weir may be set higher in the portion where the centrifugal force is strongest during rotation of the differential case C.

[0117] Furthermore, the inner surface Ci of the differential case C includes multiple regions between the pinion gear support surfaces P1 and P2 and the window 18, and between the side gear support surfaces S1 and S2 and the window 18. In this case, it is not necessary to provide the main guide weir 50 as the oil guide portion in all of these regions. For example, if the oil introduction passage (the spiral grooves 15 and 16 or the gap 30) is provided only in the bearing boss Cb1 on one axial side of the differential case C or the bearing boss Cb2 on the other axial side, the main guide weir 50 (particularly the first weir 51 or the second weir 52) may be provided only between the first side gear support surface S1 and the window 18, or between the second side gear support surface S2 and the window 18, on the same side as the oil introduction passage. In addition, the main guide weir 50 (especially the third weir 53) can also be set only between the first pinion support surface P1 and the window 18, or between the second pinion support surface P2 and the window 18, which are located on the rear side in the rotation direction of the differential case C with the window 18 as the reference when the vehicle moves forward.

[0118] Furthermore, the main guide weir 50 (particularly the first weir 51 and the second weir 52) axially interposed between the side gear support surfaces S1 and S2 and the peripheral edge of the window 18 does not need to cover the entire circumferential area of ​​the peripheral edge of the window 18 in this section. For example, in the third embodiment (see Figure 7 and Figure 8 ) The first weir 61 and the second weir 62 can also suppress the oil from flowing out of the window 18 to a certain extent by covering only a part of the peripheral edge portion in the circumferential direction.

[0119] In addition, as in the second embodiment (see Figure 5 and Figure 6 ), the second modification and the third modification of the second embodiment (see Figure 9 As shown in (B) and (C) of FIG. 1 , the main guide weir 50 and the auxiliary weirs 54, 541 to 543 can be connected. In addition, as shown in the first modification (see Figure 9 As shown in FIG. 5A , the main guide weir 50 and the auxiliary weirs 54 and 541 to 543 may be interposed with gaps 55 therebetween to thereby discontinue the main guide weir 50 and the auxiliary weirs 54 and 541 to 543 .

[0120] Furthermore, in the first and third embodiments, the first weirs 51 and 61 and the second weirs 52 and 62 of the main guide weir 50 are formed continuously. However, the first weirs 51 and 61 and the second weirs 52 and 62 of the main guide weir 50 may be discontinuous.

[0121] In addition, in the first and second embodiments, an expanded diameter inner surface portion 40 of the differential case C is formed by a first expanded diameter inner surface portion 41 and a second expanded diameter inner surface portion 42, wherein the first expanded diameter inner surface portion 41 includes a sharply expanded diameter inner surface portion 41a and a gently expanded diameter inner surface portion 41b; the second expanded diameter inner surface portion 42 includes only a sharply expanded diameter inner surface portion, and the concave shape of the connecting portion where the sharply expanded diameter inner surface portion 41a and the second expanded diameter inner surface portion 42 are connected to each other and the surrounding portion forms an example of an inner surface bottom 40o where oil is collected. However, in the present invention (especially the first to third features), the expanded diameter shape of the expanded diameter inner surface portion 40 of the differential case C is not limited to the shape shown in the first and second embodiments.

[0122] For example, the gently expanding inner surface portion 41b and / or the sharply expanding inner surface portion 41a may be formed as a cylindrical surface (i.e., the inner diameter is constant throughout the entire axial range), or only the second expanded inner surface portion 42 may be formed as the cylindrical surface, in which case the cylindrical surface serves as the inner surface recessed portion 40. Alternatively, the sharply expanding inner surface portion 41a and the second expanded inner surface portion 42 may be formed on the cylindrical surface, and at least a portion of the gently expanding inner surface portion 41b may be formed on a V-shaped concave surface having the largest cross-sectional diameter at the axial center. In this case, the concave portion of the V-shaped concave surface serves as the inner surface recessed portion 40o. In addition, the expanded diameter inner surface portion 40 may be formed so that the inner diameter of the expanded diameter inner surface portion 40 gradually increases as it moves from one axial end side toward the central portion or a predetermined middle portion deviating from the central portion, and the inner diameter gradually increases as it moves from the other axial end side toward the central portion or the above-mentioned predetermined middle portion, thereby forming a V-shaped concave surface with a cross-section having the largest diameter in the axial central portion or the above-mentioned predetermined middle portion. In this case, the concave portion of the V-shaped concave surface may also be used as the inner surface concave portion 40o.

Claims

1. A differential device, characterized in that: have: a differential case (C), the differential case (C) being rotatable about a first axis (X1); a pair of side gears (23) supported on the differential case (C) in a manner capable of rotating freely around the first axis (X1); a plurality of pinion gears (22), the plurality of pinion gears (22) being supported on the differential case (C) in a manner capable of freely rotating about at least one second axis (X2) orthogonal to the first axis (X1), and respectively meshing with the pair of side gears (23); a raised portion (Cb1, Cb2), the raised portion (Cb1, Cb2) being provided protrudingly on at least one side of the differential case (C) in the axial direction along the first axis (X1); an oil introduction passage (15, 16, 30) provided on the raised portions (Cb1, Cb2) and capable of introducing lubricating oil from the outside of the differential case (C) to the side gear support surfaces (S1, S2) on the inner surface (Ci) of the differential case (C), the side gear support surfaces (S1, S2) supporting the back surface of the side gear (23) on the same side as the raised portions (Cb1, Cb2) so as to be able to rotate freely; and a window (18) formed on the differential case (C) in such a manner that the interior and the exterior of the differential case (C) are communicated with each other, and A pinion support surface (P1, P2) is provided on the inner surface (Ci) of the differential case (C), and the pinion support surface (P1, P2) supports the back surface of the pinion (22) so that it can rotate freely. The inner surface (Ci) of the differential case (C) has an oil guide portion (50), the oil guide portion (50) protruding from the inner surface (Ci) toward the first axis (X1) and surrounding the window (18) over its entire circumference. The oil guide portion (50) is formed by connecting a first weir (51) and a second weir (52) located between the side gear support surfaces (S1, S2) and the peripheral edge of the window (18), and a third weir (53) located between the pinion support surfaces (P1, P2) and the peripheral edge of the window (18). The oil guide portion (50) guides at least a portion of the oil flowing from the side gear support surface (S1, S2) toward the window (18) on the inner surface (Ci) in a manner that bypasses the window (18).

2. The differential device according to claim 1, wherein: A pinion lubricating oil groove (Gp) is recessed on the pinion support surface (P1, P2). The pinion gear lubricating oil groove (Gp) opens toward the inner surface (Ci) of the differential case (C) at the outer periphery of the pinion gear supporting surface (P1, P2).

3. The differential device according to claim 2, wherein: The side gear support surfaces (S1, S2) are formed as annular flat surfaces perpendicular to the first axis (X1). The inner surface (Ci) of the differential case (C) includes an expanded inner surface portion (40), and the expanded inner surface portion (40) includes an inner surface bottom portion (40o), the expanded inner surface portion (40) connects a pair of the side gear support surfaces (S1, S2) to each other, and the expanded inner surface portion (40) is expanded in diameter compared to each side gear support surface (S1, S2), and the inner surface bottom portion (40o) is located on the side farthest from the first axis (X1) in the expanded inner surface portion (40), The second weir (52) is located between the inner surface bottom (40°) and the window (18), the second weir (52) protrudes toward the first axis (X1) side relative to the inner surface bottom (40°), and the pinion lubricating oil groove (Gp) opens toward the inner surface bottom (40°).

4. The differential device according to claim 1, wherein: The pinion support surfaces (P1, P2) are formed on a support platform (19) convexly provided on the inner surface (Ci) of the differential case (C), and a pinion lubricating oil groove (Gp) concavely provided on the pinion support surfaces (P1, P2) has an opening (Gpi) opened at the outer periphery of the support platform (19). The inner surface (Ci) of the differential case (C) has an inner diameter changing portion (41) and auxiliary weirs (54, 541, 542), The inner diameter changing portion (41) is formed by expanding the diameter of the axial range from the side gear support surface (S1) on one axial side to at least the opening (Gpi) toward the other axial side. The auxiliary weirs (54, 541, 542) are protruding from the inner surface of the inner diameter changing portion (41) and extend from a portion of the outer periphery of the support platform (19) closer to the other side of the axial direction than the opening (Gpi) toward the window (18).

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