JP2016114241A - Differential device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively prevent seizure of a pinion slide part or an engagement part of a pinion and a side gear, even when a tooth part of the side gear is separated far from an output shaft by enlargement of the side gear or when the pinion rotates at high speed, in a differential device.SOLUTION: A side gear S has a shaft part Sj connected to an output shaft A, and a flat intermediate wall part Sw integrally connected between the shaft part Sj and a tooth part Sg of the side gear S separated from the shaft part Sj toward the radial outside of an input member I. In the intermediate wall part Sw of at least one side gear S, provided is a through oil passage 15 of which both ends are opened to the inside surface and outside surface of the intermediate wall part Sw respectively.SELECTED DRAWING: Figure 1

Description

  The present invention supports a differential device, in particular, a pinion support portion (differential gear support portion) that supports a pinion (differential gear) and meshes with the pinion the rotational force of an input member that can rotate together with the pinion support portion. The present invention relates to an improvement in what is distributed and transmitted to a pair of output shafts via a pair of side gears (output gears) having teeth on the outer periphery.

  Conventionally, such a differential device is known as described in Patent Document 1, for example. In the conventional device, the lubricating oil is supplied to the sliding portion of the pinion and the side gear meshing portion through the gap between the back surface of the side gear and the differential case and the spline fitting portion between the inner periphery of the side gear and the outer periphery of the output shaft. It has become.

JP 2008-89147 A Japanese Patent No. 4803871 JP 2002-364728 A

  However, in the conventional device, a large amount of lubricating oil cannot be efficiently collected at the meshing portion of the pinion and the side gear. For example, when the meshing portion is far from the output shaft by increasing the diameter of the side gear, the pinion rotates at high speed. In such a severe driving situation, there is a risk that the supply of lubricating oil to the sliding portion of the pinion and the side gear meshing portion will be insufficient.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a differential device that can solve the above-described problems.

  In order to achieve the above object, a differential according to the present invention includes a tooth portion that supports a pinion support portion that supports a pinion and meshes the rotational force of an input member that can rotate together with the pinion support portion with the pinion. A differential device that distributes and transmits to a pair of output shafts via a pair of side gears having an outer peripheral portion, wherein the pair of side gears are respectively connected to the pair of output shafts, and the shaft And a flat intermediate wall portion integrally connecting the tooth portion spaced from the shaft portion radially outward of the input member, and the intermediate wall portion of at least one of the side gears A through oil passage having both ends opened on the inner side surface and the outer side surface of the intermediate wall portion is formed (this is a first feature).

  Preferably, the cover further includes a side wall covering the outer surface of the at least one side gear and coupled to rotate integrally with the input member, an inner surface of the side wall, and an outer surface of the side gear. A washer interposed between the washer and the penetrating oil passage so that at least an inner peripheral portion of the washer faces an opening of the penetrating oil passage to an outer surface of the intermediate wall portion. Relative position is set (this is the second feature).

  Preferably, a washer holding groove for fitting and holding the washer is formed on at least one of the opposing surfaces of the inner side surface of the side wall portion and the outer side surface of the side gear (this is a third feature). .

  Preferably, the side wall portion includes a lightening portion that exposes an outer side surface of the side gear, and the washer and the through-hole are formed on an inner surface of the side wall portion from a peripheral edge of the lightening portion when the input member rotates. An oil guide groove that can guide the inflow of the lubricating oil into the oil passage is recessed (this is a fourth feature).

  In order to achieve the above object, the differential device according to the present invention supports the differential gear support portion that supports the differential gear, and the rotational force of the input member that can rotate with the differential gear support portion. A differential device that distributes and transmits to a pair of output shafts via a pair of output gears having tooth portions meshing with the differential gear on an outer peripheral portion, wherein the pair of output gears is the pair of output shafts A shaft portion connected to each other, and a flat intermediate wall portion integrally connecting the shaft portion and the tooth portion spaced apart from the shaft portion radially outward of the input member, and at least In the intermediate wall portion of one of the output gears, through oil passages having both ends opened on the inner surface and the outer surface of the intermediate wall portion are formed, the number of teeth of the output gear is Z1, and the differential gear The number of gear teeth is Z2, the diameter of the differential gear support is d2, and the pitch cone distance is When the CD,

The filling,
And Z1 / Z2> 2 is satisfied (this is the fifth feature).

  Preferably, Z1 / Z2 ≧ 4 is satisfied (this is the sixth feature).

  Preferably, Z1 / Z2 ≧ 5.8 is satisfied (this is the seventh feature).

  According to the first feature, the pair of side gears is a flat portion that integrally connects the shaft portion connected to the output shaft and the tooth portion spaced from the shaft portion radially outward of the input member and the shaft portion. With the intermediate wall portion, the side gear can have a sufficiently large diameter with respect to the pinion so that the number of teeth of the side gear can be set sufficiently larger than the number of teeth of the pinion, so that when torque is transmitted from the pinion to the side gear, The load on the pinion support can be reduced and the effective diameter of the pinion support can be reduced, and the axial width of the pinion can be narrowed. This can contribute to narrowing the axial width of the moving device. Further, with the increase in the diameter of the side gear, even if the tooth portion of the side gear is far away from the output shaft in the radial direction, the intermediate wall portion of at least one side gear has both ends on the inner surface and the outer surface of the intermediate wall portion. Since the through oil passages are opened, the lubricating oil can flow from the outer surface side of the side gear to the inner surface side through the through oil passage, and the lubricating oil that has flowed in is extended by centrifugal force to the teeth on the outer periphery of the side gear. Therefore, it can be efficiently supplied to the meshing portion with the pinion. As a result, even when the side gear teeth are separated from the output shaft due to the increased diameter of the side gear or in severe operating situations where the pinion rotates at high speed, the lubricating oil is applied to the meshing part of the pinion and the side gear and the sliding part of the pinion. Therefore, seizure of the meshing part and the sliding part can be effectively prevented.

  In particular, according to the second feature of the present invention, the cover further includes a side wall covering the outer surface of at least one of the side gears and coupled to rotate integrally with the input member, and the inner surface of the side wall And a washer interposed between the outer side surface of the side gear and the washer and the through oil passage so that at least the inner periphery of the washer faces the opening to the outer side surface of the intermediate wall portion of the through oil passage. The relative position of the oil is set so that the flow of lubricating oil, which tries to flow radially outward by centrifugal force in the gap between the inner surface of the cover part and the outer surface of the side gear, is suppressed by the washer and penetrates from the inner peripheral side of the washer. It can be guided to the inner side of the side gear through the oil passage. Thereby, the lubrication effect with respect to a meshing part etc. can be heightened by increasing the amount of lubricating oil which passes a penetration oil path and goes to an outer peripheral tooth part side along the inner side surface of a side gear. In addition, since the washer also serves as an oil guiding means to the through oil passage, the structure can be simplified and the cost can be reduced.

  Further, in particular, according to the third feature, the washer holding groove is formed in at least one of the opposing surfaces of the inner side surface of the side wall portion of the cover portion and the outer side surface of the side gear. The washer can be stably held at an appropriate fixed position in consideration.

  In particular, according to the fourth feature, the side wall portion of the cover portion is provided with a lightening portion that exposes the outer surface of the side gear, and the inner surface of the side wall portion has a peripheral edge of the lightening portion when the input member rotates. Since the oil guide groove that can guide the inflow of the lubricating oil into the washer and the through oil passage is recessed, the oil guide effect of the oil guide groove makes the washer from the peripheral edge of the thinned portion using the rotation of the input member. In addition, the inflow of lubricating oil to the through oil passage can be efficiently induced. Therefore, since the lubricating effect on the washer can be enhanced, the amount of lubricating oil directed toward the tooth portion on the outer periphery of the side gear through the through oil passage can be increased more effectively to further enhance the lubricating effect on the meshing portion and the like.

  According to the fifth feature, the pair of output gears are integrally connected between the shaft portion connected to the output shaft and the tooth portion spaced from the shaft portion radially outward of the input member and the shaft portion. Therefore, the output gear can have a sufficiently large diameter with respect to the differential gear so that the number of teeth of the output gear can be set sufficiently larger than the number of teeth of the differential gear. This reduces the load on the differential gear support when transmitting torque from the differential gear to the output gear, reduces the effective diameter of the differential gear support, and narrows the differential gear in the axial direction. Therefore, combined with the effect that the intermediate wall portion is flat, it is possible to contribute to narrowing the axial width of the differential device. Further, with the increase in the diameter of the output gear, even if the tooth portion of the output gear is far away from the output shaft in the radial direction, the inner wall surface and the outer surface of the intermediate wall portion are provided on the intermediate wall portion of at least one output gear. Since through oil passages are formed at both ends, the lubricating oil can flow from the outer surface side of the output gear to the inner surface side through the through oil passages. Can be efficiently supplied to the teeth portion, and thus the meshing portion with the differential gear. As a result, even when the output gear teeth are far away from the output shaft due to an increase in the diameter of the output gear, or in severe operating situations where the differential gear rotates at a high speed, the meshing portion or difference between the differential gear and the output gear can be reduced. Since the lubricating oil can be sufficiently supplied to the sliding portion of the moving gear, seizure of the meshing portion and the sliding portion can be effectively prevented. In addition, according to the fifth feature, the differential device as a whole is sufficiently wide in the axial direction of the output shaft while ensuring the same strength (for example, static torsional load strength) and the maximum torque transmission amount as the conventional device. Because it can be narrowed, it is possible to easily incorporate a differential gear into a transmission system with many restrictions on the layout around the differential gear without difficulty, and it is advantageous for downsizing the transmission system. It becomes.

  In particular, according to each of the sixth and seventh features, the differential device is more sufficiently secured in the axial direction of the output shaft while ensuring the same strength (for example, static torsional load strength) and the maximum torque transmission amount as the conventional device. Can be narrowed.

1 is a longitudinal sectional view of a differential according to a first embodiment of the present invention and its surroundings (a sectional view taken along line 1-1 of FIG. 2). 1 is a side view of one side in an axial direction in which a part of a differential device according to a first embodiment of the present invention is broken (sectional view taken along line 2-2 in FIG. 1) The principal part side view of the other axial direction side of the differential gear which concerns on 1st Embodiment of this invention (3-3 line sectional drawing of FIG. 1). FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 1 and shows only one cover portion C by a solid line. FIG. 5 is a cross-sectional view taken along line 5-5 in FIG. 1 and shows only the other cover portion C ′ and the input member with solid lines. (A) is an enlarged view of a portion indicated by arrow 6 in FIG. 1, and (B) is a sectional view taken along line BB in (A). FIG. 4 is a diagram corresponding to FIG. The fragmentary sectional view corresponding to FIG. 6 (A) which shows the modification of the pinion support part of the differential gear which concerns on 2nd Embodiment of this invention. A longitudinal sectional view showing an example of a conventional differential device The graph which shows the relationship of the gear strength change rate with respect to the ratio of the number of teeth when the number of teeth of the pinion is 10 Graph showing the relationship between the rate of change in gear strength and the rate of change in pitch cone distance The graph which shows the relationship of the change rate of the pitch cone distance with respect to the ratio of the number of teeth when the gear strength is maintained at 100% when the number of teeth of the pinion is 10 A graph showing the relationship between the ratio of the number of teeth when the number of teeth of the pinion is 10 and the ratio of the shaft diameter / pitch cone distance A graph showing the relationship between the ratio of the number of teeth when the number of teeth of the pinion is 6 and the ratio of the shaft diameter / pitch cone distance A graph showing the relationship between the ratio of the number of teeth when the number of teeth of the pinion is 12 and the ratio of the shaft diameter / pitch cone distance A graph showing the relationship between the ratio of the number of teeth when the number of teeth of the pinion is 20 and the ratio of the shaft diameter / pitch cone distance

  Embodiments of the present invention will be described below on the basis of preferred embodiments of the present invention shown in the accompanying drawings.

  First, a first embodiment shown in FIGS. 1 to 7 will be described. The differential device D distributes and transmits the rotational driving force transmitted from the engine (not shown) mounted on the automobile to the pair of left and right output shafts A connected to the pair of left and right axles, thereby transmitting the left and right axles. For driving while allowing differential rotation, for example, it is housed and supported in a mission case 1 disposed beside the engine at the front of the vehicle body.

  The differential device D can rotate together with a plurality of pinions (differential gears) P, a pinion shaft PS as a pinion support portion (differential gear support portion) that rotatably supports the pinion P, and the pinion shaft PS. A short cylindrical input member I that supports the pinion shaft PS, a pair of left and right side gears (output gears) S that are engaged with the pinion P from the left and right sides and connected to a pair of left and right output shafts A, and both side gears S And a pair of left and right cover portions C and C ′ that rotate integrally with the input member I, and a differential case DC is constituted by the input member I and the cover portions C and C ′.

  In this embodiment, there are two pinions P, and a pinion shaft PS as a pinion support is formed in a straight bar shape extending along one diameter line of the input member I, and two pinions P are provided at both ends thereof. However, three or more pinions P may be provided. In that case, the pinion shaft PS is branched in the form of three or more directions from the rotation axis L of the input member I corresponding to three or more pinions P and extends radially (for example, when there are four pinions P). Is formed in a cross shape, and the pinions P are supported on the respective tip portions of the pinion shaft PS.

  Further, the pinion P may be directly fitted to the pinion shaft PS as in the illustrated example, or a bearing means (not shown) such as a bearing bush may be inserted. Further, the pinion shaft PS may have a substantially uniform shaft diameter or a stepped shaft shape over the entire length. Further, a recess may be provided on the outer peripheral surface of the pinion shaft PS that fits with the pinion P, and this may be used as an oil passage.

  The differential case DC is rotatably supported by the transmission case 1 via the left and right bearings 2. An annular seal member 3 is interposed between the inner periphery of the through hole 1a formed in the mission case 1 and into which each output shaft A is inserted and the outer periphery of each output shaft A. Further, an oil pan (not shown) for storing a predetermined amount of lubricating oil facing the internal space of the mission case 1 is provided at the bottom of the mission case 1, and the lubricating oil stored in the oil pan is transmitted to the mission case. 1 is scattered around the differential device D by the rotation of the differential case DC and other rotating members, so that the mechanical interlocking portions existing inside and outside the differential case DC can be lubricated.

  An input tooth portion Ig as a final driven gear is provided on the outer peripheral portion of the input member I, and the input tooth portion Ig meshes with a drive gear (not shown) that is rotationally driven by engine power. In this embodiment, the input tooth portion Ig is directly formed on the outer peripheral surface of the input member I over the entire width (that is, the full width in the axial direction). However, the input tooth portion Ig is formed to be narrower than the input member I. Alternatively, it may be formed separately from the input member I and fixed to the outer peripheral portion of the input member I by retrofitting.

  The pinion P and the side gear S are formed as bevel gears in the present embodiment, and the whole including the tooth portions is formed by plastic working such as forging. Therefore, the teeth can be formed with high accuracy with an arbitrary ratio of teeth without being subjected to machining restrictions as in the case of cutting the teeth of the pinion P and the side gear S. Note that other gears may be employed instead of the bevel gear. For example, the side gear S may be a face gear, and the pinion P may be a spur gear or an inclined gear.

  The pair of side gears S is separated from the shaft portion Sj in the radial direction of the input member I by the cylindrical shaft portion Sj to which the inner end portions of the pair of output shafts A are respectively connected by spline fitting 4. An annular tooth portion Sg that is in position and meshes with the pinion P, and an intermediate portion that is formed in a flat ring plate shape orthogonal to the axis L of the output shaft A and integrally connects the shaft portion Sj and the tooth portion Sg. And wall part Sw.

  At least one (both in the present embodiment) side wall S of the intermediate wall portion Sw has a through oil passage 15 having both ends opened to the inner side surface and the outer side surface of the intermediate wall portion Sw and penetrating through the intermediate wall portion Sw. Is formed. In addition, in this embodiment, the through oil passage 15 is formed in a circular hole in which the axis L of the output shaft A and the center axis are parallel, but the cross-sectional shape is not limited to the illustrated example, and various shapes such as, for example, The hole may be a fan shape, an elliptical shape, a polygonal shape or a square shape, and the center axis of the hole may not be parallel to the axis L of the output axis A. For example, by providing the penetrating oil passage 15 obliquely with respect to the axis L of the output shaft A so that the central axis of the penetrating oil passage 15 approaches the radially outer side of the side gear S as it approaches the inner surface of the side gear S, The flow of the lubricating oil toward the outer peripheral tooth portion Sg (and hence the pinion P) of the side gear S through the through oil passage 15 can be further promoted.

  Further, the intermediate wall portion Sw of the side gear S has a radial width t1 larger than the maximum diameter d1 of the pinion P, and the intermediate wall portion Sw has a maximum wall thickness t2 in the axial direction of the output shaft A. The pinion shaft PS is formed to be smaller than the effective diameter d2 (see FIG. 1). As a result, as will be described later, the side gear S can be sufficiently increased in diameter so that the number of teeth Z1 of the side gear S can be set sufficiently larger than the number of teeth Z2 of the pinion P, and in the axial direction of the output shaft A. The side gear S can be sufficiently thinned. In this specification, the “effective diameter d2” is a shaft as a pinion support portion (that is, a pinion shaft) that is formed separately from or integrally with the pinion P, supports the pinion P, and is attached to the input member I. PS or the outer diameter d2 of the support shaft portion PS ′) described later.

  One of the pair of cover portions C and C ′ is formed separately from the input member I and is detachably coupled to the input member I with bolts b. The coupling means includes screw means. Various coupling means other than the above, such as welding means and caulking means, can also be used. The other cover portion C ′ is formed integrally with the input member I. The other cover portion C ′ may be formed separately from the input member I in the same manner as the one cover portion C, and may be coupled to the input member I by a bolt b or other coupling means.

  Each of the cover portions C and C ′ includes a cylindrical boss portion Cb that concentrically surrounds and supports the shaft portion Sj of the side gear S, and an outer surface that is connected to the rotation axis L of the input member I. And a plate-like side wall Cs integrally connected to the inner end in the axial direction of the boss Cb as an orthogonal flat surface. The side wall Cs of the cover C, C ′ is the axial direction of the output shaft A. The input member I (and thus the input tooth portion Ig) is arranged so as to be within the width. As a result, the side wall Cs of the cover portions C and C ′ can be prevented from projecting outward in the axial direction from the end face of the input member I, so that the width of the differential shaft D in the axial direction of the output shaft A is reduced. It will be advantageous to plan.

  In addition, the back surface of at least one of the intermediate wall portion Sw and the tooth portion Sg (the intermediate wall portion Sw in the illustrated example) of the side gear S is interposed through the washer W by the inner surface of the side wall portion Cs of the cover portions C and C ′. It is supported rotatably. Note that such a washer W may be omitted, and the back surface of the side gear S may be directly supported rotatably by the inner surface of the side wall portion Cs. The shaft portion Sj of the side gear S may be supported by the boss portion Cb of the cover portions C and C ′ via a bearing.

  Next, a structure for attaching the pinion shaft PS as the pinion support portion to the input member I will be described with reference to FIG. In the pinion shaft PS, both end portions of the pinion shaft PS are connected and supported to the input member I via the attachment body T, and the end portion of the pinion shaft PS is fitted to the attachment body T over the entire circumference. A holding hole Th that can be held is formed (see FIG. 1). A mounting groove Ia having a U-shaped cross section extending in the direction of the output shaft A is provided on the inner peripheral surface of the input member I. The rectangular parallelepiped mounting body T is inserted into the mounting groove Ia from the opening of the mounting groove Ia. The attachment body T is fixed to the input member I by fastening one cover portion C to the input member I with a bolt b in a state in which the attachment body T is inserted into the attachment groove Ia of the input member I. An annular thrust washer 25 that allows relative rotation between the attachment body T and the large-diameter side end face of the pinion P is interposed.

  According to the mounting structure of the pinion shaft PS to the input member I as described above, the pinion shaft PS is input via the block-shaped mounting body T in which the end of the pinion shaft PS is fitted and held over the entire circumference. Since it can be easily and firmly connected and fixed to the mounting groove Ia of the member I, the pinion shaft PS is not formed in the input member I without specially forming a through hole for supporting the pinion shaft PS, and without reducing the assembling workability. Can be connected and supported to the input member I with high strength. In addition, in this embodiment, the structure is simplified because the cover portion C that covers the outside of the side gear S also serves as a retaining fixing means for the attachment body T.

  Thus, in a state where both ends of the pinion shaft PS are connected and supported by the input member I via the attachment body T, the large-diameter side end surface of the pinion P that is rotatably supported by the pinion shaft PS, and the input member I A radial gap 10 is formed between the peripheral surface. Accordingly, since the lubricating oil easily accumulates in the gap 10, it is effective for preventing seizure of the end portion of the pinion P facing the gap 10 and the peripheral portion of the pinion P.

  By the way, the side wall portion Cs of the one cover portion C has a side gear S in a first predetermined region including a region overlapping with the pinion P as viewed from the side in the axial direction of the output shaft A (that is, as viewed in FIG. 2). An oil retaining portion 7 that covers the rear surface of the side gear S, and further, an oil retaining portion 8 that exposes the rear surface of the side gear S to the outside of the differential case DC in the second predetermined region that does not overlap the pinion P in the side view. 7 and a connecting arm portion 9 that is spaced apart from the input member I in the circumferential direction and extends in the radial direction of the input member I to connect the boss portion Cb and the input member I together. In other words, the side wall Cs that basically has a disk shape of the cover C is formed by forming a plurality of cutouts 8 in the circumferential direction at intervals in the circumferential direction. The oil holding portion 7 is formed on one side and the connecting arm portion 9 is formed on the other side with 8 being sandwiched in the circumferential direction.

  Lubricating oil which is going to move outward in the radial direction by the centrifugal force generated by the rotation of the input member I is input to the oil holding portion 7 by the structural form of the side wall portion Cs of the cover portion C, particularly the oil holding portion 7. It becomes easy to make it stay in the space covered with the member I, and it can make it easy to hold | maintain lubricating oil in the peripheral part of the pinion P and the pinion P. In addition, since the cover part C includes the lightening part 8, the lubricating oil can be circulated in and out of the differential case DC through the lightening part 8, so that the lubricating oil is appropriately exchanged and cooled to prevent oil deterioration. It is effective. Further, it is not necessary to confine a large amount of lubricating oil in the differential case DC, and the cover portion C itself becomes lighter by the amount corresponding to the formation of the thinned portion 8, so that the weight of the differential device D can be reduced.

  In the present embodiment, the thinned portion 8 is formed in a notch shape in which the outer peripheral end side of the side wall portion Cs is opened, but may be formed in a through hole shape in which the outer peripheral end side is not opened.

  In the present embodiment, as shown in FIG. 3, also in the other cover portion C ′, the thinned portion 8 is formed in the side wall portion Cs similarly to the one cover portion C. However, the oil retaining portion 7 and the connecting arm portion 9 are formed integrally with the input member I in the side wall portion Cs of the other cover portion C ′. Note that the side wall Cs of one of the covers C and C ′ does not have a lightening portion (thus covering the entire rear surface of the intermediate wall Sw of the side gear S and the tooth Sg). You may form in a shape.

  The structure for connecting the oil holding part 7 and the connecting arm part 9 to the input member I is as described above as the connecting structure of the cover parts C and C ′ to the input member I. That is, the oil holding portion 7 and the connecting arm portion 9 may be formed integrally with the input member I. When the oil holding portion 7 and the connecting arm portion 9 are formed separately, the input member is formed by screw means such as a bolt b as in the present embodiment. It may be coupled to I or may be coupled to the input member I by various other coupling means (for example, welding means, caulking means, etc.).

  By the way, the washer W is interposed between the inner side surface of the side wall portion Cs of the cover portions C and C ′ and the outer side surface of the side gear S as described above, but the washer W is lubricated to the through oil passage 15. An annular washer retaining groove 16 is provided on at least one of the inner side surface of the side wall Cs and the outer side surface of the side gear S (in the illustrated example, the outer side surface of the side gear S) in order to be positioned and held at an appropriate fixed position in consideration of the oil path. Is formed, and a washer W is fitted thereto.

  Then, the relative positions of the washer W and the through oil passage 15 are set so that the inner peripheral portion of the washer W faces the opening of the through oil passage 15 to the outer surface of the intermediate wall portion Sw. Accordingly, the washer W suppresses the flow of the lubricating oil that tends to flow outward in the radial direction by centrifugal force in the gap between the inner side surface of the side wall portion Cs of the cover portions C and C ′ and the outer side surface of the side gear S. Since it can be guided from the inner peripheral side of the washer W to the inner side of the side gear S through the through oil passage 15, the amount of lubricating oil passing through the through oil passage 15 and moving toward the tooth portion Sg along the inner side surface of the side gear S is reduced. Can be increased.

  4 and 5 together, the inner surface of the side wall portion Cs of the cover portions C and C ′ is connected to the washer W and the penetrating oil passage 15 from the periphery of the thinned portion 8 when the input member I rotates. An oil guide groove 17 that can guide the inflow of the lubricating oil is recessed. The oil guide groove 17 is inclined with respect to the tangential direction of the oil retaining portion 7 from the peripheral edge of the thinned portion 8 (more specifically, toward the rear side in the normal rotation direction to be described later of the input member I on the central axis L side) (I) by the first inner wall 17a extending in an inclined manner, the second inner wall 17b extending in the tangential direction of the oil retaining portion 7, and the inner wall 17a and the inner wall 17c connecting the inner ends of the inner walls 17b, It is generally formed in a triangular shape.

  Moreover, the inner back groove portion 17i of the oil guide groove 17 facing the back wall portion 17c always overlaps with a part of the washer W when viewed from the projection plane orthogonal to the rotation axis L of the input member I, and the input member I Along with the rotation, the penetrating oil passage 15 is disposed at a position where it can temporarily overlap with the opening to the outer surface of the intermediate wall portion Sw.

  Thus, when the input member I is rotated in the forward rotation direction (the direction of the bold arrow in FIGS. 2 to 5) by the rotational force transmitted from the engine to the input tooth portion Ig of the differential device D in order to advance the automobile. In the transmission case 1, the lubricating oil that scatters around the differential case DC is transferred from the periphery of the thinned portion 8 to the oil retaining portion 7 due to the relative speed difference between the scattered lubricating oil and the rotating cover portions C and C ′. It flows into the inside (that is, the oil guide groove 17). In this case, the lubricating oil that has flowed into the oil guide groove 17 is efficiently collected toward the inner back groove portion 17i at the rearmost position in the rotation direction of the oil guide groove 17 particularly by the guide action of the first inner wall 17a. It is efficiently guided from the groove 17i to the washer W and the through oil passage 15 side. The lubricating oil that has passed through the through oil passage 15 and has reached the inside of the side gear S flows to the radially outer side on the inner side surface of the intermediate wall portion Sw of the side gear S by centrifugal force, and the tooth portion Sg of the side gear S. To reach. As a result, the lubricating effect on the washer W can be enhanced, and the amount of lubricating oil passing through the through oil passage 15 toward the tooth Sg side of the outer periphery of the side gear S can be increased more effectively. The lubricating effect on the meshing part of S and the pinion P and the sliding part of the pinion P is enhanced.

  Furthermore, the cover portions C and C ′ of the present embodiment have an oil guide slope f that can guide the inflow of the lubricating oil to the inner side of the input member I when the input member I rotates at the peripheral portion of the thinned portion 8. The inlet of the oil guide groove 17 is also open to the oil guiding slope f. The oil guiding slope f is formed by the oil holding portion 7 and the connecting arm portion as viewed in a cross section (see the partial cross-sectional view of FIG. 2) across the oil holding portion 7 and the connecting arm portion 9 in the circumferential direction of the input member I. 9, each of the oil holding portions 7 and the connecting arm portions 9 is formed of a slope inclined toward the center in the circumferential direction from the outer side surface toward the inner side surface.

  Thus, the oil guiding action of the oil guiding slope f allows the lubricating oil to flow smoothly from the outside to the inside of the cover portions C and C ′ as the differential case DC rotates. Since the lubricating oil can flow more efficiently from the inlet opening to the oil guiding slope f, the lubricating effect on the meshing portion and the like is further enhanced in combination with the oil guiding action by the oil guide groove 17.

  Various modifications can be considered for the form of the lightening part 8 (and hence the oil retaining part 7 and the connecting arm part 9) in the cover parts C and C ', and the invention is not limited to the embodiment shown in FIGS.

  In addition, various modifications can be considered for the form of the oil guide groove 17 recessed in the inner surface of the side wall part Cs of the cover parts C and C ′. For example, as shown in FIG. You may form in a series of circular arc shape from which a curvature differs in one part area | region. That is, in the oil guide groove 17, the lubricating oil scattered in the transmission case 1 with the rotation of the input member I in the forward rotation direction flows into the oil guide groove 17 from the peripheral edge of the thinned portion 8 of the cover portions C and C ′. In some cases, the lubricating oil that has flowed into the inner groove 17i at the rearmost position in the rotational direction of the oil guide groove 17 is guided by the guide action of the arc-shaped first inner wall 17a as in the embodiment described in FIGS. Are efficiently collected toward the washer W and the through oil passage 15 from the inner back groove portion 17i. Therefore, the oil guide groove 17 shown in FIG. 7 can achieve the same effect as the oil guide groove 17 shown in FIGS.

  Next, the operation of the above-described embodiment will be described. In the differential device D of the present embodiment, when the input member I receives rotational force from the engine, the pinion P revolves around the axis L of the input member I together with the input member I without rotating around the pinion shaft PS. The left and right side gears S are rotationally driven at the same speed, and the driving force is evenly transmitted to the left and right output shafts A. Further, when a difference in rotational speed occurs between the left and right output shafts A due to turning of the automobile or the like, the pinion P revolves while rotating, thereby allowing differential rotation from the pinion P to the left and right side gears S. A rotational driving force is transmitted. The above is the same as the operation of a conventionally known differential device.

  By the way, when the power of the engine is transmitted to the left and right output shafts A through the differential device D in the forward traveling state of the automobile, the differential case DC rotates in the forward direction (the direction of the bold arrow in FIGS. 2 to 5). Along with this, the lubricating oil scatters vigorously at various locations in the mission case 1, but a part of the scattered lubricating oil flows into the cover portions C and C ′ from the lightening portion 8 as described above.

  In this case, the lubricating oil that has flowed into the oil guide groove 17 formed on the inner side surface of the side wall portion Cs of the cover portions C and C ′ is directed toward the inner back groove portion 17i by the guiding action of the first inner side wall 17a as described above. Since it is efficiently collected and efficiently guided to the washer W and the through oil passage 15 from there, it is possible to improve the lubricating effect on the washer W, and from the start, the side gear is passed through the through oil passage 15 by centrifugal force. The amount of lubricating oil toward the tooth portion Sg side of the outer periphery of S can be increased more effectively. Thereby, the lubrication effect with respect to the meshing part of the side gear S and the pinion P and the sliding part of the pinion P is enhanced. As a result, even when the tooth portion Sg of the side gear S is far away from the output shaft A due to an increase in the diameter of the side gear S or in a severe driving situation where the pinion P rotates at high speed, the lubricating oil is transferred to the meshing portion and the sliding portion. Therefore, seizure of the meshing part and the sliding part can be effectively prevented.

  Thus, in the differential device D of the present embodiment, the side gear S is formed in a flat ring plate shape orthogonal to the shaft portion Sj connected to the output shaft A and the axis L of the output shaft A, and the shaft An intermediate wall portion Sw integrally connecting the portion Sj and the tooth portion Sg of the side gear S spaced apart from the shaft portion Sj radially outward of the input member I. Sw is formed such that its radial width t1 is longer than the maximum diameter d1 of the pinion P. For this reason, since the side gear S can be sufficiently enlarged with respect to the pinion P so that the number of teeth Z1 of the side gear S can be set sufficiently larger than the number of teeth Z2 of the pinion P, the torque at the time of torque transmission from the pinion P to the side gear S can be reduced. The load on the pinion shaft PS can be reduced, the effective diameter d2 of the pinion shaft PS can be reduced, and the width of the pinion P in the axial direction of the output shaft A can be reduced.

  In addition, as described above, the load on the pinion shaft P is reduced, and the reaction force applied to the side gear S is reduced. In addition, the intermediate wall portion Sw of the side gear S or the back surface of the tooth portion Sg is supported by the cover side wall portion Cs. Therefore, even if the intermediate wall portion Sw of the side gear S is thinned, it is easy to ensure the necessary rigidity and strength of the side gear S, that is, the side gear intermediate wall portion Sw is sufficiently secured while ensuring the support rigidity for the side gear S. It is possible to reduce the thickness. In the present embodiment, the maximum thickness t2 of the side gear intermediate wall portion Sw is formed to be smaller than the effective diameter d2 of the pinion shaft PS that can be reduced in diameter as described above. Further thinning can be achieved. In addition, since the cover side wall portion Cs is formed in a plate shape whose outer surface is a flat surface orthogonal to the axis L of the output shaft A, the cover side wall portion Cs itself can be thinned.

  As a result, the differential device D should be sufficiently narrow in the axial direction of the output shaft A as a whole while securing the same strength (for example, static torsional load strength) and the maximum torque transmission amount as the conventional device. Can do. As a result, the differential device D can be easily and easily incorporated into a transmission system with many restrictions on the layout around the differential device D with a high degree of freedom, and the transmission system can be downsized. It is advantageous.

  By the way, in 1st Embodiment mentioned above, although what used the long pinion shaft PS as a pinion support part (differential gear support part) was shown, pinion (differential gear) like 2nd Embodiment shown in FIG. A pinion support portion (differential gear support portion) may be configured by a support shaft portion PS ′ that is integrally and coaxially coupled to an end face on the large diameter side of P. According to this configuration, since there is no need to provide a through-hole for fitting the pinion shaft PS in the pinion P, the pinion P can be reduced in diameter (in the axial direction), and the output shaft A of the differential device D can be reduced. Flattening in the axial direction can be achieved. That is, when the pinion shaft PS penetrates the pinion P, it is necessary to form a through hole of a size corresponding to the pinion shaft diameter in the pinion P, but when the support shaft portion PS ′ is integrated with the end surface of the pinion P Therefore, the pinion P can be reduced in diameter (narrower in the axial direction) without depending on the diameter of the support shaft PS ′.

  In the second embodiment, a bearing bush serving as a bearing that allows relative rotation between the outer peripheral surface of the support shaft portion PS ′ and the inner peripheral surface of the holding hole Th of the attachment body T into which the support shaft portion PS ′ is inserted. 12 is inserted. In addition, as a bearing, you may use bearings, such as a needle bearing. Further, the bearing may be omitted and the support shaft portion PS ′ may be directly fitted into the holding hole Th of the attachment body T.

  By the way, a conventional differential device as exemplified in Patent Documents 2 and 3 above (in particular, a pinion (differential gear) in the input member and a pair of side gears (output gears) meshed with the pinion (differential gear)). In the conventional differential device), normally, the number of teeth Z1 of the side gear (output gear) and the number of teeth Z2 of the pinion (differential gear) are, for example, 14 × 10 or 16 × 10 shown in Patent Document 3 or 13 × 9 is used. In this case, the gear ratio Z1 / Z2 of the output gear with respect to the differential gear is 1.4, 1.6, and 1.44, respectively. In addition, in the conventional differential device, other combinations of the number of teeth Z1 and Z2, for example, 15 × 10, 17 × 10, 18 × 10, 19 × 10, or 20 × 10 are also known. In this case, the tooth number ratios Z1 / Z2 are 1.5, 1.7, 1.8, 1.9, and 2.0, respectively.

  On the other hand, the number of transmission devices with layout constraints around the differential device is increasing today, and the differential device is sufficiently narrow in the axial direction of the output shaft while ensuring the gear strength of the differential device (that is, Flattening) is required in the market. However, the conventional differential device has a wide structure in the axial direction of the output shaft, as is clear from the combination of the above-mentioned number of teeth ratios, so it is difficult to satisfy the above market requirements. It is in.

  Therefore, a configuration example of the differential device D capable of sufficiently narrowing (that is, flattening) the differential device in the axial direction of the output shaft while securing the gear strength of the differential device from a viewpoint different from the above-described embodiment. Specific identification will be given below. The structure of each component of the differential device D according to this configuration example is the same as that of each component of the differential device D of the above-described embodiment described with reference to FIGS. 1 to 8 (particularly FIGS. 1 to 7). Therefore, the same reference numerals as those in the above embodiment are used as the reference numerals of the respective components, and the description of the structure is omitted.

First, a basic idea for sufficiently narrowing (that is, flattening) the differential device D in the axial direction of the output shaft A will be described with reference to FIG.
[1] The tooth number ratio Z1 / Z2 of the side gear S, that is, the output gear with respect to the pinion P, that is, the differential gear is increased from the tooth number ratio of the existing differential device. (This reduces the gear module (and hence the tooth thickness) and decreases the gear strength, while the pitch circle diameter of the side gear S increases and the transmission load at the gear meshing portion decreases and the gear strength increases. As a whole, the gear strength decreases as will be described later.)
[2] The pitch cone distance PCD of the pinion P is increased from the pitch cone distance of the existing differential device. (As a result, the gear module is increased and the gear strength is increased, and the pitch circle diameter of the side gear S is increased to reduce the transmission load at the gear meshing portion and increase the gear strength. Thus, the gear strength is greatly increased.)
Accordingly, the amount of reduction in gear strength due to the above [1] is equal to the amount of increase in gear strength due to the above [2], or the amount of gear strength due to the above [2] is larger than the amount of reduction in gear strength due to the above [1]. By setting the gear ratio Z1 / Z2 and the pitch cone distance PCD so that the amount of strength increase is greater, the gear strength as a whole can be equal or increased as compared with conventional differential devices.

Next, the change mode of the gear strength based on the above [1] and [2] will be specifically verified by mathematical expressions. The verification will be described in the following embodiment. First, the differential device D ′ when the number of teeth Z1 of the side gear S is 14 and the number of teeth Z2 of the pinion P is 10 is referred to as a “reference differential device”. The “change rate” is a change rate of various variables when the reference differential device D ′ is used as a reference (ie, 100%).
Regarding [1] When the side gear S module is M, the pitch circle diameter is PD ₁ , the pitch angle is θ ₁ , the pitch cone distance is PCD, the transmission load at the gear meshing portion is F, and the transmission torque is T, the bevel gear From the general formula of
M = PD ₁ / Z1
PD ₁ = 2PCD · sinθ ₁
θ ₁ = tan ^-1 (Z1 / Z2)
From these equations, the gear module is
M = 2PCD · sin {tan ⁻¹ (Z1 / Z2)} / Z1 (1)
And
The module of the reference differential device D ′ is 2PCD · sin {tan ⁻¹ (7/5)} / 14.
It becomes.

  Therefore, by dividing the right term of both equations, the module change rate with respect to the reference differential device D ′ is expressed by the following equation (2).

  Further, the section modulus of the tooth portion corresponding to the gear strength (that is, the bending strength of the tooth portion) is proportional to the square of the tooth thickness, and the tooth thickness is in a substantially linear relationship with the module M. Accordingly, the square of the module change rate corresponds to the change rate of the section modulus of the tooth portion, and thus the change rate of the gear strength. That is, the gear strength change rate is expressed by the following equation (3) based on the equation (2). Equation (3) is indicated by L1 in FIG. 10 when the number of teeth Z2 of the pinion P is 10, and it can be seen that the gear strength decreases due to the module decrease as the number of teeth ratio Z1 / Z2 increases.

  By the way, from the general formula of the bevel gear described above, the torque transmission distance of the side gear S is expressed by the following equation (4).

_{PD 1/2 = PCD · sin} {tan -1 (Z1 / Z2)} ··· (4)
The transmission load F due to the torque transmission distance PD _1/2 is F = 2T / PD ₁ . Therefore, if the torque T is constant in the side gear S of the reference differential device D ′, the transmission load F and the pitch circle diameter PD ₁ are in an inversely proportional relationship. The rate of change in transmitted load F, since the both the rate of change of the gear strength is inversely proportional to the rate of change in gear strength is equal to the rate of change of the pitch diameter PD _1.

As a result, the change rate of the pitch circle diameter PD ₁ is expressed by the following equation (5) using the equation (4).

  The expression (5) is indicated by L2 in FIG. 10 when the number of teeth Z2 of the pinion P is 10, and it can be seen that as the number of teeth ratio Z1 / Z2 increases, the gear strength increases as the transmission load decreases.

  After all, the change rate of the gear strength with the increase in the tooth number ratio Z1 / Z2 is the change rate of the gear strength due to the decrease of the module M (the right term of the above equation (3)) and the reduction of the transmission load. It is expressed as the following equation (6) by multiplication with the rate of increase in gear strength (the right term of the above equation (5)).

Equation (6) is indicated by L3 in FIG. 10 when the number of teeth Z2 of the pinion P is 10, and it can be seen that the gear strength as a whole decreases as the number of teeth ratio Z1 / Z2 increases.
[2] When the pitch cone distance PCD of the pinion P is increased beyond the pitch cone distance of the reference differential device D ′, when the PCD before the change is PCD1 and the PCD after the change is PCD2, before and after the change of the PCD According to the general formula of the bevel gear described above, the module change rate is (PCD2 / PCD1) if the number of teeth is constant.

On the other hand, the change rate of the gear strength of the side gear S corresponds to the square of the module change rate, as is apparent from the process of deriving the equation (3).
Gear strength change rate due to module increase = (PCD2 / PCD1) ² (7)
The equation (7) is indicated by L4 in FIG. 11, and it can be seen that the gear strength increases due to the module increase as the pitch cone distance PCD increases.

Further, when the pitch cone distance PCD is increased beyond the pitch cone distance PCD1 of the reference differential device D ′, the transmission load F is reduced. As a result, the change rate of the gear strength is as described above. equal to the rate of change of the diameter PD _1. Also there is a proportional relationship with the pitch diameter PD ₁ and a pitch cone distance PCD side gear S. Therefore,
Gear strength change rate due to reduced transmission load = PCD2 / PCD1 (8)
Expression (8) is indicated by L5 in FIG. 11, and it can be seen that as the pitch cone distance PCD increases, the gear strength increases due to the transmission load reduction.

  The change rate of the gear strength accompanying the increase in the pitch cone distance PCD is the change rate of the gear strength due to the increase in the module M (the right term in the above equation (7)) and the increase in the pitch circle diameter PD. The following equation (9) is obtained by multiplying with the rate of increase change in gear strength due to the reduction of the transmission load (the right term of the above equation (8)).

Gear strength change rate due to increase in pitch cone distance = (PCD2 / PCD1) ³ (9)
The expression (9) is indicated by L6 in FIG. 11, and it can be seen that the gear strength is greatly increased as the pitch cone distance PCD increases.

  Then, the decrease in gear strength due to the method [1] (increase in the number of teeth ratio) is sufficiently compensated by the increase in gear strength due to the method [2] (increase in pitch cone distance). The combination of the gear ratio Z1 / Z2 and the pitch cone distance PCD is determined so that the gear strength is equal to or higher than the gear strength of the existing differential gear.

  For example, when the gear strength of the side gear S of the reference differential device D ′ is maintained at 100%, the change rate of the gear strength with the increase in the tooth number ratio obtained in [1] (the right term of the above equation (6)). ) And the gear strength change rate (right term of (9) described above) obtained by increasing the pitch cone distance obtained in [2] may be set to 100%. Accordingly, the relationship between the gear ratio Z1 / Z2 and the rate of change of the pitch cone distance PCD when the gear strength of the reference differential device D ′ is maintained at 100% can be obtained by the following equation (10). The expression (10) is indicated by L7 in FIG. 12 when the number of teeth Z2 of the pinion P is 10.

  In this way, the expression (10) indicates that the change in the tooth number ratio Z1 / Z2 and the pitch cone distance PCD in the case where the gear strength of the reference differential device D ′ with the tooth number ratio Z1 / Z2 = 14/10 is maintained at 100%. The change rate of the pitch cone distance PCD on the vertical axis in FIG. 12 indicates the shaft diameter of the pinion shaft PS (that is, the pinion support portion) that supports the pinion P. In this case, the ratio can be converted to a ratio of d2 / PCD.

That is, in an existing differential device, an increase in pitch cone distance PCD is correlated with an increase in d2 as shown in Table 1 above, and when d2 is constant, the ratio of d2 / PCD decreases. It can be expressed. Moreover, in the conventional differential device, as shown in Table 1, when the reference differential device D ′ is used, d2 / PCD is within the range of 40 to 45%, and when the PCD is increased, the gear strength is increased. Therefore, when the shaft diameter d2 and the pitch cone distance PCD of the pinion shaft PS are determined so that at least d2 / PCD is 45% or less at the time of the reference differential device D ′, the gear strength is different from the existing difference. It can be equal to or greater than the gear strength of the moving device. That is, in the case of the reference differential device D ′,
d2 / PCD ≦ 0.45 may be satisfied. In this case, if the PCD after the increase / decrease change is PCD2 with respect to the pitch cone distance PCD1 of the reference differential device D ′,
d2 / PCD2 ≦ 0.45 / (PCD2 / PCD1) (11)
It will be sufficient to satisfy. Then, by applying the expression (11) to the above expression (10), the relationship between d2 / PCD and the tooth number ratio Z1 / Z2 can be converted as the following expression (12).

  When the equal sign of the expression (12) is established, when the number of teeth Z2 of the pinion P is 10, it can be expressed as L8 in FIG. The time when the equality in equation (12) is established is the relationship between d2 / PCD and the tooth number ratio Z1 / Z2 when the gear strength of the reference differential device D ′ is maintained at 100%.

  By the way, in the conventional differential device, as described above, not only the tooth number ratio Z1 / Z2 is set to 1.4 as in the reference differential device D ′, but also the tooth number ratio Z1 / Z2 is set to 1. .6 and those having a tooth number ratio Z1 / Z2 of 1.44 are also employed. Based on this fact, if it is assumed that the reference differential device D ′ (Z1 / Z2 = 1.4) can provide a sufficient and sufficient gear strength, that is, a gear strength of 100%, a conventional differential device has As can be seen from FIG. 10, in the differential device having the number ratio Z1 / Z2 of 16/10, the gear strength is reduced to 87% as compared with the reference differential device D ′. However, the gear strength reduced to such a degree is allowed as a practical strength and is practically used in existing differential devices. Therefore, even in a differential device that is flat in the axial direction, if the gear strength is at least 87% with respect to the reference differential device D ′, it is considered that the gear strength is sufficiently secured and allowed.

  From this point of view, when the relationship between the gear ratio Z1 / Z2 and the rate of change in the pitch cone distance PCD when the gear strength of the reference differential device D ′ is maintained at 87%, the relationship is: Following the process of deriving equation (10), calculation (ie, the rate of change in gear strength accompanying the increase in the number of teeth ratio (the right term in equation (6) above) and the rate of change in gear strength due to the increase in pitch cone distance (as described above ( 9) is multiplied so as to be 87%, and can be expressed as the following equation (10 ′).

  If the above-described equation (11) is applied to the above-described equation (10 ′), d2 / PCD and the gear ratio Z1 / Z2 when the gear strength of the reference differential device D ′ is maintained at 87% or more. Can be converted as in the following equation (13). However, in the calculation process, except for terms expressed using variables, the significant figures are calculated with 3 digits, and the other digits are rounded down, so that they are actually almost equal due to calculation errors. However, in the expression of the expression, it shall be expressed with an equal sign.

  When the equal sign of equation (13) holds, when the number of teeth Z2 of the pinion P is 10, it can be expressed as shown in FIG. 13 (more specifically, as shown by the line L9 in FIG. 13). In this case, the region corresponding to the expression (13) is the region above the L9 line and below the L9 line in FIG. And the specific region (hatching region in FIG. 13) that satisfies the equation (13) and satisfies that the tooth number ratio Z1 / Z2 on the right side of the L10 line in FIG. In a differential gear flat in the axial direction in which the number of teeth Z2 is 10 and the gear ratio Z1 / Z2 exceeds 2.0, Z1 / Z2 that can secure a gear strength of at least 87% with respect to the reference differential gear D ′; This is a setting area for d2 / PCD. For reference, if an example when the tooth number ratio Z1 / Z2 is set to 40/10 and d2 / PCD is set to 20.00% in FIG. 13 is illustrated in FIG. In the example shown in FIG. 13, when the tooth number ratio Z1 / Z2 is set to 58/10 and d2 / PCD is set to 16.67%, it becomes like a triangular point. It is settled. As a result of performing a strength analysis by simulation with respect to these embodiments, a gear strength equal to or higher than that of a conventional gear strength (more specifically, a gear strength of 87% or higher with respect to the reference differential device D ′). ) Was obtained.

  Therefore, the flat differential device in the specific area as a whole while securing the same gear strength (for example, static torsional load strength) and maximum torque transmission amount as conventional non-flat differential devices. It is configured as a differential device with a sufficiently narrow width in the axial direction of the output shaft. Therefore, the differential device can be used with a high degree of freedom even for transmission systems with many layout constraints around the differential device. As a result, it can be easily assembled without difficulty, and it is possible to achieve advantages such as being advantageous in reducing the size of the transmission system.

  Further, when the structure of the flat differential device in the specific area is, for example, the structure of the above-described embodiment (more specifically, the structure shown in FIGS. 1 to 8), the specific area A certain flat differential device can also achieve the effect accompanying the structure shown in the above-described embodiment.

  The above description (especially with respect to FIGS. 10, 12, and 13) is performed with respect to the differential when the number of teeth Z2 of the pinion P is 10, but the present invention is not limited to this. Absent. For example, when the number of teeth Z2 of the pinion P is set to 6, 12, and 20, the flat differential device that can achieve the above effect is (13) as shown by hatching in FIGS. It can be expressed by a formula. That is, the expression (13) derived as described above can be applied regardless of the change in the number of teeth Z2 of the pinion P. For example, when the number of teeth Z2 of the pinion P is 6, 12, 20 However, as in the case where the number of teeth Z2 of the pinion P is 10, the number of teeth Z1 of the side gear S, the number of teeth Z2 of the pinion P, the shaft diameter d2 of the pinion shaft PS, and the pitch cone distance PCD so as to satisfy the expression (13). The above effect can be obtained by setting.

  For reference, in the case where the number of teeth Z2 of the pinion P is 12, the embodiment when the tooth number ratio Z1 / Z2 is set to 48/12 and d2 / PCD is set to 20.00% is shown in FIG. FIG. 15 illustrates an example of the case where the ratio of the teeth number Z1 / Z2 is set to 70/12 and d2 / PCD is set to 16.67%. As a result of performing a strength analysis by simulation with respect to these embodiments, a gear strength equal to or higher than that of a conventional gear strength (more specifically, a gear strength of 87% or higher with respect to the reference differential device D ′). ) Was obtained. Further, these examples are within the specific area as shown in FIG.

  As a comparative example, in an example that does not fall within the above specific range, for example, when the number of teeth Z2 of the pinion P is 10, the tooth number ratio Z1 / Z2 is set to 58/10 and d2 / PCD is set to 27.50%. In the case where the number of teeth Z2 of the pinion P is 10 and the tooth number ratio Z1 / Z2 is set to 40/10 and d2 / PCD is set to 34.29%, respectively. When the number of teeth Z2 of the pinion P is set to 12 in FIG. 13, the tooth number ratio Z1 / Z2 is set to 70/12, and the d2 / PCD is set to 27.50%. In the case of the star point in FIG. 15 where the number of teeth Z2 of the pinion P is 12, the tooth number ratio Z1 / Z2 is set to 48/12 and d2 / PCD is set to 34.29%. Example of time is indicated by the dot in FIG.As a result of performing a strength analysis by simulation for these examples, a gear strength equal to or higher than the conventional one (more specifically, a gear strength of 87% or higher than the reference differential device D ′) is obtained. It was confirmed that was not obtained. In other words, it was confirmed that the above-mentioned effects could not be obtained in the examples not falling within the specific range.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment mentioned above, A various design change is possible in the range which does not deviate from the summary.

  For example, in the above-described embodiment, the lubricant that randomly scatters in the mission case 1 is shown to naturally flow through the lightening portions 8 of the cover portions C and C ′. Lubricating oil that repels in a specific direction with the rotation of the differential device D in the mission case 1 or lubricating oil that drops from a ceiling portion of the mission case 1 to a specific location may be actively introduced. Alternatively, the lubricating oil may be forcibly pumped by a lubricating oil pump.

  Further, in the above-described embodiment, the thinned portion 8 is provided on the side wall Cs of at least one of the left and right covers C, C ′. However, the side wall Cs of any of the left and right covers C, C ′ is also provided. You may make it cover the whole back surface of the corresponding side gear S by the side wall part Cs so that the lightening part 8 may not be formed.

  In the above-described embodiment, the oil path from the thinned portion 8 formed in the side wall portion Cs of the cover portions C and C ′ to the oil guide groove 17 is described as the oil route through which the lubricating oil is guided to the outside of the side gear S. However, instead of or in addition to such a lightening portion 8 (oil guide groove 17), other oil paths can be implemented. As another oil path, for example, a spiral groove is formed in at least one of the fitting surfaces of the shaft portion Sj of the side gear S and the boss portion Cb of the cover portions C and C ′, and the shaft portion Sj and the boss portion Cb The lubricating oil may be guided to the outer surface of the side gear S from the outside of the cover portions C and C ′ through the spiral groove in conjunction with the relative rotation of the side gear S. Alternatively, a through oil passage is formed in the side wall portion Cs of the cover portions C and C ′ separately from the thinned portion 8 so that the lubricating oil is guided from the outside of the cover portions C and C ′ to the outer surface of the side gear S. Also good.

  In the embodiment described above, the input member I is integrally provided with the input tooth portion Ig. However, a ring gear formed separately from the input member I may be fixed to the input member I by retrofitting. . The input member of the present invention may have a structure not including the input tooth portion Ig and the ring gear as described above. For example, the input member I is a drive member positioned upstream of the input member I in the power transmission path. For example, a rotational driving force may be input to the input member I by interlocking with and coupled to an output member of a planetary gear mechanism or a reduction gear mechanism, a driven wheel of an endless transmission band type transmission mechanism, or the like.

  Further, in the above-described embodiment, the back surface of the pair of side gears S is shown as being covered with the pair of cover portions C and C ′. However, in the present invention, the cover portion is provided only on the back surface of the one side gear S. May be. In this case, for example, a drive member located upstream in the power transmission path is disposed on the side where the cover part is not provided, and the drive member and the input member are linked and connected on the side where the cover part is not provided. You may do it.

  Further, in the above-described embodiment, the differential device D allows the rotational difference between the left and right axles. However, the differential device of the present invention is also applied to the center differential that absorbs the rotational difference between the front wheels and the rear wheels. Is possible.

A ... Output shaft C, C '... Cover portion Cs ... Side wall D ... Differential gear d2 ... Diameter of pinion shaft, diameter of support shaft (pinion support) Diameter, differential gear support diameter)
I: Input member P: Pinion (differential gear)
PCD ・ ・ ・ Pitch cone distance PS ・ ・ ・ ・ Pinion shaft (Pinion support, differential gear support)
PS '... support shaft (pinion support, differential gear support)
S: Side gear (output gear)
Sj ··· Shaft portion Sg ··· Tooth portion Sw · · · Intermediate wall portion W · · · Washer 8 · Meat removal portion 15 · · · through oil passage 16 · · ·・ Washer holding groove 17 ... Oil guide groove

Claims (7)

The rotational force of the input member (I) that supports the pinion support (PS, PS ′) that supports the pinion (P) and is rotatable together with the pinion support (PS, PS ′) is applied to the pinion (P). A differential device that distributes and transmits to a pair of output shafts (A) via a pair of side gears (S) having meshing teeth (Sg) on an outer peripheral portion,
The pair of side gears (S) includes a shaft portion (Sj) connected to the pair of output shafts (A), the shaft portion (Sj), and the shaft portion (Sj) of the input member (I). A flat intermediate wall portion (Sw) that integrally connects the tooth portions (Sg) spaced radially outwardly;
The intermediate wall (Sw) of at least one of the side gears (S) is formed with a through oil passage (15) having both ends opened on the inner surface and the outer surface of the intermediate wall (Sw). A differential device characterized by. A cover portion (C, C ′) having a side wall portion (Cs) covering an outer surface of the at least one side gear (S) and coupled to rotate integrally with the input member (I); A washer (W) interposed between the inner surface of the side wall (Cs) and the outer surface of the side gear (S),
The washer (W) and the through oil passage (so that at least the inner periphery of the washer (W) faces the opening of the through oil passage (15) to the outer surface of the intermediate wall portion (Sw). 15. The differential device according to claim 1, wherein the relative position of 15) is set.   A washer holding groove (16) for fitting and holding the washer (W) is formed on at least one of the opposing surfaces of the inner side surface of the side wall portion (Cs) and the outer side surface of the side gear (S). The differential device according to claim 2, wherein the differential device is a characteristic. The side wall (Cs) includes a lightening portion (8) that exposes an outer surface of the side gear (S),
Lubricating oil flows into the inner side surface of the side wall portion (Cs) from the periphery of the thinned portion (8) to the washer (W) and the through oil passage (15) when the input member (I) rotates. The differential device according to claim 2 or 3, characterized in that an oil guide groove (17) capable of guiding the oil is recessed. The rotational force of the input member (I) that supports the differential gear support (PS, PS ′) that supports the differential gear (P) and is rotatable together with the differential gear support (PS, PS ′), A differential device that distributes and transmits to a pair of output shafts (A) via a pair of output gears (S) having teeth (Sg) meshing with the differential gear (P) on the outer periphery,
The pair of output gears (S) includes a shaft portion (Sj) connected to the pair of output shafts (A), the shaft portion (Sj), and the shaft portion (Sj) to the input member (I). A flat intermediate wall portion (Sw) that integrally connects the tooth portions (Sg) that are spaced apart radially outward from each other,
The intermediate wall (Sw) of at least one of the output gears (S) is formed with a through oil passage (15) having both ends opened on the inner surface and the outer surface of the intermediate wall (Sw).
The number of teeth of the output gear (S) is Z1, the number of teeth of the differential gear (P) is Z2, the diameter of the differential gear support (PS, PS ') is d2, and the pitch cone distance is PCD. And when

The filling,
A differential device satisfying Z1 / Z2> 2.   The differential device according to claim 5, wherein Z1 / Z2 ≧ 4 is satisfied.   The differential device according to claim 5, wherein Z1 / Z2 ≧ 5.8 is satisfied.

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