JP2016194362A - Differential gear for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a differential gear for a vehicle capable of efficiently taking a lubricant in a mission case into a differential case, in particular, into a rotary sliding portion between a pinion and a pinion shaft.SOLUTION: A differential case DC has a plurality of oil holes H1, H2 penetrating through the inside and outside of an outer peripheral wall 4 and capable of taking a lubricant into the differential case at positions offset to a pinion P side with respect to an intermediate point m between two pinions P adjacent to each other in the circumferential direction of the differential case. The oil holes H1, H2 are formed so that axes of the oil holes are inclined to a front side in a rotating direction of the differential case when a vehicle advances from an inner opening end Hi toward an outer opening end Ho of the oil holes when observed at a projection face orthogonal to a rotation axis L of the differential case, and the pinions P are disposed outside of a region A held by a first virtual line L1 connecting one circumferential end of the inner opening end Hi of each oil hole and the rotation axis L, and a second virtual line L2 connecting the circumferential other end of the inner opening end Hi of each oil hole and the rotation axis L.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a differential device, and more particularly to a vehicle differential device that distributes and transmits a rotational force transmitted from an in-vehicle power source to a differential case housed in a transmission case to a pair of output shafts.

  Conventionally, in the above-described differential device, the differential case has a plurality of oil intake holes that penetrate the inside and outside of the outer peripheral wall of the differential case and take lubricating oil into the differential case at intervals in the circumferential direction. 1 as well.

Japanese Patent No. 3915719 Japanese Patent No. 4803871 JP 2002-364728 A

  However, in Patent Document 1, although consideration is given to the position and orientation of a plurality of oil intake holes provided on the outer peripheral wall of the differential case, the consideration is simply to efficiently store the stored lubricating oil at the bottom of the transmission case in the differential case. For scraping or scooping up, special consideration is given to the lubrication oil in the transmission case being taken into the rotating sliding part between the pinion (differential gear) and the pinion shaft (differential gear support part) It was not what I did.

  The present invention has been made in view of such circumstances, and takes in lubricating oil in a transmission case into a differential case, in particular, rotation between a pinion (differential gear) and a pinion shaft (differential gear support). An object of the present invention is to provide a vehicle differential device that can be efficiently taken into a sliding portion with a simple structure.

  In order to achieve the above object, a vehicle differential device according to the present invention is a vehicle that distributes and transmits rotational force transmitted from a power source mounted on a vehicle to a differential case accommodated in a transmission case, to a pair of output shafts. A differential for differential, a pinion disposed in the differential case, a pinion shaft disposed so as to pass through a rotation axis of the differential case and supported by the differential case and rotatably supporting the pinion, A pair of side gears meshed with the pinion in the differential case and connected to the pair of output shafts, respectively, the differential case penetrating the inside and outside of the outer peripheral wall of the differential case, and supplying the lubricating oil in the transmission case A plurality of oil intake holes that can be taken into the differential case are respectively connected to the two pinions adjacent in the circumferential direction of the differential case. Each oil take-in hole is located at a position offset to the pinion side from the intermediate point, and each oil take-in hole is viewed from a projection plane orthogonal to the rotation axis, and the axis of the oil take-in hole is from the inner opening end of the oil take-in hole. It is formed so as to incline toward the front side in the rotational direction of the differential case when the vehicle advances toward the outer opening end, and the pinion is one end in the circumferential direction of the inner opening end of each oil intake hole when viewed from the projection plane. And a first imaginary line that connects the rotation axis, and a region that is sandwiched between a second imaginary line that connects the other end in the circumferential direction of the inner opening end of each oil intake hole and the rotation axis. (This is the first feature).

  Preferably, the side gear includes a shaft portion connected to each of the pair of output shafts, the gear portion spaced radially outward from the shaft portion, and a radially outward direction from an inner end portion of the shaft portion. And a flat intermediate wall portion extending to (this is a second feature).

  In order to achieve the above object, the vehicle differential device according to the present invention distributes and transmits the rotational force transmitted from the in-vehicle power source to the differential case accommodated in the transmission case to the pair of output shafts. A differential device for a vehicle, wherein the differential gear is disposed in the differential case, and is disposed so as to pass through a rotation axis of the differential case, and is supported by the differential case and rotatably supports the differential gear. A differential gear support; and a pair of output gears that mesh with the differential gear in the differential case and that are connected to the pair of output shafts, respectively, and the differential case penetrates the inside and outside of the outer peripheral wall of the differential case A plurality of oil intake holes through which the lubricating oil in the transmission case can be taken into the differential case are provided between two differential gears adjacent in the circumferential direction of the differential case. The oil intake holes are located at positions offset to the differential gear side, and each oil intake hole is viewed from a projection plane orthogonal to the rotation axis, so that the axis of the oil intake hole extends from the inner opening end of the oil intake hole. The differential gear is formed so as to incline toward the front side in the rotational direction of the differential case when the vehicle moves forward toward the outer opening end, and the differential gear is a periphery of the inner opening end of each oil intake hole when viewed in the projection plane. Outside a region sandwiched between a first imaginary line connecting one end in the direction and the rotation axis, and a second imaginary line connecting the other end in the circumferential direction of the inner opening end of each oil intake hole and the rotation axis. The number of teeth of the output gear is Z1, the number of teeth of the differential gear is Z2, the diameter of the differential gear support is d2, and the pitch cone distance is PCD.

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

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

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

  Preferably, the oil intake hole has a circular cross-sectional shape perpendicular to the axis of the oil intake hole (this is a sixth feature).

  According to the first feature, the outer peripheral wall of the differential case has a plurality of oil intake holes through which the lubricating oil in the transmission case can be taken into the differential case from the midpoint of two pinions adjacent in the circumferential direction of the differential case. The oil intake holes are offset on the pinion side, and each oil intake hole is viewed from a projection plane orthogonal to the rotation axis of the differential case, and the axis of the oil intake hole moves from the inner opening end of the hole toward the outer opening end when the vehicle advances. A first imaginary line connecting the circumferential end of the inner opening end of each oil intake hole and the rotation axis of the differential case, as viewed from the projection plane, is formed so as to incline toward the rotation direction front side of the differential case, Since the oil intake holes are arranged outside the region sandwiched between the other circumferential end of the inner opening end of each oil intake hole and the second imaginary line connecting the rotation axis of the differential case, the lubricating oil in the transmission case is made up of a plurality of oils. Intake hole The efficient possible incorporation into the differential case through. Moreover, among the plurality of oil intake holes, the oil intake holes that are offset from the intermediate point to the pinion side on the front side in the rotation direction of each pinion, in particular, the lubricating oil taken into the differential case and the pinion and side gear near the oil intake hole Can be efficiently supplied to the meshing portion. On the other hand, the oil intake holes that are offset from the intermediate point on the rear side in the rotational direction of each pinion are not obstructed by the pinion (i.e., the pinion becomes an obstacle). It can be supplied to the outer periphery of the pinion shaft near the rotation center of the differential case (without standing in the lubricating oil path), and the supplied lubricating oil travels along the outer peripheral surface of the shaft by centrifugal force, that is, between the outer end of the shaft, that is, between the pinion and the pinion shaft. Since it goes to the rotation sliding part side, lubricating oil can be efficiently supplied also to the rotation sliding part. As a result, the lubricating oil in the transmission case can be efficiently supplied not only to the meshing part of the pinion with the side gear but also to the rotational sliding part of the pinion and the pinion shaft, thereby improving the overall lubrication efficiency. .

  According to the second feature, the side gear includes a shaft portion connected to each of the pair of output shafts, a gear portion spaced radially outward from the shaft portion, and a plate extending radially outward from the inner end of the shaft portion. Since the side gear can be made as large as possible 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, the load burden on the pinion shaft is reduced and extended. By reducing the diameter, the differential case can contribute to narrowing the width of the output shaft in the axial direction. Even if the oil intake hole is offset to the pinion side when viewed from the projection plane, the pinion is located outside the region, that is, the diameter is sufficiently reduced with respect to the side gear. In spite of being arranged on the pinion side in the circumferential direction of the differential case as described above (that is, closer to the pinion), the pinion can be easily arranged outside the region corresponding to the inner opening end of the oil intake hole, and the pinion and the pinion A sufficient lubrication effect on the rotating sliding portion between the shafts can be secured.

  According to the third feature, the lubricating oil in the transmission case can be efficiently taken into the differential case through the plurality of oil taking holes. In addition, among the plurality of oil intake holes, the oil intake holes that are offset from the intermediate point on the differential gear side on the front side in the rotational direction of the differential case when the vehicle advances, in particular, are lubricating oil that has been taken into the differential case. Can be efficiently supplied to the meshing portion between the differential gear and the output gear near the oil intake hole. On the other hand, the oil intake holes that are offset from the intermediate point on the rear side in the rotational direction of each differential gear are not obstructed by the differential gear. (Without the moving gear becoming an obstacle and standing in the lubricating oil path) The differential gear support can be supplied to the portion near the center of rotation of the differential case, and the supplied lubricating oil is transferred to the differential gear support by centrifugal force. Since it goes to the end side, that is, the rotational sliding part side between the differential gear and the differential gear support part, the lubricating oil can be efficiently supplied also to the rotational sliding part. As a result, the lubricating oil in the transmission case is efficiently supplied not only to the meshing part of the differential gear with the output gear but also to the rotating sliding part of the differential gear and the differential gear support part. As a result, the lubrication efficiency can be increased. In addition, according to the third feature, the differential device as a whole is sufficiently narrow 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. As a result, it is possible to easily incorporate a differential gear into a transmission system with many layout constraints around the differential gear with a high degree of freedom, and it is advantageous for downsizing the transmission system. .

  In particular, according to each of the fourth and fifth features, the differential device is more sufficiently installed 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.

  According to the sixth feature, the oil intake hole has a circular cross section perpendicular to the axis of the hole, that is, a cross section shape that is easy to machine. Thus, even when adopting a manufacturing method in which it is difficult to form the oil intake hole at the same time when forming the differential case, the oil intake hole can be easily machined after the differential case is formed, which contributes to the reduction of manufacturing costs. it can.

FIG. 2 is a longitudinal sectional view of a main part of a differential gear and a reduction gear mechanism according to an embodiment of the present invention (sectional view taken along line 1A-1A in FIG. 2). Side view of one side in the axial direction with a part of the differential device broken (sectional view taken along line 2A-2A in FIG. 1) Side view of the main part on the other axial side of the differential device (sectional view taken along line 3A-3A in FIG. 1) FIG. 4 is a cross-sectional view taken along line 4A-4A in FIG. 1 and shows only one cover portion C by a solid line. FIG. 5 is a cross-sectional view taken along line 5A-5A in FIG. 1 and shows only the other cover portion C ′ and the input member with solid lines. (A) is the enlarged view of the 6A arrow part of FIG. 1, (B) is the BA-BA sectional view taken on the line of (A). 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, in FIG. 1, a differential device D is connected to an engine (not shown) as a power source mounted on an automobile via a reduction gear mechanism RG. The differential device D distributes and transmits the rotational force transmitted from the engine to the differential case DC via the reduction gear mechanism RG to the pair of left and right output shafts J respectively connected to the pair of left and right axles, thereby transmitting the left and right axles. For driving while allowing differential rotation of the left and right axles, for example, in a transmission case M arranged beside the engine at the front of the vehicle body, the reduction gear mechanism RG is adjacent to the reduction gear mechanism RG. Is housed together. A conventionally known power connection / disconnection mechanism and forward / reverse switching mechanism (both not shown) are interposed between the engine and the reduction gear mechanism RG. Further, the rotation axis (rotation center) L of the differential case DC coincides with the center axis of the output shaft J.

  In the illustrated example, the reduction gear mechanism RG includes a sun gear 50 that rotates in conjunction with the crankshaft of the engine, a ring gear 51 that concentrically surrounds the sun gear 50 and is fixed to the inner wall of the transmission case M, and between the sun gear 50 and the ring gear 51. And a planetary gear mechanism including a plurality of planetary gears 52 that mesh with both gears 50 and 51, and a carrier 53 that rotatably supports the planetary gear 52. In place of such a planetary gear mechanism, a reduction gear mechanism comprising a gear train of a plurality of spur gears may be used.

  The carrier 53 is rotatably supported by the transmission case M via a bearing (not shown). The carrier 53 is coupled to one end portion of the differential case DC of the differential device D so as to rotate integrally, and the other end portion of the differential case DC is rotatably supported by the transmission case M via the bearing 2. . Therefore, the combination of the differential case DC and the carrier 53 that rotate integrally with each other is stably and stably supported by the mission case M via the plurality of bearings.

  The transmission case M is formed with a through hole Ma into which each output shaft J is inserted, and an annular seal member 3 that seals between the inner periphery of the through hole Ma and the outer periphery of each output shaft J. Is installed. Further, an oil pan (not shown) for storing a predetermined amount of lubricating oil facing the internal space 1 of the mission case M is provided at the bottom of the mission case M, and the lubricating oil stored in the oil pan is stored in the mission case. In the internal space 1 of M, the mechanical movement portions existing inside and outside the differential case DC can be lubricated by being scattered and scattered around the rotation part by the rotation of the movable element of the reduction gear mechanism RG and the differential case DC. . The lubricating oil is sucked by an oil pump (not shown) and forced toward a specific part of the internal space 1 of the mission case M, for example, the reduction gear mechanism RG or the differential case DC, or the inner wall of the mission case M in the vicinity thereof. May be scattered or dispersed.

  Incidentally, the ceiling wall Mt of the mission case M has an inclined portion that goes down directly above the differential case DC, as is apparent from FIG. A part of the lubricating oil scattered in the transmission case M as described above adheres to the ceiling wall Mt of the transmission case M and flows to the lower side along the inclined inner surface Mtf of the ceiling wall Mt. It is dropped from the specific part of Mt, for example, the terminal part of the inclined inner surface Mtf (that is, the boundary part with the horizontal surface of the ceiling wall) toward the differential case DC immediately below. As a result, a part of the dropped lubricating oil can be taken into oil take-in holes H1 and H2, which will be described later, opened on the outer peripheral surface of the differential case DC. Even when the ceiling wall Mt of the transmission case M does not have the inclined portion as described above, a large amount of lubricating oil is scattered and adhered to the ceiling wall Mt. It is dripped at random from each place of this, The part can be taken in into the said oil taking-in hole H1, H2.

  2 to 6, the differential device D includes a differential case DC, a plurality of pinions (differential gears) P accommodated in the differential case DC, and a pinion P accommodated in the differential case DC. A pinion shaft (differential gear support portion) PS that is rotatably supported, and a pair of left and right side gears that are housed in the differential case DC and mesh with the pinion P from the left and right sides and connected to the pair of left and right output shafts J (each Output gear) S. The differential case DC includes a short cylindrical case main body 4 that supports the pinion shaft PS so as to be able to rotate together with the pinion shaft PS, and a pair of right and left that covers the outer sides of both side gears S and rotates integrally with the case main body 4. Cover part C, C ', and the case body 4 constitutes the outer peripheral wall of the differential case DC.

  The pinion shaft PS is, for example, arranged so as to pass through the rotation axis L of the differential case DC in the differential case DC, and a pair of through support holes provided in the case main body 4 on one diameter line of the case main body 4 Both end portions of the shaft are inserted into 4a so as to be insertable / removable. The pinion shaft PS is fixed to the case body 4 with a retaining pin 5 that passes through one end of the pinion shaft PS and is attached to the case body 4. In a state where the pinion shaft PS is fixed to the case main body portion 4, both outer end surfaces PSf of the pinion shaft PS pass through the opening DCo (that is, the outer end opening of the through support hole 4a) in the outer peripheral surface of the differential case DC. 1

  In the present embodiment, two pinions P are provided, and the pinion shaft PS is formed in a straight bar shape extending along one diameter line of the case main body 4, and the two pinions P are respectively supported at both ends of the pinion shaft PS. Although what was made to show was shown, you may provide three or more pinions P. FIG. In that case, the pinion shaft PS is crossed into three or more directions from the rotation axis L of the differential case DC corresponding to three or more pinions P and extends radially (for example, when there are four pinions P). The pinion P is supported on each tip of the pinion shaft PS, and the case body 4 is divided into two parts, and the pinion shaft PS is sandwiched between the divided elements. Like that.

  Further, the pinion P may be directly fitted to the pinion shaft PS as shown in the figure, or may be fitted via a bearing means (not shown) such as a bearing bush. In the former case, the fitting portion between the pinion shaft PS and the pinion P is a rotational sliding portion rs between the pinion shaft PS and the pinion P. In the latter case, the bearing means is It becomes a rotation sliding part rs. Note that the pinion shaft PS may have a substantially uniform shaft diameter as in the illustrated example, or may have a stepped shaft shape.

  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 are located at the cylindrical shaft portion Sj in which the inner ends of the pair of output shafts J are respectively spline-fitted 6, and at positions away from the shaft portion Sj radially outward of the differential case DC. An annular tooth portion Sg meshing with the pinion P and an intermediate wall portion formed in a flat ring plate shape orthogonal to the axis L of the output shaft J and integrally connecting the shaft portion Sj and the tooth portion Sg Sw. The shaft portion Sj of the side gear S is directly fitted in a freely rotatable manner to the boss portion Cb of the cover portions C and C ′ in the illustrated example, but may be fitted via a bearing.

  The intermediate wall portion Sw of at least one of the left and right (both in the present embodiment) side gears S has through oil passages 15 that open at both inner and outer surfaces of the intermediate wall portion Sw and cross the intermediate wall portion Sw. It is formed.

  Further, the intermediate wall part Sw of the side gear S has a radial width t1 of the intermediate wall part Sw larger than the maximum diameter d1 of the pinion P, and the intermediate wall part Sw has a maximum wall thickness in the axial direction of the output shaft J. The thickness t2 is formed to be smaller than the effective diameter d2 of the pinion shaft PS, that is, the outer diameter (see FIG. 1). Thereby, 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 J. The side gear S can be sufficiently thinned.

  One of the pair of left and right cover portions C and C ′ in the differential case DC, for example, the cover portion C on the opposite side of the reduction gear mechanism RG is formed separately from the case main body portion 4 to form the case main body. The part 4 is detachably coupled with a bolt B. As the coupling means, various coupling means other than the screw means such as welding means and caulking means can be used. In the illustrated example, the other side cover portion C ′ is integrally formed with the case main body portion 4 and coupled to the carrier 53 of the reduction gear mechanism RG, but the cover portion C ′ is connected to the one side cover portion C. Similarly, it may be formed separately from the case body 4 and coupled to the case body 4 with 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 orthogonal to the rotation axis L of the differential case DC. And a plate-like side wall Cs integrally connected to the inner end in the axial direction of the boss Cb as a flat surface. The side walls Cs of the covers C and C ′ are arranged in the axial direction of the output shaft J. It arrange | positions so that it may be settled in the width | variety of the case main-body part 4. FIG. As a result, the side wall Cs of the covers C and C ′ can be prevented from projecting outward in the axial direction from the end surface of the case main body 4, so that the width in the axial direction of the output shaft J of the differential device D is narrow. This is advantageous for achieving the above.

  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.

  Thus, the side gear S of the present embodiment is integrally formed between the inner peripheral shaft portion Sj and the tooth portion Sg of the outer peripheral side gear S that is spaced radially outward from the shaft portion Sj. It has a flat ring plate-shaped intermediate wall part Sw to be connected, and the radial width t1 of the intermediate wall part Sw 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, and the effective diameter d2 of the pinion shaft PS can be reduced. As a result, the width of the pinion P in the axial direction of the output shaft J can be reduced.

  In addition, the load on the pinion shaft PS is reduced in this way, the reaction force applied to the side gear S is reduced, and the back surface of the intermediate wall portion Sw of the side gear S is supported by the cover side wall portion Cs. Even if the portion Sw is made thin, it is easy to ensure the necessary rigidity and strength of the side gear S. That is, the intermediate wall portion Sw of the side gear S can be sufficiently thinned while ensuring the support rigidity for the side gear S. Furthermore, in the present embodiment, since the maximum wall thickness t2 of the intermediate wall portion Sw of the side gear S is formed to be smaller than the effective diameter d2 of the pinion shaft PS that can be reduced in diameter, the intermediate wall portion Sw of the side gear S is Further thinning can be achieved. In addition, since the cover side wall Cs is formed in a plate shape whose outer surface is a flat surface orthogonal to the rotation axis L of the differential case DC, the cover side wall Cs itself can be thinned.

  As a result, the differential device D should be sufficiently narrow in the axial direction of the output shaft J as a whole while ensuring the same strength (for example, static torsional load strength) and the maximum torque transmission amount as the conventional device. Therefore, 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 is downsized. It is advantageous to do it.

  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 when viewed from the side in the axial direction of the output shaft J (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 circumferential direction of the case main body portion 4 and extends in the radial direction of the case main body portion 4 to connect the boss portion Cb and the case main body portion 4 together. In other words, the side wall portion Cs that basically has a disk shape of the cover portion C is formed by forming a plurality of cutout portions 8 that are notched in the side wall portion Cs at intervals in the circumferential direction. The oil retaining portion 7 is formed on one side and the connecting arm portion 9 is formed on the other side with the punched portion 8 interposed in the circumferential direction.

  The structure of the side wall portion Cs of the cover portion C, in particular, the oil holding portion 7 allows the lubricating oil to move outward in the radial direction by centrifugal force due to the rotation of the differential case DC, to the oil holding portion 7 and the case main body. It becomes easy to make it stay in the space covered with the part 4, and it can make it easy to hold | maintain lubricating oil in the peripheral part of the pinion P and the pinion P.

  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 case main body portion 4 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.

  By the way, in the differential case DC, the facing portion of the pinion P and the pinion shaft PS faces a space 60 adjacent to the end surface Pfi on the radially inner side of the side gear S of the pinion P as clearly shown in FIG. The oil reservoir 61 that can capture and store the lubricating oil scattered in the space 60 has an oil reservoir in a fitting portion (that is, the rotational sliding portion rs) between the pinion P and the pinion shaft PS that can rotate and slide relative to each other. 61 is formed in direct communication. In the illustrated example, the oil reservoir 61 is formed by circularly chamfering the inner peripheral surface of the pinion P on the radially inner end of the side gear S.

  Further, the opposing surfaces of the pair of left and right side gears S (in the illustrated example, the inner side surface of the intermediate wall portion Sw of each side gear S near the tooth portion Sg) are transmitted radially along the inner side surface of the intermediate wall portion Sw by centrifugal force. An edge-shaped annular stepped portion E that can be guided and scattered in the space 60 by separating a part of the lubricating oil from the flowing lubricating oil flow is formed, and the top surface of the stepped portion E is in the radial direction of the side gear S Continuing in the same plane as the inner side surface of the intermediate wall portion Sw on the inner side of the stepped portion E.

  By the way, the side gear S can be manufactured by forging and other various forming methods. For example, when the side gear S is forged, the top surface of the step portion E and the outer peripheral surface (step surface) connected to the step portion E. ) May be rounded due to so-called forging sagging. In that case, a sharp edge can be formed between the top surface and the outer peripheral surface (step surface) by machining the outer peripheral surface (step surface).

  In the state where the automobile rotates in the forward direction and the differential case DC is rotated in the forward rotation direction R, the lubricating oil passes through the through oil passage 15 of the side gear S and the diameter of the inner side surface of the intermediate wall portion Sw as will be described later. Since the oil is efficiently supplied near the intermediate portion in the direction, the lubricating oil supplied near the intermediate portion in the radial direction travels radially outward, that is, toward the tooth portion Sg along the inner surface of the intermediate wall portion Sw by centrifugal force. Attempts to reach stepped part E in the middle.

  Thus, the stepped portion E effectively separates a part of the lubricating oil at the edge portion of the stepped portion E from the lubricating oil flow flowing radially outward along the inner surface of the intermediate wall portion Sw by centrifugal force. Then, it can be guided to the space 60 and scattered. As a result, the scattered lubricating oil can be efficiently captured and stored in the oil reservoir 61 facing the space 60, so that the lubricating oil is lubricated to the rotational sliding portion rs between the pinion P and the pinion shaft PS via the oil reservoir 61. Oil is supplied sufficiently. At the same time, the remaining portion of the lubricating oil flow does not scatter from the edge portion of the step portion E but flows along the step surface of the step portion E toward the gear portion Sg of the side gear S, and the gear portion Sg and the pinion P mesh with each other. The part can be sufficiently lubricated. Thereby, even if it becomes a severe driving | running condition where the pinion P rotates at high speed in relation to the diameter reduction of the pinion P etc., lubrication with respect to the said meshing part, and the rotation sliding part between the pinion P and the pinion shaft PS Both lubrication with respect to rs is sufficiently performed.

  Moreover, the edge-shaped stepped portion E of the present embodiment passes through the top surface of the stepped portion E and a virtual plane fe that is orthogonal to the rotation axis L of the differential case DC passes through the internal space 61s or the opening edge 61e of the oil reservoir 61. Formed. Thereby, the lubricating oil separated from the lubricating oil flow at the step E and guided to the space 60 and scattered can be effectively captured by the oil reservoir 61 and can be easily stored in the oil reservoir 61. The lubricating oil can be more efficiently supplied to the rotary sliding portion rs between the pinion P and the pinion shaft PS. Further, in the differential device D of the present embodiment, the side gear S has a sufficiently large diameter with respect to the pinion P in order to reduce the width in the axial direction of the output shaft of the differential case DC as described above. In connection with the increase in the diameter of the side gear S, the lubricating oil flow that flows radially outward along the inner surface of the intermediate wall portion Sw receives a larger centrifugal force. For this reason, since the effect that a part of lubricating oil separates and scatters from the lubricating oil flow at the stepped portion E is increased, the scattered lubricating oil can be more effectively captured by the oil reservoir 61.

  By the way, in this embodiment, both the outer end surfaces PSf of the pinion shaft PS pass through the opening DCo on the outer peripheral surface of the differential case DC (that is, the outer end opening of the through support hole 4a of the case body 4) as described above. Although facing the internal space 1, both ends of the pinion shaft PS have bottomed hollow portions T having one end opened and the other end closed as clearly shown in FIG. It is formed so as to be recessed from PSf. The bottomed hollow part (hollow cylindrical part) T is formed in a bottomed cylindrical hole extending long in the axial direction of the pinion shaft PS, and the depth of the hole is determined by the rotational sliding between the pinion shaft PS and the pinion P. It is set deeply so as to extend further inward after passing through the moving part rs. Therefore, the bottomed hollow portion T has an arrangement configuration in which at least an intermediate portion of the bottomed hollow portion T is concentrically surrounded by the rotary sliding portion rs.

  The peripheral wall of the bottomed hollow portion T in the pinion shaft PS is provided with a plurality of oil guide holes G that can guide the lubricating oil stored in the bottomed hollow portion T to the rotating sliding portion rs by centrifugal force. The oil guide holes G are formed so as to incline to the outer side in the axial direction of the pinion shaft PS from the inner periphery to the outer periphery of the peripheral wall and cross the peripheral wall. The plurality of oil guide holes G are formed so as to be arranged at intervals in the longitudinal direction of the bottomed hollow portion T, and further, the array group of such oil guide holes G. Are arranged radially from the central axis of the plurality of groups, that is, the bottomed hollow portion T, with an interval in the circumferential direction. Moreover, since the opening end Gi of the oil guide hole G to the inner periphery of the peripheral wall of the bottomed hollow portion T is separated from the bottom surface b of the bottomed hollow portion T in the longitudinal direction of the bottomed hollow portion T, the bottomed hollow The hollow portion Ta of the portion T closer to the bottom surface b than the opening end Gi can function as an oil reservoir capable of storing a required amount of lubricating oil.

  According to such a special structure of the bottomed hollow portion T in the pinion shaft PS, when the engine is stopped, the lubricating oil scattered in the mission case M or the transmission of the transmission case M due to the operation of the differential device D before the stop, etc. Lubricating oil that adheres to the ceiling wall Mt and drops from the ceiling wall Mt can be stored and retained in the bottomed hollow portion T that is in an upward posture when stopped. Then, the lubricating oil stored in the bottomed hollow portion T is quickly transferred to the rotational sliding portion rs between the pinion P and the pinion shaft PS by centrifugal force from the oil guide hole G when the differential device D starts to operate. Can be supplied. In this case, since the oil guide hole G is inclined and extended outward in the axial direction of the pinion shaft PS from the inner periphery of the peripheral wall of the bottomed hollow portion T toward the outer periphery, the bottomed hollow portion G is provided when the differential device D is stopped. The lubricating oil stored and held in the portion T can be effectively prevented from flowing out, while the stored lubricating oil is rotated from the oil guide hole G to the rotating sliding portion rs using the centrifugal force when the differential device D starts operating. Can be supplied efficiently.

  Depending on the stop position of the differential device D, the bottomed hollow portion T may be in a horizontal posture and it may be difficult to store the lubricating oil. However, in most cases, any of the plurality of bottomed hollow portions T is present. Becomes an upward vertical posture or an inclined posture, and the lubricating oil scattered in the mission case M and the lubricating oil dropped from the ceiling wall Mt of the mission case M can be stored therein.

  Further, in the present embodiment, the lubricating oil in the transmission case M, for example, the ceiling wall Mt of the transmission case M, is dropped onto the outer peripheral wall of the differential case DC, that is, the case main body 4 through the inside and outside of the case main body 4. A plurality of first and second oil intake holes H1 and H2 capable of taking lubricating oil into the differential case DC are formed in a circular cross section and at intervals in the circumferential direction of the differential case DC. Moreover, as clearly shown in FIG. 2, the first and second oil intake holes H1 and H2 are offset from the intermediate point m between the two pinions P adjacent in the circumferential direction of the differential case DC to the respective pinion P side. Be placed.

  The oil intake holes H1 and H2 are viewed from the projection plane orthogonal to the rotation axis L of the differential case DC, and the axis of the oil intake holes H1 and H2 extends from the inner opening end Hi to the outer opening end of the oil intake holes H1 and H2. It forms so that it may incline in the rotation direction R front side of differential case DC at the time of vehicle advance toward Ho. In addition, each pinion P has a first imaginary line L1 connecting one end in the circumferential direction of the inner opening end Hi of each of the oil intake holes H1 and H2 and the rotation axis L when viewed in the projection plane, and each oil It arrange | positions out of the area | region A pinched | interposed into the 2nd virtual line L2 which connects the circumferential direction other end of the inner opening end Hi of the taking-in holes H1 and H2, and the rotating shaft L.

  In the present embodiment, since the pinion P has a flat differential structure that can sufficiently reduce the diameter of the pinion P with respect to the side gear S as described above, the oil intake holes H1 and H2 are offset from the intermediate point m to the pinion P side in the circumferential direction of the differential case DC. Even if the pinion P is disposed (that is, close to the pinion P), the pinion P can be easily disposed outside the region A corresponding to the inner opening ends Hi of the oil intake holes H1 and H2. In other words, the pinion P is formed with a sufficiently small diameter with respect to the side gear S so that the pinion P can be easily arranged outside the region A even if the oil intake holes H1 and H2 are offset on the pinion P side. Is done.

  According to the special arrangement of the oil intake holes H1 and H2 in the outer peripheral wall of the differential case DC, when the differential case DC is rotating in the normal rotation direction R at a relatively low speed when the vehicle is moving forward, Lubricating oil dripping from the ceiling wall Mt can be efficiently taken into the differential case DC through each of the plurality of first and second oil intake holes H1 and H2 inclined in a specific direction (that is, a direction in which it can be taken into the differential case DC efficiently). It becomes. Moreover, among the oil intake holes H1 and H2, the first oil intake hole H1 that is offset from the intermediate point m to the pinion P side, particularly in the forward direction R of each pinion P, is taken into the differential case DC and dropped. Lubricating oil can be efficiently supplied to the meshing portion between the pinion P and the side gear S near the first oil intake hole H1. On the other hand, the second oil intake hole H2, which is arranged behind the pinion P in the forward rotation direction R and offset from the intermediate point m to the pinion P side, allows the lubricating oil taken and dropped into the differential case DC to be fed into the pinion P. Without being obstructed (that is, without pinion P becoming an obstacle and standing in the path of the lubricating oil), the pinion shaft PS can be supplied to the outer periphery of the differential case DC near the rotation center L, from which the lubricating oil is centrifuged. Since the force travels along the outer peripheral surface of the pinion shaft PS toward the outer end side, that is, the rotational sliding portion rs between the pinion shaft PS and the pinion P, the lubricating oil can be efficiently supplied also to the rotational sliding portion rs. It is. As a result, the lubricating oil dropped from the ceiling wall Mt of the transmission case M is efficiently supplied not only to the meshing part of the pinion P with the side gear S but also to the rotational sliding part rs with the pinion shaft PS. Overall, the lubrication efficiency can be increased. A part of the lubricating oil taken and dropped into the differential case DC from the oil intake holes H1 and H2 also reaches the inner surface of the intermediate wall portion Sw of the side gear S, and travels along the inner surface of the intermediate wall portion Sw. It flows to the radially outward side, that is, the tooth portion Sg side by centrifugal force.

  Incidentally, 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 in the differential case DC as described above. In order to position and hold at an appropriate fixed position in consideration of the lubricating oil path to the path 15, at least one of the opposing surfaces of the inner surface of the side wall Cs and the outer surface of the side gear S (in the illustrated example, the outer surface of the side gear S). ) Is formed with an annular washer holding groove 16, and a washer W is fitted into the washer holding groove 16. 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 inner surface of the side gear S passes through the through oil passage 15 and travels radially outward to the tooth portion Sg side. The amount of lubricating oil heading can be increased.

  4 and 5 together, the inner side surface of the side wall portion Cs of the cover portions C and C ′ is connected to the washer W and the through oil passage 15 from the peripheral edge of the thinned portion 8 when the differential case DC rotates. An oil guide groove 17 that can guide the inflow of the lubricating oil is provided in the recess. 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 center axis L side toward the rearward direction of the differential case DC described later). A first inner side wall 17a extending in an inclined manner, a second inner side wall 17b extending in the tangential direction of the oil retaining portion 7 from the periphery of the thinned portion 8, and a back wall portion connecting the inner ends of both inner side walls 17a, 17b 17c is formed in a generally 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 differential case DC, and the rotation of the differential case DC. Accordingly, the penetrating oil passage 15 is disposed at a position where the opening to the outer surface of the intermediate wall portion Sw can be temporarily overlapped.

  Thus, when the differential case DC is rotated in the normal rotation direction R by the rotational force transmitted from the engine via the reduction gear mechanism RG in order to move the vehicle forward, the periphery of the differential case DC is scattered in the mission case M. The lubricating oil to flow flows into the oil holding portion 7 (ie, the oil guide groove 17) from the peripheral edge of the light-emission portion 8 due to the relative speed difference between the lubricating oil and the rotating cover portions C and C ′. In this case, the lubricating oil that has flowed into the oil guide groove 17 is efficiently collected toward the innermost 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 inner back groove portion 17i to the washer W and the through oil passage 15 side. Then, the lubricating oil that has passed through the through oil passage 15 and reached the inner surface of the intermediate wall portion Sw of the side gear S flows to the radially outer side along the inner surface of the intermediate wall portion Sw by centrifugal force as described above. To do.

  Further, 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 into the inner side of the case body portion 4 at the time of rotation of the differential case DC at the peripheral portion of the thinned portion 8. Have. The inlet of the oil guide groove 17 is open to the oil guide slope f. The oil guide slope f is seen in a cross section (see partial cross-sectional views of FIGS. 4 and 5) across the oil holding portion 7 and the connecting arm portion 9 in the circumferential direction of the differential case DC. It is comprised from the slope which inclined to the circumferential direction center side of each of the oil holding | maintenance part 7 and the connection arm part 9 toward the inner surface from each outer surface of the part 9. FIG. Thus, according to the oil guiding action of the oil guiding slope f, the lubricating oil can smoothly flow from the outside to the inside of the cover portions C and C ′ with the rotation of the differential case DC. Lubricating oil can be efficiently introduced from the inlet opening to the oil guiding slope f.

  Next, the operation of the above-described embodiment will be described. In the differential device D of the present embodiment, when the differential case DC receives rotational force from the engine via the reduction gear mechanism RG, the pinion P does not rotate around the pinion shaft PS and rotates together with the differential case DC and the rotational axis L of the differential case DC. When revolving around, 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 J. Further, when a difference in rotational speed occurs between the left and right output shafts J 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 J through the reduction gear mechanism RG and the differential device D in the forward traveling state of the automobile, the rotation of each movable element of the reduction gear mechanism RG and the differential case DC is accompanied. Lubricating oil splashes vigorously at various locations within the transmission case M, but 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. And is efficiently guided from there to the washer W and the through oil passage 15 side, so that the lubricating effect on the washer W is enhanced, and the intermediate portion of the side gear S passes through the through oil passage 15. A sufficient amount of lubricating oil reaching the inner surface of the wall portion Sw can be secured. Then, the reached lubricating oil flows to the radially outer side along the inner side surface of the intermediate wall portion Sw by centrifugal force as described above, and a part of the lubricating oil flow passes from the edge-shaped step portion E to the space. 60 is scattered and trapped and stored in the oil reservoir 61 to lubricate the rotational sliding portion rs between the pinion shaft PS and the pinion P, but the remaining portion of the lubricating oil flow passes along the step surface of the step E to the side gear. The tooth part Sg of S is reached, and the meshing part of the tooth part Sg and the pinion P is lubricated. As a result, even when the tooth portion Sg of the side gear S is far away from the output shaft J due to an increase in the diameter of the side gear S or in a severe driving situation where the pinion P rotates at a high speed, the meshing portion or the rotational sliding portion rs is moved to. Since the lubricating oil can be supplied efficiently, seizure of the meshing portion and the rotary sliding portion rs can be effectively prevented.

  Further, in the present embodiment, the bottomed hollow portion T that opens to the inner space 1 of the mission case M and functions as an oil reservoir is recessed in the outer end surface PSf of the pinion shaft PS. A bottomed hollow portion in an upward posture of lubricating oil splashed in the mission case M with the operation of the differential unit D or the like, or lubricating oil that adheres to the ceiling wall Mt of the mission case M and drops from the ceiling wall Mt. T can be stored and held in T. Accordingly, the lubricating oil stored in the bottomed hollow portion T is moved between the pinion P and the pinion shaft PS by centrifugal force from the oil guide hole G on the peripheral wall of the bottomed hollow portion T when the differential device D starts to operate. Therefore, the rotary sliding part rs between the pinion P and the pinion shaft PS can be sufficiently lubricated without delay from the beginning of the operation.

  Further, in the present embodiment, a plurality of first and second oil intake holes H1 and H2 are formed on the outer peripheral wall of the differential case DC, and the lubricating oil dropped from the ceiling wall Mt of the transmission case M can be taken into the differential case DC. The formation positions and orientations of the first and second oil intake holes H1 and H2 are as described above. Therefore, when the differential case DC is rotating in the forward rotation direction R at a relatively low speed when the vehicle is moving forward, the lubricating oil dripping from the ceiling wall Mt of the transmission case M is the first and second oil intake holes H1, It can be efficiently taken into the differential case DC through H2. Moreover, the first oil intake hole H1 that is arranged in front of the forward rotation direction R of each pinion P and offset from the intermediate point m of the adjacent pinion P to the pinion P side is the first oil intake hole H1 that receives the lubricating oil taken into the differential case DC in the first It becomes possible to efficiently supply the meshing portion between the pinion P and the side gear S near the oil intake hole H1. On the other hand, the second oil intake hole H2, which is arranged behind the forward rotation direction R of each pinion P and offset from the intermediate point m to the pinion P side, receives the lubricating oil taken into and dropped from the differential case DC. Can be supplied to the outer peripheral portion of the pinion shaft PS near the rotation center L of the differential case DC without being obstructed by the lubricant, from which the lubricating oil flows to the outer end side along the outer peripheral surface of the pinion shaft PS by centrifugal force. The lubricating oil can be efficiently supplied also to the rotational sliding portion rs between the pinion shaft P and the pinion P. As a result, the lubricating oil dropped from the ceiling wall Mt of the transmission case M is efficiently supplied not only to the meshing part with the side gear S of the pinion P but also to the rotational sliding part rs with the pinion shaft PS. As a result, the lubrication efficiency can be further increased.

  In the differential case DC of the present embodiment, a part of the outer peripheral portion of the differential case DC may be immersed under the lubricating oil stored in the inner bottom portion of the transmission case M or may not be immersed. In particular, when immersed under the oil level, the differential case DC is stored in the differential case DC from the first and second oil intake holes H1 and H2 while the differential case DC is rotating in the normal rotation direction R when the vehicle is moving forward. Therefore, the lubrication of each part in the differential case DC can be performed more efficiently.

  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 each component of the differential device D according to the above-described embodiment described with reference to FIGS. The reference numerals are the same as those in the above embodiment, and the structural description is omitted.

First, a basic idea for sufficiently narrowing (that is, flattening) the differential device D in the axial direction of the output shaft J 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%).
About [1] When the side gear S module is MO, 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 TO, the bevel gear From the general formula of
MO = PD ₁ / Z1
PD ₁ = 2PCD · sinθ ₁
θ ₁ = tan ^-1 (Z1 / Z2)
From these equations, the gear module is
MO = 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 MO. 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. 8 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)
Then, the transmitted load F by the torque transmission distance PD _1/2 is F = 2TO / PD _1. Accordingly, if the torque TO 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. 8 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 rate of change in gear strength as the number of teeth ratio Z1 / Z2 increases is the rate of change in gear strength due to the decrease in module MO (the right term in equation (3) above) and the reduction in 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. 8 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. 9, and it can be seen that as the pitch cone distance PCD increases, the gear strength increases as the module 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)
The equation (8) is indicated by L5 in FIG. 9, 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 increase rate of the gear strength due to the increase in the module MO (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 equation (9) is indicated by L6 in FIG. 9, and it can be seen that the gear strength is significantly 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. 10 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. 10 indicates the shaft diameter of the pinion shaft PS that supports the pinion P (that is, the pinion support portion) d2. 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 equality of the equation (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. 8, 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.

  In the case where 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. 11 (more specifically, as shown by the L9 line in FIG. 11). In this case, the region corresponding to the expression (13) is a region above the L9 line and below the L9 line in FIG. A specific region (hatching region in FIG. 11) that satisfies the expression (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 the example when the tooth number ratio Z1 / Z2 is set to 40/10 and d2 / PCD is set to 20.00% in FIG. 11 is illustrated in FIG. An example when the tooth number ratio Z1 / Z2 is set to 58/10 and d2 / PCD is set to 16.67% is shown in FIG. 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 6), the specific area The flat differential device in (1) can also achieve the effects associated with the structure shown in the above-described embodiment.

  The above description (especially with respect to FIGS. 8, 10, and 11) is performed with respect to the differential device 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, an example in which the tooth number ratio Z1 / Z2 is set to 48/12 and d2 / PCD is set to 20.00% is shown in FIG. FIG. 13 illustrates an example when the ratio of the teeth 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. Also, 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 set to 10 in FIG. 11, the tooth number ratio Z1 / Z2 is set to 40/10 and d2 / PCD is set to 34.29%. In the case where the number of teeth Z2 of the pinion P is set to 12 in FIG. 11, 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 of FIG. 13 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 a circle 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 reduction gear mechanism RG composed of the planetary gear mechanism is disposed adjacent to one side of the differential case DC and the output side element (carrier 53) is coupled to the differential case DC (cover portion C ′). In this embodiment, the power from the power source is transmitted to the differential case DC via the reduction gear mechanism RG. However, the output side element of the reduction gear mechanism other than the planetary gear mechanism may be coupled to the differential case DC. Good.

  Further, instead of such a reduction gear mechanism, an input tooth portion (final driven gear) that receives power from a power source is formed integrally with the outer peripheral portion of the differential case DC or fixed later, and power is supplied via the input tooth portion. The power from the source may be transmitted to the differential case DC. In this case, a specific part of the outer peripheral surface of the differential case DC, for example, the opening of the hollow cylindrical portion T and the openings of the first and second oil intake holes H1 and H2 are not covered with the input tooth portion, and the inside of the mission case M The space 1 is always exposed.

  In the above-described embodiment, the oil guide groove 17 is formed from the lightening portion 8 formed in the side wall portion Cs of the cover portions C and C ′ as an oil introduction path through which the lubricating oil is guided to the inner surface of the intermediate wall portion Sw of the side gear S. However, instead of or in addition to such an oil path, other oil introduction paths can be implemented. As another oil introduction path, for example, the boss part Cb of the cover part C, C ′ of the differential case DC is extended outward in the axial direction from the shaft part Sj of the side gear S, and the inner periphery of the extension part of the boss part Cb is used. If the output shaft J is rotatably fitted to the surface and a spiral groove is formed in at least one of the fitting surfaces (for example, the inner peripheral surface of the extension of the boss Cb), the periphery of the extension of the boss Cb The lubricating oil existing in the internal space 1 of the transmission case M is passed through the spiral groove when the boss portion Cb and the output shaft J are rotated relative to each other, and the spline fitting portion 6 between the shaft portion Sj of the side gear S and the output shaft J, In other words, it can be efficiently supplied to the inner side surface of the intermediate wall portion Sw. In this case, if a part of the spline teeth of the spline fitting portion 6 is omitted to form an axial lubricating oil path, the lubricating oil is further applied to the inner surface of the intermediate wall portion Sw of the side gear S. It can be supplied efficiently. In addition, in place of or in addition to the spiral groove, the lubricating oil is pumped and supplied from the oil pump to the spline fitting portion 6 between the shaft portion Sj of the side gear S and the output shaft J. You may make it supply lubricating oil to the inner surface of the intermediate wall part Sw of the side gear S through the spline fitting part 6. FIG.

  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 (for example, the carrier 53 of the reduction gear mechanism RG) located on the upstream side of the power transmission path is disposed on the side where the cover portion is not provided so that the drive member and the differential case DC are coupled. It may be.

  In the above-described embodiment, the differential device D allows a difference in rotational speed between the left and right axles. However, the differential device according to the present invention is also applied to a center differential that absorbs the rotational speed difference between the front wheels and the rear wheels. Can be implemented.

A ... A region between first and second imaginary lines D ... Differential device DC ... Differential case d2 ... Pinion shaft diameter, support shaft diameter (pinion Support part diameter, differential gear support part diameter)
H1, H2, .. First and second oil intake holes (oil intake holes)
Hi: Inner opening end of oil intake hole Ho: Outer opening end of oil intake hole J: Output shaft L: Rotation axis of differential case (rotation center of differential case)
L1, L2, ··· First and second imaginary lines M ··· Mission case Mt ··· Ceiling wall m of mission case · · · Midpoint between two pinions adjacent in the circumferential direction of the differential case P: Pinion (differential gear)
PCD ・ ・ ・ Pitch cone distance PS ・ ・ ・ ・ Pinion shaft (Pinion support, differential gear support)
PS '... support shaft (pinion support, differential gear support)
R: Differential case rotation direction when the vehicle moves forward S: Side gear (output gear)
Sg ... tooth part Sj ... shaft part Sw ... intermediate wall part 4 ... case body (outer peripheral wall of differential case)

Claims (6)

A vehicle differential device that distributes and transmits rotational force transmitted from a vehicle-mounted power source to a differential case (DC) housed in a mission case (M), to a pair of output shafts (J),
A pinion (P) disposed in the differential case (DC) and a rotation axis (L) of the differential case (DC) are disposed, supported by the differential case (DC) and the pinion (P). A pinion shaft (PS) rotatably penetrating and supported, and a pair of side gears (S) that mesh with the pinion (P) in the differential case (DC) and are respectively connected to the pair of output shafts (J). Prepared,
The differential case (DC) has a plurality of oil intake holes through which the lubricating oil in the transmission case (M) can be taken into the differential case (DC) through the inside and outside of the outer peripheral wall (4) of the differential case (DC). (H1, H2) at positions offset from the intermediate point (m) of two pinions (P) adjacent in the circumferential direction of the differential case (DC) to the pinion (P) side,
Each of the oil intake holes (H1, H2) is viewed from a projection plane orthogonal to the rotation axis (L), and the axis of the oil intake holes (H1, H2) is the axis of the oil intake holes (H1, H2). It is formed so as to incline forward in the rotational direction (R) of the differential case (DC) when the vehicle advances from the inner opening end (Hi) toward the outer opening end (Ho).
The pinion (P) is a first imaginary line that connects one end in the circumferential direction of the inner opening end (Hi) of each of the oil intake holes (H1, H2) and the rotation axis (L) when viewed from the projection plane. Sandwiched between the line (L1) and a second imaginary line (L2) connecting the other end in the circumferential direction of the inner opening end (Hi) of each of the oil intake holes (H1, H2) and the rotation axis (L). The vehicle differential device is disposed outside the region (A).   The side gear (S) includes a shaft portion (Sj) connected to the pair of output shafts (J), the gear portion (Sg) spaced radially outward from the shaft portion (Sj), The vehicle differential device according to claim 1, further comprising a flat intermediate wall portion (Sw) extending radially outward from an inner end portion of the shaft portion (Sj). A vehicle differential device that distributes and transmits rotational force transmitted from a vehicle-mounted power source to a differential case (DC) housed in a mission case (M), to a pair of output shafts (J),
A differential gear (P) disposed in the differential case (DC) and a differential gear (P) disposed so as to pass through a rotation axis (L) of the differential case (DC) and supported by the differential case (DC) A differential gear support (PS) that rotatably supports (P), and meshes with the differential gear (P) in the differential case (DC) and is connected to the pair of output shafts (J). A pair of output gears (S),
The differential case (DC) has a plurality of oil intake holes through which the lubricating oil in the transmission case (M) can be taken into the differential case (DC) through the inside and outside of the outer peripheral wall (4) of the differential case (DC). (H1, H2) at positions offset from the intermediate point (m) of the two differential gears (P) adjacent in the circumferential direction of the differential case (DC) toward the differential gear (P). And
Each of the oil intake holes (H1, H2) is viewed from a projection plane orthogonal to the rotation axis (L), and the axis of the oil intake holes (H1, H2) is the axis of the oil intake holes (H1, H2). It is formed so as to incline forward in the rotational direction (R) of the differential case (DC) when the vehicle advances from the inner opening end (Hi) toward the outer opening end (Ho).
The differential gear (P) is connected to the circumferential end of the inner opening end (Hi) of each of the oil intake holes (H1, H2) and the rotation axis (L) when viewed from the projection plane. A first imaginary line (L1) and a second imaginary line (L2) connecting the other circumferential end of the inner opening end (Hi) of each of the oil intake holes (H1, H2) and the rotation axis (L). Arranged outside the area (A) sandwiched between
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,
And a vehicle differential device satisfying Z1 / Z2> 2.   The vehicle differential device according to claim 3, wherein Z1 / Z2 ≧ 4 is satisfied.   The vehicle differential device according to claim 3, wherein Z1 / Z2 ≧ 5.8 is satisfied.   The oil intake hole (H1, H2) has a circular cross-sectional shape orthogonal to the axis of the oil intake hole (H1, H2), according to any one of claims 1 to 5. The differential for vehicles as described.

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