JP2017190782A - Differential apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact differential apparatus capable of dispersing torque to the whole of each transmission member.SOLUTION: A differential apparatus includes an eccentric shaft 18 rotatable relatively to an input member 7 and connected to a first output shaft 11 in a state of being eccentric from a center axis X1, a first differential member 16 adjacent to the input member 7, and capable of revolving around the center axis X1 while rotating on the eccentric shaft 18, and a second differential member 17 adjacent to the first differential member 16 and connected to a second output shaft 12. A first hypocycloid groove 21 is formed on the input member 7, a first epicycloid groove 22 overlapped to the first hypocycloid groove 21 is formed on the first differential member 16, a first transmission rolling element 23 is disposed on an overlapping portion of the first hypocycloid groove 21 and the first epicycloid groove 22, further a second hypocycloid groove 24 is formed on the first differential member 16, a second epicycloid groove 25 overlapped to the second hypocycloid groove 24 is formed on the second differential member 17, and a second transmission rolling element 26 is disposed on an overlapping portion of the second hypocycloid groove 24 and the second epicycloid groove 25.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an improvement of a differential device that distributes rotation of an input member to a first output shaft and a second output shaft that are arranged so as to be relatively rotatable on a central axis.

  In a conventional differential device using a bevel gear (see Patent Document 1 below), a plurality of bevel gears mesh with each other with some teeth, and only some of these teeth bear the torque. In addition, since it is necessary to arrange a plurality of bevel gears in a cross shape, the axial dimension of the output shaft is particularly long, making it difficult to make the device compact.

JP 2012-67889 A

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a compact differential device that can disperse torque over the entire transmission members.

In order to achieve the above object, the present invention is capable of rotating on a central axis in a differential device that distributes rotation of an input member to a first output shaft and a second output shaft arranged in a relatively rotatable manner on the central axis. The input member disposed on the first output shaft; and an eccentric shaft integrally connected to the first output shaft so as to revolve around the central axis while being positioned on an eccentric axis that is eccentric from the central axis; A first differential member having a smaller diameter than the input member, the first differential member being arranged adjacent to one side of the input member and capable of revolving around the central axis while rotating on the eccentric shaft; A second differential member having a smaller diameter than the first differential member integrally connected to the second output shaft so as to be rotatable on the central axis adjacent to one side; A cover coupled to cover the first and second differential members, the input Forming a first hypo-groove extending in a circumferential direction along a hypocycloid curve on the side surface of the material facing the first differential member, while the side surface of the first differential member facing the input member In addition, a first epi groove extending in the circumferential direction along the epicycloid curve and overlapping with the first hypo groove is formed at a plurality of locations, and the first hypo groove and the first epi groove are overlapped with each other. While interposing one transmission rolling body and forming a second hypo-groove extending in a circumferential direction along a hypocycloid curve on a side surface of the first differential member facing the second differential member, A second epi-groove extending in a circumferential direction along an epicycloid curve and overlapping the second hypo-groove at a plurality of locations is formed on a side surface of the second differential member facing the first differential member. These second hypo-grooves and second epi-grooves A second transmission rolling element is interposed in the overlapping portion, the wave number of the first hypo groove is Z1, the wave number of the first epi groove is Z2, the wave number of the second hypo groove is Z3, and the second epi groove is Z3. When the wave number of the groove is Z4,
(Z1 / Z2) × (Z3 / Z4) = 2
The above formula is established, and the first feature is that a ring gear coupled to the cover is disposed on the outer periphery of the second differential member. The first and second transmission rolling elements correspond to first and second transmission balls 23 and 26 in the embodiment of the present invention to be described later.

  In addition to the first feature, the present invention has a second feature that at least a part of the ring gear overlaps the input member and the first differential member on a projection plane projected along the central axis. And

  Furthermore, in addition to the first feature, the present invention forms an annular recess disposed in a step between the outer peripheral surfaces of the first differential member and the second differential member in the cover. A third feature is that at least a part of the ring gear is arranged and the ring gear is fixed to the cover.

  According to the first feature of the present invention, the amount of rotation and the amount of revolution of the first differential member change steplessly in response to changes in the loads of the first and second output shafts, and the first and second outputs. The average value of the rotational speed of the shaft becomes equal to the rotational speed of the input member, and the rotation of the input shaft can be distributed to the first and second output shafts. In addition, the relatively flat input member, first differential member, and second differential member are arranged adjacent to each other in the axial direction of the output shaft, so that the differential device as a whole is more compact than a conventional bevel gear type. In particular, the axial dimension can be shortened effectively. The rotational torque of the input member is applied to the first differential member via the first hypo groove, the plurality of first transmission rolling elements and the first epi groove, and the rotational torque of the first differential member is set to the second hypo groove. Since it is transmitted to the second differential member through the groove, the plurality of second transmission rolling elements and the second epi-groove, respectively, the input member and the first differential member, the first differential member and the second differential Between each of the members, torque transmission is performed in a distributed manner at a plurality of locations where the first and second transmission rolling bodies exist, and the input member, the first and second differential members, and the first and second transmissions. The strength and weight of a transmission member such as a rolling element can be increased, and a differential device for high load can be provided. Further, the ring gear is disposed on the outer periphery of the second differential member having a smaller diameter than the input member and the first differential member, and is coupled to the cover of the differential case, so that the dead space on the outer periphery of the second differential member can be reduced. It can be used for arrangement, and a differential gear with a ring gear can be made compact.

  According to the second feature of the present invention, at least a part of the ring gear overlaps with the input member and the first differential member on the projection surface projected along the central axis, so that the input member and the first differential member The side dead space can be used for the arrangement of the ring gear, and the differential gear with the ring gear can be made compact.

  According to the third feature of the present invention, the cover is formed with an annular recess disposed in a step between the outer peripheral surfaces of the first differential member and the second differential member, and at least one of the ring gears is formed in the annular recess. Since the ring gear is fixed to the cover by arranging the portion, the ring gear can be arranged on the outer periphery of the second differential member without being interfered by the cover.

1 is a longitudinal front view of a differential according to a first embodiment of the present invention. FIG. 2 is a sectional view taken along line 2-2 in FIG. 1. FIG. 3 is a sectional view taken along line 3-3 in FIG. 1. The longitudinal section front view of the differential which concerns on 2nd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  First, the description starts with the description of the first embodiment of the present invention shown in FIGS. In FIG. 1, a differential device D is housed in a transmission case 1 of an automobile together with a transmission. This differential device distributes the rotation of the output member of the transmission, that is, the ring gear 3 driven from the drive gear 2, to the left and right drive axles S1, S2 arranged on the central axis X1 so as to be relatively rotatable.

  As shown in FIGS. 1 and 2, the differential device D includes a differential case 6 that is rotatably supported by the transmission case 1 via first and second bearings 4 and 5 on a central axis X1. The differential case 6 includes an input member 7 supported via a first bearing 4 and a cover 8 fixed to the input member 7 with a first bolt 9. Via the transmission case 1.

  A first output shaft 11 of the differential device D is rotatably supported by the input member 7 via a third bearing 13 on the center axis X1, and a left driving axle S1 is supported on the first output shaft 11. Spline combined. Further, the cover 8 supports a second output shaft 12 of the differential device D so as to be rotatable via a fourth bearing 14 on the center axis X1, and a right drive axle S2 is supported on the second output shaft 12. Spline combined.

  In the cover 8, a first differential member 16 that is adjacent to one side of the input member 7 and has a smaller diameter than the input member 7, and a first differential member that is adjacent to one side of the first differential member 16. The second differential member 17 having a diameter smaller than 16 is accommodated.

  An eccentric shaft 18 is integrally connected to the first output shaft 11, and the eccentric shaft 18 revolves around the central axis X1 that is positioned on the eccentric axis X2 that is eccentric by a predetermined distance e from the central axis X1. To get. The first differential member 16 is supported on the eccentric shaft 18 via a fifth bearing 19 so as to be relatively rotatable. The first output shaft 11 and the second differential member 17 are supported by each other via a sixth bearing 20 located on the central axis X1. Thus, the first differential member 16 can revolve around the central axis X1 while rotating around the eccentric shaft 18.

  As shown in FIGS. 1 to 3, an endless first hypo-groove 21 extending in the circumferential direction along the hypocycloid curve is formed on the side of the input member 7 facing the first differential member 16. On the other hand, one side surface of the first differential member 16 facing the input member 7 extends in the circumferential direction along the epicycloid curve and overlaps with the first hypo-groove 21 at a plurality of locations, which is less than the wave number. An endless first epi-groove 22 having a wave number is formed, and a plurality of first transmission balls 23 are interposed in the overlapping portion of the first hypo-groove 21 and the first epi-groove 22.

  An endless second hypo-groove 24 extending in the circumferential direction along the hypocycloid curve is formed on the other side of the first differential member 16, while the second differential member 17 has a first differential On the side surface facing the member 16, an endless second epi-groove 25 having a wave number smaller than the wave number is formed extending in the circumferential direction along the epicycloid curve and overlapping the second hypo-groove 24 at a plurality of locations. A plurality of second transmission balls 26 are interposed in the overlapping portion of the second hypo-grooves 24 and the second epi-grooves 25.

  Thus, the first hypo-groove 21 and the second epi-groove 25 are centered on the central axis X1, and the first epi-groove 22 and the second hypo-groove 24 are centered on the eccentric axis X2. become.

  In the above, when the wave number of the first hypo groove 21 is Z1, the wave number of the first epi groove 22 is Z2, the wave number of the second hypo groove 24 is Z3, and the wave number of the second epi groove 25 is Z4, The hypo-grooves 21 and 24 and the epi-grooves 22 and 25 are formed so that the following formula is established.

(Z1 / Z2) × (Z3 / Z4) = 2
Preferably, the eccentric amount of the eccentric axis X2 with respect to the central axis X1 is e as described above, and the reference of the first hypo-groove 21, the first epi-groove 22, the second hypo-groove 24, and the second epi-groove 25 is preferable. When the pitch circle radii are R1, P1, R2, and P2, respectively, e: R1: P1: R2: P2 = 1: 4: 3: 3: 2 and Z1 = 8, Z2 as illustrated. = 6, Z3 = 6, Z4 = 4, or e: R1: P1: R2: P2 = 1: 3: 2: 4: 3, and Z1 = 6, Z2 = 4, Z3 = 8, It is good to set Z4 = 6.

  In the illustrated example, the eight-wave first hypo-grooves 21 and the six-wave first epi-grooves 22 overlap at seven locations, and seven first transmission balls 23 are interposed in the seven overlapping portions. The six-wave second hypo-grooves 24 and the four-wave second epi-grooves 25 overlap at five locations, and five second transmission balls 26 are interposed at the five overlapping portions.

  Referring again to FIG. 1, the cover 8 is formed with an annular recess 27 disposed at a step portion between the outer peripheral surfaces of the first differential member 16 and the second differential member 17. An annular arm portion 3 a is disposed and the arm portion 3 a is fixed to the cover 8 by the second bolt 10. In the ring gear 3, a rim portion 3b having a tooth portion 3c is integrally formed on the outer periphery of the arm portion 3a. The rim portion 3b is formed so as to protrude from the left and right sides of the arm portion 3a.

  Thus, the ring gear 3 is arranged so that at least a part thereof is located on the outer periphery of the second differential member 17. The ring gear 3 is arranged so that a part thereof overlaps the input member 7 and the second differential member 17 on the projection plane projected along the central axis X1.

  In FIG. 1, reference numeral 29 denotes an oil seal.

  Next, the operation of this embodiment will be described.

  Now, by fixing the left drive axle S1, the ring gear 3 is driven from the drive gear 2 in a state where the first output shaft 11 and the eccentric shaft 18 are fixed, and the input member 7 is connected to the central axis via the cover 8. When rotating around X1, the first hypogrooves of eight waves of the input member 7 drive the first epigrooves of six waves of the first differential member 16 via the first transmission balls 23. The input member 7 drives the first differential member 16 with a speed increasing ratio of 8/6. Then, according to the rotation of the first differential member 16, the six-wave second hypo-groove 24 of the first differential member 16 changes the second-wave second epi-groove 25 of the second differential member 17 to the second. Since it is driven via the transmission ball 26, the first differential member 16 drives the second differential member 17 with a speed increasing ratio of 6/4. Eventually, the input member 7 has the second differential member 17, that is, the second output shaft 12 with a speed increasing ratio of (Z1 / Z2) × (Z3 / Z4) = (8/6) × (6/4) = 2. Will be driven.

  Further, when the input member 7 is rotated in a state where the second output shaft 12 and the second differential member 17 are fixed by fixing the right drive axle S2, the input member 7 with respect to the first differential member 16 is fixed. Due to the driving and the driving reaction force of the first differential member 16 against the stationary second differential member 17, the first differential member 16 rotates around the eccentric shaft 18 and revolves around the central axis X1. Then, the eccentric shaft 18 is driven around the central axis X1. As a result, the input member 7 drives the first output shaft 11 with a double speed increasing ratio.

  Thus, when the loads of the first and second output shafts 11 and 12 are balanced or changed with each other, the amount of rotation and the amount of revolution of the first differential member 16 change steplessly, and both output shafts The average value of the rotational speeds 11 and 12 is equal to the rotational speed of the input member 7. Thus, the rotation of the input member 7 is distributed to the first and second output shafts 12, so that the rotation of the ring gear 3 can be distributed to the left and right drive axles S1, S2.

  At that time, by setting Z1 = 8, Z2 = 6, Z3 = 6, Z4 = 4, or by setting Z1 = 6, Z2 = 4, Z3 = 8, Z4 = 6, the necessary minimum wave number is obtained. It is possible to simplify the eaves structure while ensuring the differential function.

  The differential device D includes an input member 7, a first differential member 16 adjacent to one side of the input member 7, and a second differential member adjacent to one side of the first differential member 16. 17, the overall structure can be made more compact than a conventional bevel gear type differential device, and in particular, the axial dimension can be effectively shortened.

  Moreover, the rotational torque of the input member 7 is applied to the first differential member 16 via the first hypo groove 21, the plurality of first transmission balls 23 and the first epi groove 22, and to the rotation of the first differential member 16. Since the torque is transmitted to the second differential member 17 through the second hypo groove 24, the plurality of second transmission balls 26, and the second epi groove 25, respectively, the input member 7 and the first differential member 16 are transmitted. , Torque transmission between the first differential member 16 and the second differential member 17 is performed in a distributed manner at a plurality of locations where the first and second transmission balls 23 and 26 exist. The first and second differential members 16 and 17 and the first and second transmission balls 23 and 26 can be increased in strength and weight, and a high-load differential device D is provided. be able to.

  The ring gear 3 is disposed on the outer periphery of the second differential member 17 having a smaller diameter than the input member 7 and the first differential member 16 and is coupled to the cover 8 of the differential case 6. The dead space on the outer periphery can be used for the arrangement of the ring gear 3, and the differential device D with the ring gear 3 can be made compact.

  The ring gear 3 is arranged so that a part of the ring gear 3 overlaps the input member 7 and the second differential member 17 on the projection surface projected along the central axis X1. The side dead space of 16 can be used for the arrangement of the ring gear 3, and the differential device D with the ring gear 3 can be made compact.

  The cover 8 is formed with an annular recess 27 disposed at a step portion between the outer peripheral surfaces of the first differential member 16 and the second differential member 17, and the annular arm portion 3 a of the ring gear 3 is formed in the annular recess 27. And the arm 3a is fixed to the cover 8 by the second bolt 10, so that the ring gear 3 can be arranged on the outer periphery of the second differential member 17 without being interfered with the cover 8. It becomes.

  Next, a second embodiment of the present invention shown in FIG. 4 will be described.

  In the second embodiment, the cover 8 is coupled to the outer periphery of the input member 7 by welding 31. The annular arm 3 a of the ring gear 3 is fixed by welding 32 in the annular recess 27 of the cover 8. At that time, the rim portion 3b of the ring gear 3 is formed so as to protrude from the arm portion 3a to one side on the input member 7 side. Since the other configuration is the same as that of the previous embodiment, portions corresponding to those of the previous embodiment are denoted by the same reference numerals in FIG.

  According to the second embodiment, it is possible to dispose the ring gear 3 within the narrow axial width of the differential device D while utilizing the dead space on the outer periphery of the second differential member 17 for disposing the ring gear 3. Thus, the differential device D with the ring gear 3 can be made more compact.

  As mentioned above, although embodiment of this invention was described, this invention can perform various design changes in the range which does not deviate from the summary. For example, transmission rollers can be used in place of the transmission balls 23 and 26. The differential device D can also be applied to front and rear wheel transmission systems in front and rear wheel drive vehicles.

D ... Differential gear X1 ... Center axis X2 ... Eccentric axis 3 ... Ring gear 7 ... Input member 8 ... Cover 11 ... First output shaft 12 ... Second output shaft 16 ... first differential member 17 ... second differential member 18 ... eccentric shaft 21 ... first hypo groove 22 ... first epi groove 23 ...・ First transmission rolling body (first transmission ball)
24 ... 2nd hypo groove 25 ... 2nd epi groove 26 ... 2nd transmission rolling body (2nd transmission ball)
27 ... Annular recess

Claims (3)

In the differential device that distributes the rotation of the input member (7) to the first output shaft (11) and the second output shaft (12) arranged in a relatively rotatable manner on the central axis (X1),
The input member (7) rotatably disposed on the central axis (X1), and an eccentric axis (X2) eccentric from the central axis (X1) and around the central axis (X1) An eccentric shaft (18) that is integrally connected to the first output shaft (11) so as to be able to revolve, and is disposed adjacent to one side of the input member (7), on the eccentric shaft (18). Adjacent to one side of the first differential member (16) and the first differential member (16) having a smaller diameter than the input member (7) and capable of revolving around the central axis (X1) And a second differential member having a smaller diameter than the first differential member (16), which is integrally connected to the second output shaft (12) so as to be able to rotate on the central axis (X1). 17) and a cover that is coupled to the input member (7) and covers the first and second differential members (16, 17). ) And equipped with a,
On the side surface of the input member (7) facing the first differential member (16), a first hypo-groove (21) extending in the circumferential direction along a hypocycloid curve is formed, while the first difference A first epi-groove (16) extending in a circumferential direction along an epicycloid curve and overlapping the first hypo-groove (21) at a plurality of locations on a side surface of the moving member (16) facing the input member (7). 22), and a first transmission rolling element (23) is interposed in the overlapping portion of the first hypo-groove (21) and the first epi-groove (22),
A second hypo-groove (24) extending in the circumferential direction along a hypocycloid curve is formed on the side surface of the first differential member (16) facing the second differential member (17), On the side surface of the second differential member (17) facing the first differential member (16), it extends in the circumferential direction along the epicycloid curve, and at a plurality of locations with the second hypo-groove (24). Overlapping second epi-groove (25) is formed, and a second transmission rolling element (26) is interposed in the overlapping portion of these second hypo-groove (24) and second epi-groove (25),
The wave number of the first hypo groove (21) is Z1, the wave number of the first epi groove (22) is Z2, the wave number of the second hypo groove (24) is Z3, the second epi groove (25 ) Wave number is Z4,
(Z1 / Z2) × (Z3 / Z4) = 2
The above equation is established,
A differential gear, wherein a ring gear (3) coupled to the cover (8) is disposed on an outer periphery of the second differential member (17). The differential device according to claim 1,
The differential characterized in that at least a part of the ring gear (3) overlaps the input member (7) and the first differential member (16) on a projection plane projected along the central axis (X1). apparatus. The differential device according to claim 1,
An annular recess (27) is formed in the cover (8) at a step between the outer peripheral surfaces of the first differential member (16) and the second differential member (17). ), At least a part of the ring gear (3) is disposed, and the ring gear (3) is fixed to the cover (8).

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