JP2016031081A - Differential gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a differential gear which can increase the strength of each tooth by setting the module of each tooth large without causing tooth profile interference, and is compact.SOLUTION: A differential gear comprises: an eccentric shaft 18 which is arranged to be relatively rotatable to an input member 7, is situated on an eccentric axis X2 eccentric from a center axis X1 and is integrally connected to a first output shaft 11; a first differential member 16 which is adjacent to the input member 7 and can revolve around the center axis X1 while rotating on the eccentric shaft 18; and a second differential member 17 integrally connected to a second output shaft 12 adjacently to the first differential member 16. The input member 7 is formed with first cycloid internal teeth 21, and first cycloid outer teeth 22 for meshing with the first cycloid internal teeth 21 are formed on one side part of the first differential member 16. Second cycloid internal teeth 24 are formed on the other side part of the first differential member 16, and second cycloid outer teeth 25 for meshing with the second cycloid internal teeth 24 are formed on the second differential member 17.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), if the gear module is made larger in order to increase the gear strength of each gear, the differential device is increased in size and tooth profile interference. A problem occurs.

JP 2012-67889 A

  The present invention has been made in view of such circumstances, and can provide a compact differential device that can increase the strength of each tooth by setting a large module for each tooth profile without causing tooth profile interference. For the purpose.

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 central axis so as to be rotatable relative to the input member on the central axis, and positioned on an eccentric axis eccentric from the central axis so as to revolve around the central axis. An eccentric shaft integrally connected to the first output shaft, a first differential member disposed 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 integrally connected to the second output shaft so as to be rotatable on the central axis adjacent to one side of the first differential member, Forms the first cycloid internal teeth and bites the first cycloid internal teeth A first cycloid external tooth is formed on one side of the first differential member, a second cycloid internal tooth is formed on the other side of the first differential member, and meshed with the second cycloid internal tooth Second cycloid external teeth are formed on the second differential member, the number of teeth of the first cycloid internal teeth is Z1, the number of teeth of the first cycloidal external teeth is Z2, and the number of teeth of the second cycloidal internal teeth Is Z3, and the number of teeth of the second cycloid external teeth is Z4,
(Z1 / Z2) × (Z3 / Z4) = 2
The first characteristic is to establish the above equation.

  In addition to the first feature of the present invention, the (Z1 / Z2) is 4/3 and the (Z3 / Z4) is 3/2, or the (Z1 / Z2) is 3/2. In addition, the second feature is that (Z3 / Z4) is set to 4/3.

  In the present invention, the input member is rotatably supported on a transmission case, and a cover that is rotatably supported on the transmission case and covers the first and second differential members is coupled to the input member. The third feature is to constitute

  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 rotation speed of the shaft becomes equal to the rotation speed of the input member, and the rotation of the input member can be distributed to the first and second output shafts. The entire apparatus can be configured compactly in the axial direction, and in particular, the axial dimension can be shortened effectively. In addition, by adopting the first cycloid internal teeth, the first cycloid external teeth, the second cycloid internal teeth, and the second cycloid external teeth, while preventing tooth profile interference, each tooth profile module is set large to increase the strength of each tooth. A differential device for high load can be provided.

  According to the second aspect of the invention, (Z1 / Z2) = 4/3, (Z3 / Z4) = 3/2, or (Z1 / Z2) = 3/2, (Z3 / Z4) = 4. By setting / 3, the module of each tooth profile can be maximized and the strength of each tooth can be effectively increased.

  According to the third feature of the present invention, the input member also serves as one side wall of the differential case, so that the structure of the differential case can be simplified and the weight thereof can be reduced.

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 arrow 2-2 in FIG. 1. FIG. 3 is a cross-sectional view taken along arrow 3-3 in FIG. 1.

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

  First, 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 together with the ring gear 3 by a bolt 9. The cover 8 is configured by the second bearing 5. It is supported by the mission case 1 via.

  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.

  A first differential member 16 adjacent to one side of the input member 7 and a second differential member 17 adjacent to one side of the first differential member 16 are accommodated in the cover 8.

  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. As described above, the first differential member 16 can revolve around the central axis X <b> 1 while rotating around the eccentric shaft 18.

  As shown in FIGS. 1 to 3, a first cycloid internal tooth 21 is formed on one side of the input member 7, and meshes with the first cycloid internal tooth 21 and has a smaller number of teeth than the number of teeth. A first cycloid external tooth 22 is formed on one side of the first differential member 16, and a second cycloid internal tooth 24 is formed on the other side of the first differential member 16. Second cycloid outer teeth 25 smaller than the number of teeth that mesh with the second cycloid inner teeth 24 are formed on the second differential member 17. Therefore, the first cycloid inner teeth 21 and the second cycloid outer teeth 25 have the center axis X1 as the center, and the first cycloid outer teeth 22 and the second cycloid inner teeth 24 have the eccentric axis X2. .

  Thus, the number of teeth of the first cycloid internal teeth 21 is Z1, the number of teeth of the first cycloid external teeth 22 is Z2, the number of teeth of the second cycloid internal teeth 24 is Z3, and the number of teeth of the second cycloid external teeth 25 is When Z4 is set, the inner teeth 21 and 24 and the outer teeth 22 and 25 are formed so that the following formula is established.

(Z1 / Z2) × (Z3 / Z4) = 2
Desirably, the amount of eccentricity of the eccentric axis X2 with respect to the central axis X1 is set to e as described above, and the reference of the first cycloid internal tooth 21, the first cycloid external tooth 22, the second cycloid internal tooth 24, and the second cycloid external tooth 25 is used. When the pitch circle radii are R1, P1, R2 and P2, respectively, e: R1: P1: R2: P2 = 1: 4: 3: 3: 2 and Z1 = 4 as in the illustrated example. Z2 = 3, Z3 = 3, Z4 = 2, or e: R1: P1: R2: P2 = 1: 3: 2: 4: 3 and Z1 = 3, Z2 = 2, Z3 = 4 , Z4 = 3.

  In FIG. 1, reference numeral 27 denotes an oil seal.

  Next, the operation of this embodiment will be described.

  Now, by fixing the left driving axle S1, in the state where the first output shaft 11 and the eccentric shaft 18 are fixed, the ring gear 3 is driven from the driving gear 2 to rotate the input member 7 around the central axis X1. When the first cycloid internal teeth 21 drive the first cycloid external teeth 22, the first differential member 16 rotates around the stationary eccentric shaft 18, and the second cycloidal internal teeth 24 become the second cycloidal external teeth. By driving 25, the second differential member 17, and thus the second output shaft 12, rotates.

  In the illustrated example, (Z1 / Z2) = 4/3 and (Z3 / Z4) = 3/2, so that the input member 7 drives the first differential member 16 with a speed increasing ratio of 4/3, The first differential member 16 drives the second differential member 17, that is, the second output shaft 12 with a speed increasing ratio of 3/2. As a result, the input member 7 is (4/3) × ( The second output shaft 12 is driven with a speed increasing ratio of 3/2) = 2.

  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 first cycloid internal teeth 21 are outside the first cycloid. The first differential member 16 rotates around the eccentric shaft 18 due to the driving with respect to the teeth 22 and the driving reaction force of the second cycloidal outer teeth 25 with respect to the second cycloidal inner teeth 24, and the second differential that does not move. Revolving around the member 17, 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 11 and 12, and therefore the rotation of the ring gear 3 can be distributed to the left and right drive axles S1 and S2.

  By the way, as described above, the differential device D is adjacent to the input member 7, the first differential member 16 adjacent to one side of the input member 7, and one side of the first differential member 16. Since the second differential member 17 is provided, the overall configuration can be made more compact than a conventional general bevel gear type differential device, and in particular, the axial dimension can be effectively shortened. .

  Further, by adopting the first cycloid inner teeth 21, the first cycloid outer teeth 22, the second cycloid inner teeth 24, and the second cycloid outer teeth 25, each tooth profile module is set to be large while easily preventing tooth profile interference. The tooth | gear intensity | strength can be raised and the differential gear D for high loads can be provided.

  In particular, as described above, (Z1 / Z2) = 4/3, (Z3 / Z4) = 3/2, or (Z1 / Z2) = 3/2, (Z3 / Z4) = 4/3 By maximizing the module of each tooth profile, the strength of each tooth can be effectively increased.

  The differential case 6 has an input member 7 supported by the transmission case 1 via the first bearing 4 and is rotatably supported by the transmission case 1 and coupled to the input member 7 so that the first and second differential members 6 are supported. Since it is comprised with the cover 8 which covers the members 16 and 17, the input member 7 will also serve as one side wall of the differential case 6, and the structure of the differential case 6 can be simplified and the weight can be reduced.

  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, the differential device D can be applied to front and rear wheel transmission systems in front and rear wheel drive vehicles.

DESCRIPTION OF SYMBOLS 1 ... Mission case 6 ... Differential case 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 cycloid internal tooth 22 ... First cycloid external tooth 24 ... Second cycloid internal tooth 25 ... Second cycloid External teeth X1 ... Center axis X2 ... Eccentric axis

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 the input member (7) rotatably disposed on the central axis (X1), and the central axis (X1) An eccentric shaft (18) integrally connected to the first output shaft (11) so as to revolve around the central axis (X1), which is positioned on the eccentric axis (X2) deviated from A first differential member (16) disposed adjacent to one side of the input member (7) and capable of revolving around the central axis (X1) while rotating on the eccentric shaft (18); A second differential member (17) integrally connected to the second output shaft (12) so as to be rotatable on the central axis (X1) adjacent to one side of the differential member (16); With
A first cycloid internal tooth (21) is formed on the input member (7), and a first cycloid external tooth (22) meshing with the first cycloid internal tooth (21) is provided as the first differential member (16). A second cycloid internal tooth (24) formed on one side of the first differential member (16) and meshed with the second cycloid internal tooth (24). Forming external teeth (25) on the second differential member (17);
The number of teeth of the first cycloid internal tooth (21) is Z1, the number of teeth of the first cycloid external tooth (22) is Z2, the number of teeth of the second cycloid internal tooth (24) is Z3, and the second cycloid external When the number of teeth of the tooth (25) is Z4,
(Z1 / Z2) × (Z3 / Z4) = 2
A differential device characterized by satisfying the above equation. The differential device according to claim 1,
The (Z1 / Z2) is 4/3 and the (Z3 / Z4) is 3/2, or the (Z1 / Z2) is 3/2 and the (Z3 / Z4) is 4/3. A differential device characterized by that. The differential device according to claim 1,
The input member (7) is rotatably supported by the transmission case (1), and the input member (7) is rotatably supported by the transmission case (1) and the first and second differential members ( 16. A differential device characterized in that a differential case (6) is formed by coupling a cover (8) covering 16 and 17).

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