JP2007078053A - Differential gear and final reduction gear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a differential gear and a final reduction gear which requires a pinion gear to have no high precision in processing and can be manufactured at low cost. <P>SOLUTION: The differential gear 10 includes: a differential case 26 which gets input for rotation; first and second side gears 30, 32 supported in a rotatable manner around a rotational axis B and engaging with first and second drive shafts 16, 18; first and second shaft halves 41, 42 having an axial center C perpendicular to the rotational axis B of the differential case 26 and rotating together with the differential case 26; and first and second pinion gear sections 44, 46 supported coaxially with the shaft halves and engaging with the first and second side gears 30, 32. The first pinion gear section 44 is secured to the first shaft half 41 so as to constitute a first pinion 50, and the second pinion gear section 46 is secured to the second shaft half 42 so as to constitute a second pinion 52. The first and second pinions 50, 52 are connected to each other relatively rotatably. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a component structure of a differential gear that differentially transmits an input to two output shafts, and more particularly to a differential gear incorporated in a final reduction gear.

  When an input is distributed and transmitted to a plurality of output shafts, a difference in rotational speed may occur between these output shafts. There is a differential device as a device for absorbing this speed difference. For example, when a vehicle such as an automobile makes a turning motion, the left and right wheels have different trajectory lengths, so the left and right drive wheels have a difference in rotational speed while transmitting power from the prime mover. That is, it is necessary to make it differential. For this reason, the vehicle is provided with a differential device capable of transmitting power with a difference in rotational speed. The differential device normally constitutes a final reduction device together with a reduction gear device that decelerates the power rotation input via the propulsion shaft and increases the driving force, and the rotation input from the reduction gear device, It is transmitted differentially to an axle (hereinafter referred to as drive shaft) that drives the left and right drive wheels.

  The differential device has left and right side gears respectively connected to the left and right drive shafts in a differential case driven by the reduction gear device, and a rotation shaft orthogonal to the rotation shaft of the side gear. Holding the meshing pinion gear. In general, two pinion gears are provided, and are rotatably supported by a pinion shaft fixed to the differential case. Therefore, the pinion gear revolves with the rotation of the differential case and can rotate about the pinion shaft. When a difference in rotational speed occurs between the left and right drive wheels, a rotational speed difference also occurs in the side gear, but this rotational speed difference can be absorbed by the rotation of the pinion gear.

  The above-described pinion shaft is rotatably supported by penetrating the shaft hole of the pinion gear. The inner wall of the shaft hole of the pinion gear through which the pinion shaft penetrates has a shape that bulges near the center in the axial direction in order to ensure lubrication with the sliding surface of the pinion shaft that is in sliding contact and to prevent contact with the edge of the shaft hole It has become.

  In manufacturing such a pinion gear, there are many processing steps such as a step of forming a shaft hole by centering the pinion gear and a step of polishing an inner wall of the shaft hole. Furthermore, since extremely high processing accuracy is required for the sliding contact surface of the shaft hole, the conventional pinion gear structure has a problem that the manufacturing cost increases. On the other hand, if the processing accuracy of the slidable contact surface of the completed pinion gear shaft hole is low, there is a possibility that seizure may occur on this surface or cracks may occur from this surface.

  Therefore, the present invention provides a differential gear and a final reduction gear that can be manufactured at a lower cost without requiring high machining accuracy for the pinion gear.

  The differential device of the present invention includes a differential case that rotates upon receiving an input, and is held rotatably in the differential case around the rotation axis of the differential case, and is coaxially connected to the first and second output shafts. The first and second side gears to be combined, the pinion shaft whose axis is perpendicular to the rotation axis of the differential case and rotated together with the differential case, and the first and second side gears supported coaxially by the pinion shaft First and second pinion gears, and the pinion shaft is divided into first and second shaft halves, and the first pinion gear is connected to the first shaft half. A second pinion gear is fixed to the two-shaft half to form first and second pinions, and the first and second pinions are connected so as to be relatively rotatable. According to this structure, it is not necessary to form a pinion gear shaft hole that requires high accuracy.

  Preferably, a first pinion gear is integrally formed on the first shaft half, and a second pinion gear is integrally formed on the second shaft half. Since the pinion gear and the shaft half are integrally formed, the possibility of breakage such as cracks can be reduced from here.

  Preferably, the first shaft half is formed with a substantially cylindrical convex portion protruding from the shaft end surface, and the second shaft half is formed with a substantially cylindrical recess recessed from the shaft end surface. The convex portion is inserted into the concave portion, and the first and second pinions are connected.

  Preferably, the convex portion and the concave portion are connected via a rolling bearing.

  The final reduction gear of the present invention includes a drive pinion connected to a propulsion shaft, a ring gear meshing with the drive pinion, a differential case fixed to the ring gear and rotating, and a rotation shaft of the differential case in the differential case. First and second side gears that are rotatably held as a center and coaxially engage with the first and second drive shafts, and a pinion shaft whose axis is orthogonal to the rotation shaft of the differential case and rotates with the differential case And first and second pinion gears that are coaxially supported by the pinion shaft and mesh with both the first and second side gears, the pinion shaft being divided into first and second shaft halves, The first pinion gear is fixed to the first shaft half, the second pinion gear is fixed to the second shaft half, and the first and second pinions are configured, and the first and second pinions are relatively rotatable. It is connected to.

  According to the present invention, a differential gear and a final reduction gear that can be manufactured at a lower cost can be realized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present embodiment is a final reduction device 1 that decelerates rotation input from a propulsion shaft 12 that transmits power from a prime mover in an automobile or the like and distributes the rotation to left and right drive shafts 16 and 18. The final reduction gear device 1 includes a differential device 10 that distributes power by making the rotational speeds different from each other, that is, differentially with respect to the first and second drive shafts 16 and 18 extending in the left-right direction. However, the present invention is not limited to the final reduction gear 1 of this embodiment, and is applied to a differential device that distributes the input from the input shaft to the first and second output shafts in a differential manner. For example, the present invention can also be applied to a transfer device that distributes and transmits power from a prime mover to the front and rear wheels of a vehicle.

  The final reduction gear 1 in which the differential device 10 of this embodiment is incorporated will be described with reference to FIGS. FIG. 1 shows a cross section of the final reduction gear 1, and FIG. 2 shows a cross section of the differential device 10. FIG. 3 shows a perspective view of the connection portion 54 of the first and second pinions constituting the differential device 10. For ease of understanding, only the main components of the final reduction gear 1 are shown in FIG. 1, the description of the bearings and the housing is omitted, and only the second pinion 52 is shown in FIG. The cross section is shown.

  The final reduction gear 1 is configured to reduce the rotation input from the propulsion shaft 12 to increase the driving force and the rotation input from the reduction gear device 14 between the first and second drive shafts. It is comprised from the differential device 10 which moves and outputs. The differential device 10 may be combined with the reduction gear device 14 to form the final reduction device 1 as in this embodiment, or may be incorporated as a part of a unit other than the final reduction device 1. .

  As shown in FIG. 1, the reduction gear device 14 includes a flange 20 coupled to the propulsion shaft 12 of the vehicle, a drive pinion 22 that engages with the flange 20 and rotates integrally therewith, and a drive pinion. And a ring gear 24 meshing with the ring 22. The reduction gear device 14 has a function of decelerating the rotation input from the propulsion shaft 12, increasing the torque, and transmitting the rotation to the differential device 10 described later.

  The end 12a of the propulsion shaft 12 has a flange shape, and the flange 20 of the reduction gear device 14 is coupled to the end 12a by a bolt (not shown). The flange 20 of the reduction gear device 14 has a shaft receiving portion 20a formed with a spline groove, and the shaft end portion 22a of the drive pinion 22 also formed with a spline groove is engaged with the shaft receiving portion 20a. Connected. In other words, the drive pinion 22 is connected to the propulsion shaft 12 via the flange 20 and rotates integrally with the propulsion shaft 12 around the axis A of the drive pinion indicated by a one-dot chain line A in FIG. By being connected in this way, the power from the propulsion shaft 12 is transmitted to the drive pinion 22. The drive pinion 22 is integrally provided with a gear portion 22c, which is a bevel gear or a hypoid gear, together with a shaft end portion 22a.

  A ring gear 24 having a larger number of teeth meshes with the gear portion 22c of the drive pinion 22 at right angles. The rotation about the axis A of the drive pinion 22 is transmitted to the ring gear 24 while changing its direction via the gear portion 22c. As a result, the ring gear 24 rotates around the ring gear axis B indicated by a one-dot chain line B in FIG. Since the rotation of the ring gear 24 is decelerated compared to the rotation of the drive pinion 22, the torque transmitted from the drive pinion 22 to the ring gear 24 increases.

  A case 26 (hereinafter referred to as a differential case 26) that accommodates the components of the above-described differential device 10 is fixed to the ring gear 24 with bolts 28. The ring gear 24 and the differential case 26 rotate integrally around the axis of the ring gear 24, that is, the rotation axis B of the differential case 26. That is, when the drive pinion 22 rotates about the axis A by the input from the propulsion shaft 12, the differential case 26, that is, the entire differential device 10 rotates in response to this input.

  On the other hand, as shown in FIG. 2, the differential device 10 includes first and second side gears 30 and 32 that are coaxially engaged with the first and second drive shafts 16 and 18 in the differential case 26. The first and second pinions 50 and 52 having the pinion gear portions 44 and 46 meshing with both the first and second side gears 30 and 32 are accommodated. The first and second pinions 50 and 52 respectively have the above-described pinion gear portions 44 and 46 and shaft half bodies 41 and 42 obtained by dividing the pinion shaft serving as the rotation axis of the pinion gear portions 44 and 46 into two parts. Yes. The differential case 26 is filled with lubricating oil (not shown) so that these components can slide and rotate smoothly.

  The first and second side gears 30 and 32 are held in the differential case 26 so as to be rotatable about the rotation axis B of the differential case 26. A side gear washer 36 is provided between the differential case 26 and the first and second side gears 30 and 32, and the differential case 26 and the first and second side gears 30 and 32 are in direct sliding contact. This prevents the side gear from rotating about the rotation axis B of the side gear. The first and second drive shafts 16 and 18 are coaxially engaged with the shaft holes 30a and 32a of the first and second side gears 30 and 32 by a spline structure or the like, respectively. As a result, the first side gear 30 can rotate integrally with the first drive shaft 16, and the second side gear 32 can rotate together with the second drive shaft 18. The first and second side gears 30 and 32 are configured as bevel gears and mesh with the pinion gear portions 44 and 46 of the first and second pinions 50 and 52 at right angles.

  The first and second pinions 50 and 52 are provided between the first side gear 30 and the second side gear 32, and are centered on the axis C of the pinion that is orthogonal to the rotation axis B and rotates with the differential case 26. The differential case 26 is rotatably held. The pinions 50 and 52 have pinion gear portions 44 and 46, which are bevel gears, respectively. The first and second pinions 50 and 52 are the first side gear 30 and the pinion gear portions 44 and 46, respectively. And the second side gear 32.

  Further, the first and second pinions 50 and 52 respectively have shaft halves 41 and 42 obtained by dividing a pinion shaft serving as a rotation shaft of the pinion gear portions 44 and 46. A first pinion gear portion 44 is formed on the first shaft half body 41 and a second pinion gear portion 46 is integrally formed on the second shaft half body 42 by integral forging. Two pinions 50 and 52 are formed. The first shaft half body 41 of the first pinion 50 and the second shaft half body 42 of the second pinion 52 are connected at the connecting portion indicated by reference numeral 54 in FIG. Has been.

  That is, the first pinion 50 and the second pinion 52 can rotate in directions opposite to each other about the axis C. Hereinafter, the rotation of the first and second pinions 50 and 52 around the axis C will be referred to as “spinning”. In contrast, the rotation of the first and second pinions 50 and 52 around the rotation axis B together with the differential case 26 is marked as “revolution” and distinguished from the rotation.

  The first and second pinions 50 and 52 receive the input from the reduction gear device 14 as described above, and when the differential case 26 rotates about the rotation axis B, the differential pin 26 and the rotation axis B become the center. Revolve. As the first and second pinions 50 and 52 revolve, the first and second side gears 30 and 32 that mesh with them, and the first and second drive shafts 16 and 18 that engage with the side gears 30 and 32, respectively, Rotate around the rotation axis B. In this way, the rotation input to the differential case 26 is transmitted to the first and second drive shafts 16, 18, that is, the first and second output shafts. When the first and second pinions 50 and 52 do not rotate, the rotational speed of the differential case 26 and the rotational speed of the first and second drive shafts 16 and 18 are the same.

  Thus, in the process of transmitting the rotation input to the differential case 26 to the first and second drive shafts 16, 18, the first and second pinions 50, 52 are opposite to each other about the axis C. , The first and second side gears 30 and 32 and the first and second drive shafts 16 and 18 engaged with the first and second side gears 30 and 32 are opposite to each other about the rotation axis B with respect to the differential case 26. Relative rotation. That is, one of the two drive shafts 16 and 18 is rotated at a higher rotational speed around the rotation axis B than the differential case 26 and the other is rotated at a lower rotation than the differential case 26. It will rotate at speed.

  In this way, the differential device 10 allows the first pinion 50 and the second pinion 52 to be centered when the rotational speeds of the first drive shaft 16 and the second drive shaft 18 are different, such as when the automobile is turning. By rotating in the opposite directions around C, the difference in rotational speed generated between the first drive shaft 16 and the second drive shaft can be absorbed.

  In the differential device 10 of the present embodiment, the pinion shaft 40 is divided into two shaft halves 41 and 42, and corresponding pinion gear portions 44 and 46 are respectively provided on the shaft halves 41 and 42. Fixed, two pinions 50 and 52 are formed.

  Therefore, according to the differential device 10 of the present embodiment, there is no need to form a pinion gear shaft hole having a slidable contact surface as in the prior art. Since the sliding contact surface of the pinion gear shaft hole that requires high machining accuracy is not required, the differential device 10 and the final reduction gear device 1 can be manufactured at a lower cost.

  By the way, in the differential device 10 of the present embodiment, the pinion gear portions 44 and 46 are fixed to the shaft halves 41 and 42 obtained by dividing the pinion shaft 40, and the pinion 50 and 52 rotate integrally. As described above, in order to absorb the rotational difference between the first and second side gears 30 and 32 about the rotation axis B, the first pinion 50 and the second pinion 52 are opposite to each other about the axis C. Need to rotate.

  Therefore, the first and second pinions 50 and 52 configured as described above are connected to each other at a connection portion 54 shown in FIG. The connection portion 54 has a convex portion 56 formed on the shaft half body 41 of one pinion 50 and a concave portion 58 formed on the shaft half body 42 of the other pinion 52. The portion 56 is configured to be fitted so as to be rotatable about the axis C. In the following description, “fitting” includes a case where there is a “gap” between a shaft (for example, the convex portion 56) and a hole (for example, the concave portion 58) or a case where there is “interference”. It is out.

  As shown in FIG. 3, the first shaft half 41 is formed with a convex portion 56 that is a substantially cylindrical shaft. The convex portion 56 projects from the shaft end surface 41a of the first shaft half 41 in the direction along the axis C, and the length in the direction along the axis C is set to a predetermined value X. On the other hand, the second shaft half 42 is formed with a recess 58 that is a substantially cylindrical hole. The recess 58 is recessed in the direction along the axis C from the shaft end surface 42a of the second shaft half body 42, and the depth along the axis C is set to the same value X as the length of the projection 56. ing. Furthermore, a cylindrical rolling bearing 60 is provided in the recess 58 formed in the second shaft half 42. The outer wall 60 a of the rolling bearing 60 is fitted to the inner wall 58 b of the recess 58, and the rolling bearing 60 is attached to the recess 58 of the second shaft half 42. FIG. 3 shows a mode in which “roller bearings” are provided in the recess 58 as the rolling bearing 60.

  Then, the convex portion 56 of the first shaft half body 41 is inserted into the concave portion 58 of the second shaft half body 42. The outer wall 56 a of the convex portion 56 is fitted into the inner wall 60 b of the rolling bearing 60, and the convex portion 56 is connected to the concave portion 58 via the rolling bearing 60. As a result, the first pinion 50 and the second pinion 52 are connected so as to be relatively rotatable about the axis C.

  The length X of the convex portion 56 and the concave portion 58, the fitting between the concave portion 58 and the bearing outer wall 60a, and the fitting between the bearing inner wall 60b and the convex outer wall 56a are set so as not to cause the wobbling in the connecting portion 54. It is necessary to These dimensions and tolerances are set so that the cylindricity of the pinion shaft 40 (see FIG. 2) connecting the first shaft half 41 and the second shaft half 42 satisfies 0.05 or less. .

  Further, in the differential device 10 of the present embodiment, the first and second pinions 50 and 52 rotate about the axis C with respect to the differential case 26. That is, unlike the conventional pinion shaft, the pinion shaft 40 constituting the first and second pinions 50 and 52 rotates with respect to the differential case 26. Therefore, the differential case 26 needs to hold the first and second pinions 50 and 52 “rotatably” about the axis C.

  Therefore, in the differential case 26, as shown in FIG. 2, pinion washers 70 and 72 are provided between the first and second pinions 50 and 52 and the inner surface of the differential case 26 facing the first and second pinions 50 and 52, respectively. It has been. The first and second pinions 50 and 52 have end faces 74 and 76 (hereinafter, referred to as pinion end faces 74 and 76) on the opposite side to the connection part 54, respectively. The pinion washers 70 and 72 are These are formed in shapes along the pinion end faces 74 and 76 facing each other. The pinion washers 70 and 72 and the first and second pinion end surfaces 74 and 76 are in sliding contact with each other, and the sliding contact portions are lubricated with lubricating oil filled in the differential case 26. In this manner, the first and second pinions 50 and 52 are slidably held in the differential case 26 so as to be rotatable.

  The differential case inner surfaces 66 and 68 sandwich the first and second pinions 50 and 52 and the pinion washers 70 and 72 corresponding thereto by applying a predetermined force in the direction along the axis C. ing. This pinching force is a force such that the pinion washers 70 and 72, the first and second pinions 50 and 52, and the differential case 26 are slightly elastically deformed in the direction along the axis C, and the pinion washers The first and second pinions 50 and 52 are set to a force that allows the first and second pinions 50 and 52 to slide in the differential case 26 without causing seizure between the 70 and 72 and the pinion end surfaces 74 and 76. Thus, the first and second pinions 50 and 52 can be prevented from swinging in the radial direction of the axis C with respect to the differential case 26. As a result, the backlash between the first and second side gears 30 and 32 and the first and second pinion gear portions 44 and 46 meshing with the first and second side gears 30 and 32 can be kept optimal.

  As described above, in the differential device 10 and the final reduction gear device 1 of the present embodiment, the first and second pinion gear portions 44 and 46 are fixed to the shaft half bodies 41 and 42 obtained by dividing the pinion shaft 40. The pinions 50 and 52 are configured to be connected so as to be relatively rotatable, and there is no need to provide a pinion gear shaft hole that requires high machining accuracy as in the prior art. According to this structure, the differential device 10 and the final reduction gear 1 that function in the same manner as the conventional one can be realized at a lower cost.

  In the present embodiment, the shaft halves 41 and 42 and the pinion gear portions 44 and 46 are integrally formed. However, the present invention is not limited to this. The shaft half and the pinion gear may be fixed and can rotate integrally around the axis C. For example, a shaft half provided with a flange having a bolt hole in a pinion gear having no shaft hole is provided. The first and second pinions may be configured by fastening with bolts.

It is sectional drawing of the final reduction gear apparatus of this embodiment. It is sectional drawing of the differential gear of this embodiment. It is a perspective view of the connection part of the 1st and 2nd pinion which comprises the differential gear of this embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Final reduction gear, 10 Differential, 16 1st drive shaft (1st output shaft), 18 2nd drive shaft (2nd output shaft), 26 Differential case, 30 1st side gear, 32 2nd side gear , 40 pinion shaft, 41 first shaft half, 42 second shaft half, 44 first pinion gear part, 46 second pinion gear part, 50 first pinion, 52 second pinion, 54 connecting part.

Claims (5)

A differential device that differentially transmits an input to first and second output shafts,
A differential case that rotates in response to input,
First and second side gears held in the differential case so as to be rotatable about the rotation axis of the differential case and coaxially engaged with the first and second output shafts;
A pinion shaft whose axis is perpendicular to the rotation axis of the differential case and rotates with the differential case; and
First and second pinion gears supported coaxially by the pinion shaft and meshing with both the first and second side gears;
Have
The pinion shaft is divided into first and second shaft halves,
A first pinion gear is fixed to the first shaft half, and a second pinion gear is fixed to the second shaft half to constitute the first and second pinions,
The first and second pinions are connected in a relatively rotatable manner;
Differential device. The differential device according to claim 1,
A first pinion gear is integrally formed on the first shaft half, and a second pinion gear is integrally formed on the second shaft half.
Differential device. The differential device according to claim 1,
The first shaft half is formed with a substantially cylindrical convex portion protruding from the axial end surface thereof,
The second shaft half is formed with a substantially cylindrical recess recessed from its axial end surface.
The differential device in which the convex portion is inserted into the concave portion and the first and second pinions are connected. The differential device according to claim 2,
The differential unit, wherein the convex part and the concave part are connected via a rolling bearing. A final reduction gear that decelerates the input rotation from the propulsion shaft and transmits it differentially to the first and second drive shafts;
A drive pinion connected to the propulsion shaft;
A ring gear meshing with the drive pinion;
A differential case that is fixed to the ring gear and rotates;
First and second side gears, which are rotatably held around the rotation shaft of the differential case in the differential case, and are coaxially engaged with the first and second drive shafts;
A pinion shaft whose axis is perpendicular to the rotation axis of the differential case and rotates with the differential case; and
First and second pinion gears supported coaxially by the pinion shaft and meshing with both the first and second side gears;
Have
The pinion shaft is divided into first and second shaft halves,
A first pinion gear is fixed to the first shaft half, and a second pinion gear is fixed to the second shaft half to constitute the first and second pinions,
The first and second pinions are connected in a relatively rotatable manner;
Final reduction gear.

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