JP2008281159A - Differential device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a differential device capable of certainly carrying out differential limiting while restraining enlargement, weight increase, etc. and low in manufacturing cost. <P>SOLUTION: This differential device 10 has a differential case 18 to support a left axle 28 and a right axle 30 and a pair of side gears 48, 50 connected to the both left and right axles 28, 30 and respectively engaged with differential pinions 44, 46 axially supported on a pinion shaft 36 fixed on the differential case 18. A plurality of groove parts 54 extending in a direction toward the outer peripheral side from the shaft center side are formed on back surfaces 44b, 46b on the opposite side of the surface side on which tooth surfaces 44a, 46a to be engaged with each of the side gears 48, 50 of the differential pinions 44, 46, and a rolling element 56 free to move in the groove part 54 is arranged in each of the groove parts 54. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a differential device that transmits a driving force from a prime mover such as an engine or a motor to an axle.

  A differential apparatus mounted on an automobile is disposed in a power train of a vehicle in order to rotate an outer wheel faster than an inner wheel during turning while maintaining a torque distribution equally divided between the left and right wheels. The automobile can make a smooth turn by the action of the differential device.

  A typical differential device has a pair of side gears each composed of a bevel gear, and a pair of differential pinions. A pair of side gears arranged so as to face each other are splined to axles that transmit rotation to the left and right wheels, respectively. Similarly, a pair of differential pinions are also arranged to face each other and mesh with both side gears. The differential pinion is fixed to a ring gear (mainly an external gear for an FF vehicle and a bevel gear for an FR vehicle) to which the output of the transmission is transmitted, and is arranged so as to be able to revolve and rotate together with the ring gear.

  In such a differential device, for example, when one drive wheel slips and slips on a snowy road or the like, the drive wheel enters a substantially unloaded state. For this reason, the rotation of the drive wheel on the other grounded side does not increase, and the rotation of the differential case is converted to the rotation of the drive wheel on the idle side, so that the drive wheel on the idle side is rotated. The rotation of the motor increases excessively, and the driving force may not be transmitted to the grounded driving wheel.

  Therefore, in order to avoid this problem, LSD (Limited Slip Differentials) for limiting the differential in the differential device may be mounted on the differential device. For example, Patent Document 1 describes a differential control method of a differential device of a torque difference sensitive type that controls differential limitation by detected output torque.

JP 2000-283280 A

  However, in order to add such a torque difference-sensitive function to the differential device, it is necessary to add a precisely processed torque difference detection mechanism and an electrical control system. For this reason, it has been pointed out that this increases the size, weight, and cost of the differential device.

  The present invention has been made in view of the above-described conventional problems, and can reliably perform differential limiting while suppressing an increase in the size and weight of the differential device, and also can be manufactured at low cost. An object is to provide a differential device.

  A differential device according to the present invention includes a differential case that rotatably supports a pair of axles, and a pair that is coupled to each axle and that meshes with a differential pinion that is pivotally supported by a pinion shaft fixed to the differential case. In the differential device having a plurality of side gears, a groove portion extending in a direction from the axial side toward the outer peripheral side is provided on the back surface of the differential pinion opposite to the surface side provided with the tooth surfaces meshing with the side gears. Two or more are formed, and each of the groove portions is provided with a rolling element movable in the groove portion.

  According to such a configuration, for example, when one drive wheel idles on a snowy road or the like, when a large differential rotation occurs between the left and right axles and the differential pinion causes excessive high-speed rotation, The said rolling element moves to the outer peripheral side in a groove part, and presses it in the direction which presses a differential pinion to a side gear. Thereby, the backlash between the differential pinion and the side gear can be reduced, and the differential rotation between the right and left axles can be appropriately limited.

  The groove portion is formed so as to become shallower from the axial side toward the outer peripheral side, and the opening side of the groove portion is closed between the back surface of the differential pinion and the inner wall surface of the differential case. It is also possible to configure such that a sealing body for sealing the rolling element is interposed in the groove portion.

  According to the present invention, for example, when one of the drive wheels is idled on a snowy road or the like, the differential pinion is pressed by the rolling element disposed in the groove formed in the differential pinion, and the differential pinion and the side gear The backlash between is reduced. This makes it possible to appropriately limit the differential rotation between the left and right axles with a small size, light weight, and low cost.

  DESCRIPTION OF EMBODIMENTS Preferred embodiments of a differential apparatus according to the present invention will be described in detail below with reference to the accompanying drawings.

  FIG. 1 is a partially omitted cross-sectional view along the axle direction of a differential apparatus 10 according to an embodiment of the present invention. The differential device 10 according to the present embodiment is mounted on the front side of an automobile, for example, and transmits driving force from the engine or motor to the front wheels that are driving wheels, but can also be mounted on the rear side. Of course.

  The differential device 10 includes a hollow and flat spherical differential case 18 rotatably supported in the transmission case 12 via a pair of ball bearings 14 and 16, and a plurality of differential devices 10 on the outer wall surface of the differential case 18 (FIG. 1). In FIG. 2, a final driven gear (ring gear) 22 fixed by bolts 20 of which only one is shown and the others are omitted) and a cylindrical shape extending from both ends of the differential case 18 in the vehicle body left-right direction (axis A direction). Inboard portions (boss portions) 24 and 26 are provided.

  The shaft end side of the left axle 28 is rotatably supported on the inner peripheral side of the left inboard portion 24. Similarly, the shaft end side of the right axle 30 is rotatable on the inner peripheral side of the right inboard portion 26. It is supported.

  The differential case 18 is formed with a pair of holes 32 and 34 centering on an axis B perpendicular to the axis A extending in the left-right direction (axle direction) of the vehicle body. The pinion shaft 36 which is located between the opposite ends of the left and right axles 28 and 30 and is orthogonal to the axis A of the left and right axles 28 and 30 is fitted into the shaft.

  The pinion shaft 36 has a pin hole 38 penetratingly formed along the axis A on one end side (lower end side in FIG. 1), and a pin hole formed coaxially with the pin hole 38 in the differential case 18. A pin 42 is inserted into the pin hole 38 and the pin hole 38. Thereby, the pinion shaft 36 is fixed to the differential case 18 so as not to rotate and to be inserted and removed.

  A pair of differential pinions 44 and 46 are rotatably inserted into both end sides of the pinion shaft 36 in the vicinity of the inner wall surface of the differential case 18, and a pair of meshing with the pair of differential pinions 44 and 46. Side gears 48 and 50 are splined to the left axle 28 and the right axle 30, respectively. That is, in the differential case 18, the differential pinions 44 and 46 are rotatably supported around the axis B, while the side gears 48 and 50 are rotatably supported along with the left and right axles 28 and 30 around the axis A. Yes.

  Between the back surfaces (back surfaces) 44b and 46b of the differential pinions 44 and 46 opposite to the surface side where the tooth surfaces 44a and 46a are formed, a curved inclined surface is provided between the inner wall surface of the differential case 18. An annular thrust washer (sealing body) 52 is interposed.

  As shown in FIGS. 2 and 3, the back surfaces 44b and 46b of the differential pinions 44 and 46 have a plurality of groove portions 54 extending in the direction from the axial center side (axis B, center side) toward the outer peripheral side. In the case of the embodiment, six are formed radially at equal intervals, and in these groove portions 54, rolling elements 56 that are movable along the thrust washers 52 in the groove portions 54 are disposed. The rolling element 56 only needs to have a shape that can move smoothly in the groove 54, and examples thereof include a spherical (ball-shaped) or cylindrical metal member.

  In this case, along with the shape of the back surfaces 44b and 46b curved from the axial side toward the outer peripheral side, the groove portion 54 is formed so as to become shallower from the axial side toward the outer peripheral side. In other words, the bottom surface of the groove portion 54 is formed along a planar shape orthogonal to the axis B. The opening side of the groove 54 is closed by the thrust washer 52, and the rolling element 56 is sealed in the groove 54 by the thrust washer 52.

  On the other hand, a planar and annular thrust washer 58 is interposed between the back surface (back surface) opposite to the front surface side where the tooth surfaces of the side gears 48 and 50 are formed and the differential case 18. .

  The thrust washer 52 serves to receive a thrust force in the direction of the axis B of the pinion shaft 36, and the thrust washer 58 serves to receive a thrust force in the direction of the axis A of the left and right axles 28, 30.

  Further, oil seals 60 and 62 for preventing leakage of the lubricating oil filled in the transmission case 12 to the outside are disposed between the left and right axles 28 and 30 and the transmission case 12, respectively. Yes. Between the oil seals 60 and 62 and the ball bearings 14 and 16, they are lifted up and scattered by the final driven gear 22, and collected through a lubricating oil guide groove (not shown) provided in the transmission case 12. Annular grooves (annular spaces) 64 and 66 to which lubricating oil is supplied are formed.

  Next, the operational effects of the differential apparatus 10 according to the present embodiment basically configured as described above will be described.

  First, during normal travel of an automobile equipped with the differential device 10 according to the present embodiment, during linear running, the driving force from the engine and motor of the automobile is applied to the final driven gear 22, and the differential driven gear 22 and the differential gear 22 together. The case 18 is driven to rotate while being supported by the ball bearings 14 and 16.

  Accordingly, the pinion shaft 36 fixed to the differential case 18 is driven to rotate about the axis A, and at the same time the differential pinions 44 and 46 are revolved about the axis A. At this time, since there is no difference in the load between the left and right axles 28 and 30, the differential pinions 44 and 46 do not rotate around the axis B but only perform the revolution. For this reason, the side gears 48 and 50 meshing with the differential pinions 44 and 46 are rotationally driven in the same direction around the axis A (opposite directions at opposite ends). Thereby, the left axle 28 and the right axle 30 are also rotationally driven in the same direction at the same rotational speed, and the automobile can move forward and backward.

  In this state, for example, when the vehicle turns leftward, a predetermined load is applied to the side gear 48 to which the left axle 28 that is the inner wheel side of the turn is connected, so the right axle 30 that is the outer wheel side of the turn is connected. Therefore, a difference in rotational speed is generated between the side gear 50 and the side gear 50. Accordingly, the differential pinions 44 and 46 revolving due to the rotation of the differential case 18 rotate at a predetermined rotational speed in a direction to increase the rotational speed of the side gear 50 on the outer ring side of the turning. As a result, a difference in rotational speed is generated between the left axle 28 and the right axle 30, so that the automobile can turn smoothly. That is, for example, if the rotational speed of the final driven gear 22 is 100, the rotational speed of the left axle 28 is 70, the rotational speed of the right axle 30 is 130, and the average rotational speed of the left and right axles 28 and 30 is It matches the rotation speed.

  However, when one drive wheel, for example, the right wheel slips on a snowy road or the like, the right wheel becomes almost unloaded and starts to idle, and the right axle 30 and the side gear 50 connected thereto rotate at an extremely high rotational speed. Will do. Further, the left axle 28 and the side gear 48 connected to the left wheel, which is the driving wheel on the side that is in contact with the ground, are in a state where their rotations are substantially fixed. For this reason, the differential pinions 44 and 46 revolving due to the rotation of the differential case 18 rotate at an extremely high rotational speed in the direction of increasing the rotational speed of the side gear 50 to which the right axle 30 is connected, and the left axle 28 and the right A large difference in rotational speed is produced with respect to the axle 30.

  In this case, for example, if the rotational speed of the final driven gear 22 is 100, the rotational speed of the left axle 28 is approximately 0, and the rotational speed of the right axle 30 is approximately 200, that is, all the rotational driving force from the final driven gear 22 is right. The state of being transmitted to the axle 30 causes a situation in which the rotational driving force is not transmitted to the left axle 28 on the ground side.

  Therefore, in the case of the differential device 10 according to the present embodiment, in order to limit the extreme differential between the left and right axles 28 and 30 as described above, the grooves 54 are formed in the rear surfaces 44b and 46b of the differential pinions 44 and 46. , And a rolling element 56 is disposed in the groove 54.

  That is, when the differential pinions 44 and 46 are not rotating or are rotating at a low speed, as shown in FIG. 4A, the rolling element 56 is close to the axial center side (pinion shaft 36 side) of the groove portion 54. It has become. On the other hand, in the state where an excessive rotational speed difference occurs between the left and right axles 28 and 30 as described above and the differential pinions 44 and 46 are rotating at an extremely high rotational speed, as shown in FIG. The rolling element 56 moves to the outer peripheral side of the groove portion 54 (the side away from the pinion shaft 36) by the centrifugal force generated with the high-speed rotation of the pinions 44 and 46. At this time, the rolling element 56 presses the upper surface (bottom surface) of the groove portion 54 facing the thrust washer 52 while moving to the outer peripheral side of the groove portion 54 along the curved shape of the thrust washer 52, and the differential pinions 44, 46. Is lifted (pressed) in a direction close to the side gears 48, 50.

  As a result, the backlash between the differential pinions 44 and 46 and the side gears 48 and 50 (meshing intersection between tooth surfaces, tooth surface play) is jammed, and the difference in rotational speed between the side gears 48 and 50 is reduced. That is, the differential between the left and right axles 28 and 30 is limited. Accordingly, the rotational driving force from the final driven gear 22 is transmitted not only to the idling right axle 30 side, but also to the grounded left axle 28, in other words, on the grounding side. It is possible to effectively avoid the situation where the rotational driving force is not transmitted to the left axle 28.

  As described above, according to the differential device 10 according to the present embodiment, the groove portion 54 is formed on the back surfaces 44 b and 46 b of the differential pinions 44 and 46, and the rolling elements 56 are disposed in the groove portion 54. For this reason, when one of the drive wheels is idling on a snowy road or the like, a large differential rotation occurs between the left and right axles 28 and 30, and the differential pinions 44 and 46 cause excessive high-speed rotation. The moving body 56 moves and moves the differential pinions 44 and 46 in a direction of pressing (adjacent to) the side gears 48 and 50. As a result, the backlash between the differential pinions 44 and 46 and the side gears 48 and 50 is reduced, so that the differential rotation between the left and right axles 28 and 30 is appropriately limited. Therefore, even when one of the driving wheels is in a substantially no-load state, it is possible to reliably transmit the driving force from the engine or motor to the other driving wheel that is grounded.

  In other words, in the differential device 10, the speed-sensitive differential limiting mechanism (LSD function) can be realized with a simple configuration by the groove portion 54 and the rolling element 56, and the differential device 10 can be reduced in size and weight. Is possible. Further, since a complicated control device or the like is not required, the structure of the differential device 10 can be simplified and the cost can be reduced.

  Further, when one of the driving wheels is in a substantially no-load state or the like, the backlash between the differential pinions 44 and 46 and the side gears 48 and 50 is reduced, resulting in rattling between these gears. It is also possible to effectively suppress the generation of abnormal noise.

  Note that the weight of the rolling elements 56 may be set so that the differential pinion can be lifted by a centrifugal force at a predetermined rotational speed, based on the number of the rolling elements 56 and the weight of the differential pinions 44 and 46. Further, in the differential apparatus 10 according to the present embodiment, in addition to the number of the groove portions 54 being six, for example, two differential pinions 70 (see FIG. 5A) and three differential pinions 72 (see FIG. 5A). (See FIG. 5B). However, if the number of the groove portions 54 is one, it is difficult to lift the differential pinions 44 and 46 smoothly. Therefore, the number of the groove portions 54 is preferably two or more.

  In addition, the back surfaces 44b and 46b of the differential pinions 44 and 46 are not necessarily curved at the inclined surfaces from the axial center side to the outer peripheral side. Similarly, the inclined surface of the thrust washer 52 is not necessarily curved.

  Furthermore, the number of installed differential pinions is not limited to two, and may be four, for example. In this case, for example, a new pinion shaft orthogonal to the pinion shaft 36 may be added.

  As mentioned above, although this invention was demonstrated by the said embodiment, it is naturally possible to take various structures, without restricting to this, without deviating from the summary of this invention.

It is a partially omitted sectional view along the axle direction of the differential device according to the embodiment of the present invention. FIG. 2 is a partially omitted exploded perspective view in which the differential pinion and its peripheral components shown in FIG. 1 are enlarged. FIG. 3 is a partially omitted exploded perspective view of the differential pinion shown in FIG. 2 as viewed from the back side. FIG. 4A is a partially omitted cross-sectional view of the differential pinion and its peripheral parts in a state where the rolling element is close to the axial center side, and FIG. 4B is a diagram showing the differential pinion and It is a partially omitted sectional view of the peripheral parts. FIG. 5A is a bottom view showing a modified example of the differential pinion constituting the differential device according to the present embodiment, and FIG. 5B is a bottom view showing another modified example of the differential pinion constituting the differential device according to the present embodiment. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Differential apparatus 12 ... Transmission case 22 ... Final driven gear 28 ... Left axle 30 ... Right axle 36 ... Pinion shaft 44, 46, 70, 72 ... Differential pinion 44a, 46a ... Tooth surface 44b, 46b ... Back surface 48, 50 ... Side gear 52, 58 ... Thrust washer 54 ... Groove 56 ... Rolling element

Claims (3)

A differential case that rotatably supports a pair of axles;
A pair of side gears coupled to each axle and meshing with a differential pinion pivotally supported by a pinion shaft fixed to the differential case;
In a differential apparatus having
Two or more grooves extending in the direction from the axial side toward the outer peripheral side are formed on the back surface of the differential pinion opposite to the surface side provided with the tooth surfaces that mesh with the side gears, and A differential device, wherein each groove portion is provided with a rolling element movable in the groove portion. The differential device according to claim 1,
The groove is formed so as to become shallower from the axial side toward the outer peripheral side,
Between the back surface of the differential pinion and the inner wall surface of the differential case, a sealing body that closes the opening side of the groove and seals the rolling element is interposed in the groove. Feature differential device. The differential apparatus according to claim 1 or 2,
The differential device, wherein the differential pinion moves in a direction approaching the side gear as the rolling element moves in a direction toward the outer peripheral side of the groove.

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