JP4665445B2 - Driving force transmission device for vehicle - Google Patents

Description

  The present invention relates to a vehicle driving force transmission device, and more particularly to a torque-sensitive vehicle driving force transmission device.

  As an example of a torque-sensitive vehicle driving force transmission device, a planetary gear type vehicle differential gear device (see, for example, Patent Document 1) will be briefly described with reference to FIG. An internal gear 104 is rotatably accommodated inside the differential case 102, and a sun gear 106 is disposed on a concentric circle on the inner peripheral side of the internal gear 104. Between the internal gear 104 and the sun gear 106, a plurality of planet gears 108 held by the planetary carrier 110 are disposed and meshed with both the gears 104 and 106. In the configuration of the present invention, the internal gear 104, the sun gear 106, and the planet gear 108 all have helical teeth and mesh with each other.

  The internal gear 104 has a cylindrical portion 104b and an inward flange portion 104c extending from one end portion (left end in FIG. 5) to the inner peripheral side, and is formed on the inner peripheral surface of the cylindrical portion 104b. The internal teeth 104a have splines 104d formed on the inner peripheral surface of the flange portion 104c. A spline 114a formed on the outer periphery of the coupling 114 is fitted to the spline 104d of the flange portion 104c.

  In the vehicle differential gear device having the above-described configuration, for example, the drive from the engine side is transmitted to the differential case 102 integral with the planetary carrier 110 and the coupling 114 is spline-engaged with the internal gear 104 and formed on the inner periphery. One of the front and rear wheels of the four-wheel drive vehicle is connected to the spline 114b, and the other of the front and rear wheels is connected to the spline 106b formed on the inner periphery of the sun gear 106.

  In this vehicle differential gear device, when the driving force of the engine is transmitted, the planetary carrier 110 holding the planet gear 108 is rotationally driven, and is held by the planetary carrier 110 when traveling straight on a good road surface. The planet gear 108 and the internal gear 104 and the sun gear 106 that mesh with the planet gear 108 rotate integrally without rotating relative to each other. When cornering, the planet gear 108 held by the planetary carrier 110 rotates to absorb the rotational difference between the front and rear drive wheels connected to the internal gear 104 and the sun gear 106, respectively.

  Further, when the front and rear road surface μs are different and there is a difference in the gripping force between the front and rear drive wheels, the axial thrust force generated by the rotational reaction force between the helical teeth meshing with each other, the planet gear 108 and this planet Friction force generated on the sliding surface with the planetary carrier 110 holding the gear 108, and further, the planetary gear 108 and the planetary carrier 110 are disposed between the front end surface and the inner surface of the flange portion 104 c of the internal gear 104. Friction force caused by sliding of the washer 116, the flange portion 104 c of the internal gear 104 and the coupling 114 and the washer 124 disposed between the inner surface of the differential case 102, the washer between the end surface of the sun gear 106 and the planetary carrier 110. Washers between 120, 122 and coupling 114 Such as by frictional force due to sliding between 118 performs differential between the internal gear 104 and sun gear 106, i.e., the torque distribution while limiting differential between the front and rear wheels.

The vehicle differential gear device having the above-described configuration is a planetary gear type torque-sensitive center differential, and the torque generated in the two output shafts (the coupling 114 connected to the internal gear 104 and the sun gear 106) is Based on the torque distribution set by the gear ratio, a differential limit torque generated in proportion to the input torque to the housing 102 is added and subtracted (one of the output shafts is added and the other is subtracted).
Japanese Patent Application No. 2003-118818 (page 7-11, FIG. 1)

  In a vehicle differential gear device as an example of a conventional vehicle driving force transmission device, as shown in FIG. 6, the transmission torque is further determined based on torque distribution determined by the gear ratio (see symbol G in FIG. 6). Because the differential limiting torque proportional to the input torque from the housing (difference case) 102 is added (see arrow T1 in the figure), for example, the rear wheel drive is used as a base, and the torque is distributed to the front wheels according to the input torque. In other words, the number of parts requiring high machining accuracy is high, the cost is increased, and the weight and volume are increased.

The present invention relates to a first output shaft rotatably accommodated in a housing, a second output shaft disposed coaxially with the first output shaft, and thrust generation for generating thrust by torque input to the housing. and a mechanism, pressing against the first output shaft by the thrust of the thrust generating mechanism to the second output shaft, thereby to generate a frictional force between the shaft and the output torque of the frictional force the second output shaft It is characterized by that.

  The vehicular driving force transmission device of the present invention has a simple configuration as compared with the conventional one, so that the cost, weight and volume can be suppressed. Further, since the transmission torque on the second output shaft side starts from zero instead of adding torque based on the gear ratio as in the conventional differential gear device, for example, torque based on rear wheel drive Distribution characteristics can be obtained.

A first output shaft to which an input torque is transmitted via a thrust generated by a thrust generating mechanism is disposed in the housing, and is disposed coaxially with the first output shaft, and the thrust acts via the first output shaft. The object of suppressing the absolute value of the differential limiting torque is achieved with a simple configuration of providing a second output shaft that uses the generated frictional force as an output torque.

  Hereinafter, the present invention will be described with reference to embodiments shown in the drawings. FIG. 1 is a longitudinal sectional view of a vehicle driving force transmission device (torque-sensitive coupling) 1 according to an embodiment of the present invention, and includes a case 2 having a large diameter cylindrical portion 2a and a small diameter cylindrical portion 2b. A housing 8 is formed by a cap 6 that is inserted into an opening (the right-side opening in FIG. 1) on the large-diameter cylindrical portion 2 a side of the case 2 and fixed by a bolt 4.

  A first output shaft (main output shaft) 10 is held in the housing 8 so as to rotate integrally with the case 2 on a cam surface formed on the flange portion 10b. The main output shaft 10 has a cylindrical portion 10a and a flange-shaped portion 10b formed on the outer peripheral surface thereof, and a spline 10c is formed on the inner peripheral surface of the cylindrical portion 10a. A rear shaft (not shown) of the 4WD vehicle is connected. Further, a second output shaft (coupling output shaft 12) is rotatably arranged on the same axis as the main output shaft 10. A front shaft (not shown) of the 4WD vehicle is connected to the spline 12a formed on the inner peripheral surface of the coupling output shaft 12.

  A thrust washer 14 is disposed between the end face of the coupling output shaft 12 on the main output shaft 10 side and the main output shaft 10, and the end face on the opposite side of the coupling output shaft 12 (the end face on the right side in FIG. 1). Two thrust washers 16 and 18 are disposed between the inner surface of the cap 6 and the inner surface of the cap 6.

  Further, a thrust generating mechanism 20 is provided between the main output shaft 10 and the disc-shaped bottom surface 2 c between the large diameter cylindrical portion 2 a and the small diameter cylindrical portion 2 b of the case 2. The thrust generating mechanism 20 of this embodiment includes a flange portion 10b formed on the outer peripheral side of the main output shaft 10, a ring-shaped plate 22 that is disposed inside the bottom surface 2c of the case 2 and rotates integrally with the case 2, and these It is comprised from the ball | bowl 24 interposed between the flange part 10b and the plate 22, and on the mutually opposing surface of the flange part 10b and the ring-shaped plate 22, it is a cam surface (for example, radial V-groove, for example). ) Is formed. The plate 22 corresponds to a “first cam member” of the present invention, and the flange portion 10b corresponds to a “second cam member” of the present invention. When the flange portion 10b and the plate 22 rotate relative to each other by the input torque from the housing 8, a thrust is generated that presses the flange portion 10b in the axial direction (right side of the drawing) of the first output shaft by the action of the cam. The thrust of the coupling output shaft 12 is pressed by this thrust, the thrust washer 14 disposed between one end surface (the left end surface in FIG. 1) of the coupling output shaft 12 and the main output shaft 10, and the other end surface. And the cap 6 receive the frictional force of the two thrust washers 16 and 18 disposed between them. The input torque is transmitted to the second output shaft 12 by this frictional force, and is transmitted to the front shaft as a coupling output torque.

  The operation of the vehicle driving force transmission device (torque-sensitive coupling) according to the above configuration will be described with reference to FIG. As described above, the driving torque of the engine (not shown) is input from the outer peripheral side of the housing 8 (see arrow A in FIG. 2). This input torque A is transmitted to the main output shaft 10 while generating a thrust by a thrust generating mechanism 20 comprising a cam (the flange 10b of the main output shaft 10 and the ring-shaped plate 22) and a ball 24 (arrow B in FIG. 2). reference). Further, this thrust acts on the coupling output shaft 12, and the coupling output shaft 12 is placed between the flange portion 10 b of the main output shaft 10 and the inner surface of the cap 6 via the thrust washers 14, 16, 18 on both sides thereof. To generate friction torque (see arrow C in FIG. 2). This friction torque C becomes a coupling output torque. Therefore, the arrow D in FIG. 2 is the main output torque from the main output shaft 10, and the arrow E is the coupling output torque from the coupling output shaft 12.

  When the road surface resistance between the front side where the torque is output from the main output shaft 10 and the rear side output from the coupling output shaft 12 are greatly different, as in the case of the conventional differential gear device, it is proportional to the input torque. In the torque-sensitive coupling according to this embodiment, as shown in FIG. 3, the transmission torque T2 on the coupling output shaft 12 side (rear side) is zero%. Since it is added as a reference, the absolute value of the torque distributed to the front side can be suppressed as compared with the conventional configuration, and the weight of the drive components thereafter can be reduced. Note that the characteristics of torque distribution of the front and rear wheels with respect to the input torque can be easily adjusted by the angle of the cam surface. By configuring the cam surface with a plurality of surfaces having different angles, for example, it is possible to obtain a characteristic that the ratio of torque distributed to the second output shaft rises sharply when the input torque exceeds a predetermined value. it can.

  FIG. 4 is a longitudinal sectional view of the vehicle driving force transmission apparatus according to the second embodiment. This embodiment is a vehicle driving force transmission device (torque-sensitive coupling) 51 of a twin differential type in which a bevel gear type front differential 80 is coupled to a main output shaft 60 and based on front wheel drive.

  The differential gear device 51 for a twin differential type vehicle has a first output shaft coupled to a bevel gear type front differential 80 in a housing 58 formed by abutting a first housing 58A and a second housing 58B. A (main output shaft) 60 and a second output shaft (coupling output shaft 62) arranged coaxially with the main output shaft 60 are rotatably accommodated.

  A cup-shaped main output shaft 60 having a plurality of step portions is accommodated in the housing 58. The largest diameter portion 60a of the main output shaft 60 is accommodated in the portion having the largest inner diameter of the housing 58 with a slight gap therebetween. A coupling output shaft 62 having an inner surface of substantially the same shape is disposed on the outer surface side including the medium diameter portion 60b and the small diameter portion 60c of the main output shaft 60. The small diameter portion 62c of the coupling output shaft 62 protrudes outside the housing 58 and is connected to, for example, a rear shaft (not shown). The main output shaft 60 and the coupling output shaft 62 are arranged coaxially and rotate around the same axis O1.

  Three thrust washers 82 between the end face on the coupling output shaft 62 side of the large diameter portion 60a of the main output shaft 60 and the end face on the main output shaft 60 side of the outer peripheral side large diameter portion 62a of the coupling output shaft 62, 84 and 86 are arranged. Out of the three thrust washers 82, 84, 86, the outer two 82, 86 have engaging portions (not shown) formed on the outer peripheral surface engaged with the inner surface of the housing (second housing 58B). The intermediate thrust washer 84 is configured to rotate integrally with the engagement portion on the inner peripheral side engaged with the coupling output shaft 60. In addition, a thrust washer 88 is also disposed between the end surface (the right end surface in FIG. 4) of the outer periphery of the coupling output shaft 62 opposite to the main output shaft 60 and the inner surface of the housing 58.

  An axial groove 60d is formed on the inner peripheral surface of the large diameter portion 60a of the main output shaft 60, and a direction orthogonal to the rotation axis O1 of the main output shaft 60 and the coupling output shaft 62 is formed in the groove 60d. Both ends of the pinion pin 90 are inserted.

  Pinion gears 92 are fitted on the outer circumferences of the pinion pins 90 near both ends. The pair of pinion gears 92 mesh with a pair of side gears 94 arranged on the left and right sides around the rotation axis O1 of the main output shaft 60 and the coupling output shaft 62. A bevel gear 90 includes a pinion pin 90 inserted into the axial groove 60d of the main output shaft 60, a pair of pinion gears 92 fitted to the pinion pin 90, and a pair of side gears 94 disposed on both the left and right sides and meshing with the pinion gear 92. For example, left and right side gears 94 are respectively connected to front left and right axles (not shown).

  A thrust generating mechanism 70 is provided between the outer peripheral portion of the inner surface of the housing (first housing 58A) and the end surface of the large diameter portion 60a of the main output shaft 60. The thrust generating mechanism 70 is opposed to the first cam members 96 on the inner surface of the first housing 58A and a plurality of first cam members 96 held on the end face of the main output shaft 60 at equal intervals in the circumferential direction. A second cam member 98 is held in position. The first cam member 96 is formed with a V-shaped groove in the radial direction, and a V-shaped protrusion formed on the second cam member 98 is engaged with the V-shaped groove of the first cam member 96. Thrust is generated by the relative rotation of the cam members 96 and 98.

  When engine driving force is input to the housing 58, the input torque is transmitted to the main output shaft 60 while generating thrust by the thrust generating mechanism 70. This thrust acts on the coupling output shaft 62 side, and thrust washers 82, 84, 86 between the main output shaft 60 and the coupling output shaft 62 and the coupling output shaft 62 and the housing (second housing 58B). The friction torque generated by the thrust washer 88 is transmitted to the rear shaft as a coupling output torque from the coupling output shaft 62. Further, axial thrust from the bevel gear (pinion 92) of the front differential 80 also acts on the coupling output shaft 62 via the side gear 94 and the main output shaft 60.

  In the twin differential type vehicle driving force transmission device 51 having the above-described configuration, the driving force from the engine is normally input to the housing 58 and is applied to both side gears 94 of the bevel gear type front differential 80 coupled to the main output shaft 60. Both front shafts are connected, and the rear shaft is connected to the coupling output shaft 62.

  In this embodiment, the input torque from the housing 58 is generated by the thrust generating mechanism 70 and transmitted to the main output shaft 60 as in the first embodiment, and the frictional force generated by the thrust is coupled. In addition to the output torque from the output shaft 62, the thrust from the bevel gear (pinion 92) of the front differential 80 can also act on the coupling output shaft 62, and a large differential limiting force can be obtained.

It is a longitudinal cross-sectional view which shows the principal part of the driving force transmission device for vehicles. Example 1 It is explanatory drawing which shows the transmission direction of the torque of the said driving force transmission device for vehicles. It is a graph explaining the effect | action of the said Example. It is a longitudinal cross-sectional view which shows a twin diff type vehicle driving force transmission device. (Example 2) It is a longitudinal cross-sectional view of the differential gear device for vehicles as an example of the conventional vehicle driving force transmission device. It is a graph which shows the transmission torque of the conventional differential gear apparatus for vehicles.

Explanation of symbols

8 Housing 10 First output shaft (main output shaft)
12 Second output shaft (coupling output shaft)
20 Thrust generating mechanism

Claims (3)

A first output shaft rotatably accommodated in the housing; a second output shaft disposed coaxially with the first output shaft; and a thrust generating mechanism for generating a thrust by torque input to the housing. ,
Pressing against the first output shaft by the thrust of the thrust generating mechanism to the second output shaft, thereby to generate a frictional force between the shaft and characterized in that the frictional force was output torque of the second output shaft A vehicle driving force transmission device. The thrust generating mechanism includes a first cam member that rotates integrally with the housing, and a second cam member that faces the first cam member and rotates integrally with the first output shaft, and the first cam member and the first cam member An axial thrust is generated by relative rotation with the second cam member,
2. The vehicle driving force transmission device according to claim 1, wherein the second output shaft receives a thrust from the second cam member to generate a frictional force.   3. The vehicle driving force transmission device according to claim 2, wherein the second output shaft receives a thrust from the second cam member and is pressed against the housing to generate a frictional force. 4.

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