JP2007002984A - Differential device with differential restricting mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a differential device having good differential restricting property corresponding to input torque without complicating the construction. <P>SOLUTION: A ring gear member 6 is divided into an input side ring gear member 6a and an output side ring gear member 6b, the input side ring gear member 6a is made to mesh with a planetary pinion 11a, the output side ring gear member 6b is continuously provided on a sun gear shaft 5 via a multiple disc clutch 10, both members 6a, 6b are made to mesh with each other via a dog 15, and input side dog teeth 13 are formed with two-stage cam faces 13a, 13b ranging from the dedendum side to the addendum side. Since a cam angle θ1 on the side of the cam face 13a is set to be gentle and a cam angle θ2 on the side of the cam face 13b is set to be sharp, a change in differential restricting torque with a change in input torque is reduced when the input torque is smaller, and a change in differential restricting torque with a change in input torque is increased when the input torque is greater. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a differential device having a planetary gear mechanism, and more specifically, a differential with a differential limit mechanism that generates a differential limit torque in accordance with torque acting on either an input side or an output side element of the planetary gear mechanism. It relates to a moving device.

  Conventionally, a full-time four-wheel drive vehicle using a planetary gear mechanism as a center differential is known. Many of these types of center differentials are also provided with a differential limiting mechanism for appropriately distributing torque by limiting the differential between the front and rear wheels in accordance with the torque acting on the center differential.

  For example, Patent Document 1 (Japanese Patent Laid-Open No. 2004-225716) discloses a differential device including a torque-sensitive differential limiting mechanism. That is, in this document, the ring gear member constituting the planetary gear mechanism is divided into an input side ring gear member and an output side ring gear member, the input side ring gear member is engaged with the planetary pinion, and the output side ring gear member is connected via the clutch member. In addition to being connected to the sun gear shaft, a dog is provided between the input side ring gear member and the output side ring gear member.

When an input torque generated by resistance during travel is applied to the input side ring gear member and a cam thrust force acting in the axial direction is generated on the cam surface of the dog, the output side ring gear member is pressed against the clutch member via the pressure plate. Is added. As a result, a differential limit corresponding to the input torque is obtained.
JP 2004-225716 A

  By the way, in the technique disclosed in the above-mentioned document, since the dog cam surface is linear, the pressing force applied to the clutch member has a value substantially proportional to the input torque.

  However, when the pressing force is changed in proportion to the input torque, the input torque is low, and a relatively high pressing force is generated even in a region where almost no pressing force is applied to the clutch member. Therefore, torque loss due to drag resistance is reduced. There is an inconvenience that occurs easily.

  On the other hand, differential restriction is required in a region where the input torque is high. However, if the pressing force is changed in proportion to the input torque, sufficient pressing force cannot be obtained, and a good differential limiting effect can be obtained. There are inconveniences that cannot be obtained.

  In view of the above circumstances, the present invention suppresses the generation of unnecessary differential limiting torque by setting the pressing force applied to the clutch member that executes differential limiting to be low when the input torque is small, and is based on drag resistance. It is an object of the present invention to provide a differential device with a differential limiting mechanism that can reduce torque loss and can obtain a good differential limiting effect by setting a high pressing force when the input torque is large.

  In order to achieve the above object, a differential device with a differential limiting mechanism according to the present invention transmits drive torque from an engine to a planetary gear mechanism via an input shaft, and the first output shaft and the second output via the planetary gear mechanism. In the differential device that distributes torque to the output shaft, a first rotating member connected to any one of the input shaft, the first output shaft, and the second output shaft, and the input shaft A second rotating member connected to any one of the first output shaft and the second output shaft excluding the first rotating member, the first rotating member, and the second output shaft. A clutch member interposed between the rotary member, a first pressure plate that presses the clutch member from one side and that is connected to the first rotary member, and a second that presses the clutch member from the other side. A pressure plate, the first The rotating member is divided into an input-side rotating member and an output-side rotating member, and the output-side rotating member is slidable in the axial direction, and the dog is placed on the opposing surface of the input-side rotating member and the output-side rotating member. When the input torque is small, the pressing force applied to the clutch member is changed with a small inclination, and when the input torque is large, the dog engagement surface of the dog is a cam surface. It is characterized in that it is formed into a shape that changes with a large inclination.

  According to the present invention, when the input torque is small, the pressing force applied to the clutch member that executes the differential limitation is changed with a small inclination, so that the generation of unnecessary differential limiting torque can be suppressed. In addition, torque loss due to drag resistance is reduced, and when the input torque is large, the pressing force is changed with a large slope, so that a good differential limiting effect can be obtained.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 to 7 show a first embodiment of the present invention. FIG. 1 is a cross-sectional side view of the differential device along the axial direction, and FIGS. In the following, a case where the differential device 1 with the differential limiting mechanism according to the present embodiment is adopted as a so-called center differential device that distributes engine torque to the front and rear wheels will be described as an example. For the sake of convenience, the transmission torque will be described with the left side of the drawing as the front wheel (front) side and the right side as the rear wheel (rear) side.

  The differential device 1 with a differential limiting mechanism includes a planetary gear mechanism as a mechanism for absorbing the differential between the front and rear wheels. This planetary gear mechanism is accommodated in a cylindrical differential case 2. A planetary carrier 4 constituting a planetary gear mechanism is integrally formed at the base portion of the input shaft 3 protruding from the front end of the differential case 2. The input shaft 3 is coupled to an output shaft (not shown) of the transmission.

  Further, a sun gear shaft 5 as a second rotating member is disposed coaxially with the differential case 2. The front end of the sun gear shaft 5 is inserted into and supported by the input shaft 3 so as to be relatively rotatable, and is integrally coupled to a front drive shaft (not shown) as a first output shaft.

  Further, a ring gear member 6 as a first rotating member is supported on the inner periphery of the differential case 2 so as to be slidable relative to the differential case 2. The ring gear member 6 is formed in a cylindrical shape, and the opening end on the input side that opens forward is in contact with the inner surface of the planetary carrier 4 via a bearing member 7 such as a needle bearing or a washer. .

  On the other hand, a rear drive shaft 8 as a second output shaft is coaxially inserted from the rear with respect to the sun gear shaft 5, and the tip of the rear drive shaft 8 has a bearing 21 on the inner periphery of the sun gear shaft 5. The shaft is supported so as to be relatively rotatable.

  Further, a boss portion 8b projects from the rear portion of the rear drive shaft 8, and a bearing 9 is fitted to the boss portion 8b. The boss 8b is rotatably supported by a transmission case (not shown) via a bearing 9. A rear drive gear 8c formed on the rear drive shaft 8 is connected to a transfer shaft extending to the rear wheel side via a reduction gear (not shown). Is connected to the rear wheel shaft via a propeller shaft and a rear differential device.

  A wet multi-plate clutch 10 serving as a clutch member is disposed at the ends of the ring gear member 6 and the sun gear shaft 5 extending rearward. The wet multi-plate clutch 10 includes a clutch drum 20 formed at an extension portion of the ring gear member 6, a clutch hub 22 formed at an extension portion of the sun gear shaft 5, and the clutch drum 20 and the clutch hub 22. Drive plates 10a and 10b that are alternately arranged at a predetermined interval.

  Further, in the middle of the ring gear member 6, a front pressure plate 6 d as a first pressure plate is provided so as to press the alternately arranged plates 10 a and 10 b of the wet multi-plate clutch 10 from the front to the rear. A rear pressure plate 30 as a second pressure plate is opposed to the rear end surfaces of the plates 10a and 10b arranged in a predetermined manner. The outer periphery of the rear pressure plate 30 is spline-fitted to the clutch drum 20 formed on the ring gear member 6, and the boss portion 30 a is splined to the rear drive shaft 8.

  Further, a plurality of (for example, six) planetary pinion shafts 11 are arranged at equal intervals between the outer periphery of the sun gear shaft 5 and the inner periphery of the ring gear member 6, and are formed on the planetary pinion shaft 11. A planetary pinion 11 a is meshed with a sun gear 5 b formed on the sun gear shaft 5 and a ring gear 6 c formed on the ring gear member 6.

  Further, both ends of this planetary pinion shaft 11 are rotatably supported by planetary carriers 4 and 12 arranged opposite to each other via bearings. These planetary carriers 4 and 12 are integrally coupled via a connecting member at a portion that does not interfere with the planetary pinion shaft 11.

  On the other hand, the ring gear member 6 is divided into an input side ring gear member 6a as an input side rotating member and an output side ring gear member 6b as an output side rotating member. A ring gear 6c that meshes with the planetary pinion 11a is formed on the input side ring gear member 6a, and a front pressure plate 6d and a clutch drum 20 are formed on the output side ring gear member 6b.

  The output side ring gear member 6b is supported on the inner periphery of the differential case 2 and is allowed to slide in the axial direction. A dog 15 is provided between the opposing surfaces of the input side ring gear member 6a and the output side ring gear member 6b.

  As shown in FIGS. 2 and 3, the dog 15 meshes with the input side dog teeth 13 formed at regular intervals on the circumference of the end surface of the input side ring gear member 6 a and the input side dog teeth 13. Along with the output side dog gear 14 formed at regular intervals on the circumference of the end face of the output side ring gear member 6b. In the figure, the rotation direction during forward running is shown as a flow from the top to the bottom of the page.

  The tooth surface of the input-side dog tooth 13 is formed by linear cam surfaces 13a and 13b having two different cam angles. On the other hand, a curved cam receiving surface 14 a that contacts the cam surfaces 13 a and 13 b is formed on the tooth surface of the output side dog teeth 14 that mesh with the input side dog teeth 13.

  Cam angle between the first-stage cam surface 13a formed on the base side of the input-side dog tooth 13 and the cam receiving surface 14a slidably contacting the cam surface 13a (when the dog teeth 13 and 14 are unfolded) The angle (θ1) between the thrust axis of the dog tooth 14 and the tangential axis between the cam surfaces 13a, 14a is set to a relatively gentle angle, and is formed on the tooth tip side. The cam angle between the second cam surface 13b and the cam receiving surface 14a (the axis in the thrust direction of the dog teeth 14 when the dog teeth 13 and 14 are expanded and the tangential direction between the cam surfaces 13b and 14a) The angle between the shaft and the axis (θ2) is set to a relatively steep angle.

  The cam angles θ1 and θ2 are related to the input torque of the input side dog teeth 13 and the pressing force to be applied to the wet multi-plate clutch 10 via the output side ring gear member 6b connected to the output side dog teeth 14. It is obtained from experiments or simulations and set to an optimum value.

  When the input side ring gear member 6a is rotated, this rotation is transmitted to the output side ring gear member 6b via the dog teeth 13 and 14 meshing with each other. When the input torque of the input side ring gear member 6a is small, the first-stage cam surface 13a of the input side dog teeth 13 engages with the cam receiving surface 14a of the output side dog teeth 14 to thrust the output side ring gear member 6b. Press in the direction. Since the cam angle θ1 between the first stage cam surface 13a and the cam receiving surface 14a is set to a gentle angle, the cam angle moves slowly in the thrust direction in proportion to the increase in input torque. When the input torque of the input side ring gear member 6a increases, the second-stage cam surface 13b of the input side dog teeth 13 engages with the cam receiving surface 14a of the output side dog teeth 14, and the output side ring gear member 6b. Is pushed in the thrust direction. 2 and 3 show the meshing states of the dog teeth 13 and 14 during driving, and the opposite tooth surfaces are meshed during coasting.

  As a result, as indicated by a solid line in FIG. 4A, the pressing force applied to the wet multi-plate clutch 10 is low when pressed by the first stage cam surface 13a and high when pressed by the second stage cam surface 13b. Become. The characteristic indicated by the alternate long and short dash line in FIG. 3 shows the relationship between the input torque and the pressing force in a conventional linear cam in which the cam surface of the input-side dog teeth is linear. The characteristic indicated by the broken line indicates the relationship between the input torque and the pressing force when the cam surface of the second embodiment described later is a non-linear cam.

  On the other hand, an electronically controlled differential limiting device 31 is disposed behind the wet multi-plate clutch 10. The configuration of the electronically controlled differential limiting device 31 is described in detail in Japanese Patent Laid-Open No. 6-320973 previously filed by the present applicant.

  The configuration of the electronically controlled differential limiting device 31 will be briefly described. This electronically controlled differential limiting device 31 has an electromagnet 33 that accommodates an electromagnetic coil 32, and a device-side pressure in which the outer periphery of the electromagnet 33 is spline fitted to the rear end of the differential case 2 in front of the electromagnet 33. A plate 34 is opposed to each other, and a clutch plate 35 is disposed between the electromagnet 33 and the apparatus-side pressure plate 34.

  The clutch plate 35 is configured by alternately arranging a drive plate and a driven plate at a predetermined interval, and the outer periphery of the drive plate is spline-fitted to the inner periphery of the differential case 2, while the inner side of the driven plate is The circumference is spline-fitted to the clutch hub 36. Reference numeral 38 denotes a drum that supports the electromagnet 33 via a bearing. The drum 38 is rotatably supported by the rear drive shaft 8 via a bearing.

  The clutch hub 36 is externally mounted on the boss portion 30a of the rear pressure plate 30 so as to be rotatable and restricted in movement in the axial direction.

  A cam ball 37 is interposed between the clutch hub 36 and the rear pressure plate 30. A cam groove for accommodating a cam ball 37 is formed on the opposing surface of the clutch hub 36 and the rear pressure plate 30, and when a differential rotation occurs between the clutch hub 36 and the rear pressure plate 30, A cam thrust force that presses the pressure plate 30 forward is generated.

  When a control current is applied to the electromagnetic coil 32 housed in the electromagnet 33 from a control unit (not shown), the electromagnet 33 is excited and the device-side pressure plate 34 is attracted to the device-side pressure plate 34 and the electromagnet 33. The clutch plate 35 interposed therebetween is fastened with a cam thrust force corresponding to the control current value.

  The control unit sets the cam thrust force for the rear pressure plate 30 based on the values detected by sensors that detect the behavior of the vehicle, such as a wheel speed sensor that detects the rotational speed of each wheel and a longitudinal acceleration sensor. To do.

Next, the effect | action of this form by such a structure is demonstrated.
During forward travel, the drive torque that is shifted by the transmission and output from the output shaft is input to the input shaft 3 of the differential 1 that is coupled to the output shaft, and is connected to the input shaft 3. The planetary pinion shaft 11 supported by the planetary carriers 4 and 12 is revolved through the planetary carriers 4 and 12 to be provided.

  The planetary pinion 11 a formed on the planetary pinion shaft 11 is meshed with a sun gear 5 b formed on the sun gear shaft 5 and a ring gear 6 c formed on the ring gear member 6. The sun gear shaft 5 is coupled to a front drive shaft (not shown), while the output side of the ring gear member 6 is splined to the rear drive shaft 8 via a rear pressure plate 30.

  Accordingly, the drive torque output from the transmission is distributed by the planetary pinion shaft 11 between the sun gear shaft 5 side and the ring gear member 6 side according to the gear ratio between the sun gear 5b and the ring gear 6c (for example, the front wheel 4: Distributed by the rear wheels 6) and transmitted to the front and rear wheels for four-wheel drive running.

  By the way, the drive torque distributed to the input side ring gear member 6a of the ring gear member 6 by the planetary gear mechanism is transmitted to the output side ring gear member 6b. As shown in FIG. 3, between the dog teeth 13 and 14 of the dog 15 provided on the dividing surface of both, the transmission torque TF acting in the rotational direction and the axial direction are applied. And a cam thrust force TS acting on the.

  In this case, the input side end face of the input side ring gear member 6a is brought into contact with the inner side surface of the planetary carrier 4 via the bearing member 7 and is restricted from moving in the axial direction. The output-side ring gear member 6b is pushed and moved rearward by the cam thrust force TS generated at the same time.

  At this time, the cam angle θ1 between the first-stage cam surface 13a formed on the base side of the input-side dog tooth 13 and the cam receiving surface 14a is set to a gentle angle. Therefore, the cam thrust force TS generated on the cam receiving surface 14a of the output-side dog teeth 14 that is pressed in the thrust direction by the first-stage cam surface 13a is gradually increased. Therefore, as shown by a solid line in FIG. 4A, the differential limiting torque generated in the wet multi-plate clutch 10 gradually increases in response to the input torque from the input side dog teeth 13.

  In a state where the input torque applied to the input side dog teeth 13 is small, there is almost no need to limit the differential of the planetary gear mechanism. Therefore, it is unnecessary by reducing the pressing force applied to the wet multi-plate clutch 10. Generation of differential limiting torque can be suppressed, drag resistance of the wet multi-plate clutch 10 is reduced, and torque loss can be improved accordingly.

  As shown in FIG. 3, as the input torque applied to the input-side dog teeth 13 gradually increases and the cam thrust force TS generated on the output-side dog teeth 14 increases, the output-side dog teeth 14 move in the thrust direction. Further, the cam receiving surface 14a of the output side dog teeth 14 meshes with the second stage cam surface 13b formed on the tooth tip side of the input side dog teeth 13. The cam angle θ2 between the second stage cam surface 13b and the cam receiving surface 14a is set to a steep angle.

  Therefore, the cam thrust force TS generated on the cam receiving surface 14a of the output side dog teeth 14 pressed in the thrust direction by the second stage cam surface 13b is larger than the input torque applied to the output side dog teeth 14. Will change. Accordingly, as shown by a solid line in FIG. 4A, the differential limiting torque generated in the wet multi-plate clutch 10 also increases rapidly.

  In a state where the input torque applied to the input-side dog teeth 13 is large, good driving performance can be obtained by increasing the pressing force and limiting the differential of the planetary gear mechanism at an early stage. That is, when the cam thrust force TS generated in the output side ring gear member 6b increases, the front pressure plates 6d formed integrally with the output side ring gear member 6b are alternately arranged in the wet multi-plate clutch 10. The drive plate 10a and the driven plate 10b are pressed against the rear pressure plate 30, and the differential limiting torque indicated by the solid line in FIG.

  When a differential limiting torque is generated in the wet multi-plate clutch 10, an output side ring gear member 6 b that is directly connected to the rear drive shaft 8 via the rear pressure plate 30 and a clutch hub 22 that is integrally formed with the sun gear shaft 5, In the meantime, the torque path is bypassed through the wet multi-plate clutch 10.

  As a result, the wet multi-plate clutch 10 is formed between the sun gear shaft 5 and the rear drive shaft 8 connected to the front drive shaft in order from the larger rotational speeds NF and NR to the smaller one. A certain percentage of torque movement is performed via the torque path. The differential limiting torque (clutch engagement force) generated in the wet multi-plate clutch 10 can be appropriately set according to the number of plates 10a and 10b.

  On the other hand, in coasting, the driving torque from the rear wheel side is applied to the output side ring gear member 6b via the rear drive shaft 8 and the rear pressure plate 30, so that the output formed on the output side ring gear member 6b. The coast side (the upper side of FIGS. 2 and 3) is formed on the input side dog tooth 13 of the input side ring gear member 6 a with the cam receiving surface 14 a on the coast side (the lower side of FIGS. 2 and 3) of the side dog teeth 14. ) Of the cam surface 13a or 13b.

  Then, due to the reaction from the input side ring gear member 6a, the output side ring gear member 6b is pressed by the cam thrust force TS. Similarly to the above, the wet multi-plate clutch 10 has the input side dog teeth 13 in the state where the input torque is small. The wet multi-plate clutch is driven by a relatively low pressing force generated by the pressing force of the first stage cam surface 13a, and in a state where the input torque is large, by a relatively large pressing force generated by the second stage cam surface 13b. A differential limiting torque is generated at 10, and a torque path is bypassed between the rear drive shaft 8 and the sun gear shaft 5.

  As a result, a constant rate of torque movement is performed between the rear drive shaft 8 and the sun gear shaft 5 via the torque path from the larger rotational speeds NR and NF to the smaller one.

  Next, referring to FIG. 5 to FIG. 7, the transmission torque transmitted to the front wheel side (hereinafter referred to as “front wheel side transmission torque TF”) from the relationship between the front wheel side rotational speed NF and the rear wheel side rotational speed NR. Next, a change in driving torque transmitted to the rear wheel side (hereinafter referred to as “rear wheel side transmission torque TR”) will be described.

  First, when the driving torque is hardly applied, that is, for example, when the accelerator pedal is released when entering the curve in actual traveling, the dog teeth 13 and 14 of the dog 15 meshing with each other are engaged. Since the acting torque decreases, the cam thrust force TS in the axial direction decreases, and the wet multi-plate clutch 10 generates only a small differential limiting torque.

  Therefore, when turning the steering wheel when entering the curve, the planetary gear mechanism smoothly absorbs the difference in rotation between the front and rear wheels, thereby enabling smooth turning.

  Next, as shown in FIG. 5, the front wheel side rotational speed NF becomes larger than the rear wheel side rotational speed NR from the state where the front wheel side rotational speed NF and the rear wheel side rotational speed NR are equal while the driving torque is applied. In an understeering state that occurs when the vehicle is about to be driven, i.e. understeering when the accelerator pedal is depressed and accelerated after actually entering the curve, the input torque corresponding to the amount of depression of the accelerator pedal is engaged with each other. 13 and 14, the cam surface 13 a or 13 b formed on the input side dog tooth 13 of the input side ring gear member 6 a becomes the cam receiver formed on the output side dog tooth 14 of the output side ring gear member 6 b. The cam thrust force TS in the axial direction is generated to press the surface 14a, and the output side ring gear member 6b is moved backward (rightward direction in FIG. 2) by the cam thrust force TS. To be pressed and moved, adding a pressing force to the wet multi-plate clutch 10.

  Then, differential limiting torque is generated in the wet multi-plate clutch 10, and a torque path is bypassed between the sun gear shaft 5 and the rear drive shaft 8 via the wet multi-plate clutch 10, and is shown by a middle line in FIG. As indicated by the arrow, part of the driving torque input to the sun gear shaft 5 is transmitted to the rear drive shaft 8 side via the wet multi-plate clutch 10. Therefore, the rear drive shaft 8 has a drive torque (indicated by a thin line arrow) input via the ring gear member 6 and a drive torque (indicated by a medium line arrow) input from the sun gear shaft 5 described above. Is added to the transmission torque TR (indicated by a thick arrow).

  As a result, in a state such as understeering, the driving torque transmitted to the front wheels decreases, so that understeering can be suppressed and a favorable steering operation can be performed.

  Further, as shown in FIG. 6, from the state where the front wheel side rotational speed NF and the rear wheel side rotational speed NR are equal while the driving torque is applied, the rear wheel side rotational speed NR is likely to be larger than the front wheel side rotational speed NF. In a state where the rear wheel slips while accelerating on a curve, torque corresponding to the amount of depression of the accelerator pedal acts on the dog teeth 13 and 14 of the dog 15, so that the input side ring gear The cam surface 13a or 13b of the input side dog teeth 13 formed on the member 6a presses the cam receiving surface 14a formed on the output side dog teeth 14 of the output side ring gear member 6b, and the cam thrust force in the axial direction. TS occurs.

  Then, by this cam thrust force TS, the wet multi-plate clutch 10 is engaged, and a torque path is bypassed between the differential case 2 and the rear drive shaft 8, and as shown by the arrow shown by the middle line in FIG. A part of the driving torque input to the ring gear member 6b is input to the sun gear shaft 5 through the torque path.

  As a result, the sun gear shaft 5 has a driving torque (indicated by a thin line arrow) inputted from the planetary pinion shaft 11 and a driving torque (medium value) inputted from the output side ring gear member 6 b side via the wet multi-plate clutch 10. The transmission torque TF (indicated by a thick arrow) is added.

  Therefore, for example, in a state where the rear wheel slides sideways while traveling on a curve, the rear-wheel-side transmission torque TR is reduced, so that the side slip is suppressed and good traveling performance can be obtained.

  By the way, when one of the front and rear wheels slips when starting and running on a road surface of a low μ road such as a snowy road, the torque generated by running resistance (running resistance, acceleration resistance, etc.) is small. The cam thrust force TS generated when the first cam surface 13a of the dog teeth 13 presses the cam receiving surface 14a formed on the output dog teeth 14 is small, and therefore the pressing force applied to the wet multi-plate clutch 10 is small. Therefore, the differential limitation hardly acts and the grip force on the road surface is remarkably lowered.

  In such a situation, the electronically controlled differential limiting device 31 operates to actively limit the differential between the front and rear wheels. This electronically controlled differential limiting device 31 has a wheel speed sensor that detects the rotational speed (wheel speed) of each wheel, and when the wheel slip is detected by each wheel speed sensor, the wet multi-plate clutch 10 is engaged to limit the differential between the front and rear wheels.

  Then, for example, when the rear wheel is slipping (TR≈0 and NR> 0), as shown by the white arrow in FIG. Therefore, the rear wheel slip is suppressed.

  On the other hand, when the front wheels are slipping (TF≈0 and NF> 0), as shown by the hatched arrows in FIG. Since it is transmitted to the drive shaft 8 side, the slip of the front wheel is suppressed.

  As described above, in this embodiment, the region where the differential limiting torque necessary for the dog 15 cannot be generated is activated by the electronic control type differential limiting device 31 to actively limit the differential. Even when starting and running on a low μ road surface, slip is suppressed and good running performance can be obtained.

  Next, the relationship between the front wheel side rotational speed NF and the rear wheel side rotational speed NR, and the front wheel side transmission torque TF and the rear wheel side transmission torque TR will be described using the characteristic diagram shown in FIG.

  When the front wheel side rotational speed NF and the rear wheel side rotational speed NR are equal and torque transmission by the wet multi-plate clutch 10 is not performed, the torque distribution set by the planetary gear mechanism is indicated by a solid line in the center of the figure. Thus, the front wheel side transmission torque TF and the rear wheel side transmission torque TR are set.

  On the other hand, in a state where the front wheel side rotational speed NF is going to be larger than the rear wheel side rotational speed NR, the wet multi-plate clutch 10 is engaged, so that the differential is limited and transmitted to the front wheel side. A part of the driving torque is transmitted to the rear wheel side, and the rear wheel transmission torque TR increases.

  Even in a state where the rear wheel side rotational speed NR is going to be larger than the front wheel side rotational speed NF, the wet multi-plate clutch 10 is engaged, so that the differential is limited and transmitted to the rear wheel side. A part of the drive torque is transmitted to the front wheel side, and the front wheel side transmission torque TF increases.

  Further, in a region where the front wheel or the rear wheel slips beyond the limit of the engaging force of the wet multi-plate clutch 10, and a region where the front wheel side transmission torque TF and the rear wheel side transmission torque TR are small and the differential limiting force by the dog 15 is small. In the region where the front wheel or the rear wheel slips, as shown by the one-dot chain line in the figure, the operation region of the electronically controlled differential limiting device 31 is set, and the wet multi-plate clutch 10 is engaged in the region, for example, It is possible to suppress the occurrence of slip when starting and running on a low μ road surface.

  As described above, the region where the differential of the front and rear wheels cannot be limited by the dog 15 is operated on the road surface of the low μ road by operating the electronic control type differential limiting device 31 and actively limiting the differential. It is possible to suppress slipping when starting and running.

  Further, the dog 15 operates at the moment when a differential rotation is generated between the front wheel side rotational speed NF and the rear wheel side rotational speed NR, and generates a cam thrust force TS on the output side dog teeth 14 of the dog 15. Since the differential limiting torque is generated in the wet multi-plate clutch 10 by the pressing force by the cam thrust force TS, the responsiveness is better than the control operation of the electronic control type differential limiting device 31, and the electronic control type The differential limiting device 31 can supplement a region that cannot be controlled, and as a whole, good running performance can be obtained.

  Further, the cam angle between the meshing surfaces of the input-side dog teeth 13 and the output-side dog teeth 14 of the dog 15 is formed at a gentle angle with respect to the cam angle θ1 with the first-stage cam surface 13a on the tooth base side. When a two-stage cam is formed with a steep angle cam angle θ2 with the second-stage cam surface 13b on the front side, and the input torque from the input-side dog teeth 13 is small, the first-stage cam surface 13a is on the output side. The cam receiving surface 14a of the dog tooth 14 is pressed and a low pressing force is generated in the wet multi-plate clutch 10. Therefore, generation of unnecessary differential limiting torque can be suppressed. Further, drag resistance acting on the wet multi-plate clutch 10 is reduced, and torque loss can be improved. On the other hand, when the input torque increases, the second stage cam surface 13b presses the cam receiving surface 14a of the output side dog teeth 14 and generates a high pressing force on the wet multi-plate clutch 10. Can be fastened and a good differential limiting effect can be obtained.

  In this case, the pressing force applied to the wet multi-plate clutch 10 by sliding between the cam surfaces 13a, 13b formed on the input side dog teeth 13 of the dog 15 and the cam receiving surfaces 14a formed on the output side dog teeth 14 is applied. Since it is generated, a special gear is not required, manufacture becomes easy, and reduction of product cost can be realized.

  Furthermore, the pressing force for generating the differential limiting torque can be easily varied by changing the cam angles θ1 and θ2 of the cam surfaces 13a and 13b of the two-stage cam formed on the input side dog teeth 13. This pressing force can be easily set for each model.

  Further, the cam angles θ1 and θ2 formed by the cam surfaces 13a and 13b of the input side dog teeth 13 and the cam receiving surfaces 14a of the output side dog teeth 14 are meshed with a surface (lower side in FIG. 2). It is possible to set different pressure angles on the surface meshing during coasting (upper surface in FIG. 2). For example, the cam angles θ1 and θ2 of the cam surfaces 13a and 13b meshing during coasting are 0 °, that is, The differential limiting characteristic can be set freely according to the driving characteristics of each vehicle, such as setting the cam thrust force TS to 0 and not limiting the differential during coast driving, and the degree of freedom in design. Can be increased.

  Further, since the wet multi-plate clutch 10 is engaged by the dog 15 and the electronic control type differential limiting device 31, the planetary gear mechanism itself does not need to use a special gear, and is configured with a standard gear. Therefore, the product cost can be reduced.

  8 and 9 are side views of the main part of the ring gear member according to the second embodiment of the present invention. The dog 15 'shown in the present embodiment is applied in place of the dog 15 of the first embodiment, and other configurations are the same as those of the first embodiment. Therefore, the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  The dog 15 according to the first embodiment described above has the cam surfaces 13a and 13b of the input side dog teeth 13 formed by linear two-stage cams. However, the dog 15 'according to the present embodiment has a root of the input side dog teeth 13'. The first cam surface 13a 'on the side and the second cam surface 13b' on the tooth tip side are formed as non-linear cams formed by cam curves having different curvatures. The cam angles θ1 and θ2 between the cam surfaces 13a ′ and 13b ′ and the cam receiving surface 14a are formed with a gentle angle of the cam angle θ1 and a steep angle of the cam angle θ2 as in the first embodiment. Has been. The cam surfaces 13a 'and 13b are continuously formed with a smooth curve.

  In this embodiment, the cam surfaces 13a and 13b are nonlinear cams formed by cam curves having different curvatures, and the cam angles θ1 and θ2 between the cam surfaces 13a and 13b and the cam receiving surface 14a are the same as in the first embodiment. Since the cam angle θ1 is a gentle angle and the cam angle θ2 is a steep angle, not only the same effect as in the first embodiment can be obtained, but also as shown by a broken line in FIG. The increase in the applied pressing force can be smoothly transferred from the first-stage cam surface 13a to the second-stage cam surface 13b. Other functions and effects are the same as those of the first embodiment.

  The present invention is not limited to the above-described embodiments, and the cam pressures θ1 and θ2 may be set according to the shape of the cam receiving surface 14a of the output side dog teeth 14.

Sectional side view along the axial direction of the differential device with a differential limiting mechanism according to the first embodiment Same as above, side view of main part of ring gear member with low input torque Side view of main part of ring gear member with large input torque (A) Characteristic diagram showing relationship between input torque to dog and pressing force generated thereby, (b) Explanatory diagram showing characteristic of differential limiting torque FIG. 6 is an explanatory diagram showing torque transmission paths to the front and rear wheels when the driving torque acts and the front wheel side rotational speed is going to be larger than the rear wheel side rotational speed. FIG. 5 is an explanatory diagram showing torque transmission paths to the front and rear wheels when the drive torque is applied and the rear wheel rotation speed is going to be larger than the front wheel rotation speed. Explanatory drawing which shows the torque transmission path to the front and rear wheels when the differential limiting device operates Side view of main part corresponding to FIG. 2 according to the second embodiment Same side view as FIG.

Explanation of symbols

1 differential,
4,12 Planetary carrier,
5 Sun gear shaft,
6 Ring gear member,
6a input side ring gear member,
6b output side ring gear member,
10 Wet multi-plate clutch,
11 Planetary pinion shaft,
13 Input side dog teeth,
13a, 13b cam surface,
14 Output side dog teeth,
14a Cam receiving surface,
15 dogs,
22 Clutch hub,
31 Electronically controlled differential limiting device,
θ1, θ2 Cam angle,
TS Cam thrust force

Claims (3)

In a differential device that transmits driving torque from an engine to a planetary gear mechanism via an input shaft, and distributes torque to the first output shaft and the second output shaft via the planetary gear mechanism.
A first rotating member connected to any one of the input shaft, the first output shaft, and the second output shaft;
A second rotating member connected to any one of the input shaft, the first output shaft, and the second output shaft excluding the first rotating member;
A clutch member interposed between the first rotating member and the second rotating member;
A first pressure plate that presses the clutch member from one side and is connected to the first rotating member;
A second pressure plate for pressing the clutch member from the other,
While dividing the first rotating member into an input side rotating member and an output side rotating member,
The output side rotating member is slidable in the axial direction,
A dog is provided on the opposing surface of the input side rotating member and the output side rotating member, and the meshing surface of the dog is a cam surface,
The cam surface is formed in a shape that changes the pressing force applied to the clutch member with a small inclination when the input torque is small, and changes the pressing force with a large inclination when the input torque is large. A differential device with a differential limiting mechanism. 2. The differential device with a differential limiting mechanism according to claim 1, wherein the cam surface is formed in multiple stages. 2. The differential device with a differential limiting mechanism according to claim 1, wherein the cam surface is formed in a non-linear shape.

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