Differential device

Abstract

To provide a differential device capable of improving the responsiveness of an intermittent mechanism.SOLUTION: The differential device includes: a differential case rotatably arranged to which driving force is input; a differential gear rotatably supported by the differential case for revolving with the rotation of the differential case; a pair of output gears arranged in a relatively rotatable manner and engaging with the differential gear for outputting driving force to a pair of wheels; an intermittent mechanism arranged between the differential case and at least one of the pair of output gears for interrupting power transmission between the differential case and the output gear; a sensor 49 for detecting a stroke state of at least one of wheels; and a control device 47 for controlling the operation of the intermittent mechanism on the basis of a detected value detected by the sensor 49. When the detected value detected by the sensor 49 exceeds a first threshold value, the control part 47 realizes connection of the intermittent mechanism.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a differential device. [Background technology]

[0002] Conventionally, a differential device includes a differential case that is rotatably arranged and receives a driving force, and a differential gear that is rotatably supported by the differential case and revolves with the rotation of the differential case. The differential device also includes a pair of output gears that are rotatable relative to one another and mesh with the differential gears to output a driving force to a pair of wheels. The differential device also includes a clutch pack that is arranged between the differential case and at least one of the pair of output gears and serves as an interrupting mechanism for interrupting the power transmission between the differential case and the output gear. A differential device that includes a sensor that detects slippage of the pair of wheels and a control unit that controls the operation of the clutch pack based on the detection value detected by the sensor is also known (see Patent Document 1). In this differential device, when the sensor detects the occurrence of slippage of the wheels or the possibility of slippage, the control unit connects the clutch pack to prevent the wheels from slipping. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-287106 A Summary of the Invention [Problem to be solved by the invention]

[0004] Meanwhile, a vehicle to which a differential device such as that disclosed in Patent Document 1 is applied may travel on a so-called mogul road that is dotted with multiple raised and recessed parts. When a vehicle travels on a mogul road, one wheel often comes into contact with the road surface while the other wheel lifts off the road surface. In such a situation, if the control unit controls the on-off mechanism based on the differential rotation of a pair of wheels detected by a sensor, the timing of connecting the on-off mechanism may be delayed, resulting in a decrease in the responsiveness of the on-off mechanism.

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a differential device capable of improving the responsiveness of an interrupting mechanism. [Means for solving the problem]

[0006] The differential device of this embodiment includes a differential case that is rotatably arranged and to which driving force is input, a differential gear that is rotatably supported on the differential case and revolves due to the rotation of the differential case, a pair of output gears that are arranged to rotate relative to each other and mesh with the differential gear to output driving force to a pair of wheels, an interrupting mechanism that is arranged between the differential case and at least one of the pair of output gears and interrupts the power transmission between the differential case and the output gear, a sensor that detects the stroke state of at least one of the wheels, and a control unit that controls the operation of the interrupting mechanism based on the detection value detected by the sensor, and the control unit connects the interrupting mechanism when the detection value detected by the sensor exceeds a first threshold value. Effect of the Invention

[0007] Advantageous Effects of Invention According to the present invention, it is possible to provide a differential device capable of improving the responsiveness of an interrupting mechanism. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing an example of a power system of a vehicle to which a differential device according to an embodiment of the present invention is applied; [Diagram 2] 4 is a schematic diagram showing another example of a power system of a vehicle to which the differential device according to the present embodiment is applied. FIG. [Diagram 3] 4 is a schematic diagram showing another example of a power system of a vehicle to which the differential device according to the present embodiment is applied. FIG. [Figure 4] FIG. 2 is a cross-sectional view showing an example of a differential device according to the present embodiment. [Diagram 5] FIG. 4 is a cross-sectional view showing another example of a differential device according to the present embodiment. [Figure 6] 5 is a diagram showing an example of a change in the stroke amount of a wheel with respect to time in the differential device according to the embodiment. FIG. [Figure 7] 5 is a diagram showing a change in the detection value of the load sensor relative to the stroke amount of the differential device according to the embodiment. FIG. [Figure 8] FIG. 2 is a block diagram of a control unit of the differential device according to the embodiment. [Figure 9] 4 is a flowchart of a control unit of the differential device according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The differential device according to the present embodiment will be described in detail below with reference to the drawings. Note that the dimensional ratios in the drawings are exaggerated for the sake of explanation and may differ from the actual ratios.

[0010] First, an example of a power system of a vehicle to which a differential device according to this embodiment is applied will be described with reference to FIG.

[0011] As shown in FIG. 1, the power system of a vehicle is roughly divided into a main drive system for the front wheels and an auxiliary drive system for the rear wheels.

[0012] The main drive system includes an engine 201 and an electric motor 203 as a main drive source, a transmission 205 as a speed change mechanism, and a front differential 207 as a differential device that allows differential movement between the left and right wheels on the front wheel side. The main drive system also includes front axles 209, 211, front wheels 213, 215, and a generator 217 that charges a power source such as a battery or a storage battery. In the main drive system, driving force is transmitted from the engine 201 and the electric motor 203 via the transmission 205 to the front differential 207, and the driving force is distributed to the front wheels 213, 215 via the front axles 209, 211. In the main drive system, when the capacity of the power source is low, the generator 217 operates to charge the power source.

[0013] The auxiliary drive system includes an electric motor 219 as an auxiliary drive source, a rear differential 221 as a differential device that allows differential movement between the left and right rear wheels, rear axles 223, 225, and rear wheels 227, 229. In the auxiliary drive system, driving force from the electric motor 219 is transmitted to the rear differential 221, and the driving force is distributed to the rear wheels 227, 229 via the rear axles 223, 225.

[0014] In this vehicle power system, the vehicle is driven mainly by engine 201 and electric motor 203 as main drive sources, and is in a two-wheel drive state with the front wheels driven. Electric motor 219 as an auxiliary drive source distributes drive force to rear wheels 227, 229 when traveling on a rough road, for example, to put the vehicle in a four-wheel drive state with the front and rear wheels driven, and assists the traveling of the vehicle. Note that electric motor 219 as an auxiliary drive source may function as a generator to charge the power source. It is also possible to naturally assume that a power system is configured in which the main drive system on the front wheel side is arranged on the rear wheel side, and the auxiliary drive system on the rear wheel side is arranged on the front wheel side.

[0015] Next, another example of a power system of a vehicle to which the differential device according to this embodiment is applied will be described with reference to FIG.

[0016] 2, the power system of the vehicle includes a drive source 301 such as an engine or an electric motor, a transmission 303 as a speed change mechanism, and a transfer 305 that transmits the drive force from the drive source 301 to the front and rear wheels. It also includes a rear-wheel propeller shaft 307, a rear differential 309 as a differential device that allows differential movement between the left and right wheels on the rear wheel side, rear axles 311, 313, and rear wheels 315, 317. It also includes a front-wheel propeller shaft 319, a front differential 321 as a differential device that allows differential movement between the left and right wheels on the front wheel side, front axles 323, 325, and front wheels 327, 329.

[0017] In the power system of this vehicle, driving force input from a driving source 301 via a transmission 303 is transmitted to a transfer 305. The driving force transmitted to the transfer 305 is constantly transmitted to a rear differential 309 via a rear wheel-side propeller shaft 307, and the driving force is distributed to rear wheels 315, 317 via rear axles 311, 313.

[0018] On the other hand, the driving force transmitted to the transfer 305 is switched on and off by, for example, an on-off mechanism (not shown) provided in the transfer 305. When the on-off mechanism of the transfer 305 is in a connected state, the driving force is transmitted to the front differential 321 via the front-wheel propeller shaft 319, and the driving force is distributed to the front wheels 327, 329 via the front axles 323, 325, so that the vehicle is in a four-wheel drive state with the front and rear wheels being driven. When the on-off mechanism of the transfer 305 is in a disconnected state, the power transmission from the front-wheel propeller shaft 319 to the front differential 321 is cut off, and the driving force is not transmitted to the front wheels 327, 329, so that the vehicle is in a two-wheel drive state with the rear wheels being driven.

[0019] In addition, the power system of this vehicle is an FR-based vehicle in which driving force is transmitted mainly to the rear wheels, but it is not limited to this and may be a FF-based vehicle in which driving force is transmitted mainly to the front wheels.

[0020] Next, another example of a power system of a vehicle to which the differential device according to this embodiment is applied will be described with reference to FIG.

[0021] As shown in FIG. 3, the power system of a vehicle is roughly divided into a main drive system for the front wheels and an auxiliary drive system for the rear wheels.

[0022] The main drive system includes a main drive source 401 consisting of an electric motor, a speed reduction mechanism 403, a front differential 405 as a differential device that allows differential movement between the left and right wheels on the front wheel side, front axles 407, 409, and front wheels 411, 413. In the main drive system, driving force is transmitted from the main drive source 401 via the speed reduction mechanism 403 to the front differential 405, and the driving force is distributed to the front wheels 411, 413 via the front axles 407, 409.

[0023] The auxiliary drive system includes an auxiliary drive source 415 consisting of an electric motor, a speed reduction mechanism 417, a rear differential 419 as a differential device that allows differential movement between the left and right rear wheels, rear axles 421, 423, and rear wheels 425, 427. In the auxiliary drive system, driving force is transmitted from the auxiliary drive source 415 via the speed reduction mechanism 417 to the rear differential 419, and the driving force is distributed to the rear wheels 425, 427 via the rear axles 421, 423.

[0024] In this vehicle power system, the vehicle is driven mainly by the main drive source 401, resulting in a two-wheel drive state with the front wheels being driven. The auxiliary drive source 415 mainly functions as a generator to charge the power source, and when traveling on rough roads, for example, functions as a drive source to put the vehicle in a four-wheel drive state with the front and rear wheels being driven, thereby assisting the traveling of the vehicle.

[0025] In the power system of a vehicle as shown in Figures 1 to 3, the differential device applied to the front differential and the rear differential has an on-off mechanism that controls the differential movement of a pair of left and right wheels. When connected, the on-off mechanism limits the differential movement of the pair of wheels, preventing wheel slippage and improving the vehicle's ability to travel on rough roads.

[0026] First, an example of a differential device 1 according to this embodiment will be described with reference to FIG.

[0027] As shown in FIG. 4, the differential device 1 includes a differential mechanism 3 and a disconnecting mechanism 5.

[0028] The differential mechanism 3 includes a differential case 7, a pinion shaft 9, a differential gear 11, and a pair of output gears 13 and 15.

[0029] The differential case 7 is rotatably supported by a stationary member (not shown) such as a carrier via bearings (not shown) at the outer periphery of each of bosses 17, 19 formed on both axial sides. The differential case 7 is formed with a flange portion 21 to which a power transmission member (not shown) such as a ring gear is fixed. The power transmission member fixed to the flange portion 21 meshes with, for example, a power transmission gear (not shown) that transmits driving force from a drive source, and the driving force is input to rotate the differential case 7. The differential case 7 accommodates a pinion shaft 9, a differential gear 11, a pair of output gears 13, 15, and the like.

[0030] The pinion shaft 9 has one long pinion shaft and two short pinion shafts. Both ends of the long pinion shaft are engaged with holes in the differential case 7 to prevent it from coming off, and the long pinion shaft is rotated and driven together with the differential case 7. One end of the short pinion shaft is engaged with a hole formed in the middle of the long pinion shaft, and the other end is engaged with holes in the differential case 7 to prevent it from coming off, and the short pinion shaft is rotated and driven together with the differential case 7. Differential gears 11 are supported on the outer end side of the pinion shaft 9. The long pinion shaft and the two short pinion shafts are each prevented from coming off and from rotating by fixing means such as a rod-shaped pin (not shown) to the differential case 7.

[0031] A plurality of differential gears 11 (four in this example) are arranged at equal intervals in the circumferential direction of the differential case 7. Each of the differential gears 11 is supported on the end side of the pinion shaft 9 and revolves with the rotation of the differential case 7. The differential gear 11 is rotatably supported by the pinion shaft 9 so as to be rotationally driven when a differential rotation occurs between a pair of meshed output gears 13, 15. The differential gear 11 transmits the driving force input to the differential case 7 to the pair of output gears 13, 15.

[0032] The pair of output gears 13, 15 are accommodated in the differential case 7 so as to be capable of relative rotation. The pair of output gears 13, 15 are each meshed with the differential gear 11. On the inner circumferential side of the pair of output gears 13, 15, spline-shaped output sections 23, 25 that output the driving force transmitted to the pair of output gears 13, 15 are provided. A pair of output shafts (not shown) connected to a pair of left and right wheels so as to be capable of integrally rotating are connected to the output sections 23, 25 so as to be integrally rotatable with the pair of output gears 13, 15.

[0033] Driving force from a driving source is input to the differential case 7 via a power transmission member. The driving force input to the differential case 7 is transmitted to a pair of output gears 13, 15 via a differential gear 11 of the differential mechanism 3. The driving force transmitted to the pair of output gears 13, 15 is distributed and output to a pair of left and right wheels via a pair of output shafts. The differential rotation in the differential mechanism 3 is on-off controlled by an on-off mechanism 5.

[0034] The on-off mechanism 5 includes a multi-plate clutch 27 and an actuator 29 .

[0035] The multi-plate clutch 27 is disposed radially between the differential case 7 and one of the output gears 15. The multi-plate clutch 27 includes a plurality of outer clutch plates and a plurality of inner clutch plates.

[0036] The multiple outer clutch plates are engaged with a spline-shaped engagement portion formed on the inner periphery of the differential case 7 so as to be movable in the axial direction and rotate integrally with the differential case 7. The multiple inner clutch plates are arranged alternately in the axial direction with the multiple outer clutch plates, and are engaged with a spline-shaped engagement portion formed on the outer periphery of a boss portion of the output gear 15 so as to be movable in the axial direction and rotate integrally with the output gear 15.

[0037] The multi-plate clutch 27 is a friction clutch consisting of multiple clutch plates that are controllable with sliding friction and can intermediately control the transmission torque. The multi-plate clutch 27 connects the differential case 7 and the output gear 15 according to the amount of engagement, and limits the differential in the differential mechanism 3. The multi-plate clutch 27 is pressed in the axial direction by an actuator 29 to be engaged.

[0038] The actuator 29 includes a cam mechanism 31, a pressing member 33, and an electric motor (not shown).

[0039] The cam mechanism 31 includes a moving member 35 , a rotating member 37 , and a cam ball 39 .

[0040] The moving member 35 is formed in an annular shape and is disposed on the outer periphery of the boss portion 19 of the differential case 7. The moving member 35 is prevented from rotating with respect to a stationary member (not shown) such as a fixed member fixed to a carrier, and is disposed so as to be movable in the axial direction. The moving member 35 has a plurality of cam surfaces formed in the circumferential direction on an opposing surface that faces the rotating member 37 in the axial direction.

[0041] The rotating member 37 is formed in an annular shape and is disposed adjacent to the moving member 35 on the outer periphery of the boss portion 19 of the differential case 7. The rotating member 37 is disposed rotatably via a bearing, and the bearing restricts the axially outward movement of the rotating member 37. A gear portion is formed on the outer periphery of the rotating member 37. The rotating member 37 has a surface facing the moving member 35 in the axial direction, on which a plurality of cam surfaces are formed in the circumferential direction, the cam surfaces having the same inclination as the moving member 35.

[0042] A plurality of cam balls 39 are rotatably held by an annular holding member 41 that is disposed axially between the moving member 35 and the rotating member 37. The plurality of cam balls 39 are interposed between the cam surfaces of the moving member 35 and the rotating member 37. When the rotating member 37 rotates, a relative differential rotation occurs between the moving member 35 and the rotating member 37, and the cam balls 39 generate a cam thrust force that moves the moving member 35 axially toward the multi-plate clutch 27 side.

[0043] The pressing member 33 is formed in an annular shape and is disposed adjacent to the moving member 35 via a thrust bearing on the outer periphery of the boss portion 19 of the differential case 7. The pressing member 33 is disposed so as to be movable in the axial direction by the axial movement of the moving member 35. The pressing member 33 is provided with a plurality of pressing portions 43 which are inserted through a plurality of holes formed in the differential case 7 and press the multi-plate clutch 27. An annular return spring 45 is disposed between the pressing member 33 and the differential case 7 in the axial direction to bias the pressing member 33 in the direction of releasing the engagement of the multi-plate clutch 27. The pressing member 33 is moved axially toward the multi-plate clutch 27 by the cam thrust force generated by the cam mechanism 31, and presses the multi-plate clutch 27 via the pressing portions 43 to engage the multi-plate clutch 27.

[0044] The electric motor is fixed to a stationary member (not shown), such as a fixed member fixed to a carrier. The motor shaft of the electric motor meshes with gear portions of a gear mechanism (not shown) consisting of a plurality of gear portions arranged between the electric motor and a rotating member 37. The electric motor rotates the rotating member 37 via the gear mechanism by the rotation of the motor shaft. The rotation of the rotating member 37 generates a cam thrust force in the cam mechanism 31.

[0045] In the actuator 29, the electric motor is electrically connected to a control unit 47 (described later) that controls the operation of each mechanism of the vehicle. The control unit 47 controls the supply of electricity to the electric motor of the actuator 29 in accordance with the engagement torque to be applied to the multi-plate clutch 27. The operation of the actuator 29 engages the multi-plate clutch 27, and the differential movement of the pair of output gears 13, 15 is limited.

[0046] Next, another example of the differential device 101 according to the present embodiment will be described with reference to FIG.

[0047] As shown in FIG. 5, the differential device 101 includes a differential mechanism 103 and an on-off mechanism 105 .

[0048] The differential mechanism 103 includes a differential case 107 , a pinion shaft 109 , a differential gear 111 , and a pair of output gears 113 and 115 .

[0049] The differential case 107 is rotatably supported by a stationary member 125 such as a carrier via bearings 121, 123 at the outer periphery of each of bosses 117, 119 formed on both axial sides. The differential case 107 is formed with a flange portion 127 to which a power transmission member (not shown) such as a ring gear is fixed. The power transmission member fixed to the flange portion 127 meshes with, for example, a power transmission gear (not shown) that transmits a driving force from a driving source, and the driving force is input to rotate the differential case 107. The differential case 107 accommodates a pinion shaft 109, a differential gear 111, a pair of output gears 113, 115, and the like.

[0050] The pinion shaft 109 has one long pinion shaft and two short pinion shafts. The long pinion shaft is engaged at both ends with holes in the differential case 107 to prevent it from coming off, and is rotated integrally with the differential case 107. The short pinion shaft has one end engaged with a hole formed in the middle of the long pinion shaft, and the other end engaged with a hole in the differential case 107 to prevent it from coming off, and is rotated integrally with the differential case 107. Differential gears 111 are supported on the outer end side of the pinion shaft 109. The one long pinion shaft and the two short pinion shafts are prevented from coming off and from rotating by fixing the short pinion shafts to the differential case 107 with pins.

[0051] A plurality of differential gears 111 (four in this example) are arranged at equal intervals in the circumferential direction of the differential case 107. Each of the differential gears 111 is supported on the end side of the pinion shaft 109 and revolves with the rotation of the differential case 107. The differential gear 111 is rotatably supported by the pinion shaft 109 so as to be rotationally driven when a differential rotation occurs between a pair of meshed output gears 113, 115. The differential gear 111 transmits the driving force input to the differential case 107 to the pair of output gears 113, 115.

[0052] The pair of output gears 113, 115 are accommodated in the differential case 107 so as to be capable of relative rotation. The pair of output gears 113, 115 are each meshed with the differential gear 111. On the inner circumferential side of the pair of output gears 113, 115, spline-shaped output portions 129, 131 that output the driving force transmitted to the pair of output gears 113, 115 are provided. A pair of output shafts (not shown) connected to a pair of left and right wheels so as to be capable of integrally rotating are coupled to the pair of output gears 113, 115 in the output portions 129, 131 so as to be integrally rotatable with the pair of output gears 113, 115.

[0053] Driving force from a driving source is input to a differential case 107 via a power transmission member. The driving force input to the differential case 107 is transmitted to a pair of output gears 113, 115 via a differential gear 111 of a differential mechanism 103. The driving force transmitted to the pair of output gears 113, 115 is distributed and output to a pair of left and right wheels via a pair of output shafts. The differential rotation in the differential mechanism 103 is on-off controlled by an on-off mechanism 105.

[0054] The interrupting mechanism 105 includes an interrupting member 133 , an interrupting portion 135 , and an actuator 137 .

[0055] The interrupter member 133 is formed in an annular shape, and a base portion formed of a single circumferentially continuous member is disposed axially movable between a wall portion 139 of the differential case 107 and the back side of the output gear 115. An engagement portion 141 is provided on the wall portion 139 side of the differential case 107 of the interrupter member 133, and an interrupter portion 135 is provided on the back side of the output gear 115 of the interrupter member 133.

[0056] The engagement portion 141 is composed of a plurality of protrusions provided at equal intervals in the circumferential direction on the base of the interrupter member 133, and a plurality of holes provided at equal intervals in the circumferential direction and penetrating in the axial direction in a wall portion 139 of the differential case 107. By engaging the protrusions and the holes in the rotational direction, the interrupter member 133 is prevented from rotating with respect to the differential case 107, and the interrupter member 133 and the differential case 107 can rotate integrally.

[0057] The engaging portion 141 is provided with a cam that moves the interrupting member 133 in the connecting direction of the interrupting portion 135. The cam has cam surfaces of the same inclination formed on opposing surfaces on both circumferential sides of the convex portion and the hole portion. When the interrupting member 133 is moved in the connecting direction of the interrupting portion 135 and an engagement action in the rotational direction occurs in the interrupting portion 135, the cam surfaces of the cams are engaged by the rotation of the differential case 107. The engagement of the cam surfaces causes the interrupting member 133 to move further in the engaging direction of the interrupting portion 135, strengthening the connection of the interrupting portion 135.

[0058] The interrupting portion 135 is provided axially between the interrupting member 133 and the back side of the output gear 115 on a side surface of the base of the interrupting member 133 opposite to the engaging portion 141 in the axial direction. The interrupting portion 135 is a meshing clutch consisting of meshing teeth formed in the circumferential direction on each of the interrupting member 133 and the output gear 115 that mesh with each other. When the meshing teeth of the interrupting portion 135 mesh with each other, the interrupting member 133 and the output gear 115 are connected to be rotatable together, that is, the differential case 107 and the output gear 115 are connected to be rotatable together, and the differential of the differential mechanism 103 is locked.

[0059] Meanwhile, a biasing member 143 is provided radially inside the interrupting portion 135, between the axial direction of the interrupting member 133 and the back side of the output gear 115, and constantly biases the interrupting member 133 in the direction of disconnecting the interrupting portion 135. The biasing member 143 moves the interrupting member 133 in the direction of disconnecting the interrupting portion 135, disconnecting the interrupting portion 135, and the differential of the differential mechanism 103 becomes an unlocked state.

[0060] In a differential lock state of the differential mechanism 103 with the interrupting unit 135 connected, the driving force transmitted to the pair of output gears 113, 115 is output evenly to the pair of left and right wheels. In this way, the differential device 101 having the interrupting mechanism 105 that locks the differential of the differential mechanism 103 is a differential device having a so-called differential lock function. The interrupting state of the interrupting unit 135 is controlled by an actuator 137.

[0061] The actuator 137 includes a movable member 145 and an electromagnet 147 .

[0062] The movable member 145 is disposed on the outer periphery of the boss portion 119 of the differential case 107 on the inner diameter side of the electromagnet 147 so as to be movable in the axial direction, and includes an annular plunger 149 and a ring member 151 .

[0063] Plunger 149 is made of a magnetic material and is disposed on the inner diameter side of electromagnet 147 with an air gap, which is a minute gap set to allow magnetic flux to pass therethrough.

[0064] The ring member 151 is made of a non-magnetic material and is fixed integrally to the inner diameter side of the plunger 149, preventing leakage of magnetic flux from the inner circumferential side of the plunger 149 to the differential case 107 side. The ring member 151 is arranged on the outer periphery of the boss portion 119 of the differential case 107 so as to be movable in the axial direction, and its movement outward in the axial direction is restricted by a restricting member 153 made of a non-magnetic material that is press-fitted and fixed to the outer periphery of the boss portion 119 of the differential case 107. The ring member 151 is provided on an axial end face on the interrupter member 133 side with a pressing portion 155 that can abut against a convex portion of the interrupter member 133. The pressing portion 155 transmits the axial moving operation force of the movable member 145 operated by the electromagnet 147 to the interrupter member 133 via the pressing portion 155, and presses the interrupter member 133 in the connection direction of the interrupter member 135.

[0065] The electromagnet 147 is disposed axially adjacent to a wall portion 139 of the differential case 107 on the outer circumferential side of the boss portion 119 of the differential case 107. A rotation stopper 157 is fixed integrally to the electromagnet 147, and is prevented from rotating by engaging the rotation stopper 157 with the stationary system member 125. The electromagnet 147 includes an electromagnetic coil 159 and a core 161.

[0066] The electromagnetic coil 159 is wound in an annular shape with a predetermined number of turns and molded with resin. A lead wire drawn out from the core 161 is electrically connected to the electromagnetic coil 159, and an end of the lead wire drawn out from the core 161 is electrically connected to a connector 163. The connector 163 is electrically connected to the control unit 47 described later, and the supply of electricity to the electromagnet 147 is controlled.

[0067] The core 161 is made of a magnetic material so that a magnetic field is generated by energizing the electromagnetic coil 159, and has a predetermined magnetic path cross-sectional area. The core 161 covers the inner and outer peripheral surfaces of the electromagnetic coil 159 and one axial end face of the electromagnetic coil 159 located opposite the wall portion 139 of the differential case 107 in an annular shape. On the outer diameter side of the core 161, an extension portion 165 extending in the axial direction from the wall portion 139 of the differential case 107 is arranged so as to cover the outer diameter side of the core 161 with a sliding contact surface set to be permeable to magnetic flux. The axial end face of the extension portion 165 is arranged so as to be able to abut against a convex portion provided on the outer diameter of the core 161, and is positioned axially inward of the electromagnet 147. The axially outer end face of the core 161 is positioned axially outward of the electromagnet 147 together with the movable member 145 by a restricting member 153 that restricts the movement of the movable member 145 outward in the axial direction.

[0068] In such an actuator 137, the shortest magnetic flux loop is formed by the magnetic flux penetrating the core 161, the plunger 149, and the wall portion 139 of the differential case 107 by energizing the electromagnet 147 controlled by the control unit 47. The formed magnetic flux loop moves the plunger 149 toward the interrupter 133, and the ring member 151 presses the interrupter 133 via the pressing portion 155. By the pressing operation of the interrupter 133 by the movable member 145, the interrupter 133 is moved in the connection direction of the interrupter 135 against the biasing force of the biasing member 143, and the interrupter 135 is connected. By the connection of the interrupter 135, the output gear 115 and the interrupter 133 are connected to be able to rotate together, and the output gear 115 and the differential case 107 are connected, so that the differential mechanism 103 is in a locked state.

[0069] On the other hand, when disconnecting the interrupting unit 135, the control unit 47 stops energizing the electromagnet 147, and the biasing force of the biasing member 143 moves the interrupting member 133 in the direction of disconnecting the interrupting unit 135, thereby disconnecting the interrupting unit 135. By disconnecting the interrupting unit 135, the output gear 115 and the interrupting member 133 become relatively rotatable, and the output gear 115 and the differential case 107 become relatively rotatable, and the locked state of the differential mechanism 103 is released.

[0070] Here, an annular detection member 167 is fixed to the axial end face of the convex portion of the interrupter 133 via a bolt so as to be movable axially integrally with the interrupter 133. The detection member 167 is disposed outside the differential case 107 via a through hole formed such that the outer diameter side of the detection member 167 penetrates radially through a wall portion 139 of the differential case 107.

[0071] A portion of the detection member 167 located outside the differential case 107 is arranged so as to be engageable with a detection portion of a position switch 169 fixed to the stationary system member 125. The position switch 169 is electrically connected to the control unit 47, which will be described later. The position switch 169 detects the axial position of the detection member 167, and detects the axial position of the interrupter member 133 that moves integrally with the detection member 167. By determining the axial position of the interrupter member 133 with the position switch 169, it is possible to determine whether the interrupter 135 is in a connected state, and therefore whether the differential mechanism 103 is in a locked state.

[0072] The actuator 29 of the differential 1 and the actuator 137 of the differential 101 are electrically connected to the control unit 47, and their operations are controlled by the control unit 47. As shown in Figs. 1 to 3, when the control unit 47 is electrically connected to the electric motor of the actuator 29, the control unit 47 controls the supply of electricity to the electric motor. When the control unit 47 is electrically connected to the electromagnet 147 of the actuator 137, the control unit 47 controls the supply of electricity to the electromagnet 147.

[0073] The control unit 47 can receive information from, for example, an accelerator sensor that detects the accelerator state, a rotation sensor that detects the rotation of the axle and wheels, a drive sensor that detects the state of the drive source and transmission, and a vehicle speed sensor. Note that the vehicle speed may be detected directly from the vehicle speed sensor, but the vehicle speed may also be calculated based on the rotation detected by rotation sensors provided on the front, rear, left and right wheels.

[0074] In addition to the various sensors described above, the control unit 47 can receive information from, for example, a torque sensor that detects input torque from a drive source, an acceleration sensor that detects the gradient state of the vehicle, and a brake sensor that detects the brake status. The gradient state of the vehicle may be detected from the acceleration sensor, but a stroke sensor (also called a height sensor) and a load sensor (also called a load cell or pressure sensor) are used to detect the stroke state of the wheels and grasp the inclination of the vehicle. In addition, the gradient state of the vehicle may be detected using altitude information from GPS, road information estimated from map information, values ​​learned by AI from camera images, and the like. An ultrasonic sensor or a laser sensor may also be used to detect the stroke state of the wheels.

[0075] In addition to the various sensors described above, the control unit 47 can receive information from, for example, a grip limit sensor, a left / right wheel difference rotation sensor, a lateral inclination sensor that detects the lateral inclination state of the vehicle, a lateral acceleration sensor that detects the lateral acceleration of the vehicle, etc. In addition to the various sensors described above, the control unit 47 can receive information from, for example, an acceleration / deceleration feel sensor, a steering angle sensor, a front / rear wheel difference rotation sensor, a yaw moment sensor, an oil temperature sensor, an outside air temperature sensor, etc.

[0076] The control unit 47, which can receive information from various sensors, can select the necessary sensor information, perform calculations, or compare it with a record chart, and output control information to each mechanism installed in the vehicle to control the operation of each mechanism.

[0077] Here, in the conventional control unit, the operation of the actuator 29, 137 is controlled based on the occurrence or prediction of a differential rotation between a pair of left and right wheels, for example, using a left-right wheel differential rotation sensor, etc. However, in the control by the conventional control unit, the timing of activating the actuator 29, 137 may be delayed when traveling on a so-called mogul road with multiple raised and depressed parts.

[0078] Therefore, the control unit 47 controls the operation of the actuators 29, 137 based on the stroke state of the wheels. As shown in Figs. 1 to 3, sensors 49 for detecting the stroke state of the wheels are arranged in the vicinity of all the wheels. The sensors 49 are electrically connected to the control unit 47. Examples of the sensors 49 include the above-mentioned sensors, such as stroke sensors, load sensors, ultrasonic sensors, and laser sensors, which detect the stroke state of the wheels to be electrically measured. As a specific example of the sensor 49, a magnetostrictive type (linear displacement) using the magnetostrictive phenomenon from the magnetic field of a current pulse and the magnetic field of a magnet can be used. As another example, a conversion output type can be used in which the magnetic field density detected by a Hall IC according to the stroke position is converted into an electric signal inside the IC. As another example, a phase difference distance type or pulse propagation type that measures the distance by measuring the time until the reflected light of the irradiated light is received, a piezoelectric element type that utilizes the change in the piezoelectric effect during the stroke, and the like can be used. The control unit 47 controls the energization of the actuators 29, 137 based on the detection value detected by the sensor 49.

[0079] Here, the control unit 47 can control the operation of the actuators 29, 137 using the above-mentioned sensors in the same manner as the conventional control unit, such as by using a second sensor that functions in addition to the sensor that detects the stroke state of the wheels, such as detecting the differential rotation of a pair of wheels. That is, the control unit 47 determines the optimal amount of electricity to the actuators 29, 137 from all the sensor information. Therefore, the control performed by the control unit 47 based on the detection value of the sensor 49 constitutes a part of the operation control of the actuators 29, 137 by the control unit 47. By the control unit 47 performing control based on all the sensor information, the connection state of the on-off mechanism 5, 105 is optimized by the control of the control unit 47, and the running stability of the vehicle can be improved. The control based on the detection value of the sensor 49 by the control unit 47 will be described below.

[0080] First, a stroke sensor (sensor 49) is used as a specific embodiment for detecting the stroke state of the wheel. For example, since there are left and right wheels 213, 215 in FIG. 1, a stroke sensor (sensor 49) is disposed on each of the left and right wheels. FIG. 6 shows an example of the change in stroke amount applied to one of the left and right wheels over time. In FIG. 6, when the stroke amount increases, there is less contact between the wheel and the road surface. On the other hand, in FIG. 6, when the stroke amount decreases, there is more contact between the wheel and the road surface. For this reason, FIG. 6 shows that when the stroke amount increases, there is a high possibility that the wheel will slip.

[0081] Next, as another specific embodiment for detecting the stroke state of the wheel, a load sensor (sensor 49) is used. Fig. 7 shows the change in the detection value of sensor 49 relative to the stroke amount. As shown in Fig. 7, sensor 49 outputs a detection value that increases linearly with an increase in the stroke amount. For this reason, if the detection value output by sensor 49 increases, there is a high possibility that the wheel will slip, and if the detection value decreases, there is a low possibility that the wheel will slip.

[0082] As shown in Figs. 6 and 7, the control unit 47 has a first threshold value 51 and a second threshold value 53 for the detection value detected by the sensor 49. The first threshold value 51 is set at a high detection value position where the possibility of wheel slippage is high in the change in the detection value of the sensor 49. Therefore, when the detection value of the sensor 49 exceeds the first threshold value 51, it can be considered that the wheel is slipping. The second threshold value 53 is set at a low detection value position where the possibility of wheel slippage is low in the change in the detection value of the sensor 49, which is lower than the first threshold value 51. Therefore, when the detection value of the sensor 49 falls below the second threshold value 53, the possibility of wheel slippage is nonexistent or extremely low.

[0083] As shown in FIG. 8, the control unit 47 includes a connection start determination unit 55 and a connection release determination unit 57.

[0084] The connection start determination unit 55 determines whether the detection value of the sensor 49 exceeds the first threshold value 51. At this time, the connection start determination unit 55 concurrently determines whether the time during which the detection value of the sensor 49 exceeds the first threshold value 51 has elapsed for a predetermined time. When the control unit 47 determines that the detection value of the sensor 49 exceeds the first threshold value 51 for the predetermined time, it energizes the actuator 29, 137 with a control value (or a control amount) for obtaining a differential limiting force that is assumed to be appropriate when one of the left and right wheels slips. By energizing the actuator 29, 137, the on-off mechanism 5, 105 is in a connected state, the differential of the differential mechanism 3, 103 is limited, and slip of the pair of wheels can be prevented. Note that, when the connection start determination unit 55 determines that the detection value of the sensor 49 does not exceed the first threshold value 51, the control unit 47 controls the energization of the actuator 29, 137 based on the second sensor information.

[0085] The disconnection determination unit 57 determines whether or not the detection value of the sensor 49 is below the second threshold value 53 in the connected state of the on-off mechanism 5, 105. At this time, the disconnection determination unit 57 concurrently determines whether or not the time during which the detection value of the sensor 49 is below the second threshold value 53 has elapsed a predetermined time. When the control unit 47 determines that the detection value of the sensor 49 is below the second threshold value 53, it stops the supply of electricity to the actuators 29, 137 for a control value (also called a control amount) for obtaining a differential limiting force assumed when one of the left and right wheels slips. By stopping the supply of electricity to the actuators 29, 137, the on-off mechanism 5, 105 is in a disconnected state, and the differential limiting of the differential mechanism 3, 103 is released. At this time, when it is necessary to limit the differential of the differential mechanism 3, 103 based on the second sensor information, the control unit 47 controls the supply of electricity to the actuators 29, 137 based on the second sensor information.

[0086] Such control in the control unit 47 is shown in the flowchart of Fig. 9. As shown in Fig. 9, first, the control unit 47 judges whether or not the detection value of the sensor 49 exceeds the first threshold value 51 during a predetermined time (S1). If the detection value of the sensor 49 does not exceed the first threshold value 51 during the predetermined time (No), the control unit 47 controls the actuators 29, 137 based on the second sensor information (S2). If the detection value of the sensor 49 exceeds the first threshold value 51 during the predetermined time (Yes), the control unit 47 controls the actuators 29, 137 based on the detection value of the sensor 49 and connects the on-off mechanism 5, 105 (S3).

[0087] Next, in the connected state of the on-off mechanism 5, 105, the control unit 47 determines whether or not the detection value of the sensor 49 falls below the second threshold 53 for a predetermined time (S4). If the detection value of the sensor 49 does not fall below the second threshold 53 for the predetermined time (No), the control unit 47 controls the actuator 29, 137 based on the detection value of the sensor 49 to connect the on-off mechanism 5, 105 (S3). If the detection value of the sensor 49 falls below the second threshold 53 for the predetermined time (Yes), the control unit 47 controls the actuator 29, 137 based on the detection value of the sensor 49 to disconnect the on-off mechanism 5, 105 (S5).

[0088] In this way, the control unit 47 can control the on-off state of the on-off mechanism 5,105 based on the stroke state of at least one of the pair of wheels. Therefore, the timing of on-off of the on-off mechanism 5,105 can be quickly adjusted in response to the direct contact state between the wheel and the road surface. The control unit 47 connects the on-off mechanism 5,105 when the detection value detected by the sensor 49 exceeds the first threshold value 51. Therefore, the timing of connecting the on-off mechanism 5,105 can be quickly adjusted to the contact state between the wheel and the road surface in which the wheel is likely to slip. When the detection value detected by the sensor 49 exceeds the first threshold value 51 and the on-off mechanism 5,105 is in the connected state, the control unit 47 disconnects the on-off mechanism 5,105 when the detection value detected by the sensor 49 is the second threshold value 53 below the first threshold value 51. Therefore, the timing of disconnecting the on-off mechanism 5,105 can be quickly adjusted to the contact state between the wheel and the road surface in which the wheel is unlikely to slip.

[0089] In the following, the control unit 47 will be described as being applied to the differential device 1, but the same effect can be obtained even if the control unit 47 is applied to a left and right wheel drive device that does not have a differential device 101, and therefore the description will be omitted.

[0090] Such a differential device 1 includes a differential case 7 that is rotatably arranged and to which a driving force is input, and a differential gear 11 that is rotatably supported by the differential case 7 and revolves by the rotation of the differential case 7. The differential device 1 also includes a pair of output gears 13, 15 that are rotatable relative to one another and mesh with the differential gear 11 to output a driving force to a pair of wheels. The differential device 1 also includes an on-off mechanism 5 that is arranged between the differential case 7 and at least one of the pair of output gears 13, 15 and that interrupts the power transmission between the differential case 7 and the output gear 15. The differential device 1 also includes a sensor 49 that detects the stroke state of at least one of the pair of wheels, and a control unit 47 that controls the operation of the on-off mechanism 5 based on the detection value detected by the sensor 49. The control unit 47 connects the on-off mechanism 5 when the detection value detected by the sensor 49 exceeds a first threshold value 51.

[0091] The control unit 47 controls the operation of the on-off mechanism 5 based on the detection value of the sensor 49 that detects the stroke state of the wheel. Therefore, the timing of on-off of the on-off mechanism 5 can be quickly adjusted in response to the direct contact state between the wheel and the road surface. Furthermore, the control unit 47 connects the on-off mechanism 5 when the detection value detected by the sensor 49 exceeds the first threshold value 51. Therefore, the timing of connecting the on-off mechanism 5 can be quickly adjusted in response to the contact state between the wheel and the road surface in which there is a high possibility of the wheel slipping.

[0092] Therefore, in such a differential device 1, the responsiveness of the on-off mechanism 5 can be improved.

[0093] In addition, when the detection value exceeds the first threshold value 51 and the on-off mechanism 5 is in a connected state, the control unit 47 disconnects the on-off mechanism 5 when the detection value is at a second threshold value 53 that is lower than the first threshold value 51.

[0094] Therefore, the timing to release the connection of the disconnecting mechanism 5 can be quickly adapted to a contact state between the wheel and the road surface where the possibility of the wheel slipping is low.

[0095] Moreover, the sensor 49 is a stroke sensor.

[0096] Therefore, the timing of engaging and disengaging the engaging mechanism 5 can be quickly adjusted in response to the state of direct contact between the wheel and the road surface.

[0097] The sensor 49 is a load sensor.

[0098] Therefore, the timing of engaging and disengaging the engaging mechanism 5 can be quickly adjusted in response to the state of direct contact between the wheel and the road surface.

[0099] Further, the on-off mechanism 5 has the control amount of the on-off state controlled together with the information of the second sensor inputted to the control unit 47.

[0100] Therefore, the connection state in the on-off mechanism 5 is optimized by the control of the control unit 47, and the running stability of the vehicle can be improved.

[0101] Although the present embodiment has been described above, the present embodiment is not limited to this, and various modifications are possible within the scope of the gist of the present embodiment.

[0102] For example, the multi-plate clutch is disposed between the differential case and one of the output gears, but this is not limiting, and a pair of multi-plate clutches may be disposed between the differential case and a pair of output gears.

[0103] Further, the actuator is an electric motor actuator or an electromagnetic actuator, but is not limited to this and may be, for example, a hydraulic actuator.

[0104] In addition, sensors for detecting the stroke state of the wheels may be provided on both the left and right wheels, or in order to achieve stable control for the front and rear, sensors may be provided on both the left and right, front and rear wheels.

[0105] Furthermore, when this embodiment is applied to a suspension device of an axle that functions as a rigid left and right wheel, a sensor can be provided on either the left or right wheel to detect the stroke state of one of the wheels and estimate the stroke state of the other wheel, thereby appropriately controlling the interrupting mechanism.

[0106] In addition, the sensor, which is a component of this embodiment, is not limited to detecting the direct stroke state of the wheel as long as it has a function of detecting the stroke amount of the wheel. For example, the sensor may detect the stroke state of a mounting arm, a spring, a damper, a hub, a suspension, an axle, or the like that is in the same operating state as the wheel. [Explanation of symbols]

[0107] 1,101 Differential device 5,105 Intermittent mechanism 7,107 Differential case 11,111 Differential gear 13,15,113,115 Output gear 47 Control Unit 49 Sensors 51 First Threshold 53 Second Threshold

Claims

1. A differential case that is rotatably disposed and to which driving force is input; A differential gear that is rotatably supported by the differential case and revolves with the rotation of the differential case; a pair of output gears arranged to be capable of rotating relative to one another and meshing with the differential gear to output driving force to a pair of wheels; an interrupting mechanism disposed between the differential case and at least one of the pair of output gears, for interrupting power transmission between the differential case and the output gear; a sensor for detecting a stroke state of at least one of the wheels; A control unit that controls the operation of the on-off mechanism based on a detection value detected by the sensor; Equipped with The control unit is a differential device that connects the disconnecting mechanism when a detection value detected by the sensor exceeds a first threshold value.

2. 2. The differential device according to claim 1, wherein when the detection value exceeds the first threshold value and the disconnecting mechanism is in a connected state, the control unit disconnects the disconnecting mechanism when the detection value is a second threshold value that is lower than the first threshold value.

3. 3. The differential device according to claim 1, wherein the sensor is a stroke sensor.

4. 3. The differential device according to claim 1, wherein the sensor is a load sensor.

5. 3. The differential device according to claim 1, wherein a control amount of the on-off mechanism is controlled together with information from a second sensor input to the control unit.

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