JP2014037168A - Driving force distribution device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving force distribution device capable of saving power consumption when holding a rotational angle of a crank shaft.SOLUTION: When a crank shaft rotational angle θ reaches a rotational angle target value tθ, an inter-roller radial direction pressing force control motor 35 is not actuated, and a current corresponding to the crank shaft rotational angle θ is supplied to an electromagnetic brake 59.

Description

  The present invention relates to a driving force distribution device.

Patent Document 1 discloses a first roller that rotates together with a main drive wheel transmission system, a second roller that rotates together with a driven wheel transmission system, and a second roller that is rotatable about an eccentric axis that is offset from the rotation axis. A driving force distribution device including a crankshaft to be supported and an electric motor that rotationally drives the crankshaft is disclosed.
In this prior art, the crankshaft is rotationally driven by an electric motor and the second roller is turned around the eccentric axis, thereby causing the second roller to be displaced relative to the first roller in the radial direction, and thereby, between the two rollers. The radial pressing force, that is, the distribution of driving force between the main driving wheel and the sub driving wheel is controlled.

JP 2009-173261 A

  However, in the above-described prior art, after the rotation angle of the crankshaft in which the radial pressing force between the two rollers is as the command value is obtained and the target driving force distribution between the main and slave driving wheels is achieved, the rollers Even when the radial direction pressing force command value is unchanged, it is necessary to continue to supply the electric motor with electric power for maintaining the rotation angle, resulting in a problem that power consumption increases.

  The present invention has been made paying attention to the above-mentioned problems, and an object of the present invention is to provide a driving force distribution device capable of suppressing power consumption when maintaining the rotation angle of the crankshaft.

  In the present invention, when the rotation angle of the crankshaft reaches a target value, the electric motor is deactivated and a current corresponding to the rotation angle of the crankshaft is supplied to the electromagnetic brake that applies a braking force to the crankshaft.

  Therefore, power consumption can be suppressed by stopping the output of the electric motor and maintaining the rotation angle of the crankshaft by the braking force of the electromagnetic brake. Furthermore, the frictional force of the electromagnetic brake necessary to maintain the rotation angle changes according to the rotation angle of the crankshaft, whereas the power consumption is minimized by supplying a current according to the rotation angle. You can stay.

1 is a schematic plan view showing a power train of a four-wheel drive vehicle including a driving force distribution device according to an embodiment of the present invention as viewed from above the vehicle. It is a vertical side view of the driving force distribution apparatus in FIG. It is a longitudinal front view which shows the crankshaft used with the driving force distribution apparatus shown in FIG. FIG. 3 is an operation explanatory diagram of the driving force distribution device shown in FIG. 2, wherein (a) is an operation explanatory diagram showing a separation state of the first roller and the second roller at a position where the crankshaft rotation angle is 0 ° of the reference point; ) Is an operation explanatory view showing the contact state of the first roller and the second roller when the crankshaft rotation angle is 90 °, and (c) is the first roller and the second roller when the crankshaft rotation angle is 180 °. It is operation | movement explanatory drawing which shows the contact state of a roller. It is a flowchart which shows the flow of the current command value calculation control process of the electromagnetic brake in a transfer controller. It is a calculation map of the current command value according to the crankshaft rotation angle.

Hereinafter, embodiments of the present invention will be described in detail based on the illustrated examples.
[Example 1]
FIG. 1 is a schematic plan view showing a power train of a four-wheel drive vehicle equipped with a driving force distribution device 1 according to an embodiment of the present invention as a transfer as viewed from above the vehicle.

  The four-wheel drive vehicle shown in FIG. 1 is a rear-wheel drive vehicle in which rotation from the engine 2 is transmitted to the left and right rear wheels 6L and 6R through the rear propeller shaft 4 and the rear final drive unit 5 after being shifted by the transmission 3. Is the base vehicle. Then, a part of the torque to the left and right rear wheels (main drive wheels) 6L, 6R is sequentially passed through the front propeller shaft 7 and the front final drive unit 8 by the driving force distribution device 1, and left and right front wheels (secondary drive wheels) 9L, 9R This is a vehicle that enables four-wheel drive traveling by transmitting to the vehicle.

  As described above, the driving force distribution device 1 distributes and outputs a part of the torque to the left and right rear wheels (main driving wheels) 6L and 6R to the left and right front wheels (secondary driving wheels) 9L and 9R. The driving force distribution ratio between the wheels (main driving wheels) 6L and 6R and the left and right front wheels (secondary driving wheels) 9L and 9R is determined. In the first embodiment, the driving force distribution device 1 is shown in FIG. Configure.

In FIG. 2, reference numeral 11 denotes a housing of the driving force distribution device 1, and the input shaft 12 and the output shaft 13 are inclined in the housing 11 so that the respective rotation axes O ₁ and O ₂ intersect with each other. To do. The input shaft 12 is rotatably supported with respect to the housing 11 by ball bearings 14 and 15 at both ends thereof. Both ends of the input shaft 12 are protruded from the housing 11 under liquid-tight sealing by seal rings 25 and 26, respectively. 2, the left end of the input shaft 12 is drivingly coupled to the output shaft of the transmission 3 (see FIG. 1), and the right end is drivingly coupled to the rear final drive unit 5 via the rear propeller shaft 4 (see FIG. 1).

  Arranged near the both ends of the input shaft 12 and the output shaft 13, respectively, a pair of bearing supports 16, 17 are installed between the input / output shafts 12, 13, and the bearing supports 16, 17 are arranged in the middle of each bolt. (Not shown) is attached to the axially opposed inner wall of the housing 11. The bearing supports 16 and 17 include input shaft through holes 16a and 17a through which the input shaft 12 passes, output shaft through holes 16c and 17c through which the output shaft 13 and the crankshafts 51L and 51R pass, and input shaft through holes 16a, It has vertical walls 16b and 17b connecting between 17a and the output shaft through holes 16c and 17c, and has a substantially glasses shape when viewed from the front in the axial direction. Roller bearings 21 and 22 are interposed between the bearing supports 16 and 17 and the input shaft 12 so that the input shaft 12 can be rotated with respect to the bearing supports 16 and 17. However, the input shaft 12 is rotatably supported in the housing 11.

A first roller 31 is coaxially formed integrally in the axial direction of the input shaft 12 between the bearing supports 16 and 17 (between the roller bearings 21 and 22), and hydraulic power can be transmitted to the first roller 31 through hydraulic oil. The second roller 32 is coaxially and integrally formed at an intermediate position in the axial direction of the output shaft 13 so as to be in frictional contact.
The outer peripheral surfaces 31a and 32a of the first roller 31 and the second roller 32 are conical tapered surfaces that can come into line contact with each other even when the input shaft 12 and the output shaft 13 are inclined as described above. Thrust bearings 31cL, 31cR and 32cL, 32cR abut on both sides of the radially extending portions of the first roller 31 and the second roller 32, and holding grooves for holding the thrust bearings 31cL, 31cR and 32cL, 32cR in the radial direction. 31b and 32b are formed. The thrust bearings 31cL and 31cR contact the side walls 16a1 and 17a1 of the bearing supports 16 and 17, thereby positioning the first roller 31 in the axial direction. On the other hand, the thrust bearings 32cL and 32cR position the second roller 32 in the axial direction by abutting against roller side abutting portions 51Ld and 51Rd of crankshafts 51L and 51R, which will be described later.

The output shaft 13 is pivotally supported on the bearing supports 16 and 17 in the vicinity of both ends 13L and 13R, so that the output shaft 13 is pivotally supported in the housing 11 via the bearing supports 16 and 17.
Thus, when the output shaft 13 (13L, 13R) is pivotally supported on the bearing supports 16, 17, the following eccentric support structure is used.

A hollow outer shaft type crankshaft 51L, 51R is loosely fitted between the output shaft 13 (13L, 13R) and the bearing supports 16, 17 through which the output shaft 13 (13L, 13R) passes.
The crankshaft 51L and the output shaft 13 (13L) protrude from the housing 11 at the left end in FIG. 2, respectively, and the seal ring 27 is interposed between the housing 11 and the crankshaft 51L at the protruding portion. By interposing a seal ring 28 between (13L), the crankshaft 51L protruding from the housing 11 and the protruding portion of the output shaft 13 (13L) are liquid-tightly sealed.

  In FIG. 2, the left end 13L of the output shaft 13 discharged from the housing 11 is drivingly coupled to the left and right front wheels 9L and 9R via the front propeller shaft 7 (see FIG. 1) and the front final drive unit 8.

The roller shafts 52L and 52R are interposed between the hollow holes 51La and 51Ra (radius Ri) of the crankshafts 51L and 51R and the corresponding ends 13L and 13R of the output shaft 13, respectively, so that the output shaft 13 (13L and 13R) crankshafts 51L, hollow hole 51La of 51R, in 51Ra, supports that can freely rotate around these central axis O _2.

As clearly shown in FIG. 3, the hollow holes 51La, 51Ra (center axis O ₂ ) of the crankshafts 51L, 51R are eccentric hollow holes eccentric to the outer peripheral portions 51Lb, 51Rb (center axis O ₃ , radius Ro). The central axis O ₂ of these eccentric hollow holes 51La and 51Ra is offset from the central axis O ₃ of the outer peripheral portions 51Lb and 51Rb by the eccentricity ε between them.
The outer peripheries 51Lb and 51Rb of the crankshafts 51L and 51R are rotatable to the inner periphery of the output shaft through holes 16c and 17c of the bearing supports 16 and 17 on the corresponding side via roller bearings 53L and 53R, which are radial bearings To support. Further, the roller side contact portions 51Ld and 51Rd of the crankshafts 51L and 51R are rotatably supported by the thrust bearings 32cL and 32cR. Further, the thrust bearings 32cL, 32cR and axially disposed thrust bearings 54L, 54R are provided.The thrust bearings 54L, 54R are in contact with the spacers 60L, 60R in a freely rotating manner, and ring gears 51Lc, 51Rc described later. The crankshafts 51L and 51R are rotatably supported by contacting with each other.

The spacers 60L and 60R are in contact with the wall surfaces 16b1 and 17b1 of the vertical walls 16b and 17b facing the second roller 32 and are on the inner diameter side of the inner peripheral surfaces of the output shaft through holes 16c and 17c. First spacer portions 61L and 61R extending to a position not in contact with 51R, and second spacer portions 62L and 62R (extending portions) extended so as to be inserted into the output shaft through holes 16c and 17c. .
Then, the spacers 60L and 60R are positioned in the radial direction by abutting between the outer periphery of the second spacer portions 62L and 62R and the inner peripheral surfaces of the output shaft through holes 16c and 17c, and the roller bearings 53L and 53R And mutual interference between the thrust bearings 54R and 54L.

  Ring gears 51Lc and 51Rc of the same specification are integrally provided at adjacent ends of the crankshafts 51L and 51R that face each other, and a common crankshaft drive pinion 55 is engaged with the ring gears 51Lc and 51Rc, respectively. 55 is coupled to the pinion shaft 56.

  As described above, when the crankshaft drive pinion 55 is engaged with the ring gears 51Lc and 51Rc, the crankshafts 51L and 51R are rotated in such a manner that their outer peripheral portions 51Lb and 51Rb are aligned with each other in the circumferential direction. In this state, the crankshaft drive pinion 55 is engaged with the ring gears 51Lc and 51Rc.

  Both ends of the pinion shaft 56 are rotatably supported with respect to the housing 11 by bearings 56a and 56b. A large-diameter output gear 57b (first output gear) is fixed to the right end side of the pinion shaft 56 on the right side of FIG. On the outer diameter side of the large-diameter output gear 57b, as shown by an arrow A, a crank for detecting the rotation angle of the large-diameter output gear 57b by detecting irregularities 57b1 and 57b2 on the tooth surfaces of the large-diameter output gear 57b. A shaft rotation angle sensor 115 is provided. The crankshaft rotation angle sensor 115 is a magnetic sensor that detects a change in magnetic flux density due to a change in the unevenness of the tooth surface of the large-diameter output gear 57b, and determines the rotation angle of the pinion shaft 56 and thus the rotation angles of the crankshafts 51L and 51R. Detect.

  As described above, in the case of the rotation angle sensor that detects the unevenness of the tooth surface of the large-diameter output gear 57b, components such as a rotary encoder that detects the motor rotation angle require parts on both the rotating body side and the stator side. Compared to an expensive configuration, the rotation angle can be detected at low cost while achieving compactness in terms of space. In addition, since it can be attached from the outer periphery side of the housing 11 at a part of the outer peripheral space of the large-diameter output gear 57b, there can be an advantageous arrangement in terms of space.

  A small-diameter output gear 57a (second output gear) that meshes with the large-diameter output gear 57b is provided on the outer periphery of the large-diameter output gear 57b. The small-diameter output gear 57a is integrally formed with the small-diameter output gear shaft 57a1, and is further assembled to a motor drive shaft 58a of a roller-to-roller radial direction pressing force control motor (hereinafter referred to as a motor) 35 on the left end side in FIG. And rotate integrally with the motor 35.

  On the right end side of the small-diameter output gear shaft 57a1, an electromagnetic brake 59 that can fix the rotation of the small-diameter output gear shaft 57a1 by applying a braking force to the small-diameter output gear shaft 57a1 is provided. The electromagnetic brake 59 includes a coil 59a that generates electromagnetic force, and a clutch plate 59b that is spline-fitted at the right end of the small-diameter output gear shaft 57a1 so as to be capable of stroke in the axial direction.

  The clutch plate 59b is provided with an armature. When the coil 59a is energized, the clutch plate 59b is moved in the axial direction by an electromagnetic attractive force and is attracted and fixed to the yoke on the outer periphery of the coil 59a. When the electromagnetic brake 59 is on (engaged state) by supplying current to the coil 59a, a braking torque corresponding to the current value is applied to the pinion shaft 56, and this braking torque acts on the pinion shaft 56 from the second roller 32 side. By setting the torque to be greater than or equal to the torque to be applied, the pinion shaft 56 can be fixed and the desired distance between the roller axes can be maintained. On the other hand, when the current supply to the coil 59a is stopped and the electromagnetic brake 59 is off (in the released state), the rotation operation of the motor 35 can be transmitted to the pinion shaft 56, so that the desired roller shaft distance can be achieved.

Note that the pinion 55 and the ring gear 51Lc by the motor 35, a crank shaft 51L via the 51Rc, when rotating position control 51R, the rotation axis O ₂ of output shaft 13 and the second roller 32, the trajectory circle α indicated by a broken line in FIG. 3 pivots about the central axis O ₃ along.

As will be described later in detail, the second roller 32 is rotated by the rotation axis O ₂ (second roller 32) along the locus circle α in FIG. 3 as shown in FIGS. 4 (a) to 4 (c). As the rotation angle θ of the crankshafts 51L and 51R increases with the distance L1 between the roller axes of the first roller 31 and the second roller 32 in the radial direction, the radius of the first roller 31 and the second roller 32 It can be made smaller than the sum value with the radius. Due to such a decrease in the distance L1 between the roller shafts, the radial pressing force of the second roller 32 against the first roller 31 (the transmission torque capacity between the rollers: the traction transmission capacity) increases. The inter-roller radial pressing force (inter-roller transmission torque capacity: traction transmission capacity), that is, the driving force distribution ratio can be arbitrarily controlled.

As shown in FIG. 4A, in the first embodiment, the second roller rotation axis O ₂ is located immediately below the crankshaft rotation axis O ₃ , and the inter-axis distance L1 between the first roller 31 and the second roller 32 is The distance L1 between the roller axes at the maximum bottom dead center is made larger than the sum of the radius of the first roller 31 and the radius of the second roller 32. Thereby, at the bottom dead center of the crankshaft rotation angle θ = 0 °, the first roller 31 and the second roller 32 are not pressed against each other in the radial direction, and traction is transmitted between the rollers 31 and 32. No traction transmission capacity = 0, and the traction transmission capacity is between 0 at the bottom dead center and the maximum value obtained at the top dead center (θ = 180 °) shown in Fig. 4 (c). Can be controlled arbitrarily. In the first embodiment, the description will be given assuming that the rotation angle reference point of the crankshafts 51L and 51R is the bottom dead center of the crankshaft rotation angle θ = 0 °.

[Driving force distribution]
The drive force distribution action of the transfer 1 described above with reference to FIGS. On the other hand, the torque that has reached the input shaft 12 of the transfer 1 from the transmission 3 (see FIG. 1) passes directly from the input shaft 12 through the rear propeller shaft 4 and the rear final drive unit 5 (both see FIG. 1) to the left and right rear wheels 6L. , 6R (main drive wheel).

  On the other hand, the transfer 1 controls the rotational position of the crankshafts 51L and 51R via the pinion 55 and the ring gears 51Lc and 51Rc by the motor 35, and the first roller 31 and the second roller 32 have a roller shaft distance L1 (see FIG. 4). Since the rollers 31, 32 have a torque transfer capacity between the rollers according to the radial mutual pressing force, the left and right rear wheels 6L, 6R (main A part of the torque to the drive wheels) is directed from the first roller 31 to the output shaft 13 via the second roller 32, and the left and right front wheels 9L and 9R (secondary drive wheels) can also be driven. Thus, the vehicle is capable of four-wheel drive running by driving all of the left and right rear wheels 6L and 6R (main drive wheels) and the left and right front wheels (secondary drive wheels) 9L and 9R.

  Note that the radial pressing reaction force between the first roller 31 and the second roller 32 during the transmission is received by the bearing supports 16 and 17 which are rotation support plates common to these rollers, and does not reach the housing 11. The radial pressing reaction force is 0 when the crankshaft rotation angle θ is 0 ° to 90 °, and increases as θ increases while the crankshaft rotation angle θ is 90 ° to 180 °. The maximum value is obtained when the crankshaft rotation angle θ is 180 °.

  During such four-wheel drive traveling, the rotation angle θ of the crankshafts 51L and 51R is 90 ° of the reference position as shown in FIG. 4B, and the first roller 31 and the second roller 32 are mutually In this case, when the frictional contact is made by pressing with the radial pressing force corresponding to the offset amount OS at this time, the traction transmission capacity corresponding to the offset amount OS between these rollers is applied to the left and right front wheels (sub driven wheels) 9L, 9R. Power transmission is performed.

  Then, the crankshafts 51L and 51R are rotated from the reference position in FIG. 4B toward the top dead center of the crankshaft rotation angle θ = 180 ° shown in FIG. 4C to increase the crankshaft rotation angle θ. As a result, the distance L1 between the roller shafts further decreases and the mutual overlap amount OL of the first roller 31 and the second roller 32 increases. As a result, the first roller 31 and the second roller 32 increase the radial mutual pressing force. Thus, the traction transmission capacity between these rollers can be increased.

When the crankshafts 51L and 51R reach the top dead center position in FIG. 4 (c), the first roller 31 and the second roller 32 are in the radial direction with the maximum radial pressing force corresponding to the maximum overlap amount OL. The traction transmission capacity between them can be maximized. The maximum overlap amount OL is the sum of the eccentric amount ε between the second roller rotation axis O ₂ and the crankshaft rotation axis O ₃ and the offset amount OS described above with reference to FIG.

  As is apparent from the above description, the crankshaft rotation angle is controlled by rotating the crankshafts 51L and 51R from the rotation position of the crankshaft rotation angle θ = 0 ° to the rotation position of the crankshaft rotation angle θ = 180 °. As θ increases, the traction transmission capacity between rollers can be continuously changed from 0 to the maximum value. Conversely, by rotating the crankshaft 51L, 51R from the rotation position of the crankshaft rotation angle θ = 180 ° to the rotation position of θ = 0 °, the traction transmission between the rollers is reduced as the crankshaft rotation angle θ decreases. The capacity can be continuously changed from the maximum value to 0, and the traction transmission capacity between the rollers can be freely controlled by rotating the crankshafts 51L and 51R.

[Traction transmission capacity control]
During the four-wheel drive described above, the transfer 1 distributes and outputs a part of the torque to the left and right rear wheels (main drive wheels) 6L and 6R to the left and right front wheels (secondary drive wheels) 9L and 9R as described above. Therefore, the traction transmission capacity between the first roller 31 and the second roller 32 can be obtained from the driving force of the left and right rear wheels 6L, 6R (main driving wheels) and the front and rear wheel target driving force distribution ratio. ) It is necessary to correspond to the target front wheel drive force to be distributed to 9L and 9R.

In order to control the traction transmission capacity that meets this requirement, in the first embodiment, a transfer controller (eccentric rotation angle holding control means) 111 is provided as shown in FIG. 1, thereby controlling the rotational position of the motor 35 (crankshaft rotation angle). θ control).
Therefore, the transfer controller 111 has a signal from the accelerator opening sensor 112 that detects the accelerator pedal depression amount (accelerator opening) APO that adjusts the output of the engine 2, and the rotation of the left and right rear wheels 6L and 6R (main drive wheels). A signal from the rear wheel speed sensor 113 that detects the circumferential speed Vwr, a signal from the yaw rate sensor 114 that detects the yaw rate φ around the vertical axis passing through the center of gravity of the vehicle, and the rotation angle θ of the crankshafts 51L and 51R are detected. A signal from the crankshaft rotation angle sensor 115 and a signal from the oil temperature sensor 116 for detecting the temperature TEMP of the hydraulic oil in the transfer 1 (housing 11) are input.

The transfer controller 111 performs the traction transmission capacity control of the transfer 1 (front and rear wheel driving force distribution control of a four-wheel drive vehicle) based on the detection information of the sensors 112 to 116 as described below.
That is, first, the transfer controller 111 first knows the driving force of the left and right rear wheels 6L and 6R (main driving wheels) and the front and rear wheel target driving force distribution ratio based on the accelerator opening APO, the rear wheel speed Vwr, and the yaw rate φ. Ask for.
Next, the transfer controller 111 determines the target front wheel drive force to be distributed to the left and right front wheels (secondary drive wheels) 9L and 9R from the drive force of the left and right rear wheels 6L and 6R (main drive wheels) and the front and rear wheel target drive force distribution ratio. Ask for.

Further, the transfer controller 111 determines the radial pressing force between the rollers required for the first roller 31 and the second roller 32 to transmit the target front wheel driving force (the traction transmission capacity between the first roller 31 and the second roller 32). Of the crankshafts 51L and 51R (see FIGS. 2 and 3) necessary for realizing the radial pressing force between the rollers (the traction transmission capacity between the first roller 31 and the second roller 32). The rotation angle target value tθ, that is, the target turning position of the second roller axis O ₂ is calculated.

  Then, the transfer controller 111 changes the crankshaft rotation angle θ to the crankshaft rotation angle target value tθ in accordance with the crankshaft rotation angle deviation between the crankshaft rotation angle θ detected by the sensor 115 and the crankshaft rotation angle target value tθ. The drive of the motor 35 is controlled so as to match. When the rotation angle θ of the crankshafts 51L and 51R coincides with the target value tθ by the drive control of the motor 35, the first roller 31 and the second roller 32 can mutually transmit the target front wheel driving force. It is possible to control the traction transmission capacity between the first roller 31 and the second roller 32 to be the front / rear wheel target driving force distribution ratio by being pressed and contacted in the radial direction.

When the rotation angle θ of the crankshafts 51L and 51R matches the target value tθ, the transfer controller 111 turns on the electromagnetic brake 59 to maintain the rotation angle θ and deactivates the motor 35.
At this time, the current value supplied to the electromagnetic brake 59 is set to the minimum current value necessary for maintaining the rotation angle of the crankshafts 51L and 51R, thereby suppressing power consumption.

FIG. 5 is a flowchart showing a flow of current command value calculation control processing of the electromagnetic brake 59 in the transfer controller 111, and each step will be described below.
In step S1, the crankshaft rotation angle θ is input.
In step S2, it is determined whether or not the crankshaft rotation angle θ matches the crankshaft rotation angle target value tθ. If YES, the process proceeds to step S3, and if NO, the process proceeds to return.
In step S3, a current command value corresponding to the crankshaft rotation angle θ is calculated with reference to the map shown in FIG.
In step S4, the supply current to the electromagnetic brake 59 is increased or decreased so that the supply current to the electromagnetic brake 59 becomes the current command value calculated in step S3.

  FIG. 6 is a calculation map of a current command value according to the crankshaft rotation angle θ. The current command value is a minimum value (> 0) while the crankshaft rotation angle θ = 0 ° to 90 °, and θ = The angle θ is set so as to increase as the angle θ increases between 90 ° and 135 °, and decreases as the angle θ increases between 135 ° and 180 °. The characteristic of the current command value with respect to the crankshaft rotation angle θ shown in FIG. 6 is to maintain the crankshaft rotation angle θ against the radial pressing reaction force of the first roller 31 and the second roller 32, that is, the crankshaft 51L, This is the minimum current value for obtaining the braking torque of the electromagnetic brake 59 necessary for stopping the rotation of 51R.

According to the driving force distribution device 1 of the first embodiment described above, the following operational effects are obtained.
When the crankshaft rotation angle θ reaches the rotation angle target value tθ, the motor 35 is deactivated and a current corresponding to the crankshaft rotation angle θ is supplied to the electromagnetic brake 59.
In maintaining the crankshaft rotation angle θ, the power consumption is compared with the case where the crankshaft rotation angle θ is held by the output torque of the motor 35 by holding the crankshaft rotation angle θ by the braking torque of the electromagnetic brake 59. Can be greatly reduced.

Here, the braking torque of the electromagnetic brake 59 necessary for stopping the rotation of the crankshafts 51L and 51R varies according to the crankshaft rotation angle θ, and the larger θ is between θ = 90 ° and 135 °. It becomes larger, and becomes smaller as θ becomes larger between 135 ° and 180 °.
Therefore, by making the current value to be applied to the electromagnetic brake 59 variable based on the map shown in FIG. 6 according to the crankshaft rotation angle θ, the power consumption is always compared with the case where the maximum current value is always applied. Can be kept to a minimum.

In the first embodiment, the current for maintaining the crankshaft rotation angle θ with respect to the electromagnetic brake 59 even when the crankshaft rotation angle θ = 0 ° to 90 ° at which no radial pressing reaction force acts. Supply.
If the current value supplied to the electromagnetic brake 59 is zero when θ = 0 ° to 90 °, the crankshafts 51L and 51R are in a free state. This is because the hitting noise and the controllability of the crankshaft rotation angle θ are deteriorated.
Therefore, even when the radial pressing reaction force does not act, by supplying the current necessary for maintaining the crankshaft rotation angle θ to the electromagnetic brake 59, the generation of rattling noise and the crankshaft rotation angle θ The deterioration of controllability can be avoided.

1 Driving force distribution device (transfer)
31 1st roller
32 Second roller
35 Roller radial pressing force control motor (electric motor)
51L, 51R Crankshaft
59 Electromagnetic brake
111 Transfer controller (Eccentric rotation angle retention control means)

Claims (2)

An input shaft that rotates with the main drive wheel transmission system;
A first roller provided on the input shaft;
An output shaft that rotates with the driven wheel transmission system;
A second roller provided on the output shaft;
A crankshaft that rotatably supports the second roller around an eccentric axis offset from a rotation axis of the second roller;
An electric motor for rotationally driving the crankshaft;
Have
In the driving force distribution device that operates the electric motor to rotate the second roller around the eccentric axis and distributes the driving force to the driven wheels by bringing the outer peripheral surfaces of both rollers into frictional contact with each other.
An electromagnetic brake for applying a braking force to the rotation of the crankshaft;
When the rotation angle of the crankshaft reaches a target value, the electric motor is deactivated, and an eccentric rotation angle holding control means for supplying a current corresponding to the rotation angle to the electromagnetic brake;
A driving force distribution device comprising: The driving force distribution device according to claim 1,
The eccentric rotation angle holding control means sets the current value to a value higher than zero.

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