JP2014124993A - Power transmission device of four-wheel drive car - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power transmission device of a four-wheel drive car, capable of improving performance of switching from a four-wheel drive state to a two-wheel drive state.SOLUTION: The power transmission device of a four-wheel drive car includes: a transfer 24 (a second engagement clutch unit 54) capable of switching states between a two-wheel drive state and a four-wheel drive state; and a clutch unit 110 (an engagement clutch 38) which is, when in the two-wheel drive state, switched into a cut-off state where power transmission is not performed between one front wheel 14R and a front differential 30 provided between front wheels 14L, 14R, and when in the four-wheel drive state, switched into a connection state where power transmission is performed between the front differential 30 and one front wheel 14R. At the time of switching from the four-wheel drive state to the two-wheel drive state, even if switching to the two-wheel drive state by the transfer 24 is not completed, switching to the cut-off state of the clutch unit 110 is started when set time T1 has passed since the start of switching to the two-wheel drive state.

Description

  The present invention relates to a power transmission device for a four-wheel drive vehicle configured to be switchable between a two-wheel drive state and a four-wheel drive state.

  A four-wheel drive vehicle (for example, a part-time four-wheel drive vehicle) that can be switched between a two-wheel drive state and a four-wheel drive state is known. In such a four-wheel drive vehicle, a sufficient driving force can be transmitted to the four wheels in the four-wheel drive state, so that it is suitable when traveling on a low μ road surface such as a rough road, but on the other hand, for example, asphalt When traveling on a relatively high μ road surface curve such as the above, the braking difference occurs between the front wheels and the rear wheels, causing a braking phenomenon. Since circulating torque is accumulated in the power transmission device due to this braking phenomenon, the power transmission device is in a high load state, which is not preferable in terms of vehicle running performance and strength of the power transmission device.

  Conventionally, the power between one of left and right wheels (for example, front wheels) that are driven wheels in a two-wheel drive state and a differential (for example, front differential) provided between the left and right wheels. There has been known one provided with a clutch device (ADD: Automatic Disconnecting Differential) for switching transmission or disconnection (see, for example, Patent Document 1). In the power transmission device provided with such a clutch device, when the two-wheel drive state is set, the clutch device is disengaged so that power transmission between the differential device and one of the wheels is not performed. The diff case, propeller shaft, etc. are made non-rotating to improve fuel efficiency.

JP-A 63-269734

  In the power transmission device for a four-wheel drive vehicle equipped with the clutch device as described above, when switching from the four-wheel drive state to the two-wheel drive state, the transfer (power distribution device) switches from the four-wheel drive state to the two-wheel drive state. After completion, the clutch device is switched to a disconnected state. However, if the above-described circulating torque is accumulated in the power transmission device, the switching from the four-wheel drive state to the two-wheel drive state in the transfer is hindered by the circulation torque, and the switching time from the four-wheel drive state to the two-wheel drive state There is a concern that it will be long. This point will be described with a specific example.

  As a 2WD / 4WD switching device that switches between a two-wheel drive state and a four-wheel drive state in a transfer, for example, there is a sleeve type device, a drive sprocket provided on the first output shaft, and a driven provided on the second output shaft. A sprocket, a chain that spans the two sprockets, and a switching clutch that switches between allowing or preventing relative rotation of the drive sprocket relative to the first output shaft. The switching clutch includes a cylindrical sleeve and an actuator (for example, an electric motor) that moves the sleeve along the axial direction. The sleeve is located between a position where the drive sprocket can rotate relative to the first output shaft and a position where the drive sprocket cannot rotate relative to the first output shaft, in other words, a position where the drive sprocket and the sleeve are connected (for example, spline fitting). It can be moved to and from the position where the connection is released.

  When switching from the four-wheel drive state to the two-wheel drive state by transfer, the sleeve is moved (sliding) by the actuator to release the connection between the drive sprocket and the sleeve, and the drive sprocket is rotated relative to the first output shaft. Make it possible. However, when the circulating torque is accumulated in the power transmission device, the connection between the drive sprocket and the sleeve must be released against the sliding resistance of the sleeve due to the accumulated circulating torque. For this reason, the greater the accumulated circulating torque, the longer the switching time from the four-wheel drive state to the two-wheel drive state. Further, when the actuator load (motor load) is insufficient as compared with the accumulated circulating torque, there is a problem that switching cannot be performed until the circulating torque decreases. Furthermore, in vehicles such as a pickup truck where the front and rear wheel diameter difference is set to be relatively large, the greater the difference between the front and rear wheel diameters, the greater the circulating torque that is generated. Is done.

  The present invention has been made in view of such problems, and provides a power transmission device for a four-wheel drive vehicle capable of improving the switching performance from the four-wheel drive state to the two-wheel drive state. Objective.

  In the present invention, means for solving the above-described problems are configured as follows. That is, the present invention relates to a transfer that can be switched between a two-wheel drive state and a four-wheel drive state, one wheel among left and right wheels that are driven wheels in the two-wheel drive state, and between these left and right wheels. Switched to a disconnected state in which power transmission is not performed with the provided differential device, and switched to a connected state in which power transmission is performed between the differential device and the one wheel in the four-wheel drive state. A four-wheel drive vehicle power transmission device provided with a clutch device, wherein when the four-wheel drive state is switched to the two-wheel drive state, the transfer to the two-wheel drive state may not be completed. When a set time has elapsed from the start of switching to the two-wheel drive state, the clutch device is started to switch to the disengaged state.

  According to the above configuration, after the set time has elapsed, the circulating torque accumulated in the power transmission device is released during traveling in the four-wheel drive state by switching the clutch device to the disconnected state. Switching to the state can be performed without being disturbed by the circulating torque. Thereby, the switching time from the four-wheel drive state to the two-wheel drive state can be shortened, and the switching performance from the four-wheel drive state to the two-wheel drive state can be improved.

  Here, when the set time has elapsed since the start of switching to the two-wheel drive state, the switching to the two-wheel drive state by the transfer is stopped, and then the switching of the clutch device to the disengaged state is started. Is preferred. In this case, after the switching of the clutch device to the disengaged state is completed, the transfer to the two-wheel drive state is resumed by the transfer, or a second set time has elapsed from the start of the clutch device to the disengaged state. In this case, the switching of the clutch device to the disengaged state can be stopped, and the switching to the two-wheel drive state by the transfer can be resumed.

  According to the power transmission device for a four-wheel drive vehicle of the present invention, the switching time from the four-wheel drive state to the two-wheel drive state can be shortened, and the switching performance from the four-wheel drive state to the two-wheel drive state is improved. Can do.

It is a figure showing a schematic structure of a power transmission device of a four-wheel drive vehicle concerning an embodiment of the present invention. It is a figure which shows the transfer with which the power transmission device of FIG. 1 is equipped. It is a figure which shows the front differential with which the power transmission device of FIG. 1 is provided, and a clutch apparatus periphery. It is a flowchart which shows the switching control from the four-wheel drive state in a power transmission device to a two-wheel drive state.

  Embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a diagram showing a schematic configuration of a power transmission device 100 for a four-wheel drive vehicle according to an embodiment of the present invention. FIG. 2 is a diagram showing the transfer 24 provided in the power transmission device 100 of FIG. FIG. 3 is a view showing the periphery of the front differential 30 and the clutch device 38 provided in the power transmission device 100 of FIG.

  FIG. 1 illustrates a power transmission device 100 for a four-wheel drive vehicle based on an FR (front engine / rear drive) type vehicle. The power transmission device 100 uses a pair of left and right front wheels 14L and 14R (also simply referred to as “front wheels 14”) as auxiliary drive wheels, and left and right main drive wheels as power from the engine 12 as a driving force source for traveling. The signals are transmitted to a pair of rear wheels 16L and 16R (also simply referred to as “rear wheels 16”).

  Specifically, the power transmission device 100 includes an automatic transmission 22 having a torque converter 20 connected to the engine 12 and the power transmitted from the automatic transmission 22 connected to the output side of the automatic transmission 22 on the front wheels. 14, a transfer (power distribution device) 24 that distributes to the rear wheel 16, a front propeller shaft 26 and a rear propeller shaft 28 that transmit the power distributed by the transfer 24 to the front wheel 14 and the rear wheel 16, respectively, and a front propeller shaft 26 and a rear differential (differential device) 32 and a rear differential (differential device) 32, respectively. The front differential 30 and the front wheels 14L and 14R are connected via a pair of left and right axles 34L and 34R (also simply referred to as “axle 34”), and the rear differential 32 and the rear wheels 16L and 16R are paired with a pair of left and right axles 36L. , 36R (also simply referred to as “axle 36”). In the power transmission device 100, the power generated by the engine 12 is transmitted from the torque converter 20, the automatic transmission 22, the transfer 24, the front propeller shaft 26 and the rear propeller shaft 28, the front differential 30 and the rear differential 32, the axle 34 and the axle. The power is transmitted to the front wheels 14 and the rear wheels 16 through the power transmission paths 36 and the like sequentially.

  The transfer 24 selectively cuts off (cuts) or connects power transmission between the rear propeller shaft 28 and the front propeller shaft 26, and transmits power from the automatic transmission 22 only to the rear wheels 16, or Distribute to each of the front wheel 14 and the rear wheel 16. Further, the transfer 24 establishes either the high speed side gear stage (high speed side gear stage) H or the low speed side gear stage (low speed side gear stage) L to shift and transmit the power from the automatic transmission 22. It functions as an auxiliary transmission.

  Specifically, as shown in FIG. 2, the transfer 24 includes a transfer case 42 as a non-rotating member connected to the rear side of the transmission case 40 of the automatic transmission 22. In the transfer case 42, a first output shaft (main drive shaft) connected to a sub-transmission 46 mainly composed of a single-pinion type planetary gear unit 44 and a rear propeller shaft 28 on an axis C1. ) 48 and one of the two power transmission paths from the sub-transmission 46 to the first output shaft 48 is brought into a connected state to selectively establish the low-speed gear stage L or the high-speed gear stage H. A drive sprocket 52 provided so that the relative rotation of the one-mesh clutch device 50, the relative rotation with respect to the first output shaft 48 (rear propeller shaft 28) can be selectively switched, and the drive sprocket 52 with respect to the first output shaft 48 And a second meshing clutch device (2WD / 4WD switching device) 54 for selectively switching the permissible or blocked relative rotation.

  Further, in the transfer case 42, the second output shaft (sub drive shaft) 60 connected to the front propeller shaft 26 and the second output shaft 60 are provided on the axis C <b> 2 so as not to rotate relative to the second output shaft 60. A driven sprocket 62 is provided. A chain 64 (or a belt or the like) is wound around the drive sprocket 52 on the first output shaft 48 and the driven sprocket 62 on the second output shaft 60.

  The transfer 24 transmits the rotation of the input shaft 66 connected to the output shaft 68 of the automatic transmission 22 to the first output shaft 48 via the auxiliary transmission 46. Here, in a state where the relative rotation of the drive sprocket 52 with respect to the first output shaft 48 is allowed, power transmission from the first output shaft 48 to the second output shaft 60 is not performed. That is, the power transmission path from the first output shaft 48 to the second output shaft 60 is blocked. On the other hand, in a state where the relative rotation of the drive sprocket 52 with respect to the first output shaft 48 is blocked, the power from the first output shaft 48 to the second output shaft 60 via the drive sprocket 52, the chain 64, and the driven sprocket 62. Transmission takes place. That is, the power transmission path from the first output shaft 48 to the second output shaft 60 is connected.

  The planetary gear unit 44 of the sub-transmission 46 is connected to the input shaft 66 and is arranged concentrically with the sun gear S1 and rotatable about the axis C1. The planetary gear unit 44 is arranged on the transfer case 42 around the axis C1. A ring gear R1 that is non-rotatably connected, and a carrier CA1 that supports the sun gear S1 and a plurality of pinion gears P1 meshing with the ring gear R1 so as to rotate and revolve around the sun gear S1. The rotational speed of the sun gear S1 is constant with respect to the rotational speed of the input shaft 66, while the rotational speed of the carrier CA1 is decelerated with respect to the rotational speed of the input shaft 66. A clutch gear 72 of the synchronous meshing mechanism 70 of the first meshing clutch device 50 is fixed to the sun gear S1 so as not to rotate relative to the sun gear S1. In addition, the clutch gear 76 of the meshing clutch 74 of the first meshing clutch device 50 is fixed to the carrier CA1 so as not to rotate relative to the carrier CA1.

  The first meshing clutch device 50 includes a synchronous meshing mechanism (synchro mechanism) 70 for establishing the high speed side gear stage H and a meshing clutch 74 for establishing the low speed side gear stage L. The synchronous meshing mechanism 70 includes a clutch hub 78 that is spline-fitted so as not to rotate relative to the first output shaft 48, and a spline-fitting to the clutch hub 78, so that relative rotation with respect to the clutch hub 78 is impossible. A cylindrical sleeve 80 provided so as to be relatively movable in the axial direction, a clutch gear 72 disposed between the planetary gear unit 44 and the clutch hub 78 and fixed to the sun gear S1, a sleeve 80, and And a synchronizer ring 82 that prevents the sleeve 80 from moving in the direction of the clutch gear 72 when the rotation of the clutch gear 72 is asynchronous. The synchronizer ring 82 has a function of synchronizing the sleeve 80 and the clutch gear 72 with each other when the sleeve 80 and the clutch gear 72 are engaged with each other. The clutch gear 72 has outer peripheral teeth that mesh with the inner peripheral teeth provided on the inner peripheral surface of the sleeve 80 so as not to rotate relative to each other and to be relatively movable in the axial direction. Movement (sliding) of the sleeve 80 in the axial direction relative to the clutch hub 78 is performed by a shift actuator 84 (for example, an electric motor). In this case, a first shift fork shaft 95 extending in a direction parallel to the axial direction is attached to the shift actuator 84 as an output member, and the first shift fork 96 is fixed to the tip of the first shift fork shaft 95. It is installed. When the first shift fork shaft 95 is moved along the axial direction by driving the shift actuator 84, the sleeve 80 is moved in the axial direction with respect to the clutch hub 78 via the first shift fork 96. It has come to be.

  The meshing clutch 74 has the above-described sleeve 80 and a clutch gear 76 fixed to the carrier CA1. The clutch gear 76 has inner peripheral teeth that mesh with the outer peripheral teeth 86 provided on the outer peripheral surface of the sleeve 80 so as not to rotate relative to each other and to be relatively movable in the axial direction. It is arranged on the opposite side to 72.

  In the first meshing clutch device 50, the sleeve 80 slides along the axial direction by the drive of the shift actuator 84, and the sleeve 80 meshes with the clutch gear 72 of the synchronous meshing mechanism 70, whereby the auxiliary transmission 46 has a high speed side. The gear stage H is established. A path through which power is transmitted to the first output shaft 48 via the sun gear S1 and the clutch gear 72 is a power transmission path for establishing the high speed side gear stage H. On the other hand, when the sleeve 80 slides along the axial direction and the sleeve 80 meshes with the clutch gear 76 of the meshing clutch 74, the low-speed gear stage L is established in the auxiliary transmission 46. A path through which power is transmitted to the first output shaft 48 via the carrier CA1 and the clutch gear 76 is a power transmission path for establishing the low-speed gear stage L. As shown in FIG. 2, the transfer 24 is in a neutral state when the sleeve 80 does not mesh with either of the clutch gears 72 and 76, and the gear 24 is moved between the high-speed gear stage H and the low-speed gear stage L. When the stage is switched, it is switched after passing through this neutral state.

  The 2nd meshing clutch apparatus 54 is a 2WD / 4WD switching apparatus which consists of a well-known dog clutch etc., for example. Specifically, the second meshing clutch device 54 includes a clutch hub 88 that is spline-fitted so as not to rotate relative to the first output shaft 48, and a clutch hub 88 that is spline-fitted to the clutch hub 88. A cylindrical sleeve 90 provided so as not to rotate relative to the shaft and movable in the axial direction, and a clutch disposed between the drive sprocket 52 and the clutch hub 88 and fixed to the drive sprocket 52. And a gear 92. The clutch gear 92 has outer peripheral teeth that mesh with the inner peripheral teeth of the inner peripheral surface of the sleeve 90 so that they cannot rotate relative to each other and are relatively movable in the axial direction. The sleeve 90 is connected between a position where the drive sprocket 52 can rotate relative to the first output shaft 48 and a position where the drive sprocket 52 cannot rotate relative to the first output shaft 48, in other words, a position where the drive sprocket 52 and the sleeve 90 are connected. It is possible to move between the positions to be released. Movement (sliding) of the sleeve 90 in the axial direction relative to the clutch hub 88 is performed by the shift actuator 84. In this case, a second shift fork shaft 97 extending in a direction parallel to the axial direction is attached to the shift actuator 84 as an output member, and the second shift fork 98 is fixed to the tip of the second shift fork shaft 97. It is installed. When the second shift fork shaft 97 is moved along the axial direction by driving the shift actuator 84, the sleeve 90 moves in the axial direction relative to the clutch hub 88 via the second shift fork 98. It has come to be.

  In the second meshing clutch device 54, when the shift actuator 84 is not driven, the sleeve 90 is positioned at a position as shown in FIG. In this position, the connection between the sleeve 90 and the clutch gear 92 is released, the drive sprocket 52 is rotatable relative to the first output shaft 48 around the axis C1, and the drive sprocket 52 is Since the first output shaft 48 is idled, no power is transmitted to the second output shaft 60 via the drive sprocket 52. On the other hand, when the sleeve 90 is moved to the drive sprocket 52 side by the drive of the shift actuator 84, when the sleeve 90 meshes with the clutch gear 92, relative rotation around the axis C <b> 1 of the drive sprocket 52 with respect to the first output shaft 48 is performed. Be blocked. As a result, the drive sprocket 52 is rotated integrally with the first output shaft 48, so that power is transmitted to the second output shaft 60 side via the drive sprocket 52, the chain 64, and the driven sprocket 62. Become. That is, the power transmission device 100 has a two-wheel drive state in which the power from the engine 12 is transmitted from the first output shaft 48 only to the rear wheel 16 by the second meshing clutch device 54, and the power from the engine 12 is transmitted to the rear wheel 16. In addition to transmitting, it is switched to a four-wheel drive state in which power is transmitted from the second output shaft 60 to the front wheels 14 (directly connected four-wheel drive state).

  When the power transmission device 100 is in the four-wheel drive state, the power distributed to the second output shaft 60 by the transfer 24 is input to the front differential 30 via the front propeller shaft 26. As shown in FIG. 1, a drive pinion 104 that is a bevel gear is provided at the end of the front propeller shaft 26, and the gear of the drive pinion 104 is engaged with a ring gear 106 that is a bevel gear of the front differential 30. It is configured. The ring gear 106 is fixed to a differential case (difference case) 108 and integrally rotates (revolves) around the axis of the axle 34.

  In this embodiment, a meshing clutch 38 as an ADD mechanism is provided between the front differential 30 and the front wheel 14R. Specifically, the axle 34R is divided into an axle 341R mechanically coupled to the front differential 30 side and an axle 342R mechanically coupled to the front wheel 14R side. The meshing clutch 38 is disposed between the axles 341R and 342R. The engagement clutch 38 switches between a connected state where power is transmitted between the axles 341R and 342R and a disconnected state where power transmission is cut off. The meshing clutch 38 is composed of, for example, a known dog clutch that selectively connects / disconnects between the axle 341R and the axle 342R, and an intermittent switching mechanism that selectively switches disconnection or connection of power transmission between the front differential 30 and the front wheel 14R. It functions as. That is, the meshing clutch 38 cuts off the power transmission path between the front differential 30 and the front wheel 14R in the disconnected state (released state), while in the connected state, the power transmission path between the front differential 30 and the front wheel 14R. Connect.

  Specifically, a clutch device (ADD device) 110 is configured by the meshing clutch 38 and an electric motor (ADD motor) 112 for switching the operating state (connected state or disconnected state) of the meshing clutch 38. In the clutch device 110, the operating state of the meshing clutch 38 is selectively switched by driving of the electric motor 112, and the connected state where the axles 341R and 342R are connected and the state where the axles 341R and 342R are disconnected. Is switched to the disconnected state. The motor load of the electric motor 112 is set in consideration of the transmission torque to the front wheel 14 side.

  As shown in FIG. 3, the meshing clutch 38 can be fitted to the outer peripheral teeth 130 formed on the outer peripheral portion of the axle shaft 341R, the outer peripheral teeth 134 formed on the outer peripheral portion of the axle shaft 342R, and the outer peripheral teeth 130, 134. And a cylindrical sleeve 138 on which inner peripheral teeth 136 are formed. A cylindrical annular groove (not shown) is formed on the outer peripheral side of the sleeve 138, and an engagement member 142 (see FIG. 1) is engaged with the annular groove. The engagement member 142 is moved along the axial direction (in FIG. 3, the direction of the axial center C3) by driving the electric motor 112, and the movement of the engagement member 142 causes the sleeve 138 to move in the axial direction. It is done.

  When the sleeve 138 is in the position shown in FIG. 3, the meshing clutch 38 is in a disconnected state. At this time, the sleeve 138 is moved toward the axle 342R in the axial direction, and the engagement between the outer peripheral teeth 130 of the axle 341R and the inner peripheral teeth 136 of the sleeve 138 is released. For this reason, the axles 341R and 342R are cut. 3, the sleeve 138 is moved toward the front differential 30 in the axial direction by driving the electric motor 112, so that the outer peripheral teeth 130 of the axle 341R and the inner peripheral teeth 136 of the sleeve 138 mesh with each other. Is done. As a result, the axles 341R and 342R are connected.

  When the meshing clutch 38 (clutch device 110) is in the disconnected state, the rotation state is as shown by the solid line arrow in FIG. 3, and when the meshing clutch 38 is in the connected state, the rotation is as shown by the broken line arrow in FIG. It becomes a state. Specifically, when the meshing clutch 38 is in a disconnected state, the front wheel 14L and the front wheel 14R rotate in the same rotational direction and at the same rotational speed. Accordingly, the axle 34L and the axle 342R rotate at the same rotational direction and at the same rotational speed. Similarly, the side gear 35L provided at the end of the axle 34L is rotated integrally with the axle 34L, and the pinion gear 39 meshing with the side gear 35L is rotated around the pinion shaft 37. Further, the axle 341R meshing with the pinion gear 39 is rotated in the reverse rotation direction and at the same rotation speed with respect to the axle 34L. That is, the axle 341R is rotated with respect to the axle 342R in the reverse rotation direction and at the same rotation speed. On the other hand, when the meshing clutch 38 is in the connected state, the axle 341R rotates at the same rotational speed and at the same rotational speed as the axle 342R. At this time, since the rotation of the axle 34L and the axle 34R becomes equal, the differential case 108 and the ring gear 106 are rotated together with the axle 34L and the axle 34R around the axis C3, while the rotation of the pinion gear 39 is stopped.

  The meshing clutch 38 (clutch device 110) is switched to a connected state when the power transmission device 100 is in a four-wheel drive state, and is switched to a disconnected state when the power transmission device 100 is in a two-wheel drive state. That is, when the power transmission device 100 is in the two-wheel drive state, the second mesh clutch device 54 is disconnected, and the power from the engine 12 is transmitted only to the left and right rear wheels 16 by the transfer 24. At this time, if the axles 341R and 342R are connected by the mesh clutch 38, the axle 34, the front differential 30, the front propeller shaft 26, the second output shaft 60, the driven sprocket 62, the chain 64, and the drive sprocket 52 are driven by the front wheels 14. Etc. are carried around. For this reason, in the power transmission device 100, torque in the deceleration direction (drag torque) is applied, and fuel consumption is reduced. Therefore, in conjunction with the switching of the power transmission device 100 to the two-wheel drive state, the power transmission between the front differential 30 and the front wheels 14R is interrupted by switching the meshing clutch 38 to the disconnected state. Thereby, even if the front wheel 14 rotates, the power transmission is interrupted in the front differential 30 and the front propeller shaft 26, the second output shaft 60, the chain 64, the drive sprocket 52, and the like are prevented from being rotated.

  When the power transmission device 100 is in the four-wheel drive state, when the axles 341R and 342R are connected by the meshing clutch 38, the power generated by the engine 12 and distributed by the transfer 24 is transferred to the front differential 30 via the front propeller shaft 26. To the left and right front wheels 14 via the axle 34. At this time, the remaining driving force distributed by the transfer 24 in which the second meshing clutch device 54 is connected is transmitted to the left and right rear wheels 16 via the rear propeller shaft 28, the rear differential 32, and the axle 36, respectively. Is done.

  The power transmission device 100 is controlled by an electronic control unit (ECU) 200 as a control device. The ECU 200 is configured to include, for example, a CPU, a ROM, a RAM, and the like. The ROM stores various control programs, maps that are referred to when the various control programs are executed, and the like. The CPU executes various arithmetic processes based on various control programs and maps stored in the ROM. The RAM is a memory that temporarily stores calculation results of the CPU, data input from each sensor, and the like. The ECU 200 performs signal processing according to a program stored in the ROM while using the temporary storage function of the RAM, thereby controlling the output of the engine 12, the shift control of the automatic transmission 22, the first and second meshing clutch devices 50, 54 switching control, clutch device 110 switching control, and the like are executed.

As shown in FIG. 1, the ECU 200 corresponds to, for example, a signal representing the engine rotation speed Ne detected by the engine rotation speed sensor 162 and the output rotation speed Npr of the rear propeller shaft 28 detected by the rear propeller rotation speed sensor 164. A signal representing the vehicle speed V, a signal representing the wheel speed Nfr, Nfl, Nrr, Nrl corresponding to the rotational speed Nw of each wheel (ie, the front wheels 14R, 14L, the rear wheels 16R, 16L) detected by each wheel speed sensor 166, A signal indicating the operation position Pdial of the driving state change dial switch 170 detected by the dial position sensor 168, a two-wheel driving state S _2WD corresponding to the power transmission state in the transfer 24 detected by the driving state detection switch (transfer switch) 172, and Table four-wheel drive state S _4WD Signal, the signal or the like is supplied indicating the connection state Son and disconnected Soff corresponding to operating conditions of the engagement clutch 38 of the clutch device 110 detected by the operation state detection switch (ADD switch) 174.

Further, from the ECU 200, for example, an engine output control command signal Se for output control of the engine 12, a shift control command signal St for shift control of the automatic transmission 22, and a shift actuator 84 via the first shift fork shaft 95. By operating the first meshing clutch device 50, the second shift is performed by the high / low switching control command signal Shl for shifting the gear stage of the auxiliary transmission 46 to the high speed side gear stage H or the low speed side gear stage L, and the shift actuator 84. A drive state switching control command signal S _{2-4 for} switching the drive state of the transfer 24 to the two-wheel drive state or the four-wheel drive state by operating the second meshing clutch device 54 via the fork shaft 97, by the electric motor 112 Front differential by operating the meshing clutch 38 ADD switch control command signal Sadd and the like for switching the cutting or connection of the power transmission path between the Le 30 and the front wheel 14R is output. The drive state switching dial switch 170 is, for example, a dial switch that is provided in the vicinity of the driver and is manually operated by the driver. The two-wheel drive state (H-2WD) in the high-speed side gear stage H, and the high-speed side gear. Three operation positions Pdial are provided for instructing switching to a four-wheel drive state (H-4WD) at the stage H and a four-wheel drive state (L-4WD) at the low-speed gear stage L. Yes. The driving state switching dial switch 170 is not limited to a dial type, and may be, for example, a slide type or a seesaw type.

The ECU 200 executes switching control of the transfer 24 based on a signal indicating the operation position Pdial of the drive state switching dial switch 170. Specifically, when the operation position Pdial is a signal indicating the two-wheel drive state (H-2WD), the ECU 200 switches the high / low switching control signal Shl for switching the gear stage of the auxiliary transmission 46 to the high speed side gear stage H. Is output to the shift actuator 84 and the first meshing clutch device 50 is operated via the first shift fork shaft 95 to switch the gear stage of the sub-transmission 46 to the high speed side gear stage H. In addition, the ECU 200 outputs a drive state switching control command signal S _2-4 for switching the drive state of the transfer 24 to the two-wheel drive state to the shift actuator 84, and the second meshing clutch via the second shift fork shaft 97. The device 54 is cut off.

On the other hand, when the operation position Pdial is a signal indicating the four-wheel drive state (H-4WD), the ECU 200 sets the gear stage of the auxiliary transmission 46 to the high speed side as in the two-wheel drive state (H-2WD). A high / low switching control command signal Shl for switching to the gear stage H is output to the shift actuator 84. In addition, the ECU 200 outputs a drive state switching control command signal S _2-4 for switching the drive state of the transfer 24 to the four-wheel drive state to the shift actuator 84, and the second meshing via the second shift fork shaft 97. The clutch device 54 is brought into a connected state.

On the other hand, when the operation position Pdial is a signal representing the four-wheel drive state (L-4WD), the ECU 200 generates a high / low switching control command signal Shl for switching the gear stage of the auxiliary transmission 46 to the low speed side gear stage L. The gear stage of the sub-transmission 46 is switched to the low-speed gear stage L by outputting to the shift actuator 84 and operating the first meshing clutch device 50 via the first shift fork shaft 95. In addition, the ECU 200 sends a drive state switching control command signal S _2-4 for switching the drive state in the transfer 24 to the four-wheel drive state to the shift actuator 84 as in the case of the four-wheel drive state (H-4WD). Output.

  In addition, ECU 200 executes switching control of meshing clutch 38 of clutch device 110 based on a signal indicating operation position Pdial of driving state switching dial switch 170. Specifically, when the operation position Pdial is a signal representing the two-wheel drive state (H-2WD), the ECU 200 adds an ADD switching control command for interrupting the power transmission path between the front differential 30 and the front wheels 14. The signal Sadd is output to the electric motor 112, and the meshing clutch 38 is disengaged. On the other hand, when the operation position Pdial is a signal indicating either the four-wheel drive state (H-4WD) or the four-wheel drive state (L-4WD), the ECU 200 determines the power between the front differential 30 and the front wheels 14. An ADD switching control command signal Sadd for connecting the transmission path is output to the electric motor 112, and the meshing clutch 38 is brought into a connected state.

  Next, an example of switching control from the four-wheel drive state to the two-wheel drive state performed in the power transmission device 100 will be described with reference to FIG. The flowchart shown in FIG. 4 relates to switching control from the four-wheel drive state (H-4WD) to the two-wheel drive state (H-2WD), and is executed by the ECU 200 at regular intervals.

First, in step ST1, the ECU 200 determines whether or not a command signal for switching from the four-wheel drive state (H-4WD) to the two-wheel drive state (H-2WD) has been output. This determination can be made based on the drive state switching control command signal S _2-4 from the operation position Pdial of the drive state switching dial switch 170. If the determination result of step ST1 is affirmative (Yes), the process proceeds to step ST2. On the other hand, if the determination result in step ST1 is negative (No), the process returns.

  Next, in step ST2, the ECU 200 determines whether the vehicle speed is less than a predetermined vehicle speed V1. This determination can be made based on a signal representing the vehicle speed V corresponding to the output rotational speed Npr of the rear propeller shaft 28 detected by the rear propeller rotational speed sensor 164. If the determination result of step ST2 is affirmative (Yes), the process proceeds to step ST3. On the other hand, when the determination result of step ST2 is negative (No), the process is in a standby state.

  Next, in step ST3, the ECU 200 energizes the shift actuator 84 to drive the shift actuator 84 in order to switch the second meshing clutch device 54 of the transfer 24 to the disconnected state. As a result, the sleeve 90 of the second meshing clutch device 54 is moved in the direction to release the connection with the clutch gear 92, and the transfer 24 changes from the four-wheel drive state (H-4WD) to the two-wheel drive state (H-2WD). Switching starts.

Next, in step ST4, the ECU 200 determines whether or not the switching of the second meshing clutch device 54 to the disconnected state has been completed. That is, it is determined whether or not the transfer 24 has been switched from the four-wheel drive state (H-4WD) to the two-wheel drive state (H-2WD). This determination can be made based on a signal indicating the power transmission state in the transfer 24 detected by the transfer switch 172. If this signal is a signal indicating the two-wheel drive state _S2WD , an affirmative determination (Yes) If the signal is a signal representing the four-wheel drive state S _4WD , a negative determination (No) is made. If the determination result of step ST4 is affirmative (Yes), it is determined that the switching of the second mesh clutch device 54 to the disconnected state is completed, and the process proceeds to step ST6. On the other hand, if the determination result of step ST4 is negative (No), it is determined that the switching of the second meshing clutch device 54 to the disconnected state has not been completed, and the process proceeds to step ST5.

  Next, in step ST5, the ECU 200 determines whether or not the switching time t1 for switching the second meshing clutch device 54 to the disconnected state has passed a predetermined set time T1. This switching time t1 is the drive time (energization time) of the shift actuator 84, and is measured from the drive start time (energization start time) of the shift actuator 84 in step ST3. In the set time T1, the sliding resistance of the sleeve 90 of the second mesh clutch device 54 increases due to the circulating torque accumulated in the power transmission device 100 during traveling in the four-wheel drive state, and the second mesh clutch device. Considering that the switching time t1 of 54 becomes long, etc., it is determined in advance by experiment, simulation or the like. If the determination result of step ST5 is affirmative (Yes), the process proceeds to step ST9. On the other hand, if the determination result of step ST4 is negative (No), the process proceeds to step ST4.

  Next, in step ST6, the ECU 200 stops energization of the shift actuator 84 to stop the shift actuator 84, and switches the meshing clutch 38 of the clutch device 110 to the disconnected state so that the front differential 30 and the front wheel 14R are disconnected. In order to cut the power transmission path, the electric motor 112 is energized to drive the electric motor 112. As a result, the sleeve 138 of the meshing clutch 38 is moved in a direction to release the connection with the axle 341R, and the switching of the meshing clutch 38 to the disconnected state is started.

  Next, in step ST7, the ECU 200 determines whether or not the switching of the meshing clutch 38 to the disconnected state has been completed. That is, it is determined whether or not the power transmission path between the front differential 30 and the front wheel 14R is disconnected. This determination can be made based on a signal indicating the operating state of the meshing clutch 38 detected by the ADD switch 174. If this signal is a signal indicating the disconnected state Soff, the determination is affirmative (Yes), If the signal is a signal representing the connection state Son, a negative determination (No) is made. If the determination result of step ST7 is affirmative (Yes), it is determined that the switching of the meshing clutch 38 to the disengaged state is completed, and the process proceeds to step ST8. On the other hand, when the determination result of step ST7 is negative (No), the process is in a standby state until the switching of the meshing clutch 38 to the disconnected state is completed.

  Next, in step ST8, the ECU 200 stops energization of the electric motor 112 and stops the electric motor 112.

  In step ST9, the ECU 200 stops energization of the shift actuator 84 to stop the shift actuator 84, and switches the meshing clutch 38 to a disconnected state so that a power transmission path between the front differential 30 and the front wheels 14R is established. In order to cut, the electric motor 112 is energized to drive the electric motor 112. In this case, the movement of the sleeve 90 of the second meshing clutch device 54 is stopped by the stop of the shift actuator 84, and the transfer 24 is switched from the four-wheel drive state (H-4WD) to the two-wheel drive state (H-2WD). Once stopped (interrupted). Then, the drive of the electric motor 112 moves the sleeve 138 of the meshing clutch 38 in a direction to release the connection with the axle 341R, and the switching of the meshing clutch 38 to the disconnected state is started.

  Next, in step ST10, the ECU 200 determines whether or not the switching of the meshing clutch 38 to the disconnected state has been completed. This determination is the same as the determination in step ST7. If the determination result of step ST10 is affirmative (Yes), the process proceeds to step ST12. On the other hand, when the determination result of step ST10 is negative (No), the process proceeds to step ST11.

  Next, in step ST11, the ECU 200 determines whether or not the switching time t2 for switching the engagement clutch 38 to the disconnected state has passed a predetermined set time T2. This switching time t2 is the drive time (energization time) of the electric motor 112, and is measured from the drive start time (energization start time) of the electric motor 112 in step ST9. The set time T2 takes into consideration that, in the four-wheel drive state, the sliding resistance of the sleeve 138 of the meshing clutch 38 increases according to the transmission torque to the front wheel 14 side, and the switching time t2 of the meshing clutch 38 becomes longer. Thus, it is determined in advance by experiment, simulation, or the like. If the determination result in step ST11 is affirmative (Yes), the process proceeds to step ST15. On the other hand, if the determination result of step ST11 is negative (No), the process proceeds to step ST10.

  Next, in step ST12, the ECU 200 stops energization of the electric motor 112 to stop the electric motor 112 and restarts energization of the shift actuator 84 in order to switch the second meshing clutch device 54 to the disconnected state. The shift actuator 84 is driven again. By re-driving the shift actuator 84, the movement of the sleeve 90 of the second meshing clutch device 54 stopped in step ST9 is resumed, and the transfer 24 is switched from the four-wheel drive state (H-4WD) to the two-wheel drive state (H-2WD). ) Is resumed.

  Next, in step ST13, the ECU 200 determines whether or not the switching of the second meshing clutch device 54 to the disconnected state has been completed. This determination is the same as the determination in step ST4. If the determination result of step ST13 is affirmative (Yes), it is determined that the switching of the second mesh clutch device 54 to the disconnected state is completed, and the process proceeds to step ST14. On the other hand, when the determination result of step ST13 is negative (No), the process is in a standby state until the switching of the second meshing clutch device 54 to the disconnected state is completed.

  Next, in step ST14, the ECU 200 stops energization of the shift actuator 84 and stops the shift actuator 84.

  Next, in step ST15, the ECU 200 stops energization of the electric motor 112 to stop the electric motor 112, and resumes energization to the shift actuator 84 in order to switch the second meshing clutch device 54 to the disconnected state. The shift actuator 84 is driven again. In this case, when the electric motor 112 is stopped, the movement of the sleeve 138 of the meshing clutch 38 is stopped, and the switching of the meshing clutch 38 to the disconnected state is temporarily stopped (interrupted). Then, by re-driving the shift actuator 84, the movement of the sleeve 90 of the second meshing clutch device 54 that has been stopped in step ST9 is resumed, and the transfer 24 is switched from the four-wheel drive state (H-4WD) to the two-wheel drive state (H -2WD) is resumed. Then, after step ST15, the process proceeds to step ST4.

  In this embodiment, when switching from the four-wheel drive state (H-4WD) to the two-wheel drive state (H-2WD), switching to the two-wheel drive state by the transfer 24 (second mesh clutch device 54) has not been completed. When the set time T1 has elapsed since the start of switching to the two-wheel drive state (Yes in step ST5), the clutch device 110 (meshing clutch 38) is started to be switched to the disconnected state (step ST9). More specifically, after the set time T1 has elapsed, the switching to the two-wheel drive state by the second meshing clutch device 54 is stopped (step ST9), and after the switching to the disconnected state of the clutch device 110 is completed (Yes in step ST10). ), The switching to the two-wheel drive state by the second meshing clutch device 54 is resumed (step ST12).

  Thus, after the set time T1 elapses, the meshing clutch 38 is switched to the disengaged state, so that the circulating torque accumulated in the power transmission device 100 is released during traveling in the four-wheel drive state. Switching to the two-wheel drive state by the device 54 can be performed without being hindered by the circulating torque. That is, the circulating torque accumulated in the power transmission device 100 is eliminated by disconnecting the power transmission path between the front differential 30 and the front wheel 14R by switching the meshing clutch 38 to the disconnected state. Thereby, the sliding resistance of the sleeve 90 due to the circulating torque is eliminated, and the second meshing clutch device 54 can be quickly switched to the disconnected state. Therefore, the switching time from the four-wheel drive state to the two-wheel drive state can be shortened, and the switching performance from the four-wheel drive state to the two-wheel drive state can be improved.

  Here, even when the load (motor load) of the shift actuator 84 is insufficient compared with the accumulated circulating torque and it is difficult to switch the second meshing clutch device 54 to the disconnected state, the meshing clutch 38 is disconnected. By releasing the circulating torque accompanying the switching to the state, the shift actuator 84 can easily switch the second meshing clutch device 54 to the disconnected state. That is, if the motor load of the electric motor 112 is sufficiently large compared to the transmission torque to the front wheel 14 in the four-wheel drive state, the engagement clutch 38 can be easily switched to the disengaged state. The switching of the meshing clutch device 54 to the disconnected state is stopped, the switching of the meshing clutch 38 to the disconnected state is performed, and after the switching of the meshing clutch 38 to the disconnected state, the second meshing clutch device 54 is switched to the disconnected state. The switching is resumed.

  On the other hand, when the motor load of the electric motor 112 is insufficient and the switching time t2 of the meshing clutch 38 becomes longer than the torque transmitted to the front wheel 14 in the four-wheel drive state, the meshing clutch 38 is disconnected. The switching to the state is stopped and the switching of the second meshing clutch device 54 to the disconnected state is resumed. The switching of the second meshing clutch device 54 to the disconnected state and the switching of the meshing clutch 38 to the disconnected state are respectively performed. Are alternately performed at the set times T1 and T2. In this way, the transmission torque to the front wheel 14 side when the second meshing clutch device 54 is switched to the disconnected state is gradually cut off, and the circulation torque is released when the meshing clutch 38 is switched to the disconnected state. Thus, the total of the switching time t1 of the second meshing clutch device 54 and the switching time t2 of the meshing clutch 38 is shortened as a whole to improve the switching performance from the four-wheel drive state to the two-wheel drive state.

  In the above embodiment, the power transmission device 100 for a four-wheel drive vehicle based on an FR type vehicle has been described. However, the power of a four-wheel drive vehicle based on an FF (front engine / front drive) type vehicle has been described. The present invention can also be applied to a transmission device.

  In the above embodiment, the power transmission device 100 including the transfer 24 having the auxiliary transmission function has been described. However, the present invention can also be applied to a power transmission device including a transfer having no auxiliary transmission function. Moreover, although the case where the clutch device 110 (meshing clutch 38) is provided on the axle 34R side has been described in the above embodiment, the clutch device may be provided on the axle 34L side.

  The present invention relates to a transfer that can be switched between a two-wheel drive state and a four-wheel drive state, and one of the left and right wheels that are driven wheels in the two-wheel drive state, and a difference provided between the left and right wheels. The present invention is applicable to a power transmission device of a four-wheel drive vehicle including a clutch device that switches disconnection or connection of power transmission with a moving device.

14L, 14R Front wheel 24 Transfer 30 Front differential (differential device)
38 meshing clutch 54 second meshing clutch device (2WD / 4WD switching device)
DESCRIPTION OF SYMBOLS 100 Power transmission device 110 Clutch device 200 ECU
T1 set time

Claims (4)

A transfer capable of switching between a two-wheel drive state and a four-wheel drive state;
When in the two-wheel drive state, it is switched to a disconnected state in which power transmission is not performed between one of the left and right wheels to be driven wheels and a differential provided between the left and right wheels, A power transmission device for a four-wheel drive vehicle comprising a clutch device that is switched to a connected state for transmitting power between the differential and the one wheel when in a four-wheel drive state;
When switching from the four-wheel drive state to the two-wheel drive state, even if the transfer to the two-wheel drive state by the transfer has not been completed, if the set time has elapsed since the start of switching to the two-wheel drive state, the clutch 4. A power transmission device for a four-wheel drive vehicle, wherein switching of the device to the cut state is started. The power transmission device for a four-wheel drive vehicle according to claim 1,
When the set time has elapsed since the start of switching to the two-wheel drive state, the switching to the two-wheel drive state by the transfer is stopped, and then the switching of the clutch device to the disengaged state is started. Power transmission device for four-wheel drive vehicles. The power transmission device for a four-wheel drive vehicle according to claim 2,
A power transmission device for a four-wheel drive vehicle, wherein after the switching of the clutch device to the disengaged state is completed, switching to the two-wheel drive state by the transfer is resumed. The power transmission device for a four-wheel drive vehicle according to claim 2,
When a second set time has elapsed from the start of switching the clutch device to the disengaged state, the clutch device stops switching to the disengaged state and resumes switching to the two-wheel drive state by the transfer. A power transmission device for a four-wheel drive vehicle.

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