JP2016210325A - Four-wheel-drive vehicular control apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a four-wheel-drive vehicular control apparatus for improving response in switching from a two-wheel-drive state to a four-wheel-drive state by controlling the position of a pressure application piston of a clutch at clutch release in accordance with a magnitude of relative rotation speed at input-output elements of the clutch at clutch release in addition to a degree of temperature of the clutch.SOLUTION: A clutch gap C is changed in accordance with both an oil temperature T of a transfer 22 and a vehicular speed V, and a position of a piston 82 at clutch release, where a front wheel-driving clutch 50 is released by the clutch gap C, is changed. Therefore, compared to a conventional case of changing a piston position in accordance with only a clutch temperature, it is possible to cause a standby position of the piston 82 to approach a position where the front wheel-driving clutch 50 is stated to press while dragging torque at a given value or less is maintained in a case where relative rotation torque of a friction engagement element 80 of the front wheel-driving clutch 50 is high, enabling response in switching from a two-wheel-drive state to a four-wheel-drive state to be further improved.SELECTED DRAWING: Figure 5

Description

  The present invention includes a two-wheel drive state in which a driving force is transmitted from a driving source to left and right main driving wheels by releasing a multi-plate clutch, and a left and right auxiliary driving wheel from the driving source by engaging the multi-plate clutch. The present invention relates to a technique for improving the switching response from a two-wheel drive state to a four-wheel drive state in a four-wheel drive vehicle in which a four-wheel drive state that transmits a driving force is selected.

  Patent Document 1 describes a differential device with a differential limiting function in which a multi-plate clutch is provided between a differential case and one of a pair of side gears (power transmission path). In the multi-plate clutch, the motor moves the piston against the biasing force of the reaction spring via a ball cam in which a ball is sandwiched between the first cam plate and the second cam plate, and the multi-plate clutch is engaged. The position of the piston in the multi-plate clutch at the time of non-differential restriction is changed according to the oil temperature change of the differential device, and the clutch clearance accompanying the dimensional change of the parts of the multi-plate clutch due to the oil temperature change Thus, the decrease in the response to the differential limited state due to the increase in the clearance of the multi-plate clutch and the increase in the drag torque due to the decrease in the clearance are suppressed.

JP 2008-223869 A

  By the way, the multi-plate clutch of the differential device as described above is used as, for example, a clutch that connects and disconnects the power transmission path between the drive source and the power transmission member, and is released from the drive source by releasing the multi-plate clutch. A two-wheel driving state in which driving force is transmitted to the left and right main driving wheels and a four-wheel driving state in which driving force is transmitted from the driving source to the left and right auxiliary driving wheels by engaging a multi-plate clutch are selected. It can be considered to be applied to a four-wheel drive vehicle.

  However, when the multi-plate clutch is applied as a sub-drive wheel drive clutch of a transfer of a four-wheel drive vehicle with a disconnect function, which will be described later, the relative rotational speed of the input / output elements of the clutch when the clutch is released and changes thereof In view of the change in the magnitude of the clutch drag torque accompanying the change, there is room for improvement in the clutch control method.

  The present invention has been made against the background of the above circumstances. The purpose of the present invention is to increase the relative rotational speed of the input / output elements of the clutch when the clutch is released, in addition to the temperature of the clutch. Accordingly, an object of the present invention is to provide a control device for a four-wheel drive vehicle that improves the switching responsiveness from the two-wheel drive state to the four-wheel drive state by controlling the position of the pressing piston of the clutch when the clutch is released.

  To achieve the above object, the gist of the present invention is that: (a) a multi-plate clutch that connects and disconnects a power transmission path between a drive source and a power transmission member; A two-wheeled wheel that includes a connecting / disconnecting clutch that connects / disconnects a power transmission path to / from the wheels, and that transmits the driving force from the driving source to the left and right main driving wheels by releasing the connecting / disconnecting clutch and the multi-plate clutch. A four-wheel drive vehicle in which a driving state and a four-wheel driving state in which a driving force is transmitted from the driving source to the left and right auxiliary driving wheels by engaging the connecting / disconnecting clutch and the multi-plate clutch are selected. And (b) a clutch driving device for driving a piston of the multi-plate clutch by a motor and a screw mechanism for converting the rotational motion of the motor into a linear motion, and (c) the multi-plate Clutch temperature or The clutch driving device is controlled so as to change the position of the piston when the multi-plate clutch is released according to both the estimated temperature and the relative rotational speed of the clutch input / output element of the multi-plate clutch. (D) the clutch control means, the higher the clutch temperature of the multi-plate clutch or its estimated temperature, the higher the relative rotational speed of the clutch input / output elements of the multi-plate clutch, The standby position of the piston is brought close to a reference position where the pressing of the multi-plate clutch is started.

  According to the four-wheel drive vehicle configured as described above, the multi-plate clutch according to both the clutch temperature of the multi-plate clutch or its estimated temperature and the relative rotational speed of the clutch input / output element of the multi-plate clutch. Since the position of the piston when the clutch is released is changed, the relative rotation of the input / output elements of the multi-plate clutch is higher than when the piston position is changed only according to the conventional clutch temperature. Can maintain the drag torque below a predetermined value and move the standby position of the piston closer to the position where the multi-plate clutch starts to be pressed, switching from the two-wheel drive state to the four-wheel drive state. Responsiveness can be further improved.

  Here, preferably, the screw mechanism includes a rotating member driven by the motor and a nut member screwed into the rotating member to drive the piston. For this reason, compared with the case where the nut member is driven by a motor, the nut member moves by the action of a screw when the rotary member is rotated by the motor in the screw mechanism, and the piston is moved. Moves to a predetermined position.

  Preferably, the rotation angle of the motor is determined based on the position of the piston stored in the control device of the four-wheel drive vehicle at the time of starting to press the multi-plate clutch. For this reason, since the position of the piston can be suitably moved to a predetermined position by the motor based on the piston position at the start of pressing, high positioning accuracy can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining schematic structure of the vehicle to which this invention is applied, and is a figure explaining the principal part of the control system for the various control in a vehicle. It is a skeleton diagram explaining the schematic structure of a transfer. FIG. 3 is a cross-sectional view illustrating a schematic configuration of a front wheel drive clutch that is a multi-plate clutch provided in the transfer of FIG. 2. The figure which shows the relationship between the clutch clearance of a front-wheel drive clutch and the drag torque of a front-wheel drive clutch, and the figure which shows the relationship between the clutch clearance of a front-wheel drive clutch and the clutch engagement time of a front-wheel drive clutch are represented. FIG. It is a figure which shows the image of the map which changes a clutch clearance gap according to both the oil temperature of a transfer, and a vehicle speed in the clutch clearance change control part of the electronic controller of FIG. 2 is a flowchart for explaining an example of a control operation of clutch control of a multi-plate clutch in which the travel mode of the vehicle is changed and the position of a piston is moved by the clutch drive device during travel of the vehicle in the electronic control device of FIG. 1.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios, shapes, and the like of the respective parts are not necessarily drawn accurately.

  FIG. 1 is a diagram illustrating a schematic configuration of a vehicle (four-wheel drive vehicle) 10 to which the present invention is applied, and also illustrates a main part of a control system for various controls in the vehicle 10. In FIG. 1, a vehicle 10 includes an engine 12 as a drive source, left and right front wheels 14L and 14R (front wheels 14 unless otherwise specified), and left and right rear wheels 16L and 16R (respectively rear wheels 16 unless otherwise specified). A vehicle power transmission device 18 (hereinafter referred to as a power transmission device 18) for transmitting the power of the engine 12 to the front wheels 14 and the rear wheels 16, respectively. The rear wheel 16 is a main drive wheel that serves as a drive wheel during two-wheel drive (2WD) traveling and four-wheel drive (4WD) traveling. The front wheel 14 is a sub driving wheel that becomes a driven wheel when traveling in 2WD and a driving wheel when traveling in 4WD. Accordingly, the vehicle 10 is a four-wheel drive vehicle based on a front engine rear wheel drive (FR).

  The power transmission device 18 includes a transmission 20 connected to the engine 12, a transfer 22 that is a front and rear wheel power distribution device connected to the transmission 20, and a front propeller shaft (power transmission member) connected to the transfer 22. 24), the rear propeller shaft 26, the front wheel differential gear device 28 connected to the front propeller shaft 24, the rear wheel differential gear device 30 connected to the rear propeller shaft 26, and the front wheel differential gear device 28. Left and right front wheel axles 32L and 32R (referred to as front wheel axle 32 unless otherwise specified), and left and right rear wheel axles 34L and 34R connected to the rear wheel differential gear device 30 (respectively indicated unless otherwise specified) A wheel axle 34). In the power transmission device 18 configured as described above, the power of the engine 12 transmitted to the transfer 22 via the transmission 20 is transmitted from the transfer 22 to the rear propeller shaft 26, the rear wheel differential gear device 30, and the rear wheel. The power is transmitted to the rear wheel 16 via the power transmission path on the rear wheel side such as the axle 34. Further, a part of the power of the engine 12 transmitted to the rear wheel 16 side is distributed to the front wheel 14 side by the transfer 22, and the front wheels such as the front propeller shaft 24, the front wheel differential gear device 28, the front wheel axle 32, and the like. The power is transmitted to the front wheels 14 sequentially through the power transmission path on the side.

  The front wheel differential gear device 28 includes a front side clutch (connection / disconnection clutch) 36 on the front wheel axle 32R side (that is, between the front wheel differential gear device 28 and the front wheel 14R). The front side clutch 36 selectively connects or disconnects the power transmission path between the front wheel differential gear device 28 and the front wheel 14R, that is, the power transmission path between the front propeller shaft 24 and the left and right front wheels 14L, 14R. This is a dog clutch (that is, a meshing clutch) that is electrically (electromagnetically) controlled. The front side clutch 36 may further include a synchronization mechanism (synchronization mechanism).

  FIG. 2 is a skeleton diagram illustrating a schematic configuration of the transfer 22, and FIG. 3 is an enlarged cross-sectional view of a part of the transfer 22. In FIG. 2, the transfer 22 includes a transfer case 40 as a non-rotating member. In the transfer case 40, the transfer 22 includes an input shaft 42 as an input rotation member, and a rear wheel side output shaft 44 as a first output rotation member that outputs power to the rear wheels 16 as left and right main drive wheels. A drive gear 46 as a second output rotating member that outputs power to the front wheels 14 as the left and right auxiliary driving wheels, and an auxiliary transmission that changes the rotation of the input shaft 42 and transmits it to the rear wheel side output shaft 44 And a front wheel drive clutch 50 as a multi-plate clutch for adjusting a transmission torque transmitted from the rear wheel side output shaft 44 to the drive gear 46 is provided around a common axis C1. The transfer 22 includes a front wheel side output shaft 52 and a driven gear 54 provided integrally with the front wheel side output shaft 52 around the common axis C2 in the transfer case 40, and further includes a drive gear 46. A front-wheel drive chain 56 that connects the driven gear 54 and a differential lock mechanism 58 as a dog clutch that integrally connects the rear-wheel-side output shaft 44 and the drive gear 46 are provided.

  The input shaft 42 is connected to an output rotating member (not shown) of the transmission 20 via a spline fitting joint or the like, and is rotated by driving force (torque) input from the engine 12 via the transmission 20. . The rear wheel side output shaft 44 is a main drive shaft connected to the rear propeller shaft 26. The drive gear 46 is supported by the rear wheel side output shaft 44 so as to be rotatable relative to the rear wheel side output shaft 44 around the axis C1. The front wheel side output shaft 52 is a sub drive shaft connected to the front propeller shaft 24.

  The transfer 22 configured as described above adjusts the torque transmitted to the drive gear 46, for example, to transmit the power transmitted from the transmission 20 only to the rear wheel 16, or to each of the front wheel 14 and the rear wheel 16. To distribute. The transfer 22 is, for example, a differential state in which the rotational differential between the rear propeller shaft 26 and the front propeller shaft 24 is not limited, and a non-differential state in which the rotational differential between them is limited (so-called center diff lock state). ). Further, the transfer 22 establishes, for example, either a high-speed gear stage (high-speed gear stage) H or a low-speed gear stage (low-speed gear stage) L to shift the rotation from the transmission 20 to the subsequent stage. introduce. That is, the transfer 22 transmits the rotation of the input shaft 42 to the rear wheel side output shaft 44 through the high / low switching mechanism 48, and the transmission torque through the front wheel driving clutch 50 is made zero and the diff lock mechanism 58 is released. In this state, power is not transmitted from the rear wheel output shaft 44 to the front wheel output shaft 52, but torque is transmitted through the front wheel drive clutch 50 or the diff lock mechanism 58 is engaged. In this state, power is transmitted from the rear wheel side output shaft 44 to the front wheel side output shaft 52 via the drive gear 46, the front wheel drive chain 56, and the driven gear 54.

  Specifically, the high / low switching mechanism 48 includes a single pinion type planetary gear device 60 and a high / low sleeve 62. The planetary gear device 60 is disposed so as to be substantially concentric with the sun gear S, which is connected to the input shaft 42 so as not to rotate relative to the input shaft 42 around the axis C1, and relative to the transfer case 40 about the axis C1. A ring gear R that is non-rotatably connected and a carrier CA that supports the sun gear S and a plurality of pinion gears P meshing with the ring gear R so as to be capable of rotating and revolving around the sun gear S are provided. Therefore, the rotational speed of the sun gear S is constant with respect to the input shaft 42, and the rotational speed of the carrier CA is decelerated with respect to the input shaft 42. High side gear teeth 64 are fixed to the inner peripheral surface of the sun gear S, and low side gear teeth 66 having the same diameter as the high side gear teeth 64 are fixed to the carrier CA. The high-side gear teeth 64 are spline teeth that are involved in the establishment of the high-speed side gear stage H that outputs a rotation at the same speed as the input shaft 42. The low-side gear teeth 66 are spline teeth that are involved in the establishment of the low-speed side gear stage L that outputs rotation at a lower speed side than the high-side gear teeth 64. The high / low sleeve 62 is spline-fitted to the rear wheel side output shaft 44 so as to be relatively movable in a direction parallel to the axis C1, and is integrally provided adjacent to the fork connecting portion 62a and the fork connecting portion 62a. Further, there are outer peripheral teeth 62b that mesh with the high-side gear teeth 64 and the low-side gear teeth 66 by movement in the direction parallel to the axis C1 of the rear wheel side output shaft 44, respectively. The high side gear teeth 64 and the outer peripheral teeth 62b mesh with each other, whereby the rotation of the input shaft 42 and the rotation at the same speed are transmitted to the rear wheel side output shaft 44, and the low side gear teeth 66 and the outer peripheral teeth 62b mesh with each other. The rotation decelerated with respect to the rotation of the input shaft 42 is transmitted to the rear wheel output shaft 44. The high side gear teeth 64 and the high / low sleeve 62 function as a high speed side gear stage clutch that forms the high speed side gear stage H, and the low side gear teeth 66 and the high / low sleeve 62 form the low speed side gear stage L. Functions as a low speed gear clutch. The high / low switching mechanism 48 enters a power transmission cut-off state (neutral state) when the high / low sleeve 62 does not mesh with either the high side gear teeth 64 or the low side gear teeth 66, and the high speed side gear stage H and the low speed side gear stage. When the gear stage is switched with L, it is switched after this power transmission cut-off state.

  The differential lock mechanism 58 is spline-fitted to the lock teeth 68 fixed to the inner peripheral surface of the drive gear 46 and the rear wheel side output shaft 44 so as to be relatively movable in a direction parallel to the axis C1. The outer peripheral teeth 70a meshing with the lock teeth 68 by the movement in the direction parallel to the lock sleeve 70 are fixed to the outer peripheral surface. In the engaged state of the differential lock mechanism 58 in which the outer peripheral teeth 70a of the lock sleeve 70 and the lock teeth 68 are engaged with each other, the transfer 22 rotates the rear wheel side output shaft 44 and the drive gear 46 integrally, and the center differential lock A state is formed.

  The high / low sleeve 62 is provided in a space on the drive gear 46 side with respect to the support bearing 71 of the input shaft 42 (more specifically, with respect to the planetary gear device 60). The lock sleeve 70 is provided as a separate member adjacent to the high / low sleeve 62 in the space between the high / low switching mechanism 48 and the drive gear 46. The transfer 22 abuts between the high / low sleeve 62 and the lock sleeve 70 and urges the high / low sleeve 62 and the lock sleeve 70 toward the side away from each other. 72). The transfer 22 abuts against the convex portion 44 a of the rear wheel side output shaft 44 and the lock sleeve 70 between the drive gear 46 and the lock sleeve 70 and biases the lock sleeve 70 away from the lock teeth 68. 2 springs 74 (hereinafter referred to as second springs 74). The convex portion 44 a is a flange portion of the rear wheel side output shaft 44 provided to protrude toward the lock teeth 68 in the radially inner space of the drive gear 46. The high side gear teeth 64 are provided at a position farther from the lock sleeve 70 than the low side gear teeth 66 when viewed in a direction parallel to the axis C1. The outer peripheral teeth 62b of the high / low sleeve 62 mesh with the high side gear teeth 64 on the side where the high / low sleeve 62 is separated from the lock sleeve 70 (left side in FIG. 2), and the side where the high / low sleeve 62 approaches the lock sleeve 70 (FIG. 2). At the right side of FIG. The outer peripheral teeth 70a of the lock sleeve 70 mesh with the lock teeth 68 on the side where the lock sleeve 70 approaches the drive gear 46 (right side in FIG. 2). Accordingly, the outer peripheral teeth 70 a of the lock sleeve 70 mesh with the lock teeth 68 at a position where the high / low sleeve 62 meshes with the low-side gear teeth 66.

  The front-wheel drive clutch 50 includes a clutch hub 76 that is non-rotatably connected to the rear-wheel output shaft 44, a clutch drum 78 that is non-rotatably connected to the drive gear 46, a clutch hub 76, and a clutch drum 78. It is a multi-plate friction clutch comprising a friction engagement element (clutch input / output element) 80 that is inserted between the two and selectively connects and disconnects them, and a piston 82 that presses the friction engagement element 80. The front wheel drive clutch 50 is disposed around the axis C1 of the rear wheel output shaft 44 on the opposite side of the drive gear 46 from the high / low switching mechanism 48 in the direction of the axis C1 of the rear wheel output shaft 44. The friction engagement element 80 is pressed by the piston 82 that moves toward the drive gear 46. The front-wheel drive clutch 50 is moved to the non-pressing side (the right side in FIG. 3), which is the side where the piston 82 is separated from the drive gear 46 in the direction parallel to the axis C1, and does not contact the friction engagement element 80. Then, it becomes a release state. On the other hand, the front-wheel drive clutch 50 is moved to the pressing side (the left side in FIG. 3) that is close to the drive gear 46 in the direction parallel to the shaft center C <b> 1 and contacts the friction engagement element 80. In the state, the transmission torque (torque capacity) is adjusted according to the movement amount of the piston 82, and the slip state or the engaged state is established. The front-wheel drive clutch 50 is a multi-plate clutch that is provided in a power transmission path between the engine 12 and the front propeller shaft 24 and connects and disconnects the power transmission path.

  In the released state of the front wheel drive clutch 50 and the released state of the differential lock mechanism 58 in which the outer peripheral teeth 70a of the lock sleeve 70 and the lock teeth 68 are not engaged, the transfer 22 is located between the rear wheel side output shaft 44 and the drive gear 46. Is interrupted, and the power transmitted from the transmission 20 is transmitted only to the rear wheels 16. The transfer 22 distributes the power transmitted from the transmission 20 to each of the front wheels 14 and the rear wheels 16 when the front wheel drive clutch 50 is in a slip state or an engaged state. In the slip state of the front-wheel drive clutch 50, the transfer 22 is allowed to rotate differentially between the rear-wheel output shaft 44 and the drive gear 46, and a differential state (non-center differential lock state) is formed. When the front wheel drive clutch 50 is engaged, the transfer 22 is rotated integrally with the rear wheel output shaft 44 and the drive gear 46 to form a center differential lock state. The front-wheel drive clutch 50 can continuously change the torque distribution between the front wheels 14 and the rear wheels 16, for example, between 0: 100 and 50:50 by controlling the transmission torque.

  The transfer 22 is a device for operating the high / low switching mechanism 48, the front wheel drive clutch 50, and the differential lock mechanism 58, a motor 84, a screw mechanism 86 that converts the rotational motion of the motor 84 into linear motion, and a straight line of the screw mechanism 86. A transmission mechanism 88 for transmitting the kinetic force to the high / low switching mechanism 48, the front wheel drive clutch 50, and the differential lock mechanism 58 is further provided. The motor 84 is, for example, a brushless motor, and includes a rotation angle sensor 85 (see FIG. 1) that detects a rotation angle Am (hereinafter referred to as a motor rotation angle Am) of the motor 84 that is built in or provided on a motor shaft. I have.

  The screw mechanism 86 is disposed around the same axis C1 as the rear-wheel-side output shaft 44, and is a rotary member indirectly connected to the motor 84 via a worm gear 90 (see FIG. 2) provided in the transfer 22. That is, the screw shaft member 92 as a rotating member that is driven to rotate around the shaft center C1 by the motor 84, and the screw shaft member 92 is connected to the screw shaft member 92 so as to be movable in a direction parallel to the shaft center C1 as the screw shaft member 92 rotates. And a nut member 94 for driving the piston 82 by being screwed to the linear motion member, that is, the screw shaft member 92. The screw mechanism 86 is a ball screw in which a screw shaft member 92 and a nut member 94 are actuated via a large number of balls 96. The worm gear 90 is a gear pair including a worm 98 formed integrally with the motor shaft of the motor 84 and a worm wheel 100 disposed around the shaft center C1 and formed integrally with the screw shaft member 92. . The rotation of the motor 84 is decelerated and transmitted to the screw shaft member 92 via the worm gear 90. The screw mechanism 86 converts the rotation of the motor 84 transmitted to the screw shaft member 92 into a linear motion of the nut member 94. For example, the motor 84, the screw mechanism 86, and the like are the clutch driving device 95 that drives the piston 82 of the front wheel driving clutch 50 to bring the front wheel driving clutch 50 into a released state, a slip state, and an engaged state.

  As shown in FIG. 2, the transmission mechanism 88 is provided around another axis C3 parallel to the axis C1 of the screw shaft member (rotating member) 92, and is connected to the nut member 94. A fork 104 fixed to the fork shaft 102 and connected to a high / low sleeve 62 is provided. The transmission mechanism 88 transmits the linear motion force of the nut member 94 in the screw mechanism 86 to the high / low sleeve 62 of the high / low switching mechanism 48 via the fork shaft 102 and the fork 104. A force is applied between the high / low sleeve 62 and the lock sleeve 70 via the first spring 72, and a force is applied to the lock sleeve 70 from the convex portion 44 a of the rear wheel side output shaft 44 via the second spring 74. Yes. Therefore, the transmission mechanism 88 transmits the linear motion force of the nut member 94 in the screw mechanism 86 to the lock sleeve 70 of the differential lock mechanism 58 via the high / low sleeve 62. Therefore, the first spring 72 and the second spring 74 function as members that constitute part of the transmission mechanism 88.

  The screw mechanism 86 is disposed on the side opposite to the drive gear 46 with respect to the front wheel drive clutch 50. The piston 82 of the front-wheel drive clutch 50 is connected to the nut member 94 of the screw mechanism 86 so as not to be relatively movable in a direction parallel to the axis C1 and to be relatively rotatable around the axis C1. Accordingly, the linear motion force of the nut member 94 in the screw mechanism 86 is transmitted to the friction engagement element 80 of the front wheel drive clutch 50 via the piston 82. Therefore, the piston 82 is a pressing member that is connected to the nut member 94 and presses the friction engagement element 80 of the front wheel driving clutch 50, and functions as a member that constitutes a part of the transmission mechanism 88. As described above, the transmission mechanism 88 transmits the linear motion force of the nut member 94 in the screw mechanism 86 to the friction engagement element 80 of the front wheel drive clutch 50.

  As shown in FIG. 2, the transmission mechanism 88 includes a connecting mechanism 106 that connects the nut member 94 and the fork shaft 102. The coupling mechanism 106 is disposed around the axis C3 so as to be slidable with the fork shaft 102 in a direction parallel to the axis C3, and the two flanged cylindrical members 108a and 108b provided at one end face each other. A cylindrical spacer 110 interposed between the two flanged cylindrical members 108a and 108b, a third spring 112 (hereinafter referred to as a third spring 112) disposed on the outer peripheral side of the spacer 110, and 2 A gripping member 114 that grips the two flanged cylindrical members 108a, 108b in a direction parallel to the axis C3 and a connecting member 116 that connects the gripping member 114 and the nut member 94 are provided. The gripping member 114 slides the flanged cylindrical members 108a and 108b on the fork shaft 102 by coming into contact with the flanges of the flanged cylindrical members 108a and 108b. The length of the collar in the state where the collars of the flanged cylindrical members 108 a and 108 b are in contact with the gripping member 114 is longer than the length of the spacer 110. Therefore, the state in which the scissors are in contact with the gripping member 114 is formed by the biasing force of the third spring 112.

  The fork shaft 102 is provided with stoppers 118a and 118b on the outer peripheral surface which make the flanged cylindrical members 108a and 108b non-slidable in the direction parallel to the axis C3. By making the flanged cylindrical members 108 a and 108 b non-slidable by the stoppers 118 a and 118 b, the transmission mechanism 88 causes the linear motion force of the nut member 94 to be changed from the high-low switching mechanism 48 via the fork shaft 102 and the fork 104. Can be communicated to.

  The outer peripheral teeth 70a of the lock sleeve 70 mesh with the lock teeth 68 at a position where the fork shaft 102 meshes the outer peripheral teeth 62b of the high / low sleeve 62 with the low gear gear 66 (referred to as a low gear position). The friction engagement element 80 of the front-wheel drive clutch 50 is pressed by the piston 82 at a position where the fork shaft 102 meshes the outer peripheral teeth 62b of the high / low sleeve 62 with the high side gear teeth 64 (referred to as a high gear position). It is not pressed by the piston 82 at the low gear position 102.

  At the high gear position of the fork shaft 102, the length between the flanges of the flanged cylindrical members 108a and 108b is changed between the length when the flanges are in contact with the gripping member 114 and the length of the spacer 110. Can do. Therefore, the coupling mechanism 106 remains in the high gear position of the fork shaft 102, and the shaft of the nut member 94 is between the position where the friction engagement element 80 of the front wheel drive clutch 50 is pressed by the piston 82 and the position where the friction engagement element 80 is not pressed. Allow movement in a direction parallel to the center C1.

  The transfer 22 includes a gear position holding mechanism 120 that holds the high gear position of the fork shaft 102 and holds the low gear position of the fork shaft 102. The gear position holding mechanism 120 includes an accommodation hole 122 formed on the inner peripheral surface of the transfer case 40 on which the fork shaft 102 slides, a lock ball 124 accommodated in the accommodation hole 122, and an accommodation hole 122 accommodated in the lock. A locking spring 126 that biases the ball 124 toward the fork shaft 102, a recess 128 h that is formed on the outer peripheral surface of the fork shaft 102 and receives a part of the lock ball 124 at the high gear position of the fork shaft 102, and the fork shaft 102 And a recess 128l for receiving a part of the lock ball 124 in the low gear position. Each gear position of the fork shaft 102 is held by the gear position holding mechanism 120, so that each gear position of the fork shaft 102 is held even when the output from the motor 84 is stopped at each gear position.

  In the vehicle 10 configured as described above, when, for example, a four-wheel drive travel mode is selected by an electronic control unit 150 (see FIG. 1) described later, the front-wheel drive clutch 50 and the front-side clutch 36 are engaged. A four-wheel drive state is formed in which driving force is transmitted from the engine 12 to the left and right rear wheels 16L, 16R and the left and right front wheels 14L, 14R. Further, when the two-wheel drive travel mode is selected by the electronic control unit 150, for example, the front-wheel drive clutch 50 and the front-side clutch 36 are released, and the driving force is transmitted from the engine 12 to the left and right rear wheels 16L, 16R. A two-wheel drive state is formed. In the two-wheel drive state, the front-wheel drive clutch 50 and the front-side clutch 36 are disengaged. Therefore, in the four-wheel drive state, the front propeller shaft 24 for transmitting drive force exclusively to the left and right front wheels 14L and 14R. Is disconnected from the engine 12 and the left and right front wheels 14L, 14R. That is, in the two-wheel drive state, the vehicle 10 is a disc that separates the power transmission member for transmitting the driving force from the engine 12 and its sub drive wheels to the left and right front wheels 14L and 14R that are exclusively sub drive wheels in the four wheel drive state. This is a four-wheel drive vehicle with a connect function.

  Returning to FIG. 1, the power transmission device 18 is provided with an electronic control device (control device) 150 including a control device that executes, for example, switching control for switching between a two-wheel drive state and a four-wheel drive state. The electronic control unit 150 includes, for example, a so-called microcomputer having a CPU, a RAM, a ROM, an input / output interface, and the like. The CPU uses a temporary storage function of the RAM and follows a program stored in the ROM in advance. Various controls of the power transmission device 18 are executed by performing signal processing.

The electronic control device 150 is supplied with various input signals detected by each sensor provided in the vehicle 10. For example, a signal indicating the motor rotation angle Am of the motor 84 detected by the rotation angle sensor 85, a signal indicating the vehicle speed V (km / h) of the vehicle 10 detected by the vehicle speed sensor 152, and an oil temperature sensor 154 are detected. A signal indicating the oil temperature T (° C.) of the transfer 22 and a signal indicating that the H range selection switch 156 detected from the H range selection switch 156 for selecting the high speed side gear stage H by the operation of the driver is operated. H range request H _ON , 4WD request 4WD _ON , which is a signal indicating that the 4WD selection switch 158 detected from the 4WD selection switch 158 for selecting the four-wheel drive state by the driver's operation is operated, The diff lock selection detected from the diff lock selection switch 160 for selecting the center diff lock state by the user's operation Differential lock request LOCK _ON is a signal indicating that the switch 160 is _operated, is input to the electronic control unit 150.

  Various output signals are supplied from the electronic control device 150 to each device provided in the vehicle 10. For example, the operation command signal Sd for switching the state of the front side clutch 36, the motor drive command signal Sm for controlling the rotation angle of the motor 84 based on the motor rotation angle Am, etc. 84, etc.

  The shift position determination unit 162 shown in FIG. 1 executes a two-wheel drive state in which the shift position of the piston 82 in the transfer 22 transmits the driving force from the engine 12 to the left and right rear wheels 16L, 16R at the high speed gear stage H. It is determined whether or not the position is H2. For example, in the shift position determination unit 162, the shift position of the piston 82 in the transfer 22 is the four wheels that transmit the driving force from the engine 12 to the left and right rear wheels 16L and 16R and the left and right front wheels 14L and 14R at the high speed gear H. When the driving position is the H4 position, or when the shift position of the piston 82 in the transfer 22 is the L4 position in which the four-wheel driving state is executed in the center differential lock state at the low speed gear L, the transfer 22 is performed. It is determined that the shift position of the piston 82 is not the H2 position. In the electronic control unit 150, for example, the rotation angle of the motor 84 is determined based on the position of the piston 82 at the start of pressing against the front wheel drive clutch 50 stored in the electronic control unit 150. The shift position of the piston 82, that is, the position of the piston 82 is obtained from the rotation angle 84.

  The motor drive control unit 164 drives and controls the motor 84 to move the piston 82 according to the travel mode of the vehicle 10 selected by the electronic control unit 150. For example, in the electronic control unit 150, when the traveling mode of the vehicle 10 is the H2 mode in which the two-wheel drive state is executed in which the driving force is transmitted from the engine 12 to the left and right rear wheels 16L, 16R at the high speed side gear stage H. The motor drive control unit 164 drives the motor 84 to move the piston 82 to the H2 position. Further, in the electronic control unit 150, the traveling mode of the vehicle 10 executes a four-wheel drive state in which the driving force is transmitted from the engine 12 to the left and right rear wheels 16L, 16R and the left and right front wheels 14L, 14R at the high speed side gear stage H. In the H4 mode, the motor drive control unit 164 drives the motor 84 to move the piston 82 to the H4 position. In the electronic control unit 150, when the traveling mode of the vehicle 10 is the L4 mode in which the four-wheel drive state is executed in the center differential lock state at the low speed gear L, the motor drive control unit 164 drives the motor 84. Then, the piston 82 is moved to the L4 position. In the electronic control unit 150, for example, the driver operates the H range selection switch 156, and the driving traveling state of the vehicle 10 is the start traveling of the vehicle 10, the wheel slip, the understeer, the turning traveling, the acceleration traveling, The H4 mode is selected by satisfying the four-wheel drive start condition for any one of high load traveling and deceleration traveling. In the electronic control unit 150, for example, the H2 mode is selected when the driver operates the H range selection switch 156 and the driving state of the vehicle 10 does not satisfy the four-wheel drive start condition. It has become so. In the electronic control unit 150, for example, the L4 mode is selected by operating the differential lock selection switch 160 by the driver.

  When the shift position determination unit 162 determines that the shift position of the piston 82 is the H2 position, the clutch clearance change control unit 166 estimates the estimated clutch temperature of the front wheel drive clutch 50, that is, the hydraulic oil (cooling) of the transfer 22. Of the front wheel drive clutch 50 in accordance with both the oil temperature T (° C.) for use and lubrication) and the relative rotational speed of the friction engagement element 80 of the front wheel drive clutch 50, that is, the vehicle speed V (km / h). The clutch clearance C (mm) is changed, and the position of the piston 82 is changed by the clutch driving device 95 so that the changed clutch clearance C (mm) is obtained. The clutch clearance change control unit 166 determines whether the front wheel driving clutch 50 is in accordance with both the estimated temperature of the clutch temperature of the front wheel driving clutch 50 and the relative rotational speed of the friction engagement element 80 of the front wheel driving clutch 50. It functions as a clutch control means for controlling the motor 84 of the clutch driving device 95 so as to change the position of the piston 82 when the released clutch is released, that is, the H2 position of the piston 82. The clutch clearance C is the distance between the frictional engagement element 80 on the most piston 82 side and the piston 82 when the frictional engagement element 80 approaches the drive gear 46 side when the front-wheel drive clutch 50 is released. It is. When the front wheel driving clutch 50 is engaged and the piston 82 presses the friction engagement element 80, the clutch clearance C becomes zero. The clutch temperature of the front wheel drive clutch 50 can be detected directly or indirectly. The estimated temperature of the clutch temperature, that is, the oil temperature T (° C.) of the hydraulic oil (for cooling, lubrication, etc.) of the transfer 22 is detected by an oil temperature sensor (not shown). For example, the hydraulic oil of the transfer 22 accumulated in the lower part of the transfer case 40 is pumped up, and the hydraulic oil is discharged radially from the center of the rear wheel side output shaft 44 to cool and lubricate the front wheel driving clutch 50 and the like. . The clutch temperature of the front-wheel drive clutch 50 is estimated based on the oil temperature T (° C.) of the hydraulic oil of the transfer 40 detected by an oil temperature sensor provided in the vicinity of the pumping port formed in the lower part of the transfer case 40. .

FIG. 4 is a diagram showing the relationship between the clutch clearance C (mm) of the front wheel drive clutch 50 and the drag torque T _H (Nm) of the front wheel drive clutch 50, and the clutch clearance C of the front wheel drive clutch 50. FIG. 6 is a diagram illustrating a relationship between (mm) and a clutch engagement time T _K (sec) of the front-wheel drive clutch 50. As shown in FIG. 4, as the clutch temperature of the front wheel drive clutch 50 is increased, as the relative rotational speed of the friction engagement elements 80 of the front wheel drive clutch 50 is high, the drag torque T _H of the front wheel drive clutch 50 It is getting smaller. In the former, the higher the clutch temperature of the front-wheel drive clutch 50, the higher the temperature of the oil interposed between the friction engagement elements 80 and the lower the viscosity. Therefore, the shear resistance of the oil interposed between the friction engagement elements 80 The latter is because the oil interposed between the friction engagement elements 80 of the front-wheel drive clutch 50 causes the oil to be frictionally engaged by centrifugal force as the relative rotational speed of the friction engagement elements 80 increases. This is considered to be because it is easy to go out from between 80 and the shear resistance of the oil interposed between the friction engagement elements 80 decreases. The clutch gap C is changed by the clutch gap change control unit 166, for example, dragging torque T _H as shown in FIG. 4 are set in advance by experiment or the like so as to have a predetermined value T _{H 1} (Nm) Value. The predetermined value T _H 1 (Nm) is, for example, a magnitude that prevents the front propeller shaft 24 from rotating due to the drag torque T _H of the front-wheel drive clutch 50. Further, as shown in FIG. 4, when the drag torque T _H of the front wheel drive clutch 50 determines the clutch clearance C to be a predetermined value T _{H 1} (Nm), the clutch temperature of the front wheel drive clutch 50 is high As the relative rotational speed of the friction engagement element 80 of the front wheel drive clutch 50 becomes higher, the clutch gap C can be made smaller. In other words, the position of the piston 82 becomes the friction engagement element 80 of the front wheel drive clutch 50. Since it can approach, that is, the reference position where the front wheel driving clutch 50 starts to be pressed, the time for the piston 82 to move is shortened, and the clutch starts to be engaged from the start of the piston movement of the front wheel driving clutch 50. The time T _K (sec) can be shortened.

In the clutch gap change control unit 166, the clutch temperature of the front wheel drive clutch 50 such that the magnitude of the drag torque T _H of the front wheel drive clutch 50 as shown in FIG. 4 becomes a predetermined value T _{H 1} (Nm) The clutch clearance C determined by the estimated temperature and the relative rotational speed of the frictional engagement element 80 of the front-wheel drive clutch 50 is changed to a map as shown in FIG. 5, for example, and the clutch clearance C (mm) is determined from the map of FIG. I am trying to change it. In the map of FIG. 5, a plurality of map values (for example, A1, A2) representing the clutch clearance C corresponding to the oil temperature T (° C.) of the transfer 22 within a predetermined range and the vehicle speed V (km / h) within the predetermined range. ,..., B1, B2,. Therefore, in the map of FIG. 5, when the oil temperature T (° C.) and the vehicle speed V (km / h) of the transfer 22 are determined, a plurality of map values (for example, A1, A2,..., B1, B2, ...) is determined, and the clutch clearance C is determined. Note that the clutch clearance C represented by a plurality of map values (for example, A1, A2,..., B1, B2,...) Set in the map of FIG. 5 increases as the vehicle speed V (km / h) increases. The clutch gap C increases as the clutch gap C decreases and the vehicle speed V (km / h) decreases. 5, the clutch gap C decreases as the oil temperature T (° C.) of the transfer 22 increases, and the clutch gap C increases as the oil temperature T (° C.) of the transfer 22 decreases.

  When the shift position determination unit 162 determines that the shift position of the piston 82 is not the H2 position, the motor drive control unit 164 performs drive control of the motor 84 at each shift position of the piston 82. For example, in the motor drive control unit 164, when the shift position determination unit 162 determines that the shift position of the piston 82 is not the H2 position but the H4 position in the transfer 22, it is used for front wheel driving according to the traveling state of the vehicle 10. The piston 82 is driven by the motor 84 so that the magnitude of the transmission torque of the clutch 50 is controlled.

  When the clutch clearance C is changed by the clutch clearance change control unit 166, the change determination unit 168 determines the vehicle speed V (km / h) and the oil temperature T (° C.) of the transfer 22 when the clutch clearance C is changed. Then, it is determined whether or not at least one of the current vehicle speed V (km / h) and the oil temperature T (° C.) of the transfer 22 has changed more than a certain level. In the change determination unit 168, when the clutch clearance change control unit 166 has not changed the clutch clearance C, for example, when the engine is started, the vehicle speed V (km / h) set in advance and the oil of the transfer 22 are set. It is determined whether or not at least one of the current vehicle speed V (km / h) and the oil temperature T (° C.) of the transfer 22 has changed more than a certain level with respect to the temperature T (° C.).

  The clutch clearance change control unit 166 has at least one of the vehicle speed V (km / h) and the oil temperature T (° C.) of the transfer 22 when the clutch clearance change C is changed by the change determination unit 168 and the clutch clearance change control unit 166. If it is determined that the change has exceeded a certain level, the clutch clearance C (mm) of the front-wheel drive clutch 50 is changed using the map of FIG. 5 according to the oil temperature T (° C.) of the transfer 22 and the vehicle speed V (km / h). Then, the position of the piston 82 is moved by the clutch driving device 95 so that the changed clutch clearance C (mm) is obtained. For example, in the clutch clearance change control unit 166, when a relatively high vehicle speed V (km / h) is detected from the vehicle speed sensor 152 and a relatively high oil temperature T (° C.) is detected from the oil temperature sensor 154, FIG. According to the map, the clutch clearance C (mm) is changed to a relatively small value. Further, when the clutch gap change control unit 166 detects a relatively low vehicle speed V (km / h) from the vehicle speed sensor 152 and a relatively low oil temperature T (° C.) from the oil temperature sensor 154, FIG. The clutch clearance C (mm) having a relatively large value is changed according to the map. Further, the clutch clearance change control unit 166 includes either the vehicle speed V (km / h) when the clutch clearance C is changed by the change determination unit 168 or the oil temperature T (° C.) of the transfer 22. If it is determined that the valve has not changed more than a certain value, the clutch gap C changed by the previous clutch gap change control unit 166 is maintained without changing the clutch gap C using the map of FIG. Further, the clutch clearance change control unit 166 includes either the vehicle speed V (km / h) when the clutch clearance C is changed by the change determination unit 168 or the oil temperature T (° C.) of the transfer 22. If it is determined that the current has not changed more than a certain value, the current supplied to the motor 84 is stopped and the position of the piston 82 is maintained.

  FIG. 6 shows an example of a control operation for clutch control of the front-wheel drive clutch 50 in which the travel mode of the vehicle 10 is changed while the vehicle is traveling and the position of the piston 82 is moved by the clutch drive device 95 in the electronic control unit 150. It is a flowchart explaining these.

  First, in step S1 corresponding to the function of the shift position determination unit 162 (hereinafter, step is omitted), the shift position of the piston 82 in the transfer 22 is changed from the engine 12 to the left and right rear wheels 16L, 16R at the high speed side gear stage H. It is determined whether or not the vehicle is in the H2 position in which the two-wheel drive state for transmitting the drive force to is executed. If the determination of S1 is negative, S2 corresponding to the function of the motor drive control unit 164 is executed, but if the determination of S1 is affirmative, it corresponds to the function of the change determination unit 168. S3 is executed.

  In S2, the drive control of the motor 84 at each shift position of the piston 82 is performed. For example, if it is determined that the shift position of the piston 82 is not the H2 position but the H4 position, the piston is driven by the motor 84 so that the transmission torque of the front-wheel drive clutch 50 is controlled according to the traveling state of the vehicle 10. 82 is driven.

  In S3, from the vehicle speed V (km / h) when the clutch clearance C is changed in S5 described later and the oil temperature T (° C.) of the transfer 22, or when the clutch clearance C has never been changed. At least one of the current vehicle speed V (km / h) and the oil temperature T (° C.) of the transfer 22 has changed from a preset vehicle speed V (km / h) and the oil temperature T (° C.) of the transfer 22 to a certain level or more. It is determined whether or not.

  When S3 is negative, S4 corresponding to the function of the clutch clearance change control unit 164 is executed. When S3 is positive, S5 corresponding to the function of the clutch clearance change control unit 166 is performed. Is executed. In S4, the current supplied to the motor 84 is stopped and the position of the piston 82 is maintained.

  In S5, the clutch clearance C is changed from the map of FIG. 5 according to the oil temperature T (° C.) of the transfer 22 and the vehicle speed V (km / h), and the clutch is changed to the changed clutch clearance C (mm). The position of the piston 82 is moved by the driving device 95.

  In the flowchart of FIG. 6, the current vehicle speed V (km / h) is calculated from the vehicle speed V (km / h) when the clutch clearance C is changed in S5 and the oil temperature T (° C.) of the transfer 22 in S3. When the oil temperature T (° C.) of the transfer 22 and the transfer 22 change more than a certain value, the clutch clearance C is changed in S5, but the current vehicle speed V (km / h) and the oil temperature T of the transfer 22 are changed. If none of (° C.) changes more than a certain value, the clutch gap C changed in S5 is maintained and the supply of current to the motor 84 is stopped.

  As described above, according to the electronic control unit 150 of the vehicle 10 of the present embodiment, the oil temperature T (° C.) of the transfer 22 related to the clutch temperature of the front wheel driving clutch 50 and the friction engagement of the front wheel driving clutch 50. The clutch clearance C is changed in accordance with both the vehicle speed V (km / h) related to the relative rotational speed of the element 80, and the front wheel drive clutch 50 is released by the clutch clearance C. Since the position can be changed, when the relative rotational speed of the friction engagement element 80 of the front-wheel drive clutch 50 is higher than when the piston position is changed only in accordance with the conventional clutch temperature, the drag is less than a predetermined value. While maintaining the torque, the standby position of the piston 82 can be brought close to the position where the front wheel drive clutch 50 starts to be pressed. The response to switching to the four-wheel drive state can be further improved.

  Further, according to the electronic control unit 150 of the vehicle 10 of the present embodiment, the screw mechanism 86 includes the screw shaft member 92 driven by the motor 84 and the nut member that is screwed into the screw shaft member 92 and drives the piston 82. 94. For this reason, compared with the case where the nut member 94 is driven by the motor 84, when the screw shaft member 92 is driven to rotate by the motor 84 in the screw mechanism 86, the nut member 94 is moved by the action of the screw. The piston 82 moves to a predetermined position.

  Further, according to the electronic control device 150 of the vehicle 10 of the present embodiment, the rotation of the motor 84 is based on the position of the piston 82 that is stored in the electronic control device 10 of the vehicle 10 when the front wheel driving clutch 50 starts to be pressed. The corner is decided. For this reason, since the piston 82 can be suitably moved to a predetermined position by the motor 84 with reference to the position of the piston 82 at the start of pressing, high positioning accuracy can be obtained.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this invention is applied also in another aspect.

  For example, although the vehicle 10 of the above-described embodiment is an FR-based four-wheel drive vehicle, the present invention can be appropriately implemented on an FF base, an RR base, and the like.

  In the above-described embodiment, the clutch clearance change control unit 166 uses the oil temperature T (° C.) of the hydraulic oil (for cooling, lubrication, etc.) of the transfer 22 as the estimated temperature of the clutch temperature of the front-wheel drive clutch 50. However, instead of this, the estimated temperature of the clutch estimated from the travel distance and travel time after the start of traveling of the four-wheel drive vehicle 10 may be used.

  The above description is only an embodiment, and the present invention can be implemented in variously modified and improved forms based on the knowledge of those skilled in the art.

10: Vehicle (4-wheel drive vehicle)
12: Engine 14L, 14R: Front wheel (sub drive wheel)
16L, 16R: Rear wheels (main drive wheels)
24: Front propeller shaft (power transmission member)
36: Front side clutch (connection / disconnection clutch)
50: Front wheel drive clutch (multi-plate clutch)
80: Friction engagement element (clutch input / output element)
82: Piston 84: Motor 86: Screw mechanism 95: Clutch drive device 150: Electronic control device (control device)
166: Clutch clearance change control unit (clutch control means)

Claims (1)

A multi-plate clutch for connecting / disconnecting a power transmission path between the drive source and the power transmission member; and a connection / disconnection clutch for connecting / disconnecting a power transmission path between the power transmission member and the left and right auxiliary drive wheels. A two-wheel drive state in which a driving force is transmitted from the drive source to the left and right main drive wheels by releasing the contact clutch and the multi-plate clutch; and by engaging the connection / disconnection clutch and the multi-plate clutch. A control device for a four-wheel drive vehicle in which a four-wheel drive state in which driving force is transmitted from the drive source to the left and right auxiliary drive wheels is selected,
A clutch driving device that drives the piston of the multi-plate clutch with a motor and a screw mechanism that converts the rotational motion of the motor into linear motion;
The position of the piston when the multi-plate clutch is released is changed according to both the clutch temperature of the multi-plate clutch or its estimated temperature and the relative rotational speed of the clutch input / output element of the multi-plate clutch. Clutch control means for controlling the clutch drive device so that the clutch temperature of the multi-plate clutch is higher when the clutch temperature of the multi-plate clutch or its estimated temperature is higher. The control device for a four-wheel drive vehicle, characterized in that the higher the rotation speed, the closer the standby position of the piston is to a reference position where the multi-plate clutch starts to be pressed.

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