Power transmission control device

Abstract

To provide a driving force transmission control device capable of controlling transmitted driving force with high accuracy even in a case when a state that electric current supplied to an electromagnetic coil is gradually increased and a state that the electric current is gradually decreased are frequently switched.SOLUTION: A driving force transmission control device 2 includes: a driving force transmission device 2A for transmitting driving force of torque according to electric current supplied to an electromagnetic coil 63; and a control device 2B for controlling the driving force transmission device 2A by the electric current supplied to the electromagnetic coil 63. The control device 2B stores first and second torque characteristics indicating characteristics of change of torque in gradually increasing the electric current supplied to the electromagnetic coil 63 and gradually decreasing the same, and makes an electric current command value gradually approach a value corresponding to the first torque characteristics or the second torque characteristics according to a hysteresis state, when a state of gradually increasing a torque command value and a state of gradually decreasing the same are switched when the state of the driving force transmission device 2A is a hysteresis state between the first torque characteristics and the second torque characteristics.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a driving force transmission control device.

Background Art

[0002] Conventionally, a four-wheel drive vehicle having a main drive wheel and an auxiliary drive wheel and capable of switching between a two-wheel drive state in which the driving force of a drive source is transmitted only to the main drive wheel and a four-wheel drive state in which the driving force of the drive source is transmitted to the main drive wheel and the auxiliary drive wheel is equipped with a driving force transmission device capable of adjusting the driving force transmitted to the auxiliary drive wheel. The applicant of the present application has proposed the device described in Patent Document 1 as a device related to such a driving force transmission device.

[0003] The driving force transmission control device described in Patent Document 1 includes a driving force transmission device having an electromagnetic clutch mechanism that generates frictional force between a plurality of clutch plates by the movement of an armature due to energization of an electromagnetic coil, and a control device that controls the driving force transmission device. The control device includes a storage unit that stores a hysteresis value indicating a difference in current values required to transmit a predetermined driving force when the energizing current to the electromagnetic coil is gradually increased and when it is gradually decreased, a torque command value calculation means that calculates a torque command value, and a current command value calculation means that calculates a current command value, which is a target value of the current to be supplied to the electromagnetic coil, based on the torque command value and the hysteresis value. The current command value calculation means calculates the current command value so as to suppress the influence of hysteresis and transmit a driving force of a magnitude corresponding to the torque command value between the rotating member on the input side and the rotating member on the output side.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the driving force transmission control device configured as described above, depending on the running state of the four-wheel drive vehicle, there are cases where the current supplied to the electromagnetic coil frequently switches between a state of gradually increasing and a state of gradually decreasing. In such cases, the influence of hysteresis is not always sufficiently suppressed, and there still remains room for improvement.

[0006] Therefore, an object of the present invention is to provide a driving force transmission control device capable of controlling the driving force transmitted between the input-side rotating member and the output-side rotating member with high accuracy even when the current supplied to the electromagnetic coil frequently switches between a state of gradually increasing and a state of gradually decreasing.

Means for Solving the Problems

[0007] In order to achieve the above object, the present invention includes a driving force transmission device that transmits a driving force of torque corresponding to the current supplied to an electromagnetic coil between an input-side rotating member and an output-side rotating member, and a control device that controls the driving force transmitted between the input-side rotating member and the output-side rotating member by the current supplied to the electromagnetic coil. The control device includes a storage unit that stores characteristic information including information on the amount of hysteresis, which is the current difference between a first torque characteristic indicating the characteristics of the change in the torque when the current supplied to the electromagnetic coil is gradually increased and a second torque characteristic indicating the characteristics of the change in the torque when the current supplied to the electromagnetic coil is gradually decreased; torque command value calculation means that calculates the magnitude of the driving force to be transmitted from the input-side rotating member to the output-side rotating member as a torque command value; and current control means that supplies a current corresponding to the current command value obtained according to the torque command value to the electromagnetic coil. When the torque command value switches between a state of gradually increasing and a state of gradually decreasing when the state of the driving force transmission device is in a hysteresis state between the first torque characteristic and the second torque characteristic, the current command value is gradually brought closer to the value corresponding to the first torque characteristic or the second torque characteristic according to the hysteresis state. Furthermore, the control device includes a current command value calculation means for monotonic change, which calculates the magnitude of the current to be supplied to the electromagnetic coil based on the first torque characteristic as a current command value when the torque command value is monotonically increasing, and calculates the magnitude of the current to be supplied to the electromagnetic coil based on the second torque characteristic as a current command value when the torque command value is monotonically decreasing; a gradual decrease processing means for gradually decreasing the current command value while bringing it closer to the value obtained based on the second torque characteristic from the value obtained based on the first torque characteristic when the torque command value switches from a state of gradually increasing to a state of gradually increasing, The system includes a gradual increase processing means that increases the current command value while gradually approaching the value obtained based on the first torque characteristic from a value obtained based on the second torque characteristic, wherein the gradual decrease processing means changes the amount of change in the current command value when gradually approaching the value obtained based on the second torque characteristic, according to the hysteresis state immediately before the torque command value switches from a state of gradually increasing to a state of gradually decreasing, and the gradual increase processing means changes the amount of change in the current command value when gradually approaching the value obtained based on the first torque characteristic, according to the hysteresis state immediately before the torque command value switches from a state of gradually decreasing to a state of gradually increasing. A driving force transmission control device is provided.

Effects of the Invention

[0008] According to the drive force transmission control device of the present invention, even when the state in which the current supplied to the electromagnetic coil gradually increases and the state in which it gradually decreases frequently switch, it is possible to control the drive force transmitted between the input side rotating member and the output side rotating member with high precision. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing a general configuration example of a four-wheel drive vehicle equipped with a drive force transmission control device according to an embodiment of the present invention. [Figure 2] This is a cross-sectional view showing an example of the configuration of a power transmission device. [Figure 3] This is a block diagram showing an example of the functional configuration of a control device. [Figure 4] This graph shows an example of the relationship between current and transmitted torque when the current supplied to an electromagnetic coil is gradually increased from 0 to the rated current, and then gradually decreased from the rated current. [Figure 5] This graph shows an example of the processing content of the gradual decrease processing means when the state of the drive force transmission device is not in a hysteresis state immediately before switching from a state in which the torque command value is gradually increasing to a state in which it is gradually decreasing. [Figure 6] This graph shows an example of the processing content of the gradual decrease processing means when the state of the drive force transmission device is in a hysteresis state immediately before switching from a state in which the torque command value is gradually increasing to a state in which it is gradually decreasing. [Figure 7] This graph shows an example of the processing content of the gradual increase processing means when the state of the drive force transmission device is not in a hysteresis state immediately before switching from a state in which the torque command value is gradually decreasing to a state in which it is gradually increasing. [Figure 8] This graph shows an example of the processing content of the gradual torque increase processing means when the state of the drive force transmission device is in a hysteresis state immediately before switching from a state where the torque command value is gradually decreasing to a state where it is gradually increasing. [Modes for carrying out the invention]

[0010] [Embodiment] Embodiments of the present invention will be described with reference to the drawings. The embodiments described below are shown as preferred specific examples for carrying out the present invention, and some parts specifically illustrate various technically preferable technical matters, but the technical scope of the present invention is not limited to these specific embodiments.

[0011] Figure 1 is a schematic diagram showing a general configuration example of a four-wheel drive vehicle equipped with a drive force transmission control device according to an embodiment of the present invention.

[0012] As shown in Figure 1, the four-wheel drive vehicle 1 includes an engine 11 as a drive source that generates driving force according to the amount of operation of the accelerator pedal 110 (accelerator opening), a transmission 12 that changes the output of the engine 11, left and right front wheels 181, 182 as main drive wheels to which the driving force of the engine 11, which has been shifted by the transmission 12, is always transmitted, and left and right rear wheels 191, 192 as auxiliary drive wheels to which the driving force of the engine 11 is transmitted according to the driving state of the four-wheel drive vehicle 1. Wheel speed sensors 101 to 104 are respectively positioned on the left and right front wheels 181, 182 and the left and right rear wheels 191, 192.

[0013] Furthermore, the four-wheel drive vehicle 1 is equipped with a front differential 13, a propeller shaft 14, a rear differential 15, a pinion gear shaft 150 that transmits driving force to the rear differential 15, left and right front drive shafts 161 and 162, left and right rear drive shafts 171 and 172, a power transmission device 2A positioned between the propeller shaft 14 and the pinion gear shaft 150, and a control device 2B that controls the power transmission device 2A. The power transmission device 2A and the control device 2B constitute the power transmission control device 2.

[0014] The power transmission device 2A transmits power from the propeller shaft 14 to the pinion gear shaft 150 in accordance with the current supplied from the control device 2B. Power from the engine 11 is transmitted to the left and right rear wheels 191 and 192 via the power transmission device 2A. The control device 2B can acquire wheel speed signals indicating the rotational speed of the left and right front wheels 181 and 182 and the left and right rear wheels 191 and 192 detected by wheel speed sensors 101 to 104, and accelerator opening signals indicating the amount of operation of the accelerator pedal 110 detected by the accelerator pedal sensor 105, and controls the power transmission device 2A by supplying current to the power transmission device 2A.

[0015] The driving force from the engine 11 is transmitted to the left and right front wheels 181 and 182 via the transmission 12, the front differential 13, and the left and right front drive shafts 161 and 162. The front differential 13 includes a pair of side gears 131, 131 connected to the left and right front drive shafts 161 and 162 respectively so as not to rotate relative to each other, a pair of pinion gears 132, 132 that mesh with the pair of side gears 131, 131 with their gear axes perpendicular to each other, a pinion gear shaft 133 that supports the pair of pinion gears 132, 132, and a front differential case 134 that houses these components.

[0016] A ring gear 135 is fixed to the front differential case 134, and this ring gear 135 meshes with a pinion gear 141 located at the vehicle-front end of the propeller shaft 14. The vehicle-rear end of the propeller shaft 14 is connected to the housing 20 of the power transmission device 2A. The power transmission device 2A has an inner shaft 3 that is rotatable relative to the housing 20, and a pinion gear shaft 150 is connected to the inner shaft 3 in a way that prevents relative rotation. Details of the power transmission device 2A will be described later.

[0017] The rear differential 15 includes a pair of side gears 151, 151 connected to the left and right rear drive shafts 171, 172 so as not to rotate relative to each other, a pair of pinion gears 152, 152 that mesh with the pair of side gears 151, 151 with their gear shafts perpendicular to each other, a pinion gear shaft 153 that supports the pair of pinion gears 152, 152, a rear differential case 154 that houses these components, and a ring gear 155 fixed to the rear differential case 154 and meshing with the pinion gear shaft 150.

[0018] (Configuration of the power transmission system) Figure 2 is a cross-sectional view showing an example of the configuration of the drive force transmission device 2A. In Figure 2, the area above the rotation axis O shows the operating state of the drive force transmission device 2A, and the area below the rotation axis O shows the non-operating state of the drive force transmission device 2A. Hereinafter, the direction parallel to the rotation axis O will be referred to as the axial direction.

[0019] The drive force transmission device 2A comprises a housing 20 consisting of a front housing 21 and a rear housing 22, a cylindrical inner shaft 3 supported to be rotatable relative to the housing 20 on the same axis, a main clutch 4 positioned between the housing 20 and the inner shaft 3, a cam mechanism 5 that generates a thrust force to press the main clutch 4, and an electromagnetic clutch mechanism 6 that operates the cam mechanism 5 by receiving current from the control device 2B. The housing 20 is an example of the input-side rotating member of the present invention, and the inner shaft 3 is an example of the output-side rotating member of the present invention. The inside of the housing 20 is sealed with lubricating oil (not shown).

[0020] The front housing 21 is a bottomed cylindrical shape, having a cylindrical tubular portion 21a and a bottom portion 21b integrally. A female threaded portion 21c is formed on the inner surface of the open end of the tubular portion 21a. The propeller shaft 14 (see Figure 1) is connected to the bottom portion 21b of the front housing 21 via a cross joint. The front housing 21 also has a plurality of axially extending outer spline projections 211 on the inner circumferential surface of the tubular portion 21a.

[0021] The rear housing 22 is composed of a first annular member 221 made of a magnetic material such as iron, a second annular member 222 made of a non-magnetic material such as austenitic stainless steel which is integrally bonded to the inner circumference of the first annular member 221 by welding or the like, and a third annular member 223 made of a magnetic material such as iron which is integrally bonded to the inner circumference of the second annular member 222 by welding or the like. An annular housing space 22a for housing the electromagnetic coil 63 is formed between the first annular member 221 and the third annular member 223. In addition, a male threaded portion 221a is formed on the outer circumferential surface of the first annular member 221 which screws into the female threaded portion 21c of the front housing 21.

[0022] The inner shaft 3 has a plurality of inner spline projections 31 extending in the axial direction on its outer circumferential surface and is supported on the inner circumference side of the housing 20 by ball bearings 24 and needle roller bearings 25. A spline fitting portion 32 is formed on the inner surface of one end of the inner shaft 3 into which one end of the pinion gear shaft 150 (see Figure 1) is fitted so as not to rotate relative to it.

[0023] The main clutch 4 consists of a plurality of main outer clutch plates 41 and a plurality of main inner clutch plates 42 arranged alternately along the axial direction. The main outer clutch plates 41 rotate with the front housing 21, and the main inner clutch plates 42 rotate with the inner shaft 3. The main outer clutch plates 41 have a plurality of engaging projections 411 on their outer peripheral ends that engage with the outer spline projections 211 of the front housing 21. The main outer clutch plates 41 are restricted from relative rotation with the front housing 21 by the engagement of the engaging projections 411 with the outer spline projections 211, and are movable axially relative to the front housing 21.

[0024] The main inner clutch plate 42 has a plurality of engaging protrusions 421 on its inner circumference end that engage with the inner spline projections 31 of the inner shaft 3. The main inner clutch plate 42 is restricted from relative rotation with respect to the inner shaft 3 by the engagement of the engaging protrusions 421 with the inner spline projections 331, and is movable in the axial direction relative to the inner shaft 3. The main inner clutch plate 42 also has a disc-shaped base material 431 made of metal and friction material 432 attached to both sides of the base material 431. The base material 431 has a plurality of oil holes 433 formed inside the portion to which the friction material 432 is attached, for the flow of lubricating oil. The main outer clutch plate 41 has oil grooves (not shown) formed on the contact surface with the friction material 432 for the flow of lubricating oil.

[0025] The cam mechanism 5 is configured to include a pilot cam 51 that receives rotational force from the housing 20 via an electromagnetic clutch mechanism 6, a main cam 52 as a pressing member that presses the main clutch 4 in the axial direction, and a plurality of spherical cam balls 53 positioned between the pilot cam 51 and the main cam 52.

[0026] The main cam 52 integrally comprises a ring-shaped pressing portion 521 that contacts the main inner clutch plate 42 at one end of the main clutch 4 and presses the main clutch 4, and a cam portion 522 provided on the inner circumference side of the main cam 52 relative to the pressing portion 521. The main cam 52 has a spline engaging portion 521a formed at the inner circumference end of the pressing portion 521 that engages with the inner spline projection 331 of the inner shaft 3, thereby restricting relative rotation with the inner shaft 3. Furthermore, the main cam 52 is biased to move axially away from the main clutch 4 by a disc spring 54 positioned between it and a stepped surface 3a formed on the inner shaft 3.

[0027] The pilot cam 51 has a spline projection 511 on its outer circumference that receives a rotational force from the electromagnetic clutch mechanism 6 that rotates relative to the main cam 52. A thrust needle roller bearing 55 is positioned between the pilot cam 51 and the third annular member 223 of the rear housing 22. Multiple cam grooves 51a and 522a are formed on the opposing surfaces of the pilot cam 51 and the cam portion 522 of the main cam 52, respectively, with axial depths that vary along the circumferential direction. The cam ball 53 is positioned between the cam groove 51a of the pilot cam 51 and the cam groove 522a of the main cam 52.

[0028] The cam mechanism 5 generates a pressing force that presses the main clutch 4 against it as the pilot cam 51 rotates relative to the main cam 52. The main clutch 4 receives the pressing force from the cam mechanism 5, causing frictional contact between the main outer clutch plate 41 and the main inner clutch plate 42, and the driving force is transmitted by the frictional force generated between the main outer clutch plate 41 and the main inner clutch plate 42.

[0029] The electromagnetic clutch mechanism 6 comprises an armature 60, a plurality of pilot outer clutch plates 61, a plurality of pilot inner clutch plates 62, an electromagnetic coil 63, and an annular yoke 64 made of magnetic material that holds the electromagnetic coil 63. The electromagnetic coil 63 is held by the yoke 64 and housed in the housing space 22a of the rear housing 22. The yoke 64 is supported by a ball bearing 26 on the third annular member 223 of the rear housing 22, and its outer circumferential surface faces the inner circumferential surface of the first annular member 221. The inner circumferential surface of the yoke 64 also faces the outer circumferential surface of the third annular member 223.

[0030] The electromagnetic coil 63 is supplied with an excitation current from the control device 2B via the electric wire 631. When the electromagnetic coil 63 is energized, a magnetic flux is generated in the magnetic path G shown in Figure 2. The yoke 64, the first annular member 221 and the third annular member 223 of the rear housing 22, the multiple pilot outer clutch plates 61 and pilot inner clutch plates 62, and the armature 60, which form the path of this magnetic flux, are magnetic path forming members that form the magnetic path G. These magnetic path forming members have coercivity inherent to their respective materials and exhibit magnetic hysteresis, where the magnetic susceptibility is influenced not only by the strength of the magnetic field at that moment but also by past magnetization processes.

[0031] Multiple pilot outer clutch plates 61 and multiple pilot inner clutch plates 62 are disc-shaped members made of a magnetic material such as iron, and are arranged alternately along the axial direction between the armature 60 and the rear housing 22. Multiple arc-shaped slits are formed in the pilot outer clutch plates 61 and pilot inner clutch plates 62 at positions aligned axially with the second annular member 222 of the rear housing 22 to prevent short circuits of magnetic flux.

[0032] The pilot outer clutch plate 61 has a plurality of engaging projections 611 on its outer circumference that engage with the outer spline projections 211 of the front housing 21. The pilot inner clutch plate 62 has a plurality of engaging projections 621 on its inner circumference that engage with the spline projections 511 of the pilot cam 51. The frictional sliding between the pilot outer clutch plate 61 and the pilot inner clutch plate 62 is lubricated by lubricating oil, similar to the main clutch 4.

[0033] The armature 60 is an annular member made of a magnetic material such as iron, and has a plurality of engaging protrusions 601 formed on its outer circumference that engage with the outer spline protrusions 211 of the front housing 21. As a result, the armature 60 is movable in the axial direction relative to the front housing 21, and its relative rotation with respect to the front housing 21 is restricted.

[0034] The electromagnetic clutch mechanism 6 attracts the armature 60 towards the yoke 64 by the magnetic force generated when the electromagnetic coil 63 is energized, and this movement of the armature 60 generates a frictional force between the pilot outer clutch plate 61 and the pilot inner clutch plate 62. The pilot outer clutch plate 61 and the pilot inner clutch plate 62 are pressed against the rear housing 22 by the armature 60 and come into frictional contact.

[0035] In the drive force transmission device 2A, the operation of the electromagnetic clutch mechanism 6 transmits a rotational force corresponding to the current supplied to the electromagnetic coil 63 to the pilot cam 51, causing the pilot cam 51 to rotate relative to the main cam 52, and the cam ball 53 to roll in the cam grooves 51a, 522a. This rolling of the cam ball 53 generates a thrust force that presses the main clutch 4 against the main cam 52, and frictional force is generated between the multiple main outer clutch plates 41 and the multiple main inner clutch plates 42. In other words, the drive force transmission device 2A transmits a torque drive force corresponding to the current supplied to the electromagnetic coil 63 between the housing 20 and the inner shaft 3. The control device 2B controls the drive force transmitted between the housing 20 and the inner shaft 3 by the current supplied to the electromagnetic coil 63. Hereinafter, the magnitude of the drive force transmitted between the housing 20 and the inner shaft 3 will be referred to as the transmitted torque.

[0036] (Control device configuration) Figure 3 is a block diagram showing an example of the functional configuration of the control device 2B. The control device 2B includes a control unit 7 having a CPU (processing unit), a storage unit 8 having non-volatile memory such as EEPROM or flash memory, and a switching power supply unit 9 that switches the voltage of a DC power supply such as a battery to supply current to the electromagnetic coil 63 of the drive force transmission device 2A. The switching power supply unit 9 has switching elements such as transistors and generates current by switching the DC voltage based on the PWM (Pulse Width Modulation) signal output from the control unit 7.

[0037] The control unit 7 functions as a torque command value calculation means 71, a monotonic current command value calculation means 72, a gradual decrease processing means 73, a gradual increase processing means 74, and a current control means 75, when the CPU executes the program 81 stored in the memory unit 8.

[0038] In addition to the program 81, the memory unit 8 stores characteristic information 82, a correction coefficient map 83, and an offset amount map 84 as information used in the processing of the control unit 7. The memory unit 8 also has a work memory area 85 for temporarily storing information such as variables used in the processing executed by the control unit 7.

[0039] The characteristic information 82 is based on the results of measuring the transmission torque when the current supplied to the electromagnetic coil 63 is changed after the assembly of each individual drive force transmission device 2A in the manufacturing line of the drive force transmission device 2A. The correction coefficient map 83 and the offset amount map 84 are map information set based on experimental results or computer simulation results using multiple drive force transmission devices 2A, for example.

[0040] The characteristic information 82 includes a first torque characteristic showing the characteristics of the change in transmitted torque when the current supplied to the electromagnetic coil 63 is gradually increased, a second torque characteristic showing the characteristics of the change in transmitted torque when the current supplied to the electromagnetic coil 63 is gradually decreased, and information on the amount of hysteresis, which is the current difference between the first torque characteristic and the second torque characteristic.

[0041] Here, the amount of hysteresis is the difference in the current value required to transmit a predetermined driving force between the housing 20 and the inner shaft 3 when the current supplied to the electromagnetic coil 63 is gradually increased and when it is gradually decreased. When the current supplied to the electromagnetic coil 63 is gradually increased, the magnetic path forming members such as the yoke 64 are gradually magnetized, so a larger current is required to transmit a predetermined driving force compared to when the current supplied to the electromagnetic coil 63 is gradually decreased.

[0042] Characteristic information 82 stores information on the amount of hysteresis for multiple torque values ​​ranging from near zero to the rated torque. If the first torque characteristic and the amount of hysteresis are stored for multiple torque values, the second torque characteristic can be calculated from the first torque characteristic and the amount of hysteresis. Therefore, in the following explanation, processes performed by referring to the second torque characteristic can be performed by referring to the first torque characteristic and the amount of hysteresis. In other words, the second torque characteristic can be rephrased as the characteristic obtained by subtracting the amount of hysteresis from the first torque characteristic.

[0043] The characteristic information 82 is stored in the memory unit 8 of the control device 2B that is combined with the drive force transmission device 2A when the drive force transmission device 2A is mounted on the four-wheel drive vehicle 1. Due to dimensional errors, assembly errors, or variations in material properties of the magnetic path forming members, the characteristic information 82 based on the above measurement results will differ for each drive force transmission device 2A.

[0044] Figure 4 is a graph showing an example of the relationship between current and transmitted torque when the current supplied to the electromagnetic coil 63 is gradually increased from 0 to the rated current, and then gradually decreased from the rated current to 0. This graph shows a first torque characteristic line L1 that shows the transmitted torque when the current supplied to the electromagnetic coil 63 is gradually increased, and a second torque characteristic line L2 that shows the transmitted torque when the current supplied to the electromagnetic coil 63 is gradually decreased.

[0045] As shown in Figure 4, when the current supplied to the electromagnetic coil 63 gradually increases, the transmitted torque between the housing 20 and the inner shaft 3 becomes smaller compared to when the current gradually decreases. The relationship between the current supplied to the electromagnetic coil 63 and the transmitted torque is approximately linear in the intermediate range, excluding the range near zero current and the range near the rated current. When the drive force transmission device 2A is installed in the four-wheel drive vehicle 1, the drive force transmission device 2A is mainly used in this intermediate range.

[0046] When a torque T, shown on the vertical axis of Figure 4, is transmitted from the housing 20 to the inner shaft 3, the current value required to be supplied to the electromagnetic coil 63 is I1 when the current increases and I2 when the current decreases. The hysteresis amount ΔI (=I1-I2), which is the difference between I1 and I2, varies depending on the magnitude of the torque. In the operation description of the control unit 7 described below, the hysteresis amount refers to the hysteresis amount corresponding to the torque command value when the control is being performed.

[0047] (Processing details of the torque command value calculation means) The torque command value calculation means 71 calculates the magnitude of the driving force to be transmitted from the housing 20 to the inner shaft 3 as a torque command value at predetermined control cycles (e.g., 5ms). The torque command value calculation means 71 sets the torque command value to a larger value, for example, the greater the difference between the average rotational speed of the left and right front wheels 181, 182 and the average rotational speed of the left and right rear wheels 191, 192, and the greater the amount of operation of the accelerator pedal 110.

[0048] (Processing details of the current command value calculation means during monotonic change) The monotonic current command value calculation means 72 calculates the magnitude of the current to be supplied to the electromagnetic coil 63 as a current command value based on the first torque characteristic when the torque command value increases monotonically, and calculates the magnitude of the current to be supplied to the electromagnetic coil 63 as a current command value based on the second torque characteristic when the torque command value decreases monotonically. This sets a current command value that suppresses the influence of magnetic hysteresis in magnetic path forming members such as the yoke 64 on the transmitted torque. The processing of this monotonic current command value calculation means 72 is a basic current command value calculation process that is performed when the torque command value gradually increases or decreases continuously over a longer range than the gradual decrease processing means 73 and gradual increase processing means 74 described later.

[0049] However, the processing of the monotonic current command value calculation means 72 alone is insufficient to properly set the current command value in the hysteresis state between the first torque characteristic and the second torque characteristic after the torque command value switches between a state in which it is gradually increasing and a state in which it is gradually decreasing. Here, the hysteresis state refers to the transient state between a state in which the current supplied to the electromagnetic coil 63 and the transmitted torque change in accordance with the first torque characteristic and a state in which they change in accordance with the second torque characteristic. Therefore, in this embodiment, in order to properly set the current command value even in the hysteresis state, the control device 2B is equipped with a gradual decrease processing means 73 and a gradual increase processing means 74. The processing contents of the gradual decrease processing means 73 and the gradual increase processing means 74 will be described in detail below.

[0050] (Processing details of the gradual decrease processing means) The gradual decrease processing means 73, when switching from a state in which the torque command value is gradually increasing to a state in which it is gradually decreasing, reduces the current command value while gradually bringing it closer to the value obtained based on the second torque characteristic from the value obtained based on the first torque characteristic. Specifically, the gradual decrease processing means 73 executes the calculation processes A to H described below.

[0051] Calculation process A stores the current command value, which is determined based on the first torque characteristic in the control cycle immediately before the torque command value switches from a state in which it is gradually increasing to a state in which it is gradually decreasing, as the current value corresponding to the torque command at the start of the descent in the work memory area 85 of the storage unit 8, and also stores the current command value in the control cycle immediately before the torque command value switches from a state in which it is gradually increasing to a state in which it is gradually decreasing, as the current value at the start of the descent in the work memory area 85 of the storage unit 8.

[0052] Calculation process B is a process that determines whether the state of the drive force transmission device 2A immediately before it switches from a state in which the torque command value is gradually increasing to a state in which it is gradually decreasing is in a hysteresis state. This determination can be made, for example, by determining whether the current value corresponding to the torque command at the start of descent and the current value at the start of descent, which are stored in the work memory area 85 of the storage unit 8 in calculation process A, are substantially equal. In this determination process, if the current value corresponding to the torque command at the start of descent and the current value at the start of descent are substantially equal, it is determined that the state of the drive force transmission device 2A immediately before is not in a hysteresis state, and if there is a difference between these values, it is determined that it is in a hysteresis state.

[0053] Calculation process C is a process that calculates a hysteresis current correction rate based on the torque command value and current command value in the control cycle immediately before the torque command value switches from a state in which it is gradually increasing to a state in which it is gradually decreasing, when calculation process B determines that the state of the drive force transmission device 2A immediately before is a hysteresis state. The hysteresis current correction rate is calculated using the formula (Ia-Ib) / H, where Ia is the current value corresponding to the torque command at the start of the descent, Ib is the current value at the start of the descent, and H is the amount of hysteresis. This hysteresis current correction rate is an index value that indicates how close the hysteresis state immediately before the torque command value switches from a state in which it is gradually increasing to a state in which it is gradually decreasing is to the second torque characteristic. The closer the hysteresis current correction rate is to 1, the closer the hysteresis state is to the second torque characteristic, and the closer the hysteresis current correction rate is to 0, the closer the hysteresis state is to the first torque characteristic.

[0054] The calculation processes A through C described above are executed only once when the torque command value switches from a state of gradually increasing to a state of gradually decreasing, while the calculation processes D through H described below are executed for each control cycle.

[0055] Calculation process D is a process that determines a reference current command value, which is a current value corresponding to the torque command value calculated by the torque command value calculation means 71, by referring to the first torque characteristic. For example, if the torque command value is T as shown in Figure 4, the reference current command value will be I1. In addition, in calculation process D, the reference current command value may be determined by taking into account the relative rotational speed between the housing 20 and the inner shaft 3 and the temperature of the drive force transmission device 2A, based on the value obtained by referring to the first torque characteristic based on the torque command value. The relative rotational speed between the housing 20 and the inner shaft 3 and the temperature of the drive force transmission device 2A are fluctuating factors that affect the magnitude of the driving force transmitted between the housing 20 and the inner shaft 3. For example, if the temperature of the drive force transmission device 2A is low, the viscosity of the lubricating oil inside the housing 20 increases, and the transmitted torque between the housing 20 and the inner shaft 3 increases, so it is desirable to perform temperature correction to lower the reference current command value.

[0056] Calculation process E calculates the current change range (=current value corresponding to torque command at the start of descent - reference current command value), which is the difference between the current value corresponding to the torque command at the start of descent stored in calculation process A and the reference current command value obtained in calculation process D. Based on this current change range, it refers to the correction coefficient map 83 and calculates the correction coefficient. The correction coefficient map 83 stores positive coefficients as correction coefficients, the larger the current change range and the smaller the relative rotational speed between the housing 20 and the inner shaft 3.

[0057] Calculation process F is performed when calculation process B determines that the state of the drive force transmission device 2A immediately before was in a hysteresis state. It refers to the offset amount map 84 to determine an offset value according to the current change range determined in calculation process E and the hysteresis current correction rate determined in calculation process C, and subtracts this offset value from the correction coefficient determined in calculation process E to offset the correction coefficient. The offset amount map 84 stores larger offset amounts as the absolute value of the hysteresis current correction rate increases. Hereinafter, the correction coefficient after offset processing will be called the adjusted correction coefficient. If calculation process B determines that the state of the drive force transmission device 2A immediately before was not in a hysteresis state, the offset amount is set to 0 and no offset processing of the correction coefficient is performed.

[0058] Calculation process G is a process that calculates a subtraction correction value (= hysteresis amount × correction coefficient) by multiplying the amount of hysteresis obtained from the characteristic information 82 of the memory unit 8 by a correction coefficient. This correction coefficient is the correction coefficient obtained in calculation process E if calculation process B did not determine that the state of the drive force transmission device 2A immediately before was in a hysteresis state, and is the adjustment correction coefficient which is the correction coefficient after the offset processing in calculation process F if calculation process B determined that the state of the drive force transmission device 2A immediately before was in a hysteresis state.

[0059] Calculation process H is a process that calculates the current command value (= current command value - current change range - subtraction correction value) by subtracting the current change range and subtraction correction value from the current command value at the start of the decline. The subtraction correction value is the amount of change in the current command value when the current command value is gradually brought closer to the value obtained based on the second torque characteristic. If calculation process B determines that the state of the drive force transmission device 2A immediately before is a hysteresis state, the correction coefficient is offset in calculation process F to become smaller, so the subtraction correction value becomes smaller compared to when calculation process B determines that the state of the drive force transmission device 2A immediately before is not a hysteresis state.

[0060] As described above, the gradual decrease processing means 73, in the hysteresis state after the torque command value switches from a state of gradually increasing to a state of gradually decreasing, determines a reference current command value by referring to the first torque characteristic based on the torque command value, determines a correction coefficient according to the current change range which is the difference between the decreasing start current value and the reference current command value, obtains a subtraction correction value by multiplying the amount of hysteresis obtained from characteristic information 82 by the correction coefficient, and determines the current command value by subtracting the current change range and the subtraction correction value from the decreasing start current value.

[0061] Furthermore, if the state of the drive force transmission device 2A in the control cycle immediately before the torque command value switches from a state of gradually increasing to a state of gradually decreasing is in a hysteresis state, the gradual change reduction processing means 73 determines the offset amount of the correction coefficient based on the torque command value and current command value in the control cycle immediately before the switch from a state of gradually increasing to a state of gradually decreasing, and calculates a subtraction correction value by multiplying the value obtained by offsetting the correction coefficient by this offset amount by the hysteresis amount. This makes it possible to appropriately determine the current command value even when the torque command value switches from a state of gradually increasing to a state of gradually decreasing.

[0062] The processing by the gradual decrease processing means 73 is repeatedly performed until an appropriate current command value can be determined according to the second torque characteristic. If the torque command value continues to decrease thereafter, the current command value is calculated by the monotonic change current command value calculation means 72.

[0063] Figure 5 is a graph showing an example of the processing content of the gradual decrease processing means 73 when the state of the drive force transmission device 2A is not in a hysteresis state immediately before switching from a state in which the torque command value is gradually increasing to a state in which it is gradually decreasing, by enlarging a part of Figure 4. In Figure 5, the torque command value changes from 0 to T0 * After gradually increasing to T1 * ~T6 * This shows an example where the value gradually decreases with each control cycle.

[0064] The coordinate point P0 shown in FIG. 5 is T0, which is the torque command value immediately before switching from the state where the torque command value gradually increases to the state where it gradually decreases. * It is a point on the first torque characteristic line L1 corresponding to * . The current value I0 corresponding to this coordinate point P0 is the current value corresponding to the torque command at the start of descent obtained by referring to the first torque characteristic based on T0 * and is the current value at the start of descent, which is the current command value in the previous control period.

[0065] The coordinate point P in the next control period after the torque command value switches from the state where it gradually increases to the state where it gradually decreases 10 is a point on the first torque characteristic line L1 corresponding to the torque command value T1 * The difference between the current value I corresponding to the coordinate point P 10 and I0 is the current change width in the control period. Also, the current value I 10 is a value obtained by subtracting the subtraction correction value obtained in the arithmetic processing F from the current value I 11 and is the current command value in the control period. The coordinate point P 10 is a point with T1 11 and I * as coordinate values. Thus, the current command value is obtained as a value obtained by subtracting the current change width and the subtraction correction value from the current value I0 at the start of descent. 11

[0066] Also, in FIG. 5, the coordinate points on the first torque characteristic line L1 corresponding to the sequentially decreasing torque command values T2 * ~T6 * are shown as P 20 ~P 60 and the coordinate points obtained by offsetting these coordinate points to the second torque characteristic line L2 side corresponding to the subtraction correction values in their respective control periods are shown as P 21 ~P 61 Even in these control periods, the current command value is obtained by the same processing as above. The subtraction correction value gradually increases as the torque command value decreases, but the increase amplitude gradually shrinks. And when the torque command value is T6 *If the current change range exceeds a predetermined value during the control cycle, the processing of the gradual decrease processing means 73 is terminated. Note that the coordinate point P 11 ~P 61 The torque curve asymptotically approaches the second torque characteristic curve L2 with each control cycle, but it never moves beyond the second torque characteristic curve L2 to the left side of the graph (opposite side from the first torque characteristic curve L1).

[0067] Figure 6 is a graph showing an example of the processing content of the gradual decrease processing means 73 when the state of the drive force transmission device 2A is in a hysteresis state immediately before switching from a state in which the torque command value is gradually increasing to a state in which it is gradually decreasing, by enlarging a portion of Figure 4. Figure 6 shows an example when the drive force transmission device 2A is in a hysteresis state and the torque command value is gradually increasing, and then switches to a state in which the torque command value is gradually decreasing.

[0068] Coordinate point P shown in Figure 6 00 T0 is the torque command value in the control cycle immediately before the switch from a state where the torque command value is gradually increasing to a state where it is gradually decreasing. * , and the coordinate point indicating the command current value I0 during the control cycle. This command current value I0 is stored in the work memory area 85 of the storage unit 8 as the starting current value Ib. Command torque T0 * The current value at coordinate point P0, which is a point on the first torque characteristic line L1 corresponding to the current value, is the current value Ia corresponding to the torque command at the start of descent. In calculation process C, the hysteresis current correction rate is determined based on the current value Ia corresponding to the torque command at the start of descent and the descent start current value Ib.

[0069] The torque command value in the next control cycle after the state in which the torque command value gradually increases is T1 * In this case, this torque command value T1 * The point on the first torque characteristic line L1 corresponding to this is coordinate point P. 10 And the coordinate point P 10 The current value I is the corresponding current value. 10The difference between the current value Ia corresponding to the torque command at the start of the descent is the current change range during that control cycle. In calculation process E, the correction coefficient is determined by referring to the correction coefficient map 83 according to the current change range. In calculation process F, the correction coefficient is offset by the offset value obtained by referring to the offset amount map 84. In calculation process G, the subtraction correction value is obtained by multiplying the hysteresis amount by the adjustment correction coefficient, and in calculation process H, the current command value is obtained by subtracting the current change range and the subtraction correction value from the descent start current value Ib.

[0070] (Processing details of the gradual increase processing means) The gradual increase processing means 74, when switching from a state in which the torque command value is gradually decreasing to a state in which it is gradually increasing, increases the current command value while gradually bringing it closer to the value obtained based on the first torque characteristic from the value obtained based on the second torque characteristic. Specifically, the gradual increase processing means 74 executes the calculation processes I to P described below.

[0071] Calculation process I stores in the work memory area 85 of the storage unit 8 the current command value corresponding to the torque command value in the control cycle immediately before the switch from a state in which the torque command value is gradually decreasing to a state in which it is gradually increasing, based on the second torque characteristic, as the torque command corresponding current value at the start of the rise, and also stores in the work memory area 85 of the storage unit 8 the current command value in the control cycle immediately before the switch from a state in which the torque command value is gradually decreasing to a state in which it is gradually increasing, as the current command value at the start of the rise.

[0072] Calculation process J is a process that determines whether the state of the drive force transmission device 2A immediately before it switches from a state in which the torque command value is gradually decreasing to a state in which it is gradually increasing is in a hysteresis state. This determination can be made, for example, by determining whether the current value corresponding to the torque command at the start of the rise and the current value at the start of the rise, which are stored in the work memory area 85 of the storage unit 8 in calculation process I, are substantially equal. In this determination process, if the current value corresponding to the torque command at the start of the rise and the current value at the start of the rise are substantially equal, it is determined that the state of the drive force transmission device 2A immediately before is not in a hysteresis state, and if there is a difference between these values, it is determined that it is in a hysteresis state.

[0073] Calculation process K is a process that calculates a hysteresis current correction rate based on the torque command value and current command value in the control cycle immediately before the torque command value switches from a state in which it is gradually decreasing to a state in which it is gradually increasing, when calculation process J determines that the state of the drive force transmission device 2A immediately before is a hysteresis state. The hysteresis current correction rate is calculated using the formula (Ic-Id) / H, where Ic is the current value corresponding to the torque command at the start of the rise, Id is the current value at the start of the rise, and H is the amount of hysteresis. This hysteresis current correction rate is an index value that indicates how close the hysteresis state immediately before the torque command value switches from a state in which it is gradually decreasing to a state in which it is gradually increasing is to the first torque characteristic. The closer the hysteresis current correction rate is to -1, the closer the hysteresis state is to the first torque characteristic, and the closer the hysteresis current correction rate is to 0, the closer the hysteresis state is to the second torque characteristic.

[0074] The calculation processes I through K described above are executed only once when the torque command value switches from a state of gradually decreasing to a state of gradually increasing, while the calculation processes L through H described below are executed for each control cycle.

[0075] The calculation process L is a process in which a reference current command value, which is a current value corresponding to the torque command value calculated by the torque command value calculation means 71, is determined by referring to a second torque characteristic. For example, if the torque command value is T as shown in Figure 4, the reference current command value will be I2. In addition, in the calculation process L, the reference current command value may be determined by taking into account the relative rotational speed between the housing 20 and the inner shaft 3 and the temperature of the drive force transmission device 2A, based on the value obtained by referring to the second torque characteristic based on the torque command value.

[0076] Calculation process M calculates the current change range (=current value corresponding to torque command at the start of rising - reference current command value), which is the difference between the current value corresponding to the rising start torque command stored in calculation process I and the reference current command value obtained in calculation process L. Based on this current change range, it refers to the correction coefficient map 83 and calculates the correction coefficient. The correction coefficient map 83 stores positive coefficients as correction coefficients, the larger the absolute value of the current change range and the smaller the relative rotational speed between the housing 20 and the inner shaft 3. The value of the correction coefficient map 83 that the gradual increase processing means 74 refers to in calculation process M may be the same as, or different from, the value of the correction coefficient map 83 that the gradual decrease processing means 73 refers to in calculation process E.

[0077] Calculation process N is performed when calculation process J determines that the state of the drive force transmission device 2A immediately before was in a hysteresis state. It then refers to the offset amount map 84 to determine an offset value according to the current change range determined in calculation process M and the hysteresis current correction rate determined in calculation process K, and subtracts this offset value from the correction coefficient determined in calculation process M to offset the correction coefficient. The offset amount map 84 stores larger offset amounts as the absolute value of the hysteresis current correction rate increases. If calculation process J determines that the state of the drive force transmission device 2A immediately before was not in a hysteresis state, the offset amount is set to 0 and the correction coefficient is not offset.

[0078] The calculation process O is a process that calculates an additive correction value (= hysteresis amount × correction factor) by multiplying the amount of hysteresis obtained from the characteristic information 82 of the memory unit 8 by a correction factor. This correction factor is the correction factor obtained in calculation process M if calculation process J does not determine that the state of the drive force transmission device 2A immediately before was in a hysteresis state, and is the adjustment correction factor which is the correction factor after the offset processing in calculation process N if calculation process J determines that the state of the drive force transmission device 2A immediately before was in a hysteresis state.

[0079] Calculation process P is the process of obtaining the current command value (= rising current value + absolute value of current change range + addition correction value) by subtracting the current change range and the addition correction value from the rising start current value. In calculation process M, the current change range is calculated as a negative value, so the above formula can also be replaced with Current command value = Rising start current value - Current change range + Addition correction value. The addition correction value is the amount of change in the current command value when the current command value is gradually brought closer to the value obtained based on the first torque characteristic. If calculation process J determines that the state of the drive force transmission device 2A immediately before is a hysteresis state, the correction coefficient is offset in calculation process N to become smaller, so the addition correction value is smaller compared to when calculation process J determines that the state of the drive force transmission device 2A immediately before is not a hysteresis state.

[0080] As described above, the gradual increase processing means 74, in the hysteresis state after the torque command value switches from a state of gradually decreasing to a state of gradually increasing, determines a reference current command value by referring to a second torque characteristic based on the torque command value, determines a correction coefficient according to the current change range which is the difference between the torque command corresponding current value at the start of the rise and the reference current command value, obtains an additive correction value by multiplying the amount of hysteresis obtained from characteristic information 82 by the correction coefficient, and determines the current command value by adding the absolute value of the current change range and the additive correction value to the rise start current value.

[0081] Furthermore, if the state of the drive force transmission device 2A in the control cycle immediately before the torque command value switches from a state of gradually decreasing to a state of gradually increasing is in a hysteresis state, the gradual change and increase processing means 74 determines the offset amount of the correction coefficient based on the torque command value and current command value in the control cycle immediately before the switch from the state of gradually decreasing to a state of gradually increasing, and calculates the additive correction value by multiplying the value obtained by offsetting the correction coefficient by the hysteresis amount. This makes it possible to appropriately determine the current command value even when the torque command value switches from a state of gradually decreasing to a state of gradually increasing.

[0082] The processing by the gradual increase processing means 74 is repeatedly performed until an appropriate current command value is determined according to the first torque characteristic. If the torque command value continues to increase thereafter, the current command value is calculated by the monotonic change current command value calculation means 72.

[0083] Figure 7 is a graph showing an example of the processing content of the gradual increase processing means 74 when the state of the drive force transmission device 2A is not in a hysteresis state immediately before switching from a state in which the torque command value is gradually decreasing to a state in which it is gradually increasing, by enlarging a part of Figure 4. In Figure 7, the torque command value is from the maximum value near the rated value to T0 * After gradually decreasing to T1 * ~T6 * This example shows a case where the torque gradually increases with each control cycle. Coordinate point P0 is the torque command value T0 when the state switches from a state where the torque command value is gradually decreasing to a state where it is gradually increasing. * This is a point on the second torque characteristic line L2 corresponding to T0, and the current value I0 corresponding to this coordinate point P0 is T0 * This is the rising start current value obtained by referring to the second torque characteristic based on the above.

[0084] The coordinate point P in the next control cycle after the state where the torque command value gradually decreases has switched to a state where it gradually increases. 10 The torque command value T1 * P is a point on the second torque characteristic line L2 that corresponds to the same point. 10 The current value I is the corresponding current value. 10 The difference between and I0 is the current change range during the control period. Also, the current value I 11 The summation correction value obtained in the calculation process H is the current value I 10 This is the value obtained by adding it to the given value, and it is the current command value for that control cycle. Coordinate point P 11 T1 * and I 11 This is the point whose coordinate value is . In this way, the current command value can be determined by adding the current change range and the addition correction value to the starting current value I0.

[0085] Furthermore, in Figure 7, the torque command value T2 *~T6 * P is the coordinate point on the second torque characteristic line L2 that corresponds to this. 20 ~P 60 These coordinate points are shown, and the coordinate points obtained by offsetting these coordinate points in accordance with the additive correction value in each control cycle are P 21 ~P 61 This is shown. In these control cycles as well, the current command value is obtained by the same process as above. The summation correction value gradually increases as the torque command value increases, but the rate of increase gradually decreases. And when the torque command value is T6 * If the current change range exceeds a predetermined value during the control cycle, the processing of the gradual increase processing means 74 is terminated. Coordinate point P 11 ~P 61 The torque curve asymptotically approaches the first torque characteristic curve L1 with each control cycle, but it never moves beyond the first torque characteristic curve L1 to the right side of the graph (opposite side from the second torque characteristic curve L2).

[0086] Figure 8 is a graph showing an example of the processing content of the gradual increase processing means 74 when the state of the drive force transmission device 2A is in a hysteresis state immediately before switching from a state in which the torque command value is gradually decreasing to a state in which it is gradually increasing, by enlarging a portion of Figure 4. Figure 8 shows an example when the drive force transmission device 2A is in a hysteresis state and the torque command value is gradually decreasing, and then switches to a state in which the torque command value is gradually increasing.

[0087] Coordinate point P shown in Figure 8 00 T0 is the torque command value in the control cycle immediately before the switch from a state where the torque command value is gradually decreasing to a state where it is gradually increasing. * , and the coordinate point indicating the command current value I0 during the control cycle. This command current value I0 is stored in the work memory area 85 of the storage unit 8 as the rising start current value Id. Command torque T0 * The current value at coordinate point P0, which is a point on the second torque characteristic line L2 corresponding to the rise, is the current value Ic corresponding to the torque command at the start of the rise. In calculation process K, the hysteresis current correction rate is determined based on the current value Ic corresponding to the torque command at the start of the rise and the rise start current value Id.

[0088] The torque command value in the next control cycle after the state in which the torque command value gradually increases is T1 * In this case, this torque command value T1 * The point on the second torque characteristic line L2 corresponding to this is coordinate point P. 10 And the coordinate point P 10 The current value I is the corresponding current value. 10 The difference between the current value Ic corresponding to the torque command at the start of the rise is the current change range during that control cycle. In calculation process M, a correction coefficient is obtained by referring to the correction coefficient map 83 according to the current change range. In calculation process N, the correction coefficient is offset by the offset value obtained by referring to the offset amount map 84. In calculation process O, an additive correction value is obtained by multiplying the hysteresis amount by the adjustment correction coefficient, and in calculation process P, the current command value is obtained by subtracting the current change range and the additive correction value from the rising start current value Id.

[0089] (Processing details of the current control means) The current control means 75 supplies a current to the electromagnetic coil 63 that corresponds to the current command value calculated by the monotonic current command value calculation means 72, the gradual decrease processing means 73, or the gradual increase processing means 74. Specifically, it adjusts the duty cycle of the PWM signal that turns the switching elements of the switching power supply unit 9 on and off, and performs feedback control so that a current corresponding to the current command value is supplied to the electromagnetic coil 63. As a result, a driving force of a magnitude corresponding to the torque command value is transmitted between the housing 20 and the inner shaft 3.

[0090] (Operation and Effects of the Embodiment) As described above, according to this embodiment, it is possible to suppress fluctuations in the rotational force transmitted to the pilot cam 51 by the electromagnetic clutch mechanism 6 due to the influence of magnetic hysteresis of the magnetic path forming member constituting the magnetic path G when the electromagnetic coil 63 is energized, thereby improving the accuracy of the driving force transmitted by the driving force transmission device 2A. Furthermore, when the driving force transmission device 2A is in a hysteresis state and the torque command value switches between a state in which it is gradually increasing and a state in which it is gradually decreasing, the current command value is gradually brought closer to a value corresponding to the first torque characteristic or the second torque characteristic according to the hysteresis state. Therefore, even when the state in which the current supplied to the electromagnetic coil 63 is gradually increasing and a state in which it is gradually decreasing switches frequently, it is possible to control the driving force transmitted between the housing 20 and the inner shaft 3 with high accuracy.

[0091] (Note) The present invention has been described above based on embodiments, but these embodiments do not limit the invention as defined in the claims. It should also be noted that not all combinations of features described in the embodiments are necessarily essential for solving the problem of the invention. Furthermore, the present invention can be implemented by omitting some components, or by adding or substituting components, without departing from its spirit. [Explanation of Symbols]

[0092] 2…Drive force transmission control device 20…Housing (rotating member on the input side) 21…Front housing 2A…Drive force transmission device 2B...Control device 3...Inner shaft (rotating member on the output side) 63... Electromagnetic coil 71... Torque command value calculation means 72...Mechanism for calculating current command value during monotonic change 73...Mechanism for processing gradual decrease 74... Gradual change and increase processing means 75... Current control means 8...Storage section 82...Characteristics information 83...Correction factor map 84...Offset amount map

Claims

1. The system comprises a drive force transmission device that transmits a torque driving force corresponding to the current supplied to an electromagnetic coil between an input-side rotating member and an output-side rotating member, and a control device that controls the driving force transmitted between the input-side rotating member and the output-side rotating member by the current supplied to the electromagnetic coil, The control device is A storage unit that stores characteristic information including information on the amount of hysteresis, which is the current difference between a first torque characteristic showing the characteristics of the torque change when the current supplied to the electromagnetic coil is gradually increased and a second torque characteristic showing the characteristics of the torque change when the current supplied to the electromagnetic coil is gradually decreased. Torque command value calculation means that calculates the magnitude of the driving force to be transmitted from the input side rotating member to the output side rotating member as a torque command value, The system includes current control means for supplying a current to the electromagnetic coil corresponding to a current command value determined according to the torque command value, When the state of the drive force transmission device is in a hysteresis state between the first torque characteristic and the second torque characteristic, and the torque command value switches between a state of gradually increasing and a state of gradually decreasing, the current command value is gradually brought closer to the value corresponding to the first torque characteristic or the second torque characteristic, according to the hysteresis state. Furthermore, the control device is A current command value calculation means for monotonically changing currents that calculates the magnitude of the current to be supplied to the electromagnetic coil as a current command value based on the first torque characteristic when the torque command value increases monotonically, and calculates the magnitude of the current to be supplied to the electromagnetic coil as a current command value based on the second torque characteristic when the torque command value decreases monotonically, When the torque command value switches from a state in which it is gradually increasing to a state in which it is gradually decreasing, the current command value is gradually decreased while approaching the value obtained based on the second torque characteristic from the value obtained based on the first torque characteristic, The system includes a gradual increase processing means that, when the torque command value switches from a state of gradually decreasing to a state of gradually increasing, gradually increases the current command value while bringing it closer to the value obtained based on the first torque characteristic from the value obtained based on the second torque characteristic. The gradual decrease processing means changes the amount of change in the current command value when gradually bringing the current command value closer to the value obtained based on the second torque characteristic, according to the hysteresis state immediately before the torque command value switches from a state of gradually increasing to a state of gradually decreasing. The gradual increase processing means changes the amount of change in the current command value when gradually bringing the current command value closer to the value obtained based on the first torque characteristic, according to the hysteresis state immediately before the torque command value switches from a state in which it is gradually decreasing to a state in which it is gradually increasing. Power transmission control device.

2. The storage unit stores the correction coefficient map that the gradual decrease processing means and the gradual increase processing means refer to. The correction coefficient map stores a correction coefficient that increases as the current change range increases, corresponding to the difference between the current value obtained based on the characteristic information in accordance with the torque command value and the current command value immediately before the state in which the torque command value gradually increases and the state in which it gradually decreases switches. The gradual decrease processing means and the gradual increase processing means determine the current command value based on a value obtained by multiplying the hysteresis amount by a correction coefficient obtained by referring to the correction coefficient map according to the current change range. The gradual decrease processing means offsets a correction coefficient obtained by referring to the correction coefficient map according to the current change range, according to the hysteresis state immediately before the torque command value switches from a state in which it is gradually increasing to a state in which it is gradually decreasing, and determines the current command value based on the value obtained by multiplying the offset correction coefficient by the amount of hysteresis. The gradual increase processing means offsets a correction coefficient obtained by referring to the correction coefficient map according to the current change range, according to the hysteresis state immediately before the torque command value switches from a state in which it is gradually decreasing to a state in which it is gradually increasing, and determines the current command value based on the value obtained by multiplying the offset correction coefficient by the amount of hysteresis. The drive force transmission control device according to claim 1.

3. The monotonic current command value calculation means, the gradual decrease processing means, and the gradual increase processing means determine the current command value by taking into account the fluctuating factors that affect the magnitude of the driving force transmitted between the input-side rotating member and the output-side rotating member. The aforementioned fluctuating factors include at least one of the relative rotational speed between the input-side rotating member and the output-side rotating member, and the temperature of the drive force transmission device. The drive force transmission control device according to claim 1 or 2.

Images