JP2021130401A - Control apparatus of four-wheel-drive vehicle - Google Patents

Abstract

To provide a control apparatus of a four-wheel-drive vehicle, which can restrain running stability from being deteriorated by a fallen object on a road surface that may cause a skid.SOLUTION: A control apparatus 3, which controls a driving force transmitted to right and left rear wheels 194 and 193 of a four-wheel-drive vehicle 1, acquires vehicle type information on the type of a preceding vehicle ahead in a traveling direction. The driving force, which is transmitted to the right and left rear wheels 194 and 193, is set to be a specified value or above when prescribed conditions, which include the fact that it is determined that the preceding vehicle is an automobile for work, according to the acquired vehicle type information, are satisfied.SELECTED DRAWING: Figure 5

Description

The present invention relates to a control device that controls a driving force transmitted to an auxiliary drive wheel among the main drive wheel and the auxiliary drive wheel of a four-wheel drive vehicle.

Conventionally, a four-wheel drive vehicle capable of switching between a two-wheel drive state in which only the main drive wheels are driven and a four-wheel drive state in which the main drive wheels and sub-drive wheels are driven is set to the two-wheel drive state during normal driving. By suppressing the deterioration of fuel efficiency and switching to the four-wheel drive state when slip occurs in the main drive wheels, it is possible to converge the slip of the main drive wheels and secure running stability. In such a four-wheel drive vehicle, considering that it takes a certain amount of time to switch from the two-wheel drive state to the four-wheel drive state, it is driven in advance when traveling in a situation where slip is likely to occur. It has been proposed that the state be a four-wheel drive state.

The control device described in Patent Document 1 detects the traveling state of the preceding vehicle by communicating with the preceding vehicle traveling on the planned road ahead of the own vehicle, and mainly drives the control device based on the detected traveling state of the preceding vehicle. It controls the torque distribution ratio for the front wheels, which are the wheels, and the rear wheels, which are the auxiliary drive wheels. Specifically, the control information of the driving force of the preceding vehicle (for example, the operating status of the anti-lock braking system or the traction control system) is acquired, and the front wheels are determined and evaluated according to the control degree and the control state based on the control information. And set the torque distribution rate for the rear wheels.

Japanese Unexamined Patent Publication No. 9-290655 (see abstract and paragraphs [0036]-[0038])

However, depending on the road surface condition and the running condition of the preceding vehicle, wheel slip may occur due to unforeseen factors. For example, when the preceding vehicle is a work vehicle such as a tractor, the preceding vehicle may leave a falling object such as a mud mass that induces slip on the road, and such a fall If the main drive wheels slip due to an object, the running stability temporarily deteriorates at least until the two-wheel drive state is switched to the four-wheel drive state.

Therefore, an object of the present invention is to provide a control device for a four-wheel drive vehicle capable of suppressing a decrease in running stability due to a falling object on a road surface that may induce slippage. ..

The present invention is a control device that controls a driving force transmitted to the sub-driving wheels of the main driving wheels and the sub-driving wheels of a four-wheel drive vehicle in order to achieve the above object, and is a preceding device in front of the traveling direction. Drive transmitted to the auxiliary drive wheels when predetermined conditions including acquisition of vehicle type information regarding the vehicle type and determination of the preceding vehicle as a work vehicle based on the vehicle type information are satisfied. Provided is a control device for a four-wheel drive vehicle that makes a force equal to or higher than a predetermined value.

According to the control device for a four-wheel drive vehicle according to the present invention, it is possible to prevent the traveling stability from being lowered due to a falling object on the road surface that may induce slippage.

It is a schematic block diagram which shows the structural example of the four-wheel drive vehicle which concerns on 1st Embodiment. It is sectional drawing which shows the structural example of the driving force transmission device. It is a schematic block diagram which shows the schematic block block example of a control device and its surroundings. (A) is an explanatory view showing a tractor traveling on a farm road as viewed from the side. (B) is an explanatory view showing a tractor and its own vehicle as viewed from above the farm road. It is a flowchart which shows the process which the control part of a control device executes. It is a flowchart which shows the process which concerns on the modification of 1st form. It is a schematic block diagram which shows the structural example of the four-wheel drive vehicle which concerns on 2nd Embodiment. It is a schematic block diagram which shows the structural example of the four-wheel drive vehicle which concerns on 3rd Embodiment.

[First Embodiment]
The first embodiment of the present invention will be described with reference to FIGS. 1 to 5. It should be noted that the embodiments described below are shown as suitable specific examples for carrying out the present invention, and there are some parts that specifically exemplify various technically preferable technical matters. , The technical scope of the present invention is not limited to this specific aspect.

FIG. 1 is a schematic configuration diagram showing a schematic configuration example of a four-wheel drive vehicle according to the first embodiment of the present invention.

As shown in FIG. 1, the four-wheel drive vehicle 1 includes a driving force transmission system 10 that can distribute the driving force of the engine 11 as a driving source to the left and right front wheels 191 and 192 and the left and right rear wheels 193 and 194. The force transmission system 10 is controlled by the control device 3. The rotation of the crankshaft, which is the output shaft of the engine 11, is changed by the transmission 12. The left and right front wheels 191 and 192 are main driving wheels to which the driving force of the engine 11 is always transmitted, and the left and right rear wheels 193 and 194 are transmitted to the driving force of the engine 11 according to the vehicle state of the four-wheel drive vehicle 1. It is a secondary drive wheel. Hereinafter, the four-wheel drive vehicle 1 may be referred to as the own vehicle 1.

The driving force transmission system 10 has a four-wheel drive state in which the driving force of the engine 11 is distributed to the left and right front wheels 191 and 192 and the left and right rear wheels 193 and 194, and the driving force of the engine 11 is distributed only to the left and right front wheels 191 and 192. It is possible to switch between the two-wheel drive state. Wheel speed sensors 101 to 104 are respectively arranged on the left and right front wheels 191 and 192 and the left and right rear wheels 193 and 194, respectively. An electric motor may be used as the drive source, or the engine and the electric motor may be combined as the drive source.

The driving force transmission system 10 includes a front differential 13 and a transfer 14 arranged on the front wheel side, a propeller shaft 15 for transmitting a driving force in the front-rear direction of the vehicle, a rear differential 16 arranged on the rear wheel side, and a rear differential 16. The pinion gear shaft 160 that transmits the driving force to the left and right front wheels, the drive shafts 171 and 172 on the left and right front wheels, the drive shafts 181 and 182 on the left and right rear wheels, and the propeller shaft 15 and the pinion gear shaft 160 are arranged. It has a driving force transmission device 2.

The driving force transmission device 2 is controlled by the control device 3 and transmits a driving force corresponding to the current supplied from the control device 3 from the propeller shaft 15 to the pinion gear shaft 160. The control device 3 includes wheel speed information indicating the rotation speeds of the left and right front wheels 191 and 192 and left and right rear wheels 193 and 194 detected by the wheel speed sensors 101 to 104, and the accelerator pedal 111 detected by the accelerator pedal sensor 105. It is possible to acquire information on the accelerator opening degree indicating the amount of operation and information on the steering angle indicating the rotation angle of the steering wheel 112 detected by the steering angle sensor 106. Information on the wheel speed, accelerator opening, and steering angle is an example of a state quantity indicating the vehicle state of the four-wheel drive vehicle 1, and the control device 3 controls the driving force transmission system 10 based on these state quantities. Then, the driving force distribution ratio to the left and right front wheels 191 and 192 and the left and right rear wheels 193 and 194 is adjusted.

For example, the control device 3 sets the drive state to the two-wheel drive state during steady traveling in which the four-wheel drive vehicle 1 travels straight at a constant vehicle speed. As a result, power loss due to friction at the meshing portion between the transfer 14 or the pinion gear shaft 160 and the ring gear 165 is suppressed, and fuel efficiency is improved. Further, the control device 3 travels with a high driving force distribution ratio to the left and right rear wheels 193 and 194, for example, when sudden acceleration or turning, or when slip occurs in any of the left and right front wheels 191 and 192. Stabilize the condition.

The driving force of the engine 11 is transmitted to the left and right front wheels 191 and 192 via the transmission 12, the front differential 13, and the drive shafts 171 and 172 on the left and right front wheels. The front differential 13 is a pair of side gears 131 and 131 connected to the drive shafts 171 and 172 on the left and right front wheels so as not to rotate relative to each other, and a pair of pinion gears that mesh with the pair of side gears 131 and 131 with their gear axes orthogonal to each other. It has 132, 132, a pinion gear shaft 133 that supports a pair of pinion gears 132, 132, and a front differential case 134 that accommodates them.

The transfer 14 has a ring gear 141 fixed to the front differential case 134 and a pinion gear 142 connected to the front end of the propeller shaft 15 and meshing with the ring gear 141, and transmits a driving force to the propeller shaft 15. The rear end of the propeller shaft 15 on the vehicle rear side is connected to the housing 20 which is an input rotating member of the driving force transmission device 2. The driving force transmission device 2 has an inner shaft 23 as an output rotating member arranged so as to be relatively rotatable with the housing 20, and a pinion gear shaft 160 is connected to the inner shaft 23 so as to be relatively non-rotatable. The details of the driving force transmission device 2 will be described later.

The rear differential 16 is a pair of side gears 161, 161 connected to the drive shafts 181 and 182 on the left and right rear wheels so as not to rotate relative to each other, and a pair of side gears 161, 161 that are engaged with the gear axes orthogonal to each other. It has a pinion gear 162, 162, a pinion gear shaft 163 that supports a pair of pinion gears 162, 162, a rear differential case 164 that accommodates the pinion gears 162, and a ring gear 165 that is fixed to the rear differential case 164 and is a hypoid gear that meshes with the pinion gear shaft 160. ing.

(Structure of driving force transmission device)
FIG. 2 is a cross-sectional view showing a configuration example of the driving force transmission device 2. In FIG. 2, the upper side of the rotation axis O shows the operating state (torque transmission state) of the driving force transmission device 2, and the lower side shows the non-operating state (torque non-transmission state) of the driving force transmission device 2. Hereinafter, the direction parallel to the rotation axis O is referred to as an axial direction.

The driving force transmission device 2 is formed between a housing 20 composed of a front housing 21 and a rear housing 22, a tubular inner shaft 23 supported so as to be relatively rotatable coaxially with the housing 20, and between the housing 20 and the inner shaft 23. It has a main clutch 24 arranged in, a cam mechanism 25 that generates a thrust force that presses the main clutch 24, and an electromagnetic clutch mechanism 26 that operates the cam mechanism 25 by receiving a current supply from the control device 3. It is configured. Lubricating oil (not shown) is sealed inside the housing 20.

The front housing 21 has a bottomed cylindrical shape having a cylindrical tubular portion 21a and a bottom portion 21b integrally, and a propeller shaft 15 (see FIG. 1) is connected to the bottom portion 21b via, for example, a cross joint. A plurality of outer spline protrusions 211 extending in the axial direction are formed on the inner surface of the tubular portion 21a. The rear housing 22 is partially formed of a ring-shaped non-magnetic material 221 in the radial direction, and rotates integrally with the front housing 21.

The inner shaft 23 is supported on the inner circumference of the housing 20 by bearings 271,272, and has a plurality of inner spline protrusions 231 extending in the axial direction on the outer peripheral surface. Further, on the inner surface of one end of the inner shaft 23, a spline fitting portion 232 in which one end of the pinion gear shaft 160 (see FIG. 1) is fitted so as not to rotate relative to each other is formed.

The main clutch 24 includes a plurality of main outer clutch plates 241 and a plurality of main inner clutch plates 242 arranged alternately along the axial direction. The outer peripheral end of the main outer clutch plate 241 is engaged with the outer spline protrusion 211 of the front housing 21. The end of the main inner clutch plate 242 on the inner peripheral side is engaged with the inner spline protrusion 231 of the inner shaft 23.

The cam mechanism 25 is arranged between the pilot cam 251 that receives the rotational force of the housing 20 via the electromagnetic clutch mechanism 26, the main cam 252 that presses the main clutch 24 in the axial direction, and the pilot cam 251 and the main cam 252. It is configured to have a plurality of spherical cam balls 253. A plurality of cam grooves 251a and 252a whose axial depths change along the circumferential direction are formed on the facing surfaces of the pilot cam 251 and the main cam 252, respectively, and between these cam grooves 251a and 252a. A cam ball 253 is arranged. A thrust bearing 254 is arranged between the pilot cam 251 and the rear housing 22. The main cam 252 is engaged with the inner spline protrusion 231 of the inner shaft 23 so as to be relatively non-rotatable and axially movable, and is urged toward the pilot cam 251 by a disc spring 255 as a return spring.

The electromagnetic clutch mechanism 26 includes an armature 260, a plurality of pilot outer clutch plates 261 and a plurality of pilot inner clutch plates 262, and an electromagnetic coil 263. The electromagnetic coil 263 is held by a yoke 264 supported by a rear housing 22 by a bearing 273. A current from the control device 3 is supplied to the electromagnetic coil 263 via the electric wire 265.

The plurality of pilot outer clutch plates 261 and pilot inner clutch plates 262 are alternately arranged along the axial direction between the armature 260 and the rear housing 22. The outer peripheral end of the pilot outer clutch plate 261 and the armature 260 is engaged with the outer spline protrusion 211 of the front housing 21. The end of the pilot inner clutch plate 262 on the inner peripheral side is engaged with the pilot cam 251.

The control device 3 can adjust the driving force transmitted from the driving force transmitting device 2 to the left and right rear wheels 193 and 194 by increasing or decreasing the current supplied to the electromagnetic coil 263. In the driving force transmission device 2, magnetic flux is generated in the magnetic path G by the current supplied to the electromagnetic coil 263, the armature 260 is attracted to the rear housing 22 side, and the pilot outer clutch plate 261 and the pilot inner clutch plate 262 rub against each other. Upon contact, the pilot cam 251 rotates relative to the main cam 252, the cam ball 253 rolls on the cam grooves 251a and 252a, and a thrust force is generated on the main cam 252 to press the main clutch 24. Then, a frictional force is generated between the plurality of main outer clutch plates 241 and the plurality of main inner clutch plates 242, and the driving force is transmitted from the housing 20 to the inner shaft 23.

In the driving force transmission device 2, the electromagnetic clutch mechanism 26 and the cam mechanism 25 are sequentially operated as described above, and a frictional force is generated between the plurality of main outer clutch plates 241 of the main clutch 24 and the plurality of main inner clutch plates 242. Since it is generated, there is a time delay between the time when the current is supplied to the electromagnetic coil 263 and the time when the driving force is transmitted to the left and right rear wheels 193 and 194. Therefore, even if the current is supplied to the electromagnetic coil 263 after one of the left and right front wheels 191 and 192 slips when traveling in the two-wheel drive state, the driving force distribution ratio to the left and right rear wheels 193 and 194 becomes high. It may take several seconds, for example, for the slip to converge, and the vehicle behavior may become unstable during this period.

Therefore, for example, when the road surface condition is a low μ state such as an icy road, it is conceivable to distribute the driving force to the left and right rear wheels 193 and 194 in advance to bring the four-wheel drive state. However, depending on the road surface condition and the like, wheel slip may occur due to unforeseen factors. For example, when the preceding vehicle is a work vehicle such as a tractor, the preceding vehicle may leave a falling object that induces slip on the road, and such a falling object causes the main drive wheel to slip. Then, the running stability is temporarily lowered at least until the two-wheel drive state is switched to the four-wheel drive state.

Therefore, in the present embodiment, when a predetermined condition including the determination that the preceding vehicle is a work vehicle is satisfied, a current is supplied to the electromagnetic coil 263 even during steady running, and the driving state is driven. Is a four-wheel drive state. Hereinafter, the configuration of the control device 3 for this purpose and specific examples of the processing contents will be described in detail. In the present embodiment, the preceding vehicle is not limited to the vehicle traveling immediately in front of the own vehicle 1, but refers to a vehicle traveling in front of the own vehicle 1 within a range of a distance that enables inter-vehicle communication, for example.

(Control device configuration)
FIG. 3 is a schematic configuration diagram showing a schematic configuration example of the control device 3 and its surroundings. The four-wheel drive vehicle 1 is used for vehicle-to-vehicle communication and road-to-vehicle communication in accordance with the communication specifications of Intelligent Transport Systems (ITS), which is a comprehensive information communication system for road traffic. The device 4 and the road-to-vehicle communication device 5 are mounted. The control device 3 can communicate with the vehicle-to-vehicle communication device 4 and the road-to-vehicle communication device 5 by, for example, an in-vehicle network such as CAN (Controller Area Network).

The vehicle-to-vehicle communication device 4 can acquire various information regarding the position and vehicle state of the other vehicle by wireless inter-vehicle communication with another vehicle traveling around the own vehicle 1. The road-to-vehicle communication device 5 can communicate with the information providing server 50 of the intelligent transportation system. The information providing server 50 stores information on road conditions such as traffic congestion information and traffic regulation information, information on road speed limits, road type information on road types, and the like. Here, the type of road refers to the classification of roads such as highways, national roads, prefectural roads, unpaved roads, and farm roads (agricultural roads under the Land Improvement Law). In addition, the information providing server 50 stores travel history information related to the travel history of the vehicle.

The road-to-vehicle communication device 5 can acquire various information from the information providing server 50 via the core network 51 of the intelligent transportation system and the wireless access network 52. The radio access network 52 is constructed by a base station 521 that performs wireless communication, and the road-to-vehicle communication device 5 performs wireless communication with the base station 521. As a standard for wireless communication between the vehicle-to-vehicle communication device 4 and the road-to-vehicle communication device 5, for example, the wireless access technology (RAT) of 3GPP (Third Generation Partnership Project), which is a standardization project for examining and creating network specifications such as mobile communication. : Radio Access Technology) using V2X (Vehicle-to-Everything) can be mentioned. Further, the communication standard of the radio access network 52 may be the 4th generation mobile communication system (4G) or the 5th generation mobile communication system (5G).

The control device 3 is an electromagnetic coil 263 via a control unit 30 realized by executing a program by a CPU (arithmetic processing unit), a switching element 301 controlled by PWM, a flywheel diode 302, and a switching element 301. It has a current detection circuit 303 that detects the current supplied to the CPU. The switching element 301 is, for example, a MOSFET, and an IG power supply 110 that outputs a power supply voltage when the ignition switch for starting the engine 11 is in the ON state is connected to the drain, and the source is connected to one end of the electromagnetic coil 263. There is.

The control unit 30 can acquire road type information regarding the type of the road on which the own vehicle 1 travels from the road-to-vehicle communication device 5. Further, the control unit 30 can acquire vehicle type information regarding the type of the preceding vehicle ahead in the traveling direction from the vehicle-to-vehicle communication device 4. When the vehicle type information of the preceding vehicle can be obtained from the information providing server 50, the vehicle type information may be acquired via the road-to-vehicle communication device 5. Here, the type of vehicle refers to a type of vehicle such as a private vehicle, a freight vehicle such as a truck, a passenger transportation vehicle such as a bus, and a work vehicle. Here, the work vehicle is a vehicle for the purpose of performing some kind of work. For example, among agricultural work vehicles such as tractors, combines and rice transplanters, and civil engineering work vehicles such as excavators, the vehicle travels on public roads. It means what is possible.

The control unit 30 is a first torque command value calculation unit that calculates a torque command value indicating a driving force to be transmitted to the left and right rear wheels 193 and 194 based on information such as wheel speed, accelerator opening, and steering angle. 31. Second torque command value calculation for calculating the torque command value indicating the driving force to be transmitted to the left and right rear wheels 193 and 194 based on the information obtained via the vehicle-to-vehicle communication device 4 or the road-to-vehicle communication device 5. The driving force is transmitted according to the larger torque command value of the torque command value calculated by the unit 32 and the first torque command value calculation unit 31 and the torque command value calculated by the second torque command value calculation unit 32. The current command value calculation unit 33 that calculates the current command value indicating the value of the current to be supplied to the electromagnetic coil 263 of the device 2, and the switching element 301 so that the current corresponding to the current command value is supplied to the electromagnetic coil 263. It functions as a current control unit 34 for PWM control. Hereinafter, the torque command value calculated by the first torque command value calculation unit 31 is referred to as a first torque command value, and the torque command value calculated by the second torque command value calculation unit 32 is referred to as a second torque command. It is called a value.

FIG. 4A is an explanatory view showing the tractor 6 traveling on the farm road R as viewed from the side. FIG. 4B is an explanatory view showing the tractor 6 and the own vehicle 1 as viewed from above the farm road R. The tractor 6 is a work vehicle for performing agricultural work, and is a preceding vehicle for the own vehicle 1. In the illustrated example of FIG. 4A, a rotary 61, which is a kind of land leveling machine, is attached to the rear part of the tractor 6 to level the farmland. Further, the tractor 6 is provided with a vehicle-to-vehicle communication device 62, and wireless communication between the vehicle-to-vehicle communication device 62 and the vehicle-to-vehicle communication device 4 of the own vehicle 1 is possible. Although the driver D of the tractor 6 is shown in FIG. 4A, the tractor 6 may be an autonomous vehicle capable of automatic traveling.

When such a tractor 6 is traveling in front of the own vehicle 1, for example, a mud mass M may fall from the wheels of the rotary 61 or the tractor 6 onto the farm road R. If either the left or right front wheel 191 or 192 steps on the mud mass M while the own vehicle 1 is traveling in a two-wheel drive state, slippage may occur and the vehicle behavior may become unstable. ..

Therefore, in the present embodiment, the control unit 30 acquires vehicle type information of the preceding vehicle from the vehicle-to-vehicle communication device 4, and the acquired vehicle type information determines that the preceding vehicle is a work vehicle. When the predetermined condition is satisfied, the driving force transmitted to the left and right rear wheels 193 and 194 is set to the predetermined value or more by setting the second torque command value. Next, the process executed by the control unit 30 will be described in detail with reference to FIG.

FIG. 5 is a flowchart showing a specific example of processing executed by the control unit 30 at predetermined control cycles. In the process shown in this flowchart, the control unit 30 first acquires the wheel speed information, the accelerator opening information, and the steering angle information via the vehicle-mounted network (step S1), and the wheels are stored in the control map stored in advance. The first command torque is calculated by applying the speed, the accelerator opening degree, and the steering angle (step S2).

Next, the control unit 30 acquires vehicle type information of the preceding vehicle ahead in the traveling direction from the preceding vehicle via the vehicle-to-vehicle communication device 4 (step S3), and whether or not the acquired vehicle type information of the preceding vehicle is a working vehicle. (Step S4). When the vehicle type information is a work vehicle in this determination (S4: Yes), the control unit 30 acquires the road type information of the road on which the vehicle is traveling from the information providing server 50 via the road-to-vehicle communication device 5 (step). S5), it is determined whether or not the acquired road type information is a farm road (step S6). In this determination, when the road type information is a farm road (S6: Yes), the control unit 30 determines whether or not the current date and time is included within a predetermined period set corresponding to the time when the farm work is performed (S6: Yes). Step S7). This predetermined period is a period set according to the time when the work vehicle for agricultural work easily removes mud lumps and the like, more specifically, the time when rice planting and tillage are carried out.

When the current date and time are included in the predetermined period (S7: Yes), the control unit 30 sets the second command torque to a predetermined value at which the own vehicle 1 is in the four-wheel drive state (step S8). This predetermined value is a value capable of suppressing a large disturbance in vehicle behavior even if slip occurs in any of the left and right front wheels 191 and 192, and is, for example, 200 to 300 Nm. Further, for example, a value of 200 to 300 Nm is set as the minimum value, and a value larger than the minimum value that changes according to the magnitude of the input torque input from the propeller shaft 15 to the housing 22 of the driving force transmission device 2 is set as the second command. It may be set as a torque. On the other hand, if the result of the determination in step S4, S6 or S7 is no (No), the control unit 30 sets the second command torque to 0 (zero) (step S9).

Next, the control unit 30 calculates a current command value according to the larger command torque of the first command torque and the second command torque (step S10), and the current of this current command value is the electromagnetic coil 263. The switching element 301 is PWM-controlled so as to be supplied to (step S11). Specifically, the duty ratio of PWM control is adjusted so that the current value detected by the current detection circuit 303 matches the current command value, and feedback control is performed.

In this way, the control unit 30 has the first condition that the preceding vehicle is determined to be a work vehicle, the second condition that the road type information of the traveling road is a farm road, and the time when the farm work is performed. When the third condition including the current date and time is satisfied within the predetermined period set corresponding to the above, the driving force transmitted to the left and right rear wheels 193 and 194 is set to a predetermined value or more. The third condition may be omitted, and the second condition may be omitted. Further, other conditions may be added as conditions for executing the process of step S8.

(Effect of the first embodiment)
According to the first embodiment described above, when the preceding vehicle is a work vehicle, the driving force transmitted to the left and right rear wheels 193 and 194 is set to a predetermined value or more. It is possible to prevent the running stability from being lowered due to a falling object on the road surface that may induce the vehicle.

(Modified example of the first embodiment)
Next, a modified example of the first embodiment will be described with reference to the flowchart shown in FIG. In this modification, a part of the processing content executed by the control unit 30 is different from that of the first embodiment. Specifically, instead of the above-mentioned second and third conditions, when the traveling history information of the preceding vehicle indicates that the preceding vehicle has traveled on the agricultural land within a predetermined time in the past from the current date and time, left and right. The driving force transmitted to the rear wheels 193 and 194 is set to a predetermined value or more.

In the flowchart shown in FIG. 6, the processes of steps S1 to S4 and S8 to S11 are the same as those of the flowchart shown in FIG. 5, so duplicate description will be omitted. In this modification, when the preceding vehicle is determined to be a work vehicle in the determination in step S4 (S4: Yes), the travel history information regarding the traveling history of the preceding vehicle is transmitted from the information providing server 50 via the road-to-vehicle communication device 5. (Step S5). Then, based on the acquired travel history information, it is determined whether or not the preceding vehicle has traveled on the agricultural land within the past predetermined time from the current date and time (step S6), and when the result of this determination is positive (Yes). , The process of step S8 is executed. This predetermined time can be set to a time (for example, several hours) in which it is expected that the influence of the falling object on the running of the own vehicle 1 will be small due to, for example, the drying of the mud mass. When the traveling history information regarding the traveling history of the preceding vehicle is obtained from the preceding vehicle, the information may be acquired from the preceding vehicle by vehicle-to-vehicle communication via the vehicle-to-vehicle communication device 4.

Similar to the first embodiment, this modification also makes it possible to prevent the running stability from being lowered by a falling object on the road surface that may induce slippage such as a mud mass. Further, the driving force transmitted to the left and right rear wheels 193 and 194 can be set to a predetermined value or more by more accurately identifying the case where the preceding vehicle is likely to leave a falling object such as a mud mass on the road. In addition, one or both of the second condition and the third condition described in the first embodiment may be added as a condition for executing the process of step S8.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 7 is a schematic configuration diagram showing a schematic configuration example of the four-wheel drive vehicle 1A according to the present embodiment. Similar to the first embodiment, the four-wheel drive vehicle 1A provides a driving force transmission system 10 capable of distributing the driving force of the engine 11 as a driving source to the left and right front wheels 191 and 192 and the left and right rear wheels 193 and 194. The driving force transmission system 10 is controlled by the control device 3, but the configuration of the driving force transmission system 10 is different from that of the first embodiment.

In the first embodiment, the case where the driving force transmission device 2 is arranged between the propeller shaft 15 and the rear differential 16 has been described, but in the present embodiment, the driving force transmission device 2 is the rear differential 16. A pinion gear 151 that is arranged between one side gear 161 and the drive shaft 181 on the left rear wheel side and meshes with the ring gear 165 of the rear differential 16 is attached to the rear end of the propeller shaft 15 on the vehicle rear side. Further, in the first embodiment, the case where the ring gear 141 of the transfer 14 is fixed to the front differential case 134 and rotates integrally has been described, but in the present embodiment, the transfer 14 has the front differential case 134 and the ring gear 141. A meshing clutch 7 for interrupting the connection is arranged.

Since the configuration of the other four-wheel drive vehicle 1A is the same as that of the first embodiment, the members and the like common to those described in the first embodiment are the same as those attached to FIG. The duplicate description is omitted by adding a reference numeral.

The meshing clutch 7 is arranged on the outer periphery of the first meshing member 71 that rotates integrally with the front differential case 134, the second meshing member 72 that rotates integrally with the ring gear 141, and the first meshing member 71 and the second meshing member 72. A sleeve 73, which is a cylindrical connecting member, and an actuator 74 for moving the sleeve 73 are provided.

The actuator 74 is controlled by the control device 3 to move the sleeve 73 in the axial direction of the first meshing member 71 and the second meshing member 72. When the sleeve 73 moves to one side in the axial direction, the sleeve 73 meshes with the first meshing member 71 and the second meshing member 72, and when the sleeve 73 moves to the other side in the axial direction, the sleeve 73 moves to the second meshing member. It meshes only with 72. When the sleeve 73 meshes with the first meshing member 71 and the second meshing member 72, the driving force of the engine 11 is transmitted to the rear differential 16 via the propeller shaft 15. Of the first meshing member 71 and the second meshing member 72, one meshing member may be movable in the axial direction with respect to the other meshing member. In this case, the driving force of the engine 11 is transmitted to the rear differential 16 via the propeller shaft 15 by engaging the one meshing member with the other meshing member.

One side gear 161 of the rear differential 16 is connected to the housing 20 of the driving force transmission device 2 via an intermediate shaft 166, and rotates integrally with the housing 20. A drive shaft 181 on the left rear wheel side is connected to the inner shaft 23 of the driving force transmission device 2 so as not to rotate relative to each other.

When traveling in the four-wheel drive state, the sleeve 73 of the meshing clutch 7 connects the first meshing member 71 and the second meshing member 72 so that they cannot rotate relative to each other, and the current supplied to the electromagnetic coil 263 of the driving force transmission device 2. The driving force corresponding to the above is transmitted to the left rear wheel 193 via the drive shaft 181 on the left rear wheel side. Further, the differential gear mechanism of the rear differential 16 also transmits a driving force corresponding to the driving force transmitted to the left rear wheel 193 to the right rear wheel 194.

On the other hand, when traveling in the two-wheel drive state, the connection between the first meshing member 71 and the second meshing member 72 in the meshing clutch 7 is released, and the current supplied to the electromagnetic coil 263 of the driving force transmission device 2 is released. It becomes zero. As a result, the rotation of the propeller shaft 15 is stopped, and the power loss due to the rotation of the propeller shaft 15, the engagement between the ring gear 141 of the transfer 14 and the pinion gear 142, and the engagement between the ring gear 165 of the rear differential 16 and the pinion gear 151 is suppressed. , Fuel efficiency is improved.

When switching the drive state to the four-wheel drive state during driving in the two-wheel drive state, the current supplied to the electromagnetic coil 263 of the drive force transmission device 2 is gradually increased to drive the rotational force of the left rear wheel 193. It is transmitted to the propeller shaft 15 via the transmission device 2 and the rear differential 16, and the propeller shaft 15 is rotated to rotate and synchronize the first meshing member 71 and the second meshing member 72 of the meshing clutch. After that, the actuator 74 is controlled, and the sleeve 73 connects the first meshing member 71 and the second meshing member 72 so that they cannot rotate relative to each other.

Similar to the first embodiment, the control device 3 satisfies a predetermined condition including that the preceding vehicle is determined to be a work vehicle while the own vehicle 1 is traveling in a two-wheel drive state. The driving force transmitted to the left and right rear wheels 193 and 194 is set to a predetermined value or more, and the driving state is set to the four-wheel driving state. The same effect as that of the first embodiment can be obtained by this second embodiment.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 8 is a configuration diagram showing a schematic configuration example of the four-wheel drive vehicle 1B according to the third embodiment. In the first and second embodiments, the four-wheel drive vehicles 1 and 1A are configured to distribute the driving force of the engine 11 as a single drive source to the left and right front wheels 191 and 192 and the left and right rear wheels 193 and 194. However, the four-wheel drive vehicle 1B according to the present embodiment drives the left and right front wheels 191 and 192 by the engine 11 as the first drive source, and the electric motor 8 as the second drive source. Drives the left and right rear wheels 193 and 194. Further, the four-wheel drive vehicle 1B includes a reduction mechanism 9 for decelerating the rotation of the output shaft 81 of the electric motor 8 and a pair of driving force transmission devices 2.

The reduction gear 9 includes a pinion gear 91 connected to the output shaft 81 of the electric motor 8, a large-diameter gear 92 that meshes with the pinion gear 91, a small-diameter gear 93 that rotates integrally with the large-diameter gear 92, and a larger diameter gear 93 than the small-diameter gear 93. It has a drive shaft 94 having a diameter ring gear 941, and a small diameter gear 93 is meshed with the ring gear 941. The control device 3 controls the electric motor 8 and the pair of driving force transmission devices 2. Of the pair of driving force transmitting devices 2, one driving force transmitting device 2 is arranged between the driving shaft 94 and the left rear wheel 193, and the other driving force transmitting device 2 is the driving shaft 94 and the right rear wheel. It is located between 194 and 194.

Since the configuration of the other four-wheel drive vehicle 1B is the same as that of the first embodiment, the members and the like common to those described in the first embodiment are the same as those attached to FIG. The duplicate description is omitted by adding a reference numeral.

The control device 3 supplies an electric current to the electric motor 8 when a predetermined condition including that the preceding vehicle is determined to be a work vehicle is satisfied while the own vehicle 1B is traveling in a two-wheel drive state. Along with generating a driving force, a current is supplied to the electromagnetic coil 263 of one of the driving force transmission devices 2 to make the driving force transmitted to the left and right rear wheels 193 and 194 equal to or more than a predetermined value, and the driving state is set to the four-wheel driving state. do. The same effect as that of the first embodiment can be obtained by this third embodiment.

(Additional note)
Although the present invention has been described above based on the embodiment, the embodiment does not limit the invention according to the claims. It should also be noted that not all combinations of features described in the embodiments are essential to the means for solving the problems of the invention.

Further, the present invention can be carried out by appropriately modifying it by omitting a part of the configuration or adding or replacing the configuration within a range not deviating from the gist thereof.

1,1A, 1B ... Four-wheel drive vehicle (own vehicle) 3 ... Control device 6 ... Tractor (work vehicle, preceding vehicle) 191,192 ... Left and right front wheels 193,194 ... Left and right rear wheels

Claims (4)

A control device that controls the driving force transmitted to the sub-driving wheels among the main driving wheels and the sub-driving wheels of a four-wheel drive vehicle.
When the vehicle type information regarding the type of the preceding vehicle ahead in the traveling direction is acquired and a predetermined condition including the determination that the preceding vehicle is a work vehicle is satisfied based on the vehicle type information, the auxiliary driving wheel is satisfied. Make the driving force transmitted to
Control device for four-wheel drive vehicles. When the first condition for acquiring the road type information regarding the type of the road on which the vehicle travels and determining that the preceding vehicle is a work vehicle and the second condition indicating that the road type information is a farm road are satisfied. , Make the driving force transmitted to the auxiliary driving wheels a predetermined value or more.
The control device for a four-wheel drive vehicle according to claim 1. The first condition in which the road type information regarding the type of the road on which the vehicle travels is acquired and the preceding vehicle is determined to be a work vehicle, the second condition indicating that the road type information is a farm road, and the farm work are performed. When the third condition including the current date and time is satisfied within a predetermined period set according to the time, the driving force transmitted to the auxiliary driving wheels is set to a predetermined value or more.
The control device for a four-wheel drive vehicle according to claim 1. It is possible to acquire travel history information regarding the travel history of the preceding vehicle.
The predetermined condition includes that the travel history information indicates that the preceding vehicle has traveled on the agricultural land within a predetermined time in the past from the current date and time.
The control device for a four-wheel drive vehicle according to claim 1.

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