Crosswind influence estimation device and vehicle control device

Abstract

The present invention relates to a crosswind influence estimation device and a vehicle control device. The crosswind influence estimation device is mounted in a vehicle and is configured to estimate the influence of crosswind on the vehicle. The crosswind influence estimation device includes a processor configured to: i) obtain crosswind information in a predetermined area ahead of the vehicle in the direction of travel; ii) obtain information about shielding objects located on the windward side in the direction of the crosswind; and iii) estimate the influence of the crosswind on the vehicle based on the obtained crosswind information and the obtained shielding object information.

Description

Technical Field

[0001] The present invention relates to a crosswind influence estimation device configured to estimate the influence of crosswind on a vehicle and a vehicle control device configured to control a driving force distribution ratio for wheels. Background Art

[0002] A differential limiting force control device has been proposed that suppresses left-right swaying of a vehicle due to external disturbances such as crosswind during travel by limiting the differential motion between left and right wheels (for example, refer to Japanese Unexamined Patent Application Publication No. 2009-257383 (JP 2009-257383 A)).

[0003] The differential limiting force control device described in JP 2009-257383 A includes a wind force detection unit, a differential device, a differential limiting unit, and a differential limiting force control unit. The wind force detection unit detects wind force acting on a portion of the vehicle, which portion is located in front of the center of gravity of the vehicle. The differential device transmits power generated by a power generation device to the left and right drive wheels while allowing differential movement between the left and right drive wheels. The differential limiting unit limits the differential movement permitted by the differential device by generating a differential reaction force that offsets the differential movement between the left and right wheels. The differential limiting force control unit controls the differential control unit so that when the wind force detection unit detects wind force, the differential limiting unit generates a differential reaction force based on the detected wind force. Summary of the Invention

[0004] However, when a vehicle is traveling in a crosswind, conventional differential limiting force control units only control the differential control unit after sensors detect the crosswind's impact on the vehicle. This temporarily disrupts vehicle behavior, potentially causing driver anxiety. Using widely available road-to-vehicle communication technology to detect wind conditions ahead of the vehicle in its direction of travel, it is possible to estimate the wind's impact on vehicle travel to some extent. However, when objects obstruct the wind, the wind's impact may not be accurately estimated.

[0005] Therefore, the present inventors have conceived the following idea: if the influence of crosswind on the vehicle can be estimated in advance by taking into account the presence of an obstruction, the disturbance of vehicle behavior can be suppressed, and further, the driver's anxiety can be suppressed. Therefore, the present inventors have made the present invention based on this idea.

[0006] The present invention provides a crosswind influence estimation device capable of estimating the influence of crosswind on a vehicle in advance, and a vehicle control device capable of suppressing interference with vehicle behavior based on the pre-estimated crosswind influence.

[0007] A first aspect of the present invention relates to a crosswind impact estimation device, which is mounted in a vehicle and is configured to estimate the impact of a crosswind on the vehicle. The crosswind impact estimation device includes a processor configured to: i) obtain information about the crosswind in a predetermined area ahead of the vehicle in the direction of travel; ii) obtain information about an obstruction located on the windward side in the direction of the crosswind; and iii) estimate the impact of the crosswind on the vehicle based on the obtained crosswind information and the obtained obstruction information.

[0008] A second aspect of the present invention relates to a control device for a vehicle, the vehicle including wheels, the wheels including left and right front wheels and left and right rear wheels, the control device being configured to control a driving force distribution ratio for the wheels. The control device includes: at least one processor, the at least one processor being configured to: i) obtain information about a crosswind in a predetermined area ahead of the vehicle in the direction of travel of the vehicle; ii) obtain information about an obstruction located on the windward side in the direction of the crosswind; iii) estimate an effect of the crosswind on the vehicle based on the obtained crosswind information and the obtained obstruction information to obtain an estimation result; and iv) control the driving force distribution ratio for the wheels based on the obtained estimation result.

[0009] The crosswind influence estimation device according to the above aspect of the present invention can estimate the influence of crosswind on the vehicle in advance, taking into account the presence of shielding objects. The vehicle control device according to the above aspect of the present invention can suppress interference with vehicle behavior based on the estimated crosswind influence. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, wherein like reference numerals represent like elements, and wherein:

[0011] Figure 1 is a schematic diagram showing a configuration example of a four-wheel drive vehicle according to a first embodiment of the present invention;

[0012] Figure 2 is an explanatory diagram showing a specific example of inter-vehicle communication and road-to-vehicle communication;

[0013] Figure 3 is a block diagram showing a configuration example of a control device and a crosswind influence estimating device;

[0014] Figure 4 Parts (a) to (e) in FIG. 1 are explanatory diagrams showing, in chronological order, a situation in which the vehicle passes by other vehicles when the vehicle turns on a curved road when wind blows from the outside to the inside of the turn;

[0015] Figure 5A is a graph showing an example of forecast information generated by an estimation unit of a crosswind influence estimation device, and Figure 5B is a graph showing the auxiliary driving force transmitted to the left and right rear wheels when the driving force transmission device is controlled based on the generated forecast information;

[0016] Figure 6 Parts (a) to (e) in FIG. 1 are explanatory diagrams showing, in chronological order, a situation in which the vehicle passes by other vehicles when the vehicle turns on a curved road when wind blows from the inside to the outside of the turn;

[0017] Figure 7A is a graph showing an example of forecast information generated by an estimation unit of a crosswind influence estimation device, and Figure 7B is a graph showing the auxiliary driving force transmitted to the left and right rear wheels when the driving force transmission device is controlled based on the generated forecast information;

[0018] Figure 8 is a schematic diagram showing a configuration example of a four-wheel drive vehicle 1A according to a second embodiment;

[0019] Figure 9 is a schematic diagram showing a configuration example of a four-wheel drive vehicle 1B according to a third embodiment;

[0020] Figure 10 is a schematic diagram showing a configuration example of a four-wheel drive vehicle 1C according to a fourth embodiment; and

[0021] Figure 11 is a block diagram showing a configuration example of a control device according to a fifth embodiment. DETAILED DESCRIPTION

[0022] Will refer to Figure 1 The first embodiment of the present invention will be described with reference to FIG7. The embodiment described below is a specific example, and the technical scope of the present invention is not limited to the specific example.

[0023] Figure 1 This is a schematic diagram illustrating an example configuration of a four-wheel drive vehicle 1 according to a first embodiment of the present invention. Four-wheel drive vehicle 1 can drive both the front and rear wheels. In this embodiment, four-wheel drive vehicle 1 includes a left front wheel 11 and a right front wheel 12 as main drive wheels, to which driving force is constantly transmitted. Four-wheel drive vehicle 1 also includes a left rear wheel 13 and a right rear wheel 14 as auxiliary drive wheels, to which driving force is transmitted based on vehicle information. In the following description, four-wheel drive vehicle 1 may sometimes be referred to as vehicle 1.

[0024] The four-wheel drive vehicle 1 includes an engine 15, a transmission 16, a vehicle navigation system 17 and a driving force transmission system 2. The engine 15 serves as a driving source. The transmission 16 changes the rotational speed of the output shaft of the engine 15. The vehicle navigation system 17 provides the driver with route guidance to the destination based on position information obtained using a global positioning system (GPS) antenna 170. After the rotational speed is changed by the transmission 16, the driving force transmission system 2 transmits the driving force generated by the engine 15 to the left and right front wheels 11, 12 and the left and right rear wheels 13, 14. As a driving source, for example, an electric motor can be used. Alternatively, the driving source can be a so-called hybrid system in which an engine and an electric motor are combined.

[0025] The driving force transmission system 2 includes a left drive shaft 21 and a right drive shaft 22 on the front wheel side, a left drive shaft 23 and a right drive shaft 24 on the rear wheel side, a front differential 3 as a differential device on the front wheel side, a rear differential 4 as a differential device on the rear wheel side, a propeller shaft 20 that transmits driving force in the vehicle front-rear direction (i.e., from front to rear in the vehicle), and a driving force transmission device 5 that transmits driving force to the left rear wheel 13 and the right rear wheel 14. In addition, the four-wheel drive vehicle 1 includes a control device 6 that controls the driving force transmission device 5 and a crosswind influence estimating device 7 that estimates the influence of crosswind on the four-wheel drive vehicle 1 during driving.

[0026] In this embodiment, the driving force transmission device 5 is arranged between the propeller shaft 20 and the rear differential 4. The driving force transmission device 5 is configured to adjust the driving force transmitted from the propeller shaft 20 to the left rear wheel 13 and the right rear wheel 14. With this configuration, the front and rear wheel driving force distribution ratio is variable. The front and rear wheel driving force distribution ratio is the ratio between the driving force distributed to the left and right front wheels 11, 12 and the driving force distributed to the left and right rear wheels 13, 14.

[0027] The front differential 3 includes a front differential case 31, a pinion shaft 32, a pair of pinion gears 33, and first and second side gears 34 and 35. The pinion shaft 32 rotates integrally with the front differential case 31. The pinion gears 33 are supported by the pinion shaft 32. The first and second side gears 34 and 35 mesh with the pinion gears 33 so that the gear axes of the pinion gears 33 are orthogonal to the gear axes of the first and second side gears 34 and 35. The front differential 3 distributes driving force to the left and right front wheels 11 and 12. The first side gear 34 is coupled to the left drive shaft 21 on the front wheel side so that it cannot rotate relative to the left drive shaft 21. The second side gear 35 is coupled to the right drive shaft 22 on the front wheel side so that it cannot rotate relative to the right drive shaft 22.

[0028] The driving force output from the transmission 16 is transmitted to the front differential case 31 in the front differential 3 and further transmitted from the front differential case 31 to the propeller shaft 20 via the gear mechanism 25. The gear mechanism 25 is, for example, a hypoid gear pair. The gear mechanism 25 includes a ring gear 251 and a pinion gear 252 that mesh with each other. The ring gear 251 rotates integrally with the front differential case 31, and the pinion gear 252 is provided at one end of the propeller shaft 20. The other end of the propeller shaft 20 is coupled to the driving force transmission device 5 via, for example, a cross joint (not shown).

[0029] The driving force transmission device 5 includes a bottomed cylindrical housing 51, an inner shaft 52, a multi-plate clutch 53, a cam mechanism 54, an electromagnetic clutch 55, and an electromagnetic coil 56. The driving force from the transmission shaft 20 is input to the housing 51. The inner shaft 52 is coaxially supported by the housing 51 so as to be rotatable relative to the housing 51. The multi-plate clutch 53 includes a plurality of clutch plates arranged between the housing 51 and the inner shaft 52. The cam mechanism 54 generates a pressing force for pressing the multi-plate clutch 53. The electromagnetic clutch 55 transmits an operating force for operating the cam mechanism 54. An excitation current is supplied to the electromagnetic coil 56 from the control device 6.

[0030] When the electromagnetic coil 56 is energized, the electromagnetic clutch 55 is engaged by the generated magnetic force, and a portion of the rotational force of the housing 51 is transmitted to the guide cam 541 of the cam mechanism 54 by the electromagnetic clutch 55. The cam mechanism 54 includes a guide cam 541, a main cam 542, and a plurality of cam balls 543. The guide cam 541 and the main cam 542 are capable of rotating relative to each other within a predetermined angular range. The cam balls 543 are capable of rolling between the guide cam 541 and the main cam 542. Each of the guide cam 541 and the main cam 542 includes a cam groove on which the cam balls 543 roll. The cam groove of the guide cam 541 and the cam groove of the main cam 542 are inclined relative to the circumferential direction of the guide cam 541 and the circumferential direction of the main cam 542, respectively.

[0031] The main cam 542 is capable of axial movement and cannot rotate relative to the inner shaft 52. When the guide cam 541 rotates relative to the main cam 542 due to the rotational force transmitted by the electromagnetic clutch 55, the cam ball 543 rolls on the cam groove, and the main cam 542 moves away from the guide cam 541. Therefore, the multi-plate clutch 53 is pressed, and the clutch plates in the multi-plate clutch 53 are in frictional contact with each other, and therefore, the driving force is transmitted between the housing 51 and the inner shaft 52. The driving force transmitted by the multi-plate clutch 53 varies depending on the magnitude of the current supplied to the electromagnetic coil 56. The control device 6 increases or decreases the auxiliary driving force transmitted to the left and right rear wheels 13, 14 by changing the magnitude of the current supplied to the electromagnetic coil 56.

[0032] For example, when the four-wheel drive vehicle 1 is traveling in a straight line and the multi-plate clutch 53 is pressed so that the clutch plates of the multi-plate clutch 53 do not rotate relative to each other, the front and rear wheel drive force distribution ratio is 50:50. When the multi-plate clutch 53 is not pressed and the drive force transmitted by the drive force transmission device 5 is zero (0), the front and rear wheel drive force distribution ratio is 100 (front wheels):0 (rear wheels).

[0033] The pinion shaft 26 is coupled to the inner shaft 52 of the driving force transmission device 5. The pinion shaft 26 cannot rotate relative to the inner shaft 52. The pinion shaft 26 includes a gear portion 261 provided at one end thereof. The gear portion 261 of the pinion shaft 26 meshes with the ring gear 40 fixed to the rear differential case 41 of the rear differential 4.

[0034] The rear differential 4 includes a rear differential case 41, a pinion shaft 42, a pair of pinion gears 43, and first and second side gears 44, 45. The pinion shaft 42 rotates integrally with the rear differential case 41. The pinion gears 43 are supported by the pinion shaft 42. The first and second side gears 44, 45 mesh with the pinion gears 43 so that the gear axes of the pinion gears 43 are orthogonal to the gear axes of the first and second side gears 44, 45. The rear differential 4 distributes driving force to the left and right rear wheels 13, 14. The first side gear 44 is coupled to the left drive shaft 23 on the rear wheel side so that it cannot rotate relative to the left drive shaft 23. The second side gear 45 is coupled to the right drive shaft 24 on the rear wheel side so that it cannot rotate relative to the right drive shaft 24.

[0035] The control device 6 and the crosswind influence estimation device 7 can obtain various vehicle information via an on-vehicle communication network such as a controller area network (CAN). The vehicle information is information indicating the conditions of components of the four-wheel drive vehicle 1, and includes information such as the wheel speed of each of the left and right front wheels 11, 12 and the left and right rear wheels 13, 14, the steering angle of the steering wheel 18, the depression amount of the accelerator pedal 19, and the vehicle speed.

[0036] Furthermore, an antenna 70 is connected to the crosswind influence estimation device 7. The crosswind influence estimation device 7 can use the antenna 70 to perform inter-vehicle communication with other vehicles traveling near the host vehicle 1, and can also perform road-to-vehicle communication with a communication device installed on the road. An example of a typical communication method used for inter-vehicle communication and road-to-vehicle communication is Dedicated Short Range Communication (DSRC), which is wireless communication and is used in intelligent transportation systems (ITS).

[0037] Figure 2 is an explanatory diagram showing a specific example of inter-vehicle communication and road-to-vehicle communication. Figure 2The figure shows a vehicle 1 turning on a curved road, another vehicle 10 traveling in an opposite lane (i.e., an oncoming vehicle), a noise barrier 101, a roadside communication device 102 installed on the roadside, and an anemometer 103. The crosswind influence estimation device 7 of the vehicle 1 can communicate with the other vehicle 10 and the roadside communication device 102 via the antenna 70. Figure 2 In the example shown in FIG, a roadside communication device 102 is attached to the upper portion of the noise barrier 101. The roadside communication device 102 transmits information on wind direction and wind speed measured by the anemometer 103 together with position information of the roadside communication device 102. The other vehicle 10 is a truck having a longer total length than the vehicle 1.

[0038] In addition, Figure 2 In FIG, multiple arrows A show the direction of the wind. Figure 2 In the example illustrated in FIG, the direction of the wind extends from the outside toward the inside of the curved road. The lane Lo in which the other vehicle 10 is traveling is located on the windward side relative to the lane Li in which the host vehicle 1 is traveling (i.e., the lane Lo is located on the windward side of the lane Li). The lane Lo in which the other vehicle 10 is traveling and the lane Li in which the host vehicle 1 is traveling are separated by a center line CL. When the other vehicle 10 and the host vehicle 1 pass each other, the other vehicle 10 is located on the windward side relative to the host vehicle 1 (i.e., the other vehicle 10 is located on the windward side of the host vehicle 1) and serves as a shield to shield the host vehicle 1 from the crosswind.

[0039] The anemometer 103 is generally installed at a location where strong winds may occur. The sound insulation barrier 101 is installed between a road (lane Lo, Li) and a residential area or the like. For example, when a strong wind blows in the direction indicated by the arrow A, the sound insulation barrier 101 acts as a shield located on the windward side relative to the vehicle 1 (i.e., a shield located on the windward side of the vehicle 1) and shields the vehicle 1 from the crosswind. Therefore, the effect of the crosswind on the vehicle 1 varies significantly at or near the terminal portion of the sound insulation barrier 101. In the first embodiment, the crosswind influence estimating device 7 estimates the effect of the crosswind on the vehicle 1 in advance (i.e., before the vehicle 1 is actually affected by the crosswind).

[0040] Figure 3is a block diagram showing a configuration example of the control device 6 and the crosswind influence estimation device 7. The control device 6 includes a central processing unit (CPU) 61, a storage unit 62, a switching circuit 63, and a communication circuit 64. The CPU 61 serves as a calculation processing unit. The storage unit 62 includes semiconductor memory elements such as a read-only memory (ROM) and a random access memory (RAM). The switching circuit 63 generates a current to be supplied to the electromagnetic coil 56 of the driving force transmission device 5. The communication circuit 64 performs communication via the on-vehicle communication network N. The storage unit 62 stores a program 621 and map information 622. The program 621 indicates the process of the calculation processing to be performed by the CPU 61. The map information 622 indicates the relationship between the vehicle information of the four-wheel drive vehicle 1 and the command torque indicating the driving force to be transmitted to the left and right rear wheels 13, 14.

[0041] By executing program 621, CPU 61 (i.e., processor) functions as control unit 611 for controlling the driving force distribution ratio between left and right front wheels 11, 12 and left and right rear wheels 13, 14. Control unit 611 calculates a command torque based on vehicle information obtained by communication circuit 64, with reference to map information 622. Furthermore, control unit 611 sets the duty ratio (i.e., duty cycle) of the PWM signal supplied to switching circuit 63 according to the command torque. Consequently, switching circuit 63 supplies current to electromagnetic coil 56 of driving force transmission device 5 according to the command torque, and thus, driving force is transmitted to left and right rear wheels 13, 14.

[0042] The relationship between the vehicle speed S and the steering angle θ of the steering wheel 18 and the command torque T is defined in the map information 622 that the control unit 611 refers to when the host vehicle 1 turns on a curved road. The command torque T tends to increase as the vehicle speed S increases and as the steering angle θ increases.

[0043] The crosswind influence estimation device 7 includes a CPU 71, a storage unit 72, a first communication circuit 73, and a second communication circuit 74. The CPU 71 functions as a computational processing unit. The storage unit 72 includes semiconductor memory elements such as ROM and RAM. The first communication circuit 73 communicates using an antenna 70. The second communication circuit 74 communicates via the in-vehicle communication network N. By executing a program 721 stored in the storage unit 72, the CPU 71 (i.e., a processor) functions as a first acquisition unit 711, a second acquisition unit 712, and an estimation unit 713.

[0044] The first acquisition unit 711 acquires information on crosswinds in a predetermined area in front of (i.e., in front of) the vehicle 1 in the direction of travel of the vehicle 1, for example, via road-to-vehicle communication. The second acquisition unit 712 acquires information on shields located on the windward side in the direction of the crosswind relative to the vehicle 1 (i.e., shields located on the windward side of the vehicle 1 in the direction of the crosswind) via inter-vehicle communication. When the first acquisition unit 711 acquires information on crosswinds via road-to-vehicle communication, the predetermined area is an area in which the first acquisition unit 711 can communicate with the roadside communication device 102. In this case, for example, the predetermined area is an area with a radius of 100 m. The second acquisition unit 712 acquires information on shields located on the windward side in the direction of the crosswind in the predetermined area.

[0045] Estimation unit 713 estimates the impact of the crosswind on host vehicle 1 based on the crosswind information acquired by first acquisition unit 711 and the information about the obstruction acquired by second acquisition unit 712. Furthermore, based on the estimation result, estimation unit 713 generates forecast information including the time or location at which the impact of the crosswind changes, and transmits the generated forecast information to control device 6 via onboard communication network N. The forecast information is a forecast value obtained by, assuming that vehicle 1 is traveling at the same speed and steering angle as at the time when estimation unit 713 generates the forecast information, forecasting the crosswind intensity based on the time elapsed after that time or at each location along the travel route of host vehicle 1, taking into account the presence of obstructions.

[0046] exist Figure 2 In the illustrated example, the first communication circuit 73 receives information on the wind direction and wind speed measured by the anemometer 103 and the position information of the roadside communication device 102 via communication with the roadside communication device 102, and then the first acquisition unit 711 acquires this information. Based on the acquired information, the first acquisition unit 711 calculates the wind speed having a component perpendicular to the direction of travel of the vehicle 1. The position information of the vehicle 1 can be acquired from, for example, the vehicle navigation system 17 via the in-vehicle network N.

[0047] When the four-wheel drive vehicle 1 is provided with a camera that captures an image of the scene in front of the vehicle 1 in the direction of travel of the vehicle 1, the first acquisition unit 711 can acquire information about the crosswind based on an image of a streamer (i.e., a wind vane) installed on the roadside. In addition, the second acquisition unit 712 can acquire information about obstructions based on the image captured by the above-mentioned camera. In this case, other vehicles and fixed objects (such as the sound barrier 101 and buildings) that are not provided with a communication function capable of performing inter-vehicle communication can be detected as obstructions, and the estimation unit 713 can generate forecast information taking into account the influence of the above-mentioned detected obstructions on the crosswind.

[0048] When the second acquisition unit 712 detects another vehicle capable of performing inter-vehicle communication with the host vehicle 1 as an obstruction, the second acquisition unit 712 acquires information on the other vehicle's speed and direction of travel via inter-vehicle communication. The estimation unit 713 generates forecast information including the time and location of changes in the influence of the crosswind based on the speed and direction of travel of the other vehicle. It should be noted that even when another vehicle is near the host vehicle 1, the second acquisition unit 712 does not detect the other vehicle as an obstruction if the other vehicle is located on the leeward side relative to the host vehicle 1 (i.e., if the other vehicle is located on the leeward side of the host vehicle 1) or if the other vehicle is moving away from the host vehicle 1.

[0049] When the second acquisition unit 712 detects another vehicle capable of performing inter-vehicle communication as an obstruction, the second acquisition unit 712 acquires information on the size of the other vehicle, including the total length and total height of the other vehicle. The estimation unit 713 generates forecast information including the time or position at which the influence of the crosswind on the host vehicle 1 increases and decreases based on the total length of the other vehicle. In addition, the estimation unit 713 estimates the magnitude of the influence of the crosswind on the host vehicle 1 based on the size of the other vehicle serving as the obstruction, and generates forecast information including this estimated value. In this embodiment, the yaw moment to be generated in the host vehicle 1 is estimated as the influence of the crosswind. The magnitude of the influence of the crosswind corresponds to the magnitude of the yaw moment.

[0050] Figure 4 Parts (a) to (e) in FIG. 1 are explanatory diagrams showing, in chronological order, a situation when the host vehicle 1 passes by the other vehicle 10 while turning on a curved road. Figure 4 The arrows A shown in parts (a) to (e) in FIG. 1 indicate the direction of the wind. Figure 5A is a graph showing an example of forecast information generated by the estimation unit 713. Figure 5B Graph showing the auxiliary driving force transmitted to the left and right rear wheels 13 , 14 when the driving force transmission device 5 is controlled based on the generated forecast information.

[0051] Figure 4 Parts (a) to (e) in FIG. 1 indicate a situation where the wind blows from the outside to the inside of a turn, and the arched arrows at the center of the vehicle 1 indicate the direction and magnitude of the yaw moment generated by the crosswind. The length of each arched arrow indicates the magnitude of the generated yaw moment. Figure 5A and Figure 5B In the example, the horizontal axis is the time axis and corresponds to Figure 4 The time points of the conditions shown in parts (a) to (e) are indicated as Ta to Te. That is, Figure 4 The time point of the situation shown in part (a) corresponds to Figure 5A and Figure 5B Ta in the graph shown. Similarly, Figure 4The conditions shown in parts (b) to (e) correspond to Figure 5A and Figure 5B Tb to Te as shown in the graph.

[0052] Figure 5A The portion above the time axis in indicates a tendency toward oversteering, and the portion below the time axis indicates a tendency toward understeering. Figure 5B The dotted line in the figure indicates the auxiliary driving force in the no-wind condition.

[0053] Generally speaking, when a vehicle turns, as the driving force transmitted to the wheels and the tire lateral force (cornering force) increase, and as the ground contact load of the tire decreases, lateral slip is more likely to occur. Therefore, in the four-wheel drive vehicle 1, as the auxiliary driving force transmitted to the left and right rear wheels 13, 14 increases, the tendency to oversteer increases, and as the auxiliary driving force transmitted to the left and right rear wheels 13, 14 decreases, the tendency to understeer increases. By utilizing the above-mentioned characteristics, when a yaw moment with a tendency to oversteer is generated by a crosswind, the auxiliary driving force is reduced. When a yaw moment with a tendency to understeer is generated by a crosswind, the auxiliary driving force is increased. Therefore, the driver can drive the four-wheel drive vehicle 1 while having a feeling similar to that in a no-wind situation.

[0054] Figure 4 Part (a) in the figure shows the situation before the host vehicle 1 and the other vehicle 10 overlap in the direction of the crosswind. In this situation, the host vehicle 1 is swung toward the inside of the turn due to the crosswind. Consequently, the crosswind generates a yaw moment that tends to oversteer. In this situation, the influence of the crosswind can be reduced by reducing the auxiliary driving force compared to a calm situation.

[0055] Figure 4 Part (b) in the figure shows a situation where a portion of the front side of the vehicle 1 overlaps with another vehicle 10 in the direction of the crosswind. In this situation, a portion of the rear side of the vehicle 1 is affected by the crosswind. As a result, the vehicle 1 is pulled toward the outside of the turn, resulting in severe understeer. In this situation, the influence of the crosswind can be reduced by increasing the auxiliary driving force.

[0056] Figure 4 Section (c) in FIG. 1 shows a situation where the host vehicle 1 overlaps the other vehicle 10 along its entire length and is located on the leeward side of the other vehicle 10. In this situation, the host vehicle 1 is temporarily shielded from the wind. Therefore, a yaw moment due to the crosswind is not generated, and an auxiliary driving force equivalent to that in a no-wind situation is transmitted to the left and right rear wheels 13 and 14. The length of time during which the host vehicle 1 is shielded from the wind varies depending on the total length of the other vehicle 10.

[0057] Figure 4Portion (d) in the figure indicates a situation where a portion of the rear side of the vehicle 1 overlaps with another vehicle 10 in the direction of the crosswind. In this situation, a portion of the front side of the vehicle 1 is affected by the crosswind. Consequently, the vehicle 1 is pulled toward the inside of the turn, resulting in severe oversteer. In this situation, the effects of the crosswind can be mitigated by reducing the auxiliary driving force.

[0058] Figure 4 The portion (e) in indicates that the host vehicle 1 has passed a position on the leeward side relative to the other vehicle 10 (i.e., a position on the leeward side of the other vehicle 10). In this situation, a yaw moment having an oversteering tendency is generated, which is equal to Figure 4 Part (a) in FIG. 1 shows the yaw moment of the vehicle 1 before it overlaps with the other vehicle 10 in the direction of the crosswind.

[0059] Before the yaw moment generated by the crosswind in the vehicle 1 actually changes, the crosswind influence estimating device 7 Figure 5A The prediction information of the yaw moment shown is transmitted to the control device 6. More specifically, for example, when the vehicle 1 is traveling a few meters ahead of the position where the front end portion of the vehicle 1 overlaps with the front end portion of the other vehicle 10 in the lateral direction, the crosswind influence estimation device 7 Figure 5A The predicted information of the yaw moment from Ta to Te shown is transmitted to the control device 6. With this configuration, the behavior of the host vehicle 1 can be stabilized without causing the driver to feel anxious, compared to a case where, for example, the current supplied to the electromagnetic coil 56 of the driving force transmission device 5 is increased or decreased after detecting a change in the yaw moment generated by the crosswind.

[0060] For example, the control unit 611 corrects the command torque by multiplying the command torque T obtained by referring to the map information 622 by a correction coefficient corresponding to the magnitude of the yaw moment indicated by the forecast information, and sets the duty cycle of the PWM signal to be supplied to the switching circuit 63 based on the corrected command torque.

[0061] Figure 6 Parts (a) to (e) in the diagram indicate in chronological order the wind blowing from the inside to the outside of the turn (i.e., at the same time as the Figure 4 An explanatory diagram of a situation in which the vehicle 1 is located on the leeward side of another vehicle 10 and passes by the other vehicle 10 when the wind blows in the direction opposite to the direction in parts (a) to (e)). Figure 7A is a graph showing an example of forecast information generated by the estimation unit 713 under the above-described situation. Figure 7B It is shown that when based on Figure 7A 1 is a graph showing the auxiliary driving force transmitted to the left and right rear wheels 13 and 14 when the driving force transmission device 5 is controlled using the forecast information shown.

[0062] When the crosswind blows from the inside to the outside of the turn, Figure 7A and Figure 7B As shown in FIG, the relationship between oversteering and understeering of the generated yaw moment and the increase and decrease of the auxiliary driving force are Figure 5A and Figure 5B The opposite of what is shown in .

[0063] According to the first embodiment of the present invention as described above, the influence of the crosswind on the vehicle 1 can be accurately estimated, taking into account the presence of an obstruction to the crosswind. Furthermore, the driving force transmission device 5 is controlled based on the estimated influence of the crosswind, taking into account the presence of the obstruction. Consequently, the vehicle's behavior can be stabilized by varying the auxiliary driving force in sync with changes in the influence of the crosswind, thereby reducing the influence of the crosswind.

[0064] Next, a second embodiment of the present invention will be described. In the first embodiment, the present invention is applied to a four-wheel drive vehicle 1 in which the front and rear wheel drive force distribution ratio can be controlled by the control device 6. In the second embodiment and the subsequent third and fourth embodiments, the present invention is applied to a four-wheel drive vehicle in which the drive force distribution ratio between the left and right wheels can be controlled, more specifically, the drive force distribution ratio between the left rear wheel 13 and the right rear wheel 14.

[0065] Figure 8 1A is a schematic diagram showing a configuration example of a four-wheel drive vehicle 1A according to the second embodiment. Figure 8 In, with reference Figure 1 The same components as those described above will be denoted by the same reference numerals, and detailed descriptions thereof will be omitted.

[0066] In the four-wheel drive vehicle 1A, the ring gear 461 of the rear rotating member 46 meshes with the pinion 201 provided at the rear end of the propeller shaft 20. The rear rotating member 46 includes a shaft portion 462 at its center. The left driving force transmission device 5L and the right driving force transmission device 5R are arranged close to the shaft portion 462 in the vehicle width direction. Similar to the configuration of the driving force transmission device 5 according to the first embodiment, the left driving force transmission device 5L and the right driving force transmission device 5R each include a housing 51, an inner shaft 52, a multi-plate clutch 53, a cam mechanism 54, an electromagnetic clutch 55, and an electromagnetic coil 56.

[0067] The housing 51 of the left driving force transmission device 5L is connected to the shaft portion 462 by the connecting shaft 471 and rotates integrally with the rear-side rotating member 46. The housing 51 of the right driving force transmission device 5R is connected to the shaft portion 462 by the connecting shaft 472 and rotates integrally with the rear-side rotating member 46. The drive shaft 23 is connected to the inner shaft 52 of the left driving force transmission device 5L so as to be unable to rotate relative to the inner shaft 52. The drive shaft 24 is connected to the inner shaft 52 of the right driving force transmission device 5R so as to be unable to rotate relative to the inner shaft 52.

[0068] An excitation current is supplied from the control device 6A to the electromagnetic coil 56 in each of the left and right driving force transmission devices 5L and 5R. In the second embodiment, the control device 6A can independently increase or decrease the excitation current supplied to the electromagnetic coil 56 in each of the left and right driving force transmission devices 5L and 5R. Thus, driving force is transmitted to the left rear wheel 13 in accordance with the current supplied to the electromagnetic coil 56 in the left driving force transmission device 5L. Driving force is transmitted to the right rear wheel 14 in accordance with the current supplied to the electromagnetic coil 56 in the right driving force transmission device 5R.

[0069] Based on the forecast information acquired from the crosswind influence estimation device 7, the control device 6A increases or decreases the current supplied to the electromagnetic coil 56 of each of the left and right driving force transmission devices 5L and 5R, depending on the estimated yaw moment to be generated. Specifically, when a counterclockwise yaw moment relative to the center of gravity of the four-wheel drive vehicle 1A is estimated to be generated by the crosswind, the control device 6A increases the current supplied to the electromagnetic coil 56 of the left driving force transmission device 5L, or decreases the current supplied to the electromagnetic coil 56 of the right driving force transmission device 5R, at that time, to generate a clockwise yaw moment. Furthermore, when a clockwise yaw moment relative to the center of gravity of the four-wheel drive vehicle 1A is estimated to be generated by the crosswind, the control device 6A increases the current supplied to the electromagnetic coil 56 of the right driving force transmission device 5R, or decreases the current supplied to the electromagnetic coil 56 of the left driving force transmission device 5L, at that time, to generate a counterclockwise yaw moment.

[0070] With this configuration, the vehicle behavior can be stabilized by controlling the driving force distribution ratio between the left rear wheel 13 and the right rear wheel 14 so that the influence of the crosswind is reduced.

[0071] Next, refer to Figure 9 A third embodiment of the present invention will be described. Figure 9 : is a schematic diagram showing an example of the configuration of a four-wheel drive vehicle 1B according to the third embodiment. Figure 9 In, with reference Figure 1 and Figure 8The same components as those described above will be denoted by the same reference numerals, and detailed descriptions thereof will be omitted.

[0072] In the first and second embodiments, a portion of the driving force from the engine 15 is distributed to the left and right rear wheels 13, 14. In the third embodiment, in addition to the engine 15, an electric motor 81 is provided as a driving source for driving the left and right rear wheels 13, 14. The driving force generated by the electric motor 81 is transmitted to the rear rotating member 46 via the reduction mechanism 82. The reduction mechanism 82 includes a pinion 821, a large diameter gear portion 822, and a small diameter gear portion 823. The pinion 821 is fixed to the shaft of the electric motor 81. The large diameter gear portion 822 meshes with the pinion 821. The small diameter gear portion 823 meshes with the ring gear 461. The large diameter gear portion 822 and the small diameter gear portion 823 are connected to each other so as not to rotate relative to each other.

[0073] In the third embodiment, the control device 6B controls the rotational speed and output torque of the electric motor 81 by supplying motor current to the electric motor 81. Furthermore, similar to the second embodiment, the control device 6B supplies excitation current to the electromagnetic coil 56 of each of the left and right driving force transmission devices 5L and 5R based on forecast information acquired from the crosswind influence estimation device 7, thereby offsetting the yaw moment estimated to be generated by the crosswind. With this configuration, the third embodiment also stabilizes the vehicle's behavior even when the four-wheel drive vehicle 1B is traveling while being affected by a crosswind.

[0074] Next, refer to Figure 10 A fourth embodiment of the present invention will be described. Figure 10 1C is a schematic diagram showing a configuration example of a four-wheel drive vehicle 1C according to a fourth embodiment. Figure 10 In, with reference Figure 1 The same components as those described above will be denoted by the same reference numerals, and detailed descriptions thereof will be omitted.

[0075] In the fourth embodiment, the four-wheel drive vehicle 1C includes a left-side electric motor 83 configured to drive the left rear wheel 13 and a right-side electric motor 84 configured to drive the right rear wheel 14. The driving force generated by the left-side electric motor 83 is transmitted to the drive shaft 23 via the left-side reduction mechanism 85. The driving force generated by the right-side electric motor 84 is transmitted to the drive shaft 24 via the right-side reduction mechanism 86.

[0076] The left-side speed reduction mechanism 85 includes a pinion 851, a large-diameter gear portion 852, and a small-diameter gear portion 853. The pinion 851 is fixed to the shaft of the left-side motor 83. The large-diameter gear portion 852 meshes with the pinion 851. The small-diameter gear portion 853 meshes with the gear portion 231 of the drive shaft 23. The large-diameter gear portion 852 and the small-diameter gear portion 853 are connected to each other so as to be unable to rotate relative to each other. The right-side speed reduction mechanism 86 includes a pinion 861, a large-diameter gear portion 862, and a small-diameter gear portion 863. The pinion 861 is fixed to the shaft of the right-side motor 84. The large-diameter gear portion 862 meshes with the pinion 861. The small-diameter gear portion 863 meshes with the gear portion 241 of the drive shaft 24. The large-diameter gear portion 862 and the small-diameter gear portion 863 are connected to each other so as to be unable to rotate relative to each other.

[0077] In the fourth embodiment, the control device 6C controls the rotational speed and output torque of the left and right motors 83, 84 by supplying motor current to the left and right motors 83, 84. Furthermore, the control device 6C supplies motor current to the left and right motors 83, 84 based on forecast information acquired from the crosswind influence estimation device 7 to offset the yaw moment estimated to be generated by the crosswind. With this configuration, the fourth embodiment also stabilizes the vehicle's behavior even when the four-wheel drive vehicle 1C is traveling while being affected by a crosswind.

[0078] Next, refer to Figure 11 The fifth embodiment of the present invention will now be described. In the first through fourth embodiments, control devices 6, 6A, 6B, and 6C are provided separately from crosswind influence estimation device 7, and the forecast information generated by crosswind influence estimation device 7 is transmitted to control devices 6, 6A, 6B, and 6C. However, in the fifth embodiment, control device 9 functions as crosswind influence estimation device 7.

[0079] Figure 11The control device 9 shown in FIG. 1 can be replaced with the control device 6 and crosswind influence estimation device 7 of the four-wheel drive vehicle 1 according to the first embodiment. The control device 9 includes a CPU 91, a storage unit 92, a switching circuit 93, a first communication circuit 94, and a second communication circuit 95. The switching circuit 93 generates current supplied to the electromagnetic coil 56 of the driving force transmission device 5. The first communication circuit 94 performs communication using the antenna 70. The second communication circuit 95 performs communication via the in-vehicle communication network N. The storage unit 92 stores a program 921 and map information 922. By executing the program 921, the CPU 91 (i.e., a processor) functions as a first acquisition unit 911, a second acquisition unit 912, an estimation unit 913, and a control unit 914. The functions of the first acquisition unit 911, the second acquisition unit 912, and the estimation unit 913 are the same as those of the first acquisition unit 711, the second acquisition unit 712, and the estimation unit 713 of the crosswind influence estimation device 7 according to the first embodiment. The functions of the control unit 914 are the same as those of the control unit 611 of the control device 6 according to the first embodiment.

[0080] By means of the above-described control device 9, the same operations and advantageous effects as those in the first embodiment can be achieved.

[0081] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments.

[0082] The embodiments of the present invention may be modified in various ways as appropriate by omitting a portion of the configuration or adding or replacing configurations within the scope of the present invention. For example, in the first to fourth embodiments, the control devices 6, 6A, 6B, and 6C that control the drive force distribution ratio obtain the forecast information generated by the crosswind influence estimation device 7. However, the forecast information generated by the crosswind influence estimation device 7 may be transmitted to, for example, a steer-by-wire system, and control may be performed to reduce the influence of the crosswind by changing the steering angle of the steering wheels.

[0083] In the above-described embodiments, the present invention is applied to four-wheel drive vehicles 1, 1A, 1B, and 1C. However, the present invention is not limited to four-wheel drive vehicles and can be applied to two-wheel drive vehicles in which the left and right front wheels are driven. In this case, even when the two-wheel drive vehicle is traveling while being affected by a crosswind, the vehicle's behavior can be stabilized by controlling the driving force transmitted to the left and right front wheels, thereby reducing the influence of the crosswind.

[0084] In the above embodiment, the left and right front wheels 11 and 12 are the main drive wheels, and the left and right rear wheels 13 and 14 are the auxiliary drive wheels. However, the present invention is not limited to this configuration, and the left and right front wheels 11 and 12 may be the auxiliary drive wheels, and the left and right rear wheels 13 and 14 may be the main drive wheels.

Claims

1. A crosswind influence estimation device, the crosswind influence estimation device being mounted in a vehicle and configured to estimate the influence of crosswind on the vehicle, the crosswind influence estimation device comprising: A processor configured to: i) acquiring information about the crosswind in a predetermined area ahead of the vehicle in the direction of travel of the vehicle; ii) obtaining information of shielding objects located on the windward side in the direction of the crosswind; and iii) estimating the impact of the crosswind on the vehicle based on the acquired crosswind information and the acquired shielding object information, wherein the processor is configured to estimate a yaw moment to be generated in the vehicle as an effect of the crosswind, Wherein, the processor is configured to: When the obstruction is another vehicle, obtaining information on the speed and travel direction of the other vehicle; and generating prediction information including a time or position of a change in the yaw moment based on the speed and travel direction of the other vehicle, The forecast information is a forecast value obtained in the following manner: assuming that the vehicle is traveling at the vehicle speed and steering angle at the time point when the forecast information is generated, taking into account the presence of the obstruction, the forecast is based on the time elapsed after the time point or the crosswind intensity at each position along the vehicle's driving route.

2. The crosswind influence estimation device according to claim 1, characterized in that: The processor is configured to: Further obtaining information about the length of the other vehicles; and The forecast information including the time or position at which the yaw moment increases and the time or position at which the yaw moment decreases is generated based on the total length of the other vehicle.

3. The crosswind influence estimation device according to any one of claims 1 to 2, characterized in that: The processor is configured to: obtaining information on the size of the shield; and The magnitude of the yaw moment is estimated based on the size of the obstruction.

4. A control device for a vehicle, the vehicle including wheels, the wheels including left and right front wheels and left and right rear wheels, the control device being configured to control a driving force distribution ratio for the wheels, the control device being characterized by comprising: at least one processor configured to: i) acquiring information about crosswinds in a predetermined area ahead of the vehicle in a traveling direction of the vehicle; ii) obtaining information of shielding objects located on the windward side in the direction of the crosswind; iii) estimating the effect of the crosswind on the vehicle based on the acquired crosswind information and the acquired shielding object information to obtain an estimation result; and iv) controlling the driving force distribution ratio for the wheels based on the obtained estimation result, wherein the processor is configured to estimate a yaw moment to be generated in the vehicle as an effect of the crosswind, The processor is configured to: When the obstruction is another vehicle, obtaining information on the speed and travel direction of the other vehicle; and generating prediction information including a time or position of a change in the yaw moment based on the speed and travel direction of the other vehicle, The forecast information is a forecast value obtained in the following manner: assuming that the vehicle is traveling at the vehicle speed and steering angle at the time point when the forecast information is generated, taking into account the presence of the obstruction, the forecast is based on the time elapsed after the time point or the crosswind intensity at each position along the vehicle's driving route.

5. The control device according to claim 4, characterized in that: The vehicle is a four-wheel drive vehicle in which i) one of the left and right front wheels and ii) the left and right rear wheels is a main drive wheel, and the other of i) the left and right front wheels and ii) the left and right rear wheels is an auxiliary drive wheel; and The at least one processor is configured to control a driving force transmitting device configured to transmit driving force to the auxiliary drive wheel.

6. The control device according to claim 4, characterized in that: The driving force distribution ratio between the left and right wheels of the wheels is variable; and The at least one processor is configured to control the driving force distribution ratio between the left and right wheels so that the yaw moment is reduced.

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