JP6539066B2 - Automobile - Google Patents

Description

  The present invention relates to a vehicle capable of switching between 2WD travel and 4WD travel.

  There are vehicles that enable any of the drive states of 4WD (four-wheel drive) traveling with front and rear wheels and 2WD (two-wheel drive) traveling one of the front and rear wheels. Depending on the state, it is possible to switch between 4WD travel and 2WD travel (part time 4WD etc.). At this time, for example, there is disclosed a technology in which a car constantly travels 4WD and switches from 4WD travel to 2WD travel at the time of sudden turning of the vehicle (for example, Patent Document 1). There is also disclosed a technology in which, if a slip occurs during 2WD traveling, the vehicle is switched to 4WD traveling, and returned to 2WD traveling when acceleration or steady driving is left (for example, Patent Document 2). In addition, while traveling 4WD, if the speed change is small and the speed difference between the left and right wheels is small, the vehicle will switch to 2WD and return to 4WD when the speed change is small and the speed difference between the left and right wheels becomes large. The disclosed technology is also disclosed (Patent Document 3).

  In addition, when switching between 4WD traveling and 2WD traveling is realized using the electronically controlled coupling, driving power is always consumed by the electronically controlled coupling while traveling 4WD. In view of the above, there has been disclosed a technology for reducing power consumption by supplying drive power to the electronically controlled coupling in a time-division (duty) manner while traveling 4WD (for example, Patent Document 4). In addition, there is also disclosed a technology in which when the EV switch is in the on state, a region operated by 4WD drive is set smaller than in the case where the EV switch is in the off state (for example, Patent Document 5).

Japanese Examined Patent Publication No. 5-37854 Japanese Examined Patent Publication No. 62-8334 Patent No. 3582375 gazette Japanese Patent Application Laid-Open No. 2002-225583 Patent No. 4225314

  In an automobile that switches between 2WD travel and 4WD travel as described above, if a large driving force is applied during 2WD travel, load is applied only to the drive wheels involved in 2WD travel, and parts of the drive system (for example, , The differential gear and the drive shaft may be damaged. Therefore, it is conceivable to disperse the driving force and prevent breakage of parts of the driving system by always performing 4WD traveling.

  However, as described above, the drive power is always consumed by the electronic control coupling during 4WD traveling, and for example, in an electric vehicle (EV) or a hybrid vehicle, it is used for traveling by consumption of a battery. The power available is reduced and will affect the distance traveled.

  An object of the present invention is to provide an automobile capable of reducing power consumption while avoiding damage to parts of a drive system in view of such problems.

In order to solve the above problems, the vehicle of the present invention comprises a transmission for transmitting the driving force output from the driving source to either the front wheel or the rear wheel, and the driving force output from the transmission for the front wheel or the rear wheel. The required driving force condition that requires a driving force of a predetermined driving threshold or more based on the traveling environment, an electronically controlled coupling transmitted to one of the other, a traveling environment recognition unit that recognizes the traveling environment outside the vehicle, and Coupling control to drive the electronically controlled coupling while 4WD travel is being performed, and a drive switching portion that performs 4WD travel when it is determined that the required driving force condition is satisfied comprising a part, the driving switching unit, after the 4WD running meet the requirements driving force conditions, the change in vehicle speed during a predetermined time threshold, if it is maintained within a predetermined speed range, 2 The D travel, characterized in row Ukoto.

  The required driving force condition is relative to the preceding vehicle in a state in which the following cruise control that follows the preceding vehicle is executed while maintaining the relative distance between the preceding vehicle and the host vehicle specified by the traveling environment recognition unit at a predetermined distance. The distance may be equal to or greater than a predetermined distance threshold, or the relative velocity to the preceding vehicle may be equal to or greater than a predetermined first velocity threshold.

  The required driving force condition may be that the difference between the target speed and the vehicle speed is equal to or greater than a predetermined second speed threshold while constant speed cruise control is performed while maintaining the vehicle speed at a predetermined target speed. .

  The required driving force condition may be that the slope of the road specified by the traveling environment recognition unit is equal to or higher than a predetermined first angle threshold and the vehicle speed is equal to or higher than a predetermined third speed threshold.

  The required driving force condition may be that the radius of curvature of the road specified by the traveling environment recognition unit is less than a predetermined length threshold and the vehicle speed is equal to or higher than a predetermined fourth speed threshold.

The vehicle may be a plug-in hybrid vehicle that includes an engine and a motor as drive sources, drives one or both of the engine and the motor when traveling, and can charge the battery for supplying power to the motor directly from the outside.
In order to solve the above problems, another vehicle of the present invention includes a transmission that transmits the driving force output from a driving source to either the front wheel or the rear wheel, and the driving force output from the transmission on the front wheel and the rear. Based on the driving environment in the power consumption reduction mode in which the 2WD driving is performed by stopping the drive of the electronically controlled coupling and the electronically controlled coupling transmitted to any other of the wheels, the traveling environment recognition unit that recognizes the traveling environment outside the vehicle A determination unit that determines that a driving force equal to or greater than a predetermined driving threshold that leads to damage to components of the driving system that transmits the driving force is required after an external factor, and if determined, from 2WD to 4WD Characterized by comprising: a drive switching unit for switching; and a coupling control unit for driving the electronic control coupling while 4WD travel is being performed. That.

  According to the present invention, it is possible to reduce power consumption while avoiding damage to parts of the drive system.

It is a figure showing composition of a car. It is a flowchart for demonstrating the traveling process by a control part.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values and the like shown in this embodiment are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the specification and the drawings, elements having substantially the same functions and configurations will be denoted by the same reference numerals to omit repeated description, and elements not directly related to the present invention will not be illustrated. Do.

  FIG. 1 is a diagram showing the configuration of a car 100. As shown in FIG. The vehicle 100 is capable of any driving condition such as 4WD (four-wheel drive) traveling with front and rear wheels and 2WD (two-wheel drive) traveling only the front wheels, and the engine 110, fuel tank 112, clutch 114, transmission 116, electronic control unit (hereinafter simply referred to as ECU) 118, motor 120, inverter 122, battery 124, propeller shaft 126, front differential gear 128, front drive shaft 130, front wheel 132, electronic control coupling 134, rear differential gear A rear drive shaft 138, a rear wheel 140, a control unit 142, a vehicle speed sensor 144, and an imaging device 146 are included.

  In the present embodiment, a plug-in hybrid vehicle (PHEV) that can be charged with electric energy directly from an external commercial outlet and can be switched between 2WD travel and 4WD travel is described as the automobile 100, in particular. . However, if the vehicle can travel by switching between 2WD travel and 4WD travel, the drive source may be either one or both of the engine and the motor; electric vehicles (EVs), engine cars, non plug-in Various types of vehicles such as hybrid vehicles (hybrid vehicles) can be adopted. Here, the configuration related to the feature of the present embodiment will be described in detail, and the description of the configuration unrelated to the feature of the present embodiment will be omitted.

  The engine 110 is composed of a gasoline engine or a diesel engine, and obtains driving power by burning fuel (gasoline, diesel, etc.) supplied from the fuel tank 112, and obtains driving power via the clutch 114. It is transmitted to the transmission 116. Engine 110 is connected to ECU 118, and the driving force is adjusted based on a control command of ECU 118.

  The motor 120 is coaxially arranged with the engine 110, obtains driving force by the power supplied from the battery 124 through the inverter 122, and transmits the obtained driving force to the transmission 116. In addition, the motor 120 also functions as a generator at a timing when the supply of power is not received, and the generated power is stored in the battery 124 via the inverter 122. The inverter 122 is connected to the ECU 118, and the supplied electric power (driving force of the motor 120) is adjusted based on a control command of the ECU 118.

  The driving force output from the driving source such as the engine 110 and the motor 120 is adjusted in torque, rotational speed and rotational direction by the transmission 116 and transmitted to the propeller shaft 126, and further through the front differential gear 128 and the front drive shaft 130. Is transmitted to the front wheel 132. Further, during 4WD traveling, the driving force output from the transmission 116 is also transmitted to the rear wheel 140 via the electronic control coupling 134, the rear differential gear 136, and the rear drive shaft 138. Here, the front wheel 132 obtains driving force directly from the transmission 116, and the rear wheel 140 obtains driving force via the electronic control coupling 134. However, the driving force is directly transmitted from the transmission 116 to the rear wheel 140. The driving force may be transmitted to the front wheel 132 via the electronic control coupling 134.

  The control unit 142 is constituted by a semiconductor integrated circuit including a central processing unit (CPU), a ROM storing programs and the like, and a RAM as a work area, and centrally controls the entire automobile 100. Further, in the present embodiment, the control unit 142 also functions as a traveling environment recognition unit 160, a condition determination unit 162, a drive switching unit 164, a coupling control unit 166, and a traveling mode switching unit 168. In addition, a vehicle speed sensor 144 and an imaging device 146 are also connected to the control unit 142. The vehicle speed sensor 144 detects the speed of the vehicle 100. The imaging device 146 includes an imaging element such as a charge-coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS), and can capture the front of the automobile 100 to generate a monochrome image or a color image. . The imaging devices 146 are paired in two, and are spaced apart substantially in the horizontal direction such that the optical axes thereof are substantially parallel on the traveling direction side of the vehicle 100. Further, the control unit 142 controls the driving force of the engine 110 and the motor 120 via the ECU 118.

(Operation of control unit 142)
In the automobile 100, as described above, it can be set to travel by switching between 2WD traveling and 4WD traveling. However, if a large driving force is applied (when requested) during 2WD traveling, only the driving wheels involved in the 2WD traveling are loaded, which may cause damage to parts of the drive system. On the other hand, if 4WD traveling is always performed to disperse the driving power, the electronic control coupling 134 consumes driving power at all times during the traveling, and the consumption of the battery 124 makes it possible to use the electric power available for traveling. Decrease and affect mileage. Therefore, in the present embodiment, it is determined in advance whether or not the driving force is required after the fact, and according to the determination result, the components of the driving system are efficiently switched by 2WD traveling and 4WD traveling. The purpose is to reduce power consumption while avoiding damage to the

  In addition, in the automobile 100 of the present embodiment, the front of the automobile 100 is imaged by the imaging device 146, and the traveling environment outside the automobile is recognized based on color information and position information in the imaged image. Here, the traveling environment is the condition of the road, the condition of a building located outside the road, the traveling condition of the vehicle traveling or crossing the road, the movement of a pedestrian, etc. in front of the vehicle 100 along with the traveling of the vehicle 100. Indicate comprehensive environmental information including status etc. Based on such a traveling environment, for example, the preceding vehicle or the like in the image is specified, and the relative distance with the preceding vehicle (inter-vehicle distance) is kept at a predetermined distance (while avoiding a collision). A so-called follow-up cruise control, or a so-called constant-speed cruise control in which the vehicle 100 travels while maintaining the speed of the vehicle 100 at a predetermined target speed. Here, the traveling environment is recognized using the functions used for such follow-up cruise control and constant-speed cruise control, and in particular, the leading vehicle and the road on which the host vehicle (car 100) travels are identified. And, based on the driving environment where the road is included, the situation where the driving force is required is determined after the fact.

  First, the traveling environment recognition unit 160 acquires image data from each of the two imaging devices 146, and generates a block corresponding to a block (for example, an array of 4 horizontal pixels × 4 vertical pixels) arbitrarily extracted from one of the two images. The parallax is derived using so-called pattern matching which is searched from the other image. Here, “horizontal” indicates the horizontal direction of the screen of the captured image, and “vertical” indicates the vertical direction of the screen of the captured image. The traveling environment recognition unit 160 performs such block-based parallax derivation processing for all blocks displayed in the detection area (for example, 600 horizontal pixels × 180 vertical pixels). Here, the block is set to 4 horizontal pixels × 4 vertical pixels, but the number of pixels in the block can be set arbitrarily.

  Subsequently, traveling environment recognition unit 160 derives three-dimensional position information including horizontal distance, height and relative distance using so-called stereo method based on the parallax for each block in the detection area. Here, the stereo method is a method of deriving the relative distance of the block to the imaging device 146 from the parallax of the block by using the triangulation method. At this time, the traveling environment recognition unit 160 determines the height of the block from the road surface based on the relative distance of the block and the distance from the point on the road surface which is the same relative distance as the block to the block. Derive

  Next, with reference to an arbitrary block, traveling environment recognition unit 160 has that block, the difference in horizontal distance, the difference in height, and the difference in relative distance within a predetermined range (for example, 0.1 m). Blocks are grouped assuming that they correspond to the same three-dimensional object. Thus, a three-dimensional object which is a virtual block group is generated. The above range is expressed by the distance in real space, and can be set to an arbitrary value by the manufacturer or the passenger. Also, with regard to the blocks newly added by grouping, the traveling environment recognition unit 160 further makes the blocks whose difference in horizontal distance, difference in height and difference in relative distance is within a predetermined range, with the block as a base point. Group As a result, all identical blocks and possible blocks can be grouped.

  Subsequently, if the grouped three-dimensional object satisfies a predetermined condition corresponding to a predetermined vehicle (for example, the three-dimensional object is positioned on the road, and the size of the entire three-dimensional object) If the object corresponds to the size of the specific object “vehicle”, the three-dimensional object is identified as the specific object “vehicle”. Then, traveling environment recognition unit 160 identifies a vehicle having the same traveling direction as that of vehicle 100 based on the positional relationship with vehicle 100 and the relative speed among the specific objects "vehicles", and sets the vehicle as the leading vehicle. The preceding vehicle identified in this way is the target of tracking in the following cruise control.

  In addition, if the three-dimensional object satisfies a predetermined condition corresponding to a predetermined road (for example, the traveling environment recognition unit 160 specifies a positional relationship with a roadside three-dimensional object such as a white line, a leading vehicle, or a guardrail). If it corresponds to an object "road", the three-dimensional object is specified as a specific object "road". Since the specification process of the specific thing by the traveling environment recognition part 160 demonstrated above can employ | adopt various existing techniques, such as patent 5580233, the detailed description is abbreviate | omitted here.

  The condition determination unit 162 requires (or is likely to require) a driving force condition after the driving force higher than a predetermined driving threshold value based on the traveling environment, in particular, the traveling state of the preceding vehicle. It is determined whether the condition is satisfied. With this configuration, it is possible to grasp in advance that a high driving force is required after the fact, and to efficiently switch between 2WD travel and 4WD travel.

  Here, as a situation where a driving force equal to or greater than a predetermined driving threshold value is required afterward, for example, during acceleration in follow-up cruise control (during acceleration of the host vehicle accompanying acceleration of a preceding vehicle) or in constant-speed cruise control At the time of acceleration (at the time of acceleration of the vehicle until reaching a constant speed) can be considered.

  In order to determine that acceleration is performed in the following cruise control, the relative distance between the preceding vehicle and the host vehicle specified by the traveling environment recognition unit 160 in the state where the following cruise control is being executed as the required driving force condition. Is equal to or greater than a predetermined distance threshold (for example, 10 m), or it may be satisfied that the relative velocity with respect to the preceding vehicle is equal to or greater than a predetermined first velocity threshold (10 km / h).

  Further, in order to determine that acceleration is being performed in constant speed cruise control, the target speed and the vehicle speed sensor 144 are detected while constant speed cruise control is being performed at a predetermined target speed as a required driving force condition. It is sufficient that the difference from the speed (vehicle speed) of the automobile 100 is equal to or greater than a predetermined second speed threshold (5 km / h).

  As described above, by appropriately determining the acceleration time in the following cruise control and the acceleration time in the constant speed cruise control, it is possible to appropriately grasp the timing at which a high driving force is required after the fact.

  In addition, the condition determination unit 162 can also determine, based on the traveling environment, in particular, the state of the road, whether or not the necessary driving force condition that the driving force equal to or more than a predetermined driving threshold is required is satisfied. With this configuration, as in the case based on the traveling state of the leading vehicle, it is possible to grasp in advance that a situation where a high driving force is required afterward and to efficiently switch between 2WD traveling and 4WD traveling. Become. In addition, here, the state of the road is determined based on the road specified by the traveling environment recognition unit 160, but the present invention is not limited thereto. For example, the traveling position in the road map may be GPS (Global Positioning System) or the like. The state of the road may be determined by specifying.

  Here, as a situation where a driving force equal to or higher than a predetermined driving threshold value is required afterward, for example, a case where the road gradient is large (uphill) or a case where the road curvature radius is short (curve) can be considered.

  In order to determine that the slope of the road is large, the speed of the vehicle 100 detected by the vehicle speed sensor 144 and the slope of the road specified by the traveling environment recognition unit 160 is equal to or greater than a predetermined first angle threshold. However, it may be satisfied that the vehicle speed is equal to or higher than a predetermined third speed threshold (for example, 10 km / h).

  Further, in order to determine that the curvature radius of the road is short, the curvature radius of the road is less than a predetermined length threshold as the required driving force condition, and the speed of the vehicle 100 detected by the vehicle speed sensor 144 is predetermined. It may be satisfied to be equal to or higher than a fourth speed threshold (e.g., 30 km / h).

  As described above, by appropriately determining the case where the road gradient is large or the case where the road curvature radius is short, it is possible to appropriately grasp the timing at which a high driving force is required afterward.

  Drive switching portion 164 can switch between 2WD travel and 4WD travel, and if condition determination portion 162 determines that the required driving force condition is satisfied, whichever 2WD travel or 4WD travel is being performed at that time , 4WD run. In addition, after the drive switching unit 164 performs the 4WD traveling while satisfying the required driving force condition, the change in the speed of the vehicle 100 detected by the vehicle speed sensor 144 is predetermined during a predetermined time threshold (for example, 5 seconds). If it is maintained within the speed range (for example, ± 5 km / h), that is, if the vehicle speed is stabilized, it returns to 2WD traveling (hysteresis characteristic). Drive switching unit 164 also performs 4WD traveling even when a high driving force (driving force equal to or greater than a predetermined driving threshold) is required as a result of the driver's operation of the accelerator pedal, brake pedal, etc. It is also good.

  The coupling control unit 166 drives the drive solenoid of the electronic control coupling 134 while 4WD traveling is being performed, and adjusts the duty of the front wheel 132 and the rear wheel 140 according to the traveling state to adjust to the rear wheel 140. Optimal driving force transmission.

  Here, when the condition determination unit 162 determines that the required driving force condition is satisfied, for example, during acceleration in follow-up cruise control, during acceleration in constant-speed cruise control, when the road gradient is large, the road curvature radius is short. In other words, in a situation where a high driving force is required afterward, switching to 4WD traveling can disperse the high driving force that can actually be generated by the subsequent rapid acceleration, so that breakage of parts of the driving system can be realized. It is possible to avoid (part protection). Further, while the required driving force condition is not satisfied or after the required driving force condition is satisfied, the change in the vehicle speed is maintained within the predetermined speed range for the predetermined time threshold. By performing the 2WD traveling, it is not necessary to drive the electronic control coupling 134, and it is possible to reduce the power consumption accordingly.

  Also, here, instead of switching to 4WD driving only after the situation where driving force is actually required, it is estimated in advance that such a situation will occur, and driving is switched to 4WD in advance. It is possible to improve the response of the state switching and to effectively disperse the required high driving force.

(Traveling process)
FIG. 2 is a flowchart for explaining the traveling process by the control unit 142. First, the traveling environment recognition unit 160 recognizes the traveling environment based on the image obtained by imaging the front of the automobile 100, and in particular, identifies a specific object such as a leading vehicle or a road (S200). Then, the condition determination unit 162 determines, based on the traveling state of the preceding vehicle, whether or not it is time to accelerate in the following cruise control (S202). Specifically, the condition determination unit 162 determines that the relative distance between the leading vehicle and the host vehicle is equal to or greater than a predetermined distance threshold or that the relative speed with the leading vehicle is at a predetermined value while the follow-up cruise control is being executed. If it is equal to or higher than the first speed threshold value, it is determined that acceleration is being performed in the following cruise control. Here, if the condition determination unit 162 determines that acceleration is not in follow-up cruise control (NO in S202), whether the condition determination unit 162 is in acceleration during constant-speed cruise control based on the traveling state of the host vehicle It is determined whether or not (S204). Specifically, the constant speed cruise control is performed if the difference between the target speed and the vehicle speed is equal to or higher than a predetermined second speed threshold while the constant speed cruise control is being executed at the predetermined target speed. It is determined that acceleration is in control.

  In addition, when the condition determination unit 162 determines that acceleration is not in constant speed cruise control (NO in S204), the condition determination unit 162 determines whether the road gradient is large based on the condition of the road (S206). ). Specifically, the condition determination unit 162 determines that the road gradient is large if the road gradient is equal to or greater than a predetermined first angle threshold and the vehicle speed is equal to or greater than a predetermined third velocity threshold. Here, when the condition determination unit 162 determines that the gradient of the road is not large (NO in S206), the condition determination unit 162 determines whether the curvature radius of the road is short based on the condition of the road (S208) . Specifically, the condition determination unit 162 determines that the curvature radius of the road is short if the curvature radius of the road is less than the predetermined length threshold and the vehicle speed is equal to or greater than the predetermined fourth speed threshold.

  Then, the condition determination unit 162 determines that acceleration is being performed in follow-up cruise control (YES in S202), or is it determined that acceleration is in constant-speed cruise control (YES in S204), or the road gradient is large If it is determined (YES in S206) or it is determined that the curvature radius of the road is short (YES in S208), the following processing is executed.

  That is, the drive switching unit 164 determines whether or not the current drive state is 4WD traveling (S210), and switches to 4WD traveling if it is not 4WD traveling (NO in S210) (S212). At this time, the coupling control unit 166 drives the electronic control coupling 134 to perform optimum driving force transmission to the rear wheel 140 according to the traveling state. If the current drive state is 4WD traveling (YES in S210), the 4WD traveling is maintained.

  In addition, when condition determination unit 162 determines that the curvature radius of the road is not short (NO in S208), whether or not the change in the speed of vehicle 100 is maintained within a predetermined speed range for a predetermined time threshold. If it is determined (S214) that the change in speed is not maintained within a predetermined speed range for a predetermined time threshold (NO in S214), the current drive state (2WD traveling or 4WD traveling) is maintained, and the speed is determined. If the change of is maintained within the predetermined speed range for the predetermined time threshold (YES in S214), the following processing is performed.

  That is, the drive switching unit 164 determines whether or not the current drive state is 2WD traveling (S216), and switches to 2WD traveling if it is not 2WD traveling (NO in S216) (S218). At this time, the coupling control unit 166 stops the drive of the electronic control coupling 134. If the current drive state is 2WD traveling (YES in S216), the 2WD traveling is maintained.

  As described above, in the automobile 100 according to the present embodiment, when accelerating in following cruise control, accelerating in constant-speed cruise control, when the road gradient is large, when the road curvature radius is short, etc. In a situation where driving force is required, switching to 4WD traveling can disperse high driving force that can actually be generated by subsequent rapid acceleration, thus avoiding damage to parts of the drive system (part protection). Can. In addition, 2WD traveling is performed while the required driving force condition is not satisfied or when the change in the vehicle speed is maintained within the predetermined speed range for the predetermined time threshold after the required driving force condition is satisfied. Since it is not necessary to drive the electronic control coupling 134, it is possible to reduce the power consumption accordingly. In short, it is possible to reduce power consumption in 2WD running while avoiding damage to parts of the drive system by 4WD running. In PHEV in particular, there is a need to increase the cruising distance of the motor alone. In the automobile 100 of the present embodiment, it is possible to extend the cruising distance of the motor travel by reducing the power consumption while enjoying the merit of 4WD. Also, here, since it is estimated in advance that such a situation will occur, and switching to 4WD traveling in advance, to improve the responsiveness of the drive state switching, to effectively disperse the required high driving force Is possible.

  Moreover, if the time occupancy ratio of 4WD traveling in the entire traveling can be increased within the range allowed by the power consumption, that is, if it is possible to lower the predetermined threshold, switching to 4WD traveling starts while the driving force required by the driver is low. As a result, the durability of the automobile 100 itself against the driving force does not have to be increased, and the manufacturing cost can be reduced.

  In addition, a program that causes a computer to function as the control unit 142, and a storage medium such as a computer readable flexible disk, a magneto-optical disk, a ROM, a CD, a DVD, a BD, etc. in which the program is recorded are also provided. Here, the program refers to data processing means described in any language or description method.

  Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such embodiments. It is obvious that those skilled in the art can conceive of various changes or modifications within the scope of the claims, and it is naturally understood that they are also within the technical scope of the present invention. Be done.

  For example, in the embodiment described above, the drive threshold, the distance threshold, the first speed threshold, the second speed threshold, the third speed threshold, the fourth speed threshold, the first angle threshold, the length threshold, the time threshold, and numerical values as the speed range However, the present invention is not limited to such a case, and any value can be set according to an experiment or actual traveling.

  Note that each step of the traveling processing in the present specification does not necessarily have to be processed in chronological order according to the order described as the flowchart, and may include processing in parallel or by a subroutine.

  The present invention can be applied to an automobile capable of switching between 2WD travel and 4WD travel.

100 car 116 transmission 134 electronic control coupling 146 imaging device 160 driving environment recognition unit 162 condition determination unit 164 drive switching unit 166 coupling control unit

Claims (7)

A transmission for transmitting the driving force output from the driving source to either the front wheel or the rear wheel;
An electronically controlled coupling for transmitting the driving force output from the transmission to either the front wheel or the rear wheel;
A traveling environment recognition unit that recognizes the traveling environment outside the vehicle;
A condition determination unit that determines whether or not a necessary driving force condition that a driving force equal to or greater than a predetermined driving threshold value is required is subsequently satisfied based on the traveling environment;
A drive switching unit that performs 4WD traveling when it is determined that the required driving force condition is satisfied;
A coupling control unit for driving the electronically controlled coupling while the 4WD travel is being performed;
Equipped with
The driving switching unit, after the 4WD running meets the main driving force conditions, the change in vehicle speed during a predetermined time threshold, if it is maintained within a predetermined speed range, rows 2WD running Ukoto A car characterized by   The required driving force condition is a state in which a following cruise control that follows the preceding vehicle is executed while maintaining the relative distance between the preceding vehicle specified by the traveling environment recognition unit and the host vehicle at a predetermined distance. The vehicle according to claim 1, wherein the relative distance to the vehicle is equal to or greater than a predetermined distance threshold, or the relative velocity to the preceding vehicle is equal to or greater than a predetermined first speed threshold.   The required driving force condition is that a difference between the target speed and the vehicle speed is equal to or higher than a predetermined second speed threshold while constant speed cruise control is performed while maintaining the vehicle speed at the predetermined target speed. The vehicle according to claim 1 or 2, characterized in that.   The driving force requirement is characterized in that the gradient of the road specified by the traveling environment recognition unit is equal to or higher than a predetermined first angle threshold, and the vehicle speed is equal to or higher than a predetermined third speed threshold. A car according to any one of the preceding.   The driving force condition is characterized in that the curvature radius of the road specified by the traveling environment recognition unit is less than a predetermined length threshold, and the vehicle speed is equal to or higher than a predetermined fourth speed threshold. A car according to any one of 4. A plug-in hybrid vehicle comprising an engine and a motor as the drive source, and driving one or both of the engine and the motor when traveling, and capable of directly charging a battery for supplying power to the motor from the outside. The car according to any one of claims 1 to 5 . A transmission for transmitting the driving force output from the driving source to either the front wheel or the rear wheel;
An electronically controlled coupling for transmitting the driving force output from the transmission to either the front wheel or the rear wheel;
A traveling environment recognition unit that recognizes the traveling environment outside the vehicle;
In reducing power consumption mode in which to 2WD travel stops driving of the electronic controlled coupling, the driving environment with outside factors rather based on a predetermined or more driving threshold leading to damage to the drive system components for transmitting a driving force and determine tough driving force you determined a posteriori needs,
A drive switching portion for switching to 4WD running from the 2WD running to be the determination Gana,
A coupling control unit for driving the electronically controlled coupling while the 4WD travel is being performed;
An automobile characterized by comprising.

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