Vehicle travel control method and device

Abstract

In a case where a vehicle has multiple driving characteristics, from which one driving characteristic can be selected, front wheels and rear wheels have multiple driving force distribution characteristics, from which one driving force distribution characteristic can be selected, and the driving characteristic and the driving force distribution characteristic can be selected independently of each other, the present invention sets in advance driving force distribution characteristics for the front wheels and rear wheels, which are appropriate for each driving characteristic, and when one driving characteristic is selected, causes the driving force distribution characteristic for the front wheels and rear wheels to transition to the one appropriate for the selected driving characteristic on the basis of the selected driving characteristic.

Description

Vehicle driving control method and device

[0001] The present invention relates to a vehicle driving control method and device.

[0002] For example, since it has become possible to control the amount of fuel injected into the engine, which is the vehicle's power source, and the ignition timing, an increasing number of vehicles have been developed that allow multiple driving characteristics of the vehicle to be selected as driving modes, and control the output characteristics of the drive source to achieve driving characteristics corresponding to the selected driving mode. Controlling the output characteristics of the drive source is even easier for vehicles equipped with an electric motor as the drive source. One method for achieving multiple driving characteristics is to change the transmission's shift line. Meanwhile, an increasing number of vehicles are now capable of controlling the distribution of driving force between the vehicle's front and rear wheels. Some vehicles allow the occupant to select the characteristics of the driving force distribution between the front and rear wheels. In Patent Document 1 listed below, when rain is detected, a four-wheel drive mode, which distributes driving force equally between the front and rear wheels, is recommended to the occupant.

[0003] JP 2011-156933 A

[0004] However, the driving force distribution characteristics for the front and rear wheels can only be selected and switched by the occupant, and even if driving characteristics suitable for slippery road conditions are selected, there is a risk that the drive wheels may slip or that appropriate vehicle driving characteristics will not be achieved unless the occupant selects driving force distribution characteristics for the front and rear wheels suitable for those road conditions.An object of the present invention is to provide a vehicle driving control method and device that can achieve appropriate vehicle driving characteristics.

[0005] One aspect of the present invention is to provide a vehicle having a plurality of driving characteristics, one of which can be selected, a vehicle having a plurality of driving force distribution characteristics for the front and rear wheels, one of which can be selected, and the driving characteristics and driving force distribution characteristics can be selected independently, by presetting a driving force distribution characteristic for the front and rear wheels that is suitable for each of the driving characteristics, and when one of the driving characteristics is selected, transitioning to a driving force distribution characteristic for the front and rear wheels that is suitable for the selected driving characteristic based on the selected driving characteristic.

[0006] According to one aspect of the present invention, when a driving characteristic is selected, a transition to a driving force distribution characteristic between the front and rear wheels that is suitable for that driving characteristic is made. For example, a driving characteristic suitable for a slippery road surface can be achieved by a driving force distribution characteristic between the front and rear wheels that is suitable for that driving characteristic. The objects and advantages of the present invention are realized and attained by using the elements and combinations thereof set forth in the appended claims. It should be understood that both the foregoing general description and the following detailed description are merely exemplary and explanatory and are not intended to limit the invention as defined by the claims.

[0007] It is a schematic diagram showing an example of a vehicle driving control system of an embodiment. It is an explanatory diagram of a transmission shift line performed in the driving characteristics of the vehicle of FIG. 1. It is a flowchart showing an example of calculation processing performed by the transfer controller of FIG. 1. It is an appropriateness table showing whether or not a drive mode-transfer mode can be selected. It is a switching control map for automatic transition between the drive mode and the transfer mode.

[0008] The vehicle cruise control system of the embodiment shown in FIG. 1 is installed in a four-wheel drive vehicle capable of distributing driving force between front wheels 1F and rear wheels 1R. The vehicle is equipped with an engine and / or electric motor (not shown) as a driving force source, and a transmission (not shown) for converting the output of the driving force source into driving force corresponding to the vehicle speed. A transfer 2 is provided between the transmission and the front wheels 1F and rear wheels 1R, capable of adjusting the distribution of driving force between the front wheels 1F and rear wheels 1R. The transfer 2 generally adjusts the distribution of driving force between the front wheels 1F and rear wheels 1R by controlling the engagement state of a friction element such as a clutch. In this embodiment, the engagement state of the friction element is controlled by a transfer actuator 3 such as an electric motor. In this vehicle, as an example, the rear wheels 1R are set as primary driving wheels and the front wheels 1F are set as secondary driving wheels. When the driving force distribution to the front wheels 1F is zero, the vehicle is in a two-wheel drive state in which only the rear wheels 1R are used for driving. In this embodiment, an auxiliary transmission is incorporated within the transfer case 2, and depending on the operating state of this auxiliary transmission, the vehicle can be switched between a high-speed direct-coupled state (4H), in which the driving force is equally distributed (50:50) between the front wheels 1F and the rear wheels 1R, and a low-speed direct-coupled state (4L), in which the driving force is increased even more. However, since the low-speed direct-coupled state 4L can only be switched manually, it will be omitted from the following description, which focuses on automatic control of the driving force distribution between the front wheels 1F and the rear wheels 1R. Note that there are also vehicles in which the transfer case 2 is incorporated within the transmission case, and vehicles equipped with such a transfer case 2 can also be subject to the vehicle cruise control system of the present invention.

[0009] The vehicle is provided with a transfer mode (hereinafter referred to as T / F mode) selection means, such as a switch (lever) 4, which allows selection of the operating state of the transfer 2, i.e., the driving force distribution characteristics between the front wheels 1F and the rear wheels 1R. The operating state of the transfer actuator 3 is controlled by a transfer controller 5. In this vehicle, in addition to the high-speed direct (4H) mode and low-speed direct (4L) mode described above, an auto mode can be selected, which automatically optimizes the driving force distribution between the front wheels 1F and the rear wheels 1R. The word "mode" here refers to the "style" or "state" of the English word "mode." For example, in the auto mode, driving force is distributed only to the rear wheels 1R, which are the main driving wheels, during normal driving, and if the rear wheels 1R slip, driving force corresponding to the slip state is also distributed to the front wheels 1F. Furthermore, driving force is also distributed to the front wheels 1F depending on the vehicle's driving state, for example, when the vehicle starts moving. Furthermore, when the front wheels 1F and rear wheels 1R are directly coupled, the friction elements in the transfer 2 described above are fully engaged. These are achieved by calculations executed within the transfer controller 5. For this reason, the vehicle is provided with a control input acquisition means such as a sensor that detects the rotation state of the wheels. As mentioned above, in the following explanation, only the high-speed direct (4H) mode and the auto mode will be explained regarding the T / F mode.

[0010] The transfer controller 5 is an electronic control unit (ECU) that performs the above-described arithmetic processing and the arithmetic processing described below and outputs control commands to the transfer actuator 3. Therefore, the transfer controller 5 includes a computer system with advanced arithmetic processing capabilities. Like well-known computer systems, this computer system includes a processor 9 that exhibits advanced arithmetic processing capabilities and a storage device 10 that stores information such as programs and sensor signals. The processor 9 may be, for example, a central processing unit (CPU) or a microprocessing unit (MPU). The storage device 10 may be a semiconductor storage device, a magnetic storage device, or an optical storage device. The storage device 10 may further include a register, a cache memory, and a memory used as a main storage device. The arithmetic processing performed by the transfer controller 5 is realized, for example, by the processor 9 executing a computer program stored in the storage device 10 of the transfer controller 5. The arithmetic processing performed by the transfer controller 5 may also be executed by a functional logic circuit configured in a general-purpose semiconductor integrated circuit. For example, the transfer controller 5 may include a programmable logic device such as a field programmable gate array. The vehicle is also equipped with a drive source controller that controls the operating state of the drive source and a transmission controller that controls the operating state of the transmission, and these other controllers have the same configurations and functions. The controllers can also share data and communicate with each other. The vehicle is also equipped with a monitor 8 that displays image information from the navigation system, etc., and the transfer controller 5 is also connected to the monitor 8. The monitor 8 is also equipped with a speaker that can output audio.

[0011] The vehicle is also equipped with a driving mode (hereinafter, D mode) selector 7 for varying the vehicle's driving characteristics. As shown in FIG. 4 , the D modes include a standard mode that displays typical vehicle driving characteristics, an eco mode that displays driving characteristics that reduce environmental impact, a sport mode that displays driving characteristics that offer excellent maneuverability, and a snow mode that displays driving characteristics suitable for slippery surfaces such as snow, ice, and slush. The D modes also include a rock mode that displays driving characteristics suitable for traversing gravel and rocky terrain, a sand mode that displays driving characteristics suitable for traversing sandy terrain, a mud / rut mode that displays driving characteristics suitable for traversing muddy roads, ruts, and riverbeds, and a tow mode that displays driving characteristics suitable for trailer towing. Note that gravel refers to areas where debris accumulates. The driving characteristics corresponding to each D mode are achieved by changing the output characteristics of the drive source and the gear shift characteristics of the transmission. FIG. 2 shows an example of transmission shift lines in standard mode, sport mode, and eco mode. In this example, the shift lines are set to higher speeds in sport mode and lower speeds in eco mode compared to standard mode, resulting in brisk driving characteristics in sport mode and reduced environmental impact in eco mode. These are controlled by the transmission controller. In addition, when changing the output characteristics of the drive source, the drive force can be increased or decreased by adjusting the fuel injection amount for the engine and the applied current for the drive motor. These are controlled by the drive source controller.

[0012] As can be seen from the above, in this embodiment, the D mode (driving characteristics) and the T / F mode (drive force distribution characteristics) can be selected independently. Meanwhile, as will be described later, when the D mode is selected, control is also performed to automatically transition to the T / F mode, and switching between the two is performed by turning the automatic transition switch 6 on and off. That is, as an example, when the automatic transition switch 6 is on, automatic transition to a T / F mode suitable for the D mode is enabled, and when the automatic transition switch 6 is off, linked transition between the D mode and the T / F mode is not performed (disabled). The flowchart in FIG. 3 shows the calculation process for automatic transition to a T / F mode suitable for the D mode. This calculation process is executed, for example, at a predetermined sampling period. First, in step S1, the D mode selected by the D mode selector 7 and the T / F mode selected by the T / F mode selection switch 4 are read. Next, the process proceeds to step S2, where it is determined whether the automatic transition switch 6 is on. If the automatic transition switch 6 is on, the process proceeds to step S3; if not, the process returns.

[0013] In step S3, it is determined whether the D mode has been switched (since the previous reading). If the D mode has been switched, the process proceeds to step S4; if not, the process returns. In step S4, a D mode-T / F mode appropriateness table (a table in the figure) and a switching control map, which will be described later, are referenced. Next, in step S5, based on the reference to the D mode-T / F mode appropriateness table and the switching control map, it is determined whether an automatic transition to a T / F mode appropriate for the D mode after switching is to be performed. If an automatic transition to T / F mode is to be performed, the process proceeds to step S6; if not, the process returns. In step S6, a T / F mode appropriate for the D mode after switching is read from the appropriateness table and the switching control map. In step S7, the operating state of the transfer (T / F in the figure) actuator 3 is controlled (a control signal is output) so that the T / F mode to which the automatic transition is to be performed is achieved. Next, in step S8, the process proceeds to displaying the automatic T / F mode transition on the monitor 8 and then returning. The content of the display on the monitor 8 may also be output as audio from the speaker. According to this calculation process, if a T / F mode suitable for the D mode after switching exists and automatic transition to that T / F mode is permitted, automatic transition to that T / F mode is executed.

[0014] This is performed according to the suitability table of FIG. 4 and the switching control map of FIG. 5. In the suitability table of FIG. 4, the D mode is arranged vertically and the T / F mode is arranged horizontally, indicating whether the combination of the two is suitable or not. An x in the figure indicates an inappropriate combination, a ◯ indicates a suitable combination, and a ⊚ indicates a more recommended combination than suitable. For example, when the D mode is Rock mode, Sand mode, or Mud / Rat mode, only the 4H mode is suitable for the T / F mode, and Auto mode is not used. On the other hand, when the D mode is Eco mode or Sport mode, only Auto mode is suitable (recommended) for the T / F mode, and 4H mode is not used. When the D mode is Standard mode, Snow mode, or Tow mode, 4H mode is also suitable for the T / F mode, but Auto mode is more recommended. In the switching control map of FIG. 5, X and O indicate whether automatic transition between the T / F modes before and after switching is performed, with O indicating automatic transition and X indicating no automatic transition. The leftmost side of the figure indicates the T / F mode before switching, the right side indicates the T / F mode after switching, and the right side of that indicates whether automatic transition is performed. The x, ◯, and ◎ in the auto mode and 4H mode in the figure indicate the combinations of auto mode and 4H mode in Figure 4, and the auto mode or 4H mode surrounded by ◯ indicates the T / F mode selected (before switching) or to which automatic transition is performed (after switching).

[0015] In this switching control map, when 4H mode is selected with an inappropriate combination of auto mode and 4H mode and then switched to an inappropriate combination of auto mode and 4H mode, 4H mode will essentially remain in operation, and no automatic transition to the T / F mode will be performed. Also, when auto mode is recommended and 4H mode is switched to an appropriate combination, an automatic transition to auto mode will be performed. Also, when auto mode is recommended and 4H mode is switched to an inappropriate combination, an automatic transition to auto mode will be performed. Also, when auto mode is selected with an appropriate combination of auto mode and 4H mode and then switched to an inappropriate combination of auto mode and 4H mode, an automatic transition to 4H mode will be performed. Also, when auto mode is recommended and 4H mode is switched to an appropriate combination, auto mode will essentially remain in operation, and no automatic transition to the T / F mode will be performed. Also, when auto mode is recommended and 4H mode is switched to an inappropriate combination, auto mode will essentially remain in operation, and no automatic transition to the T / F mode will be performed.

[0016] Furthermore, when 4H mode is selected with a recommended combination of auto mode and 4H mode appropriate, and then switched to an inappropriate combination of auto mode and 4H mode appropriate, 4H mode will essentially remain in effect, and no automatic transition to T / F mode will be performed. When auto mode is recommended and 4H mode is switched to an appropriate combination, an automatic transition to auto mode will be performed. When auto mode is recommended and 4H mode is switched to an inappropriate combination, an automatic transition to auto mode will be performed. When auto mode is selected with a recommended combination of auto mode and 4H mode appropriate, and then switched to an inappropriate combination of auto mode and 4H mode appropriate, an automatic transition to 4H mode will be performed. When auto mode is recommended and 4H mode is switched to an appropriate combination, auto mode will essentially remain in effect, and no automatic transition to T / F mode will be performed. When auto mode is recommended and 4H mode is switched to an inappropriate combination, auto mode will essentially remain in effect, and no automatic transition to T / F mode will be performed.

[0017] However, in this embodiment, even if the automatic transition switch 6 is in the on state and the T / F mode is automatically transitioned after switching to the D mode, if the occupant selects a different T / F mode with the T / F mode selection switch 4, the T / F mode is switched to the selected T / F mode. This places importance on the occupant's intention to select, reflecting the fact that the T / F mode selected by the occupant may be more appropriate under actual road surface conditions. Also, as described above, when the automatic transition switch 6 is in the off state, the automatic transition of the T / F mode accompanying switching to the D mode is not executed (is disabled). This also places importance on the occupant's intention to select, reflecting the fact that the T / F mode selected by the occupant may be more appropriate under actual road surface conditions.

[0018] In this manner, in this vehicle cruise control system, when the vehicle has a plurality of D modes for its driving characteristics, one of which can be selected, a plurality of T / F modes for its driving force distribution characteristics for the front wheels 1F and the rear wheels 1R, one of which can be selected, and the D mode and the T / F mode can be selected independently, a T / F mode suitable for each D mode is set in advance, and when one of the D modes is selected, the system transitions to the T / F mode suitable for the selected D mode based on the selected D mode. This makes it possible to achieve driving characteristics suitable for, for example, slippery road conditions by using driving force distribution characteristics suitable for the front wheels 1F and the rear wheels 1R.

[0019] Furthermore, by being able to disable the transition to the T / F mode suitable for the selected D mode, it is possible to place importance on the occupant's intention to select a suitable T / F mode selected by the occupant for actual road surface conditions. Furthermore, by being able to select a T / F mode after transition to the T / F mode suitable for the selected D mode, it is possible to place importance on the occupant's intention to select a suitable T / F mode selected by the occupant for actual road surface conditions.

[0020] The D-mode includes at least two of the following modes: an eco mode that reduces environmental impact, a sport mode that offers excellent maneuverability, and a snow mode that is suitable for slippery road surfaces. The T / F modes include an auto mode that controls the drive force distribution between the front wheels 1F and the rear wheels 1R in accordance with at least one of the wheel slip state and the vehicle's driving state, and a direct mode that distributes the drive force equally between the front wheels 1F and the rear wheels 1R. This allows for a combination of driving characteristics suited to a variety of driving environments and needs and drive force distribution characteristics suited to those driving characteristics between the front wheels 1F and the rear wheels 1R. Furthermore, by recommending and transitioning to the auto mode when the snow mode is selected, driving characteristics suitable for slippery road surfaces are achieved by the drive force distribution characteristics suited to those driving conditions.

[0021] The multiple D modes are achieved by changing at least one of the drive source output characteristics and the transmission shift line characteristics. This allows the vehicle to have driving characteristics suited to a variety of driving environments and needs. Furthermore, the transition to the T / F mode suited to the selected D mode is displayed and / or output as audio, allowing the occupant to be aware of the automatic transition to the T / F mode.

[0022] Although the vehicle driving control method and device according to the embodiment have been described above, the present invention is not limited to the configurations described in the above embodiment and various modifications are possible within the scope of the present invention. For example, the appropriate table and switching control map for the D mode and T / F mode in the above embodiment are only examples, and appropriate combinations and switching controls other than those described above are also possible. Furthermore, the types and combinations of the D mode and T / F mode are only examples, and D mode and T / F mode other than those described above can be set as appropriate.

[0023] 1F...front wheels, 1R...rear wheels, 2...transfer, 3...transfer actuator, 4...transfer mode selection switch, 5...transfer controller (controller), 6...automatic transition switch, 7...driving mode selector, 8...monitor

Claims

1. A vehicle running control method, which has a plurality of running characteristics of a vehicle, can select one running characteristic from the plurality of running characteristics, has a plurality of driving force distribution characteristics of front and rear wheels, can select one driving force distribution characteristic from the plurality of driving force distribution characteristics, and the running characteristics and the driving force distribution characteristics can be independently selected. In this method, the driving force distribution characteristics of the front and rear wheels suitable for each of the running characteristics are preset, and when any one of the running characteristics is selected, based on the selected running characteristic, it is characterized in that it is shifted to the driving force distribution characteristics of the front and rear wheels suitable for the selected running characteristic.

2. The vehicle running control method according to claim 1, characterized in that the transition to the driving force distribution characteristics of the front and rear wheels suitable for the selected running characteristic can be invalidated.

3. The vehicle running control method according to claim 1, characterized in that the driving force distribution characteristics to the front and rear wheels can be selected after the transition to the driving force distribution characteristics of the front and rear wheels suitable for the selected running characteristic.

4. As the running characteristics, it has at least two or more modes among an eco-mode capable of reducing environmental load, a sports mode with excellent maneuverability, and a snow mode suitable for a slippery road surface. As the driving force distribution characteristics, it has an auto mode in which the driving force distribution of the front and rear wheels is controlled according to at least one of the slip state of the wheels and the running state of the vehicle, and a direct connection mode in which the driving force distribution of the front and rear wheels is equally divided. The vehicle running control method according to claim 1 is characterized in that it has.

5. The vehicle running control method according to claim 4, characterized in that when the snow mode is selected, it is recommended to transition to the auto mode.

6. The vehicle running control method according to claim 1, characterized in that the plurality of running characteristics are achieved by changing at least one of the output characteristics of the drive source and the shift line characteristics of the transmission.

7. The vehicle running control method according to claim 1, characterized in that the transition to the driving force distribution characteristics of the front and rear wheels suitable for the selected running characteristic is displayed and / or output by voice.

8. In a vehicle travel control device that has a plurality of driving characteristics of a vehicle, one driving characteristic can be selected from the plurality of driving characteristics, has a plurality of driving force distribution characteristics between the front wheels and the rear wheels, and one driving force distribution characteristic can be selected from the plurality of driving force distribution characteristics, and the driving characteristics and the driving force distribution characteristics can be independently selected, a controller is provided that presets the driving force distribution characteristics between the front wheels and the rear wheels suitable for each of the driving characteristics, and when any one of the driving characteristics is selected, based on the selected driving characteristic, makes a transition to the driving force distribution characteristics between the front wheels and the rear wheels suitable for the selected driving characteristic. A vehicle travel control device characterized by having such a controller.

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