JP7225733B2 - Driving mode control device for four-wheel drive vehicle - Google Patents

Description

The present invention relates to a driving mode control device for a four-wheel drive vehicle.

In Patent Document 1, a hybrid vehicle that has an internal combustion engine and a rotating electric machine as power sources and can independently drive the front wheels and the rear wheels by the rotating electric machine. Disclosed is one with an EV switch to activate.

In this hybrid vehicle, when the EV switch is in the ON state, the four-wheel drive condition is changed so that the region in which the vehicle operates in four-wheel drive is reduced compared to when the EV switch is in the OFF state. Power consumption is suppressed by expanding the operating area.

JP 2007-168690 A

However, in the above-described conventional hybrid vehicle, when an EV switch is operated by an occupant during four-wheel drive driving, if the driving environment at that time is, for example, a rough road, the vehicle is switched to EV driving. The behavior of the vehicle may become unstable.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a driving mode control device for a four-wheel drive vehicle that can ensure the stability of the behavior of the vehicle during four-wheel drive running. and

In order to achieve the above object, the present invention provides an engine that drives either one of the front wheels and the rear wheels, a motor that drives the other of the front wheels and the rear wheels, and a battery that supplies power to the motor. wherein at least one of the engine and the motor is driven according to the running state of the four-wheel drive vehicle as the running mode of the four-wheel drive vehicle. The vehicle has a normal mode in which the vehicle runs by power, a four-wheel drive mode in which the vehicle runs by the driving force of both the engine and the motor, and an EV mode in which the vehicle runs only by the driving force of the motor, and the normal mode and the EV mode. a first switching unit for switching between the normal mode and the four-wheel drive mode; a second switching unit for switching between the normal mode and the four-wheel drive mode; and a control unit that sets a running mode to either an EV mode or the four-wheel drive mode, wherein the control unit selects the EV mode by the first switching unit and the second switching unit. When the four-wheel drive mode is selected by the unit, the driving mode is set to the normal mode.

According to the present invention, it is possible to provide a driving mode control device for a four-wheel drive vehicle that can ensure the stability of the behavior of the vehicle during four-wheel drive driving.

FIG. 1 is a schematic configuration diagram of a four-wheel drive vehicle according to one embodiment of the present invention. FIG. 2 is a flow chart showing the flow of processing for determining the driving mode executed by the VCM mounted on the four-wheel drive vehicle according to one embodiment of the present invention. FIG. 3 is a diagram showing an example of a timing chart when operating the EV mode switch in the four-wheel drive vehicle according to one embodiment of the present invention.

A driving mode control device for a four-wheel drive vehicle according to an embodiment of the present invention includes an engine that drives either one of the front wheels or the rear wheels, a motor that drives the other of the front wheels or the rear wheels, and A driving mode control device for a four-wheel drive vehicle, comprising: a battery for supplying electric power; , a four-wheel drive mode in which the vehicle travels with the driving force of both the engine and the motor, and an EV mode in which the vehicle travels only with the driving force of the motor, and switches between the normal mode and the EV mode. A first switching section, a second switching section for switching between the normal mode and the four-wheel drive mode, and a normal mode, an EV mode, and a four-wheel drive mode based on the first switching section and the second switching section. a control unit for setting the driving mode, wherein the control unit, when the EV mode is selected by the first switching unit and the four-wheel drive mode is selected by the second switching unit, It is characterized by setting the driving mode to the normal mode. As a result, the driving mode control device for a four-wheel drive vehicle according to one embodiment of the present invention can ensure the stability of the behavior of the vehicle during four-wheel drive driving.

A four-wheel drive vehicle equipped with a driving mode control device according to an embodiment of the present invention will now be described with reference to the drawings.

As shown in FIG. 1, a four-wheel drive vehicle 1 includes an engine 2, a transmission 3, a motor generator 4 as a motor, front wheels 5 and rear wheels 6, and an ECM (Engine Control Module) 11 for controlling the engine 2. , a TCM (Transmission Control Module) 12 that controls the transmission 3, and a VCM (Vehicle Control Module) 13 as a control section.

The four-wheel drive vehicle 1 of this embodiment drives the front wheels 5 with the power of the engine 2, drives the rear wheels 6 with the power of the motor generator 4, and adjusts the distribution of the driving force between the engine 2 and the motor generator 4. Two-wheel drive or four-wheel drive can thus be switched. In this embodiment, the engine 2 drives the front wheels 5 and the motor generator 4 drives the rear wheels 6. On the contrary, the engine 2 drives the rear wheels 6 and the motor generator 4 drives the front wheels 5. It is good also as a structure which carries out.

A plurality of cylinders are formed in the engine 2 . In this embodiment, the engine 2 is constructed so that each cylinder performs a series of four strokes consisting of an intake stroke, a compression stroke, an expansion stroke and an exhaust stroke.

An ISG (Integrated Starter Generator) 20 is connected to the engine 2 . The ISG 20 is connected to the crankshaft of the engine 2 via a power transmission member such as a belt (not shown). The ISG 20 is connected to the battery 8 and the second inverter 41 via the first inverter 21 .

The ISG 20 has a function of an electric motor that rotates when supplied with power from the battery 8 to rotate the engine 2, and a function of a generator that converts the rotational force input from the crankshaft by driving the engine 2 into electric power. and

The ISG 20 can supply the electric power generated by driving the engine 2 to the battery 8 or the second inverter 41 , or supply both the battery 8 and the second inverter 41 .

The transmission 3 is configured by an automatic transmission that shifts the rotation output from the engine 2 at a gear ratio corresponding to one of a plurality of gear stages and outputs the gear. As the automatic transmission, a multi-stage AT (Automatic Transmission) or CVT (Continuously Variable Transmission) can be used. Automatic transmissions include multi-stage ATs and CVTs, as well as AMTs (Automated Manual Transmissions) that automatically perform gear shifting operations and clutch operations. The transmission 3 drives the left and right front wheels 5 via drive shafts 31 .

Gear stages that can be established by the transmission 3 include, for example, first to fourth gear stages for traveling and reverse gear stages. The number of gear stages for running varies depending on the specifications of the four-wheel drive vehicle 1, and is not limited to the first to fourth gear stages described above.

The motor generator 4 is connected to the left and right rear wheels 6 via a drive shaft 61 . The motor generator 4 is connected to the second inverter 41 . A battery 8 is connected to the second inverter 41 . Battery 8 supplies power to motor generator 4 via second inverter 41 .

The motor generator 4 has a function as an electric motor that is driven by electric power supplied from the battery 8 and a function as a generator that generates power by reverse driving force input from the rear wheels 6 .

The battery 8 is composed of, for example, a secondary battery such as a lithium ion battery. The battery 8 is charged by the power generated by the ISG 20 and the motor generator 4, and is also charged by the external power supply 90 via the charger 9. As shown in FIG. Note that the four-wheel drive vehicle 1 may be configured so as not to be charged by the external power source 90 . In this case, the four-wheel drive vehicle 1 does not have the charger 9 .

The battery 8 is provided with a battery sensor 81 . The battery sensor 81 detects charge/discharge current and voltage of the battery 8 and outputs them to the VCM 13 . The VCM 13 calculates the state of charge of the battery 8, that is, SOC (State Of Charge), based on the detection result input from the battery sensor 81 . If the four-wheel drive vehicle 1 is provided with a BMS (Battery Management System) that manages the battery 8, the BMS may calculate the SOC and transmit the calculated SOC from the BMS to the VCM 13. .

Each of the ECM 11, TCM 12 and VCM 13 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory for storing backup data, an input port, and an output port. It is composed of a computer unit with

The ROMs of these computer units store programs for causing the computer units to function as the ECM 11, TCM 12 and VCM 13, along with various constants and various maps.

That is, these computer units function as the ECM 11, TCM 12, and VCM 13 in this embodiment, respectively, by the CPU executing the programs stored in the ROM using the RAM as a work area.

In this embodiment, the ECM 11 is connected to the VCM 13 and controls the engine 2 according to commands from the VCM 13 . A crank angle sensor 23 is connected to the ECM 11 . The ECM 11 calculates the engine speed based on detection information from the crank angle sensor 23 .

The TCM 12 is connected to the VCM 13 and controls the transmission 3 according to commands from the VCM 13 . A vehicle speed sensor 101 is connected to the TCM 12 . The TCM 12 transmits information indicating the vehicle speed input from the vehicle speed sensor 101 to the VCM 13 . A vehicle speed sensor 101 detects, for example, the rotation speed of the output shaft of the transmission 3 .

VCM 13 is connected to ECM 11 , TCM 12 and second inverter 41 . Various switches such as an EV mode switch 104 and a 4WD mode switch 105 are connected to the VCM 13 .

The EV mode switch 104 and the 4WD mode switch 105 are both push-button switches for switching the driving mode of the four-wheel drive vehicle 1, and are arranged at positions such as the steering wheel that are easy for the driver to operate. The EV mode switch 104 and the 4WD mode switch 105 are not limited to the push button type, and may be of other types such as a dial type.

As driving modes of the four-wheel drive vehicle 1, a normal mode, an EV mode, and a 4WD mode as a four-wheel drive mode are set. The normal mode is a running mode in which the four-wheel drive vehicle 1 runs with the driving force of at least one of the engine 2 and the motor generator 4 according to the running state. Therefore, in the normal mode, the two-wheel drive state using the driving force of the engine 2, the two-wheel drive state using the driving force of the motor generator 4, and the four-wheel drive state are changed according to the running state of the four-wheel drive vehicle 1. automatically switched.

Specifically, in the normal mode, if the four-wheel drive vehicle 1 is traveling on a rough road, for example, the four-wheel drive state is set, the four-wheel drive vehicle 1 is not traveling on a rough road, and the SOC of the battery 8 is a predetermined threshold value. If the above conditions are met, that is, if the state of charge of the battery 8 is good, the two-wheel drive state is established using the driving force of the motor generator 4 .

Whether or not the vehicle is traveling on a rough road is determined by the VCM 13, and the VCM 13 can determine that the vehicle is traveling on a rough road when, for example, slipping or spinning of the front wheels 5 and rear wheels 6 or vehicle body shaking is detected. Slipping or spinning of the front wheels 5 and rear wheels 6 can be detected based on detection results of wheel speed sensors 107 and 108, which will be described later. Further, the vehicle body shake can be detected based on the detection result of an acceleration sensor (not shown) or the like.

Furthermore, in the normal mode, if the four-wheel drive vehicle 1 is not traveling on rough roads and the SOC of the battery 8 is less than a predetermined threshold, that is, if the state of charge of the battery 8 is not good, the driving force of the engine 2 is used. It is assumed to be in a two-wheel drive state.

The EV mode is a running mode in which the vehicle runs only with the driving force of the motor generator 4 . In the EV mode, the four-wheel drive vehicle 1 is driven only by the driving force of the motor generator 4 and is in a two-wheel drive state. The 4WD mode is a driving mode in which the vehicle is driven by both the driving force of the engine 2 and the motor generator 4 . In the 4WD mode, the vehicle is in a four-wheel drive state in which both the engine 2 and the motor generator 4 are constantly driven.

The EV mode switch 104 is a switch for switching between a normal mode and an EV mode as the driving mode of the four-wheel drive vehicle 1. When turned on, the EV mode switch is switched to the EV mode, and when turned off, the switch is switched to the normal mode. The EV mode switch 104 of this embodiment constitutes a first switching unit.

The 4WD mode switch 105 is a switch for switching between a normal mode and a 4WD mode as the driving mode of the four-wheel drive vehicle 1. When turned on, the 4WD mode is selected, and when turned off, the normal mode is selected. The 4WD mode switch 105 of this embodiment constitutes a second switching unit.

The VCM 13 sets one of the normal mode, the EV mode, and the 4WD mode as the running mode based on the ON/OFF states of the EV mode switch 104 and the 4WD mode switch 105, respectively.

Various sensors such as an accelerator sensor 106 , wheel speed sensors 107 for the left and right front wheels 5 , and wheel speed sensors 108 for the left and right rear wheels 6 are connected to the VCM 13 .

The accelerator sensor 106 detects the amount of depression of an accelerator pedal (not shown) by the driver as an accelerator opening. A wheel speed sensor 107 and a wheel speed sensor 108 detect the rotational speeds of the left and right front wheels 5 and the left and right rear wheels 6, respectively.

The VCM 13 refers to a required power calculation map based on the accelerator opening detected by the accelerator sensor 106 and the vehicle speed detected by the vehicle speed sensor 101, and calculates the required power required for the four-wheel drive vehicle 1. It has become. The required power calculation map is a map in which the required power is associated with the accelerator opening and the vehicle speed, and is experimentally determined in advance and stored in the ROM of the VCM 13 . The required power coincides with the engine required power in the two-wheel drive state by the engine 2, and is the sum of the engine required power and the motor required power in the four-wheel drive state.

Next, referring to FIG. 2, the processing for determining the driving mode of the four-wheel drive vehicle 1 will be described. The processing shown in FIG. 2 is repeatedly executed by the VCM 13 at predetermined time intervals.

As shown in FIG. 2, the VCM 13 determines whether the EV mode switch 104 is ON (step S1). When the VCM 13 determines that the EV mode switch 104 is not ON, it determines whether the 4WD mode switch 105 is ON (step S7).

When the VCM 13 determines in step S7 that the EV mode switch 104 is ON, it sets the 4WD mode as the driving mode (step S8), and terminates this process. As a result, the four-wheel drive vehicle 1 runs with the driving force of both the engine 2 and the motor generator 4 .

When the VCM 13 determines in step S7 that the EV mode switch 104 is not ON, it sets the normal mode as the running mode (step S9), and terminates this process. As a result, the four-wheel drive vehicle 1 runs with the driving force of at least one of the engine 2 and the motor generator 4 according to the running state of the four-wheel drive vehicle 1 .

When the VCM 13 determines in step S1 that the EV mode switch 104 is ON, it determines whether the 4WD mode switch 105 is ON (step S2). When the VCM 13 determines in step S2 that the 4WD mode switch 105 is ON, it sets the normal mode as the driving mode (step S3), and terminates this process.

Thus, in this embodiment, when the EV mode is selected by turning on the EV mode switch 104 and the 4WD mode is selected by turning on the 4WD mode switch 105, the VCM 13 changes the running mode to the normal mode. set. As a result, the four-wheel drive vehicle 1 runs with the driving force of at least one of the engine 2 and the motor generator 4 according to the running state of the four-wheel drive vehicle 1 .

When the VCM 13 determines in step S2 that the 4WD mode switch 105 is not ON, it determines whether the four-wheel drive vehicle 1 is running in the four-wheel drive state (step S4). Specifically, the VCM 13 determines whether or not the four-wheel drive vehicle 1 is running in the four-wheel drive state in the normal mode.

When the VCM 13 determines in step S4 that the four-wheel drive vehicle 1 is running in the four-wheel drive state, the VCM 13 sets the normal mode as the running mode (step S5), and terminates this process.

As described above, in this embodiment, the VCM 13 changes the running state of the four-wheel drive vehicle 1 when the EV mode is selected by turning the EV mode switch 104 ON and the normal mode is selected by turning the 4WD mode switch 105 OFF. is in the four-wheel drive state, the driving mode is set to the normal mode. As a result, the four-wheel drive vehicle 1 is maintained in the normal mode, and in the four-wheel drive state in which both the engine 2 and the motor generator 4 are constantly driven.

When the VCM 13 determines in step S4 that the four-wheel drive vehicle 1 is not running in the four-wheel drive state, it sets the EV mode as the running mode (step S6), and terminates this process.

As described above, in this embodiment, the VCM 13 changes the running state of the four-wheel drive vehicle 1 when the EV mode is selected by turning the EV mode switch 104 ON and the normal mode is selected by turning the 4WD mode switch 105 OFF. is not in the four-wheel drive state, the driving mode is set to the EV mode.

That is, the VCM 13 sets or maintains the running mode to the EV mode, for example, when the four-wheel drive vehicle 1 is running in the two-wheel drive state in the normal mode or in the EV mode. As a result, the four-wheel drive vehicle 1 runs only with the driving force of the motor generator 4 .

Next, an example of operating the EV mode switch in the four-wheel drive vehicle 1 of this embodiment will be described with reference to FIG.

As shown in FIG. 3, in the four-wheel drive vehicle 1, the EV mode switch 104 and the 4WD mode switch 105 are both OFF at time t0, so the normal mode is set as the driving mode. Therefore, at time t0, the four-wheel drive vehicle 1 is not always in the four-wheel drive state (indicated as "always" in FIG. 3), but automatically switches between the two-wheel drive state and the four-wheel drive state according to the running state. is switched (indicated as "automatic" in FIG. 3). At time t0, the four-wheel drive vehicle 1 is traveling on a rough road, so the drive system is set to four-wheel drive in the normal mode, that is, the four-wheel drive vehicle is traveling in the four-wheel drive state.

After that, at time t1, the EV mode switch 104 is turned ON by the driver. This means that the driver requests the EV mode as the driving mode. However, at time t1, the four-wheel drive vehicle 1 is traveling on a rough road, and the behavior of the four-wheel drive vehicle 1 may become unstable if the mode is switched to the EV mode.

Therefore, in this embodiment, even if the driver turns on the EV mode switch 104 at time t1, the normal mode is maintained without switching to the EV mode because the four-wheel drive vehicle 1 is traveling on a rough road. . As a result, the four-wheel drive vehicle 1 is maintained in the four-wheel drive state.

After that, when the four-wheel drive vehicle 1 stops running on the rough road at time t2, the running mode of the four-wheel drive vehicle 1 is switched from the normal mode to the EV mode because the EV mode switch 104 is ON.

As a result, the drive system of the four-wheel drive vehicle 1 is automatically switched from four-wheel drive to two-wheel drive in the normal mode. The four-wheel drive vehicle 1 is in a two-wheel drive state in which it runs only with the driving force of the motor generator 4 .

As described above, the driving mode control apparatus for a four-wheel drive vehicle according to the present embodiment selects the driving mode when the EV mode is selected by the EV mode switch 104 and the 4WD mode is selected by the 4WD mode switch 105. to normal mode. For example, when the four-wheel drive vehicle 1 is running in four-wheel drive mode in the four-wheel drive mode, it is determined that the four-wheel drive vehicle 1 is running on a rough road that requires four-wheel drive in order to ensure the stability of the four-wheel drive vehicle 1. Even if the EV mode is selected by , priority is given to securing the stability of the behavior of the four-wheel drive vehicle 1, and the normal mode is set without setting the EV mode.

As described above, the driving mode control device for a four-wheel drive vehicle according to the present embodiment sets the normal mode when the EV mode and the 4WD mode are selected at the same time. The stability of behavior of the wheel drive vehicle 1 can be ensured.

Depending on the specifications of the four-wheel drive vehicle 1, switches for other functions may be arranged adjacent to the EV mode switch 104 in some cases. In such a case, the adjacent EV mode switch 104 may be erroneously operated when the driver tries to operate a switch for another function. If the EV mode switch 104 is erroneously operated, there is a risk that the four-wheel drive vehicle 1 will behave unintendedly by the driver. The running mode control device for a four-wheel drive vehicle according to the present embodiment sets the normal mode when the EV mode and the 4WD mode are selected at the same time as described above. Even if it is operated erroneously, it is possible to prevent the four-wheel drive vehicle 1 from behaving unintended by the driver.

Further, when the running state of the four-wheel drive vehicle 1 when the normal mode is selected is the four-wheel drive state, the running mode control device for the four-wheel drive vehicle according to the present embodiment controls the running mode during the normal mode. Even if the EV mode is selected by turning on the EV mode switch 104, the four-wheel drive state is maintained by maintaining the normal mode. As described above, the driving mode control apparatus for a four-wheel drive vehicle according to the present embodiment determines that there is a high possibility that the vehicle is traveling on a rough road during the four-wheel drive state in the normal mode. is selected, priority is given to ensuring the stability of the behavior of the four-wheel drive vehicle 1, and the normal mode is maintained without setting the EV mode. As a result, the running mode control device for a four-wheel drive vehicle according to this embodiment can ensure the stability of the behavior of the four-wheel drive vehicle 1 during four-wheel drive running.

Further, the running mode control device for a four-wheel drive vehicle according to the present embodiment is configured so that when the running state of the four-wheel drive vehicle 1 when the normal mode is selected is not a four-wheel drive state, such as a two-wheel drive state, , set the driving mode to the EV mode. As a result, the driving mode control apparatus for a four-wheel drive vehicle according to the present embodiment can set the EV mode to give priority to fuel efficiency when it is not necessary to prioritize ensuring the stability of the behavior of the four-wheel drive vehicle 1. can.

Although embodiments of the present invention have been disclosed, it will be apparent that modifications may be made by those skilled in the art without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

1 four-wheel drive vehicle 2 engine 3 transmission (automatic transmission)
4 Motor generator (motor)
5 front wheels 6 rear wheels 11 ECM
12 TCMs
13 VCM (control unit)
104 EV mode switch 105 4WD mode switch

Claims (4)

Driving mode of a four-wheel drive vehicle comprising an engine that drives one of front wheels and rear wheels, a motor that drives the other of the front wheels and rear wheels, and a battery that supplies power to the motor a controller,
As driving modes of the four-wheel drive vehicle, a normal mode in which the driving force of at least one of the engine and the motor is used according to the driving state of the four-wheel drive vehicle, and a driving mode in which both the engine and the motor are driven. having a four-wheel drive mode in which the vehicle runs by force and an EV mode in which the vehicle runs only by the driving force of the motor;
a first switching unit for switching between the normal mode and the EV mode;
a second switching unit for switching between the normal mode and the four-wheel drive mode;
a control unit that sets one of the normal mode, the EV mode, and the four-wheel drive mode based on the first switching unit and the second switching unit,
The control unit sets the driving mode to the normal mode when the EV mode is selected by the first switching unit and the four-wheel drive mode is selected by the second switching unit. A driving mode control device for a four-wheel drive vehicle, characterized by: Driving mode of a four-wheel drive vehicle comprising an engine that drives one of front wheels and rear wheels, a motor that drives the other of the front wheels and rear wheels, and a battery that supplies power to the motor a controller,
As driving modes of the four-wheel drive vehicle, a normal mode in which the driving force of at least one of the engine and the motor is used according to the driving state of the four-wheel drive vehicle, and a driving mode in which both the engine and the motor are driven. having a four-wheel drive mode in which the vehicle runs by force and an EV mode in which the vehicle runs only by the driving force of the motor;
a first switching unit that switches between the normal mode and the EV mode by a driver's operation ;
a second switching unit that switches between the normal mode and the four-wheel drive mode by a driver's operation ;
a control unit that sets one of the normal mode, the EV mode, and the four-wheel drive mode based on the first switching unit and the second switching unit,
The control unit sets the driving mode to the normal mode when the EV mode is selected by the first switching unit and the four-wheel drive mode is selected by the second switching unit. A driving mode control device for a four-wheel drive vehicle, characterized by: The controller controls the driving state of the four-wheel drive vehicle when the EV mode is selected by the first switching section and the normal mode is selected by the second switching section. 3. The running mode control device for a four-wheel drive vehicle according to claim 1, wherein the four-wheel drive running state is maintained when . The controller controls the driving state of the four-wheel drive vehicle when the EV mode is selected by the first switching section and the normal mode is selected by the second switching section. 4. The running mode control device for a four-wheel drive vehicle according to any one of claims 1 to 3, wherein the running mode is set to the EV mode if not.

Images