Vehicle control device

Abstract

To suppress noise at a rear seat when a passenger is detected in the rear seat of a vehicle.SOLUTION: A vehicle control device installed in a vehicle comprises: a first drive unit connected to a front wheel; a second drive unit connected to a rear wheel; a detection unit for detecting presence or absence of a passenger in the rear seat of the vehicle; a processor and a memory communicably connected to each other; and a control system for controlling the first and second drive units. The second drive unit includes a traction motor. When a passenger is detected in the rear seat, the control system reduces the amount of drive force assigned to the second drive unit, among the demand drive force based on the vehicle's driving state, compared to when no passenger is detected in the rear seat.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a vehicle control device provided in a vehicle.

Background Art

[0002] Vehicles equipped with a plurality of driving motors as power sources have been developed (see Patent Document 1). As such vehicles, vehicles equipped with a driving motor connected to the front wheels and a driving motor connected to the rear wheels, and vehicles in which one driving motor is connected to each wheel have been developed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In such vehicles, the generation of noise due to the driving motor driving the wheels becomes a problem. The vehicle of Patent Document 1 detects the position of a person existing around the vehicle. This vehicle controls the operations of the driving motor connected to the front wheels and the driving motor connected to the rear wheels based on the detected position of the person. Thereby, the vehicle of Patent Document 1 reduces noise according to the position of a person existing around the vehicle. However, the reduction of noise for the passengers existing inside the vehicle is not considered.

Means for Solving the Problems

[0005] A vehicle control device according to an embodiment is a vehicle control device provided in a vehicle, and includes a first drive unit connected to a front wheel, a second drive unit connected to a rear wheel, a detection unit that detects the presence or absence of an occupant in a rear seat of the vehicle, and a processor and a memory that are communicably connected to each other, and a control system that controls the first drive unit and the second drive unit. The second drive unit has a driving motor. When an occupant is detected in the rear seat, the control system reduces the driving force assigned to the second drive unit among the required driving forces based on the driving state of the vehicle compared to the case where no occupant is detected in the rear seat.

Advantages of the Invention

[0006] According to the present invention, when an occupant is detected in the rear seat of a vehicle, noise in the rear seat can be suppressed.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same or substantially the same configurations and elements are denoted by the same reference numerals, and repeated descriptions thereof are omitted.

[0009] [Vehicle Configuration] FIG. 1 is a diagram showing a configuration example of a vehicle 11 provided with a vehicle control device 10 according to an embodiment of the present invention. FIG. 2 is a block diagram schematically showing a main configuration of the vehicle 11 provided with the vehicle control device 10 according to the embodiment. As shown in FIGS. 1 and 2, the vehicle 11 includes a front drive unit 13, a rear drive unit 15, a control system 20, inverters 30 and 32, a battery pack 31, and a seating detection unit 28.

[0010] [Front Drive Unit 13] The front drive unit 13 is disposed, for example, in the vicinity of the axle 23 of the front wheels 12L and 12R under the bonnet of the vehicle 11. The front drive unit 13 is a first drive unit connected to the front wheels 12L and 12R via the axle 23. As shown in FIG. 2, the front drive unit 13 has a front motor 16, a front differential 17, and an inverter 30.

[0011] The front motor 16 is a traveling motor that drives the front wheels 12L and 12R via the axle 23. The stator 16s of the front motor 16 is connected to the inverter 30. The inverter 30 is connected to a battery pack 31 and a front motor control unit 40, which will be described later. The front motor control unit 40 controls the operation of the front motor 16 via the inverter 30. The front motor 16 rotates in response to the control by the front motor control unit 40 to generate a driving force.

[0012] The rotor 16r of the front motor 16 is connected to the drive gear 21. The drive gear 21 meshes with a driven gear 22 fixed to the front differential 17. The axle 23 extending from the front differential 17 is connected to the front wheels 12L, 12R. Thus, the front wheels 12L, 12R are driven by the driving force generated by the front motor 16.

[0013] Details of the inverter 30 will be described later.

[0014] [Rear drive unit 15] The rear drive unit 15 is disposed, for example, in the vicinity of the axles 26 of the rear wheels 14L, 14R on the lower side of the rear seat 29R of the vehicle 11. The rear drive unit 15 is a second drive unit connected to the rear wheels 14L, 14R via the axles 26. The rear drive unit 15 includes a rear motor 18, a rear differential 19, a transmission 27, and an inverter 32.

[0015] The rear motor 18 is a traveling motor that drives the rear wheels 14L, 14R via the axles 26. The stator 18s of the rear motor 18 is connected to the inverter 32. The inverter 32 is connected to a battery pack 31 and a rear motor control unit 41, which will be described later. The rear motor control unit 41 controls the operation of the rear motor 18 via the inverter 32. The rear motor 18 rotates according to the control by the rear motor control unit 41 and generates a driving force.

[0016] The transmission 27 is, for example, a stepped automatic transmission. The transmission 27 has, for example, two steps of gears with different gear ratios including a high gear and a low gear. The transmission 27 is electrically connected to the rear motor control unit 41. The rear motor control unit 41 controls the transmission 27 to set either the high gear or the low gear. Note that the transmission 27 may be configured to be able to set three or more gear ratios. Further, the transmission 27 is not limited to a stepped automatic transmission and may be a continuously variable transmission (CVT).

[0017] The input side of the transmission 27 is connected to the rotor 18r of the rear motor 18, and the output side is connected to the drive gear 24. The drive gear 24 meshes with a driven gear 25 fixed to the rear differential 19. The axle 26 extending from the rear differential 19 is connected to the rear wheels 14L, 14R. Accordingly, the rear wheels 14L, 14R are driven by the driving force generated by the rear motor 18.

[0018] Details of the inverter 32 will be described later.

[0019] [Battery pack 31] The battery pack 31 includes a battery module 33, a battery control unit 34, and a battery sensor 35. The battery module 33 has a plurality of battery cells. The battery sensor 35 detects the charge / discharge current, terminal voltage, etc. of the battery module 33. The battery control unit 34 monitors the charge / discharge of the battery module 33. The battery control unit 34 has a function of calculating the state of charge (SOC) of the battery module 33 based on the charge / discharge current, terminal voltage, etc. detected by the battery sensor 35. Note that the SOC of the battery module 33 is a ratio indicating the remaining amount of electricity stored in the battery module 33. That is, the SOC of the battery module 33 is the ratio of the stored power to the full charge capacity of the battery module 33.

[0020] [Inverter 30] The inverter 30 is composed of a plurality of switching elements and the like, and is connected to the front motor 16 and the front motor control unit 40 as described above. The inverter 30 is controlled by the front motor control unit 40 to convert the DC power of the battery module 33 into AC power and supply it to the front motor 16. The inverter 30 generates AC power by turning on / off a plurality of switching elements by a PWM signal.

[0021] The front motor control unit 40 generates the above PWM signal based on a voltage command value or a current command value and a carrier wave of a predetermined frequency. The front motor control unit 40 controls the inverter 30 to control the energization state of the stator 16s and thus control the motor torque of the front motor 16.

[0022] When controlling the front motor 16 to be in the power running state, the front motor control unit 40 controls the inverter 30 based on the PWM signal to supply power from the battery module 33 to the stator 16s via the inverter 30. On the other hand, when controlling the front motor 16 to be in the power generation state, the front motor control unit 40 causes the stator 16s to supply power to the battery module 33 via the inverter 30.

[0023] [Inverter 32] The inverter 32 is composed of a plurality of switching elements and the like, and is connected to the rear motor 18 and the rear motor control unit 41 as described above. The inverter 32 is controlled by the rear motor control unit 41 to convert the DC power of the battery module 33 into AC power and supply it to the rear motor 18. The inverter 32 generates AC power by turning on / off a plurality of switching elements by means of a PWM signal.

[0024] The rear motor control unit 41 generates the above PWM signal based on a voltage command value or a current command value and a carrier wave of a predetermined frequency. The rear motor control unit 41 controls the inverter 32 to control the energization state of the stator 18s and thus control the motor torque of the rear motor 18.

[0025] When controlling the rear motor 18 to the power running state, the rear motor control unit 41 controls the inverter 32 based on the PWM signal to supply power from the battery module 33 to the stator 18s via the inverter 32. On the other hand, when controlling the rear motor 18 to the power generation state, the rear motor control unit 41 causes the stator 18s to supply power to the battery module 33 via the inverter 32.

[0026] [Seat occupancy detection unit 28] The seat occupancy detection unit 28 is, for example, a seat occupancy sensor. The seat occupancy detection unit 28 is provided for each seat. The seat occupancy detection unit 28 detects the load or pressure acting on the lower surface (seating surface) of each seat, and outputs a seat occupancy signal when a load or pressure equal to or greater than a predetermined value acts. That is, the seat occupancy detection unit 28 detects that a driver or a passenger has seated on the seat by detecting that a load or pressure equal to or greater than a predetermined value has acted on the seat. Therefore, the seat occupancy detection unit 28 provided on the lower surface of the rear seat 29R functions as a detection unit for detecting the presence or absence of a passenger in the rear seat 29R.

[0027] Note that the seat occupancy detection unit 28 may be a seat belt reminder. In this case, when the seat belt is buckled in a state where it is detected by the seat occupancy sensor that a load or pressure equal to or greater than a predetermined value has acted on the seat, the seat occupancy detection unit 28 outputs a seat occupancy signal. Further, the seat occupancy detection unit 28 may include an imaging device capable of imaging the interior of the vehicle 11. In this case, the seat occupancy detection unit 28 analyzes the image generated by the imaging device and outputs a seat occupancy signal when it detects that a passenger is seated on the seat.

[0028] [Control system 20] The vehicle control device 10 includes a control system 20 composed of a plurality of electronic control units in order to control the front drive unit 13, the rear drive unit 15, etc. The electronic control units constituting the control system 20 include a battery control unit 34, a front motor control unit 40, a rear motor control unit 41, and a vehicle control unit 52.

[0029] The vehicle control unit 52 outputs control signals to the control units 34, 40, and 41. These control units 34, 40, 41, and 52 are communicably connected to each other via an in-vehicle network 53 such as CAN or LIN. The vehicle control unit 52 sets operation targets for the front motor 16, rear motor 18, etc. based on input information from various control units 34, 40, 41 and various sensors described later. Then, the vehicle control unit 52 generates control signals corresponding to the operation targets of the front motor 16, rear motor 18, etc., and outputs these control signals to the various control units 34, 40, 41.

[0030] Sensors connected to the vehicle control unit 52 include an accelerator position sensor that detects the depression of the accelerator pedal, i.e., the operation position of the accelerator pedal, a wheel speed sensor, etc. Also, the vehicle control unit 52 is connected to the above-described seating detection unit 28 and a start switch 68. The start switch 68 is a switch that receives an operation by the driver when starting or ending the control system 20.

[0031] FIG. 3 is a diagram briefly showing the basic structure of each control unit 34, 40, 41, and 52. As shown in FIG. 3, each control unit 34, 40, 41, and 52 has a microcontroller 72 in which a processor 70, a memory 71, etc. are incorporated. A predetermined program is stored in the memory 71, and the instruction set of the program is executed by the processor 70. The processor 70 and the memory 71 are communicably connected to each other. In the example shown in the figure, one processor 70 and one memory 71 are incorporated in the microcontroller 72, but it is not limited to this, and a plurality of processors 70 may be incorporated in the microcontroller 72, or a plurality of memories 71 may be incorporated in the microcontroller 72.

[0032] In addition, each of the control units 34, 40, 41, and 52 is provided with an input conversion circuit 73, a drive circuit 74, a communication circuit 75, an external memory 76, a power supply circuit 77, and the like. The input conversion circuit 73 converts a signal input from various sensors into a signal that can be input to the microcontroller 72. The drive circuit 74 generates a drive signal for actuators such as the front motor 16 and the rear motor 18 described above based on a signal output from the microcontroller 72. The communication circuit 75 converts a signal output from the microcontroller 72 into a communication signal directed to another control unit. Also, the communication circuit 75 converts a communication signal received from another control unit into a signal that can be input to the microcontroller 72. Further, the power supply circuit 77 supplies a stable power supply voltage to the microcontroller 72, the input conversion circuit 73, the drive circuit 74, the communication circuit 75, the external memory 76, and the like. The external memory 76 such as a non-volatile memory stores data and the like that should be retained even when not powered on.

[0033] [Required driving force] FIG. 4 is a diagram showing an example of a driving force map indicating the required driving force. The required driving force is a value determined based on the running state of the vehicle 11. The running state includes, for example, the vehicle speed and the accelerator position. As shown in FIG. 4, in the driving force map, with the accelerator position being 100% at the maximum and 0% at the minimum, characteristic lines L1 to L4 indicating the required driving force are set for each accelerator position Acp. The driving force map shows that when the accelerator position Acp is 0%, the required driving force for the vehicle 11 is determined along the characteristic line L1. Also, the driving force map shows that when the accelerator position Acp is 25%, the required driving force for the vehicle 11 is determined along the characteristic line L2. Also, the driving force map shows that when the accelerator position Acp is 50%, the required driving force for the vehicle 11 is determined along the characteristic line L3. Also, the driving force map shows that when the accelerator position Acp is 100%, the required driving force for the vehicle 11 is determined along the characteristic line L4.

[0034] For example, when the vehicle speed is "0" at a stop and the accelerator pedal is depressed so that the accelerator position Acp is "25%", the required driving force is determined as "Fa" shown in FIG. 4. Also, when the vehicle is stopped and the accelerator pedal is depressed so that the accelerator position Acp is "50%", the required driving force is determined as "Fb" shown in FIG. 4. The vehicle control unit 52 sets the target torque of the front motor 16 and the target torque of the rear motor 18 so that the required driving forces "Fa" and "Fb" can be obtained.

[0035] Note that in the driving force map shown in FIG. 4, four characteristic lines L1 to L4 are set from the viewpoint of facilitating explanation, but it is needless to say that it is not limited to this, and a driving force map with five or more characteristic lines may be used.

[0036] [Noise Reduction Control] The vehicle control unit 52 performs noise reduction control to reduce the influence of noise on the passengers in the vehicle 11. When no passenger is detected in the rear seat 29R of the vehicle 11, the vehicle control unit 52 performs control to keep the noise level associated with the driving of the front drive unit 13 low. Also, when a passenger is detected in the rear seat 29R of the vehicle 11, the vehicle control unit 52 performs control to keep the noise level associated with the driving of the rear drive unit 15 low. For this purpose, the vehicle control unit 52 performs torque distribution control to the front motor 16 and the rear motor 18 with respect to the required driving force, control of the transmission 27 provided in the rear drive unit 15, and switching frequency control of the inverter 32. Each control will be described below.

[0037] [Torque Distribution Control] The vehicle control unit 52 varies the distribution of the required driving force to the front wheels 12L, 12R and the distribution of the driving force to the rear wheels 14L, 14R according to the presence or absence of a passenger in the rear seat 29R.

[0038] FIG. 5 schematically shows an example of the distribution of the required driving force when no occupant is detected in the rear seat 29R and an example of the distribution of the required driving force when an occupant is detected in the rear seat 29R. In FIG. 5, the horizontal axis indicates the ratio of the driving force distribution to the front wheels 12L, 12R and the driving force distribution to the rear wheels 14L, 14R with respect to the total required driving force for the front wheels 12L, 12R and the rear wheels 14L, 14R. With reference to FIG. 5, the distribution of the required driving force performed by the vehicle control unit 52 will be described.

[0039] When no occupant is detected in the rear seat 29R, the vehicle control unit 52 distributes, for example, 30% of the total required driving force R0 such as Fa or Fb shown in FIG. 4 as the driving force R1 for the front wheels 12L, 12R, and distributes, for example, 70% as the driving force R2 for the rear wheels 14L, 14R. Then, the vehicle control unit 52 sets the target torque of the front motor 16 so that the driving force R1 is obtained, and sets the target torque of the rear motor 18 so that the driving force R2 is obtained. In the following description, the target torque of the front motor 16 set so that the driving force R1 is obtained is referred to as the first target torque. Also, the target torque of the rear motor 18 set so that the driving force R2 is obtained is referred to as the second target torque.

[0040] Since the driving force R1 is a smaller value than the driving force R2, when no occupant is detected in the rear seat 29R, the first target torque is smaller than the second target torque. Note that the ratio of the distribution of the driving force R1 and the driving force R2 with respect to the total required driving force R0 is an example and is not limited to the above ratio.

[0041] When an occupant is detected in the rear seat 29R, the vehicle control unit 52 sets the distribution of the driving force to the rear wheels 14L and 14R to be smaller than the ratio of the distribution of the driving force R2 to the total required driving force R0 when no occupant is detected in the rear seat 29R. That is, when an occupant is detected in the rear seat 29R, the vehicle control unit 52 reduces the driving force allocated to the rear drive unit 15 having the rear motor 18 out of the total required driving force R0 compared to the case where no occupant is detected in the rear seat 29R. For example, the vehicle control unit 52 distributes, for example, 70% of the total required driving force R0 as the driving force R3 to the front wheels 12L and 12R, and distributes, for example, 30% as the driving force R4 to the rear wheels 14L and 14R.

[0042] Then, the vehicle control unit 52 sets the target torque of the front motor 16 so that the driving force R3 is obtained, and sets the target torque of the rear motor 18 so that the driving force R4 is obtained. In the following description, the target torque of the front motor 16 set so that the driving force R3 is obtained is referred to as the third target torque. Also, the target torque of the rear motor 18 set so that the driving force R4 is obtained is referred to as the fourth target torque.

[0043] Since the driving force R4 is a smaller value than the driving force R3, when an occupant is detected in the rear seat 29R, the fourth target torque becomes smaller than the third target torque. Note that the ratio of the distribution of the driving force R3 and the driving force R4 to the total required driving force R0 is an example and is not limited to the above ratio.

[0044] As shown in FIG. 5, the ratio of the distribution of the driving force R1 to the total required driving force R0 when no occupant is detected in the rear seat 29R is smaller than the ratio of the distribution of the driving force R3 to the total required driving force R0 when an occupant is detected in the rear seat 29R. For this reason, the vehicle control unit 52 sets the first target torque of the front motor 16 to a value smaller than the third target torque.

[0045] Further, the ratio of the distribution of the driving force R4 to the total required driving force R0 when an occupant is detected in the rear seat 29R is smaller than the ratio of the distribution of the driving force R2 to the total required driving force R0 when no occupant is detected in the rear seat 29R. For this reason, the vehicle control unit 52 sets the fourth target torque of the rear motor 18 to a value smaller than the second target torque.

[0046] Specifically, the memory 71 or the external memory 76 of the vehicle control unit 52 stores a first driving force map, a second driving force map, a third driving force map, and a fourth driving force map. The first driving force map is a driving force map as shown in FIG. 4 showing the required driving force of the front wheels 12L and 12R when no occupant is detected in the rear seat 29R. The second driving force map is a driving force map as shown in FIG. 4 showing the required driving force of the rear wheels 14L and 14R when no occupant is detected in the rear seat 29R. The third driving force map is a driving force map as shown in FIG. 4 showing the required driving force of the front wheels 12L and 12R when an occupant is detected in the rear seat 29R. The fourth driving force map is a driving force map as shown in FIG. 4 showing the required driving force of the rear wheels 14L and 14R when an occupant is detected in the rear seat 29R.

[0047] [When no occupant is detected in the rear seat 29R] When the vehicle control unit 52 does not receive a seating signal from the seating detection unit 28 provided in the rear seat 29R, the vehicle control unit 52 sets the first target torque of the front motor 16 based on the driving force R1 calculated by referring to the first driving force map. Further, when the vehicle control unit 52 does not receive a seating signal from the seating detection unit 28 provided in the rear seat 29R, the vehicle control unit 52 sets the second target torque of the rear motor 18 based on the driving force R2 calculated by referring to the second driving force map.

[0048] The vehicle control unit 52 commands the front motor control unit 40 to operate the front motor 16 at the first target torque. In this case, the front motor control unit 40 reduces the level of the voltage command value or current command value for generating the PWM signal for the inverter 30. Also, the vehicle control unit 52 commands the rear motor control unit 41 to operate the rear motor 18 at the second target torque. In this case, the rear motor control unit 41 increases the level of the voltage command value or current command value for generating the PWM signal for the inverter 32.

[0049] Since the first target torque is a value smaller than the second target torque, the noise caused by the rotation of the front motor 16 is reduced. As described above, the front drive unit 13 having the front motor 16 is disposed near the axle 23 of the front wheels 12L and 12R under the bonnet of the vehicle 11. That is, the front motor 16 is disposed near the front seat 29F. Therefore, by reducing the noise caused by the rotation of the front motor 16, the noise for the driver and passengers in the front seat 29F is reduced.

[0050] [When a passenger is detected in the rear seat 29R] When the vehicle control unit 52 inputs a seating signal from the seating detection unit 28 provided in the rear seat 29R, the vehicle control unit 52 sets the third target torque of the front motor 16 based on the driving force R3 calculated by referring to the third driving force map. Also, when the vehicle control unit 52 inputs a seating signal from the seating detection unit 28 provided in the rear seat 29R, the vehicle control unit 52 sets the fourth target torque of the rear motor 18 based on the driving force R4 calculated by referring to the fourth driving force map.

[0051] The vehicle control unit 52 commands the front motor control unit 40 to operate the front motor 16 at the third target torque. In this case, the front motor control unit 40 increases the level of the voltage command value or current command value for generating the PWM signal for the inverter 30. Also, the vehicle control unit 52 commands the rear motor control unit 41 to operate the rear motor 18 at the fourth target torque. In this case, the rear motor control unit 41 decreases the level of the voltage command value or current command value for generating the PWM signal for the inverter 32.

[0052] Since the fourth target torque is a value smaller than the third target torque, the noise caused by the rotation of the rear motor 18 is reduced. As described above, the rear drive unit 15 having the rear motor 18 is disposed below the rear seat 29R of the vehicle 11. Therefore, by reducing the noise caused by the rotation of the rear motor 18, the noise for the passengers in the rear seat 29R is reduced.

[0053] [Transmission control] The vehicle control unit 52 changes the gear ratio of the transmission 27 according to the presence or absence of a passenger in the rear seat 29R. Specifically, when no seating signal is output from the seating detection unit 28, the vehicle control unit 52 commands the rear motor control unit 41 to set the gear ratio of the transmission 27 to be small. That is, the rear motor control unit 41 sets the transmission 27 to the high gear. Thereby, the rotational speed of the rear motor 18 becomes the first rotational speed.

[0054] Also, when a seating signal is output from the seating detection unit 28, the vehicle control unit 52 commands the rear motor control unit 41 to set the gear ratio of the transmission 27 to be large. That is, the rear motor control unit 41 sets the transmission 27 to the low gear. Thereby, the rotational speed of the rear motor 18 becomes the second rotational speed higher than the first rotational speed. That is, when there is a passenger in the rear seat 29R, the rotational speed of the rear motor 18 increases compared to the case where there is no passenger in the rear seat 29R.

[0055] FIG. 6 is a graph showing the relationship between vehicle speed and torque when the gear ratio of transmission 27 is changed, and the relationship between vehicle speed and the rotational speed of rear motor 18. In FIG. 6, the torque at the high gear with a small gear ratio of transmission 27 is indicated by solid line P1, and the torque at the low gear with a large gear ratio of transmission 27 is indicated by broken line P2. Also, the first rotational speed of rear motor 18 is indicated by one-dot chain line P3, and the second rotational speed is indicated by two-dot chain line P4. Further, the left vertical axis in FIG. 6 indicates torque, the right vertical axis indicates the rotational speed of rear motor 18, and the horizontal axis indicates vehicle speed.

[0056] As shown in FIG. 6, when transmission 27 is changed to the low gear, the torque decreases compared to the case of the high gear. For this reason, the generation of noise caused by the drive of the gear is suppressed. As a result, the noise in the rear seat 29R near the rear drive unit 15 having transmission 27 can be suppressed. Also, when transmission 27 is changed to the low gear, the rotational speed of rear motor 18 increases compared to when transmission 27 is in the high gear. For this reason, even when the torque decreases, the decrease in the driving force of rear wheels 14L, 14R is suppressed.

[0057] [Switching Frequency Control] Vehicle control unit 52 sets the carrier frequency of inverter 32 provided in rear motor 18 to different values according to the presence or absence of an occupant in rear seat 29R. The carrier frequency in the generation of the PMW signal is often set to a frequency in the audible range that can be heard by humans. The carrier frequency in the audible range is, for example, 20 Hz to 20 kHz. When no seating signal is output from seating detection unit 28 of rear seat 29R and no occupant is detected in rear seat 29R, vehicle control unit 52 sets the carrier frequency to the frequency in the above audible range. Rear motor control unit 41 generates a PMW signal based on this carrier frequency and operates inverter 32.

[0058] On the other hand, when a seating signal is output from the seating detection unit 28 of the rear seat 29R and a passenger is detected in the rear seat 29R, the vehicle control unit 52 sets the carrier frequency to a frequency higher than the frequency in the audible range. That is, when a passenger is detected in the rear seat 29R, the vehicle control unit 52 sets the switching frequency of the inverter 32 to a higher frequency than when no passenger is detected in the rear seat 29R. The rear motor control unit 41 generates a PWM signal based on this carrier frequency and operates the inverter 32. When the carrier frequency becomes higher than the frequency in the audible range, the carrier noise caused by the carrier wave occurs in a frequency range higher than the audible range. For this reason, the noise due to the carrier noise is less likely to be heard by the passenger in the rear seat 29R near the inverter 32. As a result, the noise in the rear seat 29R can be suppressed.

[0059] [Explanation of flowchart] FIG. 7 is a flowchart for explaining the noise reduction control performed by the vehicle control unit 52. When the start switch 68 receives an ON operation by the driver, the vehicle control unit 52 reads out the program recorded in the memory 71. Then, by executing the read program, the vehicle control unit 52 performs each process shown in the flowchart of FIG. 7.

[0060] In step S1, the vehicle control unit 52 determines the presence or absence of a passenger in the rear seat 29R. When a seating signal is output from the seating detection unit 28 of the rear seat 29R, the vehicle control unit 52 determines that a passenger is detected in the rear seat 29R and makes an affirmative determination. Thereafter, the process proceeds to step S2. When a seating signal is not output from the seating detection unit 28 of the rear seat 29R, the vehicle control unit 52 determines that no passenger is detected in the rear seat 29R and makes a negative determination. Thereafter, the process proceeds to step S5.

[0061] In step S2, the vehicle control unit 52 sets the third target torque of the front motor 16 based on the third driving force map, and sets the fourth target torque of the rear motor 18 based on the fourth driving force map. Then the process proceeds to step S3. In step S3, the vehicle control unit 52 sets the transmission 27 provided in the rear drive unit 15 to a low gear so that it has a large gear ratio. At this time, the rotational speed of the rear motor 18 becomes a second rotational speed that is higher than the first rotational speed. Then, the process proceeds to step S4. In step S4, the vehicle control unit 52 sets the carrier frequency of the inverter 32 to a frequency higher than the audible range. Then, the process proceeds to step S8 described later.

[0062] In step S5, the vehicle control unit 52 sets the first target torque of the front motor 16 based on the first driving force map, and sets the second target torque of the rear motor 18 based on the second driving force map. Then, the process proceeds to step S6. In step S6, the vehicle control unit 52 sets the transmission 27 provided in the rear drive unit 15 to a high gear so that it has a small gear ratio. At this time, the rotational speed of the rear motor 18 becomes a first rotational speed that is lower than the second rotational speed. Then, the process proceeds to step S7. In step S7, the vehicle control unit 52 sets the carrier frequency of the inverter 32 to a frequency within the audible range. Then, the process proceeds to step S8.

[0063] In step S8, the vehicle control unit 52 determines whether the start switch 68 has received an off operation from the driver. If the start switch 68 has not received an off operation, the vehicle control unit 52 makes a negative determination. Then, the process returns to step S1. If the start switch 68 has received an off operation, the vehicle control unit 52 makes an affirmative determination. Then, the process of the noise reduction control ends.

[0064] Further, in the above description, the vehicle control unit 52 performed torque distribution control, transmission control, and switching frequency control as noise reduction processes, but it is not necessary to perform all of the controls. For example, the vehicle control unit 52 may not perform switching frequency control. In this case, the vehicle control unit 52 does not have to perform the processes of steps S4 and S7 shown in FIG. 7.

[0065] According to the embodiment described above, at least one of the following operational effects can be obtained. (1) When a passenger is detected in the rear seat 29R, the vehicle control unit 52 of the control system 20 reduces the driving force assigned to the rear drive unit 15 among the total required driving force R0 compared to when no passenger is detected in the rear seat 29R. Thereby, the generation of noise due to the driving of the rear drive unit 15 is suppressed. As a result, the noise for the passenger in the rear seat 29R arranged in the vicinity of the rear drive unit 15 can be reduced.

[0066] (2) When a passenger is detected in the rear seat 29R by the seating detection unit 28, the vehicle control unit 52 of the control system 20 sets the target torque of the rear motor 18 to a smaller value compared to when no passenger is detected in the rear seat 29R. As a result, the noise due to the rotation of the rear motor 18 is reduced, making it possible to reduce the noise for the passenger in the rear seat 29R.

[0067] (3) When a passenger is detected in the rear seat 29R by the seating detection unit 28, the vehicle control unit 52 of the control system 20 sets a larger gear ratio of the transmission 27 compared to when no passenger is detected in the rear seat 29R. Thereby, the torque is reduced, and the generation of noise caused by the driving of the gears of the transmission 27 is suppressed. As a result, the noise in the rear seat 29R located in the vicinity of the transmission 27 can be suppressed.

[0068] (4) When an occupant is detected in the rear seat 29R by the seating detection unit 28, the vehicle control unit 52 of the control system 20 sets the switching frequency of the inverter 32 to a higher frequency than when no occupant is detected in the rear seat 29R. Specifically, the vehicle control unit 52 sets the switching frequency of the inverter 32 to a frequency higher than the audible range. As a result, since the carrier noise generated due to the carrier wave occurs in a frequency range higher than the audible range, the noise caused by the carrier noise is less likely to be heard by the occupant in the rear seat 29R near the inverter 32. As a result, the noise in the rear seat 29R can be suppressed.

[0069] [Modification Example 1] The front drive unit 13 of the vehicle 11 in the above-described embodiment has been described as having the front motor 16. However, the present invention is not limited to this example, and the front drive unit 13 of the vehicle 11 may have an engine instead of the front motor 16. Also in this case, when no occupant is detected in the rear seat 29R by the seating detection unit 28, the vehicle control unit 52 sets the first target torque of the engine and the second target torque of the rear motor 18 in the same manner as in the embodiment. Further, when an occupant is detected in the rear seat 29R by the seating detection unit 28, the vehicle control unit 52 sets the third target torque of the engine and the fourth target torque of the rear motor 18. Thereby, similar to the case of the embodiment, when an occupant in the rear seat 29R is detected, the noise in the rear seat 29R can be reduced.

[0070] [Modification Example 2] Instead of changing the target torque of the front motor 16 and the target torque of the rear motor 18 according to the presence or absence of an occupant in the rear seat 29R, the vehicle control unit 52 may cut off the driving force by the front motor 16 or the rear motor 18. In this case, the front drive unit 13 has a disconnect mechanism including a clutch or the like that disconnects the connection between the front motor 16 and the front wheels 12L, 12R. Further, the rear drive unit 15 has a disconnect mechanism including a clutch or the like that disconnects the connection between the rear motor 18 and the rear wheels 14L, 14R.

[0071] When no occupant is detected in the rear seat 29R, the vehicle control unit 52 shuts off the front wheels 12L and 12R from the front motor 16 by means of the disconnect mechanism of the front drive unit 13. Since the front motor 16 is disconnected from the front wheels 12L and 12R, the rotation of the front motor 16 can be stopped. As a result, when no occupant is detected in the rear seat 29R, the noise near the front seat 29F can be reduced.

[0072] In addition, even when the front drive unit 13 has an engine instead of the front motor 16 as in the first modification, the vehicle control unit 52 can disconnect the connection between the engine and the front wheels 12L and 12R by means of the disconnect mechanism. Also in this case, when no occupant is detected in the rear seat 29R, the noise near the front seat 29F can be reduced.

[0073] When an occupant is detected in the rear seat 29R, the vehicle control unit 52 shuts off the rear wheels 14L and 14R from the rear motor 18 by means of the disconnect mechanism of the rear drive unit 15. Since the rear motor 18 is disconnected from the rear wheels 14L and 14R, the rotation of the rear motor 18 can be stopped. That is, when an occupant is detected in the rear seat 29R, the vehicle control unit 52 reduces the driving force assigned to the rear drive unit 15 out of the total required driving force R0 as compared with the case where no occupant is detected in the rear seat 29R. As a result, when an occupant is detected in the rear seat 29R, the noise near the rear seat 29R can be reduced.

Explanation of Reference Numerals

[0074] 10 Vehicle control device, 11 Vehicle, 12L, 12R Front wheels, 13 Front drive unit, 14L, 14R Rear wheels, 15 Rear drive unit, 16 Front motor, 18 Rear motor, 20 Control system, 27 Transmission, 28 Occupancy detection unit, 29R Rear seat, 30, 32 Inverter, 40 Front motor control unit, 41 Rear motor control unit, 52 Vehicle control unit, 70 Processor, 71 Memory

Claims

1. A vehicle control device provided in a vehicle, a first drive unit connected to the front wheels, a second drive unit connected to the rear wheels, a detection unit that detects the presence or absence of an occupant in the rear seat of the vehicle, a control system including a processor and a memory connected to be communicable with each other, and controlling the first drive unit and the second drive unit, comprising, When an occupant is detected in the rear seat, the control system reduces the driving force assigned to the second drive unit among the required driving forces based on the driving state of the vehicle compared to when no occupant is detected in the rear seat. A vehicle control device.

2. In the vehicle control device according to claim 1, the second drive unit has a driving motor, When an occupant is detected in the rear seat, the control system sets the torque of the driving motor to a smaller value than when no occupant is detected in the rear seat. A vehicle control device.

3. In the vehicle control device according to claim 2, the second drive unit has a transmission, When an occupant is detected in the rear seat, the control system sets the gear ratio of the transmission to a larger value than when no occupant is detected in the rear seat. A vehicle control device.

4. In the vehicle control device according to claim 3, the second drive unit has an inverter, When an occupant is detected in the rear seat, the control system sets the switching frequency of the inverter to a higher frequency than when no occupant is detected in the rear seat. A vehicle control device.

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