Electric vehicle

Abstract

The invention relates to an electric vehicle. An electric vehicle is provided with: a drive device having a motor for travel and an electricity storage device that exchanges electric power with the motor; and a control device that controls the drive device so as to switch between the manual driving mode and the automatic driving mode to travel, and cuts the creep torque when a creep cut-off condition is satisfied when the creep torque is output from the motor. The control device mitigates the creep cutoff condition during the automatic driving mode than during the manual driving mode.

Description

Technical Field

[0001] The present disclosure relates to electric vehicles. Background Art

[0002] In the past, as such an electric vehicle, the following electric vehicle has been proposed: in an electric vehicle having a motor for running and a power storage device for exchanging electric power with the motor, the vehicle can run at a slow speed by using the creep torque from the motor, and during a period in which creep cut-off conditions such as the absolute value of the vehicle speed being less than a parking determination speed and the braking force being greater than a set braking force are satisfied, creep cut-off for reducing the creep torque of the electric motor can be performed (for example, refer to Japanese Patent Application Laid-Open No. 2012-016168).

[0003] In such an electric vehicle, if the response to the driver's acceleration request is prioritized in the automatic driving mode using the same creep cut conditions as in the manual driving mode, power consumption may not be sufficiently suppressed. Therefore, the improvement of power economy may not be fully achieved. Summary of the invention

[0004] The main purpose of the electric vehicle disclosed in the present invention is to achieve improved power economy in the autonomous driving mode.

[0005] The electric vehicle of the present disclosure employs the following means to achieve the above-mentioned main object.

[0006] The electric vehicle of the present disclosure comprises:

[0007] a drive device including a motor for traveling and a power storage device for exchanging electric power with the motor; and

[0008] A control device, wherein the control device controls the drive device so as to switch between a manual driving mode and an automatic driving mode for driving, and if a creep cut-off condition is satisfied when a creep torque is output from the motor, the creep torque is cut off, and in the automatic driving mode, the creep cut-off condition is relaxed compared to the manual driving mode.

[0009] In the electric vehicle disclosed herein, the drive device is controlled so as to switch between the manual driving mode and the automatic driving mode for driving. Furthermore, if the creep cut-off condition is satisfied when the creep torque is output from the motor, the creep torque is cut off. In this case, in the automatic driving mode, the creep cut-off condition is relaxed compared to the manual driving mode. Thus, in the automatic driving mode, it is easier to cut off the creep torque than in the manual driving mode, so that the power consumption of the vehicle can be suppressed and the power economy can be improved. Of course, in the manual driving mode, the response to the driver's acceleration request can be prioritized.

[0010] In the electric vehicle disclosed herein, it may be that, in the manual driving mode, the creep cut-off condition is a condition that the vehicle speed is below a first vehicle speed and the brake is on, and in the automatic driving mode, the creep cut-off condition is a condition that the vehicle speed is below a second vehicle speed, and the second vehicle speed is a vehicle speed above the first vehicle speed.

[0011] In the electric vehicle of the present disclosure, the control device may control the motor in the automatic driving mode so that the vehicle speed becomes a target vehicle speed based on the current location of the vehicle.

[0012] In the manual driving mode, the creep cut-off condition is a condition that the vehicle speed is below a first vehicle speed and the brake is on. In the automatic driving mode, the creep cut-off condition is a condition that the target vehicle speed is below a second vehicle speed, and the second vehicle speed is a vehicle speed above the first vehicle speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like parts, and in which:

[0014] Figure 1 1 is a schematic structural diagram showing the structure of a battery-powered vehicle 20 .

[0015] Figure 2 This is a flowchart showing an example of a processing routine.

[0016] Figure 3 This is a flowchart showing an example of a processing routine. DETAILED DESCRIPTION

[0017] Embodiments of the present disclosure will be described with reference to the drawings. Figure 1 1 is a schematic structural diagram showing the structure of a battery electric vehicle 20 as an embodiment of the present disclosure. As shown in the figure, the battery electric vehicle 20 of the embodiment includes a drive device 22, a braking device 24, a steering device 26, an air conditioning device 29, and a main electronic control unit (hereinafter referred to as "main ECU") 30.

[0018] The drive device 22 is configured to drive the drive shaft 22a connected to the drive wheels 28a and 28b via the differential gear 27, and includes a motor 22m, an inverter 22i, and a battery 22b. The motor 22m is configured as a synchronous generator motor, for example, and the rotor of the motor 22m is connected to the drive shaft 22a. The inverter 22i has a plurality of switching elements and is connected to the power line together with the battery 22b. The motor 22m is driven to rotate by switching the plurality of switching elements of the inverter 22i.

[0019] The drive device 22 is controlled by a drive electronic control unit (hereinafter referred to as "drive ECU") 23. Although not shown in the figure, the drive ECU 23 has a microcomputer with a CPU, ROM, RAM, flash memory, input and output ports, and a communication port. Signals from various sensors are input to the drive ECU 23 via the input port. For example, the rotation position θm from the rotation position sensor that detects the rotation position of the rotor of the motor 22m, the voltage Vb and the current Ib from the voltage sensor and the current sensor installed on the battery 22b are input to the drive ECU 23. The drive ECU 23, for example, performs switching control of multiple switching elements of the inverter 22i. The drive ECU 23 calculates the rotation speed Nm of the motor 22m (the rotation speed of the drive shaft 22a) based on the rotation position θa of the rotor of the motor 22m from the rotation position sensor. In addition, the drive ECU 23 communicates with the main ECU 30 via the communication port.

[0020] The brake device 24 is configured as a known brake device driven by hydraulic pressure. The brake device 24 is configured to be able to apply the braking force caused by the brake pedal force generated by stepping on the brake pedal 48 and the braking force caused by hydraulic pressure adjustment to the driving wheels 28a, 28b, and the driven wheels 28c, 28d. The brake device 24 is controlled by a brake electronic control unit (hereinafter referred to as "brake ECU") 25. Although not shown in the figure, the brake ECU 25 has a microcomputer with a CPU, ROM, RAM, flash memory, input and output ports, and a communication port. The brake ECU 25 controls, for example, the braking force caused by the brake pedal force based on the brake device 24 and the braking force caused by hydraulic pressure adjustment. In addition, the brake ECU 25 communicates with the main ECU 30 via the communication port.

[0021] In the steering device 26, a steering wheel (not shown) and driving wheels 28a, 28b are mechanically connected via a steering shaft, and an actuator for steering is provided. The steering device 26 steers the driving wheels 28a, 28b based on the driver's operation, and drives the actuator based on a steering signal from the main ECU 30, thereby steering the driving wheels 28a, 28b.

[0022] The air-conditioning device 29 includes a refrigeration cycle and a blower fan, and performs air conditioning in the vehicle cabin.

[0023] The main ECU 30 includes a microcomputer having a CPU 31, a ROM 32, a RAM 33, a flash memory 34, an input / output port and a communication port (not shown). Signals from various sensors are input to the main ECU 30 via the input port. For example, an air conditioning instruction signal from an air conditioning switch 29a that instructs the air conditioning device 29 to be turned on or off is input to the main ECU 30. The main ECU 30 is input with an ignition signal IG from an ignition switch 40, a vehicle speed V from a vehicle speed sensor 41, wheel speeds Vwa to Vwd of the driving wheels 28a, 28b and the driven wheels 28c, 28d from a wheel speed sensor 42, an acceleration α from an acceleration sensor 43, a yaw rate Yr from a yaw rate sensor 44, and a road surface gradient θr from a gradient sensor 45. The main ECU 30 is also input with an accelerator position AP from an accelerator pedal position sensor 47 that detects the amount of depression of an accelerator pedal 46, and a brake position BP from a brake pedal position sensor 49 that detects the amount of depression of a brake pedal 48.

[0024] The main ECU 30 controls, for example, the steering device 26, the air conditioning device 29, the display of the display device 70, and the communication of the communication device 72. As described above, the main ECU 30 communicates with the drive ECU 23, the brake ECU 25, etc. via the communication port. The main ECU 30 communicates with the electronic control unit for shifting (hereinafter referred to as "shift ECU") 50, the electronic control unit for surrounding recognition (hereinafter referred to as "surrounding recognition ECU") 55, and the navigation device 60 via the communication port.

[0025] Although not shown in the figure, the shift ECU 50 has a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and a communication port. A shift position signal from a shift position sensor 52 that detects the operation position of a shift lever 51 is input to the shift ECU 50 via an input port. The shift positions include a parking position (P position), a neutral position (N position), a drive position (D position), a reverse position (R position), and the like. The shift ECU 50 is connected to the main ECU 30 and the peripheral identification ECU 55 via a communication port. The shift ECU 50 sets the shift position based on the shift position signal from the shift position sensor 52 and the control signal from the peripheral identification ECU 55, or sends the set shift position to the main ECU 30.

[0026] Although not shown in the figure, the surrounding recognition ECU 55 has a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and a communication port. Various signals are input to the surrounding recognition ECU 55 via the input port. For example, the signal input to the surrounding recognition ECU 55 can include a signal representing information about the vehicle and its surroundings from the surrounding recognition device 56 (for example, the inter-vehicle distance D1, D2 with other vehicles in front and behind the vehicle, the driving position of the vehicle in the lane on the road, etc.), a mode signal from the automatic driving switch 57, etc. As the surrounding recognition device 56, for example, a camera, a millimeter wave radar, a quasi-millimeter wave radar, an infrared laser radar, a sonar, etc. can be listed. The automatic driving switch 57 is a switch for switching between a manual driving mode in which the driver performs driving operations and an automatic driving mode in which the driver does not perform driving operations. As described above, the surrounding recognition ECU 55 communicates with the main ECU 30 and the shift ECU 50 via the communication port.

[0027] The navigation device 60 includes a main body 61 with a built-in control unit, a GPS antenna 62 for receiving information related to the current location of the vehicle, and a display 63. The control unit of the main body 61 has a storage medium (such as a hard disk, SSD, etc.) storing map information, etc., an input / output port, and a communication port. In the map information, service information (such as sightseeing information, parking lots, etc.), road information of each driving section (such as between traffic lights, between intersections, etc.), etc. are stored as a database. The road information includes distance information, width information, number of lanes information, regional information (urban area, suburbs), category information (general roads, highways), slope information, legal speed, number of traffic lights, turning radius of each curve, etc. The display 63 is configured as a touch panel display that displays various information such as information related to the current location of the vehicle and the planned driving route to the destination, and the user can input various instructions. When the user sets a destination by operating the display 63, the main body 61 of the navigation device 60 sets a planned driving route from the current location of the vehicle to the destination based on the map information stored in the main body 61 and the current location and destination of the vehicle from the GPS antenna 62. The main body 61 of the navigation device 60 displays the set planned driving route on the display 63 to provide route guidance.

[0028] In the battery electric vehicle 20 of the embodiment thus constructed, the vehicle is driven by switching between the manual driving mode (automatic driving switch 57 is turned off) and the automatic driving mode (automatic driving switch 57 is turned on). In the manual driving mode, the main ECU 30 sets the required torque Td* for driving based on the accelerator position AP, the brake position BP and the vehicle speed V. The main ECU 30 controls the motor 22m (inverter 22i) and the brake device 24 so as to drive with the set required torque Td*. In the embodiment, when the accelerator is turned off and the vehicle speed V is below the threshold value Vref0, it is determined that the creep torque condition is satisfied. In addition, the creep torque is set to the required torque Td*, and the motor 22m is controlled so that the creep torque is output from the motor 22m to the drive shaft 22a. The threshold value Vref0 is, for example, about 5km / h to 10km / h.

[0029] In the automatic driving mode, the main ECU 30 sets the target vehicle speed V* based on the information from the navigation device 60 (e.g., the planned travel route, the current location of the vehicle, map information, etc.) and the information from the surrounding recognition device 56 (e.g., information of the vehicle and its surroundings). The main ECU 30 sets the required torque Td* so that the vehicle speed V becomes the target vehicle speed V*, and controls the motor 22m (inverter 22i), the brake device 24, and the steering device 26 so that the vehicle travels along the planned travel route with the required torque Td*. In the embodiment, the main ECU 30 determines that the creep torque condition is satisfied when the vehicle speed V and the target vehicle speed V* are less than the threshold value Vref0. In addition, the main ECU 30 sets the creep torque to the required torque Td* and controls the motor 22m so that the creep torque is output from the motor 22m to the drive shaft 22a. It should be noted that the creep torque condition may be replaced by the condition that the vehicle speed V and the target vehicle speed V* are less than the threshold value Vref0, and may be set to the condition that at least one of the vehicle speed V and the target vehicle speed V* is less than the threshold value Vref0.

[0030] Next, the operation of the battery-powered vehicle 20 according to the embodiment, particularly the operation when the creep torque is output from the motor 22m to the drive shaft 22a, will be described. Figure 2 2 is a flowchart showing an example of a processing routine executed by the main ECU 30. This routine is repeatedly executed when the creep torque is output from the motor 22m to the drive shaft 22a.

[0031] When executing this routine, the main ECU 30 determines whether it is a manual driving mode or an automatic driving mode (S100). And, when it is determined that it is a manual driving mode, it is determined whether the vehicle speed V is less than the threshold value Vref1 (S110), and it is determined whether the brake is on (S120). Here, the threshold value Vref1 is a threshold value for determining whether the vehicle is stopped in the manual driving mode. The threshold value Vref1 is determined as a vehicle speed lower than the above-mentioned threshold value Vref0, for example, 0 km / h to several km / h. The determination process of whether the brake is on can be performed by, for example, determining whether the brake pedal 48 is stepped on, whether the braking force is applied from the brake device 24 to the drive wheels 28a, 28b, and the driven wheels 28c, 28d. The processing of S110 and S120 is a process for determining whether the creep cut-off condition for cutting off the creep torque is established in the manual driving mode.

[0032] If the vehicle speed V is higher than the threshold value Vref1 in S110 or the brake is released in S120 , the creep cut-off condition is determined not to be satisfied, creep torque cut-off is prohibited ( S150 ), and this routine ends. In this case, the motor 22 m outputs creep torque to the drive shaft 22 a .

[0033] If the vehicle speed V is determined to be less than the threshold value Vref1 in S110 and the brake is determined to be on in S120, the creep cut-off condition is determined to be satisfied, creep torque is cut off (S140), and this routine ends. In this case, the motor 22m does not output creep torque to the drive shaft 22a.

[0034] If it is determined in S100 that the automatic driving mode is in operation, it is determined whether the vehicle speed V is equal to or lower than the threshold value Vref1 ( S130 ). The process in S130 is a process for determining whether the creep cut condition is satisfied in the automatic driving mode.

[0035] When it is determined in S130 that the vehicle speed V is higher than the threshold value Vref1, it is determined that the creep cut-off condition is not satisfied, the creep torque cut-off is prohibited (S150), and the routine ends. On the other hand, when it is determined in S130 that the vehicle speed V is lower than the threshold value Vref1, it is determined that the creep cut-off condition is satisfied, the creep torque cut-off is executed (S150), and the routine ends.

[0036] Thus, in the manual driving mode, the condition that the vehicle speed V is less than the threshold value Vref1 and the brake is on is used as the creep cut-off condition. In contrast, in the automatic driving mode, the condition that the vehicle speed V is less than the threshold value Vref1 is used as the creep cut-off condition. That is, in the automatic driving mode, the creep cut-off condition is relaxed compared to the manual driving mode (the creep cut-off condition is easily satisfied). Thus, in the automatic driving mode, it is easier to cut off the creep torque than in the manual driving mode, so that the power consumption of the vehicle can be suppressed and the power economy can be improved. Of course, in the manual driving mode, the response to the driver's acceleration request can be prioritized.

[0037] In the battery electric vehicle 20 of the present embodiment described above, when the creep torque is output from the motor 22m to the drive shaft 22a, if the creep cut-off condition is satisfied, the creep torque is cut off. In this case, in the automatic driving mode, the creep cut-off condition is relaxed compared to the manual driving mode (the creep cut-off condition is easily satisfied). As a result, in the automatic driving mode, it is easier to cut off the creep torque than in the manual driving mode, so that the power consumption of the vehicle can be suppressed and the power economy can be improved. Of course, in the manual driving mode, the response to the driver's acceleration request can be prioritized.

[0038] In the above-mentioned embodiment, the main ECU 30 executes Figure 2 , but you can also instead execute Figure 3 processing routine. Figure 3 The processing routine of is different from that of Figure 2 The processing routines are different.

[0039] exist Figure 3 In the processing routine of , when it is determined in S100 that the automatic driving mode is in operation, it is determined whether the target vehicle speed V* is less than the threshold value Vref1 (S132). Furthermore, when it is determined that the target vehicle speed V* is higher than the threshold value Vref1, it is determined that the creep cut-off condition is not satisfied, the creep torque cut-off is prohibited (S150), and the routine is terminated. On the other hand, when it is determined that the target vehicle speed V* is less than the threshold value Vref1, it is determined that the creep cut-off condition is satisfied, the creep torque cut-off is executed (S150), and the routine is terminated.

[0040] Considering the case where the vehicle slows down and stops, the vehicle speed V decreases after the target vehicle speed V* decreases. Therefore, after the target vehicle speed V* reaches the threshold value Vref1 or less, the vehicle speed V reaches the threshold value Vref1. Therefore, instead of Figure 2The condition that the vehicle speed V is less than the threshold value Vref1 is used as in S130 of the processing routine of the control unit, and the condition that the target vehicle speed V* is less than the threshold value Vref1 is used. As a result, when the vehicle speed is decelerated and stopped, the creep torque can be cut off at an earlier timing. As a result, the power consumption of the vehicle can be further suppressed.

[0041] In the above-mentioned embodiment, Figure 2 In the processing routine, the same threshold value Vref1 is used to determine whether the vehicle is stopped in the manual driving mode and whether the vehicle is stopped in the automatic driving mode. However, the threshold value Vref1 may be used to determine whether the vehicle is stopped in the manual driving mode, and the threshold value Vref2 which is higher than the threshold value Vref1 and lower than the threshold value Vref0 may be used to determine whether the vehicle is stopped in the automatic driving mode. In this way, the creep torque is easily cut off in the automatic driving mode, so the power consumption of the vehicle can be suppressed. Figure 3 The processing routine can also be changed in the same way.

[0042] In the above-mentioned embodiment, the battery electric vehicle 20 is provided with a motor 22m, an inverter 22i and a battery 22b as the driving device 22. However, it may be provided with a hybrid electric vehicle (hybrid electric vehicle) provided with an engine as a driving device in addition to the motor, the inverter and the battery. It may also be provided with a fuel cell electric vehicle (fuel cell electric vehicle) provided with a fuel cell as a driving device in addition to the motor, the inverter and the battery.

[0043] The correspondence between the main elements of the embodiment and the main elements of the invention described in the means for solving the problem column is described. In the embodiment, the drive device 22 having the motor 22m and the battery 22b corresponds to the "drive device", and the main ECU 30 and the drive ECU 23 correspond to the "control device".

[0044] It should be noted that the correspondence between the main elements of the embodiment and the main elements of the invention recorded in the column of means for solving the problem is an example of a way for the embodiment to specifically explain the way in which the invention recorded in the column of means for solving the problem is implemented. Therefore, the elements of the invention recorded in the column of means for solving the problem are not limited. That is, the interpretation of the invention recorded in the column of means for solving the problem is based on the record in the column, and the embodiment is only a specific example of the invention recorded in the column of means for solving the problem.

[0045] Although the embodiments for implementing the present disclosure have been described above, the present disclosure is not limited to such embodiments, and can of course be implemented in various forms within the scope not departing from the gist of the present disclosure.

[0046] The present disclosure can be used in the electric vehicle manufacturing industry and the like.

Claims

1. An electric vehicle, wherein: The electric vehicle comprises: a drive device including a motor for traveling and a power storage device for exchanging electric power with the motor; as well as A control device, wherein the control device controls the drive device so as to switch between a manual driving mode and an automatic driving mode for driving, and if a creep cut-off condition is satisfied when a creep torque is output from the motor, the creep torque is cut off, and in the automatic driving mode, the creep cut-off condition is relaxed compared to the manual driving mode.

2. The electric vehicle according to claim 1, wherein: In the manual driving mode, the creep cut-off condition is a condition that the vehicle speed is lower than the first vehicle speed and the brake is on. In the automatic driving mode, the creep cut condition is a condition that the vehicle speed is equal to or lower than a second vehicle speed, and the second vehicle speed is a vehicle speed equal to or higher than the first vehicle speed.

3. The electric vehicle according to claim 1, wherein: The control device controls the motor in the automatic driving mode so that the vehicle speed becomes a target vehicle speed based on the current location of the vehicle. In the manual driving mode, the creep cut-off condition is a condition that the vehicle speed is lower than a first vehicle speed and the brake is on. In the automatic driving mode, the creep cut condition is a condition that the target vehicle speed is equal to or lower than a second vehicle speed, and the second vehicle speed is a vehicle speed equal to or higher than the first vehicle speed.

Images