JP2022036823A - Electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a shortage of driving force with respect to a required driving force while realizing a driving sensation required by a driver. SOLUTION: It is possible to execute a manual speed change running mode in which a torque of a running electric motor is controlled so as to have a torque characteristic corresponding to a shift stage mode selected by an operation of a clutch device and a shift device by a driver. It is an electric vehicle equipped with a control device having a torque control unit, and the control device is a driving force and a required drive that can be output with the torque characteristics of the currently selected shift stage mode while traveling in the manual shift drive mode. The torque control unit has a determination unit that compares the forces and determines whether or not the driving force is insufficient for the required driving force, and when the determination unit determines that the driving force is insufficient for the required driving force, the torque control unit is used. , Raises the upper limit of the driving force in the currently selected shift driving mode. [Selection diagram] FIG. 8

Description

The present invention relates to an electric vehicle.

Patent Document 1 discloses that in an electric vehicle powered by an electric motor, control is performed to change the torque of the electric motor according to a vehicle speed, an accelerator opening degree, and a brake depression amount in order to produce a feeling of shifting. Has been done.

Japanese Unexamined Patent Publication No. 2018-166386

In the configuration described in Patent Document 1, since the clutch pedal and the shift lever do not exist in the driver's seat, the pseudo shift control is performed without the intervention of the shift operation by the driver himself / herself. Therefore, it gives a sense of discomfort to the driver who seeks the enjoyment of driving such as operating an MT vehicle. Therefore, in order to realize the driving feeling required by the driver, it is conceivable to provide a clutch pedal and a shift lever in the electric vehicle. In this electric vehicle, it is possible to select a manual shift running mode in which shift control is executed according to the operation of the clutch pedal and the shift lever.

However, in the manual shift traveling mode, a limit value is set for the driving force of the motor for each shift mode in order to simulate a plurality of shift stages. Therefore, when the driving force required for the vehicle (required driving force) is large while driving in the manual driving mode, a driving force larger than the limit value of the driving force in the shift stage mode is required, and the required driving force is required. There is a risk that the driving force will be insufficient.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electric vehicle capable of suppressing a shortage of driving force with respect to a required driving force while realizing a driving sensation required by a driver. ..

The present invention selects one of a traveling motor, a clutch device operated by the driver, and a plurality of gear modes in which the torque characteristics with respect to the rotation speed of the motor are stepwise different. It is possible to execute a manual shift traveling mode in which the torque of the electric motor is controlled so as to have torque characteristics corresponding to the shift device selected by the driver's operation of the clutch device and the shift device. An electric vehicle including a control device having a torque control unit, wherein the control device is running in the manual shift travel mode and can output a driving force that can be output with the torque characteristics of the shift mode currently selected. The torque control unit has a determination unit for determining whether or not the driving force is insufficient for the required driving force by comparing the required driving force with the torque control unit. When it is determined that the torque is generated, the upper limit of the driving force in the currently selected shift traveling mode is raised.

In the present invention, when it is determined that the driving force that can be output by the torque characteristics of the current gear shifting mode causes insufficient driving force with respect to the required driving force while traveling in the manual shifting driving mode, the gear shifting stage thereof. The upper limit of the driving force in the mode can be raised. As a result, it is possible to suppress the occurrence of insufficient driving force while realizing the driving sensation required by the driver.

FIG. 1 is a skeleton diagram schematically showing an electric vehicle according to an embodiment. FIG. 2 is a functional block diagram for explaining the configuration of the control device. FIG. 3 is a diagram showing a calculation map of the virtual engine output torque. FIG. 4 is a diagram showing a calculation map of torque transmission gain. FIG. 5 is a diagram showing a calculation map of the gear ratio. FIG. 6 is an operation flow diagram showing a procedure of a pseudo manual shifting operation executed by the driver. FIG. 7 is a diagram showing an example of torque characteristics of a motor corresponding to a plurality of shift speed modes. FIG. 8 is a flowchart showing a driving force determination flow carried out during traveling in the manual speed change traveling mode.

Hereinafter, the electric vehicle according to the embodiment of the present invention will be specifically described with reference to the drawings. The present invention is not limited to the embodiments described below.

FIG. 1 is a skeleton diagram schematically showing an electric vehicle according to an embodiment. As shown in FIG. 1, the electric vehicle 10 includes a motor 2 as a power source for traveling. The motor 2 is, for example, a three-phase AC motor. The output shaft 3 of the motor 2 is connected to one end of the propeller shaft 5 via the gear mechanism 4. The other end of the propeller shaft 5 is connected to the drive shaft 7 in front of the vehicle via the differential gear 6. The electric vehicle 10 includes a drive wheel 8 as a front wheel and a driven wheel 12 as a rear wheel. The drive wheels 8 are provided at both ends of the drive shaft 7. Further, a shaft rotation speed sensor 40 for detecting the shaft rotation speed Np is arranged on the propeller shaft 5. A wheel rotation speed sensor 42 for detecting the wheel rotation speed Nw is arranged on the drive wheel 8. The signals detected by the shaft rotation speed sensor 40 and the wheel rotation speed sensor 42 are output to the control device 50, respectively.

The electric vehicle 10 includes a battery 14, an inverter 16, and a control device 50. The battery 14 stores electrical energy used to drive the motor 2. The inverter 16 converts the direct current stored in the battery 14 into a three-phase alternating current by, for example, performing pulse width modulation processing (PWM). The inverter 16 has a function of controlling the drive torque of the motor 2 based on the target drive torque input from the control device 50. That is, the motor 2 is controlled by the control device 50.

Further, the electric vehicle 10 includes an accelerator pedal 22 for inputting an acceleration request and a brake pedal 24 for inputting a braking request as an operation request input device for the driver to input an operation request for the electric vehicle 10. , Is equipped. The accelerator pedal 22 is provided with an accelerator position sensor 32 for detecting the accelerator opening degree Pap (%). Further, the brake pedal 24 is provided with a brake position sensor 34 that detects the pedal depression amount. The signals detected by the accelerator position sensor 32 and the brake position sensor 34 are output to the control device 50, respectively.

Further, the electric vehicle 10 includes a shift lever 26 and a clutch pedal 28 as an operation request input device for shifting. However, since the electric vehicle 10 is a vehicle driven by a motor 2 and does not have an engine as a power source, it does not have a transmission and a clutch mechanism included in an MT vehicle. Therefore, the shift lever 26 and the clutch pedal 28 are provided with the following functions in place of the functions of mechanically operating the actual transmission and the clutch mechanism.

The shift lever 26 functions as a shift device for the driver to select one shift mode from a plurality of shift modes in which torque characteristics with respect to the rotation speed of the motor 2 are defined stepwise. The plurality of shift modes here are shift modes simulating the gear stages (shift stages) of an MT vehicle, and are, for example, 1st speed (1st), 2nd speed (2nd), 3rd speed (3rd), and 4th speed (4th). ), 5th gear (5th), 6th gear (6th), and neutral (N) gear mode. As shown in FIG. 7, for example, the torque characteristics of each shift mode are preset to the torque characteristics simulating the gear stages of an MT vehicle. That is, a limit value (upper limit value) is provided for the driving force of the motor 2 for each shift mode. However, since each of these gear speed modes is a simulated reproduction of the gear gear of an MT vehicle, there are no restrictions on the torque characteristics for corresponding to the actual fixed gear ratio. That is, the torque characteristics of each of the plurality of shift speed modes can be freely preset as long as they are within the output range of the motor 2.

The shift lever 26 has a structure simulating a shift lever included in an MT vehicle. The arrangement and operation feeling of the shift lever 26 are the same as those of an actual MT vehicle. The shift lever 26 is provided with each position corresponding to a plurality of shift mode modes having different torque characteristics. The shift lever 26 is provided with a shift position sensor 36 that detects the shift position Gp indicating the position of the shift mode. The signal detected by the shift position sensor 36 is output to the control device 50.

The clutch pedal 28 functions as a clutch device having a structure simulating a clutch pedal included in an MT vehicle. The clutch pedal 28 is stepped on when the driver operates the shift lever 26. The arrangement and operation feeling of the clutch pedal 28 are the same as those of an actual MT vehicle. The clutch pedal 28 is provided with a clutch position sensor 38 for detecting the clutch pedal depression amount Pc (%), which is the operation amount of the clutch pedal 28. The signal detected by the clutch position sensor 38 is output to the control device 50.

In the electric vehicle 10, it is possible to realize a plurality of traveling modes by controlling the control device 50. The plurality of driving modes include a manual speed change driving mode and an electric driving mode. The manual shift running mode is a running mode in which the drive torque of the motor 2 is controlled according to the operation of the shift lever 26 and the clutch pedal 28 by the driver. The electric travel mode is a travel mode in which the drive torque of the motor 2 is controlled without operating the shift lever 26 and the clutch pedal 28. That is, the manual speed change driving mode realizes an operation feeling like that of an MT vehicle. The electric driving mode gives an operation feeling like that of an AT vehicle, does not require the driver to operate the shift lever 26 and the clutch pedal 28, and responds to the driver's operation of the accelerator pedal 22 and the brake pedal 24. The drive torque of the motor 2 is controlled.

The control device 50 is an ECU (Electronic Control Unit). The processing circuit of the control device (hereinafter referred to as ECU) 50 includes an input / output interface 52, a memory 54, and a CPU 56. The input / output interface 52 takes in sensor signals from various sensors attached to the electric vehicle 10, and outputs operation signals to various actuators included in the electric vehicle 10. In addition to the various sensors described above, the sensors that the ECU 50 captures signals include various sensors necessary for controlling the electric vehicle 10. The actuator for which the ECU 50 outputs an operation signal includes various actuators such as the motor 2 described above. Various control programs for controlling the electric vehicle 10, the latest shift position Gp, a map, and the like are stored in the memory 54. The CPU 56 reads a control program or the like from the memory 54 and executes it, and generates an operation signal based on the captured sensor signal.

The control of the electric vehicle 10 performed by the ECU 50 includes torque control for controlling the torque transmitted to the drive wheels 8. In the torque control here, the drive torque of the motor 2 is controlled so that the motor drive torque Tp transmitted to the propeller shaft 5 becomes the motor required drive torque Tpreq.

That is, the ECU 50 is output from the motor 2 so that the required driving force calculation unit that calculates the driving force (required driving force) required by the driver for the electric vehicle 10 and the driving force of the motor 2 become the required driving force. It has a torque control unit that controls the torque.

The required driving force calculation unit calculates the required driving force based on the accelerator opening degree Pap and the vehicle speed. For example, the ECU 50 detects the vehicle speed using the wheel rotation speed Nw from the wheel rotation speed sensor 42. Then, the required driving force calculation unit calculates the required driving force based on the accelerator opening degree Pap and the vehicle speed using a predetermined map. This map is stored in advance in a storage unit included in the ECU 50. Further, the torque control unit calculates the driving torque of the motor 2 so that the driving force can satisfy the required driving force calculated by the required driving force calculation unit. The ECU 50 is not limited to the configuration in which the vehicle speed is detected by using the wheel rotation speed Nw from the wheel rotation speed sensor 42 when detecting the vehicle speed, and the vehicle speed is determined by using the shaft rotation speed Np from the shaft rotation speed sensor 40. It may be calculated.

Further, in the torque control of the motor 2, the ECU 50 performs an operation assuming that the traveling state of the electric vehicle 10 is realized by the MT vehicle equipped with the virtual engine and the transmission during the manual shifting traveling mode. Then, the ECU 50 calculates the transmission output torque Tgout output from the transmission, and uses the calculated transmission output torque Tgout as the motor required drive torque Tpreq. In the following description, the engine virtually mounted on the electric vehicle 10 is described as "virtual engine", the engine output torque of the virtual engine is described as "virtual engine output torque Teu", and the rotation speed of the virtual engine is described. Is described as "virtual engine rotation speed Ne".

FIG. 2 is a functional block diagram for explaining the configuration of the control device. The ECU 50 has a virtual engine rotation speed calculation unit 500, a virtual engine output torque calculation unit 502, a torque transmission gain calculation unit 504, a clutch output torque calculation unit 506, and gears as functional blocks related to torque control of the motor 2. It includes a ratio calculation unit 508, a transmission output torque calculation unit 510, and a determination unit 512.

For example, while the electric vehicle 10 is traveling, the ECU 50 dynamically calculates the virtual engine rotation speed Ne based on the operating state. Specifically, the ECU 50 has a shaft rotation speed Np of the propeller shaft 5, a gear ratio (gear ratio) r corresponding to the shift position Gp, and a slip ratio slip of the clutch mechanism calculated from the clutch pedal depression amount Pc and the like. From the following equation (1) using the above, the virtual engine rotation speed Ne during running is calculated back.
Ne = Np × (1 / r) × slip ... (1)

Of the energy output from the virtual engine, it can be assumed that the kinetic energy that is not used for torque transmission to the propeller shaft 5 is used for increasing the virtual engine rotation speed Ne. Therefore, the virtual engine rotation speed Ne may be dynamically calculated based on an equation of motion based on kinetic energy.

Further, assuming an MT vehicle, idle speed control control (ISC control) for maintaining the engine rotation speed at a constant rotation speed is performed while the MT vehicle is idling. Therefore, in consideration of ISC control in the virtual engine, the ECU 50 indicates that the virtual engine is idling when, for example, the shaft rotation speed Np is 0 (zero) and the accelerator opening Pap is 0%. Is assumed, the virtual engine rotation speed Ne is output as a predetermined idling rotation speed (for example, 1000 rpm). The calculated virtual engine rotation speed Ne is output to the virtual engine output torque calculation unit 502.

The virtual engine output torque calculation unit 502 executes a process of calculating the virtual engine output torque Teu. The accelerator opening degree Pap and the virtual engine rotation speed Ne are input to the virtual engine output torque calculation unit 502. The memory 54 of the ECU 50 stores a map in which the virtual engine output torque Teout with respect to the virtual engine rotation speed Ne is defined for each accelerator opening Pap. An example of the map is shown in FIG. The virtual engine output torque calculation unit 502 calculates the virtual engine output torque Teu corresponding to the input accelerator opening degree Pap and the virtual engine rotation speed Ne by using the map shown in FIG. The calculated virtual engine output torque Teout is output to the clutch output torque calculation unit 506.

The torque transmission gain calculation unit 504 executes a process of calculating the torque transmission gain k. The torque transmission gain k is a gain for calculating the degree of torque transmission according to the amount of depression of the clutch for operating the clutch mechanism connected to the virtual engine. The clutch pedal depression amount Pc is input to the torque transmission gain calculation unit 504. The memory 54 of the ECU 50 stores a map in which the torque transmission gain k with respect to the clutch pedal depression amount Pc is defined. An example of the map is shown in FIG. As shown in FIG. 4, the torque transmission gain k becomes 1 when the clutch pedal depression amount Pc is in the range of pc0 to pc1, and when the clutch pedal depression amount Pc is in the range of Pc1 to Pc2, the clutch pedal depression amount Pc increases. It is specified that the amount of depression of the clutch pedal Pc gradually decreases toward 0 and becomes 0 in the range of Pc1 to Pc2. Here, Pc0 corresponds to the position where the clutch pedal depression amount Pc corresponds to 0%, Pc1 corresponds to the position of the play limit when depressing from Pc0, and Pc3 corresponds to the position where the clutch pedal depression amount Pc corresponds to 100%. , Pc2 corresponds to the position of the play limit at the time of returning from Pc3. The torque transmission gain calculation unit 504 calculates the torque transmission gain k corresponding to the input clutch pedal depression amount Pc using the map shown in FIG. The calculated torque transmission gain k is output to the clutch output torque calculation unit 506.

The clutch output torque calculation unit 506 executes a process of calculating the clutch output torque Tcout. The clutch output torque Tcout is the torque output from the clutch mechanism connected to the virtual engine. The virtual engine output torque Teu and the torque transmission gain k are input to the torque transmission gain calculation unit 504. In the clutch output torque calculation unit 506, the clutch output torque Tcout is calculated by using the following equation (2) in which the virtual engine output torque Teu is multiplied by the torque transmission gain k. The calculated clutch output torque Tcout is output to the transmission output torque calculation unit 510.
Tcout = Teu x k ... (2)
The actual clutch mechanism often includes a damping device such as a spring or a damper. Therefore, the clutch output torque Tcout may calculate the dynamic transmission torque in consideration of each characteristic.

The gear ratio calculation unit 508 executes a process of calculating the gear ratio r. The gear ratio r is a torque characteristic of the motor 2 corresponding to a plurality of gear ratio modes, and simulates the gear ratio of the transmission. The shift position Gp is input to the gear ratio calculation unit 508. The memory 54 of the ECU 50 stores a map in which the gear ratio r with respect to the shift position Gp is defined. An example of the map is shown in FIG. As shown in FIG. 5, the gear ratio r is defined so that the gear ratio r becomes lower as the shift position Gp is in higher gear. The gear ratio calculation unit 508 calculates the gear ratio r corresponding to the input shift position Gp using the map shown in FIG. The calculated gear ratio r is output to the transmission output torque calculation unit 510.

The transmission output torque calculation unit 510 executes a process of calculating the transmission output torque Tgout. The transmission output torque Tgout is the torque output from the transmission. The clutch output torque Tcout and the gear ratio r are input to the transmission output torque calculation unit 510. In the transmission output torque calculation unit 510, the transmission output torque Tgout is calculated by using the following equation (3) in which the clutch output torque Tcout is multiplied by the gear ratio r.
Tgout = Tcout × r ... (3)

As described above, in the torque control during the manual shift running mode, the ECU 50 calculates the virtual engine output torque calculation unit 502, the torque transmission gain calculation unit 504, the clutch output torque calculation unit 506, the gear ratio calculation unit 508, and the transmission output torque. The processes in unit 510 are executed in order. Then, the calculated transmission output torque Tgout is output to the inverter 16 as the motor required drive torque Tpreq. In the inverter 16, the command value to the motor 2 is controlled so that the motor drive torque Tp approaches the calculated motor required drive torque Tpreq. In torque control, the motor drive torque Tp is controlled by the motor required drive torque Tpreq by repeatedly executing such processing in a predetermined control cycle.

The driver of the electric vehicle 10 performs a manual shift operation at an arbitrary timing during operation with the manual shift traveling mode selected. FIG. 6 is an operation flow diagram showing a procedure of a pseudo manual shift operation executed by the driver. As shown in FIG. 6, when the driver performs a pseudo manual shifting operation in the electric vehicle 10, the driver first depresses the clutch pedal 28 (step S101). When the clutch pedal depression amount Pc exceeds Pc1, the clutch output torque Tcout changes toward 0 as the clutch pedal depression amount Pc increases. When the clutch pedal depression amount Pc exceeds Pc2, the clutch output torque Tcout becomes 0. According to such a depressing operation of the clutch pedal 28, the motor drive torque Tp changes toward 0 in response to the depressing operation of the clutch pedal 28, so that when the driver depresses the clutch pedal of the MT vehicle, the driver depresses the clutch pedal. You can feel the torque coming off.

Next, the driver operates the shift lever 26 with the clutch pedal 28 depressed (step S102). For example, the shift mode of the shift lever 26 is operated from the first speed to the second speed. By operating the shift lever 26 accompanied by depressing the clutch pedal 28, the driver can obtain a feeling close to the manual shifting operation of the MT vehicle.

After that, the driver returns the clutch pedal 28 (step S103). When the clutch pedal depression amount Pc is less than Pc3, the clutch output torque Tcout changes toward the virtual engine output torque Teout as the clutch pedal depression amount Pc decreases. When the clutch pedal depression amount Pc is less than Pc1, the clutch output torque Tcout becomes the virtual engine output torque Teu. According to such a return operation of the clutch pedal 28, the motor drive torque Tp changes toward the motor drive torque Tp reflecting the current mode in response to the return operation of the clutch pedal 28. You can feel the torque connected when the clutch pedal of the MT vehicle is released.

As described above, according to the electric vehicle 10, the torque changes according to the operation of the clutch pedal 28, so that the driver can experience the unique shifting feeling of the MT vehicle by the manual shifting operation in a pseudo manner. Further, the virtual engine output torque calculation unit 502, the torque transmission gain calculation unit 504, the clutch output torque calculation unit 506, the gear ratio calculation unit 508, and the transmission output torque calculation unit 510 are torques that enable the manual shift running mode to be executed. Functions as a control unit.

The determination unit 512 executes a process of determining whether or not the driving force is insufficient for the required driving force while the electric vehicle 10 is traveling. The determination unit 512 compares the driving force that can be output in the currently selected shift stage mode with the required driving force required by the driver for the electric vehicle 10 while traveling in the manual shift driving mode, and requests the driving force. It is determined whether or not the driving force is insufficient with respect to the driving force.

FIG. 8 is a flowchart showing a driving force determination flow carried out during traveling in the manual speed change traveling mode. The control shown in FIG. 8 is repeatedly executed by the ECU 50 while the traveling mode is selected as the manual shifting traveling mode.

The ECU 50 compares the driving force that can be output in the currently selected shift stage mode with the required driving force while traveling in the manual shifting driving mode, and determines whether or not the driving force is insufficient for the required driving force. (Step S201). In step S201, the determination process by the determination unit 512 is performed. For example, when the electric vehicle 10 travels on an uphill road having a large slope, the required driving force becomes large.

In step S201, for example, when the currently selected shift mode is 3rd gear, the determination unit 512 compares the driving force that can be output by the torque characteristic in the 3rd gear shift mode with the required driving force. That is, the upper limit value of the driving force of the motor 2 set in the 3rd speed shift mode is used to compare the upper limit value of the driving force with the required driving force. When the required driving force is larger, it is determined that the driving force is insufficient in the currently selected 3-speed shift mode.

When it is determined that the driving force is insufficient with respect to the required driving force (step S201: No), this control routine ends.

When it is determined that the driving force is insufficient for the required driving force (step S201: Yes), the ECU 50 raises the upper limit value of the driving force in the current shift stage mode (step S202). In step S202, for the torque characteristic (for example, shown in FIG. 7) preset as the currently selected shift mode, the upper limit of the driving force is set so that the upper limit of the driving force in the torque characteristic becomes a larger value. The value is changed.

In the process of step S202, the ECU 50 can raise the upper limit of the driving force of the shift mode within the output range of the motor 2 with respect to the torque characteristic in the selected shift mode. For example, when raising the upper limit value of the driving force in the 3rd speed shift mode, the upper limit value of the driving force can be changed to a magnitude close to the torque characteristic of the 2nd speed shift mode. In this way, the upper limit of the driving force can be changed so as to be closer to the torque characteristic on the lower shift stage side than the shift gear currently being set. Alternatively, it is possible to change the upper limit value to the maximum of the output range of the motor 2. In short, the upper limit can be changed to a driving force that can satisfy the required driving force or a driving force that can minimize the shortage of the driving force. As a result, even on an uphill road with a large slope, the upper limit of the driving force is increased, so that the vehicle can travel in the selected shift mode. As a result, drivability is improved. When the process of step S202 is executed, this control routine ends.

As described above, according to the embodiment, when it is determined that the driving force is insufficient for the required driving force while traveling in the manual shifting driving mode, the upper limit of the driving force in the current shifting stage mode can be raised. can. As a result, it is possible to suppress a shortage of driving force. Further, by selecting the manual speed change driving mode, it becomes possible to give the driver a driving feeling like that of an MT vehicle.

2 Motor 10 Electric vehicle 22 Accelerator pedal 24 Brake pedal 26 Shift lever (shift device)
28 Clutch pedal (clutch device)
50 Control unit (ECU)
512 Judgment unit

Claims (1)

With a motor for driving
A clutch device operated by the driver and
A shift device that selects one of a plurality of shift modes in which the torque characteristics with respect to the rotation speed of the motor are gradually different, and a shift device that selects one of the shift modes.
It has a torque control unit capable of executing a manual shift running mode that controls the torque of the electric motor so as to have torque characteristics corresponding to the shift mode selected by the operation of the clutch device and the shift device by the driver. With the control device
It is an electric vehicle equipped with
While traveling in the manual shift drive mode, the control device compares the drive force that can be output with the torque characteristic of the shift stage mode currently selected and the required drive force, and the driving force is insufficient with respect to the required drive force. It has a determination unit that determines whether or not it occurs, and has a determination unit.
The torque control unit is characterized by raising the upper limit value of the driving force in the currently selected shift traveling mode when the determination unit determines that the driving force is insufficient for the required driving force. vehicle.

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