JP2024038489A - Electric car - Google Patents

Abstract

The present invention provides an electric vehicle in which a driver can easily enjoy zero start acceleration like an MT vehicle. A control device for an electric vehicle uses an electric motor as a driving power device and includes an accelerator pedal, a pseudo clutch pedal, a memory, and a processor. The memory stores a clutch model in which the relationship between the amount of depression of the pseudo clutch pedal and the torque transmission gain is defined. The processor determines the motor torque to be output from the electric motor based on the amount of depression of the accelerator pedal and the torque transmission gain. The clutch model is configured to vary the relationship between the amount of depression of the pseudo clutch pedal and the clutch transmission gain. [Selection diagram] Figure 12

Description

The present invention relates to an electric vehicle that uses an electric motor as a driving power device.

An electric motor used as a driving power device in an electric vehicle (EV) has significantly different torque characteristics from an internal combustion engine that has been used as a driving power device in conventional vehicles. Due to differences in the torque characteristics of power plants, CVs require a transmission, whereas EVs generally do not have a transmission. Of course, EVs are not equipped with a manual transmission (MT) that changes the gear ratio manually by the driver. For this reason, there is a big difference in driving sensation between driving a conventional vehicle with an MT (hereinafter referred to as an MT vehicle) and driving an EV.

On the other hand, the torque of an electric motor can be controlled relatively easily by controlling the applied voltage and magnetic field. Therefore, in an electric motor, by performing appropriate control, it is possible to obtain desired torque characteristics within the operating range of the electric motor. Taking advantage of this feature, techniques have been proposed to control the torque of an EV to simulate the torque characteristics unique to MT vehicles.

Patent Document 1 discloses a technique for producing a pseudo shift change in a vehicle in which torque is transmitted to wheels by a drive motor. In this vehicle, the torque of the drive motor is reduced by a set variation amount at a predetermined timing determined by the vehicle speed, accelerator opening degree, accelerator opening speed, or amount of brake depression, and then the torque is increased again at a predetermined time. Variation control is performed. The company claims that this will reduce the sense of discomfort that it gives to drivers who are accustomed to vehicles equipped with stepped transmissions.

Japanese Patent Application Publication No. 2018-166386

However, with the above technology, the timing of torque fluctuation control that simulates a gear shift operation cannot be independently determined by the driver's own operation. Particularly for drivers who are accustomed to driving MT vehicles, pseudo-shifting operations that do not involve the driver's own manual shifting operations may give a sense of discomfort to drivers who seek the pleasure of operating an MT. .

In consideration of these circumstances, the inventors of the present application are considering providing an EV with a pseudo shift device and a pseudo clutch pedal so that the EV can provide the driving sensation of a manual transmission vehicle. Of course, these pseudo devices are not simply attached to EVs. The inventors of the present application are considering making it possible to control an electric motor so as to obtain torque characteristics similar to those of an MT vehicle by operating a pseudo shift device and a pseudo clutch pedal.

By the way, one of the pleasures of driving a manual transmission vehicle is zero-start acceleration. Zero start acceleration is acceleration from a stopped state. In order to do this quickly and smoothly in a manual transmission vehicle, the driver must skillfully and cooperatively operate the accelerator pedal, shift device, and clutch pedal. In particular, the operation of the accelerator pedal and clutch pedal at the moment the vehicle starts moving is important in determining quick acceleration.

However, drivers these days are accustomed to driving AT vehicles with automatic transmissions (AT), so it is not easy to skillfully perform zero-start acceleration operations in MT vehicles. This is a problem that can similarly occur when reproducing the driving sensation of an MT vehicle in an EV. In particular, EVs can generate a large amount of torque from a stopped state, whereas MT vehicles have less torque at low speeds, and there is a big difference in driving sensation. Therefore, even if an EV achieves the torque characteristics of a manual transmission vehicle and zero-start acceleration becomes possible, a driver who is familiar with the driving sensation of an EV may not be able to perform the necessary operations well.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an electric vehicle in which a driver can easily enjoy zero-start acceleration like a manual transmission vehicle.

The electric vehicle according to the present invention is an electric vehicle that uses an electric motor as a driving power device, and includes an acceleration pedal, a pseudo clutch pedal, a pseudo shift device, a pseudo engine speed meter, and a control device. Be prepared. The control device is a device that controls the motor torque output by the electric motor.

The control device includes a memory and a processor. The memory stores the MT vehicle model. The MT vehicle model is a model that simulates the torque characteristics of drive wheel torque in an MT vehicle. The MT vehicle here is a vehicle that has an internal combustion engine whose torque is controlled by operating a gas pedal, and a manual transmission whose gears are changed by operating a clutch pedal and operating a shift device.

The processor executes the following first to sixth processes. The first process is a process of accepting the operation amount of the acceleration pedal as an input of the operation amount of the gas pedal for the MT vehicle model. The second process is a process of accepting the operation amount of the pseudo clutch pedal as an input of the operation amount of the clutch pedal for the MT vehicle model. The third process is a process of accepting the shift position of the pseudo shift device as an input of the shift position of the shift device for the MT vehicle model. The fourth process is a process of calculating the drive wheel torque determined by the operation amount of the acceleration pedal, the operation amount of the pseudo clutch pedal, and the shift position of the pseudo shift device using the MT vehicle model. The fifth process is a process of calculating a motor torque for applying drive wheel torque to the drive wheels of the own vehicle. The sixth process is a process of displaying the rotational speed of the internal combustion engine calculated using the MT vehicle model on a pseudo engine rotational speed meter.

When the zero start acceleration operation is detected when the electric vehicle is stopped, the processor executes at least one of the seventh and eighth processes below. Zero start acceleration operation is performed by increasing the rotational speed of the internal combustion engine displayed on the simulated engine rotational speed meter, that is, the rotational speed of the virtual internal combustion engine calculated by the MT vehicle model, to around a predetermined rotational speed, and then pressing the simulated clutch pedal. This is an operation that connects the The seventh process is a process in which the torque of the electric motor is made larger than that at the time of normal start. The eighth process is a process in which the torque transmission gain determined by the operation amount of the pseudo clutch pedal is made larger than that at the time of normal start.

According to the above configuration, the driver can drive the electric vehicle like a manual transmission vehicle having an internal combustion engine and a manual transmission. Furthermore, when it is desired to perform zero start acceleration, the torque of the electric motor is made larger than during normal start. Alternatively or additionally, the torque transmission gain determined by the amount of operation of the pseudo-clutch pedal is made larger than during normal start-up. As a result, sufficient driving force can be obtained at the time of starting, and the driver can easily enjoy zero starting acceleration like a manual transmission vehicle.

As described above, according to the present invention, it is possible to provide an electric vehicle in which a driver can easily enjoy zero-start acceleration like a manual transmission vehicle.

1 is a diagram schematically showing the configuration of a power system of an electric vehicle according to an embodiment of the present invention. 2 is a block diagram showing the configuration of a control system for the electric vehicle shown in FIG. 1. FIG. FIG. 2 is a block diagram showing functions of a control device for the electric vehicle shown in FIG. 1. FIG. 4 is a diagram showing an example of a motor torque command map included in the control device shown in FIG. 3. FIG. 4 is a block diagram showing an example of an MT vehicle model included in the control device shown in FIG. 3. FIG. 6 is a diagram showing an example of an engine model that constitutes the MT vehicle model shown in FIG. 5. FIG. 6 is a diagram showing an example of a clutch model that constitutes the MT vehicle model shown in FIG. 5. FIG. 6 is a diagram showing an example of an MT model that constitutes the MT vehicle model shown in FIG. 5. FIG. FIG. 3 is a diagram illustrating the torque characteristics of the electric motor realized in the MT driving mode in comparison with the torque characteristics of the electric motor realized in the EV driving mode. It is a flowchart which shows the procedure of zero start acceleration control. It is a figure which shows the 1st method of torque increase for zero start acceleration. It is a figure which shows the 2nd method of torque increase for zero start acceleration.

Embodiments of the present invention will be described below with reference to the drawings. However, in the embodiments shown below, when referring to the number, quantity, amount, range, etc. of each element, unless it is specifically specified or it is clearly specified to that number in principle, This invention is not limited to the number. Furthermore, the structures and the like described in the embodiments shown below are not necessarily essential to the present invention, unless specifically specified or clearly specified in principle. In each figure, the same or corresponding parts are denoted by the same reference numerals, and repeated explanations thereof will be simplified or omitted as appropriate.

1. Configuration of Electric Vehicle FIG. 1 is a diagram schematically showing the configuration of a power system of an electric vehicle 10 according to the present embodiment. As shown in FIG. 1, the electric vehicle 10 includes an electric motor 2 as a power source. The electric motor 2 is, for example, a brushless DC motor or a three-phase AC synchronous motor. The electric motor 2 is provided with a rotation speed sensor 40 for detecting its rotation speed. An output shaft 3 of the electric motor 2 is connected to one end of a propeller shaft 5 via a gear mechanism 4. The other end of the propeller shaft 5 is connected to a drive shaft 7 at the front of the vehicle via a differential gear 6.

The electric vehicle 10 includes driving wheels 8, which are front wheels, and driven wheels 12, which are rear wheels. Drive wheels 8 are provided at both ends of the drive shaft 7, respectively. Each wheel 8, 12 is provided with a wheel speed sensor 30. In FIG. 1, only the wheel speed sensor 30 of the right rear wheel is representatively depicted. The wheel speed sensor 30 is also used as a vehicle speed sensor for detecting the vehicle speed of the electric vehicle 10. The wheel speed sensor 30 is connected to a control device 50, which will be described later, via an in-vehicle network such as a CAN (Controller Area Network).

Electric vehicle 10 includes a battery 14 and an inverter 16. Battery 14 stores electrical energy for driving electric motor 2 . Inverter 16 converts DC power input from battery 14 into driving power for electric motor 2 . Power conversion by the inverter 16 is performed by PWM (Pulse Wave Modulation) control by the control device 50. Inverter 16 is connected to control device 50 via an in-vehicle network.

The electric vehicle 10 has an accelerator pedal (acceleration pedal) 22 for inputting an acceleration request and a brake for inputting a braking request as an operation request input device for the driver to input an operation request for the electric vehicle 10. It is equipped with a pedal 24. The accelerator pedal 22 is provided with an accelerator position sensor 32 for detecting the accelerator opening degree Pap [%], which is the operation amount of the accelerator pedal 22 . Further, the brake pedal 24 is provided with a brake position sensor 34 for detecting the amount of brake depression, which is the amount of operation of the brake pedal 24. An accelerator position sensor 32 and a brake position sensor 34 are connected to a control device 50 via an in-vehicle network.

The electric vehicle 10 further includes a pseudo shift lever (pseudo shift device) 26 and a pseudo clutch pedal 28 as operation input devices. Although a shift lever (shift device) and a clutch pedal are devices for operating a manual transmission (MT), the electric vehicle 10 is not equipped with an MT. The pseudo shift lever 26 and the pseudo clutch pedal 28 are merely dummies different from the original shift lever and clutch pedal.

The pseudo shift lever 26 has a structure that simulates a shift lever included in an MT vehicle. The arrangement and operational feel of the pseudo shift lever 26 are equivalent to those of an actual MT vehicle. The pseudo shift lever 26 is provided with positions corresponding to, for example, 1st, 2nd, 3rd, 4th, 5th, 6th, and neutral gear stages. The pseudo shift lever 26 is provided with a shift position sensor 36 that detects the gear stage by determining which position the pseudo shift lever 26 is in. Shift position sensor 36 is connected to control device 50 via an on-vehicle network.

The pseudo clutch pedal 28 has a structure that simulates a clutch pedal provided in an MT vehicle. The arrangement and operational feel of the pseudo clutch pedal 28 are equivalent to those of an actual MT vehicle. When the driver wants to change the gear setting using the pseudo shift lever 26, he depresses the pseudo clutch pedal 28, and when he finishes changing the gear setting, he stops depressing the pedal and returns the pseudo clutch pedal 28 to its original position. The pseudo clutch pedal 28 is provided with a clutch position sensor 38 for detecting the depression amount Pc [%] of the pseudo clutch pedal 28. Clutch position sensor 38 is connected to control device 50 via an on-vehicle network.

The electric vehicle 10 is equipped with a pseudo engine speed meter 44. The engine rotation speed meter is a device that displays the rotation speed of the internal combustion engine (engine) to the driver, but of course the electric vehicle 10 does not include an engine. The pseudo engine speed meter 44 is merely a dummy that is different from the original engine speed meter. The pseudo engine rotation speed meter 44 has a structure that simulates an engine rotation speed meter provided in a conventional vehicle. The pseudo engine speed meter 44 may be of a mechanical type or a liquid crystal display type. In the case of a liquid crystal display type, the rev limit may be set arbitrarily. The pseudo engine speed meter 44 is connected to the control device 50 via an on-vehicle network.

The electric vehicle 10 includes a mode selection switch 42. The mode selection switch 42 is a switch for selecting a driving mode of the electric vehicle 10. The driving modes of the electric vehicle 10 include an MT mode and an EV mode. The mode selection switch 42 is configured to be able to arbitrarily select either MT mode or EV mode. Although details will be described later, in the MT mode, the electric motor 2 is controlled in a control mode (first mode) for driving the electric vehicle 10 like a MT vehicle. In the EV mode, the electric motor 2 is controlled in a normal control mode (second mode) for general electric vehicles. The mode selection switch 42 is connected to the control device 50 via an in-vehicle network.

Control device 50 is typically an ECU (Electronic Control Unit) mounted on electric vehicle 10. The control device 50 may be a combination of multiple ECUs. The control device 50 includes an interface 52, a memory 54, and a processor 56. An in-vehicle network is connected to the interface 52. The memory 54 includes a RAM (Random Access Memory) that temporarily records data, and a ROM (Read Only Memory) that stores a control program executable by the processor 56 and various data related to the control program. . The processor 56 reads control programs and data from the memory 54 and executes them, and generates control signals based on signals acquired from each sensor.

FIG. 2 is a block diagram showing the configuration of a control system for electric vehicle 10 according to the present embodiment. Signals are input to the control device 50 from at least the wheel speed sensor 30 , the accelerator position sensor 32 , the brake position sensor 34 , the shift position sensor 36 , the clutch position sensor 38 , the rotational speed sensor 40 , and the mode selection switch 42 . An in-vehicle network is used for communication between these sensors and the control device 50. Although not shown, various other sensors are mounted on the electric vehicle 10 and connected to the control device 50 via an on-vehicle network.

Furthermore, signals are output from the control device 50 to at least the inverter 16 and the pseudo engine speed meter 44. An in-vehicle network is used for communication between these devices and the control device 50. Although not shown, various other actuators and indicators are mounted on the electric vehicle 10 and connected to the control device 50 via an on-vehicle network.

The control device 50 has a function as a zero start acceleration request determination section 500 and a function as a control signal calculation section 520. Specifically, the program stored in the memory 54 (see FIG. 1) is executed by the processor 56 (see FIG. 1), so that the processor 56 includes at least the zero start acceleration request determination section 500 and the control signal calculation section. 520. Control signal calculation is a function of calculating control signals for actuators and devices. The control signals include at least a signal for PWM control of the inverter 16 and a signal for displaying information on the pseudo engine speed meter 44. Hereinafter, these functions that the control device 50 has will be explained.

2. Control device functions 2-1. Motor Torque Calculation Function FIG. 3 is a block diagram showing functions of the control device 50 according to the present embodiment, particularly functions related to calculation of a motor torque command value for the electric motor 2. As shown in FIG. Control device 50 calculates a motor torque command value using the functions shown in this block diagram, and generates a control signal for PWM control of inverter 16 based on the motor torque command value.

As shown in FIG. 3, the control signal calculation section 520 includes an MT vehicle model 530, a required motor torque calculation section 540, a motor torque command map 550, and a changeover switch 560. Signals from the wheel speed sensor 30 , accelerator position sensor 32 , shift position sensor 36 , clutch position sensor 38 , rotational speed sensor 40 , and mode selection switch 42 are input to the control signal calculation unit 520 . The control signal calculation unit 520 processes the signals from these sensors and calculates the motor torque to be output by the electric motor 2.

There are two ways to calculate the motor torque by the control signal calculation unit 520: calculation using the MT vehicle model 530 and requested motor torque calculation unit 540, and calculation using the motor torque command map 550. The former is used to calculate the motor torque when the electric vehicle 10 is driven in the MT mode. The latter is used to calculate the motor torque when the electric vehicle 10 is driven in EV mode. Which motor torque is used is determined by the changeover switch 560. The changeover switch 560 is operated by a signal input from the mode selection switch 42.

2-2. Calculation of motor torque in MT mode The driving wheel torque in an MT vehicle is determined by the operation of the gas pedal that controls fuel supply to the engine, the operation of the shift lever (shift device) that changes the MT gear, and the difference between the engine and MT. This is determined by the operation of the clutch pedal that operates the clutch. If the electric vehicle 10 is equipped with an engine, a clutch, and an MT, the MT vehicle model 530 is a model that calculates the driving wheel torque obtained by operating the accelerator pedal 22, the pseudo clutch pedal 28, and the pseudo shift lever 26. It is. Hereinafter, in the MT mode, the engine, clutch, and MT virtually realized by the MT vehicle model 530 will be referred to as a virtual engine, a virtual clutch, and a virtual MT.

A signal from the accelerator position sensor 32 is input to the MT vehicle model 530 as the operation amount of the gas pedal of the virtual engine. A signal from the shift position sensor 36 is input as the shift position of the shift device of the virtual MT. Further, a signal from the clutch position sensor 38 is input as the operation amount of the clutch pedal of the virtual clutch. In addition, a signal from the wheel speed sensor 30 is also input to the MT vehicle model 530 as a signal indicating the load state of the vehicle. The MT vehicle model 530 is a model that simulates the torque characteristics of drive wheel torque in an MT vehicle. The MT vehicle model 530 is created so as to be reflected in the driving wheel torque values when the accelerator pedal 22, pseudo shift lever 26, and pseudo clutch pedal 28 are operated by the driver. Details of the MT vehicle model 530 will be described later.

The required motor torque calculation unit 540 converts the drive torque calculated by the MT vehicle model 530 into a required motor torque. The required motor torque is the motor torque required to realize the drive torque calculated by the MT vehicle model 530. The reduction ratio from the output shaft 3 of the electric motor 2 to the drive wheels 8 is used to convert the drive torque into the required motor torque. Further, a signal is input to the required motor torque calculation unit 540 from the zero start acceleration request determination unit 500. The details of the determination by the zero-start acceleration request determining section 500 and the processing of the required motor torque calculating section 540 that receives the determination result will be described later.

2-3. Calculation of Motor Torque in EV Mode FIG. 4 is a diagram showing an example of a motor torque command map 550 used to calculate motor torque in EV mode. The motor torque command map 550 is a map that determines the motor torque using the accelerator opening, Pap, and the rotational speed of the electric motor 2 as parameters. A signal from the accelerator position sensor 32 and a signal from the rotational speed sensor 40 are input to each parameter of the motor torque command map 550. Motor torque command map 550 outputs motor torque corresponding to these signals.

2-4. Switching Motor Torque The motor torque calculated using the motor torque command map 550 is expressed as Tev, and the motor torque calculated using the MT vehicle model 530 and the required motor torque calculation unit 540 is expressed as Tmt. The motor torque selected by the changeover switch 560 from the two motor torques Tev and Tmt is given to the electric motor 2 as a motor torque command value.

In the EV mode, even if the driver operates the pseudo shift lever 26 or the pseudo clutch pedal 28, the operation is not reflected in the operation of the electric vehicle 10. That is, in the EV mode, the operation of the pseudo shift lever 26 and the operation of the pseudo clutch pedal 28 are disabled. However, even while the motor torque Tev is being output as the motor torque command value, calculation of the motor torque Tmt using the MT vehicle model 530 continues. Conversely, calculation of the motor torque Tev continues even while the motor torque Tmt is being output as the motor torque command value. That is, both the motor torque Tev and the motor torque Tmt are continuously input to the changeover switch 560.

By switching the input using the changeover switch 560, the motor torque command value is switched from motor torque Tev to motor torque Tmt, or from motor torque Tmt to motor torque Tev. At this time, if there is a difference between the two motor torques, a torque step will occur due to switching. Therefore, for a while after switching, a gradual change process is performed on the motor torque command value so that a sudden change in torque does not occur. For example, when switching from EV mode to MT mode, the motor torque command value is not immediately switched from motor torque Tev to motor torque Tmt, but is changed toward motor torque Tmt at a predetermined rate of change. Similar processing is performed when switching from MT mode to EV mode.

The changeover switch 560 operates according to the driving mode selected by the mode selection switch 42. When the EV mode is selected by the mode selection switch 42, the changeover switch 560 is connected to the motor torque command map 550 and outputs the motor torque Tev input from the motor torque command map 550 as a motor torque command value. When the MT mode is selected by the mode selection switch 42, the changeover switch 560 switches the connection destination to the required motor torque calculation unit 540. Then, the changeover switch 560 outputs the motor torque Tmt input from the required motor torque calculation section 540 as a motor torque command value. Such input switching is performed in conjunction with selection of the row mode by the mode selection switch 42.

2-5. MT vehicle model 2-5-1. Overview Next, the MT vehicle model 530 will be explained. FIG. 5 is a block diagram showing an example of an MT vehicle model 530. The MT vehicle model 530 includes an engine model 531, a clutch model 532, an MT model 533, and an axle/drive wheel model 534. The engine model 531 models a virtual engine. In the clutch model 532, a virtual clutch is modeled. The MT model 533 is a model of a virtual MT. The axle/drive wheel model 534 models a virtual torque transmission system from the axle to the drive wheels. Each model may be represented by a calculation formula or a map.

Calculation results are input and output between each model. Furthermore, the accelerator opening degree Pap detected by the accelerator position sensor 32 is input to the engine model 531 . The clutch depression amount Pc detected by the clutch position sensor 38 is input to the clutch model 532. In the MT model, the shift position Sp detected by the shift position sensor is input to 533. Furthermore, in the MT vehicle model 530, the vehicle speed Vw (or wheel speed) detected by the wheel speed sensor 30 is used in a plurality of models. In the MT vehicle model 530, the driving wheel torque Tw and the virtual engine rotation speed Ne are calculated based on these input signals.

2-5-2. Engine Model The engine model 531 calculates virtual engine rotational speed Ne and virtual engine output torque Teout. The engine model 531 includes a model that calculates the virtual engine rotational speed Ne and a model that calculates the virtual engine output torque Teout. For example, a model expressed by the following equation (1) is used to calculate the virtual engine rotational speed Ne. In the following equation (1), a virtual engine rotation speed Ne is calculated from the rotation speed Nw of the wheels 8, the overall reduction ratio R, and the slip ratio slip of the clutch mechanism.

In equation (1), the rotational speed Nw of the wheel 8 is calculated from the wheel speed detected by the wheel speed sensor 30. The overall reduction ratio R is calculated from a gear ratio (speed ratio) r calculated by an MT model 533, which will be described later, and a reduction ratio defined by an axle/drive wheel model 534. The slip rate slip is calculated by a clutch model 532, which will be described later. The virtual engine rotation speed Ne is displayed on the pseudo engine rotation speed meter 44 when the MT mode is selected.

Note that while the MT vehicle is idling, idle speed control control (ISC control) is performed to maintain the engine rotation speed at a constant rotation speed. Therefore, when the vehicle speed is 0 and the accelerator opening Pap is 0%, the engine model 531 calculates the virtual engine rotation speed Ne as a predetermined idling rotation speed (for example, 1000 rpm).

Engine model 531 calculates virtual engine output torque Teout from virtual engine rotational speed Ne and accelerator opening Pap. For example, a two-dimensional map as shown in FIG. 6 is used to calculate the virtual engine output torque Teout. In this two-dimensional map, virtual engine output torque Teout for virtual engine rotational speed Ne is given for each accelerator opening Pap. The torque characteristics shown in FIG. 6 can be set to characteristics assuming a gasoline engine, or can be set to characteristics assuming a diesel engine. Furthermore, the characteristics can be set assuming a naturally aspirated engine, or the characteristics can be set assuming a supercharged engine. A switch for switching the virtual engine in MT mode may be provided so that the driver can switch to his or her preferred setting. The virtual engine output torque Teout calculated by the engine model 531 is output to the clutch model 532.

2-5-3. Clutch Model Clutch model 532 calculates torque transfer gain k. The torque transmission gain k is a gain for calculating the degree of torque transmission of the virtual clutch according to the amount of depression of the pseudo clutch pedal 28. The clutch model 532 has a map as shown in FIG. 7, for example. In this map, a torque transmission gain k is given to the clutch pedal depression amount Pc. In FIG. 7, the torque transmission gain k becomes 1 when the clutch pedal depression amount Pc ranges from Pc0 to Pc1, monotonically decreases with a constant slope to 0 when the clutch pedal depression amount Pc ranges from Pc1 to Pc2, and the torque transmission gain k becomes 1 when the clutch pedal depression amount Pc ranges from Pc1 to Pc2. Pc is given so that it becomes 0 in the range from Pc2 to Pc3. Here, Pc0 corresponds to the clutch pedal depression amount Pc of 0%, Pc1 corresponds to the play limit when the clutch pedal is depressed, Pc3 corresponds to the clutch pedal depression amount Pc of 100%, and Pc2 corresponds to the play between Pc3 and Pc3. It corresponds to the limits.

The map shown in FIG. 7 is an example, and the change curve of the torque transmission gain k with respect to the increase in the clutch pedal depression amount Pc is not limited as long as it is a broad monotonous decrease toward 0. For example, the change in torque transmission gain k from Pc1 to Pc2 may be a monotonically decreasing curve that is convex upward, or may be a monotonically decreasing curve that is convex downward.

Clutch model 532 calculates clutch output torque Tcout using torque transmission gain k. Clutch output torque Tcout is torque output from the virtual clutch. The clutch model 532 calculates the clutch output torque Tcout from the virtual engine output torque Teout and the torque transmission gain k using, for example, the following equation (2). The clutch output torque Tcout calculated by the clutch model 532 is output to the MT model 533.

2-5-4. MT Model The MT model 533 calculates the gear ratio (speed ratio) r. The gear ratio r is a gear ratio determined by the shift position Sp of the pseudo shift lever 26 in the virtual MT. The shift position Sp of the pseudo shift lever 26 and the gear stage of the virtual MT have a one-to-one relationship. The MT model 533 has a map as shown in FIG. 8, for example. In this map, a gear ratio r is given for each gear stage. As shown in FIG. 8, the gear ratio r becomes smaller as the gear stage becomes larger.

The MT model 533 calculates the transmission output torque Tgout using the gear ratio r. The transmission output torque Tgout is the torque output from the virtual transmission. The MT model 533 calculates the transmission output torque Tgout from the clutch output torque Tcout and the gear ratio r using, for example, the following equation (3). The transmission output torque Tgout calculated by the MT model 533 is output to the axle/drive wheel model 534.

2-5-5. Axle/Drive Wheel Model The axle/drive wheel model 534 calculates the drive wheel torque Tw using a predetermined reduction ratio rr. The reduction ratio rr is a fixed value determined by the mechanical structure from the virtual MT to the drive wheels 8. The axle/driving wheel model 534 calculates the driving wheel torque Tw from the transmission output torque Tgout and the reduction ratio rr, for example, using the following equation (4). The drive wheel torque Tw calculated by the axle/drive wheel model 534 is output to the required motor torque calculation unit 540.

2-6. Torque Characteristics of Electric Motor Realized in MT Mode The required motor torque calculation unit 540 converts the drive wheel torque Tw calculated by the MT vehicle model 530 into motor torque. FIG. 9 is a diagram showing the torque characteristics of the electric motor 2 realized in the MT driving mode in comparison with the torque characteristics of the electric motor 2 realized in the EV driving mode. In the case of the MT mode, as shown in FIG. 9, torque characteristics (solid line in the figure) that simulate the torque characteristics of an MT vehicle can be realized according to the gear stage set by the pseudo shift lever 26.

2-6. Zero start acceleration request determination 2-6-1. Overview Next, the zero start acceleration request determination by the zero start acceleration request determining section 500 will be explained. Zero start acceleration is acceleration from a stopped state. With automatic transmission vehicles and regular EVs, you can quickly accelerate by pressing the accelerator pedal. If a driver desires even greater acceleration, he or she can depress the accelerator pedal while pressing the brake pedal, and then release the brake pedal while applying torque to the drive wheels. However, in the case of MT vehicles, more complicated operations are required. In a manual transmission vehicle, it is necessary to press the accelerator pedal with the clutch pedal released, increase the engine speed to near the maximum torque, and then connect the clutch pedal, that is, perform a zero-start acceleration operation. Zero start acceleration operation is also required for zero start acceleration when electric vehicle 10 is driven in MT mode.

Zero start acceleration request determination unit 500 determines that the driver requests zero start acceleration when a zero start acceleration operation is performed in the MT mode. The driver's zero start acceleration operation can be detected from the virtual engine rotational speed Ne when the vehicle is stopped and the depression amount Pc of the pseudo clutch pedal. Zero start acceleration request determination section 500 outputs a torque up instruction signal to requested motor torque calculation section 540 when a zero start acceleration request is detected. Upon receiving the torque-up instruction signal, the required motor torque calculation unit 540 increases the motor torque at the time of starting to be higher than the motor torque at the time of normal starting in the MT mode.

2-6-2. Procedure for Determining Zero Start Acceleration Request FIG. 10 is a flowchart showing the procedure for zero start acceleration control including determining the zero start acceleration request. In step S101, it is determined whether the current driving mode is the MT mode. If the current driving mode is EV mode, subsequent processing is skipped. In addition, in the case of EV mode, acceleration with large torque unique to EV mode is possible.

If the current driving mode is the MT mode, it is determined in step S102 whether the vehicle is stopped. When the vehicle speed detected by the wheel speed sensor 30 is zero, it is determined that the vehicle is stopped. If the vehicle speed is not zero, the starting acceleration will not be zero, and the subsequent processing will be skipped.

If the vehicle is stopped, it is determined in step S103 whether the virtual engine rotation speed Ne is equal to or higher than a predetermined rotation speed Nes. The predetermined rotational speed Nes is a rotational speed at which the virtual engine output torque Teout falls within a predetermined range that includes the maximum torque. If the virtual engine rotational speed Ne is less than the predetermined rotational speed Nes, it is unclear whether the driver intends to perform zero start acceleration, and the subsequent processing is skipped.

When the virtual engine rotational speed Ne becomes equal to or higher than the predetermined rotational speed Nes, it is determined in step S104 whether the depression amount Pc of the pseudo clutch pedal has been returned to a predetermined value Pcs or less. The predetermined value Pcs is the amount of depression when the virtual clutch is engaged. If the clutch pedal depression amount Pc is larger than the predetermined value Pcs, it is unclear whether the driver intends to perform zero-start acceleration, and the subsequent processing is skipped.

When the depression amount Pc of the pseudo clutch pedal becomes equal to or less than the predetermined value Pcs, in step S105, the torque is increased for zero start acceleration. As a result, sufficient driving force can be obtained at the time of starting, and the driver can easily enjoy zero starting acceleration like a manual transmission vehicle.

In step S106, it is determined whether the vehicle has started. If the vehicle has not started, subsequent processing is skipped.

When the vehicle starts moving, it is determined in step S107 whether or not the drive wheels 8 are slipping. Slip can be detected from the speed difference that occurs between the wheel speed of the driving wheels 8 and the wheel speed of the driven wheels 12. If no slip has occurred, the next process is skipped.

If slip occurs in the drive wheels 8, the process of step S108 is executed. In step S108, torque down control is executed to reduce the motor torque. Torque down control uses TRC (Traction Control), a function that ensures traction on slippery or rough roads. This suppresses the slip of the drive wheels 8 and enables stable starting.

2-6-3. Method of increasing torque for zero start acceleration FIG. 11 is a diagram showing a first method of increasing torque for zero start acceleration. In the first method, the torque of the electric motor 2 is made larger than when starting normally. Specifically, in the MT mode, a torque curve is determined for each gear stage, and the motor torque is determined along the torque curve. As can be seen from the torque curve in 1st gear, the motor torque obtained when starting in 1st gear in normal MT mode is not large. Therefore, when a torque up instruction signal is input from the zero start acceleration request determination section 500 to the required motor torque calculation section 540, the required motor torque calculation section 540 cancels the current restriction and increases the motor torque to the maximum torque. This allows the electric motor 2 to output a large torque equivalent to that in the EV mode, so even a driver accustomed to EVs can enjoy zero-start acceleration without feeling any discomfort.

FIG. 12 is a diagram showing a second method of increasing torque for zero start acceleration. In the second method, a torque up instruction signal is input from zero start acceleration request determination section 500 to MT vehicle model 530. In the MT vehicle model 530, when the torque up instruction signal is input, the torque transmission gain k in the clutch model 532 is made larger than that at the time of normal start. Specifically, when the depression amount Pc of the pseudo clutch pedal is returned to a predetermined value Pcs or less and the virtual clutch is engaged, the torque transmission gain k is increased compared to normal. This results in an increase in the torque of the electric motor 2 at the time of starting, so that, similarly to the first method, the driver can enjoy zero starting acceleration without feeling any discomfort.

3. Others The electric vehicle 10 according to the embodiment described above is an FF vehicle that drives the front wheels with one electric motor 2. However, the present invention can also be applied to an electric vehicle in which two electric motors are arranged at the front and the rear to drive the front wheels and the rear wheels, respectively. Further, the present invention can also be applied to an electric vehicle that includes an in-wheel motor in each wheel. As the MT vehicle model in these cases, a model of an all-wheel drive vehicle with MT can be used.

The electric vehicle 10 according to the embodiment described above does not include a transmission. However, the present invention is also applicable to electric vehicles equipped with stepped or continuously variable automatic transmissions. In this case, the power train consisting of the electric motor and automatic transmission may be controlled so as to output the motor torque calculated using the MT vehicle model.

2 Electric motor 8 Drive wheel 10 Electric vehicle 16 Inverter 26 Pseudo shift lever (pseudo shift device)
28 Pseudo clutch pedal 30 Wheel speed sensor 40 Rotation speed sensor 42 Mode selection switch 44 Pseudo engine rotation speed meter 50 Control device 500 Zero start acceleration request determination section 520 Control signal calculation section 530 MT vehicle model 540 Requested motor torque calculation section 550 Motor torque Command map 560 changeover switch

Claims (3)

An electric vehicle that uses an electric motor as a driving power device,
accelerator pedal and
pseudo clutch pedal,
a memory storing a clutch model in which a relationship between a depression amount of the pseudo clutch pedal and a torque transmission gain is defined;
a processor that determines a motor torque to be outputted to the electric motor based on the amount of depression of the accelerator pedal and the torque transmission gain;
The electric vehicle is characterized in that the clutch model is configured to vary the relationship between the amount of depression of the pseudo clutch pedal and the clutch transmission gain. The electric vehicle according to claim 1,
The electric vehicle is characterized in that the clutch model is configured to change the relationship between the depression amount of the pseudo clutch pedal and the clutch transmission gain under predetermined conditions from the relationship at the time of normal start. The electric vehicle according to claim 2,
The electric vehicle is characterized in that the clutch model is configured to make the clutch transmission gain larger than when starting normally when a zero start acceleration request is detected.

Images