electric vehicles

Abstract

To optimize torque change characteristics in response to operation of a pseudo clutch pedal or an indicator equivalent thereto in an electric vehicle according to the situation. [Solution] A vehicle according to an embodiment of the present disclosure has an electric motor as a drive source and is equipped with an accelerator pedal and a pseudo clutch pedal. A vehicle control device controls the torque output by the electric motor in response to the driver's operation of the accelerator pedal and the pseudo clutch pedal. The control device switches the torque change characteristic relative to the pseudo clutch pedal operation amount based on the vehicle speed. When the vehicle speed is equal to or greater than a predetermined speed, a characteristic CHARC1 is used, which causes the torque change relative to the pseudo clutch pedal operation amount to be upwardly convex. When the vehicle speed is less than the predetermined speed, a characteristic CHARC2 is used, which causes the torque change relative to the pseudo clutch pedal operation amount to be downwardly convex or linear.

Description

[Technical Field]

[0001] The present disclosure relates to an electric vehicle having an electric motor as a drive source. [Background technology]

[0002] Japanese Patent Application Laid-Open Publication No. 2024-038489 discloses a conventional electric vehicle that can simulate the operation of a manually-shifted internal combustion engine vehicle driven by an internal combustion engine by controlling an electric motor. The electric vehicle according to the conventional technology is equipped with a pseudo clutch pedal that imitates the clutch pedal of a manually-shifted internal combustion engine vehicle, in addition to an accelerator pedal. By operating the pseudo clutch pedal with the left foot while operating the accelerator pedal with the right foot, the driver can achieve delicate torque control that is not possible with a normal electric vehicle that only has an accelerator pedal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2024-038489 Summary of the Invention [Problem to be solved by the invention]

[0004] In the case of a manual transmission internal combustion engine vehicle, the torque change characteristics in response to clutch pedal operation are mechanically determined by the pedal stroke-torque capacity characteristics of the clutch mechanism. On the other hand, when the operation of a manual transmission internal combustion engine vehicle is simulated by controlling an electric motor, the torque change characteristics in response to pseudo clutch pedal operation can be arbitrarily determined by programming the control device. While it is possible to program the system to exactly replicate the pedal stroke-torque capacity characteristics of a manual transmission internal combustion engine vehicle, the mechanically determined characteristics are not always optimal for a manual transmission internal combustion engine vehicle.

[0005] One object of the present disclosure is to enable the torque change characteristics in response to the operation of a pseudo clutch pedal or an indicator equivalent thereto to be optimized according to the situation in an electric vehicle having an electric motor as a drive source. [Means for solving the problem]

[0006] The present disclosure provides an electric vehicle to achieve the above-mentioned object. According to one aspect of the present disclosure, the electric vehicle has an electric motor as a drive source, and includes a control device that controls the torque output by the electric motor and two indicators that issue instructions to the control device. A first of the two indicators issues continuous instructions to the control device in accordance with an operation amount. A second of the two indicators issues continuous instructions to the control device in accordance with an operation amount that can be operated simultaneously with the first indicator. When the second indicator is not operated, the control device causes the electric motor to output a base torque that corresponds to the operation amount of the first indicator and the vehicle speed, and when the operation amount of the second indicator is equal to or greater than the first operation amount, causes the electric motor to output a predetermined minimum torque. Furthermore, when the operation amount of the second indicator is smaller than the first operation amount, the control device increases the torque output by the electric motor from the minimum torque to the base torque in accordance with a decrease in the operation amount of the second indicator.

[0007] The control device switches the torque change characteristic with respect to the operation amount of the second indicator based on the vehicle speed when the operation amount of the second indicator is reduced below the first operation amount. The torque change characteristic with respect to the operation amount of the second indicator switched by the control device includes a high-speed characteristic that is selected when the vehicle speed is equal to or greater than a predetermined speed, and a low-speed characteristic that is selected when the vehicle speed is less than the predetermined speed. The high-speed characteristic is a characteristic in which there is an upward convex section in the torque change with respect to the change in the operation amount of the second indicator as the torque output by the electric motor increases from the minimum torque to the base torque. The low-speed characteristic is a characteristic in which the change in the torque output by the electric motor as it increases from the minimum torque to the base torque is downward convex or more linear than the high-speed characteristic with respect to the change in the operation amount of the second indicator. [Effects of the Invention]

[0008] According to the electric vehicle of the present disclosure, the torque change characteristics in response to the amount of operation of the second indicator are switched depending on whether the vehicle speed is above or below a predetermined speed. According to the high-speed characteristics selected when the vehicle speed is above the predetermined speed, a section in which the torque change in response to the amount of operation of the second indicator becomes convex upward as the torque output by the electric motor increases from minimum torque to base torque appears. This characteristic allows the driver to feel a direct sense of operation due to the quick torque rise. On the other hand, according to the low-speed characteristics selected when the vehicle speed is below the predetermined speed, the torque change in response to the amount of operation of the second indicator becomes convex downward as the torque output by the electric motor increases from minimum torque to base torque, or becomes more linear compared to the high-speed characteristics. According to this characteristic, excessive acceleration changes due to sudden changes in torque transmission at low speeds can be suppressed. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing a configuration of an electric vehicle according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is a diagram showing a vehicle model used in the control device of the electric vehicle shown in FIG. [Figure 3] FIG. 4 is a diagram showing an example of clutch pedal stroke-clutch capacity characteristics of a clutch model constituting a vehicle model. [Figure 4] FIG. 10 is a diagram showing an example of setting a clutch pedal stroke-clutch capacity characteristic. [Figure 5] FIG. 10 is a diagram showing a flow of selection of clutch pedal stroke-clutch capacity characteristics by the control device. [Figure 6] FIG. 10 is a diagram showing an example of switching of clutch pedal stroke-clutch capacity characteristics in a situation where an upshift is performed after starting, and the results of vehicle control realized thereby. [Figure 7] FIG. 10 is a diagram showing another example of switching of the clutch pedal stroke-clutch capacity characteristics in a situation where an upshift is performed after starting. [Figure 8]FIG. 10 is a diagram showing an example of switching of clutch pedal stroke-clutch capacity characteristics in a situation where a downshift is performed after an upshift, and the results of vehicle control realized thereby. [Figure 9] FIG. 4 is a diagram showing the configuration of an electric vehicle according to a second embodiment of the present disclosure. [Figure 10] FIG. 10 is a diagram showing a vehicle model used in the control device for the electric vehicle shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] 1. First embodiment 1-1. Vehicle power system configuration 1 is a diagram schematically illustrating the configuration of a vehicle 100 according to a first embodiment of the present disclosure. First, the configuration of the power system of the vehicle 100 will be described with reference to FIG.

[0011] The vehicle 100 is equipped with an electric motor (M) 6 as a driving source for traveling. The vehicle 100 also has a battery (BATT) 2 and an inverter (INV) 4. The battery 2 stores electric energy for driving the electric motor 6. In other words, the vehicle 100 is a battery electric vehicle (BEV) that runs on the electric energy stored in the battery 2. The electric motor 6 is, for example, a three-phase AC motor. The inverter 4 is, for example, a voltage-type inverter, and controls the torque of the electric motor 6 by PWM control.

[0012] The output shaft of the electric motor 6 is connected to a reduction gear (RG) 8. The reduction gear 8 is connected to a differential gear 14 by a propeller shaft 12. The differential gear 14 is connected to left and right drive wheels 18 by left and right drive shafts 16. The drive wheels 18 may be rear wheels or front wheels. However, the vehicle 100 may be configured as an all-wheel drive vehicle. In that case, a center differential gear may be provided on the propeller shaft 12, and the drive torque divided by the center differential gear may be transmitted to the front wheels and the rear wheels, respectively.

[0013] 1-2. Vehicle control system configuration Next, the configuration of the control system of the vehicle 100 will be described with reference to FIG.

[0014] The vehicle 100 is equipped with a vehicle speed sensor 40. The vehicle speed sensor 40 is a sensor that outputs a signal corresponding to the traveling speed (hereinafter referred to as vehicle speed) of the vehicle 100. At least one of wheel speed sensors (not shown) provided on each of the left and right front wheels and the left and right rear wheels is used as the vehicle speed sensor 40.

[0015] Vehicle 100 also includes accelerator position sensor 42. Accelerator position sensor 42 is provided on accelerator pedal 52 and outputs a signal corresponding to the amount of operation of accelerator pedal 52. The amount of operation of accelerator pedal 52 refers to the amount of depression of accelerator pedal 52 by the driver, i.e., the accelerator opening.

[0016] The accelerator pedal 52 is a driving operation member used to drive the vehicle 100. In addition to the accelerator pedal 52, the driving operation members also include a brake pedal (not shown). In addition to these driving operation members, the vehicle 100 is equipped with pseudo gearshift operation members that imitate operation members used to change gears in a manually variable transmission internal combustion engine vehicle. The pseudo gearshift operation members include a pseudo clutch pedal 54 and a pseudo shifter 56, which will be described below.

[0017] The pseudo clutch pedal 54 is a dummy that is different from an actual clutch pedal. The pseudo clutch pedal 54 has a structure similar to that of a clutch pedal provided in a conventional manual transmission internal combustion engine vehicle. For example, the pseudo clutch pedal 54 is equipped with a reaction force mechanism that generates a reaction force when the driver presses down on the pedal. The position when no pressure is applied to the pseudo clutch pedal 54 is the start position of the pseudo clutch pedal 54, and the position when the pseudo clutch pedal is pressed down to the farthest point is the end position of the pseudo clutch pedal 54. The driver can operate the pseudo clutch pedal 54 from the start position to the end position against the reaction force from the reaction force mechanism.

[0018] Vehicle 100 is equipped with clutch position sensor 44. Clutch position sensor 44 is provided on pseudo clutch pedal 54 and is a sensor that outputs a signal corresponding to the amount of operation of pseudo clutch pedal 54. The amount of operation of pseudo clutch pedal 54 means the amount of depression of pseudo clutch pedal 54 by the driver, i.e., the clutch pedal stroke.

[0019] The pseudo shifter 56 is a dummy that is different from an actual shifter. The pseudo shifter 56 has a structure that resembles an H-shaped shifter equipped in a conventional manual transmission internal combustion engine vehicle. The pseudo shifter 56 has a shift lever that can be moved along an H-shaped gate. A shift position is assigned to each gate. However, since the vehicle 100 does not have an actual transmission, the shift positions of the pseudo shifter 56 are virtual shift positions. In the example shown in FIG. 1, first, second, third, fourth, fifth, and sixth gears are provided as virtual shift positions. In a conventional manual transmission internal combustion engine vehicle, first gear is the shift position with the largest gear ratio, followed by second, third, fourth, fifth, and sixth gears, in that order.

[0020] The vehicle 100 is equipped with a shift position sensor 46. The shift position sensor 46 is provided in the pseudo shifter 56 and outputs a signal indicating the shift position selected by the pseudo shifter 56. When the shift lever is not in any shift position, the shift position sensor 46 outputs a signal indicating the neutral position.

[0021] The vehicle 100 is equipped with a control device 101. Sensors and devices to be controlled mounted on the vehicle 100 are connected to the control device 101 via an in-vehicle network. A vehicle speed sensor 40, an accelerator position sensor 42, a clutch position sensor 44, and a shift position sensor 46 are examples of sensors mounted on the vehicle 100. Signals from these sensors 40, 42, 44, and 46 are input to the control device 101.

[0022] The control device 101 is typically an electronic control unit (ECU). The control device 101 may be a combination of multiple ECUs. The control device 101 includes an interface, memory, and processor (not shown). An in-vehicle network is connected to the interface. The memory includes a RAM for temporarily recording data and a ROM for storing programs executable by the processor and various data related to the programs. The programs are made up of multiple instructions. The processor reads and executes the programs and data from the memory, and generates control signals based on signals acquired from each sensor. The control device 101 may include one or more processors. The one or more processors form a processing circuit.

[0023] 1-3.Control device functions The programs stored in the memory of the control device 101 include a program for enabling the vehicle 100 to be operated like a manually-shiftable internal combustion engine vehicle. A vehicle model that models a manually-shiftable internal combustion engine vehicle is implemented in the program. When the program is executed, the processor or processors of the control device 101 function as a virtual gear ratio calculation unit 111, a virtual clutch capacity calculation unit 112, a virtual engine speed calculation unit 113, a virtual engine torque calculation unit 114, a virtual transmission torque calculation unit 115, and a pseudo-engine sound generation unit 116.

[0024] The virtual gear ratio calculation unit 111 acquires a signal from the shift position sensor 46. A virtual shift position of the pseudo shifter 58 is obtained from the signal from the shift position sensor 46. The virtual gear ratio calculation unit 111 calculates a virtual gear ratio of the vehicle 100 based on the virtual shift position using a transmission model (described later) that constitutes the vehicle model. The virtual gear ratio is the gear ratio of a transmission (hereinafter referred to as a virtual transmission) that is virtually realized by torque control of the electric motor 6 using the vehicle model.

[0025] The virtual clutch capacity calculation unit 112 acquires a signal from the clutch position sensor 44. The clutch pedal stroke of the pseudo clutch pedal 54 is obtained from the signal from the clutch position sensor 44. The virtual clutch capacity calculation unit 112 calculates a virtual clutch capacity based on the clutch pedal stroke using a clutch model (described later) that constitutes a vehicle model. The virtual clutch capacity is the torque transmission capacity of a clutch (hereinafter referred to as a virtual clutch) that is virtually realized by torque control of the electric motor 6 using the vehicle model.

[0026] The virtual engine speed calculation unit 113 acquires a signal from the vehicle speed sensor 40. The vehicle speed of the vehicle 100 is obtained from the signal from the vehicle speed sensor 40. The virtual engine speed calculation unit 113 calculates a virtual engine speed based on the vehicle speed and the virtual gear ratio according to a predetermined calculation formula. The virtual engine speed is the rotation speed of an engine (hereinafter referred to as a virtual engine) that is virtually realized by torque control of the electric motor 6 using a vehicle model. When the virtual clutch is in a half-engaged state, the virtual engine speed is calculated using the vehicle speed, the virtual gear ratio, and the virtual slip ratio. The virtual slip ratio is calculated using the virtual clutch capacity and a virtual engine torque, which will be described later.

[0027] The virtual engine torque calculation unit 114 acquires a signal from the accelerator position sensor 42. The accelerator opening of the accelerator pedal 52 is obtained from the signal from the accelerator position sensor 42. The virtual engine torque calculation unit 114 calculates a virtual engine torque based on the virtual engine speed and the accelerator opening using an engine model (described later) that constitutes a vehicle model. The virtual engine torque is the torque output from the virtual engine.

[0028] The virtual transmission torque calculation unit 115 calculates the virtual transmission torque using the virtual engine torque, the virtual clutch capacity, and the virtual gear ratio. The virtual transmission torque is the torque output from the virtual transmission. The virtual transmission torque is the product of the virtual clutch torque input from the virtual clutch and the gear ratio, and the virtual clutch torque is the smaller of the virtual engine torque and the virtual clutch capacity. In other words, if the virtual engine torque is smaller than the virtual clutch capacity, the virtual clutch torque is equal to the virtual engine torque. On the other hand, if the virtual engine torque is larger than the virtual clutch capacity, the virtual clutch torque is limited to the virtual clutch capacity.

[0029] The control device 101 controls the inverter 4 so that the torque output by the electric motor 6 changes in accordance with the virtual transmission torque. The virtual transmission torque changes discontinuously in accordance with the switching of the virtual gear ratio. This discontinuous change in the virtual transmission torque changes the behavior of the vehicle 100, creating the appearance of a vehicle equipped with a stepped transmission.

[0030] The virtual engine speed and virtual engine torque are input to a display device 30 provided on the instrument panel of the vehicle 100. The display device 30 displays a pseudo engine speed meter, a pseudo engine torque meter, and a pseudo engine power meter. These meters may be analog or digital meters. The pseudo engine speed meter displays the virtual engine speed. The pseudo engine torque meter displays the virtual engine torque. The pseudo engine power meter displays the virtual engine power calculated from the virtual engine speed and virtual engine torque. The contents of these meters change depending on the driver's operation of the accelerator pedal 52, and also change depending on the operation of the pseudo clutch pedal 54 and the pseudo shifter 56. By watching the meters change in this way, the driver visually gets the feeling that he or she is driving a manually-shifted internal combustion engine vehicle.

[0031] The pseudo engine sound generation unit 116 generates a pseudo engine sound to be output from the speaker 32 installed in the passenger compartment of the vehicle 100. The pseudo engine sound generation unit 116 calculates the sound pressure of the pseudo engine sound using a sound pressure map and calculates the frequency of the pseudo engine sound using a frequency map. In the sound pressure map, sound pressure data is set with respect to the virtual engine speed so that the sound pressure increases as the virtual engine speed increases. Also, sound pressure data is set with respect to the virtual engine torque so that the sound pressure increases as the virtual engine torque increases. In the frequency map, frequency data is set with respect to the virtual engine speed so that the frequency increases as the virtual engine speed increases. Therefore, the sound pressure and frequency of the pseudo engine sound emitted from the speaker change depending on the driver's operation of the accelerator pedal 52, and also change depending on the operation of the pseudo clutch pedal 54 and the pseudo shifter 56. By listening to the pseudo engine sound whose sound pressure and frequency change in this way, the driver auditorily acquires the sensation of driving a manually-shifted internal combustion engine vehicle.

[0032] The vehicle model used by the control device 101 will now be described with reference to Fig. 2. As shown in Fig. 2, the vehicle model MOD01 is composed of a transmission model MOD11, an engine model MOD12, and a clutch model MOD13. The transmission model MOD11 models a virtual transmission. The engine model MOD12 models a virtual engine. And the clutch model MOD13 models a virtual clutch.

[0033] The engine model MOD12 defines the relationship between the virtual engine speed and the virtual engine torque for each throttle position. The torque characteristics of the engine model MOD12 can be set to those assumed for a gasoline engine or a diesel engine. Furthermore, the engine model MOD12 can be set to those assumed for a naturally aspirated engine or a supercharged engine. The virtual engine torque Te calculated by the engine model MOD12 is input to the clutch model MOD13. When the virtual engine speed drops below a predetermined engine stall speed, the virtual engine torque fluctuates for a very short period of time and then becomes zero, and the virtual engine speed is also reduced to zero.

[0034] In the clutch model MOD13, a virtual clutch capacity is assigned to the clutch pedal stroke. The clutch pedal stroke is 0% at the start position of the pseudo clutch pedal 54 and 100% at the end position of the pseudo clutch pedal 54. When the clutch pedal stroke is 100%, the virtual clutch capacity is zero. At this time, the virtual clutch is completely released in the clutch model MOD13, and the transmission of virtual engine torque from the virtual engine to the virtual transmission is cut off. When the clutch pedal stroke is returned from the 100% state, the state of the virtual clutch changes from the released state to the partially engaged state at a predetermined position (this position is called the clutch meet point). This causes the virtual clutch capacity to begin to increase, and accordingly, the transmission of virtual engine torque from the virtual engine to the virtual transmission begins. Then, when the virtual clutch capacity becomes equal to or greater than the virtual engine torque, the virtual clutch is engaged, and all of the virtual engine torque output from the virtual engine is input to the virtual transmission.

[0035] In the transmission model MOD11, a virtual gear ratio is set for each virtual shift position. The maximum virtual gear ratio is set for first gear, and the virtual gear ratios decrease in the order of second gear, third gear, fourth gear, fifth gear, and sixth gear. A virtual transmission torque Tp is calculated using the virtual gear ratio calculated by the transmission model MOD11 and the virtual clutch torque Tout input from the clutch model MOD13.

[0036] With the vehicle model MOD01 configured in this manner, the virtual transmission torque Tp changes in response to the accelerator pedal position and the clutch pedal stroke. When the clutch pedal stroke is equal to or greater than the clutch meet point where the virtual clutch changes from a released state to a partially engaged state, the virtual transmission torque Tp is at its minimum. This minimum torque may be set to zero, or may be set to a value greater than zero, like the creep torque of an automatic transmission. When the clutch pedal stroke becomes smaller than the clutch meet point, the virtual transmission torque Tp increases from the minimum torque to the virtual engine torque Te as the clutch pedal stroke decreases.

[0037] 1-4.Details of the clutch model In an actual clutch installed in a manual transmission internal combustion engine vehicle, the clutch capacity is mechanically determined by factors such as spring force, disc diameter, number of discs, and friction coefficient. The clutch pedal stroke is also mechanically determined by the distance between the discs. Therefore, in an actual clutch, the characteristics of the change in clutch capacity relative to changes in clutch pedal stroke are also mechanically determined, and these characteristics are essentially constant except for changes over time due to use.

[0038] Meanwhile, with the virtual clutch realized by the above-described clutch model MOD13, the clutch pedal stroke-clutch capacity characteristics can also be made variable by programming the clutch model MOD13. One advantage of using the clutch model MOD13 to calculate the torque output from the electric motor 6 is that the clutch pedal stroke-clutch capacity characteristics can be optimized to suit various situations requiring clutch operation.

[0039] FIG. 3 shows an example of the clutch pedal stroke-clutch capacity characteristics (hereinafter simply referred to as clutch capacity characteristics) set by the clutch model MOD13. In this example, a first high-speed characteristic CHARC1, a low-speed characteristic CHARC2, and a second high-speed characteristic CHARC3 are set as clutch capacity characteristics in the clutch model MOD13. In each of the characteristics CHARC1, CHARC2, and CHARC3, the virtual clutch switches from a released state to a partially engaged state at point S1, which is the clutch meet point. In each of the characteristics CHARC1, CHARC2, and CHARC3, the virtual clutch reaches the upper limit value C_UL of the virtual clutch capacity at point S2, which is the fully engaged point. Point S1 may be referred to as the first operation amount of the pseudo clutch pedal 54, and point S2 may be referred to as the second operation amount of the pseudo clutch pedal 54.

[0040] The clutch model MOD13 switches between three characteristics CHARC1, CHARC2, and CHARC3 depending on the situation. The first high-speed characteristic CHARC1 and the second high-speed characteristic CHARC3 are clutch capacity characteristics that are selected when the vehicle speed is equal to or greater than a predetermined speed. The low-speed characteristic CHARC2 is a clutch capacity characteristic that is selected when the vehicle speed is less than a predetermined speed. The predetermined speed that serves as the basis for switching is a speed used to determine whether the vehicle 100 is starting, and is set to, for example, 5 km / h. The determination of whether to switch the clutch capacity characteristics is based on the vehicle speed at the time the pseudo clutch pedal 54 is operated. Therefore, while the pseudo clutch pedal 54 is operated, the clutch capacity characteristics are not switched even if the vehicle speed changes from less than the predetermined speed to greater than the predetermined speed or from greater than the predetermined speed to less than the predetermined speed.

[0041] Of the first high-speed characteristic CHARC1 and the second high-speed characteristic CHARC3, the clutch capacity characteristic that is basically selected when the vehicle speed is equal to or higher than a predetermined speed is the first high-speed characteristic CHARC1. The second high-speed characteristic CHARC3 is selected only when the pseudo shifter 56 is operated while the pseudo clutch pedal 54 is being operated and the operation is a downshift. When the pseudo shifter 56 is not operated or when the operation of the pseudo shifter 56 is an upshift, the first high-speed characteristic CHARC1, which is the basic clutch capacity characteristic, is selected.

[0042] The three characteristics CHARC1, CHARC2, and CHARC3 differ in the manner in which the virtual clutch capacity changes in response to changes in clutch pedal stroke in the section from point S1 to point S2. The first high-speed characteristic CHARC1 is a characteristic in which there is a section in which the change in virtual clutch capacity in response to changes in clutch pedal stroke becomes convex upward as the clutch pedal stroke changes from point S1 to point S2. In the example shown in Figure 3, the characteristic is such that the change in virtual clutch capacity in response to changes in clutch pedal stroke becomes convex upward from point S11, which is slightly on the engagement side of point S1, to point S2.

[0043] The low-speed characteristic CHARC1 is a characteristic in which the virtual clutch capacity changes from the minimum value of zero to the upper limit value C_UL in a downward convex manner or more linearly than the first high-speed characteristic CHARC1 as the clutch pedal stroke changes from point S1 to point S2. In the example shown in Figure 3, the virtual clutch capacity changes in a downward convex manner with respect to the change in clutch pedal stroke from point S11 to point S2. However, the change in virtual clutch capacity from point S1 to point S11 in the low-speed characteristic CHARC1 is the same as that in the first high-speed characteristic CHARC1.

[0044] The second high-speed characteristic CHARC3 is a characteristic in which the rate of change of virtual clutch capacity with respect to clutch pedal stroke when the clutch pedal stroke is reduced from point S1 is lower than the rate of change in the first high-speed characteristic CHARC1. In the example shown in Figure 3, the change in virtual clutch capacity with respect to the change in clutch pedal stroke from point S11 to point S2 is more linear than in the first high-speed characteristic CHARC1. However, the change in virtual clutch capacity from point S1 to point S11 in the second high-speed characteristic CHARC3 is the same as that in the first high-speed characteristic CHARC1.

[0045] Switching the clutch capacity characteristics of the clutch model MOD13 as described above is equivalent to switching the change characteristics of the torque output by the electric motor 6 relative to the clutch pedal stroke. In the example shown in Figure 3, the section from point S1 to point S12 is the section during the initial engagement of the virtual clutch, and corresponds to the section during which the torque output by the electric motor 6 rises. The change characteristics of the torque relative to the clutch pedal stroke in this section have a particularly large impact on the driving feel.

[0046] When the first high-speed characteristic CHARC1 is selected, the virtual clutch exhibits a quick engagement response in response to the release operation of the pseudo clutch pedal 54. This allows the driver to feel a direct sensation in response to the operation due to the quick torque buildup. Furthermore, when the pseudo clutch pedal 54 is operated in conjunction with the shift operation of the pseudo shifter 56, the driver can enjoy a smooth gear change.

[0047] When the low-speed characteristic CHARC2 is selected, the virtual clutch exhibits a slow engagement response to the release operation of the virtual clutch pedal 54. This suppresses the rise in torque in response to the operation of the virtual clutch pedal 54, making it easier for the driver to half-engage the clutch when starting off. Furthermore, because the half-engagement operation is easier, it is possible to prevent the occurrence of a pseudo engine stall caused by the virtual engine speed dropping below the engine stall speed.

[0048] When the second high-speed characteristic CHARC3 is selected, the virtual clutch exhibits a slower engagement response to the release operation of the pseudo clutch pedal 54 than when the first high-speed characteristic CHARC1 is selected. When the virtual transmission downshifts by operating the pseudo shifter 56, the virtual engine speed increases. However, by suppressing the engagement response of the virtual clutch to the operation of the pseudo clutch pedal 54, the rate at which the virtual engine speed increases is also suppressed, making it possible to mitigate surge shock associated with engine braking.

[0049] The clutch model MOD13 can be programmed to set clutch capacity characteristics other than those shown in Figure 3. Figures 4A, 4B, and 4C show examples of clutch capacity characteristic settings. The low-speed characteristic CHARC2 and the second high-speed characteristic CHARC3 are common to all examples. With the low-speed characteristic CHARC2, the virtual clutch capacity changes in a downward convex curve from zero to the upper limit C_UL as the clutch pedal stroke changes from point S1 to point S2. With the second high-speed characteristic CHARC3, the virtual clutch capacity changes linearly from zero to the upper limit C_UL as the clutch pedal stroke changes from point S1 to point S2.

[0050] According to the first high-speed characteristic CHARC1 shown in FIG. 4A, as the clutch pedal stroke changes from point S1 to point S2, the virtual clutch capacity changes from zero to the upper limit value C_UL in a downward convex shape, and then changes upward in a convex shape. According to the first high-speed characteristic CHARC1 shown in FIG. 4B, as the clutch pedal stroke changes from point S1 to point S2, the virtual clutch capacity changes overall in an upward convex shape from zero to the upper limit value C_UL. According to the first high-speed characteristic CHARC1 shown in FIG. 4C, as the clutch pedal stroke changes from point S1 to point S2, the virtual clutch capacity changes from zero to the upper limit value C_UL in an upward convex shape, and then changes downward in a convex shape. With any of the settings shown in FIGS. 4A-4C, torque can be quickly generated in response to operation of the pseudo clutch pedal 54.

[0051] 1-5. Vehicle control using a clutch model Next, vehicle control using the above-mentioned clutch model MOD13 will be described. The control device 101 selects one of the three characteristics CHARC1, CHARC2, and CHARC3 of the clutch model MOD13 according to the selection flow shown in FIG. 5. First, the control device 101 selects either the first high-speed characteristic CHARC1 or the low-speed characteristic CHARC2 based on the vehicle speed at the start of the selection flow. The selection flow starts when the vehicle 100 is switched from an EV mode, in which the vehicle 100 is controlled as a normal electric vehicle, to an MT mode, in which the vehicle 100 is controlled to simulate a manually-shifted internal combustion engine vehicle. For example, if the vehicle 100 is switched from the EV mode to the MT mode while the vehicle 100 is stopped, the low-speed characteristic CHARC2 is selected as the clutch capacity characteristic. If the vehicle 100 is switched from the EV mode to the MT mode while traveling at a speed of 5 km / h or more, the first high-speed characteristic CHARC1 is selected as the clutch capacity characteristic.

[0052] After the selection flow starts, in step S01, it is determined whether the clutch pedal stroke is 0 mm, i.e., whether the pseudo clutch pedal 54 is being operated. If the pseudo clutch pedal 54 is not being operated, step S02 is executed. If the pseudo clutch pedal 54 is being operated, step S05 is executed.

[0053] In step S02, it is determined whether the vehicle speed is less than 5 km / h. If the vehicle speed is less than 5 km / h, step S03 is executed to select the low speed characteristic CHARC2. If the vehicle speed is 5 km / h or more, step S04 is executed to select the first high speed characteristic CHARC1.

[0054] In step S05, it is determined whether a downshift of the virtual transmission has been performed by operating the pseudo shifter 56. If a downshift has been performed, step S06 is executed to select the second high-speed characteristic CHARC3. If a downshift has not been performed, step S07 is executed to maintain the currently selected clutch capacity characteristic.

[0055] The selection of the three characteristics CHARC1, CHARC2, and CHARC3 is performed according to the above selection flow, thereby realizing the vehicle control as exemplified below.

[0056] 6 shows an example of switching of the clutch capacity characteristics when an upshift is performed after the vehicle 100 starts moving, and the results of the vehicle control achieved by this. In this example, the vehicle 100 is initially stopped. In this state, the accelerator pedal 52 is depressed to a certain opening, and the pseudo clutch pedal 54 is depressed until the clutch pedal stroke reaches the maximum value S_MAX.

[0057] When the pseudo clutch pedal 54 begins to be released at time t1, the clutch pedal stroke reaches the clutch meet point at time t2, and the virtual clutch capacity begins to increase. At this time, the virtual clutch capacity increases gradually in accordance with the low-speed characteristic CHARC2 selected in the initial state. By suppressing the increase in the virtual clutch capacity, sudden changes in vehicle acceleration are suppressed. Then, as the clutch pedal stroke approaches zero, the virtual clutch capacity approaches the upper limit value C_UL, and eventually the virtual clutch is fully engaged.

[0058] With the virtual clutch engaged, vehicle 100 starts moving and the vehicle speed increases. At time t3, the vehicle speed reaches 5 km / h. At this time, the virtual clutch pedal 54 is fully released and the clutch pedal stroke is zero, so the clutch capacity characteristic is switched from the low speed characteristic CHARC2 to the first high speed characteristic CHARC1.

[0059] After that, the pseudo clutch pedal 54 is depressed again, and the shift position of the virtual transmission is changed from first to second by shifting the pseudo shifter 56. When the pseudo clutch pedal 54 begins to be released at time t4, the clutch pedal stroke reaches the clutch meet point at time t5, and the virtual clutch capacity begins to increase. At this time, the virtual clutch capacity rises quickly in accordance with the first high-speed characteristic CHARC1. This rapid rise in the virtual clutch capacity causes a sudden increase in vehicle acceleration, allowing the driver to feel a direct sense of operation. As the clutch pedal stroke approaches zero, the virtual clutch capacity approaches the upper limit value C_UL, and eventually the virtual clutch is fully engaged. This completes the upshift from first to second gear.

[0060] Figure 7 shows another example of switching of the clutch capacity characteristics when an upshift is performed after the vehicle 100 starts moving. In this example, similar to the example shown in Figure 6, the pseudo clutch pedal 54 is operated twice: once when the vehicle 100 starts moving and once when the vehicle 100 upshifts. When the pseudo clutch pedal 54 is operated when the vehicle 100 starts moving, the low-speed characteristic CHARC2 selected in the initial state is used as the clutch capacity characteristic.

[0061] After the vehicle 100 starts moving, the vehicle speed reaches 5 km / h at time t11. However, in this example, the pseudo clutch pedal 54 is depressed to perform an upshift. Therefore, even if the vehicle speed reaches 5 km / h or more, the clutch capacity characteristic is not switched from the low-speed characteristic CHARC2 to the first high-speed characteristic CHARC1, and the low-speed characteristic CHARC2 continues to be maintained.

[0062] When the pseudo clutch pedal 54 begins to be released at time t12, the clutch pedal stroke reaches the clutch meet point and the virtual clutch capacity begins to increase. The change in virtual clutch capacity at this time follows the low-speed characteristic CHARC2. The switch from the low-speed characteristic CHARC2 to the first high-speed characteristic CHARC1 occurs at time t13 when the clutch pedal stroke reaches zero. Thereafter, at time t14, the vehicle speed decreases to less than 5 km / h, but because the clutch pedal stroke at this time is zero, the switch from the first high-speed characteristic CHARC1 to the low-speed characteristic CHARC2 occurs.

[0063] 8 shows an example of clutch capacity characteristic switching when a downshift is performed after an upshift, and the results of vehicle control achieved by this. In this example, the vehicle 100 is initially traveling at a speed of 5 km / h or more.

[0064] While maintaining a speed of 5 km / h or more, the virtual clutch pedal 54 is depressed, and at time t21, the virtual shifter 56 is operated to change the shift position of the virtual transmission from third to fourth. Then, at time t22, when the virtual clutch pedal 54 begins to be released, the clutch pedal stroke reaches the clutch meet point, and the virtual clutch capacity begins to increase. At this time, the virtual clutch capacity rises quickly in accordance with the first high-speed characteristic CHARC1. This rapid rise in the virtual clutch capacity causes a sudden increase in vehicle acceleration, allowing the driver to feel a direct sense of operation. As the clutch pedal stroke approaches zero, the virtual clutch capacity approaches the upper limit value C_UL, and eventually the virtual clutch is fully engaged. This completes the upshift from third to fourth gear.

[0065] Then, while maintaining a speed of 5 km / h or more, the virtual clutch pedal 54 is depressed again, and at time t23, the virtual shifter 56 is operated to change the shift position of the virtual transmission from fourth to third. This operation switches the clutch capacity characteristics from the first high-speed characteristics CHARC1 to the second high-speed characteristics CHARC3. Then, at time t24, when the virtual clutch pedal 54 begins to be released, the clutch pedal stroke reaches the clutch meet point, and the virtual clutch capacity begins to increase. At this time, the virtual clutch capacity increases relatively gradually in accordance with the second high-speed characteristics CHARC3. This relatively gradual increase in the virtual clutch capacity prevents a sudden increase in the virtual engine speed due to engine braking. As the clutch pedal stroke approaches zero, the virtual clutch capacity approaches the upper limit value C_UL, and eventually the virtual clutch is fully engaged. This completes the downshift from fourth to third gear.

[0066] 2. Second embodiment In the first embodiment, a virtual engine, a virtual clutch, and a virtual transmission are realized by controlling the torque of an electric motor, and the behavior of a manually variable speed internal combustion engine vehicle is reproduced in an electric vehicle. However, the behavior of a manually variable speed internal combustion engine vehicle can also be reproduced in an electric vehicle in which an electric motor is combined with a real transmission.

[0067] FIG. 9 is a diagram schematically illustrating a configuration of a vehicle 200 according to a second embodiment of the present disclosure. In FIG. 9, elements common to the vehicle 100 according to the first embodiment are assigned the same reference numerals. The vehicle 200 is a battery electric vehicle that controls an inverter 4 to supply electric energy stored in a battery 2 to an electric motor 6, which then drives drive wheels 18. The vehicle 200 is equipped with a transmission (T / M) 10. The output shaft of the electric motor 6 is connected to the transmission 16. The transmission 16 is a stepped transmission having multiple shiftable gears. The driver manually operates a shifter 58 to shift between the multiple gears of the transmission 16. The shifter 58 is, for example, an H-type shifter, and the shift lever can be moved along an H-type gate. The shifter 58 may be mechanically connected to the transmission 16 or may be connected to the transmission 16 via a by-wire system. The transmission 16 is connected to a differential gear 14 via a propeller shaft 12.

[0068] The control device 102 of the vehicle 200 includes a gear ratio calculation unit 117, a virtual clutch capacity calculation unit 112, a virtual engine speed calculation unit 113, a virtual engine torque calculation unit 114, a virtual clutch torque calculation unit 118, and a pseudo engine sound generation unit 116. These calculation units are virtually realized by a processor or a group of processors executing programs stored in the memory of the control device 102. Of these, the virtual clutch capacity calculation unit 112, the virtual engine speed calculation unit 113, the virtual engine torque calculation unit 114, and the pseudo engine sound generation unit 116 are the same as those in the first embodiment, and therefore detailed description thereof will be omitted.

[0069] The gear ratio calculation unit 117 acquires a signal from the shift position sensor 46. The shift position of the shifter 58 is obtained from the signal from the shift position sensor 46. The gear ratio of the transmission 10 is mechanically uniquely determined for each shift position. The gear ratio calculation unit 117 calculates the gear ratio corresponding to the current shift position using a correspondence table prepared in advance. The actual gear ratio of the transmission 10 calculated by the gear ratio calculation unit 117 is used to calculate the virtual engine speed by the virtual engine speed calculation unit 113.

[0070] Virtual clutch torque calculation unit 118 calculates a virtual clutch torque using the virtual engine torque calculated by virtual engine torque calculation unit 114 and the virtual clutch capacity calculated by virtual clutch capacity calculation unit 112. If the virtual engine torque is smaller than the virtual clutch capacity, virtual clutch torque calculation unit 118 outputs the virtual engine torque as the virtual clutch torque. On the other hand, if the virtual engine torque is larger than the virtual clutch capacity, virtual clutch torque calculation unit 118 outputs a virtual clutch torque limited to the virtual clutch capacity. Control device 102 controls inverter 4 so as to change the torque output by electric motor 6 in accordance with the virtual clutch torque.

[0071] In this embodiment, the control device 102 uses a vehicle model MOD02 shown in FIG. 10. The vehicle model MOD02 is made up of an engine model MOD12 and a clutch model MOD13. The control device 102 outputs the virtual clutch torque Tout calculated by the clutch model MOD13 to the electric motor 6. The transmission 10 increases the virtual clutch torque Tout input from the electric motor 6 in accordance with the gear ratio. The engine model MOD12 and the clutch model MOD13 are the same as those in the first embodiment, so detailed description thereof will be omitted.

[0072] In this embodiment as well, by switching the clutch capacity characteristics of the clutch model MOD13 according to the situation, it is possible to optimize the torque change characteristics in response to the operation of the pseudo clutch pedal 54 according to the situation. The first high-speed characteristic CHARC1 allows the driver to feel a direct sense of operation due to the quick rise in torque in response to the operation of the pseudo clutch pedal 54. The low-speed characteristic CHARC2 makes it easier to perform a half-clutch operation when starting off by suppressing the rise in torque in response to the operation of the pseudo clutch pedal 54. And the second high-speed characteristic CHARC3 makes it possible to suppress the rate of increase in the virtual engine speed during a downshift and alleviate surge shock associated with engine braking.

[0073] 3. Other embodiments In the first and second embodiments described above, accelerator pedal 52 and accelerator position sensor 42 constitute a first indicator that issues continuous instructions to control device 101 in accordance with the amount of operation of accelerator pedal 52. Accelerator pedal 52 is a pedal-type operating tool operated by foot, but a lever-type operating tool operated by hand may also be used as the first indicator.

[0074] In the first and second embodiments described above, the pseudo clutch pedal 54 and the clutch position sensor 44 constitute a second indicator that can be operated simultaneously with the pseudo clutch pedal 54 and that issues continuous instructions to the control device 101 according to the amount of operation of the pseudo clutch pedal 54. The pseudo clutch pedal 54 is a pedal-type operating device operated by foot, but a lever-type operating device or a dial-type operating device operated by hand may also be used as the second indicator. However, the second indicator is required to be operable with a foot or hand different from the foot or hand that operates the first indicator.

[0075] In the first embodiment described above, the pseudo shifter 56 and the shift position sensor 46 constitute a third indicator that issues a discrete instruction to the control device 101 for each operation of the pseudo shifter 56. Also, in the second embodiment described above, the shifter 58 and the shift position sensor 46 constitute a third indicator that issues a discrete instruction to the control device 101 for each operation of the shifter 58. The pseudo shifter 56 and the shifter 58 are shifters in which a shift position is uniquely associated with each operation, but a relative instruction type shifter such as a sequential shifter may also be used as the third indicator. The sequential shifter may have a structure similar to a shift stick provided on a console, for example, or a structure similar to shift paddles attached to a steering wheel.

[0076] In the first and second embodiments described above, hysteresis may be provided to the threshold value of the vehicle speed at which the clutch capacity characteristics are switched. Specifically, a first speed (e.g., 5 km / h) and a second speed (e.g., 10 km / h) are set as threshold vehicle speeds. In this case, when the vehicle speed increases from less than the first speed to equal to or greater than the first speed, the clutch capacity characteristics may be maintained at the first high-speed characteristics CHARC1 until the vehicle speed becomes less than the second speed. Also, when the vehicle speed decreases from equal to or greater than the second speed to less than the second speed, the clutch capacity characteristics may be maintained at the low-speed characteristics CHARC2 until the vehicle speed becomes equal to or greater than the first speed.

[0077] In the first and second embodiments described above, the relationship defined by the clutch model MOD13 is not limited to the relationship between the clutch pedal stroke and the virtual clutch capacity. For example, the clutch angle measured by a clutch angle sensor may be used instead of the clutch pedal stroke. Also, the torque transmission gain of the virtual clutch may be used instead of the virtual clutch capacity.

[0078] The torque control technology of the present disclosure is not limited to battery electric vehicles (BEVs) but can be widely applied to any electric vehicle that uses an electric motor as a driving power unit. For example, the torque control technology of the present disclosure can be applied to hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs) that have a mode in which they run solely on the driving force of the electric motor. The torque control technology of the present disclosure can also be applied to fuel cell electric vehicles (FCEVs) that supply electric energy generated by a fuel cell to an electric motor. [Explanation of symbols]

[0079] 2 Battery, 4 Inverter, 6 Electric motor, 8 Reducer, 10 Transmission, 12 Propeller shaft, 14 Differential gear, 16 Drive shaft, 18 Drive wheels, 30 Display device, 32 Speaker, 40 Vehicle speed sensor, 42 Accelerator position sensor, 44 Clutch position sensor, 46 Shift position sensor, 52 Accelerator pedal, 54 Dummy clutch pedal, 56 Dummy shifter, 58 Shifter, 100 Vehicle (First embodiment), 101 Control device, 102 Control device, 200 Vehicle (Second embodiment)

Claims

1. An electric vehicle having an electric motor as a drive source, a control device for controlling the torque output by the electric motor; a first indicator that issues continuous instructions to the control device in accordance with an operation amount; a second indicator that can be operated simultaneously with the first indicator and that issues successive instructions to the control device in accordance with an operation amount; The control device When the second indicator is not operated, a basic torque corresponding to the operation amount of the first indicator and a vehicle speed is output to the electric motor; When the operation amount of the second indicator is equal to or greater than the first operation amount, a predetermined minimum torque is output to the electric motor; When the operation amount of the second indicator is smaller than the first operation amount, the torque is increased from the minimum torque to the basic torque in accordance with the decrease in the operation amount of the second indicator; a torque change characteristic with respect to the operation amount of the second indicator when the operation amount of the second indicator is reduced to be less than the first operation amount is switched between a high speed characteristic that is selected when the vehicle speed is equal to or greater than a predetermined speed and a low speed characteristic that is selected when the vehicle speed is less than the predetermined speed, the high-speed characteristic is a characteristic in which a section in which the change in the torque with respect to the change in the operation amount of the second indicator is convex upward appears until the torque increases from the minimum torque to the basic torque, The low-speed characteristic is a characteristic in which the change in the torque from the minimum torque to the base torque is downwardly convex with respect to the change in the operation amount of the second indicator or is more linear than the high-speed characteristic. An electric vehicle characterized by:

2. 2. The electric vehicle according to claim 1, When the basic torque is a predetermined upper limit torque, the control device When the operation amount of the second indicator is equal to or less than a second operation amount that is smaller than the first operation amount, the electric motor is caused to output the upper limit torque; When the operation amount of the second indicator is smaller than the first operation amount and larger than the second operation amount, the torque is increased from the minimum torque to the upper limit torque in accordance with a decrease in the operation amount of the second indicator, the high-speed characteristic is a characteristic such that a section appears in which the change in the torque with respect to the change in the operation amount of the second indicator is convex upward until the operation amount of the second indicator changes from the first operation amount to the second operation amount, The low-speed characteristic is a characteristic in which the torque changes convexly downward from the minimum torque to the upper limit torque or changes more linearly than the high-speed characteristic while the operation amount of the second indicator changes from the first operation amount to the second operation amount. An electric vehicle characterized by:

3. 3. The electric vehicle according to claim 1, The high-speed characteristic is a characteristic in which the torque changes downwardly convexly and then upwardly convexly as the operation amount of the second indicator decreases from the first operation amount. An electric vehicle characterized by:

4. 3. The electric vehicle according to claim 1, The control device is configured not to switch the change characteristic when the second indicator is operated, even if the vehicle speed increases from less than the predetermined speed to equal to or greater than the predetermined speed, or even if the vehicle speed decreases from equal to or greater than the predetermined speed to less than the predetermined speed. An electric vehicle characterized by:

5. 3. The electric vehicle according to claim 1, the predetermined speeds include a first speed and a second speed that is smaller than the first speed; The control device When the vehicle speed increases from less than the first speed to equal to or greater than the first speed, the change characteristic is maintained at the high-speed characteristic until the vehicle speed becomes less than the second speed; When the vehicle speed decreases from equal to or greater than the second speed to less than the second speed, the change characteristic is maintained at the low speed characteristic until the vehicle speed becomes equal to or greater than the first speed. An electric vehicle characterized by:

6. 3. The electric vehicle according to claim 1, a third indicator that issues a discrete instruction to the control device for each operation; The control device a relationship between the operation amount of the first indicator, the vehicle speed, and the base torque is switched from among a plurality of predetermined relationships in accordance with the operation of the third indicator; When the vehicle speed is equal to or higher than the predetermined speed, if the second indicator is operated to the first operation amount or more and the third indicator is operated to increase the basic torque, the rate of change of the torque with respect to the operation amount of the second indicator when the operation amount of the second indicator is reduced below the first operation amount is reduced to be lower than the rate of change in the high-speed characteristics. An electric vehicle characterized by:

7. 3. The electric vehicle according to claim 1, a manual transmission that changes the gear ratio between the electric motor and the drive wheels; The control device is configured to, when the vehicle speed is equal to or higher than the predetermined speed, if the second indicator is operated to an amount equal to or greater than the first operation amount and the manual transmission is shifted down, reduce a rate of change of the torque with respect to the operation amount of the second indicator when the operation amount of the second indicator is reduced below the first operation amount, to be lower than a rate of change in the high-speed characteristics. An electric vehicle characterized by:

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