Electric vehicle and method of manufacturing an electric vehicle

Abstract

Disclosed are an electric vehicle and a manufacturing method for an electric vehicle. The electric vehicle has a motor, a clutch, a transmission, a rotational speed sensor that detects a rotational speed of the motor, and a control circuit that controls the motor. The control circuit performs: a learning process that detects a change in the rotational speed of the motor using the rotational speed sensor when a shift is performed; and a control process that controls the rotational speed of the motor based on the change in the rotational speed detected in the learning process when the shift is performed after the learning process.

Description

Technical Field

[0001] The technology disclosed in this specification relates to electric vehicles and methods of manufacturing them. Background Technology

[0002] The electric vehicle disclosed in International Publication WO2013 / 061359 includes a motor, a clutch, and a transmission. The input shaft of the transmission is connected to the motor via the clutch. The output shaft of the transmission transmits power to the drive wheels. The transmission changes the gear stages that transmit power from the input shaft to the output shaft. Furthermore, the electric vehicle has a control circuit that controls the motor speed during gear shifting. The control circuit suppresses shift shock by controlling the motor speed during gear shifting. Summary of the Invention

[0003] In the technology disclosed in International Publication WO2013 / 061359, the appropriate speed of the motor during gear shifting is determined as the target speed, and the control circuit suppresses shift shock by controlling the motor speed to the target speed during gear shifting. Therefore, the technology of International Publication WO2013 / 061359 cannot be used when the appropriate speed is unknown. For example, sometimes the engine of various gasoline vehicles (e.g., used gasoline vehicles) is replaced with a motor to create an electric vehicle. In this case, the appropriate speed for suppressing shift shock varies depending on the original gasoline vehicle's construction, making it difficult to set the target speed in the control circuit. This disclosure proposes a technology for suppressing shift shock when the appropriate speed is unknown.

[0004] One aspect of this disclosure discloses an electric vehicle having a motor, a clutch, a transmission, a speed sensor, and a control circuit. The transmission has an input shaft and an output shaft. The input shaft is connected to the motor via the clutch. The output shaft transmits power to drive wheels. The transmission changes gear stages that transmit power from the input shaft to the output shaft. The speed sensor detects the rotational speed of the motor. The control circuit controls the motor. The electric vehicle is capable of performing gear shifting by changing the gear stages after disengaging the clutch and engaging the clutch after changing the gear stages. The control circuit is configured to perform: a learning process, which detects a change in the motor's rotational speed using the speed sensor when the gear shift is performed; and a control process, which, after the learning process, controls the motor's rotational speed based on the rotational speed change detected in the learning process when the gear shift is performed.

[0005] In the electric vehicle described above, the control circuit performs a learning process in which a speed sensor detects changes in the motor's speed when a gear shift is performed. By detecting these changes in motor speed during gear shifts, the control circuit can calculate the motor speed at which shift shock can be suppressed. After the learning process, when a gear shift is performed, the control circuit controls the motor speed based on the speed changes detected during the learning process. Therefore, the control circuit can appropriately control the motor speed and suppress shift shock. Attached Figure Description

[0006] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, wherein like symbols denote like elements, wherein:

[0007] Figure 1 This is a block diagram showing the drive system of an electric vehicle.

[0008] Figure 2 This is a block diagram illustrating the drive system of a gasoline vehicle used in the manufacture of electric vehicles.

[0009] Figure 3 It is a table showing the transmission and torsional characteristics stored by the ECU.

[0010] Figure 4 This is a flowchart showing the first half of the process performed by the ECU during gear shifting.

[0011] Figure 5 This is a flowchart showing the second half of the process performed by the ECU during gear shifting.

[0012] Figure 6 It is a graph showing the motor speed during downshifting when the gear is not being learned.

[0013] Figure 7 It is a graph showing the motor speed during upshifting when the gear is not being learned.

[0014] Figure 8 It is a graph showing the motor speed during downshifting in the learned condition.

[0015] Figure 9 It is a graph showing the motor speed during upshifting in the learned condition.

[0016] Figure 10 It is a graph showing the predicted values ​​of vibration and the torque command values ​​in vibration control.

[0017] Figure 11 It is a graph showing the motor speed during oil replenishment. Detailed Implementation

[0018] In an example electric vehicle disclosed in this specification, during the learning process, the control circuit can also detect a first speed and a second speed. The first speed is the motor speed at a first timing when the clutch is disengaged, and the second speed is the motor speed at a second timing, which is a timing after vibrations in the motor speed occur following clutch engagement. Furthermore, during the control process, the control circuit can also vary the motor speed based on the first and second speeds during the period from the first timing to a third timing when the clutch is engaged. According to this structure, the difference between the motor speed and the input shaft speed of the transmission can be reduced at the timing of clutch engagement. Therefore, shift shock can be appropriately suppressed.

[0019] In one example of an electric vehicle disclosed in this specification, the control circuit may also reduce the motor speed during the period from the first timing to the third timing when the gear shift in the control process is an upshift. Alternatively, the control circuit may also increase the motor speed during the period from the first timing to the third timing when the gear shift in the control process is a downshift.

[0020] This structure can effectively suppress transmission shocks.

[0021] In an example electric vehicle disclosed in this specification, the control circuit may also, when the gear shift in the control process is downshifting, increase the motor speed faster when the required torque for the motor after disengaging the clutch is greater than or equal to a first reference value, compared to when the required torque for the motor after disengaging the clutch is less than the first reference value.

[0022] According to this structure, when the required torque is above the first reference value, the motor speed can be increased to a suitable value in a short time, and downshifting with less shift shock can be performed in a short time.

[0023] In an example electric vehicle disclosed in this specification, the control circuit may also perform speed control to maintain the target speed of the motor at a constant value from the third timing to the second timing during the control process, and after the third timing, when the speed of the motor detected by the speed sensor changes by a gradient greater than the second reference value, the speed control is stopped.

[0024] According to this structure, speed control can be stopped when the motor speed is not suitable for the input shaft speed of the transmission during speed control.

[0025] In one example of an electric vehicle disclosed in this specification, during the learning process, the control circuit can also detect a vibration waveform of the motor's rotational speed generated after the clutch is engaged. During the control process, the control circuit can also control the motor in a manner that suppresses vibrations in the motor's rotational speed generated after the clutch is engaged, based on the vibration waveform detected during the learning process.

[0026] This structure can suppress vibrations in the motor's rotational speed after the clutch is engaged.

[0027] In an example electric vehicle disclosed in this specification, the control circuit may also store the speed change in a storage area for each combination of gear stages changed during the gear shift. During the control process, the control circuit may also predict the combination of gear stages changed during the gear shift, read the speed change corresponding to the predicted combination from the storage area, and control the motor speed based on the read speed change.

[0028] Based on this structure, the motor speed can be appropriately controlled according to the combination of gear stages during gear shifting.

[0029] In one example of an electric vehicle disclosed in this specification, the control circuit may also presuppose that the gear stage at the start of the electric vehicle is the first speed, that the gear stage is raised by one level when the shift is an upshift, and that the gear stage is lowered by one level when the shift is a downshift.

[0030] Based on this structure, the gear stage can be inferred without using sensors that detect the gear stage.

[0031] In one example of an electric vehicle disclosed in this specification, the control circuit may also determine whether the gear shift is an upshift or a downshift based on the gradient of the change in the motor's rotational speed before the clutch is disengaged.

[0032] Based on this structure, it is possible to detect whether a gear shift is upshifting or downshifting without using sensors that detect gears.

[0033] In one example of an electric vehicle disclosed in this specification, the control circuit may also determine whether the shift is an upshift or a downshift based on the gradient of the motor's rotational speed before the clutch is disengaged and the torque demanded on the motor after the clutch is disengaged.

[0034] Based on this structure, it is possible to detect whether a gear shift is upshifting or downshifting without using sensors that detect gears.

[0035] In one example of an electric vehicle disclosed in this specification, the control circuit may also determine whether the clutch is engaged or disengaged based on the ratio of the change in the motor's rotational speed detected by the speed sensor to the motor's drive torque.

[0036] According to this structure, it is possible to detect whether the clutch is engaged or disengaged without using sensors to detect the state of the clutch.

[0037] This specification provides a method for manufacturing the aforementioned electric vehicle. The method includes: preparing a vehicle having an engine connected to the input shaft of the transmission via the clutch; and replacing the engine of the vehicle with the motor.

[0038] In electric vehicles manufactured using this method, the rotational speed at which shift shocks are unlikely to occur varies depending on the characteristics of the original vehicle's drive system. Vehicles manufactured using this method incorporate control circuits that perform the aforementioned learning and control processes, thereby suppressing shift shocks.

[0039] Figure 1 The drive system of an electric vehicle according to an embodiment is shown. Figure 1 Electric vehicles use motor 10 to drive drive wheels 40 to move. Figure 1 Electric vehicles are made of Figure 2 Vehicles manufactured using gasoline. Figure 2 The gasoline vehicle has an engine 110, a clutch 20, and a transmission 30. Figure 2 In gasoline vehicles, power is transmitted from engine 110 to drive wheels 40 via clutch 20 and transmission 30. Figure 1 Electric vehicles are achieved by... Figure 2 It was manufactured by replacing the engine 110 of a gasoline vehicle with a motor 10. Therefore, in Figure 1 In electric vehicles, power is transmitted from motor 10 to drive wheels 40 via clutch 20 and transmission 30.

[0040] Motor 10 has an output shaft 10a. Transmission 30 has an input shaft 30a and an output shaft 30b. The output shaft 10a of motor 10 is connected to the input shaft 30a of transmission 30 via clutch 20. When clutch 20 is engaged, power is transmitted from the output shaft 10a of motor 10 to the input shaft 30a of transmission 30; when clutch 20 is disengaged, power is not transmitted from the output shaft 10a of motor 10 to the input shaft 30a of transmission 30. Clutch 20 is operated by the driver. Transmission 30 has multiple gear stages. Power is transmitted from the input shaft 30a to the output shaft 30b via the gear stages. Transmission 30 changes the rotational ratio (i.e., gear ratio) of input shaft 30a relative to output shaft 30b by changing the gear stages that transmit power from input shaft 30a to output shaft 30b. The driver operates the gear lever, thereby changing the gear stages of transmission 30. That is, transmission 30 is a so-called manual transmission. The output shaft 30b of the transmission 30 is connected to the drive wheel 40 via a pinion (not shown), a gear ring, a drive shaft, etc.

[0041] Figure 1 The electric vehicle has a control circuit 50 that controls a motor 10 and a speed sensor 60 that detects the rotational speed (in rpm) of the motor 10. The control circuit 50 includes an ECU (Electronic Control Unit) 52 and an inverter 54. The inverter 54 supplies AC power to the motor 10. That is, the motor 10 is an AC motor that operates using AC power. The ECU 52 controls the frequency and amplitude of the AC power supplied from the inverter 54 to the motor 10 by controlling the inverter 54. This controls the rotational speed and drive torque of the motor 10. The speed sensor 60 detects the rotational speed of the output shaft 10a of the motor 10.

[0042] The specifications of gasoline vehicles used in the manufacture of electric vehicles vary widely, so it is impossible to input the detection values ​​of sensors present in traditional gasoline vehicles (e.g., sensors that detect the state of clutch 20, sensors that detect the gear stages of transmission 30, sensors that detect the rotational speed of the output shaft 30b of transmission 30, etc.) into ECU 52. Therefore, ECU 52 detects the state of the drive system based on the rotational speed of motor 10 detected by speed sensor 60. Furthermore, the shifting characteristics of the drive systems (i.e., clutch 20, transmission 30, etc.) of gasoline vehicles used in the manufacture of electric vehicles vary widely. Therefore, in Figure 1 In electric vehicles, ECU52 learns the shifting characteristics of the drive system and controls the speed of motor 10 during shifting based on the learning results. The following explains the processing performed by ECU52 during shifting.

[0043] The ECU 52 assumes the gear level at the start of the electric vehicle is 1st gear. Furthermore, as will be described in detail later, the ECU 52 determines whether a gear shift is upshifting or downshifting. If it determines an upshift, the ECU 52 assumes the gear level has increased by one stage. If it determines a downshift, the ECU 52 assumes the gear level has decreased by one stage. Therefore, the ECU 52 continuously determines the current gear level throughout the operation of the electric vehicle.

[0044] ECU 52 has a storage area. ECU 52 stores the transmission characteristics and torsional characteristics of the drive system in this storage area. Transmission characteristics are indicators of the degree to which the rotational speed of the input shaft 30a of the transmission 30 changes during gear shifts. For example, ECU 52... Figure 3 The diagram shows that each combination of gear stages changed during gear shifting stores transmission characteristics. Details regarding transmission characteristics will be described later. Torsional characteristics represent the vibrational characteristics of the motor 10's rotational speed generated during gear shifting. For example, ECU 52... Figure 3 The diagram shows that torsional characteristics are stored for each combination of gear stages that change during gear shifts. Details regarding torsional characteristics will be described later. Furthermore, the shifting and torsional characteristics stored in the storage area are acquired by the ECU 52 through a learning process. Therefore, if the ECU 52 has not learned these characteristics, empty values ​​(i.e., NULL values) are stored in the ECU 52's storage area as shifting and torsional characteristics.

[0045] Figure 4 , 5 The process executed by ECU 52 during gear shifting is shown. In step S2, ECU 52 determines whether clutch 20 is disengaged. ECU 52 repeatedly executes step S2 during the operation of the electric vehicle. In step S2, ECU 52 detects whether clutch 20 is disengaged based on the ratio of the torque command value for motor 10 to the change in motor 10 speed detected by speed sensor 60. That is, when clutch 20 is disengaged, motor 10 is separated from drive wheel 40, so the speed of motor 10 is prone to change. Therefore, even if the torque command value is the same, the change in motor 10 speed is much larger when clutch 20 is disengaged compared to when clutch 20 is engaged. In step S2, ECU 52 determines that clutch 20 is disengaged if the value obtained by dividing the change in motor 10 speed by the torque command value is above a reference value.

[0046] After disengaging clutch 20, the driver changes the gear stage of transmission 30. When changing gear stages, the rotational speed of the input shaft 30a of transmission 30 changes. That is, when downshifting, the rotational speed of the input shaft 30a of transmission 30 increases. When upshifting, the rotational speed of the input shaft 30a of transmission 30 decreases. After changing gear stages, the driver engages clutch 20. When engaging clutch 20 while the difference between the rotational speed of motor 10 (i.e., the rotational speed of the output shaft 10a of motor 10) and the rotational speed of the input shaft 30a of transmission 30 is large, a large shift shock occurs. Therefore, ECU 52 can reduce the difference between the rotational speed of motor 10 and the rotational speed of the input shaft 30a of transmission 30 during the period from clutch 20 disengagement to clutch 20 engagement. Furthermore, ECU 52 can perform vibration damping control to suppress vibration after clutch 20 engagement. The processing performed by ECU 52 varies depending on whether ECU 52 has learned the shift characteristics and torsional characteristics.

[0047] First, let's explain the situation where ECU52 has not learned the transmission characteristics and torsional characteristics. Figure 6 , 7 The diagram shows the change in motor 10 speed during gear shifts when the ECU 52 has not learned the transmission and torsional characteristics. Figure 6 , 7 In step S2, timing t1 is the timing at which the clutch 20 is determined to be disengaged.

[0048] When it is determined that the clutch 20 is disengaged, the ECU 52 executes step S4. In step S4, the ECU 52 uses the speed sensor 60 to detect the speed of the motor 10 (hereinafter referred to as speed r1) at the time t1 when the clutch 20 is disengaged. The ECU 52 stores the speed r1.

[0049] Next, in steps S6 to S12, ECU52 determines whether the shift is an upshift or a downshift.

[0050] In step S6, ECU 52 determines whether the electric vehicle is decelerating. Here, ECU 52 makes this determination based on the rate of change of the motor 10's rotational speed, dr / dt, when the clutch 20 is disengaged. That is, when the rate of change, dr / dt, is negative, ECU 52 determines that the electric vehicle is decelerating, and therefore determines it is so in step S6. For example, in... Figure 6 In step S6, the motor 10's speed decreases at time t1, so it is determined to be "yes". Conversely, when the rate of change dr / dt is positive or zero, the electric vehicle is either accelerating or moving at a constant speed, so it is determined to be "no" in step S6. For example, in... Figure 7 In step S6, the speed of motor 10 increases at time t1, so it is determined to be negative.

[0051] If the determination is yes in step S6, ECU52 determines in step S12 that the gear shift is a downshift.

[0052] If the determination in step S6 is negative, ECU 52 determines whether the required torque input to ECU 52 in step S8 is above a reference value (first reference value). The required torque input to ECU 52 varies depending on the amount of accelerator pedal depressed by the driver. In normal shifting, the driver does not depress the accelerator pedal, so the required torque is low. However, in a technique called rev-matching, the driver depresses the accelerator pedal in parallel with shifting. In this case, the required torque becomes higher than the reference value during the shift. In step S8, ECU 52 determines whether the driver has performed rev-matching by determining whether the required torque is above the reference value. If the determination in step S8 is positive (i.e., the driver performed rev-matching), ECU 52 determines in step S12 that the shift is a downshift. Conversely, if the determination in step S8 is negative (i.e., the driver did not perform rev-matching), ECU 52 determines in step S10 that the shift is an upshift.

[0053] As described above, when the electric vehicle is decelerating, ECU52 interprets the gear shift as a downshift regardless of whether throttle input has been made. Conversely, when the electric vehicle is accelerating or moving at a constant speed and throttle input has been made, ECU52 interprets the gear shift as a downshift. And when the electric vehicle is accelerating or moving at a constant speed but without throttle input, ECU52 interprets the gear shift as an upshift.

[0054] If, in step S12, it is determined that the gear shift is a downshift, ECU 52 begins torque increase control in step S16. That is, ECU 52 increases the torque command value for motor 10, thereby increasing the speed of motor 10. For example, in... Figure 6 In the process, after the clutch 20 disengages at a time t1, the ECU 52 increases the torque command value, thus increasing the speed of the motor 10. Furthermore, if lubrication is performed, the ECU 52 increases the torque command value to an even higher value, causing the motor 10 to speed up even faster. Torque increase control continues until step S22 or S24, which will be described later.

[0055] Furthermore, if it is determined in step S10 that the gear shift is an upshift, ECU 52 begins torque reduction control in step S14. That is, ECU 52 reduces the torque command value for motor 10, thereby reducing the speed of motor 10. For example, in Figure 7 In the process, after the clutch 20 disengages at a time t1, the ECU 52 reduces the torque command value, thus reducing the speed of the motor 10. Torque reduction control continues until step S22 or step S24.

[0056] When step S14 or S16 is executed, ECU 52 determines the gear stage after the shift in step S18. As described above, ECU 52 determines the gear stage before shifting. In the case of upshifting, ECU 52 determines the gear stage one level higher than the gear stage before the shift as the gear stage after the shift. In the case of downshifting, ECU 52 determines the lower gear stage one level lower than the gear stage before the shift as the gear stage after the shift. Thus, in step S18, the combination of gear stages changed during the shift is determined. Hereinafter, the combination of gear stages changed during the shift will sometimes be referred to as the type of shift.

[0057] Next, ECU 52 executes step S20. In step S20, ECU 52 determines whether it has learned the transmission characteristics corresponding to the shift type determined in step S18. That is, ECU 52 accesses... Figure 3 The dataset of illustrated shift characteristics is used to determine whether the shift characteristics corresponding to the shift types determined in step S18 have been learned. If the shift characteristics of the target object have been learned, ECU 52 determines "yes" in step S20; otherwise, it determines "no" in step S20. Figure 6 , 7 In the example, ECU 52 has not learned the transmission characteristics, so ECU 52 determines no in step S20. In this case, ECU 52 executes step S24. In step S24, ECU 52 monitors the speed of motor 10, and terminates torque increase control or torque decrease control when the speed of motor 10 changes by a predetermined amount. For example, in Figure 6 In the process, at a predetermined timing t2 when the speed of motor 10 increases by a certain amount Δrx, ECU 52 terminates the torque increase control. Additionally, for example, in... Figure 7 In the process, at a time t2 when the speed of motor 10 decreases by a predetermined amount Δrx, ECU 52 terminates the torque reduction control. After the torque increase control or torque decrease control ends, ECU 52 controls motor 10 to maintain its speed at a constant level.

[0058] exist Figure 6 , 7 In this context, speed r2 represents the speed of motor 10 after torque increase control or torque decrease control is implemented. Additionally, speed rh represents the actual speed of the input shaft 30a of the transmission 30 after gear stage changes. As described above, the ECU 52 changes the speed of motor 10 by a predetermined amount Δrx without learning the transmission characteristics. Therefore, it is impossible to accurately match speed r2 to speed rh.

[0059] Similar to step S2, during gear shifting, ECU 52 monitors the ratio of the change in motor 10 speed to the torque command value. When the driver engages clutch 20, the value obtained by dividing the change in motor 10 speed by the torque command value decreases to a value less than a reference value. Therefore, ECU 52 determines in step S26 that clutch 20 is engaged. For example, in Figure 6 , 7 At time t3, clutch 20 engages.

[0060] When engagement of clutch 20 is detected, ECU 52 executes step S28. In step S28, ECU 52 determines whether it has learned the torsional characteristics corresponding to the type of shift determined in step S18. That is, ECU 52 accesses... Figure 3 The illustrated dataset of torsional characteristics is used to determine whether the torsional characteristics corresponding to the shift type determined in step S18 have been learned. If the torsional characteristics of the target have not been learned, the ECU 52 determines no in step S28 and skips steps S30 and S32. That is, if the torsional characteristics of the target have not been learned, the ECU 52 does not perform the vibration control in step S32.

[0061] As explained above, when the ECU 52 has not learned the transmission characteristics, it cannot accurately match the speed r2 of the motor 10 to the speed rh of the input shaft 30a of the modified gearbox 30. Furthermore, when the ECU 52 has not learned the torsional characteristics, vibration control is not performed after the clutch 20 engages. Therefore, a large shift shock occurs immediately after the clutch 20 engages. For example, in… Figure 6 , 7 During the period T1 immediately following the engagement of clutch 20, the rotational speed of motor 10 fluctuates significantly. Furthermore, the rotational speed of motor 10 changes significantly before and after the period T1 during which the vibration occurs. For example, in... Figure 6 In the process, when the clutch 20 engages at time t3, the output shaft 10a of the motor 10 is driven by the rotation of the input shaft 30a of the transmission 30, thereby increasing the speed of the motor 10 to a speed r3 that is approximately the same as the speed rh of the input shaft 30a. Additionally, in Figure 7 In the process, when clutch 20 engages at time t3, the output shaft 10a of motor 10 is dragged by the rotation of input shaft 30a of transmission 30, causing the speed of motor 10 to drop to a speed r3 that is approximately the same as the speed rh of input shaft 30a. Thus, in a state where ECU 52 has not learned the transmission and torsional characteristics, the speed of motor 10 changes drastically after clutch 20 engages, generating a large transmission shock in the electric vehicle.

[0062] After the clutch 20 is engaged, the ECU 52 monitors the speed of the motor 10. At the timing t4 when the vibration of the motor 10's speed converges, the ECU 52 executes steps S34 and S36.

[0063] In step S34, the ECU 52 stores the vibration waveform of the motor 10's rotational speed generated during period T1 as a torsional characteristic. Here, the ECU 52 stores the detected vibration waveform as a torsional characteristic corresponding to the type of gear shift determined in step S18.

[0064] In step S36, ECU 52 detects the rotational speed r3 of motor 10 at time t4. Next, in step S38, ECU 52 divides rotational speed r3 by rotational speed r1 to calculate the rate of change of rotational speed r3 / r1 of motor 10 before and after the gear shift. The rotational speed r1 of motor 10 before the gear shift is equal to the rotational speed of input shaft 30a of transmission 30 before the gear shift. Furthermore, the rotational speed r3 of motor 10 after the gear shift is equal to the rotational speed of input shaft 30a of transmission 30 after the gear shift. Therefore, the rate of change r3 / r1 is equal to the rate of change of rotational speed of input shaft 30a of transmission 30 before and after the gear shift. ECU 52 stores the rate of change r3 / r1 as a shift characteristic. ECU 52 stores the rate of change r3 / r1 calculated in step S38 as a shift characteristic corresponding to the type of gear shift determined in step S18.

[0065] Furthermore, when the gear stage before the shift has a gear ratio A, the rotational speed rs of the output shaft 30b of the transmission 30 at the start of the shift satisfies the relationship rs = r1 / A. Also, the rotational speed rs of the output shaft 30b remains almost unchanged before and after the shift. Furthermore, when the gear stage after the shift has a gear ratio B, the rotational speed rh of the input shaft 30a of the transmission 30 after the shift satisfies the relationship rh = B·rs = (B / A)·r1 (hereinafter referred to as Equation 1). Furthermore, the rotational speed r3 of the motor 10 after the shift is equal to the rotational speed rh of the input shaft 30a of the transmission 30 after the shift, so it satisfies the relationship r3 = rh (hereinafter referred to as Equation 2). From Equations 1 and 2 above, the relationship r3 / r1 = B / A (hereinafter referred to as Equation 3) can be obtained. That is, the rate of change r3 / r1 is approximately equal to the ratio of the gear ratios A and B of the gear stages before and after the shift. By multiplying the rate of change r3 / r1 by the speed of motor 10 before the shift, a predicted value of the speed rh of the input shaft 30a of the transmission 30 after the shift can be calculated. Thus, the transmission characteristics are such that the value of the speed rh of the input shaft 30a after the shift can be predicted.

[0066] Furthermore, in this embodiment, the shift characteristic is the rate of change r3 / r1, but other values ​​can also be used as the shift characteristic. For example, the shift characteristic can also be a function, database, etc., capable of calculating a predicted value of the input shaft 30a's rotational speed rh after the shift based on the type of shift and the rotational speed of the motor 10 at the start of the shift. Additionally, when learning the shift characteristic for each shift, the shift characteristic can also be a function, database, etc., capable of calculating a predicted value of the input shaft 30a's rotational speed rh after the shift based on the rotational speed of the motor 10 at the start of the shift.

[0067] As explained above, ECU52 learns the shift characteristics and torsional characteristics without having learned them beforehand.

[0068] Next, we will explain shifting gears when the transmission characteristics and torsional characteristics have been learned. Figure 8 , 9 The example illustrates the change in the rotational speed of motor 10 during gear shifting, assuming that the transmission and torsional characteristics have been learned.

[0069] Even when the transmission and torsional characteristics have been learned, ECU52 executes steps S2 to S18 in the same manner as when they haven't been learned. Therefore, in Figure 8 , 9 In, with Figure 6 , 7 Similarly, at time t1, the disengagement of clutch 20 is detected, and the speed of motor 10 at time t1 (hereinafter referred to as speed r11) is detected. After time t1, torque reduction control or torque increase control is performed.

[0070] If the transmission characteristics have been learned, ECU 52 determines "yes" in step S20. Therefore, ECU 52 executes step S22. In step S22, ECU 52 reads the transmission characteristics corresponding to the type of shift determined in step S18 from the storage area. Then, based on the read transmission characteristics and the motor 10 speed r11 detected in step S4, it calculates a predicted value rt of the speed of the input shaft 30a of the transmission 30 after the shift. For example, if the transmission characteristics are a rate of change r3 / r1, ECU 52 calculates the predicted value rt using the formula rt = (r3 / r1)·r11. Next, ECU 52 sets the predicted value rt as the control target value for the motor 10 speed. Therefore, as... Figure 8 , 9As shown, ECU 52 performs torque increase control or torque decrease control until the speed of motor 10 matches the control target value rt. At time t5, after the speed of motor 10 matches the control target value rt, ECU 52 controls the speed of motor 10 in a manner that keeps the speed of motor 10 consistent with the control target value rt. Therefore, immediately after time t5, the speed of motor 10 is approximately consistent with the control target value rt. The control target value rt of motor 10 is maintained until the shift completion time (i.e., Figure 8 , 9 (Timer t7).

[0071] Then, in step S26, ECU52 detects the engagement of clutch 20. Figure 8 , 9 At time t6, clutch 20 engages. When clutch 20 engages, the speed of motor 10 then vibrates. As described above, before clutch 20 engages, the speed of motor 10 is controlled to a target value rt that is approximately the same as the speed rh of the input shaft 30a of the gearbox 30 after gear shifting. Therefore, in Figure 8 , 9 In this process, the vibration of the motor 10's speed after the clutch 20 engages is small, and the speed variation before and after the vibration is also small. Thus, with the transmission characteristics already learned, the speed of the motor 10 is controlled to be approximately the same as the speed rh before the clutch 20 engages, resulting in minimal transmission shock.

[0072] In addition, when the ECU52 detects the engagement of the clutch 20 in step S26, it performs vibration control as needed in steps S28 to S32.

[0073] If the ECU 52 has learned the torsional characteristics corresponding to the shift type determined in step S18, it determines "yes" in step S28 and executes step S30. In step S30, if the amplitude of the torsional characteristic of the object (i.e., the amplitude of the vibration waveform of the rotational speed detected in the learning process) is less than a reference value, the ECU 52 determines "no" in step S30 and does not perform vibration control. If the amplitude of the torsional characteristic of the object is greater than or equal to the reference value, the ECU 52 determines "yes" in step S30 and performs vibration control in step S32.

[0074] Figure 10 The predicted value of the vibration of the motor 10's rotational speed and the torque command value ts of the motor 10 in vibration damping control are shown. The timing t6x of the ECU 52 at the start of vibration damping control (and...) Figure 8 , 9The ECU 52 reads the torsional characteristics of the object from the storage area (approximately the same timing as t6x) and calculates the predicted value of the vibration generated after the timing t6x. The frequency of the vibration generated after the clutch 20 is engaged is determined based on the configuration of the drive system (e.g., the resonant frequency of the drive system). Therefore, the ECU 52 can predict the vibration generated after the timing t6x from the torsional characteristics (i.e., the vibration waveform detected in the learning process). When the ECU 52 calculates the predicted value of the vibration generated after the timing t6x, it differentiates the predicted value and calculates the predicted value of the torque applied to the rotating shaft of the motor 10 due to the vibration. Next, the ECU 52 calculates the torque command value ts in a way that eliminates the predicted value of the calculated torque. After the timing t6x, the ECU 52 controls the torque of the motor 10 according to the graph of the calculated torque command value ts. As a result, the vibration of the motor 10's rotational speed generated after the clutch 20 is engaged is suppressed. By performing vibration damping control in this way, the vibration of the motor 10's rotational speed is further suppressed.

[0075] Afterwards, ECU52 executes steps S34 to S38. Furthermore, if the torsional characteristics have already been learned, step S34 (i.e., the torsional characteristic learning process) can be skipped, or step S34 can be executed. Executing step S34 when the torsional characteristics have already been learned allows for more precise vibration control. Similarly, if the gear shifting characteristics have already been learned, steps S36 and S38 (i.e., the gear shifting characteristic learning process) can be skipped, or steps S36 and S38 can be executed. Executing steps S36 and S38 when the gear shifting characteristics have already been learned allows for more precise matching of the motor 10's rotational speed with the input shaft 30a of the transmission 30.

[0076] Furthermore, when the required torque after clutch 20 engagement is higher than the reference value (i.e., when lubrication has been performed), ECU52 sets the torque value in the torque rise control to be higher than when lubrication has not been performed. When lubrication is performed while the transmission characteristics have been learned, such as... Figure 11 As shown, after detecting the timing tb for rev-matching, ECU 52 increases the torque command value for motor 10. As a result, the speed of motor 10 increases more rapidly after timing tb. Therefore, the speed of motor 10 can be controlled to the target control value rt in a shorter time. Thus, with rev-matching, gear shifts with less shift shock can be performed in a shorter time.

[0077] Furthermore, as mentioned above, ECU 52 assumes that the gears change one gear at a time with each gear shift. However, sometimes the driver skips gears. For example, sometimes the driver upshifts from 2nd gear to 4th gear, or downshifts from 4th gear to 2nd gear. In this case, the control target value rt becomes a value that is significantly different from the actual rotational speed rh of the input shaft 30a, and the rotational speed of the motor 10 sometimes increases or decreases sharply immediately after the clutch 20 engages at the timing t6. In this case, when ECU 52 maintains the target value of the motor 10's rotational speed at the control target value rt, the operation of the motor 10 sometimes becomes abnormal. Therefore, when the rotational speed of the motor 10 changes by a gradient (i.e., increases or decreases) above a predetermined reference value (the second reference value) immediately after the clutch 20 engages at the timing t6, ECU 52 can also stop the control that aims to maintain the rotational speed of the motor 10 at the control target value rt.

[0078] Furthermore, in the above embodiment, torsional characteristics were learned for each type of gear shift. However, if the torsional characteristics remain almost unchanged even if the type of gear shift changes, then one torsional characteristic can also be learned. In this case, vibration control based on a common torsional characteristic can be performed for all types of gear shifts.

[0079] Steps S36 and S38 above are examples of learning processes for detecting the first and second rotational speeds. Step S22 above is an example of control processes for changing the motor speed based on the first and second rotational speeds. Step S34 above is an example of learning processes for detecting vibration waveforms. Step S32 above is an example of control processes for controlling the motor to suppress vibrations in its rotational speed based on the vibration waveform. Timing t1 above is an example of the first timing. Timing t4 above is an example of the second timing. Timing t6 above is an example of the third timing.

[0080] The embodiments have been described in detail above, but these are merely illustrative and do not limit the scope of the patent claims. The technology described in the patent claims includes examples of various modifications and alterations to the specific examples illustrated above. The technical elements described in this specification or drawings exert their technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of application. Furthermore, the technology illustrated in this specification or drawings achieves multiple objectives simultaneously, and achieving even one of these objectives is itself technically useful.

Claims

1. An electric vehicle, characterized by Comprise: a motor; a clutch; a transmission having an input shaft and an output shaft, the input shaft being connected to the motor via the clutch, the output shaft transmitting power to drive wheels, a gear stage changing the power transmitted from the input shaft to the output shaft; a rotational speed sensor detecting a rotational speed of the motor; and a control circuit controlling the motor, wherein the electric vehicle is manufactured by replacing an engine of a vehicle having the engine connected to the input shaft of the transmission via the clutch with the motor, the electric vehicle is capable of performing a shift in which the gear stage is changed after the clutch is disengaged and the clutch is engaged after the gear stage is changed, the control circuit is configured to perform: a learning process in which a change in the rotational speed of the motor is detected by the rotational speed sensor when the shift is performed; and a control process in which the rotational speed of the motor is controlled based on the change in the rotational speed detected in the learning process when the shift is performed after the learning process, in the learning process, the control circuit detects a first rotational speed and a second rotational speed, the first rotational speed being a rotational speed of the motor at a first timing at which the clutch is disengaged, the second rotational speed being a rotational speed of the motor at a second timing that is a timing after a vibration of the rotational speed of the motor occurs after the clutch is engaged, in the control process, the control circuit changes the rotational speed of the motor during a period from the first timing to a third timing at which the clutch is engaged, based on the first rotational speed and the second rotational speed, the control circuit decreases the rotational speed of the motor during the period from the first timing to the third timing when the shift in the control process is an upshift, and increases the rotational speed of the motor during the period from the first timing to the third timing when the shift in the control process is a downshift, the control circuit increases the rotational speed of the motor more rapidly when the shift in the control process is a downshift and a required torque for the motor after the clutch is disengaged is equal to or greater than a first reference value than when the shift in the control process is a downshift and the required torque for the motor after the clutch is disengaged is less than the first reference value.

2. The electric vehicle according to claim 1, wherein the control circuit performs rotational speed control in which a target rotational speed of the motor is maintained at a constant value during a period from the third timing to the second timing in the control process, and suspends the rotational speed control when the rotational speed of the motor detected by the rotational speed sensor after the third timing changes at a gradient equal to or greater than a second reference value.

3. The electric vehicle according to claim 1 or 2, wherein in the learning process, the control circuit detects a vibration waveform of the rotational speed of the motor that occurs after the clutch is engaged, in the control process, the control circuit controls the motor in a manner that suppresses the vibration of the rotational speed of the motor that occurs after the clutch is engaged, based on the vibration waveform detected in the learning process. ​ 4. The electrically driven vehicle according to claim 1 or 2, characterized in that the control circuit stores the change in the rotational speed for each combination of the gear stages changed in the shift in a storage area, in the control process, the control circuit speculates the combination of the gear stages changed in the shift, reads out the change in the rotational speed corresponding to the speculated combination from the storage area, and controls the rotational speed of the motor according to the read-out change in the rotational speed.

5. The electrically driven vehicle according to claim 4, characterized in that the control circuit speculates the gear stage at the start of the electrically driven vehicle as the first speed, speculates the gear stage as being raised by one stage when the shift is upshift, and speculates the gear stage as being lowered by one stage when the shift is downshift.

6. The electrically driven vehicle according to claim 1, characterized in that the control circuit determines whether the shift is upshift or downshift according to the gradient of the change in the rotational speed of the motor before the clutch is disengaged.

7. The electrically driven vehicle according to claim 1, characterized in that the control circuit determines whether the shift is upshift or downshift according to the gradient of the change in the rotational speed of the motor before the clutch is disengaged and the required torque for the motor after the clutch is disengaged.

8. The electrically driven vehicle according to claim 1 or 2, characterized in that the control circuit determines whether the clutch is engaged or disengaged according to the ratio of the amount of change in the rotational speed of the motor detected by the rotational speed sensor to the drive torque of the motor.

9. A manufacturing method of an electric vehicle according to any one of claims 1 to 8, characterized by, including: preparing a vehicle provided with an engine connected to the input shaft of the transmission via the clutch; and replacing the engine of the vehicle with the motor.

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