Control device for electric vehicle

Abstract

To achieve suppression of both a torque shock and a slip loss.SOLUTION: During traveling of an electric vehicle 1, clutch complete engagement control is executed together with torque control, and when executing magnetic force change control during operation of the electric vehicle 1, clutch slip control is executed at the time of the magnetic force change control. A transmission clutch 83 has a transit transmission torque range RM with respect to the characteristic of torque transmitted when engagement, and further has a clutch characteristic that in the transit transmission torque range RM, clutch difference torque becomes equal to or less than specific insensitive difference torque and a clutch difference rotation speed becomes equal to or less than a specific allowance rotation speed. The transmission clutch 83 is slipped slightly so that just before the magnetic force change control, the clutch difference rotation speed becomes equal to or less than an allowance rotation speed and the clutch difference torque becomes equal to or less than the insensitive difference torque.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The disclosed technology relates to a control device for an electrically powered vehicle capable of running using electric power, such as an electric vehicle or a hybrid vehicle. [Background technology]

[0002] Patent Document 1 discloses a hybrid vehicle equipped with a permanent magnet synchronous drive motor. In this drive motor, a variable magnetic force magnet that can change the magnitude of magnetic force is used as the permanent magnet installed in the rotor.

[0003] When changing the magnetic force of the variable magnetic force magnet, a large current for magnetization (so-called d-axis current) is applied to the coil of the stator of the drive motor. As a result, while the drive motor is rotating, this current interferes with the driving current (so-called q-axis current) and causes the torque to fluctuate. In other words, the d-axis current is a component that is orthogonal to the q-axis current that generates the torque. Therefore, although this large current itself is not output as torque, it interferes with the q-axis current and causes the torque to fluctuate.

[0004] In general, the torque required to engage a clutch provided between a drive motor and drive wheels is set higher than the torque required to fully engage the clutch. Therefore, when the fluctuating torque is transmitted to the drive wheels, a torque shock occurs in the vehicle while it is moving, which may cause a driver to feel uncomfortable.

[0005] One way to suppress such torque shock is to slip the clutch installed between the drive motor and the drive wheels. In other words, even if a high torque is output from the drive motor, slipping the clutch reduces the torque transmitted to the drive wheels, thereby mitigating the torque shock.

[0006] However, when the clutch is slipped, a phenomenon occurs in which the rotation of the drive motor suddenly increases (known as "revving up"). If this revving up phenomenon is not resolved quickly, there is a concern that the clutch may be damaged by frictional heat caused by the slippage.

[0007] Therefore, the present inventors have previously proposed a technique for quickly eliminating the racing of the drive motor that accompanies such clutch slippage (Patent Document 2).

[0008] This technology basically switches from torque control, which controls the torque required for output as a target, to power control, which controls the output power as a target, when slippage occurs in the clutch due to magnetization. This makes it possible to converge the rotation speed as well as the output torque, and quickly eliminates the racing of the drive motor. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent Publication No. 2021-027615 [Patent Document 2] JP 2022-187694 A Summary of the Invention [Problem to be solved by the invention]

[0010] The present inventors also found that when the kinetic friction coefficient and static friction coefficient of the clutch are different, the above-mentioned torque shock may occur when the clutch is engaged due to the difference in the friction coefficient. Therefore, focusing on this point, the inventors have previously proposed a technology for suppressing the torque shock caused by the difference in the friction coefficient (Patent Application No. 2022-062954).

[0011] Incidentally, the above-mentioned revving generates energy loss (slip loss). Slip loss deteriorates fuel economy (including electricity consumption, the same applies below). Therefore, it is preferable to suppress not only torque shock but also slip loss.

[0012] In response to this, the inventors investigated the relationship between the occurrence of torque shock and clutch characteristics and found that when certain conditions are met in a clutch having specific transmission torque characteristics, it is possible to suppress both the torque shock and slip loss described above.

[0013] Therefore, this time, we will disclose a technology that makes it possible to suppress both the torque shock and slip loss described above. [Means for solving the problem]

[0014] The disclosed technology relates to a control device for an electric vehicle capable of running using electric power, which is equipped with a drive motor whose rotor poles are composed of variable magnetic magnets whose magnetic force can be changed, and a clutch arranged between the drive motor and drive wheels.

[0015] When the electric vehicle is traveling, the control device performs torque control to control the motor torque output by the drive motor so that it matches the required torque required to be output to the drive wheels, as well as clutch full engagement control to make the engagement torque of the clutch higher than both the input torque input to the clutch and the output torque output from the clutch, and when magnetic force change control to change the magnetic force of the magnetic force variable magnet is performed while the electric vehicle is in operation, during the magnetic force change control, instead of the clutch full engagement control, performs clutch slip control to lower the engagement torque to close to the output torque and the input torque.

[0016] The clutch has, with regard to the torque characteristics transmitted when engaged, a low transmission torque region in which the output torque and the input torque are the same value, a high transmission torque region in which the output torque remains unchanged at a predetermined upper limit transmission torque even if the input torque increases, and a transition transmission torque region that exists between the low transmission torque region and the high transmission torque region and in which the output torque is smaller than the input torque.The clutch further has clutch characteristics in which, in the transition transmission torque region, a clutch differential torque, which is the difference between the current output torque and the upper limit transmission torque, is equal to or less than a specific insensible differential torque set based on the human detection limit, and a clutch differential rotational speed, which is the difference in the rotational speed between the input side and the output side of the clutch, is equal to or less than a specific allowable difference rotational speed set based on energy gain or loss.

[0017] Then, immediately before the magnetic force change control, the clutch is slightly slipped so that the clutch differential speed is equal to or lower than the allowable differential speed and the clutch differential torque is equal to or lower than the insensible differential torque.

[0018] The inventors have studied the relationship between the occurrence of torque shock and the transmission torque characteristics of a clutch and have found that when a clutch having specific transmission torque characteristics further has a predetermined clutch characteristic, both torque shock and slip loss can be effectively suppressed and minimized. This control device has such specific transmission torque characteristics and predetermined clutch characteristics.

[0019] Therefore, according to this control device, it is possible to slightly slip the clutch so that the clutch differential speed is equal to or lower than the allowable differential speed and the clutch differential torque is equal to or lower than the insensible differential torque just before the magnetic force change control is performed, and in this way it is possible to effectively suppress both the torque shock and the slip loss, which were previously thought to be difficult to achieve at the same time. In other words, the application of the disclosed technology improves the performance of electric vehicles.

[0020] In the case where the clutch further has a transmission torque variation characteristic in which the transmission torque varies as the fastening torque fluctuates within a predetermined error range due to variation in actual oil pressure relative to the target oil pressure, it is preferable for the clutch to have the transmission torque variation characteristic in a state including the negative clutch characteristic.

[0021] This makes it possible to suppress both torque shock and slip loss even when hydraulic pressure fluctuates, further improving the performance of electric vehicles.

[0022] During the clutch slip control executed before the magnetic force change control, a pre-stage feedback control may be executed so that the clutch difference rotation speed converges to a predetermined target difference rotation speed within a range equal to or less than the allowable difference rotation speed.

[0023] This allows the minute slippage of the clutch described above to be controlled with relatively high precision, and allows the clutch to be quickly stabilized in an appropriate state.

[0024] During the clutch slip control executed after the magnetic force change control, instead of the torque control, power control may be executed for a predetermined period of time to control the motor torque so that the power output from the drive wheels coincides with a predetermined target power value, and then a subsequent feedback control may be executed so that the clutch difference rotational speed converges to the target difference rotational speed.

[0025] In this way, even if the state of the clutch becomes unstable due to the magnetic force change control, the state can be smoothly settled and the clutch can be quickly stabilized to a slight slip state.

[0026] During the clutch slip control that is executed after the magnetic force change control, a subsequent feedback control may be executed so that the clutch difference rotation speed is eliminated.

[0027] In this way, slip after magnetic force variation control can be quickly eliminated, and slip loss can be effectively suppressed. Effect of the Invention

[0028] According to the disclosed technology, it is possible to suppress both torque shock and slip loss, thereby improving the performance of electric vehicles. [Brief description of the drawings]

[0029] [Figure 1] 1 is a schematic diagram showing the main configuration of an automobile to which the disclosed technology is applied. [Diagram 2] FIG. 2 is a schematic cross-sectional view showing the configuration of a drive motor. [Diagram 3] FIG. 2 is a block diagram showing the TCU and its associated major input / output devices. [Figure 4] FIG. 2 is a block diagram showing an MCU and its associated main input / output devices. [Diagram 5] FIG. 4 is a diagram illustrating an example of an output range of a drive motor. [Figure 6] FIG. 2 is a simplified system diagram relating to control of a drive motor. [Figure 7] 5 is a flowchart showing an example of control of a drive motor. [Figure 8] 5 is a flowchart showing a flow of main processes of magnetic force change control. [Figure 9] 11A and 11B are diagrams for explaining the occurrence of a torque shock. [Figure 10] FIG. 1 is a diagram for explaining the blowing up phenomenon. [Figure 11] FIG. 4 is a diagram for explaining the transmission torque characteristics of a clutch. [Figure 12] 11 is a time chart of a control example to which the disclosed technology is applied. [Figure 13] 13 is a flowchart of a control example corresponding to FIG. 12. [Figure 14] 14 is a flowchart continuing from FIG. 13. [Figure 15] 13 is a time chart when the hydraulic pressure varies in the control example of FIG. 12. [Figure 16] 13 is a time chart when the hydraulic pressure varies in the control example of FIG. 12. [Figure 17] 14 is a flowchart continuing from FIG. 13 in a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] The disclosed technology will now be described, however, the following description is merely exemplary in nature.

[0031] <Electric vehicles> FIG. 1 shows an automobile 1 (an example of an electric vehicle) to which the disclosed technology is applied. The automobile 1 is a hybrid vehicle capable of running on electric power. The automobile 1 is equipped with an engine 2 and a drive motor 3 as its drive source. These work together to drive two wheels (drive wheels 4R) located symmetrically on the left and right of the four wheels 4F, 4F, 4R, 4R. This causes the automobile 1 to run. Note that the automobile 1 may be an electric vehicle equipped with only the drive motor 3. The automobile 1 may also be a four-wheel drive vehicle.

[0032] In the case of this automobile 1, the engine 2 is disposed at the front of the vehicle body, and the drive wheels 4R are disposed at the rear of the vehicle body. In other words, this automobile 1 is a so-called FR vehicle. Furthermore, in the case of this automobile 1, the engine 2 is the main driving source rather than the drive motor 3, and the drive motor 3 is used to assist the driving of the engine 2 (a so-called mild hybrid). The drive motor 3 is also used not only as a driving source, but also as a generator during regeneration.

[0033] In addition to an engine 2 and a drive motor 3, the automobile 1 is equipped with drive system devices such as an intermediate clutch 5, an inverter 6, a transmission 8, a differential gear 9, and a battery 10. The automobile 1 is also equipped with control system devices such as an engine control unit (ECU) 20, a motor control unit (MCU) 21, a transmission control unit (TCU) 22, a brake control unit (BCU) 23, and a general control unit (GCU) 24. An engine revolution sensor 50, a motor revolution sensor 51, a current sensor 52, a magnetic sensor 53, an accelerator sensor 54, a transmission sensor 55, and the like are also installed in the automobile 1 in association with the control system devices.

[0034] (Drive system device) The engine 2 is an internal combustion engine that burns gasoline as fuel. The engine 2 is also a so-called four-stroke engine that generates rotational power by repeating cycles of intake, compression, expansion, and exhaust. There are various types and forms of the engine 2, such as a diesel engine, but the technology disclosed herein is not particularly limited to the type or form of the engine.

[0035] In this automobile 1, the engine 2 is disposed in the approximate center in the vehicle width direction with the output shaft that outputs rotational power facing the front-rear direction of the vehicle body. The automobile 1 is equipped with various devices and mechanisms associated with the engine 2, such as an intake system, an exhaust system, and a fuel supply system, but these are not shown and will not be described.

[0036] The drive motor 3 is disposed in series behind the engine 2 via an intermediate clutch 5. The drive motor 3 is a permanent magnet type synchronous motor that is driven by three-phase AC. As shown in a simplified form in Fig. 2, the drive motor 3 is mainly composed of a motor case 31, a shaft 32, a rotor 33, a stator 34, etc.

[0037] Motor case 31 is a container having a cylindrical space therein with its front and rear end faces sealed, and is fixed to the body of automobile 1. Rotor 33 and stator 34 are housed in motor case 31. Shaft 32 is axially supported by motor case 31 so as to be freely rotatable, with its front and rear ends protruding from motor case 31.

[0038] An intermediate clutch 5 is provided so as to be interposed between a front end of the shaft 32 and the output shaft of the engine 2. The intermediate clutch 5 is configured to be switchable between a state in which the output shaft of the engine 2 and the shaft 32 are connected (engaged state) and a state in which the output shaft of the engine 2 and the shaft 32 are separated (disengaged state).

[0039] The rear end of the shaft 32 is connected to an input shaft 80 of the transmission 8. A second intermediate clutch may be provided between the shaft 32 and the input shaft 80 of the transmission 8.

[0040] The rotor 33 is a cylindrical member formed by laminating multiple metal plates each having an axial hole in the center. The rotor 33 is integrated with the shaft 32 by fixing the middle part of the shaft 32 to the axial hole of the rotor 33.

[0041] Magnets 35 are installed around the entire outer periphery of rotor 33. Magnets 35 are configured so that different magnetic poles, i.e., S poles and N poles, are alternately arranged at equal intervals in the circumferential direction. Magnet 35 may be configured as one cylindrical magnet having multiple magnetic poles, or may be configured as multiple arc-shaped magnets that make up each magnetic pole.

[0042] Furthermore, in this drive motor 3, the magnet 35 is configured so that the magnitude of the magnetic force can be changed between large and small (variable magnetic force magnet 35). Normally, a magnet (permanent magnet) with large coercive force (resistance) and capable of retaining its magnetic force for a long period of time is used in this type of drive motor 3. In this drive motor 3, a permanent magnet with small coercive force is used as the variable magnetic force magnet 35 so that the magnetic force can be changed relatively easily.

[0043] There are various types of permanent magnets, such as ferrite magnets, neodymium magnets, samarium-cobalt magnets, and alnico magnets, and they have various holding powers. The type and material of the variable magnetic force magnet 35 can be selected according to the specifications and are not particularly limited. In addition, it is not necessary for all magnets to be variable magnetic force magnets 35, and permanent magnets may be included.

[0044] A cylindrical stator 34 (inner rotor type) is installed around the rotor 33 with a small gap between them. The stator 34 has a stator core 34a formed by laminating multiple metal plates, and multiple coils 36 formed by winding electric wires around the stator core 34a.

[0045] The stator core 34a is provided with a plurality of teeth 34b that radiate inward, and a plurality of coils 36 are formed by winding electric wires around these teeth 34b in a predetermined order. These coils 36 constitute a three-phase coil group consisting of U-phase, V-phase, and W-phase.

[0046] To energize the coil group of each phase, a connection cable 36a is led out from each of the coil groups of each phase to the outside of the motor case 31. These connection cables 36a are connected to a battery 10 mounted on the vehicle as a driving power source via an inverter 6. In the case of this automobile 1, the battery 10 is a DC battery with a rated voltage of 50V or less, specifically 48V.

[0047] The battery 10 supplies DC power to the inverter 6. The inverter 6 converts the DC power into three-phase AC and supplies it to the drive motor 3. This causes the rotor 33 to rotate, and the power (rotational power) of the drive motor 3 is output to the transmission 8 via the shaft 32.

[0048] In the case of this automobile 1, the transmission 8 is a multi-stage automatic transmission (so-called AT). As shown in Fig. 1, the transmission 8 has an input shaft 80 at one end, which is connected to the drive motor 3 (shaft 32). The other end of the transmission 8 has an output shaft 81 which rotates independently of the input shaft 80. A transmission mechanism including a torque converter 84, a plurality of planetary gear mechanisms 82, and a plurality of transmission clutches 83 (including brakes) is incorporated between the input shaft 80 and the output shaft 81.

[0049] By switching these speed change mechanisms, it is possible to switch between forward and reverse, and to change the rotation speed between the input shaft 80 and the output shaft 81 of the transmission 8 to a different speed, that is, to change the gear ratio.

[0050] For example, an input side 83a of each transmission clutch 83 is configured to be connectable to an input shaft 80 via a torque converter 84. An output side 83b of each transmission clutch 83 is connected to an output shaft 81 via a corresponding planetary gear mechanism 82. When a specific transmission clutch 83 is selected and engaged, the input shaft 80 and output shaft 81 of the transmission 8 are connected via the transmission clutch 83 and the corresponding planetary gear mechanism 82. This changes the gear ratio, etc.

[0051] The output shaft 81 is connected to a differential gear 9 via a propeller shaft 11 that extends in the front-rear direction of the vehicle body and is arranged coaxially with the output shaft 81. A pair of drive shafts 13, 13 that extend in the vehicle width direction and are connected to the left and right drive wheels 4R, 4R are connected to the differential gear 9. The rotational power output through the propeller shaft 11 is distributed by the differential gear 9 and then transmitted to each drive wheel 4R through the pair of drive shafts 13, 13. A brake 14 is attached to each of the wheels 4F, 4F, 4R, 4R to brake their rotation.

[0052] (Control system equipment) The automobile 1 is provided with the above-mentioned units, ECU 20, MCU 21, TCU 22, BCU 23, and GCU 24, in order to control the running of the automobile 1 in response to the driver's operation. Each of these units is composed of hardware such as a processor, memory, and interface, and software such as a database and a control program. Each of these units is connected, for example, by a CAN (Controller Area Network), and is configured to be able to electrically communicate with one another.

[0053] The ECU 20 is a unit that mainly controls the operation of the engine 2. The MCU 21 is a unit that mainly controls the operation of the drive motor 3. The TCU 22 is a unit that mainly controls the operation of the transmission 8. The BCU 23 is a unit that mainly controls the operation of the brake 14. The GCU 24 is electrically connected to the ECU 20, MCU 21, TCU 22, and BCU 23, and is a higher-level unit that comprehensively controls these.

[0054] The "control device" in the disclosed technology is composed of these units. In particular, the MCU 21, which mainly controls the operation of the drive motor 3, and the TCU 22, which mainly controls the operation of the transmission 8, constitute the main components of the control device. These units work together to perform clutch slip control, which will be described later.

[0055] The engine revolution sensor 50 is attached to the engine 2, detects the revolution speed of the engine 2, and outputs the detected revolutions to the ECU 20. The motor revolution sensor 51 is attached to the drive motor 3, and detects the revolution speed and rotation position of the drive motor 3, and outputs the detected revolutions to the MCU 21. The current sensor 52 is attached to the connection cable 36a, and detects the value of the current flowing through each coil 36, and outputs the detected revolutions to the MCU 21.

[0056] The magnetic sensor 53 is attached to the drive motor 3, and detects the magnetic force of the variable magnetic magnet 35, and outputs the result to the MCU 21. The accelerator sensor 54 is attached to the accelerator pedal (accelerator pedal 15) that the driver depresses when driving the automobile 1, and detects the accelerator opening degree corresponding to the output required to drive the automobile 1, and outputs the result to the ECU 20. The transmission sensor 55 detects the rotation speed and engagement torque of each transmission clutch 83, the rotation speed of the output shaft 81, and the like, and outputs the result to the TCU 22.

[0057] Based on the detection value signals input from these sensors, each unit cooperates to control each device in the drive system, thereby running the automobile 1. For example, when the automobile 1 runs using the driving force of the engine 2, the ECU 20 controls the operation of the engine 2 based on the detection values ​​of the accelerator sensor 54 and the engine revolution sensor 50.

[0058] Then, the TCU 22 controls the intermediate clutch 5 to be in an engaged state, and switches the speed change mechanism of the transmission 8 in accordance with the driving state of the automobile 1. When braking the automobile 1, the BCU 23 controls the brakes 14. When braking by regeneration, the TCU 22 controls the intermediate clutch 5 to be in a disengaged state or a partially engaged state, and engages a predetermined transmission clutch 83 of the transmission 8. Then, the MCU 21 controls the drive motor 3 to generate electricity and recover the electricity to the battery 10.

[0059] 3 shows the TCU 22 and its related main input / output devices. The TCU 22 is provided with an intermediate clutch control unit 22a and a transmission clutch control unit 22b as functional components, which are implemented by hardware and software. The intermediate clutch control unit 22a controls the operation of the intermediate clutch 5. The transmission clutch control unit 22b controls the operation of each of the transmission clutches 83.

[0060] <Drive motor control> The MCU 21 controls the automobile 1 to run using the power output by the drive motor 3, either with the drive motor 3 outputting alone or with the output of the engine 2 being assisted as necessary.

[0061] Specifically, the ECU 20 sets the torque to be output by the engine 2 based on the detected values ​​of the accelerator sensor 54, the engine revolution sensor 50, etc. In accordance with this, the GCU 24 sets a torque demand (demanded torque) for the drive motor 3 within a predetermined output range in accordance with a preset output distribution ratio between the engine 2 and the drive motor 3. The MCU 21 controls the drive motor 3 so that the requested torque is output.

[0062] 4 shows the MCU 21 and its related main input / output devices. The MCU 21 is provided with a motor output control unit 21a and a magnetization control unit 21b as functional components, which are implemented by hardware and software. The motor output control unit 21a has a function of controlling the drive of the drive motor 3, and controls the drive current flowing through the coil 36 to cause the drive motor 3 to output the required power.

[0063] On the other hand, the magnetization control unit 21b has a function of increasing the power factor of the drive motor 3, and changes the magnetic force of the variable magnetic force magnet 35 by controlling the magnetization current flowing through the coil 36. Specifically, the magnetic force of the variable magnetic force magnet 35 is changed so that the magnetic force of the variable magnetic force magnet 35 approximately matches the electromagnetic force generated in the coil 36 by the drive current.

[0064] The power factor is the ratio of effective power (power actually consumed) to apparent power (power supplied to the drive motor 3). If the power factor is low, a large current must be passed to obtain the same output, and the motor must be accordingly larger. Therefore, by increasing the power factor of the drive motor 3, the drive motor 3 can be made lighter and more compact. Furthermore, if the power factor is increased, the power generation during regeneration can also be increased.

[0065] (Drive motor output range) 5 illustrates an example of the output range of the drive motor 3. The output range is defined by an upper load line indicating the upper limit of the torque (load) for each rotation speed.

[0066] Specifically, in the low RPM range up to a certain RPM (r1), the upper limit of the torque is kept at a maximum (T2). In the medium and high RPM ranges, where the RPM is higher than the low RPM range, the upper limit of the torque is gradually decreased until the RPM reaches the upper limit (r2).

[0067] Data such as maps and tables that define such output ranges are preset in the MCU 21. The motor output control unit 21a controls the drive motor 3 within the output range by referring to the data.

[0068] Furthermore, the output range of the drive motor 3 is divided into a plurality of magnetized regions. The magnetization control unit 21b is configured to change the magnetic force of the variable magnetic magnet 35 in accordance with each of these magnetized regions.

[0069] 5, in this embodiment, the output range of the drive motor 3 is divided into four magnetized regions Rm, namely, first to fourth magnetized regions Rm. Specifically, the output range is divided into a first magnetized region Rm1 with a high load that is biased toward the low rotation side and includes a maximum torque value T2, a second magnetized region Rm2 that spreads from the low rotation side to the high rotation side and has a torque peak at medium rotation at a lower load than the first magnetized region Rm1, a third magnetized region Rm3 with a torque peak shifted to the high rotation side at a lower load than the second magnetized region Rm2, and a fourth magnetized region Rm4 with a lower load than the third magnetized region Rm3 and including a torque (torque that does not contribute to the running of the automobile 1) T1 at which the drive motor 3 runs idle.

[0070] In each of the magnetized regions Rm, an optimal magnetic force value (magnetic force optimum value) that achieves a high power factor is set in correspondence with the respective output. For example, in the first magnetized region Rm1, the magnetic force of the variable magnetic force magnet 35 in the initial state is set as the magnetic force optimum value (first magnetic force optimum value). In the second magnetized region Rm2, a magnetic force optimum value lower than the first magnetic force optimum value is set (second magnetic force optimum value). In the third magnetized region Rm3, a third magnetic force optimum value lower than the second magnetic force optimum value is set, and in the fourth magnetized region Rm4, a fourth magnetic force optimum value lower than the third magnetic force optimum value is set.

[0071] The magnetization control unit 21b predicts the optimal magnetized region Rm based on the driving state of the automobile 1, and when the magnetized region Rm transitions to another adjacent magnetized region Rm, changes the magnetic force of the magnetic force variable magnet 35 to a magnetic force optimal value corresponding to the magnetized region Rm. For example, when transitioning from the first magnetized region Rm1 to the second magnetized region Rm2, a demagnetization process is executed in the drive motor 3, and the magnetic force of the magnetic force variable magnet 35 is changed from the first magnetic force optimal value to the second magnetic force optimal value.

[0072] Also, for example, when transitioning from the third magnetization region Rm3 to the second magnetization region Rm2, a magnetization process is executed in the drive motor 3, and the magnetic force of the variable magnetic force magnet 35 is changed from the third magnetic force optimum value to the second magnetic force optimum value.

[0073] (Specific example of drive motor control) FIG. 6 shows a simplified system diagram relating to the control of the drive motor 3. FIG. 7 shows an example of the control of the drive motor 3 performed by the MCU 21. With reference to these diagrams, a specific flow of control of the drive motor 3 will be described. Note that the drive motor 3 is driven by a torque current command Iq * and excitation current command Id * It is controlled by vector control using

[0074] When the automobile 1 is in a state in which it can run, the MCU 21 constantly receives detection values ​​from the current sensor 52, the motor rotation sensor 51, and the magnetic sensor 53 (step S1). Similarly, the ECU 20 constantly receives detection values ​​from the accelerator sensor 54 and the engine rotation sensor 50.

[0075] The GCU 24 obtains the detection value of the accelerator sensor 54 from the ECU 20, and sets the torque (required torque) required of the drive motor 3 out of the torque to be output to the drive wheels 4R in accordance with a preset distribution ratio of the output between the engine 2 and the drive motor 3. The GCU 24 issues a command (torque command value T * ) to MCU 21.

[0076] That is, the MCU 21 controls the output of the drive motor 3 based on a predetermined target torque (so-called torque control). Through torque control, the torque (motor torque) output by the drive motor 3 is controlled so as to match the target torque. Therefore, when the above-mentioned command is input while the automobile 1 is running, the MCU 21 controls the drive motor 3 with the required torque as the target torque. Through torque control of the drive motor 3, the automobile 1 runs in accordance with the driver's request.

[0077] When the magnetized region Rm is shifted as described above while the automobile 1 is in operation, the torque control is interrupted and control is executed to apply a high voltage to the coil 36 of the drive motor 3 (magnetic force change control). The magnetic force of the magnetic force variable magnet 35 is changed by the magnetic force change control.

[0078] Specifically, the MCU 21 (motor output control unit 21a) calculates a torque command value T * When the command Idq is input (Yes in step S2), a command (drive current command value Idq) is output to output the amount of change in the drive current (torque current component) that generates the torque. * ) (step S3). In addition, the MCU 21 (magnetization control unit 21b) executes a calculation process of a command (magnetization state command value Φ* ) (step S4). The magnetization control unit 21b executes the calculation process of the magnetization state command value Φ * Based on this, a command (magnetic current command value Idq) that outputs a torque current component corresponding to the change in magnetic force of the magnetic variable magnet 35 is generated. * ) is calculated (step S5).

[0079] The MCU 21 calculates the drive current command value Idq * and magnetic current command value Idq * Based on this, it is determined whether or not the magnetic force of the magnetic force variable magnet 35 needs to be changed (step S6). For example, as described above, if the magnetized region Rm transitions to another magnetized region Rm when the requested torque is output, it is determined that the magnetic force of the magnetic force variable magnet 35 needs to be changed, and if the magnetized region Rm is located in the same magnetized region Rm even when the requested torque is output, it is determined that the magnetic force of the magnetic force variable magnet 35 does not need to be changed.

[0080] If the MCU 21 determines that it is not necessary to change the magnetic force of the magnetic force variable magnet 35, it determines whether the output torque is greater than the torque T1 at which the drive motor 3 runs idle (step S7). If the output torque is greater than the torque T1, the MCU 21 controls the drive motor 3 by normal vector control.

[0081] That is, the motor output control unit 21a outputs a command (voltage command value Vuvw * ) is calculated (step S8). Then, a switching command value is calculated by PWM control (step S9).

[0082] The switching command value is output to the inverter 6 through a driver circuit, whereby multiple switching elements are controlled to be turned on and off inside the inverter 6. As a result, a predetermined three-phase AC (drive current) is passed through each coil group, and the drive motor 3 rotates with the required torque (step S10).

[0083] On the other hand, when the MCU 21 determines that the magnetic force of the magnetic force variable magnet 35 needs to be changed (No in step S6), the magnetization control unit 21b executes magnetic force change control (step S11).

[0084] Furthermore, even if the MCU 21 determines that it is not necessary to change the magnetic force of the magnetic force variable magnet 35, if it determines that the output torque is equal to or less than the torque T1 at which the drive motor 3 runs idle (No in step S7), the magnetization control unit 21b executes magnetic force change control (step S11).

[0085] That is, when the required amount of rotational power of the drive motor 3 becomes almost 0 (zero), the magnetic force of the variable magnetic magnet 35 is changed (reset) to the initial state. In the case of the automobile 1, for example, there are cases where the accelerator pedal 15 is suddenly depressed from an idling state or a stopped state, causing rapid acceleration.

[0086] In the case of the variable magnetic force magnet 35, the magnetic force in the initial state is set high to match the high load, so by resetting the magnetic force during idle operation, the drive motor 3 can be driven appropriately even when such rapid acceleration is performed.

[0087] 8 shows a flow of main processing of the magnetic force change control. When the magnetic force change control is requested, the magnetization control unit 21b calculates a magnetization state command value Φ * Based on this, the direction of the magnetization process is determined. That is, it is determined whether to execute a process to increase the magnetic force of the magnetic force variable magnet 35 (magnetization process) or to execute a process to decrease the magnetic force of the magnetic force variable magnet 35 (demagnetization process). The magnetization control unit 21b further specifies the amount of change in the magnetic force that is increased or decreased.

[0088] Then, the magnetization control unit 21b determines whether the position (position in the direction of rotation) of the rotor 33 relative to the stator 34 is suitable for the magnetization process based on the detection value of the motor rotation sensor 51 (step S21), and outputs a magnetization current when the rotor 33 is in an appropriate position (step S22). The magnetization current is a pulsed current that generates an electromagnetic force larger than the coercive force of the variable magnetic force magnet 35. The directions of the magnetic field lines of the electromagnetic force are opposite between the magnetization process and the demagnetization process.

[0089] The magnetization control unit 21b controls the magnetic force of the variable magnetic magnet 35 to be equal to or greater than the magnetization state command value Φ * (step S23), and executes the magnetization process until the magnetic force of the variable magnetic force magnet 35 becomes substantially the same as the magnetic force optimum value. When resetting the magnetic force of the variable magnetic force magnet 35, executes the magnetization process until the magnetic force becomes substantially the same as the initial magnetic force.

[0090] Then, when the magnetic force of the variable magnetic force magnet 35 becomes substantially the same as its optimum magnetic force value or the initial magnetic force, the magnetic force change control is terminated, and the drive motor 3 is controlled by normal vector control as shown in FIG. 7 (steps S8 to S10).

[0091] <Transmission clutch control> As described above, in this automobile 1, the magnetic force change control is executed even while the automobile 1 is being driven. If the magnetic force change control is executed while the automobile 1 is being driven, there is a concern that a torque shock may occur in the traveling automobile 1, causing the driver to feel uncomfortable.

[0092] The upper diagram of FIG. 9 illustrates an example of the change over time of the motor torque Tm during magnetic force change control. In this example, a magnetization process (one example of magnetic force change control) is executed during the period from time t1 to t1'. The period from t1' to t2 is a period in which the change in magnetic force is confirmed and control (learning control) is executed to learn the driving current value (the value of the q-axis current) so that it corresponds to the magnetic force after magnetization, thereby making the motor torque Tm match the required torque. The learning control is control associated with the change in magnetic force and is included in the magnetic force change control. Ta is the required torque. Since the drive motor 3 is torque controlled while the automobile 1 is traveling, the motor torque Tm before and after the execution of the magnetic force change control matches the required torque Ta.

[0093] Tt is the clutch engagement torque in the transmission 8. The clutch engagement torque Tt is the engagement torque of the transmission clutch 83 that connects the input shaft 80 and the output shaft 81 of the transmission 8. The clutch engagement torque Tt is adjusted by well-known hydraulic control. Specifically, if the hydraulic pressure supplied to the transmission 8 is reduced, the clutch engagement torque Tt becomes smaller, and if the hydraulic pressure supplied to the transmission 8 is increased, the clutch engagement torque Tt becomes larger.

[0094] In order to reliably transmit the motor torque Tm to the drive wheels 4R, the clutch engagement torque Tt is usually controlled to be sufficiently higher than the required torque Ta (clutch full engagement control). The hydraulic pressure supplied to the transmission 8 during clutch full engagement control is, for example, 1000 kPa, and is at least 500 kPa or more.

[0095] In other words, under clutch full engagement control, the transmission clutch 83 is fully engaged, the rotation speeds of both the input side 83a and the output side 83b of the transmission clutch 83 are the same, and the torque (input torque) of the input side 83a input to the transmission clutch 83 and the torque (output torque) of the output side 83b output from the transmission clutch 83 are also in a state where they match the required torque Ta.

[0096] During magnetic force change control, a magnetizing current (d-axis current) is passed through the coil 36 to generate a large electromagnetic force. This causes a high voltage that is much higher than the drive voltage to be applied to the drive motor 3. Therefore, as shown in the upper diagram of FIG. 9, during magnetic force change control, a high peak-shaped motor torque Tm that is much higher than the required torque Ta is output from the drive motor 3. As a result, under clutch full engagement control, a torque shock occurs in the traveling automobile 1, which may cause the driver to feel uncomfortable.

[0097] In order to suppress such torque shock, it is conceivable to slip the transmission clutch 83 when executing the magnetic force change control. That is, the hydraulic pressure supplied to the transmission 8 is lowered during the period from before to after the magnetic force change control. By doing so, the clutch engagement torque Tt is reduced, and the clutch engagement torque Tt is controlled to match the required torque Ta (clutch slip control before improvement).

[0098] Specifically, as shown in the lower diagram of Fig. 9, immediately before (at time t0) the start of magnetic force change control (at time t1), clutch slip control is executed instead of clutch full engagement control. This reduces the clutch engagement torque Tt, causing the transmission clutch 83 to slip. As a result, even if a high motor torque Tm is output from the drive motor 3 by the magnetic force change control, torque exceeding the required torque Ta is prevented from being transmitted to the drive wheels 4R. As a result, torque shock caused by the magnetic force change can be suppressed.

[0099] (Rotational surge) However, when the transmission clutch 83 is caused to slip, a phenomenon occurs in which the rotation of the drive motor 3 increases suddenly (so-called "revving up").

[0100] Fig. 10 shows the relationship between motor torque Tm and motor rotation speed Rm during magnetic force change control. Note that since the output of the engine 2 is not taken into consideration here, the motor rotation speed Rm is also the rotation speed of the input shaft 80 of the transmission 8. The motor torque Tm corresponds to the torque input to the transmission 8 (torque at the input side 83a of the transmission clutch 83: input torque). The clutch engagement torque Tt is controlled to match the required torque Ta, and therefore corresponds to the torque output from the transmission 8 (torque at the output side 83b of the transmission clutch 83: output torque).

[0101] Before the magnetic force change control is executed, the drive motor 3 rotates at a predetermined rotation speed Ra. At this time, the transmission clutch 83 being used is fully engaged, so both the input side 83a and the output side 83b of the transmission clutch 83 also rotate at the rotation speed Ra. The output shaft 81 of the transmission 8 rotates at a rotation speed changed by the planetary gear mechanism 82 corresponding to the transmission clutch 83.

[0102] As shown in Fig. 10, if the transmission clutch 83 is effectively slipped during magnetic force change control, the drive motor 3 will be in an idling state, and the motor rotation speed Rm will suddenly increase from the rotation speed Ra corresponding to the required torque Ta. The motor rotation speed Rm will further increase during learning control, and will remain high. If this phenomenon of sudden rotation is not resolved quickly, the transmission clutch 83 may be damaged by frictional heat caused by the slip.

[0103] Furthermore, in the torque control, the motor torque Tm is controlled so that it coincides with the target torque (required torque Ta) according to the rotation speed at that time. Therefore, after the rotation speed increases due to the revving, the rotation speed is maintained. In other words, the revving cannot be eliminated by the conventional torque control alone.

[0104] A possible measure to quickly eliminate the racing is to increase the clutch engagement torque Tt, which was set to match the required torque Ta, immediately after magnetic force change control. This reduces slippage, which in turn reduces the motor rotation speed Rm, eliminating the racing. However, this causes a reaction, which results in a high motor torque Tm being transmitted to the drive wheels 4R, resulting in a torque shock.

[0105] As another countermeasure, it is possible to reduce the target torque in the torque control to be smaller than the required torque Ta immediately after the magnetic force change control, thereby reducing the motor torque Tm itself. This will reduce the motor rotation speed Rm, thereby eliminating the racing.

[0106] However, this may cause the motor rotation speed Rm to drop below the initial rotation speed Ra. In this case, even if the motor torque Tm returns to the required torque by torque control after the revving is resolved, the motor rotation speed Rm does not return to the initial state. There is a concern that the driver may feel uncomfortable due to insufficient power of the drive motor 3.

[0107] Therefore, in the technology proposed earlier, after the magnetic force change control, power control is executed to control the motor torque Tm based on the power output from the drive motor 3, so that the torque and rotation speed output by the drive motor 3 can converge early.

[0108] <Suppression of both torque shock and slip loss> As a result of further investigation, the inventors have found that, although limited to a specific clutch, problems associated with magnetic force change control can be effectively suppressed.

[0109] In other words, the above-mentioned revving not only affects the durability of the transmission clutch, but also causes energy loss (slip loss) due to slip. Slip loss deteriorates the fuel efficiency of the automobile 1. Therefore, it is preferable to suppress not only the torque shock but also the slip loss. However, slip is unavoidable in suppressing the torque shock, and it was thought that it was difficult to achieve both.

[0110] However, when the present inventors studied the relationship between the occurrence of torque shock and the transmission torque characteristics of the transmission clutch 83, they found that when certain conditions are met in a transmission clutch 83 having specific transmission torque characteristics, both the torque shock and slip loss described above can be effectively suppressed and minimized. The details of this will be explained below.

[0111] (Clutch transmission torque characteristics) An example of the torque characteristics (transmission torque characteristics) transmitted when the clutch is engaged is shown in Fig. 11. The transmission torque characteristics differ depending on the type and performance of the clutch, but the disclosed technology can be applied to a clutch having the transmission torque characteristics shown in Fig. 11.

[0112] As described above, in order to suppress the torque shock caused by the magnetic force change control, it is necessary to slip the transmission clutch 83. To do this, it is necessary to significantly reduce the hydraulic pressure supplied to the transmission 8 from the hydraulic pressure during the clutch full engagement control, and to relax the clutch engagement torque.

[0113] As shown in Fig. 5, in the case of this automobile 1, the magnetic force change control is executed when transitioning to another adjacent magnetized region Rm. The output torque (required torque Ta) at that time is generally within the range of T1 to T3 where the boundaries exist, and falls within a range of the intermediate torque (e.g., 80 to 50 Nm) with respect to the maximum torque T2. In other words, the magnetic force change control and the clutch slip control are executed with the output torque generally within this range.

[0114] Therefore, the transmission torque characteristics shown in Fig. 11 are assumed to be at the time of such clutch slip control. The vertical axis is output torque (Tout) and the horizontal axis is input torque (Tin). Graph G1 represents the torque transmitted from the input side to the output side of transmission clutch 83 when the hydraulic pressure is adjusted to 200 kPa and a clutch fastening torque corresponding to that is output to transmission clutch 83. Similarly, graph G2 represents the case where the hydraulic pressure is 210 kPa, and graph G3 represents the case where the hydraulic pressure is 190 kPa.

[0115] As shown in graphs G1 to G3, the transmission torque characteristics change depending on the hydraulic pressure, but the same clutch has the same transmission torque characteristics even if the hydraulic pressure is different. That is, the clutch has a region corresponding to low input torque (low transmission torque region RL), a region corresponding to high input torque (high transmission torque region RH), and a region (transition transmission torque region RM) that exists between the low transmission torque region and the high transmission torque region.

[0116] For example, looking at graph G1, in the low transmission torque region RL (region where the input torque is 35 Nm or less), the input torque and the output torque are the same value. In other words, the transmission clutch 83 is in an engaged state, and all of the input torque is transmitted and output. In the transition transmission torque region RM (region where the input torque is from 35 Nm to 50 Nm), the output torque is smaller than the input torque. In other words, the transmission clutch 83 is in a slipping state, and all but a portion of the input torque is transmitted and output.

[0117] In the high transmission torque region RH (region where the input torque is 50 Nm or more), the output torque approaches 45 Nm as the input torque increases. In other words, if the input torque increases any higher, the slip will simply increase and the increase in input torque will not be transmitted. The output torque will remain essentially unchanged at that value (corresponding to the upper limit transmission torque).

[0118] In other words, in the case of transmission clutch 83 having this transmission torque characteristic, by adjusting the hydraulic pressure to 200 kPa, the output torque can be limited to 45 Nm or less even if the input torque becomes high. Therefore, with this transmission clutch 83, when the output torque (required torque Ta) when magnetic force change control is required is 45 Nm, it is preferable to adjust the hydraulic pressure supplied to the transmission 8 to 200 kPa.

[0119] Then, hydraulic control is performed so that the clutch engagement torque Tt (corresponding to the upper limit transmission torque) coincides with 45 Nm, and the input torque (output torque of the drive motor) is set to 50 Nm taking slip loss into consideration. By doing so, even if a peak torque (shown as Tp1 in FIG. 11) occurs in the input torque due to magnetic force change control, the output torque can be limited to 45 Nm, which is the required torque Ta. Therefore, there is almost no shock torque (shown as Ts1 in FIG. 11) generated in the output torque due to the influence of the peak torque Tp1, and torque shock can be suppressed.

[0120] However, even in this case, there was an excess torque difference (50Nm-45Nm=5Nm) between the input torque and the output torque, resulting in slippage exceeding 100 rpm. Considering the impact on fuel economy, there was room for improvement in this slip loss.

[0121] In contrast, if the transmission clutch 83 has such transmission torque characteristics, specifically, a transition transmission torque region RM where the output torque is smaller than the input torque, then by having further specific clutch characteristics, it is possible to minimize both torque shock and slip loss, making it possible to suppress both torque shock and slip loss at the same time.

[0122] Specifically, the transmission clutch 83 further has clutch characteristics such that, in the transition transmission torque region RM, the clutch differential torque, which is the difference between the current output torque and the upper limit transmission torque, is equal to or less than a specific insensible differential torque, and the clutch differential rotational speed, which is the difference in rotational speed between the input side and output side of the clutch, is equal to or less than a specific allowable difference rotational speed.

[0123] Here, the insensible torque difference is the upper limit of the clutch torque difference that is unlikely to cause the driver to feel uncomfortable (for example, 7 Nm; the following description will be based on this value). The insensible torque difference is set in advance through experiments, etc., based on the human sensing limit.

[0124] The allowable difference speed is the upper limit of the clutch difference speed that is allowable as a slip loss from a comprehensive viewpoint of fuel efficiency (for example, 100 rpm; the following explanation is based on this value). The allowable difference speed is set in advance through experiments, etc., based on the energy gain and loss associated with the magnetic force change control.

[0125] When the magnetic force change control is executed while the automobile 1 is in operation, the torque (the above-mentioned peak torque) output from the drive motor 3 in association with the magnetic force change is instantaneously added to the output torque at that time. It is known that the added peak torque is a roughly constant value (for example, 15 Nm) in the case of this automobile 1.

[0126] Taking this into consideration, if we look at the transmission torque characteristics shown in Figure 11 following the example described above, for example, if the input torque is changed from 50 Nm to 35 Nm and the output torque is changed from 45 Nm to 35 Nm, the clutch differential rotation speed is zero, but due to the influence of the peak torque Tp2 at that time, a shock torque (Ts2) larger than the insensible differential torque is generated (10 Nm in this example).

[0127] In contrast, for example, if the input torque is 43 Nm and the output torque is 42 Nm, the clutch differential speed is smaller than 100 rpm (about 20 rpm in this example), and the shock torque (Ts3) caused by the peak torque Tp3 at that time can also be reduced (3 Nm in this example). In other words, both the torque shock and slip loss can be minimized, making it possible to simultaneously suppress both the torque shock and the slip loss.

[0128] On the other hand, for example, if the output torque is 38 Nm, it can be made below the insensible differential torque (45-38=7), but if the clutch characteristics cause the clutch differential speed to exceed 100 rpm, it is not possible to suppress both the torque shock and the slip loss.Also, if the output torque is 37 Nm, even if the clutch characteristics can make the clutch differential speed below 100 rpm, a shock torque of 8 Nm will be generated, exceeding the insensible differential torque, and this cannot be achieved in this case either.

[0129] Therefore, in order to suppress both torque shock and slip loss, it is a prerequisite that the transmission clutch 83 in question has clutch characteristics that satisfy the above-mentioned specific conditions in the transition transmission torque region.

[0130] Then, for a transmission clutch 83 having such specific clutch characteristics, the TCU 22 (transmission clutch control unit 22b) executes control (improved clutch slip control) to slightly slip the transmission clutch 83 so that the clutch difference rotation speed is equal to or lower than the allowable difference rotation speed and the clutch difference torque is equal to or lower than the insensible difference torque just before the magnetic force change control.

[0131] In the above-mentioned example, the hydraulic pressure of the transmission 8 is adjusted to 200 kpa. This causes the transmission clutch 83 to have the transmission torque characteristics shown in graph G1. If the torque is controlled so that the output torque is 42 Nm for an input torque of 43 Nm, the transmission clutch 83 can be slightly slipped at a clutch difference rotation speed of about 20 rpm.

[0132] Then, the magnetic force change control is started in this state where the transmission clutch 83 is slightly slipped (slight slip state).By doing so, not only the torque shock associated with the magnetic force change control but also the slip loss associated with suppressing the torque shock can be minimized, and it is possible to suppress both the torque shock and the slip loss.

[0133] (Variation characteristics of clutch transmission torque) As described above, the clutch engagement torque is adjusted by the hydraulic pressure supplied to the transmission 8. Specifically, the TCU 22 (transmission clutch control unit 22b) hydraulically controls the transmission 8 based on a predetermined target hydraulic pressure. As a result, the clutch engagement torque of the transmission clutch 83 is set to a required magnitude.

[0134] However, due to the mechanism of hydraulic control, there is a limit to its accuracy, and the hydraulic pressure actually supplied (actual hydraulic pressure) varies to a certain extent with respect to the target hydraulic pressure. Therefore, the transmission clutch 83 has a transmission torque variation characteristic in which the clutch engagement torque fluctuates within a predetermined error range (for example, ±4 Nm), and the transmission torque (output torque) in the transition transmission torque region RM also varies accordingly.

[0135] Therefore, in order to more effectively suppress both the torque shock and the slip loss, it is preferable to take into consideration the variation characteristics of the transmitted torque. Specifically, it is preferable that the transmission clutch 83 has the above-mentioned clutch characteristics in consideration of the variation characteristics of the transmitted torque.

[0136] Specifically, the input torque during magnetic force change control is increased by a large torque on top of the required torque, so the output torque reaches the upper limit transmission torque. The upper limit transmission torque also varies due to the variation in the clutch fastening torque caused by hydraulic control during the clutch slip control period. Therefore, the difference between the upper limit transmission torque, which takes this variation into account, and the output torque immediately before the clutch slip control, and the minimum output torque during the clutch slip control period must be within the insensitive torque difference (7 Nm).

[0137] In the example given above, when the clutch is slipped at a clutch differential rotation of 20 rpm during clutch slip control, if no variation occurs in the transmitted torque, the minimum output torque during that period must be set to 38 Nm or more, calculated by subtracting the insensitive differential torque of 7 Nm from the upper limit transmitted torque of 45 Nm.

[0138] If the deviation reaches its maximum on the positive side (+4 Nm), it must be set to 42 Nm or more, which is the upper limit transmission torque of 49 Nm minus the insensible torque difference of 7 Nm; if the deviation reaches its maximum on the negative side (-4 Nm), it must be set to 36 Nm or more, which is the output torque of 43 Nm just before clutch slip control minus the insensible torque difference of 7 Nm.

[0139] In other words, by satisfying the conditions of being less than the insensible differential torque and less than the allowable differential rotation speed, while taking into account the variation characteristics of the transmitted torque, it is possible to suppress both torque shock and slip loss even if the clutch engagement torque fluctuates due to variations in hydraulic pressure.

[0140] (Specific control examples) Fig. 12 shows a time chart of a specific control example corresponding to the above example. Fig. 13 and Fig. 14 show a flow chart showing the flow of main processes performed by the control device corresponding to the time chart. Note that here, the output is only from the drive motor 3, and the variation characteristics of the transmission torque are also taken into consideration, but an example is shown of a case where hydraulic control is appropriate (when there is no error in the clutch fastening torque).

[0141] In order to satisfy the conditions of being equal to or less than the corrected insensitive differential torque and the allowable differential rotation speed, an optimal clutch differential rotation speed (target differential rotation speed Rs, for example, 20 rpm) is preset in the control device (TCU 22) based on the above-mentioned clutch characteristics.

[0142] 12, the upper part is a time chart relating to the hydraulic pressure of the transmission 8. Pc represents the hydraulic pressure during full clutch engagement control, and Ps represents the target hydraulic pressure.

[0143] The middle part is a time chart relating to the torque of the transmission clutch 83. The dashed and dotted line L1 represents the input torque, the dashed and dotted line L2 represents the output torque, the solid line L3 represents the clutch engagement torque, and the dashed and dotted line L4 represents the upper limit output torque.

[0144] The lower part is a time chart relating to the clutch differential speed, which shows the difference between the speed of the input side 83a and the speed of the output side 83b of the transmission clutch 83.

[0145] 13, the control device (MCU 21) judges whether or not magnetic force change control is executed while the automobile 1 is in operation (step S30). If it is judged that magnetic force change control is executed, the TCU 22 sets the target hydraulic pressure Ps of the transmission 8 according to the required torque Ta at that time (step S31). As illustrated, if the required torque Ta at that time (the same applies to the input torque and the output torque) is 43 Nm, the target hydraulic pressure Ps is set to 200 kPa.

[0146] At this time, the transmission clutch 83 is under full clutch engagement control, so the hydraulic pressure Pc is high (for example, 1000 kPa). The TCU 22 starts clutch slip control and reduces the hydraulic pressure to the set target hydraulic pressure Ps. Accordingly, the clutch engagement torque also decreases (step S32, t0 to t1). As a result, the transmission clutch 83 begins to slip, and the clutch differential rotation speed increases.

[0147] Then, the MCU 21 starts a front-stage feedback control so as to converge to the slight slip state (step S33). Specifically, the MCU 21 adjusts the input rotation speed, that is, the rotation speed output by the drive motor 3, so that the clutch difference rotation speed actually measured or estimated based on the detection value of the transmission sensor 55 becomes equal to or less than the target difference rotation speed Rs (step S34).

[0148] The rotation speed of the drive motor 3 can be controlled with relatively high accuracy. Also, the clutch difference rotation speed can be quickly converged to the target difference rotation speed Rs. When the clutch difference rotation speed converges to 20 rpm, which is the target difference rotation speed Rs, the input torque and the output torque are stabilized at 43 Nm and 42 Nm, respectively, due to the transmission torque characteristics (t1 to t2).

[0149] In this state, the MCU 21 starts the magnetic force change control (step S35). When the magnetic force change control is executed, as described above, a high motor torque is instantaneously output from the drive motor 3, and the torque is added to the input torque (t2 to t3).

[0150] In response, the motor speed (input torque) increases, but because it is restricted by the upper limit transmission torque (45 Nm), the output torque only rises to 45 Nm. The shock torque at that time is 3 Nm, which is below the insensitive torque difference, as shown by arrow Y1 in Figure 12, and therefore cannot be sensed. Therefore, the torque shock can be effectively suppressed.

[0151] Although the clutch differential speed increases slightly, it can be suppressed to the allowable differential speed of 100 rpm or less. Therefore, slip loss can also be effectively suppressed.

[0152] The MCU 21 determines whether the magnetic force change control has ended (step S36). If the magnetic force change control has ended, the MCU 21 starts power control aiming at a slight slip state (step S37).

[0153] In the power control, torque control is executed so that the power output from the drive wheel 4R, that is, the product of the torque T and the rotation speed R of the drive wheel 4R, becomes a predetermined target power value (target power value) (t3 to t4). That is, in the power control, torque control is executed with the motor torque Tm corresponding to the target power value as the target torque, instead of the required torque Ta.

[0154] If the target power value is constant, when the motor rotation speed Rm is high, the target torque is accordingly low, and when the motor rotation speed Rm is low, the target torque is accordingly high. Therefore, unlike torque control, power control can adjust both the rotation speed and the torque in a well-balanced manner. As a result, the transmission clutch 83, whose rotation speed and torque have become unstable due to the magnetic force change control, quickly converges to a slight slip state.

[0155] Then, after a predetermined period of time has elapsed, when the clutch difference rotation speed reaches a predetermined difference rotation speed Rf that is greater than the target difference rotation speed Rs (Yes in step S38), the MCU 21 starts post-stage feedback control (step S39). Specifically, the input rotation speed, that is, the rotation speed output by the drive motor 3, is adjusted so that the clutch difference rotation speed converges to the target difference rotation speed Rs (step S40). This allows the clutch difference rotation speed to converge to the target difference rotation speed Rs more quickly, and the slight slip state can be maintained (t4 to t5).

[0156] Thereafter, the TCU 22 increases the hydraulic pressure of the transmission 8 to a normal hydraulic pressure, and returns to the state of clutch complete engagement control (step S41, t6).Then, the MCU 21 resumes the normal torque control (step S42).

[0157] (When hydraulic pressure fluctuates) 15 and 16 are time charts showing the hydraulic pressure variations in the above-mentioned control example. Except for the hydraulic pressure difference, the control is the same as that described above.

[0158] Figure 15 shows a time chart when the oil pressure varies up to its upper limit Pe1. As the oil pressure varies upward, the clutch engagement torque also falls within the error range. Due to the fluctuation in the transmission torque characteristics, the upper limit transmission torque indicated by L4 is 49 Nm.

[0159] As the hydraulic pressure deviates upward, the input torque, output torque, and differential speed also behave differently, but as shown by arrow Y2, the shock torque is approximately 6.5 Nm, which is the same as the insensitive differential torque, and cannot be detected. Therefore, torque shock can be effectively suppressed. Although an increase in the clutch differential speed is observed, it can be suppressed to 100 rpm or less, which is the allowable differential speed. Therefore, slip loss can also be effectively suppressed.

[0160] Figure 16 shows a time chart when the oil pressure varies to the lower limit Pe2. As the oil pressure varies downward, the clutch engagement torque also falls within the error range. Due to the fluctuation in the transmission torque characteristics, the upper limit transmission torque indicated by L4 is 41 Nm.

[0161] As the hydraulic pressure drops, the input torque, output torque, and differential speed also behave differently. In this case, the upper limit transmission torque is lower than the input torque and the output torque, so the torque difference generated in the slight slip state is larger than the torque difference generated in the magnetic force change control.

[0162] Therefore, the shock torque is as shown by the arrow Y3, but its magnitude is about 3 Nm, which is less than the insensitive differential torque, and cannot be detected. Therefore, the torque shock can be effectively suppressed. Although an increase in the clutch differential speed is observed, it can be suppressed to 100 rpm or less, which is the allowable differential speed. Therefore, the slip loss can also be effectively suppressed.

[0163] <Modification of control> In the above-described control example, the magnetic force change control is followed by power control to stabilize the disturbed state of the transmission clutch 83 and converge it to a slight slip state, and then feedback control is executed to quickly converge it to a slight slip state. This makes it possible to quickly return to a normal state while effectively suppressing torque shock even after the magnetic force change control.

[0164] In contrast, in the control of this modified example, control is performed so that slip is immediately eliminated after magnetic force change control in order to further reduce slip loss. Specifically, during clutch slip control executed after magnetic force change control, post-stage feedback control is executed so that the clutch differential rotation speed is eliminated. By applying the disclosed technology, revving is suppressed (the clutch differential rotation speed is small), so that disturbance of the transmission clutch 83 is small and power control can be omitted.

[0165] A flow chart of this control is shown in Fig. 17. This flow chart replaces the flow chart shown in Fig. 14 and is a sequel to Fig. 13.

[0166] In the control of this modified example, when the magnetic force change control is completed, the MCU 21 starts a post-stage feedback control so as to eliminate the clutch differential rotation speed (step S50). Specifically, the target clutch differential rotation speed in the feedback control is set to 0 (zero), and the rotation speed of the input side 83a of the transmission clutch 83, that is, the rotation speed output by the drive motor 3, is adjusted so that the clutch differential rotation speed converges to 0, that is, there is no slippage (step S51).

[0167] By doing so, as shown by the imaginary line Ln in FIG. 12, the clutch differential rotation speed can be eliminated in an extremely short time, and slip loss can be suppressed even further.

[0168] The technology disclosed is not limited to the above-described embodiment, but includes various other configurations. For example, there are many different configurations for the drive motor 3, the transmission 8, etc. The same is true for the automobile 1. Therefore, these configurations can be selected according to the specifications, and the technology disclosed can be applied according to the specifications. [Explanation of symbols]

[0169] 1. Automobiles (electric vehicles) 2 Engine 3 Drive motor 3 4R Drive Wheel 5 Intermediate clutch 8. Transmission 10 Battery 20 Engine Control Unit (ECU) 21 Motor control unit (MCU) 21a Motor output control section 21b Magnetization control section 22 Transmission Control Unit (TCU) 22a Intermediate clutch control section 22b Transmission clutch control unit 23 Brake Control Unit (BCU) 24 General Control Unit (GCU) 33 Rotor 34 Stator 35 Magnet (variable magnetic force magnet) 80 Input shaft 81 Output shaft 82 Planetary Gear Mechanism 83 Transmission clutch 83a Input side 83b Output side

Claims

1. A control device for an electric vehicle capable of running using electric power, the control device including a drive motor having a rotor whose magnetic poles are formed by a variable magnetic force magnet whose magnetic force can be changed, and a clutch disposed between the drive motor and a drive wheel, When the electric vehicle is traveling, a torque control is performed to control the motor torque output by the drive motor so that the motor torque matches a required torque required to be output to the drive wheels, and a clutch complete engagement control is performed to make the engagement torque of the clutch higher than both the input torque input to the clutch and the output torque output from the clutch. When a magnetic force change control is performed to change the magnetic force of the magnetic force variable magnet while the electric vehicle is in operation, a clutch slip control is performed in place of the clutch complete engagement control during the magnetic force change control to reduce the engagement torque to a value close to the output torque and the input torque. The clutch is With regard to the torque characteristics transmitted at the time of engagement, the clutch has a low transmission torque region in which the output torque and the input torque have the same value, a high transmission torque region in which the output torque remains unchanged at a predetermined upper limit transmission torque even if the input torque increases, and a transition transmission torque region that exists between the low transmission torque region and the high transmission torque region and in which the output torque is smaller than the input torque, The clutch further has a clutch characteristic in which, in the transitional transmission torque region, a clutch differential torque, which is the difference between the current output torque and the upper limit transmission torque, is equal to or less than a specific insensible differential torque set based on a human sensing limit, and a clutch differential rotation speed, which is the difference between the rotation speeds of the input side and the output side of the clutch, is equal to or less than a specific allowable difference rotation speed set based on energy gain or loss, The control device causes the clutch to slightly slip so that the clutch differential rotation speed is equal to or lower than the allowable differential rotation speed and the clutch differential torque is equal to or lower than the insensible differential torque immediately before the magnetic force change control.

2. 2. The control device according to claim 1, The clutch further has a transmission torque variation characteristic in which the transmission torque varies as the fastening torque varies within a predetermined error range due to a variation in an actual hydraulic pressure relative to a target hydraulic pressure, A control device in which the clutch has the clutch characteristics in a state including the variation characteristics of the transmission torque.

3. 3. The control device according to claim 1, a control device that executes a pre-stage feedback control during the clutch slip control executed before the magnetic force change control so that the clutch difference rotation speed converges to a predetermined target difference rotation speed within a range equal to or less than the allowable difference rotation speed.

4. 4. The control device according to claim 3, During the clutch slip control executed after the magnetic force change control, instead of the torque control, power control is executed for a predetermined period of time to control the motor torque so that the power output from the drive wheels coincides with a predetermined target power value, and then a subsequent feedback control is executed so that the clutch difference rotational speed converges to the target difference rotational speed.

5. 4. The control device according to claim 3, A control device that performs a post-stage feedback control so that the clutch difference rotation speed is eliminated when the clutch slip control is performed after the magnetic force change control.

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