Vehicle control device

Abstract

To provide a vehicle control device capable of inhibiting an overcurrent state of current that is being supplied to an electric motor even in a case where rotation of an internal combustion engine is not in synchronization with rotation of the electric motor.SOLUTION: An electronic control device 90 is for a vehicle 10 having an electric motor MG connected to an engine 12 via a belt 48. To start the engine 12 by cranking using the electric motor MG, the electronic control device determines, as a start torque Tmgsta to be outputted from the electric motor MG, a smaller torque between a first torque Tmg1 which is an output torque necessary for the electric motor MG calculated on the basis of an engine rotational speed Ne which is the rotational speed of the engine 12, and a second torque Tmg2 which is an output torque necessary for the electric motor MG calculated on the basis of an MG rotational speed Nmg which is the rotational speed of the electric motor MG.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a control device for a vehicle having an electric motor connected to an internal combustion engine via an endless annular transmission member. [Background technology]

[0002] In a vehicle having an electric motor connected to an internal combustion engine via a belt that is an endless annular transmission member, there is known a vehicle control device that sets the smaller of an output torque required by the electric motor to increase the rotation speed of the internal combustion engine, which is calculated based on the rotation speed of the internal combustion engine, and a limit torque of the electric motor to limit a current supplied to the electric motor, as a starting torque in starting control of the internal combustion engine. For example, one such control device is described in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-22867 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the output torque of the electric motor fluctuates greatly, such as in the start-up control of an internal combustion engine, the rotation of the internal combustion engine and the rotation of the electric motor may not be synchronized. The term "synchronization" used here means that the internal combustion engine and the electric motor connected via an endless annular transmission member rotate in conjunction with each other, and more specifically, means that when the rotation speed of the electric motor is converted to the rotation speed of the rotating shaft of the internal combustion engine according to a predetermined rotation ratio in a transmission device using an endless annular transmission member, the converted rotation speed of the electric motor and the rotation speed of the internal combustion engine match. When the rotation of the internal combustion engine and the rotation of the electric motor are not synchronized, even if the starting torque is set based on the rotation speed of the internal combustion engine, there is a risk that it is not possible to prevent the current supplied to the electric motor from becoming an overcurrent.

[0005] The present invention has been made against the background of the above circumstances, and its object is to provide a vehicle control device that can prevent the current supplied to the electric motor from becoming an overcurrent even when the rotation of the internal combustion engine and the rotation of the electric motor are not synchronized. [Means for solving the problem]

[0006] The gist of the first invention is a control device for a vehicle having an electric motor connected to an internal combustion engine via an endless annular transmission member, which, when cranking and starting the internal combustion engine using the electric motor, sets the smaller of a first torque, which is an output torque required by the electric motor calculated based on the rotational speed of the internal combustion engine, and a second torque, which is an output torque required by the electric motor calculated based on the rotational speed of the electric motor, as the starting torque to be output from the electric motor. Effect of the Invention

[0008] According to the vehicle control device of the first aspect of the invention, when the internal combustion engine is cranked and started by the electric motor, the smaller of a first torque, which is an output torque required by the electric motor calculated based on the rotation speed of the internal combustion engine, and a second torque, which is an output torque required by the electric motor calculated based on the rotation speed of the electric motor, is set as a starting torque to be output from the electric motor. When the rotation speed of the electric motor converted into the rotation speed of the rotating shaft of the internal combustion engine is higher than the rotation speed of the internal combustion engine, the output torque of the electric motor can be reduced, and when the converted rotation speed of the electric motor is lower than the rotation speed of the internal combustion engine, the output torque of the electric motor is prevented from becoming higher than necessary. This prevents the current supplied to the electric motor from becoming an overcurrent.

[0010] No. 2 According to the vehicle control device of the present invention, ClearlyIn the above-mentioned system, the tension of the endless annular transmission member is adjusted by a tensioner, and even if the rotational speed of the electric motor, converted into the rotational speed of the rotating shaft of the internal combustion engine, repeatedly rises and falls due to the elastic component of the tensioner relative to the rotational speed of the internal combustion engine, the current supplied to the electric motor is prevented from becoming an overcurrent. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic configuration diagram of a vehicle equipped with an electronic control device according to an embodiment of the present invention, and is also a functional block diagram showing essential parts of control functions for various controls in the vehicle. [Diagram 2] FIG. 2 is a diagram illustrating the belt transmission device shown in FIG. [Diagram 3] 1 is a diagram showing an example of a relationship between the rotation speed of a motor and the output torque of the motor that is adjusted accordingly. [Figure 4] 2 is an example of a flowchart illustrating a main part of a control operation of the electronic control device shown in FIG. [Diagram 5] 5 is an example of a time chart in the case where the flowchart of FIG. 4 is executed when the engine in a stopped state is restarted. [Figure 6] 5 is an example of a time chart in a case where the flowchart in FIG. 4 is executed in a case where the engine is restarted during engine stop control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios and shapes of the various parts are not necessarily drawn accurately. EXAMPLES

[0013] FIG. 1 is a schematic diagram of a vehicle 10 equipped with an electronic control device 90 according to an embodiment of the present invention, and is also a functional block diagram showing the main parts of the control functions for various controls in the vehicle 10.

[0014] The vehicle 10 includes an engine 12, a transmission 18, an output shaft 24, a differential gear 26, a pair of axles 28, and drive wheels 30. The vehicle 10 also includes a belt transmission device 40, an electric motor MG, an inverter 50, a high-voltage battery 52, a DC / DC converter 54, a low-voltage battery 56, an electric load 58, an air compressor AC, and an electronic control device 90.

[0015] The engine 12 is a well-known internal combustion engine and is a driving force source for running the vehicle 10. The engine 12 is, for example, a gasoline engine, and an electronic control device 90 controls a throttle actuator, a fuel injection device, an ignition device, and the like provided in the engine 12 to control the engine torque Te [Nm] that is the output torque of the engine 12. In this specification, unless otherwise specified, the terms torque, power, driving force, and force (power) are synonymous.

[0016] The transmission 18 is configured with a known torque converter or automatic transmission, and a desired gear ratio is selected from a plurality of gear ratios γat by an electronic control device 90. An output shaft 24, which is an output rotating member of the transmission 18, is connected to a pair of drive wheels 30 via a differential gear 26 and a pair of axles 28.

[0017] The electric motor MG is a so-called motor generator, for example a three-phase synchronous motor generator.

[0018] The electric motor MG is connected to a high-voltage battery 52 via an inverter 50. The inverter 50 is a power supply circuit that converts direct current to alternating current and vice versa under the control of an electronic control device 90. For example, the inverter 50 converts direct current supplied from the high-voltage battery 52 into three-phase alternating current and outputs the three-phase alternating current to the electric motor MG, and converts the three-phase alternating current generated power Wg generated by the electric motor MG into direct current and outputs the direct current to the high-voltage battery 52.

[0019] The inverter 50 is controlled by the electronic control device 90, thereby controlling the MG torque Tmg [Nm] which is the torque output from the electric motor MG. For example, when the MG rotation speed Nmg [rpm] which is the rotation speed of the electric motor MG is in the positive direction, the MG torque Tmg is a power torque when it is a positive torque on the acceleration side, and is a regenerative torque when it is a negative torque on the deceleration side. When the MG torque Tmg is a power torque, for example, it means that a cranking torque is being output from the electric motor MG to the engine 12. When the MG torque Tmg is a regenerative torque, for example, the electric motor MG is made to generate electricity by the engine 12 and functions as an alternator.

[0020] The high voltage battery 52 is a chargeable and dischargeable secondary battery, and is mainly used to discharge (supply) electric power for driving the electric motor MG, and to charge the electric power Wg generated by the electric motor MG through regeneration.

[0021] The low-voltage battery 56 is a chargeable and dischargeable secondary battery, and is used mainly to supply power to electrical loads 58 including auxiliary devices (e.g., a throttle actuator, a fuel injector, an ignition device, various sensors, switches, etc.). Due to differences in use, the high-voltage battery 52 has a higher battery voltage than the low-voltage battery 56. For example, the low-voltage battery 56 has a voltage of 12 V, whereas the high-voltage battery 52 has a higher voltage.

[0022] The DC / DC converter 54 is a power supply circuit that is provided between the high-voltage battery 52 and the low-voltage battery 56 and that boosts or lowers the voltage of a direct current. For example, the DC / DC converter 54 lowers the voltage of the direct current supplied from the high-voltage battery 52 and outputs a direct current having a lower voltage than the high-voltage battery 52 to the low-voltage battery 56, or boosts the direct current supplied from the low-voltage battery 56 and outputs a direct current having a higher voltage than the low-voltage battery 56 to the high-voltage battery 52.

[0023] The air compressor AC is a well-known air compressor.

[0024] The engine 12, the electric motor MG, and the air compressor AC can be connected to each other via a belt transmission device 40. The belt transmission device 40 is a well-known belt-type transmission device including a crank pulley 42 connected to the crankshaft 32 of the engine 12 so as not to rotate relative to the rotor shaft 34 of the electric motor MG, an AC pulley 46 connected to the drive shaft 36 of the air compressor AC so as not to rotate relative to the rotor shaft 34, and a belt 48 wound between the crank pulley 42, the MG pulley 44, and the AC pulley 46. The crankshaft 32, the rotor shaft 34, and the drive shaft 36 are rotating members whose rotation centers are the first axis C1, the second axis C2, and the third axis C3, respectively. The first axis C1, the second axis C2, and the third axis C3 are parallel to each other. The belt 48 is an endless annular transmission member capable of transmitting power between the engine 12 and the electric motor MG, and is, for example, an endless annular compression-type power transmission belt or an endless annular tension-type power transmission belt capable of transmitting power between the crank pulley 42 and the MG pulley 44. The belt 48 corresponds to the "endless annular transmission member" in this invention.

[0025] Here, the crank pulley 42 has a radius R1 [mm], the MG pulley 44 has a radius R2 [mm], and the value obtained by dividing the radius R2 by the radius R1 is the predetermined rotation ratio α (=R2 / R1) in the belt transmission device 40.

[0026] The air compressor AC can be switched between an operating state and a stopped state. For example, the AC pulley 46 is connected to the drive shaft 36 of the air compressor AC via a clutch (not shown). When the clutch is engaged, the rotation of the AC pulley 46 is transmitted to the drive shaft 36, thereby putting the air compressor AC into an operating state. When the clutch is released, the AC pulley 46 rotates freely relative to the drive shaft 36, so that the air compressor AC is put into a stopped state.

[0027] FIG. 2 is a diagram illustrating the belt transmission device 40 shown in FIG.

[0028] As described above, the belt transmission device 40 includes the crank pulley 42, the MG pulley 44, the AC pulley 46, and the belt 48 wound around them. The belt transmission device 40 further includes a tensioner 60 for adjusting the tension of the belt 48 in the vicinity of the MG pulley 44. For example, the tensioner 60 is a pendulum-type tensioner shown in Fig. 2. The tensioner 60 includes a support body 60s held so as to be swingable about the second axis C2 of the MG pulley 44, and a pair of tension pulleys 60p held at both ends of the support body 60s, respectively. Assuming that the belt 48 rotates as indicated by the dashed arrow, one of the pair of tension pulleys 60p is positioned so as to press the outer circumferential surface of one side 48a of the belt 48 between the crank pulley 42 and the MG pulley 44 (e.g., the side of the belt 48 that faces from the crank pulley 42 connected to the engine 12 to the MG pulley 44 connected to the electric motor MG) toward the inner circumferential surface, and the other of the pair of tension pulleys 60p is positioned so as to press the outer circumferential surface of the other side 48b of the belt 48 between the crank pulley 42 and the MG pulley 44 (e.g., the side of the belt 48 that faces from the MG pulley 44 connected to the electric motor MG to the crank pulley 42 connected to the engine 12) toward the inner circumferential surface.

[0029] When the tension of one side 48a of the belt 48 becomes higher than the tension of the other side 48b of the belt 48, the pair of tension pulleys 60p and the support 60s are moved in the direction of arrow A shown in FIG. 2 by the one side 48a. This movement reduces the tension of the one side 48a and increases the tension of the other side 48b. On the other hand, when the tension of the other side 48b of the belt 48 becomes higher than the tension of the one side 48a of the belt 48, the pair of tension pulleys 60p and the support 60s are moved in the direction of arrow B shown in FIG. 2 by the other side 48b. This movement reduces the tension of the other side 48b and increases the tension of the one side 48a. Therefore, the tensioner 60 operates so that the tension of the one side 48a and the tension of the other side 48b of the belt 48 are equal to each other. The elastic component of tensioner 60 causes tensioner 60 to alternate between movement in the directions of arrows A and B, gradually decreasing the amount of movement, so that the tension on one side 48a and the tension on the other side 48b of belt 48 become equal to each other.

[0030] When the belt 48 is not in a slack state, when the belt 48 is not slipping on at least one of the crank pulley 42 and the MG pulley 44, and when the tension of one side 48a and the tension of the other side 48b of the belt 48 are not changing, the rotation speed obtained by multiplying the MG rotation speed Nmg by a predetermined rotation ratio α, that is, the converted rotation speed Nmgc (=Nmg×α) obtained by converting the MG rotation speed Nmg into the rotation speed of the crankshaft 32, which is the rotating shaft of the engine 12, coincides with the engine rotation speed Ne [rpm], which is the rotation speed of the engine 12. In this state, the engine 12 and the electric motor MG, which are connected via the belt 48, rotate in conjunction with each other, and the rotation of the engine 12 and the rotation of the electric motor MG are synchronized. The engine rotation speed Ne and the MG rotation speed Nmg correspond to the "rotation speed of the internal combustion engine" and the "rotation speed of the electric motor" in the present invention, respectively.

[0031] When the belt 48 is in any of the following states: when the belt 48 is bent, when the belt 48 is slipping relative to at least one of the crank pulley 42 and the MG pulley 44, and when the tension on one side 48a and the other side 48b of the belt 48 is changing, the converted rotational speed Nmgc (=Nmg×α) and the engine rotational speed Ne do not match, and the rotation of the engine 12 and the rotation of the electric motor MG are not synchronized.

[0032] 1, the electronic control device 90 includes a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input / output interface, etc., and the CPU executes various controls of the vehicle 10 by performing signal processing according to a program previously stored in the ROM while utilizing the temporary storage function of the RAM. The electronic control device 90 corresponds to the "control device" in the present invention.

[0033] The electronic control device 90 receives various signals based on detection values ​​from various sensors (e.g., an engine rotation speed sensor 70, a MG rotation speed sensor 72, an output shaft rotation speed sensor 74, an accelerator opening sensor 76, a throttle valve opening sensor 78, etc.) provided in the vehicle 10 (e.g., an engine rotation speed Ne [rpm], an MG rotation speed Nmg [rpm] which is the rotation speed of the electric motor MG, an output shaft rotation speed Nout [rpm] which is the rotation speed of the output shaft 24 corresponding to the vehicle speed V [km / h], an accelerator opening θacc [%] which is an acceleration operation amount which indicates the magnitude of the acceleration operation by the driver, a throttle valve opening θth [%] which is the opening of the electronic throttle valve, etc.). The engine rotation speed sensor 70 is a known rotation speed sensor which can detect, for example, the rotation speed of the crankshaft 32 but cannot detect the rotation direction. The MG rotation speed sensor 72 is, for example, a resolver which can detect the phase of the rotor shaft 34, i.e., the rotation direction and rotation speed.

[0034] The electronic control device 90 outputs various command signals (e.g., an engine control signal Se for controlling the engine 12, an MG control signal Smg for executing rotation control of the electric motor MG via the inverter 50, a shift control signal Sat for executing shift control of the transmission 18, a converter control signal Scon for controlling the voltage conversion of the DC / DC converter 54, etc.) to each device (e.g., the engine 12, the inverter 50, the transmission 18, the DC / DC converter 54, etc.) provided in the vehicle 10.

[0035] Hereinafter, a case will be described in which the engine 12 is cranked and started by the electric motor MG. For example, the vehicle 10 is equipped with an idling stop function that stops the engine 12 when the vehicle is stopped at an intersection or the like, and then restarts the engine 12 when a restart condition is met, and the engine 12 that has been stopped by the idling stop function is restarted.

[0036] The electronic control device 90 functionally comprises an engine control section 92 , a gear shift control section 94 , a starting control section 96 , and an electric motor control section 98 .

[0037] While the vehicle is traveling, the engine control unit 92 controls the engine torque Te so as to realize the drive demand amount for the vehicle 10. When the vehicle is stopped and the idling stop function is activated, the engine control unit 92 stops the engine 12. When the vehicle is stopped and the idling stop function is deactivated, the engine control unit 92 resumes operation of the engine 12.

[0038] The shift control unit 94 judges whether or not to shift the transmission 18 using, for example, a shift map, and outputs a shift control signal Sat to the transmission 18 to execute shift control as necessary. The shift map is a predetermined relationship having a shift line for judging whether or not to shift the automatic transmission on a two-dimensional coordinate system having, for example, the vehicle speed V and the required driving torque Trdem as variables. In the shift map, the output shaft rotation speed Nout or the like may be used instead of the vehicle speed V, and the required driving force Frdem, the accelerator opening θacc, the throttle valve opening θth or the like may be used instead of the required driving torque Trdem.

[0039] Incidentally, the current supplied to the electric motor MG becomes an overcurrent during execution of engine start control due to an increase in the power of the electric motor MG (for example, the power Ws supplied to the electric motor MG). The power of the electric motor MG is proportional to the product of the MG torque Tmg and the MG rotation speed Nmg. Therefore, in order to prevent the current supplied to the electric motor MG from becoming an overcurrent, it is desirable to adjust the MG torque Tmg based on the MG rotation speed Nmg.

[0040] Fig. 3 shows an example of the relationship between the MG rotation speed Nmg and the MG torque Tmg adjusted accordingly. As shown in Fig. 3, when the MG rotation speed Nmg is high, the MG torque Tmg is lowered compared to when the MG rotation speed Nmg is low, thereby preventing the current supplied to the electric motor MG from becoming an overcurrent.

[0041] However, when the MG torque Tmg is set based on the MG rotation speed Nmg during execution of engine start control, if the rotation of the engine 12 and the rotation of the electric motor MG are not synchronized, the MG torque Tmg, which is the starting torque Tmgsta, will be set high when the converted rotation speed Nmgc decreases with respect to the engine rotation speed Ne, and the MG rotation speed Nmg will increase around the time when the actual MG torque Tmg increases, which may result in the current supplied to the electric motor MG becoming an overcurrent.

[0042] The start control unit 96 controls the electric motor MG and the engine 12 to execute engine start control. The start control unit 96 functionally includes a first torque calculation unit 96a, a second torque calculation unit 96b, a rotation speed determination unit 96c, a torque determination unit 96d, and a start torque setting unit 96e.

[0043] The first torque calculation unit 96a calculates a first torque Tmg1, which is an output torque required for cranking by the electric motor MG, based on the engine rotation speed Ne. For example, the first torque Tmg1 is calculated by applying the actual engine rotation speed Ne to a torque calculation map. The torque calculation map is a map in which a relationship between the engine rotation speed Ne and the output torque required for cranking by the electric motor MG is determined in advance experimentally or by design, for example, so that the engine rotation speed Ne is increased at a predetermined rate of increase. The predetermined rate of increase is a rate of increase of the engine rotation speed Ne when the engine 12 is cranked by the electric motor MG, and is a value determined experimentally or by design.

[0044] The second torque calculation unit 96b calculates the second torque Tmg2, which is an output torque required for cranking by the electric motor MG, based on the MG rotation speed Nmg. For example, a converted rotation speed Nmgc (=Nmg×α) is calculated based on the actual MG rotation speed Nmg, and the converted rotation speed Nmgc is applied to the torque calculation map described above to calculate the second torque Tmg2. When the rotation of the engine 12 and the rotation of the electric motor MG are synchronized, the engine rotation speed Ne and the converted rotation speed Nmgc match, so that the first torque Tmg1 and the second torque Tmg2 match. When the rotation of the engine 12 and the rotation of the electric motor MG are not synchronized, the engine rotation speed Ne and the converted rotation speed Nmgc do not match, so that the first torque Tmg1 and the second torque Tmg2 do not match.

[0045] The rotation speed determination unit 96c determines whether the MG rotation speed Nmg is equal to or greater than zero. The torque determination unit 96d determines whether the first torque Tmg1 calculated by the first torque calculation unit 96a is smaller than the second torque Tmg2 calculated by the second torque calculation unit 96b.

[0046] When the rotation speed determination unit 96c determines that the MG rotation speed Nmg is equal to or greater than zero and the torque determination unit 96d determines that the first torque Tmg1 is smaller than the second torque Tmg2, the starting torque setting unit 96e sets the first torque Tmg1 as the starting torque Tmgsta. Otherwise, the starting torque setting unit 96e sets the second torque Tmg2 as the starting torque Tmgsta. The starting torque Tmgsta is a torque that cranks the engine 12.

[0047] In this way, even when the rotation of the engine 12 and the rotation of the electric motor MG are not synchronized, the smaller of the first torque Tmg1 calculated based on the engine rotation speed Ne and the second torque Tmg2 calculated based on the MG rotation speed Nmg is set as the starting torque Tmgsta of the electric motor MG. Therefore, when the converted rotation speed Nmgc decreases with respect to the engine rotation speed Ne, the MG torque Tmg, which is the starting torque Tmgsta, is set high, and the MG rotation speed Nmg increases around the time the actual MG torque Tmg increases, thereby preventing the current supplied to the electric motor MG from becoming an overcurrent.

[0048] In engine start control, the motor control unit 98 controls the MG torque Tmg so as to output the start torque Tmgsta set by the start torque setting unit 96e. In regenerative control, the motor control unit 98 controls the MG torque Tmg so as to obtain the generated power Wg at the motor MG using the power of the engine 12.

[0049] Fig. 4 is an example of a flowchart illustrating a main part of the control operation of the electronic control device 90 shown in Fig. 1. The flowchart in Fig. 4 is repeatedly executed during execution of engine start control for restarting the engine 12 that has been stopped by the idling stop function.

[0050] First, in step S10 (hereinafter, "step" will be omitted), which corresponds to the function of the first torque calculation unit 96a, a first torque Tmg1, which is an output torque required for cranking by the electric motor MG, is calculated based on the engine rotation speed Ne. After execution of S10, in S20, which corresponds to the function of the second torque calculation unit 96b, a second torque Tmg2, which is an output torque required for cranking by the electric motor MG, is calculated based on the MG rotation speed Nmg. As described above, when the rotation of the engine 12 and the rotation of the electric motor MG are synchronized, the first torque Tmg1 and the second torque Tmg2 match, and when the rotation of the engine 12 and the rotation of the electric motor MG are not synchronized, the first torque Tmg1 and the second torque Tmg2 do not match.

[0051] After execution of S20, in S30 corresponding to the function of the rotation speed determination unit 96c, it is determined whether or not the MG rotation speed Nmg is equal to or greater than zero. If the determination in S30 is positive, in S40 corresponding to the function of the torque determination unit 96d, it is determined whether or not the first torque Tmg1 is smaller than the second torque Tmg2. If the determination in S40 is positive, in S50 corresponding to the function of the starting torque setting unit 96e, the first torque Tmg1 is set as the starting torque Tmgsta. If the determination in S30 is negative or if the determination in S40 is negative, the second torque Tmg2 is set as the starting torque Tmgsta. After execution of S50 and S60, in S70 corresponding to the function of the motor control unit 98, the MG torque Tmg is controlled so as to output the starting torque Tmgsta set in either S50 or S60. After execution of S70, the process returns.

[0052] Fig. 5 is an example of a time chart in the case where the flowchart in Fig. 4 is executed when the engine 12 in a stopped state is restarted. In Fig. 5, the horizontal axis represents time t [ms].

[0053] At time t0, the electric motor MG starts to output the MG torque Tmg in order to crank the engine 12. As the MG torque Tmg starts to be output, the engine rotation speed Ne starts to increase at time t1 (>t0).

[0054] In the period from time t1 to time t2 (>t1), the period from time t3 (>t2) to time t4 (>t3), and the period from time t5 (>t4) to time t6 (>t5), the converted rotation speed Nmgc is greater than the engine rotation speed Ne. In the period from time t2 to time t3, and the period from time t4 to time t5, the converted rotation speed Nmgc is smaller than the engine rotation speed Ne. In this way, due to the change in tension of the belt 48 caused by large fluctuations in the MG torque Tmg and the elastic component of the tensioner 60, the period in which the converted rotation speed Nmgc is greater than the engine rotation speed Ne and the period in which the converted rotation speed Nmgc is smaller than the engine rotation speed Ne are alternately repeated.

[0055] In each of the periods from time t1 to time t2, from time t3 to time t4, and from time t5 to time t6 (periods in which the converted rotational speed Nmgc is greater than the engine rotational speed Ne), the second torque Tmg2 calculated based on the converted rotational speed Nmgc, i.e., the MG rotational speed Nmg, is smaller than the first torque Tmg1 calculated based on the engine rotational speed Ne. In each of the periods from time t2 to time t3 and from time t4 to time t5 (periods in which the converted rotational speed Nmgc is smaller than the engine rotational speed Ne), the second torque Tmg2 calculated based on the converted rotational speed Nmgc, i.e., the MG rotational speed Nmg, is larger than the first torque Tmg1 calculated based on the engine rotational speed Ne.

[0056] Therefore, in each of the periods from time t1 to time t2, from time t3 to time t4, and from time t5 to time t6, the second torque Tmg2 is set as the starting torque Tmgsta, and in each of the periods from time t2 to time t3 and from time t4 to time t5, the first torque Tmg1 is set as the starting torque Tmgsta.

[0057] Fig. 6 is an example of a time chart in the case where the flow chart of Fig. 4 is executed when the engine 12 is restarted during engine stop control. In Fig. 6, the horizontal axis represents time t [ms].

[0058] In the period before time t11, the engine speed Ne, which is the forward rotation speed, is reduced due to the engine stop control.

[0059] During the period from time t11 to time t12 (>t11), the engine 12 rotates in the reverse direction, and the engine speed Ne (true value) is negative. For example, if the engine speed sensor 70 cannot detect the rotation direction during the period from time t11 to time t12, the engine speed sensor 70 may erroneously detect the negative engine speed Ne as positive.

[0060] For example, at time t11, the electric motor MG starts to output the MG torque Tmg in order to restart the engine 12. If the first torque Tmg1 is calculated based on the erroneously detected positive engine rotation speed Ne during the period from time t11 to time t12, the first torque Tmg1 will be smaller than the first torque Tmg1 calculated based on the true negative engine rotation speed Ne.

[0061] On the other hand, the MG rotation speed sensor 72, which is a resolver, detects the negative MG rotation speed Nmg, which is a true value. When the MG rotation speed Nmg is negative, the second torque Tmg2 calculated based on the MG rotation speed Nmg is set as the starting torque Tmgsta, instead of the first torque Tmg1 calculated based on the engine rotation speed Ne, which may be erroneously detected.

[0062] In the period after time t12, the engine speed Ne, which is a forward rotation, increases due to the engine start control. In the period after time t12, when the converted rotation speed Nmgc is larger than the engine speed Ne, the second torque Tmg2 is set as the starting torque Tmgsta, and when the converted rotation speed Nmgc is smaller than the engine speed Ne, the first torque Tmg1 is set as the starting torque Tmgsta.

[0063] According to this embodiment, when the engine 12 is cranked and started by the electric motor MG, the smaller of the first torque Tmg1, which is the output torque required by the electric motor MG calculated based on the engine rotation speed Ne, and the second torque Tmg2, which is the output torque required by the electric motor MG calculated based on the MG rotation speed Nmg, is set as the starting torque Tmgsta to be output from the electric motor MG. When the converted rotation speed Nmgc, which is the MG rotation speed Nmg converted into the rotation speed of the crankshaft 32, which is the rotating shaft of the engine 12, is higher than the engine rotation speed Ne, the MG torque Tmg can be reduced, and when the converted rotation speed Nmgc is lower than the engine rotation speed Ne, the MG torque Tmg is prevented from becoming higher than necessary. This prevents the current supplied to the electric motor MG from becoming an overcurrent.

[0064] According to this embodiment, when the MG rotation speed Nmg is negative, the second torque Tmg2 is set as the starting torque Tmgsta. Even when the engine 12 is rotating in reverse and the engine speed sensor 70 erroneously detects that the reverse rotation is a forward rotation, the second torque Tmg2 calculated based on the MG rotation speed Nmg is set as the starting torque Tmgsta, so that the starting torque Tmgsta is prevented from being erroneously set to a small value.

[0065] According to this embodiment, the tension of the belt 48 is adjusted by the tensioner 60. Even if the converted rotation speed Nmgc, which is the MG rotation speed Nmg converted into the rotation speed of the crankshaft 32, which is the rotating shaft of the engine 12, with respect to the engine rotation speed Ne, repeatedly becomes higher and lower due to the elastic component of the tensioner 60, the current supplied to the electric motor MG is prevented from becoming an overcurrent.

[0066] Although the embodiment of the present invention has been described in detail above with reference to the drawings, the present invention can be applied to other embodiments.

[0067] In the above embodiment, the engine 12 is a gasoline engine, but the present invention is also applicable to a diesel engine. If the engine 12 is a diesel engine, the engine 12 does not include an ignition device.

[0068] In the above embodiment, the belt 48 corresponds to the "endless annular transmission member" of the present invention, but the present invention is not limited to this embodiment. For example, if a well-known chain-type transmission device including an engine-side sprocket connected to the crankshaft 32 of the engine 12 so as not to rotate relative thereto, an electric motor-side sprocket connected to the rotor shaft 34 of the electric motor MG so as not to rotate relative thereto, an AC-side sprocket connected to the drive shaft 36 of the air compressor AC so as not to rotate relative thereto, and a chain wound between the engine-side sprocket, the electric motor-side sprocket, and the AC-side sprocket, is provided on the vehicle 10 instead of the belt transmission device 40, the chain corresponds to the "endless annular transmission member" of the present invention. In this way, the "endless annular transmission member" in the present invention is interpreted broadly and includes a chain as well as the belt 48 as long as it is a transmission member that can be in any of the following states: a bent state, a slipping state relative to at least one of the rotating member connected to the engine 12 (e.g., the crank pulley 42) and the rotating member connected to the electric motor MG (e.g., the MG pulley 44), and a state in which the tension on one side and the other side of the endless annular transmission member change between the engine 12 and the electric motor MG.

[0069] In the above-described embodiment, the belt transmission device 40 connects the engine 12, the electric motor MG, and the air compressor AC to one another. However, for example, the belt transmission device 40 may connect the engine 12 and the electric motor MG to one another but not to the air compressor AC.

[0070] In the above-described embodiment, the tensioner 60 is a pendulum type tensioner, but other embodiments may be used that incorporate a tension adjustment function using a spring structure or the like within the support body 60s, between the support body 60s and the MG pulley 44, or between the support body 60s and the MG pulley 44. The present invention is also applicable to embodiments in which the belt transmission device 40 is not provided with a tensioner 60.

[0071] In the above-described embodiment, the electronic control device 90 is for engine control, which controls the engine 12, and for electric motor control, which controls the electric motor MG. However, the electronic control device 90 may be configured so as to be divided into an electronic control device for engine control and an electronic control device for electric motor control, if necessary.

[0072] It should be noted that the above-described embodiments are merely examples of the present invention, and the present invention can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art without departing from the spirit of the present invention. [Explanation of symbols]

[0073] 10: Vehicle 12: Engine (internal combustion engine) 48: Belt (endless circular transmission member) 90: Electronic control device (control device) MG: Electric motor Ne: Engine speed (rotation speed of the internal combustion engine) Nmg: MG rotation speed (motor rotation speed) Tmg1: First torque Tmg2: Second torque Tmgsta: Starting torque

Claims

[Claim 1] A control device for a vehicle having an electric motor connected to an internal combustion engine via an endless annular transmission member, When the internal combustion engine is cranked and started by the electric motor, the smaller of a first torque, which is an output torque required by the electric motor calculated based on the rotation speed of the internal combustion engine, and a second torque, which is an output torque required by the electric motor calculated based on the rotation speed of the electric motor, is set as a starting torque to be output from the electric motor. A vehicle control device comprising:

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