Hybrid vehicle control device

Abstract

To provide a controller for a hybrid vehicle which can suppress a delay in the synchronization determination of an engine and an electric motor when the engine is started, and can suppress a delay in the completion of engine start control.SOLUTION: There is provided an electronic controller 90 for a hybrid vehicle 10 including an engine 12, an electric motor MG, and a K0 clutch 20 provided between the engine 12 and the electric motor MG. (a) When the K0 clutch 20 is engaged, and cranking by the electric motor MG causes the engine 12 to be started, the electronic controller 90 sequentially calculates a first rotational difference ΔN1 between an engine rotational speed Ne and an electric motor rotational speed Nmg for determining the synchronization of the engine 12 and the electric motor MG, (b) the electronic controller 90 sequentially calculates a second rotational difference ΔN2 between the engine rotational speed Ne and the electric motor rotational speed Nmg to be used for control other than the determination of the synchronization, and (c) the degree of smoothing in the first rotational difference ΔN1 is set to be greater than that in the second rotational difference ΔN2.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a control device for a hybrid vehicle including an engine, an electric motor, and a clutch provided between the engine and the electric motor. [Background technology]

[0002] A hybrid vehicle is known that includes an engine, an electric motor, and a clutch provided between the engine and the electric motor. A technique is known in which, when the engine of the hybrid vehicle is started, synchronization between the engine and the electric motor is determined using a rotational difference between the engine rotational speed and the electric motor rotational speed (synonymous with the rotational speed difference of the clutch), and control of the electric motor is shifted from control at engine start to control at normal times other than when the engine is started. For example, the technique is described in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-108988 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the control device for a hybrid vehicle described in Patent Document 1, if the rotational difference between the engine rotational speed and the electric motor rotational speed used for control other than the synchronization determination is used as the rotational difference between the engine and the electric motor used for the synchronization determination when the engine is started, there is a risk of a deviation between the actual rotational difference and the rotational difference used for the synchronization determination (particularly, a positive / negative inversion in which the signs of the actual rotational difference and the rotational difference used for the synchronization determination are reversed) occurring due to the influence of the damper and the running state of the vehicle. Since the output torque of the electric motor is adjusted based on the rotational difference, the output torque of the electric motor may delay the convergence of the rotational difference due to the deviation. If the convergence of the rotational difference is delayed, the synchronization determination between the engine and the electric motor is also delayed, and the completion of the engine start control may be delayed.

[0005] The present invention has been made against the background of the above circumstances, and its object is to provide a control device for a hybrid vehicle that can suppress delays in determining synchronization between the engine and the electric motor when the engine is started, and suppress delays in completing engine start control. [Means for solving the problem]

[0006] The gist of the first invention is a control device for a hybrid vehicle having an engine, an electric motor, and a clutch provided between the engine and the electric motor, which (a) sequentially calculates a first rotation difference between the engine rotation speed and the electric motor rotation speed for determining synchronization between the engine and the electric motor when the clutch is engaged and the engine is started by cranking by the electric motor, (b) sequentially calculates a second rotation difference between the engine rotation speed and the electric motor rotation speed for use in control other than the determination of synchronization, and (c) has a greater degree of smoothing of the first rotation difference than the second rotation difference. Effect of the Invention

[0007] According to the control device for a hybrid vehicle of the first invention, (a) when the clutch is engaged and the engine is started by cranking by the electric motor, a first rotation difference between the engine rotation speed and the electric motor rotation speed for determining synchronization between the engine and the electric motor is calculated sequentially, (b) a second rotation difference between the engine rotation speed and the electric motor rotation speed for use in control other than the synchronization determination is calculated sequentially, and (c) the first rotation difference is smoothed to a greater extent than the second rotation difference. When the smoothing degree of the first rotation difference for determining synchronization between the engine and the electric motor is greater than the smoothing degree of the second rotation difference for use in control other than the synchronization determination, the deviation (positive / negative reversal in which the sign is reversed) between the actual rotation difference and the rotation difference used for synchronization determination is suppressed compared to other cases, and the output of erroneously adjusted torque from the electric motor is suppressed. As a result, the delay in the convergence of the first rotation difference used for synchronization determination when the engine is started is suppressed, thereby suppressing the delay in the completion of the engine start control.

[0008] According to the control device for a hybrid vehicle of the second invention, in the first invention, the control other than the determination of the synchronization is the output torque control of the electric motor when the engine is started. When the smoothing degree of the second rotation difference used for controlling the torque transmitted from the electric motor to the engine via the clutch when the engine is started is smaller than the smoothing degree of the first rotation difference for determining the synchronization between the engine and the electric motor, the difference (absolute value) between the actual rotation difference and the second rotation difference used for controlling the output torque of the electric motor becomes smaller than in other cases. This prevents the torque transmitted from the electric motor to the engine via the clutch as the cranking reaction torque from becoming excessive. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram of a hybrid 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]2 is an example of a flowchart illustrating a control operation of the electronic control device shown in FIG. 1. [Diagram 3] 3 is an example of a time chart when the flowchart of FIG. 2 is executed. [Figure 4] 4 is an example of a time chart according to Comparative Example 1. [Diagram 5] 11 is an example of a time chart according to Comparative Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 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

[0011] FIG. 1 is a schematic diagram of a hybrid 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 hybrid vehicle 10.

[0012] The hybrid vehicle 10 (hereinafter simply referred to as “vehicle 10”) includes an engine 12 and an electric motor MG, which are driving power sources for traveling, and a power transmission device 16 provided in a power transmission path between the engine 12 and drive wheels 14.

[0013] The engine 12 is a known internal combustion engine. An engine control device 50 including a throttle actuator, a fuel injection device, an ignition device, and the like provided in the vehicle 10 is controlled by an electronic control device 90 (described later), whereby an engine torque Te [Nm] that is an output torque of the engine 12 is controlled.

[0014] The power transmission device 16 includes, in order from the engine 12 side, a damper 42, a K0 clutch 20, an electric motor connecting shaft 36, a torque converter 22, an automatic transmission 24, and the like, housed within a case 18 which is a non-rotating member attached to the vehicle body. The power transmission device 16 includes a propeller shaft 28 connected to a transmission output shaft 26 which is an output rotating member of the automatic transmission 24, a differential gear 30 connected to the propeller shaft 28, a pair of drive shafts 32 connected to the differential gear 30, and the like. The power transmission device 16 includes an engine connecting shaft 34 which connects the engine 12 and the damper 42. The electric motor connecting shaft 36 connects the K0 clutch 20 and the torque converter 22.

[0015] The damper 42 is a well-known damper device, such as a pendulum damper, that transmits the rotation of the engine 12 while absorbing pulsation of the engine 12. The K0 clutch 20 is a clutch provided between the engine 12 and the electric motor MG in a power transmission path between the engine 12 and the drive wheels 14. When the K0 clutch 20 is in an engaged state, one end of the electric motor connecting shaft 36 is connected to the engine 12 via the damper 42, and is thus rotationally driven by the engine 12. The K0 clutch 20 corresponds to the "clutch" of this invention.

[0016] The torque converter 22 is a well-known torque converter. The torque converter 22 includes a pump wheel 22a connected to the motor connecting shaft 36, a turbine wheel 22b connected to a transmission input shaft 38 that is an input rotating member of the automatic transmission 24, and an LU clutch 40 that directly connects the pump wheel 22a and the turbine wheel 22b. The torque converter 22 is a fluid-type power transmission device that transmits driving force from each of the driving force sources (engine 12, electric motor MG) from the motor connecting shaft 36 to the transmission input shaft 38 via a fluid. The torque converter 22 is connected to the engine 12 via a K0 clutch 20 and a damper 42. The automatic transmission 24 is connected to the torque converter 22 and is provided in a power transmission path between the torque converter 22 and the driving wheels 14. The torque converter 22 and the automatic transmission 24 each constitute a part of the power transmission path between the driving force sources (engine 12, electric motor MG) and the driving wheels 14.

[0017] The electric motor MG is a rotating electric machine having a function as a motor that generates mechanical power from electric power and a function as a generator that generates electric power from mechanical power, and is a so-called motor generator. The electric motor MG is connected to a battery 54 provided in the vehicle 10 via an inverter 52 described later. The battery 54 is an electricity storage device that supplies and receives electric power to the electric motor MG. The electric motor MG controls the electric motor torque Tmg [Nm], which is the output torque of the electric motor MG, by controlling the inverter 52 by an electronic control device 90 described later. For example, when the rotation direction of the electric motor MG is a positive rotation that is the same as the rotation direction when the engine 12 is in operation, the electric motor torque Tmg is a powering 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. The electric power also means electric energy when there is no particular distinction. The power also means torque and force when there is no particular distinction.

[0018] The electric motor MG is connected to the electric motor connecting shaft 36 in the case 18 so as to be capable of transmitting power. In other words, the electric motor MG is connected to a power transmission path between the K0 clutch 20 and the torque converter 22 so as to be capable of transmitting power. In other words, the electric motor MG is connected to the torque converter 22 and the automatic transmission 24 so as to be capable of transmitting power without passing through the K0 clutch 20.

[0019] The automatic transmission 24 is a known planetary gear type automatic transmission including, for example, one or more planetary gear devices (not shown) and a plurality of engagement devices CB. The engagement devices CB are, for example, known hydraulic friction engagement devices. The engagement devices CB have their respective torque capacities, or CB torques Tcb [Nm], changed by the CB hydraulic pressure PRcb [Pa], which is a regulated hydraulic pressure supplied from a hydraulic control circuit 56, thereby switching between operating states, such as an engaged state and a released state, i.e., control states.

[0020] The automatic transmission 24 is a stepped transmission in which one of a plurality of gear stages (also called gear stages) with different speed ratios (also called gear ratios) γat (=AT input rotation speed Ni [rpm] / AT output rotation speed No [rpm]) is formed by engaging one of the engagement devices CB. The automatic transmission 24 switches the formed gear stages by switching the control state of a predetermined engagement device, which is an engagement device involved in the shifting of the automatic transmission 24 among the engagement devices CB, according to the driver's accelerator operation, the vehicle speed V [km / h], etc., by an electronic control device 90 described later. That is, in the shift control of the automatic transmission 24, for example, a shift is performed by switching the engagement of a predetermined engagement device, that is, a shift is performed by disengaging a release-side engagement device and engaging an engagement-side engagement device, so-called a clutch-to-clutch shift is performed. The disengagement side engagement device is an engagement device that was in an engaged state before the automatic transmission 24 is shifted among the predetermined engagement devices, and is an engagement device that is controlled from an engaged state to a released state during a shift transition of the automatic transmission 24. The engagement side engagement device is an engagement device that was in a released state before the automatic transmission 24 is shifted among the predetermined engagement devices, and is an engagement device that is controlled from a released state to an engaged state during a shift transition of the automatic transmission 24. The AT input rotation speed Ni is the rotation speed of the transmission input shaft 38, and is the input rotation speed of the automatic transmission 24. The AT input rotation speed Ni is the same value as the turbine rotation speed Nt [rpm], which is the output rotation speed of the torque converter 22. The AT input rotation speed Ni can be expressed by the turbine rotation speed Nt. The AT output rotation speed No is the rotation speed of the transmission output shaft 26, and is the output rotation speed of the automatic transmission 24.

[0021] The K0 clutch 20 is a hydraulic friction engagement device constituted by, for example, a multi-plate or single-plate clutch. The K0 clutch 20 switches between control states such as an engaged state and a released state by changing the torque capacity of the K0 clutch 20, K0 torque Tk0 [Nm], by the regulated hydraulic pressure, K0 hydraulic pressure PRk0 [Pa], supplied from the hydraulic control circuit 56.

[0022] In the vehicle 10, when the K0 clutch 20 is in an engaged state, the engine 12 and the torque converter 22 are connected to each other so as to transmit power. On the other hand, when the K0 clutch 20 is in a disengaged state, power transmission between the engine 12 and the torque converter 22 is interrupted. Since the electric motor MG is connected to the torque converter 22, the K0 clutch 20 functions as a clutch that connects and disconnects the engine 12 from the electric motor MG.

[0023] In the power transmission device 16, when the K0 clutch 20 is engaged, the power output from the engine 12 is transmitted from the engine connecting shaft 34 to the driving wheels 14 via the K0 clutch 20, the electric motor connecting shaft 36, the torque converter 22, the automatic transmission 24, the propeller shaft 28, the differential gear 30, the drive shaft 32, etc. in this order. The power output from the electric motor MG is transmitted from the electric motor connecting shaft 36 to the driving wheels 14 via the torque converter 22, the automatic transmission 24, the propeller shaft 28, the differential gear 30, the drive shaft 32, etc. in this order, regardless of the control state of the K0 clutch 20.

[0024] The vehicle 10 includes the MOP 58, which is a mechanical oil pump, the EOP 60, which is an electric oil pump, a pump motor 62, and the like. The MOP 58 is connected to the pump impeller 22a, and is rotated and driven by a driving force source (the engine 12, the electric motor MG) to discharge hydraulic oil OIL used in the power transmission device 16. The pump motor 62 is a motor dedicated to the EOP 60 for rotating and driving the EOP 60. The EOP 60 is rotated and driven by the pump motor 62 to discharge hydraulic oil OIL. The hydraulic oil OIL discharged by the MOP 58 and the EOP 60 is supplied to a hydraulic control circuit 56. The hydraulic control circuit 56 supplies the CB hydraulic pressure PRcb, the K0 hydraulic pressure PRk0, and the like, which are adjusted based on the hydraulic oil OIL discharged by the MOP 58 and / or the EOP 60.

[0025] The vehicle 10 includes an electronic control device 90. The electronic control device 90 includes a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input / output interface, and the like, 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 includes computers for engine control, electric motor control, hydraulic control, and the like as necessary. The electronic control device 90 corresponds to the "control device" in the present invention.

[0026] The electronic control device 90 receives various signals based on detection values ​​from various sensors provided in the vehicle 10 (e.g., an engine rotation speed sensor 70, a turbine rotation speed sensor 72, an output rotation speed sensor 74, an electric motor rotation speed sensor 76, an accelerator opening sensor 78, a throttle valve opening sensor 80, a battery sensor 84, an oil temperature sensor 86, etc.) (e.g., an engine rotation speed Ne [rpm] which is the rotation speed of the engine 12, a turbine rotation speed Nt which is the same value as the AT input rotation speed Ni, an AT output rotation speed No corresponding to the vehicle speed V, an electric motor rotation speed Nmg [rpm] which is the rotation speed of the electric motor MG, an accelerator opening θacc [%] which is the driver's accelerator operation amount which indicates the magnitude of the driver's acceleration operation, a throttle valve opening θth [%] which is the opening of the electronic throttle valve, a battery temperature THbat [°C], a battery charge / discharge current Ibat [A], and a battery voltage Vbat [V] of the battery 54, and a hydraulic oil temperature THoil [°C] which is the temperature of the hydraulic oil OIL in the hydraulic control circuit 56).

[0027] The electronic control device 90 outputs various command signals (e.g., an engine control signal Se for controlling the engine 12, an electric motor control signal Sm for controlling the electric motor MG, a CB hydraulic control signal Sbc for controlling the engagement device CB, a K0 hydraulic control signal Sk0 for controlling the K0 clutch 20, an LU hydraulic control signal Slu for controlling the LU clutch 40, an EOP control signal Seop for controlling the EOP 60, etc.) to each device (e.g., an engine control device 50, an inverter 52, a hydraulic control circuit 56, a pump motor 62, etc.) provided in the vehicle 10.

[0028] The electronic control device 90 functionally comprises a hybrid control means or hybrid control section 92 , a clutch control means or clutch control section 94 , and a gear shift control means or gear shift control section 96 .

[0029] The hybrid control unit 92 functionally comprises an engine control means, i.e., an engine control unit 92a, that controls the operation of the engine 12, and an electric motor control means, i.e., an electric motor control unit 92b, that controls the operation of the electric motor MG via the inverter 52, and performs hybrid drive control using the engine 12 and the electric motor MG, etc., using these control functions.

[0030] The hybrid control unit 92 calculates the driving demand amount of the vehicle 10 by the driver, for example, by applying the accelerator opening θacc and the vehicle speed V to a driving demand amount map. The driving demand amount map is a relationship that is experimentally or design-wise determined and stored in advance, that is, a predetermined relationship. The driving demand amount is, for example, the required driving torque Trdem [Nm] at the driving wheels 14. In other words, the required driving torque Trdem is the required driving power Prdem [W] at the vehicle speed V at that time. The driving demand amount can also be the required driving force Frdem [N] at the driving wheels 14, the required AT output torque at the transmission output shaft 26, or the like. In calculating the driving demand amount, the AT output rotation speed No, or the like, can be used instead of the vehicle speed V.

[0031] The hybrid control unit 92 outputs an engine control signal Se for controlling the engine 12 and an electric motor control signal Sm for controlling the electric motor MG so as to realize the required driving power Prdem, taking into consideration the transmission loss, the auxiliary load, the gear ratio γat of the automatic transmission 24, the chargeable electric power Win [W] and the dischargeable electric power Wout [W] of the battery 54, etc. The engine control signal Se is, for example, a command value for the engine power Pe [W], which is the power of the engine 12 that outputs the engine torque Te at the engine rotation speed Ne at that time. The electric motor control signal Sm is, for example, a command value for the power consumption Wm [W] of the electric motor MG that outputs the electric motor torque Tmg at the electric motor rotation speed Nmg at that time.

[0032] The chargeable power Win of the battery 54 is the maximum power that can be input, which specifies the limit on the input power of the battery 54, and indicates the input limit of the battery 54. The dischargeable power Wout of the battery 54 is the maximum power that can be output, which specifies the limit on the output power of the battery 54, and indicates the output limit of the battery 54. The chargeable power Win and dischargeable power Wout of the battery 54 are calculated by the electronic control device 90 based on, for example, the battery temperature THbat and the state of charge value SOC [%] of the battery 54 (the ratio of the amount of charge actually stored to a predetermined full charge capacity).

[0033] When the required drive torque Trdem can be satisfied only by the output of the electric motor MG, the hybrid control unit 92 sets the drive mode to the motor drive (=EV drive) mode. In the EV drive mode, the hybrid control unit 92 performs EV drive by outputting drive force only from the electric motor MG among the drive power sources (engine 12, electric motor MG) when the K0 clutch 20 is in the disengaged state. On the other hand, when the required drive torque Trdem cannot be satisfied without using at least the output of the engine 12, the hybrid control unit 92 sets the drive mode to the engine drive mode, i.e., hybrid drive (=HV drive) mode. In the HV drive mode, the hybrid control unit 92 performs engine drive by outputting drive force only from the engine 12 among the drive power sources (engine 12, electric motor MG) when the K0 clutch 20 is in the engaged state, i.e., HV drive. On the other hand, even if the required drive torque Trdem can be satisfied only by the output of the electric motor MG, the hybrid control unit 92 establishes the HV driving mode when the state of charge value SOC of the battery 54 falls below a predetermined engine start threshold value or when warming up of the engine 12 or the like is required. The engine start threshold value is a predetermined threshold value for determining that the state of charge value SOC is at a value at which the engine 12 needs to be forcibly started to charge the battery 54. In this way, the hybrid control unit 92 switches between the EV driving mode and the HV driving mode by automatically stopping the engine 12 during HV driving, restarting the engine 12 after the engine is stopped, starting the engine 12 during EV driving, automatically stopping the engine 12 while the vehicle is stopped, or starting the engine 12, based on the required drive torque Trdem, etc.

[0034] The engine control unit 92a controls the engine torque Te so as to realize the drive demand amount for the vehicle 10. The electric motor control unit 92b controls the electric motor torque Tmg so as to realize the drive demand amount for the vehicle 10. Specifically, in the HV driving mode, the engine control unit 92a controls the engine torque Te so as to realize all or part of the required drive torque Trdem, and the electric motor control unit 92b controls the electric motor torque Tmg so as to compensate for the torque that is insufficient in the engine torque Te for the required drive torque Trdem. In the EV driving mode, the electric motor control unit 92b controls the electric motor torque Tmg so as to realize the required drive torque Trdem.

[0035] The hybrid control unit 92 further includes, functionally, an engine start determination means, that is, an engine start determination unit 92c, and a start control means, that is, a start control unit 92d.

[0036] The engine start determination unit 92c determines whether or not a request has been made to start the engine 12. That is, the engine start determination unit 92c determines whether or not there has been a request to start the engine 12. For example, in the EV driving mode, when the required driving torque Trdem increases beyond a range that can be covered only by the output of the electric motor MG, when warming up of the engine 12 or the like is required, or when the state of charge value SOC of the battery 54 is less than the engine start threshold, the engine start determination unit 92c determines that there has been a request to start the engine 12.

[0037] The clutch control unit 94 controls the K0 clutch 20 to execute start control of the engine 12. For example, when the engine start determination unit 92c determines that there is a request to start the engine 12, the clutch control unit 94 outputs a K0 hydraulic control signal Sk0 to the hydraulic control circuit 56 to control the K0 clutch 20 in the released state toward the engaged state so that a K0 torque Tk0 for transmitting a torque required for cranking the engine 12, which is a torque for increasing the engine rotation speed Ne, to the engine 12 side is obtained. When starting the engine 12, the clutch control unit 94 outputs a K0 hydraulic control signal Sk0 to the hydraulic control circuit 56 to control the actuator so as to switch the control state of the K0 clutch 20 from the released state to the engaged state. In this embodiment, the torque required for cranking the engine 12 is referred to as a required cranking torque Tcrn [Nm].

[0038] The start control unit 92d controls the engine 12 and the electric motor MG to execute start control of the engine 12. For example, when the engine start determination unit 92c determines that there is a request to start the engine 12, the start control unit 92d outputs to the inverter 52 an electric motor control signal Sm for causing the electric motor MG to output the required cranking torque Tcrn in accordance with switching of the K0 clutch 20 to the engaged state by the clutch control unit 94. That is, when starting the engine 12, the start control unit 92d outputs to the inverter 52 an electric motor control signal Sm for controlling the electric motor MG to output the required cranking torque Tcrn.

[0039] When the engine start determination unit 92c determines that there is a request to start the engine 12, the start control unit 92d outputs an engine control signal Se to the engine control device 50 for starting fuel supply, ignition, and the like in conjunction with cranking of the engine 12 by the K0 clutch 20 and the electric motor MG. That is, when starting the engine 12, the start control unit 92d outputs an engine control signal Se to the engine control device 50 for controlling the engine 12 so that the engine 12 starts operating. In this way, when the engine start determination unit 92c determines that there is a request to start the engine 12, the start control unit 92d executes start control of the engine 12.

[0040] When cranking the engine 12, a cranking reaction torque Trfcr [Nm] is generated, which is a reaction torque associated with the engagement of the K0 clutch 20. During EV driving, this cranking reaction torque Trfcr causes a pulling sensation of the vehicle 10 due to the inertia during engine start, that is, a drop in the drive torque Tr [Nm]. Therefore, the required cranking torque Tcrn output by the electric motor MG when starting the engine 12 is also the electric motor torque Tmg for canceling the cranking reaction torque Trfcr. In other words, the required cranking torque Tcrn is the K0 torque Tk0 required for cranking the engine 12, and corresponds to the electric motor torque Tmg flowing from the electric motor MG side to the engine 12 side via the K0 clutch 20. In other words, the K0 torque Tk0 is also a reaction guarantee torque for canceling the cranking reaction torque Trfcr. The required cranking torque Tcrn is, for example, a constant cranking torque Tcr that is determined in advance based on, for example, the specifications of the engine 12.

[0041] When starting the engine 12 during EV driving, the start control unit 92d causes the electric motor MG to output an electric motor torque Tmg equivalent to the required cranking torque Tcrn in addition to the electric motor torque Tmg for EV driving, that is, the electric motor torque Tmg that generates the driving torque Tr. Therefore, during EV driving, it is necessary to secure the required cranking torque Tcrn in preparation for starting the engine 12. Therefore, the range in which the required driving torque Trdem can be satisfied only by the output of the electric motor MG is a torque range obtained by subtracting the required cranking torque Tcrn from the maximum torque of the electric motor MG that can be output. The maximum torque of the electric motor MG that can be output is the maximum electric motor torque Tmg that can be output by the dischargeable power Wout of the battery 54.

[0042] The shift control unit 96 judges whether or not to shift the automatic transmission 24 by using, for example, a shift map which is a predetermined relationship, and outputs a CB hydraulic control signal Sbc to the hydraulic control circuit 56 for executing shift control of the automatic transmission 24 as necessary. The shift map is a predetermined relationship having a shift line for judging whether or not to shift the automatic transmission 24 on a two-dimensional coordinate system having, for example, vehicle speed V and required driving torque Trdem as variables. In the shift map, the AT output rotation speed No or the like may be used instead of the vehicle speed V, and the required driving force Frdem, accelerator opening θacc, throttle valve opening θth or the like may be used instead of the required driving torque Trdem.

[0043] From here, the control function of the electronic control device 90 will be described in more detail, taking as an example a case where the start control of the engine 12 is executed by the early ignition start method. The early ignition start method is a method in which the K0 clutch 20 is engaged and cranked by the electric motor MG, fuel is injected and ignited into the engine 12 before the synchronization of the K0 clutch 20, and when the combustion can be continued, the K0 clutch 20 is temporarily released, and then the K0 clutch 20 is re-engaged. In the early ignition start method, fuel is injected and ignited near the compression TDC (Top Dead Center) when the engine speed Ne is low, and the engine 12 is started. Note that the "start" of the engine 12 here refers not only to the time when the engine 12 is completely exploded (starts operation) and can operate independently, but also to a series of control operations related to engine start until the K0 clutch 20 is fully engaged. When the K0 clutch 20 is re-engaged, it is determined that the engine 12 is fully engaged, that is, that the synchronization between the engine 12 and the electric motor MG is completed, and the engine start control is completed.

[0044] When the K0 clutch 20 is re-engaged in the early ignition start method, the required cranking torque Tcrn (=K0 torque Tk0) is transmitted from the electric motor MG to the engine 12 side in order to increase the engine speed Ne and synchronize it with the electric motor speed Nmg. For example, ideally, when the actual rotation difference ΔN0 (=Nmg-Ne) [rpm], which is the difference between the electric motor speed Nmg and the engine speed Ne, is a positive value, the start control unit 92d sets the K0 torque Tk0 to a positive value in order to increase the engine speed Ne. When the actual rotation difference ΔN0 is a negative value, the start control unit 92d sets the K0 torque Tk0 to a negative value in order to decrease the engine speed Ne. As a result, the engine speed Ne is increased or decreased toward the electric motor speed Nmg. Note that, in reality, it is not possible to output the K0 torque Tk0 from the electric motor MG to the engine 12 without a delay with respect to the actual rotation difference ΔN0. In this specification, in order to facilitate understanding of the invention, it is described that the actual rotation difference ΔN0 can be calculated in the control processing of the electronic control device 90, but in reality, the calculation is performed with a delay.

[0045] The hybrid control unit 92 further includes, functionally, a rotation difference calculation means, that is, a rotation difference calculation unit 92e, and a synchronization determination means, that is, a synchronization determination unit 92f.

[0046] The rotation difference calculation unit 92e sequentially calculates a plurality of rotation differences with different smoothing degrees for the actual rotation difference ΔN0 (=Nmg-Ne). The smoothing degree is the degree of slowness of the change rate in the rotation difference calculated from the rotation difference ΔN0. For example, the first rotation difference ΔN1 [rpm] and the second rotation difference ΔN2 [rpm] are moving averages of the rotation difference ΔN0, and the smoothing degree can be increased by increasing the moving average period τ (the acquisition period of the rotation difference ΔN0, which is data when calculating the moving average) [ms]. The moving average period τ corresponds to the "smoothing degree" in the present invention. The rotation difference calculation unit 92e sequentially calculates the first rotation difference ΔN1 calculated with a predetermined moving average period τ1 and the second rotation difference ΔN2 calculated with a moving average period τ2 (<τ1) shorter than the predetermined moving average period τ1. That is, the first rotation difference ΔN1 has a larger smoothing degree than the second rotation difference ΔN2. The predetermined moving average period τ1 is a period determined experimentally or by design so that the first rotation difference ΔN1 converges faster than the actual rotation difference ΔN0. For example, the predetermined moving average period τ1 is determined to be longer than the period T based on a period T {a duration of a positive or negative value when the second rotation difference ΔN2 is inverted due to a misadjusted torque being output from the motor MG caused by a deviation (positive / negative inversion with the opposite sign) between the actual rotation difference ΔN0 and the second rotation difference ΔN2} [ms] described later. The predetermined moving average period τ2 is a period determined experimentally or by design so that the difference (absolute value) between the actual rotation difference ΔN0 and the second rotation difference ΔN2 is small. Preferably, the predetermined moving average period τ2 is set to a period short enough to remove noise components that have an influence on the output torque control of the motor MG beyond an allowable range.

[0047] The synchronization determination unit 92f determines whether the engine 12 and the electric motor MG are synchronized based on the first rotation difference ΔN1 calculated by the rotation difference calculation unit 92e. Determining that the engine 12 and the electric motor MG are synchronized is equivalent to determining that the K0 clutch 20 is fully engaged. For example, when the state in which the first rotation difference ΔN1 is within a range of a synchronization determination width [rpm] including a predetermined zero value continues for a predetermined period Tcon [ms], it is determined that the synchronization is completed. When the state in which the first rotation difference ΔN1 is within the range of the synchronization determination width does not continue for the predetermined period Tcon, it is impossible to distinguish whether the K0 clutch 20 is not fully engaged and a slip occurs in the K0 clutch 20, or the K0 clutch 20 is fully engaged but the engine connecting shaft 34 and the electric motor connecting shaft 36 are twisted due to the influence of the damper 42. Therefore, it is not determined that the synchronization is completed. The synchronization determination width and the predetermined period Tcon are each a determination value that is determined in advance experimentally or by design in order to determine that synchronization between the engine 12 and the electric motor MG has been completed.

[0048] When the synchronization determination unit 92f determines that synchronization is not completed, the start control unit 92d continues to execute the start control of the engine 12. In the start control of the engine 12, the start control unit 92d controls the engine 12 and the electric motor MG based on the second rotation difference ΔN2 calculated by the rotation difference calculation unit 92e. For example, the start control unit 92d controls the required cranking torque Tcrn (cranking reaction torque Trfcr, which is equal to the K0 torque Tk0) output by the electric motor MG to the engine 12 in accordance with the switching of the K0 clutch 20 to the engaged state by the clutch control unit 94 based on the second rotation difference ΔN2.

[0049] Here, the period T is defined as a duration of a positive or negative value when the second rotation difference ΔN2 is inverted in positive or negative due to a misadjusted torque being output from the electric motor MG caused by a deviation (positive / negative inversion in which the sign is reversed) between the actual rotation difference ΔN0 and the second rotation difference ΔN2. Hereinafter, this period T may be referred to as a "period T of positive / negative inversion." Preferably, when the period T of the second rotation difference ΔN2 is shorter than a predetermined judgment period Tjdg [ms] that is set in advance, the start control unit 92d prevents the electric motor MG from outputting the K0 torque Tk0 to the engine 12. Note that the predetermined judgment period Tjdg is a judgment value for judging that the period T is generated only due to the influence of the damper 42 or the running state of the vehicle 10 (for example, vibration of the damper 42), and is a value that is determined in advance experimentally or by design.

[0050] When the synchronization determination unit 92f determines that synchronization is complete, the start control unit 92d ends the start control of the engine 12, and the hybrid control unit 92 executes normal hybrid control other than when the engine is started.

[0051] Fig. 2 is an example of a flowchart illustrating the control operation of the electronic control device 90 shown in Fig. 1. The flowchart in Fig. 2 is repeatedly executed during execution of start control of the engine 12 while the vehicle is traveling.

[0052] First, in step S10 (hereinafter, step will be omitted) corresponding to the function of the rotation difference calculation unit 92e, the first rotation difference ΔN1 and the second rotation difference ΔN2 are calculated. Next, in S20 corresponding to the function of the synchronization determination section 92f, a synchronization determination at engine start is performed based on the first rotation difference ΔN1, and in S30 corresponding to the function of the synchronization determination section 92f, it is determined whether or not synchronization has been completed.

[0053] If the determination in S30 is negative, the output torque control of the electric motor MG at the time of engine startup is executed based on the second rotational speed difference ΔN2 in S40 corresponding to the function of the startup control unit 92d, and then the process returns. If the determination in S30 is positive, the process returns.

[0054] Fig. 3 is an example of a time chart when the flowchart of Fig. 2 is executed. The horizontal axis of Fig. 3 is time t [ms].

[0055] In FIG. 3, with respect to the rotational difference calculated from the electric motor rotational speed Nmg and the engine rotational speed Ne, the actual rotational difference ΔN0 is shown by a thin solid line, the first rotational difference ΔN1 is shown by a dashed line, and the second rotational difference ΔN2 is shown by a thick solid line.

[0056] At time t0, fuel is injected into the engine 12 and ignited by the early ignition start method, and the combustion continues (eg, idling state), and the K0 clutch 20 is temporarily released.

[0057] At time t1 (>t0), prior to re-engagement of the K0 clutch 20, an increase in output of the K0 torque Tk0 is started in order to ensure the required cranking torque Tcrn to be transmitted from the electric motor MG to the engine 12. During the period from time t1 to time t2 (>t1), the K0 torque Tk0 is increased, and at time t2, the required cranking torque Tcrn is ensured from the electric motor MG.

[0058] At time t2, engagement control is started to re-engage the K0 clutch 20. As a result, in the period from time t2 to time t3, the engine rotation speed Ne starts to increase toward the electric motor rotation speed Nmg.

[0059] At time t3 (>t2), the actual engine speed Ne is equal to the motor speed Nmg, i.e., the actual rotation difference ΔN0 is zero, but the second rotation difference ΔN2 is delayed with respect to the rotation difference ΔN0, so the second rotation difference ΔN2 is a negative value. Since the K0 torque Tk0 output from the motor MG is adjusted based on the negative second rotation difference ΔN2, the positive K0 torque Tk0 is erroneously adjusted and output between time t3 and time t4. During the period when the positive K0 torque Tk0 is output, the actual rotation difference ΔN0 is a positive value, so the vibration of the damper 42 is promoted. This erroneous adjustment is caused by delays in the communication time from the sensor (engine speed sensor 70 or turbine speed sensor 72) to the electronic control device 90 when the second rotation difference ΔN2 is calculated, the calculation time of the second rotation difference ΔN2, and the response time from the control instruction to the motor MG via the inverter 52 to the start of control, etc. In other words, due to this delay, the actual rotational difference ΔN0 is reversed by the time the K0 torque Tk0 commanded by the electronic control device 90 is reflected in the motor torque Tmg, resulting in control with the positive and negative polarities reversed with respect to the actual rotational difference ΔN0.

[0060] At time t4 (>t3), the actual engine speed Ne is equal to the motor speed Nmg, i.e., the actual rotation difference ΔN0 is zero, but since the second rotation difference ΔN2 is delayed with respect to the rotation difference ΔN0, the second rotation difference ΔN2 is a positive value. Based on this positive second rotation difference ΔN2, the negative K0 torque Tk0 is erroneously adjusted and output between time t4 and time t5 (>t4). During the period when this negative K0 torque Tk0 is output, the actual rotation difference ΔN0 is negative, which promotes vibration of the damper 42.

[0061] Since the period T from time tx (>t3) when the second rotation difference ΔN2 switches from a negative value to a positive value to time ty (>t4) when the second rotation difference ΔN2 switches from a positive value to a negative value after time tx is shorter than the predetermined judgment period Tjdg, it is determined that the positive and negative are reversed in a short period of time at time ty. That is, it is determined whether the period T of the positive and negative reversal of the second rotation difference ΔN2 is shorter than the predetermined judgment period Tjdg. After the time ty when it is determined that the period T of the positive and negative reversal of the second rotation difference ΔN2 is shorter than the predetermined judgment period Tjdg, the output of the K0 torque Tk0 is stopped, that is, the K0 torque Tk0 is set to zero.

[0062] After time t5, the actual rotation difference ΔN0 and the second rotation difference ΔN2 oscillate between positive and negative values ​​for a while, but the oscillation amplitude gradually decreases.

[0063] On the other hand, after time t2, the first rotation difference ΔN1 changes more slowly than the second rotation difference ΔN2, from a negative value to zero, lagging behind the change in the actual rotation difference ΔN0. At time tp (>t5), the first rotation difference ΔN1 falls within the synchronization judgment width, and at time tq (>tp), the state in which the first rotation difference ΔN1 remains within the synchronization judgment width for a predetermined period Tcon, and it is determined that synchronization is completed. Comparative Example 1

[0064] FIG. 4 is an example of a time chart according to Comparative Example 1. In the above-mentioned embodiment, the synchronization judgment is performed based on the first rotation difference ΔN1, and the K0 torque Tk0 output from the motor MG is adjusted based on the second rotation difference ΔN2. However, in this comparative example, the synchronization judgment and the adjustment of the K0 torque Tk0 output from the motor MG are both performed based on the second rotation difference ΔN2, which is different from the above-mentioned embodiment. In addition, in this comparative example, the output of the K0 torque Tk0 is not stopped because the period T of the positive / negative inversion of the second rotation difference ΔN2 is not determined to be shorter than the predetermined judgment period Tjdg. Therefore, the following description will focus on the parts that are different from FIG. 3, and the same reference numerals will be used to denote substantially common parts, and the description will be omitted as appropriate.

[0065] In FIG. 4, regarding the rotation difference calculated from the electric motor rotation speed Nmg and the engine rotation speed Ne, the actual rotation difference ΔN0 is indicated by a thin solid line, and the second rotation difference ΔN2 is indicated by a thick solid line.

[0066] After time t5, the positive K0 torque Tk0 is output during the period when the actual rotation difference ΔN0 is positive, and the negative K0 torque Tk0 is output during the period when the actual rotation difference ΔN0 is negative, so that the vibration of the damper 42 is further promoted compared to the above-mentioned embodiment. That is, the vibration of the damper 42 is promoted by the erroneous adjustment of the K0 torque Tk0 due to the deviation (positive / negative reversal of the sign) between the actual rotation difference ΔN0 and the second rotation difference ΔN2. This promotion of the vibration of the damper 42 makes it difficult for the second rotation difference ΔN2 to converge.

[0067] In this comparative example, since the synchronization determination is performed based on the second rotation difference ΔN2, the state in which the second rotation difference ΔN2 is within the synchronization determination width is less likely to continue for the predetermined period Tcon compared to the above-mentioned embodiment, and the determination that the synchronization is complete is more likely to be delayed. Therefore, in this comparative example, the completion of the engine start control is more likely to be delayed compared to the above-mentioned embodiment. Comparative Example 2

[0068] FIG. 5 is an example of a time chart according to Comparative Example 2. In the above-mentioned embodiment, the synchronization determination is performed based on the first rotation difference ΔN1, and the K0 torque Tk0 output from the motor MG is adjusted based on the second rotation difference ΔN2. However, in this comparative example, both the synchronization determination and the adjustment of the K0 torque Tk0 output from the motor MG are performed based on the first rotation difference ΔN1, which is different from the above-mentioned embodiment. In addition, in this comparative example, the output of the K0 torque Tk0 is not stopped because the period T of the positive / negative inversion of the first rotation difference ΔN1 (the second rotation difference ΔN2 in the above-mentioned embodiment) is not determined to be shorter than the predetermined judgment period Tjdg. Therefore, the following description will focus on the parts that are different from FIG. 3, and the same reference numerals will be used to denote substantially common parts, and the description will be omitted as appropriate.

[0069] In FIG. 5, regarding the rotational difference calculated from the motor rotational speed Nmg and the engine rotational speed Ne, the actual rotational difference ΔN0 is shown by a solid line, and the first rotational difference ΔN1 is shown by a broken line. Also, regarding the K0 torque Tk0, the present comparative example is shown by a solid line, and that for the aforementioned embodiment is shown by a broken line for reference.

[0070] At time t3, the actual engine rotational speed Ne becomes the same value as the motor rotational speed Nmg. Compared with the second rotational difference ΔN2 in the aforementioned embodiment, since the first rotational difference ΔN1 changes gently from a negative value toward zero following the change in the actual rotational difference ΔN0, the state where the first rotational difference ΔN1 is a negative value continues even after time t3. Since the K0 torque Tk0 output from the motor MG is adjusted based on this negative first rotational difference ΔN1, a positive K0 torque Tk0 continues to be output during the period after time t3 (the period from time t3 to time tv). Regarding the period from time tu (t3 < tu < tv) to time tv within the period from time t3 to time tv (>t3), compared with the K0 torque Tk0 in the aforementioned embodiment, an unnecessary K0 torque Tk0 is output, and the K0 torque Tk0 is excessive. That is, the K0 torque Tk0 has become excessive due to the misadjustment of the K0 torque Tk0 by the difference (absolute value) between the actual rotational difference ΔN0 and the first rotational difference ΔN1, and the vibration of the damper 42 is promoted by this excessive K0 torque Tk0. In the present comparative example, compared with the aforementioned embodiment, due to the excessive K0 torque Tk0, the rising widths of the engine rotational speed Ne and the motor rotational speed Nmg after time t3 are likely to be large.

[0071] According to this embodiment, (a) when the K0 clutch 20 is engaged and the engine 12 is started by cranking the electric motor MG, a first rotation difference ΔN1 between the engine rotation speed Ne and the electric motor rotation speed Nmg for determining synchronization between the engine 12 and the electric motor MG is sequentially calculated, (b) a second rotation difference ΔN2 between the engine rotation speed Ne and the electric motor rotation speed Nmg for use in controlling the output torque of the electric motor MG when the engine 12 is started is sequentially calculated, and (c) the first rotation difference ΔN1 is smoothed to a greater extent than the second rotation difference ΔN2. When the smoothing degree of the first rotation difference ΔN1 for determining synchronization between the engine 12 and the electric motor MG is greater than the smoothing degree of the second rotation difference ΔN2 for use in controlling the output torque of the electric motor MG, the deviation (positive / negative sign reversal) between the actual rotation difference ΔN0 and the rotation difference used for determining synchronization is suppressed compared to other cases, and the output of erroneously adjusted torque from the electric motor MG is suppressed. This suppresses the delay in the convergence of the first rotation difference ΔN1 used to determine synchronization when the engine 12 is started, thereby suppressing the delay in the completion of the engine start control. Also, when the smoothing degree of the second rotation difference ΔN2 used to control the output torque of the electric motor MG when the engine 12 is started is smaller than the smoothing degree of the first rotation difference ΔN1 for determining synchronization between the engine 12 and the electric motor MG, the difference (absolute value) between the actual rotation difference ΔN0 and the second rotation difference ΔN2 used to control the output torque of the electric motor MG becomes smaller than in other cases. This suppresses the torque transmitted as the cranking reaction torque Trfcr from the electric motor MG via the K0 clutch 20 to the engine 12, i.e., the K0 torque Tk0, from becoming excessive.

[0072] 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.

[0073] In the above-described embodiment, the second rotational difference ΔN2 was used to control the output torque of the electric motor MG when the engine 12 was started, but this is not limited to the above, and the second rotational difference ΔN2 may be used for control other than determining synchronization.

[0074] In the above embodiment, the actual rotation difference ΔN0 (=Nmg-Ne) is calculated, and then the moving average of this rotation difference ΔN0 is calculated sequentially, but for example, the moving averages of the engine rotation speed Ne and the electric motor rotation speed Nmg are calculated sequentially, and then the moving average of the engine rotation speed Ne is subtracted sequentially from the moving average of the electric motor rotation speed Nmg. In short, with regard to the first rotation difference ΔN1 and the second rotation difference ΔN2 that are finally calculated sequentially, it is sufficient that the first rotation difference ΔN1 is smoothed to a greater extent than the second rotation difference ΔN2.

[0075] In the above embodiment, when it is determined that the period T of positive / negative reversal of the second rotation difference ΔN2 is shorter than the predetermined judgment period Tjdg, the output of the K0 torque Tk0 is stopped, but in the present invention, the output of the K0 torque Tk0 does not necessarily have to be stopped. Even if the output of the K0 torque Tk0 is not stopped, the first rotation difference ΔN1 is used to determine the synchronization between the engine 12 and the electric motor MG, and the delay in the convergence of the first rotation difference ΔN1 used to determine the synchronization when the engine 12 is started is suppressed compared to when the second rotation difference ΔN2 is used, thereby suppressing the delay in the completion of the engine start control.

[0076] In the above embodiment, the torque converter 22 is used as the fluid transmission device, but the present invention is not limited to this. For example, other fluid transmission devices, such as a fluid coupling that does not amplify torque, may be used as the fluid transmission device instead of the torque converter 22. Also, the fluid transmission device does not necessarily have to be provided, and may be replaced with, for example, a starting clutch.

[0077] It should be noted that the above is merely an embodiment 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]

[0078] 10: Hybrid vehicles 12: Engine 20:K0 clutch (clutch) 90: Electronic control device (control device) MG: Electric motor Ne: Engine speed Nmg: Motor rotation speed ΔN1: First rotation difference ΔN2: Second rotation difference τ, τ1-τ2: moving average period (degree of smoothing)

Claims

1. A control device for a hybrid vehicle including an engine, an electric motor, and a clutch provided between the engine and the electric motor, when the clutch is engaged and the engine is started by cranking the electric motor, sequentially calculating a first rotation difference between an engine rotation speed and an electric motor rotation speed for determining synchronization between the engine and the electric motor; sequentially calculating a second rotation difference between the engine rotation speed and the electric motor rotation speed for use in control other than the determination of synchronization; The first rotation difference is smoothed to a greater degree than the second rotation difference. A control device for a hybrid vehicle.

2. The control other than the determination of synchronization is the output torque control of the electric motor when the engine is started.

2. The control device for a hybrid vehicle according to claim 1.

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