Control system for hybrid vehicles

Abstract

To provide a control device of a hybrid vehicle capable of achieving both hardware protection and convenience of a driver in launch control.SOLUTION: At least one of rotational speed of an engine and torque capacity of a clutch itself during start standby transition is set to a lower value in a case where at least one of temperature of cooling oil and temperature of the clutch itself until a start time point of the launch control is high compared to a case where at least one of the temperature of the cooling oil and the temperature of the clutch itself is low. Accordingly, when at least one of the temperature of the cooling oil and the temperature of the clutch itself is high, heat generation of the clutch is easily suppressed, and thus it is possible to avoid a situation in which the launch control can be performed only when the temperature is low. Therefore, it is possible to achieve both hardware protection and convenience of a driver during the launch control.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a control device for a hybrid vehicle that starts by controlling the clutch to be switched to an engaged state while slipping. [Background Art]

[0002] A control device for a hybrid vehicle comprising a power source including an engine and an electric motor, and a clutch provided in a power transmission path between the power source and drive wheels is well known. For example, the control device for a hybrid vehicle described in Patent Document 1 is one such example. This Patent Document 1 discloses that when starting, the engine torque is increased and the clutch is switched from a released state to an engaged state. Patent Document 1 also discloses that the electric motor generates electric power using the output of the engine, thereby reducing the torque input from the engine to the clutch. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2019-108021 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] In this case, launch control is sometimes performed, which involves increasing the engine torque while transitioning the clutch from a slipped state to an engaged state, with the engine speed and torque already increased. In this case, during the transient period of waiting to start with the brakes and accelerator pressed, it is conceivable to generate regenerative torque from the electric motor and the torque capacity of the clutch to maintain the clutch in a slipped state so that it can handle the engine torque, preparing for starting after the brakes are released. However, while maintaining the clutch in a slipped state can improve responsiveness during starting, it is prone to overheating during the transient period of waiting to start and during the transient period of starting. If the clutch overheats too much, its durability may decrease. In that case, depending on the degree of clutch overheating, launch control may have to be stopped to ensure durability or protect the hardware, which may reduce the convenience for the driver.

[0005] This invention was made against the above circumstances, and its objective is to provide a control device for a hybrid vehicle that can achieve both hardware protection and driver convenience during launch control. [Means for solving the problem]

[0006] The gist of the first invention is a control device for a hybrid vehicle comprising (a) a power source including an engine and an electric motor, and a clutch provided in a power transmission path between the power source and the drive wheels, wherein (b) during a starting standby transient with the brake on and the accelerator on, the rotational speed and torque of the engine are increased in advance to values ​​prepared for starting after the brake is released, and the regenerative torque of the electric motor and the torque capacity of the clutch that maintains the clutch in a slip state are generated to handle the torque of the engine, and After releasing the brakes(c) The starting control unit performs starting control by increasing the torque of the engine while transitioning the clutch from a slip state to an engaged state during the starting transient, and (c) the starting control unit sets at least one of the rotational speed of the engine and the torque capacity of the clutch during the starting standby transient to a lower value compared to the case where at least one of the temperature of the cooling oil for the clutch and the temperature of the clutch itself is high up to the start of the starting control. [Effects of the Invention]

[0007] According to the first invention, if at least one of the cooling oil temperature and the clutch temperature itself is high up to the start of launch control, at least one of the engine rotational speed and clutch torque capacity during the launch standby transient is set to a lower value compared to when they are low. This makes it easier to suppress clutch heat generation when at least one of the cooling oil temperature and the clutch temperature itself is high, thus avoiding a situation where launch control can only be performed when the temperature is low. Therefore, it is possible to achieve both hardware protection and driver convenience during launch control. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram illustrates the schematic configuration of a vehicle to which the present invention is applied, as well as the main parts of the control functions and control systems for various control functions in the vehicle. [Figure 2] This diagram illustrates an example of how launch control works. [Figure 3] This flowchart explains the key aspects of the control operation of an electronic control unit, specifically the control operation that balances hardware protection and driver convenience during launch control. [Figure 4]Figure 3 shows an example of a time chart when the control operation shown in the flowchart is performed, illustrating a control that changes the settings during the launch standby transient based on the temperature before launch control is initiated. [Figure 5] Figure 3 is a diagram showing an example of a time chart when the control operation shown in the flowchart is performed, illustrating a control that changes the initial settings based on the temperature during the launch standby transient. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. [Examples]

[0010] Figure 1 is a diagram illustrating the schematic configuration of a vehicle 10 to which the present invention is applied, as well as illustrating the main parts of the control functions and control systems for various controls in the vehicle 10. In Figure 1, the vehicle 10 is a hybrid vehicle equipped with an engine 12 and an electric motor MG that function as a power source SP. The vehicle 10 also includes drive wheels 14 and a power transmission device 16 provided in the power transmission path between the engine 12 and the drive wheels 14.

[0011] The engine 12 is, for example, a known internal combustion engine having a supercharger. The engine torque Te of the engine 12 is controlled by an engine control device 50 provided in the vehicle 10, which is controlled by an electronic control device 90, which will be described later.

[0012] The electric motor MG is a known rotating electric machine, a so-called motor generator. The electric motor MG is connected to a battery 54 provided in the vehicle 10 via an inverter 52 provided in the vehicle 10. The motor torque Tm of the electric motor MG is controlled by the control of the inverter 52 by an electronic control device 90, which will be described later.

[0013] The power transmission device 16 is housed in a case 18, which is a non-rotating member attached to the vehicle body, and includes a damper 20, a disengagement clutch K0, a starting clutch WSC, an automatic transmission 22, and the like. The damper 20 is located between the engine 12 and the disengagement clutch K0 in the power transmission path between the engine 12 and the drive wheels 14. The disengagement clutch K0 is located between the engine 12 and the electric motor MG in the power transmission path between the engine 12 and the drive wheels 14. The starting clutch WSC is located between the electric motor MG and the automatic transmission 22 in the power transmission path between the engine 12 and the drive wheels 14. The starting clutch WSC is a clutch located in the power transmission path between the power source SP and the drive wheels 14. The automatic transmission 22 constitutes part of the power transmission path between the power source SP and the drive wheels 14.

[0014] Furthermore, the power transmission device 16 includes a propeller shaft 24 connected to the transmission output shaft 22o, a differential gear 26 connected to the propeller shaft 24, a pair of drive shafts 28 connected to the differential gear 26, and the like. The transmission output shaft 22o is the output rotating member of the automatic transmission 22. The power transmission device 16 also includes, within the case 18, an engine connecting shaft 30 connecting the engine 12 and the damper 20, a damper connecting shaft 32 connecting the damper 20 and the engagement / disengagement clutch K0, and an electric motor connecting shaft 34 connecting the engagement / disengagement clutch K0 and the starting clutch WSC. The power transmission device 16 also includes, within the case 18, a mechanical oil pump 36, which is a mechanical oil pump, and a transmission member 38 connecting the electric motor connecting shaft 34 and the mechanical oil pump 36.

[0015] The electric motor MG is connected within the case 18 to the motor coupling shaft 34, that is, to the power transmission path between the engine 12 and the drive wheels 14, so as to be able to transmit power.

[0016] The disconnecting clutch K0 is, for example, a known frictional engagement device. The control state of the disconnecting clutch K0 is switched by changing the disconnecting clutch torque Tk0 via the disconnecting clutch hydraulic pressure PRk0. The disconnecting clutch hydraulic pressure PRk0 is the pressure-regulated hydraulic pressure for the disconnecting clutch K0 supplied from a hydraulic control circuit 56 provided in a vehicle 10. The disconnecting clutch torque Tk0 is the torque capacity of the disconnecting clutch K0, that is, the clutch torque. The control state of the engagement device is an operating state such as an engaged state, a released state, or a slip state.

[0017] The starting clutch WSC is a known wet-type frictional engagement device configured by, for example, a multi-plate clutch pressed by a hydraulic actuator. The control state of the starting clutch WSC is switched by changing the starting clutch torque Twsc via the starting clutch hydraulic pressure PRwsc. The starting clutch hydraulic pressure PRwsc is the pressure-regulated hydraulic pressure for the starting clutch WSC supplied from the hydraulic control circuit 56. The starting clutch torque Twsc is the torque capacity of the starting clutch WSC.

[0018] The automatic transmission 22 is a known planetary gear type automatic transmission including, for example, a planetary gear device and an engagement device CB. The engagement device CB includes, for example, a plurality of known frictional engagement devices. For each engagement device CB, the control state is switched by changing the shift engagement torque Tcb via the shift engagement hydraulic pressure PRcb. The shift engagement hydraulic pressure PRcb is the pressure-regulated hydraulic pressure for the engagement device CB supplied from the hydraulic control circuit 56. The shift engagement torque Tcb is the torque capacity of the engagement device CB. In the automatic transmission 22, any one of a plurality of shift speeds (also referred to as gear speeds) having different gear ratios γat (also referred to as gear ratio, γat = Ni / No) is formed by engagement of any one of the engagement devices CB. "Ni" is the transmission input rotational speed Ni, which is the rotational speed of a transmission input shaft 22i that is an input rotating member of the automatic transmission 22. "No" is the transmission output rotational speed No, which is the rotational speed of a transmission output shaft 22o.

[0019] The mechanical oil pump 36 is rotationally driven by the power source SP to discharge oil FLD. In the vehicle 10, the oil FLD discharged by the mechanical oil pump 36 and the electric oil pump 58 provided in the vehicle 10 is supplied to the hydraulic control circuit 56. The electric oil pump 58 is an electric oil pump that is rotationally driven by a pump motor 60 provided in the vehicle 10 to discharge oil FLD. The hydraulic control circuit 56 supplies connection / disconnection clutch hydraulic pressure PRk0, starting clutch hydraulic pressure PRwsc, shift engagement hydraulic pressure PRcb, etc., each pressure-regulated based on the oil FLD from the mechanical oil pump 36 and the electric oil pump 58. In addition, the oil FLD is used for lubricating each part of the power transmission device 16 and cooling the starting clutch WSC and the like. The oil FLD also functions as cooling oil for the starting clutch WSC. The oil FLD is hydraulic fluid for operating the automatic transmission 22 and the like.

[0020] The vehicle 10 is provided with an electronic control unit 90 serving as a controller including a control device for the vehicle 10. The electronic control unit 90 is configured to include, for example, a so-called microcomputer provided with a CPU, RAM, ROM, input / output interface, and the like. The CPU performs signal processing according to a program stored in advance in ROM while utilizing the temporary storage function of RAM

[0021] Various signals based on detection values from various sensors provided in the vehicle 10 are respectively supplied to the electronic control unit 90. The various sensors include, for example, an engine rotational speed sensor 70, an electric motor rotational speed sensor 72, an input rotational speed sensor 74, an output rotational speed sensor 76, an accelerator opening sensor 78, a throttle valve opening sensor 80, a brake switch 82, an oil temperature sensor 84, and the like. The various signals include, for example, engine rotational speed Ne, electric motor rotational speed Nm, transmission input rotational speed Ni, transmission output rotational speed No, accelerator opening θacc, throttle valve opening θth, brake-on signal Bon, oil temperature THoil, and the like.

[0022] Engine rotational speed Ne is the rotational speed of engine 12. Electric motor rotational speed Nm is the rotational speed of electric motor MG, and is also the rotational speed of the input side member of the starting clutch WSC. Transmission input rotational speed Ni is also the rotational speed of the output side member of the starting clutch WSC. Transmission output rotational speed No is also the rotational speed corresponding to the vehicle speed V. Accelerator opening θacc is a signal that represents the magnitude of the driver's acceleration operation, and is the amount of accelerator operation by the driver. Throttle valve opening θth is a signal that represents the opening degree of the electronic throttle valve. Brake-on signal Bon is a signal that indicates that the brake pedal for activating the wheel brakes is being operated by the driver. Oil temperature THoil is the temperature of the oil FLD in the hydraulic control circuit 56.

[0023] The electronic control unit 90 outputs various command signals to each device installed in the vehicle 10. These devices include, for example, an engine control unit 50, an inverter 52, a hydraulic control circuit 56, and a pump motor 60. The various command signals include, for example, an engine control command signal Se, an electric motor control command signal Sm, a clutch engagement / disengagement hydraulic control command signal Sk0, a starting clutch hydraulic control command signal Swsc, a gear shift engagement hydraulic control command signal SCB, and an electric oil pump control command signal Seop.

[0024] The electronic control unit 90 includes a power source control unit 92, a hydraulic control unit 94, and a starting control unit 96 in order to perform various controls on the vehicle 10.

[0025] The power source control unit 92 includes functions for controlling the operation of the engine 12 and the operation of the electric motor MG, and these control functions enable hybrid drive control of the engine 12 and the electric motor MG.

[0026] The power source control unit 92 calculates the driver's drive request Qrdem for the vehicle 10 by applying the accelerator opening θacc and vehicle speed V to a predetermined drive request map, for example. The drive request Qrdem is, for example, the required drive torque Trdem [Nm] or required drive force Frdem [N] at the drive wheels 14. The required drive torque Trdem is, conversely, the required drive power Prdem [W] at the vehicle speed V at that time. The power source control unit 92 outputs an engine control command signal Se to control the engine 12 and an electric motor control command signal Sm to control the electric motor MG, taking into account transmission losses, auxiliary loads, the gear ratio of the automatic transmission 22, etc., in order to realize the drive request Qrdem.

[0027] The power source control unit 92 sets the drive mode for driving the vehicle 10 to BEV drive mode when the drive requirement Qrdem can be met by the output of the electric motor MG alone. The BEV drive mode is a motor drive mode in which motor driving (=BEV driving) is possible when the engine 12 is stopped and the disengaged clutch K0 is released, using only the electric motor MG as the power source. On the other hand, the power source control unit 92 sets the drive mode to engine drive mode, i.e., HEV drive mode, when the drive requirement Qrdem cannot be met without using at least the output of the engine 12. The HEV drive mode is a hybrid drive mode in which engine driving (=HEV driving) is possible when the disengaged clutch K0 is engaged, using at least the engine 12 as the power source. On the other hand, even when the drive requirement Qrdem can be met by the output of the electric motor MG alone, the power source control unit 92 sets the HEV drive mode when charging the battery 54 is necessary or when warming up the engine 12, etc., is necessary.

[0028] The power source control unit 92 determines whether there is an engine start request when the BEV drive mode is active, based on whether the drive request amount Qrdem has increased beyond the range that can be covered by the output of the electric motor MG alone, whether the engine 12 or the like needs to be warmed up, or whether the battery 54 needs to be charged.

[0029] When the power source control unit 92 determines that there is an engine start request, the hydraulic control unit 94 controls the engagement / disengagement clutch K0 to execute engine start control for the engine 12. For example, the hydraulic control unit 94 outputs an engagement / disengagement clutch hydraulic control command signal Sk0 to control the engagement / disengagement clutch K0 from the released state toward the engaged state so that an engagement / disengagement clutch torque Tk0 is obtained to transmit the cranking torque Tcr to the engine 12. The cranking torque Tcr is a predetermined torque required to crank the engine 12 in order to increase the engine rotational speed Ne.

[0030] When the power source control unit 92 determines that there is an engine start request, it controls the engine 12 and the electric motor MG to perform engine start control. For example, in conjunction with the switching of the engagement clutch K0 by the hydraulic control unit 94 to the engaged state, the power source control unit 92 outputs an electric motor control command signal Sm for the electric motor MG to output cranking torque Tcr. In addition, the power source control unit 92 outputs an engine control command signal Se in conjunction with the cranking of the engine 12 to start fuel supply, engine ignition, etc.

[0031] The hydraulic control unit 94, for example, uses a predetermined shift map to determine the shift of the automatic transmission 22 and outputs a shift engagement hydraulic control command signal Sb to the hydraulic control circuit 56 to execute shift control by switching the gear position of the automatic transmission 22 as needed.

[0032] The hydraulic control unit 94 controls the starting clutch WSC to remain in the disengaged state, for example, when the vehicle is stationary. The hydraulic control unit 94 also controls the starting clutch WSC to remain in the engaged state, for example, when the vehicle 10 is in motion.

[0033] The starting control unit 96 performs starting control, for example, when starting, by outputting a command to the hydraulic control unit 94 to switch the starting clutch WSC, which is in the disengaged state, to the engaged state while allowing it to slip, and at the same time outputting a command to the power source control unit 92 to increase the engine torque Te. This starting control is also called friction start control.

[0034] Here, in order to achieve high acceleration quickly when starting after releasing the brakes, the accelerator may be applied in addition to the brakes during the starting standby transient while the vehicle is stationary. In this case, it is desirable to increase the power of engine 12 from the starting standby transient. Also, considering the response delay of the starting clutch WSC, it is desirable to increase the starting clutch hydraulic pressure PRwsc to a certain extent from the starting standby transient to generate the starting clutch torque Twsc.

[0035] During the starting standby transient when the brake is applied and the accelerator is pressed, the starting control unit 96 outputs a command to the power source control unit 92 to pre-increase the engine rotational speed Ne and engine torque Te to values ​​prepared for starting after the brake is released. The starting control unit 96 also outputs a command to the power source control unit 92 to generate regenerative torque from the electric motor MG to handle the engine torque Te, and outputs a command to the hydraulic control unit 94 to generate starting clutch torque Twsc to maintain the starting clutch WSC in a slip state. Then, during the starting transient after the brake is released, the starting control unit 96 outputs a command to the hydraulic control unit 94 to transition the starting clutch WSC from a slip state to an engaged state, while simultaneously outputting a command to the power source control unit 92 to increase the engine torque Te. Thus, the launch control unit 96 increases the power of the engine 12 and generates regenerative torque and launch clutch torque Twsc during the launch standby transient with the brake and accelerator on, and performs launch control by increasing the engine torque Te while shifting the launch clutch WSC to the engaged state during the launch transient. This launch control is specifically called launch control within friction start control. In launch control, the engine rotation speed Ne and engine torque Te, which are set to values ​​in advance to prepare for launching after the brake is released, are, for example, predetermined optimal values ​​A that best achieve acceleration performance at launch while ensuring the durability of the launch clutch WSC. Also, in launch control, the launch clutch torque Twsc during the launch standby transient is, for example, a predetermined optimal value A. In launch control, the power of the engine 12 is absorbed by the electric motor MG and launch clutch WSC during the launch standby transient, preparing for acceleration during the subsequent launch transient.

[0036] Figure 2 illustrates an example of operation during launch control. In Figure 2, time t1a indicates the point in time when the brake is applied and the accelerator is pressed, initiating launch control. During launch control, the engine 12 is in operation and the disengagement clutch K0 is engaged. When launch control is initiated, the engine speed Ne and engine torque Te are increased in advance during the transient period of waiting to start while stationary (see time t1a-t2a). At this time, the engine torque Te is received by the electric motor torque Tm and the launch clutch torque Twsc. During the transient period of waiting to start, the power of the engine 12 is increased as much as possible while ensuring the durability of the launch clutch WSC, and the engine speed Ne is increased to improve the supercharging response. In addition, considering the hydraulic response of the launch clutch WSC, the launch clutch torque Twsc is also increased while ensuring the durability of the launch clutch WSC. When the brakes are released (see time t2a), the launch clutch WSC is controlled from a slipping state to an engaged state, and the engine torque Te is increased towards a target value corresponding to the degree of accelerator application (accelerator opening θacc) (see time t2a-t3a). The engine torque Te during the launch standby transient is set, for example, to optimize the increase in engine torque Te in the supercharging region. After launching begins due to the increase in launch clutch torque Twsc, when the launch clutch WSC is switched to the engaged state, that is, when the engine speed Ne and the transmission input speed Ni are synchronized, the launch control is terminated (see time t3a).

[0037] Incidentally, the launch clutch WSC generates heat due to being in a slipping state. In particular, with launch control, the launch clutch WSC is in a slipping state during the transient state of waiting to start and during subsequent acceleration. In addition, to ensure power performance at launch, the differential rotational speed and launch clutch torque Twsc of the launch clutch WSC are set to high values. Therefore, if the temperature has already reached the prerequisite temperature for ensuring the durability of the launch clutch WSC before the start of launch control, the launch control must be stopped to ensure durability or protect the hardware, which may reduce driver convenience. The temperature referred to as the "prerequisite temperature" is, for example, the oil temperature THoil, or the launch clutch temperature THwsc, which is the temperature of the launch clutch WSC itself. In other words, although the launch clutch WSC is cooled by the oil FLD, it generates heat due to "differential rotational speed of the launch clutch WSC × launch clutch torque Twsc," and if it generates too much heat, the durability of the launch clutch WSC may decrease. The differential rotational speed of the starting clutch WSC is the starting clutch differential rotational speed ΔNwsc, which is the difference between the rotational speed of the input side member of the starting clutch WSC (= motor rotational speed Nm) and the rotational speed of the output side member of the starting clutch WSC (= transmission input rotational speed Ni).

[0038] In launch control, where engine 12 is running and clutch K0 is engaged, the motor rotational speed Nm and engine rotational speed Ne are equal. The starting clutch differential rotational speed ΔNwsc is expressed as the difference between the engine rotational speed Ne and the transmission input rotational speed Ni (=Ne-Ni). Therefore, increasing the engine rotational speed Ne or increasing the starting clutch hydraulic pressure PRwsc makes it easier for the starting clutch temperature THwsc to rise during the vehicle stop phase in launch control, i.e., during the launch standby transient.

[0039] Therefore, the launch control unit 96 sets at least one of the engine speed Ne and launch clutch torque Twsc during the launch standby transient to a lower value compared to the case where at least one of the oil temperature THoil and launch clutch temperature THwsc is higher up to the start of launch control. The launch clutch temperature THwsc is an estimated value calculated based on, for example, the oil temperature THoil, the amount of heat generated by the launch clutch WSC, and the flow rate of the oil FLD. The amount of heat generated by the launch clutch WSC is calculated based on "start clutch differential rotational speed ΔNwsc × launch clutch torque Twsc". The flow rate of the oil FLD is calculated based on the rotational speed of the mechanical oil pump 36 and the rotational speed of the electric oil pump 58.

[0040] For example, if the oil temperature THoil and the starting clutch temperature THwsc are below a predetermined threshold C up to the start of launch control, the launch control unit 96 sets the engine speed Ne and the starting clutch torque Twsc to a predetermined optimal value A. On the other hand, if at least one of the oil temperature THoil and the starting clutch temperature THwsc is above threshold C up to the start of launch control, the launch control unit 96 sets at least one of the engine speed Ne and the starting clutch torque Twsc to a value smaller than the predetermined optimal value A. The value smaller than the predetermined optimal value A is, for example, a predetermined appropriate value B that suppresses the deterioration of the durability performance of the starting clutch WSC. The threshold C is, for example, a predetermined lower temperature value at which it is determined that it is better to restrict at least one of the engine speed Ne and the starting clutch torque Twsc during the launch standby transient. The threshold C may be the same value for oil temperature THoil and starting clutch temperature THwsc, or it may be different values ​​for each. Furthermore, monitoring not only the starting clutch temperature (THwsc) but also the oil temperature (THoil) is necessary because, for example, even if the starting clutch temperature (THwsc) is low, if the oil temperature (THoil) is high, the starting clutch temperature (THwsc) is likely to rise quickly.

[0041] The launch clutch temperature (THwsc) is often gradually increased during the launch control's standby transient. In this case, if the launch standby time (TMsd), which is the duration of the launch standby transient, becomes long, the launch clutch temperature (THwsc) is more likely to rise, potentially reducing the durability of the launch clutch (WSC).

[0042] Therefore, if the starting standby time TMsd is greater than or equal to a predetermined threshold D, the starting control unit 96 changes at least one of the engine rotation speed Ne and the starting clutch torque Twsc, which were set at the start of the starting standby, to a value lowered by a predetermined value F. The threshold D is, for example, a predetermined lower limit of time during the starting standby transient in which it is determined that it is better to restrict at least one of the engine rotation speed Ne and the starting clutch torque Twsc from their initial values.

[0043] If the starting clutch temperature THwsc is high, there is a risk that the starting clutch temperature THwsc will quickly rise to a level where the durability of the starting clutch WSC is likely to decrease. For this reason, the threshold D is set to a shorter time when the starting clutch temperature THwsc is high compared to when it is low.

[0044] Alternatively, if the starting clutch temperature THwsc is above a predetermined threshold E during the starting standby transient, the starting control unit 96 changes at least one of the engine rotation speed Ne and starting clutch torque Twsc, which were set at the start of the starting standby, to a value lowered by a predetermined value F. The threshold E is, for example, a predetermined lower limit of temperature at which it is determined that at least one of the engine rotation speed Ne and starting clutch torque Twsc should be restricted from its initial value during the starting standby transient.

[0045] A value lower than the predetermined value F is, for example, a predetermined value at which the starting clutch temperature THwsc saturates at its current value. The value at which the starting clutch temperature THwsc saturates at its current value is a predetermined value at which the cooling performance of the starting clutch WSC by oil FLD and the amount of heat generated in the starting clutch WSC are balanced, and the rise in the starting clutch temperature THwsc stagnates.

[0046] Figure 3 is a flowchart illustrating the essential parts of the control operation of the electronic control unit 90. This flowchart explains the control operation that balances hardware protection and driver convenience during launch control, and is, for example, repeatedly executed.

[0047] In Figure 3, each step in the flowchart corresponds to a function of the launch control unit 96. In step S10 (the step will be omitted hereafter), it is determined whether or not launch control is being performed. If the determination in S10 is negative, this routine is terminated. If the determination in S10 is positive, in S20, it is determined whether or not at least one of the oil temperature THoil and the launch clutch temperature THwsc is greater than or equal to threshold C up to the start of launch control. If the determination in S20 is negative, in S30, the engine speed Ne and the launch clutch torque Twsc are set to a predetermined optimal value A. If the determination in S20 is positive, in S40, at least one of the engine speed Ne and the launch clutch torque Twsc is constrained and set to a value smaller than the predetermined optimal value A. Following S30, or following S40, in S50, it is determined whether or not the launch waiting time TMsd is greater than or equal to threshold D, or whether or not the launch clutch temperature THwsc is greater than or equal to threshold E. If the judgment in S50 is affirmative, in S60, at least one of the values ​​of engine speed Ne and launch clutch torque Twsc, which were set at the start of the launch standby, is changed to a value lower by a predetermined value F. If the judgment in S50 is negative, or following S60, in S70, it is determined whether the vehicle 10 has started moving and whether the launch clutch WSC has been switched to the engaged state, that is, whether the launch control has been terminated. If the judgment in S70 is negative, the process returns to S50. If the judgment in S70 is affirmative, this routine is terminated.

[0048] Figure 4 is a diagram showing an example of a time chart when the control operation shown in the flowchart of Figure 3 is performed, illustrating the control that changes the settings during the launch standby transient depending on the temperature before the launch control starts. In Figure 4, time t1b indicates the time when launch control starts. Time t1b-t2b indicates the launch standby transient. Time t2b indicates the time when the brake is released and launch begins. If the launch clutch temperature THwsc and oil temperature THoil are low before the launch control starts (see solid line and dashed line), the engine speed Ne and launch clutch torque Twsc during the launch standby transient are set to, for example, a predetermined optimal value A. The operation when the launch clutch temperature THwsc is low before the launch control starts is the same as the operation during launch control shown in Figure 2. On the other hand, if the starting clutch temperature THwsc is high before the start of launch control (see dashed line), the engine speed Ne and starting clutch torque Twsc during the launch standby transient are set to a predetermined appropriate value B, which is smaller than, for example, the optimal value A. The same applies if the oil temperature THoil is high. Either the engine speed Ne or the starting clutch torque Twsc may be set to the appropriate value B. Since the engine speed Ne is more controllable by the electric motor MG, reducing the engine speed Ne may be the first option. However, if the engine speed Ne must be reduced to a level where the supercharging response etc. deteriorates significantly, reducing the starting clutch torque Twsc may also be an option. When the vehicle 10 moves from the launch standby state to the acceleration state, the starting clutch WSC is switched to the engaged state, and control of the engine speed Ne is no longer necessary, the launch control is terminated. In the case of controlling the starting clutch torque Twsc, once vehicle 10 enters an accelerating state, the starting clutch torque Twsc is increased, so the control to reduce the starting clutch torque Twsc is terminated.

[0049] Figure 5 is a diagram showing an example of a time chart when the control operation shown in the flowchart of Figure 3 is performed, and it illustrates the control that changes the initial settings depending on the temperature during the launch standby transient during launch control. In Figure 5, time t1c indicates the time when launch control is started. Time t1c-t4c indicates the launch standby transient. Time t4c indicates the time when the brake is released and launching begins. When the launch clutch temperature THwsc and oil temperature THoil are low before the start of launch control (see solid line and dashed line), the operation is the same as the operation when the temperature is low as shown in Figure 4 until time t3c during the launch standby transient. When the launch standby time TMsd becomes longer, the engine speed Ne and launch clutch torque Twsc during the launch standby transient are changed to an appropriate value one step lower than the initial value (optimal value A) at the start of launch standby (see time t3c). The same applies when the launch clutch temperature THwsc becomes high. On the other hand, when the starting clutch temperature THwsc is high before launch control is initiated (see dashed line), the operation is the same as when the temperature is high, as shown in Figure 4, until point t2c during the launch standby transient. The same applies when the oil temperature THoil is high. Furthermore, when the launch standby time TMsd becomes longer, the engine speed Ne and the starting clutch torque Twsc during the launch standby transient are changed to an appropriate value one step lower than the initial value at the start of launch standby (appropriate value B) (see point t2c). The same applies when the starting clutch temperature THwsc is high. When the temperature is high, the initial value at the start of launch standby (appropriate value B) is set close to the limit in terms of heat generation requirements, and as the launch standby time TMsd becomes longer, the need to lower it to an appropriate value one step smaller than the initial value is higher than when the temperature is low. For example, considering a sports vehicle, the frequency of launch control activation in high temperature situations is not infrequent, and control to lower it to an appropriate value one step smaller is effective. The engine speed Ne and the starting clutch torque Twsc may be changed to an appropriate value one step lower than the other. In this case, the guideline for lowering the engine speed Ne and the starting clutch torque Twsc is to set them to values ​​that cause the starting clutch temperature THwsc to saturated at its current value.This way, even if the starting waiting time TMsd becomes longer afterward, there is no need to further reduce the engine speed Ne or the starting clutch torque Twsc. Also, the threshold D is set to be shorter when the starting clutch temperature THwsc is high than when it is low.

[0050] As described above, according to this embodiment, if at least one of the oil temperature THoil and the starting clutch temperature THwsc is high up to the start of launch control, at least one of the engine speed Ne and the starting clutch torque Twsc during the launch standby transient is set to a lower value compared to when it is low. This makes it easier to suppress the heat generation of the starting clutch WSC when at least one of the oil temperature THoil and the starting clutch temperature THwsc is high, thus avoiding a situation where launch control can only be performed when the starting clutch temperature THwsc is low. Therefore, it is possible to achieve both hardware protection and driver convenience during launch control.

[0051] Furthermore, according to this embodiment, if the launch waiting time TMsd is greater than or equal to threshold D, at least one of the engine rotation speed Ne and launch clutch torque Twsc, which are set at the start of the launch waiting period, is changed to a value lower by a predetermined value F. This makes it possible to improve launch responsiveness without discontinuing launch control, even if there is variation in the driver's operation.

[0052] Furthermore, according to this embodiment, the threshold D is set to a shorter time when the starting clutch temperature THwsc is high compared to when it is low. This suppresses or avoids the rapid rise in the starting clutch temperature THwsc, which is prone to degrading the durability of the starting clutch WSC.

[0053] Furthermore, according to this embodiment, if the launch clutch temperature THwsc is above a threshold E during the launch standby transient, at least one of the engine speed Ne and launch clutch torque Twsc, which were set at the start of the launch standby, is changed to a value lower by a predetermined value F. This makes it possible to improve launch responsiveness without discontinuing launch control, even if there is variation in the driver's operation.

[0054] Furthermore, according to this embodiment, a value lower than a predetermined value F is a predetermined value at which the cooling performance of the launch clutch WSC by oil FLD balances with the amount of heat generated in the launch clutch WSC, causing the rise in the launch clutch temperature THwsc to stagnate. As a result, even if the launch waiting time TMsd becomes longer, it is not necessary to further reduce the engine rotation speed Ne or the launch clutch torque Twsc, thus achieving both drivability and durability. In addition, it becomes easier to predict the heat generated by the launch clutch WSC. Consequently, fluctuations in engine rotation speed Ne are reduced, and drivability is improved. Moreover, it is possible to control the launch clutch WSC at its performance limit while avoiding or suppressing the rise in the launch clutch temperature THwsc. This protects the hardware, prevents or suppresses the deterioration of drivability caused by discontinuing launch control, and allows the vehicle 10 to perform at its maximum potential.

[0055] Although embodiments of the present invention have been described in detail above with reference to the drawings, the present invention is also applicable to other embodiments.

[0056] For example, in the above embodiment, the automatic transmission 22 is not limited to a stepped automatic transmission, but may be, for example, a belt-type continuously variable transmission. Alternatively, the engine 12 is not limited to an internal combustion engine with a supercharger, but may be, for example, a known internal combustion engine without a supercharger. In this case, during the launch control's standby transient, the engine rotation speed Ne is increased to make it easier to produce, for example, a large engine torque Te. The present invention can be applied to any hybrid vehicle equipped with a power source including the engine 12 and electric motor MG, and a launch clutch WSC. Therefore, for example, it is not necessary to have an automatic transmission 22. If an automatic transmission 22 is provided, the launch clutch WSC may constitute a part of the automatic transmission 22.

[0057] It should be noted that the above-described embodiment is merely one example, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art. [Explanation of symbols]

[0058] 10: Vehicle (Hybrid Vehicle) 12: Engine 14: Drive Wheels 90: Electronic Control Unit (Control Unit) 96: Launch Control Unit WSC: Launch Clutch (Clutch) FLD: Oil (Cooling Oil) MG: Electric Motor SP: Power Source

Claims

1. A control device for a hybrid vehicle comprising a power source including an engine and an electric motor, and a clutch provided in the power transmission path between the power source and the drive wheels, The system includes a starting control unit that performs starting control by, during the starting standby transient when the brakes are applied and the accelerator is pressed, pre-increasing the engine's rotational speed and torque to values ​​prepared for starting after the brakes are released, generating regenerative torque from the electric motor and torque capacity of the clutch to maintain the clutch in a slip state so as to handle the engine's torque, and increasing the engine's torque while transitioning the clutch from a slip state to an engaged state during the starting transient after the brakes are released. A control device for a hybrid vehicle, characterized in that the starting control unit sets at least one of the engine rotational speed and the torque capacity of the clutch to a lower value during the starting standby transient compared to when at least one of the temperature of the clutch cooling oil and the temperature of the clutch itself is high up to the start of the starting control.

2. The control device for a hybrid vehicle according to claim 1, characterized in that, if the time during the transient period of the standby period of the standby period is greater than or equal to a predetermined threshold, the starting control unit changes at least one of the values ​​of the rotational speed of the engine and the torque capacity of the clutch, which were set at the start of the standby period of the standby period, to a value lower by a predetermined amount.

3. The control device for a hybrid vehicle according to claim 2, characterized in that the predetermined threshold is set to a shorter time when the temperature of the clutch itself is high compared to when it is low.

4. The control device for a hybrid vehicle according to claim 1, characterized in that, if the temperature of the clutch itself is above a predetermined threshold during the starting standby transient, the starting control unit changes at least one of the values ​​of the engine rotation speed and the torque capacity of the clutch, which were set at the start of the starting standby, to a predetermined value lower.

5. The control device for a hybrid vehicle according to any one of claims 2 to 4, characterized in that the value lower by the predetermined value is a predetermined value at which the cooling performance of the clutch by the cooling oil and the amount of heat generated in the clutch are balanced, and the rise in the temperature of the clutch itself stagnates.

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