JP2022164093A - Control apparatus for hybrid vehicle - Google Patents

Abstract

To provide a control apparatus capable of suppressing an excessive decrease in battery power due to torque assist by a motor during travel in a hybrid vehicle with an engine and a motor as power sources.SOLUTION: In calculating a MG torque Tm of a motor MG during travel in an HV travel mode, an upper limit value Trlim is calculated by adding a maximum torque Tmmx of the motor MG to an environmental correction maximum torque Temaxmod of an engine 12 which takes an air density ρ taken into consideration. When a demanded drive torque Trdem is higher than the upper limit value Trlim, a demanded drive torque Trdem2 used for calculating the MG torque Tm is limited to the upper limit value Trlim, and therefore an increase in the MG torque Tm of the motor MG is limited. This results in suppressing an excessive decrease in a charge state value SOC of a battery 54 due to an increase in the MG torque Tm, thus suppressing decrease in time or frequency of available assistance with the motor MG.SELECTED DRAWING: Figure 1

Description

The present invention relates to a control device for a hybrid vehicle that uses an engine and an electric motor as driving force sources.

A hybrid vehicle that uses an engine and an electric motor as driving force sources is well known. For example, a hybrid vehicle described in Patent Document 1 is one of them. Japanese Patent Laid-Open No. 2002-200001 describes that when the engine output is insufficient while traveling on high ground, the shortage is compensated for by the torque assist of the electric motor.

JP 2015-182570 A

By the way, in the technique described in Patent Document 1, the output torque of the electric motor increases because the electric motor compensates for the insufficient output of the engine. As a result, the rate of decrease of the battery charge becomes faster, and the problem arises that the time and frequency in which the electric motor can assist is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and its object is to provide a hybrid vehicle in which an engine and an electric motor are used as driving force sources, in order to prevent an excessive battery from being overcharged by torque assist of the electric motor while the vehicle is running. An object of the present invention is to provide a control device capable of suppressing a decrease in the amount of charge.

The gist of the first invention is that (a) it is applied to a hybrid vehicle having an engine and an electric motor as driving force sources, and during running in a hybrid running mode in which the vehicle is driven by the power output from the engine and the electric motor; and calculating the output torque of the electric motor based on the required drive torque of the driver and the engine torque of the engine, wherein: (b) air density is taken into account during running in the hybrid running mode When calculating an upper limit value obtained by adding the maximum torque of the electric motor to the maximum torque of the engine calculated by and a controller for limiting the value of the required driving torque used for the above to the upper limit value.

According to the first invention, when calculating the output torque of the electric motor while traveling in the hybrid traveling mode, the upper limit value is calculated by adding the maximum torque of the electric motor to the maximum torque of the engine taking air density into consideration, and the required drive torque is the upper limit. If it is larger than the value, the value of the required drive torque is limited to the upper limit value, so the increase in the output torque of the electric motor is limited. As a result, an excessive decrease in the amount of charge in the battery due to an increase in the output torque of the electric motor is suppressed, thereby suppressing a reduction in the time and frequency in which assistance can be provided by the electric motor. In addition, since the required drive torque at the initial stage of acceleration does not change regardless of the air density, it is possible to obtain the acceleration responsiveness desired by the driver.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram for explaining a schematic configuration of a vehicle to which the present invention is applied, and is a diagram for explaining control functions and main parts of a control system for various controls in the vehicle; 4 is a relationship map used when determining environmental correction factors; FIG. 4 is a diagram showing the relationship between the environment-considered maximum torque and the upper limit value; 4 is a time chart showing the output state of each torque during vehicle acceleration; 4 is a flowchart for explaining a main part of the control operation of the electronic control unit, that is, the control operation for obtaining the acceleration responsiveness desired by the driver while suppressing an increase in the rate of decrease of the state of charge value of the battery during HV running; .

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following examples, the drawings are appropriately simplified or modified, and the dimensional ratios, shapes, etc. of each part are not necessarily drawn accurately.

FIG. 1 is a diagram for explaining a schematic configuration of a vehicle 10 to which the present invention is applied, and is a diagram for explaining control functions and main parts of a control system for various controls in the vehicle 10. As shown in FIG. In FIG. 1, a vehicle 10 is a hybrid vehicle including an engine 12 and an electric motor MG, which are driving force sources for running. The vehicle 10 also includes drive wheels 14 and a power transmission device 16 provided in a power transmission path between the engine 12 and the drive wheels 14 .

The engine 12 is a known internal combustion engine such as a gasoline engine or a diesel 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, which will be described later, to control the engine 12. The engine torque Te, which is the output torque of the engine 12, is controlled by the engine 12. is controlled.

The electric motor MG is a so-called motor-generator, which is a rotary electric machine having a function as a motor that generates mechanical power from electric power and a function as a generator that generates power from mechanical power. Electric motor MG is connected to a battery 54 provided in vehicle 10 via an inverter 52 provided in vehicle 10 . In the electric motor MG, the MG torque Tm, which is the output torque of the electric motor MG, is controlled by controlling the inverter 52 by the electronic control unit 90, which will be described later. For example, when the rotation direction of the electric motor MG is the same rotation direction as the engine 12 is running, the MG torque Tm is a power running torque when the positive torque is on the acceleration side, and is a regenerative torque when the negative torque is on the deceleration side. be. Specifically, the electric motor MG generates power for running from electric power supplied from the battery 54 via the inverter 52 instead of the engine 12 or in addition to the engine 12 . Further, the electric motor MG generates power using the power of the engine 12 and the driven power input from the drive wheel 14 side. Electric power generated by electric power generation by electric motor MG is stored in battery 54 via inverter 52 . The battery 54 is a power storage device that transfers electric power to and from the electric motor MG. Electric power is also synonymous with electrical energy when not specifically distinguished. The power is also synonymous with torque and force unless otherwise specified.

The power transmission device 16 includes a K0 clutch 20, a torque converter 22, an automatic transmission 24, etc. in a case 18, which is a non-rotating member attached to the vehicle body. K0 clutch 20 is a clutch provided between engine 12 and electric motor MG in a power transmission path between engine 12 and driving wheels 14 . Torque converter 22 is connected to engine 12 via K0 clutch 20 .

Automatic transmission 24 is connected to torque converter 22 and is interposed in a power transmission path between torque converter 22 and drive wheels 14 . Torque converter 22 and automatic transmission 24 each form part of a power transmission path between engine 12 and drive wheels 14 . The power transmission device 16 also includes a propeller shaft 28 connected to a transmission output shaft 26 which is an output rotating member of an automatic transmission 24, a differential gear 30 connected to the propeller shaft 28, and a differential gear 30 connected to the differential gear 30. A pair of drive shafts 32 and the like are provided. The power transmission device 16 also includes an engine connection shaft 34 that connects the engine 12 and the K0 clutch 20, an electric motor connection shaft 36 that connects the K0 clutch 20 and the torque converter 22, and the like.

The electric motor MG is connected to the electric motor connecting shaft 36 within the case 18 so as to be able to transmit power. The electric motor MG is coupled to a power transmission path between the engine 12 and the driving wheels 14, particularly a power transmission path between the K0 clutch 20 and the torque converter 22 so as to be able to transmit power. That is, the electric motor MG is connected to the torque converter 22 and the automatic transmission 24 without the K0 clutch 20 so that power can be transmitted. From another point of view, the torque converter 22 and the automatic transmission 24 each form part of a power transmission path between the electric motor MG and the drive wheels 14 . Torque converter 22 and automatic transmission 24 each transmit the driving force from each of the driving force sources of engine 12 and electric motor MG to drive wheels 14 .

The torque converter 22 includes a pump impeller 22 a connected to an electric motor connecting shaft 36 and a turbine impeller 22 b connected to a transmission input shaft 38 which is an input rotating member of the automatic transmission 24 . The pump impeller 22a is connected to the engine 12 via the K0 clutch 20 and directly connected to the electric motor MG. Pump impeller 22 a is an input member of torque converter 22 , and turbine impeller 22 b is an output member of torque converter 22 . The electric motor connecting shaft 36 is also an input rotating member of the torque converter 22 . The transmission input shaft 38 is also an output rotating member of the torque converter 22 integrally formed with a turbine shaft rotationally driven by the turbine impeller 22b. Torque converter 22 is a hydrodynamic transmission device that transmits driving force from each of the driving force sources (engine 12, electric motor MG) to transmission input shaft 38 via fluid. The torque converter 22 includes an LU clutch 40 that connects the pump impeller 22a and the turbine impeller 22b. The LU clutch 40 is a direct coupling clutch that connects the input and output rotating members of the torque converter 22, that is, a known lockup clutch.

The LU clutch 40 is controlled by changing the LU clutch torque Tlu, which is the torque capacity of the LU clutch 40, by the regulated LU hydraulic pressure PRlu supplied from the hydraulic control circuit 56 provided in the vehicle 10. state can be switched. The control state of the LU clutch 40 includes a completely released state in which the LU clutch 40 is released, a slip state in which the LU clutch 40 is engaged with slippage, and a state in which the LU clutch 40 is engaged. There is a state, fully engaged.

The automatic transmission 24 is a known planetary gear type automatic transmission including, for example, one or a plurality of sets of planetary gears (not shown) and a plurality of engagement devices CB. The engagement device CB is a hydraulic friction engagement device configured by, for example, a multi-plate or single-plate clutch or brake that is pressed by a hydraulic actuator, or a band brake that is tightened by a hydraulic actuator. Each of the engagement devices CB changes its CB torque Tcb, which is its torque capacity, by the regulated CB hydraulic pressure PRcb supplied from the hydraulic control circuit 56, thereby changing the control state such as the engaged state and the disengaged state. can be switched.

In the automatic transmission 24, the gear ratio (also referred to as gear ratio) γat (=AT input rotation speed Ni/AT output rotation speed No) is established by engaging any one of the engagement devices CB. is a stepped transmission in which one of a plurality of gear stages (also referred to as gear stages) is formed. In the automatic transmission 24, an electronic control unit 90, which will be described later, switches between gear stages according to the driver's accelerator operation, vehicle speed V, etc. In other words, a plurality of gear stages are selectively formed. be. The AT input rotation speed Ni is the rotation speed of the transmission input shaft 38 and the input rotation speed of the automatic transmission 24 . The AT input rotation speed Ni is also the rotation speed of the output rotation member of the torque converter 22 and has the same value as the turbine rotation speed Nt, which is the output rotation speed of the torque converter 22 . The AT input rotation speed Ni can be represented by the turbine rotation speed Nt. The AT output rotation speed No is the rotation speed of the transmission output shaft 26 and the output rotation speed of the automatic transmission 24 .

The K0 clutch 20 is a wet or dry friction engagement device composed of a multi-plate or single-plate clutch pressed by a hydraulic actuator (not shown). The K0 clutch 20 is switched between control states such as an engaged state and a disengaged state by controlling the operating state of a hydraulic actuator by an electronic control unit 90, which will be described later. In the K0 clutch 20, when the K0 hydraulic pressure PRk0 regulated from the hydraulic control circuit 56 is supplied to the hydraulic actuator, the K0 torque Tk0, which is the torque capacity of the K0 clutch 20, is changed, thereby changing the control state of the K0 clutch 20. can be switched.

In the engaged state of the K0 clutch 20, the pump impeller 22a and the engine 12 are integrally rotated via the engine connecting shaft . That is, the K0 clutch 20 couples the engine 12 and the drive wheels 14 so as to be able to transmit power when engaged. On the other hand, in the released state of the K0 clutch 20, power transmission between the engine 12 and the pump impeller 22a is interrupted. That is, the K0 clutch 20 disconnects the engine 12 and the drive wheels 14 by being released. Since the electric motor MG is connected to the pump impeller 22a, the K0 clutch 20 is provided in the power transmission path between the engine 12 and the electric motor MG to connect and disconnect the power transmission path, that is, the engine 12 and the electric motor. It functions as a clutch that connects and disconnects the MG. That is, the K0 clutch 20 is a connecting/disconnecting clutch that connects the engine 12 and the electric motor MG when engaged, and disconnects the connection between the engine 12 and the electric motor MG when released.

In the power transmission device 16, the power output from the engine 12 when the K0 clutch 20 is engaged is transmitted from the engine connection shaft 34 to the K0 clutch 20, the electric motor connection shaft 36, the torque converter 22, the automatic transmission 24, The power is transmitted to the drive wheels 14 through the propeller shaft 28, the differential gear 30, the drive shaft 32, and the like. Further, regardless of the control state of the K0 clutch 20, the power output from the electric motor MG is transmitted from the electric motor connecting shaft 36 to the torque converter 22, the automatic transmission 24, the propeller shaft 28, the differential gear 30, the drive shaft 32, and the like. The power is transmitted to the driving wheels 14 through successively.

The vehicle 10 includes a mechanical oil pump MOP 58, an electric oil pump EOP 60, a pump motor 62, and the like. The MOP 58 is connected to the pump impeller 22a, and is driven to rotate by a driving force source (engine 12, electric motor MG) to discharge hydraulic oil OIL used in the power transmission device 16. As shown in FIG. The pump motor 62 is a motor dedicated to the EOP 60 for driving the EOP 60 to rotate. The EOP 60 is rotationally driven by the pump motor 62 to discharge hydraulic oil OIL. Hydraulic oil OIL discharged from the MOP 58 and the EOP 60 is supplied to the hydraulic control circuit 56 . The hydraulic control circuit 56 supplies the CB hydraulic pressure PRcb, the K0 hydraulic pressure PRk0, the LU hydraulic pressure PRlu, etc., which are adjusted based on the hydraulic oil OIL discharged from at least one of the MOP 58 and the EOP 60 .

The vehicle 10 further includes an electronic control unit 90 including control units related to travel control of the vehicle 10 and the like. The electronic control unit 90 includes, for example, a so-called microcomputer having a CPU, a RAM, a ROM, and an input/output interface. Various controls of the vehicle 10 are executed by performing signal processing. The electronic control unit 90 includes computers for engine control, electric motor control, hydraulic control, etc., as required.

The electronic control unit 90 includes various sensors provided in the vehicle 10 (for example, the engine rotation speed sensor 70, the turbine rotation speed sensor 72, the output rotation speed sensor 74, the MG rotation speed sensor 76, the accelerator opening sensor 78, the throttle valve opening sensor 80, brake switch 82, battery sensor 84, oil temperature sensor 86, atmospheric pressure sensor 88, outside air temperature sensor 89). Turbine rotation speed Nt which is equivalent to AT input rotation speed Ni, AT output rotation speed No corresponding to vehicle speed V, MG rotation speed Nm which is the rotation speed of electric motor MG, and driver's acceleration operation magnitude The accelerator opening θacc, which is the amount of accelerator operation, the throttle valve opening θth, which is the opening of the electronic throttle valve, and the brake-on signal Bon, which is a signal indicating that the brake pedal for operating the wheel brake is being operated by the driver. , the battery temperature THbat of the battery 54, the battery charging/discharging current Ibat, the battery voltage Vbat, the working oil temperature THoil which is the temperature of the working oil OIL in the hydraulic control circuit 56, the atmospheric pressure Pair, the outside air temperature Tair, etc.) are supplied, respectively. be.

From the electronic control device 90, various command signals (for example, an engine signal for controlling the engine 12) are sent to each device (for example, the engine control device 50, the inverter 52, the hydraulic control circuit 56, the pump motor 62, etc.) provided in the vehicle 10. Control command signal Se, MG control command signal Sm for controlling electric motor MG, CB hydraulic control command signal Scb for controlling engagement device CB, K0 hydraulic control command signals Sko and LU for controlling K0 clutch 20 LU oil pressure control command signal Slu for controlling the clutch 40, EOP control command signal Seop for controlling the EOP 60, etc.) are respectively output.

The electronic control unit 90 includes hybrid control means, a hybrid control section 92 , clutch control means, a clutch control section 94 , and shift control means, a shift control section 96 , in order to implement various controls in the vehicle 10 .

The hybrid control unit 92 functions as engine control means, that is, an engine control unit 92a that controls the operation of the engine 12, and functions as an electric motor control unit, that is, an electric motor control unit 92b that controls the operation of the electric motor MG via the inverter 52. , and executes hybrid drive control and the like by the engine 12 and the electric motor MG by their control functions.

The hybrid control unit 92 calculates the required drive amount for the vehicle 10 by the driver by applying the accelerator opening θacc and the vehicle speed V to the required drive amount map, for example. The required drive amount map is a relation that is experimentally or design-determined in advance and stored, that is, a predetermined relation. The required driving amount is, for example, the required driving torque Trdem in the driving wheels 14 . The required driving torque Trdem [Nm] is, in other words, the required driving power Prdem [W] at the vehicle speed V at that time. As the required driving amount, the required driving force Frdem [N] at the driving wheels 14, the required AT output torque at the transmission output shaft 26, and the like can be used. In calculating the required drive amount, the AT output rotational speed No may be used in place of the vehicle speed V. FIG. In other words, the required drive torque Trdem can be viewed as the torque transmitted to the electric motor connection shaft 36, that is, the total torque of the engine torque Te and the MG torque Tm of the electric motor MG, which is transmitted to the electric motor connection shaft 36. can also For convenience, the required drive torque Trdem will be described below as the torque transmitted to the electric motor connecting shaft 36 .

The hybrid control unit 92 considers the transmission loss, the auxiliary load, the gear ratio γat of the automatic transmission 24, the chargeable power Win and the dischargeable power Wout of the battery 54, and the like so as to realize the required drive power Prdem. It outputs an engine control command signal Se for controlling the engine 12 and an MG control command signal Sm for controlling the electric motor MG. The engine control command signal Se is, for example, a command value of the engine power Pe, which is the power of the engine 12 that outputs the engine torque Te at the engine rotation speed Ne at that time. The MG control command signal Sm is, for example, a command value for the power consumption Wm of the electric motor MG that outputs the MG torque Tm at the MG rotational speed Nm at that time.

The chargeable power Win of the battery 54 is the maximum power that can be input that defines the limit of 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 that defines the limit of the output power of the battery 54 and indicates the output limit of the battery 54 . The chargeable power Win and the dischargeable power Wout of the battery 54 are calculated by the electronic control unit 90 based on the battery temperature THbat and the state of charge value SOC [%] of the battery 54, for example. The state-of-charge value SOC of the battery 54 is a value indicating the state of charge (amount of charge, remaining charge) of the battery 54, and is calculated by the electronic control unit 90 based on, for example, the battery charge/discharge current Ibat and the battery voltage Vbat. .

The hybrid control unit 92 sets the driving mode to the motor driving (=EV driving) mode when the required drive torque Trdem can be covered only by the output of the electric motor MG. In the EV running mode, the hybrid control unit 92 performs EV running in which the K0 clutch 20 is released and only the electric motor MG is used as the driving force source. On the other hand, the hybrid control unit 92 sets the driving mode to the engine driving mode, that is, the hybrid driving (hereinafter referred to as HV driving) mode when the required drive torque Trdem cannot be met without using at least the output of the engine 12 . In a hybrid running mode (hereinafter referred to as HV running mode), the hybrid control unit 92 performs engine running, ie, HV running, in which the K0 clutch 20 is engaged and the engine 12 and the electric motor MG are used as driving force sources. On the other hand, even when the required drive torque Trdem can be covered only by the output of the electric motor MG, the hybrid control unit 92 controls the state of charge value SOC of the battery 54 to be less than the predetermined engine start threshold value or the engine 12 or the like. When it is necessary to warm up the engine, the HV running mode is established. The engine start threshold is a predetermined threshold for determining the state of charge value SOC at which it is necessary to forcibly start the engine 12 and charge the battery 54 . In this manner, the hybrid control unit 92 automatically stops the engine 12 during HV running, restarts the engine 12 after stopping the engine, or restarts the engine 12 during EV running based on the required drive torque Trdem. EV running mode and HV running mode are appropriately switched by starting the vehicle.

The clutch control unit 94 controls the K0 clutch 20 according to the running mode during running. For example, when switching to the HV running mode is determined during EV running, the clutch control unit 94 performs engagement control of the K0 clutch 20 so as to execute start control of the engine 12 . For example, when it is determined that there is a request to start the engine 12 based on the running state, the clutch control unit 94 applies torque necessary for cranking the engine 12, which is torque for increasing the engine rotation speed Ne, to the engine 12 side. A K0 hydraulic control command signal Sko for controlling the released K0 clutch 20 toward the engaged state is output to the hydraulic control circuit 56 so as to obtain the K0 torque Tk0 for transmission to the hydraulic control circuit 56 .

The shift control unit 96 performs shift determination for the automatic transmission 24 using, for example, a shift map having a predetermined relationship, and outputs a CB hydraulic pressure control command signal for executing shift control for the automatic transmission 24 as necessary. Scb is output to the hydraulic control circuit 56 . The shift map is a predetermined relationship having a shift line for judging the shift of the automatic transmission 24 on two-dimensional coordinates having, for example, the vehicle speed V and the accelerator opening .theta.acc as variables. In the shift map, the AT output rotation speed No may be used instead of the vehicle speed V, and the required driving torque Trdem, the required driving force Frdem, the throttle valve opening θth, etc. may be used instead of the accelerator opening θacc. You can use it.

By the way, when the atmospheric pressure Pair is low or the outside air temperature Tair is high, the air density ρ decreases, so the engine torque Te output from the engine 12 relatively decreases compared to when the normal temperature and pressure. Note that the normal temperature and normal pressure means a state in which the engine torque Te due to the atmospheric pressure Pair and the outside air temperature Tair hardly decreases, and the rated maximum torque Temax of the engine 12 is It means when it is ready to output. In a driving state that satisfies at least one of a low atmospheric pressure Pair and a high outside air temperature Tair, the hybrid control unit 92 compensates for the decrease in the engine torque Te of the engine 12 during driving in the HV driving mode by reducing the MG torque of the electric motor MG. Since control is performed so as to compensate for the torque Tm, the MG torque Tm of the electric motor MG increases compared to that at normal temperature and normal pressure. As a result, the rate of decrease of the state of charge value SOC of the battery 54 becomes faster than at normal temperature and normal pressure, which causes a problem that the time and frequency of torque assist by the electric motor MG decrease.

On the other hand, the hybrid control unit 92 controls the air density ρ is low, the driver's required drive torque Trdem is limited to suppress an increase in the MG torque Tm of the electric motor MG. The hybrid control unit 92 functionally includes an upper limit value calculation unit 92c and an MG torque calculation unit 92d having a control function of suppressing an increase in the MG torque Tm of the electric motor MG during traveling in the HV traveling mode. The upper limit value calculator 92c and the MG torque calculator 92d correspond to the controller of the present invention.

The upper limit value calculator 92c calculates the maximum torque Temaxmod (hereinafter referred to as the environment correction maximum Calculate the torque Temaxmod). In equation (1), "Temax" corresponds to the maximum torque of the engine 12 output at normal temperature and normal pressure. "Tegnd" is a loss torque that is lost until the torque due to combustion generated in the combustion chamber of the engine 12 is transmitted to the crankshaft, and is a predetermined known value. Therefore, (Temax+Tegnd) indicates the maximum value of torque generated in the combustion chamber of the engine 12. Also, "K" in equation (1) represents an environment correction coefficient that takes into consideration the environment during running (specifically, the air density ρ). The environmental correction coefficient K is a coefficient for correcting the maximum torque Temax of the engine 12 output at normal temperature and normal pressure according to the air density ρ, and the atmospheric pressure Pair and the outside temperature Tair related to the air density ρ. variable. It should be noted that the outside air temperature Tair corresponds to the intake air temperature of the engine 12 . Also, the environment correction coefficient K is specified in the range of 0 to 1.0. From equation (1), when the environmental correction coefficient K is the maximum value of 1.0, the environmental correction maximum torque Temaxmod is equal to the maximum torque Temax that can be generated at normal temperature and normal pressure. Further, according to the equation (1), the smaller the environmental correction coefficient K, the smaller the environmental corrected maximum torque Temaxmod. The environment-corrected maximum torque Temaxmod corresponds to the engine maximum torque calculated in consideration of the air density ρ of the present invention.
Temaxmod=(Temax+Tegnd)×K−Tegnd (1)

The environmental correction coefficient K is obtained experimentally or by design in advance, and is defined by a two-dimensional map having variables of the atmospheric pressure Pair and the outside air temperature Tair, as shown in FIG. 2, for example. In FIG. 2, the horizontal axis corresponds to the outside air temperature Tair, and the vertical axis corresponds to the atmospheric pressure Pair. Here, as the atmospheric pressure Pair decreases, the air density ρ decreases. Therefore, as shown in FIG. 2, the environmental correction coefficient K decreases as the atmospheric pressure Pair decreases. Further, the higher the outside air temperature Tair, the lower the air density ρ. Therefore, as shown in FIG. 2, the higher the outside air temperature Tair, the lower the value of the environment correction coefficient K. Incidentally, the environment correction coefficient K in FIG. 2 can be replaced with the air density ρ. The upper limit value calculator 92c obtains the environmental correction coefficient K by applying the current atmospheric pressure Pair and the outside air temperature Tair to a two-dimensional map as shown in FIG. to calculate the environment-corrected maximum torque Temaxmod.

Further, the upper limit value calculation unit 92c adds a predetermined, for example, rated maximum torque that can be output by the electric motor MG to the environment-corrected maximum torque Temaxmod calculated in consideration of the air density ρ during traveling in the HV traveling mode. By adding Tmmx, the upper limit value Trlim of the required driving torque Trdem is calculated. Note that the maximum torque Tmmx of the electric motor MG is not affected by the air density ρ. On the other hand, the maximum torque Tmmx depends on the state of charge value SOC and the temperature of the electric motor MG, for example, when the state of charge value SOC of the battery 54 is less than the specified value or when the temperature of the electric motor MG exceeds the specified value. may be restricted by

FIG. 3 is a diagram showing the relationship between the environment-corrected maximum torque Temaxmod and the upper limit Trlim. In FIG. 3, the horizontal axis corresponds to the accelerator opening θacc[%], and the vertical axis corresponds to each torque T[Nm]. A straight line L shown in FIG. 3 indicates the required drive torque Trdem with respect to the accelerator opening θacc, which is the amount of acceleration required by the driver. As shown in FIG. 3, the required drive torque Trdem increases as the accelerator opening θacc increases. Further, at the maximum accelerator opening θmax in which the accelerator pedal is fully depressed, the required drive torque Trdem is the maximum value Temgtgtmax. This maximum value Temgtgtmax is calculated as the sum (Temax+Tmmx) of the maximum torque Temax of the engine 12 and the maximum torque Tmmx of the electric motor MG. Further, the value X in FIG. 3 is the difference between the maximum value Temgtgtmax and the maximum torque Temax of the engine 12 (=Temgtgtmax−Temax), which is the same value as the maximum torque Tmmx of the electric motor MG.

The environment-corrected maximum torque Temaxmod shown in FIG. 3 is obtained from the above equation (1). As shown in FIG. 3 , the environment-corrected maximum torque Temaxmod is a smaller value than the maximum torque Temax of the engine 12 . A value obtained by adding the maximum torque Tmmx of the electric motor MG, which is the difference (Temgtgtmax-Temax) between the maximum value Temgtgtmax and the maximum torque Temax of the engine 12, to the environment-corrected maximum torque Temaxmod is the upper limit value Trlim of the required driving torque Trdem. Calculated. From equation (1), the smaller the environment correction coefficient K, the smaller the environment correction maximum torque Temaxmod. Therefore, the smaller the environment correction coefficient K, the smaller the upper limit value Trlim. That is, the lower the air density ρ (the lower the atmospheric pressure Pair and the higher the outside air temperature Tair), the smaller the upper limit value Trlim.

The MG torque calculator 92d calculates the MG torque Tm of the electric motor MG based on the required drive torque Trdem and the engine torque Te. The MG torque calculation unit 92d first calculates a required driving torque Trdem (hereinafter referred to as a required driving torque Trdem2 to distinguish from the required driving torque Trdem of the driver) used when calculating the MG torque Tm of the electric motor MG. do. The MG torque calculation unit 92d calculates the required drive torque Trdem2 using the upper limit value Trlim calculated by the upper limit value calculation unit 92c as the upper limit. Specifically, the MG torque calculation unit 92d uses the smaller one of the driver's required driving torque Trdem and the upper limit value Trlim obtained from the accelerator opening θacc and the vehicle speed V to calculate the MG torque Tm of the electric motor MG. Set to the required drive torque Trdem2. That is, when the required drive torque Trdem is greater than the upper limit value Trlim, the MG torque calculator 92d limits the required drive torque Trdem2 used when calculating the MG torque Tm of the electric motor MG to the upper limit value Trlim. Specifically, when the required driving torque Trdem is larger than the upper limit value Trlim, the upper limit value Trlim is set to the required driving torque Trdem2, and the required driving torque Trdem2 is reduced to the upper limit value Trlim. On the other hand, when the required driving torque Trdem is smaller than the upper limit value Trlim, the required driving torque Trdem is set as it is as the required driving torque Trdem2.

After calculating the required drive torque Trdem2, the MG torque calculator 92d calculates the MG torque Tm of the electric motor MG based on the required drive torque Trdem2 and the estimated engine torque Teest of the engine 12 . The MG torque calculator 92d calculates the MG torque Tm of the electric motor MG based on the following formula (2). Teest in equation (2) corresponds to the estimated engine torque that is presumptively calculated in consideration of the accelerator opening θacc, the vehicle speed V, the atmospheric pressure Pair, and the outside air temperature Tair. In equation (2), while the vehicle is running in a low pressure state or a high temperature state, the estimated engine torque Teest is smaller than the engine torque Te estimated at normal temperature and normal pressure. By limiting to the upper limit, the MG torque Tm becomes equal to or less than the torque output at normal temperature and normal pressure.
Tm = Trdem2 - Test (2)

FIG. 4 is a time chart showing torque output states during vehicle acceleration. In FIG. 4, the horizontal axis corresponds to time t [sec], and the vertical axis corresponds to each torque T [Nm]. Each straight line shown in FIG. 4 corresponds to an indicated value. Also, the indication value may be smoothed by appropriately performing smoothing processing. In FIG. 4, the dashed line indicates the engine torque Te that is output at normal temperature and normal pressure. A two-dot chain line indicates the engine torque Telow of the engine 12 output when the air density ρ is low (during high temperature or low pressure). As shown in FIG. 4, the engine torque Telow when the air density ρ is low, indicated by the two-dot chain line, is lower than the engine torque Te indicated by the one-dot chain line. Also, the engine torque Telow decreases as the air density ρ decreases.

The solid line shown in FIG. 4 indicates the required driving torque Trdem of the driver, and the dashed line indicates the required driving torque Trdem2 set when the air density ρ is low. As shown in FIG. 4, when the air density ρ is low, the engine torque Telow is lower than the engine torque Te at normal temperature and pressure. do. Therefore, since the required driving torque Trdem2 does not exceed the upper limit value Trlim, an increase in the MG torque Tm is suppressed according to the equation (2). In addition, since the torque (target value) of the required drive torque Trdem is limited after the time t3, the required drive torque Trdem2 becomes the same value as at the normal temperature and normal pressure in the time t1 to the time t3, which is the rising period of the torque. . Therefore, even when the air density ρ is low, the required drive torque Trdem2 during the torque rise transition period is the same as that at normal temperature and normal pressure, so that the same acceleration responsiveness as that at normal temperature and normal pressure can be obtained. Further, since the required drive torque Trdem is limited to a region exceeding the upper limit value Trlim, it is possible to prevent the required drive torque Trdem from being limited to an unnecessary low torque region.

FIG. 5 shows the essential part of the control operation of the electronic control unit 90, that is, the acceleration responsiveness desired by the driver is obtained while suppressing the increase in the rate of decrease of the state of charge value SOC of the battery 54 during traveling in the HV traveling mode. 4 is a flow chart illustrating the possible control actions; This flowchart is repeatedly executed while the vehicle 10 is running.

First, in step (hereinafter, step is omitted) S10 corresponding to the control function of the hybrid control unit 92, it is determined whether or not an acceleration request is output to the vehicle 10 by depressing the accelerator pedal during running. . If the determination in S10 is negative, this routine is terminated. If the determination in S10 is affirmative, in S20 corresponding to the control function of the upper limit value calculator 92c, the driver's required drive torque Trdem is calculated based on the accelerator opening θacc, the vehicle speed V, and the like. Next, in S30 corresponding to the control function of the upper limit value calculator 92c, the environmental correction coefficient K is obtained based on the atmospheric pressure Pair and the outside air temperature Tair during running, and the environmental correction coefficient K is calculated by the above-described formula (1 ), the environment-corrected maximum torque Temaxmod that can be output from the engine 12 is calculated. At S40 corresponding to the control function of the upper limit calculator 92c, the maximum torque Tmmx of the electric motor MG is added to the environment corrected maximum torque Temaxmod obtained at S30 to calculate the upper limit Trlim. At S50 corresponding to the control function of the MG torque calculator 92d, the smaller value of the required driving torque Trdem obtained at S20 and the upper limit value Trlim obtained at S40 is set as the required driving torque Trdem2. In S60 corresponding to the control function of the MG torque calculation unit 92d, the required driving torque Trdem2 obtained in S50 is applied to the above-described equation (2) to calculate the MG torque Tm (assist torque) of the electric motor MG. be. In S70 corresponding to the control function of the electric motor control section 92b, the electric motor MG is controlled so that the MG torque Tm calculated in S60 is output from the electric motor MG.

In this way, by limiting the required drive torque Trdem2 used when calculating the MG torque Tm of the electric motor MG to the upper limit value Trlim, the MG torque Tm of the electric motor MG is equal to the MG torque Tm that is output at normal temperature and normal pressure. and is suppressed from exceeding the MG torque Tm output at normal temperature and normal pressure. As a result, even when the air density ρ is low, the MG torque Tm is substantially the same as that at normal temperature and normal pressure. The time and frequency in which torque assist can be performed by the MG torque Tm are ensured to be equivalent to those at normal temperature and normal pressure. Further, in the rising transition period of the required drive torque Trdem, the required drive torque Trdem does not change from that at normal temperature and normal pressure, so the same acceleration responsiveness as that at normal temperature and normal pressure is ensured.

As described above, according to this embodiment, when calculating the MG torque Tm of the electric motor MG during traveling in the HV traveling mode, the maximum torque Tmmx of the electric motor MG is added to the environment-corrected maximum torque Temaxmod of the engine 12 considering the air density ρ. is added to calculate the upper limit value Trlim, and when the required drive torque Trdem is larger than the upper limit value Trlim, the required drive torque Trdem2 used for calculating the MG torque Tm is limited to the upper limit value Trlim, so that the electric motor MG limit the increase in MG torque Tm. As a result, an excessive decrease in the state of charge value SOC of the battery 54 due to an increase in the MG torque Tm of the electric motor MG is suppressed, thereby suppressing a decrease in the time and frequency in which assistance can be provided by the electric motor MG. Further, since the required drive torque Trdem2 at the initial stage of acceleration does not change regardless of the air density ρ, it is possible to obtain the acceleration responsiveness desired by the driver.

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

For example, in the above embodiment, the engine 12 and the electric motor MG are configured to be connectable via the K0 clutch 20, and the hybrid type in which the automatic transmission 24 is interposed between the engine 12 and the electric motor MG and the drive wheels 14. However, the present invention is not necessarily limited to the aspect of this embodiment. For example, if the vehicle is a hybrid type vehicle that uses an engine and an electric motor as drive sources, such as a vehicle in which the engine and the electric motor are connected so as to be able to transmit power via a differential mechanism as a power distribution mechanism, the present invention is suitable. can be applied.

Further, in the above-described embodiment, the environmental correction coefficient K was obtained based on the atmospheric pressure Pair and the outside temperature Tair. It doesn't matter if it's what you want.

Further, in the above embodiment, the engine 12 is a naturally aspirated engine without a supercharger, but the present invention is not necessarily limited to this. For example, the present invention can be appropriately applied even to an engine equipped with a supercharger.

It should be noted that what has been described above is just one embodiment, and the present invention can be implemented in aspects with various modifications and improvements based on the knowledge of those skilled in the art.

10: Vehicle (hybrid vehicle)
12: Engine 90: Electronic control device (control device)
92c: upper limit control unit (control unit)
92d: MG torque calculator (controller)
MG: electric motor Te: engine torque Trdem: required driving torque of the driver Trdem2: required driving torque used when calculating the output torque of the electric motor Temaxmod: environment correction maximum torque (maximum engine torque calculated considering air density )
Tmmx: Maximum torque of motor Trlim: Upper limit

Claims (1)

Applied to a hybrid vehicle using an engine and an electric motor as driving force sources, and during driving in a hybrid driving mode in which the driving force is output from the engine and the electric motor, the driving torque required by the driver and the engine torque of the engine. A control device for a hybrid vehicle, which calculates the output torque of the electric motor based on
During running in the hybrid running mode, an upper limit value obtained by adding the maximum torque of the electric motor to the maximum torque of the engine calculated in consideration of the air density is calculated, and the required driving torque is greater than the upper limit value. A control device for a hybrid vehicle, comprising: a control unit that limits the value of the required driving torque used when calculating the output torque of the electric motor to the upper limit value when the required driving torque is larger.

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