Control device for hybrid electric vehicle

Abstract

The invention relates to a control device for a hybrid electric vehicle. The engine is controlled on the basis of a full-open operation line obtained by connecting operation points at which the engine outputs maximum torque in a state in which the accelerator opening degree is maximum, and a non-full-open operation line obtained by connecting operation points at which the exhaust state of the engine is improved compared with the full-open operation line. The hybrid electric vehicle is driven by selecting either the CD mode or the CS mode, and when the CD mode is selected, the use of the full-open operation line is prohibited, and when the CS mode is selected, the use of the full-open operation line is prohibited. The driving force is controlled by setting a required driving force corresponding to a state in which the accelerator opening degree is maximum on the basis of a composite torque obtained by adding up an engine torque determined on the basis of the non-fully-open operation line and a motor torque that can be output in accordance with the allowable discharge power of the battery.

Description

Technical Field

[0001] The present invention relates to a control device for a hybrid electric vehicle equipped with an engine (internal combustion engine) and an electric motor as driving force sources. Background Art

[0002] Japanese Patent Application Laid-Open No. 2020-75534 describes a control device for a hybrid electric vehicle that performs driving control of the vehicle by selecting any one of a plurality of control modes including a charge sustaining (CS) mode for suppressing a decrease in the amount of power stored in a battery and a charge depleting (CD) mode for consuming the power of the battery. The control device for a hybrid electric vehicle described in Japanese Patent Application Laid-Open No. 2020-75534 switches the engine's operating line according to the selected control mode in a manner such that the engine's operating line when the CD mode is selected is located on a side with a lower engine torque than the engine's operating line when the CS mode is selected, when the engine speed is within a range below a predetermined value.

[0003] In addition, Japanese Patent Laid-Open No. 2016-16689 describes a control device for a hybrid electric vehicle that is driven in a hybrid electric vehicle that selects either a CD mode or a CS mode, and that aims to improve fuel economy in a CD mode. The control device for the hybrid electric vehicle described in Japanese Patent Laid-Open No. 2016-16689 selects either a CD mode that consumes the state of charge (SOC) of a battery or a CS mode that maintains the SOC of the battery at a specified level to drive the hybrid electric vehicle. Furthermore, when the CD mode is selected, control is performed in such a manner that the maximum value of the vehicle driving force becomes smaller than when the CS mode is selected. The maximum value of the vehicle driving force when the CD mode is selected is set in such a manner that the torque of the motor does not exceed a limit torque set based on the efficiency of the motor.

[0004] It should be noted that Japanese Patent Application Laid-Open No. 2019-199194 describes a control device for a hybrid electric vehicle for the purpose of obtaining a large driving force even when the output of the electric motor is restricted. The control device for the hybrid electric vehicle described in Japanese Patent Application Laid-Open No. 2019-199194 charges the battery while driving the hybrid electric vehicle when the required driving force relative to the hybrid electric vehicle is greater than the driving force that can be output when the output of the electric generator is maximum and the battery is not charged (maximum driving force without battery charging). In addition, Japanese Patent Application Laid-Open No. 2019-199194 describes a control example for calculating the target engine torque based on the required driving force, the maximum driving force without battery charging, the maximum driving force with battery charging (the driving force that can be output when the battery is charged), and the wide open throttle (WOT) action line. Summary of the invention

[0005] A hybrid electric vehicle (HEV) equipped with an engine and an electric motor (motor generator) as a driving force source drives the electric motor using the power supplied from the battery. The HEV can generate driving force using the output of the electric motor to drive (motor driving or EV driving), and can charge the battery by making the electric motor function as a generator. In particular, the so-called plug-in hybrid electric vehicle (PHEV) that can charge the battery from an external power source is equipped with a battery with a larger capacity than a conventional HEV. Basically, the PHEV performs EV driving until the SOC of the battery becomes lower than a specified level. In such a PHEV, the CD mode and CS mode described in the above-mentioned Japanese Patent Application Laid-Open No. 2020-75534 and Japanese Patent Application Laid-Open No. 2016-16689 are usually set. In a PHEV, either the CD mode or the CS mode is selected according to the SOC of the battery.

[0006] On the other hand, the engine installed as the driving force source of HEV and PHEV is based on, for example, Figure 1The fully open action line (WOT action line) and the fuel economy priority action line set as shown in the figure are controlled. The fully open action line or the fuel economy priority action line is selected according to the size of the required driving force, and the engine torque and engine speed are controlled based on the selected action line. Therefore, when the CD mode is set in the PHEV as described above, for example, when a large driving force is required in the fully open state of the accelerator such that the accelerator pedal is pressed to the maximum, the output of the engine is added to the output of the motor in the CD mode, so that a large driving force corresponding to the required driving force is generated. In such a case, in the previous control, in order to give priority to the fuel economy of the engine over the power, the fully open action line is selected and the engine is controlled in the maximum output state. If the engine is controlled based on the fully open action line, the fuel economy and exhaust emissions (properties and discharge amount of exhaust gas) of the engine will deteriorate compared with the case where the engine is controlled based on the fuel economy priority action line. If the fuel economy priority action line is selected relative to such a large driving requirement when the accelerator is fully open, the driving force obtained will be insufficient, and the power performance of the hybrid electric vehicle will decrease.

[0007] The present invention has been made in view of the above technical problems and has been devised to improve the fuel economy of an engine without causing a decrease in power performance. In addition, an object of the present invention is to provide a control device for a hybrid electric vehicle that can prevent deterioration of exhaust emissions.

[0008] In order to achieve the above-mentioned object, the present invention provides a control device for a hybrid electric vehicle, wherein the hybrid electric vehicle is equipped with an engine and an electric motor as a driving force source for outputting a driving torque for generating a driving force, and has a battery for exchanging electric power with the electric motor, and is capable of selectively setting at least a first control mode in which the electric motor is driven by supplying electric power from the battery and a second control mode in which the electric motor is driven without supplying electric power from the battery, and controls the driving force based on a required driving force set corresponding to a vehicle speed and an accelerator opening.

[0009] The control device includes a controller for controlling the hybrid electric vehicle.

[0010] The controller controls the engine based on at least a fully open operation line obtained by connecting an operation point at which the engine outputs a maximum torque when the accelerator opening is at a maximum and a non-fully open operation line obtained by connecting an operation point at which the exhaust state of the engine is improved compared to the fully open operation line.

[0011] The controller selects either the first control mode or the second control mode to cause the hybrid electric vehicle to travel, and

[0012] When the first control mode is selected, the controller prohibits use of the full-open action line (i.e., prohibits operation of the engine based on the full-open action line), and sets the required driving force corresponding to the state of the maximum accelerator opening based on a composite torque obtained by summing the output torque of the engine determined based on the non-full-open action line and the output torque of the electric motor that can be output according to the discharge allowable power of the battery at that time, thereby controlling the driving force.

[0013] In addition, the controller in the present invention can be configured as follows:

[0014] When the first control mode is selected, determining a predetermined condition that indicates a possibility that the exhaust gas state may deteriorate,

[0015] When it is determined that there is a possibility that the exhaust state may deteriorate, use of the full-open operation line is prohibited, and the required driving force corresponding to the state where the accelerator opening is maximum is set based on the composite torque to control the driving force.

[0016] In addition, the non-fully open operation line in the present invention may include a fuel economy priority operation line obtained by connecting the exhaust state to the fully open operation line and the fuel economy of the engine to an operating point where the exhaust state is improved and the fuel economy of the engine is improved or the fuel economy of the engine is optimal.

[0017] The composite torque in the present invention may include a fuel economy priority torque obtained by summing the output torque of the engine determined based on the fuel economy priority operation line and the output torque of the electric motor that can be output according to the discharge allowable power of the battery.

[0018] In addition, the non-fully open operation line in the present invention may include an intermediate operation line obtained by connecting operating points where the exhaust state is improved and the fuel economy is improved compared to the fully open operation line, and the output torque of the engine is increased compared to the fuel economy priority operation line.

[0019] The composite torque in the present invention may include an intermediate torque obtained by summing the output torque of the engine determined based on the intermediate operation line and the output torque of the electric motor that can be output according to the discharge allowable power of the battery.

[0020] The controller in the present invention can be configured as follows:

[0021] When the first control mode is selected or when it is determined that the exhaust state may deteriorate, use of the full-open operation line is prohibited, and the required driving force corresponding to the maximum accelerator opening state is set based on the intermediate torque to control the driving force.

[0022] Furthermore, the first control mode in the present invention may include a CD mode in which the stored power of the battery is consumed by the electric motor.

[0023] The second control mode in the present invention may include a CS mode for maintaining the storage amount of the battery at a predetermined level or suppressing a decrease in the storage amount of the battery.

[0024] The controller in the present invention can be configured as follows:

[0025] When the CD mode is selected, use of the full-open operation line is prohibited, and the required driving force corresponding to the state in which the accelerator opening is maximum is set based on the composite torque to control the driving force.

[0026] In addition, the controller in the present invention can be configured as follows:

[0027] When the CD mode is selected, determining a predetermined condition that may cause the exhaust gas state to deteriorate,

[0028] When it is determined that there is a possibility that the exhaust state may deteriorate, use of the full-open operation line is prohibited, and the required driving force corresponding to the state where the accelerator opening is maximum is set based on the composite torque to control the driving force.

[0029] In addition, the non-fully open operation line in the present invention may include a fuel economy priority operation line obtained by connecting operation points where the exhaust state is improved and the fuel economy of the engine is improved compared to the fully open operation line.

[0030] The composite torque in the present invention may include a fuel economy priority torque obtained by summing the output torque of the engine determined based on the fuel economy priority operation line and the output torque of the electric motor that can be output according to the discharge allowable power of the battery.

[0031] Furthermore, the non-fully open operation line in the present invention may include an intermediate operation line obtained by connecting operating points where the exhaust state is improved and the fuel economy is improved compared to the fully open operation line and the output torque of the engine is increased compared to the fuel economy priority operation line.

[0032] The composite torque in the present invention may include an intermediate torque obtained by summing the output torque of the engine determined based on the intermediate operation line and the output torque of the electric motor that can be output according to the discharge allowable power of the battery.

[0033] The controller in the present invention can be configured as follows:

[0034] When the CD mode is selected or when it is determined that the exhaust state may deteriorate, use of the full-open operation line is prohibited, and the required driving force corresponding to the maximum accelerator opening state is set based on the intermediate torque to control the driving force.

[0035] The hybrid electric vehicle of the present invention includes an engine and an electric motor as a driving force source. A battery is connected to the electric motor via a power supply device such as a converter or a transformer. Therefore, the electric motor is driven by the electric power supplied from the battery to output torque. In addition, the battery can also be charged with the electricity generated by the electric motor. The engine operates based on a fully open action line that becomes an operating state in which the maximum torque is output corresponding to the maximum or fully open accelerator opening, and a non-fully open action line that becomes an operating state in which the exhaust state of the engine is improved compared to the case of operating on the fully open action line, that is, an operating state in which the exhaust gas discharge amount is reduced and the properties and components of the exhaust gas are improved. In addition, the hybrid electric vehicle of the present invention selectively sets the first control mode or CD mode and the second control mode or CS mode to travel.

[0036] In the hybrid electric vehicle constructed as described above, when the first control mode or CD mode is selected and the vehicle is traveling, in the state where the accelerator opening is the largest, that is, when the driving requirement based on the driver's operation becomes the largest, in order to obtain a large driving force corresponding to the maximum driving requirement, the engine is operated, and the driving force is generated by adding the output torque of the engine. In this case, in the previous control, the engine is operated based on the full-open action line as described above under the concept of responding to the large driving requirement by obtaining the maximum torque of the engine. By adding the maximum torque of the engine to the output torque of the motor in the first control mode or CD mode, a larger driving force (for example, the maximum driving force of the hybrid electric vehicle) can be generated, and good vehicle power performance can be obtained. However, if the engine is operated on the full-open action line, although the maximum torque of the engine can be obtained, on the other hand, compared with the case where the engine is operated on a non-full-open action line that does not output the maximum torque, such as the fuel economy priority action line, the exhaust state of the engine will deteriorate. For example, the exhaust gas discharge increases, and exhaust components such as CO will increase. In addition, the fuel economy of the engine will also deteriorate. In contrast, in the control device of the hybrid electric vehicle of the present invention, when the first control mode or the CD mode is selected, the operation of the engine based on the full-open action line is prohibited. At the same time, the required driving force corresponding to the large driving requirement with the accelerator opening being the maximum (i.e., the target driving force in the driving force control) is set based on, for example, the composite torque obtained by adding the engine torque when the engine is operated with a non-full-open action line such as a fuel economy priority action line, an intermediate action line, and the motor torque that can be output according to the state of the battery at that point in time. Therefore, even in the case of a large driving force with the accelerator opening being the maximum, the use of the full-open action line is avoided to suppress the deterioration of the exhaust state of the engine. In addition, since the maximum torque of the motor that can be output at that point in time is added to the engine torque based on the non-full-open action line, large driving requirements can also be appropriately dealt with. That is, the power performance of the hybrid electric vehicle can be ensured.

[0037] Therefore, the hybrid electric vehicle control device of the present invention can improve the fuel economy of the engine without causing a decrease in the power performance of the hybrid electric vehicle. In addition, the hybrid electric vehicle control device of the present invention can prevent the exhaust emission of the engine from being deteriorated. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Features, advantages and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like numerals represent like elements, and in which:

[0039] Figure 1This is a line diagram showing the image of a wide-open operation line (WOT operation line) and a fuel economy priority operation line used in conventional engine control;

[0040] Figure 2 is a diagram schematically showing an example of a structure and a control system of a hybrid electric vehicle that is a control target in the present invention;

[0041] Figure 3 is a flowchart for explaining an example (basic control example) of control performed by the control device for a hybrid electric vehicle of the present invention;

[0042] Figure 4 is a line diagram showing an image of a required driving force map used in driving force control of a hybrid electric vehicle according to the present invention;

[0043] Figure 5 is a flowchart for explaining another example of control executed by the control device for a hybrid electric vehicle of the present invention (a control example in which control for determining the exhaust state of the engine is added);

[0044] Figure 6 This is a line diagram showing the concept of a full-open operation line, a fuel economy priority operation line, and an intermediate operation line used in the engine control and the driving force control of the hybrid electric vehicle of the present invention. DETAILED DESCRIPTION

[0045] Embodiments of the present invention will be described with reference to the drawings. It should be noted that the embodiments described below are merely examples of the present invention, and do not limit the present invention.

[0046] In the embodiment of the present invention, the vehicle that is the object of control is a hybrid electric vehicle equipped with at least an engine and an electric motor as a driving force source. The electric motor is connected to the battery in a manner that allows power to be transferred. The electric motor is driven by supplying power from the battery, and the torque is output by the electric motor. In addition, the battery can also be charged with electricity generated by the electric motor. Therefore, it is also possible to use a so-called electric generator that has both the function of a prime mover and the function of a generator. Alternatively, it is also possible to have multiple electric motors, including an electric motor that mainly functions as a prime mover and an electric motor that mainly functions as a generator. In the embodiment described later, an example in which two electric motors (a first electric motor 2 and a second electric motor 3) are installed is shown. In Figure 2 Schematic diagram of the structure of a hybrid electric vehicle (hereinafter referred to as a vehicle) Ve that is a control target in the embodiment of the present invention is shown in FIG.

[0047] Figure 2The illustrated vehicle Ve includes an engine (ENG) 1, a first motor (MG) 2, a second motor (MG) 3, a power split device (GEAR) 4, and a battery (BAT) 5. The vehicle Ve also includes a detection unit 6 and a controller (ECU) 7 for executing various controls.

[0048] The engine 1 is an internal combustion engine such as a gasoline engine or a diesel engine that generates power by burning fuel. The engine 1 is configured so that the output adjustment and the operation states such as starting and stopping are electrically controlled. In the case of a gasoline engine, the throttle opening, the fuel supply amount or injection amount, the fuel injection timing, the execution and stopping of ignition, and the ignition timing are electrically controlled.

[0049] The first motor 2 is connected to the engine 1 and the drive wheel 10 described later via the power split mechanism 4 described later in a manner that allows power transmission. In addition, the first motor 2 is electrically connected to the battery 5 described later in a manner that allows power to be transferred. The first motor 2 also has a function as a generator that receives torque output by the engine 1 and is driven to generate power. That is, the first motor 2 is a so-called electric generator having a power generation function, and is composed of, for example, a permanent magnet synchronous motor or an induction motor.

[0050] The second motor 3 is connected to the drive wheel 10 via the differential gear 8 and the drive shaft 9, for example, in a manner that enables power transmission. In addition, the second motor 3 is electrically connected to the battery 5 described later in a manner that enables power transfer. The second motor 3 has at least a function as a motor that is driven by receiving power supply to output torque. The second motor 3 also has a function as a generator that is driven by receiving torque from the outside to generate electricity. That is, the second motor 3 is a so-called electric generator with a power generation function, similar to the above-mentioned first motor 2, and is composed of, for example, a permanent magnet synchronous motor or an induction motor.

[0051] The power split mechanism 4 is connected to the engine 1 and the first motor 2 in a power-transmittable manner, and transmits the output torque of the engine 1 (engine torque) and the output torque of the first motor 2 (motor torque) to the drive wheel 10 side. Figure 2 In the example shown, the power split mechanism 4 is disposed adjacent to the first electric motor 2 on the same axis as the first electric motor 2 and the engine 1. The power split mechanism 4 is configured by utilizing the differential rotation function of a planetary gear mechanism (not shown), for example.

[0052] The battery 5 is a secondary battery such as a lithium-ion battery or a nickel-metal hydride battery. The battery 5 is electrically connected to the first motor 2 and the second motor 3 via an inverter (INV) 11 or the like so as to enable power transfer. Therefore, the battery 5 is charged and stored with the power generated by the first motor 2. In addition, the battery 5 supplies power to the second motor 3, and the second motor 3 generates a driving torque.

[0053] Moreover, in Figure 2 In the example shown, the battery 5 is configured to be chargeable by power supplied from an external power source 12 of the vehicle Ve. In addition, as described above, the vehicle Ve generates power using the engine 1 and the first motor 2, and is driven by the output of the second motor 3 described later. Figure 2 In the example shown, the vehicle Ve becomes a so-called split-flow "plug-in hybrid electric vehicle (PHEV)" equipped with a power split mechanism 4. However, in the embodiment of the present invention, the vehicle Ve that is the object of control is not limited to the split-flow PHEV as described above. For example, the vehicle Ve may also be a "battery electric vehicle with a range extender" that can be charged by the power supplied from the external power source 12 as described above. In addition, it may be a conventional "hybrid electric vehicle (HEV)" that does not have the function of charging from the external power source 12. Alternatively, it may be a parallel or series HEV or PHEV other than the split-flow method described above.

[0054] The detection unit 6 is a device or apparatus for obtaining various data and information required when controlling the vehicle Ve, and includes, for example, a power supply unit, a microcomputer, a sensor, and an input / output interface. In particular, the detection unit 6 in the embodiment of the present invention detects data for controlling the engine 1, the first motor 2, and the second motor 3, respectively. For example, the detection unit 6 has an engine speed sensor 6a for detecting the speed of the engine 1, a motor speed sensor 6b for detecting the speed of the first motor 2, and a motor speed sensor 6c for detecting the speed of the second motor 3. In addition, for example, the detection unit 6 has various sensors / devices such as an SOC sensor 6d for detecting the state of charge (SOC) of the battery 5, a battery current sensor 6e for detecting the current value of the battery 5, and a battery temperature sensor 6f for detecting the temperature of the battery 5. In addition, the detection unit 6 is electrically connected to the controller 7 described later, and outputs an electrical signal corresponding to the detection value or calculated value of the various sensors, devices / apparatuses, etc. as described above to the controller 7 as detection data.

[0055] The controller 7 is, for example, an electronic control device mainly composed of a microcomputer, and mainly controls the actions of the engine 1, the first motor 2, and the second motor 3. Various data detected or calculated by the above-mentioned detection unit 6 are input to the controller 7. The controller 7 performs calculations using the input various data and pre-stored data, calculation formulas, etc. In addition, the controller 7 is configured to output its calculation results as control command signals, and control the actions of the engine 1, the first motor 2, and the second motor 3, etc., as described above.

[0056] In particular, the controller 7 in the embodiment of the present invention at least selectively sets a first control mode in which power is supplied from the battery 5 to drive the first motor 2 and the second motor 3 (mainly the second motor 3) and a second control mode in which power is not supplied from the battery 5 to the first motor 2 and the second motor 3 to drive the vehicle Ve (battery control). In addition, at this time, the controller 7 controls the driving force of the vehicle Ve based on the required driving force determined according to the accelerator opening (i.e., the driving requirement based on the driver's operation) and the vehicle speed (driving force control). Moreover, the controller 7 controls the operation of the engine 1 (engine control) based on at least a fully open action line (or WOT action line) obtained by connecting the operating point where the engine 1 outputs the maximum torque when the accelerator opening is maximum (i.e., the accelerator opening is 100%) and a non-fully open action line obtained by connecting the operating point where the exhaust state of the engine 1 is improved compared to the fully open action line. It should be noted that in Figure 2 Although only one controller 7 is shown in the figure, a plurality of controllers 7 may be provided for each device or apparatus to be controlled or for each control content.

[0057] The controller 7 of the vehicle Ve in the embodiment of the present invention is configured to appropriately execute the battery control, driving force control, and engine control described above, for example, by executing the following: Figure 3 The control is shown in the flowchart.

[0058] Figure 3 The control shown in the flowchart is executed, for example, when the main switch or power switch (not shown) of the vehicle Ve is turned on. First, in S1, it is determined whether the control mode that determines the control content of the vehicle Ve and the battery 5 is set to the power consumption (CD) mode or the first control mode. The CD mode is a control mode in which the stored power stored in the battery 5 is consumed by the motors 2 and 3, and is included in the "first control mode" in the embodiment of the present invention. Therefore, in the CD mode, power is supplied from the battery 5 to drive the first motor 2 or the second motor 3.

[0059] It should be noted that, in the battery control in the embodiment of the present invention, for example, one of the CD mode (or first control mode) and the power maintenance (CS) mode (or second control mode) is selected and set according to the state of charge (SOC) of the battery 5. The CS mode is a control mode for maintaining the power storage of the battery 5 at a predetermined level or suppressing the decrease of the power storage of the battery 5, and is included in the "second control mode" in the embodiment of the present invention. Therefore, in the CS mode, power is not supplied from the battery 5 to the first motor 2 and the second motor 3.

[0060] The CD mode and the CS mode are switched, for example, according to the SOC of the battery 5. Figure 2 The PHEV shown basically runs using the stored power of the battery 5 charged by the external power source 12 and the output torque of the second motor 3. Therefore, when the SOC of the battery 5 is sufficient, the CD mode is selected, and the power is supplied from the battery 5 to drive the second motor 3. And when the SOC of the battery 5 drops to a predetermined level, it changes to the CS mode, and controls so as to maintain the stored power of the battery 5 at a predetermined level.

[0061] If the control mode of the vehicle Ve and the battery 5 is not the CD mode (first control mode), that is, is set to the CS mode (second control mode), and the result of the determination in S1 is "No", the subsequent control is not executed. Figure 3 The routine is shown in the flowchart.

[0062] On the other hand, if the control mode of the vehicle Ve and the battery 5 is set to the CD mode (first control mode), and therefore a “YES” is determined in S1 , the process proceeds to S2 .

[0063] In S2, the use of the full-open action line (or WOT action line) is prohibited. Figure 4 As shown, in the driving force control in the embodiment of the present invention, the required driving force corresponding to the state of the maximum accelerator opening (100%) is set based on the composite torque (or fuel economy priority torque) obtained by summing the engine torque determined based on the non-full-opening operation line (or fuel economy priority operation line) and the motor torque that can be output based on the discharge allowable power (or dischargeable power) of the battery 5. In addition, in the engine control in the embodiment of the present invention, as described above Figure 1 As shown, the operation of the engine 1 is controlled based on the full-open operation line and the fuel economy priority operation line.

[0064] The fully open action line is an action line obtained by connecting the operating points at which the engine 1 outputs the maximum torque in the state where the driving demand based on the driver's operation is the maximum, that is, the state where the accelerator opening is the maximum (100%). The operating point of the engine 1 is a control target value of the engine 1 determined in the engine control, for example, based on the engine torque and the engine speed. By controlling the engine 1 based on the fully open action line, the engine 1 is in an operating state where the maximum torque is output. Therefore, the vehicle Ve is in a state where the maximum driving force corresponding to the maximum or fully open accelerator opening can be generated.

[0065] On the other hand, the fuel economy priority action line is an action line obtained by connecting the operating points where the exhaust state of the engine 1 is improved compared to the above-mentioned full-open action line and the fuel economy of the engine 1 is improved or the fuel economy of the engine 1 becomes optimal. That is, the fuel economy priority action line is an action line obtained by connecting the operating points where the exhaust state of the engine 1, such as the exhaust volume and exhaust components, is improved compared to the full-open action line, and is included in the non-full-open action line in the embodiment of the present invention. By controlling the engine 1 based on the non-full-open action line, the exhaust gas discharge of the engine 1 can be reduced compared to the case where the engine 1 is controlled based on the full-open action line, and the exhaust components such as CO can be reduced. In addition, by controlling the engine 1 based on the fuel economy priority action line, the exhaust gas discharge of the engine 1 can be reduced compared to the case where the engine 1 is controlled based on the full-open action line, and the exhaust components such as CO can be reduced. Moreover, the fuel economy of the engine 1 can be improved.

[0066] As mentioned above, in Figure 2 When the CD mode is set in the PHEV shown, when a large driving force is required such as the accelerator opening is at the maximum, the output of the engine 1 is added to the output of the second motor 3 in the CD mode to generate a large driving force corresponding to the required driving force. In such a case, in the previous control, in order to give priority to the power over the fuel economy of the engine 1, the full-open action line as described above is selected to control the engine 1 in the maximum output state. In the maximum output state of the engine 1, the exhaust temperature becomes high, so in order to reduce the exhaust temperature to protect the catalyst, the fuel injection amount is sometimes increased (so-called OTP increase, OT increase). Therefore, when the engine 1 is controlled based on the full-open action line, the fuel economy and exhaust emissions (properties and discharge amount of the exhaust gas) of the engine 1 will deteriorate compared to the case where the engine 1 is controlled based on the non-full-open action line or the fuel economy priority action line. If the fuel economy priority action line or the non-full-open action line is selected for a large driving requirement such as the accelerator opening being at the maximum, the driving force obtained will be insufficient, and the power performance of the vehicle Ve will be reduced.

[0067] Therefore, in the control device of the hybrid electric vehicle Ve in the embodiment of the present invention, as described above Figure 3 Flowchart and Figure 4 As shown, when the control mode of the vehicle Ve and the battery 5 is set to the CD mode (the first control mode), the operation of the engine 1 based on the full-open action line is prohibited. At the same time, the required driving force corresponding to the large driving requirement in which the accelerator opening is the largest is set based on the fuel economy priority torque (or compound torque) obtained by adding the engine torque when the engine 1 is operated on the fuel economy priority action line (or non-full-open action line) and the motor torque that can be output according to the state of the battery 5 at that time point. By prohibiting the operation of the engine 1 based on the full-open action line, the deterioration of the exhaust state of the engine 1 can be suppressed. At the same time, by setting the required driving force based on the fuel economy priority torque (compound torque) to which the maximum motor torque that can be output at that time point is added in addition to the engine torque, a suitable driving force corresponding to the driving requirement can be obtained.

[0068] As described above, if the use of the full-open operation line is prohibited in S2 and the process of setting the required driving force based on the fuel economy priority torque (compound torque) is executed, then the process is temporarily terminated. Figure 3 The routine is shown in the flowchart.

[0069] exist Figure 5 Another control example executed by the control device of the hybrid electric vehicle in the embodiment of the present invention is shown in the flowchart of Figure 5 In the control shown in the flowchart, compared with the above Figure 4 The control example shown in the flowchart of FIG. 1 adds the control of S11.

[0070] In this Figure 5 In the flowchart, if the control mode of the vehicle Ve and the battery 5 is set to the CD mode (first control mode) and the result in S1 is YES, it is determined in S11 whether a predetermined condition that the exhaust gas state of the engine 1 may deteriorate is satisfied.

[0071] As the predetermined condition that there is a possibility that the exhaust gas state of the engine 1 may deteriorate, for example, the following conditions can be cited.

[0072] (1) The intake air temperature of the engine 1 is higher than a predetermined temperature;

[0073] (2) The exhaust temperature of the engine 1 is above a predetermined temperature;

[0074] (3) The temperature of the cooling water of the engine 1 is above a predetermined temperature;

[0075] (4) The estimated temperature of the catalyst (not shown) is above a predetermined temperature;

[0076] (5) The elevation of the current location of vehicle Ve is above a prescribed height;

[0077] (6) Fuel of a fuel property (with a possibility of deterioration of the exhaust gas state) is being used, etc. When at least one of these predetermined conditions is satisfied, it is determined that there is a possibility that the exhaust gas state of the engine 1 will deteriorate.

[0078] If the above-mentioned predetermined conditions are not satisfied and it is determined that there is no possibility that the exhaust gas state of the engine 1 will deteriorate, and the determination in S11 is "No", the subsequent control is not executed. Figure 5 The routine is shown in the flowchart.

[0079] On the other hand, if at least one of the above-mentioned predetermined conditions is satisfied and it is determined that there is a possibility that the exhaust state of the engine 1 is deteriorated, and the determination in S11 is "yes", the process proceeds to S2 and the same control as before is performed. That is, the use of the full-open operation line is prohibited and the processing of setting the required driving force based on the fuel economy priority torque (compound torque) is performed.

[0080] It should be noted that the control device of the hybrid electric vehicle Ve in the embodiment of the present invention may also be configured as follows: Figure 6 As shown, in addition to the above-mentioned full-open action line and fuel economy priority action line, an intermediate action line is also set to perform engine control. The intermediate action line is an action line obtained by connecting operating points where the exhaust state of the engine 1 is improved compared to the above-mentioned full-open action line, the fuel economy of the engine 1 is improved, and the engine torque is increased compared to the above-mentioned fuel economy priority action line. That is, the intermediate action line is at least an action line obtained by connecting operating points where the exhaust state of the engine 1, such as the exhaust volume and exhaust composition, is improved compared to the full-open action line, and is included in the non-full-open action line in the embodiment of the present invention.

[0081] Furthermore, in the control device for the hybrid electric vehicle Ve in the embodiment of the present invention, for example, Figure 3 or Figure 5 In S2 of the flowchart of FIG. 5 , the use of the full-open action line is prohibited. Moreover, in S2, a process of setting the required driving force based on the intermediate torque (composite torque) is executed. The intermediate torque is a composite torque obtained by summing the engine torque determined based on the intermediate action line and the motor torque that can be output according to the discharge allowable power of the battery 5.

[0082] It should be noted that in the control device of the hybrid electric vehicle Ve in the embodiment of the present invention, as described above Figure 6As shown in FIG. 1 , three operation lines are set, namely, a full-open operation line, a fuel economy priority operation line, and an intermediate operation line. In the control device of the hybrid electric vehicle Ve, three torques (maximum torque, fuel economy priority torque, and intermediate torque) determined based on these three operation lines may be appropriately selected to perform engine control. Alternatively, in the control device of the hybrid electric vehicle Ve, instead of the aforementioned Figure 1 The control device of the hybrid electric vehicle Ve may also appropriately select torques (maximum torque and intermediate torque) determined based on both the full-open operation line and the intermediate operation line to perform engine control.

[0083] As described above, in the control device of the hybrid electric vehicle in the embodiment of the present invention, when the first control mode or the CD mode is selected, the operation of the engine 1 based on the full-open action line is prohibited. At the same time, the required driving force corresponding to the large driving requirement with the accelerator opening being the maximum (i.e., the target driving force in the driving force control) is set based on, for example, the engine torque when the engine 1 is operated by a non-full-open action line such as a fuel economy priority action line, an intermediate action line, and the composite torque (i.e., the fuel economy priority torque or the intermediate torque) obtained by adding the motor torque that can be output according to the state of the battery at that time point. Therefore, even in the case of requiring the accelerator opening to be the maximum large driving force, the use of the full-open action line is avoided, and the deterioration of the exhaust state of the engine 1 is suppressed. In addition, since the maximum torque of the motor that can be output at that time point is added to the engine torque based on the non-full-open action line, it is possible to appropriately deal with large driving requirements. That is, the power performance of the vehicle Ve can be ensured.

[0084] Therefore, the control device of the hybrid electric vehicle Ve according to the embodiment of the present invention can improve the fuel economy of the engine 1 without causing a decrease in the power performance of the vehicle Ve. Furthermore, the control device of the hybrid electric vehicle Ve according to the embodiment of the present invention can prevent the exhaust emission of the engine 1 from deteriorating.

Claims

1. A control device for a hybrid electric vehicle, the hybrid electric vehicle being equipped with an engine and an electric motor as driving force sources, and having a battery for exchanging electric power with the electric motor, the hybrid electric vehicle being capable of selectively setting at least a first control mode in which the electric motor is driven by power supplied from the battery and a second control mode in which the electric motor is driven without power supplied from the battery, and controlling the driving force based on a required driving force set in accordance with a vehicle speed and an accelerator opening, The control device includes a controller for controlling the hybrid electric vehicle. The controller controls the engine based on at least a fully open operation line obtained by connecting an operation point at which the engine outputs a maximum torque when the accelerator opening is at a maximum and a non-fully open operation line obtained by connecting an operation point at which the exhaust state of the engine is improved compared to the fully open operation line. The controller selects either the first control mode or the second control mode to cause the hybrid electric vehicle to travel, and When the first control mode is selected, the controller prohibits use of the full-open operation line, sets the required driving force corresponding to the state of the maximum accelerator opening based on a composite torque obtained by summing the output torque of the engine determined based on the non-full-open operation line and the output torque of the electric motor that can be output according to the discharge allowable power of the battery, and controls the driving force.

2. The control device for a hybrid electric vehicle according to claim 1, The controller determines, when the first control mode is selected, a predetermined condition indicating a possibility that the exhaust state may deteriorate. When determining that there is a possibility that the exhaust state may deteriorate, the controller prohibits use of the full-open operation line and sets the required driving force corresponding to the state where the accelerator opening is maximum based on the composite torque to control the driving force.

3. The control device for a hybrid electric vehicle according to claim 1 or 2, The non-fully open operation line includes a fuel economy priority operation line obtained by connecting operation points where the exhaust state is improved and the fuel economy of the engine is improved compared to the fully open operation line, The composite torque includes a fuel economy priority torque obtained by summing the output torque of the engine determined based on the fuel economy priority operation line and the output torque of the electric motor that can be output according to the discharge allowable power of the battery.

4. The control device for a hybrid electric vehicle according to claim 3, The non-fully open operation line includes an intermediate operation line obtained by connecting operation points where the exhaust state is improved and the fuel economy is improved compared to the fully open operation line and the output torque of the engine is increased compared to the fuel economy priority operation line, The composite torque includes an intermediate torque obtained by summing the output torque of the engine determined based on the intermediate operation line and the output torque of the electric motor that can be output according to the discharge allowable power of the battery. When the first control mode is selected or when it is determined that there is a possibility that the exhaust state may deteriorate, the controller prohibits use of the full-open action line and sets the required driving force corresponding to the state of maximum accelerator opening based on the intermediate torque to control the driving force.

5. The control device for a hybrid electric vehicle according to claim 1, The first control mode includes a CD mode in which the stored power of the battery is consumed by the electric motor. The second control mode includes a CS mode for maintaining the storage amount of the battery at a predetermined level. When the CD mode is selected, the controller prohibits use of the full-open operation line, sets the required driving force corresponding to the state where the accelerator opening degree is maximum based on the composite torque, and controls the driving force.

6. The control device for a hybrid electric vehicle according to claim 5, The controller determines, when the CD mode is selected, a predetermined condition indicating a possibility that the exhaust state may deteriorate. When determining that there is a possibility that the exhaust state may deteriorate, the controller prohibits use of the full-open operation line and sets the required driving force corresponding to the state where the accelerator opening is maximum based on the composite torque to control the driving force.

7. The control device for a hybrid electric vehicle according to claim 5 or 6, The non-fully open operation line includes a fuel economy priority operation line obtained by connecting operation points where the exhaust state is improved and the fuel economy of the engine is improved compared to the fully open operation line, The composite torque includes a fuel economy priority torque obtained by summing the output torque of the engine determined based on the fuel economy priority operation line and the output torque of the electric motor that can be output according to the discharge allowable power of the battery.

8. The control device for a hybrid electric vehicle according to claim 7, The non-fully open operation line includes an intermediate operation line obtained by connecting operation points where the exhaust state is improved and the fuel economy is improved compared to the fully open operation line, and the output torque of the engine is increased compared to the fuel economy priority operation line. The composite torque includes an intermediate torque obtained by summing the output torque of the engine determined based on the intermediate operation line and the output torque of the electric motor that can be output according to the discharge allowable power of the battery. When the CD mode is selected or when it is determined that there is a possibility that the exhaust state may deteriorate, the controller prohibits use of the full-open operation line and sets the required driving force corresponding to the state of the maximum accelerator opening based on the intermediate torque to control the driving force.

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