JP2022082371A - Engine start-up control method and engine start-up control device - Google Patents

Abstract

To provide optimized engine start-up control method and engine start-up control device which reduce energy consumption including fuel and electric power necessary for starting up an engine.SOLUTION: An engine start-up control method enables an engine to reach a target engine operation point through driving the same using fuel after motoring thereof. The engine start-up control method also enables the engine to be started up at a low rotation speed or a high rotation speed. In the engine start-up control method, a charging rate of a battery in a predetermined time section related to control is calculated on the basis of an analysis with respect to a present running pattern of a vehicle. When the charging rate in the predetermined section is higher than a predetermined value, the engine is started-up at the high rotation speed in the predetermined section. When the charging rate in the predetermined section is lower than the predetermined value, the engine is started up at the low rotation speed in the predetermined section.SELECTED DRAWING: Figure 3

Description

The present invention relates to a start control method and a start control device for an engine mounted on a vehicle.

Patent Document 1 proposes a hybrid vehicle that switches the engine starting method according to the cooling water temperature of the engine and the outputable power of the battery that supplies power to the cranking motor. Specifically, in the vehicle according to Patent Document 1, in a state where the water temperature of the engine is low and the battery for the cranking motor has a low output, the engine is used with fuel after waiting for the reduction of friction at low rotation speed. The two-stage start is adopted. Further, in the vehicle according to Patent Document 1, when the engine is started by the above-mentioned two-step start, the output power of the battery for the cranking motor and the resonance frequency band of the vehicle are taken into consideration, and the engine at the time of cranking is used. Set the number of revolutions.

Japanese Unexamined Patent Publication No. 2011-047348

In the hybrid vehicle, the engine speed to be reached by cranking (target rotation speed by cranking) can be set almost arbitrarily. On the other hand, the present inventors have found that the total amount of fuel and other energy consumption for starting the engine changes depending on the target rotation speed of cranking. However, in the control of Patent Document 1, it is not considered that the total consumption of fuel and the like (total energy consumed at the start of the engine) changes depending on the rotation speed at which the target of cranking is reached, and the fuel consumption and the electricity cost are poor. May become.

An object of the present invention is to provide an optimized engine start control method and engine start control device in which energy consumption is reduced, including fuel and electric power required for starting an engine.

One embodiment of the present invention is executed in a vehicle having a motor that generates driving force by electric power supplied from a battery, a generator that generates electric power supplied to the battery, and an engine that drives the generator, and starts an engine. This is an engine start control method in which the engine is driven by using fuel after the engine is motorized by using a generator to reach the target engine operating point, which is the target operating point of the engine. In this engine start control method, the engine is operated by either a low rotation start in which the motoring rotation speed, which is the rotation speed of the engine reached by motoring, is set low, or a high rotation start in which the motoring rotation speed is set high. Start. At this time, the battery charge rate in the predetermined section is calculated based on the analysis related to the current traveling pattern of the vehicle. When the charge rate of the battery in the predetermined section becomes higher than the predetermined value, the engine is started in the predetermined section by high rotation start. On the other hand, when the charge rate of the battery in the predetermined section becomes lower than the predetermined value, the engine is started in the predetermined section by low rotation start.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide an optimized engine start control method and an engine start control device in which energy consumption is reduced, including fuel and electric power required for starting an engine.

FIG. 1 is an explanatory diagram showing a schematic configuration of a vehicle. FIG. 2 is a block diagram showing a configuration of a controller related to engine starting. FIG. 3 is an explanatory diagram showing switching of an engine starting profile according to a battery charge rate. FIG. 4 is a graph showing the fluctuation of the threshold value with respect to the charge rate of the battery. FIG. 5 is an explanatory diagram showing switching of the engine starting profile in the modified example. FIG. 6 is a graph showing an example of changes in engine speed, cranking power, fuel consumption, and equivalent fuel consumption according to the starting profile. FIG. 7 is a table showing the magnitude of the cranking power at the time of starting, the fuel consumption until the target is reached, and the amount of power generation until the target is reached according to the starting profile. FIG. 8 is a graph showing the relationship between the motoring rotation speed and the equivalent fuel consumption according to the target engine rotation speed. FIG. 9 is an explanatory diagram showing candidates for operating points of the engine that can be transitioned. FIG. 10 is a graph referred to when determining an operating point that provides the best fuel economy when generating electricity. FIG. 11 is an explanatory diagram showing an example of basic equivalent fuel consumption. FIG. 12 is an explanatory diagram showing an example of total equivalent fuel consumption. FIG. 13 is a flowchart showing the engine starting method of the second embodiment according to the first method. FIG. 14 is a flowchart showing the engine starting method of the second embodiment according to the second method. FIG. 15 is a flowchart showing an engine starting method with a conversion coefficient as a variable when the engine starting method of the second embodiment is executed by the first method. FIG. 16 is a flowchart showing an engine starting method with a conversion coefficient as a variable when the engine starting method of the second embodiment is executed by the second method.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is an explanatory diagram showing a schematic configuration of a vehicle 100. As shown in FIG. 1, the vehicle 100 is a so-called series type hybrid vehicle. The vehicle 100 includes a motor 10, a battery 11, a generator 12, an engine 13, an auxiliary machine 14, and a controller 20.

The motor 10 is an electric motor that functions as a driving force source for the vehicle 100. That is, the motor 10 is a so-called drive motor, and the driving force is generated by the electric power supplied from the battery 11. Specifically, the output shaft of the motor 10 is connected to the drive shaft 17 via the speed reducer 16. Therefore, in the vehicle 100, torque is generated in the drive wheels 18 due to the output of the motor 10.

The battery 11 is electrically connected to the motor 10 and supplies electric power to the motor 10. At the time of regenerative control, the regenerative power is recovered by the battery 11. Further, the battery 11 is connected to the generator 12 and is charged by the electric power generated by the generator 12.

The generator 12 is a generator (power generation motor) that generates electric power to be supplied to the battery 11. The generator 12 is connected to the engine 13 connected via the reducer 19. When generating electric power, the generator 12 is driven by the engine 13. Further, when the engine 13 is started, the generator 12 cranks the engine 13 by idling (hereinafter, referred to as motoring) using the electric power of the battery 11. When starting the engine 13, the target of the engine rotation speed to be reached by motoring (hereinafter referred to as the motoring rotation speed) can be set (adjusted) almost arbitrarily.

The engine 13 is an internal combustion engine (ICE) driven by burning gasoline or other fuel. As described above, the engine 13 is not used as a direct driving force source for the vehicle 100, but the engine 13 is used to generate electric power to be supplied to the battery 11 by driving the generator 12. Therefore, the engine 13 is not always driven, but is started as needed while the vehicle is running or at other timings. The timing and output of starting the engine 13 are controlled by the controller 20 based on the analysis of the traveling pattern of the vehicle 100 according to the remaining amount of the battery 11 and the like.

The auxiliary machine 14 is another specific device constituting the vehicle 100. In the present embodiment, the auxiliary device 14 particularly refers to a load that consumes the electric power of the battery 11. For example, the inverter that converts the DC voltage output by the battery 11 into the AC voltage belongs to the auxiliary machine 14.

The controller 20 is a computer that collectively controls each part of the vehicle 100 such as the motor 10, the battery 11, the generator 12, and the engine 13. For example, the controller 20 is a target operating point of the engine 13 by driving the engine 13 with fuel after motorizing the engine 13 with the generator 12 when starting the engine 13. Reach the target engine operating point. That is, the controller 20 constitutes the engine starting device in the vehicle 100. The controller 20 is composed of, for example, a central processing unit (CPU), a random access memory (RAM), an input / output interface (I / O interface), and the like. Further, the controller 20 is programmed to periodically execute control of each unit at a predetermined control cycle.

Further, the controller 20 can acquire information related to the operating state and the like (hereinafter referred to as vehicle information) from each part of the vehicle 100 as needed. For example, the controller 20 can acquire other information such as operation information of the vehicle 100, temperature / environment information, and information necessary for analysis and prediction (running prediction) of a running pattern at an arbitrary timing. The operation information is, for example, information representing an operation state of a steering wheel, an accelerator pedal, a brake pedal, a shift lever, and the like. The temperature / environmental information includes, for example, the temperature of each part constituting the vehicle 100, the temperature of exhaust gas, information indicating the operating state or operating environment of other parts constituting the vehicle 100, and the charge rate of the battery 11 (hereinafter referred to as “charge rate”). , SOC (State Of Charge), etc.

In FIG. 1, P _{m_driv} represents the consumption of kinetic energy in the drive shaft 17 (hereinafter referred to as axle end kinetic energy consumption), and P _{m_mot} represents the consumption of kinetic energy in the motor 10 (hereinafter referred to as drive motor end kinetic energy consumption). ). P _{m_gen} represents the consumption of kinetic energy in the generator 12 (hereinafter referred to as power generation motor end kinetic energy consumption), and P _{m_ICE} represents the consumption of kinetic energy in the engine 13 (hereinafter referred to as ICE end kinetic energy consumption).

Further, P _{e_mot} represents the consumption of electric energy in the motor 10 (hereinafter referred to as the consumption of electric energy at the end of the drive motor). P _{e_bat} represents the consumption of electric energy in the battery 11 (hereinafter referred to as battery end electric energy consumption), and P _{e_gen} represents the consumption of electric energy in the generator 12 (hereinafter referred to as power generation motor end electric energy consumption). P _{e_other} represents the consumption of electrical energy by the auxiliary machine 14 (hereinafter referred to as auxiliary machine power consumption). The FC _ICE represents the consumption of fuel in the engine 13 (hereinafter referred to as fuel consumption).

FIG. 2 is a block diagram showing a configuration of a controller 20 related to starting the engine 13. As shown in FIG. 2, the controller 20 includes a traveling pattern analysis unit 21, an SOC calculation unit 22, and a start profile switching unit 23 in order to control the start of the engine 13.

The travel pattern analysis unit 21 analyzes the travel pattern of the vehicle 100. The traveling pattern of the vehicle 100 refers to a combination of vehicle information that can specify the amount of energy consumed, generated, or converted along with the traveling of the vehicle 100 or its transition. Therefore, the analysis of the traveling pattern means to identify, estimate, or predict the energy consumption, generation, conversion, or the like associated with the traveling of the vehicle 100 by calculation or the like using the vehicle information. The analysis of the running pattern is performed with respect to a time interval (hereinafter referred to as a predetermined section) relating to control of a certain time point or a certain time range in the past, present (time point of analysis of the running pattern), and / or in the future. Further, the analysis (prediction) of the driving pattern in the future can be performed based on, for example, the past and / or the current driving pattern. In the present embodiment, the travel pattern analysis unit 21 analyzes at least the current travel pattern. Further, for example, since the SOC fluctuates according to the traveling pattern, in the present embodiment, the SOC is specified by the analysis of the traveling pattern.

More specifically, the traveling pattern analysis unit 21 specifies the total power consumption _{Pe_all} of the vehicle 100 at least at the time of analysis (current time). The total power consumption _{Pe_all} is determined by the demand for driving force by the driver's operation (hereinafter referred to as driver operation). As shown in the following equation (1), the total power consumption P _{e_all} is the drive motor end electric energy consumption P _{e_mot} , the auxiliary power consumption P _{e_other} , the power generation motor end electric energy consumption P _{e_gen} , and the battery end electric energy consumption. It is the sum of _{Pe_bat} .

As shown in the following equation (2), the axle end kinetic energy consumption P _{m_driv} is determined by the drive motor end kinetic energy consumption P _{m_mot} and the drive system transmission efficiency η _driv . Further, as shown in the following equation (3), the drive motor end kinetic energy consumption P _{m_mot} is determined by the drive motor end electric energy consumption P _{e_mot} and the efficiency η _mot of the motor 10. It should be noted that the equations (2) and (3) represent the time of power running, and the efficiency (η _driv and η _mot ) of each of these equations is divided at the time of regeneration.

The axle end kinetic energy consumption P _{m_driv} is determined according to the driving force required for the vehicle 100 by the driver operation and the like. As a result, the drive motor end electric energy consumption _{Pe_mot} is determined by the equations (2) and (3). That is, the traveling pattern analysis unit 21 can specify the drive motor end electric energy consumption _{Pe_mot} in the equation (1) based on the vehicle information representing the driver operation. Further, the auxiliary power consumption _{Pe_other} is also determined by the required driving force to the vehicle 100 by the driver operation and the like. Therefore, the traveling pattern analysis unit 21 can specify the auxiliary power consumption _{Pe_other} in the equation (1). Therefore, the traveling pattern analysis unit 21 can specify the sum of the electric energy consumption P _{e_gen} at the power generation motor end and the electric energy consumption P _{e_bat} at the battery end, as shown in the following equation (4). From these facts, as a result of the analysis of the running pattern, there is a degree of freedom in the distribution of the electric energy consumption P _{e_gen} at the power generation motor end and the electric energy consumption P _{e_bat} at the battery end.

Here, as shown in the following equation (5), the electric energy consumption P _{e_gen} at the end of the power generation motor is expressed using the kinetic energy consumption P _{m_gen} at the end of the power generation motor and the efficiency η _gen of the generator 12. Then, as shown in the following equation (6), the power generation motor end kinetic energy consumption P _{m_gen} is expressed by using the ICE end kinetic energy consumption P _{m_ICE} and the transmission efficiency η _ICE-gen between the engine 13 and the generator 12. To. Further, as shown in the following equation (7), the ICE end kinetic energy consumption P _{m_ICE} is a predetermined function (or map) f (rev _ICE , trq) with the rotation speed rev _ICE and the torque trq _ICE of the engine 13 as arguments. _ICE ). Therefore, if the rotation speed rev _ICE and the torque trq _ICE of the engine 13 are determined, the electric energy consumption _{Pe_gen} at the end of the power generation motor is determined. As a result, the battery end electric energy consumption _{Pe_bat} is also determined by the equation (4). The rotation speed rev _ICE and torque trq _ICE of the engine 13 are vehicle information according to the driver operation. Therefore, the driving pattern analysis unit 21 identifies the total power consumption _{Pe_all} , which is the left side of the equation (1), and the terms on the right side of the equation (1), respectively, by analyzing the traveling pattern based on the vehicle information. Can be done.

The SOC calculation unit 22 calculates the SOC based on the analysis of the traveling pattern of the vehicle 100. The calculation of SOC changes according to the driving pattern by specifying or estimating the tendency of increase or decrease of SOC, the speed of increase or decrease of SOC, and / or the amount of increase or decrease of SOC. It refers to specifying or estimating the value of SOC. In the present embodiment, the travel pattern analysis unit 21 analyzes the current travel pattern of the vehicle 100, so that the SOC calculation unit 22 calculates the SOC at the time of analysis of the travel pattern based on the analysis result of the current travel pattern. calculate.

The starting profile switching unit 23 switches the starting profile of the engine 13 in a predetermined section based on the calculated SOC. More specifically, the start profile switching unit 23 determines whether or not the SOC in the predetermined section exceeds a predetermined value (threshold value SOC_t) based on the SOC. Then, based on this determination result, the starting profile of the engine 13 in the predetermined section is changed.

The starting profile is a setting that defines an aspect (starting method of the engine 13) when starting the engine 13. In the present embodiment, the start profile switching unit 23 has a low rotation start profile 24 and a high rotation start profile 25. Then, when the engine 13 is started in the predetermined section based on the SOC in the predetermined section, the start profile switching unit 23 sets the start mode of the engine 13 based on the low rotation start profile 24 (hereinafter referred to as low rotation start). , The start mode of the engine 13 based on the high-speed start profile 25 (hereinafter referred to as high-speed start) or which is to be adopted is determined. Therefore, when it is necessary to start the engine 13 within a predetermined section in which the traveling pattern is analyzed, the controller 20 sets the engine 13 in either a low rotation start or a high rotation start determined by the start profile switching unit 23. Start.

The low rotation speed start is a start mode of the engine 13 that sets the motoring rotation speed low. Therefore, in the low rotation start, the engine 13 reaches the target engine operating point by using fuel from the low rotation state. In the low rotation speed start, since the motoring rotation speed is low, the electric power of the battery 11 consumed for starting the engine 13 can be suppressed to a low level. Instead, the fuel consumed to start the engine 13 may be higher than in a high rpm start. That is, the low rotation start is a start mode for starting the engine 13 using fuel as a main energy source.

The high rotation speed start is a start mode of the engine 13 in which the motoring rotation speed is set higher than that of the low rotation speed start. Therefore, in the high rotation start, the engine 13 reaches the target engine operating point by using fuel from the high rotation state. Since the motoring speed is set high in the high rotation speed start, the electric power of the battery 11 consumed for starting the engine 13 is larger than that in the low rotation speed start. Instead, less fuel is consumed to start the engine 13 than to start at low rpm. That is, the high rotation start is a start mode in which the engine 13 is started by using the electric power of the battery 11 as a main energy source.

The terms "low rotation" and "high rotation" do not indicate the absolute value of the motoring rotation speed, but are relative. Further, in the present embodiment, for convenience of explanation, the start profile switching unit 23 has the low rotation start profile 24 and the high rotation start profile 25, but the start profile switching unit 23 has three or more start profiles. Can have in advance. Further, the start profile switching unit 32 can appropriately set a start profile according to the SOC.

FIG. 3 is an explanatory diagram showing switching of the starting profile of the engine 13 according to the charge rate (SOC) of the battery 11. As shown in FIG. 3, when the SOC in a predetermined section becomes higher than a predetermined value (hereinafter referred to as a threshold value) SOC_t based on the SOC, the engine 13 is started by high rotation start in this predetermined section. Will be. Further, when the SOC in the predetermined section becomes lower than the threshold value SOC_t based on the SOC, the engine 13 in the predetermined section is started by the low rotation start. When the SOC in a predetermined section is expected to be equivalent to the threshold SOC_t, the engine 13 is started in any mode of high rotation start or low rotation start. In the present embodiment, when the SOC in a predetermined section is expected to have the same value as the threshold value SOC_t, the engine 13 is started by a high rotation start.

FIG. 4 is a graph showing changes in the threshold value with respect to the charge rate (SOC) of the battery 11. As shown in FIG. 4, the threshold value SOC_t for switching between the low rotation start and the high rotation start is variable. The starting profile switching unit 23 adjusts (changes) the threshold value SOC_t according to, for example, the target engine operating point. Further, the start profile switching unit 23 can switch the threshold value SOC_t according to, for example, the temperature of the cooling water of the engine 13 (so-called engine water temperature). The starting profile switching unit 23 may set the threshold value SOC_t according to one or a plurality of parameters from the target engine operating point, engine water temperature, and / or other vehicle information. can.

As described above, in the engine starting method according to the first embodiment, the motor 10 that generates the driving force by the electric power supplied from the battery 11, the generator 12 that generates the electric power supplied to the battery 11, and the generator 12 are driven. It is executed by the vehicle 100 having the engine 13 and the engine 13. Further, in the engine starting method according to the first embodiment, when the engine 13 is started, the engine 13 is driven by using fuel after the engine 13 is motorized by the generator 12. Reach the target operating point (target engine operating point). Then, the engine 13 is started by either a low rotation start in which the motoring rotation speed, which is the rotation speed of the engine 13 reached by motoring, is set low, or a high rotation start in which the motoring rotation speed is set high. At this time, the charge rate (SOC) of the battery 11 is calculated for a predetermined time section related to control based on the analysis related to the current traveling pattern of the vehicle 100. When the charge rate (SOC) of the battery 11 in the predetermined section becomes higher than the predetermined value (threshold value SOC_t), the engine 13 in the predetermined section is started by the high rotation start. On the other hand, when the battery charge rate (SOC) in the predetermined section is lower than the predetermined value (threshold value SOC_t), the engine 13 is started in the predetermined section by low rotation start.

That is, in the engine starting method according to the first embodiment, when the engine 13 is started in the vehicle 100 which is a hybrid vehicle, the starting method of the engine 13 is started at a low rotation speed based on the SOC calculated based on the traveling pattern. It can be switched between and high rotation start. This depends on the value of the battery 11 held by the battery 11 as an energy source (hereinafter referred to as the value of the battery power) and the value of the fuel as an energy source (hereinafter referred to as the value of the fuel). It switches between starting the engine 13 as the main energy source and starting the engine 13 using fuel as the main energy source.

The situation where the SOC increases is that the value of the battery power is lower than the value of the fuel in the total amount of energy that the vehicle 100 can use for driving each part and the like. Therefore, in a situation where the value of the battery power is lower than the value of the fuel, such as when the SOC increases, the engine 13 is started using the power of the battery 11 as the main energy source by adopting the high rotation start. .. That is, when the SOC increases, the consumption of the relatively high-value fuel is suppressed, and the electric power of the relatively low-value battery 11 is positively used to start the engine 13. As a result, the total consumption of energy that can be used by the vehicle 100 for driving each part and the like can be suppressed, and as a result, the electricity cost and the fuel consumption (hereinafter referred to as energy efficiency) of the vehicle 100 are improved.

In addition, the situation where SOC decreases is that the value of battery power is higher than the value of fuel. Therefore, in a situation where the value of the battery power is higher than the value of the fuel, such as a decrease in SOC, the engine 13 is started using the fuel as the main energy source by adopting the low rotation start. That is, when the SOC decreases, the power of the relatively high value battery 11 is preserved, and the relatively low value fuel is positively used to start the engine 13. As a result, the total consumption of energy that can be used by the vehicle 100 for driving each part or the like can be suppressed, and as a result, the energy efficiency of the vehicle 100 is improved.

Therefore, according to the engine starting method according to the first embodiment, it is possible to improve the energy efficiency of the vehicle 100, which needs to start the engine 13 in a timely manner. That is, according to the engine starting method according to the first embodiment, it is optimized to a state in which energy consumption is reduced, including fuel, electric power, and the like required for starting the engine 13.

In the first embodiment, the traveling pattern analysis unit 21 analyzes the current traveling pattern. Therefore, the SOC calculation unit 22 calculates the SOC based on the current traveling pattern. As a result, the switching of the starting profile by the starting profile switching unit 23 is also based on the analysis result of the current traveling pattern. However, as described above, the travel pattern analysis unit 21 can predict the future travel pattern of the vehicle 100. At this time, the SOC calculation unit 22 can calculate the charge rate (SOC) of the battery 11 in the predetermined section based on the prediction of the running pattern in the future in addition to the analysis of the current running pattern. As a result, the switching of the starting profile by the starting profile switching unit 23 can also be performed in consideration of the running pattern in the future.

FIG. 5 is an explanatory diagram showing switching of the engine starting profile in the modified example. As shown in FIG. 5, the start profile switching unit 23 sets a predetermined value of the SOC predicted value (hereinafter referred to as “predicted SOC”) calculated by the SOC calculation unit 22 including the prediction of the driving pattern in the future as a threshold value. Compare with SOC_t. This threshold value SOC_t is, for example, the same value as the threshold value SOC_t in the first embodiment, and is set according to one or a plurality of parameters from the target engine operating point, engine water temperature, and / or other vehicle information and the like. To. In this modification, when the predicted SOC is higher than the threshold SOC_t, the high rotation start is adopted, and when the predicted SOC is lower than the threshold SOC_t, the low rotation start is adopted.

As described above, in the engine starting method according to the first embodiment, the future driving pattern of the vehicle 100 is predicted, and the charge rate (SOC) of the battery 11 in the predetermined section is added to the analysis of the current driving pattern. , It can be transformed into a mode calculated based on the prediction of the driving pattern in the future. In this modification, when the charge rate (SOC) of the battery 11 in a predetermined section is predicted to increase from a predetermined value (threshold value SOC_t), the engine 13 in this predetermined section is started by a high rotation start. On the other hand, when the charge rate (SOC) of the battery 11 in the predetermined section is predicted to be smaller than the predetermined value (threshold value SOC_t), the engine 13 in the predetermined section is started by the low rotation start.

Also in the engine starting method of the above modification, the energy efficiency of the vehicle 100, which needs to start the engine 13 in a timely manner, can be improved for the same reason as the engine starting method according to the first embodiment. Further, in the engine starting method of the above modification, since the running pattern in the future is taken into consideration, the value of the battery power can be estimated more accurately than the engine starting method according to the first embodiment. As a result, according to the engine starting method according to the above-described modification, the energy efficiency of the vehicle 100, which needs to start the engine 13 in a timely manner, can be particularly improved.

[Second Embodiment]
In the first embodiment and the modification, the SOC is calculated or predicted based on the analysis of the running pattern in order to estimate the value of the battery power, but the SOC is not limited to this. For example, if the SOC is correlated and the value of battery power can be estimated, other parameters can be used instead of directly calculating or predicting the SOC. Therefore, in the second embodiment, an example in which the conversion coefficient K is used as a parameter that has a correlation with the SOC and represents the value of the battery power will be described.

The conversion coefficient K is a coefficient for virtually converting the battery end electric energy consumption _{Pe_bat} into fuel consumption equivalent to this. That is, the conversion coefficient K is a parameter that equivalently converts the charge rate (SOC) of the battery 11 in a predetermined section from the power consumption of the battery 11 (electrical energy consumption at the battery end Pe_bat) to the consumption of fuel. Therefore, according to the conversion coefficient K, the value of battery power and the value of fuel are evaluated in a unified manner. The chemical conversion coefficient for evaluating the fuel as energy is constant depending on the chemical composition of the fuel, regardless of the traveling pattern of the vehicle 100 or the like. However, the conversion coefficient K used here does not represent such a constant chemical conversion coefficient, and evaluates the value of battery power or the value of fuel including the energy loss that occurs in actual driving and the like. It is a parameter for. Therefore, the conversion coefficient K varies depending on the actual driving pattern, particularly the SOC that changes depending on the actual traveling pattern. However, the conversion coefficient K is a substantially constant value for each traveling pattern and is predetermined, for example, by an experiment or the like. For example, the conversion coefficient K is obtained from the low calorific value of the fuel, the representative fuel consumption rate, the power generation efficiency, and the like. Further, the conversion coefficient K is obtained by machine learning using the traveling pattern and position information of the vehicle 100, the operation information of the accelerator and the brake, and the like. Further, the conversion coefficient K may be a delivery value calculated from the probe data.

The value obtained by converting the battery end electric energy consumption _{Pe_bat} to the fuel consumption equivalent (hereinafter referred to as the battery end fuel consumption) FC _bat is expressed by the following equation (8) using the conversion coefficient K.

When the SOC is high, the conversion coefficient K is correspondingly small. On the contrary, when the SOC is low, the conversion coefficient K is correspondingly large. That is, the relationship between the SOC and the conversion coefficient K is generally inversely proportional. Therefore, in the second embodiment, the SOC calculation unit 22 specifies the conversion coefficient K according to the travel pattern based on the analysis of the travel pattern. The conversion coefficient K is predetermined for each traveling pattern, for example, by an experiment or the like.

Further, in the second embodiment, the starting profile switching unit 23 changes the motoring rotation speed at the time of starting the engine 13 based on the conversion coefficient K calculated by the SOC calculation unit 22 to change the engine. Adjust the starting method of 13. This corresponds to smoothly switching between the low rotation start and the high rotation start in the first embodiment by dividing into finer stages.

More specifically, the starting profile switching unit 23 calculates the equivalent fuel consumption FC _eq using the conversion coefficient K, and determines the motoring rotation speed under the condition of minimizing the equivalent fuel consumption FC eq. The equivalent fuel consumption FC _eq is the energy consumption obtained by converting the total energy consumption of the power consumption of the battery 11 (electrical energy consumption at the battery end _{Pe_bat} ) and the fuel consumption FC _ICE of the engine 13 into fuel consumption. That is, the equivalent fuel consumption FC _eq is expressed by the following equation (9).

FIG. 6 is a graph showing an example of changes in engine speed, cranking power, fuel consumption, and equivalent fuel consumption according to the starting profile. 6 (A) to 6 (D) show the time of high rotation start in which motoring is executed until time τ1, and FIGS. 6 (E) to 6 (F) show motoring until time τ2 (τ2 <τ1) under the same conditions. Indicates the time of low rotation start to be executed. Further, the cranking powers in FIGS. 6 (B) and 6 (F) show the power of motoring, and the area of these graphs is the total amount of battery-end electric energy consumption _{Pe_bat} consumed for motoring. show. As shown in FIGS. (A) and (E), the engine speed (engine speed corresponding to the target engine operating point) finally reached is the same between the high speed start and the low speed start. However, as shown in FIGS. 6 (D) and 6 (H), the equivalent fuel consumption FC _eq may differ between the low rotation start and the high rotation start. In this example, the equivalent fuel consumption FC _{eq at low rpm start is larger than the equivalent fuel consumption FC eq at} high rpm start.

FIG. 7 is a table showing the magnitude of the cranking power at the time of starting, the fuel consumption until the target is reached, and the amount of power generation until the target is reached according to the starting profile. As shown in FIG. 7, the cranking power at the start, that is, the power consumed by the motoring is small at the low rotation start and large at the high rotation start. Further, the fuel consumption in the engine 13 until the target engine operating point is reached is large at the low rotation speed start and small at the high rotation speed start. Further, the amount of power generation until the target engine operating point is reached is large at low rotation start and small at high rotation start.

Further, FIG. 8 is a graph showing the relationship between the motoring rotation speed and the equivalent fuel consumption FC _eq according to the target engine rotation speed. As shown in FIG. 8, in a traveling pattern to which a certain conversion coefficient K is applied, when the motoring rotation speed is changed when the engine 13 is started, the equivalent fuel consumption FC _eq also changes. At this time, the specific transition of the equivalent fuel consumption FC _eq changes depending on whether the engine speed (hereinafter referred to as the target speed) Trev at the target engine operating point is T1 [rpm] or T2 [rpm] (T2> T1). do. However, there is a relationship shown in FIG. 7 between the cranking power at the time of starting and the motoring rotation speed, and the relationship between the change in the motoring rotation speed and the equivalent fuel consumption FC _eq is as shown in FIG. There is. Therefore, as shown by the black dots in FIG. 8, there is a motoring rotation speed at which the equivalent fuel consumption FC _eq is the minimum or the minimum in any case.

Therefore, the starting profile switching unit 23 calculates a plurality of equivalent fuel consumption FC _eq by changing the motoring rotation speed as shown in FIG. Then, based on the calculated plurality of equivalent fuel consumption FC _eq , the optimum motoring rotation speed which is the motoring rotation speed when the equivalent fuel consumption FC _eq is minimized (motoring rotation speed indicated by black dots in FIG. 8). To decide. After that, when the engine 13 is started, the controller 20 motors the engine 13 to this optimum motoring speed.

As described above, in the engine starting method according to the second embodiment, the charge rate (SOC) of the battery 11 in the predetermined section is equivalently converted from the power consumption of the battery 11 (electrical energy consumption at the battery end _{Pe_bat} ) to the fuel consumption. It is represented by the conversion coefficient K. Further, using the conversion coefficient K, the equivalent fuel consumption FC _eq is calculated by converting the energy consumption, which is the sum of the power consumption of the battery 11 and the fuel consumption, into the fuel consumption. Then, the motoring rotation speed is determined under the condition of minimizing the equivalent fuel consumption.

As a result, according to the engine starting method according to the second embodiment, the energy consumption is optimized to be reduced, including the fuel and electric power required for starting the engine. In particular, in the second embodiment, since the motoring rotation speed is determined based on the equivalent fuel consumption FC _eq , the starting method of the engine 13 is smoothly adjusted almost steplessly. Therefore, according to the engine starting method of the second embodiment, the energy consumption is optimized to be more preferably reduced than that of the engine starting method of the first embodiment.

Further, in the engine starting method according to the second embodiment, specifically, a plurality of equivalent fuel consumption FC _eqs are calculated by changing the motoring rotation speed, and based on the calculated plurality of equivalent fuel consumption FC _eqs , Determine the optimum motoring speed, which is the motoring speed when the equivalent fuel consumption FC _eq is minimized. Then, when the engine is started, the engine is motorized to this optimum motoring speed.

That is, in the engine starting method of the second embodiment, when the target engine operating point and the conversion coefficient K are determined according to the traveling pattern, the optimum motoring rotation speed is calculated in this specific traveling pattern. Therefore, according to the engine starting method of the second embodiment, it is possible to accurately respond to a realistic change in the traveling pattern and optimize the state in which energy consumption is reduced.

Hereinafter, in the engine starting method according to the second embodiment, there are two types, the first method and the second method, as more specific methods for determining the optimum motoring speed and optimizing the energy consumption. To explain.

FIG. 9 is an explanatory diagram showing candidates for operating points of the engine 13 that can transition. In FIG. 9, it is assumed that the operation for control by the controller 20 is performed every predetermined time step sti (i = 1 to n). In FIG. 9, the time step st0 is the present, and the time steps st1 to n are the future. The time section from the time step st0 to the time step stn is a predetermined section in the first embodiment. Further, the points indicated by white circles in each time step sti represent the operating points (i, j) (j = 1 to m) of the engine 13 that can be transitioned. For example, the operating points that can transition from the current (st0) operating point to the time of the next time step st1 are (1,1) to (1, m). Further, the operating points (i, j) that can be transitioned include an operating point belonging to the HEV mode (hybrid electric vehicle mode) in which the engine 13 is used and an operating point belonging to the EV mode (electric vehicle mode) in which the engine 13 is not used. There is. In FIG. 9, the operating point of j = 1 is the operating point of the EV mode, and the operating point of j = 2 to m is the operating point of the HEV mode. Therefore, when the EV mode operating point (i, 1) transitions to the HEV mode operating point (i + 1, 2) to (i + 1, m), the engine 13 is started. As for the operating point in the HEV mode, the larger the value of the index "j", the larger the output (ICE power) of the engine 13.

Note that FIG. 10 is a graph referred to when determining an operating point at which the fuel consumption at the time of power generation is the best. P1, P2, and P3 in FIG. 10 indicate isopower lines. As shown by black dots in FIG. 10, the operating point sequence (so-called α ray) of the engine 13 that gives the best fuel consumption during power generation under the same output conditions is determined. Therefore, the operating point (i, j) in FIG. 9 is the rotation speed and torque that the ICE power (ICE end kinetic energy consumption P _{m_ICE} ) actually outputs to the engine 13 by referring to the graph in FIG. Can be associated.

[First method]
The starting profile switching unit 23 in the second embodiment is the equivalent fuel consumption FC _eq required for the transition for each operating point (i, j) of the engine 13 that can be transitioned when the optimum motoring rotation speed is determined. Calculate the basic equivalent fuel consumption FC _eq-basic . The basic equivalent fuel consumption FC _eq-basic is an operating point (i + 1, j) that can transition from the operating point (i, j) of one time step to the next time step (“j” here is an arbitrary value. Represents the energy consumption required when transitioning to (a). However, the basic equivalent fuel consumption FC _eq-basic represents the energy consumption required for the transition of the operating point, and does not include the energy consumption required for starting the engine 13. Therefore, the basic equivalent fuel consumption FC _eq-basic represents the energy consumed when the operating point is changed while the engine 13 is started.

The ICE end kinetic energy consumption P _{m_ICE} (i, j) and the battery end electric energy consumption P _{e_bat} (i, j) at each operating point (i, j) can be obtained by vehicle information and / or prediction of vehicle information. .. The basic equivalent fuel consumption FC _eq-basic is calculated based on the ICE end kinetic energy consumption P _{m_ICE} (i, j) and the battery end electric energy consumption P _{e_bat} (i, j) at each operating point (i, j). It is possible.

FIG. 11 is an explanatory diagram showing an example of the basic equivalent fuel consumption FC _eq-basic . Here, it is assumed that there are operating points (i, 1) to (i, 5) that can transition from a certain operating point (i-1, j) in a certain time step sti-1 in the next time step sti. As shown in FIG. 11, the amount and breakdown of the energy consumption for the transition, that is, the basic equivalent fuel consumption FC _eq-basic , differs depending on the operating points (i, 1) to (i, 5) that can be transitioned.

For example, in order to transition to the operating point (i, 1) in the EV mode, there is no fuel consumption FC _ICE of the engine 13, and only the power consumption of the battery 11 (battery end fuel consumption FC _bat ) is required. Therefore, the basic equivalent fuel consumption FC _eq-basic required for transitioning to the operating point (i, 1) of the EV mode is the same as the battery end fuel consumption FC _bat as shown by the left arrow.

Further, when transitioning to the operating point (i, 2) of the HEV mode, for example, both the fuel consumption FC _ICE and the battery end fuel consumption FC _bat are required. Therefore, the basic equivalent fuel consumption FC _eq-basic required when transitioning to the operating point (i, 2) of the HEV mode is the sum of the fuel consumption FC _ICE and the battery end fuel consumption FC _bat , as shown by the left arrow. Is.

When transitioning to the operating point (i, 4) or the operating point (i, 5), the battery end fuel consumption FC _bat is a negative value. This means that the electric power corresponding to the fuel consumption FC _bat at the battery end is recovered to the battery 11 by the power generation.

As can be seen by comparing the lines of the left arrow indicating the basic equivalent fuel consumption FC _eq -basic, the basic equivalent fuel consumption FC _eq-basic is the fuel consumption FC _ICE and the battery end fuel consumption required for the transition of the operating point. It fluctuates depending on the balance of FC _bat . In the example of FIG. 11, the basic equivalent fuel consumption FC _eq-basic at the transition to the operating point (i, 3) is the minimum.

The starting profile switching unit 23 calculates the above-mentioned basic equivalent fuel consumption FC _eq-basic for all the transition paths in FIG. 9, for example, so that the sum of the basic equivalent fuel consumption FC _eq-basic is minimized. The transition pattern of the operating point (i, j) determined in the series is determined. For example, in FIG. 9, the transition pattern shown by the thick line is the transition pattern in which the basic equivalent fuel consumption FC _eq-basic is minimized.

When the transition pattern is determined in this way, the start profile switching unit 23, when the transition to the operating point accompanied by the start of the engine 13 is included in this transition pattern, the transition to the operating point accompanied by the start of the engine 13. Equivalent fuel consumption FC _eq-start at start (see FIG. 12) is calculated. The equivalent fuel consumption FC _eq-start at the time of starting is the equivalent fuel consumption FC _eq related to the start of the engine 13. For example, in FIG. 9, in the transition pattern in which the basic equivalent fuel consumption FC _eq-basic is minimized, the operating point of the EV mode (1, 1) in the time step st1 is changed to the operating point of the HEV mode in the time step st2. At the time of transition, the engine 13 is started. Therefore, the start profile switching unit 23 calculates the equivalent fuel consumption FC _eq-start at the time of starting for this transition path.

Further, the start profile switching unit 23 calculates a plurality of equivalent fuel consumption FC _eq- starts at the time of starting by changing the motoring rotation speed. This is because the equivalent fuel consumption FC _eq-start at the time of starting changes according to the motoring rotation speed. Then, the start profile switching unit 23 determines the optimum motoring rotation speed to be the motoring rotation speed when the equivalent fuel consumption FC _eq-start at the time of starting is minimized. When there are multiple transition paths that accompany the start of the engine 13 in the transition pattern that minimizes the basic equivalent fuel consumption FC _eq-basic , the optimum motoring speed is determined for each of these transition paths in the same manner as above. do.

Equivalent fuel consumption at start FC _eq-start is expressed as follows. First, assuming that the motoring rotation speed is "r", _{Pe_bat-stat} , which is the electrical energy consumed by the motoring at the start of the engine 13 (hereinafter referred to as the power consumption at the start), is a function in which the motoring rotation speed r is used as an argument. Suppose there is. At this time, after motoring, the fuel consumption required to raise the engine speed to the target speed Trev (hereinafter referred to as fuel consumption at start) FC _ICE-stat is also a function that takes the motoring speed r as an argument. Can be represented. In addition, _{Pe_bat-statgen} , which is the electric energy generated via the generator 12 (hereinafter referred to as the amount of power generated at the start) while consuming fuel to increase the rotation speed, also uses the motoring rotation speed r as an argument. It can be expressed by a function.

The larger the motoring speed "r", the larger the power consumption _{Pe_bat-start} at the start, and the smaller the fuel consumption FC _ICE-stat at the start and the power generation amount _{Pe_bat-statgen} at the start. Therefore, if the conversion coefficient K is determined, the operation from the start of the engine 13 to the target ICE end kinetic energy consumption P _{m_ICE} when the motoring rotation speed is set to a certain motoring rotation speed "r". The equivalent fuel consumption fc _eq-start at the time of starting consumed by is expressed by the following equation (10).

Therefore, when the transition to a certain operating point (i, j) is accompanied by the start of the engine 13, when the adjustment is made so as to be the minimum by the motoring rotation speed “r”, it is consumed to start the engine 13. The equivalent fuel consumption FC _eq-start at the time of starting is expressed by the following equation (11). The argument of the minimum function of the equation (11) is the start equivalent fuel consumption fc _eq-start of the equation (10).

Considering the equivalent fuel consumption FC _eq-start at the time of starting as described above, the operating point to be transitioned may change in order to minimize the energy consumption as compared with the case where this is not taken into consideration (see FIG. 11). In the following, the sum of the basic equivalent fuel consumption FC _eq-basic and the start equivalent fuel consumption FC _eq-start is referred to as the total equivalent fuel consumption FC _eq-all .

FIG. 12 is an explanatory diagram showing an example of the total equivalent fuel consumption FC _eq-all . FIG. 12 shows the same situation as in FIG. 11 with the addition of FC _eq-start equivalent fuel consumption at the start. Further, in FIG. 12, the total equivalent fuel consumption FC _eq-all is shown by the left arrow. According to the basic equivalent fuel consumption FC _eq-basic , the energy consumption becomes the minimum when the operating point (i, 3) is reached (see Fig. 11). Considering the equivalent fuel consumption FC _eq-start at the start, the energy consumption Is truly minimized at the transition to the operating point (i, 4), as shown in FIG.

However, in the first method described here, the transition to the operating point (i, 4) is not selected instead of the transition to the operating point (i, 3). The first method described here is to select the transition to the operating point (i, 3) according to the basic equivalent fuel consumption FC _eq-basic , while motorizing the equivalent fuel consumption FC _eq-start at the start. By adjusting and minimizing "r", it is optimized for the state where energy consumption is reduced. The method of determining the transition pattern of the operating point so that the total equivalent fuel consumption FC _eq-all is minimized is the second method described later.

FIG. 13 is a flowchart showing the engine starting method of the second embodiment according to the first method. As shown in FIG. 13, in step S201, parameters necessary for calculating the total equivalent fuel consumption FC _eq-all , such as the drive motor end electric energy consumption _{Pe_mot} , are acquired. Further, in steps S202 and S203, the index that specifies the operating point (i, j) is initialized. After that, in step S204, the ICE output candidates at each transitionable operating point (i, j), that is, the ICE end kinetic energy consumption P _{m_ICE} (i, j) and the battery end electric energy consumption P _{e_bat} (i, j) Set. Then, in step S205, the best fuel consumption operating point (rotation speed and torque) is set for each ICE end kinetic energy consumption P _{m_ICE} (i, j).

Then, in step S206, the basic equivalent fuel consumption FC _eq-basic is calculated for each transition path between the operating points (i, j). Specifically, the fuel consumption FC _ICE (i, j) is calculated for each of the ICE end kinetic energy consumption P _{m_ICE} (i, j). Further, the battery end electric energy consumption P _{e_bat} (i, j) corresponding to the ICE end kinetic energy consumption P _{m_ICE} (i, j) is calculated, and the battery corresponding to the battery end electric energy consumption P _{e_bat} (i, j) is further calculated. The end fuel consumption FC _bat (i, j) is calculated. As a result, the basic equivalent fuel consumption FC _eq-basic , which is the sum of the fuel consumption FC _ICE (i, j) and the battery end fuel consumption FC _bat (i, j), is calculated.

In step S207, it is confirmed whether the basic equivalent fuel consumption FC _eq-basic has been calculated for all the operating points that can be transitioned in the specific time step. If there is an operating point for which the basic equivalent fuel consumption FC _eq-basic has not been calculated, the index “j” is incremented in step S208, and the above calculation of the basic equivalent fuel consumption FC _eq-basic is repeated. Then, in step S209, it is confirmed whether the basic equivalent fuel consumption FC _eq-basic has been calculated for all the time steps in the predetermined section. If there is a time step in which the basic equivalent fuel consumption FC _eq-basic has not been calculated, the index “i” is incremented in step S210, and the above calculation of the basic equivalent fuel consumption FC _eq-basic is repeated. As a result, the basic equivalent fuel consumption FC _eq-basic is calculated for all the time steps included in the predetermined section and the transition between the operating points (i, j).

When the calculation of the basic equivalent fuel consumption FC _eq-basic is completed, it is confirmed in step S211 whether or not the transition between the operating points is accompanied by the start of the engine 13. Then, for the transition path accompanied by the start of the engine 13, in step S212, the equivalent fuel consumption FC _eq-start at the time of starting is calculated while changing the motoring rotation speed “r” of the equation (10). As a result, in step S213, the optimum motoring rotation speed that minimizes the equivalent fuel consumption FC _eq-start at the start is determined.

After that, in step S214, the total equivalent fuel consumption FC _eq-all is calculated. As a result, in step S215, the transition pattern of the operating point at which the total equivalent fuel consumption FC _eq-all is minimized is determined. Then, in step S216, an instruction of an operating point based on the determined transition pattern is output to the vehicle 100. As a result, when the determined transition pattern includes the transition path of the operating point accompanied by the start of the engine 13, when the engine 13 is started, the motor is motorized to the optimum motor rotation speed.

As described above, in the engine starting method of the second embodiment according to the first method, the equivalent fuel consumption FC _eq required for the transition is obtained for each operating point (i, j) of the engine 13 that can transition in the predetermined section. The basic equivalent fuel consumption FC _eq-basic is calculated, and the transition pattern of the operating points (i, j) determined in time series is determined so that the sum of the basic equivalent fuel consumption FC _eq-basic is minimized. Further, when the transition to the operating point accompanied by the start of the engine 13 is included in this transition pattern, the equivalent fuel consumption FC _eq related to the start of the engine 13 is obtained for the transition to the operating point accompanied by the start of the engine 13. A plurality of equivalent fuel consumption FC _eq- starts at the time of starting are calculated by changing the motoring rotation speed "r". Then, the optimum motoring rotation speed is determined by the motoring rotation speed when the equivalent fuel consumption FC _eq-start at the start is minimized.

In the engine starting method according to this first method, after the transition pattern of the operating point is determined, the equivalent fuel consumption FC _eq-start at the time of starting is calculated for the transition path accompanied by the starting of the engine 13 included in the transition pattern. Therefore, since the FC _eq-start equivalent fuel consumption at the start is calculated only for the required transition path, the calculation load for the above-mentioned minimum equivalent fuel consumption strategy is light. Therefore, the engine 13 can be driven quickly and easily with a semi-optimal transition pattern. As a result, the drive of the engine 13 is optimized to a state in which energy consumption is reduced.

[Second method]
In the engine starting method of the second embodiment according to the first method described above, after determining the transition pattern based on the basic equivalent fuel consumption FC _eq-basic , the equivalent fuel consumption FC _eq-start at the time of starting is calculated as necessary. do. On the other hand, in the second method described here, the starting profile switching unit 23 determines the transition pattern based on the total equivalent fuel consumption FC _eq-all .

FIG. 14 is a flowchart showing the engine starting method of the second embodiment according to the second method. As shown in FIG. 14, the difference between the second method and the first method is that steps S211 to S214 for calculating the equivalent fuel consumption FC _{eq-start at the start} and the total equivalent fuel consumption FC _eq-all are , It is provided between step S206 and step S207 (that is, in the loop for calculating the basic equivalent fuel consumption FC _eq-basic by the first method). Therefore, in the second method, for all the transition paths of the operating points (i, j) that can be transitioned, when the transition path is accompanied by the start of the engine 13, the equivalent fuel consumption FC _eq-start at the start is set. It is calculated and the total equivalent fuel consumption FC _eq-all is calculated.

That is, in the engine starting method of the second embodiment according to the second method, the basic equivalent fuel which is the equivalent fuel consumption FC _eq required for the transition for each operating point (i, j) of the engine 13 that can transition in the predetermined section. The consumption FC _eq-basic is calculated. Further, when the transition of the operating point (i, j) is accompanied by the start of the engine 13, the equivalent fuel consumption FC _eq related to the start of the engine 13 for the transition to the operating point (i, j) accompanied by the start of the engine 13. The equivalent fuel consumption FC _eq-start at the time of starting is calculated in plurality by changing the motoring rotation speed “r”. At this time, the optimum motoring rotation speed is determined by the motoring rotation speed that minimizes the equivalent fuel consumption FC _eq-start at the time of starting for each transition to the operating point (i, j) accompanied by the start of the engine 13. (Step S213 in FIG. 14). Further, for each transition pattern of the operating point (i, j) determined in time series, the basic equivalent fuel consumption FC _eq-basic and the equivalent fuel consumption FC _eq- at the time of starting when the engine 13 is started at the optimum motoring speed. By adding _start and, the total equivalent fuel consumption FC _eq-all is calculated. Then, the transition pattern to be executed is determined so that the total equivalent fuel consumption FC _eq-all is minimized.

As described above, in the engine starting method of the second embodiment by the second method, a transition pattern in which the total equivalent fuel consumption FC _eq-all is minimized is adopted. This corresponds to the selection of the transition pattern transitioning to the operating point (i, 4) in the example of FIG. Therefore, according to the engine starting method according to the second method, the driving of the engine 13 is optimized to a state in which the energy consumption is particularly reduced.

In the engine starting method of the second embodiment, a plurality of time steps are taken into consideration regardless of whether the method of specifically executing the engine starting method of the second embodiment is the first method or the second method. is doing. That is, the engine starting method of the second embodiment is based on the prediction of the running pattern in the future. However, the engine starting method of the second embodiment can be executed based on the analysis of the current driving pattern without considering the prediction of the driving pattern in the future. In this case, for example, the engine starting method of the second embodiment may be implemented in consideration of only the operating point (1, m) in the time step st1 of FIG. As described above, when the engine starting method of the second embodiment is executed based on the analysis of the current traveling pattern, the operating point that minimizes the energy consumption is selected as the transition destination for each calculation cycle. Therefore, at least a semi-optimal transition pattern is adopted. As a result, the drive of the engine 13 is optimized to a state in which energy consumption is reduced.

Further, in the engine starting method of the second embodiment, it is premised that the conversion coefficient K is known, but even when the conversion coefficient K is not known, if the conversion coefficient K is used as a variable, the second embodiment The engine starting method according to the above can be implemented.

FIG. 15 is a flowchart showing an engine starting method with a conversion coefficient K as a variable when the engine starting method of the second embodiment is executed by the first method. The flowchart of FIG. 15 is a flowchart according to the first method (see FIG. 13) to which steps S301, S302, and S303 are added. Step S301 is inserted, for example, between step S201 and step S202, and in step S301, the initial value of the conversion coefficient K is set. Step S302 is inserted between steps S215 and S216, and in step S302, as a result of determining the transition pattern using the initially set conversion coefficient K, whether or not the SOC satisfies the constraint (hereinafter referred to as SOC constraint) is determined. judge. Then, when the transition pattern determined by using the default conversion coefficient K satisfies the SOC constraint, an instruction of the operating point according to the determined transition pattern is output as in the second embodiment described above. On the other hand, when it is determined in step S302 that the SOC constraint is not satisfied, the conversion coefficient K is adjusted in the direction of satisfying the SOC constraint in step S303, and then the total equivalent fuel consumption FC _eq-all is calculated until the SOC constraint is satisfied. And the determination of the transition pattern are repeated.

The SOC constraint is a constraint determined for the SOC by, for example, the characteristics of the battery 11 and the planning of the running pattern (running plan). For example, when it is necessary to keep the SOC above a predetermined value after traveling in a predetermined section, this predetermined value becomes an SOC constraint. Further, the adjustment of the conversion coefficient K in step S303 is performed, for example, by adding or subtracting the value of the conversion coefficient K so as to satisfy the SOC constraint. The determination of the direction satisfying the SOC constraint (determination of whether to add or subtract the value) and the adjustment amount thereof are determined based on the relationship between the conversion coefficient K and the SOC.

The conversion coefficient K may be adjusted as described above after setting the initial value of the conversion coefficient K based on the vehicle information or the like as in the second embodiment. In this case, since the conversion coefficient K is optimized according to changes in the traveling pattern of the vehicle 100 and the like, the drive of the engine 13 is optimized to a state in which energy consumption is particularly reduced. Further, in this case, since the adjustment amount of the conversion coefficient K is small, the optimum conversion coefficient K can be reached quickly.

Further, in the above modification, when the engine starting method of the second embodiment is executed by the first method, the conversion coefficient K is used as a variable, but the engine starting method of the second embodiment is used by the second method. The conversion coefficient K can also be a variable when executing.

FIG. 16 is a flowchart showing an engine starting method with a conversion coefficient as a variable when the engine starting method of the second embodiment is executed by the second method. The flowchart of FIG. 16 is obtained by adding step S301, step S302, and step S303 to the flowchart according to the second method (see FIG. 14). The content of each of these added steps is the same as in the above-mentioned case in which the conversion coefficient K is used as a variable when the engine starting method of the second embodiment is executed by the first method.

In the engine starting method according to the modification of FIGS. 15 and 16 above, the conversion coefficient K is made variable according to the current running pattern and / or the future running pattern, and the equivalent fuel consumption FC _eq is set to the motoring rotation speed. It is calculated by iterative calculation that changes "r" and the conversion coefficient K.

By making the conversion coefficient K variable as well as the motoring rotation speed in this way, the engine starting method of the second embodiment can be executed even when the conversion coefficient K is unknown. Further, even when the conversion coefficient K is generally known, the drive of the engine 13 is optimized to a state in which energy consumption is particularly reduced according to a more realistic traveling pattern.

Further, in the engine starting method according to the modification of FIG. 15, the conversion coefficient K is set to a predetermined initial value according to the current traveling pattern and / or the future traveling pattern. Then, using the conversion coefficient K of this initial value, the basic equivalent fuel consumption FC _eq-basic , which is the equivalent fuel consumption required for the transition, is calculated for each operating point (i, j) of the engine 13 that can be transitioned. .. In addition, the transition pattern of the operating points (i, j) determined in time series is determined so that the sum of the basic equivalent fuel consumption FC _eq-basic is minimized. Then, when the transition to the operating point (i, j) accompanied by the start of the engine 13 is included in this transition pattern, the operating point (i, j) accompanied by the start of the engine 13 is used by using the conversion coefficient K of the initial value. Regarding the transition to j), a plurality of equivalent fuel consumption FC _eq- starts at the time of starting, which are equivalent fuel consumption FC _eq related to the start of the engine 13, are calculated by changing the motoring rotation speed “r”. Then, the optimum motoring rotation speed is determined by the motoring rotation speed when the equivalent fuel consumption FC _eq-start at the start is minimized. After that, when the engine 13 is operated according to the transition pattern, it is determined whether or not the constraint imposed on the charge rate (SOC) of the battery 11 is satisfied, and when it is determined that the constraint is not satisfied, the conversion coefficient K is determined. Is changed and the iterative calculation is performed to redetermine the transition pattern.

Thus, when the engine starting method of the second embodiment is executed by the first method, if the conversion coefficient K is made variable, the advantage of the first method is enjoyed and the SOC is imposed. The drive of the engine 13 is optimized to reduce energy consumption while satisfying the constraints.

Further, in the engine starting method according to the modification of FIG. 16, the conversion coefficient K is set to a predetermined initial value according to the current traveling pattern and / or the future traveling pattern. Then, using the conversion coefficient K of this initial value, the basic equivalent fuel consumption FC _eq-basic , which is the equivalent fuel consumption FC _eq required for the transition, is calculated for each operating point (i, j) of the engine 13 that can be transitioned. Will be done. Further, when the transition of the operating point (i, j) is accompanied by the start of the engine 13, the conversion coefficient K of the initial value is used for the transition to the operating point (i, j) accompanied by the start of the engine 13. A plurality of equivalent fuel consumption FC _eq- starts at the time of starting, which are equivalent fuel consumption FC _eq related to the start of 13, are calculated by changing the motoring rotation speed “r”. At this time, the optimum motoring rotation speed is determined by the motoring rotation speed that minimizes the FC _eq-start equivalent fuel consumption at the start for each transition to the operating point (i, j) accompanied by the start of the engine 13. .. Further, for each transition pattern of the operating point (i, j) determined in time series, the basic equivalent fuel consumption FC _eq-basic and the equivalent fuel consumption FC _eq- at the time of starting when the engine 13 is started at the optimum motoring speed. By adding _start and, the total equivalent fuel consumption FC _eq-all is calculated. Then, the transition pattern to be executed is determined so that the total equivalent fuel consumption FC _eq-all is minimized. Further, when the engine 13 is operated according to the transition pattern, it is determined whether or not the constraint imposed on the charge rate (SOC) of the battery 11 is satisfied. When it is determined that the constraint is not satisfied, the iterative calculation is performed so as to change the conversion coefficient K and redetermine the transition pattern.

Thus, when the engine starting method of the second embodiment is executed by the second method, if the conversion coefficient K is made variable, the advantage of the second method is enjoyed and the SOC is imposed. The drive of the engine 13 is optimized to reduce energy consumption while satisfying the constraints.

Although the embodiments of the present invention have been described above, the configurations described in the above-described embodiments and the modifications thereof are only a part of the application examples of the present invention, and are intended to limit the technical scope of the present invention. do not have.

10: Motor 11: Battery 12: Generator 13: Engine 14: Auxiliary machine 20: Controller 21: Driving pattern analysis unit 22: SOC calculation unit 23: Starting profile switching unit

Claims (10)

When executed in a vehicle having a motor that generates driving force by electric power supplied from a battery, a generator that generates electric power supplied to the battery, and an engine that drives the generator, when the engine is started. An engine start control method for reaching a target operating point of the engine by driving the engine with fuel after motorizing the engine using the generator.
The engine is started by either a low rotation start in which the motoring rotation speed, which is the rotation speed of the engine reached by the motoring, is set low, or a high rotation start in which the motoring rotation speed is set high.
Based on the analysis of the current driving pattern of the vehicle, the charge rate of the battery is calculated for a predetermined time section related to control.
When the charge rate of the battery in the predetermined section becomes higher than a predetermined value, the engine is started in the predetermined section by the high rotation start.
When the charge rate of the battery in the predetermined section becomes lower than the predetermined value, the engine is started in the predetermined section by the low rotation start.
Engine start control method. The engine start control method according to claim 1.
Predicting the future driving pattern of the vehicle,
The charge rate of the battery in the predetermined section is calculated based on the prediction of the driving pattern in the future in addition to the analysis of the current driving pattern.
When it is predicted that the charge rate of the battery in the predetermined section will increase more than the predetermined value, the engine in the predetermined section is started by the high rotation start.
When the charge rate of the battery in the predetermined section is predicted to be lower than the predetermined value, the engine is started in the predetermined section by the low rotation start.
Engine start control method. The engine start control method according to claim 2.
The charge rate of the battery in the predetermined section is represented by a conversion coefficient that equivalently converts the power consumption of the battery to the consumption of the fuel.
Using the conversion coefficient, the equivalent fuel consumption obtained by converting the energy consumption obtained by combining the power consumption and the fuel consumption into the fuel consumption is calculated.
The motoring speed is determined under the condition of minimizing the equivalent fuel consumption.
Engine start control method. The engine start control method according to claim 3.
By changing the motoring speed, a plurality of the equivalent fuel consumptions are calculated.
Based on the plurality of calculated equivalent fuel consumptions, the optimum motoring rotation speed, which is the motoring rotation speed when the equivalent fuel consumption is minimized, is determined.
When starting the engine, the engine is motorized to the optimum motoring speed.
Engine start control method. The engine start control method according to claim 4.
The basic equivalent fuel consumption, which is the equivalent fuel consumption required for the transition, is calculated for each operating point of the engine that can transition in the predetermined section.
The transition pattern of the operating point determined in time series is determined so that the sum of the basic equivalent fuel consumption is minimized.
When the transition pattern includes a transition to the operating point accompanied by the start of the engine, the transition to the operating point accompanied by the start of the engine is a start that is the equivalent fuel consumption related to the start of the engine. Multiple time-equivalent fuel consumptions are calculated by changing the motoring speed.
The optimum motoring speed is determined by the motoring speed when the equivalent fuel consumption at the start is minimized.
Engine start control method. The engine start control method according to claim 4.
The basic equivalent fuel consumption, which is the equivalent fuel consumption required for the transition, is calculated for each operating point of the engine that can transition in the predetermined section.
When the transition of the operating point is accompanied by the start of the engine, for the transition to the operating point accompanied by the start of the engine, the equivalent fuel consumption at the time of starting, which is the equivalent fuel consumption related to the start of the engine, is set to the motor. Multiple calculations by changing the ring rotation speed,
The optimum motor rotation speed is determined by the motoring rotation speed that minimizes the equivalent fuel consumption at the time of starting each transition to the operating point accompanied by the start of the engine.
Comprehensive equivalent by adding the basic equivalent fuel consumption and the starting equivalent fuel consumption when starting the engine at the optimum motoring speed for each transition pattern of the operating point determined in time series. Calculate fuel consumption,
The transition pattern to be performed is determined so that the total equivalent fuel consumption is minimized.
Engine start control method. The engine start control method according to claim 4.
The conversion coefficient is made variable according to the current running pattern and / or the future running pattern.
The equivalent fuel consumption is calculated by iterative calculation in which the motoring speed and the conversion coefficient are changed.
Engine start control method. The engine start control method according to claim 7.
The conversion coefficient is set to a predetermined initial value according to the current driving pattern and / or the future driving pattern.
Using the conversion coefficient of the initial value, the basic equivalent fuel consumption, which is the equivalent fuel consumption required for the transition, is calculated for each operating point of the engine that can be transitioned.
The transition pattern of the operating point determined in time series is determined so that the sum of the basic equivalent fuel consumption is minimized.
When the transition pattern includes a transition to the operating point accompanied by the start of the engine, the engine is used for the transition to the operating point accompanied by the start of the engine by using the conversion coefficient of the initial value. The equivalent fuel consumption at the time of starting, which is the equivalent fuel consumption related to the start of the engine, is calculated by changing the motoring rotation speed.
The optimum motoring speed is determined by the motoring speed when the equivalent fuel consumption at the start is minimized.
When operating the engine according to the transition pattern, it is determined whether or not the constraint imposed on the charge rate of the battery is satisfied.
When it is determined that the constraint is not satisfied, the iterative calculation is performed so as to change the conversion coefficient and redetermine the transition pattern.
Engine start control method. The engine start control method according to claim 7.
The conversion coefficient is set to a predetermined initial value according to the current driving pattern and / or the future driving pattern.
Using the conversion coefficient of the initial value, the basic equivalent fuel consumption, which is the equivalent fuel consumption required for the transition, is calculated for each operating point of the engine that can be transitioned.
When the transition of the operating point is accompanied by the start of the engine, the equivalent fuel consumption related to the start of the engine is used for the transition to the operating point accompanied by the start of the engine by using the conversion coefficient of the initial value. The equivalent fuel consumption at the time of starting, which is, is calculated by changing the motoring rotation speed.
The optimum motor rotation speed is determined by the motoring rotation speed that minimizes the equivalent fuel consumption at the time of starting each transition to the operating point accompanied by the start of the engine.
Comprehensive equivalent by adding the basic equivalent fuel consumption and the starting equivalent fuel consumption when starting the engine at the optimum motoring speed for each transition pattern of the operating point determined in time series. Calculate fuel consumption,
The transition pattern to be executed is determined so that the total equivalent fuel consumption is minimized.
When operating the engine according to the transition pattern, it is determined whether or not the constraint imposed on the charge rate of the battery is satisfied.
When it is determined that the constraint is not satisfied, the iterative calculation is performed so as to change the conversion coefficient and redetermine the transition pattern.
Engine start control method. Provided in a vehicle having a motor that generates driving force by electric power supplied from a battery, a generator that generates electric power to be supplied to the battery, and an engine that drives the generator, when the engine is started. An engine start control device that controls an engine to reach a target operating point of the engine by driving the engine with fuel after motorizing the engine using the generator.
The engine is started by either a low rotation start in which the motoring rotation speed, which is the rotation speed of the engine reached by the motoring, is set low, or a high rotation start in which the motoring rotation speed is set high.
Based on the analysis of the current driving pattern of the vehicle, the charge rate of the battery is calculated for a predetermined time section related to control.
When the charge rate of the battery in the predetermined section becomes higher than a predetermined value, the engine is started in the predetermined section by the high rotation start.
When the charge rate of the battery in the predetermined section becomes lower than the predetermined value, the engine is started in the predetermined section by the low rotation start.
Engine start control device.

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