Abstract:
A regeneration control device of a hybrid vehicle detects brake fluid pressure for detecting the amount of engagement of the brakes of the hybrid vehicle, and performs a first regeneration control in a closed state of the accelerator and the brake pedal not being depressed, a second regeneration control in the closed state of the accelerator and the brake pedal being depressed, and a third regeneration control when the accelerator pedal is in the closed state and the brake fluid pressure exceeds a predetermined value, wherein X(Nm/s) is set as the rate of increase of regenerative torque in the first regeneration control, Y(Nm/s) is set as the rate of increase of regenerative torque in the second regeneration control, and Z(Nm/s) is set as the rate of increase of regenerative torque in the third regeneration control, then X&lt;y&lt;Z is satisfied.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a U.S. national stage of application No. PCT/JP2011/074157, filed on Oct. 20, 2011. Priority under 35 U.S.C. §119(a) and 35 U.S.C. §365(b) is claimed from Japanese Patent Application No. 2010-236607, filed on Oct. 21, 2010, the disclosure of which are also incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention relates to a regeneration control device, a hybrid vehicle, a regeneration control method, and a computer program. 
     BACKGROUND ART 
     A hybrid vehicle includes an engine and an electric motor and is capable of running by the engine or the electric motor, or is capable of running by the cooperation between the engine and the electric motor. During the deceleration of the hybrid vehicle, the electric motor can regenerate electric power. When the regenerative power generation is performed, regeneration torque is generated at the electric motor. The regeneration torque becomes the friction against the run of the hybrid vehicle and works as braking force similarly to the engine breaking. (for example, see patent literature PTL1). 
     CITATION LIST 
     Patent Literature 
     
         
         PTL1: JP 2007-223421 A 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     As described above, the regeneration torque generated by the electric motor works as the braking force for the hybrid vehicle. In a conventional hybrid vehicle, the magnitude of the regeneration torque varies in two steps depending on whether the driver depresses the brake pedal (in other words, whether the brake lights are lighted). For example, the magnitude of the regeneration torque varies between a state in which the accelerator is closed and the brake pedal is not depressed and a state in which the accelerator is closed and the brake pedal is depressed. 
     In such a control of the regeneration torque, the regeneration torque is switched to large regeneration torque even if the driver only slightly puts the driver&#39;s foot on the brake pedal. At that time, the driver feels the braking force more than the driver has required and then, for example, accelerates the vehicle again with depressing the accelerator pedal. This lowers the fuel efficiency. Further, in terms of the drivability of the driver, it is unfavorable that the driver feels the braking force more than the driver has required. 
     Once the driver gets used to the drivability in which only slightly putting the driver&#39;s foot on the brake pedal generates large braking force, the driver tends to refrain from a brake operation until large braking force is required. As a result, the driver would slightly depress the brake pedal less frequently and deeply depresses the brake pedal more frequently. This reduces the amount of regeneration because there is not time enough for regenerating electric power and a desired deceleration is more frequently accomplished only at the friction brake side. 
     In light of the foregoing, an objective of the present invention is to provide a regeneration control device, a hybrid vehicle, a regeneration control method, and a computer program that can secure the amount of regeneration without detracting from the driver&#39;s drivability. 
     Solution to Problem 
     An aspect of the present invention is directed to a regeneration control device. The regeneration control device of a hybrid vehicle that includes an engine and an electric motor, that is capable of running by the engine or the electric motor or capable of running by a cooperation between the engine and the electric motor, and that is capable of performing regenerative power generation with the electric motor at least during deceleration, the regeneration control device includes detection means for detecting a performance of a brake of the hybrid vehicle, wherein the regeneration control device performs a first regeneration control that is performed in a state in which an accelerator of the hybrid vehicle is in a closed state and a brake pedal is not depressed, a second regeneration control that is performed in a state in which the accelerator of the hybrid vehicle is in the closed state and the brake pedal is depressed, and a third regeneration control that is performed when the accelerator of the hybrid vehicle is in the closed state and a detection result from the detection means exceeds a predetermined value, and X&lt;Y&lt;Z is provided when an increase rate of regeneration torque in the first regeneration control is set at X(Nm/s), an increase rate of regeneration torque in the second regeneration control is set at Y(Nm/s), and an increase rate of regeneration torque in the third regeneration control is set at Z(Nm/s). 
     Another aspect of the present invention is directed to a hybrid vehicle. The hybrid vehicle includes the regeneration control device according to the aspect of the present invention. 
     A further aspect of the present invention is directed to a regeneration control method. The regeneration control method of a hybrid vehicle that includes an engine and an electric motor, that is capable of running by the engine or the electric motor or capable of running by a cooperation between the engine and the electric motor, and that is capable of performing regenerative power generation with the electric motor at least during deceleration, the regeneration control method includes: a first regeneration step that is performed in a state in which an accelerator of the hybrid vehicle is in a closed state and a brake pedal is not depressed; a second regeneration step that is performed in a state in which the accelerator of the hybrid vehicle is in the closed state and the brake pedal is depressed; and a third regeneration step that is performed when the accelerator of the hybrid vehicle is in the closed state and a detection result from the detection means exceeds a predetermined value, wherein X&lt;Y&lt;Z is provided when an increase rate of regeneration torque in the first regeneration step is set at X(Nm/s), an increase rate of regeneration torque in the second regeneration step is set at Y(Nm/s), and an increase rate of regeneration torque in the third regeneration step is set at Z(Nm/s). 
     A further aspect of the present invention is a computer program. The computer program causes an information processing apparatus to implement a function of the regeneration control device according to the aspect of the present invention. 
     Advantageous Effects of Invention 
     The present invention can secure the amount of regeneration without detracting from the driver&#39;s drivability. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram for illustrating an exemplary structure of a hybrid vehicle according to an embodiment of the present invention. 
         FIG. 2  is a block diagram for illustrating an exemplary configuration of a function implemented in a hybrid ECU illustrated in  FIG. 1 . 
         FIG. 3  is a flowchart for illustrating a process for controlling regeneration by a regeneration control unit illustrated in  FIG. 2 . 
         FIG. 4  is a view for describing, with the time course, the variations of the brake fluid pressure and the regeneration torque in the process of the regeneration control in the regeneration control unit illustrated in  FIG. 2 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, the hybrid vehicle according to an embodiment of the present invention will be described with reference to  FIGS. 1 to 4 . 
       FIG. 1  is a block diagram for illustrating an exemplary structure of a hybrid vehicle  1 . The hybrid vehicle  1  is an example of a vehicle. The hybrid vehicle  1  is driven by an engine (internal combustion engine)  10  and/or an electric motor  13  through a gear box that is an automated mechanical/manual transmission. For example, when the hybrid vehicle decelerates, the electric motor  13  can regenerate electric power. Without detracting from the driver&#39;s drivability, the hybrid vehicle  1  can coordinate the braking force caused by the brake operation by the driver during deceleration with the braking force caused by the regeneration torque of the electric motor  13 . Note that the automated mechanical/manual transmission is a transmission that can automatically shift the gears while having the same structure as a manual transmission. 
     The hybrid vehicle  1  includes the engine  10 , an engine Electronic Control Unit (ECU)  11 , a clutch  12 , the electric motor  13 , an inverter  14 , a battery  15 , a transmission  16 , a motor ECU  17 , a hybrid ECU  18 , a wheel  19 , a key switch  20  and a shift unit  21 . Note that the transmission  16  includes the above-mentioned automated mechanical/manual transmission, and is operated by the shift unit  21  including a drive range (hereinafter, referred to as a D (Drive) range). 
     The engine  10  is an example of an internal combustion engine, and is controlled by the engine ECU  11 . The engine  10  internally combusts gasoline, light oil, Compressed Natural Gas (CNG), Liquefied Petroleum Gas (LPG), alternative fuel, or the like in order to generate power for rotating a shaft and transmit the generated power to the clutch  12 . 
     The engine ECU  11  is a computer working in coordination with the motor ECU  17  according to the instructions from the hybrid ECU  18 , and controls the engine  10 , for example, the amount of fuel injection and the valve timing. For example, the engine ECU  11  includes a Central Processing Unit (CPU), an Application Specific Integrated Circuit (ASIC), a microprocessor (microcomputer), a Digital Signal Processor (DSP), and the like, and internally has an operation unit, a memory, an Input/Output (I/O) port, and the like. 
     The clutch  12  is controlled by the hybrid ECU  18 , and transmits the shaft output from the engine  10  to the wheel  19  through the electric motor  13  and the transmission  16 . In other words, the clutch  12  mechanically connects the rotating shaft of the engine  10  to the rotating shaft of the electric motor  13  by the control of the hybrid ECU  18  in order to transmit the shaft output of the engine  10  to the electric motor  13 . On the other hand, the clutch  12  cuts the mechanical connection between the rotating shaft of the engine  10  and the rotating shaft of the electric motor  13  so that the shaft of the engine  10  and the rotating shaft of the electric motor  13  can rotate at different rotational speeds from each other. 
     For example, the clutch  12  mechanically connects the rotating shaft of the engine  10  to the rotating shaft of the electric motor  13 , for example, when the hybrid vehicle  1  runs by the power of the engine  10  and this causes the electric motor  13  to generate electric power, when the driving force of the electric motor  13  assists the engine  10 , and when the electric motor  13  starts the engine  10 . 
     Further, for example, the clutch  12  cuts the mechanical connection between the rotating shaft of the engine  10  and the rotating shaft of the electric motor  13  when the engine  10  stops or is in an idling state and the hybrid vehicle  1  runs by the driving force of the electric motor  13 , and when the hybrid vehicle  1  reduces the speed or runs on the downgrade and the electric motor  13  generates (regenerates) electric power while the engine  10  stops or is in an idling state. 
     Note that the clutch  12  differs from the clutch operated by the driver&#39;s operation of a clutch pedal, and is operated by the control of the hybrid ECU  18 . 
     The electric motor  13  is a so-called motor generator that supplies a shaft output to the transmission  16  by generating the power for rotating the shaft using the electric power supplied from the inverter  14 , or that supplies electric power to the inverter  14  by generating the electric power using the power for rotating the shaft supplied from the transmission  16 . For example, when the hybrid vehicle  1  gains the speed or runs at a constant speed, the electric motor  13  generates the power for rotating the shaft to supply the shaft output to the transmission  16  in order to cause the hybrid vehicle  1  to run in cooperation with the engine  10 . Further, the electric motor  13  works as an electric generator, for example, when the electric motor  13  is driven by the engine  10 , or when the hybrid vehicle  1  runs without power, for example, when the hybrid vehicle  1  reduces the speed or runs on the downgrade. In that case, electric power is generated by the power for rotating the shaft supplied from the transmission  16  and is supplied to the inverter  14  in order to charge the battery  15 . 
     The inverter  14  is controlled by the motor ECU  17 , and converts the direct voltage from the battery  15  into an alternating voltage or converts the alternating voltage from the electric motor  13  into a direct voltage. When the electric motor  13  generates power, the inverter  14  converts the direct voltage from the battery  15  into an alternating voltage and supplies the electric power to the electric motor  13 . When the electric motor  13  generates electric power, the inverter  14  converts the alternating voltage from the electric motor  13  into a direct voltage. In other words, in that case, the inverter  14  works as a rectifier and a voltage regulator for supplying a direct voltage to the battery  15 . 
     Note that the magnitude of the regeneration torque of the electric motor  13  is proportional to the magnitude of the current flowing in a coil (not illustrated in the drawings) of the electric motor  13 . Thus, by regulating the amount of the current when the inverter  14  supplies the direct voltage to the battery  15 , the magnitude of the regeneration torque of the electric motor  13  can be regulated. 
     The battery  15  is a secondary cell capable of being charged and discharged. The battery  15  supplies electric power to the electric motor  13  through the inverter  14  when the electric motor  13  generates power. Alternatively, the battery  15  is charged with the electric power generated by the electric motor  13  when the electric motor  13  generates electric power. 
     The transmission  16  includes an automated mechanical/manual transmission (not shown in the drawings) that selects one of a plurality of gear ratios (change gear ratios) according to the shift instruction signal from the hybrid ECU  18  in order to shift the change gear ratios and transmit the gear-shifted power of the engine  10  and/or the power of the electric motor  13  to the wheel  19 . Alternatively, the transmission  16  transmits the power from the wheel  19  to the electric motor  13 , for example, when the vehicle reduces the speed or runs on the downgrade. Note that the automated mechanical/manual transmission can also shift the gear position to a given gear number by the driver&#39;s hand operation of the shift unit  21 . 
     The motor ECU  17  is a computer working in coordination with the engine ECU  11  according to the instructions from the hybrid ECU  18 , and controls the electric motor  13  by controlling the inverter  14 . For example, the motor ECU  17  includes a CPU, an ASIC, a microprocessor (microcomputer), a DSP, and the like, and internally has an operation unit, a memory, an I/O port, and the like. 
     The hybrid ECU  18  is an example of a computer. For hybrid driving, the hybrid ECU  18  obtains accelerator opening amount information, brake operation information, vehicle speed information, brake fluid pressure information, the gear position information obtained from the transmission  16 , and the engine rotational speed information obtained from the engine ECU  11  in order to refer to the information, resultantly control the clutch  12  and supply the shift instruction signal in order to control the transmission  16 . For hybrid driving, the hybrid ECU  18  further gives the instruction to the motor ECU  17  to control the electric motor  13  and the inverter  14  based on the obtained State of Charge (SOC) information on the battery  15  and other information, and gives the instruction to the engine ECU  11  to control the engine  10 . For example, the hybrid ECU  18  includes a CPU, an ASIC, a microprocessor (microcomputer), a DSP, and the like, and internally has an operation unit, a memory, an I/O port, and the like. 
     Note that a computer program to be executed by the hybrid ECU  18  can be installed on the hybrid ECU  18  that is a computer in advance by being stored in a non-volatile memory inside the hybrid ECU  18  in advance. 
     The engine ECU  11 , the motor ECU  17 , and the hybrid ECU  18  are connected to each other, for example, through a bus complying with the standard of the Control Area Network (CAN) or the like. 
     The wheel  19  is a drive wheel for transmitting the driving force to the road surface. Note that, although only a wheel  19  is illustrated in  FIG. 1 , the hybrid vehicle  1  actually includes a plurality of the wheels  19 . 
     The key switch  20  is a switch that is turned ON/OFF, for example, by insertion of a key by the user at the start of drive. Turning ON the switch activates each unit of the hybrid vehicle  1 , and turning OFF the key switch  20  stops each unit of the hybrid vehicle  1 . 
       FIG. 2  is a block diagram for illustrating an exemplary configuration of a function implemented in the hybrid ECU  18  executing a computer program. In other words, when the hybrid ECU  18  executes a computer program, the functions of a regeneration control unit  30  and a brake fluid pressure criterion value storage unit  31  are implemented. 
     The regeneration control unit  30  instructs the motor ECU  14  to perform regeneration based on the accelerator opening amount information, the brake operation information, and the brake fluid pressure information. The brake fluid pressure criterion value storage unit  31  is implemented by allotting the region in a part of the memory included in the hybrid ECU  18  thereto, and storages a brake fluid pressure criterion value that has been generated by the regeneration control unit  30  based on the brake operation information and the brake fluid pressure information. 
     Next, the process for the regeneration control performed in the hybrid ECU  18  executing the computer program will be described with reference to the flowchart illustrated in  FIG. 3 . Note that the procedures in  FIG. 3  are a cycle of the process, and the process is repeatedly performed as long as the key switch  20  is the ON state. Note that it is assumed in the below description that the hybrid vehicle  1  runs while regenerating electric power with the electric motor  13  without an accelerator operation. At that time, the clutch  12  can be in any state. For example, the clutch  12  can be disengaged while the electric motor  13  regenerates electric power, or the clutch  12  can be engaged while the engine braking of the engine  10  and the regeneration torque caused by the regeneration by the electric motor  13  work as braking force. 
     In the “START” illustrated in  FIG. 3 , the hybrid ECU  18  has executed a computer program, and the regeneration control unit  30  and the brake fluid pressure criterion value storage unit  31  are implemented by the hybrid ECU  18 . Then, the process goes to step S 1 . 
     In step S 1 , the regeneration control unit  30  determines whether a brake operation is performed. When it is determined that a brake operation is performed, the process goes to step S 2 . On the other hand, when it is determined in step S 1  that a brake operation is not performed, the process goes to step S 4 . 
     In step S 2 , the regeneration control unit  30  calculates the increase rate of the brake fluid pressure and determines whether the increase rate is equal to or less than A %. The increase rate of the brake fluid pressure is the rate of increasing from the brake fluid pressure at the time when a brake operation is not performed being stored in step S 4  described below to the brake fluid pressure immediately after the brake has been operated. When it is determined in step S 2  that the increase rate of the brake fluid pressure is equal to or less than A %, the process goes to step S 3 . On the other hand, when it is determined in step S 2  that that the increase rate of the brake fluid pressure exceeds A %, the process goes to step S 7 . Note that the A % is set, for example, at 12 to 13%. 
     In step S 3 , the regeneration control unit  30  performs regeneration at a “moderate regeneration rate”, and terminates a cycle of the process. Note that the “moderate regeneration rate” will be described in detail below. 
     In step S 4 , the regeneration control unit  30  stores the brake fluid pressure at the time when the brake operation is not performed as the standard value in the brake fluid pressure standard value storage unit  31 . Then, the process goes to step S 5 . 
     In step S 5 , the regeneration control unit  30  determines whether an accelerator operation is performed. When it is determined that an accelerator operation is not performed, the process goes to step S 6 . On the other hand, when it is determined in step S 5  that an accelerator operation is performed, the process goes back to step S 1 . 
     In step S 6 , the regeneration control unit  30  performs regeneration at a “low regeneration rate”, and terminates a cycle of the process. Note that the “low regeneration rate” will be described in detail below. 
     In step S 7 , the regeneration control unit  30  performs regeneration at a “high regeneration rate”, and terminates a cycle of the process. Note that the “high regeneration rate” will be described in detail below. 
       FIG. 4  is a view for describing, with the time course, the variations of the fluid pressure of the brake and the regeneration torque in the process of the regeneration control in the regeneration control unit  30 . The brake fluid pressure becomes larger from the bottom of the drawing to the top. The regeneration torque becomes larger from the top of the drawing to the bottom. The brake fluid pressure is the pressure of the brake oil in a brake master cylinder (not illustrated in the drawings), and varies depending on the atmospheric pressure, the temperature, or the like at that time (for example, around 9 to 10%). Thus, the brake fluid pressure at the time when a brake operation is not performed cannot be set as a predetermined fixed value. In light of the foregoing, as illustrated in  FIG. 4 , the regeneration control unit  30  stores the brake fluid pressure at the time when a brake operation is not performed as the standard value in the brake fluid pressure standard value storage unit  31  while momentarily updating the standard value (step S 4 ). 
     While the accelerator is in the ON state (term T 1 ), operating the accelerator accelerates the hybrid vehicle  1 . Thus, the regeneration by the electric motor  13  is not performed. Note that, for example, when the SOC of the battery  15  decreases, the electric motor  13  sometimes performs regeneration as an electric generator with the output from the engine  10  even if the hybrid vehicle  1  accelerates. However, such a case is not taken into consideration herein. 
     Here, while the accelerator operation is not performed (the accelerator is in the closed state) (term T 2 ), the regeneration is performed at the “low regeneration rate”. In the regeneration at the “low regeneration rate”, the regeneration torque is minimized. For example, the regeneration torque that increases at an increase rate of about a newton meter per second (□Nm/s) is generated. This gradually increases the deceleration of the hybrid vehicle  1 . 
     Here, when a brake operation is performed (it is illustrated as BRAKE ON in the drawing) (term T 3 ), the regeneration is performed at the “moderate regeneration rate”. In the regeneration at the “moderate regeneration rate”, for example, the regeneration torque that increases at an increase rate of about two newton meters per second (□Nm/s) is generated. This causes the hybrid vehicle  1  to run at a deceleration in which the braking force works more because of the increased regeneration torque in addition to the braking force caused by the service brake. 
     Then, the brake operation is further operated. When the increase rate of the brake fluid pressure at that time is equal to or more than A % (term T 4 ), the regeneration is performed at the “high regeneration rate”. The regeneration at the “high regeneration rate” is regeneration with the maximum regeneration torque, and the regeneration torque is generated at the maximum rate. This causes the hybrid vehicle  1  to run at the maximum deceleration in which the braking force caused by the regeneration torque strongly works in addition to the braking force caused by the service brake. Note that a rate is not set as the maximum rate. The maximum rate occurs in a state in which the rate happens to increase according to the characteristics of the electric motor  13 , the inverter  14  and the like. 
     Note that the regeneration torque in a conventional regeneration control is illustrated as a comparison example with a broken line in  FIG. 4 . In the prior art, the regeneration torque has happened to increase to the maximum regeneration torque without a set increase rate (in other words, at the above-mentioned maximum rate) as soon as a brake operation has been performed. 
     Effects 
     Performing the regeneration at the “low regeneration rate” in which the accelerator is in the closed state and the brake pedal is not depressed, performing the regeneration at the “moderate regeneration rate” in which the brake pedal is depressed even if only slightly, and performing the regeneration at the “high regeneration rate” in which the brake fluid pressure increases by more than A %, the hybrid vehicle  1  can secure the amount of regeneration without detracting from the driver&#39;s drivability. In the example of the prior art illustrated as a comparison example in  FIG. 4 , even if the driver only slightly performs a brake operation, the regeneration torque would rapidly increase. This brings an uncomfortable feeling about the drivability to the driver. However, the control by the regeneration control unit  30  according to an embodiment of the present invention rarely brings an uncomfortable feeling about the drivability to the driver. 
     Further, the increase in the brake fluid pressure is determined while compared with the brake fluid pressure at the time when the brake pedal is not depressed, so that an appropriate regeneration rate can constantly be set even if the atmospheric pressure or the temperature varies. 
     Other Embodiments 
     Although the value of A that is a threshold of the increase rate of the brake fluid pressure has been described as a fixed value in the above-mentioned embodiment, the value of the A can variably be set. For example, when the SOC of the battery  15  is high and the battery  15  cannot be charged any more, the threshold A is set at a relatively large value. This can prevent the value indicating the SOC from increasing by reducing the electric power to be generated by the electric motor  13  because the “high regeneration rate” occurs only when the brake pedal is strongly depressed. Note that the regeneration control unit  30  can automate the switch of the threshold A by detecting the value indicating the SOC of the battery  15 . 
     Alternatively, when the gross weight of the hybrid vehicle  1  is relatively large, or when the angle of the downgrade of the road surface on which the hybrid vehicle  1  runs is relatively large, it is favorable that a relatively large deceleration is obtained because it is difficult for the hybrid vehicle  1  to decelerate. In such a case, the regeneration rate is changed to a rapid rate (in other words, the inclination angle of the regeneration rate is increased). One or some of the low regeneration rate, the moderate regeneration rate, and the high regeneration rate can be changed. For example, the term T 3  at the moderate regeneration rate is longer than that at the low regeneration rate, the high regeneration rate, or the like. Thus, the deceleration obtained by changing only the value of the moderate generation rate to a rapid rate becomes large. Further, a large deceleration can be obtained as soon as the accelerator gets into the OFF state also by changing the value of the low regeneration rate to a rapid rate together with the value of the moderate regeneration rate. Alternatively, the feeling of deceleration at the time when the accelerator is turned OFF can be obtained by changing only the value of the low regeneration rate to a rapid rate. 
     This facilitates a large deceleration because the deceleration relative to the depressed amount of the brake pedal increases. This brings a sufficient feeling of deceleration to the driver and thus can contribute to the improvement of the drivability. Note that the switch of the regeneration rate may be performed by the driver&#39;s hand operation according to the amount of cargo loaded on the hybrid vehicle  1  or the degree of the inclination of the road surface, or may be automatically performed by detecting the gross weight of the hybrid vehicle  1  or the degree of the inclination of the road surface with the regeneration control unit  30 . The gross weight of the hybrid vehicle  1  can be found, for example, by measuring the load of the carrier using an axle load sensor provided on the axle. Alternatively, the gross weight of the hybrid vehicle  1  may also be estimated by checking the behavior of the running hybrid vehicle  1  (for example, see JP 2004-025956 A). Further, the inclination of the road surface on which the hybrid vehicle  1  runs can be found, for example, using an inclination sensor or the like. 
     The boundaries of the regions for determination may variously be changed, for example, the “equal to or more than” may be changed into “exceeds” and the “less than” may be changed into “equal to or less than” in the description of the above-mentioned flowchart. 
     Although the engine  10  has been described as an internal combustion engine, the engine  10  may also be a heat engine including an external combustion engine. 
     Further, while the computer program executed by the hybrid ECU  18  is installed on the hybrid ECU  18  in advance in the above-mentioned description, the computer program may be installed on the hybrid ECU  18  as a computer by attaching removable media recording the computer program (storing the computer program), for example, to a drive (not shown in the drawings) and storing the computer program read from the removable media in a non-volatile memory inside the hybrid ECU  18 , or receiving, with a communication unit (not shown in the drawings), a computer program transmitted through a wired or wireless transmission medium and storing the computer program in a non-volatile memory inside the hybrid ECU  18 . 
     Further, each ECU may be implemented by an ECU combining some or all of the functions of the ECUs. Alternatively, an ECU may newly be provided by the further subdivision of the function of each ECU. 
     Note that the computer program executed by the computer may be for performing the process in chronological order according to the order described herein or may be for performing the process in parallel or at the necessary timing, for example, when the computer program is invoked. 
     Further, the embodiments of the present invention are not limited to the above-mentioned embodiments, and may variously be modified without departing from the gist of the invention.