Abstract:
A battery supplies electric power to electric equipments of the vehicle. An alternator generates the electric power and charges the battery when an engine of the vehicle is operated. An economical running control section is operable to perform an economical running in which the engine is automatically stopped when the vehicle is in a predetermined engine stopping condition and the engine is automatically restarted when the vehicle is in a predetermined engine restarting condition. A calculate section is operable to calculate an available current value which is available to supply to the electric equipments from the battery. A feed limiting section is operable to limit to supply the electric power to the electric equipments from the battery. The economical running control section controls the economical running based on a total value of necessary current values which are necessary for the respective electric equipments and the available current value. The feed limiting section limits to supply the electric power to the electric equipments from the battery based on the total value of the necessary current values and the sum of the available current value and a generated current value of the alternator.

Description:
The disclosures of Japanese Patent Application No. 2006-012636 filed on Jan. 20, 2006 including specification, drawings and claims are incorporated herein by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to a vehicle control unit and a vehicle control method, and more particularly to a vehicle control unit and a vehicle control method for controlling a vehicle having a battery which supplies electric power to electric equipments of the vehicle and an alternator which generates the electric power and charges the battery when an engine of the vehicle is operated and an economical running control section operable to perform an economical running in which the engine is automatically stopped when the vehicle is in a predetermined engine stopping condition and the engine is automatically restarted when the vehicle is in a predetermined engine restarting condition. 
     There are vehicles on which an economical running system is installed. The economical running system is operable to perform the economical running in which the engine is automatically stopped when the vehicle is in a predetermined engine stopping condition and the engine is automatically restarted when the vehicle is in a predetermined engine restarting condition. 
     In addition, there are vehicles on which a plurality of electric equipments is installed. The electric equipments include accessories such as an on-board car audio system, and safety system units such as an ABS (Anti-Lock Braking System) for preventing the car from slip by sustained wheel-locking when the vehicle is suddenly braked or the vehicle is braked on a slippery road surface, a braking assist system for assisting a braking force so as to obtain a strong braking force when the vehicle is suddenly braked, and a pre-crash safety system in which a distance to an object from the vehicle is measured by a radar and when a collision is inevitable, the auxiliary brake is applied and occupants of the vehicle are restrained by retracting the seatbelts before the collision occurs. 
     In the above related-art vehicle, there is a vehicle on which a power supply management system is installed. When a current value which is supplied to the electric equipments becomes insufficient, the power supply management system performs a feed limitation on the accessories so as to securely feed to the safety system in view of safety. 
     In the power supply management system, for example, the consumption of the electric power by the electric equipments is equally suppressed in order to reduce the consumption of the electric power when an economical running is performed in a case where the charged level of the battery is low or the economical running is performed a number of times (refer, for example, to Japanese Patent Publication No. 2004-106621). When the economical running is performed, an engine of the vehicle is activated in a case where an ignition switch is on, the vehicle is in idling-stop state, and a predetermined condition is established is performed. 
     When the electric equipments such as the accessories and safety system units are used for a long period of time in a state that the engine is stopped and the alternator generates no current since the economical running is performed, the available current value of the battery is surely at a lower level than before the economical running is performed. Therefore, the feed limitation on the accessories other than the safety system units easily occurs at all times depending on the condition of the battery when the vehicle is restored to the normal state from the economical running state. 
     Here, when a feed limitation on the accessories is implemented due to the current value supplied to the electric equipments becoming insufficient, since the available current value that can be supplied to the electric equipments from the battery cannot be calculated accurately, the current value that can be so supplied is estimated lower. Therefore, the feed limitation on the accessories is implemented more than actually necessary. By such a feed limitation, the feed on the accessory on which the feed limitation did not actually have to be performed may be limited. Then, there is a problem that a reproduction of musing was stopped while the user was listening thereto, the conveniences of the user being thereby damaged. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the invention to provide a system and method of controlling a vehicle which can reduce the occurrence of feed limitation on the accessories. 
     In order to achieve the above described object, according to the invention, there is provided a vehicle control unit adapted to be mounted on a vehicle having a battery which supplies electric power to electric equipments of the vehicle and an alternator which generates the electric power and charges the battery when an engine of the vehicle is operated and an economical running control section operable to perform an economical running in which the engine is automatically stopped when the vehicle is in a predetermined engine stopping condition and the engine is automatically restarted when the vehicle is in a predetermined engine restarting condition, the vehicle control unit comprising: 
     a calculate section, operable to calculate an available current value which is available to supply to the electric equipments from the battery; and 
     a feed limiting section, operable to limit to supply the electric power to the electric equipments from the battery, wherein: 
     the economical running control section controls the economical running based on a total value of necessary current values which are necessary for the respective electric equipments and the available current value; and 
     the feed limiting section limits to supply the electric power to the electric equipments from the battery based on the total value of the necessary current values and the sum of the available current value and a generated current value of the alternator. 
     According to the invention, there is also provided a vehicle control method for controlling a vehicle having a battery which supplies electric power to electric equipments of the vehicle and an alternator which generates the electric power and charges the battery when an engine of the vehicle is operated and an economical running control section operable to perform an economical running in which the engine is automatically stopped when the vehicle is in a predetermined engine stopping condition and the engine is automatically restarted when the vehicle is in a predetermined engine restarting condition, the vehicle control method comprising: 
     calculating an available current value which is available to supply to the electric equipments from the battery; 
     controlling the economical running based on a total value of necessary current values which are necessary for the respective electric equipments and the available current value; and 
     limiting to supply the electric power to the electric equipments from the battery based on the total value of the necessary current values and the sum of the available current value and a generated current value of the alternator. 
     According to the invention, there is also provided a vehicle control unit adapted to be mounted on a vehicle having a battery which supplies electric power to electric equipments of the vehicle, the vehicle control unit comprising: 
     a priority table which indicates a priorities of the respective electric equipments in which the electric power is supplied to the respective electric equipments from the battery; 
     a feed limiting section, operable to limit to supply the electric power to the electric equipments from the battery based on the priority table. 
     According to the invention, there is also provided a vehicle control unit adapted to be mounted on a vehicle having a battery which supplies electric power to electric equipments of the vehicle and an alternator which generates the electric power and charges the battery when an engine of the vehicle is operated, the vehicle control unit comprising: 
     a calculate section, operable to calculate a generated voltage value of the alternator based on a revolution of the engine; 
     an acquiring section, operable to acquire a correction coefficient based on an internal resistance value of the battery; and 
     a correction section, operable to correct the generated voltage value based on the correction coefficient. 
     With the above configurations, the available current value which the battery can supply to the electric equipments is accurately calculated. Since the economical running is performed based on the available current value and a feed limitation to the electric equipments from the battery is performed based on the total value of the necessary current values and the available current value, an unreasonable feed limitation of the electric equipment other than the safety system units can be reduced, thereby making it possible to enhance the conveniences of the user. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above objects and advantages of the present invention will become more apparent by describing in detail preferred exemplary embodiments thereof with reference to the accompanying drawings, wherein: 
         FIG. 1  is a block diagram showing a system configuration of a vehicle control system according to an embodiment of the present invention; 
         FIG. 2  is a block diagram showing a hardware configuration of a vehicle control unit according to the embodiment; 
         FIG. 3  is a block diagram showing a functional configuration of the vehicle control unit; 
         FIG. 4  is a flowchart showing a calculating process of an available current value according to the embodiment; 
         FIG. 5  is a flowchart showing updating process of a battery internal resistance value according to the embodiment; 
         FIG. 6A  is a diagram showing the battery internal resistance value related to fluid temperature; 
         FIG. 6B  is a table showing the battery internal resistance values related to fluid temperatures; 
         FIG. 7  is a flowchart showing an economical running controlling process; 
         FIG. 8  is a flowchart showing a generation commanding process of issuing a generation command to an alternator; 
         FIG. 9  is a diagram showing an available-for-generation voltage value property relative to engine speed; 
         FIG. 10  is a diagram showing a correction coefficient property of an available-for-generation voltage value relative to the internal resistance value of the battery; 
         FIG. 11  is a diagram showing an output voltage value property relative to running conditions of a vehicle and the voltage value of the battery; 
         FIG. 12  is a flowchart showing a feed limiting process; 
         FIG. 13  is a diagram showing a priority table. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, an embodiment of the invention will be described in detail with reference to the accompanying drawings. 
     Firstly, a system configuration of a vehicle control system will be described. As shown in  FIG. 1 , a vehicle control system includes a vehicle control unit  10  having an economical running function, and an alternator  11  for generating an alternating current while an engine is in operation, a battery  12  for providing a power supply to electric equipments, safety system units  13 , accessories  14  and an electronic meter control unit  15  are connected to the vehicle control unit  10  via a power supply line  16 . The accessories  14  are connected to the power supply line  16  via switches  17  which can interrupt a power supply to the accessories  14 . In addition, the switches  17  and the electronic meter control unit  15  are connected to the vehicle control unit  10  via a signal line  18 . 
     A voltage sensor  19  for detecting a voltage and a current sensor  20  for detecting a current are provided on the alternator  11 , and output terminals of the voltage sensor  19  and the current sensor  20  are connected to the vehicle control unit  10 , although not so illustrated in the figure. In addition, a voltage sensor  21 , a current sensor  22  and a temperature sensor  23  for detecting a temperature are provided on the battery  12 , and although not so illustrated in the figure, output terminals of the voltage sensor  21 , the current sensor  22  and the temperature sensor  23  are connected to the vehicle control unit  10 . 
     The safety system units  13  and the accessories  14  are included in a plurality of electric equipments which are installed on a vehicle. The safety system units  13  are electric equipments which are related to the safety of the vehicle of the vehicle, and for example, electronic control units such as an engine control system and a brake control system are raised. The accessories  14  are the other pieces of electronic equipment than the safety system units  13 , and for example, a car audio system and a car navigation system are raised. 
     In this vehicle control unit  10 , an available current value which the battery  12  can supply to the electric equipments is calculated based on detection signals by the voltage sensor  21 , current sensor  22  and temperature sensor  23  of the battery  12 , and a determination on whether an economical running is permitted or prohibited, a calculation of a generation requiring current value that is to be generated by the alternator  11  and a feed limitation on the accessories  14  are implemented based on the available current value so calculated. 
     When a feed limitation on some of the accessories  14  is implemented, the corresponding switches  17  and the electronic meter control unit  15  receive a feed limitation signal which signals the implementation of a feed limitation on the relevant accessories  14  from the vehicle control unit  10  via the signal line  18 , and as this occurs, the corresponding switches  17  cut off the power supply line  16 , and the electronic meter control unit  15  notifies the user of those of the accessories  14  on which the feed limitation is implemented. 
     In addition, although not shown, the vehicle control unit  10  receives from other electronic control units or sensors signals which represent a running condition of the vehicle including an idle state, accelerated state, steady-speed running state or decelerated state and engine speeds in the relevant vehicle running conditions. 
     Next, a hardware configuration of the vehicle control unit  10  will be described. As shown in  FIG. 2 , the vehicle control unit  10  includes a microcomputer  30 , and this microcomputer  30  is connected to a bus  31  within the vehicle control unit  10  and is then connected to the external signal line  18  via an I/F interface)  32 . 
     The microcomputer  30  has a CPU (Central Processing Unit)  33 , and a ROM (Read Only Memory)  34  and a RAM (Random Access Memory)  35  are connected to the CPU  33  via a bus  36  within the microcomputer  30 . In addition, the bus  31  is connected to the CPU  33  via the bus  36 . 
     The CPU  33  controls the whole of the vehicle control unit  10 . At least a part of a program of an OS (Operating System) and an application program which are executed by the CPU  33  is temporarily stored in the RAM  35 . In addition, various types of data which are necessary for processing by the CPU  33  are stored in the RAM  35 . The program of the OS and the application program are stored in the ROM  34 . 
     This application program contains programs for an available current value calculation process, an economical running control process, an alternator generation commanding process and a feed limiting process which are executed by the vehicle control unit  10 . 
     Next, a functional configuration of the vehicle control unit  10  will be described which is realized by the hardware configuration shown in  FIG. 2 . As shown in  FIG. 3 , the vehicle control unit  10  includes a battery monitoring section  41 , an alternator monitoring section  42 , an available current value calculating section  43 , an economical running controlling section  44 , an alternator generation commanding section  45 , a priority table  46  and a feed limiting section  47 . 
     The battery monitoring section  41  samples voltage values, current values and fluid temperatures of the battery  12  which are detected by the voltage sensor  21 , the current sensor  22  and the temperature sensor  23 , respectively. In addition, the alternator monitoring section  42  samples voltage values and current values of the alternator  11  which are detected by the voltage sensor  19  and the current sensor  20 , respectively. 
     The available current value calculating section  43  calculates an available current value which the battery  12  can supply to the electric equipments by calculating an internal resistance value of the battery  12  from voltage values and current values of the battery  12  which have been sampled by the battery monitoring section  41 . In addition, the available current value calculating section  43  appropriately updates the available current value based on a variation in the fluid temperatures of the battery  12  which have been sampled by the battery monitoring section  41 . 
     The economical running controlling section  44  determines whether it permits or prohibits an economical running based on the available current value. Based on the result of this determination, the economical running control unit  44  prohibits an economical running when a current value that is supplied to the safety system units  13  and the accessories  14  from the battery  12  is insufficient and permits the economical running when the current value is sufficient. 
     The alternator generation commanding section  45  calculates a generation requiring current value that is generated by the alternator  11  in order to secure a sufficient current value that is supplied to the safety system units  13  and the accessories  14  based on the available current value and issues a generation command to the alternator so as to obtain at least a generation of an electric current which corresponds to the generation requiring current value. 
     The priority table  46  stores relations between priorities in feeding and consumed current values of the accessories  14  in the ROM  34 . 
     The feed limiting section  47  calculates a feed limiting current value which is an insufficient portion of a current value that is supplied to the safety system units  13  and the accessories  14  based on a current value of the alternator  11  which has been sampled by the alternator monitoring section  42  and the available current value resulting after the current value that was to be supplied to the safety system units  13  and the accessories  14  was determined insufficient. The feed limiting section  47  identifies a minimum number of feed limitation candidates from the accessories  14  based on the feed limiting current value so calculated which are of low priories in feeding and whose consumed current values amount to at least a value which exceeds the feed limiting current value by referring to the priority table  46 , implements a feed limitation on the feed limitation candidate accessories  14  by interrupting the switches  17  therefor, and notifies the user of the implementation of the feed limitation on the relevant accessories  14  via the electronic meter control unit  15 . 
     Note that the vehicle control unit  10  may be integrated with an engine control unit which controls the engine. In addition, the invention may be carried out by configuring the economical running control unit  44  itself as a separate unit and through communication between the unit and the vehicle control unit  10 . 
     Next, a process carried out by the available current value calculating section  43  will be described. As shown in  FIG. 4 , the available current value calculating section  43  executes an available current value calculating process program to implement the process which follows the following steps.
     [Step S 11 ] The CPU  33  determines whether or not the engine has been started by driving a starter motor. If the engine has been so started, the process proceeds to Step S 12 , whereas if the engine has not been so started, the available current value calculating process ends.   [Step S 12 ] The CPU  33  determines whether or not a predetermined period of time has elapsed since the engine was started. This is because since a starter motor rush current flows in an initial stage of the start of the engine, in order not to sample this rush current as a current value of the battery  12 , a wait of the predetermined period of time is necessary. If the predetermined period of time has elapsed, the process proceeds to Step S 13 , whereas if the predetermined period of time has not yet elapsed, the process in this step S 12  is repeated.   [Step S 13 ] The CPU  33  starts sampling a voltage value and a current value of the battery  12  which have been detected by the voltage sensor  21  and the current sensor  22 , respectively.   [Step S 14 ] The CPU  33  determines whether or not a complete explosion has occurred in the engine. If the complete explosion has occurred, the process proceeds to Step S 18 , whereas if no complete explosion has occurred in the engine, the process proceeds to Step S 15 .   [Step S 15 ] The CPU  33  calculates an internal resistance value of the battery  12  by calculating a variation in voltage value and a variation in current value from a voltage value and a current value of the battery  12  which have been sampled this time and a voltage value and a current value of the battery  12  which were sampled previously and then dividing the voltage value variation by the current value variation.   [Step S 16 ] The CPU  33  determines whether or not a predetermined period of time has elapsed since the engine was started. If no complete explosion has occurred in the engine although the predetermined period of time has elapsed since the engine was started, since there exists a possibility of the occurrence of a trouble of a malfunction of the starter motor or the like, the available current value calculating process ends here. On the other hand, if the predetermined period of time has not yet elapsed since the engine was started, the process proceeds to Step S 17 .   [Step S 17 ] The CPU  33  determines whether or not the starting of the engine by driving the starter motor has been completed. If the start-up of the engine through the drive of the starter motor has ended although the engine was started with no complete explosion occurring in the engine, since there exists a possibility of the occurrence of a trouble of a malfunction of the starter motor or the like, the available current value calculating process ends here. On the other hand, if the start-up of the engine through the drive of the starter motor has not yet been completed, the process returns to Step S 14 .   [Step S 18 ] The CPU  33  finishes sampling a voltage value and a current value of the battery  12 . Here, internal resistance values of the battery  12  have been calculated from the voltage values and current values of the battery  12  which had been sampled during the time from the sampling was started until the complete explosion occurred in the engine.   [Step S 19 ] The CPU  33  determines on the internal resistance value of the battery  12 . This internal resistance value is a mean value, a maximum value or a most frequently occurring value of the internal resistance values of the battery  12  which were calculated through the process in Step S 15 . Note that the internal resistance value of the battery may be determined after off-values among the internal resistance values of the battery are deleted.   [Step S 20 ] The CPU  33  calculates an available current value which the battery  12  can supply by subtracting a discharge termination voltage value of the battery  12  at which the battery  12  cannot be discharged any more from the voltage value of the battery  12  and dividing the result of the subtraction by the internal resistance value of the battery  12 .   [Step S 21 ] The CPU  33  stores a fluid temperature of the battery which is detected by the temperature sensor  23  as Ta.   

     Next, a process will be described in which the internal resistance value of the battery  12  is updated by the available current value calculating section  43 . As shown in  FIG. 5 , the available current value calculating section  43  executes the available current value calculating process program to implement the process which follows the following steps.
     [Step S 31 ] The CPU  33  stores a fluid temperature of the battery  12  which is detected by the temperature sensor  23  as Tb.   [Step S 32 ] The CPU  33  determines whether or not a difference between the previous fluid temperature Ta of the battery  12  and the current fluid temperature Tb of the battery  12  is equal to or greater than a predetermined value To. If the difference is equal to or greater than the predetermined value To, the process proceeds to Step S 33 , whereas if the difference is less than the predetermined value To, the battery internal resistance value updating process ends. Here, since the battery  12  has a temperature property in which its internal resistance value changes as the fluid temperature changes, the internal resistance value has changed by such an extent that the fluid temperature has changed by comparing the stored fluid temperature and a fluid temperature that resulted thereafter. Namely, as is shown in  FIG. 6A , the battery  12  has a temperature property in which the internal resistance value R decreases as the fluid temperature T increases, and as is shown in  FIG. 6B , this temperature property is stored in the ROM  34  in the form of a table in which temperatures T and internal resistance values R of the battery  12  are related to each other.   [Step S 33 ] The CPU  33  calculates a generation requiring current value which is to be generated by the alternator  11  by subtracting the available current value from a sum of necessary current values which are necessary for the safety system units  13  and consumed current values which are consumed or used by the accessories  14 .   [Step S 34 ] The CPU  33  determines whether or not the current value of the alternator  11  is larger by a predetermined value Io or more than the generation requiring current value. If the current value of the alternator  11  is so larger than the generation requiring current value, the process proceeds to Step S 37 , whereas if the current value is smaller than the generation requiring current value, the process proceeds to Step S 35 .   [Step S 35 ] The CPU  33  determines whether or not the vehicle is stopped temporarily. If the vehicle is so stopped, the process proceeds to Step S 37 , whereas if the vehicle is not stopped temporarily, the process proceeds to Step S 36 .   [Step S 36 ] The CPU  33  determines whether or not a predetermined period of time has elapsed since the difference between the fluid temperature Ta and the fluid temperature Tb of the battery  12  became the predetermined value To or greater. If the predetermined period of time has elapsed, the process proceeds to Step S 45 , whereas if the predetermined period of time has not yet elapsed, the process returns to Step S 33 .   [Step S 37 ] The CPU  33  gradually reduces the voltage value of the alternator  11  by causing the alternator generation commanding section  45  to control the adjusting voltage value of the alternator  11 , so as to cause the battery  12  to be discharged by such an extent that the voltage value of the alternator  11  has so decreased to thereby cause the voltage value and current value of the battery  12  to change.   [Step S 38 ] The CPU  33  starts sampling a voltage value and a current value of the battery  12  which have been detected by the voltage sensor  21  and the current sensor  22 , respectively on a predetermined cycle.   [Step S 39 ] The CPU  33  determines whether or not a predetermined period of time has elapsed since the sampling was started. If the predetermined period of time has so elapsed, the process proceeds to Step S 41 , whereas if the predetermined period of time has not yet elapsed, the process proceeds to Step S 40 .   [Step S 40 ] The CPU  33  calculates an internal resistance value of the battery  12  by calculating a variation in voltage value and a variation in current value from a voltage value and a current value of the battery  12  which have been sampled this time and a voltage value and a current value of the battery  12  which were sampled previously and then dividing the voltage value variation by the current value variation.   [Step S 41 ] The CPU  33  finishes sampling the voltage value and current value of the battery  12 . Here, internal resistance values of the battery  12  have been calculated from the voltage values and current values of the battery  12  which had been sampled for the duration that a predetermined period of time had elapsed since the voltage value of the alternator  11  was started to be gradually reduced.   [Step S 42 ] The CPU  33  determines on the internal resistance value of the battery  12 . This internal resistance value is a mean value, a maximum value or a most frequently occurring value of the internal resistance values of the battery  12  which were calculated through the process in Step S 40 . Note that the internal resistance value of the battery may be determined after off-values among the internal resistance values of the battery are deleted.   [Step S 43 ] The CPU  33  calculates an available current value which the battery  12  can supply by subtracting the discharge termination voltage value from the voltage value of the battery  12  and then dividing the result of the subtraction by the internal resistance value of the battery  12  and updates the available current value of the battery  12 .   [Step S 44 ] The CPU  33  stores the fluid temperature Tb of the battery  12  which resulted when the latest internal resistance value of the battery  12  was calculated as a fluid temperature Ta.   [Step S 45 ] The CPU  33  obtains an internal resistance value of the battery  12  which corresponds to the fluid temperature of the battery  12  by referring to the table which is stored in the ROM  34  in advance and temporarily updates the internal resistance value of the battery  12 .   [Step S 46 ] The CPU  33  calculates an available current value which the battery  12  can supply by subtracting the discharge termination voltage value from the voltage value of the battery  12  and then dividing the result of the subtraction by the internal resistance value of the battery  12  and temporarily updates the available current value of the battery  12 . The processes in Steps S 45  and S 46  are such as to be carried out in an attempt to temporarily update the available current value based on a theoretical internal resistance value instead of using an actual one when the updating of the internal resistance value of the battery  12  cannot be implemented although there is occurring a change in fluid temperature of the battery  12 . Namely, for example, when the vehicle is driven on a highway over a long period of time at a constant speed, since the engine speed is constant, there occurs little change in generation amount of the alternator  11 . Since this makes it difficult for the current value of the alternator  11  to become large and the vehicle is not stopped, the process is made difficult to proceed to Steps S 42  and S 43 , whereby the updating of the internal resistance value and the available current value is made difficult to take place. In order to avoid the situation in which the internal resistance value and the available current values are not updated, the theoretical internal resistance value is obtained so as to temporarily update the available current value in the processes of Steps S 45  and S 46 . Note that in the event that the process can proceed to Step S 42  after the theoretical internal resistance value was obtained to update the available current value temporarily, the available current value is to be updated by an actual internal resistance value.   

     Next, an economical running control process by the economical running controlling section  44  will be described. As shown in  FIG. 7 , the economical running controlling section  44  executes an economical running controlling process program to repeatedly carry out the process which follows the following steps.
     [Step S 51 ] The CPU  33  determines whether or not an economical running condition has been established. This economical running condition is established, for example, when the brake pedal is depressed to apply the brakes so as to stop the vehicle temporarily after it has been started to run, whereby the running conditions of the vehicle is being in an idle state with the vehicle speed of 0. If the economical running condition has been established, the process proceeds to Step S 52 , whereas if the condition has not been established, the process proceeds to Step S 63 .   [Step S 52 ] The CPU  33  determines whether it permits or prohibits an economical running. The CPU  33  permits the economical running when the available current value is larger than a sum of the necessary current values for the safety system units  13  and the consumed current values by the accessories  14 , and the process proceeds to Step S 53 , whereas when the available current value is smaller than the sum, the CPU  33  prohibits the economical running, and the process proceeds to Step S 63 .   [Step S 53 ] The CPU  33  permits and implements the economical running.   [Step S 54 ] The CPU  33  starts sampling of voltage values and current values of the battery  12  which are detected by the voltage sensor  21  and the current sensor  22 , respectively, on a predetermined cycle.   [Step S 55 ] The CPU  33  determines whether or not a predetermined period of time has elapsed since the economical running was implemented. If the predetermined period of time has elapsed, the process proceeds to Step S 57 , whereas if the predetermined period of time has not elapsed, the process proceeds to Step S 56 .   [Step S 56 ] The CPU  33  calculates an internal resistance value of the battery  12  by calculating a variation in voltage value and a variation in current value from a voltage value and a current value of the battery  12  which have been sampled this time and a voltage value and a current value of the battery  12  which were sampled previously and then dividing the voltage value variation by the current value variation.   [Step S 57 ] The CPU  33  finishes sampling voltage values and current values of the battery  12 . As this occurs, internal resistance values of the battery  12  have been calculated from the voltage values and current values of the battery  12  which had been sampled for the duration that a predetermined period of time had elapsed since the economical running was started.   [Step S 58 ] The CPU  33  determines on the internal resistance value of the battery  12 . This internal resistance value is a mean value, a maximum value or a most frequently occurring value of the internal resistance values of the battery  12  which were calculated through the process in Step S 40 . Note that the internal resistance value of the battery may be determined after off-values among the internal resistance values of the battery are deleted.   [Step S 59 ] The CPU  33  calculates an available current value which the battery  12  can supply by subtracting the discharge termination voltage value from the voltage value of the battery  12  and then dividing the result of the subtraction by the internal resistance value of the battery  12 .   [Step S 60 ] The CPU  33  determines whether or not an economical running prohibiting condition for prohibiting the economical running has been established while the economical running is in operation. If the available current value is smaller than the sum of the necessary current values for the safety system units  13  and the consumed current values by the accessories  14 , the economical running prohibiting condition is established, and the process proceeds to Step S 61 , whereas if the available current value is larger than the sum, the economical running prohibiting condition is not established, and the process returns to Step S 54 . Note that since the safety system unit such as the ABS is activated in no case while the economical running is in operation, the necessary current value for such a safety system unit can be excluded, and this makes it difficult for the economical running prohibiting condition to be established.   [Step S 61 ] The CPU  33  determines whether or not a predetermined period of time has elapsed since the economical running prohibiting condition was established. If the predetermined period of time has elapsed, the process proceeds to Step S 62 , whereas if the predetermined period of time has not elapsed, the process in this step S 61  is repeated.   [Step S 62 ] The CPU  33  prohibits the economical running and forcibly restarts the engine to start the generation.   [Step S 63 ] When an economical running condition is not established or the economical running is not permitted although the economical running condition is established, the CPU  33  prohibits the economical running.   

     Next, an alternator generation commanding process by the alternator generation commanding section  45  will be described. When a complete explosion occurs in the engine, the alternator generation commanding section  45  executes an alternator generation commanding process program, as shown in  FIG. 8 , to repeatedly carry out the process which follows the following steps.
     [Step S 71 ] The CPU  33  obtains a state of the vehicle which is informed thereto from other electronic control units or sensors, that is, a running condition of the vehicle which is represented by an idle state, accelerated state, steady-speed running state or decelerated state of the vehicle, as well as an engine speed.   [Step S 72 ] The CPU  33  obtains a state of the battery, that is, a voltage value and a current value of the battery  12  which are detected by the voltage sensor  21  and the current sensor  22 , respectively and obtains the internal resistance value of the battery  12  which was calculated by the available current value calculating section  43  in the process in Step S 42 .   [Step S 73 ] The CPU  33  obtains an available-for-generation voltage value which corresponds to an engine speed. As is shown in  FIG. 9 , since the alternator  11  has a property in which an available-for-generation voltage value Vt which the alternator  11  can generate changes according to engine speeds, the CPU  33  obtains an available-for-generation voltage value Vt which corresponds to the engine speed which was obtained in the process in Step S 71  by referring to the ROM  34  which stores the property of the alternator  11 .   [Step S 74 ] The CPU  33  obtains a correction coefficient of the available-for-generation voltage value which corresponds to the internal resistance value of the battery  12  and corrects the available-for-generation voltage value which was obtained in the process in Step S 73  by the correction coefficient so obtained. This is because a voltage value to be generated needs to be increased as the internal resistance value of the battery  12  increases even with the same engine speed. The corresponding relationship between the internal resistance value R of the battery  12  and the correction coefficient of the available-for-generation voltage value is such as shown in  FIG. 10 , and the CPU  33  is designed to obtain a correction coefficient for an available-for-generation voltage value which corresponds to the internal resistance value R of the battery  12  by referring to the ROM  34  which stores the property of the correction coefficient, as shown in  FIG. 10 .   [Step S 75 ] The CPU  33  protects the available-for-generation voltage value which was calculated in the process in Step S 74  by an output voltage value which corresponds to the running condition of the vehicle and the voltage value of the battery  12 . Namely, as is shown in  FIG. 11 , the output voltage value Vm of the alternator  11  may be reduced as the voltage Vb of the battery  12  increases, and furthermore, the output voltage value Vm has a property in which the output voltage value Vm changes according to the running conditions of the vehicle in such a manner as to be increased in the order of an idle, accelerated, steady-speed running and decelerated state of the vehicle. However, since the available-for-generation voltage value that was corrected in the process in Step S 74  was calculated irrespective of the property, there may occur a case where the calculated value increases to a very high level, and in such a case, the CPU  33  obtains an output voltage value which corresponds to the running condition of the vehicle and the voltage value Vb of the battery  12  which were both obtained in the process in Step S 71  and protects the corrected available-for-generation voltage value by the output voltage value so obtained.   [Step S 76 ] The CPU  33  calculates a generation requiring current value by subtracting the available current value from the sum of the necessary current values for the safety system units  13  and the consumed current values by the accessories  14 .   [Step S 77 ] The CPU  33  calculates an adjusting voltage value of the alternator  11  which is equal to or less than the available-for-generation voltage value which was calculated in the process in Step S 75  and which can attain at least a generation of the generation requiring current value which was calculated in the process in Step S 76  and issues a generation command to the alternator  11 .   [Step S 78 ] The CPU  33  determines whether or not the current value of the alternator  11  is larger than the generation requiring current value, in other words, determines whether or not a sum of the available current value and the current value of the alternator is larger than the sum of the necessary current values for the safety system units  13  and the consumed current values by the accessories  14 . If the former sum is larger than the latter sum, the alternator generation commanding process ends, whereas the former sum is smaller than the latter sum, the process proceeds to Step S 79 .   [Step S 79 ] The CPU  33  implements a feed limiting process which will be described by reference to  FIG. 12 .   

     Next, a feed limiting process by the feed limiting section  47  will be described. As shown in  FIG. 12 , the feed limiting section  47  executes a feed limiting process program so as to repeatedly carry out the process which follows the following steps when a complete explosion occurs in the engine.
     [Step S 81 ] The CPU  33  determines whether or not a feed limiting process starting condition for starting a feed limiting process has been established. The feed limiting process starting condition is established when the sum of the available current value and the current value of the alternator  11  is smaller than the sum of the necessary current values for the safety system units  13  and the consumed current values by the accessories  14 , and the process proceeds to Step S 82 , whereas if the former sum is larger than the latter sum, the feed limiting process starting condition is not established, whereby the feed limiting process ends.   [Step S 82 ] The CPU  33  determines whether or not the safety system units  13  are in operation. If the units are in operation, the process proceeds to Step S 83 , whereas if the units are not in operation, the process proceeds to Step S 87 .   [Step S 83 ] The CPU  33  calculates a feed limiting current value which constitutes an insufficient portion of the current value that is supplied to the electric component by subtracting the consumed current values by some of the safety system units  13  which are in operation from the sum of the necessary current values for the safety system units  13  and the consumed current values of the accessories  14  and further subtracting the sum of the available current value and the current value of the alternator  11  from the remaining of the sum of the necessary current values for the safety system units  13  and the consumed current values of the accessories  14 .   [Step S 84 ] The CPU  33  identifies feed limitation candidate accessories. As this occurs, the CPU  33  identifies a minimum number of feed limitation candidate accessories  14  by referring to the priority table  46  as shown in  FIG. 13  in such a manner that the minimum number of feed limitation candidate accessories  14  are of low priority in feeding and whose consumed current values amount to at least a value which exceeds the feed limiting current value. This priority table  46  stores corresponding relationships of names, priorities in feeding and consumed current values of the accessories  14 , and the priorities are classified into three stages such as, for example, “high,” “medium,” and “low.” For example, in the event that the sum of the available current value and the current value of the alternator is insufficient by “10 A,” the CPU  33  refers to the priority table  46  to select only a “JJJ” which is low in priority and which has a consumed current value of “12 A,” whereby the number of accessories  14  on which the feed limiting is implemented can be minimized.   [Step S 85 ] The CPU  33  interrupts the switch  17  for the accessory  14  which has been selected as the feed limitation candidate and implements the feed limitation.   [Step S 86 ] The CPU  33  controls the electronic meter control unit  15  to notify the user of the accessory  14  on which the feed limitation is implemented. The user notification is implemented through, for example, illumination of a lamp, display of characters and the like.   [Step S 87 ] The CPU  33  determines whether or not a predetermined period of time has elapsed since the feed limiting process starting condition was established. If the predetermined period of time has elapsed, the process proceeds to step S 88 , whereas if the predetermined period of time has not elapsed, the process in Step S 87  is repeated.   [Step S 88 ] The CPU  33  calculates a feed limiting current value which constitutes an insufficient portion of the current value that is supplied to the electric equipment by subtracting the sum of the available current value and the current value of the alternator  11  from the sum of the necessary current values for the safety system units  13  and the consumed current values by the accessories  14 .   [Step S 89 ] The CPU  33  identifies the minimum number of feed limitation candidate accessories  14  on which the feed limiting is implemented by referring to the priority table  46  as shown in  FIG. 13  in such a manner that the candidates are low in priority in feeding and a total of the consumed current values thereof exceeds at least the feed limiting current value.   [Step S 90 ] The CPU  33  determines whether or not the operation of the safety system units  13  which are not in operation is anticipated. If the operation is anticipated, the process proceeds to Step S 91 , whereas if not, the feed limiting process ends. For example, in the case of the safety system unit  13  of the pre-crash safety system, assuming that the pre-crash safety system is activated when the vehicle speed is X km/h or faster and a distance to a preceding vehicle is Y m, an operation of the pre-crash safety system is anticipated when the vehicle speed is X km/h or faster and the distance to the preceding vehicle is Z m which is longer than Y m.   [Step S 91 ] The CPU  33  cuts off the switch  17  for the accessory  14  which is selected as the feed limitation candidate accessory and implements the feed limitation. For example, since, in the event that the vehicle runs Z m after the operation of the pre-crash safety system was anticipated in the process in Step S 90 , the pre-crash safety system is activated in an ensured fashion, the feed limitation is implemented on the accessory  14  in the process in Step S 91  in preparation for the anticipated activation of the pre-crash safety system. Here, in the event that the safety system unit  13  is in operation, a feed limitation is implemented on the accessory  14  immediately, whereas if the safety system unit  13  is not in operation, the feed limitation on the accessory  14  is implemented when an operation of the safety system unit  13  is anticipated after a predetermined period of time has elapsed.   [Step S 92 ] The CPU  33  monitors a predetermined terminal of the alternator  11  and determines whether or not a charging system failure signal which signals a failure of the charging system has been received from the alternator  11 . If a charging system failure signal is received with the charging system failing, the process proceeds to Step S 93 , whereas if no charging system failure signal has been received because the charging system does not fail, the process proceeds to Step S 94 .   [Step S 93 ] The CPU  33  controls the electronic meter control unit  15  to notify the user of the accessory  14  on which the feed limitation is implemented. In addition, since the failure of the charging system is confirmed in the process in Step S 92 , the CPU  33  controls the electronic meter control unit  15  to notify the user that the use of the accessories  14  be suppressed because there will be an anticipated shortage in current value to be supplied in the future due to the failure of the charging system.   [Step S 94 ] The CPU  33  controls the electronic meter control unit  15  to notify the user of the accessory  14  on which the feed limitation is implemented.