Patent Publication Number: US-9417081-B2

Title: Device for predicting energy consumption and method for predicting energy consumption

Description:
TECHNICAL FIELD 
     The present invention relates to a device for predicting energy consumption and a method for predicting energy consumption. 
     This application claims a priority on the basis of Japanese Patent Application No. 2013-082823, filed on Apr. 11, 2013. The contents of the above application is incorporated herein by reference in the designated countries in which the incorporation by reference is accepted. 
     BACKGROUND ART 
     As a prior art, a device for predicting fuel consumption on the basis of a vehicle speed, an acceleration, and air resistance caused when the vehicle actually travels is known (see Patent Document 1). 
     PRIOR ART DOCUMENT 
     Patent Document 
     [Patent Document 1] JP 2011-506873 A 
     SUMMARY OF INVENTION 
     Problems to be Solved by Invention 
     In the prior art, energy consumption at the current time point is predicted on the basis of such as the vehicle speed and the acceleration obtained when the vehicle actually travels. It is, however, impossible to predict the energy consumption over a scheduled traveling route before the vehicle travels. 
     A problem to be solved by the present invention is to provide a device for predicting energy consumption which can appropriately predict energy consumption. 
     Means for Solving Problems 
     The invention solves the problem as below. Air resistance caused when a vehicle travels along a scheduled traveling route is calculated by using an air resistance calculation formula on the basis of a traveling speed information set for each route. The calculated air resistance is corrected so that the air resistance is higher according as the traveling speed along the scheduled traveling route is slower. The energy consumption over the scheduled traveling route is predicted on the basis of the corrected air resistance. 
     Effect of Invention 
     According to the present invention, the air resistance caused when the vehicle travels along the scheduled traveling route is calculated on the basis of the traveling speed information set for each route. Accordingly, it is possible to predict the energy consumption over the scheduled traveling route. In particular, according to the present invention, the air resistance calculated by the air resistance calculation formula is corrected in consideration of the tendency that the frequency of acceleration is higher according as the traveling speed along the scheduled traveling route is lower. Accordingly, it is possible to highly precisely predict the air resistance caused when the vehicle travels along the traveling route. As a result, it is possible to appropriately predict the energy consumption over the scheduled traveling route on the basis of the corrected air resistance. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a configuration diagram of a navigation device according to an embodiment of the present invention; 
         FIG. 2  is a functional block diagram of a control device according to a first embodiment; 
         FIG. 3  is a graph illustrating an example of an integrated value of actual air resistance in a predetermined traveling section and an integrated value of air resistance predicted on the basis of the following formula (2); 
         FIG. 4(A)  is a diagram illustrating an example of an experiment values of air resistance coefficients; 
         FIG. 4(B)  is a diagram illustrating an example of an air resistance calculating function; 
         FIG. 5  is a diagram illustrating an example of an air resistance correction function when a traveling section is inclined; 
         FIG. 6  is a graph illustrating an example of an integrated value of actual loss in a drive-train in a predetermined traveling section and an integrated value of loss in a drive-train predicted on the basis of the following formula (3); 
         FIG. 7(A)  is a diagram illustrating an example of an experiment values of loss coefficients; 
         FIG. 7(B)  is a diagram illustrating an example of a loss calculating function; 
         FIG. 8  is a diagram illustrating an example of a loss correction coefficients when a traveling section is inclined; 
         FIG. 9  is a flowchart illustrating a process for predicting energy consumption according to the first embodiment; 
         FIG. 10(A)  is a diagram illustrating an example of an average vehicle speed in each traveling section of a recommended route; 
         FIG. 10(B)  is a diagram illustrating an example of an altitude of each traveling section of a recommended route; 
         FIG. 11  is a graph illustrating an example of a temporal transition of an actual vehicle speed, an average vehicle speed, an integrated value of actual air resistance, an integrated value of air resistance predicted on the basis of the following formula (2), and an integrated value of air resistance predicted on the basis of the following formula (10) in a predetermined traveling section; 
         FIG. 12  is a graph illustrating an example of an integrated value of actual air resistance, an integrated value of air resistance predicted on the basis of the following formula (2), and an integrated value of air resistance predicted on the basis of the following formula (10) in a predetermined traveling section; 
         FIG. 13  is a graph illustrating an example of an integrated value of actual air resistance when a traveling section is inclined, an integrated value of air resistance predicted by using an air resistance correction coefficient α when the traveling section is flat, and an integrated value of air resistance predicted by using an air resistance correction coefficient α when the traveling section is inclined; 
         FIG. 14  is a graph illustrating an example of a temporal transition of an actual vehicle speed, an average vehicle speed, and an integrated value of actual loss in a drive-train, an integrated value of loss in a drive-train predicted on the basis of the following formula (3) and an integrated value of loss in a drive-train predicted on the basis of the formula (14) in a predetermined traveling section; 
         FIG. 15  is a graph illustrating an example of an integrated value of actual loss in a drive-train, an integrated value of loss in a drive-train predicted on the basis of the following formula (3), and an integrated value of loss in a drive-train predicted on the basis of the following formula (14) in a predetermined traveling section; 
         FIG. 16  is a graph illustrating an example of an integrated value of actual loss in a drive-train when a traveling section is inclined, an integrated value of loss in a drive-train predicted by using a loss correction coefficient  13  when the traveling section is flat, and an integrated value of loss in a drive-train predicted by using the loss correction coefficient  13  when the traveling section is inclined; 
         FIG. 17  is a functional block diagram of a control device according to a second embodiment; 
         FIG. 18  is a diagram illustrating an example of a correlation of an ambient air temperature and a rolling resistance coefficient; 
         FIG. 19  is a graph illustrating an example of a correlation of a rolling resistance, an average vehicle speed, and a loss correction coefficient; 
         FIG. 20  is a diagram illustrating an example of a loss correction coefficient of each type of vehicles; 
         FIG. 21  is a first flowchart illustrating a process for predicting energy consumption according to the second embodiment; 
         FIG. 22  is a second flowchart illustrating a process for predicting energy consumption according to the second embodiment; 
         FIG. 23  is a diagram illustrating an example of actual energy consumption and energy consumption predicted regardless of an ambient air temperature; 
         FIG. 24  is a diagram illustrating an example of actual energy consumption and energy consumption predicted in consideration of an ambient air temperature; 
         FIG. 25  is a diagram illustrating an example of a predicted value of ambient air temperature; and 
         FIG. 26  is a graph illustrating an example of energy consumption of each type of vehicles. 
     
    
    
     MODE(S) FOR CARRYING OUT THE INVENTION 
     Hereinafter, embodiments of the present invention will be described with reference to the drawings. Further, the embodiments of the present invention will be described below by exemplifying a navigation device mounted on an electric vehicle. 
     First Embodiment 
       FIG. 1  is a configuration diagram of a navigation device  1  according to a present embodiment. The navigation device  1  predicts energy consumption from a current position to a destination. The navigation device  1  determines whether a vehicle can reach a destination from the current position by a remaining amount of current battery on the basis of the predicted energy consumption. The navigation device  1  includes an input device  200  configured to input a destination, an own vehicle position detecting device  300  configured to detect a current position of an own vehicle, a map database  400  configured to store map information including road information, a control device  100  configured to predict energy consumption to a destination, and a display  500  configured to suggest a prediction result to a passenger. Hereinafter, the configurations will be described in detail. 
     The input device  200  is, for example, a device such as a touch panel disposed on a display screen used to input a user&#39;s instruction by user&#39;s hand or a microphone used to input a user&#39;s voice. The information which is input by the input device  200  is transmitted to the control device  100 . 
     The own vehicle position detecting device  300  includes a GPS (Global Positioning System) unit, a gyro sensor, and a vehicle speed sensor. The own vehicle position detecting device  300  detects radio waves transmitted from telecommunication satellites and periodically obtain the position information of the own vehicle. Further, the own vehicle position detecting device  300  detects the current position of the own vehicle on the basis of the position information of the own vehicle, the angle change information obtained from the gyro sensor, and the vehicle speed obtained from the vehicle speed sensor. The position information of the own vehicle detected by the own vehicle position detecting device  300  is transmitted to the control device  100 . 
     The map database  400  stores the map information including the road information. Specifically, the map database  400  stores the road information including a traveling distance, an altitude, an inclination, and an average vehicle speed in each traveling section such as a road link. The average vehicle speed in the traveling section is an average value of vehicle speed information collected from vehicles actually traveling in the traveling section. The map information stored in the map database  400  is used for the control device  100  to predict the energy consumption from the current position to the destination. 
     The display  500  displays the information transmitted from the control device  100  on a screen of the display  500 . The information which is displayed by the display  500  includes a map around the own vehicle and the recommended route from the current position to the destination. In addition, the information includes energy consumption from the current position to the destination, information used to determine whether the battery charging is necessary, and positions of battery charging stations. 
     The control device  100  includes a ROM (Read Only Memory) configured to store a program for predicting the energy consumption from the current position to the destination, a CPU (Central Processing Unit) configured as an operation circuit for executing a program stored in the ROM, and a RAM (Random Access Memory) configured as an accessible storage device. Further, an MPU (Micro Processing Unit), a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or the like can be used as the operation circuit instead of or together with the CPU. 
       FIG. 2  is a functional block diagram illustrating a function of the control device  100  according to the first embodiment of the present invention. In the first embodiment, as illustrated in  FIG. 2 , the control device  100  includes a map information obtaining unit  110 , a recommended route searching unit  120 , an energy consumption predicting unit  130 , a correction coefficient storing unit  140 , a correction coefficient calculating unit  150 , a charging necessity determining unit  160 , a charging station searching unit  170 , and a display unit  180 . 
     The map information obtaining unit  110  obtains the map information including the road information from the map database  400 . The map information obtained by the map information obtaining unit  110  is transmitted to the recommended route searching unit  120 , the energy consumption predicting unit  130 , and the correction coefficient calculating unit  150 . 
     The recommended route searching unit  120  searches for the recommended route from the current position to the destination on the basis of the map information obtained from the map information obtaining unit  110 , the destination input through the input device  200 , and the position information of the own vehicle detected by the own vehicle position detecting device  300 . 
     The energy consumption predicting unit  130  predicts the energy consumption from the current position to the destination. Specifically, the energy consumption predicting unit  130  predicts rolling resistance, inclination resistance, air resistance, and loss in a drive-train such as a motor and a gear in a recommended route. The energy consumption predicting unit  130  predicts the energy consumption from the current position to the destination by summing up these values. 
     Air resistance Fa caused when the vehicle travels can be calculated on the basis of the following formula (1). In the following formula (1), V cur  indicates a traveling vehicle speed and K indicates a parameter relating to air resistance which includes an air resistance coefficient and projected area of a vehicle.
 
[Formula 1]
 
AIR RESISTANCE  Fa=kV   cur   2   (1)
 
     In this way, the air resistance Fa changes in response to the vehicle speed V cur  obtained when the vehicle travels. Therefore, for example, when the recommended route is divided into a plurality of traveling sections, an integrated value of the air resistance in each traveling section can be calculated on the basis of the average speed V ave  of the traveling section and the traveling distance of the traveling section as the following formula (2). Then, the integrated values of air resistance in the traveling sections are summarized as the integrated value of air resistance to the destination in the recommended route.
 
[Formula 2]
 
INTEGRATED VALUE OF AIR RESISTANCE IN TRAVELING SECTION= kV   ave   2   *d    (2)
 
     However, the integrated value of air resistance calculated by the formula (2) is air resistance caused when the vehicle travels at a constant average speed V ave . Since the vehicle actually travels while being accelerated and decelerated, an error may be caused between the integrated value of air resistance calculated by the formula (2) and the integrated value of actual air resistance. That is, the air resistance caused when the vehicle travels at a constant speed is proportional to the square of the speed as illustrated in the formula (2), but the air resistance caused when the vehicle is accelerated is proportional to the cube of the speed. For that reason, the integrated value of air resistance in the traveling section increases according as the vehicle is accelerated in the traveling section. Accordingly, an error is caused between the integrated value of air resistance calculated by the formula (2) and the integrated value of actual air resistance. 
     Therefore, when the energy consumption predicting unit  130  predicts the integrated value of air resistance in each traveling section, the integrated value of air resistance calculated on the basis of the formula (2) is corrected in consideration of the influence of the acceleration in each traveling section. Specifically, the energy consumption predicting unit  130  corrects the air resistance by using the air resistance correction coefficient calculated by the correction coefficient calculating unit  150  to be described later. Further, a method for correcting the integrated value of air resistance in the traveling section will be described later. 
     Further, the energy consumption predicting unit  130  according to the embodiment predicts the energy consumption to the destination on the basis of an integrated value of loss caused in a drive-train such as a motor or a gear. Here, when the vehicle travels at a constant speed in a predetermined traveling section, the loss L in the drive-train in the traveling section is caused by travel resistance such as rolling resistance and air resistance. The loss L in the drive-train in the traveling section can be calculated on the basis of, for example, the following formula (3). 
     
       
         
           
             
               
                 
                   
                       
                   
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                     [ 
                     
                       Formula 
                       ⁢ 
                       
                           
                       
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                       3 
                     
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                     LOSS 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     L 
                   
                   = 
                   
                     
                       ( 
                       
                         
                           ROLLING 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           RESISTANCE 
                         
                         + 
                         
                           AIR 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           RESISTANCE 
                         
                       
                       ) 
                     
                     
                       
                         
                           
                             
                               MOTOR 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               EFFICIENCY 
                               * 
                               GEAR 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               EFFICIENCY 
                             
                             - 
                           
                         
                       
                       
                         
                           
                             ( 
                             
                               
                                 ROLLING 
                                 ⁢ 
                                 
                                     
                                 
                                 ⁢ 
                                 RESISTANCE 
                               
                               + 
                               
                                 AIR 
                                 ⁢ 
                                 
                                     
                                 
                                 ⁢ 
                                 RESISTANCE 
                               
                             
                             ) 
                           
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   3 
                   ) 
                 
               
             
           
         
       
     
     However, the integrated value of loss in the drive-train calculated by the formula (3) is obtained when the vehicle travels at a constant speed. Since the vehicle actually travels while being accelerated and decelerated, an error may be caused between the integrated value of loss in the drive-train calculated by the formula (3) and the integrated value of actual loss in the drive-train. That is, when the vehicle is accelerated, the loss in the drive-train caused by an inertia moment is added to the loss L in the drive-train other than the loss in the drive-train caused by the travel resistance. For that reason, an error may be caused between the loss in the drive-train obtained by the formula (3) and the actual loss in the drive-train. When the energy consumption predicting unit  130  predicts the integrated value of loss in the drive-train in the traveling section, the loss in the drive-train calculated by the formula (3) is corrected in consideration of an influence of the acceleration in the traveling section. Specifically, the energy consumption predicting unit  130  corrects the loss in the drive-train calculated by the formula (3) by using the loss correction coefficient calculated by the correction coefficient calculating unit  150  to be described later. 
     The correction coefficient storing unit  140  stores the air resistance correction coefficient for correcting the air resistance in the recommended route and the loss correction coefficient for correcting the loss in the drive-train in the recommended route. Hereinafter, the air resistance correction coefficient and the loss correction coefficient will be described. 
       FIG. 3  is a graph illustrating an example of the integrated value of actual air resistance in a predetermined traveling section and the integrated value of air resistance calculated by the formula (2). Further, in  FIG. 3 , the integrated value of actual air resistance is indicated by white bar graph, and the integrated value of air resistance calculated by the formula (2) is indicated by diagonal hatching bar graph. In  FIG. 3 , the integrated value of air resistance calculated by the formula (2) is indicated by the percentage (%) when the integrated value of actual air resistance is set as 100%. Further, the integrated value of actual air resistance in  FIG. 3  is an integrated value of air resistance obtained by an experiment from the profile of the travel speed when the vehicle actually travels in the traveling section. 
     In the examples illustrated in  FIG. 3 , when the vehicle speed is low, the integrated value of air resistance calculated by the formula (2) is approximately 40% of the integrated value of actual air resistance. It show that a large error is caused with respect to the actual air resistance. Further, even when the vehicle travels at a medium speed, the integrated value of air resistance calculated by the formula (2) is approximately 60% of the integrated value of actual air resistance. It shows that an error is caused with respect to the actual air resistance. Further, when the vehicle travels at a high speed, the integrated value of air resistance calculated by the formula (2) is approximately 100% of the integrated value of actual air resistance, close to the integrated value of actual air resistance. In this way, there is a tendency that an error between the integrated value of actual air resistance and the integrated value of air resistance calculated by the formula (2) is larger according as the vehicle speed in the traveling section is lower. 
     In the embodiment, the air resistance correction coefficient for correcting the error of the air resistance by the acceleration is stored in advance in the correction coefficient storing unit  140 . Hereinafter, the air resistance correction coefficient stored in the correction coefficient storing unit  140  will be described in detail. 
     The air resistance correction coefficient stored in the correction coefficient storing unit  140  is set in advance, on the basis of the integrated value of actual air resistance obtained in advance by an experiment and the integrated value of air resistance calculated in advance by the formula (2). For example, the ratio between the integrated value of air resistance calculated on the basis of the formula (2) and the integrated value of actual air resistance obtained by an experiment is calculated in advance as an experiment value of air resistance coefficients each average vehicle speed V ave  in the traveling section. The ratio the integrated value of actual air resistance/the integrated value of air resistance calculated on the basis of the formula (2)′ is indicated as a calculated experiment values. Then, the calculated experiment values of air resistance coefficients is plotted each average vehicle speed V ave  in the traveling section as illustrated in  FIG. 4(A) . Further,  FIG. 4(A)  is a diagram illustrating an example of the experiment values of air resistance coefficients. 
     In the embodiment, for example, as illustrated in  FIG. 4(B) , a regression line of the plotted experiment values of air resistance coefficients is calculated. Then, the calculated regression line is stored in advance as a function f 1  (hereinafter, referred to as an air resistance calculating function f 1 ) in the correction coefficient storing unit  140 . The function f 1  is used for calculating the air resistance correction coefficient. In this way, in the embodiment, the air resistance correction coefficient for each average vehicle speed V ave  in the traveling section is stored as the air resistance calculating function f 1  in the correction coefficient storing unit  140 . Further,  FIG. 4(B)  is a diagram illustrating an example of the air resistance calculating function f 1 . 
     Further, there is a tendency that frequency of acceleration in the traveling section decreases when the traveling section is inclined compared to a case in which the traveling section is flat. Therefore, in the embodiment, as illustrated in  FIG. 5 , an air resistance calculating function f 2  used when the traveling section is inclined is stored in advance in the correction coefficient storing unit  140  separately from the air resistance calculating function f 1  used when the traveling section is not inclined. Further,  FIG. 5  is a diagram illustrating an example of the air resistance calculating function f 2  used when the traveling section is inclined. In  FIG. 5 , the experiment values of air resistance coefficients obtained by an experiment in the inclined traveling section is indicated by a white square plot. Further, for convenience of description, the air resistance calculating function f 1  used when the traveling section is not inclined is also illustrated by a dashed line in  FIG. 5 . 
     As illustrated in  FIG. 5 , when the average speed V ave  in the traveling section is low (for example, a speed lower than 40 km/h), the value of the air resistance correction coefficient calculated by the air resistance calculating function f 2  used when the traveling section is inclined is smaller than that of the air resistance correction coefficient calculated by the air resistance calculating function f 1  used when the traveling section is not inclined. In this way, the air resistance correction coefficient calculated by the air resistance calculating function f 2  is stored as a value smaller than the air resistance correction coefficient calculated by the air resistance calculating function f 1 . Accordingly, even when the traveling section is inclined and the frequency of acceleration in the traveling section is low, it is possible to appropriately correct the integrated value of air resistance in the traveling section. 
     Further, the air resistance calculating function f 2  used when the traveling section is inclined is set so that the air resistance correction coefficient is calculated in response to an inclination degree of the traveling section. That is, the air resistance calculating function f 2  illustrated in  FIG. 5  exemplarily shows the air resistance calculating function f 2  at a predetermined inclination degree. The air resistance calculating function f 2  stored in the correction coefficient storing unit  140  can calculate one air resistance correction coefficient in response to the average vehicle speed V ave  and the inclination of the traveling section. Further, in the embodiment, the air resistance calculating function f 2  can be set so that the air resistance correction coefficient is smaller according as the inclination degree of the traveling section is larger. 
     Further,  FIG. 6  is a graph illustrating an example of the integrated value of actual loss in the drive-train in a predetermined traveling section and the integrated value of loss in the drive-train calculated on the basis of the formula (3). Further, in  FIG. 6 , the integrated value of actual loss in the drive-train is indicated by white bar graph, and the integrated value of loss in the drive-train calculated on the basis of the formula (3) is indicated by diagonal hatching bar graph. Further, in  FIG. 6 , the integrated value of loss in the drive-train calculated on the basis of the formula (3) is indicated by the percentage (%) when the integrated value of actual loss in the drive-train is set as 100%. Further, the actual loss in the drive-train is loss in a drive train obtained by an experiment from the profile of the travel speed when the vehicle actually travels in the traveling section. 
     In the example illustrated in  FIG. 6 , when the vehicle speed is low, the integrated value of loss in the drive-train calculated by the formula (3) is approximately 30% of the integrated value of actual loss in the drive-train. It shows that a large error is caused with respect to the integrated value of actual loss. Further, even when the vehicle speed is medium or high, an error is caused between the integrated value of actual loss and the loss calculated by the formula (3) according as the vehicle speed is lower. In this way, there is a tendency that an error between the integrated value of actual loss in the drive-train and the integrated value of loss in the drive-train calculated by the formula (3) is larger according as the average vehicle speed V ave  is lower. 
     In the embodiment, the loss correction coefficient for correcting the error of the loss in the drive-train such as the motor or the gear is stored in advance in the correction coefficient storing unit  140 . Hereinafter, the loss correction coefficient stored in the correction coefficient storing unit  140  will be described in detail. 
     The loss correction coefficient stored in the correction coefficient storing unit  140  is set in advance on the basis of the integrated value of loss caused by the travel resistance and the integrated value of loss caused by the inertia moment. Note that, the integrated value of loss caused by the travel resistance is calculated in advance on the basis of the formula (3). The integrated value of loss caused by the inertia moment is calculated in advance on the basis of speed information obtained when the vehicle actually travels in the traveling section. For example, the ratio between the integrated value of loss caused by the travel resistance and the integrated value of loss caused by the inertia moment is calculated in advance as an experiment value of loss coefficient each average vehicle speed V ave  in the traveling section. The ratio is indicated as ({the integrated value of loss in the drive-train caused by the travel resistance+the integrated value of loss in the drive-train caused by the inertia moment}/the integrated value of loss in the drive-train caused by the travel resistance). Then, the calculated experiment value of loss coefficient is plotted each average vehicle speed V ave  in the traveling section as illustrated in  FIG. 7(A) .  FIG. 7(A)  is a diagram illustrating an example of the experiment values of loss coefficients. 
     In the embodiment, for example, as illustrated in  FIG. 7(B) , the regression line of the plotted experiment values of loss coefficients is calculated. Then, the calculated regression line is stored in advance as a function f 3  (hereinafter, referred to as a loss calculating function f 3 ) in the correction coefficient storing unit  140 . The function f 3  is used for calculating the loss correction coefficient.  FIG. 7(B)  is a diagram illustrating an example of the loss calculating function f 3 . 
     Further, when the traveling section is inclined, the amount of work of a motor or a gear is larger than a case in which the traveling section is flat. For that reason, in the embodiment, as illustrated in  FIG. 8 , a loss calculating function f 4  used when the traveling section is inclined is stored in advance in the correction coefficient storing unit  140  separately from the loss calculating function f 3  used when the traveling section is not inclined.  FIG. 8  is a diagram illustrating an example of the loss calculating function f 4  used when the traveling section is inclined. In  FIG. 8 , the experiment values of loss coefficients obtained by an experiment in the inclined traveling section is indicated by a white square plot. Further, for convenience of description, the loss calculating function f 3  used when the traveling section is not inclined is also illustrated in the drawing. 
     As illustrated in  FIG. 8 , when the average speed V ave  of the traveling section is low (for example, a speed lower than 35 km/h), the value of the loss correction coefficient calculated by the loss calculating function f 4  is larger than that of the loss correction coefficient calculated by the loss calculating function f 3 . In this way, the loss correction coefficient calculated by the loss calculating function f 4  is stored as a value larger than the loss correction coefficient calculated by the loss calculating function f 3 . For that reason, even when the traveling section is inclined and the amount of work of a motor or a gear in the traveling section is large, it is possible to appropriate correct the integrated value of loss of the drive-train in the traveling section. 
     Further, the loss calculating function f 4  used when the traveling section is inclined is set so that the loss correction coefficient can be calculated in response to an inclination degree of the traveling section. That is, the loss calculating function f 4  illustrated in  FIG. 8  exemplarily shows the loss calculating function f 4  at a predetermined inclination degree. The loss correction coefficient f 4  stored in the correction coefficient storing unit  140  is set so that one loss correction coefficient can be calculated in response to the average vehicle speed V ave  and the inclination of the traveling section. Further, in the embodiment, the loss calculating function f 4  can be set so that the loss correction coefficient is larger according as the inclination of the traveling section is larger. 
     The correction coefficient calculating unit  150  calculates the air resistance correction coefficient for correcting the integrated value of air resistance in the traveling section. The correction coefficient calculating unit  150  calculates the integrated value of air resistance by using the air resistance calculating function stored in the correction coefficient storing unit  140 . Further, the correction coefficient calculating unit  150  calculates the loss correction coefficient for correcting the integrated value of loss in the drive-train in the traveling section by using the loss calculating function stored in the correction coefficient storing unit  140 . The air resistance correction coefficient and the loss correction coefficient calculated by the correction coefficient calculating unit  150  are used to predict energy consumption to the destination by the energy consumption predicting unit  130 . 
     The charging necessity determining unit  160  determines whether to charge the battery on the basis of the prediction result of the energy consumption predicting unit  130 . Specifically, the charging necessity determining unit  160  compares the remaining amount of current battery energy with the energy consumption to the destination predicted by the energy consumption predicting unit  130 . The charging necessity determining unit  160  determines that the battery needs to be charged when the energy consumption to the destination is larger than the remaining amount of current battery energy. The determination result obtained by the charging necessity determining unit  160  is transmitted to the charging station searching unit  170  and the display unit  180 . 
     When the charging necessity determining unit  160  determines that the battery needs to be charged, the charging station searching unit  170  searches for the charging station at which the vehicle can arrive by the remaining amount of current battery energy. The search result of the charging station searching unit  170  is transmitted to the display unit  180 . 
     The display unit  180  displays the information including the energy consumption to the destination predicted by the energy consumption predicting unit  130 , the determination result obtained by the charging necessity determining unit  160 , and the charging station searched by the charging station searching unit  170  on the display  500  as the information to suggest for the passenger of the own vehicle. 
     A process or sequence for predicting the energy consumption will be described with reference to  FIG. 9 .  FIG. 9  is a flowchart illustrating the process or sequence for predicting the energy consumption according to the first embodiment of the present invention. For example, the process or sequence for predicting the energy consumption is performed when the passenger inputs a destination through the input device  200 . 
     In step S 101 , the recommended route searching unit  120  searches for the recommended route from the current position to the destination. Specifically, the recommended route searching unit  120  searches for the recommended route on the basis of the map information obtained by the map information obtaining unit  110 , the destination input by the input device  200 , and the current position of the own vehicle detected by the own vehicle position detecting device  300 . 
     In step S 102 , the road information of the recommended route searched in step S 101  is obtained by the map information obtaining unit  110 . The road information includes the traveling distance information, the altitude information, and the average vehicle speed information of each predetermined traveling section (for example, a road link or the like) in the recommended route. For example, when the traveling section of the recommended route is divided into five traveling sections, the map information obtaining unit  110  obtains the road information including the traveling distance information, the altitude information, and the average vehicle speed information for each of five traveling sections. 
     Here,  FIG. 10  illustrates an example of the road information obtained by the map information obtaining unit  110 .  FIG. 10(A)  illustrates the average vehicle speed V ave  in each traveling section of the recommended route.  FIG. 10(B)  illustrates the altitude in each traveling section of the recommended route. Further, in  FIG. 10(A) , the horizontal axis indicates the traveling distance of the recommended route, and the line graph indicates the average vehicle speed V ave . The range (for example, a 1  and a 2  of  FIG. 10(A) ) between the points of the line indicates the average vehicle speed V ave  of one traveling section. Similarly, even in  FIG. 10(B) , the horizontal axis indicates the traveling distance of the recommended route, and the line graph indicates the altitude. The range (for example, a 1  and a 2  of  FIG. 10(B) ) between the points on the line indicates the altitude of one traveling section. In this way, the map information obtaining unit  110  obtains the road information including the traveling distance of each traveling section, the altitude, and the average vehicle speed of the traveling section. 
     The processes in step S 103  to step S 116  are performed each traveling section of the recommended route. In the description below, the traveling section which is a target in process in step S 103  to step S 116  will be described as the target section. 
     First, in step S 103 , the energy consumption predicting unit  130  determines whether the target section is inclined. For example, the energy consumption predicting unit  130  calculates the inclination of the target section as illustrated in the following formula (4) on the basis of the altitude information and the traveling distance information obtained in step S 102 . The energy consumption predicting unit  130  determines whether the target section is inclined on the basis of the calculated inclination of the target section.
 
INCLINATION (%)=100×ALTITUDE DIFFERENCE( m )/TRAVELING DISTANCE( m )  (4)
 
     When the target section is not inclined, the routine proceeds to step S 104 . On the other hand, when the target section is inclined, the routine proceeds to step S 106 . Further, the energy consumption predicting unit  130  may determine that the target section is inclined, for example, when the inclination of the target section is equal to or larger than 1%. The energy consumption predicting unit  130  also may determine that the target section is inclined, for example, when the inclination of the target section is equal to or smaller than −1%. 
     In step S 104 , the integrated value of rolling resistance Fr in the target section is calculated by the energy consumption predicting unit  130 . Specifically, the energy consumption predicting unit  130  calculates it on the basis of the traveling distance information of the target section obtained in step S 102  as illustrated in the following formula (5).
 
[Formula 4]
 
INTEGRATED VALUE OF ROLLING RESISTANCE  Fr=μWg*d   (5)
 
     In the formula (5), μ indicates the rolling resistance coefficient, W indicates the vehicle weight, g indicates the gravity acceleration, and d indicates the traveling distance of the target section. 
     Further, in step S 105 , the air resistance correction coefficient α of the target section is calculated by the correction coefficient calculating unit  150 . Specifically, the correction coefficient calculating unit  150  calculates it on the basis of the average vehicle speed V ave  of the target section and the correction coefficient calculating function f 1  as illustrated in the following formula (6). The correction coefficient calculating function f 1  is a function used when the traveling section is not inclined and stored in the correction coefficient storing unit  140 .
 
[Formula 5]
 
AIR RESISTANCE CORRECTION COEFFICIENT α= f   1 ( V   ave )  (6)
 
     On the other hand, in step S 103 , when it is judged that the target section is inclined, the routine proceeds to step S 106 . In step S 106 , since it is judged that the target section is inclined, inclination resistance Fi of the target section is calculated by the energy consumption predicting unit  130 . Specifically, the energy consumption predicting unit  130  calculates it on the basis of the following formula (7).
 
[Formula 6]
 
INTEGRATED VALUE OF INCLINATION RESISTANCE  Fi=Wg  sin θ* d   (7)
 
     In the formula (7), W indicates the vehicle weight, g indicates the gravity acceleration, θ indicates the inclination of the target section, and d indicates the traveling distance of the target section. 
     In step S 107 , the integrated value of the rolling resistance Fr of the target section is calculated similarly to step S 104 . 
     Then, in step S 108 , the air resistance correction coefficient of the target section is calculated by the correction coefficient calculating unit  150 . In step S 108 , it is judged that the target section is inclined. For that reason, the correction coefficient calculating unit  150  calculates the air resistance correction coefficient α of the target section on the basis of the inclination angle θ of the target section, the average vehicle speed V ave  of the target section, and the correction coefficient calculating function f 2  as illustrated in the following formula (8). The correction coefficient calculating function f 2  is a function used when the traveling section is inclined.
 
[Formula 7]
 
AIR RESISTANCE CORRECTION COEFFICIENT α= f   2 ( V   ave ,θ)  (8)
 
     In step S 109 , the integrated value of the air resistance Fa of the target section is calculated by the energy consumption predicting unit  130 . Specifically, the energy consumption predicting unit  130  calculates it on the basis of the traveling distance d of the target section and the average speed V ave  of the target section obtained in step S 102  as illustrated in the following formula (9).
 
[Formula 8]
 
INTEGRATED VALUE OF AIR RESISTANCE  Fa=kV   2   *d   (9)
 
     In the formula (9), k is a parameter relating to air resistance which includes air resistance coefficient or the projected area of the vehicle. 
     In step S 110 , the integrated value of air resistance Fa calculated in step S 109  is corrected by the energy consumption predicting unit  130 . Specifically, the energy consumption predicting unit  130  corrects it on the basis of the air resistance correction coefficient α calculated in step S 105  or step S 108  and the integrated value of the air resistance Fa calculated in step S 109  as illustrated in the following formula (10). In the description below, the integrated value of the air resistance Fa which is corrected in step S 110  will be described as the integrated value of the air resistance correction value Fa′.
 
[Formula 9]
 
INTEGRATED VALUE OF AIR RESISTANCE CORRECTION VALUE  Fa ′=INTEGRATED VALUE OF AIR RESISTANCE  Fa *AIR RESISTANCE CORRECTION COEFFICIENT α  (10)
 
     Next, in step S 111 , it is judged whether the target section is inclined similarly to step S 103 . When the target section is not inclined, the routine proceeds to step S 112 . On the other hand, when the target section is inclined, the routine proceeds to step S 113 . 
     In step S 112 , the loss correction coefficient  13  of the target section is calculated by the correction coefficient calculating unit  150 . In step S 112 , it is determined that the process target section is not inclined. For that reason, the correction coefficient calculating unit  150  calculates it on the basis of the average speed V ave  of the target section obtained in step S 102  and the loss calculating function f 3  as illustrated in the following formula (11). The loss calculating function f 3  is a function used when the traveling section is not inclined and stored in the correction coefficient storing unit  140 .
 
[Formula 10]
 
LOSS CORRECTION COEFFICIENT β= f   3 ( V   ave )  (11)
 
     On the other hand, in step S 111 , when it is judged that the target section is inclined, the routine proceeds to step S 113 . In step S 113 , it is determined that the target section is inclined. For that reason, the correction coefficient calculating unit  150  calculates the loss correction coefficient β of the target section on the basis of the average speed V ave  of the target section obtained in step S 102  and the loss calculating function f 4  as illustrated in the following formula (12). The loss calculating function f 4  is a function used when the traveling section is inclined and stored in the correction coefficient storing unit  140 .
 
[Formula 11]
 
LOSS CORRECTION COEFFICIENT β= f   4 ( V   ave ,θ)  (12)
 
     Then, in step S 114 , the integrated value of loss L in the drive-train of the target section is calculated by the energy consumption predicting unit  130 . Specifically, the energy consumption predicting unit  130  calculates it on the basis of the integrated value of the air resistance correction value Fa′ calculated in step S 110  and the integrated value of the rolling resistance Fr calculated in step S 104  or step S 107  as illustrated in the following formula (13). 
     
       
         
           
             
               
                 
                   
                       
                   
                   ⁢ 
                   
                     [ 
                     
                       Formula 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       12 
                     
                     ] 
                   
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     INTEGRATED 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     VALUE 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     OF 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     LOSS 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     L 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     IN 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     DRIVE 
                     ⁢ 
                     
                       - 
                     
                     ⁢ 
                     TRAIN 
                   
                   = 
                   
                     
                       
                         
                           
                             ( 
                             
                               ( 
                               
                                 
                                   INTEGRATED 
                                   ⁢ 
                                   
                                       
                                   
                                   ⁢ 
                                   VALUE 
                                   ⁢ 
                                   
                                       
                                   
                                   ⁢ 
                                   OF 
                                   ⁢ 
                                   
                                       
                                   
                                   ⁢ 
                                   ROLLING 
                                   ⁢ 
                                   
                                       
                                   
                                   ⁢ 
                                   RESISTANCE 
                                   ⁢ 
                                   
                                       
                                   
                                   ⁢ 
                                   Fr 
                                 
                                 + 
                               
                             
                           
                         
                       
                       
                         
                           
                             
                               INTEGRATED 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               VALUE 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               OF 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               AIR 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               RESISTANCE 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               
                                 Fa 
                                 ′ 
                               
                             
                             ) 
                           
                         
                       
                     
                     
                       
                         
                           
                             
                               MOTOR 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               EFFICIENCY 
                               * 
                               GEAR 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               EFFICIENCY 
                             
                             - 
                           
                         
                       
                       
                         
                           
                             
                               
                                 
                                   ( 
                                   
                                     ( 
                                     
                                       
                                         INTEGRATED 
                                         ⁢ 
                                         
                                             
                                         
                                         ⁢ 
                                         VALUE 
                                         ⁢ 
                                         
                                             
                                         
                                         ⁢ 
                                         OF 
                                         ⁢ 
                                         
                                             
                                         
                                         ⁢ 
                                         ROLLING 
                                         ⁢ 
                                         
                                             
                                         
                                         ⁢ 
                                         RESISTANCE 
                                         ⁢ 
                                         
                                             
                                         
                                         ⁢ 
                                         Fr 
                                       
                                       + 
                                     
                                   
                                 
                               
                             
                             
                               
                                 
                                   
                                     INTEGRATED 
                                     ⁢ 
                                     
                                         
                                     
                                     ⁢ 
                                     VALUE 
                                     ⁢ 
                                     
                                         
                                     
                                     ⁢ 
                                     OF 
                                     ⁢ 
                                     
                                         
                                     
                                     ⁢ 
                                     AIR 
                                     ⁢ 
                                     
                                         
                                     
                                     ⁢ 
                                     RESISTANCE 
                                     ⁢ 
                                     
                                         
                                     
                                     ⁢ 
                                     
                                       Fa 
                                       ′ 
                                     
                                   
                                   ) 
                                 
                               
                             
                           
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   13 
                   ) 
                 
               
             
           
         
       
     
     In step S 115 , the integrated value of the loss L in the drive-train in the target section calculated in step S 114  is corrected by the energy consumption predicting unit  130 . Specifically, the energy consumption predicting unit  130  corrects it on the basis of the integrated value of the loss L in the drive-train calculated in step S 114  and the loss correction coefficient β calculated in step S 112  or step S 113  as illustrated in the following formula (14). Further, in the description below, the integrated value of the loss L corrected in step S 115  will be described as the integrated value of the loss correction value L′.
 
[Formula 13]
 
INTEGRATED VALUE OF LOSS CORRECTION VALUE  L ′=INTEGRATED VALUE OF LOSS  L *(LOSS CORRECTION COEFFICIENT β)  (14)
 
     In step S 116 , the energy consumption predicting unit  130  judges whether the processes of step S 103  to step S 115  are performed in all traveling sections of the recommended route. When the processes of step S 103  to step S 115  are performed in all traveling sections of the recommended route, the routine proceeds to step S 117 . On the other hand, when there is a traveling section in which the processes of step S 103  to step S 115  are not performed, the routine returns to step S 103  so as to perform the processes of step S 103  to step S 115  in the traveling section in which the processes are not performed yet. 
     Next, in step S 117 , the energy consumption from the current position to the destination is predicted by the energy consumption predicting unit  130 . Specifically, the energy consumption predicting unit  130  adds the integrated value of the rolling resistance Fr, the integrated value of the inclination resistance Fi, the integrated value of the air resistance correction value Fa′, and the integrated value of the loss corrected value L′ in each traveling section of the recommended route. The added integrated value is the energy consumption each traveling section. The energy consumption predicting unit  130  sums up the energy consumption of the traveling sections as the energy consumption of the recommended route. Specifically, the energy consumption predicting unit  130  calculates the energy consumption of the recommended route on the basis of the following formula (15). The information of the energy consumption predicted by the energy consumption predicting unit  130  is transmitted to the display unit  180 . 
     
       
         
           
             
               
                 
                   
                       
                   
                   ⁢ 
                   
                     [ 
                     
                       Formula 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       14 
                     
                     ] 
                   
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     ENERGY 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     CONSUMPTION 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     TO 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     DESTINATION 
                   
                   = 
                   
                     ∑ 
                     
                       ( 
                       
                         
                           
                             
                               INTEGRATED 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               VALUE 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               OF 
                             
                           
                         
                         
                           
                             
                               
                                 ROLLING 
                                 ⁢ 
                                 
                                     
                                 
                                 ⁢ 
                                 RESISTANCE 
                                 ⁢ 
                                 
                                     
                                 
                                 ⁢ 
                                 Fr 
                               
                               + 
                             
                           
                         
                         
                           
                             
                               
                                 INTEGRATED 
                                 ⁢ 
                                 
                                     
                                 
                                 ⁢ 
                                 VALUE 
                                 ⁢ 
                                 
                                     
                                 
                                 ⁢ 
                                 OF 
                                 ⁢ 
                                 
                                     
                                 
                                 ⁢ 
                                 INCLINATION 
                               
                               ⁢ 
                               
                                   
                               
                             
                           
                         
                         
                           
                             
                               
                                 RESISTANCE 
                                 ⁢ 
                                 
                                     
                                 
                                 ⁢ 
                                 Fi 
                               
                               ⁢ 
                               
                                   
                               
                               + 
                             
                           
                         
                         
                           
                             
                               INTEGRATED 
                               ⁢ 
                               
                                   
                               
                             
                           
                         
                         
                           
                             
                               VALUE 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               OF 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               AIR 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               RESISTANCE 
                             
                           
                         
                         
                           
                             
                               
                                 CORRECTION 
                                 ⁢ 
                                 
                                     
                                 
                                 ⁢ 
                                 VALUE 
                                 ⁢ 
                                 
                                     
                                 
                                 ⁢ 
                                 
                                   Fa 
                                   ′ 
                                 
                               
                               + 
                             
                           
                         
                         
                           
                             
                               INTEGRATED 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               VALUE 
                             
                           
                         
                         
                           
                             
                               OF 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               LOSS 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               CORRECTION 
                             
                           
                         
                         
                           
                             
                               VALUE 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               
                                 L 
                                 ′ 
                               
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               IN 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               DRIVE 
                               ⁢ 
                               
                                 - 
                               
                               ⁢ 
                               TRAIN 
                             
                           
                         
                       
                       ) 
                     
                   
                 
               
               
                 
                   ( 
                   15 
                   ) 
                 
               
             
           
         
       
     
     In step S 118 , the charging necessity determining unit  160  determines whether to charge the battery until the vehicle reaches the destination on the basis of the predicted energy consumption to the destination in step S 117 . Specifically, the charging necessity determining unit  160  determines that the battery needs to be charged when the energy consumption to the destination is larger than the remaining amount of battery energy. The charging necessity determining unit  160  determines that the battery does not need to be charged when the energy consumption to the destination is equal to or smaller than the remaining amount of battery energy. The result determined by the charging necessity determining unit  160  is transmitted to the display unit  180 . 
     In step S 118 , when it is determined that the battery needs to be charged, the routine proceeds to step S 119 . In step S 119 , the charging station around the vehicle is searched by the charging station searching unit  170 . Specifically, the charging station searching unit  170  searches for the charging station at which the vehicle can arrive by the remaining amount of current battery energy on the basis of the map information obtained by the map database  400  and the current position of the vehicle detected by the own vehicle position detecting device  300 . Then, the information of the charging station searched by the charging station searching unit  170  is transmitted to the display unit  180 . 
     In step S 120 , the display unit  180  display the information including the energy consumption to the destination on the display  500  to suggest the passenger. Specifically, the display unit  180  displays the information including the energy consumption to the destination predicted in step S 117 , the charging necessity determination result in step S 118 , and the position of the charging station searched in step S 119  on the screen of the display  500 . Accordingly, these kinds of information are suggested to the passenger. 
     As described above, in the first embodiment of the present invention, the integrated value of air resistance to the destination is corrected in consideration of the air resistance caused by the acceleration of the vehicle when the energy consumption to the destination is predicted. Further, the integrated value of loss in the drive-train to the destination is corrected in consideration of the loss in the drive-train caused by the acceleration of the vehicle. Accordingly, in the embodiment, it is possible to highly precisely predict the integrated value of air resistance to the destination and the integrated value of loss in the drive-train. As a result, it is possible to appropriately predict the energy consumption to the destination. Particularly, since the electric vehicle has a feature that the battery is heavy and the traveling distance is short compared to an engine vehicle, it is desirable to highly precisely determine whether the vehicle reaches the destination. In the embodiment, it is possible to highly precisely predict the energy consumption to the destination in such a case. As a result, it is possible to highly precisely determine whether the vehicle reaches the destination. 
       FIG. 11  is a graph illustrating an example of a temporal transition of the actual vehicle speed, the average vehicle speed, and the integrated value of actual air resistance in a predetermined traveling section. In  FIG. 11 , the graph also illustrates the integrated value of air resistance predicted on the basis of the formula (2) and the integrated value of air resistance predicted on the basis of the formula (10) in a predetermined traveling section. In  FIG. 11 , the actual vehicle speed and the average vehicle speed are respectively indicated by a dashed line. In  FIG. 11 , the integrated value of actual air resistance, the integrated value of air resistance predicted on the basis of the formula (2), and the integrated value of air resistance predicted on the basis of the formula (10) are respectively indicated by a solid line. Further, the actual vehicle speed and the average vehicle speed of  FIG. 11  correspond to the vehicle speed (km/h) at the left side of the graph. And the integrated value of actual air resistance, the integrated value of air resistance predicted on the basis of the formula (2), and the integrated value of air resistance predicted on the basis of the formula (10) correspond to the integrated value of air resistance (kJ) at the right side of the graph in  FIG. 11 . Further, the actual air resistance is the air resistance obtained by an experiment from the profile of the travel speed when the vehicle actually travels in the traveling section (the same applies to  FIGS. 12 and 13  below). 
     The air resistance is proportional to the square of the vehicle speed when the vehicle travels at a constant vehicle speed. On the contrary, the air resistance is proportional to the cube of the vehicle speed when the vehicle is accelerated. For that reason, as illustrated in  FIG. 12 , an error was caused between the actual air resistance (indicated by white bar graph in  FIG. 12 ) and the air resistance predicted on the basis of the constant average vehicle speed V ave  as illustrated in the formula (2) (indicated by diagonal hatching bar graph in  FIG. 12 ) as much as the vehicle accelerates. For example, in the example illustrated in  FIG. 12 , the air resistance predicted on the basis of the formula (2) is approximately ¼ of the actual air resistance at maximum. On the contrary, since the air resistance (indicated by gray bar graph in  FIG. 12 ) predicted by the air resistance correction coefficient α as illustrated in the formula (10) corrects the air resistance in consideration of the acceleration of the vehicle, the air resistance substantially is equal to the actual air resistance. 
       FIG. 12  is a graph illustrating an example of the integrated value of actual air resistance (indicated by white bar graph in  FIG. 12 ) in a predetermined traveling section, the integrated value of air resistance predicted from the average vehicle speed V ave  of the traveling section on the basis of the formula (2) (indicated by diagonal hatching bar graph in  FIG. 12 ), and the integrated value of air resistance predicted by using the air resistance correction coefficient α on the basis of the formula (10) (indicated by gray bar graph in  FIG. 12 ). Further,  FIG. 12  illustrates the air resistance predicted on the basis of the formula (10) and the air resistance predicted on the basis of the formula (2) while the actual air resistance by an experiment is set as 100%. 
     More specifically, as illustrated in  FIG. 12 , when the vehicle speed is low, an error between the actual air resistance and the air resistance predicted on the basis of the formula (2) is approximately 60%. On the contrary, an error between the actual air resistance and the air resistance predicted on the basis of the formula (10) is approximately 5%. In the air resistance predicted on the basis of the formula (10), the error with respect to the actual air resistance is small compared to the air resistance predicted on the basis of the formula (2). Similarly, even when the vehicle speed is medium, an error with respect to the actual air resistance is small in the air resistance predicted on the basis of the formula (10) compared to the air resistance predicted on the basis of the formula (2). 
     In this way, the navigation device  1  of the embodiment corrects the integrated value of air resistance calculated on the basis of the constant average vehicle speed V ave  as illustrated in the formula (10) in consideration of the air resistance increased by acceleration. Accordingly, it is possible to effectively prevent a problem in which the integrated value of air resistance of the traveling section is predicted as a value smaller than the integrated value of actual air resistance. Further, the navigation device  1  of the embodiment calculates the air resistance correction coefficient α so that the integrated value of air resistance in the traveling section is larger according as the average vehicle speed V ave  in the traveling section is lower. Then, the navigation device  1  corrects the integrated value of air resistance on the basis of the calculated air resistance correction coefficient α. Accordingly, even when the average vehicle speed V ave  is low and the frequency of acceleration is high in the traveling section, it is possible to appropriately predict the integrated value of air resistance. 
     Further, the navigation device  1  of the embodiment calculates the air resistance correction coefficient α so that the integrated value of air resistance in the traveling section is small when the traveling section is inclined. Because there is a tendency that the frequency of acceleration is low when the traveling section is inclined compared to a case in which the traveling section is not inclined. Accordingly, even when the traveling section is inclined, it is possible to appropriately predict the air resistance in the traveling section. 
       FIG. 13  is a graph illustrating an example of the integrated value of actual air resistance when the traveling section is inclined (indicated by white bar graph in  FIG. 13 ), the integrated value of air resistance predicted by using the air resistance correction coefficient α of the traveling section being flat (indicated by gray bar graph in  FIG. 13 ), and the integrated value of air resistance predicted by using the air resistance correction coefficient α of the traveling section being inclined (indicated by horizontal hatching bar graph in  FIG. 13 ). 
     As illustrated in  FIG. 13 , in a case in which the traveling section is a downhill having a predetermined inclination, when the integrated value of air resistance is predicted by using the air resistance correction coefficient α of the traveling section being flat, the predicted integrated value of air resistance is larger than the integrated value of actual air resistance by about 30%. On the contrary, in the same case, when the integrated value of air resistance is predicted by using the air resistance correction coefficient α of the traveling section being inclined, the predicted integrated value of air resistance is larger than the integrated value of actual air resistance by about 10%. That is, when the integrated value of air resistance is predicted by using the air resistance correction coefficient cc of the traveling section being inclined, it is possible to predict a value substantially equal to the actual air resistance compared to using the air resistance correction coefficient α of the traveling section being flat. Similarly, even in a case in which the traveling section is an uphill having a predetermined inclination, when the integrated value of air resistance is predicted by the air resistance correction coefficient α of the traveling section being inclined, it is possible to predict a value close to the actual air resistance compared to using the air resistance correction coefficient α of the traveling section being flat. In this way, the navigation device  1  of the embodiment can effectively prevent a problem in which the integrated value of air resistance to the destination is predicted as a value larger than the integrated value of actual air resistance. Because when the traveling section is inclined, the navigation device  1  predicts the integrated value in consideration of the inclination of the traveling section, and predicts by using the air resistance correction coefficient α of the traveling section being inclined. 
     Further, the navigation device  1  of the embodiment corrects the integrated value of loss in the drive-train calculated on the basis of the average vehicle speed of the traveling section as illustrated in the formula (3). Because the loss in the drive-train such as the motor or the gear increases when the vehicle is accelerated. 
       FIG. 14  is a graph illustrating an example of a temporal transition of the actual vehicle speed, the average vehicle speed, and the integrated value of actual loss in the drive-train in a predetermined traveling section. In  FIG. 14 , the graph also illustrates the integrated value of loss in the drive-train predicted on the basis of the average vehicle speed V ave  in the traveling section as illustrated in the formula (3) and the integrated value of loss in the drive-train predicted on the basis of the loss correction coefficient β as illustrated in the formula (14). In  FIG. 14 , the actual vehicle speed and the average vehicle speed of the traveling section are respectively indicated by a dashed line. In  FIG. 14 , the integrated value of actual loss in the drive-train, the integrated value of loss in the drive-train predicted on the basis of the formula (3), and the integrated value of loss in the drive train predicted on the basis of the formula (10) are respectively indicated by a solid line. Further, in  FIG. 14 , the actual vehicle speed and the average vehicle speed V ave  in the traveling section correspond to the vehicle speed (km/h) at the left side of the graph. The integrated value of actual loss in the drive-train in the traveling section, the integrated value of loss in the drive-train predicted on the basis of the formula (3), and the integrated value of loss in the drive-train predicted on the basis of the formula (14) correspond to the integrated value of loss (kJ) in the drive-train at the right side of the graph. The actual loss in the drive-train is the loss obtained by an experiment from the profile of the travel speed obtained when the vehicle actually travels in the traveling section (the same applies to  FIGS. 15 and 16  below). 
     When the vehicle is accelerated, the loss in the drive-train includes the loss caused by the inertia moment and the loss caused by the travel resistance. For that reason, as illustrated in  FIG. 15 , an error is caused between the integrated value of actual loss in the drive-train and the integrated value of loss in the drive-train predicted on the basis of the formula (3) as much as the vehicle accelerates. For example, in the example illustrated in  FIG. 15 , the integrated value of loss in the drive-train predicted on the basis of the formula (3) is approximately ⅙ of the actual loss in the drive-train at maximum. On the contrary, as illustrated in the formula (14), the integrated value of loss in the drive-train predicted by using the loss correction coefficient β corrects the loss in the drive-train in consideration of the acceleration of the vehicle. Therefore, the integrated value of loss is substantially equal to the actual loss in the drive-train. 
       FIG. 15  is a graph illustrating an example of the integrated value of actual loss in the drive-train in a predetermined traveling section (indicated by white bar graph in  FIG. 15 ), the integrated value of loss in the drive-train predicted by using the average vehicle speed V ave  on the basis of the formula (3) (indicated by diagonal hatching bar graph in  FIG. 15 ), and the integrated value of loss in the drive-train predicted by using the loss correction coefficient β on the basis of the formula (14) (indicated by gray bar graph in  FIG. 15 ).  FIG. 15  illustrates the integrated value of loss in the drive-train predicted on the basis of the formula (3) and the integrated value of loss in the drive-train predicted on the basis of the formula (14) while the integrated value of actual loss in the drive-train by an experiment is set as 100%. 
     As illustrated in  FIG. 15 , when the vehicle speed is low, an error between the integrated value of actual loss in the drive-train and the integrated value of loss in the drive-train predicted on the basis of the formula (3) is 70%. On the contrary, an error between the integrated value of actual loss in the drive-train and the integrated value of loss in the drive-train predicted on the basis of the formula (14) is 5%. With respect to the integrated value of actual loss in the drive-train, an error of the integrated value of loss in the drive-train predicted on the basis of the formula (14) is small compared to an error of the integrated value of loss in the drive-train predicted on the basis of the formula (3). Similarly, even when the vehicle speed is medium or high, with respect to the integrated value of actual loss in the drive-train, an error of the integrated value of loss in the drive-train predicted on the basis of the formula (14) is small compared to an error of the integrated value of loss in the drive-train predicted on the basis of the formula (3). 
     In this way, the navigation device  1  of the embodiment corrects the integrated value of loss in the drive-train calculated on the basis of the average vehicle speed V ave  in consideration of the loss in the drive-train increased by acceleration as illustrated in the formula (14). Accordingly, it is possible to effectively prevent a problem in which the integrated value of loss in the drive-train in the traveling section is predicted as a value smaller than the actual loss in the drive-train. Further, the navigation device  1  of the embodiment calculates the loss correction coefficient β so that the integrated value of loss in the drive-train is larger according as the average vehicle speed V ave  is lower. Then, the navigation device  1  corrects the integrated value of loss in the drive-train on the basis of the calculated loss correction coefficient β. Accordingly, even in the traveling section in which the average vehicle speed V ave  is low and the frequency of acceleration is high, it is possible to appropriately predict the integrated value of loss in the drive-train in the traveling section. 
     Further, the navigation device  1  calculates the loss correction coefficient  13  so that the integrated value of loss in the drive-train is large when the traveling section is inclined compared to a case in which the traveling section is not inclined. Because the amount of work is large when the traveling section is inclined compared to a case in which the traveling section is not inclined. Accordingly, even when the traveling section is inclined, it is possible to appropriately predict the loss in the drive-train in the traveling section. 
       FIG. 16  is a graph illustrating an example of the integrated value of actual loss in the drive-train when the traveling section is inclined (indicated by white bar graph in  FIG. 16 ), the integrated value of loss in the drive-train predicted by using the loss correction coefficient  13  of the traveling section being flat (indicated by gray bar graph in  FIG. 16 ), and the integrated value of loss in the drive-train predicted by using the loss correction coefficient β of the traveling section being inclined (indicated by a horizontal line bar graph in  FIG. 16 ). 
     As illustrated in  FIG. 16 , in a case in which the traveling section is a downhill having a predetermined inclination, when the integrated value of loss in the drive-train is predicted by using the loss correction coefficient β of the traveling section being flat, the predicted integrated value of loss is smaller than the integrated value of actual loss by about 10%. On the contrary, in the same case, when the integrated value of loss in the drive-train is predicted by using the loss correction coefficient β of the traveling section being inclined, the predicted integrated value of loss in the drive-train is larger than the integrated value of actual loss by about 5%. That is, when the integrated value of loss in the drive-train is predicted by using the loss correction coefficient β of the traveling section being inclined, it is possible to predict a value substantially equal to the integrated value of actual loss of the drive-train compared to a case in which the integrated value of loss in the drive-train is predicted by using the loss correction coefficient β of the traveling section being flat. 
     Similarly, even in a case in which the traveling section is an uphill having a predetermined inclination, when the integrated value of loss in the drive-train is predicted by using the loss correction coefficient β of the traveling section being inclined, it is possible to predict a value close to the actual loss in the drive-train compared to a case in which the integrated value of loss in the drive-train is predicted by using the loss correction coefficient β of the traveling section being flat. In this way, the loss correction coefficient β of the traveling section being inclined is used when the traveling section is inclined. Then it is possible to effectively prevent a problem in which the integrated value of loss in the drive-train to the destination is predicted as a value smaller than the actual value. 
     Second Embodiment 
     Next, a navigation device according to a second embodiment of the present invention will be described. The navigation device  1  according to the second embodiment is similar to the navigation device  1  according to the first embodiment except that the control device  100  has a function illustrated in  FIG. 17  and is operated as described below.  FIG. 17  is a functional block diagram illustrating a function of the control device  100  according to the second embodiment. 
     In the second embodiment, as illustrated in  FIG. 17 , the control device  100  includes an ambient air temperature obtaining unit  210  configured to obtain an ambient air temperature, a vehicle information obtaining unit  220  configured to obtain vehicle information, and a rolling resistance coefficient calculating unit  230  configured to calculate a rolling resistance coefficient in addition to the function according to the first embodiment. 
     The ambient air temperature obtaining unit  210  obtains an ambient air temperature outside the vehicle. For example, the ambient air temperature obtaining unit  210  can obtain information of the ambient air temperature from an outside air temperature gauge if the vehicle mounts a thermometer detecting the ambient air temperature. Further, the ambient air temperature obtaining unit  210  predicts the ambient air temperature of the vehicle as will be described below even if the vehicle does not mounts the thermometer. 
     That is, the ambient air temperature obtaining unit  210  predicts the ambient air temperature on the basis of a season, a month, a date, a region of the traveling section, and a latitude and a longitude of the traveling section. Accordingly, the ambient air temperature can be obtained. For example, a condition set by the combination of at least one or more of the season, the month, the date, the region, the latitude, and the longitude at the current time point are stored in the navigation device  1  in advance. Further, a correlation with the above condition and the predicted value of ambient air temperature are stored in the navigation device  1  in advance. Alternatively, the condition and the correlation are obtained from a server (not illustrated). Accordingly, it is possible to predict the ambient air temperature outside the vehicle. 
     When the ambient air temperature is predicted on the basis of the combination of the season, the month, the date, the region, the latitude, and the longitude, the predicted value of ambient air temperature is obtained at higher precision (the predicted value of ambient air temperature is obtained at smaller temperature interval) according as the ambient air temperature is lower. For example, when the predicted ambient air temperature is equal to or higher than 10° C., the correlation between the condition and the predicted value of ambient air temperature are stored so that the ambient air temperature obtaining unit  210  predicts the ambient air temperature at the temperature interval equal to or higher than 10° C. On the other hand, when the ambient air temperature is lower than 10° C., the correlation between the condition and the predicted value of ambient air temperature are stored so that the ambient air temperature obtaining unit  210  predicts the ambient air temperature at the temperature interval lower than 5° C. In the second embodiment, the rolling resistance of the vehicle is calculated on the basis of the ambient air temperature as will be described later. In this case, an amount of change of the rolling resistance is larger according as the ambient air temperature is lower. For that reason, the ambient air temperature is predicted at smaller prediction temperature interval according as the ambient air temperature is lower. Accordingly, it is possible to highly precisely calculate the rolling resistance of the vehicle. 
     The vehicle information obtaining unit  220  obtains the vehicle information including a vehicle weight (a vehicle weight except passenger weights), brake hub drag resistance, an air resistance coefficient, and a projected area. The vehicle weight except passenger weights, the brake hub drag resistance, the air resistance coefficient, and the projected area are different in accordance with the type of vehicles. The control device  100  stores these values in advance in the memory in accordance with the type of vehicles. For that reason, the vehicle information obtaining unit  220  can read the vehicle information from the memory of the control device  100 . 
     The rolling resistance coefficient calculating unit  230  calculates the rolling resistance coefficient for obtaining the rolling resistance.  FIG. 18  is a diagram illustrating an example of the correlation between the ambient air temperature and the rolling resistance coefficient. As illustrated in  FIG. 18 , there is a tendency that the rolling resistance coefficient of the tire of the vehicle is larger according as the ambient air temperature is lower and the rolling resistance coefficient of the tire is smaller according as the ambient air temperature is higher. For that reason, for example, the correlation between the ambient air temperature and the rolling resistance coefficient as illustrated in  FIG. 18  is stored as a table control map. Accordingly, the rolling resistance coefficient calculating unit  230  can calculate the rolling resistance coefficient from the ambient air temperature by referring to the table control map. Further, as another configuration, the correlation between the ambient air temperature and the rolling resistance coefficient is stored as a function. Then, the rolling resistance coefficient calculating unit  230  may calculate the rolling resistance coefficient from the ambient air temperature. Alternatively, as another configuration, the rolling resistance coefficient calculating unit  230  calculates a correction coefficient of rolling resistance from the ambient air temperature on the basis of the correlation between the ambient air temperature and the correction coefficient of rolling resistance for correcting the rolling resistance coefficient. Then, the rolling resistance coefficient calculating unit  230  corrects the rolling resistance coefficient by the correction coefficient of rolling resistance. Accordingly, the rolling resistance coefficient calculating unit  230  may calculate the rolling resistance coefficient. 
     There is a case in which the correlation between the ambient air temperature and the rolling resistance coefficient is different in accordance with the type of vehicles or the vehicle equipment (for example, the type of the drive-train or the tire). In this case, the rolling resistance coefficient calculating unit  230  can calculate the rolling resistance coefficient from the ambient air temperature by referring to the correlation between the ambient air temperature and the rolling resistance coefficient in accordance with the type of vehicles or the vehicle equipment. Further, as another configuration, the correction coefficient of rolling resistance is stored in advance in accordance with the type of vehicles or the vehicle equipment. Then, the rolling resistance coefficient calculating unit  230  obtains the correction coefficient of rolling resistance in accordance with the type of vehicles or the vehicle equipment. Accordingly, the rolling resistance coefficient calculating unit  230  may calculate the rolling resistance coefficient on the basis of the correction coefficient of rolling resistance. 
     Further, the correction coefficient calculating unit  150  according to the second embodiment calculates the loss correction coefficient in consideration of the ambient air temperature obtained by the ambient air temperature obtaining unit  210 .  FIG. 19  is a graph illustrating an example of the correlation of the rolling resistance, the average vehicle speed, and the loss correction coefficient. As described above, the rolling resistance changes in response to the ambient air temperature. For that reason, the correction coefficient calculating unit  150  predicts the rolling resistance in response to the ambient air temperature. Then, the correction coefficient calculating unit  150  calculates the loss correction coefficient on the basis of the predicted rolling resistance and the average vehicle speed V ave . Specifically, the correction coefficient calculating unit  150  calculates the loss correction coefficient as a small value as the rolling resistance increases (or the ambient air temperature decreases) at the same average vehicle speed V ave . 
     Further, the correction coefficient calculating unit  150  calculates the loss correction coefficient in consideration of the vehicle information obtained by the vehicle information obtaining unit  220 .  FIG. 20  is a diagram illustrating an example of the loss correction coefficient for each type of vehicles. Since the vehicle information such as the vehicle weight except passenger weights, the brake hub drag resistance, the air resistance coefficient, and the entire surface projected area is different in accordance with each type of vehicles, the travel resistance is different in accordance with the type of vehicles. For that reason, as illustrated in  FIG. 20 , the correction coefficient calculating unit  150  calculates the loss correction coefficient in accordance with the type of vehicles on the basis of the vehicle information obtained by the vehicle information obtaining unit  220  so that the loss correction coefficient is smaller in the type of vehicles having higher travel resistance. For example, in the example illustrated in  FIG. 20 , the travel resistance is high in order of the vehicle C, the vehicle B, and the vehicle A. In this case, as illustrated in  FIG. 20 , the loss correction coefficient is calculated as a large value in order of the vehicle A, the vehicle B, and the vehicle C. 
     Further, the energy consumption predicting unit  130  according to the second embodiment predicts the energy consumption from the current position to the destination by the loss correction coefficient calculated by the correction coefficient calculating unit  150 . Further, in the second embodiment, the energy consumption predicting unit  130  calculates the air resistance Fa by using the parameter relating to air resistance which includes the ambient air temperature and the vehicle information. Then, the energy consumption predicting unit  130  predicts the energy consumption from the current position to the destination on the basis of the calculated air resistance. 
     Subsequently, a process or sequence for predicting energy consumption according to the second embodiment will be described with reference to  FIGS. 21 and 22 .  FIGS. 21 and 22  are flowcharts illustrating the process or sequence for predicting the energy consumption according to the second embodiment. For example, the process is also performed in a manner such that the passenger inputs the destination through the input device  200 . 
     In step S 201  and step S 202 , the same processes as those of step S 101  and step S 102  of the first embodiment are performed. That is, the recommended route from the current position to the destination is searched (step S 201 ). Then, the road information of the searched recommended route is obtained (step S 202 ). 
     In step S 203 , the ambient air temperature outside the vehicle is obtained by the ambient air temperature obtaining unit  210  of the control device  100 . For example, the ambient air temperature obtaining unit  210  obtains the information of the ambient air temperature from the thermometer mounted in the vehicle. Alternatively, the ambient air temperature obtaining unit  210  predicts the ambient air temperature outside the vehicle on the basis of the combination of at least one or more of the season, the month, the date, the region of the traveling section, and the latitude and the longitude of the traveling section at the current time point. Accordingly, the ambient air temperature obtaining unit  210  can obtain the ambient air temperature outside the vehicle. 
     In step S 204 , the vehicle information is obtained by the vehicle information obtaining unit  220  of the control device  100 . Specifically, the vehicle information obtaining unit obtains the vehicle information including the vehicle weight, the brake hub drag resistance, the air resistance coefficient, and the entire surface projected area from the memory of the control device  100 . 
     In step S 205 , the rolling resistance coefficient is calculated by the rolling resistance coefficient calculating unit  230  of the control device  100 . For example, the rolling resistance coefficient calculating unit  230  can calculate the rolling resistance coefficient μ on the basis of the ambient air temperature obtained in step S 203  by referring to the correlation between the rolling resistance coefficient and the ambient air temperature illustrated in  FIG. 18 . Then, in subsequent step S 206 , the integrated value of the rolling resistance Fr of the target section is calculated on the basis of the rolling resistance coefficient μ calculated in step S 205  similarly to step S 104  of the first embodiment. As illustrated in the formula (4), the rolling resistance Fr is proportional to the rolling resistance coefficient μ, and the value of the rolling resistance Fr is larger according as the value of the rolling resistance coefficient μ is larger. For that reason, as the ambient air temperature is lower, the rolling resistance coefficient μ is larger and the rolling resistance Fr is also higher. 
     In step S 207 , it is judged whether the target section is inclined similarly to step S 103  of the first embodiment. When the target section is not inclined, the routine proceeds to step S 208 . In step S 208 , the air resistance correction coefficient α of the target section is calculated on the basis of the average vehicle speed V ave  of the target section and the correction coefficient calculating function f 1  of the traveling section being not inclined similarly to step S 105  of the first embodiment. On the other hand, when the target section is inclined, the routine proceeds to step S 209 . In step S 209 , the inclination resistance Fi of the target section is calculated similarly to step S 106  of the first embodiment. In subsequent step S 210 , the air resistance correction coefficient α of the target section is calculated on the basis of the correction coefficient calculating function f 2  of the traveling section being inclined, the average vehicle speed V ave  of the target section, and the inclination θ of the process target section similarly to step S 108  of the first embodiment. 
     In step S 211 , the integrated value of the air resistance Fa of the target section is calculated by the energy consumption predicting unit  130 . Specifically, in the second embodiment, the energy consumption predicting unit  130  calculates the integrated value of the air resistance Fa on the basis of the formula (16) as below.
 
[Formula 15]
 
INTEGRATED VALUE OF AIR RESISTANCE  Fa=k′V   2   *d   (16)
 
     In the formula (16), k′ indicates a parameter relating to the air resistance. The parameter k′ is set in response to the ambient air temperature obtained in step S 203  or the vehicle information such as the vehicle weight, the brake hub drag resistance, the air resistance coefficient, and the entire surface projected area obtained in step S 204 . Further, in the formula (16), V indicates the average vehicle speed in the target section obtained in step S 202 . In the formula (16), d indicates a traveling distance of the target section. 
     In step S 212 , the integrated value of the air resistance Fa of the target section is corrected on the basis of the air resistance correction coefficient α calculated in step S 208  or step S 210  and the integrated value of the air resistance Fa calculated in step S 211  similarly to step S 110  of the first embodiment. 
     Then, as illustrated in  FIG. 22 , in step S 213 , it is judged whether the target section is inclined similarly to step S 207 . When the target section is not inclined, the routine proceeds to step S 214 . On the other hand, when the target section is inclined, the routine proceeds to step S 215 . 
     In step S 214 , the loss correction coefficient of the target section is calculated by the correction coefficient calculating unit  150 . In the second embodiment, the correction coefficient calculating unit  150  calculates the loss correction coefficient of the target section in consideration of the ambient air temperature obtained in step S 203  and the vehicle information obtained in step S 204 . Specifically, the correction coefficient calculating unit  150  stores the function f 5  of the traveling section being not inclined in the correction coefficient storing unit  140 . As illustrated in  FIGS. 19 and 20 , the function f 5  indicates the correlation between the average speed V ave  of the vehicle and the loss correction coefficient β, and corresponds to the rolling resistance and the type of vehicles. As below, the correction coefficient calculating unit  150  calculates the loss correction coefficient β of the traveling section being not inclined. The loss correction coefficient β is corresponding to the rolling resistance, the type of vehicles, and the average vehicle speed V ave  at the current time point. The correction coefficient calculating unit  150  calculates the loss correction coefficient β on the basis of the vehicle information k″, the ambient air temperature t, and the average vehicle speed V ave  of the target section as illustrated in the formula (17).
 
[Formula 16]
 
LOSS CORRECTION COEFFICIENT β= f   5 ( V   ave   ,t,k ″)  (17)
 
     Further, the method for calculating the loss correction coefficient β is not limited to the formula (17). For example, the loss correction coefficient β may be calculated by the rolling resistance calculated in step S 205 . 
     In step S 213 , when it is judged that the target section is inclined, the routine proceeds to step S 215 . Even in this case, the correction coefficient calculating unit  150  calculates the loss correction coefficient of the target section in consideration of the ambient air temperature obtained in step S 203  and the vehicle information obtained in step S 204 . Specifically, the correction coefficient calculating unit  150  stores the function f 6  of the traveling section being inclined in the correction coefficient storing unit  140 . As illustrated in  FIGS. 19 and 20 , the function f 6  indicates the correlation between the average vehicle speed V ave  and the loss correction coefficient β, and corresponds to the rolling resistance and the type of vehicles. As below, the correction coefficient calculating unit  150  calculates the loss correction coefficient β of the traveling section being inclined. The loss correction coefficient β is corresponding to the current rolling resistance, the type of vehicles, the inclination θ, and the average speed V ave  of the vehicle. The correction coefficient calculating unit  150  calculates the loss correction coefficient β on the basis of the vehicle information k″, the ambient air temperature t, the inclination θ, and the average vehicle speed V ave  of the target section as illustrated in the formula (18).
 
[Formula 17]
 
LOSS CORRECTION COEFFICIENT β= f   6 ( V   ave   ,θ,t,k″ )  (18)
 
     In step S 216  to step S 222 , processes is performed as same as those of step S 114  to step S 120  of the first embodiment. That is, the integrated value of loss in the drive-train of the target section is calculated on the basis of the rolling resistance calculated in step S 206  and the air resistance corrected in step S 212  (step S 216 ). The loss L in the drive-train of the target section is corrected on the basis of the loss correction coefficient β calculated in step S 214  or step S 215  and the integrated value of the loss L in the drive-train calculated in step S 216  (step S 217 ). 
     Then, when the processes in step S 203  to step S 217  are performed in all traveling sections in the recommended route (‘Yes’ in step S 218 ), the energy consumption from the current position to the destination is predicted (step S 219 ). It is determined whether the battery needs to be charged by the time the vehicle reaches the destination on the basis of the predicted energy consumption to the destination (step S 220 ). When it is determined that the battery needs to be charged, the charging station around the vehicle is searched (step S 221 ). Subsequently, information including the energy consumption to the destination is displayed on the display  500  for the passenger (step S 222 ). 
     As described above, the navigation device  1  of the second embodiment obtains the ambient air temperature and the vehicle information. The navigation device  1  calculates the rolling resistance coefficient and the loss correction coefficient in consideration of the ambient air temperature and the vehicle information. Then, the navigation device  1  predicts the energy consumption from the current position to the destination by using the rolling resistance coefficient and the loss correction coefficient. Accordingly, the navigation device  1  of the second embodiment can predict the energy consumption in consideration of the ambient air temperature and the type of vehicles (or the vehicle equipment) in addition to the effect of the first embodiment. As a result, it is possible to highly precisely predict the energy consumption. 
       FIG. 23  is a diagram illustrating an example of the actual energy consumption and the predicted energy consumption without considering the ambient air temperature. In  FIG. 23 , the horizontal axis indicates the actual energy consumption. The vertical axis indicates the number (frequency) of vehicles each actual energy consumption.  FIG. 23  illustrates the median of the predicted energy consumption of the vehicles and the prediction range of ±10% from the median. As illustrated in  FIG. 23 , when the energy consumption is predicted without considering the ambient air temperature, the vehicle of which the actual energy consumption fell within the prediction range of the energy consumption is about 67% in total. 
     On the contrary,  FIG. 24  is a diagram illustrating an example of the predicted energy consumption in consideration of the actual energy consumption and the ambient air temperature. Further, in  FIG. 24 , the horizontal axis indicates the actual energy consumption similarly to  FIG. 23 . The vertical axis indicates the number (frequency) of vehicles each actual energy consumption.  FIG. 24  also illustrates the median of predicted energy consumption and the prediction range of ±10% from the median. As illustrated in  FIG. 24 , when the energy consumption is predicted in consideration of the ambient air temperature, the vehicle of which the actual energy consumption fell within the prediction range is 90% or more in four seasons. In this way, when the energy consumption is predicted in consideration of the ambient air temperature, it is possible to highly precisely predict the energy consumption compared to a case in which the energy consumption is predicted without considering the ambient air temperature as illustrated in  FIG. 23 . 
     Further, in the second embodiment, when the ambient air temperature is predicted on the basis of the combination of the season, the month, the date, the region of the traveling section, and the latitude and the longitude of the traveling section, the ambient air temperature is predicted at the smaller temperature interval as the ambient air temperature is lower.  FIG. 25  is a diagram illustrating an example of the predicted value of ambient air temperature which is necessary for most of the actual energy consumption falling within the prediction range as illustrated in  FIG. 24 . The rolling resistance is higher according as the ambient air temperature is lower. For that reason, in order to set the actual energy consumption within the prediction range, it is necessary to be higher precision of the prediction of ambient air temperature (to be smaller prediction temperature interval) according as the ambient air temperature is lower as illustrated in  FIG. 25 . In the embodiment, as illustrated in  FIG. 25 , the precision of the predicting of ambient air temperature is higher according as the ambient air temperature is lower. Accordingly, it is possible to highly precisely calculate the rolling resistance on the basis of the ambient air temperature. 
     Further, in the second embodiment, as illustrated in  FIG. 19 , the loss correction coefficient corresponding to the rolling resistance is calculated on the basis of the ambient air temperature. There is a tendency that the work efficiency of the motor caused by the acceleration and deceleration is small when the rolling resistance is high. For that reason, since the loss correction coefficient is smaller according as the rolling resistance is higher, it is possible to highly precisely predict the loss in the drive-train in the target section. As a result, it is possible to highly precisely predict the energy consumption. 
     Further, in the embodiment, as illustrated in  FIG. 20 , the loss correction coefficient corresponding to the type of vehicles is calculated on the basis of the vehicle information.  FIG. 26  is a diagram illustrating a difference in the energy consumption in accordance with the type of vehicles. For example, there is a case in which the vehicle weight (the vehicle weight except passenger weights), the brake hub drag resistance, the air resistance coefficient, and the projected area are different in accordance with the type of vehicles. And there is a case in which the travel resistance is different in accordance with the type of vehicles. For that reason, when the energy consumption is predicted without considering the vehicle information, there is a case in which an error of about ±3% occurs in accordance with the type of vehicles as illustrated in  FIG. 26 . In the embodiment, since the loss correction coefficient corresponding to the type of vehicles is calculated in consideration of the vehicle information, it is possible to decrease such error. As a result, it is possible to highly precisely predict the energy consumption. 
     The above-described embodiments are employed for the easy comprehension of the invention, and do not limit the invention. Thus, the components disclosed in the above-described embodiments include all modifications in design or equivalents that belong to the technical scope of the invention. 
     For example, in the above-described embodiments, the navigation device  1  mounted on the electric vehicle has been described as an example for the present invention. However, the present invention is not limited to this configuration. For example, the device for predicting the energy consumption may be configured to be mounted on a hybrid vehicle, an engine vehicle, or a system other than a vehicle. For example, when the present invention is applied to the engine vehicle, it is possible to appropriately predict the petroleum fuel consumption to the destination on the basis of the integrated value of air resistance to the destination and the integrated value of loss in the drive-train such as the motor or the gear. 
     Further, in the above-described embodiments, a configuration of calculating the integrated value of air resistance or the integrated value of loss in the drive-train by using the average vehicle speed V ave  in the traveling section has been exemplified. However, a configuration of using a limit speed of the traveling section instead of the average vehicle speed V ave  in the traveling section may be employed. Further, a configuration of using the average vehicle speed in the same kind of the traveling section (for example, a street or a suburb) instead of the average vehicle speed V ave  of the traveling section may be employed. 
     Further, the map information obtaining unit  110  of the above-described embodiments corresponds to the obtain unit of the present invention. The correction coefficient calculating unit  150  and the energy consumption predicting unit  130  of the above-described embodiments respectively correspond to the air resistance calculating unit and the loss calculating unit of the present invention. The energy consumption predicting unit  130  of the above-described embodiments corresponds to the energy consumption predicting unit of the present invention. The rolling resistance coefficient calculating unit  230  of the above-described embodiments corresponds to the rolling resistance calculating unit of the present invention. 
     DESCRIPTION OF REFERENCE NUMERALS 
     
         
         
           
               1  . . . Navigation device 
               100  . . . Control device 
               110  . . . Map information obtaining unit 
               120  . . . Recommended route searching unit 
               130  . . . Energy consumption predicting unit 
               140  . . . Correction coefficient storing unit 
               150  . . . Correction coefficient calculating unit 
               160  . . . Charging necessity determining unit 
               170  . . . Charging station searching unit 
               180  . . . Display unit 
               210  . . . Ambient air temperature obtaining unit 
               220  . . . Vehicle information obtaining unit 
               230  . . . Rolling resistance coefficient calculating unit 
               200  . . . Input device 
               300  . . . Own vehicle position detecting device 
               400  . . . Map database 
               500  . . . Display