Abstract:
The purpose of the present invention is to charge a battery for supplying power to an electrically-powered auxiliary machine, while achieving lower fuel consumption, lower exhaust gas emissions, and lower noise. In a vehicle having an electrically-powered compressor, a battery for supplying power to the electrically-powered compressor, and a generator for generating power to charge the battery or power to be supplied to the electrically-powered compressor, the drive shaft of the generator is directly coupled to the shaft of the engine or is an integral part of the shaft of the engine. The generator is designed to carry out regenerative power generation during deceleration or during driving on a down grade.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a U.S. national stage of application No. PCT/JP2013/072312, filed on Aug. 21, 2013. Priority under 35 U.S.C. §119(a) and 35 U.S.C. §365(b) is claimed from Japanese Patent Application No. 2012-200389, filed on Sep. 12, 2012. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to a vehicle, a generator system, and a generation method. 
       BACKGROUND ART 
       [0003]    Conventionally, a vehicle equipped with an auxiliary machine such as a refrigeration device may be configured that a part of output of a vehicle driving engine is shared as power for the auxiliary machine, or output of a sub-engine provided additionally to the engine is used as power for the auxiliary machine. 
         [0004]    In any configuration, the vehicle driving engine or the sub-engine needs to be stopped in a place, such as on a car ferry, in which generation of exhaust gas is unfavorable. In order to drive the auxiliary machine even when the vehicle driving engine or the sub-engine is stopped, an electric motor for driving the auxiliary machine may be provided on a vehicle additionally. In a case where the vehicle is on the car ferry, for example, power for the auxiliary machine driving electric motor. 
         [0005]    As another configuration, PTL 1, for example, discloses that no sub-engine is provided and only an electric motor is provided for driving an auxiliary machine, and that the auxiliary machine driving electric motor is supplied with power from a generator driven by an engine. 
       CITATION LIST 
     Patent Literature 
       [0000]    
       
         {PTL 1} JP H08-1347 B 
       
     
       SUMMARY OF INVENTION 
     Technical Problem 
       [0007]    As described above, the auxiliary machine such as the refrigeration device conventionally uses a vehicle driving engine or a sub-engine as a power source. On the contrary, in recent years, it is being considered that an auxiliary machine should be powered electrically 
         [0008]    For making an auxiliary machine be powered electrically, a battery for supplying electric power to the auxiliary machine needs to be provided on the vehicle. In addition, in order to charge such a battery, a generator needs to be provided on the vehicle. However, such a generator cannot achieve reduction of fuel consumption, reduction of gas emissions, and reduction of noise emissions if it is driven by a vehicle driving engine or a sub-engine. 
         [0009]    The present invention has been achieved under such circumstances, and an object of the present invention is to provide a vehicle, a generator system, and a generation method enabling to achieve reduction of fuel consumption, reduction of gas emissions, and reduction of noise emissions and enabling to obtain electric power for charging a battery which supplies electric power to an electric-powered auxiliary machine or obtain electric power to be supplied to the auxiliary machine. 
       Solution to Problem 
       [0010]    A vehicle according to the present invention comprises an electric-powered auxiliary machine, a battery which supplies electric power to the auxiliary machine, and a generator which generates electric power for charging the battery or electric power to be supplied to the auxiliary machine. A driving shaft of the generator is joined directly to a shaft of an engine or is in common with the shaft of the engine, and the generator performs regenerative generation during deceleration or during running on a downward slope. 
         [0011]    Maximum electric power to be generated by the generator is, for example, preferably approximately equal to maximum electric power to be consumed by the auxiliary machine. Alternatively, horsepower of the generator regarded as an electric motor may be one seventh or lower of horsepower of the engine. Since the generator is not used for performing operations of a hybrid car, no electric power is preferably supplied from the battery to the generator. 
         [0012]    A generator system according to the present invention is provided on a vehicle including an electric-powered auxiliary machine and a battery supplying electric power to the auxiliary machine and generates electric power for charging the battery or electric power to be supplied to the auxiliary machine. A driving shaft thereof is joined directly to a shaft of an engine or is in common with the shaft of the engine, and regenerative generation is performed during deceleration or during running on a downward slope. 
         [0013]    A method for generating electric power on a vehicle including an electric-powered auxiliary machine and a battery for supplying electric power to the auxiliary machine to charge a battery or supply the electric power to an auxiliary machine, comprising: a step of performing regenerative generation during deceleration or during traveling on a downward slope by a generator whose driving shaft is joined directly to a shaft of an engine or is in common with the shaft of the engine. 
         [0014]    A method for generating electric power generation method according to the present invention is to generate electric power on a vehicle including an electric-powered auxiliary machine and a battery for supplying electric power to the auxiliary machine to charge the battery or supply the electric power to the auxiliary machine, comprising a step of performing regenerative generation during deceleration or during running on a downward slope by a generator whose driving shaft is joined directly to a shaft of an engine or is in common with the shaft of the engine. 
       Advantageous Effects of Invention 
       [0015]    According to the present invention, electric power for charging a battery supplying electric power to an electric-powered auxiliary machine or electric power to be supplied to the auxiliary machine can be obtained with achieving reduction of fuel consumption, reduction of gas emissions, and reduction of noise emissions. According to the present invention, a generator for charging the battery can be attached to an existing vehicle with no modification or with simple modification. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0016]      FIG. 1  illustrates a configuration of a main part of a vehicle according to a first embodiment of the present invention. 
           [0017]      FIG. 2  is a flowchart describing operations of a control unit in  FIG. 1 . 
           [0018]      FIG. 3  illustrates a configuration of a main part of a vehicle according to a second embodiment of the present invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Embodiment 
       [0019]    A vehicle  1  according to a first embodiment of the present invention will be described with reference to  FIG. 1 .  FIG. 1  illustrates a configuration of a main part of the vehicle  1  and illustrates only a selected configuration according to the first embodiment of the present invention. 
         [0020]    The vehicle  1  includes as main components an engine  10 , a generator  11 , a converter  12 , a battery  13 , a control unit  14 , an electric compressor  15 , and a refrigerator unit  16 . The vehicle  1  further includes as conventional components a clutch  17 , a transmission  18 , driving wheels  19 , a differential gear  20 , and the like. 
         [0021]    An example of the engine  10  is a diesel engine. Assuming the vehicle  1  being a heavy-duty truck, the engine  10  is, e.g., in a 380-horsepower class. To an output shaft of the engine  10 , an input shaft of the generator  11  is joined. Alternatively, the output shaft of the engine  10  may be a common shaft member with the input shaft of the generator  11 . 
         [0022]    An example of the generator  11  is an alternating-current generator. The input shaft of the generator  11  is the output shaft of the engine  10 . Alternatively, the input shaft of the generator  11  and the output shaft of the engine  10  may be the common shaft member as described above. The generator  11  also has an output shaft to be input into the clutch  17 . That is, the output shaft of the generator  11  also functions as the output shaft of the engine  10 . 
         [0023]    The maximum electric power to be generated by the generator  11  is preferably at least the maximum electric power to be consumed by the electric compressor  15  or higher. However, when the electric power to be generated by the generator  11  increases, generation torque of the generator  11  also increases along with this. Since the generation torque of the generator  11  becomes friction for the engine  10 , the electric power to be generated by the generator  11  is preferably set to the minimum necessary. Hence, the maximum electric power to be generated by the generator  11  is preferably approximately equal to the maximum electric power to be consumed by the electric compressor  15 . Since the maximum electric power to be consumed by the electric compressor  15  is about 5 kilowatts to 6 kilowatts, the maximum electric power to be generated by the generator  11  may be equivalent to this. 
         [0024]    Alternatively, in a different viewpoint, a general-purpose electric motor for use in assisting an engine in a hybrid car more compact than the vehicle  1  may be used as the generator  11  to save the effort of new development and manufacture of the aforementioned generator  11 . Since the vehicle  1  is not a hybrid car, assist of the engine  10  by an electric motor is not performed. Thus, horsepower of an electric motor to be used as the generator  11  of the vehicle  1  may be lower than horsepower of the engine  10 . For example, in a case in which the engine  10  of the vehicle  1  is a general-purpose 380-horsepower engine, a general-purpose 40-kilowatt-class electric motor can be used as the electric motor for the more compact hybrid car than the vehicle  1 . In this case, when 0.746 kilowatts is converted into 1 horsepower, the 40-kilowatt-class electric motor has about 54 horsepower. That is, the horsepower of the general-purpose electric motor to be used as the generator  11  is one seventh or lower of the horsepower of the engine  10 . Meanwhile, if the vehicle  1  having the 380-horsepower engine  10  was constructed as a hybrid car, an approximately 270-horsepower (approximately 200-kilowatt) electric motor would be required. 
         [0025]    The generation capacity of the 40-kilowatt-class generator  11  is excessive in comparison to the maximum electric power to be consumed by the electric compressor  15  (5 kilowatts to 6 kilowatts). However, even in this case, the friction caused by the generation torque of the generator  11  is slight for the horsepower of the engine  10 . 
         [0026]    On the other hand, since the 40-kilowatt-class generator  11  may have sufficient potential for supplying electric power to the battery  13 , the generator  11  can fully charge the battery  13  in a very short time. Accordingly, the 40-kilowatt-class generator  11  easily keeps an SOC (state of charge) of the battery  13  in a good state only with regenerative generation without consuming fuel. 
         [0027]    Further, the electric motor for the hybrid car is originally designed to have a configuration in which the output shaft of the engine  10  and the input shaft of the generator  11  are integrated. Thus, the electric motor for the hybrid car can be used as the generator  11  according to the embodiment of the present invention without particular specification changes. Accordingly, time and cost required for design and manufacture can be reduced significantly. 
         [0028]    The converter  12  converts alternating-current electric power generated by the generator  11  into direct-current electric power and supplies it to the battery  13 . That is, the converter  12  functions as a rectifier disposed between the generator  11  and the battery  13 . Meanwhile, since the vehicle  1  does not perform operations as a hybrid car, the converter  12  does not supply electric power from a side of the battery  13  to a side of the generator  11 . More specifically, a circuit of the converter  12  is constituted by a diode and the like so that a current direction may be one way from the side of the generator  11  to the side of the battery  13 . 
         [0029]    The battery  13  is a battery for supplying electric power to the electric compressor  15  as an auxiliary machine. Thus, the battery  13  differs from a conventional battery for supplying electric power to a starter and electric components of the vehicle  1 . For example, the battery  13  is a lithium battery or the like for use in a hybrid car and the like. 
         [0030]    The battery  13  is supplied with electric power for charging from the generator  11  via the converter  12 . The capacity of the battery  13  is preferably one enabling electric power to be supplied to the electric compressor  15  for several consecutive hours during traveling carried by a car ferry or the like. However, in a case in which long-time traveling carried by a car ferry or the like is not taken into consideration, the capacity of the battery  13  may be smaller since electric power is supplied from the generator  11  to the battery  13  even when the electric compressor  15  is being driven. 
         [0031]    The control unit  14  may be realized by, for example, an information processing unit, in which the information processing unit executes a predetermined program installed in advance to cause the information processing unit to fulfill a function of the control unit  14 . For example, the information processing unit includes a memory, a CPU (Central Processing Unit), an input/output port, and the like. The CPU of the information processing unit retrieves and executes a control program as the predetermined program from the memory or the like. This causes the information processing unit to fulfill the function of the control unit  14 . It is to be noted that an ASIC (Application Specific Integrated Circuit), a microprocessor (microcomputer), a DSP (Digital Signal Processor), or the like may be used instead of the aforementioned CPU. 
         [0032]    The electric compressor  15  is a unit for circulating a refrigerant cooling an inside of a refrigerator of the refrigerator unit  16  in a refrigerant pipe of the refrigerator unit  16 . 
         [0033]    The refrigerator unit  16  has the refrigerator mounted on the back of the vehicle  1 . The inside of the refrigerator is kept at a constant temperature below freezing by a thermostat. 
         [0034]    The clutch  17  may be one which is engaged/disengaged by means of driver&#39;s pedal operation or another which is controlled to be engaged/disengaged automatically by an ECU (Electric Control Unit) or the like which controls the transmission  18  to fit with the driver&#39;s transmission operation to the transmission  18 . Here, the clutch  17  may be the former or the latter. As for the clutch  17 , an input side thereof is connected to the output shaft of the generator  11  (that is, the output shaft of the engine  10 ) while an output side thereof is connected to an input side of the transmission  18 . 
         [0035]    As for the transmission  18 , the input side thereof is connected to the clutch  17  while an output side thereof is connected to the differential gear  20  of the driving wheels  19 . 
         [0036]    The vehicle  1  configured as above has the auxiliary machine, in which the refrigerator unit  16  is cooled by the electric compressor  15 , and travels by means of the engine  10 . The electric compressor  15  is supplied with electric power from the battery  13  and is operated. Meanwhile, in the example of the vehicle  1 , since a direct-current electric motor is used as the electric compressor  15 , direct-current electric power is directly supplied from the battery  13  to the electric compressor  15 . In a case in which an alternating-current electric motor is used as the electric compressor  15 , an inverter is additionally disposed between the battery  13  and the electric compressor  15 . 
         [0037]    Generation by the generator  11  is performed when the engine  10  generates power and the vehicle  1  is running by means of this power, when the engine  10  generates no power but the vehicle  1  is decelerating, or when the engine  10  generates no power but the vehicle  1  is running on a downward slope. Also, when the vehicle  1  is decelerating or is traveling on a downward slope, the generation torque of the generator  11  functions as a braking force for the vehicle  1 . That is, the generator  11  also functions as a retarder for the vehicle  1 . 
         [0038]    Although generation of the generator  11  by means of power of the engine  10  is not high friction for the engine  10  as described above, it is preferable to perform regenerative generation without consuming fuel as much as possible. To do so, the control unit  14  controls the engine  10 , the generator  11 , the inverter  12 , and the battery  13  based on retarder operation information and SOC information of the battery  13  so that the regenerative generation may be performed as much as possible. Meanwhile, the retarder operation information is information for informing the control unit  14  that a driver has operated a not-illustrated retarder operation lever. 
         [0039]    Next, operations of the control unit  14  will be described with reference to a flowchart in  FIG. 2 . In the flowchart in  FIG. 2 , a condition for “START” is a condition in which the vehicle  1  is running, and in which the aforementioned information processing unit executes the predetermined program to cause this information processing unit to fulfill the function of the control unit  14 . When this condition for “START” is satisfied, the flow proceeds to step S 1 . Meanwhile, the flow from “START” to “END” is a flow for one cycle, and in a case in which the condition for “START” is satisfied when the flow has proceeded to “END”, the flow starts again. 
         [0040]    In step S 1 , the control unit  14  refers to the SOC information of the battery  13  and determines whether or not a value representing the SOC is “low.” This “value representing the SOC” can be defined by a value representing the charging amount of the battery  13 , for example. For example, in a case in which the lower limit value to the upper limit value of the charging amount of the battery  13  is 0% to 100%, the value representing the SOC is defined as “low” when the charging amount is 0% to 10%, the value representing the SOC is defined as “middle” when the charging amount is 11% to 90%, and the value representing the SOC is defined as “high” when the charging amount is 91% to 100%. 
         [0041]    When the SOC is “low,” the battery  13  needs to be charged immediately, and the battery  13  thus needs to do so. When the SOC is “middle,” the battery  13  can be charged but is in a non-emergency situation. When the SOC is “high,” the battery  13  is in a fully charged state and cannot be charged. Meanwhile, since the range of the charging amount when the SOC is “middle” is wider than that when the SOC is “low” or “high,” the SOC is often in the “middle” state. Also, in general, the state in which the SOC is “middle” is regarded as a state in which the SOC is in a good state. 
         [0042]    When it is determined in step S 1  that the value representing the SOC is “low,” the flow proceeds to step S 2 . On the other hand, when it is determined in step S 1  that the value representing the SOC is not “low,” the flow proceeds to step S 3 . 
         [0043]    In step S 2 , the control unit  14  permits both generation performed by driving of the generator  11  based on power that the engine  10  generates and regenerative generation performed based on the retarder operation information during deceleration or on a downward slope when the engine  10  does not generate power. In other words, in a situation in which the engine  10  generates power such as when the vehicle  1  is running at constant speed or is accelerating, generation performed by active driving of the generator  11  through fuel consumption by the engine  10  is carried out. On the other hand, in a situation in which the engine  10  does not consume fuel and does not generate power such as when the vehicle  1  is decelerating or is traveling on a downward slope, regenerative generation is carried out. In this manner, in step S 2 , since the battery  13  is charged almost continuously no matter which situation the vehicle  1  is in, the charging amount of the battery  13  increases promptly. 
         [0044]    In step S 3 , the control unit  14  refers to the SOC information of the battery  13  and determines whether or not the value representing the SOC is “middle.” When it is determined in step S 3  that the value representing the SOC is “middle,” the flow proceeds to step S 4 . On the other hand, when it is determined in step S 3  that the value representing the SOC is not “middle,” the flow proceeds to step S 5 . 
         [0045]    In step S 4 , the control unit  14  permits the regenerative generation performed based on the retarder operation information during deceleration or on a downward slope when the engine  10  does not generate power. Thus, the regenerative generation is carried out during deceleration or on a downward slope when the engine  10  does not generate power. On the other hand, the generation by active driving of the generator  11  by the engine  10  is not carried out. Accordingly, since the battery  13  is charged without using power of the engine  10 , charging can be performed while achieving reduction of fuel consumption, reduction of gas emissions, and reduction of noise emissions. 
         [0046]    In step S 5 , the control unit  14  does not perform generation and ends the processing (END). 
         [0047]    As described above, the driving shaft of the generator  11  is joined directly to the shaft of the engine  10  or is in common with the shaft of the engine  10 , and the generator  11  performs the regenerative generation with no fuel consumption during deceleration or during traveling on a downward slope when the SOC of the battery  13  is “middle” as in step S 4  in  FIG. 2 . Accordingly, the battery  13  can be charged while achieving reduction of fuel consumption, reduction of gas emissions, and reduction of noise emissions. 
         [0048]    Further, the horsepower of the generator  11  regarded as an electric motor is much smaller than the horsepower of the engine  10  (the maximum generation electric power which is equal to the maximum electric power to be consumed by the auxiliary machine or the horsepower which is one seventh or less of the horsepower of the engine  10 ). Thus, even in the case in which the generation is carried out by driving of the generator  11  based on power that the engine  10  generates as in step S 2  in  FIG. 2 , load required for the generation of the engine  10  is extremely low since the generator  11  is small. This can also reduce fuel consumed for generation, exhaust gas emitted for generation, and noise emitted for generation. 
         [0049]    Further, in the generator  11  whose horsepower when the generator  11  is regarded as an electric motor is about one seventh of the horsepower of the engine  10  (for example, the engine  10  has 380 horsepower, and the generator  11  has 54 horsepower), the percentage at which the generator  11  becomes friction for the engine  10  is kept low, and at the same time, since the generation electric power is higher than the maximum electric power to be consumed by the electric compressor  15 , the SOC of the battery  13  is kept in a good state (that is, a state in which the SOC is “middle”) easily only by the regenerative generation with no fuel consumption. 
         [0050]    Still further, the size of the generator  11  is much smaller than the size of the engine  10 . Thus, the generator  11  can be attached to an existing vehicle with simple modification or with no modification. For example, when the generator  11  is to be attached to the existing engine  10 , a specification change is merely a change of the size of a flywheel housing. Alternatively, even the existing flywheel housing can be used as it is depending on the size of the generator  11 . Accordingly, when an existing vehicle is to be changed to the vehicle  1  according to the present invention, time and cost required for design changes and modification can be reduced significantly. 
       Second Embodiment 
       [0051]    A vehicle  1 A according to a second embodiment of the present invention will be described with reference to  FIG. 3 . The vehicle  1 A according to the second embodiment partially differs from the vehicle  1  according to the first embodiment. Hereinbelow, different parts of the vehicle  1 A from the vehicle  1  will be described mainly, and description of common parts of the vehicle  1 A to the vehicle  1  will be omitted. 
         [0052]    The vehicle  1 A has different connection of the converter  12 , a battery  13 A, an electric compressor  15 , and the refrigerator unit  16  from that of the vehicle  1 . In the vehicle  1 A, output electric power of the converter  12  is supplied to the battery  13 A and is also supplied directly to the electric compressor  15 . In this configuration, the output electric power of the converter  12  causes the battery  13 A to be charged and also causes the electric compressor  15  to be driven directly. 
         [0053]    Accordingly, in the vehicle  1 A, the battery  13 A functions to supply power to the electric compressor  15  in a complemental manner when the generator  11  does not generate power or when power generated by the generator  11  is less than power which drives the electric compressor  15 . Hence, the capacity of the battery  13 A may be smaller than the capacity of the battery  13 . 
         [0054]    Also, in the vehicle  1 A, even when the SOC of the battery  13 A is in a low state, or even when the battery  13 A fails, the electric compressor  15 A can be driven directly by electric power generated by the generator  11 . Accordingly, since the temperature of the refrigerator unit  16  can be kept appropriately even when there is an abnormality in the battery  13 A, reliability of refrigerated transport can be improved. 
       Other Embodiments 
       [0055]    The aforementioned embodiments can be altered in various manners without departing from the spirit thereof. For example, the auxiliary machine can be applied not only to the electric compressor  15  and the refrigerator unit  16  but also to various electric auxiliary machines such as electric crane devices, refuse collecting devices, concrete mixers, and air conditioners. 
         [0056]    The program to be executed by the information processing unit constituting the control unit  14  may be one stored in a memory or the like of the information processing unit before or after shipment of the control unit  14 . Also, part of the program may be stored in the memory or the like of the information processing unit after shipment of the control unit  14 . The program stored in the memory or the like of the information processing unit after shipment of the control unit  14  may be one obtained by installing what is stored in a computer-readable recording medium such as a CD-ROM or one obtained by downloading it via a transmission medium such as the Internet. 
         [0057]    The program includes not only one that is executable directly by the information processing unit but also one that becomes executable by installation on a hard disk or the like. The program also includes compressed or encrypted one. 
         [0058]    In this manner, by causing the information processing unit and the program to fulfill the function of the control unit  14 , mass production and specification changes (or design changes) can be coped with in a flexible manner. 
         [0059]    It is to be noted that the program executed by a computer may be a program in which processing is performed in chronological order in order of the present description or a program in which processing is performed in parallel or at the required time such as when retrieval is performed. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           1 ,  1 A . . . Vehicle,  10  . . . Engine,  11  . . . Generator,  12  . . . Converter,  13  . . . Battery,  14  . . . Control unit,  15  . . . Electric compressor (part of an auxiliary machine),  16  . . . Refrigerator unit (part of the auxiliary machine).