Abstract:
A method is provided for the power requirement-dependent operation of a generator unit mounted on an agricultural work vehicle. A power output of the generator unit is varied as a function of a determined power requirement of an electrical consumer, which is fed with the power of the generator unit of an attachment which is connected to the agricultural work vehicle.

Description:
RELATED APPLICATION 
       [0001]    This application is a continuation application of International Application Serial No. PCT/EP2015/052550, which has an international filing date of Feb. 6, 2015, and which claims the benefit of German Application Ser. No. 102014202449.8, filed on Feb. 11, 2014. The disclosures of these aforementioned applications are hereby expressly incorporated by reference in their entirety. 
     
    
     FIELD OF THE DISCLOSURE 
       [0002]    The present disclosure relates to a generator unit, and in particular to a method for a power requirement-dependent operation of a generator unit mounted on an agricultural work vehicle. 
       BACKGROUND 
       [0003]    In the agricultural industry, a convention generator unit for an agricultural work vehicle is removably connected to the work vehicle and includes an electric generator with a rotor and a stator. The rotor can be connected at least indirectly to the power takeoff shaft of the work vehicle in order to provide drive. As a result, electrical consumers of an attachment which is coupled to the work vehicle can be operated with a higher rated voltage than is usually made available by the on-board power system of the work vehicle. 
         [0004]    In such an arrangement, the power output of the electric generator is proportional to the rotational speed with which the electric generator is driven. In the case of a generator unit which is driven via the power takeoff shaft, this rotational speed of the generator is proportional to the rotational speed of the power takeoff shaft, and the rotational speed of the power takeoff shaft is in turn directly dependent on the rotational speed of the internal combustion engine of the agricultural work vehicle. Ultimately, the power output of the electric generator is dependent on the rotational speed of the internal combustion engine, and a change in the power output of the electric generator can be brought about only by changing the rotational speed of the internal combustion engine. 
         [0005]    In an electrical consumer of an attachment which is coupled to the work vehicle, a power requirement then comes about during operation. The power requirement can vary as a function of the load acting on the attachment, of the operating states, or of the size of the attachment. So that the attachment ensures optimum operation, the generator unit can cover the power requirement of the attachment at all times. In order to cover the power demand of the attachment, in the arrangement described above the operator of the work vehicle must check the power output of the electric generator by means of the rotational speed of the internal combustion engine and adapt it where necessary. This requires a large degree of attentiveness on the part of the operator. In some instances due to an excessively low rotational speed of the internal combustion engine, the power output of the generator unit is not able to cover the power demand of the attachment or that, owing to a high rotational speed of the internal combustion engine, the power demand of the attachment is covered but an uneconomically high rotational speed level is present. 
       SUMMARY 
       [0006]    In this disclosure, a method is provided for the power requirement-dependent operation of a generator unit mounted on an agricultural work vehicle. In this method, a power output of the generator unit is varied as a function of a determined power requirement of an electrical consumer, which is fed with the power of the generator unit of an attachment which is connected to the agricultural work vehicle. 
         [0007]    The term “a mounted generator unit” is to be understood as meaning that the generator unit is either attached in a removable fashion to the front or rear three-point suspension of the work machine or is permanently connected to the work machine at a location at which a rotational movement can be transmitted from the work machine to the generator unit. The generator unit includes a transmission and an electric generator which has a drive connection to the transmission. By means of the transmission it is possible to make available a transmission ratio between the power takeoff shaft which drives the transmission and the electric generator. The attachment can be, for example, a manure spreader, a field sprayer or a loading wagon. Other attachments may also be used within the teachings and principles of this disclosure. Furthermore, it is possible to provide that the electrical consumer of the attachment makes available the drive in order to discharge the material which is to be distributed, for example, on an electrically driven pump or a drive of the attachment per se, such as an electric motor on the drive axle. 
         [0008]    In one embodiment, a method is provided such that, during the operation of an electrified implement by a generator unit which can be driven by an internal combustion engine of the work machine, sufficient power is made available to the attachment in every operating state, but at the same time the power output of the generator unit is limited to the power demand of the attachment. 
         [0009]    The power output of the generator unit is varied by adapting an input rotational speed of the generator unit. As a result it is possible to limit the power output of the generator unit by adapting the rotational speed of the internal combustion engine to the power demand of the attachment. Economical operation of the internal combustion engine is therefore ensured. 
         [0010]    The power requirement is determined the attachment. In this way, the power requirement is determined at the point at which it arises. 
         [0011]    The determined power requirement of the attachment is transmitted as a power demand at least indirectly to the generator unit. This ensures that the generator unit can make a comparison between the transmitted power demand and the instantaneous power output. 
         [0012]    The power demand is transmitted to the generator unit indirectly via the agricultural work machine. In this way, the connection which is present in any case for the transmission, via the AEF interface between the attachment and the work machine, can be used. 
         [0013]    The generator unit transmits a rotational speed request to the agricultural work vehicle as a function of the power requirement of the attachment. This ensures that the generator unit is responsible for the connection element between the attachment and the work vehicle, and for adaptation of the rotational speed of the work vehicle. 
         [0014]    The agricultural work vehicle converts the rotational speed request into adaptation of the rotational speed of the engine or the rotational speed of the power takeoff shaft. As a result, the operator is relieved of the need to correct the rotational speed of the engine or the rotational speed of the power takeoff shaft. 
         [0015]    A control unit is provided which meets the power requirement of the attachment, the power output of the generator unit and the rotational speed of the engine or of the power takeoff shaft to form a closed-loop control circuit in which closed-loop control is carried out to the effect that the power output of the generator unit corresponds at least approximately to the power requirement of the attachment. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The above-mentioned aspects of the present disclosure and the manner of obtaining them will become more apparent and the disclosure itself will be better understood by reference to the following description of the embodiments of the disclosure, taken in conjunction with the accompanying drawings, wherein: 
           [0017]      FIG. 1  is a side view an agricultural work vehicle with a coupled implement and generator unit; 
           [0018]      FIG. 2  is a schematic illustration of a work vehicle, of a generator unit and of an attachment, and a communication structure; and 
           [0019]      FIG. 3  is a view of time profiles of the power demand and of the rotational speed level. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]      FIG. 1  shows an agricultural work vehicle  10  in the form of a tractor which tows an attachment  30  in the form of a loading wagon via a coupled drawbar  12 . The work vehicle  10  is driven by an internal combustion engine  11  or any other type of engine. The generator unit  20  is mounted on the work vehicle  10  via a front three-point suspension  14 . The generator unit  20  is connected to a front power takeoff shaft  16  of the work vehicle  10  via an articulated shaft  18 . The generator unit  20  can be driven by rotation of the power takeoff shaft  16  in order to generate electrical power independently of the on-board power system of the work vehicle  10 . The attachment  30  is also connected via an electrical conductor  22  and an AEF connector  24  to the work vehicle  10 . Electrical power, which is generated by the generator unit  20 , can be made available to an electrical consumer  32  of the attachment  30  via conduction means (illustrated in more detail) on the work vehicle  10  via the AEF connector  24  and the electrical conductor  22 . The electrical consumer  32  is embodied here as an electric motor for driving an axle  34  of the attachment  30 . 
         [0021]    It is to be noted that the attachment  30  can be a device which is carried, for example, in the form of a manure spreader. The electrical consumer  32  does not necessarily have to drive an axle either. The drive can also be provided, for example, by means of a pump. In addition, it is possible to provide that the generator unit  20  is attached via a rear three-point suspension and can be driven via a rear-mounted power takeoff shaft of the work vehicle  10 . These alternatives are not illustrated. 
         [0022]    In  FIG. 3 , the work vehicle  10 , the generator unit  20 , the attachment  30 , and a communication structure are shown. It is to be noted that based on the operating state in which the attachment  30  is in a specific point in time, a defined electrical power requirement is produced. In this disclosure, there is provision that the power requirement which is produced as a power demand is either transmitted indirectly via the work vehicle  10  to the generator unit  20  or directly to the generator unit  20 . After the generator unit  20  has received the power demand of the attachment  30 , the generator unit  20  compares the power demand with the instantaneously available power output. In one example, the power demand and power output correspond with the result that the power output does not have to be adapted. If the power output differs from the power demand, the generator unit  20  transmits a rotational speed request to the work vehicle  10 . The rotation speed request is either a request to increase the rotational speed, specifically if the power output is below the power demand, or a request to reduce the rotational speed, specifically if the power output is above the power demand. Furthermore, the rotational speed request can relate to the rotational speed of the internal combustion engine of the work vehicle  10 , or alternatively, the rotational speed request can relate to the rotational speed of the power takeoff shaft  16  of the work vehicle  10 . 
         [0023]      FIG. 3  further illustrates time profiles of the power demand in the unit of kilowatts (kW) of the attachment  10  and the time profiles of the rotational speed (1/min) of the engine or the rotational speed (1/min) of the power takeoff shaft of the work vehicle  10 . In the case of the profile of the power demand of the attachment  10 , it is assumed that any change in the curve profile is caused by a change in an operating state of the attachment  10 , whatever the cause of said change. As a result, the communication described in relation to  FIG. 3  takes place with a change in the rotational speed level according to the requirement. It is to be noted that the respective change in the rotational speed level chronologically tracks the power demand. Expressed in a formula, the relationship illustrated in  FIG. 3  is 
         [0000]        f (rotational speed of engine)= f (power demand), if adjustment is carried out to the rotational speed of the engine 
         [0000]    or 
         [0000]        f (rotational speed of the power takeoff shaft)= f (power demand), if adjustment is carried out to the rotational speed of the power takeoff shaft. 
         [0024]    As illustrated in  FIG. 1 , a control unit  40  is provided which meets the power requirement of the attachment  30 , the power output of the generator unit  20 , and the rotational speed of the engine or of the power takeoff shaft  16 . This forms a closed-loop control circuit in which closed-loop control is carried out to the effect that the power output of the generator unit  20  corresponds at least approximately to the power requirement of the attachment  30 . 
         [0025]    While embodiments incorporating the principles of the present disclosure have been described hereinabove, the present disclosure is not limited to the described embodiments. Instead, this application is intended to cover any variations, uses, or adaptations of the disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this disclosure pertains and which fall within the limits of the appended claims.