Claims:We Claim:
1. A method of operating a hybrid vehicle, said hybrid vehicle comprising at least an engine and a battery, and a control unit in electronic communication with said engine and said battery:

receiving (200), by said control unit at least at least one drive parameter of said hybrid vehicle;

checking (202), by said control unit, if power developed by said vehicle matches said driver parameter; and

changing (204), by said control unit said power delivered to said vehicle through any one of a hybrid mode, said engine mode and an electric mode.

2. The method of claim 1, wherein said drive parameter is at least one chosen from engine speed, engine torque and load on the engine.

3. The method of claim 1, further comprising training said control unit for receiving said drive parameter.

4. The method of claim 1, further comprising calculating by said control unit a throttle point of said vehicle based on said drive parameter.

5. The method of claim 1, further comprising varying by said control unit said throttle point for changing power delivered to said vehicle to any one of a hybrid mode, said engine mode and an electric mode.

6. The method of claim 1, further comprising receiving, by said control unit state of charge of said battery;
, Description:Complete Specification:

The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed.
Field of the invention
[0001]This invention relates to the field of operating a hybrid vehicle.

Background of the invention
[0002] Electrification of vehicles is seen as one of the measures taken worldwide for reduction of emissions and thereby addresses the stricter emission norms set forth by major countries worldwide. Attempts have been made for implementing concepts of electrification with regards to off highway vehicles like tractor. While, the implementation of a purely electric vehicle involves significant investment in terms of cost, a vehicle with hybrid topology delivers the advantage of having both conventional and electric drive trains. For a vehicle with hybrid topology, a boost recuperating machine is used to convert a conventional internal combustion engine into a hybrid one. However, for effective use of both electric and conventional engine in a hybrid topology, there is a need to ensure that the use of either electric or conventional engine matches both emission and power requirements.

[0003] Prior art patent application KR20150031794A relates to a booster operating method for a hybrid tractor wherein a boost system is applied including an internal combustion engine; an engine control unit for controlling the engine; a transmission for changing the rotational speed of the engine; a transmission control unit controlling the transmission; a motor-generator connected to the engine; a motor-generator control unit controlling the motor-generator; a battery providing electricity for the motor-generator and storing electricity; and a battery control unit controlling the battery. The present invention provides the booster operating method for the hybrid tractor including i) an engine-starting step, ii) a step of determining whether the booster operating switch is turned ON or OFF, iii) a step of determining whether the battery is charged or not, iv) a basic hybrid algorithm operating step v) a discharging step of forcibly operating the motor by discharging the battery vi) a motor operation determining step, and vii) a motor residual output determining step. The purpose of the present invention is to provide an efficient operation strategy for operating the booster system by achieving results such as charging or discharging, or stopping of charging and discharging.

Brief description of the accompanying drawing
[0004] Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:
[0005] FIG. 1 illustrates a layout of a hybrid vehicle; and

[0006] FIG. 2 illustrates a method of operating a hybrid vehicle.

Detailed description of the embodiments
[0007] FIG. 1 illustrates a layout of a hybrid vehicle. The hybrid vehicle disclosed herein may be an off-highway vehicle like tractor. A clutch is in mechanical engagement with the engine 100. The clutch 102 engages/disengages the gears located in a gear box 104. From the gears, power is transmitted to the wheels 108 with the help of differential 106. In the above mentioned hybrid vehicle, battery is located in proximity to the engine and provides power to the wheels via the clutch and gears. The battery is configured in a way such that, electric power is supplied to the wheels only up to a threshold as defined during calibration of the battery. For example, consider in one instance the threshold is 30 percent. Then the battery will supply power to the wheels from 100 percent (full capacity) to 30 percent. Any demand for electric power after reaching 30 percent will be met by the engine and the battery will shut down.

[0008]The engine of the hybrid vehicle is designed to operate at various throttle points. Throttle points are defined based upon parameters like soil conditions, gear ratio, and other resistive force on the tractor. The throttle points are not restricted to the parameters mentioned, but can be any parameter in addition to the above mentioned parameters that affects the working of the hybrid vehicle, like moisture content in the soil, topography of the land. The throttle points are stored in a data map of the control unit in the vehicle. The method of operating the hybrid with these throttle points as boundary condition will now be explained in further detail.

[0009]FIG. 2 illustrates a method of operating a hybrid vehicle. The hybrid vehicle comprises at least an engine and a battery, and a control unit in electronic communication with the engine and battery. The method comprises receiving (200) by the control unit state of charge of the battery. At step 202, the control unit receives at least one drive parameter of the hybrid vehicle. The control unit checks 204 if power from state of charge matches the drive parameter. The power delivered to the vehicle is changed to any one of hybrid mode, engine mode and an electric mode. In an embodiment the drive parameter is at least one chosen from engine speed, engine torque and load on the engine. The proposed method further comprises training the control unit for receiving the drive parameters. By training the control unit, it is now possible for the control unit to receive drive parameters as input, calculate the throttle points and enable the vehicle to operate in any one of the modes.

[0010] For the purpose of better understanding the working of the above mentioned method will be explained in each of the mode of the working of the vehicle, that is the engine mode, electric mode and hybrid mode. When the vehicle is running under hybrid mode, the power delivered by the engine is transmitted to a gear box and differential and further to the wheels. The control unit receives 200 at least one drive parameter of the vehicle. The drive parameters may be engine speed, engine torque and load on the engine. The control unit checks if the power developed by the vehicle matches the drive parameter. Based on the drive parameter, if more power is required, the control unit now varies the throttle point for changing the power delivered to the vehicle from the engine mode to hybrid mode. The throttle points are defined independent of the drive parameter and stored in the control unit. By shifting the throttle point, the option of shifting to a mode that is suitable for achieving the power requirements while meeting the emission norms is now possible. This allows the engine to operate at lower torque point while allowing battery to provide power at higher torque points. Hence by changing the torque points of the engine from maximum torque points to a reduced set of torque points (also called as virtual full throttle performance) it is now possible to manage the torque demanded by the vehicle. Therefore, under instances when the engine needs to provide torque exceeding the reduced set of torque points, the electric motor/battery will now substitute for the deficient torque.

[0011]Now consider the case where the vehicle runs under electric mode. The control unit now monitors the state of charge of the battery in the vehicle. The vehicle is supported by battery as long as the state of charge does not fall below a minimum threshold as defined. Upon reaching the threshold, the control unit will shift the throttle point so that power that is developed by the engine is available to the vehicle. By using the above mentioned method it is now possible to switch the throttle points as per the driving conditions and torque demand. This brings about savings in fuel economy and reduction in emissions.
.

[0012]It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention in terms of the type of vehicle used. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.