Method and arrangement in power transmission of forest machine

An arrangement in the power transmission of a forest machine (1), the forest machine comprising:

• a front chassis (2) and a rear chassis (3) articulated to one another;
• a primary hydrostatic power source (5) arranged on the front chassis (2) for generating hydrostatic power required for moving and controlling at least one of i) the forest machine and ii) actuators (6,7) therein;
• a generator arrangement (8) connected to the primary power source for generating electric energy;
• an electric energy storage means (9) connected to store at least part of the generated electric energy from the generator arrangement;
• a conversion means (14) connected to the storage means (9), the conversion means (14) being located on the rear chassis (3) separated from the primary power source (5), the conversion means (14) being a pressure medium-transmitted power generating source separate from the primary power source (5),
• said conversion means (14) adapted to, simultaneously and parallel with the power source (5), generate additional pressure medium-transmitted power to at least partly control a hydraulic timber-processing device responsive to an immediate increased power requirement of the forest machine (1) which exceeds a power generation capacity of the primary power source.

An arrangement in the power transmission of a forest machine (1), the forest machine (1) comprising:

• a front chassis (2) articulated to a rear chassis (3);
• actuators, the actuators comprising a charger (6) connected to the forest machine and a grabbing bucket (7) connected to the charger, the charger and the grabbing bucket being a timber-processing device;
• a primary hydrostatic power source arranged on the front chassis for generating hydrostatic mechanical energy power for moving and controlling the forest machine and the actuators, the primary power source under control of control devices (23);
• a generator arrangement (8) for generating electric energy, the generator arrangement (8) power by the primary power source (5);
• storage elements (9) connected to store at least part of the generated electric energy from the generator arrangement (8);
• a conversion means (14) arranged on the rear chassis at a location separated from the primary power source, the conversion means (14) being a pressure medium-transmitted power generating source separate from the primary power source (5),
• the conversion means (14) connected to the storage elements (9) so that electric energy stored in the storage elements (9) is led from the storage elements to the conversion means (14),
• the conversion means comprising an electric motor (17),
• the conversion means comprising an arrangement (16) for generating pressure medium-transmitted power at one or more locations separated from the primary power source (5),
• the conversion means (14) adapted to at least partly control the timber-processing device by the pressure medium-transmitted power generated therein,
• the conversion means generating the pressure medium-transmitted power in parallel with the primary power source (5) running to generate electric power via the generator arrangement (8), wherein,
• i) the power generated by the primary power source (5) is converted into electric energy by the generator arrangement (8) for immediate utilization for controlling the forest machine, the electric energy stored in the storage elements (9) being fed to the conversion means (14) for generating pressure medium-transmitted power allowing use of the forest machine for a limited period of time without any operation of the primary power source, and
• ii) the storage elements (9) are configured so that electric energy discharged from the storage elements (9) is employed in parallel with the primary power source for fulfilling a momentarily risen power requirement, when operating instructions obtained from a user of the forest machine, and being conveyed by the control devices (23) to the primary power source (5) includes an immediate power requirement of the forest machine which exceeds the power generation capacity of the primary power source, both as electric power and as the pressure medium-transmitted power, with the conversion means (14) at least partly controlling the timber-processing device by the pressure medium-transmitted power generated therein, wherein, responsive to the immediate increased power requirement, the conversion means (14) is used, simultaneously and parallel with the power source (5), to generate the pressure medium-transmitted power for implementing the pressure medium-transmitted function of one of i) the forest machine (1) and ii) the actuator (6,7).