Control system for hydraulic system and method for recovering energy and leveling hydraulic system loads

A method of delivering power in a hybrid work machine, the method comprising:

• determining engine power of an engine;
• determining accumulator pressure of an accumulator;
• determining a target power flow to/from a work machine component;
• flow sharing a power flow to the work machine component from a main pump mechanically connected to the engine and from a transformer fluidly connected to the accumulator when the accumulator pressure is below a threshold value, the accumulator is available for discharge, and the target power flow is to the work machine component;
• supplying the power flow to the work machine component from the transformer when the accumulator pressure is above the threshold value and the target power flow is to the work machine component;
• and
• supplying the power flow to the work machine component from the main pump when the accumulator is unavailable for discharge and the target power flow is to the work machine component.

A method of delivering power in a hybrid excavator, the method comprising:

• determining engine power of an engine;
• determining accumulator pressure of an accumulator;
• determining a swing target power flow to/from a swing actuator;
• determining a boom target power flow to/from a boom actuator;
• determining a transformer flow capacity of a transformer;
• flow sharing a first power flow from the boom actuator and from the accumulator to the swing actuator when the boom actuator is over-running and moving down, the accumulator is available for discharge, and the boom target power flow is above a threshold value from the boom actuator;
• and
• flow sharing a second power flow from the swing actuator and from the accumulator to the boom actuator when the swing actuator is decelerating, the accumulator is available for discharge, and the swing target power flow is above a threshold value from the swing actuator.

A method of delivering power in a hybrid work machine, the method comprising:

• determining accumulator pressure of an accumulator;
• determining a target power flow to/from a work machine component;
• flow sharing a power flow to the work machine component from a first power source and from a second power source when the second power source has available energy below a threshold value, and the target power flow is to the work machine component;
• supplying the power flow to the work machine component from the second power source when the second power source has the available energy above the threshold value and the target power flow is to the work machine component;
• and
• supplying the power flow to the work machine component from the first power source when the second power source has no available energy and the target power flow is to the work machine component.

A method of delivering power in a hybrid work machine, the method comprising:

• determining engine power of an engine;
• determining accumulator pressure of an accumulator;
• determining a target power flow to/from a work machine component;
• flow sharing a power flow to the accumulator from a main pump mechanically connected to the engine and from a transformer mechanically connected to the work machine component when the accumulator pressure is below a threshold value, when the accumulator is available for charging, and when the target power flow is from the work machine component;
• supplying the power flow to the accumulator from the transformer mechanically connected to the work machine component when the accumulator pressure is above the threshold value, when the accumulator is available for charging, and when the target power flow is from the work machine component;
• and
• supplying the power flow to the accumulator from the transformer fluidly connected to the main pump when the work machine component has no available energy.