Hybrid architecture for smart power management on off-highway machines

A method for selectively providing hydraulic power to at least one hydraulically powered implement of an off highway machine, the method comprising:

• driving terrain-engagement members with a first amount of mechanical energy produced by an internal combustion engine to move the off-highway machine:
• selectively driving a first hydraulic pump with a second amount of mechanical energy to provide a first amount of hydraulic flow;
• selectively driving a second hydraulic pump with an electric motor that receives energy from an energy storage device to provide a second amount of hydraulic flow;
• maintaining a total of the first amount of mechanical energy and the second amount of mechanical energy less than a threshold amount of mechanical energy by selectively reducing the first amount of hydraulic flow by a differential amount of hydraulic flow to produce a reduced first amount of hydraulic flow;
• adjusting the second amount of hydraulic flow from the second hydraulic pump to compensate for the differential amount of hydraulic flow;
• and
• applying the reduced first amount of hydraulic flow and the second amount of hydraulic flow to the hydraulically powered implement and
• selectively operating a hydraulic source selection valve to selectively provide hydraulic fluid to the hydraulically powered implement from the first hydraulic pump only, from the second hydraulic pump only, or from both the first hydraulic pump and the second hydraulic pump.

A method for selectively providing hydraulic power to a hydraulic load of an off-highway machine, the method comprising:

• driving terrain-engagement members with a first variable amount of mechanical energy from an internal combustion engine to move the off-highway machine;
• selectively driving a first hydraulic pump with a second variable amount of mechanical energy from the internal combustion engine to provide a first source of hydraulic flow;
• driving an electrical generator with the internal combustion engine to generate electrical energy;
• storing the electrical energy in an energy storage device;
• selectively providing the stored electrical energy to drive an electric motor, the electric motor coupled to a second hydraulic pump to selectively provide a second source of hydraulic flow;
• when a first energy usage condition occurs, providing only the first source of hydraulic flow to at least one hydraulically powered implement attached to the off-highway machine;
• when a second energy usage condition occurs, providing only the second source of hydraulic flow to the hydraulically powered implement;
• and
• when a third energy usage condition occurs, providing both the first source of hydraulic flow and the second source of hydraulic flow to the hydraulically powered implement;
• wherein:
• the internal combustion engine provides the energy as a first variable amount of mechanical energy for driving a hydrostatic transmission pump to drive hydrostatic transmission motors that drive terrain-engagement members to move the off-highway machine over varying terrain conditions;
• the internal combustion engine provides a second variable amount of mechanical energy to the first hydraulic pump to drive the hydraulically powered implement attached to the off-highway machine under varying loading conditions of the hydraulically powered implement and the terrain-engagement members;
• and
• the first energy usage condition occurs when a total of the first variable amount of mechanical energy and the second variable amount of mechanical energy is no greater than a threshold amount of mechanical energy such that only the first hydraulic pump is activated to provide all the hydraulic flow to the hydraulically powered implement;
• the second energy usage condition occurs when the first variable amount of mechanical energy is at the threshold amount of mechanical energy such that only the second hydraulic pump is activated to provide all the hydraulic flow to the hydraulically powered implement;
• and
• the third energy usage condition occurs when the first variable amount of mechanical energy is less than the threshold amount of mechanical energy and the total of the first variable amount of mechanical energy and the second variable amount of mechanical energy is at least as great as the threshold amount of mechanical energy, wherein:
• the hydraulic flow produced by the first hydraulic pump is reduced by a differential amount such that the total of the first variable amount of mechanical energy and a reduced second variable amount of mechanical energy is no greater than the threshold amount of mechanical energy;
• and
• the second hydraulic pump is activated to produce hydraulic flow corresponding to the differential amount of reduced hydraulic flow produced by the first hydraulic pump.

A hybrid power generation system for an off-highway machine having terrain-engagement members to move the off-highway machine over varying terrain and having at least one hydraulically powered implement attached to the machine for moving materials, the system comprising:

• an internal combustion engine that generates a first variable amount of mechanical energy to drive the terrain-engagement members over varying terrain conditions;
• a first hydraulic pump coupled to the internal combustion engine to selectively generate a first variable amount of hydraulic flow to manipulate the hydraulically powered implement attached to the machine, the first hydraulic pump requiring a second variable amount of the mechanical energy from the internal combustion engine in response to varying loads on the hydraulically powered implement;
• an electrical generator coupled to receive mechanical energy from the internal combustion engine and to generate electrical energy;
• an energy storage device coupled to the electrical generator to store the electrical energy generated by the electrical generator;
• an electric motor that receives the electrical energy from the energy storage device and that selectively operates to provide electrically generated mechanical energy;
• a second hydraulic pump that receives the electrically generated mechanical energy from the electric motor and that selectively generates a second variable amount of hydraulic flow to manipulate the hydraulically powered implement attached to the machine, machine;
• and
• a control system configured to selectively increase the second variable amount of hydraulic flow generated by the second hydraulic pump to reduce the first variable amount of hydraulic flow generated by the first hydraulic pump to thereby reduce the second variable amount of mechanical energy that drives the first hydraulic pump.