Flow management system for hydraulic work machine

A hydraulic system comprising at least one actuator system for extending and retracting a respective unbalanced hydraulic cylinder having a head-end chamber and a rod-end chamber,

• the actuator system comprising:
• first and second fluid flow lines respectively connectable to the head-end and rod-end chambers of the hydraulic cylinder;
• and
• a bi-directional pump having first and second inlet/outlet ports respectively connected to the first and second fluid flow lines whereby operation of the pump in a first direction will supply pressurized fluid to the first fluid flow line for delivery to the head-end chamber of the hydraulic cylinder while drawing fluid through the second fluid flow line from the rod-end of the cylinder, and operation of the pump in a second direction opposite the first direction will supply pressurized fluid to the second fluid flow line for delivery to the rod-end chamber of the hydraulic cylinder while drawing fluid through the first fluid flow line from the head-end of the cylinder;
• and
• a valve assembly connected between the first and second fluid flow lines and a third fluid flow line, the valve assembly being operated by differential pressure between the first and second fluid flow lines to connect the second fluid flow line to the third fluid flow line when pressure in the first fluid flow line exceeds the pressure in the second fluid flow line by a prescribed amount whereby make-up fluid can be supplied through the third fluid flow line to the second fluid flow line, and to connect the first fluid flow line to the third fluid flow line when pressure in the second fluid flow line exceeds the pressure in the first fluid flow line by a prescribed amount whereby excess fluid from the head-end chamber of the hydraulic cylinder can be accepted by the third fluid flow line;
• and
• the hydraulic system further comprising a boost system for accepting or supplying fluid from or to the third fluid flow line, the boost system including a boost pump for supplying pressurized fluid to the third fluid flow line at a pressure normally less than the pressure at which fluid is supplied to the first and second fluid flow lines by the bi-directional pump.

A hydraulic system comprising at least one actuator system for extending and retracting a respective unbalanced hydraulic cylinder having a head-end chamber and a rod-end chamber,

• the actuator system comprising:
• first and second fluid flow lines respectively connectable to the head-end and rod-end chambers of the hydraulic cylinder;
• and
• a bi-directional pump operable in one direction for supplying pressurized fluid to the first fluid flow line for delivery to the head-end chamber of the hydraulic cylinder, and operable in a second direction opposite the first direction for supplying pressurized fluid to the second fluid flow line for delivery to the rod-end chamber of the hydraulic cylinder;
• and
• an electric drive system for driving the bi-directional pump;
• and
• the hydraulic system further comprising a boost system for accepting or supplying fluid from or to the first and second fluid flow lines, the boost system including a boost pump for supplying pressurized fluid to a third fluid flow line at a pressure normally less than the pressure at which fluid is supplied to the first and second fluid flow lines by the bi-directional pump, and for circulating hydraulic fluid through at least a part of the electric drive system for cooling purposes.

A hydraulic system comprising at least one actuator system for extending and retracting a respective unbalanced hydraulic cylinder having a head-end chamber and a rod-end chamber,

• the actuator system comprising:
• first and second fluid flow lines respectively connectable to the head-end and rod-end chambers of the hydraulic cylinder;
• and
• a bi-directional pump operable in one direction for supplying pressurized fluid to the first fluid flow line for delivery to the head-end chamber of the hydraulic cylinder, and operable in a second direction opposite the first direction for supplying pressurized fluid to the second fluid flow line for delivery to the rod-end chamber of the hydraulic cylinder;
• and
• an electric drive system for driving the bi-directional pump;
• and
• the hydraulic system further comprising a boost system for accepting or supplying fluid from or to the first and second fluid flow lines, the boost system including a boost pump for supplying pressurized fluid to a third fluid flow line at a pressure normally less than the pressure at which fluid is supplied to the first and second fluid flow lines by the bi-directional pump, and for circulating hydraulic fluid through a flow restriction for fluid warm-up.

A hydraulic system comprising at least one actuator system for extending and retracting a respective unbalanced hydraulic cylinder having a head-end chamber and a rod-end chamber,

• the actuator system comprising:
• first and second fluid flow lines respectively connectable to the head-end and rod-end chambers of the hydraulic cylinder;
• and
• a bi-directional pump operable in one direction for supplying pressurized fluid to the first fluid flow line for delivery to the head-end chamber of the hydraulic cylinder, and operable in a second direction opposite the first direction for supplying pressurized fluid to the second fluid flow line for delivery to the rod-end chamber of the hydraulic cylinder;
• and
• an electric drive system for driving the bi-directional pump;
• and
• the hydraulic system further comprising a boost system for accepting or supplying fluid from or to the first and second fluid flow lines, the boost system including a boost pump for supplying pressurized fluid to a third fluid flow line at a pressure normally less than the pressure at which fluid is supplied to the first and second fluid flow lines by the bi-directional pump, and wherein when a load acting on the hydraulic cylinder will reverse drive the hydraulic cylinder to cause fluid to flow from the hydraulic cylinder independently of the bidirectional pump, such flow is directed through the boost pump to reverse drive an electric motor connected to the boost pump for regeneration of electricity for energy recovery purposes.

A hydraulic system comprising at least one actuator system for extending and retracting a respective unbalanced hydraulic cylinder having a head-end chamber and a rod-end chamber,

• the actuator system comprising:
• first and second fluid flow lines respectively connectable to the head-end and rod-end chambers of the hydraulic cylinder;
• and
• a bi-directional pump operable in one direction for supplying pressurized fluid to the first fluid flow line for delivery to the head-end chamber of the hydraulic cylinder, and operable in a second direction opposite the first direction for supplying pressurized fluid to the second fluid flow line for delivery to the rod-end chamber of the hydraulic cylinder;
• and
• an electric drive system for driving the bi-directional pump;
• and
• the hydraulic system further comprising a boost system for accepting or supplying fluid from or to the first and second fluid flow lines, the boost system including a boost pump for supplying pressurized fluid to a third fluid flow line at a pressure normally less than the pressure at which fluid is supplied to the first and second fluid flow lines by the bi-directional pump, and wherein the boost pump is a submersible pump submersed in a reservoir for the fluid.