System to pump fluid and control thereof

A hydraulic system comprising:

• a hydraulic pump to provide fluid to a hydraulic actuator having first and second ports, the pump including,
• a first motor to rotate a first gear having a plurality of first gear teeth, the first motor being at least one of a variable-speed or a variable-torque motor, and
• a second motor to rotate a second gear having a plurality of second gear teeth, the second motor being at least one of a variable-speed or a variable-torque motor, the first gear and second gear disposed so as to transfer fluid from an inlet port of the hydraulic pump to an outlet port of the hydraulic pump;
• a control valve assembly including,
• a control valve disposed on a side of the outlet port with respect to a direction of fluid flow, the control valve in fluid communication with the first port and the outlet port, and
• a control valve actuator to operate the control valve;
• and
• a controller having a hydraulic control module for controlling hydraulic functions in the hydraulic system, the controller communicating with a pump control circuit to establish at least one of a speed or a torque of the first and second motors to adjust at least one of a flow in the hydraulic system to a flow set point or a pressure in the hydraulic system to a pressure set point, and communicating with a valve control circuit to concurrently establish an opening of the control valve to adjust at least one of the flow to the flow set point or the pressure to the pressure set point,
• wherein the pump control circuit provides a first demand signal to the first motor and a second demand signal to the second motor, the first demand signal being greater in magnitude by a predetermined value than the second demand signal so as to create synchronized contact between the first gear and the second gear to seal a fluid path from the outlet of the pump to the inlet of the pump,
• wherein the predetermined value is based on at least one of a speed of the hydraulic pump, a pressure in the system, a temperature of the fluid and or a viscosity of the fluid.

A method for controlling a fluid flow in a fluid system, the fluid system including a fluid pump and at least one control valve throttleable between a closed position and an open position, the fluid pump to provide fluid to an actuator that controls a load, the fluid pump including a first motor to rotate a first fluid displacement member and a second motor to rotate a second fluid displacement member, the method comprising:

• initiating at least one of a variable-speed or variable-torque operation of the fluid pump;
• establishing a pump demand signal to control at least one of a speed or a torque of the first and second motors to adjust at least one of a flow in the fluid system to a flow set point or a pressure in the fluid system to a pressure set point;
• establishing, concurrently with the pump demand signal, a valve demand signal to control an opening of the at least one control valve to adjust at least one of the flow to the flow set point or the pressure to the pressure set point;
• providing a first motor demand signal to the first motor and a second motor demand signal to the second motor based on the pump demand signal, the first motor demand signal being greater in magnitude by a predetermined value than the second motor demand signal so as to create synchronized contact between the first fluid displacement member and the second fluid displacement member to seal a fluid path from the outlet of the pump to the inlet of the pump, and
• establishing a plurality of operational modes in the fluid system including at least one of a flow control mode, a pressure control mode, or a balanced control mode.

A method for controlling a fluid flow in a fluid system, the fluid system including a fluid pump and at least one control valve throttleable between a closed position and an open position, the fluid pump to provide fluid to an actuator that controls a load, the fluid pump including a first motor to rotate a first fluid displacement member and a second motor to rotate a second fluid displacement member, the method comprising:

• initiating at least one of a variable-speed or variable-torque operation of the fluid pump;
• establishing a pump demand signal to control at least one of a speed or a torque of the first and second motors to adjust at least one of a flow in the fluid system to a flow set point or a pressure in the fluid system to a pressure set point;
• establishing, concurrently with the pump demand signal, a valve demand signal to control an opening of the at least one control valve to adjust at least one of the flow to the flow set point or the pressure to the pressure set point;
• and
• providing a first motor demand signal to the first motor and a second motor demand signal to the second motor based on the pump demand signal, the first motor demand signal being greater in magnitude by a predetermined value than the second motor demand signal so as to create synchronized contact between the first fluid displacement member and the second fluid displacement member to seal a fluid path from the outlet of the pump to the inlet of the pump,
• wherein the predetermined value is based on at least one of a speed of the hydraulic pump, a pressure in the system, a temperature of the fluid or a viscosity of the fluid.