Abstract: A control system for a variable displacement hydraulic pump is disclosed. The control system utilizes two flow control valves to provide a flow of hydraulic fluid to two control actuators. The control actuators create opposing moments on the pump swashplate to control swashplate orientation and pump displacement.

Abstract: A system for providing hydraulic power in a machine transmission includes a first hydraulic variator and a second hydraulic variator, each variator having a mechanical input to a hydraulic pump, and a hydraulic motor linked to the hydraulic pump via a hydraulic circuit, and a mechanical output from the hydraulic motor. In an embodiment, the first hydraulic circuit side of one variator is hydraulically connected to the first hydraulic side of the other variator, and the second hydraulic circuit sides are likewise linked together. A common input is geared to the inputs of the variators and a common output is geared to the outputs of the variators, tying the pump and motor of each variator to rotate at the same speed as the counterpart components of the other variator.

Abstract: A pump is disclosed. The pump may have a housing, a body rotatably disposed within the housing and at least partially defining a plurality of barrels, a plurality of plungers associated with the plurality of barrels, and a swashplate tiltable by a swivel torque to vary a displacement of the plurality of plungers relative to the plurality of barrels. The pump may also have a port plate with an inlet port, a discharge port, and a protrusion. The port plate may be configured to engage an end of the rotatable body. The pump may further have at least one piston disposed within the housing and configured to selectively engage the protrusion of the port plate to rotate the port plate and adjust the swivel torque.

Abstract: A method and apparatus for controlling discharge pressure and pump displacement of a plurality of variable displacement hydraulic pumps having connected discharge ports is provided. Each pump includes a swashplate and a control valve for controlling an angle of inclination of the swashplate. A desired first pump displacement control law is determined for a first pump and determined a desired second pump discharge pressure control law for a second pump. The first control law is used to determine a first intermediate control variable. The second control law is used to determine a second intermediate control variable. The control of the first and second pumps are combined using the first and second intermediate control variables. A desired first control valve setting for the control valve of the first pump is determined using the combined first and second intermediate control variables and the first control law.

Abstract: Methods, apparatuses, and computer program products for controlling the torque load of multiple variable displacement hydraulic pumps are described herein. A pump displacement limit for each variable displacement hydraulic pump is determined using a nonlinear control law to limit the total pump torque load of the variable displacement hydraulic pumps on the engine. The value of the actual pump displacement of each variable displacement hydraulic pump is controlled based upon the respective determined pump displacement limit.

Abstract: A system for providing hydraulic power in a machine transmission includes a first hydraulic variator and a second hydraulic variator, each variator having a mechanical input to a hydraulic pump, and a hydraulic motor linked to the hydraulic pump via a hydraulic circuit, and a mechanical output from the hydraulic motor. In an embodiment, the first hydraulic circuit side of one variator is hydraulically connected to the first hydraulic side of the other variator, and the second hydraulic circuit sides are likewise linked together. A common input is geared to the inputs of the variators and a common output is geared to the outputs of the variators, tying the pump and motor of each variator to rotate at the same speed as the counterpart components of the other variator.

Abstract: An electro-hydraulic control system for pump control is disclosed. The hydraulic actuator is configured to control the inclination of a swashplate. The position of the hydraulic actuator is controlled by controlling the flow of pressurized fluid into and out of two pressure chambers, one on either side of the actuator. A fluid passageway is provided that selectively connects the passageway to tank. The passageway has an orifice for each pressure chamber, and the actuator is configured to selectively block all or a portion of one or more of the orifices, depending on the position of the actuator. The components of the control system are configured such that the actuator will return to a neutral or near-neutral position upon loss of electric power.

Abstract: A control system for a variable displacement hydraulic pump is disclosed. The control system utilizes two flow control valves to provide a flow of hydraulic fluid to two control actuators. The control actuators create opposing moments on the pump swashplate to control swashplate orientation and pump displacement.

Abstract: A system and method for controlling a variator operate to detect variator torques and/or internal pressures and generates a preliminary corrective command. The preliminary corrective command is transformed via a dynamic transform to account for system characteristics during transient operating conditions such as machine acceleration, such that the acceleration of the system during transient periods is not torque-limited by static torque-control map values. In an embodiment, the acceleration may be positive or negative, and in a further embodiment, braking is automatically applied in the case of negative requested power or desired machine retarding.

Abstract: A system for controlling a power output is disclosed. The system includes a hydraulic actuator configured to output a first torque and a source of pressurized fluid configured to supply a flow of pressurized fluid to the hydraulic actuator. The system further includes a controller configured to control the flow of pressurized fluid as a function of the first torque, a predetermined torque, and changes to the first torque caused by a load operatively connected to the hydraulic actuator.

Abstract: A method is provided for controlling braking in a vehicle having a motor and a brake. The method includes sensing an actual operating parameter of the motor and receiving a desired operating parameter of the motor. The motor is controlled based on the actual operating parameter and the desired operating parameter of the motor. The brake is controlled based on the actual operating parameter and the desired operating parameter of the motor and an output from the motor control.

Abstract: A system and method for controlling a variator operate to detect variator torques and/or internal pressures and generates a preliminary corrective command. The preliminary corrective command is transformed via a dynamic transform to account for system characteristics during transient operating conditions such as machine acceleration, such that the acceleration of the system during transient periods is not torque-limited by static torque-control map values. In an embodiment, the acceleration may be positive or negative, and in a further embodiment, braking is automatically applied in the case of negative requested power or desired machine retarding.

Abstract: A system for controlling a power output is disclosed. The system includes a hydraulic actuator configured to output a first torque and a source of pressurized fluid configured to supply a flow of pressurized fluid to the hydraulic actuator. The system further includes a controller configured to control the flow of pressurized fluid as a function of the first torque, a predetermined torque, and changes to the first torque caused by a load operatively connected to the hydraulic actuator.

Abstract: A method and apparatus for determining the operating health of a hydraulic system are provided. The method may include the steps of determining a plurality of operating parameters of the hydraulic system during operation of the hydraulic system, determining an estimated working condition value of the hydraulic system, modifying the estimated working condition value as a function of the operating parameters, and determining the operating health of the hydraulic system as a function of the working condition value. In one method, the working condition value may be indicative of an effective bulk modulus value of an operating fluid within at least part of the hydraulic system.

Abstract: Consistent with an aspect of the disclosure, a method for controlling a hydraulic cylinder is provided. The hydraulic cylinder is provided with a chamber and configured to receive fluid from a valve. The method includes receiving a user input and determining a desired velocity of the hydraulic cylinder in accordance with the user input. In addition, the velocity of the hydraulic cylinder is measured and a position of the valve is determined in accordance with the desired velocity of the hydraulic cylinder and the measured velocity of the hydraulic cylinder. The method further includes determining a desired force to be applied to the valve in accordance with a difference between the desired and measured velocities of the hydraulic cylinder, and actuating the valve in accordance with the desired force to thereby inject the fluid into the chamber and move the hydraulic cylinder.

Abstract: A method and apparatus for determining the operating health of a hydraulic system are provided. The method may include the steps of determining a plurality of operating parameters of the hydraulic system during operation of the hydraulic system, determining an estimated working condition value of the hydraulic system, modifying the estimated working condition value as a function of the operating parameters, and determining the operating health of the hydraulic system as a function of the working condition value. In one method, the working condition value may be indicative of an effective bulk modulus value of an operating fluid within at least part of the hydraulic system.

Abstract: A method and apparatus for determining the operating health of a hydraulic system are provided. The method may include the steps of determining a plurality of operating parameters of the hydraulic system during operation of the hydraulic system, determining an estimated working condition value of the hydraulic system, modifying the estimated working condition value as a function of the operating parameters, and determining the operating health of the hydraulic system as a function of the working condition value. In one method, the working condition value may be indicative of an effective bulk modulus value of an operating fluid within at least part of the hydraulic system.

Abstract: Consistent with an aspect of the disclosure, a method for controlling a hydraulic cylinder is provided. The hydraulic cylinder is provided with a chamber and configured to receive fluid from a valve. The method includes receiving a user input and determining a desired velocity of the hydraulic cylinder in accordance with the user input. In addition, the velocity of the hydraulic cylinder is measured and a position of the valve is determined in accordance with the desired velocity of the hydraulic cylinder and the measured velocity of the hydraulic cylinder. The method further includes determining a desired force to be applied to the valve in accordance with a difference between the desired and measured velocities of the hydraulic cylinder, and actuating the valve in accordance with the desired force to thereby inject the fluid into the chamber and move the hydraulic cylinder.

Abstract: A method is provided for controlling braking in a vehicle having a motor and a brake. The method includes sensing an actual operating parameter of the motor and receiving a desired operating parameter of the motor. The motor is controlled based on the actual operating parameter and the desired operating parameter of the motor. The brake is controlled based on the actual operating parameter and the desired operating parameter of the motor and an output from the motor control.

Abstract: A method and apparatus for determining the operating health of a hydraulic system are provided. The method may include the steps of determining a plurality of operating parameters of the hydraulic system during operation of the hydraulic system, determining an estimated working condition value of the hydraulic system, modifying the estimated working condition value as a function of the operating parameters, and determining the operating health of the hydraulic system as a function of the working condition value. In one method, the working condition value may be indicative of an effective bulk modulus value of an operating fluid within at least part of the hydraulic system.