Parker-hannifin Corporation

Ralf Gomm

Dale Vanderlaan

Björn Eriksson

Vivek Bhaskar

Randall Denman Thompson

Amir Shenouda

Christian Josefsson

Bjoern Eriksson

A hydraulic system includes one or more hydraulic subsystems that have a source of additional flow for supplying an auxiliary system. The hydraulic system may include one or more actuator systems, a boost system, and a further hydraulic system, such as a steering system. The source of additional flow for supplying the auxiliary system may include: sizing the boost system for providing both full boost function and auxiliary function, sizing the steering system for providing both full steering function and auxiliary function, utilizing available flow from an unused actuator function, and/or utilizing a selector manifold for actively selecting the source of auxiliary flow based on the flow and pressure demands of the respective hydraulic systems. Such a hydraulic system enables flow to be available to an auxiliary function regardless of the flow requirements for the actuator functions and/or other vehicle functions, while also minimizing interactions and flow disruptions to the various hydraulic subsystems.

Auxiliary system for vehicle implements

Provided is a system and method to generate and control hydraulic fluid flow that exceeds the fluid flow capacity of an electrically driven pump to achieve high actuator retraction/extension speeds and/or electrical flow capacity of an electrical storage system to better control electrical storage. Electric machines and hydraulic pumps generally have a maximum speed beyond which they cannot be operated at. Further, electrical storage systems typically have storage capacities and rates beyond which they cannot be operated at. While an alternate approach could be to increase the hydraulic pump displacement, thus lowering the required electric machine and pump speed to generate a certain flow, it is typically desirable to reduce pump displacement in order to reduce required electric machine torque and minimize component size and losses.

Method of increasing electro-hydrostatic actuator piston velocity

An electro-hydraulic actuation system includes a regeneration valve in fluid communication with a first fluid chamber and a second fluid chamber of a hydraulic actuator, and a dump valve is in fluid communication with the second fluid chamber and a fluid reservoir. A pump provides a flow of fluid to the first and second fluid chambers, a displacement of the pump controlling a velocity of the actuator during motion in the retraction and extension directions. An electric motor drives the pump, and a controller controls a state of the regeneration valve and the dump valve. At least one feedback device senses a system condition and provides a respective feedback signal indicative of the sensed system condition to the controller, the controller responsive to the feedback signal to determine an occurrence of an over-center load condition and control a state of the regeneration valve and the dump valve in response to the occurrence to maintain the velocity of the actuator.

Method of controlling velocity of a hydraulic actuator in over-center linkage systems

A method and system is provided for controlling a hydraulic actuator in a work machine by opening a load holding valve in a measured fashion in order to leak hydraulic pressure back into a depressurized portion of the hydraulic circuit, thereby minimizing or eliminating jerkiness in the actuator when the actuator is under an external load.

Smooth control of hydraulic actuator

According to one aspect of the invention, a hydraulic system includes a controller connected to an operator interface, a pump operable in a first direction for supplying pressurized fluid, and a load-holding valve connected between the pump and a port for connection to an actuator. The load-holding valve may be controlled by the controller and operative in a first position to allow flow to the actuator to operate the actuator against a load and operative in a second position to block load-induced return flow from the actuator to the pump. The controller may be configured to receive a requested actuator stop, to control the first valve to move to the second position in response to the requested actuator stop, to monitor a first system condition in response to the requested actuator stop, to evaluate the monitored system condition with a prescribed criteria, and to determine whether or not to initiate a back-up control routine based on the evaluation.

Method to detect hydraulic valve failure in hydraulic system

Presented is a system and method to control hydraulic fluid flow, more specifically throttle hydraulic fluid flow, to achieve actuator deceleration rates greater than the maximum deceleration rate of an electrically driven pump. Electric machines and electric machine inverters generally have a maximum torque and current limit beyond which they cannot be operated at. To decelerate a large inertia load for example, high electric machine torque and inverter current are required to provide the braking torque, opposing the fluid flow and pressure generated by the load and hydraulic system.

Electro-hydrostatic actuator deceleration rate control system

In conventional load-sense systems, there is a delay between a hydraulic function being impeded by an external force and further motion of the function. This is typically due to cavitation on the low pressure side of the pump. Electro-hydraulic systems, however, typically respond very quickly because the low pressure side of the pump may be pressurized because the low-pressure side of the actuator may feed directly to the pump rather than going to tank. Thus, an operator cannot as easily rely on feedback for when a function has encountered an external load. This may result in loss of vehicle traction or other drawbacks. Therefore, provided is a system and method for mimicking a load-sense system's responsiveness using an electro-hydrostatic system via an induced passive or active time-delay.

Method for controlling pressure in a hydraulic actuator

An electro-hydraulic actuation system () includes an unbalanced hydraulic actuator () capable of motion in retraction and extension directions during movement of a load (). A pump () provides a flow of fluid to the actuator. A displacement of the pump controls a velocity of the actuator during motion in the retraction and extension directions. An electric motor () drives the pump. Speed and direction of the electric motor affects the displacement of the pump. A controller () controls the speed and direction of the electric motor. A feedback device () is operable for sensing a system condition and for providing a feedback signal indicative of the sensed system condition to the controller. The controller is responsive to the feedback signal for determining an occurrence of an over-center load condition and for modifying the speed of the electric motor in response to the occurrence in an attempt to maintain the velocity of the actuator.

Velocity control of unbalanced hydraulic actuator subjected to over-center load conditions

A method of controlling an electro-hydraulic actuator system having multiple functions includes the steps of: receiving input signals corresponding to a desired operation of the functions of the system; establishing an operating limit for the system; determining an operating characteristic of the system; using the operating limit and the determined operating characteristic to determine a limitation control factor; and influencing the received input signal with the determined limitation control factor for operating the system within the established operating limit.

Method of controlling an electro-hydraulic actuator system having multiple actuators

An electrical interlock system for including a power takeoff device operable in a first state to transfer mechanical energy from an associated combustible engine to an associated electric motor and/or generator and operative in a second state to prevent the transfer of mechanical energy from the associated combustible engine to the associated electric motor and/or generator. A relay having a first switch and an energizable portion, is coupled to the power takeoff device, the electric motor and an associated power source, such that when the energizable portion is receiving electrical power from the associated power source, the power takeoff device is in the first state and when the energizable portion is not receiving electrical power from the associated power source, the power takeoff device is in the second state.

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Charlotte, NC, United States of America

Ralf Gomm