Husco International, Inc.

Incova Technologies, Inc.

Quadtech, Inc.

Keith A Tabor

Joseph Lawrence Pfaff

Dwight B Stephenson

Eric P Hamkins

Brian R Bertolasi

Lawrence R Peters

Robert Knier

Mark Hackler

Michael J Horvath

A hydraulic system has a valve assembly with two workports coupled to chambers of first and second cylinders which are connected mechanically in parallel to a machine component. A separation control valve is connected between first chambers of both cylinders, and a shunt control valve is connected between the workports. A recovery control valve couples an accumulator to the first chamber of the second cylinder. Opening and closing the valves in different combinations routes fluid from one or both cylinders into the accumulator where the fluid is stored under pressure, and thereafter enables stored fluid to be used to power one or both cylinders. The shunt control valve is used to route fluid exhausting from one chamber of each cylinder to the other chambers of those cylinders. Thus the hydraulic system recovers and reuses energy in various manners.

Energy recovery and reuse techniques for a hydraulic system

A member of a machine, such as a boom on construction equipment for example, is pivoted by a first actuator and has a length that is alterable by a second actuator. A control method allows an operator of the machine to command a point on the member to move along a straight line path. The operator command specifies velocities along two orthogonal axes and those velocities are transformed into an angular velocity and a length velocity for the member. The angular velocity and a length velocity then are converted into individual velocities for the first and second actuators. Each actuator is operated at its respective velocity to achieve the commanded movement of the member.

Hydraulic system with coordinated multiple axis control of a machine member

A method provides several modes for recovering hydraulic energy produced by an overrunning load acting on cylinders connected in parallel to a machine component. In one mode, fluid from first chambers in both cylinders is routed into the accumulator, while other fluid is directed into second chambers of those cylinders. In a different mode, fluid is routed from the first chamber of only one cylinder into the accumulator, and fluid from the first chamber of the other cylinder goes into the second chambers of both cylinders. Yet another mode comprises routing fluid from the first chambers of both cylinders into the second chambers of both cylinders. In still another mode, fluid from the first chambers of both cylinders goes into the return conduit while the second chambers of both cylinders receive fluid from a supply conduit. Several modes of reusing the recovered energy are described.

Energy recovery and reuse methods for a hydraulic system

Motion of a hydraulically driven machine component is controlled in response to a velocity command that indicates a desired velocity for the machine component. A method for detecting a velocity fault involves determining an actual velocity at which the machine component is moving, and producing a velocity error value based on a difference between the velocity command and the actual velocity. The velocity error value is integrated, such as by a low pass, biquadratic filter function, to produce an integrated value. The integrated value is compared to one or more thresholds to determine whether a velocity fault has occurred.

Electrohydraulic valve control circuit with velocity fault detection and rectification

A system operates a hydraulic actuator, such as a cylinder, in one of several modes that include powered extension and retraction, self-powering regeneration modes in which fluid exhausting from one cylinder chamber is routed into the other cylinder chamber, and cross function regeneration modes wherein the fluid exhausted from one actuator is routed in the supply conduit to power a different actuator. A controller determines which modes are viable based on existing system conditions and selects from among the viable available modes. That determination is a function of the desired velocity for the actuator, the hydraulic load on the actuator, and pressures in the supply and return hydraulic conduits. The system also can recover potential or kinetic energy through pressure intensification which recovered energy can be used to power another simultaneously active hydraulic function or to drive the prime mover via an over-center variable pump/motor.

Hydraulic control system with cross function regeneration

A hydraulic system has an electrohydraulic valve that controls flow of fluid to operate a hydraulic actuator, such as a cylinder or motor. A set of characterization data is provided which describes performance of the electrohydraulic valve as a function of changes in differential pressure across that valve. The hydraulic system is operated by specifying desired movement of the hydraulic actuator and in response deriving a desired valve flow coefficient which designates a level of fluid flow through the electrohydraulic valve. A compensated control signal is produced from the desired valve flow coefficient and the characterization data, to counter act effects that changes in differential pressure have on flow of fluid. The electrohydraulic valve is activated in response to the compensated control signal.

Hydraulic system control method using a differential pressure compensated flow coefficient

A servomechanism includes a controller which dynamically estimates the resistance of the solenoid coil in an electrohydraulic valve as part of determining a level of electric voltage to apply to open the valve. The servomechanism receives a current setpoint designating a desired electric current level and senses the actual level of current flowing through the coil. A proportional term is derived from the current setpoint and the actual level of current. Creation of a derivative term is based on the difference between the current setpoint and the actual level of current. A feedforward term is produced by estimating the resistance of the electrohydraulic valve and limiting the feedforward term to a predefined range of acceptable values. The proportional term, derivative term, and the feedforward term are summed to define a desired voltage level, and a PWM signal for driving the electrohydraulic valve is generated based on the desired voltage level.

Electrohydraulic valve servomechanism with adaptive resistance estimator

Pressure trapped in an inactive hydraulic actuator can result in the actuator moving in a direction which is opposite to that desired upon subsequent activation. The present method detects a trapped pressure condition and takes remedial action before activating the hydraulic actuator for motion. The pressure differentials across valves that control the fluid flow to and from the hydraulic actuator are used to detect a trapped pressure condition. In response to that detection, a selected valve is initially opened in a manner that releases the trapped pressure while producing motion in the desired direction. After the trapped pressure condition has been resolved, one or more other valves are operated to produce the desired motion of the hydraulic actuator.

Hydraulic system with mechanism for relieving pressure trapped in an actuator

A hydraulic circuit branch includes a hydraulic actuator, such as a cylinder, and an assembly of one or more electrohydraulic proportional valves connected in series between a pressurized fluid supply line and a tank return line. The force acting on the hydraulic actuator is determined by sensing fluid pressures produced by the hydraulic actuator. Pressures in the supply and tank return lines also are sensed. The sensed pressures and a desired velocity for the hydraulic actuator are employed to determine an equivalent flow coefficient, which characterizes fluid flow through the hydraulic circuit branch, either a conduction or restriction coefficient may be derived. The equivalent flow coefficient is used to determine how to activate each electrohydraulic proportional valve to achieve the desired velocity of the hydraulic actuator. The equivalent flow coefficient also is employed to control the pressure levels in the supply and tank return lines.

Velocity based method for controlling a hydraulic system

The flow of fluid to a hydraulic actuator is controlled by a valve assembly which operates in different metering modes at various points in time. The metering mode to use in selected in response to the hydraulic load that acts on the valve associated with the hydraulic actuator. Specifically the load is determined and then compared to threshold levels associated with the different metering modes to choose the metering mode for use a given point in time.

Method of selecting a hydraulic metering mode for a function of a velocity based control system

A plurality of hydraulic actuators are connected between a supply line and a tank return line. A separate desired velocity is requested for each hydraulic actuator. In response to a respective metering mode and the desired velocity for each hydraulic actuator, the flow requirements that each hydraulic actuator has from the supply and return lines are derived. A determination is made as to what fractions of the required flows can be provided by the flow levels that are available from the supply and return lines. Those fractions are used to convert the desired velocity for the given hydraulic actuator into a velocity command which indicates the velocity of the given hydraulic actuator that can be achieved with the available fluid flows. The respective velocity command is used to control the flow of fluid to each hydraulic actuator.

Method of sharing flow of fluid among multiple hydraulic functions in a velocity based control system

An actuator is part of a hydraulic circuit branch that has a first electrohydraulic proportional valve connecting the actuator to a supply line containing pressurized fluid and a second electrohydraulic proportional valve connecting the actuator to a tank return line. A method for operating the valves includes requesting a desired velocity for the hydraulic actuator and sensing a parameter which varies with changes of a force on the actuator. The desired velocity and the parameter are used to derive an equivalent flow coefficient which characterizes fluid flow in the hydraulic circuit. From the equivalent flow coefficient, first and second valve flow coefficient are derived and then employed to activate each of the first and second electrohydraulic proportional valves. The coefficients may characterize either conductance or restriction in the respective part of the hydraulic system.

Velocity based method of controlling an electrohydraulic proportional control valve

An apparatus and method for creating vibration of an appendage of a work vehicle is disclosed. The apparatus includes a hydraulic cylinder, first and second valve assemblies, and a control element. The hydraulic cylinder is coupled between a first portion of the work vehicle and the appendage and includes a first chamber, a second chamber, and a piston. The first and second valve assemblies respectively govern whether hydraulic fluid is provided from a pump to, or to a tank from, the first and second chambers. The control element automatically causes a status of the second valve assembly to repeatedly alternate with time so that the vibration occurs at the piston and is in turn provided to the appendage.

Apparatus and method for providing vibration to an appendage of a work vehicle

A control system for operating a hydraulic system includes a user input device which generates an input signal indicating desired movement of a hydraulic actuator. A mapping routine converts the input signal into a velocity command indicating desired actuator velocity. A valve opening routine transforms the velocity command into a flow coefficient which characterizes fluid flow through the valve assembly and from the flow coefficient produces a set of control signals designating levels of electric current to apply to valves within the valve assembly. A pressure controller regulates pressure in the supply line in response to the velocity command. When the hydraulic system has a plurality of functions, the control system adjusts each velocity command to equitably apportion fluid to each function when the aggregate flow being demanded by the functions exceeds the total flow available from a source.

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Richfield, WI, United States of America

Keith A Tabor