Abstract: An energy recovery system for a machine is disclosed. The energy recovery system may have a tank, a pump configured to draw fluid from the tank and pressurize the fluid, an actuator, and an actuator control valve movable to direct pressurized fluid from the pump to the actuator and from the actuator to the tank to move the actuator. The energy recovery system may also have a motor connected to selectively receive fluid discharged from the actuator and mechanically connected to the pump, and an accumulator configured to store fluid discharged from the motor and to direct stored fluid to the motor to drive the pump.

Abstract: An energy recovery system for a machine is disclosed. The energy recovery system may have a boom circuit with at least a one linear actuator configured to move a work tool, and a boom accumulator configured to selectively collect pressurized fluid from the at least one linear actuator and to discharge pressurized fluid back to the at least one linear actuator. The energy recovery system may also have a swing circuit with a swing motor configured to move the work tool, and a swing accumulator configured to selectively collect pressurized fluid from the swing motor and discharge pressurized fluid back to the swing motor. The energy recovery system may further have a common accumulator passage fluidly connecting the boom accumulator and the swing accumulator.

Abstract: A hydraulic control system includes an implement movable to perform an excavation cycle having a plurality of segments, a variable displacement motor configured to swing the implement at a desired speed during the excavation cycle, and a pump configured to pressurize fluid directed to drive the motor. The system further includes an accumulator configured to selectively receive fluid discharged from the motor via a charge valve, and to discharge fluid to the motor via a discharge valve. The system includes a selector valve fluidly connected to the charge valve and the discharge valve. The system also includes a controller configured to vary displacement of the motor, resulting in the desired speed.

Abstract: A hydraulic control system is disclosed for use with a machine. The hydraulic control system may have a tank, a pump, an actuator, and a control valve configured to direct fluid from the pump to the actuator and from the actuator to the tank. The hydraulic control system may also have a pressure sensor to generate a first signal indicative of a pressure differential across the control valve, an operator input device to generate a second signal indicative of a desired movement of the actuator, and a controller. The controller may be configured to make a first determination of an opening amount of the control valve based on the second signal, and to make a second determination based on the first signal of whether the opening amount will result in overspeeding of the actuator. The controller may also be configured to reduce the opening amount based on the second determination.

Abstract: A hydraulic control system is disclosed for use with a machine. The hydraulic control system may have a tank, a pump, a swing motor, and at least one control valve configured to control fluid flow between the pump, the swing motor, and the tank. The hydraulic system may also have an accumulator configured to selectively receive pressurized fluid discharged from the swing motor and selectively supply pressurized fluid to the swing motor, at least one accumulator valve, and a controller. The controller may be configured to receive input indicative of a difference between desired and actual speeds of the swing motor, and determine if the swing motor is accelerating or decelerating based on the difference. The controller may also be configured to control the at least one accumulator valve to cause the accumulator to selectively receive or supply pressurized fluid only when the swing motor is accelerating or decelerating.

Abstract: A hydraulic control system is disclosed. The hydraulic control system may have an input device to generate a first signal indicative of a desired swing motor movement, and a control valve configured to selectively pass fluid to the swing motor and drain from the swing motor to drive the swing motor based on the first signal. The hydraulic control system may also have a pressure sensor to generate a second signal indicative of a swing motor pressure, a speed sensor configured to a third signal indicative of a swing motor speed, and a controller configured to make a comparison of at least one of the swing motor speed and the swing motor pressure with a threshold speed and a threshold pressure, and open the control valve to drain fluid from the swing motor to the tank based on the comparison when the input device is in a neutral condition.

Abstract: A hydraulic control system for a machine is disclosed. The hydraulic control system may have a tank, a pump, and a fluid actuator. The hydraulic control system may further have an accumulator configured to selectively receive pressurized fluid discharged from the fluid actuator and selectively supply pressurized fluid to the fluid actuator. The hydraulic control system may also have a pressure sensor configured to generate a signal indicative of a pressure of the accumulator, a charge valve, a discharge valve, and a controller in communication with the control valve, the charge valve, and the discharge valve. The controller may be configured to detect stall of the fluid actuator, to make a comparison of the pressure of the accumulator with a threshold pressure, and to selectively move the charge valve to charge the accumulator or move the discharge valve to discharge the accumulator during the stall based on the comparison.

Abstract: A hydraulic control system is disclosed for use with a machine. The hydraulic control system may have a tank, a pump, a swing motor, and at least one control. The hydraulic control system may further have an accumulator configured to receive fluid from and supply fluid to the swing motor, a charge valve movable to allow fluid flow from the swing motor into the accumulator, and a discharge valve movable to allow fluid flow from the accumulator to the swing motor. The hydraulic control system may additionally have a controller in communication with the at least one control valve, the charge valve, and the discharge valve. The controller may be configured to detect an acceleration of the swing motor, selectively cause the discharge valve to assist the acceleration, and selectively move the charge valve to an open position to recover energy associated with pressure spikes occurring during the acceleration.

Abstract: A hydraulic system is disclosed that includes a hydraulic actuator having a head end, a rod end and a piston disposed therebetween. The system also includes a pump configured to supply fluid to both ends of the actuator. The system also includes an energy conservation system that is configured to reduce flow from the pump to the head end of the actuator and to increase flow from a make-up fluid circuit to the head end of the actuator during an overrunning load condition. The energy conservation system also increases flow from the pump to the head end of the actuator and decreases flow from the make-up circuit to the head end of the actuator after the overrunning load condition has ceased.

Abstract: A hydraulic system includes a hydraulic actuator, a pump configured to supply fluid to the hydraulic actuator, and a first accumulator fluidly connected to the hydraulic actuator. The first accumulator is configured to store fluid received from the hydraulic actuator. The hydraulic system also includes a motor drivingly connected to the pump and fluidly connected to the first accumulator. The motor is configured to receive the stored fluid from the first accumulator to drive the pump. The hydraulic system further includes a first discharge valve fluidly connected between the first accumulator and the hydraulic actuator. The first discharge valve is configured to supply the stored fluid from the first accumulator to the hydraulic actuator without the stored fluid from the first accumulator circulating through the pump.

Abstract: A hydraulic control system is disclosed for use with a machine. The hydraulic control system may have a pump, a tank, and an actuator. The hydraulic control system may also have at least a first valve configured to control fluid flow between the pump, the tank, a first chamber of the actuator, and a second chamber of the actuator; a second valve fluidly disposed between the second chamber and the tank; and a third valve fluidly disposed between the first and second chambers. The hydraulic control system may further have a controller configured to selectively cause the second valve to block fluid flow from the second chamber of the actuator to the tank, and to selectively cause the third valve to fluidly communicate the first and second chambers of the actuator when the second valve blocks fluid flow from the second chamber of the actuator to the tank.

Abstract: A system including a hydraulic accumulator, a pressure sensor, a fluid source and a data processor to detect a pre-charge pressure is provided. The hydraulic accumulator includes first and second fluid chambers and a separator therebetween. The hydraulic accumulator has an associated pre-charge pressure. The pressure sensor is connected to the first fluid chamber. The data processor is connected to the pressure sensor. The data processor is configured to determine a first and second rate of pressure changes, and a transition pressure between the first and second rates. The approximate pre-charge pressure is determined based on the transition pressure.

Abstract: A system to diagnose a health of a hydraulic accumulator is provided. The hydraulic accumulator includes a first fluid chamber, a second fluid chamber, and a separator. The hydraulic accumulator has an associated pre-charge pressure. The system further includes a pressure sensor, a fluid source, a data processor, and a comparator. The pressure sensor and the fluid source are connected to the first fluid chamber. The data processor is configured to determine a first and second rate of pressure changes, and a transition pressure between the first and second rates. The approximate pre-charge pressure is determined based on the transition pressure. The comparator is configured to compare at least one of the determined pre charge pressure and the frictional forces with a pre-determined threshold range of pre-charge pressure and the frictional forces associated with the hydraulic accumulator to diagnose the health of the hydraulic accumulator.

Abstract: A hydraulic control system for a machine is disclosed. The hydraulic control system may have a work tool movable to perform an excavation cycle having a plurality of segments, a motor configured to swing the work tool during the excavation cycle, and a pump configured to pressurize fluid directed to drive the motor. The hydraulic control system may also have at least one accumulator configured to selectively receive fluid discharged from the motor and to discharge fluid to the motor during the plurality of segments, and a controller configured to implement a plurality of modes of operation. Each of the plurality of modes of operation includes a different combination of segments during which the at least one accumulator receives and discharges fluid.

Abstract: A hydraulic control system for a machine is disclosed. The hydraulic control system may have a work tool movable through segments of an excavation cycle, a motor configured to swing the work tool during the excavation cycle, at least one accumulator configured to selectively receive fluid discharged from the motor and to discharge fluid to the motor during the excavation cycle, and a controller. The controller may be configured to receive input regarding a current excavation cycle of the work tool, and make a determination based on the input that the current excavation cycle is associated with one of a set of known modes of operation. The controller may be further configured to cause the at least one accumulator to receive fluid and discharge fluid during different segments of the excavation cycle based on the determination.

Abstract: An energy recovery retrofit kit for a hydraulic control system is disclosed. The energy recover retrofit kit may have a first accumulator and a second accumulator. The energy recover retrofit kit may also have a recovery valve block fluidly connectable between an existing pump and an existing motor of the hydraulic system. The recovery valve block may be configured to selectively fluidly communicate the first and second accumulators with the existing motor.

Abstract: A swing energy recovery system for a machine is disclosed. The swing energy recovery system may have a pump configured to pressurize fluid, a motor driven by a flow of pressurized fluid from the pump, and an energy recovery arrangement configured to receive pressurized fluid discharged from the motor and selectively supply pressurized fluid to the motor. The swing energy recovery system may also have a pressure relief valve associated with the motor, and a controller in communication with the energy recovery arrangement and the pressure relief valve. The controller may be configured to selectively adjust a setting of the pressure relief valve based on an operating condition of the energy recovery arrangement.

Abstract: A hydraulic control system for a machine is disclosed. The hydraulic control system may have a pump configured to pressurize fluid, and a motor driven by a flow of pressurized fluid from the pump. The hydraulic control system may also have a first accumulator configured to receive pressurized fluid discharged from the motor and to selectively supply pressurized fluid to the motor, and a second accumulator configured to receive pressurized fluid discharged from the motor and selectively supply pressurized fluid to the motor.

Abstract: A hydraulic control system for a machine is disclosed. The hydraulic control system may have a tank, a pump configured to draw fluid from the tank and pressurize the fluid, a swing motor configured to receive the pressurized fluid and swing a body of the machine relative to an undercarriage, and a tool actuator configured to receive the pressurized fluid and move a tool relative to the body. The hydraulic control system may also have an energy recovery device configured to convert hydraulic energy to mechanical energy, a first accumulator configured to store waste fluid received from the swing motor, and a second accumulator configured to store waste fluid received from the tool actuator. Stored waste fluid from at least one of the first and second accumulators may be selectively discharged into the energy recovery device.

Abstract: A method of calibrating an electrically controlled hydraulic valve having a known relationship between flow rate through the valve and displacement of a valve element is disclosed. The method includes ascertaining a first current level for actuating the electrically controlled hydraulic valve to move the valve element to a position adjacent an inlet port, and a first displacement of the valve element responsive to the first current level. The method also includes ascertaining a second current level for actuating the electrically controlled hydraulic valve to move the valve element from the position adjacent the inlet port to a position permitting flow through the inlet port, and ascertaining a second displacement of the valve element responsive to the second current level. The method further includes establishing a relationship between current and displacement associated with the electrically controlled hydraulic valve.