BACKGROUND

The present disclosure relates to a float and blade impact systems and valve configurations for such systems.

SUMMARY

In one embodiment, the disclosure provides a work vehicle including a frame, a prime mover connected to the frame, an operator cab connected to the frame, a work implement that moves with respect to the frame, and a control circuit that controls movement of the work implement. The control circuit includes a pump, and an actuator in fluid communication with the pump. The actuator includes a first side and a second side. A control valve is fluidly positioned between the pump and the actuator, a controller is in electrical communication with the control valve, and a reservoir is in fluid communication with the actuator. A first proportional pressure relief valve is fluidly positioned between the reservoir and the first side of the actuator. The first proportional pressure relief valve permits flow of fluid from the first side of actuator to the reservoir in response to a pressure at the first side of the actuator being greater than a predetermined pressure value. A second proportional pressure relief valve is fluidly positioned between the reservoir and the second side of the actuator.

In one embodiment, the disclosure provides a control system operable to control movement of a work implement of a work vehicle. The control system includes a reservoir that retains fluid, a pump in fluid communication with the reservoir, and an actuator in fluid communication with the pump. The actuator has a first side and a second side. A control valve is fluidly positioned between the pump and the actuator, a first proportional relief valve is fluidly positioned between the pump and the first side of the actuator, and a second proportional relief valve is fluidly positioned between the pump and the second side of the actuator. The first proportional relief valve is configured to permit flow of fluid from the first side of the actuator to the reservoir when a pressure at the first side of the actuator exceeds a pressure set point.

In another embodiment the disclosure provides a method of moving a work implement of a work vehicle in response to an impact force. The method includes setting a first set point pressure at which a first proportional relief valve opens via an operator positioned in the work vehicle, setting a second set point pressure at which a second proportional relief valve opens via the operator positioned in the work vehicle, monitoring an actuator to detect movement thereof from a first position, permitting fluid flow between a first side of the actuator, a reservoir and a pump while the first proportional relief valve is open, and permitting fluid flow between a second side of the actuator, the reservoir and the pump while the second proportional relief valve is open. Upon movement of the actuator from the first position, the method includes determining if an operator commanded the actuator to move. If an operator commanded the actuator to move, the method includes detecting a second position of the actuator, and if an operator did not command the actuator to move, the method includes permitting fluid flow to the first side of the actuator from the pump to thereby move the actuator back to the first position.

In another embodiment the disclosure provides a method of moving a work implement of a work vehicle. The method includes setting a downward force on the work implement, determining a set position of the work implement, permitting fluid flow between a first side of an actuator, a reservoir and a pump while a first proportional relief valve is open, and permitting fluid flow between a second side of the actuator, the reservoir and the pump while a second proportional relief valve is open. Upon movement of the work implement from the set position, the method includes determining if the work implement moved upward or downward from the set position. If the work implement moved upward from the set position, the controller sends a first signal to the first proportional relief valve and to the second proportional relief valve to increase the downward force on the work implement to thereby inhibit further upward movement of the work implement. If the work implement moved downward from the set position, the controller sends a second signal to the first proportional relief valve and to the second proportional relief valve to decrease the downward force on the work implement to inhibit further downward movement of the work implement.

Other aspects of the disclosure will become apparent by consideration of the detailed description and accompanying drawings.

