Agricultural system
A hydraulic control system for controlling the down force on an agricultural implement comprises a hydraulic cylinder containing a movable ram, a source of pressurized fluid coupled to the hydraulic cylinder on a first side of the ram by a first controllable valve, a fluid sump coupled to the hydraulic cylinder on the first side of the ram by a second controllable valve, and an electrical controller coupled to the valves for opening and closing the valves. The valves may be self-latching valves that remain in an open or closed position until moved to the other position in response to a signal from the controller.
1. A hydraulic control system for controlling the down force on an agricultural implement, comprising
a hydraulic cylinder containing a movable ram,
a source of pressurized fluid coupled to said hydraulic cylinder on a first side of said movable ram by a first controllable valve,
a fluid sump coupled to said hydraulic cylinder on said first side of said movable ram by a second controllable valve,
an electrical controller coupled to said first and second controllable valves for opening and closing said first and second controllable valves,
a pair of energy storage devices coupled to said hydraulic cylinder on opposite sides of said movable ram, and
a check valve coupling said hydraulic cylinder to said energy storage device.
2. The hydraulic control system of claim 1 which includes a second check valve coupling said hydraulic cylinder to said first and second controllable valves.
3. A hydraulic control system for controlling the down force on an agricultural implement, comprising
a hydraulic cylinder containing a movable ram,
a source of pressurized fluid coupled to said hydraulic cylinder on a first side of said movable ram by a first controllable valve,
a fluid sump coupled to said hydraulic cylinder on said first side of said movable ram by a second controllable valve, and
an electrical controller coupled to said first and second controllable valves for opening and closing said first and second controllable valves,
a pressure transducer coupled to said hydraulic cylinder on one side of said movable ram,
a down pressure controller for controlling the down pressure on at least a portion of the implement, and
a load sensor comprising
a mechanical element mounted for movement in response to the downward force applied to the implement,
a fluid-containing device containing a movable element coupled to said mechanical element for changing the fluid pressure in response to the movement of said mechanical element, and
a transducer coupled to said fluid-containing device for producing an output signal in response to changes in said fluid pressure.
4. The hydraulic control system of claim 3 which includes an energy storage device coupled to said fluid-containing device for receiving a limited amount of fluid in response to changes in said fluid pressure to damp pressure spikes in the output signal of said transducer.
5. The hydraulic control system of claim 4 in which said energy storage device is an accumulator receiving pressurized fluid from said fluid-containing device, said accumulator containing a movable element responsive to the pressure of the fluid received from said fluid-containing device.