Electro-hydraulic metering valve with integral flow control
View Patent ↗A metering valve for a work machine hydraulic system is disclosed. The metering valve has a valve body with an inlet and an outlet. The metering valve also has a main poppet disposed within the valve body between the inlet and the outlet. The main poppet has a nose end and a chamber end, and is movable between a flow-passing position at which fluid flows from the inlet to the outlet, and a flow-blocking position at which fluid flow between the inlet and outlet is blocked. The metering valve also has a pilot element movable to selectively communicate the chamber end of the main poppet with a drain, thereby affecting movement of the main poppet between the flow-passing and flow-blocking positions. The metering valve further has a solenoid mechanism operable to move the pilot element. The position of the pilot element is affected by a fluid pressure at the inlet.
1. A metering valve, comprising:
a valve body having an inlet and an outlet;
a main poppet being disposed within the valve body between the inlet and the outlet, having a nose end and a chamber end, and being movable between a flow-passing position at which fluid flows from the inlet to the outlet, and a flow-blocking position at which fluid flow between the inlet and outlet is blocked;
a pilot element movable to selectively communicate the chamber end of the main poppet with a drain in fluid communication with the outlet, thereby affecting movement of the main poppet between the flow-passing and flow-blocking positions; and
a solenoid mechanism operable to move the pilot element,
wherein the position of the pilot element is affected by a fluid pressure at the inlet of the valve body.
2. The metering valve of claim 1 , wherein the solenoid mechanism is operable to move the pilot element a predetermined amount, thereby moving the main poppet a predetermined amount.
3. The metering valve of claim 2 , wherein the predetermined amount is based on an assumed fluid pressure at the inlet.
4. The metering valve of claim 3 , wherein the pilot element is movable in response to the fluid pressure at the inlet to maintain a substantially constant flow rate of fluid from the inlet to the outlet.
5. The metering valve of claim 1 , wherein the pilot element includes:
an adjuster connected to the solenoid mechanism and configured to adjust a position of the pilot element relative to the solenoid mechanism; and
a check element connected to the adjuster.
6. The metering valve of claim 1 , further including a spring disposed between the pilot element and the main poppet.
7. The metering valve of claim 1 , further including:
an adapter disposed within the valve body;
a spring disposed between the adapter and the main poppet; and
a spring disposed between the adapter and the pilot element.
8. The metering valve of claim 7 , further including a pin preventing disassembly of the main poppet from the adapter.
9. The metering valve of claim 1 , further including a central bore extending through the pilot element.
10. The metering valve of claim 9 , wherein the solenoid mechanism includes:
an electromagnet coil;
an armature;
a pin element connected to the armature; and
a central bore extending through the armature and pin element and being in communication with the central bore of the pilot element.
11. The metering valve of claim 10 , further including:
a central bore extending through the main poppet and being in communication with the central bore of the pilot element; and
a check valve element disposed within the central bore of the main poppet.
12. A method of operating a metering valve including a valve body having an inlet and an outlet, and a main poppet having a nose end and a chamber end; the method, comprising:
directing a flow of pressurized fluid to the main poppet of the metering valve;
electronically moving a pilot element to hydraulically move the main poppet to a predetermined position and allow the pressurized fluid to flow through the metering valve at a desired rate,
wherein moving the main poppet includes placing the chamber end of the main poppet in fluid communication with the outlet; and
automatically hydraulically adjusting the position of the pilot element in response to a pressure of the fluid to maintain the desired flow rate through the metering valve.
13. The method of claim 12 , wherein the predetermined position is based on an assumed fluid pressure.
14. The method of claim 12 , further including mechanically adjusting the position of the pilot element relative to a solenoid mechanism.
15. The method of claim 12 , further including mechanically biasing the pilot element and the main poppet toward flow-blocking positions.
16. The method of claim 12 , further including allowing fluid to pass through the pilot element during movement of the pilot element.
17. The method of claim 12 , further including:
allowing fluid to pass through the main poppet; and
restricting the flow of fluid through the main poppet to a single flow direction.
18. A work machine, comprising:
a work tool;
a hydraulic cylinder operatively connected to move the work tool and having a at least one chamber;
a source of pressurized fluid in communication with the at least one chamber; and
a metering valve configured to meter the pressurized fluid into the at least one chamber, the metering valve including;
a valve body having an inlet and an outlet;
a main poppet being disposed within the valve body between the inlet and the outlet, having a nose end and a chamber end, and being movable between a flow-passing position at which fluid flows from the inlet to the outlet, and a flow-blocking position at which fluid flow between the inlet and outlet is blocked;
a pilot element movable to selectively communicate the chamber end of the main poppet with a drain in fluid communication with the outlet, thereby affecting movement of the main poppet between the flow-passing and flow-blocking positions; and
a solenoid mechanism operable to move the pilot element,
wherein the position of the pilot element is affected by a fluid pressure at the inlet.
19. The work machine of claim 18 , wherein:
the solenoid is operable to move the pilot element a predetermined amount, thereby moving the main poppet a predetermined amount; and
the predetermined amount is based on an assumed fluid pressure at the inlet.
20. The work machine of claim 18 , wherein the pilot element is movable in response to the fluid pressure at the inlet to maintain a substantially constant flow rate of fluid from the in let to the outlet.
21. The work machine of claim 18 , wherein:
the pilot element includes a central bore extending through the pilot element; and
the solenoid mechanism includes:
an electromagnet coil;
an armature;
a pin element connected to the armature; and
a central bore extending through the armature and pin element and being in communication with the central bore of the pilot element.
22. The work machine of claim 21 , further including:
a central bore extending through the main poppet and being in communication with the central bore of the pilot element; and
a check valve element disposed within the central bore of the main poppet.