Systems and methods for selective enablement of hydraulic operation
A hydraulic system is provided. The hydraulic system includes a pump, a load sense conduit, a tank conduit, a function workport, and a function control valve. The hydraulic system further includes a function poppet valve arranged between the function workport and the function control valve and having a function poppet vent passage, and a system control valve arranged downstream of the function control valve. The system control valve is biased into a first position where fluid communication between the function poppet vent passage and the tank conduit is prevented and fluid communication between the load sense conduit and the tank conduit is provided. The system control valve is selectively movable to a second position where fluid communication between the function poppet vent passage and the tank conduit is allowed and fluid communication between the load sense conduit and the tank conduit is prevented.
1. A hydraulic system comprising:
a pump;
a load sense conduit;
a tank conduit in fluid communication with a tank;
a hydraulic function including a function workport;
a function control valve configured to selectively provide fluid communication between the function workport and either the pump or the tank conduit;
a function poppet valve arranged between the function workport and the function control valve and including a function poppet vent passage; and
a system control valve arranged downstream of the function control valve, wherein the system control valve is biased into a first position where fluid communication between the function poppet vent passage and the tank conduit is prevented and fluid communication between the load sense conduit and the tank conduit is provided, and wherein the system control valve is selectively movable to a second position where fluid communication between the function poppet vent passage and the tank conduit is allowed and fluid communication between the load sense conduit and the tank conduit is prevented;
wherein when the system control valve is in the first position, operation of the hydraulic function via manipulation of the function control valve is prevented.
2. The hydraulic system of claim 1 , wherein when the system control valve is in the first position, the pump is prevented from building pump pressure and the function poppet valve is configured to block fluid flow from the function workport to a function control valve workport of the function control valve.
3. The hydraulic system of claim 1 , wherein when the system control valve is in the second position, the pump is allowed to build pump pressure and, when the function control valve is displaced in a first direction, the function poppet valve is configured to allow fluid flow from the function workport to a function control valve workport of the function control valve.
4. The hydraulic system of claim 1 , wherein when the system control valve is in the second position, operation of the hydraulic function via manipulation of the function control valve is allowed.
5. The hydraulic system of claim 1 , wherein the function poppet valve includes a poppet biased against a seat by a spring and an orifice providing fluid communication between the function workport and a control chamber of the function poppet valve, and wherein the control chamber is in fluid communication with the function poppet vent passage.
6. The hydraulic system of claim 5 , wherein when the system control valve is in the first position, pressure from the function workport is communicated to the control chamber through the orifice, which forces the poppet into engagement with the seat and prevents fluid communication from the function workport to the tank conduit.
7. The hydraulic system of claim 6 , wherein when the system control valve is in the second position and the function control valve is displaced in a first direction, fluid communication is allowed between the control chamber and the tank, which enables pressure from the function workport to force the poppet off the seat and fluid communication is allowed between the function workport and the tank conduit.
8. The hydraulic system of claim 1 , wherein the system control valve is a 3-way, 2-position control valve.
9. The hydraulic system of claim 1 , wherein the system control valve is selectively movable from the first position to the second position in response to a positive operator presence indication.
10. The hydraulic system of claim 1 , wherein the system control valve is electrically operated.
11. The hydraulic system of claim 1 , wherein the system control valve is an electrically-operated solenoid control valve.
12. The hydraulic system of claim 1 , wherein the system control valve includes a first port in fluid communication with the function poppet vent passage through the function control valve, a second port in fluid communication with the load sense conduit, and a third port in fluid communication with the tank conduit.
13. A hydraulic system comprising:
a pump including an pump outlet;
a tank conduit in fluid communication with a tank;
a hydraulic function including a function workport;
a function control valve configured to selectively provide fluid communication between the function workport and either the pump or the tank conduit;
a function poppet valve arranged between the function workport and the function control valve and including a function poppet vent passage;
a system control valve arranged downstream of the function control valve; and
a pump poppet valve including a pump poppet vent passage, wherein the system control valve is biased into a first position where fluid communication between the function poppet vent passage and the tank conduit is prevented and fluid communication between the pump poppet vent passage and the tank conduit is provided, and wherein the system control valve is selectively movable to a second position where fluid communication between the function poppet vent passage and the tank conduit is allowed and fluid communication between the pump poppet vent passage and the tank conduit is prevented;
wherein when the system control valve is in the first position, operation of the hydraulic function via manipulation of the function control valve is prevented.
14. The hydraulic system of claim 13 , wherein when the system control valve is in the first position, the pump is prevented from building pump pressure and the function poppet valve is configured to block fluid flow from the function workport to a function control valve workport of the function control valve.
15. The hydraulic system of claim 13 , wherein when the system control valve is in the second position, the pump is allowed to build pump pressure and, when the function control valve is displaced in a first direction, the function poppet valve is configured to allow fluid flow from the function workport to a function control valve workport of the function control valve.
16. The hydraulic system of claim 13 , wherein the function poppet valve includes a poppet biased against a seat by a spring and an orifice providing fluid communication between the function workport and a control chamber of the function poppet valve, and wherein the control chamber is in fluid communication with the function poppet vent passage.
17. The hydraulic system of claim 16 , wherein when the system control valve is in the first position, pressure from the function workport is communicated to the control chamber through the orifice, which forces the poppet into engagement with the seat and prevents fluid communication from the function workport to the tank conduit.
18. The hydraulic system of claim 17 , wherein when the system control valve is in the second position and the function control valve is displaced in a first direction, fluid communication is allowed between the control chamber and the tank, which enables pressure from the function workport to force the poppet off the seat and fluid communication is allowed between the function workport and the tank conduit.
19. The hydraulic system of claim 13 , wherein the system control valve is a 3-way, 2-position control valve.
20. The hydraulic system of claim 13 , wherein the system control valve is selectively movable from the first position to the second position in response to a positive operator presence indication.
21. The hydraulic system of claim 13 , wherein the system control valve is electrically operated.
22. The hydraulic system of claim 13 , wherein the system control valve is an electrically-operated solenoid control valve.
23. The hydraulic system of claim 13 , wherein the system control valve includes a first port in fluid communication with the function poppet vent passage through the function control valve, a second port in fluid communication with the pump poppet vent passage, and a third port in fluid communication with the tank conduit.
24. The hydraulic system of claim 13 , wherein the pump poppet valve includes a pump poppet biased against a seat by a spring and an orifice providing fluid communication between the pump outlet and a pump poppet control chamber of the function poppet valve, and wherein the pump poppet control chamber is in fluid communication with the pump poppet vent passage.
25. The hydraulic system of claim 24 , wherein when the system control valve is in the first position, the fluid communication allowed between the pump poppet vent passage and the tank conduit allows fluid communication between the pump poppet control chamber and the tank, which enables pressure from the pump outlet to provide fluid communication between the pump outlet and the tank by forcirg the pump poppet off of the seat and
wherein when the system control valve is in the second position, pressure from the pump outlet is communicated to the pump poppet control chamber through the orifice, which forces the pump poppet into engagement with the seat and prevents fluid communication from the pump outlet to the tank conduit through the pump poppet valve.