Variable torque impact wrench
View Patent ↗Disclosed herein is a fluid control system for varying the power available to a fluid powered tool, a hydraulically driven impact wrench. The system disclosed herein varies power available to the tool by use of a bypass mechanism that is downstream of a directional control valve spool. Among other things, the advantageous placement of the bypass valve limits the thermal burden in the hydraulic circuit.
1. A power limiting system for a fluid driven tool, the power limiting system disposed upstream of a work unit and within the tool, the power limiting system comprising:
an inlet port for receiving an inlet flow comprising fluid from a supply;
a direction control valve downstream of the inlet port for controlling the flow to the work unit;
a bypass valve which is disposed downstream of the direction control valve; and
a motor reversing valve disposed downstream of the direction control valve and upstream of the bypass valve,
wherein the bypass valve comprises a movable bypass member with a valveless conduit, wherein the valveless conduit is adapted for diverting a portion of the inlet flow from entering the work unit directly to a return flow from the work unit, wherein the bypass valve is movable about an axis generally orthogonal to an axis of movement of the motor reversing valve.
2. A power limiting system as in claim 1 , wherein the motor reversing valve is adapted for redirecting the inlet flow to a reversing circuit to cause reverse operation of the work unit.
3. A power limiting system as in claim 2 , wherein the motor reversing valve is reconfigured by lateral movement thereof.
4. A power limiting system as in claim 1 , wherein the movable bypass member diverts the portion of the inlet flow upon rotation of the bypass valve.
5. A power limiting system as in claim 1 , wherein the work unit comprises a gerotor motor.
6. A power limiting system as in claim 1 , wherein the work unit comprises a gear driven motor.
7. A power limiting system as in claim 1 , wherein the portion of the inlet flow is about fifty percent of the inlet flow.
8. A power limiting system as in claim 1 , wherein the portion of the inlet flow is about zero percent of inlet flow.
9. A power limiting system as in claim 1 , wherein the portion of the inlet flow ranges from about zero percent to about one hundred percent of the inlet flow.
10. A power limiting system as in claim 1 , wherein the direction control valve is adapted for operating in the idle state to interrupt the inlet flow to the work unit.
11. A power limiting system as in claim 1 , wherein the direction control valve is adapted for operating in the idle state to divert the inlet flow from the work unit.
12. A hydraulically driven tool comprising:
a work unit within the tool for completing work;
a fluid control system disposed within the tool upstream of the work unit, the fluid control system comprising an inlet port for receiving a flow comprising hydraulic fluid from a supply, a direction control valve downstream of the inlet port for controlling the flow to the work unit, a bypass valve which is disposed downstream of the direction control valve, and a motor reversing valve disposed downstream of the direction control valve and upstream of the bypass valve, wherein the bypass valve comprises a bypass adapted for diverting a portion of the flow from entering the work unit, wherein the bypass valve is movable about an axis generally orthogonal to an axis of movement of the motor reversing valve; and,
an outlet for returning the hydraulic fluid to the supply.
13. A hydraulically driven tool as in claim 12 , wherein the tool comprises a variable torque impact wrench.
14. A hydraulically driven tool as in claim 12 , wherein the tool comprises a wrench.
15. A hydraulically driven tool as in claim 12 , wherein the tool comprises a grinder.
16. A hydraulically driven tool as in claim 12 , wherein the tool comprises a drill.
17. A hydraulically driven tool comprising:
a work unit comprising a gerotor motor;
a fluid control system operably coupled to the work unit, the fluid control system comprising an inlet port for receiving a flow comprising hydraulic fluid from a supply, a direction control valve downstream of the inlet port for controlling the flow to the work unit, a bypass valve which is disposed downstream of the direction control valve, and a motor reversing valve disposed downstream of the direction control valve, wherein the bypass valve comprises a rotatable valveless bypass member having a bypass hole adapted for diverting a portion of the flow from entering the work unit directly into a return flow from the work unit, wherein the bypass valve is movable about an axis generally orthogonal to an axis of movement of the motor reversing valve; and
an outlet for returning the hydraulic fluid to the supply.