Stall Control System for Raise Drills and Raise Boring Machines

Abstract

A stall control system for a raise boring machine is provided. In one implementation, the stall control system includes one or more hydraulic control valves connected to thrust cylinders of the raise boring machine to vent pressurize oil from a cap end of the thrust cylinders back to an oil tank or to a rod end of the thrust cylinders. In another implementation, the stall control system includes one or more hydraulic control valves connected to thrust cylinders of the raise boring machine to inject pressurized oil into a rod end of the thrust cylinders to increase pressure on the rod end of the thrust cylinders.

1 . A stall control system for a raise boring machine, the stall control system comprising:
 one or more hydraulic control valves connected to thrust cylinders of the raise boring machine to vent pressurized oil from a cap end of the thrust cylinders back to an oil tank or to a rod end of the thrust cylinders.   
     
     
         2 . The system of  claim 1 , further comprising pressure sensors coupled to the thrust cylinders to detect the pressure of the cap end and the rod end of the thrust cylinders. 
     
     
         3 . The system of  claim 2 , further comprising a controller coupled to the pressure sensors to monitor the pressure at the cap end and the rod end of the thrust cylinders. 
     
     
         4 . The system of  claim 3 , wherein the controller is programmed to, upon seeing either a rise in output torque of the raise boring machine, a decrease in output speed of the raise boring machine, or both; operate the system for a fixed time period while monitoring the pressure of the cap end and the rod end of the thrust cylinders. 
     
     
         5 . The system of  claim 1 , wherein the hydraulic control valves are high volume directional control valves. 
     
     
         6 . The system of  claim 1 , wherein the venting is provided by a manifold installed directly at the raise boring machine. 
     
     
         7 . A method of implementing a stall control system for a raise boring machine, the method comprising:
 connecting one or more hydraulic control valves to thrust cylinders of the raise boring machine; and   venting pressurized oil from a cap end of the thrust cylinders back to an oil tank or to a rod end of the thrust cylinders.   
     
     
         8 . The method of  claim 7 , further comprising coupling pressure sensors to the thrust cylinders and detecting the pressure of the cap end and the rod end of the thrust cylinders. 
     
     
         9 . The method of  claim 8 , further comprising coupling a controller to the pressure sensors and monitoring the pressure at the cap end and the rod end of the thrust cylinders. 
     
     
         10 . The method of  claim 9 , wherein the controller is programmed to, upon seeing either a rise in output torque of the raise boring machine, a decrease in output speed of the raise boring machine, or both; operate the system for a fixed time period while monitoring the pressure of the cap end and the rod end of the thrust cylinders. 
     
     
         11 . The method of  claim 7 , further comprising installing a manifold directly at the raise boring machine to perform the venting. 
     
     
         12 . A stall control system for a raise boring machine, the stall control system comprising:
 one or more hydraulic control valves connected to thrust cylinders of the raise boring machine to inject pressurized oil into a rod end of the thrust cylinders to increase pressure on the rod end of the thrust cylinders.   
     
     
         13 . The system of  claim 12 , further comprising a manifold installed at a hydraulic power pack for the raise boring machine. 
     
     
         14 . The system of  claim 13 , wherein the manifold comprises the one or more hydraulic control valves and one or more solenoids and is coupled to an accumulator configured for high pressure operation. 
     
     
         15 . The system of  claim 14 , wherein the oil injected into the rod end of the thrust cylinders is stored in the accumulator. 
     
     
         16 . The system of  claim 15 , wherein the accumulator is charged only when the system is not in use for a stall control operation. 
     
     
         17 . The system of  claim 12 , further comprising pressure sensors coupled to the thrust cylinders to detect the pressure of the cap end and the rod end of the thrust cylinders. 
     
     
         18 . The system of  claim 17 , further comprising a controller coupled to the pressure sensors to monitor the pressure at the cap end and the rod end of the thrust cylinders. 
     
     
         19 . The system of  claim 18 , wherein the controller is programmed to, upon seeing either a rise in output torque of the raise boring machine, a decrease in output speed of the raise boring machine, or both; operate the system for a fixed time period while monitoring the pressure of the cap end and the rod end of the thrust cylinders. 
     
     
         20 . The system of  claim 12 , wherein the one or more hydraulic control valves are pressure relief valves. 
     
     
         21 . A method for implementing a stall control system for a raise boring machine, the method comprising:
 connecting one or more hydraulic control valves to thrust cylinders of the raise boring machine; and   injecting pressurized oil into a rod end of the thrust cylinders to increase pressure on the rod end of the thrust cylinders.   
     
     
         22 . The method of  claim 21 , further comprising installing a manifold at a hydraulic power pack for the raise boring machine. 
     
     
         23 . The method of  claim 22 , wherein the manifold comprises the one or more hydraulic control valves and one or more solenoids and is coupled to an accumulator configured for high pressure operation. 
     
     
         24 . The system of  claim 23 , further comprising storing the oil injected into the rod end of the thrust cylinders in the accumulator. 
     
     
         25 . The method of  claim 24 , wherein the accumulator is charged only when the system is not in use for a stall control operation. 
     
     
         26 . The method of  claim 21 , further comprising coupling pressure sensors to the thrust cylinders and detecting the pressure of the cap end and the rod end of the thrust cylinders. 
     
     
         27 . The method of  claim 26 , further comprising coupling a controller to the pressure sensors and monitoring the pressure at the cap end and the rod end of the thrust cylinders. 
     
     
         28 . The method of  claim 27 , wherein the controller is programmed to, upon seeing either a rise in output torque of the raise boring machine, a decrease in output speed of the raise boring machine, or both; operate the system for a fixed time period while monitoring the pressure of the cap end and the rod end of the thrust cylinders.