Downhole torque limiter and method

Abstract

The downhole torque limiter and method eliminate damage to downhole components by eliminating excessive torque transmission. The device comprises a housing, compression assemblies, and anti-rotation plates. Inner and outer assemblies of the device are permitted to slip with respect to each other after reaching a settable torque limit which is preferably below the maximum capacity of other downhole components. The device may be positioned in drill strings that comprise a downhole motor and/or drill bit as well as drill strings that do not comprise a downhole motor and/or drill bit. In drill strings comprising a downhole motor and/or drill bit, the device may be positioned below the downhole motor and above the drill bit, adjacent to and above the downhole motor, or above the downhole motor such that at least one drill string joint is positioned between the device and the downhole motor.

1 . A downhole torque limiter comprising an outer housing, a friction plate assembly, and an inner mandrel, said friction plate assembly comprising one or more outer friction plates and one or more inner friction plates, said outer housing comprising a bore and being rotatably coupled to at least one of said outer friction plates, said inner mandrel being positioned within said bore and being rotatably coupled with at least one of said inner friction plates, and at least one of the outer friction plates being frictionally engaged with at least one of the inner friction plates. 
     
     
         2 . The downhole torque limiter of  claim 1  further comprising one or more compression assemblies structured and arranged to provide a compression of said friction plate assembly. 
     
     
         3 . The downhole torque limiter of  claim 2 , the compression assemblies comprising an upper spring assembly and a lower spring assembly, said friction plate assembly being positioned between said upper and lower spring assemblies. 
     
     
         4 . The downhole torque limiter of  claim 3  further comprising an upper housing coupled to the outer housing, wherein said upper spring assembly is positioned between the upper housing and the friction plate assembly. 
     
     
         5 . The downhole torque limiter of  claim 3  further comprising a lower end cap coupled to the outer housing, the lower spring assembly being positioned between said lower end cap and the friction plate assembly. 
     
     
         6 . The downhole torque limiter of  claim 5  further comprising a ring assembly, said ring assembly being positioned between said lower spring assembly and said friction plate assembly, and said ring assembly comprising an inner mandrel ring and a static ring, said inner mandrel ring being rotatably coupled to the inner mandrel, said static ring being rotatably coupled to the outer housing. 
     
     
         7 . The downhole torque limiter of  claim 3  wherein the compression is adjustable. 
     
     
         8 . The downhole torque limiter of  claim 7  further comprising one or more jam nuts for adjusting said compression. 
     
     
         9 . The downhole torque limiter of  claim 7  further comprising one or more shims for adjusting said compression. 
     
     
         10 . The downhole torque limiter of  claim 9 , at least one of said shims being positioned between the lower spring assembly and the lower end cap. 
     
     
         11 . The downhole torque limiter of  claim 1 , the friction plate assembly being vertically slideable in relation to said outer housing. 
     
     
         12 . The downhole torque limiter of  claim 1 , the inner plates arranged in an alternating pattern with such outer plates. 
     
     
         13 . A method of preventing damage to downhole drilling equipment comprising the steps of:
 providing a torque limiting device and downhole equipment;   said torque limiting device comprising an outer housing, a friction plate assembly, and an inner mandrel, said friction plate assembly comprising one or more outer friction plates and one or more inner friction plates, said outer housing comprising a bore and being rotatably coupled with at least one of said outer friction plates, said inner mandrel being positioned within said bore and being rotatably coupled to at least one of said inner friction plates, and at least one of the outer friction plates being frictionally engaged with at least one of the inner friction plates;   said downhole equipment comprising a drill string; and   coupling said downhole torque limiting device to said drill string.   
     
     
         14 . The method of preventing damage to downhole drilling equipment of  claim 13 , the downhole equipment further comprising a downhole motor, and a drill bit, wherein the step of coupling said downhole torque limiting device to said drill string further comprises positioning the device, in relation to the earth, below the downhole motor and above the drill bit. 
     
     
         15 . The method of preventing damage to downhole drilling equipment of  claim 14 , wherein said downhole torque limiting device is positioned above the downhole motor. 
     
     
         16 . The method of preventing damage to downhole drilling equipment of  claim 14 , the drill string comprising a plurality of joints, wherein said downhole torque limiting device is positioned above the downhole motor such that at least one of said joints is positioned between the downhole torque limiting device and the downhole motor.