Electric Actuator with a Force/Pressure Measurement Sensor

Abstract

An electric actuator for activating a valve device in the oil and natural gas industry, such as a slide valve, butterfly valve, ball valve, blow-out preventer or the like, has at least an actuator housing ( 3 ) that can be mounted to the valve device ( 2 ) and a displacement device ( 5 ) that is held within the actuator housing ( 3 ) and driven by means of an electric motor ( 4 ). In order, in the case of such an actuator, to register the forces or pressures that arise therein with both a static load or also with dynamic load changes reliably and with the exclusion of corresponding disturbance variables, and in order in this way to increase particularly the operational reliability of corresponding valve devices, at least one force/pressure measurement sensor ( 6, 7 ) is arranged between the actuator housing ( 3 ) and the displacement device ( 5 ). This sensor has, on its two interior facing sides ( 8, 9 ), two rings ( 11, 12 ) coated with a piezoresistive sensor layer ( 10 ) that forms one or more measurement surfaces ( 19 ), as well as at least one separating foil ring ( 13 ) arranged between these rings. A measurement voltage is applied between the separating foil ring ( 13 ) and a ring ( 11, 12 ) for determining a force/pressure-dependent resistance level.

1 . An electric actuator ( 1 ) for activating a valve device ( 2 ) in the oil and natural gas industry, comprising:
 an actuator housing ( 3 ) configured to mount to the valve device ( 2 );   a displacement device ( 5 ) held within the actuator housing ( 3 ) and driven by means of an electric motor ( 4 ); and   a force/pressure measurement sensor ( 6 ,  7 ) arranged between the actuator housing ( 3 ) and the displacement device ( 5 ), the sensor comprising:
 two rings ( 11 ,  12 ), each having interior sides ( 8 ,  9 ) that face each other and exterior sides ( 16 ,  17 ) that face away from each other, wherein the rings ( 11 ,  12 ) are coated with a piezoresistive sensor layer ( 10 ) that forms one or more measurement surfaces ( 19 ); and 
 a separating foil ring ( 13 ) arranged between the rings ( 11 ,  12 ), 
 wherein a measurement voltage is applied between the separating foil ring ( 13 ) and one of the rings ( 11 ,  12 ) for determining a force/pressure-dependent resistance level. 
   
     
     
         2 . The electric actuator according to  claim 1  wherein the piezoresistive sensor layer ( 10 ) comprises a diamond-like carbon layer. 
     
     
         3 . The electric actuator according to  claim 1  wherein the rings ( 11 ,  12 ) comprise steel washers. 
     
     
         4 . The electric actuator according to  claim 1  wherein the separating foil ring ( 13 ) comprises a steel foil ring. 
     
     
         5 . The electric actuator according to  claim 1  wherein the separating foil ring ( 13 ) comprises a connecting contact ( 14 ) that extends radially outward. 
     
     
         6 . The electric actuator according to  claim 1  wherein the rings ( 11 ,  12 ) and the separating foil ring ( 13 ) are connected to one another at their edges ( 15 ). 
     
     
         7 . The electric actuator according to  claim 6  wherein the rings ( 11 ,  12 ) and the separating foil ring ( 13 ) are glued to one another at their edges ( 15 ). 
     
     
         8 . The electric actuator according to  claim 1  wherein one of the sides ( 8 ,  9 ,  16 ,  17 )/of one of the rings ( 11 ,  12 ) comprises a structure for electrical contacting and/or sensor areas ( 20 ) separated from one another. 
     
     
         9 . The electric actuator according to  claim 1  wherein the force/pressure measurement sensor ( 6 ,  7 ) comprises a thickness of 4 to 10 millimeters. 
     
     
         10 . The electric actuator according  claim 1  wherein the force/pressure measurement sensor ( 6 ,  7 ) comprises one or more flat measurement surfaces ( 19 ). 
     
     
         11 . The electric actuator according to  claim 1  wherein the force/pressure measurement sensor ( 6 ,  7 ) comprises one or more measurement surfaces ( 19 ) that extend three dimensionally and/or are arranged in space. 
     
     
         12 . The electric actuator according to  claim 1  wherein the force/pressure measurement sensor ( 6 ,  7 ) is coupled to a holding device ( 21 ,  22 ) configured to provide pivoting support for the displacement device ( 5 ) in the actuator housing ( 3 ). 
     
     
         13 . The electric actuator according to  claim 1  wherein the force/pressure measurement sensor ( 6 ,  7 ) is coupled to a support device ( 23 ) configured to hold the displacement device ( 5 ) in the actuator housing ( 3 ). 
     
     
         14 . The electric actuator according to  claim 1  wherein the ring ( 11 ,  12 ) of the force/pressure measurement sensor ( 6 ,  7 ) comprises a further coating on one of the/sides ( 8 ,  9 ,  16 ,  17 ), wherein the coating comprises at least one of chromium, a doped material, or an insulation material. 
     
     
         15 . The electric actuator according to  claim 1  wherein the measurement surface ( 19 ) comprises a loaded measurement surface and an unloaded measurement surface or a loaded measurement surface and a comparison surface separated from the measurement surface , wherein a difference in resistance measurements of the loaded and unloaded measurement surfaces or the loaded measurement surface and the comparison surface can be used for temperature compensation. 
     
     
         16 . A method comprising:
 using a force/pressure measurement sensor ( 6 ,  7 ) in an electric actuator ( 1 ) for activating a valve device ( 2 ) in the oil and natural gas industry the force/pressure measurement sensor ( 6 ,  7 ) comprising two rings ( 11 ,  12 ) each having interior sides ( 8 ,  9 ) that face each other and a separating foil ring ( 13 ) arranged between the rings ( 11 ,  12 ), wherein the rings ( 11 ,  12 ) are coated with a piezoresistive sensor layer ( 10 ) that forms one or more measurement surfaces ( 19 );   applying a measurement voltage between the separating foil ring ( 13 ) and one of the rings ( 11 ,  12 ); and   determining a force/pressure-dependent resistance level based on the applied voltage and a resulting current;   wherein the electric actuator ( 1 ) comprises an actuator housing ( 3 ) configured to mount to the valve device ( 2 ) and a displacement device ( 5 ) held within the actuator housing ( 3 ) and driven by means of an electric motor ( 4 ); and   wherein said sensor ( 6 ,  7 ) is arranged between the actuator housing ( 3 ) and the displacement device ( 5 ) for determining, via the displacement device, the pressure or force acting on the valve device.