Shutoff valve

Abstract

A safety interlock valve with two flow passages, which in one position allows flow through the flow passages and blocks flow between them, and in another position blocks flow through the flow passages and allows flow between them. The safety interlock valve can be used in hydraulic systems such as power tongs.

1 . A shutoff valve comprising:
 a valve housing having a bore for receiving a valve spool;   a valve spool movable between a first position and a second position within the bore;   a first fluid port in the valve housing connected to the bore by a first flow passage within the valve housing and a second fluid port in the valve housing connected to the bore by a second flow passage within the valve housing, the valve spool being configured to allow fluid flow between the first flow passage and the second flow passage when the valve spool is in the first position, and the valve spool being configured to block fluid flow between the first flow passage and the second flow passage when the valve spool is in the second position;   a third fluid port in the valve housing connected to the bore by a third flow passage within the valve housing and a fourth fluid port in the valve housing connected to the bore by a fourth flow passage within the valve housing, the valve spool being configured to allow fluid flow between the third flow passage and the fourth flow passage when the valve spool is in the first position, and the valve spool being configured to block fluid flow between the third flow passage and the fourth flow passage when the valve spool is in the second position; and   the first fluid port being connected to the bore by a fifth flow passage within the valve housing, and the fourth fluid port being connected to the bore by a sixth flow passage within the valve housing. the valve spool being configured to block fluid flow between the fifth flow passage and the sixth flow passage when the valve spool is in the first position, and the valve spool being configured to allow fluid flow between the fifth flow passage and the sixth flow passage when the valve spool is in the second position.   
     
     
         2 . The shutoff valve of  claim 1  in which the valve spool is substantially axially symmetric, the valve spool having thinner portions that allow fluid flow in the portions of the bore through which the thinner portions pass and having thicker portions that block fluid flow in the portions of the bore through which the thicker portions pass. 
     
     
         3 . The shutoff valve of  claim 1  mounted in a hydraulic system with a hydraulic fluid source having an output line and a return line, and a hydraulic device having a input line and a drain line, in which the first fluid port is connected to the output line of the hydraulic fluid source, the second fluid port is connected to the input line of the hydraulic device, the third fluid port is connected to the drain line of the hydraulic device, and the fourth fluid port is connected to the return line of the hydraulic fluid source. 
     
     
         4 . The shutoff valve of  claim 1  mounted in a hydraulic system with a hydraulic fluid source having an output line and a return line, and a hydraulic device having a input line and a drain line, in which the first fluid port is connected to the input line of the hydraulic device, the second fluid port is connected to the output line of the hydraulic fluid source, the third fluid port is connected to the return line of the hydraulic fluid source, and the fourth fluid port is connected to the drain line of the hydraulic device. 
     
     
         5 . The shutoff valve of  claim 1  mounted in a hydraulic system with a hydraulic fluid source having an output line and a return line, and a hydraulic device having a input line and a drain line, in which the first fluid port is connected to the return line of the hydraulic fluid source, the second fluid port is connected to the drain line of the hydraulic device, the third fluid port is connected to the input line of the hydraulic device, and the fourth fluid port is connected to the output line of the hydraulic fluid source. 
     
     
         6 . The shutoff valve of  claim 1  mounted in a hydraulic system with a hydraulic fluid source having an output line and a return line, and a hydraulic device having a input line and a drain line, in which the first fluid port is connected to the drain line of the hydraulic device, the second fluid port is connected to the return line of the hydraulic fluid source, the third fluid port is connected to output line of the hydraulic fluid source, and the fourth fluid port is connected to the input line of the hydraulic device. 
     
     
         7 . The shutoff valve of  claim 3  in which the shutoff valve is connected to a detector for moving the valve spool to the second position on detecting the presence of a condition. 
     
     
         8 . The shutoff valve of  claim 7  in which the detector moves the valve spool to the first position on detecting that the condition is not present. 
     
     
         9 . The shutoff valve of  claim 3  in which the hydraulic system comprises power tongs. 
     
     
         10 . The shutoff valve of  claim 7  in which the hydraulic device is a motor operating power tongs, the power tongs having a throat and a door to prevent an oilfield tubular from exiting the throat, and the condition is that the door is open. 
     
     
         11 . The shutoff valve of  claim 10  in which the detector is a cable connected to the door. 
     
     
         12 . A shutoff valve comprising:
 a valve housing;   a first fluid port in the valve housing;   a second fluid port in the valve housing;   a third fluid port in the valve housing;   a fourth fluid port in the valve housing; and   the valve being movable between first and second configurations, the first configuration allowing fluid flow between the first fluid port and the second fluid port and between the third fluid port and the fourth fluid port, the first configuration not allowing fluid flow between the first fluid port and the fourth fluid port, and the second configuration blocking flow between the first fluid port and the second fluid port and between the third fluid port and the fourth fluid port, the second fluid configuration allowing fluid flow between the first fluid port and the fourth fluid port.