Abstract:
A valve is provided according to one embodiment of the invention. The valve comprises a piston ( 104 ), a housing ( 106 ) surrounding the piston ( 104 ), an inlet ( 108 ) capable of allowing fluid into the valve, an exhaust ( 110 ) capable of allowing fluid out of the valve, a light source ( 112 ) capable of emitting light directed at the piston ( 104 ), and a light sensor ( 114 ) capable of measuring an intensity of the light received from the light source ( 112 ), said intensity varying based on the position of the piston ( 104 ) within the housing ( 106 ). A piston assembly is also provided according to an embodiment of the invention, in which a light source  608  and a light sensor  610  may be used to determine the position of the piston. A system is provided for obtaining and analyzing operational status information is provided according to an embodiment of the invention. An action may be automatically taken depending on the analyzed operational status. A method is provided for automatically performing a diagnostic operation on a valve. A safety protocol may be executed based on the outcome of the diagnostic operation.

Description:
This application is a National Stage of International Application No. PCT/US2005/043310, filed Nov. 22, 2005, the disclosure of which is hereby incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     A valve is a mechanical device by which the flow of fluid may be started, stopped, or regulated by a movable part that opens or obstructs passage. A valve may be controlled manually, pneumatically, hydraulically, mechanically, electrically, or using a combination thereof. A valve may be used for a variety of purposes, including flow control, pressure control, and directional control. 
     Up until now, operators of systems having one or more valves had to infer or estimate valve movement by measuring the electrical current in one or more solenoid coils associated with each valve. However, measuring the current in this way does not provide any direct data on whether the valve has actually moved. Likewise, it is impossible to tell from the current in a solenoid coil whether any fluid is actually in the valve. 
     SUMMARY OF THE INVENTION 
     A valve is provided according to one embodiment of the invention. The valve comprises a piston, a housing surrounding the piston, an inlet capable of allowing fluid into the valve, an exhaust capable of allowing fluid out of the valve, a light source capable of emitting light directed at the piston, and a light sensor capable of measuring an intensity of the light received from the light source, said intensity varying based on the position of the piston within the housing. 
     A system for obtaining and analyzing operational status information is provided according to an embodiment of the invention. A sensor module measures operational status information relating to a valve. A valve control module controls the valve. A processor module analyzes the operational status information. Finally, an input/output module displays operational status information and allows user control of the processor module. 
     A method is provided for automatically performing a diagnostic operation on a valve. First, the valve is actuated. Next, operational status information relating to the valve is received. Finally, it is determined whether the valve is operating within acceptable parameters. 
     A piston assembly is provided according to another embodiment of the invention. The piston assembly comprises a piston, a housing surrounding the piston, a passage capable of allowing fluid in and out of the housing, a light source capable of emitting light directed at the piston, and a light sensor capable of measuring an intensity of the light received from the light source, said intensity varying based on the position of the piston within the housing. 
     ASPECTS OF THE INVENTION 
     In one embodiment of the valve, the light sensor outputs a voltage corresponding to a digital bit value. 
     In another embodiment of the valve, the light sensor outputs a voltage corresponding to an analog value. 
     In yet another embodiment of the valve, the light received by light sensor from the light source travels directly from the light source to the light sensor. 
     In yet another embodiment of the valve, the light received by light sensor from the light source travels indirectly, via reflection, from the light source to the light sensor. 
     In yet another embodiment of the valve, the light source may emit light of a plurality of intensities. 
     In yet another embodiment of the valve, a high light intensity may be used to verify that the light source and the light sensor are operational. 
     In yet another embodiment of the valve, the light sensor is substantially adjacent to the light source within the housing. 
     In yet another embodiment of the valve, the light sensor is substantially opposite from the light source within the housing. 
     In yet another embodiment of the valve, the piston is comprised of a spool. 
     In yet another embodiment of the valve, the piston is comprised of a poppet. 
     In one embodiment of the system, the processor module is capable of initiating one or more actions based on the operational status information, said one or more actions selected from the group consisting of reverting to a safe valve state, shutting down the valve, temporarily suspending operation of the valve, increasing the electrical current to the valve, decreasing the electrical current to the valve, rerouting fluid to one or more other valves, activating an alarm, displaying a warning message, displaying an error message, sending operational status data to one or more other nodes over an industrial network, sending a warning message to one or more other nodes over an industrial network, sending an error message to one or more other nodes over an industrial network, and logging an incident in memory. 
     In another embodiment of the system, the sensor module comprises one or more light sources in a valve housing, and one or more light sensors in a valve housing. 
     In yet another embodiment of the system, the sensor module comprises one or more pressure sensors in a valve inlet. 
     In yet another embodiment, the one or more pressure sensors are used to track a valve supply pressure in relation to a minimum pressure threshold. 
     In yet another embodiment, the one or more pressure sensors are used to track a valve supply pressure in relation to a maximum pressure threshold. 
     In yet another embodiment of the system, the one or more pressure sensors are used to detect a soft start. 
     In yet another embodiment of the system, the sensor module comprises one or more temperature sensors in a valve inlet. 
     In yet another embodiment of the system, the processor module tracks usage data for the valve. 
     In yet another embodiment of the system, the processor module uses the usage data to predict the remaining life of the valve. 
     In yet another embodiment of the system, the processor module tracks cycle time for the valve. 
     In yet another embodiment of the system, the processor module uses the cycle time to track deterioration of the valve. 
     In one embodiment of the method, a safety protocol is executed. 
     In another embodiment of the method, the safety protocol is comprised of one or more actions, said one or more actions selected from the group consisting of reverting to a safe valve state, shutting down the valve, temporarily suspending operation of the valve, increasing the electrical current to the valve, decreasing the electrical current to the valve, rerouting fluid to one or more other valves, activating an alarm, displaying a warning message, displaying an error message, sending operational status data to one or more other nodes over an industrial network, sending a warning message to one or more other nodes over an industrial network, sending an error message to one or more other nodes over an industrial network, and logging an incident in memory. 
     In one embodiment of the piston assembly, the light received by light sensor from the light source travels directly from the light source to the light sensor. 
     In another embodiment of the piston assembly, the light received by light sensor from the light source travels indirectly, via reflection, from the light source to the light sensor. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       It should be understood that the drawings are not necessarily to scale. 
         FIG. 1  illustrates a valve according to an embodiment of the claimed invention. 
         FIG. 2  is a block diagram illustrating the modules that comprise one embodiment of the present invention. 
         FIG. 3  illustrates the operational flow of the operations performed in accordance with one embodiment of the present invention. 
         FIG. 4  illustrates a spool valve according to an embodiment of the claimed invention. 
         FIG. 5  illustrates a poppet valve according to an embodiment of the claimed invention. 
         FIG. 6  illustrates a piston assembly according to an embodiment of the claimed invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     By placing a light source and a light sensor in the housing of a valve or piston bore, operational status information can be measured directly.  FIG. 1  illustrates an exemplary instantiation of a valve in both an open position  100  and a closed position  102 . Piston  104  may move up and down within housing  106  to control flow of a fluid (not pictured). When the valve is in open position  100 , fluid is allowed to flow between inlet  108  and exhaust  110 . Conversely, when the valve is in closed position  102 , fluid is blocked from entering the housing through inlet  108 . 
     Light source  112  may be a light emitting diode (LED), light bulb, or other light emitting component. Light source  112  emits light into housing  106 . Light sensor  114  is an electronic component responsive to optical input. Light sensor  114  may be a photodiode, a cadmium sulfide cell, a silicon phototransistor, or other light sensing circuit element. The electrical current through light sensor  114  changes depending on the amount of light shining on the light-sensitive surface of light sensor  114 . Light sensor  114  is located substantially adjacent to light source  112  in housing  106 . Light sensor  114  is thus capable of detecting the light from light source  112 , and light sensor  114  can therefore be used in conjunction with light source  112  to allow detection of the position of piston  104 . When the valve is in open position  100 , the light from light source  112  travels indirectly, via reflection off of piston  104 , to light sensor  114 . In contrast, when the valve is in closed position  102 , little or no light from light source  112  is reflected by piston  104 . Consequently, light sensor  114  receives very little direct or reflected light when the valve is in closed position  102 . By measuring the current at light sensor  114 , the amount of reflected light, and thus, the position of piston  104  may be determined. Piston position data can be useful for examining the operational status of a valve. In addition to verifying basic functioning of the valve, more advanced diagnostic information can be obtained as discussed below, in conjunction with  FIG. 2 . 
     Light source  112  may be capable of a plurality of emitted light intensities. More specifically, a high intensity setting may be used to test the functioning of the sensor itself without disassembling the valve or any of the valve components. The intense emitted light will be reflected throughout the valve and picked up by light sensor  114  even when the valve is closed. If the expected current change is observed at light sensor  114 , then both light source  112  and light sensor  114  can be verified as working. 
     In an embodiment, when the valve is in open position  100 , light from light source  112  that is received by light sensor  114  may be brighter than usual when no fluid is present in the valve. Light source  112  and light sensor  114  may therefore be used to detect problems with the fluid supply. 
     In an embodiment, light sensor  114  has a digital output of “1” (open) when a specific light threshold is reached, and a digital output of “0” (closed) otherwise. In a further embodiment, the light threshold of light sensor  114  may be manually set or programmed. In an alternate embodiment, light sensor  114  outputs an analog approximation of a the light level on a linear or non-linear scale, and said analog approximation is decoded into an “open” or “closed” value by a controller or microprocessor. The output of light sensor  114  may be inverted, and/or logically combined with the output of other light sensors (not pictured) relating to the same piston, or another piston, prior to being measured without departing from the scope of the claimed invention. In an embodiment, a plurality of light sensors may exist in a housing  106  at different positions to provide positional data with greater spatial resolution. 
       FIG. 2  illustrates the modules comprising one embodiment of the claimed invention, in which operational status information may be automatically observed and acted upon by a processor module  208 . A valve  202  is capable of opening and closing one or more passages through a valve housing. A sensor module  204  is connected to the valve, and measures aspects of the operational state of the valve  202  such as valve position, static valve pressure, dynamic valve pressure, pressure fluctuations with time, valve temperature, etc. In an embodiment, sensor module  204  comprises an optical sensor for determining valve position as discussed above in conjunction with  FIG. 1 . In another embodiment, sensor module  204  comprises one or more temperature sensors and/or one or more pressure sensors. In an alternate embodiment, sensor module  204  comprises one or more other types of sensors known in the art. 
     A valve control module  206  controls the valve  202 , and more specifically is capable of controlling one or more moving parts within the valve  202  such as spools, pistons, poppets, balls, discs, gates, needles, or other mechanisms. In an embodiment, valve control module  206  controls how much electrical current travels through a coil associated with valve  202 . A given sensor module  204  may be used to monitor a plurality of sensors of similar, or different, types. Similarly, a given valve control module  206  may control a plurality of valves of similar, or different, types. 
     A processor module  208  contains a microprocessor or microcontroller capable of executing user commands and running diagnostic programs, and contains memory for storing data and/or diagnostic programs. In an embodiment, processor module  208  is a personal computer (PC). Memory may be comprised of SRAM (Static Random Access Memory), DRAM (Dynamic Random Access Memory), ROM (Read Only Memory), flash memory, a hard drive, or other type of memory, or a combination thereof. A diagnostic program may be comprised of software suitable for execution by processor module  208 , firmware suitable for execution by processor module  208 , or a combination thereof. Processor module  208  sends control commands to valve control module  206 , and receives operational status information from sensor module  204 . An input/output (I/O) module  210  displays output from processor module  208 , and allows users to interact with processor module  208 . Users can execute diagnostic programs, control valves, and check the operational status of a valve using I/O module  210 . In an embodiment, I/O module  210  allows users to write diagnostic programs. In another embodiment, users can access historical data relating to past diagnostic measurements for a given valve. 
     Processor module  208  allows for advanced valve diagnostic tests. For example, processor module  208  may issue a command to valve control module  206  to change the position of valve  202 , then monitor input from sensor module  204  to determine the valve stroke time (the length of time between the valve control module  206  beginning the control operation, and the time when the valve  202  completes its positional change according to sensor module  204 ). Since a valve may speed up or slow down as it wears, overall valve wear can be computed and tracked using processor module  208 . In an embodiment, historical data relating to a valve  202 &#39;s stroke time is tracked so that wear on the valve  202  can be estimated. When a valve  202  begins to wear out, a warning message can be displayed to the user via I/O module  210 . Alternatively, when a valve  202  wears out or begins to wear out, fluid flow can be rerouted to other, less worn valves (not pictured) until valve  202  can be serviced or replaced. In another embodiment, wear data is tracked across multiple valves in a system to identify the weak links in that system for replacement, or as a starting point for troubleshooting should the system fail. 
     In an embodiment, processor module  208 , in conjunction with I/O module  210 , warns users of imminent failures. In a further embodiment, processor module  208 , in conjunction with I/O module  210 , indicates what corrective action is required to remedy the failure. Processor module  208  may also provide the user with one or more reasons for the failure, or one or more likely reasons for the failure, with the help of I/O module  210 . 
     In another embodiment, processor module  208  in conjunction with sensor module  204  track supply pressure at the inlet of valve  202 . Processor module  208  compares the supply pressure with a minimum threshold, and signals a problem and/or takes corrective action if the supply pressure is below the minimum threshold. In another embodiment, processor module  208  compares the supply pressure with a maximum threshold, and signals a problem and/or takes corrective action if the supply pressure is above the maximum threshold. 
     In still another embodiment, valve supply pressure is used to detect soft starts. The cycle in a soft start valve begins slowly so as not to send a shockwave through the fluid in a system. Conversely, the presence of a soft start in a non-soft-start valve can indicate a fluid leak or other problem. Processor module  208  compares an observed supply pressure progression to an expected pressure progression in a soft start system, and signals a problem and/or takes corrective action if the observed pressure exceeds the expected pressure at any point. Conversely, if processor module  208  detects an observed pressure that is lower than an expected pressure in a non-soft-start system, processor module  208  may signal a problem and/or take corrective action. 
     Valve stroke time may also be tracked across several valves by processor module  208 . Using this information, sequential valves (valves that operate in sequence to accomplish a multi-stage operation) can be tuned in relation to one another. In an embodiment, processor unit  208  can use timing data to automatically tune sequential valves in relation to one another. 
     Valve stroke times may be tracked over time, and gradual changes in stroke time used to extrapolate valve deterioration and predict eventual valve failure. 
     The number of times a valve cycles over a unit of time may also be tracked so that the usage rates of the valve may be tracked. In an embodiment, this valve usage data may be used to predict the remaining life of the valve based on how many total cycles the valve is rated for, and/or based on the estimated time until failure of the valve. 
       FIG. 3  illustrates the operations performed in one embodiment of the claimed invention, in which operational status data is elicited and stored, and the acceptability of the operational status data is determined. Actuate operation  302  actuates an element within a valve. The element may be a piston, spool, ball, disc, gate, needle, or other device. 
     During actuation, receive operation  304  receives operational status information relating to the piston. The operational status information may be comprised of the position of an element within the valve as determined using a light source and light sensor, the presence of overpressure or underpressure in the valve as determined by a pressure sensor in a valve inlet, the temperature in the valve as determined by a temperature sensor in a valve inlet or a valve exhaust, the presence of vacuum in the valve as determined by a pressure sensor in a valve inlet, the detection of a soft start, the usage rate of the valve (including whether the valve is being used at a rate beyond the specification of the valve), whether the valve is nearing the end of its life, or other information. 
     Determine operation  306  evaluates some or all of the operational status information received by receive operation  304 , and determines whether the operational status information status is within acceptable parameters. Said acceptable parameters may be defined by a user, supplied by a valve manufacturer, automatically calculated by a computer based on past operational status data for the valve, or based on operational status data for one or more different valves. 
     If the operational status of the valve is acceptable, flow branches YES to the end of the operational flow. However, if the operational status of the valve is not acceptable, flow branches NO to execute operation  308 . 
     Execute operation  308  executes a safety protocol in response to the unacceptable operational status of the valve. The safety protocol may warn users of an imminent failure, or of the detection of an actual failure, and indicate what corrective action is required. The safety protocol may also provide the user with one or more reasons for the failure, and/or one or more likely reasons for the failure. The safety protocol may include reverting to a safe valve state, shutting down the valve, temporarily suspending operation of the valve, increasing or decreasing the current to the valve to compensate for wear, rerouting fluid to one or more other valves, activating an alarm, displaying a warning message or error message to a user via an I/O interface, logging the incident in memory, or any combination thereof. 
     In an embodiment, the safety protocol includes sending operational status information, or a warning or error message, over an industrial network (such as a fieldbus network) to a second node. The program or protocol at the second node then determines the appropriate response to the condition. In an embodiment, the program or protocol at the second node also executes the response. In an alternate embodiment, the program or protocol at the second note sends the response to another node for execution. The second node may also log the occurrence. 
     In this way, problems with valves can be automatically resolved or worked around without requiring input from a user. Further, a problem with a system of valves may be identified much more quickly than would otherwise be possible. 
       FIG. 4  illustrates a light source  412  and a light sensor  414  in the housing  406  of a spool valve  402 . Spool  404  may move up and down within housing  406  to control flow of a fluid (not pictured). When the valve is in an open position as pictured, fluid is allowed to flow between inlet  408  and exhaust  410 , around the center of spool  404 . Conversely, when the valve is in a closed position (not pictured), fluid is blocked from entering the housing through inlet  408 . 
     Light source  412  emits light into housing  406 . The current through light sensor  414  changes depending on the amount of light shining on the light-sensitive surface of light sensor  414 . Light sensor  414  is thus capable of detecting the light from light source  412 , and light sensor  414  can therefore be used in conjunction with light source  412  to allow detection of the position of spool  404 . Light source  412  is substantially directly opposite from light sensor  414  in housing  406 . Consequently, when the valve is in an open position, the light from light source  412  travels directly to light sensor  414 . In contrast, when the valve is in a closed position, the light from light source  412  is substantially blocked by spool  404 . Consequently, light sensor  414  receives very little light. By measuring the current at light sensor  414 , the position of spool  404  may be determined. As discussed previously, light source  412  may be capable of a plurality of emitted light intensities. A high intensity setting may be used to test the functioning of the sensor itself without disassembling the valve or any of the valve components. The intense emitted light will be reflected throughout the valve, and picked up by light sensor  414  even if the valve is closed. If the expected current change is observed at light sensor  414 , then both light source  412  and light sensor  414  can be verified as working. 
     In an embodiment, when the valve is in an open position, light from light source  412  that is received by light sensor  414  may be brighter when no fluid is present in the valve. Light source  412  and light sensor  414  may therefore be used to detect problems with the fluid supply. 
     Light sensor  414  may have a digital or analog output. In an embodiment, light sensor  414  has digital output, and a programmable or otherwise adjustable light threshold. The output of light sensor  414  may be inverted, and/or logically combined with the output of other light sensors (not pictured) prior to being measured without departing from the scope of the claimed invention. 
       FIG. 5  illustrates a light source  510  and a light sensor  512  in the housing  504  of a poppet valve in a closed position. Poppet  502  is capable of moving upwards through a bore in housing  504 , thus breaking the seal formed between poppet  502  and housing  504  and allowing fluid to pass from inlet  506  to exhaust  508 . Light source  510  emits light which reflects off of poppet  502 . The reflected light is measured at light sensor  512 , light sensor  512  being substantially adjacent to light source  510  in housing  504 . Based on the amount of measured reflected light, the proximity of poppet  502  to light sensor  512  can be determined. 
       FIG. 6  illustrates a light source  608  and a light sensor  610  in the housing  604  of a piston bore. Fluid enters and exits the piston bore through passage  606 . Light source  608  emits light which reflects off of piston  602 . The reflected light is measured at light sensor  610 , light sensor  610  being substantially adjacent to light source  608  in housing  604 . Based on the amount of measured reflected light, the proximity of piston  602  to light sensor  610  can be determined. 
     The various embodiments described above are provided by way of illustration only and should not be construed to limit the invention. Those skilled in the art will readily recognize various modifications and changes that may be made to the present invention without following the example embodiments and applications illustrated and described herein, and without departing from the true spirit and scope of the present invention, which is set forth in the following claims.