Device and method for monitoring response time in a valve manifold assembly

Abstract

A field bus solenoid valve assembly has a sensor for detecting the commencement of an actuation cycle for moving a piston in a cylinder and piston assembly. A position sensor detects an end position of a piston in a cylinder and piston assembly at the end of the actuation cycle. A timer times the elapsed time between the initiation of the actuation cycle of the piston and when the position sensor for detecting an end position detects the piston in its end position at the end of the actuation cycle. A comparator operably connected to a storage device and the sensors for comparing elapsed time from the sensors to a normalized time or profile and a predetermined tolerance boundary in the storage device. An alarm device is actuated if the elapsed time is outside of the set tolerance boundary.

Claims

1. A fluid control system comprising: a controller; a fieldbus communication module controlled by the controller and connected to the controller via a fieldbus network; at least one manifold unit connected to the fieldbus communication module, the manifold unit including at least one solenoid control valve for controlling flow of a fluid; at least one fieldbus I/O module connected to the fieldbus communication module; and a field device pneumatically connected to the manifold unit, the field device including a piston and sensors for determining when the piston is in its extended or retracted position, the sensors electrically connected to the fieldbus I/O module; the fieldbus communication module configured to process signals received from the controller and, in response, send signals to the solenoid control valve to control flow of the fluid to the field device; wherein the fieldbus communication module is further configured to process the signals received from the controller and signals received from the field device sensors via the fieldbus I/O module to determine the elapsed time between an initiation and completion of an actuation cycle of the piston and to actuate an alarm if the elapsed time is outside of a predetermined tolerance boundary.

2. The system of claim 1 wherein the fieldbus communication module includes a display for displaying the alarm.

3. The system of claim 1 wherein the controller is a Programmable Logic Computer (PLC) and the fieldbus communication module is configured to send the alarm to the PLC.

4. The system of claim 1 wherein the alarm is an audio alarm.

5. A fluid control system comprising: a controller; a fieldbus communication module controlled by the controller and connected to the controller via a fieldbus network; at least one manifold unit connected to the fieldbus communication module, the manifold unit including at least one solenoid control valve for controlling flow of a fluid; at least one fieldbus I/O module connected to the fieldbus communication module; and a field device pneumatically connected to the manifold unit, the field device including a piston and sensors for determining when the piston is in its extended or retracted position, the sensors electrically connected to the fieldbus I/O module; the fieldbus communication module configured to process signals received from the controller and, in response, send signals to the solenoid control valve to control flow of the fluid to the field device; wherein the fieldbus communication module is further configured to process the signals received from the controller and signals received from the field device sensors via the fieldbus I/O module to determine the elapsed time between an initiation and completion of an actuation cycle of the piston and to actuate an alarm if the elapsed time is outside of a predetermined tolerance boundary; and wherein the fieldbus I/O module includes a display for displaying the alarm.

6. A fluid control system comprising: a controller; a fieldbus communication module controlled by the controller and connected to the controller via a fieldbus network; at least one manifold unit connected to the fieldbus communication module, the manifold unit including at least one solenoid control valve for controlling flow of a fluid; at least one fieldbus I/O module connected to the fieldbus communication module; and a field device pneumatically connected to the manifold unit, the field device including a piston and sensors for determining when the piston is in its extended or retracted position, the sensors electrically connected to the fieldbus I/O module; the fieldbus communication module configured to process signals received from the controller and, in response, send signals to the solenoid control valve to control flow of the fluid to the field device; wherein the fieldbus communication module is further configured to process the signals received from the controller and signals received from the field device sensors via the fieldbus I/O module to determine the elapsed time between an initiation and completion of an actuation cycle of the piston and to actuate an alarm if the elapsed time is outside of a predetermined tolerance boundary; and wherein the sensors are electrically connected to separate I/Os of the fieldbus I/O module.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Reference now is made to the accompanying drawings in which:

(2) FIG. 1 is a perspective and partially schematic overview of one embodiment according to the invention;

(3) FIG. 2 is a cross sectional view of the valve housing and manifold block shown in FIG. 1; and

(4) FIG. 3 is a schematic flow chart illustration typical operation of one embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(5) Referring now to FIG. 1, a fluid control system 10 is modular in nature and has a plurality of valve manifold members also referred to as manifold units 12 interconnected together with a communication module 14 and a series of I/O modules 16. The communication module 14 may be connected to a field bus network 17 controlled by a Programmable Logic Computer (PLC) and communication card 15. The particular number of manifold units 12 is dependent on the application and the capacity of the circuitry installed in each unit 12. Each manifold unit 12 includes a manifold block 19 which may mount one or two control valves 18 on its upper surface 13.

(6) Referring to FIGS. 2 and 3, each manifold block 19 has fluid supply and fluid exhaust passages 20, 22, and 24 that extend laterally through the block to be in communication with an adjacent block 19. Each manifold block also has discharge passages 21 and 23 that extend to an outer wall 29 for connecting to a pneumatically operated field device 30 through two pneumatic conduits 32 and 34 as showing in FIG. 3. Each manifold block also has a transverse pilot pressure passage 25. Each passage 20, 21, 22, 23, 24, and 25 connects to a respective port 40, 42, 44, 46, 48 and 49 at the upper surface 13 of the manifold block 19 which are in communication with respective ports 50, 52, 54, 56, 58, and 59 in valve 18.

(7) A circuit board 60 is mounted in the manifold block 19 in known fashion and supplies electric power to the solenoid valve coil 64 of the control valve for actuating the solenoid valve 18 and moving its spool 66 through the force pneumatic pressure from port 59 that is over the prior pressure. When the spool 66 axially moves, it controls the communication between the ports 50-58, i.e. the opening and closing of ports 50-58. In a well-known fashion, the spool 66 may be biased to one direction by a spring 68. Although the embodiment shown is a single solenoid valve assembly, it will be understood that commercially available dual solenoid valve assemblies may also be used. Briefly is a dual solenoid valve, the return springs 68 is eliminated and a second solenoid is operated to provide fluid pressure to return the spool 66 (to the right as shown in FIG. 2).

(8) The field device 30 is commonly operated by a piston and cylinder assembly 70 which has a piston 72 connected to a piston rod 73 that extends out of one end 76 of cylinder 74. The piston 72 is slidably housed within the cylinder housing 74 between a retracted position (to the right in FIG. 1) and an extended position (to the left in FIG. 1). The pneumatic conduits 32 and 34 are connected to opposite ends 75 and 76 and in communication to opposite internal pressure chambers 77 and 78 to provide flued pressure to either chamber 77 and 78 for cycling the piston 72 back and forth within the cylinder housing 74 to either retract or extend the piston rod 73.

(9) Two position sensors 80 and 81 are mounted on cylinder housing 74. These position sensors 80 and 81 may be Hall effect sensors. The piston 72 may have a magnet 83 mounted thereon which when in proximity to either sensor 80 or 81 triggers the sensor to send an output signal.

(10) The position sensors 80 and 81 are each electrically connected to a separate input 82 and 84 of the respective I/O unit 16 corresponding to the valve 18 that is pneumatically connected to the field device 30. The connection is through two electrically conductive cables 86 and 88. Wireless communication is also foreseen as a possibility

(11) Reference is now made to FIG. 3 to describe the general operation of the disclosed embodiment. Referring to box 100, an operator (user) selects the appropriate valve coil 64 that operates the respective field device 30 and then enters appropriate time and other parameter data for each I/O 16 associated with the valve coil 18 as indicated in box 102. The steps are repeated as set forth in box 104 until all output parameters are determined. After all appropriate outputs are set, the cycle operation is commenced. As used herein, a cycle commences when the main communication module 14 sends a signal (by providing an operating voltage or ending the operating voltage) to either actuate or de-actuate a solenoid coil 64 of the valve 18. The signal in effect commences the cycle to move the piston 72 from its present end position (either retracted or extended) to the other end position (either extended or retracted). When the cycle is commenced, a detection sensor senses the change in voltage in the actuation circuit line and an internal timer Tn in the main communication module 14 is started as illustrated in box 106. The acceptable limits and tolerances have already been set in the first step in box 100 and stored in an internal storage in the main communication module.

(12) If the timer does not shut down due to some defect, the time “Tn” will exceed the time allowed for the associated input Y (either input 82 or 84) as indicated in box 108 and an alarm is sent. The alarm can be visual indication on the graphic display 92 of the I/O unit module 16 or the display 90 of the communication module 74. The alarm can also be sent to an integrated webserver or the PLC 15 or an IPC and DCS etc.) as illustrated in box 110. Audio as well as visual alarms are foreseen.

(13) When the piston 72 moves to the other end, one of the positions sensors 80 and 81 will sense when the piston reaches the end position and a signal is sent via either cable 86 or 88 to input 82 or 84 which turns off the timer and provides the final time Tn as shown in box 112. A comparator then compares Tn and determines if it within tolerances previously set for the valve as illustrated in box 114. If the tolerances are exceeded, an alarm is sent from the I/O unit to the communication module and displayed on either graphic display, 90 or 92 an integrated webserver or the PLC 15 or an IPC and DCS etc.) as illustrated in box 116. It should be noted that the tolerances can also be set for being too short. Overly fast times may occur if someone manually increased the pressure in main line beyond the desired pressure, lowered the load on the field device or other changes that can cause faster than proper times.

(14) If the final time Tn is within parameters, the system continues and the program is reset for the next cycle as illustrated in box 118.

(15) Other parameters may be substituted such as spool motion or flow rate in place of or in addition to the position and time parameters. The choice of parameters may be selected depending on the specific application of the control valve.

(16) When a control valve or its accompanying field device 30 shows some degradation before a complete failure, an audio alarm or visual notification is provided which allows the control valve or field device 30 to be repaired or replaced at the next down time or scheduled maintenance before complete failure occurs which can then avoid unscheduled and unnecessary line stoppage.

(17) An alternate embodiment is foreseen where the signal from the Hall effect sensor also initiates the timer rather the timer being initiated by the beginning of the cycle.

(18) It is also foreseen that the dual solenoid valves can be used with this monitoring and timing system. When dual solenoid valves are used, the respective cycle is commenced when an actuating voltage is sent to a respective first or second solenoid for the valve. The cessation of the actuating voltage is ignored for setting the next cycle. The next cycle is commenced when an actuating voltage is sent to the other of the first or second solenoid.

(19) It is also foreseen that one of the position sensors may be a linear potentiometer that measures analog voltage depending on the linear position of the piston within the cylinder for determining acceleration and deceleration using the position of the piston and elapsed time.

(20) In this fashion, by having the signal that initiates the cycle also turning on the timer and timing the cycle from the moment a signal is initiated until the piston achieves its end position achieves a improved level of prognostics or preventative maintenance. Not only the valve is monitored, but also the pneumatic tubing 32 and 34, and any binding or problems with the cylinder and piston or other binding parts of the field device connected to the piston rod 73 can be detected. The cycle is monitored from its initiation to its end. The parameters that can affect the cycle time include leaks in the valve cylinder fitting and tubing for example; the manual change in the flow control, manual change in a pressure regulator, changes in load, binding in the cylinder and piston assembly caused by wear or rod side loading, valve wear, cylinder wear, weak return spring in the solenoid valve, sensor malfunction, input module malfunction and other changes or malfunctions.

(21) The timing of the cycle commencing with the actuating voltage change sent to the coil and ending with the piston reaching its end can be used to monitor the function and if any changes over time and deviations from the set forth proper time is sensed, an appropriate alarm can be sent to provide warning that something in the line from the coil and valve to the field device is not operating up to design and set standards.

(22) Other variations and modifications are possible without departing from the scope and spirit of the present invention as defined by the appended claims.