Valve device and method for anticipating failure in a solenoid valve assembly in a manifold assembly

A solenoid valve assembly has a valve body in which a spool is slidably mounted and operated by a solenoid having a coil. A manifold member has a plurality of flow paths for supplying and discharging pressurized fluid to and from ports of the solenoid valve assembly. An intermediate block is interposed between the valve body and the manifold member. The intermediate block has a plurality of through holes for connecting ports of the manifold member to ports on the valve body. At least one sensor is housed in the intermediate block for sensing at least one of pressure and flow in at least one of the through holes.

TECHNICAL FIELD

This invention relates to solenoid valve control systems in a manifold assembly.

BACKGROUND OF THE DISCLOSURE

Manifold assemblies are commonly used in an assembly or industrial line to selectively direct pneumatic pressure to various pneumatically operated devices in the line. The manifold assemblies incorporate electrically actuated solenoid valves that control the direction of pneumatic flow for operating these devices. These manifold assemblies are commonly modular and are assembled from a plurality of individual manifold block members, often referred to as manifold blocks, and individual control valve bodies, often referred to as solenoid valves, valve blocks or merely valve members. The manifold assembly often has a common pilot pressure passage and main pressure passage that are connected to the solenoid valves which in turn control the flow of main pressure to a respective pneumatically operated device.

These manifold assemblies have been known to incorporate sandwich blocks interposed between a manifold block and the solenoid actuated valve to provide shut off valves for the main pressure, to introduce a second pneumatic pressure source to a single valve station or to provide and isolate the exhaust of a single valve station from the manifold or to house pressure sensors. It is also known to install pressure sensors in sandwich blocks to monitor input and output pressures.

These manifold assemblies have the capacity to incorporate many manifold blocks, sandwich blocks, valve stations and solenoid valves which in turn operated many devices in a large manufacturing assembly or industrial line. As each of the control valves needs to be correctly operating to maintain correct operation of the respective device, failure of a single control valve and its respective device may cause an entire assembly or industrial line to cease operating. Hence it is highly desirous and advantageous to maintain each valve in operating condition and to replace any valve before its failure during scheduled maintenance and normal down time to prevent unscheduled cessation of the line.

This just-in-time replacement would be possible if failure of solenoid valve can be predicted. Prediction of failure is possible if failure is not sudden without warning. In other words, if anomalous behavior or early degradation of performance can be detected as an early warning indicator, then prediction of an imminent failure becomes possible.

U.S. Pat. No. 6,386,229 discusses a method to anticipate failure by monitoring position of the valve in the manifold block based on certain time values. The position of a spool is detected by the use of a magnet mounted on the spool valve and a Hall effect sensor protruding into the valve body for sensing the proximity of the magnet as the spool valve moves between its two end positions. The movement is timed and if the measured time slows down beyond normal operating values, the valve is then deemed to be in need of replacement. Often these timers, pressure sensors and Hall effect sensors are built into the valve body. This approach however requires the manifold block to be initially designed and constructed with the appropriate sensors and magnets and does not address the need to reduce modifications to the valve and unmet need to monitor the many control valves and manifold members that are already installed in automated industrial and assembly lines.

What is desired is a system to detect any degradation of the control valve by comparing pressure changes in the discharge lines relative to the supply lines compared to current flow that actuates the solenoid of the control valve. Further what is also desired is a sandwich block that mounts sensors that detect pressure, coil current and valve position that can be retrofitted with existing manifold blocks and control valve bodies and wherein the sensors can be used to anticipate failure of a control valve.

SUMMARY OF THE DISCLOSURE

According to one aspect of the invention, solenoid valve assembly includes a valve body in which a spool is slidably mounted and operated by a solenoid having a coil that operable causes the spool to move. A manifold member has a plurality of flow paths for supplying and discharging pressurized fluid to and from ports of the solenoid valve assembly. An intermediate block is interposed between the valve body and the manifold member with the intermediate block having a first mounting face on which the valve body is placed and a second mounting face opposite from the first mounting face for placing the intermediate block on the manifold member. The intermediate block has a plurality of through holes for connecting ports at the manifold member to ports at the valve body. At least one sensor is housed in the intermediate block for sensing at least one of pressure and flow in at least one of the through holes. Preferably, the at least one sensor is in the form of a sensor board and has a plurality of pressure transducers mounted thereon for detecting pressure in a plurality of the through holes. Preferably, the at least one sensor also includes a current sensor housed in the intermediate block for sensing current supplied to the coil. In one embodiment, a position sensor is inside the intermediate block without intruding into the valve body for sensing a position of a magnet affixed to the spool. In one embodiment, there is a leakage sensor that detects ultrasound caused by leaks in one of the flow paths.

According to another aspect of the invention, a solenoid valve assembly has a valve body in which a spool is slideably mounted and operated by a solenoid having a coil that operable causes the spool to move. A manifold member has a plurality of flow paths for supplying and discharging pressurized fluid to and from ports of the solenoid valve assembly. The solenoid valve assembly has at least one sensor for detecting a plurality of parameters of the solenoid valve assembly. One parameter may be pressure in the discharge port and another parameter may be current to the coil for comparing current with pressure during at least one actuation cycle of the solenoid valve assembly to establish a normalized cycle profile. A storage device stores the normalized cycle profile detected by the sensors and also stores a predetermined tolerance boundary determined from the normalized cycle profile. A comparator is connected to the at least one sensor and storage device and compares parameters from the at least one sensor with the normalized cycle profile and the predetermined tolerance boundary. An alarm is operable connected to the comparator and actuates if the comparator compares a parameter from the at least one sensor with normalized profile and the predetermined tolerance boundary and finds the parameter outside of the predetermined tolerance boundary.

Preferably the at least one sensor is housed in an intermediate block disposed between the valve body and the manifold member. The intermediate block has a first mounting face on which the valve body is placed and has a second mounting face opposite from the first mounting face for placing the intermediate block on the manifold member. A plurality of through holes operably connect ports at the manifold member to ports on the valve body. The at least one sensor is housed in the intermediate block for sensing at least one of pressure and flow in at least one of the through holes. In one embodiment, the at least one sensor is in the form of a sensor board mounts a plurality of pressure transducers thereon for detecting pressure in a plurality of the through holes. Preferably, one of the parameters is the position of the spool within the valve body.

According to another aspect of the invention, a detection system for a solenoid valve assembly has at least one sensor for detecting pressure in at least one discharge ports of the solenoid valve assembly and for detecting current supplied to the coil of the solenoid valve assembly for comparing current with pressure in the ports to establish a normalized cycle profile during at least one actuation cycle of the solenoid valve assembly. A storage device operably connects to the at least one sensor to receive the sensed parameter to determine the normalized cycle profile and storing a predetermined tolerance boundary established from the normalized cycle profile. A comparator is operably connected to the storage device and the at least one sensor for comparing parameters from the at least one sensor to the normalized cycle profile and the predetermined tolerance boundary. An alarm device is operably connected to the comparator and is actuated if the comparator compares a parameter from the at least one sensor with the normalized profile and predetermined tolerance boundary and finds the parameter outside of the predetermined tolerance boundary.

According to another aspect of the invention, an intermediate block is constructed to be interposed between a manifold block and a control valve body housing a solenoid operated control valve. The intermediate block has a set of through holes for connecting ports in the manifold block with ports in the control valve body. The intermediate block has a conductive circuit line to provide current to and from a power circuit line in the manifold block and to and from a coil of the solenoid in the control valve. A plurality of sensors are mounted therein for sensing pressure in at least one of the through holes and current in the conductive circuit line preferably, one of the sensors is constructed for sensing a position of the control valve in the control valve body.

According to another aspect of the invention, a method of determining the operating condition of a solenoid operated fluid valve includes actuating the solenoid operating fluid valve for at least one cycle. At least two parameters are measured after actuation of the solenoid operating fluid valve for the at least one cycle to establish a normalized operating profile of the solenoid operating fluid valve. A tolerance boundary is established based on the normalized operating profile. The normalized operating profile and the tolerance boundary are stored in a memory device. At least two parameters are sensed and measured during normal operation of the solenoid operating valve. The measured two parameters are compared in a comparator to the normalized operating profile and the tolerance boundary in the memory device. An alarm is actuated if the measured parameter is outside of the tolerance boundary.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now toFIGS.1and2, a fluid control system10is modular in nature and has a plurality of valve manifold blocks12interconnected together. The particular number of blocks12is dependent on the application and the capacity of a circuit board60installed in each manifold block12. Each manifold block12may have two valve stations14for mounting two control valves18. Each control valve18may have an outer body19. A pair of control valve bodies19may be mounted directly on the upper surface13of the manifold block12. While a manifold block12is illustrated with two valve stations, it is foreseen that a manifold block with a single valve section can also be used.

As shown inFIG.2, each manifold block12has fluid supply and fluid exhaust passages20,22, and24that extend laterally through the block to be in communication with an adjacent block12. Each manifold block also has discharge passages21and23that extend to an outer wall29for connecting to a pneumatically operated device (not shown). Each manifold block also has a transverse pilot pressure passage25. Each passage20,21,22,23,24, and25connects to a respective port40,42,44,46,48and49at the upper surface13of the manifold block.

An intermediate block26often referred to as a sandwich block is interposed between at least one control valve body19and one manifold block12. As shown inFIG.2, the intermediate block26has a plurality of through holes30,32,34,36,38and39that connect the supply, discharge pilot and exhaust ports40,42,44,46,48and49of the manifold block to the supply, discharge pilot and exhaust ports50,52,54,56,58and59of the control valve18.

The circuit board60supplies electric power to the solenoid valve coil64of the control valve for actuating the solenoid valve and moving its spool66. In a well known fashion, the spool may be biased to one direction by a spring68and is movable in the opposite direction by application of fluid pressure to the opposite end of the spool. 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.

The circuit board60besides having electrical power traces may also have a single communication line for serial connection to each control valve18. Such a single line is described in more detail in U.S. Ser. No. 14/765,019 filed on Jul. 31, 2015 and is incorporated herein by reference. The power traces and single communication line is generally attached to pin connector74.

Besides the through holes30-39, the intermediate block also has power line70passing through for connecting pin connector74on circuit board60to the pin connector76in the valve body such that the solenoid coil64is powered by power line70. Appropriate pin connectors75and77are at the top and bottom faces of the intermediate block26for operable connection to the respective pin connectors74and76to provide continuity of power line70from pin connector74to pin connector76.

A communication line72also extends from circuit board60and up through intermediate block26connected to a current sensor board78and a pressure sensor board80mounted in the intermediate block. The communication line can be incorporated in pin connectors74and75. The current sensor board is also connected to the current power line70. The pressure sensor board80has three pressure transducers82,84,86connected to discharge through holes and supply through holes32,34and36for sensing pressure therein.

An optional position sensor magnet88may be connected to the spool and sensed by a position sensor90for example a Hall effect sensor also mounted on current sensor board78.

The parameter data such as pressure, flow, electrical current, and response time is sent via the communication line72to a local or remote microcontroller such as one installed in communication module92which houses memory storage98and a comparator99.

Referring now toFIGS.7and8, a second embodiment of a sandwich or intermediate block126is shown. It generally has two end caps127and129and a mid section131. End cap127has a pin connector133extending out an end135for providing power for one or two Hall effect sensors and for a signal communication pin. Each end cap127and129is made from a non magnetic material such as plastic or aluminum and houses Hall effect sensor190and optional second Hall effect sensor191in proximity to upper walls147and143. Second Hall sensor191is in electrical communication via a cable strap145that extends through mid section131.

The mid section has the through holes130,132,134,136,138and139and similarly houses the other sensors as described for the first embodiment such as the pressure or flow, or additional sensors for sensing other parameters for example vibration or leakage sensors.

A schematic example of a normalized cycle is shown inFIG.6. The normalized cycle for current being turned on and off is shown by dotted and dash curve94for a cycle time To. The pressure is measured in the discharge line for a given pressure in the supply lines. The measured pressure values are shown as a solid curve96which can be stored in memory storage98. A tolerance band or limit can then be established as shown by broken curve97in memory storage98bases on certain degradation from line96for which the valve is not moving quickly enough and the buildup of pressure lags. A comparator99can compare a measured parameter to the normalized profile and the respective tolerance band limit for a particular time Ti. Once the degradation goes below i.e outside the tolerance limit, an alarm may be sent by the communication module92to the operator, for example via a light indicator100in the communication module92or to a light indicator100in the communication module92in a corresponding I/O unit102corresponding to the particular control valve indicating which control valve is below the preset tolerance limit. Other parameters may be substituted such as spool motion or flow rate in place of or in addition to pressure and time. The choice of parameters may be selected depending on the specific application of the control valve.

The electronic schematic of the Hall effect sensor is disclosed inFIG.9. The power connector has a ground volt pin151, power voltage pin connector103, and output signal connector155. The Hall effect sensor190receives voltage from pin103. Voltage also goes through resister R3to transistor157. When the Hall effect sensor190senses a sufficient magnetic field strength from the magnet88on spool, it actuates to pass voltage to line159through resistor R2which turns on transistor157and allows voltage out through line155to indicate the position of the spool.

At the time when a control valve shows some degradation before a complete failure, indication of this degradation can be in the form of an alarm or visual notification which allows the control valve 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.

By having the pressure sensors, current sensors, and other parameter sensors being installed in the intermediate block, one can retrofit a standard existing control valve18with the intermediate block26interposed between the manifold block12and the control valve body with no further modification to the control valve body19or manifold block12. One or a plurality of intermediate blocks26may be added later as an accessory to the valve manifold10at any or all of the control valve stations.

It is also foreseen that the information may be transmitted to the controller by wireless technology.

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