CN1288355C - Wireless intrinsically safe valve - Google Patents

Abstract

A valve system (10) that employs a piezo-electric element (38) to activate a fluid flow valve (18) so as to use a minimal amount of electrical energy. The piezo-electric element (38) activates a pilot pressure valve (36), which allows a control fluid to pass to a main control valve (44). The control fluid causes the main control valve (44) to activate a working element (16), which in turn operates the fluid flow valve (18). A switching assembly (70) is employed to activate the piezo-electric element (38). The switching assembly (70) can include various types of switching devices, such as RF switching devices, optical switching devices, infrared switching devices and low voltage electrical switching devices.

Description

Wireless, Intrinsic Safety Valve

technical field

This invention relates generally to intrinsically safety valves and, more particularly, to valves utilizing piezoelectric-electric elements with minimal operating electrical power.

Background technique

Many industries use and/or produce combustible chemicals. These industries must take special care to prevent ignition of this chemical to prevent fire or explosion. A chemical management system requires careful consideration to minimize the possibility of ignition of such chemicals. Chemical management systems are typically designed to minimize arcing and sparking often caused by switching circuits. Current chemical management systems utilize expensive wiring and switching components to achieve this goal.

A specific example of this type of chemical management system is the use of solenoid valves, the purpose of which is to move the valve element to control the flow of combustible chemicals. Current systems use expensive low-spark devices. These devices include non-sparking wiring and non-sparking switches, which are expensive due to the large number of shielded wiring and sealed switches required. Even though these switches typically operate at signal voltage levels rather than higher operating voltage levels, a very small spark in a highly flammable environment can create an extremely hazardous situation.

Accordingly, there is a need to provide an intrinsic safety valve that reduces overall valve cost in a chemical management system.

Contents of the invention

In accordance with the teachings of the present invention, a system is disclosed that utilizes a low voltage element, such as a piezo-electric element, to activate a fluid flow valve so as to use a minimum of electrical energy. In one embodiment, the piezo-electric element activates a pilot pressure valve that allows control flow through a main control valve. Controlling the flow causes the main control valve to activate a working unit which in turn controls the fluid flow valve. A switch assembly is used to activate the piezo-electric element. The switch assembly may include various types of switchgear, such as RF switchgear, optical switchgear, infrared switchgear, and low voltage electrical switchgear, enabling the valve to be remotely controlled.

For a fuller understanding of the invention, its objects and advantages, reference should be made to the following detailed description and accompanying drawings.

Description of drawings

This specification should be read in connection with the drawings which form an integral part of this specification, and like auxiliary numerals are used to designate like components in the various drawings.

1 is a schematic block diagram of an intrinsic safety valve activated by an RF signal according to one embodiment of the present invention;

2 is a schematic block diagram of an intrinsic safety valve activated by an optical signal according to another embodiment of the present invention;

3 is a schematic block diagram of a switching system of a valve assembly using an optical switching device according to another embodiment of the present invention;

4 is a schematic block diagram of a switching system of a valve assembly using an optical switching device according to another embodiment of the present invention;

5 is a schematic block diagram of a switching system of a valve assembly using an optical switching device according to another embodiment of the present invention;

6 is a schematic block diagram of a switching system of a valve assembly using an opto-coupler switching device according to another embodiment of the present invention; and

Fig. 7 is a schematic block diagram of a switching system of a valve assembly using an infrared switching device according to another embodiment of the present invention.

Detailed ways

Figure 1 is a plan view of an intrinsic safety valve system 10 according to the present invention. Safety valve system 10 includes valve activation assembly 12 , transmitter 14 , work unit 16 , and fluid valve 18 . Transmitter 14 transmits a signal 24 from antenna 26 which is received by antenna 30 associated with valve assembly 12 . In this embodiment, the signal 24 is an RF signal, but as discussed in detail below, other signals such as optical, infrared, and low voltage signals may also be used. Signal 24 may be encoded by transmitter 14 so that only a particular valve assembly 12 will operate in response to signal 24 . Accordingly, valve assemblies 12 can be addressed to distinguish a particular valve assembly 12 from other valve assemblies. When the valve assembly 12 receives the signal 24, the working unit 16 is activated, which in turn opens or closes the fluid valve 18 according to its normal state. Valve 18 controls the flow of chemicals between first side 20 and second side 22 . Valve 18 may be any type of actuator that operates at low voltage. In particular valve 18 may be any actuation device that would benefit from the system described herein.

Receiver 28 includes a detector 30 that detects signal 24 from antenna 30 . A battery 32 provides electrical power to the receiver 28 . Receiver 28 includes a non-contact switch 34 responsive to signal 24 from antenna 30 . If the transmitter 14 encodes the signal 24, the non-contact switch 34 will only respond if the receiver 28 is the correctly addressed receiver.

The receiver 28 outputs an electrical signal to the pilot valve 36 through the non-contact switch 34 . Pilot valve 36 includes a piezo-electric switch assembly 38 connected to valve body 40 of valve 36 . The switch assembly 38 includes a piezo-electric element whose configuration changes in response to a voltage, as is well understood in the art. The piezoelectric element may be any piezoelectric element suitable for the purposes described herein. In alternative embodiments, the piezo-electric element may be other types of low voltage elements suitable for the purposes described herein, such as elements employing curved element technology, such as ceramic elements. Valve 36 is a two position valve that feeds air to pilot line 42 at pilot pressure. Assembly 38 has a diaphragm (not shown) that deflects upon application of a voltage. The deflection of the diaphragm opens a small port allowing air under pilot pressure to be applied to the pilot line 42 which in turn is applied to the main spool or poppet 44 . The pilot valve 36 is preferably a commercially available pilot valve.

The main valve 44 controls the application of input air and exhausts air to the work cell 16 . In particular, the main valve 44 provides input air to displace the working unit 16 upon application of a pilot pressure from the pilot wire 42 . The working unit 16 can act as a pneumatic, rotary manipulator of the valve 18 . The valve 18 may therefore be a butterfly valve, so that displacement of the working unit 16 can switch the valve 18 . Once the electrical signal output by the receiver 28 is not applied, the pilot valve 36 stops providing pilot pressure to the pilot wire 42 . This displaces the main valve 44 to a deactuated position, which in turn displaces the working unit 16 to its initial position, thereby closing the valve 18 .

FIG. 2 depicts an intrinsic safety valve system 50 according to another embodiment of the invention. The valve system 50 is similar in structure to the valve system 10, and similar auxiliary designations will be used to designate similar units. Since the operation of similar units in FIG. 2 is as described in FIG. 1, it is not described in FIG. 2 again.

Most useful in system 50 is the actuation technique used to operate pilot valve 36 . In particular, optical actuation system 52 replaces transmitter 14 and receiver 28 in system 10 . System 52 includes a fiber optic switch 54 that outputs an optical signal to fiber optic cable 56 . Fiber optic cable 56 applies the optical signal to fiber optic detector 58 . Fiber optic detector 58 converts the optical signal from switch 54 to a voltage for operating assembly 38 of pilot valve 36 . Fiber optic detector 58 outputs the electrical signal to wire 60 .

The above-described embodiment has several advantages. In conventional systems where the operating switch is located far from the actual valve, electrical leads must be provided between the switch and the valve. Since the intrinsically safe system requires the use of explosion-proof wiring, it is time-consuming and expensive to route these electrical conductors. However, in the present invention, since the transmitter 14 and the receiver 28 only need to be connected electromagnetically instead of being directly connected by electrical wires, there is no need to route electrical wires. The invention thus enables considerable cost savings.

Furthermore, the use of piezo-electric element and pilot valve 36 avoids arcing due to connection and disconnection of electrical switches. Only a very small amount of electrical power is required to actuate the pilot valve 36, thereby providing an intrinsic safety valve system. Additionally, since the receiver 28 and assembly 38 require very little power, the battery 32 provides a relatively long battery life for operating the valve system 10 for extended periods of time. For FIG. 2 , the battery 32 may not be used since the light signal provides sufficient voltage for the steering assembly 38 .

3 is a schematic block diagram of a valve switching system 70 that replaces some of the switching devices in valve systems 10 and 50, as will be apparent from the discussion herein. In particular, valve switch system 70 can replace transmitter 14 and receiver 28 in system 10 , as well as replace optical switch 54 and fiber optic detector 58 in system 50 . Pilot valve 36, main valve 44, working unit 16, and fluid valve 18 will function in the manner discussed above. System 70 includes a control board 72 that controls the piezo-electric elements within assembly 38 .

Valve 18 is opened or closed by an optical signal from light source 74 according to its normal position. Light source 74 may be any selectively activated light source suitable for the purposes described herein. Optical signals generated by light source 74 propagate in optical fibers 76 of fiber optic bundle 78 . Light emitted from one end of the optical fiber 76 opposite the light source 74 is received by a plurality of solar cells 80 arranged in a battery pack 82 . The solar cell 80 converts light energy into an electrical signal, which is supplied to the line 84 . The electrical signal on line 84 is amplified by DC-DC converter circuit 86 to a signal level suitable for the particular application. In this embodiment, DC-DC converter circuit 86 amplifies the signal level to 7.5 volts. The converter circuit 86 is not limited by this example, and any amplifier circuit suitable for the purposes described herein may be used. The amplified electrical signal on line 84 is then sent to control board 72 which activates the piezo-electric element to switch pilot valve 36 in the manner described above. Solar cells 80 , inverter circuitry 86 , and control board 72 may all be housed within module 38 .

FIG. 4 is a schematic block diagram of a valve switch assembly 92 that is a variation of the switch assembly 70 described above. Switch assembly 92 drives control board 94 to control the piezo-electric elements within assembly 38 . In this embodiment, a voltage of 1.2 volts is used to control the piezo-electric element. System 92 has a particular application where a single light source drives many low voltage valve assemblies, and an independent low power optical signal is used to independently control each individual valve.

In this embodiment, light source 96 provides optical signals to a plurality of optical fibers 98 and 100, wherein optical fiber 98 drives control board 94 and fiber optic cable 100 drives another valve switch assembly (not shown). Light source 76 may be any light source capable of providing an optical signal to a plurality of such switching assemblies as discussed herein. The light source 76 controls two separate valve switch assemblies in this embodiment, but those skilled in the art will appreciate that more fiber optic connected light sources 96 can be provided to control more valve switch assemblies. The light source 96 is maintained so that optical power is continuously supplied to any valve power module that requires optical power at any time.

The optical signal on the fiber optic cable 98 emitted from the end of the fiber optic cable 98 opposite the light source 90 is received by the plurality of solar cells 104 arranged in the solar cell array 106 . The solar cell 104 converts light energy into electrical energy, which is supplied to the circuit 108 . A photodiode 110 is located on the wire 108 and turns on when it receives an optical signal. When valve 18 is to be activated, fiber optic transmitter 112 , such as an LED, is activated to provide an optical signal to fiber optic cable 114 . Photodiode 110 receives light emitted from the end of cable 114 opposite transmitter 112 and conducts so that an electrical signal generated by solar cell 104 can activate control board 94 . Control board 94 in turn activates piezo-electric elements in assembly 38 to control pilot valve 36 as described above. Solar cell 104 , photodiode 110 and control board 94 may be placed within assembly 38 .

FIG. 5 shows a schematic block diagram of a further valve switching system 120 for activating the valve 18 in the manner discussed here. System 120 includes a control board 122 that operates by activating the piezo-electric elements in assembly 38 with a 1.2 volt signal. The switching system 120 includes a light emitting circuit 124, which in turn includes a manual switch 126, a DC power source 128 (eg, a 9 volt DC source), and a fiber optic transmitter 130 (eg, an LED). When switch 126 is closed, the voltage provided by power supply 128 causes emitter 130 to emit light along fiber optic cable 132 .

System 120 also includes a switch assembly 136 including DC power source 138 (eg, a 1.5 volt DC power source), and photodiode 140 . When the photodiode 140 receives light emitted from the end of the fiber optic cable 132 opposite the transmitter 130 , it turns on so that the DC voltage from the power supply 138 energizes the control board 122 . As mentioned above, the control board 122 activates the piezo-electric element in the assembly 38 which in turn controls the pilot valve 36 . Switch assembly 136 and control board 122 may be located within assembly 38 .

According to another low voltage application, FIG. 6 shows a schematic block diagram of a valve switching system 144 having a control board 146 identical to control board 122 and a switch assembly 148 similar to switch assembly 136 . The switch assembly 148 includes a DC power source 150 and an opto-coupler 152 that replaces the photodiode 140 . Opto-coupler 152 receives a low voltage signal from an appropriate power source 154 which causes opto-coupler 152 to conduct and energizes control board 146 .

7 is a schematic block diagram of valve switching system 158 including a control board 160 identical to control boards 122 and 146 described above, and a switch assembly 162 similar to switch assemblies 136 and 148 . The switch assembly 162 includes a DC power source 164 , a capacitor 166 and an infrared source 168 . A low voltage signal is applied to the infrared source 168 , causing the capacitor 166 to conduct to energize the control board 160 .

While the invention has been described in its presently preferred form, it should be understood that a wide variety of applications and devices exist for the invention. Various modifications and changes can therefore be made to the present invention without departing from the spirit of the invention as set forth in the appended claims.

Claims (22)

CLAIMS 1. A system for controlling an actuator for controlling an unsteady chemical flow, the system comprising: a light source for generating a light source signal received by at least one solar cell, said solar cell generating an electric valve control signal in response to the light signal; a pilot valve including a low voltage element responsive to the electrovalve control signal, an amplifier circuit that amplifies the electrovalve control signal before the electrovalve control signal is applied to the low voltage element; the pilot valve controls pilot air pressure in response to the electrovalve control signal; and a main valve, responsive to the pilot air pressure, said main valve applying a working air pressure to displace a pneumatic rotary manipulator associated with the actuator to control unsteady chemical flow. 2. The system of claim 1, wherein the amplifier circuit amplifies the electrovalve control signal to 7.5 volts. 3. The system of claim 1, wherein the low voltage element is a piezoelectric element. 4. The system of claim 1, wherein the low voltage element is a ceramic element. 5. The system of claim 1, wherein the actuator is a chemical fluid flow valve. 6. The system of claim 1, wherein the solar cell is of the optical device type and is part of a switch assembly that includes a DC power supply that provides an electrical valve control signal to the optical device, the optical device The device transmits the electrovalve control signal in response to a switch signal. 7. The system of claim 6, wherein the optical device is a photodiode and the switching signal is an optical signal. 8. The system of claim 6, wherein the optical device is an optocoupler and the switching signal is a low voltage signal. 9. The system of claim 6, wherein the optical device is an infrared device and the switching signal is a low voltage signal. 10. The system of claim 6, wherein the switching assembly further includes an optical transmitter device, said optical transmitter device generating the switching signal. 11. The system according to claim 10, wherein the optical transmitter device comprises an optical transmitter, a DC voltage supply, and a manual switch activated to cause the DC voltage supply to energize the optical transmitter and generate said switch Signal. 12. A valve system for controlling the flow of unstable chemicals in a chemical management system, the system comprising: a remote transmitter that generates a valve activation signal; a receiver that generates a piezoelectric element signal in response to the activation signal; an assembly including a piezoelectric element, said assembly generating a pilot signal in response to a signal from the piezoelectric element; a pilot valve responsive to the pilot signal via a pilot air pressure; a main valve that generates a working air pressure in response to the pilot air pressure; a pneumatic rotary manipulator responsive to operating air pressure; and A fluid flow valve for controlling flow of the unstable chemical from the first side to the second side is displaced by a pneumatic rotary manipulator. 13. The system of claim 12, wherein the receiver is part of a switching circuit, said switching circuit further comprising a photodiode, said remote transmitter being an optical transmitter, said photodiode located between at least one solar cell and piezoelectric On wires between the elements, the photodiode responds to an optical signal that is a valve activation signal from an optical transmitter, and the photodiode turns on in response to the optical signal to allow the piezoelectric element signal to actuate the piezoelectric element. 14. The system of claim 12, wherein the transmitter is an RF transmitter, the valve activation signal is an RF signal, and the receiver is an RF receiver. 15. The system of claim 12, wherein the remote transmitter comprises an optical transmitter, a DC voltage power supply, and a manual switch, the manual switch being activated such that the DC voltage power supply energizes the optical transmitter and generates the valve activation signal. 16. The system of claim 12, wherein the transmitter is an optical transmitter, the activation signal is an optical signal, and the receiver is an optical detector. 17. The system of claim 16, wherein the optical detector is selected from the group consisting of photodiodes and solar cells. 18. The system of claim 16, wherein the transmitter is selected from the group consisting of an infrared device, an LED device, and a light source. 19. The system according to claim 12, wherein the transmitter is an optical transmitter circuit comprising an optical device and a DC power supply for providing said valve activation signal, said optical device The signal is activated through the valve in response to a transmitter signal. 20. The system of claim 19, wherein the optical device is a photodiode and the transmitter signal is an optical signal. 21. The system of claim 19, wherein the optical device is an optocoupler and the switching signal is a low voltage signal. 22. The system of claim 19, wherein the optical device is an infrared device and the switching signal is a low voltage signal.

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