WO2008072258A2

WO2008072258A2 - Electronic seal monitoring system (esms)

Info

Publication number: WO2008072258A2
Application number: PCT/IN2007/000572
Authority: WO
Inventors: Saurabh Arvindbhai Shah; Virendra Rajeshbhai Shah
Original assignee: Katlax Enterprises Pvt. Ltd.
Priority date: 2006-12-15
Filing date: 2007-12-06
Publication date: 2008-06-19
Also published as: WO2008072258A3

Abstract

The present invention makes the product compact and cost effective. The product has many configurations starting form single channel to N channel. The present invention is specially developed for use with vehicle monitoring system of tankers delivering hazardous material like fuel, chemical etc. This system is specially designed for electronically monitoring the sealing system. The open/close position is sensed by non-contact proximity sensor(s) which is placed near to the seal to be monitored. This signal then goes to the main board where it produce its signal state change by zener barrier and NAMUR amplifier circuit. Depending upon the requirements, the system can be made for single channel and can go up to N channels, where N is no of channels specified by user.

Description

ELECTRONIC SEAL MONITORING SYSTEM (ESMS)

The present invention relates to ELECTRONIC SEAL MONITORING

SYSTEM(ESMS). Seal is one of the most frequently used element in the mechanical technology. It prevents the exchange/theft of material and provides security. An electronic monitoring system is disclosed for detecting the open and closed conditions of containers or cabinets or storage tank (stationary/moving) containing liquid gas or any other expensive/important material. The invention monitoring is for the security of moving tanker material more particularly and relates to the monitoring of fuel, chemical and milk etc.

In fields like oil, pharmaceutical, chemical, marine industries etc. containers (e.g., stainless steel storage tanks; chemical vats or vessels; and fuel or water tanks/moving tankers), must be filled with metered quantities of liquid products. The metered quantity of liquid product contained by container is necessary to guard against theft/mixing and observed continuously preferably from remote place and without much manual interference because of hazardous area applications. Also, such system should be cost effective so that it can be used commonly without much cost burden on the user.

Previously no such cost effective and integrated system with single board electronic circuit like Zener Barrier, NAMUR Amplifier and Regulated power supply was available for continuously monitor the system by means of which theft/mixing of such expensive material can be controlled from remote place. In many fields (e.g., pharmaceutical, chemical and marine industries) containers (e.g., bottles or stainless steel storage tanks; chemical vats or vessels; and marine fuel or water tanks) are filled with metered quantities of liquid products. Often, the metered quantity of liquid product that fills the container is provided from a sending unit, such as a pump and/or an external tank that contains a desired liquid product (e.g., liquid pharmaceuticals, chemicals and fuels). The container is filled through a delivering means such as a nozzle, fitting or valve. In the pharmaceutical and chemical industries, storage tanks made of stainless steel or other materials are used for various procedures in the manufacturing of drugs and chemicals, respectively. The stainless steel tanks are carefully sealed to prevent any contamination of the desired drugs and chemicals being processed. Sensors and liquid level sensing products that can measure the liquid level in these tanks are critical to both pharmaceutical and chemical manufacturing processes. However, the requirements of the manufacturing process preclude using many background art liquid level monitoring products.

Previously a means of determining the amount of fuel residing in a underground storage tank beneath a petrol station forecourt and the amount delivered to the tank from a road tanker has been by the use of a dipstick. This method has disadvantage associated with it. For example, the dipstick requires an operator to perform the dipping procedure and the method is susceptible to appreciable error.

To overcome such limitations the present invention for ELECTRONIC SEAL MONITORING SYSTEM (ESMS) is invented.

Using this system along with other GPS system, user can continuously monitor stationary/moving targets so that in-between theft/mixing of material can be protected.

The present invention is described with greater specific and clarity with reference to following drawings:

Fig.l represents the block diagram of Proximity sensor(Inductive, Capacitive and

Photo) Fig.2 represents the block diagram of ELECTRONIC SEAL MONITORING

SYSTEM (ESMS)

Fig.3 represents the Circuit diagram of Electronic Seal Monitoring System main board. According to the invention there is provided a system for monitoring the sealing of a storage/process tank/tanker and cargos transporting fuel, chemicals, milk or any other type of gas, liquid or solid material... The system comprises zener barriers, NAMUR sensors and NAMUR Amplifier units on a single PCB(plastic Coated Board) , which makes the product compact and cost effective. The invention has many configurations starting from single channel to N channel i.e. it can be used to monitor/track single target or multiple targets. The present invention is also used for vehicle monitoring system. NAMUR sensors are used to detect presence and absence of the object to be sensed. It is made of electronic circuit and it can be any of type e.g. inductive, capacitive or photo electronic circuit with required sensing range.

Inductive NAMUR Proximity sensors are non contact type electronic sensors comprising of oscillator and output circuit. In these operations the oscillator creates high frequency electromagnetic field which radiates from sensing face of the sensor, when damped with metallic object, eddy currents are induced in metal causing change in amplitude of oscillations. This signal then goes to output amplifier.

Capacitive NAMUR Proximity sensors are non contact sensing solution to metallic as well as non-metallic objects. With adjustable sensitivity almost any medium can be detected with desired reliability. The primary functional elements of capacitive proximity switch are high frequency oscillator with floating electrode in the transistor base circuit. In non-activated state, noise filed exists in region of base electrode which represents active, area of proximity switch, when medium appears in active area of proximity switch. When medium frequency oscillations, resulting DC single triggers output stage rectifies and switches high frequency oscillations, resulting DC signal triggers output stage4. Switching stage includes signal feedback system, level of which can be adjusted by potentiometer, thus providing presentable response sensitivity of switch.

The easiest way to describe the photoelectric operating principal is: the emitter, also referred to as the sender, transmits a beam of light either visible or infrared, which in some fashion is directed to and detected by the receiver. Although many housings and designs are available they all seem to default to the basic operating principal. Just as the basic operating principal is the same for all photoelectric families, so is identifying their output. "Dark-On" and ^αLight-On" refers to output of the sensor in relation to when the light source is hitting the receiver. If an output is present while no light is received, this would be called a "Dark On" output. In reverse, if the output is ON while the receiver is detecting the light from the emitter, the sensor would have a "Light-On" output.

Either way, a Light On or Dark On output needs to be selected prior to purchasing the sensor unless it is user adjustable. In this case it can be decided upon during installation by either flipping a switch or wiring the sensor accordingly to the sensors are used.

Through Beam Sensor technology separates the emitter and receiver into separate housings. The emitter provides a constant beam of light to the receiver and detection occurs when an object passing between the two breaks the beam. Even though it is usually the most reliable, it often is the least popular due to installation difficulties and cost. This is because two separate pieces (the emitter and receiver) must be purchased, wired and installed. Difficulties often arise in the installation and alignment of two pieces in two opposing locations, which may be quite a distance apart. Through beam photoelectric sensors typically offer the longest sensing distance of photoelectric sensors.

The other types of photoelectric sensors are reflex types. Reflex types photoelectric sensors are available in two sub types of photoelectric sensors.

1. Diffused Beam REFLEX Sensor: Diffuse photoelectric sensors actually use the target as the "reflector", such that detection occurs upon reflection of the light off the object back onto the receiver as opposed to an interruption of the beam. The emitter i sends out a beam of light. Most often it is a pulsed infrared, visible red or laser beam, which is reflected by the target when it enters the detectable area. The beam is diffused off of the target in all directions. Part of the beam will actually return back to the receiver inside of the same housing in which the sensor originally emitted it from. Detection occurs and the output will either turn on or off (depending upon if it is Light On or Dark On) when sufficient light is reflected to the receiver.

2. Retro Reflective Reflex Sensor: Retro-reflective sensors operate similarly to through-beams without being able to reach the same sensing distances. Certain units may still be used in applications needing ranges of up to 10 m. Similarity between retro-reflective and though beam photoelectric is that there is a constant beam that needs to be broken in order for an output to occur. But, instead of having a separate housing for the emitter and receiver, they are both located in the same housing, facing the same general direction. The emitter produces a laser, infrared or visible light and projects the beam towards a specially designed reflector, which returns the beam, back to the receiver. Detection occurs when the light path is broken or otherwise interfered with. If the output occurs when the beam is broken, the sensor would be considered a dark-on photo.

The invention system is mainly designed (but not limited to) for electronically monitoring the sealing system e.g. oil tanker's lead are open or close and valve box open/close. -The open/close position is sensed by non-contact proximity sensor(s) which is placed near to the seal to be monitored. This signal then goes to the main board where it is processed for its signal state change by Zener Barrier and NAMUR

Amplifier circuit. Then high/ low logic output is produced which is available to external interface circuit for further processing. Depending upon the requirement, system can be customized for single channel and can go up to N channels, where N is no. of channels specified by user.

ELECTRONIC SEAL MONITORING SYSTEM (ESMS) contains proximity sensors and Main Board. Proximity sensors are used to detect presence and absence of the object to be monitored. It is made of electronic circuit and it can be any of type e.g. inductive, Capacitive, photo electric or any other type of electronic pick up/detector depending upon types of material and required sensing range. It takes power form zener barrier and gives signal for presence or absence of the sensed object. The main board of the system contains regulated power supply, zener barrier, NAMUR amplifier unit and relay circuit. The board receives power from vehicle's battery and provides required power supply to NAMUR sensors. The outputs are TTL (sink/source) compatible and/or relay contact type depends upon user's requirements.

The regulated power supply circuit is used to provide the regulated DC power supply to the main board. It Accepts 15 to 30 VDC supply as input and generates +12 VDC supply as output. Filter and coupling capacitors are used to remove the ripple received from external supply as well as internal regulator switching ripple. Voltage regulator is used to provide regulated power supply required for other circuit on board. Zener barrier is very critical part of the main board. It receives supply from safe area and routes low current/low voltage supply to NAMUR sensors, which are placed in the hazardous area. It contains zener diodes, resistors and current limiting fuse. Since these are fail safe device, it is potted using epoxy material. NAMUR Amplifier unit receives signal form NAMUR sensor(s) routed through Zener barrier for target movement. This unit compares the signal for high/low and provides TTL compatible output(s). This output(s) can be used by external circuit for making further decision. Relay output circuit is provided as optional circuit and it takes TTL output form NAMUR amplifier unit and this signal makes relay on/off as per NAMUR sensor switching. NAMUR proximity sensor contains oscillator which is formed by inductor and capacitor combination. Remaining sections like Schmitt trigger, output buffer and output stage are contained by NAMUR Amplifier section.

When first time power is applied to the oscillation circuit, the ransom noise is generated into the transistor and gets amplified; noise is fed back positively into the oscillator. This will cause charging of capacitor at the same time the current will flow in clockwise direction and it will build field across inductor. Constant feeding of energy to the capacitor is resulting in overcharged capacitor and at the same time field build across inductor collapses and it will cause reverse the direction of current and discharging of capacitor. Now the inductor starts build field in reverse direction. It will cause to and fro motion of current in oscillatory circuit and result in oscillation. Oscillator is used in Namur Proximity sensor is Hartley oscillator.

Example 1

Oscillator Design:

Oscillation frequency of oscillator is given by l/2π sqrt(LC). Energy of the oscillator is given by Vi L(I)2

To achieve the oscillation in MHz

L = 10 μH

Litz Wire (Guage 27/45) is used to wind Coil.

Resistance of the coil is 1.3 Ω Total turns = 15.

Cl= 1 NF

Oscillator tolerance of the component is selected 1%, in the NPO dielectric material,

Temperature coefficient is 0 + 60 ppm/°C. Rx is used to achieve the sensing distance of the coil. Means by varying the values of

Rx is the sensing distance is getting changed.

Rl= 15K

Higher value of Rl minimizes the Hysteresis.

C2= 10 NF Capacitor C2 is used to filter out sinusoidal part and it convert signal into the pure DC form.

Transistor Tl & T2 are used to form oscillator. Here Transistor T2 is added due to the oscillator will work as a class "C" operation. In class C type operation the efficiency achieved is 90%. NAMUR Amplifier Unit Design:

Namur amplifier Relay Unit contains Schmitt trigger sections. In which Op-amp IC LM324 is used as a Schmitt trigger. The supply to the Namur sensor is given from the Namur Amplifier section. Voltage Divider network of R4 & R5 will provide 8.2 V. Supply voltage of the unit is 12 VDC which is derived from Regulated power supply located on the main board.

Voltage across the resistor R5 = V * R5 / (R4+R5)

Values are R5 = 3K9 & R4 = 1K5

This will result in 8.6 V across Resistor R5.

This will connect to the inverting section (pin no.2) of the Op-Amp. When there is no target across the Namur sensor at that time voltage developed across sensor is approx. 3.2 V.

Compare voltage at the Non Inverting section (pin no. 3) is 6.0 V. Values are Rl= 6K8 & R2= 6K8

So, the Output of Op-Amp Pin no. 1 remains high. When the target comes across the sensor at that time voltage developed across the sensor is approx. 7.2 V, this will result in change of state of the Op-Amp (Pin no.l) to Low state. Resistor R3 is used as a feedback resistor. It will control the gain and Hysteresis of the Op- Amp. Resistor R6 is used to control base drive of the transistor, to achieve the collector current (Ic) max. 100 mA. The values are chosen below.

The gain of the Transistor =100 (factory specified) Formula is IC= β IB Where β = gain of the transistor. For IC= 100 mA, IB=100xl0-3/100 = l mA When pin no.1 is high voltage at pin no. 1 is 12 V.

Now V=IR So, Value of R6=10K

Transistor Tl is used as a switching element. Transistor Tl is kept in open collector configuration so it can be compatible with TTL, CMOS Logic in sink mode. When pin no. 1 of Op-Amp is high at that time transistor become ON and so the output is pulled to Vss. When pin no.1 is in Low state at that time the transistor remain OFF. When Transistor is ON, it , can sink up to 20OmA at 35VDC (from Manufacturer's Datasheet).

Now when sensor is not connected to the unit at that time the voltage across the pin no. 2 is 8.6 VDC. The compare voltage at pin no.3 is kept approx. 8 VDC so, output at pin no.1 remains LOW in condition when sensor is not connected to the NRU. When Sensor is connected but target is not across the sensor, at that time voltage across the sensor is 7.5 V. which cause high state at pin no. 1.

Zener Barrier Design:

Zener Barrier is most critical part of the system. It prevents the faulty condition in hazardous area as well as in safe area. Energy of the Zener Barrier must not increase beyond 1.5 Watt. Output Voltage of Zener Barrier is IOVDC at 10 mA. To achieve the output Zener current of 10mA, the value of resistor is chosen IK, lWatt.

When the input supply is less than 10V at that time Zener diode Zl, Z2, Z3 do not conduct and acts like as an open circuit. When input voltage exceeds 10V Zener diode Zl, Z2, Z3 start conducting and give low resistance path to the current to maintain constant 10 V (Characteristic of the Zener Diode). At same time energy will develop across the fuse. Here we are using 32 mA Fuse. When any voltage rise at input side it will increase the current and if the current exceeds specified limit at that time fuse will blow and prevent preceding circuit. Zener Z4 is used to maintain constant 10 V at output. Zener barrier is placed between component which are located in Hazardous area and controller which is located in safe area. Zener barrier controls energy flow from safe area to Hazardous area. When any short circuit occurs in Hazardous area at that time resistor R controls the Energy flow by offering resistance. When any failure occurs at supply side and supply become open and at that time fuse will blow to prevent high energy flow to the Hazardous area.

Numerous characteristics and advantages have been set forth in the foregoing description, together with details of structure and function. The Novel features are pointed out in the appended claims. This disclosure, however is illustrative only and changes may be made in detail within the principle of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. The scope of the invention is not to be deemed to be apparent to those skilled in the art, and accordingly the scope of the invention is not to be deemed to be limited to those specific embodiments illustrated described or suggested but is rather to be determined by reference to the appended claims.

Claims

We Claim:

1. ELECTRONIC SEAL MONITORING SYSTEM (ESMS) contains with proximity sensors and main board wherein

proximity or any other type of electronic sensor takes power form zener banner and gives signal for detecting the presence or absence of the object to be sensed;

main board contains regulated power supply, zener barrier, NAMUR Amplifier and Relay Circuit.

2. ELECTRONIC SEAL MONITORING SYSTEM (ESMS) as claimed in claim 1 wherein proximity sensor is placed near to the seal to be monitored.

3. ELECTRONIC SEAL MONITORING SYSTEM (ESMS) as claimed in claim 1 wherein any types of proximity sensors are used e.g. inductive, capacitive, photo electric or any other electronic pickup/detector depending upon types of material and required sensing range.

4. ELECTRONIC SEAL MONITORING SYSTEM (ESMS) as claimed in claim 1 wherein filter and coupling capacitors are provided into the regulated power supply.

5. ELECTRONIC SEAL MONITORING SYSTEM (ESMS) as claimed in claim 1 wherein zener barrier contains zener diodes, resistors and current limiting fuse.

6. ELECTRONIC SEAL MONITORING SYSTEM (ESMS) as claimed in claim 1 wherein NAMUR Amplifier unit receives supply from NAMUR Sensor(s) routed through Zener Barrier.

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7. ELECTRONIC SEAL MONITORING SYSTEM (ESMS) as claimed in claim 1 wherein relay output takes TTL output form NAMUR Amplifier unit.

8. ELECTRONIC SEAL MONITORING SYSTEM (ESMS) as claimed in claim 1 wherein NAMUR Proximity sensor contains Oscillator Which is formed by combination of R, L& C.

9. ELECTRONIC SEAL MONITORING SYSTEM (ESMS) as claimed in claim 6 wherein NAMUR Amplifier unit contains with schmitt trigger, output buffer and output stage.

10. ELECTRONIC SEAL MONITORING SYSTEM (ESMS) as claimed in claim 1 and claim 5 wherein zener barrier is placed between component placed in hazardous area and controller which is located in safe area.

11. ELECTRONIC SEAL MONITORING SYSTEM (ESMS) as substantially as herein described with reference to the foregoing description and the accompanying drawings.