WO2012066482A1

WO2012066482A1 - Method and system for determining the amount of liquid in a vessel for inventory taking

Info

Publication number: WO2012066482A1
Application number: PCT/IB2011/055107
Authority: WO
Inventors: Andrus Aaslaid; Lauri Laubre
Original assignee: LM Developments OÜ
Priority date: 2010-11-15
Filing date: 2011-11-15
Publication date: 2012-05-24

Abstract

Method and system for determining the amount of liquid in a vessel for inventory taking. The amount of liquid is determined from the total volume of the vessel and the volume of the empty space in the vessel. An reference vessel is hermetically connected with the vessel. The volume of the empty space is determined from the difference in air pressure before and after air is forced into the vessel. The system comprises a device for measuring a volume of a vessel, the device comprising a reference vessel with known pressure, a connector for connecting the reference vessel with the vessel and a pressure sensor for measuring pressure in connected vessels. The system comprises a measuring head, comprising a reader for reading the RFID tag on the vessel: The system has a communication module for forwarding the measurement data to the cash register and warehouse management software.

Description

METHOD AND SYSTEM FOR DETERMINING THE AMOUNT OF LIQUID IN A VESSEL FOR

INVENTORY TAKING

TECHNICAL FIELD

The invention belongs to the methods used in bars, restaurants, etc., enabling the amount of liquid in vessels to be determined, e.g. in a bottle, with the purpose of measuring and inventory taking, but also in the field of systems suitable for implementing such methods.

BACKGROUND ART

US patent US3895519 describes a system for determining the volume of a closed non- elastic air chamber, for example the space above the liquid in a vessel, also meant for use in bars and restaurants. According to the system constant pressure exceeding the atmospheric pressure is generated in a relatively small vessel of known size, then the vessel of known size is connected to an air chamber of unknown size, and the pressure within the connected vessels is measured. The system uses a pressure sensor that is first used to load the space of known size with the desired pressure, and then after the pressures in the vessel of known size and the air chamber of unknown size have become equal, to measure the pressure within those connected vessels.

In US patents US5760294 and US5535624 the volume of a bottle is measured by the time consumed to direct gas into the bottle using a predetermined velocity (i.e. the gas mass per a unit of time is known). Compared to the application US3895519 referred to above the advantage of the method is the fact that filling a chamber of known volume up to the required pressure is not necessary, also spending time on equalising the pressures within the chambers of known and unknown volume due to transfer processes is avoided. The method is meant to be used in the plastic bottle production process where plastic bottle blanks are worked to suitable size by blowing air into the blanks.

The object of the invention is a method for measuring the amount of liquid in vessels of relatively small volume (typically around 1 litre), whereas the liquid would not be in direct contact with the measurement instrument, and a system suitable for using such methods.

DISCLOSURE OF THE INVENTION

The object of the invention is achieved by measuring the volume of liquid in the vessel to be measured partially filled with liquid by measuring the change in the gas (typically air, or a gas with low solubility in water, such as hydrogen, oxyden, nitrogen, helium) pressure within the vessel to be measured after forcing air from a vessel of known volume (reference vessel) to the vessel to be measured. The volume of the so-called empty space in the vessel remaining free from liquid is calculated using the inversely proportional dependence between the pressure and volume changes. The temperature of the gas is preferably measured in the reference vessel, in the vessel to be measured, or in both vessels to take into account the change of the temperature before and after connecting the reference vessel to the vessel to be measured. The volume of the liquid to be measured is determined based on the total volume of the measured vessel, and the volume of the empty space. By means of a software application the result is obtained quickly and in an electronically processed format. Using of the method is facilitated, and the results become more tamper-proof by making use of a suitable security sticker located on the vessel to be measured, e.g. a security sticker readable by means of a radio device. The vessel to be measured is typically a bottle. In that case the security sticker is preferably placed on the bottleneck, and the security sticker reader is integrated into the measuring head connected to the mouth of the bottle. The design of the measuring head has been selected so as to enable only reading of the security sticker located on the neck of the bottle placed in the reader. Using a security sticker also creates additional possibilities for automation the measurement process, and integrating it with cash register, warehouse management, and other systems, and simplifying and making faster several stages of bar-room work.

The object of the invention is achieved in a system including a cylinder of known size comprising a piston, and having a measuring head pneumatically connected to the cylinder. For measuring the cylinder is connected to the bottle to be measured via the measuring head, whereas the pressures in both the cylinder and the bottle are equal at the start of the measurement process (usually equal to the ambient air pressure). Then the air is forced out of the cylinder and into the bottle to be measured using the piston, and the pressure change (increase) is recorded. The volume of the empty space in the bottle is calculated based on the pressure change, and the amount of liquid in the bottle is calculated based on the size of the bottle, and the volume of the empty space in the bottle. The bottle is equipped with an appropriate identification tag for determining the size of the bottle, containing information required to determine the size of the bottle, and the measuring head is equipped with a reader device for reading the information from the identification mark.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 depicts a schematic diagram of the system of the invention according to one embodiment of the invention.

Figure 2 depicts a schematic diagram of the system of the invention according to another embodiment of the invention.

Figures 3A to 3C show possible connections for the temperature sensors in the system.

EXAMPLES

Figure 1 depicts a system 1 for determining the amount of liquid in vessels, e.g. in bottles, where the method of the invention is used. The system includes a measuring head 23 containing a connector 4 connected hermetically to the mouth 3 of a bottle 2, that is pneumatically connected to a reference vessel 6 via a pipe 5, the reference vessel being a cylinder equipped with a piston 8 movable from one end of the cylinder to the other by means of a drive 7. A pressure sensor 9 for measuring the pressure within the pneumatic system, i.e. in the pipe 5, cylinder 6, and bottle 2 connected to them, is connected to the pipe 5. The pipe 5 is equipped with an electrically controlled valve 10 for pneumatically connecting the pipe to the external environment, and disconnecting from it. The measuring head 23 is equipped with an identification element reader 11 for reading the identification element 12 attached on the bottle, and with a button 13 for starting the measuring process. The system also includes a control and power unit 14 for controlling the operation of the system components, and supplying them with the power required for operation. The system is equipped with a calculation module 15 for processing the measurement results, and presenting them on a display 16 in a suitable format, and with a communication module 17 for transferring the data over a suitable communication network to a desired computer system, for example to a cash register and warehouse management system. The system has been set up to function in the following way. The piston 8 can be moved in the cylinder 7 between the two extreme positions by means of the drive 6, whereas the cylinder connected to the pipe 5 has the maximum volume in case of the first extreme position of the piston, and the cylinder has the minimum volume (zero) in case of the second extreme position, i.e. the whole amount of gas (air) present in the cylinder has been forced out of the cylinder. The pipe 5 is connected to the mouth 3 of the bottle to be measured by means of the connector 4. This equalises the pressures within the bottle 2, pipe 5, and cylinder 6. The button 13 starts the measuring process. The valve 10 is opened at the start of the measuring process so the pipe 5 is connected to the external environment, the piston 7 located in the cylinder 6 is moved to the first extreme position, the cylinder 6 is filled with the air from the external environment, and the pressures within the cylinder 6 and pipe 5 are equalised with the pressure of the external environment. After that the valve 10 is closed, and the initial pressure PI within the system is measured by means of the pressure sensor (presumably the pressure is equal to the pressure of the air, i.e. the pressure sensor can be calibrated to consider the pressure measured in case of the open position of the valve 10 as the zero pressure). After that the piston 8 is moved from the first extreme position to the second extreme position by means of the drive 7, forcing air out of the cylinder 6 into the pipe 5 and bottle 2. As the total volume of the system decreases the pressure within the system increases. The new pressure value P2 is determined by means of the pressure sensor. The volume of the free space in the bottle is determined from the ideal gas law based on the simplified assumption that the products of the volume and the pressure within the system before and after forcing the air from the cylinder into the bottle are equal:

VI * PI = V2 * P2, where VI = (Vbottle + Vsystem + Vcylinder) and V2 = (Vbottle + Vsystem), where Vbottle is the volume of the empty portion of the bottle, Vsystem is the total volume of the system, formed also by the volumes of the pipe and valves, and Vcylinder is the volume of cylinder 6 in case of the first extreme position of the piston.

Consequently: (Vbottle + Vsystem + Vcylinder) * PI = (Vbottle + Vsystem) * P2;

Vbottle * PI + Vsystem * PI + Vcylinder * PI = Vbottle * P2 + Vsystem * P2 or Vbottle = (Vsystem * (P2 - PI) - Vcylinder * PI) / (PI - P2)

Airtight connection of the connector 4 to the mouth 3 of the bottle 2 is essential for operating the system. For this the pressure is measured repeatedly throughout an adequate period of time after forcing air out of the cylinder 6, to make sure the pressure is constant (stable). When the pressure stays constant in view of the required accuracy then the measuring has succeeded. If the pressure decreases the system will record a measuring failure, and the measuring process has to be repeated from the start.

This simplified formula does not take into account the impact of the change of the temperature in the system when the gas is compressed into reference vessel or released from the reference vessel into the vessel to be measured. Particularly for consecutive measurements the change of temperature introduces a systematic error into measurements. Therefore, also the temperature must be measured. It is easy to see that Vsystem = Vcylinder * P1*T1 / P2*T2, where Tl is the temperature of the gas in the reference vessel at the beginning of the measurement when PI is measured and T2 is the temperature of the gas at the time the pressure P2 is measured after the gas is introduced into the vessel to be measured.

Figure 3A shows one solution according to the invention where the temperature sensor 24 is located in a silinder 6 for measuring the temperature before and after compressing the gas in the cylinder. Figure 3B shows another option, where intermediate vessel 19 is used and where temperature sensor 24 is located within. Figure 3C shows yet another option where the temperature sensor 24 is located within the measuring head 23 and is adapted to measure the temperature within. In preferred embodiment, to reduce the systematic error, the pressure sensors and the temperature sensors are located adjacent to each other and the readings are taken simultaneously. Any type of temperature sensors known from the art can be used provided it has sufficient speed of response to the change in temperature. Suitable examples include thermistors and thermocouples. One suitable temperature sensor with very simple desigg is a net made of long thin metal wire as shown in Figures 3 A to 3C.

According to the first embodiment example the bottle is equipped with a so-called i-Code security sticker 11 that has been glued on the bottleneck, and contains a unique numeric identifier. The security sticker is issued for bottles in the course of warehouse procedures, and the data of the security sticker and the bottle are stored in the system. The security sticker cannot be removed from the bottle without destroying the possibility of reading it by means of a radio device. The measuring head 23 is shielded for the sake of security, or other solutions are used to enable only the reading of security stickers located within the measuring head during the measuring process. In the course of the measuring process the data identifying the bottle are read from the security sticker by means of a reader device, and compared to the data stored in the system. If the security sticker is missing or the security sticker is damaged so the data on it cannot be read, or the data do not correspond to the data present in the database (e.g. a counterfeit security sticker; outdated or annulled security sticker, etc.) then an alarm will be fixed. If the identification data read from the security sticker correspond to the data stored in the memory then the process of measuring the liquid contained in the bottle will be started.

Another embodiment of the invention is depicted on Figure 2. The system 1 includes a measuring head connected hermetically to the mouth 3 of a bottle 2, and comprising a connector 4 that is pneumatically connected to an intermediate vessel 19 via a pipe 5, and through an electrically controlled valve 18, the intermediate vessel in its turn is connected to a pump 22 via a pipe 20 and through an electrically controlled valve 21. A pressure sensor 9 for measuring the pressure within the system (within the pipes 5 and 20, intermediate vessel 20, and bottle 2) is connected to the intermediate vessel 19. The intermediate vessel 19 can be connected to the external environment via an electrically controlled valve 10.

The system is equipped with an identification element reader 11 for reading an identification element 12 attached to the bottle. The system also includes a control and power unit 14 for controlling the operation of the system components, and supplying them with the power required for operation. The system is equipped with a calculation module 15 for processing the measurement results, and presenting them on a display 16 in a suitable format, and with a communication module 17 for transferring the data over a suitable communication network to a suitable computer system, for example to a cash register and warehouse management system.

The system according to the second embodiment is used as follows. The valves 10 and 18 are closed. After that the valve 21 is opened, and a known pressure P3 is generated within the intermediate vessel 19 by means of the pump 22. The valve 21 is closed, and stability of the pressure P3 is ascertained. The connector 4 is hermetically connected to the mouth 3 of the bottle 2, and the valve 18 is opened. The pressure P4 is measured. The volume of the empty portion of the bottle is determined based on the change in the pressures P3 and P4 according to the relation Vsystem * P3 = Vsystem + Vbottle * P4.

The system according the embodiments is preferably designed as handheld device, comprising a handle portion and a measuring head. At least the pneumatic components, but preferably all the essential components are embodied within this handheld device. Such device can be battery operated, or may include a power supply unit connected to a power outlet. The device may include a data interface, preferably wireless connection unit capable of transmitting measurement data over wireless network, such as WiFi (IEEE 802.11), Bluetooth, etc.

Claims

1. Method for determining the amount of a liquid in a vessel for inventory taking in catering establishments, comprising determining the amount of liquid in the vessel based on the difference between a total volume of the vessel and a volume of a free space in the vessel, whereas determining the volume of the free space in the vessel isbased on a pressure change caused by forcing air into the free space in the vessel, characterised in that the method comprises hermetically connecting a reference vessel of known size to the vessel, measuring a first air pressure within connected vessels, forcing air into the vessel from a reference vessel of known size, measuring a second air pressure within the vessel, and calculating the volume of the free space in the vessel from the difference of the first and second pressure.

2. Method according to claim 1, characterised in that forcing air from the reference vessel into the vessel is performed by means of a piston slidably embodied in the reference vessel.

3. Method according to claims 1 to 2, comprising reading a unique identification number of the vesseland determining the authenticity and volume of the vessel based on the identification number.

4. Method according to claim 3, comprising reading the identification number by means of a radio signal from a security sticker attached to said vessel.

5. Method according to claims 3 to 4, comprising storing the unique vessel identification numbers, the data regarding the amount of liquid and the changes in the amount of liquid obtained at consecutive measurements in a database.

6. Method according to claims 3 to 5, comprising associating the data in the database with a cash register software, and warehouse management software of the catering establishment.

7. Method according to claims 3 to 6, comprising entering an identification number of a person conducting the measurements and a measuring time into the database at measuring.

8. Method according to claims 1 to 7, comprising measuring a temperature of the gas in a system before and after forcing the gas into the vessel.

9. System for determining an amount of a liquid in a vessel for the purpose of inventory taking in catering establishments, comprising a volume measuring device that contains a reference vessel with known gas pressure, a connector pneumatically connecting the reference vessel to the vessel, and a pressure sensor for measuring the pressure within the reference vessel, characterised in that the system comprises a measuring head to be pneumatically connected with the vessel, said measuring head equipped with an identification element reader adapted for reading an identification element located on the vessel, and the system is equipped with a communication module adapted for transferring measuring data to the cash register software and warehouse management system.

10. System according to claim 9, characterised in that the volume measuring device comprises a cylinder containing a piston, and a drive for moving the piston between the two extreme positions, whereas the cylinder is connected to the vessel to be measured, and the external environment via a valve, and the system includes a control unit for controlling the drive and valve, whereas the control unit has been adapted to open the valve, move the piston to the first extreme position with the purpose of filling the cylinder with air during the open state of the valve, close the valve, and move the piston to the second extreme position with the purpose of forcing the air present in the cylinder into the vessel to be measured.

11. System according to claim 10, characterised in that the control unit is adapted to measure the first pressure corresponding to the open state of the valve and the first extreme position of the piston by means of the pressure gauge, and the second pressure corresponding to the closed state of the valve and the second extreme position of the piston.

12. System according to claims 9 to 11, comprising a temperature sensor in said measuring head for measuring the temperature of said gas in said vessel.

13. System according to claims 9 to 12, comprising a temperature sensor in said reference vessel for measuring the temperature of said gas in said system.

14. System according to claims 9 to 13, comprising means for identifying a user using the system for measurement process.