Measuring and testing – Vibration – By mechanical waves
Reexamination Certificate
2000-11-02
2001-12-04
Williams, Hezron (Department: 2856)
Measuring and testing
Vibration
By mechanical waves
C073S629000, C073S29000R, C073S597000, C073S602000
Reexamination Certificate
active
06324911
ABSTRACT:
DESCRIPTION OF INVENTION
This invention relates to an apparatus and method for detecting an interface, and particularly but not exclusively for detecting an interface between separate phases of a heterogeneous system, such as, for example, an interface between a liquid and a gas, or a liquid and a solid.
The invention is particularly directed at detecting an interface between water and a gas above the level of the water, whereby to detect the level of water in (e.g.) a container, and/or an interface between water and ice, such as are found in beverage coolers/carbonators.
Conventionally in beverage coolers/carbonators a probe has been used to monitor the level of the liquid. Such probes typically comprise means to measure the conductivity of the medium in which the probe is immersed, from which measurement of the depth of the probe covered by the liquid may be determined. However the conductivity of water varies considerably between different geographic regions, and indeed, some types of water contain so few free ions that the conductivity is extremely difficult to detect.
Additionally, beverage coolers/carbonators usually comprise a bank of cooling medium such as ice, located within a chamber in which the potable liquid is cooled. The depth of the bank of ice varies in accordance with the demand placed on the system, and it is thus desirable to monitor the depth of the ice bank so that the amount of refrigerant which is caused to flow to the ice bank may be controlled as appropriate.
It has however hitherto been extremely difficult to monitor the depth of the ice bank satisfactorily.
According to a first aspect of the invention, there is provided apparatus for detecting an interface between two media of a heterogeneous system, comprising transmission means to send a signal through one medium to the interface, measuring means to measure the time taken for the signal to be reflected to a reception means, and processing means to use said time to determine the distance of the interface from the transmission means.
If desired the transmission means and the reception means may be located adjacent to one another, but conveniently the transmission means and the reception means are coincident.
Conveniently the apparatus comprises a wave guide, the transmission means being provided by a transducer located at one end of the wave guide, said wave guide passing through, and containing, said one medium.
Thus, conveniently, the wave guide extends from a position below a chamber containing said one medium to a position at or beyond the interface.
Preferably the apparatus comprises a datum disposed in the same medium as that through which the signal is sent, and measuring means adapted to measure the time taken for a signal to be reflected from the datum to the or a further reception means Said measuring means may be the measuring means which measures the time taken for the first said signal to be reflected, and the or a further processing means may be utilized to determine the velocity of the signal in the medium, and hence the distance of the interface from the transmission means, in dependence upon the measured time.
Conveniently the wave guide comprises reflecting means operative to reflect a signal from the transmission means to a second interface, such as between water and ice within said chamber. Advantageously, the reflecting means is also operative to reflect a reflected signal from the second interface to the reception means.
Thus the reflecting means may be provided adjacent to a section of the waste guide which is open or substantially transparent to the signal.
In this way by the use of the or a further processing means, the thickness of a bank of ice within the chamber may be determined.
According to this invention there is also provided a beverage cooler and/or carbonator incorporating apparatus as set out above.
According to this invention there is also provided a method of detecting an interface between two media of a heterogeneous system, comprising sending a signal through one medium from a transmission position to the interface, measuring the time taken for the signal to be reflected to a reception position, and using the time taken to determine the distance between the transmission position and the interface.
Conveniently, the time taken is utilized to calculate the temperature of a liquid phase of the system.
Preferably, the signal comprises an ultrasound wave.
The method is particularly suitable for detecting an interface between a liquid and a gas, such as water and air/carbon dioxide, as is found in beverage coolers/carbonators.
The transducer is preferably constructed from a material such as polyvinyl-difluorodine, conveniently covered with a thin layer of stainless steel to protect it and to provide a good ground connection.
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Ohlandt Greeley Ruggiero & Perle LLP
Saint-Surin Jacques
Whitlenge Drink Equipment Limited
Williams Hezron
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