Refrigeration – Automatic control – By accumulation on freezing surface – e.g. – ice
Reexamination Certificate
1997-10-28
2002-09-17
Wayner, William (Department: 3744)
Refrigeration
Automatic control
By accumulation on freezing surface, e.g., ice
C062S059000, C324S706000
Reexamination Certificate
active
06449966
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to beverage dispensers and in particular electronically controlled beverage dispensers of the ice bank type.
BACKGROUND OF THE INVENTION
Beverage dispensers are well known in the art and are typically used to dispense carbonated beverages consisting of a combination of syrup and carbonated water. Beverage dispensers of the ice bank variety use refrigeration equipment including a compressor, condenser and evaporator to form an ice bank around the evaporator coils. The ice bank is suspended in a tank of cold water and provides a cooling reserve for the carbonated water and syrup beverage constituents.
A major problem with the ice banks concerns the regulation of the size thereof. Mechanical and electro-mechanical controls are known, however such controls can be slow to respond and therefore result in wider than desired fluctuation in the size of the ice bank. Electronic controls are known whereby a pair of probes determine the presence of ice or water as a function of the conductivity thereof However, early electronic controls suffered from reliability problems, and the probes over time can become corroded and therefore provide unreliable information. Furthermore, both mechanical and electronic controls have the problem of hysteresis management wherein undesirable short cycling of the refrigeration compressor can occur. Such prior art controls have not been able to determine with a high degree of certainty if ice is present, and if so is there is sufficient thickness that further ice production should be terminated.
A similar problem exists in current art beverage dispensers with respect to the carbonator. The carbonator, of course, is the vessel wherein plain water and carbon dioxide are combined to produce the carbonated water. Typically, a carbonator includes a probe positioned therein having high and low probe contact points for electronically determining the level of water within the carbonator. Specifically, the probes determine the presence of water or air with respect to the difference in electrical resistance there between. Prior art level controls of this type, as with ice bank controls, suffer with the problem of accuracy. The interior of the carbonator is a dynamic environment where water and carbon dioxide are being combined causing turbulation and spray: Thus, it has always been difficult to know if the water is in fact sufficiently low to require water to be pumped to the carbonator. Since it is difficult to know the level of the water in the tank, it is also difficult to build in any form of hysteresis control so that the pump is not short cycled.
A further problem with prior art dispensers of the ice bank type concerns the control of the agitator motor. The agitator motor is used to circulate water within the water tank in which the ice bank resides to enhance heat exchange between the ice and the water and ultimately the beverage constituents. In such prior art dispensers agitator motors are generally operated continuously. However, such use of electrical power is wasteful, especially during periods of time wherein the dispenser is not in use. Thus, it would be desirable to operate the agitator motor more in accordance with the actual need thereof.
It is also known that the carbonator can become less effective at carbonating plain water over time. This can occur as a result of oxygen and other gases entrained in the water being released therefrom within in the carbonator. Eventually, the air space within the carbonator that is ideally totally carbon dioxide, can include a substantial percentage of oxygen, nitrogen, and so forth. Thus, various strategies have been proposed to use a solenoid operated valve to periodically vent air from the carbonator air space and replace it with carbon dioxide. However, such devices typically purge air from the carbonator based upon a predetermined time lapse. It would be more desirable to purge the carbonator based more directly upon the actual presence of contaminating gases as opposed to the lapse of a predetermined period of time where such purging may occur needlessly.
SUMMARY OF THE INVENTION
The present invention is an electronic control for use with a beverage dispenser, and particular a beverage dispenser of the ice bank type. Such a beverage dispenser includes a water tank for holding a volume of water. The water is refrigerated by an evaporator suspended therein and connected to a compressor and a condenser. A fan motor is used to cool the condenser. A plurality of syrup lines extend through the tank for cooling thereof and are connected to a plurality of beverage dispensing valves secured to the beverage dispenser. In the preferred embodiment, a carbonator is positioned within the water tank to provide for direct cooling thereof. The carbonator includes a level sensor having low and high sensing contact points and includes a solenoid operated safety valve. The carbonator has a plurality of carbonated water lines extending therefrom for connection to the plurality of beverage dispensing valves. An agitator motor is secured to the dispenser and includes a shaft and an agitating plate for providing movement of the water in the water bath. An ice bank sensor is positioned within the water bath with respect to the evaporator coils to provide for the formation of the desired sized ice bank on the evaporator coils. The ice bank sensor includes two probes across which an electrical pulse can be generated. A temperature sensing probe is positioned with respect to the evaporator coils so that it exists centrally within the ice bank. A water pump provides for pressurized delivery of plain water to the carbonator tank.
The electronic control of the present invention includes a microprocessor connected to and receiving information from the ice bank sensor, the temperature sensor and the carbonator level sensor. In turn, the microprocessor is connected to and provides for the control, of the solenoid safety valve, the agitator motor, the water pump and the compressor. Of course, the ice bank sensor, the temperature sensor, the carbonator level sensor, the solenoid safety valve, the agitator motor, the water pump and the compressor all have specific circuitry associated therewith through which the microprocessor exercises control and receives information. Power is supplied to the microprocessor by a regulated supply and further input is provided thereto by a zero crossing circuit. A constant reference voltage circuit is supplied to the microprocessor and to the ice bank probe and carbonator probe.
The microprocessor is programmed to control the ice bank sensor and related circuitry wherein a DC signal is alternately permitted to flow in opposite directions between the two probes thereof.
The microprocessor is programmed to control the ice bank sensor and related circuitry wherein the presence or not of ice is determined by the change in resistance to electrical flow between the probes thereof. However, unlike the prior art a DC signal is alternately permitted to flow in opposite directions between the two probes thereof. Moreover, this energizing of the probes only occurs when readings are to be taken, otherwise there is no potential there between. Furthermore, it was found that if each sampling occurs for a period of time of less than 4 milliseconds, corrosive deposition from one probe to the other can be avoided. Also, the alternating of the direction of the current flow further serves to negate any deposition that could occur over time as well as permit the use of DC current which allows for simpler and less costly circuitry than with the use of AC current as seen in the prior art. The sampling is controlled by software wherein 8 readings are taken after which the two highest and two lowest readings are thrown out and the remaining four are averaged. The resulting reading is compared to high and low set points that have been experimentally determined based upon the known range of water qualities as well as the particular dimensions of the ice sensor, its specific performance
Bethuy Timothy W.
Goulet Douglas P.
Hakanson Sten Erik
IMI Cornelius Inc.
Wayner William
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