Refrigeration – Automatic control – By congealed removable product condition
Reexamination Certificate
2000-02-14
2001-05-22
Tapolcai, William E. (Department: 3744)
Refrigeration
Automatic control
By congealed removable product condition
C062S138000, C062S346000
Reexamination Certificate
active
06233953
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention concerns a flake ice machine having a cylindrical evaporating cylinder, a transmission or transmission motor with electric drive (electric motor) for the evaporating cylinder, a refrigerator, also driven electrically, which guides the cooling means through the evaporating cylinder, an evaporating pan, which can be filled with water, the evaporating cylinder disposed in the evaporating pan in a rotatable manner for wetting the evaporating cylinder with water, as well as means for removing (peeling off or flaking off) the flake ice from the circumference of the evaporating cylinder, and electric control means for the evaporating cylinder and refrigerator drives.
Flake ice machines of this type produce relatively thin flake ice for keeping food fresh, particularly in the meat industry.
A conventional flake ice machine of this kind (DE 41 08 911 A1, EP 535 498 A2) comprises an evaporating cylinder moistened by inserting one side thereof into an evaporating pan filled with water. The evaporating cylinder is turned and residual water freezes on the circumference of the evaporating cylinder. The ice layer thereby generated is removed from the circumference of the evaporating cylinder by a device disposed at the cylinder, before renewed dipping into the water. This is done either by peeling off or by flaking off the ice. The evaporating cylinder contains a cooling evaporator which is connected to a refrigerator disposed outside the cylinder. The refrigerator is preferably a compressor-driven machine. In any event, the refrigerator and the evaporating cylinder drive are controlled electrically via an electric control means. The filling time, the ice production and the water level in the evaporating pan are monitored by the control means to prevent damage to the flake ice machine due to defects in e.g. the evaporating cylinder or refrigerator drives or the water supply. Should the monitored quantities exceed or fall below the predetermined limiting values, the evaporating cylinder and the refrigerator drives are switched off. The control means comprises several sensors for monitoring. One sensor checks the thickness of the ice layer on the circumference and therefore the ice production. Another sensor detects the water level in the evaporating pan and an additional sensor monitors the filling time of the evaporating pan. Each sensor provides a measured value which has to be processed by the control means and compared with the predetermined limiting values. Disadvantageously, these conventional flake ice machines are demanding and expensive to manufacture due to the number of sensors and the corresponding control means.
SUMMARY OF THE INVENTION
In contrast thereto, the flake ice machine according to the invention has the advantage that only one sensor is provided to signal the control means for the evaporating cylinder and the refrigerator, to control the filling time of the evaporating pan, the ice production and the water level in the evaporating pan. The measured value to which the sensor reacts is thereby selected in such a manner that it is sensitive to the filling time, the thickness of the ice layer on the evaporating cylinder and to the water level in the evaporating pan. The control means checks whether the measured values detected by the sensor are within predetermined limits and whether or not the measured values have changed. The limiting values are selected by taking into consideration values for the filling time, the thickness of the ice layer and the water level which are not critical to proper operation of the flake ice machine. If a measured value exceeds the predetermined limiting value, the refrigerator and evaporating cylinder drives are switched off by the control means before the flake ice machine could be damaged.
According to an advantageous embodiment of the invention, the measured value detected by the sensor is the change of the water level in the evaporating pan over time. If the water level does not change within a predetermined time period of e.g. 60 seconds or if its change exceeds a predetermined limiting value, the evaporating cylinder and refrigerator drives are switched off after this time period has elapsed. Should e.g. the water supply be interrupted, water can no longer flow and the water level drops below the predetermined limiting value within the predetermined time period. This causes the flake ice machine to switch off. If either the evaporating cylinder or the refrigerator drive fails, ice production stops and the water level does not change. This also leads to switch-off of the flake ice machine. Should the evaporating cylinder freeze as a result of an excessively low supply temperature, the water level does not change within the time period. This also leads to switch-off of the flake ice machine after elapse of the time period. In the most unfavorable case, all of the liquid in the evaporating pan freezes. In this case, the sensor fails to provide measured values and switch-off of the flake ice machine is also triggered after the predetermined time period has elapsed. In an advantageous manner, monitoring of the changes in the water level over time begins with a delay with respect to the start of operation of the refrigerator. The delay may vary, depending on the type of flake ice machine. A typical value is e.g. 120 seconds. The monitoring control is transition operated.
According to a further advantageous embodiment of the invention, the sensor comprises a floating switch provided on the evaporating cylinder. Advantageously, floating switches are independent of the chemical and physical properties of the freezing liquid used. Therefore, there are e.g. no conductance-related problems when the ice is produced from distilled water. Moreover, should the floating switch be defective due e.g. to a broken cable, contact can no longer be interrupted or established, wherein no change in the water level within the predetermined time period is detected and the flake ice machine is therefore switched off.
Further advantages and advantageous embodiments of the invention can be extracted from the following description, the drawing and the claims.
An embodiment of the invention is shown in the drawing and is described in more detail below.
REFERENCES:
patent: 2308541 (1943-01-01), Raver
patent: 2749722 (1956-06-01), Knowles
patent: 4459824 (1984-07-01), Krueger
patent: 4700551 (1987-10-01), Nyrup
patent: 5257510 (1993-11-01), Cox
patent: 5477694 (1995-12-01), Black et al.
patent: 5913711 (1999-06-01), Visaisouk
patent: 89 12 336 (1990-01-01), None
patent: 90 02 856 (1990-07-01), None
patent: 41 08 911 (1992-09-01), None
patent: 93 07 466 (1993-08-01), None
patent: 295 17 340 U (1995-12-01), None
patent: 05 35 498 (1993-04-01), None
Maja-Maschinenfabrik Hermann Schill GmbH
Tapolcai William E.
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