JP5898967B2 - Vacuum cooling device - Google Patents

Description

  The present invention rapidly cools an object to be cooled by storing the object to be cooled such as cooked food in a cooling tank and evaporating moisture in the object to be cooled by depressurizing the inside of the cooling tank. The present invention relates to a vacuum cooling device.

  As described in Japanese Patent No. 3173535, there is known a vacuum cooling device that evaporates moisture from an object to be cooled by reducing the pressure in the cooling tank and cools the object to be cooled by vaporization heat generated by evaporation. . In food service centers and the like, it is required to pass through the temperature range in which miscellaneous germs propagate as soon as possible when cooling cooked food. Cooling to the center of the object to be cooled in a short time is possible with a vacuum cooling device. Is widely used because it is possible. However, when the pressure reduction rate is too high, a bumping phenomenon may occur due to the pressure in the cooling tank being lower than the saturated vapor pressure determined from the product temperature of the object to be cooled. In that case, the object to be cooled may be broken or scattered. Even when air is introduced into the cooling tank after cooling to return the pressure to the cooling tank, the object to be cooled may be deformed if the return pressure speed is too high. For this reason, it is possible to perform slow cooling that slows down the decompression speed in accordance with the properties of the object to be cooled and slow return that slows down the decompression speed after decompression.

  In the vacuum cooling device, a vacuum generator is connected to the cooling tank via a vacuum pipe, and the air in the cooling tank is discharged by operating the vacuum generator. A vacuum cooling pipe provided with a slow cooling valve is connected to the vacuum pipe in the middle so that air can be taken in via the slow cooling pipe. When the slow cooling valve is opened during air suction by the vacuum generator, air is sent to the vacuum pipe through the slow cooling pipe, and the vacuum generator sucks air from the slow cooling pipe in addition to the air in the cooling tank. Therefore, the amount of air discharged from the cooling tank is reduced, and the pressure reduction speed in the cooling tank is reduced. The pressure reduction rate in the cooling tank can also be adjusted by increasing or decreasing the amount of air introduced from the slow cooling valve, and the pressure reduction rate can be increased by increasing the air introduction amount by increasing the opening of the slow cooling valve. If the opening of the slow cooling valve is reduced and the amount of air introduced is reduced, the reduction in the pressure reduction rate is reduced. The same is true for the gradual return at the time of return pressure, and an air intake valve that can adjust the opening is provided in the part where the air for return pressure is introduced into the cooling tank, and the return pressure can be increased by increasing the opening of the air intake valve. The speed increases, and the return pressure speed decreases as the opening of the air intake valve is reduced.

  When performing slow cooling operation or slow return operation, set the elapsed time and the pressure in the cooling tank at that time as the target pressure, and adjust the opening of the slow cooling valve or air intake valve so that it becomes the target pressure While driving. If the tank pressure actually measured is higher than the target pressure set for slow cooling, it means that the pressure reduction speed is insufficient due to the large amount of air taken in by the slow cooling valve. In order to reduce the air intake, the pressure reducing speed is increased. Conversely, if the tank pressure actually measured is lower than the target pressure set for slow cooling, it means that the pressure reduction speed is too fast because the amount of air taken in by the slow cooling valve is small. In that case, the amount of air intake is increased by increasing the opening of the slow cooling valve, and the pressure reduction speed is decreased.

  The amount of change in the opening of the slow cooling valve is determined based on the difference between the target pressure and the pressure in the tank, and the amount of change in the opening of the slow cooling valve increases as the difference between the target pressure and the pressure in the tank increases. Set as follows. PID control is performed, the opening change amount of the slow cooling valve is determined according to the difference with the target pressure, and the opening of the slow cooling valve is adjusted so as to eliminate the difference, so that the pressure in the tank follows the target pressure. Although it should be possible to reduce the pressure, there may actually be a deviation between the tank pressure and the target pressure. If the pressure in the tank does not match the target pressure, the object to be cooled is damaged or scattered due to bumping, and it takes a long time to complete the operation.

Japanese Patent No. 3173535

  The problem to be solved by the present invention is that when performing slow cooling operation or slow return operation with a vacuum cooling device, vacuum cooling that can reduce the deviation of the internal pressure of the tank from the target pressure and increase the accuracy of pressure control. To provide an apparatus.

The invention described in claim 1 has a cooling tank for storing an object to be cooled and a vacuum generator for discharging the air in the cooling tank, and the inside of the cooling tank is evacuated so as to accommodate the object to be stored in the cooling tank. It is a vacuum cooling device that cools the cooling object, and is equipped with a slow cooling pipe with a slow cooling valve and an operation control device that controls the operation of the vacuum cooling device. The operation control device is gradually cooled during vacuum cooling. By adjusting the valve opening and introducing air for slow cooling through the slow cooling valve, it is possible to perform slow cooling operation that reduces the pressure reduction rate. During vacuum cooling operation, the pressure in the cooling tank is detected. Compare the tank pressure detected by the pressure detector with the target pressure set corresponding to the elapsed time, and adjust the opening of the slow cooling valve so that the tank pressure approaches the target pressure. In the vacuum cooling device, the operation control device has a tank internal pressure. The median opening, which is the slow cooling valve opening when is equal to the target pressure, is set to a large opening at the beginning of the cooling operation and set to a small opening as the cooling operation proceeds. In the initial stage of cooling operation, the control range of the slow cooling valve opening is reduced by increasing the opening expansion width from the central opening and increasing the opening reduction width. The opening reduction possible width from the value is reduced, and the opening enlargement possible width is set to increase.

  According to a second aspect of the present invention, in the vacuum cooling device, the opening degree of the air intake valve is adjusted so that the target pressure set in accordance with the elapsed time is obtained even when the pressure is restored after completion of the vacuum cooling. In that case, the opening of the air intake valve is made smaller when the degree of vacuum in the cooling tank is high, and the air intake is taken in as the degree of vacuum in the cooling tank decreases as the return pressure operation proceeds. The valve opening is set so as to increase.

  The problem during slow cooling is that the vacuum generator operates in the same way, and even if the opening of the slow cooling valve is the same, more air is discharged from the cooling tank during low vacuum, so cooling This is because the pressure reduction rate in the cooling tank is increased, and the amount of air discharged from the cooling tank is reduced during high vacuum, so the pressure reduction speed in the cooling tank is reduced. If the median value of the gradual cooling valve opening relative to the target pressure is shifted so that it becomes fully closed when the vacuum is low and the higher the vacuum is, the chilling valve opening increases at the time of low vacuum. The action of lowering the pressure is increased, and when the vacuum is high, the opening of the slow cooling valve is reduced, so that the action of reducing the pressure reduction speed is reduced. This makes it possible to prevent the pressure reduction rate from becoming too high at low vacuum, where the pressure reduction rate tends to be high, and conversely, the pressure reduction rate is too low even at high vacuum, where the pressure reduction rate tends to be slow. Therefore, the pressure can be reduced along the target pressure.

  The same is true at the time of return pressure, and even if the opening of the air intake valve is the same, the return pressure speed in the cooling tank increases at high vacuum, and the return pressure speed in the cooling tank decreases at low vacuum. There was a nature. In this case as well, if the median value of the air intake valve opening relative to the target pressure is shifted so that it is closer to full close when high vacuum is applied and the full open direction is increased as the vacuum is reduced, the air intake valve opening is increased during high vacuum. Since the pressure decreases, the return pressure speed becomes slower. When the vacuum is low, the air intake valve opening increases, so that the action of reducing the return pressure speed becomes smaller. This reduces the return pressure rate during high vacuum, where the return pressure rate tends to be high, and prevents the return pressure rate from becoming too low during low vacuum, where the return pressure rate tends to be slow. Therefore, it is possible to perform return pressure along the target pressure.

  By carrying out the present invention, when performing a slow cooling operation or a slow return operation, it is possible to control the pressure change rate so that it does not become too fast when the pressure change rate tends to be high. It is possible to control so that the pressure change rate does not become too small at a time when the pressure tends to be slow. Therefore, the slow cooling operation and the slow return operation along the target pressure can be performed, and both suppression of bumping and shortening of the operation time can be achieved.

Flow diagram of a vacuum cooling apparatus for carrying out the present invention Explanatory drawing explaining the slow cooling valve / air intake valve opening change amount with respect to the deviation from the target pressure during the slow cooling / slow return operation

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a flow chart of a vacuum cooling apparatus embodying the present invention, and FIG. 2 is an explanatory diagram for explaining an amount of change in opening degree of a slow cooling valve / air intake valve with respect to a deviation from a target pressure during slow cooling / slow return operation. . The vacuum cooling device has a cooling tank 2 that accommodates an object to be cooled 7 and a vacuum generator 1 that discharges air in the cooling tank 2, and is accommodated in the cooling tank 2 by evacuating the inside of the cooling tank 2. The cooled object 7 is cooled.

  The vacuum generator 1 is connected to the cooling tank 2 by a vacuum pipe 9, and the air in the cooling tank 2 is discharged through the vacuum pipe 9 by operating the vacuum generator 1. In order to perform gradual cooling with a slow cooling rate when the object to be cooled 7 is cooled, a gradual cooling pipe 4 provided with a gradual cooling valve 3 is connected to the vacuum pipe 9 and the gradual cooling valve 3 is opened. The outside air enters the vacuum pipe 9 through the slow cooling pipe 4. An electric proportional valve is used as the slow cooling valve 3, and the opening degree of the slow cooling valve 3 can be freely adjusted between 0% and 100%.

  Moreover, since the inside of the cooling tank 2 is in a negative pressure state when the cooling is completed by the vacuum cooling device, it is necessary to return the pressure of the cooling tank 2. In order to return the pressure in the cooling tank 2, a return pressure device having an air intake valve 8 is provided in the cooling tank 2. In the case where it is necessary to perform gradual return that gradually returns even when the pressure is restored, the air intake valve 8 is also an electric proportional valve, and the air intake valve 8 also freely adjusts the opening between 0% and 100%. Be able to do that.

  The cooling tank 2 is provided with a pressure detection device 5 for detecting the pressure in the cooling tank, and the value of the pressure in the cooling tank detected by the pressure detection device 5 is supplied to the operation control device 6 for controlling the operation of the vacuum cooling device. Output. The operation control device 6 controls the operation of each device based on the elapsed time and the tank pressure detected by the pressure detection device 5. The operation control device 6 sets an elapsed time and a target pressure in the cooling tank at that time, and a decompression speed or a decompression speed so that the tank pressure detected by the pressure detection device 5 becomes the target pressure. Adjust. In the present embodiment, the target pressure after the lapse of time A from the start of decompression is -10 kPa, the target pressure after the lapse of time B is -30 kPa, the target pressure after the lapse of time C is -50 kPa, and the target pressure after the lapse of time D is- The target pressure after elapse of 70 kPa and time E is set to −90 kPa.

  When the operation control device 6 performs the slow cooling operation, the operation control device 6 compares the target pressure determined from the time with the tank pressure at that time, and if the tank pressure is higher than the target pressure, the slow cooling valve 3 The opening degree is decreased, and when the tank pressure is lower than the target pressure, the opening degree of the slow cooling valve 3 is increased.

  At this time, the opening degree of the slow cooling valve 3 is increased as the initial stage of the cooling operation in which the tank internal pressure is high, and the slow cooling valve 3 is disposed toward the end of the cooling operation in which the internal pressure of the tank decreases as the cooling process proceeds. The opening degree is set so that the opening degree becomes smaller. This will be described with reference to FIG. In FIG. 2, the target pressure value set based on the elapsed time and the opening degree of the slow cooling valve 3 determined based on the tank internal pressure are shown. When the time A has elapsed from the start of the cooling operation, the target pressure is -10 kPa, and when the tank pressure detected by the pressure detection device 5 is higher than the target pressure, -10 kPa, the slow cooling valve 3 The opening degree is decreased, and when it is lower than the target constant value of −10 kPa, the opening degree of the slow cooling valve 3 is increased.

  When the tank pressure is the same as the target pressure, the slow cooling valve opening is not simply set at a fixed value of 50%. As the cooling operation proceeds, the median opening is set smaller. When the pressure in the tank at the time A is the same as the target pressure, the opening degree of the slow cooling valve 3 is 90%. If the tank pressure is higher than the target pressure, 80% if the tank pressure is -9.9 kPa, 70% if the tank pressure is -9.8 kPa, 60% if the tank pressure is -9.7 kPa, and so on. When the tank pressure is -9.1 kPa or less and is set to 0% sequentially, and the tank pressure is lower than the target pressure, the tank pressure is set to 100% if the tank pressure is -10.1 kPa or more. Since the pressure in the cooling tank is adjusted with the aim of -10 kPa, the opening degree of the slow cooling valve 3 at this time is likely to be around 90%. And even if the tank internal pressure is 0.1 kPa larger than the target pressure, the opening degree of the slow cooling valve 3 is 80%. When the tank internal pressure is 0.1 kPa smaller than the target pressure, the opening degree of the slow cooling valve 3 is Since it is set to 100%, the opening degree of the slow cooling valve 3 becomes large.

  In the case of time B, which is the next explanatory point, the slow cooling valve opening is 70% when the tank pressure is the same as the target pressure of −30.0 kPa. When the tank pressure is higher than the target pressure, 60% if the tank pressure is -29.7 kPa, 50% if the tank pressure is -29.4 kPa, 40% if the tank pressure is -29.1 kPa, and so on. If the tank internal pressure is -27.9 kPa or less and set to 0% sequentially, and the tank internal pressure is lower than the target pressure, 80% if the tank internal pressure is -30.3 kPa, 90% if the tank internal pressure is -30.6 kPa If the pressure in the tank is -30.9 kPa or more, it is set to 100%. If set in this way, the opening degree of the slow cooling valve 3 at this time is likely to be around 70%, and the opening degree of the slow cooling valve 3 is large, although not as much as in the case of time A. become.

  When the time C, which is the next explanatory point, has elapsed, the slow cooling valve opening is 50% when the tank pressure is the same as the target pressure of −50.0 kPa. When the tank pressure is higher than the target pressure, 40% if the tank pressure is -49.5 kPa, 30% if the tank pressure is -49.0 kPa, 20% if the tank pressure is -48.5 kPa, and so on. When the tank pressure is -47.5 kPa or less and set to 0% sequentially, and the tank pressure is lower than the target pressure, 60% if the tank pressure is -50.5 kPa, 70% if the tank pressure is -51.0 kPa. If the internal pressure of the tank is -51.5 kPa, it is 80%. In this case, since the opening degree adjustment of the slow cooling valve 3 is centered on 50%, there is a high possibility that the opening degree is around 50%, and there is no bias toward either a large opening degree or a small opening degree.

  In the case of time D, the slow cooling valve opening is 30% when the tank pressure is the same as the target pressure of 70.0 kPa. If the tank pressure is higher than the target pressure, 20% if the tank pressure is -69.3 kPa, 10% if the tank pressure is -68.6 kPa, 0% if the tank pressure is -67.9 kPa or less, When the internal pressure is lower than the target pressure, the tank pressure is 40% if the tank pressure is -70.7 kPa, 50% if the tank pressure is -71.4 kPa, and 60% if the tank pressure is -72.1 kPa. The internal pressure is set to 100% at -74.9 kPa or higher. If it sets in this way, possibility that the opening degree of the slow cooling valve 3 will be about 30% becomes high at this time, and the opening degree of the slow cooling valve 3 becomes small.

  In the case of time E, the slow cooling valve opening is 10% when the tank pressure is the same as the target pressure of 90.0 kPa. When the tank pressure is higher than the target pressure, 0% if the tank pressure is -89.1 kPa or less. When the tank pressure is lower than the target pressure, 20% if the tank pressure is -90.9 kPa. If the pressure is -91.8 kPa, 30%, and if the pressure in the tank is -92.7 kPa, 40%, the pressure in the tank is -98.1 kPa or more and 100%. If set in this way, the opening degree of the slow cooling valve 3 is likely to be around 10% at this time, and the opening degree of the slow cooling valve 3 becomes smaller than in the case of time D.

  The opening of the slow cooling valve 3 with respect to the target pressure is set to close to full opening when the vacuum is low, and is shifted to the full closing direction as the vacuum becomes high, so that the slow cooling valve 3 is close to full opening when starting cooling. After that, the opening gradually decreases. When the pressure is reduced and the vacuum is increased, the opening degree of the slow cooling valve 3 is reduced, so that the amount of air entering from the slow cooling valve 3 is reduced. The opening degree of the slow cooling valve 3 is increased at the initial stage of the cooling operation, and the opening degree of 3 is decreased as the cooling operation proceeds because the opening degree of the slow cooling valve 3 becomes lower than the target pressure at the initial stage of the cooling operation. This is because bumping tends to occur in the object 7 to be cooled, and conversely, at the end of the cooling operation, it takes time to drop to the target pressure.

  When the degree of vacuum at the initial stage of the cooling operation is low, when the air is discharged by the vacuum generator 1, the air in the cooling tank 2 is rapidly discharged, so the pressure drop rate in the cooling tank increases, There was a case where bumping occurred in an object to be cooled due to an excessive pressure drop. In this case, the amount of air entering the vacuum pipe 9 through the slow cooling valve 3 is increased by increasing the opening degree of the slow cooling valve 3. If the amount of air from the slow cooling valve 3 occupying the suction amount of the vacuum generator 1 increases, the amount of air sucked from the cooling bath 2 decreases, so the pressure drop rate in the cooling bath 2 is suppressed. Conversely, when the degree of vacuum at the end of the cooling operation is high, even if the vacuum generator 1 operates in the same manner, the amount of air discharged from the cooling tank 2 is reduced, so the pressure drop rate in the cooling tank is small. Thus, the cooling time may become longer due to the gradual decompression. In this case, the amount of air entering the vacuum pipe 9 through the slow cooling valve 3 is reduced by reducing the opening degree of the slow cooling valve 3. If the amount of air from the slow cooling valve 3 decreases, the amount of air sucked from the cooling tank 2 increases in the vacuum generator 1, and thus the pressure drop rate in the cooling tank 2 increases. As the cooling operation progresses, the opening time of the slow cooling valve 3 is adjusted so that the amount of air for slow cooling gradually decreases, thereby shortening the operation time while preventing the occurrence of bumping. it can.

  Moreover, since the inside of the cooling tank 2 is a high vacuum at the time of completion | finish of cooling operation, and the to-be-cooled object 7 cannot be taken out from the inside of the cooling tank 2, it is necessary to perform the process of vacuum release. In the case of releasing the vacuum, air is introduced into the cooling tank 2 by opening the air intake valve 8. Also in this case, when a problem occurs when the pressure changes abruptly, the gradual return for gradually releasing the vacuum is performed. Also in the case of performing gradual return, the opening of the air intake valve 8 is set to be small when the vacuum is high, and the opening is increased as the process proceeds and the degree of vacuum decreases. In this case, it is possible to prevent the pressure fluctuation in the cooling tank from increasing by reducing the opening of the air intake valve 8 at high vacuum, and by increasing the opening of the air intake valve 8 at low vacuum. It is possible to prevent the return pressure in the cooling tank from being delayed.

  The present invention is not limited to the embodiments described above, and many modifications can be made by those having ordinary knowledge in the art within the technical idea of the present invention.

1 Vacuum generator
2 Cooling tank
3 Slow cooling valve 4 Slow cooling pipe 5 Pressure detection device 6 Operation control device 7 Object to be cooled 8 Air intake valve 9 Vacuum piping

Claims (2)

A vacuum cooling device having a cooling tank for storing the object to be cooled and a vacuum generator for discharging the air in the cooling tank, and cooling the object to be cooled stored in the cooling tank by evacuating the inside of the cooling tank In addition, a slow cooling pipe having a slow cooling valve in the middle and an operation control device for controlling the operation of the vacuum cooling device are provided, and the operation control device adjusts the opening of the slow cooling valve during vacuum cooling , The tank pressure detected by the pressure detection device that detects the pressure in the cooling tank during the vacuum cooling operation, allowing the slow cooling operation to reduce the pressure reduction rate by introducing the air for slow cooling through the cold valve. When the elapsed time to compare the target pressure that has been set corresponding, in a vacuum cooling device intracisternal pressure is so as to adjust the opening degree of the slow cooling valve so as to approach the target pressure, the operation controller The tank pressure is the same as the target pressure. The median opening, which is the slow cooling valve opening, is set to a large opening at the beginning of the cooling operation, and is set to become a small opening as the cooling operation proceeds. In the initial stage of the cooling operation, the range in which the opening can be expanded from the median opening is reduced and the opening reduction width is increased, and the opening opening reduction width from the median is increased as the cooling operation proceeds. The vacuum cooling device is characterized in that the width of the opening can be increased by decreasing the angle . In the vacuum cooling device according to claim 1, the opening degree of the air intake valve is adjusted so that the target pressure set corresponding to the elapsed time is obtained even at the time of return after completion of the vacuum cooling, When the degree of vacuum in the cooling tank is high, the opening degree of the air intake valve is made small, and as the degree of vacuum in the cooling tank becomes low as the return pressure operation proceeds, the opening degree of the air intake valve becomes A vacuum cooling device that is set to increase in size.

Images