JP2013117354A - Temperature maintenance equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide temperature maintenance equipment which is constituted by assembling components such as a commercially-produced compressor, satisfies a client's specification and makes compatible both the reduction of power consumption and fine temperature control.SOLUTION: The temperature maintenance equipment 1 includes: a compressor 8 discharging a refrigerant while stopping discharging operation associated with a pressure drop of the returned evaporated refrigerant; a refrigerant circulation path 2 for circulating the refrigerant discharged from the compressor 8; a heat exchanger 6 for exchanging the heat of the refrigerant; and a buffer tank 9 provided along a route in the middle of the refrigerant circulation path 2 from the heat exchanger 6 to the compressor 8 where the buffer tank 9 temporarily receives the evaporated refrigerant generated at the heat exchanger.

Description

  The present invention relates to a temperature maintenance facility that needs to maintain a temperature in a certain range, such as a refrigerator compartment, a freezer compartment, and a temperature-controlled room.

  Equipment such as refrigerator rooms, freezer rooms and temperature-controlled rooms are used in various ways in food factories, precision instrument factories, chemical improvement, research laboratories and other offices. In these establishments, it is necessary to store raw materials, parts, products, etc. under certain temperature conditions, and to perform production and experiments using them. For this reason, facilities, such as a refrigerator compartment, a freezer compartment, and a temperature-controlled room, maintain the inside at predetermined temperature using the compressor which circulates a refrigerant | coolant. In particular, a technique for maintaining (that is, cooling) a temperature lower than a general room temperature or an outside air temperature (that is, cooling) is a very delicate technique and requires various elemental techniques and a combination thereof.

  Here, there are provided devices such as a so-called refrigerator, freezer, and thermostatic chamber integrated with a compressor, a compressor control device, a refrigerant circulation path, and a heat exchanger that performs indoor temperature exchange in the refrigerant circulation. These devices are manufactured and sold with all necessary elements, and the purchaser need only install them as they are. Such a device that only needs to be installed in an integrated type is not so high in accuracy required for temperature control as long as it can maintain a temperature within a certain range. For this reason, the integrated device is used for small-scale and low-precision refrigeration and freezing.

  On the other hand, there are a refrigerator room, a freezer room, and a temperature-controlled room as facilities to be designed and constructed according to customer requirements. For example, in a business establishment, there are specifications and conditions such as a predetermined area, a predetermined volume, an object, and a temperature to be maintained, and it is designed by combining units and elements necessary for constructing a refrigerator compartment or a freezer compartment. There are refrigerator rooms, freezer rooms, and temperature-controlled rooms. Demand for such facilities as refrigerated rooms and freezer rooms is increasing with the diversification and sophistication of business establishments.

  In particular, as the precision of raw materials and parts stored and used in business establishments has improved, the level of demand for refrigerated rooms and freezer rooms to be constructed is increasing year by year. For this reason, the request | requirement with respect to the temperature conditions with respect to the refrigerator compartment and freezer compartment to be constructed is also increasing. For example, the required temperature for the set temperature and the temperature range is becoming severe as the set temperature in the refrigerator compartment is 5 ° C. and the temperature range is 1 ° C. up and down.

  Here, refrigeration rooms and freezer rooms that are constructed according to customer requirements are based on commercially available compressors, and contractors design refrigerant circulation paths, refrigerator rooms, heat exchangers, control devices, etc. Then, the final refrigerator compartment and freezer compartment are installed in combination with the compressor. In other words, the contractor satisfies the customer's request by improving and improving the refrigerant circulation path, the refrigerator compartment, the heat exchanger, the control device, and the like. The demand for temperature conditions is also realized by special design and construction of these elements and units. A compressor discharges a refrigerant | coolant to a circulation path, circulates a refrigerant | coolant, and cools the refrigerator compartment and freezer compartment used as temperature maintenance object.

  At this time, a commercially available compressor often has a mechanism for stopping its operation when the pressure of the vaporized refrigerant to be refluxed is weakened. The state in which the pressure of the vaporized refrigerant to be refluxed is weak is a state in which a predetermined target temperature has been reached, and it is not necessary to further strengthen the circulation of the refrigerant. In such a state, the compressor stops its operation to reduce power consumption. A technique for constructing a temperature maintaining device on the premise that such a commercially available compressor is used has also been proposed (see, for example, Patent Documents 1 and 2).

Japanese Patent Laid-Open No. 11-108475 JP 2011-106755 A

  When a compressor that stops its operation when the pressure of the refluxed vaporized refrigerant decreases is used in a temperature maintenance facility, it becomes difficult to control the temperature of the temperature maintenance facility as the compressor stops operating. There's a problem. In a temperature maintenance facility that uses a compressor that circulates refrigerant, the temperature is controlled by the amount of refrigerant that circulates, but if the pressure of vaporized refrigerant that circulates drops and the operation of the compressor stops, It becomes difficult to control the amount of refrigerant to be performed. In particular, in a temperature maintenance facility that requires delicate temperature control, it is extremely disadvantageous that the compressor stops at the timing of delicate temperature control. The compressor stops the operation when the pressure of the vaporized refrigerant to be recirculated decreases.When the pressure of the vaporized refrigerant decreases, the compressor is often near the target temperature in the temperature maintenance facility, and is most sensitive in temperature control. This is because a stop is required at a timing that requires precise control.

  Patent Document 1 discloses a refrigerator including a refrigerant gas tank that stores refrigerant gas. This refrigerant gas tank discloses that the refrigerant gas is stored in the refrigerant circulation path, but does not disclose or mention the relevance to the operation of the compressor. Moreover, the relation with the operation stop of the compressor is not disclosed. For this reason, patent document 1 does not fully disclose solving the difficulty of temperature control due to the pressure drop of the vaporized refrigerant recirculated by the compressor.

  Patent Document 2 discloses a technique of dividing a main pressure and a secondary pressure using a main tank and a buffer tank when circulating a refrigerant. By dividing the refrigerant tank into a plurality of parts, the cooling effect can be improved in that pressure division in the refrigerant circulation can be performed, but there is a problem that it is not possible to cope with the operation stop of the compressor.

  As described above, in the prior art, it has been difficult to achieve both reduction in power consumption of the temperature maintenance facility and precise temperature control. In particular, when using a compressor that stops its operation when the pressure of the vaporized refrigerant that circulates in order to reduce power consumption, a refrigerator of the prior art, etc., uses a reduction in power consumption by stopping the compressor. There was a problem that the temperature could not be controlled.

  On the other hand, it is often required to construct a temperature maintenance facility using a commercially available compressor or other member. However, the commercially available compressor uses a pressure of the vaporized refrigerant to be recirculated for the purpose of reducing power consumption. When the value decreases, the operation is often stopped. It is impractical to modify the compressor when constructing the temperature maintenance equipment in terms of quality maintenance, reliability, cost, man-hours, and the like. For this reason, on the premise that the compressor which stops operation | movement according to the pressure fall of a vaporization refrigerant | coolant is used, the temperature maintenance installation which balances reduction of power consumption and precise temperature control was calculated | required. In particular, when the operation of the compressor is frequently stopped, problems such as power consumption, noise, and burden associated with resuming the operation of the compressor occur.

  In addition, in a temperature maintenance facility constructed by combining elements such as a commercially available compressor, the temperature maintenance room of the temperature maintenance facility is often incorporated in a part of a building such as a warehouse or a factory. In such a case, repairing the entire temperature maintenance facility based on the failure or life of the compressor, which is only one element of the temperature maintenance facility, has a high cost demerit. Of course, there is a high demerit that the life of the entire temperature maintenance facility is based on the life of the compressor.

  In view of the above-mentioned problems, the present invention is a temperature maintenance facility that satisfies the specifications of a customer who installs and combines elements such as commercially available compressors, and maintains temperature that achieves both reduction of power consumption and precise temperature control. The purpose is to provide equipment.

  In view of the above-described problems, the temperature maintenance facility according to the present invention includes a compressor that stops the sending operation as the pressure of the vaporized refrigerant that flows and recirculates the refrigerant, and a refrigerant circulation path that circulates the refrigerant sent from the compressor. And a heat exchanger that performs heat exchange of the refrigerant, and a buffer tank provided in a path from the heat exchanger to the compressor in the refrigerant circulation path, and the buffer tank temporarily stores vaporized refrigerant generated in the heat exchanger .

  The temperature maintenance facility of the present invention includes a buffer tank that temporarily stores the vaporized refrigerant that recirculates to the compressor, so that the pressure drop in the compressor itself can be prevented to the limit, and the operation of the compressor can be stopped as much as possible. Is prevented. As a result, it is possible to prevent an increase in power consumption and a burden on the compressor (and a decrease in the life associated therewith) based on frequent stoppage and resumption of operation of the compressor. For this reason, the temperature maintenance facility can reduce the maintenance cost of the temperature maintenance facility as a whole due to the failure or life of the compressor. Of course, it is possible to reduce the necessity of repairing the entire temperature maintenance facility by the compressor, which is only one element of the temperature maintenance facility, and the short life.

  Moreover, the refrigerant circulation is continued to the limit by preventing the operation of the compressor from being stopped as much as possible. In particular, by maintaining the operation of the compressor, the temperature maintenance facility can perform temperature control by controlling the circulation of the refrigerant even during a period in which the pressure of the vaporized refrigerant that normally returns to the compressor decreases. . As a result, the temperature maintenance facility can realize fine temperature control.

  The temperature maintenance facility of the present invention can achieve both reduction of maintenance cost and longer life of the temperature maintenance facility as a whole while achieving both power consumption and fine temperature control.

  As a result, the temperature maintenance facility of the present invention can realize environmental protection and power saving.

It is a block diagram of the temperature maintenance installation in Embodiment 1 of this invention. It is a graph which shows the pressure change in the compressor in Embodiment 1 of this invention. It is a graph which shows the pressure change of the vaporization refrigerant | coolant which recirculates to the compressor 8 in the case of providing the buffer tank in Embodiment 1 of this invention. It is a front view of the heat exchanger 6 in Embodiment 1 of this invention. It is a block diagram of the buffer tank in Embodiment 1 of this invention. It is a block diagram of the temperature maintenance installation in Embodiment 2 of this invention. It is a graph which shows the temperature control by the temperature maintenance installation in Embodiment 2 of this invention. It is a graph which shows opening and closing of the control valve in Embodiment 2 of this invention. It is a graph explaining control of the control valve in Embodiment 2 of this invention. It is a block diagram of the temperature maintenance installation in Embodiment 2 of this invention. It is a schematic diagram of the temperature maintenance installation in Embodiment 2 of this invention.

  The temperature maintenance facility according to the first aspect of the present invention includes a compressor that stops the delivery operation as the pressure of the vaporized refrigerant that recirculates and recirculates, and a refrigerant circulation that circulates the refrigerant delivered from the compressor. A buffer tank provided in a path from the heat exchanger to the compressor in the refrigerant circulation path, and the buffer tank temporarily stores vaporized refrigerant generated in the heat exchanger To do.

  With this configuration, the temperature maintenance facility can return the vaporized refrigerant to the compressor through the buffer tank. The recirculation of the vaporized refrigerant reduces the frequency of stopping and restarting the compressor.

  In the temperature maintenance facility according to the second aspect of the present invention, in addition to the first aspect, the buffer tank temporarily stores a predetermined amount of vaporized refrigerant that is returned to the compressor and also stores the vaporized refrigerant to be stored. Send to compressor.

  With this configuration, the buffer tank can continue to give vaporized refrigerant to the compressor.

  In the temperature maintenance facility according to the third aspect of the present invention, in addition to the first or second aspect, the predetermined amount is a predetermined pressure value (hereinafter referred to as “stop pressure value”) that causes the delivery operation of the compressor to stop. ”).

  With this configuration, the compressor can reduce the frequency of stopping and restarting.

  In the temperature maintenance facility according to the fourth aspect of the present invention, in addition to any of the first to third aspects of the invention, the refrigerant circulation path sends vaporized refrigerant to the bottom surface of the buffer tank, and the buffer tank contains the vaporization accommodated therein. The refrigerant is sent from the bottom surface of the buffer tank to the compressor.

  With this configuration, the buffer tank can efficiently utilize its capacity.

  In the temperature maintenance facility according to the fifth aspect of the present invention, in addition to any of the first to fourth aspects of the invention, the compressor receives the supply of vaporized refrigerant at a stop pressure value or higher from the buffer tank, Maintain the operation.

  With this configuration, the temperature maintenance facility can reduce power consumption.

  In the temperature maintenance facility according to the sixth aspect of the present invention, in addition to any of the first to fifth aspects of the invention, the buffer tank further includes a plurality of divided areas, depending on the use state of the plurality of areas. The amount of vaporized refrigerant to be accommodated can be changed.

  With this configuration, the setting of the buffer tank can be changed afterwards in accordance with the performance and specifications of the compressor.

  In the temperature maintenance facility according to the seventh aspect of the present invention, in addition to the sixth aspect, each of the plurality of regions is connected to each other by a communication port that can be opened and closed.

  With this configuration, the execution capacity of the buffer tank can be made variable.

  In the temperature maintenance facility according to the eighth aspect of the present invention, in addition to any one of the first to seventh aspects, a control valve for adjusting the amount of refrigerant circulating in the refrigerant circuit, and a control unit for controlling the control valve Is further provided.

  With this configuration, the temperature maintenance facility can maintain the temperature maintenance chamber at the target temperature with higher accuracy.

  In the temperature maintenance facility according to the ninth aspect of the present invention, the controller is configured to change the period from the first temperature that is higher than the target temperature by a predetermined temperature to the second temperature that is lower than the target temperature by a predetermined temperature (hereinafter, “first period”). In the change period from the second temperature to the first temperature (hereinafter referred to as “second period”), the control valve is controlled based on the PID control method.

  With this configuration, the temperature maintenance facility can perform precise temperature control according to the PID method. In particular, the temperature can be maintained finely in combination with the buffer tank.

  In the temperature maintenance facility according to the tenth aspect of the present invention, in addition to the eighth aspect, the control unit controls the control valve based on the PID control method in the first period, and in the second period. Reduce the opening of the control valve.

  With this configuration, the temperature maintenance facility can moderate the temperature change near the target temperature while maintaining the temperature in the temperature maintenance chamber near the target temperature.

  In the temperature maintenance facility according to the eleventh aspect of the present invention, in addition to the tenth aspect, in the first period, the control unit controls the amount of refrigerant passing through the control valve in unit time so as to control the amount of refrigerant. Controls the opening and closing of.

  With this configuration, the temperature maintaining chamber can maintain the temperature maintaining chamber at the target temperature while reducing the burden on the compressor.

  In the temperature maintenance facility according to the twelfth aspect of the present invention, in addition to the tenth or eleventh aspect, the control unit closes the control valve in the second period.

  With this configuration, the temperature maintaining chamber can maintain the temperature maintaining chamber at the target temperature while reducing the burden on the compressor.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  (Embodiment 1)

  Embodiment 1 will be described.

  The outline of the temperature maintenance facility in the first embodiment will be described with reference to FIG. FIG. 1 is a block diagram of a temperature maintenance facility according to Embodiment 1 of the present invention. FIG. 1 shows elements necessary for the temperature maintenance facility 1 and additional elements for convenience of explanation. Not all of the elements shown in FIG. 1 are essential to the invention.

  The temperature maintenance facility 1 is used for facilities where the temperature needs to be maintained at a predetermined target temperature, such as a refrigerator compartment, a freezer compartment, and a temperature-controlled room. In particular, it is used for equipment constructed by combining commercially available compressors and other elements.

  The temperature maintenance facility 1 includes a compressor 8, a refrigerant circulation path 2, a heat exchanger 6, and a buffer tank 9.

  The compressor 8 sends out the refrigerant by a compression operation or a rotation operation and causes the refrigerant to circulate in the refrigerant circulation path 2. That is, the compressor 8 sends out a refrigerant that is a liquid, and receives the reflux of the vaporized refrigerant that is vaporized and refluxed. At this time, it has the characteristic of stopping the delivery operation as the pressure of the vaporized refrigerant returning to itself decreases. For example, when the pressure of the vaporized refrigerant returning to the compressor 8 becomes a predetermined value or less, the compressor 8 stops the refrigerant delivery operation.

  The refrigerant reflux path 2 is connected to both the compressor 8 and the inlet and outlet, and circulates the refrigerant sent out from the compressor 8. The heat exchanger 6 is provided in the temperature maintenance chamber 7 that is a target for maintaining the temperature in the middle of the refrigerant circulation path 2. The heat exchanger 6 performs heat exchange with the refrigerant circulating in the refrigerant circuit 2.

  The buffer tank 9 is provided in a path that reaches the compressor 8 in the middle of the refrigerant circulation path 2. Preferably, it is provided in front of the compressor 8 in the refrigerant circulation path 2. The buffer tank 9 is a vaporized refrigerant that is a vaporized refrigerant generated in the heat exchanger 6 and temporarily stores vaporized refrigerant that recirculates through the refrigerant circuit 2. The buffer tank 9 sends the stored vaporized refrigerant to the compressor 8. Since the buffer tank 9 and the compressor 8 are connected by the refrigerant circulation path 2, the buffer tank 9 sends the vaporized refrigerant to the compressor 8 through the refrigerant circulation path 2. The compressor 8 receives the recirculation of the vaporized refrigerant sent from the buffer tank 9.

    (Overview of operation)

  Next, an outline of the operation of the temperature maintenance facility 1 will be described.

  The compressor 8 sends the refrigerant (liquid refrigerant) in a liquid state to the refrigerant circuit 2 by receiving necessary electric power and control. The refrigerant circulation path 2 circulates the liquid refrigerant sent from the compressor 8 toward the heat exchanger 6. The refrigerant circulation path 2 circulates the entire temperature maintenance facility 1 including the temperature maintenance chamber 7, and circulates the refrigerant (liquid state and vaporized state) throughout the temperature maintenance facility 1.

  The liquid refrigerant that has circulated through the refrigerant circulation path 2 reaches the heat exchanger 6. The heat exchanger 6 is provided in the temperature maintenance chamber 7, and maintains the inside of the temperature maintenance chamber 7 at a predetermined temperature by the heat of vaporization of the liquid refrigerant by heat exchange with the outside air. By the heat exchange in the heat exchanger 6, the liquid refrigerant is vaporized, and vaporized refrigerant is generated. The refrigerant circuit 2 recirculates the vaporized refrigerant first from the heat exchanger 6. For this reason, the refrigerant circulation path 2 conveys the vaporized refrigerant to the buffer tank 9 at the tip of the heat exchanger 6 in the refrigerant circulation flow.

  The buffer tank 9 temporarily stores a predetermined amount of vaporized refrigerant. The vaporized refrigerant generated in the heat exchanger 6 is normally returned to the compressor 8 through the refrigerant circulation path 2 as it is. However, since the buffer tank 9 is provided, It is accommodated in the buffer tank 9. The buffer tank 9 can store a predetermined amount of vaporized refrigerant that is appropriately determined according to the performance and specifications of the temperature maintenance facility 1 and the compressor 8.

  Since the buffer tank 9 has a limit on the amount of vaporized refrigerant that can be temporarily stored, the vaporized refrigerant is sent to the compressor 8 through the refrigerant circuit 2 when the vaporized refrigerant exceeding this limit is received. As shown in FIG. 1, the refrigerant circulation path 2 connects the compressor 8 from the buffer tank 9. The compressor 8 is located downstream of the buffer tank 9 in the refrigerant circulation direction in the refrigerant circulation path 2. As a result, the vaporized refrigerant overflowing the buffer tank 9 returns to the compressor 8. At this time, the buffer tank 9 can store a predetermined amount of the vaporized refrigerant, and then deliver the vaporized refrigerant after it is accommodated, so that the pressure of the vaporized refrigerant to be delivered can be maintained above a certain level. For this reason, the vaporized refrigerant returning to the compressor 8 can maintain a certain pressure or more over a certain time. The buffer tank 9 can maintain the pressure of the vaporized refrigerant returning to the compressor 8 at a certain level or more, so that the compressor 8 does not stop or does not occur frequently. When the number of times the compressor 8 is stopped is small, the number of times the compressor 8 is restarted is also reduced, so that the power consumption in the compressor 8 and the burden on the compressor 8 can be reduced.

(Comparison with conventional technology)
Description will be made based on a comparison between the prior art in which the buffer tank 9 does not exist and the temperature maintenance facility of the present invention in which the buffer tank exists.

  Assume that there is no buffer tank 9 in the temperature maintenance facility 1 as shown in FIG. In this case, heat exchange in the heat exchanger 6 gradually converges (because the temperature maintaining chamber 7 reaches a predetermined target temperature), and the amount of vaporized refrigerant generated decreases, so that the vaporized refrigerant flowing back to the compressor 8 is reduced. The pressure gradually decreases. If the pressure of the vaporized refrigerant returning to the compressor 8 gradually decreases, the compressor 8 stops the operation based on the characteristics. If the operation of the compressor 8 stops, the delivery of the liquid refrigerant from the compressor 8 to the refrigerant circulation path 2 stops, and the heat exchange in the heat exchanger 6 also stops gradually.

  FIG. 2 shows the operation stop of the compressor 8 accompanying the decrease in the pressure of the vaporized refrigerant. FIG. 2 is a graph showing pressure changes in the compressor according to Embodiment 1 of the present invention. In the graph of FIG. 2, the vertical axis represents the pressure of the vaporized refrigerant returning to the compressor 8, and the horizontal axis represents time. While heat exchange in the temperature maintenance chamber 7 is proceeding in the heat exchanger 6, the liquid refrigerant is changed to a vaporized refrigerant, and the pressure of the vaporized refrigerant returning to the compressor 8 is maintained at a predetermined value or higher. However, when the heat exchange in the heat exchanger 6 proceeds and the temperature maintenance chamber 7 approaches the target temperature, the amount of vaporized refrigerant generated decreases, and the pressure of the vaporized refrigerant returning to the compressor 8 gradually decreases. . When the pressure falls below the threshold, the compressor 8 stops its operation. When the compressor 8 stops its operation, the refrigerant is not sent out, so that the pressure of the vaporized refrigerant to be recirculated further decreases.

  On the other hand, most of the temperature maintenance chamber 7 has a temperature measurement unit for measuring the temperature, and the heat exchange by the heat exchanger 6 is gradually stopped, so that the temperature inside the temperature maintenance chamber 7 is increased. When the temperature gradually deviates from the target temperature, the operation of the compressor 8 is resumed (resumed by a control device or the like that controls the operation of the compressor 8). By restarting, heat exchange is again performed in the heat exchanger 6, the pressure of the vaporized refrigerant increases, and the refrigerant is returned to the compressor 8.

  Thus, in the case of the prior art in which the buffer tank 9 is not provided, the compressor 8 frequently stops and the compressor 8 frequently restarts. The frequent restart of operation results in an increase in power consumption in the compressor 8 (since the compressor 8 consumes the most power at the start of operation), causing a burden on the compressor 8. A large burden has a problem of increasing the maintenance cost and shortening the life of the temperature maintenance facility 1 as a whole.

(If there is a buffer tank)
On the other hand, in the case of the temperature maintenance facility 1 of the present invention as shown in FIG. 1, a buffer tank 9 is provided upstream of the compressor 8.

  When the buffer tank 9 is provided, the vaporized refrigerant stored in the buffer tank 9 maintains the pressure of the vaporized refrigerant returning to the compressor 8 at a predetermined value or higher. FIG. 3 is a graph showing the pressure change of the vaporized refrigerant returning to the compressor 8 when the buffer tank according to Embodiment 1 of the present invention is provided.

  Similar to the graph of FIG. 2, the pressure of the vaporized refrigerant returning to the compressor 8 gradually decreases as the heat exchange in the heat exchanger 6 gradually proceeds. However, unlike the graph of FIG. 2, since the pressure by the buffer tank 9 is maintained, the pressure of the vaporized refrigerant exceeding a certain value is maintained in the compressor 8. In FIG. 3, buffer tank pressure is applied. The pressure of the vaporized refrigerant returning to the compressor 8 is less likely to be less than or equal to the threshold value. As a result, the compressor 8 can continue the operation without stopping the operation.

  Of course, since the buffer tank 9 only temporarily stores a predetermined amount of vaporized refrigerant, the pressure gradually decreases. However, if the temperature of the temperature maintenance chamber 7 begins to deviate from the target temperature, the operation speed of the compressor 8 is increased by the action of the control device or the like (the liquid refrigerant is sent out at a higher speed or more), and the vaporized refrigerant that is recirculated again The pressure increases. The graph of FIG. 3 also shows an increase in compressor operation.

As is apparent from the graph of FIG. 3, the temperature maintenance facility 1 according to the first embodiment includes the buffer tank 9, so that the frequency of operation stop and operation restart of the compressor 8 can be reduced. For this reason, the power consumption at the start of the operation of the compressor 8 can be reduced, and the power consumption of the entire temperature maintenance facility 1 can be reduced. In addition, the burden on the compressor 8 can be reduced by reducing the frequency of stopping and restarting the operation of the compressor 8. As a result, the maintenance and repair costs of the temperature maintenance facility 1 due to the failure and life of the compressor 8 can also be reduced. Of course, the fact that the frequency of stopping and restarting the compressor 8 can be reduced also brings about the merit that the temperature control of the temperature maintaining chamber 7 can be made more precise. The temperature maintenance facility 1 according to the first embodiment is suitably applied to recent refrigeration equipment, refrigeration equipment, and thermostatic equipment that are highly required to maintain the target temperature.
As described above, the temperature maintenance facility 1 according to the first embodiment can achieve a reduction in power consumption, ease of maintenance, and precise temperature control in a balanced manner.

(Details of each part)
Next, the detail of each part is demonstrated.

(Compressor)
The compressor 8 is an element having a function of circulating the refrigerant. A compressor that is generally used or commercially available is used. The compressor 8 has a condensing function for liquefying the vaporized refrigerant and a rotating function for delivering the liquid refrigerant. The compressor 8 may further include a condenser and a rotating machine. The condenser condenses and liquefies the refluxed vaporized refrigerant. By being liquefied, the compressor 8 can again deliver the liquid refrigerant to the refrigerant circulation path 2. The rotating machine realizes the delivery (finally circulation) of the refrigerant by the rotation function.

  The compressor 8 may send out the refrigerant by various mechanisms. In order to send out the refrigerant, it has a rotating operation, and the delivery amount can be controlled by this rotational speed. Commercially available compressors have various characteristics, but often control rotation to reduce power consumption. In particular, the compressor often stops or restarts its rotation depending on the pressure of the refluxing gaseous refrigerant. For example, the compressor stops rotating when the pressure of the refluxing gaseous refrigerant decreases. On the other hand, when the pressure of the refluxing gaseous refrigerant increases, the compressor resumes rotation. Or a compressor restarts rotation by forced control. The compressor 8 in Embodiment 1 uses a commercially available compressor having such characteristics.

  In the temperature maintenance facility 1 according to the first embodiment, since the buffer tank 9 is provided in the previous stage of the compressor 8 (may be immediately before or other elements may be interposed therebetween), the compressor 8 The vaporized refrigerant from the buffer tank 9 recirculates. For this reason, the pressure of the vaporized refrigerant received by the compressor 8 becomes the pressure of the vaporized refrigerant received from the buffer tank 9.

  In addition, since a commercially available compressor is used as the compressor 8, it is not necessary to improve a compressor and the manufacturing cost of the temperature maintenance equipment 1 can be reduced.

(Refrigerant circuit)
The refrigerant circulation path 2 is connected to the compressor 8 and circulates the refrigerant sent from the compressor 8. The refrigerant circuit 2 circulates the liquid refrigerant to the heat exchanger 6. The heat exchanger 6 reduces the temperature of the temperature maintenance chamber 7 using the heat of vaporization of the refrigerant. That is, the refrigerant is vaporized by the heat exchanger 6. The refrigerant circulation path 2 circulates the vaporized refrigerant and returns it to the compressor 8. Thus, the refrigerant circulation path 2 circulates the liquid refrigerant and the gaseous refrigerant. For this reason, the refrigerant circulation path 2 is connected to the compressor 8 and the heat exchanger 6.

  The refrigerant circulation path 2 may be formed of a metal pipe, a resin pipe, or an alloy pipe, but a metal pipe is often used in consideration of durability, strength, and the like. The refrigerant circulation path 2 is constructed together with the temperature maintenance chamber 7. Since the refrigerant circulation path 2 often depends on the structure of the factory or business place where the refrigeration equipment or refrigeration equipment is constructed, it may be arranged according to the structure of the factory or business place. Alternatively, an already constructed pipe line may be used as the refrigerant circulation path 2.

(Heat exchanger)
The heat exchanger 6 uses the refrigerant circulating in the refrigerant circulation path 2 to maintain the temperature inside the temperature maintenance chamber 7 near the target temperature. The heat exchanger 6 is installed inside the temperature maintenance chamber 7 and reduces the ambient temperature by the heat of vaporization of the circulating refrigerant. For the heat exchanger 6, various known members may be used. For example, a member in which the refrigerant circulation path 2 is connected to a metal plate material having high thermal conductivity and the refrigerant circulates inside the plate material may be used.

  FIG. 4 is a front view of the heat exchanger 6 according to Embodiment 1 of the present invention. FIG. 4 shows an example of the heat exchanger 6. The heat exchanger 6 includes a plate material 61 and an internal circulation path 62 inside the plate material 61. The internal circulation path 62 is indicated by a broken line. The internal circulation path 62 is connected to the refrigerant circulation path 2, and the refrigerant that has circulated through the refrigerant circulation path 2 circulates inside the internal circulation path 62. At this time, the refrigerant is input from the inlet 21 and is output from the outlet 22. Since the internal circulation path 62 is provided in a state of circling the inside of the plate member 61, the area in which the refrigerant in the heat exchanger 6 is in thermal contact with the outside becomes large. Due to this large contact area, the heat exchanger 6 vaporizes the refrigerant and lowers the ambient temperature.

  The heat exchanger 6 may be provided inside the temperature maintenance chamber 7 as shown in FIG. 1, but may be integrated with the wall surface of the temperature maintenance chamber 7 or provided outside the temperature maintenance chamber 7 and indirectly. Alternatively, the inside of the temperature maintenance chamber 7 may be cooled.

  The heat exchanger 6 may have a blower fan or the like. The blower fan sends wind to the surface of the heat exchanger 6, and the wind causes the cooling air from the heat exchanger 6 to spread throughout the temperature maintenance chamber 7 throughout the temperature maintenance chamber 7. As a result, the cooling effect in the temperature maintaining chamber 7 is increased, and the cooling capacity of the temperature maintaining chamber 7 by the refrigerant circulation is increased. When such a blower fan is provided in the heat exchanger 6, the cooled air circulates inside the temperature maintenance chamber 7. For this reason, the cool air sent out from the heat exchanger 6 cools while circulating the entire temperature maintenance chamber 7. The cold air returns to the heat exchanger 6 again according to the air flow generated by the blower fan while circulating inside the temperature maintenance chamber 7. That is, the cold air circulates so as to be sucked into the heat exchanger 6.

  The heat exchanger 6 maintains the inside of the temperature maintenance chamber 7 near the target temperature by the action of the circulating refrigerant. The heat exchanger 6 may be integrated with the refrigerant circulation path 2 or may be a separate body.

(Temperature maintenance room)
The temperature maintenance chamber 7 is a space in which the internal temperature is maintained near a predetermined target temperature in the temperature maintenance facility 1 (and the compressor 8 and the heat exchanger 6 that perform an actual cooling function). The temperature maintenance room 7 is an element that becomes a refrigeration room such as a refrigeration facility installed and installed in a factory or business place. For this reason, the temperature maintenance chamber 7 is at least one of a refrigerator compartment, a freezer compartment, and a temperature-controlled room. It is a space constructed for any of these purposes.

  The temperature maintenance room 7 may be a newly constructed space (equipment) in accordance with the construction of refrigeration equipment or refrigeration equipment, or the space already provided in a factory or business place may be used. good. The temperature maintenance facility 1 is combined with the temperature maintenance chamber 7 to realize construction of a refrigeration facility or a refrigeration facility.

  Since the temperature maintaining chamber 7 needs to be cooled or heated, the temperature maintaining chamber 7 includes the heat exchanger 6 described above, and at least a part of the refrigerant circulation path 2 is provided as necessary. The heat exchanger 6 maintains the predetermined target temperature by cooling the temperature maintaining chamber 7 or maintains the predetermined target temperature by heating the temperature maintaining chamber 7 depending on the characteristics of the refrigerant.

  Since the temperature maintenance chamber 7 is constructed and maintained at a target temperature in a factory or business place, it is preferable that the temperature maintenance chamber 7 is formed of a material having high heat insulation. For example, it is appropriate to be surrounded by concrete. Of course, it may be surrounded by a metal plate.

  Whether the temperature maintenance room 7 is used as a refrigerator room, a freezer room, or a temperature-controlled room may be determined by the structure and material of the temperature maintenance room 7 itself, and the structure and material of the temperature maintenance room 7 as equipment are as follows: In common, depending on the characteristics of the compressor 8 and the temperature maintenance facility 1, it may be determined whether the temperature maintenance chamber 7 is used as a refrigerator compartment, a freezer compartment, or a temperature-controlled room. That is, even if it is the same temperature maintenance room 7, the temperature maintenance room 7 is set as one of a refrigerator compartment, a freezer compartment, and a temperature-controlled room by the target temperature (value or characteristic) by the temperature maintenance equipment 1 or the element contained in this. It can also be used. It is also useful for the entire facility that the temperature maintenance chamber 7 has strength and durability in addition to heat insulation.

(Buffer tank)
As described above, the buffer tank 9 is provided upstream of the compressor 8 (another element may be interposed between the buffer tank 9 and the compressor 8). The buffer tank 9 temporarily stores a predetermined amount of vaporized refrigerant that flows back to the compressor 8. Further, the stored vaporized refrigerant is sent to the compressor 8. At this time, the predetermined amount of the vaporized refrigerant accommodated in the buffer tank 9 may be determined by the entire temperature maintenance facility 1 or individual elements. In particular, it may be determined based on the specifications of the compressor 8. For example, the compressor 8 may have a predetermined amount that causes a pressure value equal to or higher than a pressure value at which the refrigerant delivery operation is stopped (hereinafter referred to as “stop pressure value”).

  Since the buffer tank 9 has a predetermined amount that generates a pressure equal to or higher than the stop pressure value, the vaporized refrigerant from the buffer tank 9 even when the amount of vaporized refrigerant generated decreases as the temperature maintaining chamber 7 approaches the target temperature. Thus, the compressor 8 does not stop the operation. Of course, if the vaporized refrigerant returning from the heat exchanger 6 to the buffer tank 9 decreases, the vaporized refrigerant returning to the compressor 8 may decrease regardless of the predetermined capacity of the buffer tank 9. In this case, the pressure of the vaporized refrigerant returning from the buffer tank 9 is lower than the stop pressure value. However, even in such a case, it is possible to reduce the frequency of stopping the compressor 8 when it is equal to or lower than the stop pressure value.

  As described above, the buffer tank 9 can store a predetermined amount of the refrigerant, so that the pressure on the compressor 8 can be maintained for a predetermined time. By maintaining this pressure, the frequency of stopping and restarting the compressor 8 can be reduced, and the movable life can be extended while reducing the power consumption of the entire temperature maintenance facility.

  In the buffer tank 9, it is preferable that the refrigerant circulation path 2 be input from the bottom surface of the buffer tank 9 and output from the bottom surface. That is, it is preferable that the refrigerant circulation path 2 feeds the vaporized refrigerant from the bottom surface of the buffer tank 9 and the refrigerant sent from the buffer tank 9 outputs the refrigerant circulation path 2 from the bottom surface of the buffer tank 9. By inputting the refrigerant from the bottom surface and outputting from the bottom surface, the refrigerant corresponding to the capacity of the buffer tank 9 is accommodated in the buffer tank 9.

  In FIG. 1, the refrigerant circulation path 2 is configured to send vaporized refrigerant from the bottom surface of the buffer tank 9 and to send vaporized refrigerant from the bottom surface of the buffer tank 9. When the vaporized refrigerant is input from the bottom surface of the buffer tank 9 and the vaporized refrigerant is output from the bottom surface of the buffer tank 9, all the predetermined amount provided in the buffer tank 9 is used for accommodating the vaporized refrigerant, and the use efficiency is increased.

  The compressor 8 receives its supply of vaporized refrigerant that recirculates from the buffer tank 9 through the refrigerant circulation path 2, and maintains its own operation (while a pressure higher than the stop pressure value is received). As a result, the operation of the compressor 8 is maintained, and the frequency of stop and restart is reduced.

  It is also preferable that the buffer tank 9 has a plurality of divided areas. FIG. 5 is a block diagram of the buffer tank according to Embodiment 1 of the present invention. FIG. 5 shows a mode in which the inside of the buffer tank 9 is divided into a plurality of regions 91. The plurality of areas 91 are originally inside the buffer tank 9 and are not visible from the outside, but are shown by broken lines for the sake of easy viewing.

  Although the buffer tank 9 has a predetermined amount of capacity, the capacity of the buffer tank 9 may vary depending on the specifications of the temperature maintenance facility 1, the specifications of the compressor 8, and the stop pressure value of the compressor 8. It is disadvantageous in terms of cost to prepare a plurality of buffer tanks 9 having different accommodating capacities according to these specifications and stop pressure values. In this state, when the interior of the buffer tank 9 is divided into a plurality of regions 91, the capacity of the buffer tank 9 can be easily changed according to these specifications and the stop pressure value.

  For example, in FIG. 5, the buffer tank 9 is divided into four regions 91A to 91D. For example, when only the region 91A is used, the capacity of the buffer tank 91 is naturally small. When it is desired to reduce the capacity of the buffer tank 9, only the region 91 </ b> A may be configured to store the vaporized refrigerant. Alternatively, the capacity of the buffer tank 9 can be made variable by using two areas 91A and 91B or using three areas 91.

  Each of the plurality of regions 91 is also preferably connected to each other by a communication port 92 that can be opened and closed. In the buffer tank 9 shown in FIG. 5, the regions 91 </ b> A to 91 </ b> D are connected to each other by communication ports 92 </ b> A to 92 </ b> D. Since each of the communication ports 92 </ b> A to 92 </ b> D can be opened and closed, the number of the regions 91 to be used is reduced by being closed. Or the number of the area | regions 91 used increases by releasing. Since the communication ports 92 </ b> A to 92 </ b> D can be opened and closed afterwards, it is possible to set which of the plurality of regions 91 </ b> A to 91 </ b> D (how many) is used later. As a result, the capacity of the buffer tank 9 can be changed flexibly.

  As described above, the temperature maintenance facility 1 in the first embodiment can reduce the frequency of stopping and restarting the compressor 8 by the action of the buffer tank 9. As a result, it is possible to extend the service life and reduce the maintenance cost while reducing the power consumption of the entire temperature maintenance facility 1.

  (Embodiment 2)

  Next, a second embodiment will be described. In the second embodiment, a temperature maintenance facility capable of reducing power consumption in combination with the function of the buffer tank 9 by controlling the amount of refrigerant circulating in the refrigerant circulation path 2 will be described.

  FIG. 6 is a block diagram of the temperature maintenance facility according to the second embodiment of the present invention. The temperature maintenance facility 1 shown in FIG. 6 controls the regulation valve 3 that regulates the amount of refrigerant circulating in the refrigerant circulation path 2 and the regulation valve 3 as compared with the temperature maintenance facility 1 described in the first embodiment. A control unit 5 is further provided. Moreover, the temperature detection part 4 which measures the temperature inside the temperature maintenance chamber 7 required for control of the control part 5 is also provided.

  The temperature maintenance facility 1 adjusts the amount of refrigerant circulating through the refrigerant circulation path 2 by the adjustment valve 3. By adjusting the amount of refrigerant, the temperature maintenance facility 1 can maintain the temperature of the temperature maintenance chamber 7 near a predetermined target temperature. Further, the control unit 5 can control the amount of refrigerant circulating in the refrigerant circulation path 2 by controlling the degree of opening of the control valve 3. By this control, the degree of cooling (or warming) by the refrigerant is controlled. At this time, the control valve 3 and the control unit 5 control the amount of refrigerant circulating in the refrigerant circulation path 2, and do not control the rotation speed and capacity of the compressor 8. For this reason, it is not necessary to modify the compressor 8 or the like.

  The maintenance of the vicinity of the target temperature in the temperature maintenance chamber 7 by the elements added in FIG. 6 will be described. The temperature maintenance facility 1 tries to maintain the temperature of the temperature maintenance chamber 7 near a predetermined target temperature. The vicinity of the target temperature does not mean that the temperature is strictly limited to the target temperature and does not mean that the temperature is within a certain range before and after the target temperature.

  The temperature detection unit 4 measures the temperature of the temperature maintenance chamber 7 in which the temperature is maintained near a predetermined target temperature by the temperature maintenance facility 1. That is, the temperature detection unit 4 can check the control by the control unit 5 by detecting the temperature state of the target controlled by the temperature maintenance facility 1. The temperature detection unit 4 outputs the detected temperature information to the control unit 5.

  The control unit 5 controls the adjustment valve 3. The amount of refrigerant circulating in the refrigerant circulation path 2 is controlled by controlling the degree of opening of the control valve 3 and the like. By controlling the amount of refrigerant, the temperature of the temperature maintenance chamber 7 by the heat exchanger 6 is controlled near the target temperature. The control unit 5 can control the temperature of the temperature maintaining chamber 7 by controlling the control valve 3 by various methods.

  For example, the control unit 5 includes a change period (hereinafter referred to as “first period”) from a first temperature that is higher than the target temperature by a predetermined temperature to a second temperature that is lower than the target temperature by a predetermined temperature, and from the second temperature to the second temperature. In the change period up to one temperature (hereinafter referred to as “second period”), the control unit 5 controls the control valve 3 based on PID control. The PID control method may be a generally known PID control method or the PID control method described in this specification. In short, the control unit 5 may control the control valve 3 using the PID control method in both cases in which the temperature decreases and in the temperature increase period.

  Alternatively, the control unit 5 may control the control valve 3 by the PID control method in the first period, and control the control valve 3 by OFF control that closes the control valve 3 in the second period. May be.

  Or the control part 5 adjusts the control valve 3 based on PID control in a 1st period. On the other hand, in the second period, the control unit 5 may control the control valve 3 so as to reduce the open state of the control valve 3.

  PID control is a mechanism known as proportional-integral-derivative control, and the control unit 5 controls the degree of opening of the control valve 3 using this PID control in the first period. When performing PID control, the degree of temperature change is moderated, unlike the simple opening of the control valve 3. The temperature maintenance chamber 7 is often maintained at a temperature lower than the outside air temperature as a target temperature (and vice versa of course). The first period is a temperature change period of the temperature maintenance chamber 7 when the target temperature is aimed from a state higher than the target temperature. At this time, if the circulation of the refrigerant stops when the target temperature is reached, the heat exchange in the heat exchanger 6 ends, and the temperature of the temperature maintenance chamber 7 immediately exceeds the target temperature. For this reason, it is preferable that the refrigerant circulates and heat exchange (cooling) by the heat exchanger 6 is maintained up to a second temperature lower than the target temperature. The control unit 5 controls the temperature of the temperature maintenance chamber 7 as shown in the graph shown in FIG. FIG. 7 is a graph showing temperature control by the temperature maintenance facility in Embodiment 2 of the present invention.

  The control unit 5 opens the control valve 3 and starts refrigerant circulation at a first temperature higher than the target temperature (a state in which the refrigerant needs to be circulated to lower the temperature of the temperature maintenance chamber 7). When the refrigerant circulation is performed, heat exchange by the heat exchanger 6 is performed and the temperature of the temperature maintaining chamber 7 is lowered. In the graph of FIG. 7, the temperature decreases in the first period. This state continues until the second temperature lower than the target temperature. In the first period, the control unit 5 controls the control valve 3 by PID control. Since the PID control uses proportional integral differentiation including a predetermined correction rather than simply opening the control valve 3, the temperature change becomes gentle during the control period by the PID control.

  The controller 5 reduces the opening of the control valve 3 in the second period. Due to the reduction, the amount of refrigerant circulating in the refrigerant circulation path 2 is reduced, and heat exchange in the temperature maintaining chamber 7 via the heat exchanger 6 is reduced. As a result, the temperature of the temperature maintenance chamber 7 gradually increases from the second temperature, and eventually reaches the first temperature above the target temperature. When the first temperature is reached, the control unit 5 controls the control valve 3 again based on the PID control. The control valve 3 is opened, the refrigerant circulates through the refrigerant circulation path 2, and the temperature of the temperature maintenance chamber 7 decreases via the heat exchanger 6. That is, the first period is started again.

  Here, in the second period, the controller 5 reduces the opening of the control valve 3 and the amount of refrigerant circulating in the refrigerant circuit 2 decreases, so that the amount of vaporized refrigerant that recirculates in the refrigerant circuit 2 also decreases. To do. If the amount of the vaporized refrigerant decreases, the pressure of the vaporized refrigerant flowing back to the compressor 8 immediately becomes equal to or lower than the stop pressure value, and the compressor 8 stops its operation. When the compressor 8 stops its operation, the room for control of the control valve 3 by the control unit 5 is narrowed, and the temperature control of the temperature maintaining chamber 7 by the control unit 5 and the control valve 3 becomes difficult.

  However, the temperature maintenance facility 1 of the first and second embodiments has a buffer tank 9 in the front stage of the compressor 8. Since the buffer tank 9 stores a predetermined amount of vaporized refrigerant, the degree of decrease in the pressure of the vaporized refrigerant returning to the compressor 8 can be suppressed even when the control unit 5 reduces the opening of the control valve 3. For this reason, the operation stop of the compressor 8 hardly occurs, and there remains room for control of the control valve 3 by the control unit 5. When the temperature eventually increases and approaches the first temperature again, the control unit 5 increases the degree of opening of the control valve 3 and starts to decrease the temperature. As a result, the recirculation of the vaporized refrigerant increases and the operation stop of the compressor 8 is further less likely to occur.

  Thus, it can be seen that the buffer tank 9 is effective even when the control unit 5 is used to maintain the target temperature of the temperature maintenance chamber 7 very finely as shown in the graph shown in FIG.

  Here, in the first period under the control by PID control, the temperature change becomes gentle. In addition, also in the second period, the controller 5 does not stop the rotation speed of the compressor 8, but reduces the opening of the control valve 3, so that the refrigerant circulation does not stop suddenly. For this reason, the temperature change in the second period also becomes moderate. As shown in the graph of FIG.

  The fact that the temperature change in the first period and the second period is gradual means that the temperature maintaining facility 1 maintains the temperature of the temperature maintaining chamber 7 at the target temperature (the facility having the temperature maintaining chamber 7 is in operation). The number of cycles in the first period and the second period is reduced. When the number of cycles is small, the period during which the compressor 8 is operating, the number of times the compressor 8 is started, and the starting time of the compressor 8 are reduced. As a result, the temperature maintenance facility 1 can reduce power consumption.

  In the graph of FIG. 7, a curve when the compressor 8 is operated and stopped is also shown. Compared with this curve, the number of cycles in the first period and the second period is the temperature maintenance of the first embodiment. It can be seen that there is less in equipment 1. Also from this graph, it can be seen that the temperature maintenance facility 1 can reduce power consumption.

Since the control unit 5 in the second embodiment controls not the compressor 8 but the amount of refrigerant circulating in the refrigerant circulation path 2, there is no need for modification of the compressor 8. As a result, it has a positive effect on the cost, period, and reliability in the construction of refrigeration equipment and refrigeration equipment using the temperature maintenance equipment 1. Further, the frequency of stopping and restarting the compressor 8 can be further reduced by controlling the amount of refrigerant circulating through the refrigerant circulation path 2 through the control of the control valve 3 instead of controlling the rotation of the compressor 8. In particular, it is possible to promote a decrease in the frequency of stopping and restarting the compressor 8 by the buffer tank 9. The control unit 5 can perform its function better by the buffer tank 9, and the buffer tank 9 is provided in combination with the control unit 5, thereby reducing the frequency of stopping and restarting the compressor 8. In addition, the power consumption of the temperature maintenance facility 1 can be reduced.
Details of adjustment by the control valve 3, the control unit 5, and the control unit 5 will be described.

(Control valve)
The adjustment valve 3 adjusts the amount of refrigerant circulating in the refrigerant circulation path 2. The control valve 3 is provided in the refrigerant circulation path 2 and adjusts the degree of circulation opening in a portion of the refrigerant circulation path 2. When the control valve 3 is closed, a part of the refrigerant circulation path 2 is closed, and the circulation of the refrigerant is stopped (the refrigerant cannot pass through the control valve 3). When the control valve 3 is opened, the refrigerant circulates through the refrigerant circulation path 2. Depending on the degree of opening of the control valve 3, the amount of refrigerant passing through the portion of the refrigerant circuit 2 provided with the control valve 3 changes.

  Thus, the amount of refrigerant circulating through the refrigerant circulation path 2 can be adjusted by adjusting the degree of opening of the control valve 3. If the amount of refrigerant can be adjusted, the pressure of the refrigerant returning to the compressor 8 can also be controlled. As a result, the operation of the compressor 8 is also controlled by adjusting the control valve 3.

  The control valve 3 may be configured by a member that adjusts the degree of opening inside the refrigerant circulation path 2 or may be configured by an electronic device such as an electromagnetic valve. In any case, any valve may be used as long as it is provided at a portion of the refrigerant circulation path 2 and has a mechanism capable of adjusting the amount of refrigerant passing therethrough.

(Control part)
The control unit 5 controls the degree of opening of the control valve 3. If the opening degree of the control valve 3 is controlled, the amount of refrigerant circulating in the refrigerant circulation path 2 varies, and the inside of the temperature maintenance chamber 7 is cooled or not cooled by the heat exchanger 6. As a result, the temperature maintenance facility 1 can maintain the temperature maintenance chamber 7 near the target temperature without performing the compressor 8 and the refrigerant circulation in full time. Actually, as shown in FIG. 7, the temperature maintenance facility 1 controls the temperature maintenance chamber 7 so as to swing within the range before and after the target temperature (the width due to the first temperature and the second temperature).

  The control unit 5 controls the control valve 3 according to PID control in the first period. In the first period, the control unit 5 opens the adjustment valve 3 and allows the refrigerant to pass through the adjustment valve 3 in the refrigerant circulation path 2. That is, the refrigerant is circulated in the refrigerant circulation path 2. As a result, the refrigerant circulates through the refrigerant circulation path 2, and the temperature of the temperature maintenance chamber 7 decreases (as shown in FIG. 3). Here, in the control of the control valve 3 according to the PID control, the control unit 5 controls the amount of refrigerant passing through the control valve 3 by varying the degree of opening of the control valve 3 by various methods. By appropriately controlling the amount of the refrigerant, a rapid temperature drop is prevented in the first period, or overcooling that reaches the second temperature or less is prevented. As a result, the number of rotations of the compressor 8 is also reduced and power consumption is reduced.

  In the second period, the control unit 5 reduces the pressure of the circulating refrigerant by reducing the opening of the control valve 3. Thereby, in the second period, the temperature is gradually increased, and the compressor 8 is stopped due to the pressure drop of the refrigerant returning to the compressor 8. As described above, the gradual temperature change in the second period and the stoppage of the compressor 8 reduce the power consumption of the refrigeration equipment including the compressor 8 and the like.

  The control unit 5 controls the control valve 3 in the first period by various methods.

(Control in the first period)
First, control of the control valve 3 in the first period by the control unit 5 will be described.

(Opening / closing control of control valve 3)
As an example, the control unit 5 can control the amount of refrigerant that passes through the control valve 3 per unit time by opening and closing the control valve 3. Since the control valve 3 is opened and closed, the amount of refrigerant passing therethrough decreases as a result of repeated opening and closing compared to the open state. As a result, the amount of refrigerant passing through the refrigerant circuit 2 decreases. If it decreases, the heat exchange capacity in the heat exchanger 6 decreases, and the temperature inside the temperature maintenance chamber 7 gradually rises as shown by the rising curve in FIG.

  FIG. 8 is a graph showing opening and closing of the control valve according to Embodiment 2 of the present invention. FIG. 4 shows a case where the control valve 3 is in an open state and a case where the control valve 3 repeatedly opens and closes. FIG. 8A shows the former, and FIG. 8B shows the latter. In each graph of FIG. 8A and FIG. 8B, the horizontal axis represents time, and the vertical axis represents the degree of opening of the control valve 3. The upper part of the vertical axis indicates a state in which the control valve 3 is largely opened (shows a state in which the amount of refrigerant passing through the control valve 3 is large). The horizontal axis is the time axis, but is defined in the graph of FIG. 8 with a certain time width as a unit time.

  In each graph of FIG. 8A and FIG. 8B, a curve 51 indicates a change in the degree of opening of the control valve 3. In FIG. 8A, the control valve 3 maintains a sufficiently open state, so the curve 51 is in a straight line state. In other words, control that only opens the control valve 3 is shown, such as so-called ON control.

  In FIG. 8A, since the regulating valve 3 is opened as shown by a curve 51, the refrigerant passes through the regulating valve 3 according to the opening. A region 52 indicates the amount of refrigerant that passes in accordance with the opening of the control valve 3. As can be seen from the region 52 in FIG. 8A, the amount of refrigerant passing through the control valve 3 per unit time is large. As a result, the amount of the refrigerant circulating in the refrigerant circulation path 2 increases, and the cooling of the temperature maintenance chamber 7 via the heat exchanger 6 proceeds at a stretch and falls below the target temperature in a short time.

  On the other hand, the open / close state of the control valve 3 in FIG. 8B is an example of control of the control valve 3 by the control unit 5 in the first period. The controller 5 controls the amount of refrigerant that passes through the unit time by repeatedly opening and closing the control valve 3. By controlling the amount of refrigerant passing therethrough, it is possible to prevent the temperature of the temperature maintaining chamber 7 from being rapidly lowered. A curve 51 in FIG. 8B shows a state where the control valve 3 repeats opening and closing. Region 52 indicates that the refrigerant is passing when the control valve 3 is open, and indicates that no refrigerant is passing when the control valve 3 is closed. That is, when viewed in unit time, the amount of refrigerant passing through the control valve 3 is relatively smaller than when the valve is simply opened. When the amount of refrigerant passing therethrough is small, the amount of refrigerant circulating in the refrigerant circulation path 2 is small, and the temperature maintenance chamber 7 is gradually cooled via the heat exchanger 6. As a result, as shown in the graph of FIG. 7, the temperature of the temperature maintaining chamber 7 changes gradually from the first temperature to the second temperature. This indicates that the rotational speed and operation load in the compressor 8 are reduced, and the power consumption is reduced.

  As described above, the control unit 5 can control the amount of refrigerant passing through the control valve 3 in unit time by controlling the opening and closing of the control valve 3. That is, in the first period, as shown in the graph of FIG. 8 (B), the control unit 5 controls the control valve 3 to control the refrigerant circulation amount, and from the first temperature to the second temperature. Control the temperature change of In the first period, since the refrigerant circulation amount decreases, the pressure of the vaporized refrigerant flowing back to the compressor 8 decreases. As a result, the power consumption of the compressor 8 is also reduced.

  In addition, regarding opening and closing, opening means not only that the control valve 3 is completely opened, but indicates an opened state that can accommodate the passage of refrigerant, and closing means that the valve is completely closed. It is not limited to this, and it shows that the refrigerant is in a state that is difficult to pass through.

(Control valve opening area control)
As another example, the control unit 5 controls refrigerant circulation in the first period by controlling the amount of refrigerant passing through the regulating valve 3 per unit time by controlling increase / decrease in the opening area of the regulating valve 3. To do. When the control valve 3 is provided in the refrigerant circuit 2, the control valve 3 can adjust the degree of opening in a part of the refrigerant circuit 2. That is, the control valve 3 can serve as an open / close door at a position where the refrigerant circulation path 2 is located. For this reason, the regulating valve 3 can vary the amount of refrigerant passing through the regulating valve 3 by adjusting the opening area.

  FIG. 9 is a graph for explaining the control of the control valve according to the second embodiment of the present invention. FIG. 9 shows a case where the control unit 5 increases or decreases the opening area of the control valve 3, unlike FIG. 8. FIG. 9A shows a case where the control valve 3 maintains a certain open state, as in the case of FIG. 9A. For this reason, the amount of refrigerant passing through the control valve 3 per unit time is constant and increases as a whole.

  FIG. 9B shows a state in which the control unit 5 increases or decreases the opening area of the control valve 3. A curve 51 in FIG. 9B shows an increase / decrease state. Since the open state of the control valve 3 follows this curve 51, an amount of refrigerant corresponding to the region 52 such as a half-moon shape passes through the control valve 3. As can be seen from a comparison between FIG. 9A and FIG. 9B, the region 52 in FIG. 9B is small, and the amount of refrigerant passing in a unit time decreases with the increase or decrease in the opening area. I understand. As the amount of refrigerant per unit time decreases, the temperature of the temperature maintenance chamber 7 gradually decreases during the first period. That is, the first temperature changes to the second temperature. Of course, since it changes slowly, less power is required.

  As described above, the control unit 5 controls the amount of refrigerant passing through the control valve 3 per unit time by controlling the degree of opening of the control valve 3 in various ways. Of course, it may be controlled by methods other than those described above.

(Control in the second period)
Next, control in the second period will be described.

  The controller 5 reduces the opening of the control valve 3 in the second period. Since the opening of the control valve 3 can be reduced, the amount of refrigerant circulating in the refrigerant circulation path 2 is reduced. As the amount of refrigerant decreases, the degree of heat exchange in the heat exchanger 6 decreases, and in the second period, the temperature gradually increases as shown in the graph of FIG. The temperature rises from the second temperature to the first temperature. If it raises to 1st temperature, the control part 5 will circulate a refrigerant | coolant by PID control again.

  Here, not only the opening of the control valve 3 is reduced, but the control unit 5 may close the control valve 3. By closing, the amount of refrigerant passing through the control valve 3 is almost eliminated, and the cooling of the temperature maintaining chamber 7 via the heat exchanger 6 is weakened.

  Thus, in the second period, the control unit 5 reduces the amount of refrigerant passing therethrough by reducing the opening of the control valve 3 or closing the control valve 3 in some cases, so that the temperature falls below the second temperature. The entire power consumption is reduced while preventing the temperature of the maintenance chamber 7 from decreasing.

  In addition, as shown in the graph of FIG. 7, it is preferable that the difference value between the first temperature and the target temperature is larger than the difference value between the second temperature and the target temperature. For example, in the graph of FIG. 7, the target temperature is 5 ° C., the first temperature is 1 ° C. higher 6 ° C., and the second temperature is 0.8 ° C. lower 4.2 ° C. Thus, since the difference value of 1st temperature and target temperature is larger than the difference value of 2nd temperature and target temperature, the temperature fall in the 1st period when a temperature change arises because refrigerant circulation is performed more. It becomes gradual and overcooling is prevented. This is because in the first period, the refrigerant circulation is performed and the temperature lowers more artificially. This is because if the second temperature, which is the threshold value for the first period, is set in the same manner as the first temperature, there is a possibility that a positive temperature decrease due to the refrigerant circulation will be excessive.

On the other hand, in the second period, the temperature naturally increases as the refrigerant circulation is reduced or stopped. For this reason, even if the difference value between the first temperature and the target temperature at the end of the second period is large, a problem hardly occurs. From these, it is also preferable that the difference value between the first temperature and the target temperature is larger than the difference value between the second temperature and the target temperature.
As described above, the temperature maintenance facility 1 according to the second embodiment includes the control valve 3 and the control unit 5, thereby reducing power consumption of the temperature maintenance facility 1 and facilitating maintenance in combination with the presence of the buffer tank 9. Long life can be realized.
In addition, the temperature maintenance equipment 1 demonstrated in Embodiment 1, 2 may be grasped | ascertained as a concept including the temperature maintenance room 7 and other elements required by construction. That is, the temperature maintenance facility 1 is applied to a refrigeration facility, a refrigeration facility, a constant temperature facility, and the like.

(Installation of temperature detector)
The temperature detection unit 4 detects the temperature of the temperature maintenance chamber 7 and notifies the control unit 5 of the detection result. The controller 5 extracts the first temperature and the second temperature at the temperature notified by the temperature detector 4, and performs control in the first period and the second period. For this reason, it is preferable that the temperature of the temperature maintenance chamber 7 detected by the temperature detection unit 4 is detected with high accuracy.

  As an example, the temperature detection unit 4 is preferably located at the rear end of the air circulation inside the temperature maintenance chamber 7. In the temperature maintenance chamber 7, air circulates in the interior as the heat exchanger 6 exchanges heat. Convection caused by cold and warm air creates this air circulation. FIG. 10 is a block diagram of the temperature maintenance facility according to Embodiment 2 of the present invention. In FIG. 10, the temperature detection unit 4 is located at the rear end of the air circulation 71. The air circulation 71 starts to circulate from the heat exchanger 6 and returns to the heat exchanger 6 as shown by the broken arrow, and the circulation ends. The region where the circulation ends is the rear end of the air circulation. Of course, the air circulation is connected, but for the sake of clarity, the broken line arrow is stopped after about one round.

  Here, at the initial end of the air circulation (in FIG. 10, the start portion of the air circulation 71, which is a broken line arrow), cold air from the heat exchanger 6 is generated. For this reason, the temperature tends to be detected lower than the temperature of the entire temperature maintaining chamber 7. Even if the temperature detection unit 4 is installed at this position, it is difficult to detect the accurate temperature of the temperature maintenance chamber 7. On the other hand, the end of the air circulation 71 indicated by the broken-line arrow is a portion that returns to the heat exchanger 6. This is the rear end of the air circulation. Here, since the air after the air circulation is completed exists, it is considered that the temperature of the temperature maintenance chamber 7 is reflected more accurately.

  Alternatively, if the heat exchanger 6 performs exhaust and intake, the temperature detection unit 4 is located on the intake side of the heat exchanger 6. Also in this case, since the temperature detection unit 4 is installed at a position where the air circulating through the entire temperature maintenance chamber 7 exists, the temperature detection unit 4 more accurately determines the temperature of the temperature maintenance chamber 7. It can be detected.

  As described above, the temperature detection unit 4 is located at the rear end of the air circulation 71 or is located on the intake side of the heat exchanger 6 so as to detect and control the temperature of the temperature maintaining chamber 7 more accurately. Part 5 can be notified.

  Since the temperature detection unit 4 can detect the temperature with high accuracy, the control unit 3 can be more appropriately controlled by the control unit 5. In addition to this, a buffer tank 9 is provided, which makes it easier to maintain the temperature maintaining chamber 7 at the target temperature while reducing the frequency of stopping and restarting the compressor 8.

  FIG. 11 is a schematic diagram of a temperature maintenance facility according to Embodiment 2 of the present invention. FIG. 11 is drawn with the intention of being actually constructed. The same reference numerals as those in FIG. 1 and the like are the same elements and will not be described. As shown in FIG. 11, a temperature maintenance room 7 such as a freezer room or a refrigerator room is built in a factory or business place, or is independently constructed to form one space. For this reason, the temperature maintenance chamber 7 is often already constructed regardless of the contractor. The contractor completes the temperature maintenance facility 1 by combining a commercially available compressor 8 and other elements. The buffer tank 9 may be prepared by a contractor and is installed in combination with the compressor 8. The refrigerant circulation path 2 may be newly constructed, or an existing pipe line may be diverted. In this manner, the temperature maintenance facility 1 such as a refrigeration facility, a refrigeration facility, or a constant temperature facility is constructed.

  As described above, the temperature maintenance equipment described in the first and second embodiments is an example for explaining the gist of the present invention, and includes modifications and alterations without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Temperature maintenance equipment 2 Refrigerant circuit 3 Control valve 4 Temperature detection part 5 Control part 6 Heat exchanger 7 Temperature maintenance room 8 Compressor 9 Buffer tank

Claims (13)

A compressor that stops the delivery operation as the pressure of the vaporized refrigerant that recirculates and recirculates the refrigerant;
A refrigerant circulation path for circulating the refrigerant delivered from the compressor;
A heat exchanger that performs heat exchange of the refrigerant;
A buffer tank provided in a path from the heat exchanger to the compressor in the refrigerant circulation path,
The buffer tank is a temperature maintenance facility that temporarily stores vaporized refrigerant generated in the heat exchanger.   The temperature maintenance facility according to claim 1, wherein the buffer tank temporarily stores a predetermined amount of vaporized refrigerant returning to the compressor and sends the vaporized refrigerant to be stored to the compressor.   The temperature maintenance facility according to claim 1 or 2, wherein the predetermined amount causes a pressure value (hereinafter referred to as a "stop pressure value") that is greater than or equal to a predetermined pressure value that causes a stop of the delivery operation of the compressor.   4. The refrigerant circuit according to claim 1, wherein the refrigerant circulation path sends vaporized refrigerant to a bottom surface of the buffer tank, and the buffer tank delivers vaporized refrigerant to be stored from the bottom surface of the buffer tank to the compressor. Temperature maintenance equipment.   The temperature maintenance facility according to any one of claims 1 to 4, wherein the compressor maintains its own operation by receiving supply of a vaporized refrigerant having a value equal to or higher than the stop pressure value from the buffer tank.   The temperature maintenance facility according to any one of claims 1 to 5, wherein the buffer tank further includes a plurality of divided regions, and the amount of vaporized refrigerant to be accommodated can be changed depending on a use state of the plurality of regions.   The temperature maintenance facility according to claim 6, wherein each of the plurality of regions is connected to each other by a communication port that can be opened and closed. A regulating valve for regulating the amount of refrigerant circulating in the refrigerant circuit;
The temperature maintenance facility according to any one of claims 1 to 7, further comprising a control unit that controls the control valve.   The control unit performs a change period from a first temperature higher than the target temperature by a predetermined temperature to a second temperature lower than the target temperature by a predetermined temperature (hereinafter referred to as “first period”) and the second temperature. The temperature maintenance facility according to claim 8, wherein the control valve is controlled based on a PID control method during a change period up to one temperature (hereinafter referred to as “second period”).   The control unit controls the regulating valve from a first temperature higher than the target temperature by a predetermined temperature based on a PID control method in the first period, and opens the regulating valve in the second period. The temperature maintenance facility according to claim 8, wherein   The temperature maintenance facility according to claim 10, wherein, in the first period, the control unit controls opening and closing of the control valve so as to control an amount of refrigerant passing through the control valve in a unit time.   The temperature maintenance facility according to claim 10 or 11, wherein the control unit closes the control valve in the second period.   The temperature maintenance facility according to any one of claims 1 to 12, further comprising a temperature maintenance chamber that receives heat exchange by the heat exchanger, wherein the temperature maintenance chamber is at least one of a refrigerator compartment, a freezer compartment, and a temperature-controlled room. .

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