JPH065570Y2 - Refrigeration equipment - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] This invention is applied to a refrigerating device used in a plurality of refrigerating / freezing showcase groups having different internal temperatures installed in the same place such as a supermarket in the summer. The present invention relates to guaranteeing the cooling of the group that requires the most cooling even when the load is large, such as when the outside air temperature rises.

[Conventional technology]

Conventionally, this device has been shown in FIG. In FIG. 2, (1) is a parallel compression refrigeration system, and (2) is a refrigeration system composed of a combination of a plurality of showcases (2a), (2b), (2c). The parallel compression refrigeration system (1) has a water-cooled condenser (1a) or a receiver connected downstream of an air-cooled condenser (not shown) with a rated capacity ratio of the compressor of approximately 2 pairs. Two large capacity compressors (1b) and small capacity compressors (1c) selected in No. 1 are installed in parallel, and each compressor (1b)
The refrigerant projection pipe (1d) and the suction pipe (1e) of b) and (1c) are connected in parallel with each other.

(5) is the refrigerant pressure set in the pressure setting unit (4) that sets the low-pressure side refrigerant pressure to be converged with the output signal of the pressure detection unit (3) that detects the low-pressure side refrigerant pressure This is a control unit that controls the operation and stop of the compressors (1b) and (1c) individually according to the pressure difference.

Each of the above showcases (2a), (2b), (2c) has a thermostat (2
d), (2e), (2f) are installed, and this internal thermostat controls the solenoid valves (2g), (2h), (2i) that are the refrigerant supply amount control means, and the internal storage is required. Controlled by temperature.

In (6), the duty setting unit sets the time during which the compressor can operate (duty ON) and the stop time (duty OFF). (6a) and (6b) are magnification setting / control units, (6a) is connected to the solenoid valve (2h), and (6b) is connected to the solenoid valve (2i), and the duty OFF of the duty setting unit (6) is turned off. The solenoid valve (2h) (2i) has a contact point which is closed for a period of time in which a predetermined scale factor (for example, 1.2, 1.5, 2 times, etc.) is applied, and the scale factor can be set.

Further, as shown in FIG. 3, in the normal pressure region, a capacity up signal is sent to the parallel compression refrigeration system (1) according to the capacity up pressure value and the capacity down pressure value set by the pressure setting section (4). Area (d) above the capacity increase pressure value to be output,
A region (c) that is above the capacity down pressure value and below the capacity up pressure value where neither the capacity down signal nor the capacity up signal is output to the parallel compression refrigeration system (1) and the capacity down to the parallel compression refrigeration system (1). It is divided into three areas (b) below the capacity down pressure value for outputting a signal.

The capacity down pressure value is shown in each showcase (2a), (2b),
The required evaporation saturation pressure value of the showcase with the lowest inside temperature of (2c) is set, and the capacity increase pressure value is set to 0.2 to 0.4 kg / cm ² higher. Now, assuming that the showcase (2a) has the lowest inside temperature and (2c) the highest, the relationship between the required evaporation pressures of the showcases (2a), (2b), and (2c) is (2a ) <(2b) <
(2c), the capacity down pressure value is
It is set to the required evaporation pressure of a).

The duty setting section (6) sets the duty ON and OFF according to the showcase (2a) with the lowest internal temperature.
The magnification setting control units (6a) (6b) set the magnification according to the set temperature of the connection showcases (2b) (2c). (For example, (6a) is 1.2
2 times, (6b) is 1.5 times) Next, the operation will be described. Multiple showcases (2
In the cooling device (2) including a), (2b), and (2c), the refrigeration load varies from 0 to 100% depending on the cooling condition of each showcase.
Here, among the showcases (2a), (2b), (2c), the showcases with a higher internal temperature are sequentially cooled to activate the internal thermostat, and the refrigerant pressure on the low pressure side of the refrigeration cycle decreases, Along with this, the level of the pressure detection signal output from the pressure detection unit (3) to the control unit (5) also decreases.

Since the control unit (5) has a comparison circuit for comparing the pressure detection signal with a reference value (capacity up pressure value or capacity down pressure value), that is, when the pressure detection signal is lower than the capacity down pressure value, In case of area (b), control unit (5)
Is controlled so that the capacity of the parallel compression refrigeration system (1) is decreased, and the cooling capacity is decreased, so that the refrigerant pressure rises and converges to the region (c). Furthermore, as the cooling progresses, the showcase (2a) with a low internal temperature cools, and the showcase (2b)
In the only cooling operation, the refrigerant pressure on the low pressure side of the refrigeration cycle further decreases, and when the capacity down pressure value is reached, the capacity of the parallel compression refrigeration system (1) is decreased.

Next, the duty cycle will be described. When the duty OFF time of the duty setting section (6) is reached, the compressor (1b) (1c)
Will stop. However, when the internal temperature is high, the duty OFF is canceled when a separately provided thermostat (not shown) is activated. Also, during the magnification time of the magnification setting / control units (6a) and (6b), the corresponding solenoid valves (2h) (2i) are closed and only the showcase (2a) is operated. In this case, the capacity control operation is performed as in the cooling operation.

When the outside air temperature rises in summer, the condensing temperature rises and the cooling capacity falls. Also, due to the rise in store temperature, showcase
The required refrigeration capacity of (2a) (2b) (2c) increases. Cooling capacity <required refrigeration capacity and low pressure rises to showcase (2a) (2
b) The temperature of (2c) also rises. In this case, duty OFF is canceled by a thermo that is provided separately.

[Problems to be solved by the device]

In the conventional refrigeration system, when the outside air temperature rises in the summer, the temperature of all showcases rises, and in particular, the temperature rise of the showcase with a low inside temperature (that is, a low steam temperature) is large,
There is a problem that the influence on quality deterioration is very large.
There is also a method of selecting the refrigerating apparatus itself under the condition of the maximum outside air temperature increase in summer, but there are problems that the refrigerating machine capacity becomes excessively large and expensive, and the contract electric power becomes high.

This invention was made in order to solve the above problems, and prevents deterioration of quality even in a relatively small capacity device such as a refrigerating device in which freshness is greatly reduced unless cooling operation is constantly performed. The purpose is to obtain a refrigerating device that can.

[Means for Solving the Problems]

A refrigerating apparatus according to the present invention is provided in association with a compressor, a condenser, a plurality of evaporators, and each of the above-described evaporators, the capacity of which can be controlled, and a refrigerant supply amount control for controlling a refrigerant supply amount to each evaporator. A refrigerant circuit configured by means, a pressure detection unit that detects the suction pressure of the compressor, a pressure setting unit that sets a converged pressure value of the low-pressure side refrigerant pressure that is to be converged, and a detection pressure of the pressure detection unit And a set pressure value of the pressure setting unit, a control unit that controls the capacity of the compressor, a duty setting unit that executes a duty cycle that stops the compressor for a fixed time, and a predetermined time for the stop time. According to the time set to the magnification, in the one having a magnification setting control unit that closes each refrigerant supply amount control means, if the refrigerant pressure on the low pressure side is higher than the convergent pressure value for a certain period of time, the compressor When stopped In contrast to the refrigerant supply amount control means which is controlled at a predetermined magnification, the refrigerant supply amount control means with the highest magnification is closed, and after closing, the refrigerant pressure on the low pressure side is kept below the converged pressure value for a certain period of time. At this time, the above object is achieved by providing a low pressure determination section for opening the refrigerant supply amount control means having the highest magnification. Further, in the case where the cooling load is further large, etc., after closing the refrigerant supply amount control means with the highest magnification, if the refrigerant pressure on the low pressure side is at or above the convergent pressure value for a certain period of time or more, The above object is achieved by providing a low pressure setting section for sequentially performing the operation of closing the high refrigerant supply amount control means.

[Action]

When the refrigerant pressure on the low pressure side is higher than the convergent pressure value for a certain period of time, the temperature of the evaporator with the lowest set temperature can be maintained by closing the refrigerant supply amount control means with the highest ratio. . Further, after closing the refrigerant supply amount control with the highest magnification, if the low-pressure side refrigerant pressure is equal to or higher than the convergent pressure value for a certain period of time, the refrigerant supply amount control means with the next highest magnification is closed. By performing the operations sequentially,
This is to maintain the temperature of the evaporator with the lowest set temperature.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of a refrigerating apparatus according to the present invention, and the same portions as those in FIG. 2 are designated by the same reference numerals. In the figure, (7) is a low pressure determination unit,
The output signals from the pressure detection unit (3) and the pressure setting unit (4) are input, and are connected so as to supply a required output signal to the duty setting unit (6).

Next, the operation will be described.

Cooling operation and duty cycle are the same as conventional ones.

When the outside air temperature rises in summer, the condensing temperature rises and the cooling capacity falls. In addition, the showcase (2
The required refrigeration capacity of a) (2b) (2c) is increased. [Cooling capacity] <
(Required refrigerating capacity for evaporators (2a) (2b) (2c)) and low pressure rises and is higher than the set capacity increase pressure value for a certain period of time. [Cooling capacity]> [Evaporators (2a), (2b) by closing the refrigerant supply amount control means (2i) connected to the largest magnification setting control section (6b) of the setting section (6) And the low pressure converges to the set pressure, and the showcases (2a) and (2b) can be cooled.

If the above condition continues for a certain period of time, the low pressure determination unit (7)
Then, the refrigerant supply amount control means (2i) is opened.

Further, as another embodiment, when the low pressure does not fall below the set pressure even when the refrigerant supply amount control means (2i) is closed, the refrigerant supply amount control means (2h) with the next higher magnification is closed and the same operation is performed. Take control.

It should be noted that when the outside air temperature rises in the summer, it appears during a short daytime such as 35 ° C or higher.

[Effect of device]

In the present invention, the capacity controllable compressor, condenser,
Provided corresponding to a plurality of evaporators and each of the above evaporators,
A refrigerant circuit composed of a refrigerant supply amount control means for controlling the refrigerant supply amount to each evaporator, a pressure detection unit for detecting the suction pressure of the compressor, a convergent pressure of the low-pressure side refrigerant pressure to be converged. A pressure setting section for setting a value, a pressure detecting section for comparing the detected pressure of the pressure detecting section and a set pressure value for the pressure setting section, a control section for controlling the capacity of the compressor, and a duty cycle for stopping the compressor for a certain period of time. In the refrigerating apparatus having a duty setting unit to be executed and a magnification setting control unit that closes each refrigerant supply amount control unit according to a time set to a predetermined magnification with respect to the stop time, the refrigerant pressure on the low pressure side However, if the convergent pressure value is higher than the converged pressure value for a certain period of time, among the refrigerant supply amount control means that controls the compressor stop time at a predetermined ratio, the refrigerant supply amount control device with the highest ratio is closed and closed. When the low-pressure side refrigerant pressure is held below the convergent pressure value for a certain period of time, by providing a low-pressure pressure determination unit that opens the refrigerant supply amount control means with the highest magnification, cooling at high load, By giving priority to the showcase with the lowest internal temperature, the quality of the objects to be cooled in the low showcase can be stabilized, and the equipment can be selected under normal summer conditions (outside air temperature 32 ° C, etc.). Since the capacity can be determined, the capacity can be reduced, the internal cost can be reduced, the kayak power can be reduced, and an inexpensive device can be obtained.

Further, in the case where the cooling load is further large, after closing the refrigerant supply amount control means with the highest magnification, if the refrigerant pressure on the low pressure side is below the converged pressure value for a certain period of time, the refrigerant with the next highest magnification By providing the low pressure setting section for sequentially performing the operation of closing the supply amount control means, the same effect as the above can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a refrigeration system according to the present invention, FIG. 2 is a block diagram showing a conventional system, FIG. 3 is a diagram showing a region of refrigerant pressure on the low pressure side in this system, and FIG. The figure is an explanatory view of the capacity control operation of the refrigerating apparatus of FIGS. 1 and 2. In the figure, (1a) is a condenser, (1b), (1c) is a compressor, (2a)
~ (2c) is an evaporator, (9) is a refrigerant circuit, (2g) ~ (2i) is a refrigerant supply amount control means, (3) is a pressure detection unit, (4) is a pressure setting unit,
(6) is the duty setting section, (6a) and (6b) is the magnification setting control section,
(7) is a low pressure determination section, and (5) is a control section. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] 1. A compressor having a controllable capacity, a condenser, a plurality of evaporators, and a refrigerant supply amount control means which is provided corresponding to each of the evaporators and controls the refrigerant supply amount to each evaporator. Refrigerant circuit, a pressure detection unit that detects the suction pressure of the compressor, a pressure setting unit that sets a converged pressure value of the low-pressure side refrigerant pressure that is to be converged, a detection pressure of the pressure detection unit and the pressure A control unit that compares the set pressure value of the setting unit and controls the capacity of the compressor, a duty setting unit that executes a duty cycle that stops the compressor for a certain period of time,
And, with respect to the stop time, according to the time set to a predetermined ratio, having a ratio setting control unit that closes each refrigerant supply amount control means, the refrigerant pressure on the low pressure side is greater than the convergent pressure value. If it is high for a certain period of time, among the refrigerant supply amount control means controlling the compressor at a predetermined ratio to the stop time, close the refrigerant supply amount control means with the highest ratio, and after closing, the refrigerant pressure on the low pressure side. Is maintained for a certain period of time at or below the convergent pressure value, a low-pressure pressure determination unit that opens the refrigerant supply amount control means with the highest magnification is provided.