JPS62178853A - Refrigerator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is applicable to refrigeration equipment used in a group of multiple refrigerated/frozen showcases installed at the same place such as a market, that is, a refrigeration system with large load fluctuations. The present invention relates to a refrigeration system that can be operated in an optimal state at all times.

[Conventional technology]

As a conventional refrigeration system of this type, there is one shown in FIG. In this Fig. 2, 1 is a parallel compression refrigeration system;
2 is a plurality of coolers such as showcases 2a, 2b, 2
This is a cooling device composed of a combination of C.

The parallel compression type refrigeration system 1 has a compressor with a rated capacity ratio of approximately 2:1 selected above a liquid receiver connected to the downstream side of a water-cooled condenser 1a or an air-cooled condenser (not shown). A large capacity compressor 1b and a small capacity compressor IC are mounted in parallel, and the refrigerant discharge pipe 1d and suction pipe 1e of each compressor 1b and lc are connected in parallel to each other.

Note that 1f is a pressure-equalizing oil pipe that connects the crank chambers of the compressors 1b and 1c with each other.

Further, 5 indicates the pressure difference between the output signal of the pressure detection unit 3 that detects the refrigerant pressure on the low pressure side and the refrigerant pressure set in the pressure setting unit 4 that sets the refrigerant pressure on the low pressure side to be converged. Compressor 1b and 1c? : A control unit that individually controls operation and stop.

Furthermore, as shown in FIG. 3, the normal pressure region is determined by the capacity up pressure value, capacity down pressure value, and low pressure cut value set by the pressure setting section 4 to the parallel compression type refrigeration system l. Area 2 where the capacity up pressure value is higher than the capacity up pressure value which outputs the up signal, and area C where the capacity up pressure value is at least the capacity down pressure value and less than the capacity up pressure value where neither the capacity down signal nor the capacity up signal is output to the parallel compression type refrigeration equipment l. It is divided into four areas: a region where the pressure is less than the capacity down pressure value which sends a capacity down signal to the compression refrigerating device 1, and a region where the pressure is less than the low pressure cut value which gives a stop signal to the parallel compression refrigerating device 1.

Next, the operation will be explained. For example, when the required power to obtain the required refrigerating capacity for the refrigerating load of the cooling device 2 is 15 IP, the rated capacity of one compressor 1b is selected to be 5W.

On the other hand, in the cooling device 2 made up of a plurality of coolers 2a, 2b, and 2c, the cooling load varies significantly from 0 to 100% depending on the usage status of each showcase.

Here, when the refrigeration load is small (when the refrigerant pressure on the low pressure side of the refrigeration cycle decreases, the pressure detection unit 3
The level of the pressure detection signal output to the control unit 5 also decreases.

Since the control unit 5 has a comparison circuit that compares the pressure detection signal with a reference value (capacity up pressure value or capacity down pressure value), if the pressure detection signal is lower than the capacity down pressure value, that is, In the case of a region entrance, the control unit 5
is controlled to 5 so that the capacity of the parallel compression type refrigeration system 1 is reduced, and the cooling capacity is lowered.

In this way, when the cooling capacity is lowered, the refrigerant pressure on the low pressure side of the refrigeration cycle increases and converges to the region No. 2, and the operation becomes stable.

Furthermore, when the cooling load is high, the refrigerant pressure on the low pressure side of the refrigeration cycle increases, and along with this, the pressure detection unit 3
The level of the pressure detection signal output from the controller 5 increases.

As a result, when the pressure detection signal is higher than the capacity increase pressure value, that is, in the case of region 2, the control unit 5 controls the capacity of the parallel compression type refrigeration unit 1 to increase, thereby increasing the cooling capacity.

In this way, when the cooling capacity increases, the refrigerant pressure on the low pressure side of the refrigeration cycle decreases and converges to region C1~, and the operation becomes stable.

Note that the time from when the pressure detection section 3 detects the pressure at the region 2 or the region mouth until the capacity up signal or the capacity down signal is generated from the control section 5 is the same.

Note that when the refrigerant pressure on the low pressure side of the refrigeration cycle is below the low pressure cut value, that is, in region A, the compressors 1b and 1
c is designed to stop immediately.

Therefore, for the above refrigeration load fluctuation, the refrigeration load is 3
At partial load of 3% or less, compressor IC with rated capacity 5W
Only one vehicle is operated independently.

In addition, when the refrigeration load is in the range of 33% to 66%, the rated capacity 1
Only the compressor 1b with 0EP is operated independently.

Furthermore, when the refrigeration load reaches 66 to 100L0fb, compressors 1b and lb are simultaneously operated in parallel. The transition of this capacity control operation is shown in Fig. 4.

That is, as shown in FIG. 4, by selectively operating and stopping large and small compressors whose rated capacity ratio is selected to be approximately 2:1, .6
Capacity control operation can be performed in four stages of 6%.

[Problem that the invention seeks to solve]

Conventional refrigeration equipment is configured as described above, so when the first refrigerant pressure is higher than the refrigerant pressure that is about to be converged when the compressor restarts after two compressors have stopped, that is, the capacity increase pressure In region 2 where the pressure is higher than the set value, the time from when the pressure is detected until the output signal for changing the capacity of the compressor is generated must be at least 3 minutes in order to suppress the pressure change due to the capacity change as much as possible, and two units are required. Since it takes a total of 9 minutes or more for the compressor to start operating, it takes a long time to reach the target refrigerant pressure, which has the disadvantage that the freshness of the cooled material cannot be maintained.

This invention was made to solve this problem, and even when restarting the compressors after stopping two compressors,
It is an object of the present invention to provide a refrigeration device that can quickly reach a predetermined pressure and maintain the freshness of objects to be cooled.

[Means for solving problems]

In the refrigeration system according to the present invention, the pressure detection section detects the refrigerant pressure on the low pressure side of the refrigeration cycle, generates a pressure detection signal, sets the refrigerant pressure to be converged using the pressure setting section, and generates the pressure detection signal. A control unit that determines whether the refrigerant pressure is above or below the refrigerant pressure to be converged and generates a capacity control output signal to control the capacity of the refrigerator, and a capacity control output signal generated by the control unit, A compressor capacity setting unit is provided that determines the capacity for restarting the compressor according to the pressure difference between the pressure detection signal and the convergence pressure value when all the plurality of compressors are stopped.

[Effect]

In this invention, after restarting the compressor after stopping multiple compressors, the compressor capacity setting section selects the capacity of the compressor according to the pressure difference between the pressure detection signal and the convergence pressure value, and restarts the recompressor. It works to quickly reach a predetermined pressure at certain times.

〔Example〕

Embodiments of the refrigeration system of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the configuration of one embodiment of the present invention, and parts that are the same as those in FIG. 2 are given the same reference numerals and explanation thereof will be omitted, and the explanation will mainly be given to the parts that are different from those in FIG. 2.

In this FIG. 1, parts indicated by reference numerals 1 to 5 are the same as those in FIG. 2, and a compressor capacity setting section indicated by reference numeral 6 is newly added to the configuration of FIG. 2.

That is, the compressor capacity setting section 6 controls the plurality of compressors 1 according to the capacity control output signal generated from the control section 5.
When both b and le are stopped, the compressor has a function of determining the capacity at the time of restarting the compressor according to the pressure difference between the pressure detection signal and the above-mentioned convergence pressure value. □ Next, the operation of the refrigeration system of the present invention will be explained. When the compressor 1b, le is stopped and the refrigerant pressure is higher than the refrigerant pressure to be converged, the output signal for capacity control generated by the control unit 5 indicates that the refrigerant pressure is higher than the capacity increase pressure setting value. 2, the compressor capacity setting section 6;
If the pressure difference between the pressure detection signal and the convergence pressure value is very large, for example, 4 kg/c
When restarting the compressor, multiple compressors 1b
, lc are operated at the same time.

Also, if the pressure difference is medium, for example, 2 kg/c
When the pressure difference is greater than or equal to d and less than 4/-, the compressor 1b is operated when the compressor is restarted, and when the pressure difference is less than 2 kf/i, the compressor 1c is operated when the compressor is restarted. Therefore, the predetermined pressure can be quickly reached.

〔Effect of the invention〕

As explained above, the present invention detects the refrigerant pressure on the low pressure side of the refrigeration cycle with the pressure detection section, generates a pressure detection signal, sets the refrigerant pressure to be converged with the pressure setting section, and detects the pressure as described above. A control unit that determines whether the signal is above or below the refrigerant pressure to be converged and generates a capacity control output signal to control the capacity of the refrigerator, and a capacity control output signal generated by this control unit. If all the compressors are stopped due to Even when the compressors are restarted after a plurality of compressors have been stopped, the predetermined pressure can be quickly reached, the temperature of the object to be cooled remains constant, and the freshness of the object to be cooled is maintained.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of an embodiment of the refrigeration system of the present invention, FIG. 2 is a diagram showing the configuration of a conventional refrigeration system, and FIG. 3 is a diagram showing the refrigerant pressure on the pressure side in the refrigeration system of FIG. FIG. 4, a diagram showing the regions, is an explanatory diagram of the capacity control operation of the refrigeration system in FIG. 2. la...condenser, lb, lc...compressor, 2a-2
C... Cooling device, 3... Pressure detection section, 4... Pressure membrane foot section, 5... Control section, 6... Compressor capacity membrane foot section. Note that the same reference numerals in the figures indicate the same or half parts.

Claims (1)

[Claims] A closed circuit consists of multiple compressors each having a suction pipe and a discharge pipe connected in parallel, a condenser for the refrigerant discharged from these compressors, and a cooler that evaporates the refrigerant sent from the condenser. A refrigeration circuit is connected to the pipes in order to form a refrigeration circuit, a pressure detection section that detects the refrigerant pressure on the low pressure side of this refrigeration circuit and generates a pressure detection signal according to this refrigerant pressure, and A pressure setting unit that sets a convergence pressure value of the refrigerant pressure, determines whether the pressure detection signal is greater than or equal to the convergence pressure value, generates an output signal based on the determination result, and generates an output signal based on this output signal. A control unit that generates a capacity control output signal for controlling the capacity of the machine, when all of the plurality of compressors are stopped by the capacity control output signal generated from the control unit, the pressure detection signal and the above A refrigeration system comprising a compressor capacity setting section that determines the capacity at the time of restarting the compressor according to the pressure difference between convergence pressure values.