JPS63131958A - 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. 3, 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.

In the parallel compression type refrigeration system 1, the rated capacity of the compressor is selected to be approximately 2:1 above the liquid receiver connected to the downstream side of the water-cooled condenser 1a or the air-cooled condenser (not shown). Two large-capacity compressors 1b and small-capacity compressors 1c are mounted in parallel, and each compressor 1b and the refrigerant discharge pipe 1d and suction pipe 1e of the IC are connected in parallel to each other.

Note that if is a pressure equalizing oil pipe that connects the crank chambers of the compressors 1b and lc 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. This is a control unit that controls the operation and stop of the compressors 1b and 1c individually.

Furthermore, as shown in FIG. 4, 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 1. Area 2 where the capacity up pressure value is higher than the capacity up pressure value that 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 1. 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 for obtaining the required refrigerating capacity for the refrigerating load of the cooling device 2 is 151P, the rated capacity of one compressor 1b is selected to be 5H).

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

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

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), so if the pressure detection signal is lower than the capacity down pressure value, i.e. , in the case of the area entrance, the control unit 5
controls so that the capacity of the parallel compression type refrigeration system 1 is reduced, thereby lowering the cooling capacity.

When the cooling capacity is lowered in this way, the refrigerant pressure on the low pressure side of the refrigeration cycle increases and converges to region C, 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 to the control unit 5 increases from then on.

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 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 C, and the operation becomes stable.

Note that the time from when the pressure detection unit 3 detects the pressure at the area 2 or the area mouth until the capacity up signal or capacity down signal is generated from the control unit 5 is the same, taking into account operational stability, etc. It is set to 3 minutes.

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, lc
is 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 5P
Only one vehicle is operated independently.

In addition, when the refrigeration load is in the range of 33 to 66 inches, the rated capacity is 1
Only the compressor 1b (0H) is operated independently.

Furthermore, if the refrigeration load becomes 66 to 100 inches, the compressor 1
b and 1b are operated in parallel at the same time. The transition of this capacity control operation is shown in Fig. 5.

That is, as shown in Fig. 5, by selectively operating and stopping the large and small compressors, whose rated capacity ratio is approximately 2:1, ．．
Capacity control operation can be performed in four stages of 66%.

[Problem that the invention seeks to solve]

Conventional refrigeration equipment is configured as described above, so it operates stably when the load fluctuates slowly, but it takes 3 minutes for the capacity up or down signal to be output, so it is difficult to operate when the load fluctuates suddenly. In this case, the internal temperature of the refrigerator rises due to the delay in changing the capacity, resulting in a problem that the freshness of the refrigerated material is lost and the operation becomes inefficient.

This invention was made to solve the above-mentioned problems, and the object is to obtain a refrigeration system that can quickly change the capacity according to the speed of load fluctuation and can perform efficient operation. .

[Means to solve all problems]

The refrigeration system according to the present invention includes a time setting section that changes the time for changing the compressor capacity according to the difference between the low pressure side pressure of the refrigeration cycle detected by the pressure detection section and the pressure set in the pressure setting section. It is something that

[For production]

In this invention, the time setting section sets the time for changing the capacity of the compressor according to the pressure difference between the pressure detection signal and the convergence pressure value, so that the predetermined pressure is quickly reached.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a block diagram of a refrigeration system, and the same parts as those of the conventional system shown in FIG. 1st
In the figure, numerals 1 to 5 are the same as in Fig. 3, and numeral 6
A time setting section indicated by is newly added to the apparatus shown in FIG.

That is, the time setting section 6 sets the time period from when the pressure detection section 3 detects the pressure at the area 2 or the area mouth until the capacity up or capacity down signal is generated from the control section 5 to converge with the pressure detection signal. The function of the pressure value is determined according to the pressure difference, and the relationship is as shown in Figure 2.

Next, the operation of this invention will be explained. According to the output signal for capacity control generated by the control unit 5, for example, when the compressor 1b is operating in the region C, the cooling load increases, and the detected pressure starts to increase accordingly to 1.6 KIi/1YIi.
In the case of *, the detection pressure (1,6~k) and the set pressure <
Since the difference in 1.3 Kf/+ is 0.3 to μ, the controller 5 increases the capacity 105 seconds after the detected pressure exceeds 1.3 Kp/-d' as shown in Figure 2. A signal is output, and the compressor 1b and IC are put into operation to deal with the increase in load. On the other hand, if the compressor 1b is operating in the region no and the load decreases and the detected pressure decreases to 0.6 Kt/d, the pressure difference will be 0.21'v/i, so as shown in Figure 2. As shown in FIG. 2, 23 seconds after the detected pressure falls below 0.8 Kp/cdv, the control unit 5 outputs a capacity down signal and shifts to operation of only the compressor IC.

Further, when the compressors 1b and lc are both stopped, when the mode shifts to region 2, the compressor IC starts up after the time determined by A, and time measurement for the next mode starts from that time. If the load is large and remains in region 2, the compressor 1b will be operated with characteristics A.

〔Effect of the invention〕

As explained above, according to the present invention, the pressure detection section detects the refrigerant pressure on the low pressure side of the refrigeration cycle to generate a pressure detection signal, and the pressure setting section sets the refrigerant pressure to be converged. A control unit that determines whether the pressure detection 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 control unit that generates a capacity control output signal to control the capacity of the refrigerator, and control based on the difference between the detected pressure and the set pressure. Since the time at which the capacitance increase or capacitance decrease signal generated by the section is made variable, the capacitance can be changed in accordance with the speed of load fluctuation. Therefore, stable operation can be performed and a predetermined pressure can be quickly reached, so that the temperature of the cooled material is constant and freshness can be maintained. It also allows efficient driving.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a refrigeration system according to an embodiment of the present invention;
Figure 2 is a characteristic diagram showing the relationship between the difference between the detected pressure and the set pressure and the compressor capacity change time, Figure 3 is a configuration diagram of a conventional refrigeration system, and Figure 4 is the refrigerant on the pressure side in Figure 3. FIG. 5, which is a diagram showing the pressure region, is also an explanatory diagram of the capacity control operation. 1a... Condenser, lb, lc... Compressor, 2a-2
C... Cooling device, 3... Pressure detection section, 4... Pressure setting section, 5... Control section, 6... Time setting section. Note that the same reference numerals in the figures indicate the same or similar 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 compressor, and a time setting unit that varies the time for changing the compressor capacity according to the difference between the pressure detection signal and the convergence pressure value. A refrigeration device characterized by: