JPS6325457A - Refrigerator - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Industrial Application Field The present invention relates to a variable capacity type refrigeration system that uses both the number control of a plurality of compressors and the rotation speed control of one or more of the compressors. Regarding equipment.

(0) Prior Art Conventionally, this type of refrigeration apparatus has been described in Japanese Patent Application Laid-Open No. 59-94258, etc., and was constructed as shown in FIG. To explain below, 20 is two compressors A and B connected in parallel.
This is a refrigeration cycle with an incorrect configuration in which a condenser 21, an expansion valve 22, and an evaporator 23 are sequentially connected. 24 is the compressor A
This is a controller that is electrically connected to each of the refrigeration cycles 20 and H, and controls the number of operating units according to the load amount of the refrigeration cycle 20. 2
5 is electrically connected only to the compressor B and is a refrigerating cycle 20.
This is a variable frequency device that controls the rotation speed of the compressor according to the load amount of the compressor. By controlling the rotation speed of only one compressor B out of the plurality of compressors A and H, such a refrigeration system reduces the electric capacity of the frequency variable device and saves power. By setting the capacitance ratio of A and H to 1=2 and setting the variable capacity of the frequency variable device 25 to 50 to 100%, each control region (2) is set as shown in FIG.

Capacity control over a wide range is performed by connecting the control range (2) continuously and linearly in adjacent areas.

(c) Problems to be solved by the invention However, according to the above configuration, the control range of each control area is connected continuously and linearly in adjacent areas, so the refrigeration load and the capacity of the refrigeration system are There is always a 1:1 correspondence. Therefore, if the refrigeration load slightly fluctuates in adjacent control areas, for example, if the load corresponding to around 66% of the refrigeration equipment capacity in Figure 7 begins to increase or decrease slightly. In the case of commercial The problem is that the compressor A, which is operated by a power source, frequently starts and stops, making the control unstable and causing short cycle operation. The purpose is to prevent a compressor operated by commercial power from frequently starting and stopping even if the load fluctuates near the boundary of a region, thereby stabilizing control and preventing short-cycle operation.

(D) Means for Solving the Problems The present invention comprises a refrigeration cycle constructed by sequentially connecting a plurality of compressors, condensers, depressurizers, and evaporators connected in parallel. Load detection means for detecting the amount of load is provided, and the number of operating compressors is controlled according to a signal from this means, and one of the compressors is controlled by a frequency variable device according to a signal from the means. In a refrigeration system in which the rotation speed is controlled and the remaining compressors are operated at a constant speed using commercial power, the control range of the compressor whose rotation speed is controlled, or the compressor whose rotation speed is controlled and the constant speed operation. The control ranges of each compressor combination are configured so that they overlap in adjacent control ranges.

(e) Effect The refrigeration system of the present invention has the above-described configuration, so that the capacity near the upper limit or lower limit in each control area can be duplicated in each adjacent control area. For example, in the conventional configuration, each control area If the refrigeration load, which was handled by the capacity near the area boundary, increases or decreases slightly, the control area can be changed without the conventional control of shifting the control area, that is, starting and stopping the compressor operated by commercial power. It is possible to control the rotational speed within the same control range, reduce the frequency of starting and stopping of the compressor operated by commercial power, stabilize the control, and prevent short cycle operation. .

(f) Example Embodiments of the present invention will be described below based on the drawings.

1 has three compressors A, B, and C connected in parallel.

This is a refrigeration cycle configured by sequentially connecting a condenser 2, an expansion valve 3, and an evaporator 4. The three compressors A, B, C
The respective capacities are 5Hp and 7.5Hp.

Different capacities such as 10 Hp (1:1.5:2) are used. 5 is a pressure sensor attached to the low pressure side piping 6 of the refrigeration cycle 1, and this sensor detects a low pressure value as the load amount of the refrigeration cycle 1, converts this detected value into an electric signal, and performs the control described later. It is output to device 7. Here, the compressors A and C are powered by Sanwa AC power @ 12 (commercial power supply) via electromagnetic contactors 8 and 9, respectively.
and compressor B has a frequency of 25Hz to 75Hz.
A three-phase AC power source 12 via a frequency variable device 10 that varies in the range of Hz (50 to 150%) and an electromagnetic contactor 11
It is connected to the. 7 inputs the signal from the pressure sensor 5, and outputs a signal corresponding to the difference between this input value and a preset setting value to the electromagnetic contactor 8゜9.11 and the frequency variable device 10. , performs ON-OFF of the contactor and frequency control of the frequency variable device 10, and controls the refrigeration cycle 1.
This is a control device that controls the number of compressors A and C according to the load amount, and also controls the rotation speed of compressor B according to the load amount.

In the refrigeration system configured in this way, the capacity control range is as shown in FIG. Here, the compressor B whose rotation speed is controlled by the frequency variable device 10 has a fixed capacity of 7.
．． 5 Hp, and the variable capacity of the variable frequency device 10 is 50 to 150%, so the capacity control range of the compressor B is 3.75 to 11.25 Hp. In the area (3) where the capacity is the smallest, only the compressor B is used.
Capacity control is performed from 75 to 11.25 Hp. Next, in the combination area with a small capacity, that is, the combination area (■) of compressor B whose rotation speed is controlled and compressor A that operates at a constant speed of 5 Hp, the combination of compressors A and H is 8.75 to 16.25 H.
Capacity control is performed up to p. In addition, in the combination region (2) with the next smallest capacity, that is, the combination region (3) of compressor B whose rotation speed is controlled and toup compressor C which is operated at a constant speed, the combination of compressors B and C is 13.75 to 21. Capacity control is performed up to 25 Hp. Finally, in the combination region with the largest capacity, that is, the combination region (3) of compressor B whose rotation speed is controlled and compressors A and B which are operated at constant speed, compressor A is selected.

Three units B and C control the capacity from 18.75 to 26.251 ip.

That is, the capacity control range of the refrigeration system is set so that the adjacent combination areas from ■ to ■ partially overlap (have hysteresis). As a result, for example, if the refrigeration load corresponding to the capacity shown at point P in Figure 2 changes slightly, the capacity will be controlled on the combination area ■, and the capacity will correspond to the capacity shown at point Q in the same figure. If the refrigeration load that was being used changes slightly, the capacity is directly controlled in the combination area (2), so even if the load is the same, it can be controlled within the combination area at that time. Therefore, even if the load fluctuates slightly near the boundary between each combination area, it is possible to reduce the occurrence of frequent starting and stopping of the compressors A and C, which are operated at a constant speed, and short cycle operation. Note that FIG. 3 shows the hysteresis of the refrigeration system in the control example described above.

Moreover, FIGS. 4 and 5 are explanatory diagrams of capacity control of a refrigeration system showing other embodiments, and FIG. 4 shows that each fixed capacity is 5.
Three compressors A and B with Hp, 7.5Hp, and 10Hp
, C, and a 10Hp compressor C for 25 to 75H.
The rotation speed is controlled in the range of z (50 to 150%), and each fixed capacity in FIG. 5 is 5 Hp.

Using two compressors A and B of 7 and 5 ttp, and
7.5Hp compressor B at 25~75Hz (50~150Hz)
%), and as shown in each figure, these devices can also have hysteresis in adjacent combination areas (control areas), producing the same effects as the present embodiment.

(g) Effects of the invention As described above, the present invention provides a plurality of compressors connected in parallel,
A refrigeration cycle is constructed by sequentially connecting a condenser, a pressure reducing device, and an evaporator, and the refrigeration cycle is provided with load detection means for detecting a load amount, and the compressor is operated in accordance with a signal from this means. A refrigeration system in which the number of compressors is controlled, the rotation speed of one of the compressors is controlled by a variable frequency device in response to a signal from the means, and the remaining compressors are operated at a constant speed using commercial power. The control range of the compressor whose rotation speed is controlled or the control range of the combination of the compressor whose rotation speed is controlled and the compressor which is operated at a constant speed is configured to overlap in adjacent control areas. Therefore, if the refrigeration load corresponding to the capacity near the boundary of each control area -〇- increases or decreases slightly, it is possible to prevent the control area from changing frequently. It is possible to reduce the frequency of starts and stops, stabilize control, and prevent short cycle operation.

[Brief explanation of drawings]

Figures 1 to 3 show embodiments of the present invention, Figure 1 is a configuration diagram of a refrigeration system, Figure 2 is an explanatory diagram showing capacity control of the refrigeration system, and Figure 3 shows hysteresis of capacity control. Explanatory diagram,
FIGS. 4 and 5 are explanatory diagrams showing capacity control in refrigeration systems of other embodiments, FIGS. 6 and 7 show conventional examples, FIG. 6 is a block diagram of the refrigeration system, and FIG. FIG. 2 is an explanatory diagram showing capacity control of the refrigeration device. A, B, C... Compressor, 1... Refrigeration cycle,
2... Condenser, 3... Expansion valve, 4... Evaporator, 5... Pressure sensor. Applicant Sanyo Electric Co., Ltd. (1 other person) Representative Patent attorney Higashi Nishino (1 other person) No. 1f! 1 Fig. 2 Fig. 3 12 14 16 181, f1 Fig. 4 Fig. 5 ■ Fig. 6 Fig. 7 II [

Claims (1)

[Claims] (1) A refrigeration cycle is constructed by sequentially connecting a plurality of compressors, condensers, pressure reduction devices, and evaporators connected in parallel, and the refrigeration cycle is provided with a load detection means for detecting a load amount, The number of operating compressors is controlled in response to a signal from this means, and the rotation speed of one of the compressors is controlled by a frequency variable device in response to a signal from the means, and the number of rotations of the remaining compressors is controlled by a variable frequency device. In a refrigeration system that operates at a constant speed using a commercial power supply, the control range of the compressor whose rotation speed is controlled or the control range of the combination of the compressor whose rotation speed is controlled and the compressor which is operated at a constant speed is , a refrigeration system characterized in that adjacent control areas are configured to overlap.