JPS629153A - 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] The present invention relates to a refrigeration system with large load fluctuations, more specifically, a refrigeration system used for cooling multiple units, a group of refrigeration showcases, etc. It is designed so that it can be operated in the same condition.

[Conventional technology]

A conventional refrigeration system with large load fluctuations will be explained based on FIG. 2.

In the figure, 1 is a parallel compression refrigerator, 2 is a plurality of showcases 2a that serve as variable loads for the parallel compression refrigerator 1,
This is a cooling device constructed by combining 2b and 2c.

The parallel compression refrigerator 1 is composed of a water-cooled or air-cooled condenser 1a, a large-capacity compressor 1b and a small-capacity compressor IC whose rated capacity ratio is approximately 1:2. The discharge sides of the meat compressors lb, lc are commonly connected by a refrigerant discharge pipe 1d, and the suction sides are also commonly connected by a suction pipe 1e. 1f is compression 45i1
This is a pressure equalizing oil pipe that connects the crank chambers of b and IC to each other.

In addition, 3 is a pressure detection unit that detects the refrigerant pressure on the low pressure side (suction side) of the refrigerator 1, 4 is a pressure setting unit that sets the refrigerant pressure, and 5 is an output signal of the pressure detection unit 3. This is a control unit that individually controls the operation and stop of the compressors 1b and Ic according to a pressure difference signal between the refrigerant pressure and the refrigerant pressure set by the refrigerant pressure setting unit 4.

Figure 3 shows the refrigerant pressure region on the low pressure side of the compressor.
The normal pressure region includes a capacity up pressure value and a capacity down pressure value set by the pressure setting unit 4.

Region 2, which is equal to or higher than the capacity up pressure value that outputs a capacity up signal to the parallel compression type refrigerator 1 based on the three low pressure cut values, and capacity down pressure where neither a capacity down signal nor a capacity up signal is output to the parallel compression type refrigerator 1. A region C which is equal to or more than the capacity up pressure value and less than the capacity up pressure value, a region port which is less than the capacity down pressure value which outputs a capacity down signal to the parallel compression type refrigeration machine ml, and a low pressure which outputs a stop signal to the parallel compression type refrigeration machine $1. It is divided into four areas: (a) a region below the cut value;

Next, the operation of the above-mentioned refrigeration system will be explained.

For example, if the required power to obtain the required refrigerating capacity for the refrigerating load of the cooling device 2 is 151-IP, the rated capacity of one compressor 1b is 10 HP, and the rated capacity of the other compressor I
The rated capacity of C is selected to be 5 HP.

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

Here, when the refrigeration load decreases, the refrigerant pressure on the low pressure side of the refrigeration cycle decreases, and the level of the pressure detection signal output from the pressure detection section 3 to the control section 5 also decreases accordingly. The control unit 5 compares the pressure detection signal with a reference value (capacity up pressure value or capacity down pressure value), and when it is determined that the pressure detection signal is lower than the capacity down pressure value,
That is, in the case of the area entrance, the control unit 5 controls the parallel compression refrigerator 1.
control so that the capacity of 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 its operation becomes stable.

Further, when the cooling load is high, the refrigerant pressure on the low pressure side of the refrigeration cycle increases, and the level of the pressure detection signal output from the pressure detection section 3 to the control section 5 increases accordingly.

As a result, when the pressure detection signal is higher than the capacity increase pressure value, in the case of W region 2, the control unit 5 controls the capacity of the parallel compression refrigerator 1 to increase, thereby increasing the cooling capacity. . When the cooling capacity increases in this way, the refrigerant pressure on the low pressure side of the refrigeration cycle decreases and converges to the region (), and the operation becomes stable.

Note that the refrigerant pressure on the low pressure side of the refrigeration cycle is
If it is below the value, that is, in area A, the pressure w18! lb, l
c is to be stopped immediately.

Therefore, with respect to the above-mentioned refrigeration load fluctuation, only the compressor 1c with a rated capacity of 5 HP is operated independently when the refrigeration load is at partial load of 33% or less. In addition, the refrigeration load is 33 to 6
In the 6% range, only the compressor 1b with a rated capacity of 10 HP is operated independently. Furthermore, when the refrigeration load becomes 66 to 100%, the compressors 1b and lc are simultaneously operated in parallel. The transition of the capacity control operation at this time is shown in FIG. 4.

That is, as is clear from FIG. 4, compression 91b.

By selectively operating and stopping the large and small compressor 1b, whose rated capacity ratio of 1c is selected to be approximately 1:2, the capacity can be set in four stages: 0%, 33%, 66%, and 100%. Controlled operation becomes possible.

[Problem that the invention seeks to solve]

In conventional refrigeration systems such as those mentioned above, when load fluctuations are large, the compressor frequently starts and stops, resulting in short-cycle operation. Due to repeated activation, large currents frequently flow through the motor, raising the temperature of the motor and causing the windings to burn out due to overheating.

Therefore, there is a method to forcibly stop the compressor for a certain period of time once the short cycle operation is performed, thereby preventing the compressor from seizing and the electric motor from burning out. There was a problem in that the temperature inside the refrigerator rose, which had a negative effect on the amount inside the refrigerator.

This invention was made to solve the above-mentioned conventional problems. It prevents short-cycle operation even when load fluctuations are large, prevents compressor seizure and motor burnout, and saves power. The purpose is to capture and provide refrigeration equipment that has made it possible to use all types of refrigeration equipment.

[Means for solving problems]

The refrigeration system according to the present invention includes, in addition to a pressure setting section for setting the refrigerant pressure to converge, a detection section for detecting the number of times the compressor starts and stops within a predetermined time, and a detection section that detects the number of times the compressor starts and stops within a predetermined time. The pressure setting value control section is added to control the pressure setting value of the pressure setting section according to the pressure setting section.

[For production]

In this invention, the pressure setting value control section changes the pressure setting value of the pressure setting section according to the number of starts and stops within a predetermined time from the number of starts and stops detecting section, and parallel compression is performed according to the changed pressure setting value. By controlling the type refrigerator, it is possible to eliminate short-cycle operation of the compressor even when load fluctuations are large.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail based on FIG. 1.

In FIG. 1, parts that are the same as those in FIG. 2 are given the same reference numerals and explanations thereof will be omitted, and different parts will be emphasized.

That is, the compressor 1b even when load fluctuations are large.

In order to prevent short-cycle operation of the IC (operation that repeatedly starts and stops frequently), a pressure 11 engine start/stop frequency detection section 6 and a pressure set value control section 7 are newly added.

The compressor start/stop frequency detection section 6 detects the number of times the compressors 1b, lc are started/stopped within a predetermined period of time. The setting value of the pressure setting unit 4 is changed according to the detected number of times the compressor starts and stops, and this changed pressure setting value is sent from the pressure detection unit 3 to the control unit 5 of the compressor 1b, lc. It is designed to be input together with the signal.

Next, the operation of the refrigeration system configured as described above will be explained.

The compressor start/stop frequency detecting unit 6 detects the number of times the compressors 1b and Ic start and stop within a predetermined period of time, and changes the pressure setting value set by the pressure setting unit 4 according to the number of starts and stops to the pressure setting value. It is changed by the control unit 7.

For example, if the number of starts and stops of compressors 1b and lc is 7 or more times in 5 minutes, the capacity down pressure value will be reduced to 0.2kg/cj.
Change the pressure setpoint to lower it.

By changing the pressure setting value as described above, the area C in Figure 3 is 0.2 kg/cl lower than the conventional one! r becomes larger, and the area opening becomes smaller by 0.2kg1cd. That is, when the refrigeration load fluctuates greatly, the refrigerant pressure on the low-pressure side of the refrigeration cycle will fluctuate greatly, and the level of the pressure detection signal output from the pressure detector 3 to the controller 5 will also fluctuate accordingly. However, since the capacity down pressure value is lower than in the past, the range C in which the capacity of the parallel compression refrigerator 1 is kept constant is larger than in the past, and short cycle operation is no longer possible. Furthermore, since the capacity down pressure value is kept low, the temperature inside the showcase does not rise.

In addition, by changing the capacity down pressure value according to the number of times the compressors 1b and 1c start and stop as described above, the risk of short cycle operation of the compressor is eliminated, and the capacity down pressure value and capacity up pressure value are changed. The pressure difference can be set to a minimum.

In the above embodiment, the compressors 1b have different capacities.

Although the case of the parallel compression type refrigeration 811 equipped with 1c is shown, it can be applied to the entire refrigeration system in which the operation and stop of the compressor are controlled by pressure.

〔Effect of the invention〕

As described above, according to the present invention, the compressor wJ machine start/stop frequency detecting section detects the number of times the compressor operates within a predetermined time,
The pressure setting value of the pressure setting part is changed by the pressure setting value control part according to the number of starts and stops, and is used as the reference input of the compressor control part. -1- Cycle operation can be prevented, and as a result, compressor seizure and electric motor burnout can be prevented, and
The temperature of the cooled article becomes constant, the freshness of the article can be maintained, and power consumption can also be reduced.

[Brief explanation of drawings]

FIG. 1 is a system configuration diagram showing an example of a refrigeration system according to the present invention, FIG. 2 is a system configuration diagram of a conventional refrigeration system, and FIG. 3 is a diagram showing a region of refrigerant pressure on the low pressure side of the compressor.
FIG. 4 is an explanatory diagram of a conventional capacity control operation of a refrigeration system. -1... Parallel compression refrigerator, 1a... Condenser, lb. 1c = compressor, 2... cooling device, 2a, 2b, 2c...
Showcase, 3. Pressure detection section, 4. Pressure setting section,
5 - Control unit, 6... Compressor start/stop frequency detection unit, 7...
Pressure setpoint control section. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Masuo Oiwa (2 others) Figure 1: fEJ! L#u攬15(t 7・° し tblfl　　　Figure 2　Figure J procedural amendment (voluntary)

Claims (1)

[Claims] A refrigerator that has a compressor and a condenser connected to its discharge side, a cooling device that serves as a load for this refrigerator, a pressure detection unit that detects refrigerant pressure on the low pressure side of the refrigerator, and a refrigerant pressure that is to be converged. a pressure setting section that sets the number of times the compressor starts and stops within a predetermined period of time, a compressor start/stop frequency detection section that detects the number of times the compressor starts and stops, and changes the pressure setting value of the pressure setting section according to the number of times the compressor starts and stops. A refrigeration system comprising a pressure set value control section, and a control section that controls the compressor by inputting output signals from the pressure detection section and the pressure set value control section.