JPH04369354A - Refrigerator - Google Patents

Abstract

PURPOSE:To reduce a demand power and to reduce temperature unevenness in a chamber by providing a capacity control part to control the capacity of a capacity variable compression device based on a capacity control signal from a control part and controlling the capacity to a given capacity lower than a total capacity by means of a defrosting signal during defrosting. CONSTITUTION:The refrigerant pressure on the low pressure side of a refrigerating detected by a pressure detecting part 3 is compared with a reference value set by a pressure setting part 4. During usual operation, the capacity of a capacity variable compression device 1-1 is controlled based on a capacity control signal from a control part 5 to generate a capacity control signal for a capacity variable compression device 1-1 based on the comparing result. During defrosting operation, capacity is controlled to a given capacity lower than the total capacity of the capacity variable compression device 1-1. Thus, since the capacity of the capacity variable compression device 1-1 is controlled to capacity lower than a total capacity, a so formed freezing device reduces a consumption power compared with a conventional type and reduces production of a fluctuation in temperature in a chamber.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a refrigeration system that defrosts using a defrosting heater.

0002

[Prior Art] Conventionally, this type of refrigeration equipment was
2-771, as shown in Figure 2. In the figure, 1 is a parallel compression type refrigeration system, and 2 is a cooler 2a, 2b housed in a plurality of showcases 2-1, 2-2.
This is a cooling device configured by a combination of the above cooler 2a and
, 2b have electromagnetic valves 2c, 2d, throttle device 2e,
2f are connected sequentially. 2g is a defrosting heater disposed in the cooler 2a, and 2h is a defrosting heater disposed in the cooler 2b. The above-mentioned parallel compression type refrigeration system 1 has a compressor with a rated capacity ratio of approximately 2:1 on a liquid receiver connected to the downstream side of a water-cooled condenser 1a or an air-cooled condenser (not shown).
Two compressors, a large capacity compressor 1b and a small capacity compressor 1c selected for
The refrigerant discharge pipe 1d and suction pipe 1e of 1c and 1c 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. Also,
5 is the pressure between the detected pressure of the pressure detection unit 3 that detects the refrigerant pressure on the low pressure side and the reference value of the refrigerant pressure set in the pressure setting unit 4 that sets the reference value of 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 according to the difference. 6 is the cooler 2a, 2 during defrosting.
This is a defrosting control unit that alternately closes the electromagnetic valves 2c and 2d connected to the coolers 2a and 2b, and energizes the defrosting heaters 2g and 2h disposed in the coolers 2a and 2b. In addition, as shown in FIG. 3, the normal pressure region is the pressure setting section 4.
A capacity up pressure value, a capacity down pressure value, and a low pressure cut value are set as standard values, and a capacity up signal is sent to the parallel compression refrigeration system 1. Above the capacity down pressure value, neither a capacity down signal nor a capacity up signal is sent to the refrigeration equipment 1.
and a region c below the capacity up pressure value, a region b below the capacity down pressure value that sends a capacity down signal to the parallel compression refrigeration device 1, and a region below the low pressure cut value that sends a stop signal to the parallel compression refrigeration device 1. It is divided into four parts.

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 HP, one compressor 1
The rated capacity of compressor b is selected to be 10 HP, and the rated capacity of the other compressor 1c is selected to be 5 HP. On the other hand, multiple showcases 2-1,
In the cooling device 2 consisting of the coolers 2a and 2b housed in the showcases 2-2, the cooling load varies significantly from 0 to 100% depending on the usage status of each of the showcases 2-1 and 2-2. Here, when the refrigeration load decreases, the refrigerant pressure on the low pressure side of the refrigeration cycle decreases, and the level of the detected pressure output from the pressure detection section 3 to the control section 5 also decreases accordingly. The control unit 5 has a comparison circuit that compares the detected pressure with a reference value (capacity up pressure value or capacity down pressure value), so if the detected pressure is lower than the capacity down pressure value, In this case, the control unit 5 controls the capacity of the parallel compression type refrigeration system 1 to decrease, 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. 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 detected pressure output from the pressure detection section 3 to the control section 5 increases accordingly. As a result, when the detected pressure 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 apparatus 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. It should be noted that the time from when the pressure detection section 3 detects the pressure in area 2 or area 2 until the capacity up signal or capacity down signal outputted from the control section 5 is generated is the same. Note that if the refrigerant pressure on the low pressure side of the refrigeration cycle is below the low pressure cut value, that is, in region A, compressor 1b
, 1c are arranged to stop 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. Further, in a range where the refrigeration load is 33% to 66%, 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 1c are simultaneously operated in parallel. The transition of this capacity control operation is shown in FIG. 4. In other words, as shown in Figure 4, the rated capacity ratio of the compressor is approximately 2:1.
By selectively operating and stopping the large and small compressors selected as follows, it is possible to perform capacity control operation in four stages of 0, 33, and 66%. When the operation of the refrigeration system including the cooling device 2 configured in this way is continued, the cooling device 2
Frost forms on a and 2b. When frost occurs, the defrost control device 6 first closes the electromagnetic valve 2c of the cooler 2a and energizes the defrost heater 2g to heat the cooler 2a and perform defrosting. When the defrosting of the cooler 2a is completed, the other cooler 2b
Defrosting is started, the solenoid valve 2d of the cooler 2b is closed, and the defrosting heater 2b is energized to defrost the cooler 2b.

0004

[Problem to be Solved by the Invention] Since the conventional refrigeration system is constructed as described above, during defrosting, the defrosting heater of one cooler is energized and multiple compressors are operated simultaneously. There were problems such as a large amount of electricity was required, the contracted electricity amount increased, and the temperature inside the refrigerator fluctuated.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a refrigeration system in which internal temperature fluctuations are small and contract power consumption can be reduced.

[0006]

[Means for Solving the Problems] A refrigeration system according to the present invention compares the low-pressure side refrigerant pressure of the refrigeration circuit detected by the pressure detection section with a reference value set by the pressure setting section, and based on the comparison result. Under normal conditions, the capacity of the variable capacity compression device is controlled based on the capacity control signal of the control unit that generates the capacity control signal of the variable capacity compression device, and during defrosting, the capacity of the variable capacity compression device is controlled at a predetermined capacity smaller than the total capacity of the variable capacity compression device. The capacity is controlled according to the capacity.

[0007]

[Function] In the refrigeration system of the present invention, the capacity of the variable capacity compression device is controlled to a capacity smaller than its total capacity during defrosting, so power consumption is lower than that of conventional systems, and the temperature inside the refrigerator is reduced. Fluctuations become smaller.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A configuration diagram of a refrigeration system according to an embodiment of the present invention shown in FIG. 1 will be explained below. 1, the difference from FIG. 2 is that the capacity of the variable capacity compression device 1-1 consisting of compressors 1b and 1c is controlled based on the output signal of the control unit 5, and during defrosting, the output signal from the defrosting control unit 6 is controlled. The point is that a capacity control section 7 is provided which forcibly stops one of the compressors 1b and 1c in response to a defrosting signal.

Next, the operation will be explained. Pressure detection part 3
The low-pressure side refrigerant pressure of the refrigeration circuit 1 detected in the controller 5 is compared with the reference value (capacity increase pressure value, capacity decrease pressure value, etc.) shown in FIG. When the pressure is lower than the pressure value, that is, in the case of region B, a capacity down signal is output from the control unit 5, and the capacity control unit 7 controls the variable capacity compressor 1 based on this capacity down signal.
-1 capacity is controlled to decrease. For example, when the 10 HP compressor 1b is being operated independently, the compressor 1b is stopped and the 5 HP compressor 1c is operated, thereby lowering the refrigerating capacity. As the refrigerating capacity decreases, the refrigerant pressure on the low-pressure side of the refrigerating circuit 1 increases, converges to region C, and the operation becomes stable. Furthermore, when the refrigerant load increases, the low-pressure side refrigerant pressure of the refrigeration circuit 1 increases, and the detected pressure of the pressure detector 3 increases accordingly. This detected pressure is compared with the reference value shown in FIG. 3 in the control unit 5, and if it is higher than the capacity up pressure value, that is, in the cold region 2, the control unit 5 outputs a capacity up signal, and the capacity control unit 7 controls the capacity of the variable capacity compression device 1-1 to increase based on this capacity up signal. For example, when the compressor 1b is operated independently, the operation of the compressor 1c is added, and the compressor 1b,
1c are operated in parallel at the same time, increasing the refrigerating capacity. As the refrigerating capacity increases, the refrigerant pressure on the low-pressure side of the refrigerating circuit 1 decreases, converging to the cold region C, and the operation becomes stable. If the operation of the refrigeration system configured as described above is continued, frost will form on the coolers 2a and 2b, and the defrost signal will be output from the defrost control unit 6. The solenoid valve 2c connected to is closed and the defrosting heater 2g is energized. This energization heats the cooler 2a and defrosts it. When the defrosting of the cooler 2a is completed, the defrosting of the other cooler 2b is subsequently performed in the same manner. On the other hand, in response to the defrost signal output from the defrost control unit 6, the capacity control unit 7 forcibly stops one of the compressors 1b and 1c until the end of defrosting, and the capacity of the variable capacity compressor 1-1 is reduced to that level. The capacity is controlled to be smaller than the full capacity.

In the above embodiment, the variable capacity compressor 1-1 is composed of a plurality of compressors, and the capacity control unit 7 controls the operation and stop of the plurality of compressors. Although the capacity is controlled in the above description, the present invention is not limited to this. For example, a variable capacity compression device consisting of one compressor whose capacity is controlled by inverter control or unloader control can be controlled by the capacity control unit 7 to adjust the frequency of the inverter. Alternatively, the number of idle cylinders of the multi-cylinder compressor may be controlled and the capacity thereof may be controlled in the same manner as described above, and the same effects as in the above-mentioned embodiments can be obtained.

[0011]

[Effects of the Invention] As described above, according to the present invention, since the capacity of the variable capacity compression device is controlled to a predetermined capacity smaller than the total capacity during defrosting, contract power can be reduced, and This has the effect of reducing internal temperature changes.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a refrigeration system according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a conventional refrigeration system.

FIG. 3 is a diagram showing a region of refrigerant pressure on the low pressure side of the refrigeration circuit.

FIG. 4 is an explanation of capacity control operation of the refrigeration system.

[Explanation of symbols]

1 Refrigeration circuit 1a Condenser 1b Compressor 1c Compressor 1-1 Variable capacity compression device 2-1 Showcase 2-2 Showcase 2a Cooler 2b Cooler 2c Solenoid valve 2d Solenoid valve 2e Squeezing device 2f Aperture device 2g Defrost heater 2h Defrost heater 3 Pressure detection part 4 Pressure setting section 5 Control section 6 Defrost control section 7 Capacity control section

Claims (1)

[Claims] 1. A variable capacity compression device; a condenser that condenses and liquefies refrigerant discharged from the variable capacity compression device;
A refrigeration circuit includes a plurality of electromagnetic valves that expand and evaporate the refrigerant sent out from the condenser, a throttle device, and a cooler, which are connected by piping in order to form a closed circuit, and the plurality of coolers. The defrosting heaters installed in the respective coolers generate a defrosting signal during defrosting, and the solenoid valves respectively connected to the plurality of coolers are alternately closed. a defrost control unit that energizes the frost heater; a pressure detection unit that detects the low pressure side refrigerant pressure of the refrigeration circuit;
A pressure setting section that sets a reference value for the low-pressure side refrigerant pressure of the refrigeration circuit, and a pressure detection section that compares the detected pressure detected by the pressure detection section with the reference value, and based on the comparison result, the capacity of the variable capacity compression device. a control section that generates a control signal; and a control section that controls the capacity of the variable capacity compression device based on the capacity control signal of the control section, and also controls the capacity of the variable capacity compression device based on the defrosting signal during defrosting from the total capacity of the variable capacity compression device. A refrigeration system comprising: a capacity control section that controls the capacity to a predetermined capacity that is small.