JPH0784953B2 - Refrigeration equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is, for example, a refrigerating apparatus used in a plurality of refrigerating / freezing shaving cases installed in the same place such as a supermarket, that is, a load fluctuation is large. The present invention relates to a refrigerating device that can be always operated in an optimum state.

[Conventional technology]

As a conventional refrigerating apparatus of this type, there is one shown in FIG. In FIG. 2, (1) is a parallel compression type refrigerating apparatus, and (2) is a cooler (2
This is a cooling device composed of a combination of a), (2b), and (2c).

The parallel compression type refrigeration system (1) has a rated capacity ratio of about 2 pairs on a receiver connected downstream of a water-cooled condenser (1a) or an air-cooled condenser (not shown). Two high-capacity compressors (1b) and small-capacity compressors (1c) selected in No. 1 are installed in parallel, and the refrigerant discharge pipes of each compressor (1b) and (1c) ( 1d) and the suction pipe (1e) are connected in parallel with each other.

Note that (1f) is a pressure equalizing and equalizing pipe that connects the crank chambers of the compressors (1b) and (1c) to each other.

Further, (5) is the refrigerant pressure set by the pressure setting section (4) for setting the low-pressure side refrigerant pressure to be converged with the output signal of the pressure detection section (3) for detecting the low-pressure side refrigerant pressure. Operate compressors (1b) and (1c) individually according to the pressure difference between
It is a control unit that controls the stop.

Further, as shown in FIG. 3, the normal pressure region is a capacity up pressure value set by the pressure setting unit (4),
The volume down pressure value and the low pressure cut value are three, and the volume down to the parallel compression type refrigeration system (1) and the area D above the capacity up pressure value for outputting the capacity up signal to the parallel compression type refrigeration system (1). Area C where the signal or capacity up signal is not output and is higher than the capacity down pressure value and lower than the capacity up pressure value,
It is divided into four areas, i.e., a region b below which the capacity down pressure value is output to the parallel compression type refrigeration system (1) and a low pressure cut value below which the stop signal is issued to the parallel compression type refrigeration device (1). .

Next, the operation will be described. For example, when the required power for obtaining the required refrigerating capacity for the refrigerating load of the cooling device (2) is 15, the rated capacity of one compressor (1b) is 10 and the rated capacity of the other compressor (1c) is 5 Has been selected.

On the other hand, in the cooling device (2) including a plurality of coolers (2a), (2b), and (2c), the cooling load greatly changes from 0 to 100% depending on the usage status of each canoe case.

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 unit (3) to the control unit (5) also decreases accordingly.

Since the control unit (5) has a comparison circuit for comparing the pressure detection signal with a reference value (capacity up pressure value or capacity down pressure value), when the pressure detection signal is lower than the capacity down pressure value, That is, in the case of region B, the control unit (5) controls so that the capacity of the parallel compression refrigeration system (1) is reduced, and the cooling capacity is reduced.

In this way, when the cooling capacity is lowered, the refrigerant pressure on the low pressure side of the refrigeration cycle rises, converges to the 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 rises, and the level of the pressure detection signal output from the pressure detection unit (3) to the control unit (5) accordingly increases. To rise.

As a result, when the pressure detection signal is higher than the capacity up pressure value, that is, in the case of region D, the control unit (5) controls so that the capacity of the parallel compression type refrigeration (1) is increased,
Increase cooling capacity.

In this way, when the cooling capacity is increased, the refrigerant pressure on the low pressure side of the refrigeration cycle is reduced, converges to the area C, and the operation is stabilized.

The time from when the pressure detection unit (3) detects the pressure in the area D or the area B until the capacity up signal or the capacity down signal output from the control unit (5) is the same.

When the refrigerant pressure on the low-pressure side of the refrigeration cycle is less than or equal to the low-pressure cut value, that is, when it reaches the area A, the compressor (1b),
(1c) is designed to stop immediately.

Therefore, the refrigeration load is 33
Compressor with a rated capacity of 5 (1c) at a partial load of less than 1%
Only is operated alone.

Further, when the refrigeration load is in the range of 33 to 66%, only the compressor (1b) having a rated capacity of 10 is operated independently.

Furthermore, if the refrigeration load reaches 66-100%, the compressor (1b)
And (1c) are operated in parallel at the same time. The transition of this capacity control operation is shown in FIG.

That is, as shown in FIG. 4, by selectively operating and stopping large and small compressors whose rated capacity ratio of the compressor is selected to be approximately 2: 1, 0,33 , 66,100
It is possible to perform capacity control operation in four stages of%.

[Problems to be Solved by the Invention]

Since the conventional refrigerating apparatus is configured as described above, the region where the refrigerant pressure is equal to or higher than the capacity down pressure value which does not output the capacity down signal or the capacity up signal to the parallel compression refrigeration apparatus 1 and is lower than the capacity up pressure value. If it is within the range (c), even if the refrigerant pressure is close to the capacity down pressure value, continuous operation is performed with the same capacity, which is contrary to energy saving operation.

The present invention has been made in order to solve such a problem, and an object thereof is to obtain a refrigerating apparatus in which energy can be saved without impairing the freshness of an object to be cooled.

[Means for Solving the Problems]

The refrigerating apparatus according to the present invention detects the refrigerant pressure on the low pressure side of the refrigeration cycle by the pressure detection unit to generate a pressure detection signal, and sets the refrigerant pressure to be converged by the pressure setting unit, and also the pressure detection signal. Is higher or lower than the refrigerant pressure to be converged, and the control unit that generates the output signal for capacity control for performing the capacity control of the refrigerator and the output signal for capacity control generated by the control unit are constant A compressor capacity setting unit that generates a capacity control output signal that reduces the capacity of the refrigerator by one rank when it does not change with time is provided.

[Action]

In the present invention, when the capacity control output signal generated by the control section by the compressor capacity setting section does not change for a certain period of time, the capacity control output signal for reducing the capacity of the refrigerator by one rank is generated. It works to save energy without compromising the freshness of the product.

〔Example〕

Embodiments of the refrigerating apparatus 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. The same parts as those in FIG. 2 are designated by the same reference numerals, and the description thereof will be omitted. The parts different from those of FIG. 2 will be mainly described.

In FIG. 1, the portions indicated by reference numerals (1) to (5) are the same as those in FIG. 2, and a compressor capacity setting unit indicated by reference numeral (6) is newly added to the configuration of FIG. Is.

That is, the compressor capacity setting unit (6) generates a capacity control output signal for reducing the capacity of the refrigerator by one rank when the capacity control output signal generated by the control unit (5) does not change for a certain period of time. It has the function of

Next, the operation of the refrigerating apparatus of the present invention will be described. Due to the output signal for capacity control generated from the control unit 5, the refrigerant pressure is such that the compressor (1b), (1c) is operating, and the refrigerant pressure does not output the capacity down signal or the capacity up signal to the parallel compression refrigeration apparatus 1. When the value is equal to or more than the value and less than the capacity up pressure value, for a continuous period of, for example, 20 minutes, the compressor capacity setting unit (6) stops the compressor (1c) to stop the compressor. It is beginning to change to the independent operation of (1b).

〔The invention's effect〕

As described above, the refrigerating apparatus according to the present invention detects the refrigerant pressure on the low pressure side of the refrigeration cycle by the pressure detecting unit to generate a pressure detection signal, and sets the refrigerant pressure to be converged by the pressure setting unit. , A control unit for determining whether the pressure detection signal is above or below the refrigerant pressure to be converged, and generating a capacity control output signal for controlling the capacity of the refrigerator, and a capacity generated by this control unit When the control output signal does not change for a certain period of time, energy can be saved without impairing the freshness of the object to be cooled that generates the capacity control output signal that reduces the capacity of the refrigerator by one rank.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of a refrigeration system of the present invention, FIG. 2 is a diagram showing a configuration of a conventional refrigeration system, and FIG. 3 is a refrigerant pressure on a pressure side in the refrigeration system of FIG. FIG. 4 is a diagram showing a region, and FIG. 4 is an explanatory diagram of capacity control operation of the refrigerating apparatus of FIG. In these figures, (1a) is a condenser, (1b), (1c)
Is a compressor, (2a) to (2c) are coolers, (3) is a pressure detection unit, (4) is a pressure setting unit, (5) is a control unit, and (6) is a compressor capacity setting unit. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A plurality of compressors each having a suction pipe and a discharge pipe connected in parallel, a condenser for condensing and liquefying a refrigerant discharged from these compressors, and a refrigerant discharged from this condenser. A refrigerating circuit in which the cooler to be vaporized is sequentially connected to form a closed circuit, a pressure detection unit 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, convergence A pressure setting unit that sets the convergent pressure value of the refrigerant pressure on the low pressure side to be made, determines whether the pressure detection signal is greater than or equal to the convergent pressure value, and generates an output signal based on the determination result. , A controller for generating a capacity control output signal for performing capacity control of the refrigerator based on this output signal, and if the capacity control output signal generated by the controller does not change for a certain period of time, Refrigerating device including a compressor capacity setting section for generating a capacity control output signal to reduce one rank capacity of the machine.