JPS63189744A - 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 relates to a refrigeration system, and particularly to a refrigeration system that ensures the freshness of objects to be cooled and effectively removes oil mixed in the refrigerant. This relates to a refrigeration device that returns fζ.

[Conventional technology]

Conventionally, there has been a device of this type as shown in FIG.

In Fig. 2 polyζ, (1) is a parallel compression refrigeration system, (2
) is multiple units Osi=1-case (2a), (2b), (
This is a cooling device configured with the combination of 2c). The parallel compression refrigeration system (1) is a water-cooled condenser (1a) or an air-cooled condenser i@! A large capacity compressor (1b) and a small capacity compressor (1c) are selected in which the rated capacity ratio of the compressors is approximately 2 to 1, depending on the liquid receiving pipe connected downstream of the compressor (not shown). )
Two compressors (1b) are installed in parallel, and each compressor (1b)
and (IC) refrigerant discharge pipe (1d) and suction pipe (1e)
are connected in parallel with each other. Note that (1f) is a pressure equalizing oil pipe that connects the crank chambers of each compressor (lb) and (IC) with each other.

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

(7) is E-book compression a (tb), (lc),
This is a compressor single-lung operating time integration unit that integrates the time when only one compressor is in operation. In addition, (6) means that when the compressor independent operation time calculator (7) reaches a predetermined time, the compressor (l
b), (lc) are both stopped for a certain period of time, and the cumulative time of the compressor independent operation time integration section (7) is set to 0, and if the rated capacities of the two compressors (xb) are different,
This is the compressor capacity setting unit that starts the operation of (lc).

In addition, as shown in FIG. 8, the normal pressure region is determined by the parallel compression refrigeration system ( Capacity A9, which sends an up signal to the tank pressure (in the area above the tube pressure value), and a parallel compression refrigeration device (1)
Region (c) above the capacity down pressure value where neither a capacity down signal nor a capacity up signal is issued and less than the capacity up pressure value (c), and a region below the capacity down pressure value where a capacity down signal is issued to the parallel compression refrigeration system (1). It can be divided into four regions: the region (b) where the pressure is below the low pressure cut value that sends a stop signal to the parallel compression refrigeration system Kl (1) (a).

Next, the operation will be explained. For example, cooling device (2)
When the required power to obtain the required refrigerating capacity for the refrigerating load is 15)P, the rated capacity of one compressor (lb) is 1OH) and the rated capacity of the other compressor (1c) is 6H) has been selected.

On the other hand, multiple showcases (2a), (2b), (
In the cooling device (2) consisting of 2c), the cooling load varies greatly from 0 to 100% depending on the usage status Sζ 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 section (3)
The level of the pressure detection signal outputted 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 rM@ is lower than the capacity down pressure value. That is, in the case of the region (CI), the control unit (5) controls the capacity of the parallel compression type refrigeration system (1) to be low F, and increases the cooling capacity by F. 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.

In addition, when the cooling load is high, the refrigerant pressure on the low pressure side of the refrigeration cycle increases, and the pressure detection part (3) increases.
Karasei i1 gI! (5) The level of the pressure detection signal outputted increases. As a result, if the pressure detection signal is higher than the capacity-up pressure value (in other words, in the area), the control unit (5) controls the parallel compression refrigeration system (1) to increase its capacity, Increase 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 region (c), and the operation becomes stable. In addition, after the pressure detection section (3) detects the pressure in the area) or area (b), the time at which the capacity up signal or capacity down signal output from the control unit (5) is generated is the same. It is.

In addition, 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), the compressor (lb
), (lc) are designed to stop immediately.

Therefore, for the refrigeration load fluctuation in L, the refrigeration load is 8
Only the compressor (1'c) with a part-load time moss rated capacity ffi 5 )P of less than 8% is operated independently. Also, when the refrigeration load is in the range of 88 to 66%, the rated capacity! :10) Only the compressor (1b) of P is operated independently.

Furthermore, when the refrigeration load reaches 66 to 100%, the compressor (1
b) and (lc) are operated in parallel at the same time. The transition of this capacity control operation is shown in FIG. 4.

In other words, as shown in FIG. 4, by selectively controlling the operation and stopping of large and small compressors whose rated capacity ratio is selected to be approximately 2:1, 0.1lll11
．． Capacity control operation can be performed in four stages of 66 and 100%.

In general, in compressors that compress refrigerant to high temperature and high pressure, the lubricating oil of the compressor is 0.5 to 1% in terms of ζ weight ratio in the refrigerant.
Mixed. This mixed lubricating oil mixes well with the refrigerant when the refrigerant is in a liquid state, but when the refrigerant is vaporized, it does not mix with the refrigerant and separates. Therefore, in conventional refrigeration systems, the lubricating oil mixed in the refrigerant does not return to the compressor, as will be explained next, and the lubricating oil in the compressor sometimes decreases.

In conventional refrigeration equipment, for example, a cooler (2a) is provided in each of a plurality of cooled parts, such as a showcase.

In a refrigeration system equipped with (2b) and (2c), in order to control the temperature of each showcase (v1), each showcase is equipped with a warm regulator and a liquid line solenoid valve that controls the flow of refrigerant. , the temperature of each showcase was controlled.In this case, for example, there were 8 showcases, and 8
In a refrigeration system that individually controls each showcase,
Due to load reduction at night, only one cooling unit W (2a) may be operated for a long time.

At this time, the load has been reduced, so the refrigeration system operates with the evaporation temperature of cooling 'a (2a) lowered, and the refrigerant gas flow rate in the suction pipes of the compressors (lb) and (lc) increases. decreases. When the refrigerant gas flow rate decreases, the lubricating oil separated from the refrigerant gas does not return well to the compressor (RB), (LC), and the lubricating oil in the compressor (LB), (LC) decreases, causing the compressor to There was a risk that sliding parts such as bearings would burn out.

In addition, the above cooling i! If the suction pipe diameter of the compressors (tb) and (xc) is made smaller to ensure the refrigerant gas flow rate in anticipation of a reduction in the operating load on one of the coolers (2a) to (2b), ), (2c) When eight units are operated under heavy load, the refrigerant gas flow rate becomes extremely low, and the pressure loss in the suction pipes of the compressors (lb) and (IC) becomes extremely large. For this reason, the compression capacity of the compressors (lb) and (lc) is reduced, and the refrigeration capacity of the refrigeration system is reduced.

In order to eliminate such drawbacks, Cζ, as mentioned above, changes the capacity of the refrigeration system according to the refrigerant pressure on the low-pressure side of the refrigeration cycle and maintains the evaporation temperature on the suction side constant, so-called capacity control operation. By doing so, the load is reduced and the pressure on the suction side decreases due to the heat (lb).

Of (1c), the time during which only one compressor operates is accumulated by the compressor independent operation time accumulating unit (7), and when the value reaches a predetermined time, the compressor capacity setting unit (6) (
Both lb) and (lc) are stopped for a certain period of time, and the calculation time of the compressor independent operation time calculation section (7) is reduced to O.
And if the rated condition is different, the pressure of two units wMl! ! 1(
lb) and (IC) are to be operated in parallel. That is, when the compressors (lb) and (lc) are stopped for a certain period of time, the liquid refrigerant on the high pressure side returns to the low pressure side, increasing the refrigerant pressure on the low pressure side, and the compressor (lb).

When the (IC) restarts operation, the flow rate of refrigerant gas in the suction pipe increases, and the lubricating oil accumulated in the suction pipe during low-load operation is returned to the compressors (lb) and (lc). ,
A decrease in the oil inside the compressors (tb) and (lc) is prevented.

[Problem that the invention seeks to solve]

Since the conventional refrigeration equipment is configured as described above, 2
When only one of the compressors is operating for a predetermined time, the two compressors stop and the freshness of the cooled material is not maintained.

This invention was made in order to solve the conventional problems as described in E. The time during which the compressor is stopped is kept as short as possible to maintain the freshness of the material to be cooled, and also to prevent the accumulation of water in the suction pipe. An object of the present invention is to provide a refrigeration system that effectively returns lubricating oil to a compressor.

[Means to solve the problem]

In this 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 refrigerant pressure is above or below the desired refrigerant pressure and generates a capacity control output signal to control the capacity of the refrigerator, and a control unit that determines whether the refrigerant pressure is above or below the desired refrigerant pressure, and a control unit that generates a capacity control output signal to control the capacity of the refrigerator, and a control unit that determines whether the refrigerant pressure is above or below the desired refrigerant pressure. When the cumulative time of the compressor independent operation time accumulating section and the parallel compressor independent operation time accumulating section reach a predetermined time, both compressors are stopped for a certain period of time and the parallel compressor independent operation time is integrated. The compressor capacity setting section sets the integrated time of the section to 0 and starts operation of the two compressors, and when the continuous parallel operation time of the two compressors reaches a predetermined time, the parallel compressor is set to 0. The above object is achieved by configuring the refrigeration system by providing a compressor independent operation time correction section that sets the accumulated time of the operation time accumulation section to 0.

[For production]

In the refrigeration system according to the present invention, when the continuous parallel operation time of the two compressors reaches a predetermined time, the function of the compressor independent operation time correction section causes the integrated compressor independent operation time integration section to adjust the accumulated time. 0, the time during which the compressor is stopped can be made as short as possible, the freshness of the object to be cooled can be maintained, and the lubricating oil accumulated in the suction pipe can be effectively returned to the compressor.

〔Example〕

FIG. 1 is a configuration diagram showing one embodiment of the refrigeration system of the present invention, and the same parts as in FIG. 2 are indicated using the same symbols. In FIG. It is a correction section, and the above two compressors (1b
) and (lc) reach a predetermined time, the cumulative time of the parallel compressor individual operation time calculating section (7) is set to zero.

Next, the operation will be explained. h Distribution compressor independent operation time product nose part (7) Te is pressure distribution fi (A', (lb), (l
Of c), calculate the time when only one vehicle is operating,
For example, at 48 minutes, the compressor capacity setting unit (6) stops both of the compressors m (tb) and (IC) for a certain period of time, for example, 8 minutes, and calculates the individual reversal time of the L compressor. The cumulative time (48 minutes) of part (7) is set to 0, and the above two compressors (lb) and (lc) have different rated capacities.
) is started in parallel operation. By the way, the LE compression independent operation time correction unit (8) in L indicates that two compressors (lb), (lc
) for a predetermined period of time, e.g. 1
When o minutes have passed, the compressor independent operation time product nose part (7
) even if the cumulative time is 48 minutes, the cumulative time of the sliding compressor independent operation time cumulative part (7) is reset to 0 and the cumulative time is calculated from 0.

Therefore, the time for stopping compression () is kept as short as possible, preserving the freshness of the material to be cooled, and compressing b'
A (lb) - (lc) Q) Stoppage for a certain period of time,
The liquid refrigerant on the high-pressure side returns to the low-pressure side, increasing the refrigerant pressure on the low-pressure side, and when the pressure @ machine (lb) and (lc) restart operation, the flow rate of refrigerant gas in the suction pipe increases, resulting in low-load operation. At the same time, the lubricating oil that has accumulated in the suction pipe is removed using a pressure wj machine (lb).

(lc) - by returning air to the E-distributor compressor (lb
).

(lc) Internal temperature) Reduction of R oil can be prevented.

In addition, in Example L, two compressors are used to control the capacity, but even when changing the output frequency of the inverter to open up the capacity of the compressor, oil mixed in the refrigerant can be removed. In order to effectively return the compressor to the compressor, the time during which the output frequency of the compressor is operated at a predetermined value, for example, 408Z or less, is accumulated, and when the value reaches a predetermined value, for example, 48 minutes,
After stopping the L compressor for a certain period of time, for example, 8 minutes,
Two compressors start running in parallel. When the continuous parallel operation time reaches a predetermined time, for example, 10 minutes, the same effect can be obtained by setting the cumulative time of the low frequency operation time calculation section of the compressor to 0.

〔Effect of the invention〕

As explained hereafter, in the refrigeration system of the present invention, the refrigerant pressure on the low pressure side of the refrigeration cycle is detected by the pressure detection section, a pressure detection signal is generated, and the refrigerant pressure is set by the refrigerant pressure setting section for convergence. , determine whether the pressure detection signal is above or below the refrigerant pressure to be converged;
A control unit that generates a capacity control output @ number for controlling the capacity of the refrigerator, a compressor independent operation time accumulation unit that accumulates the time during which only one compressor is operating, and a side compressor. When the independent operation time accumulator reaches a predetermined time, both compressors are stopped for a certain period of time, and the accumulated time of the parallel compressor independent operation time accumulator is set to 0, and the two compressors listed in E are operated. A compressor capacity setting unit starts the operation, and when the continuous parallel operation time of the two compressors reaches a predetermined time, a compressor independent operation time correction unit sets the accumulated time of the compressor independent operation time accumulation unit to 0. Since the compressor is equipped with a section, the time during which the compressor is stopped can be kept as short as possible, the freshness of the cooled material can be maintained, and the lubricating oil that has accumulated in the suction pipe can be effectively returned to the compressor. Can be done.

[Brief explanation of the drawing]

1N is a block diagram showing an embodiment of the refrigeration system according to the present invention, FIG. 2 is a block diagram showing a conventional refrigeration system, FIG. 3 is a diagram showing the refrigerant pressure region on the low pressure side, and FIG. 2 is an explanatory diagram of capacity control operation of the refrigeration system in FIG. 2. FIG. In the figure, (Ia) is a condenser, (1b) and (lc) are compressors, (2a) to (2c) are coolers, (3) is a pressure detection section, (4) is a pressure setting section, and (5) is a pressure detection section. ) is a control section, (6) is a compressor capacity setting section, (7) is a compressor independent operation time integration section, and (8) is a compressor independent operation time correction section. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 2, each having a suction pipe and a discharge pipe connected in parallel;
A refrigeration system in which a single compressor, a condenser that condenses and liquefies the refrigerant discharged from these compressors, and a cooler that evaporates and vaporizes the refrigerant sent out from this condenser are connected by piping in order to form a closed circuit. 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, and a pressure that sets the convergence pressure value of the refrigerant pressure on the low pressure side that is to be converged. a setting unit, a control unit that determines whether the pressure detection signal is greater than or equal to the convergence pressure value and generates a capacity control output signal for controlling the capacity of the refrigerator based on the determination result; and the compressor. When the cumulative time of the compressor independent operation time accumulator reaches a predetermined time, both of the compressors are stopped for a certain period of time, and A compressor capacity setting unit that sets the cumulative time of the compressor independent operation time integration unit to 0 and starts operation of the two compressors, and a continuous parallel operation time of the two compressors reaches a predetermined time. A refrigeration system comprising: a compressor independent operation time correction section that sets the accumulated time of the compressor independent operation time accumulation section to zero.