JPH0448164A - Freezer device - Google Patents

Abstract

PURPOSE:To enable an energy saving and freshness keeping operation to be attained by a method wherein at least one of a plurality of compressors is of a variable volume type, the load of compressor is discriminated in response to a set value corrected in response to a selected operation mode and correspondingly an operating state of the compressor is determined. CONSTITUTION:Volume of a compressor 30A is automatically changed in response to a load during a concurrent operation of a variable volume type compressor 30A and a positive volume type compressor 30B. A set pressure of a set value inputting means 51 is corrected in response to an inputting of a selection means 52 with a set value correcting means 53. As the concurrent operation of the compressors continues for a set period of time, a degree-of-opening setting means 43 causes a degree of opening of a control valve 36 to be zero during the set time, the compressor 30A is operated in a full-load state, a total capability of the compressors is increased more than the load, a low pressure is detected by a sensor 38. A discriminating means 47 compares a corrected set pressure. If the value is not the low load, a concurrent operation is carried out with an operation state determining means 48. If the load is a low load, the operation only with the compressor 30A is carried out. Subsequently, the operation state is determined by an output of the sensor.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a refrigeration device suitable for a refrigeration showcase or the like.

(Prior Art) Refrigerating showcases and the like operate in a standard operating mode in which the refrigeration equipment is operated so that the temperature inside the showcase matches a set temperature arbitrarily set by the user, as well as in an energy-saving operating mode and an energy-saving operating mode for saving energy. A system has been proposed in which a freshness operation mode can be selected to maintain the freshness of the cooled objects stored in the storage case.

In energy-saving operation, the set temperature is set higher than that in the standard operation mode, thereby increasing the percentage of the compressor's stop time in ON-OFF operation, thereby saving energy consumed by the compressor.

In the freshness operation mode, by setting the set temperature lower than that in the standard operation mode, the number of times the compressor is stopped is reduced, and fluctuations in the temperature inside the case are reduced.

(Problem to be solved by the invention) However, at least one of the plurality of compressors installed in parallel in the refrigerant circuit is a variable displacement compressor whose capacity automatically changes according to the refrigeration load. In refrigerated showcases, the capacity of the variable capacity expansion compressor changes automatically according to the refrigeration load, and the number of operating compressors increases or decreases, so it is difficult to implement the energy saving operation mode or freshness operation mode. The problem was that it was difficult.

(Means for Solving the Problems) The present invention was invented to solve the above problems, and its gist is to At least one of them has variable capacity expansion pressure that automatically changes capacity depending on the refrigeration load!
In the refrigeration system, there is provided a selection means for selecting a plurality of operation modes, a set value correction means for automatically correcting a set value in accordance with the operation mode selected by the selection means, and a set value for the set value. It has a determining means for determining the load of the compressor based on the set value corrected by the correcting means, and an operating mode determining means for determining the operating mode of the plurality of compressors according to the determination result of the determining means. A refrigeration system characterized by being provided with a control device.

(Function) Since the present invention has the above configuration, the set value is automatically corrected in accordance with the selected operation mode,
The load of the compressor is determined based on the corrected setting value, and the operating mode of the plurality of compressors is determined according to the result of this determination.

Embodiment One embodiment of the invention is shown in FIGS. 1-3.

FIG. 1 shows a system diagram of the refrigeration system, and the high temperature and high pressure refrigerant gas discharged from the variable capacity expansion compressor 30A and constant capacity compressor 30B, which are installed in parallel in the refrigerant circuit, is
As shown by the arrow, the refrigerant enters the condenser 31, where it is condensed and liquefied to become a high-pressure liquid refrigerant.

This liquid refrigerant enters a throttling mechanism 32 consisting of a capillary tube, an expansion valve, etc., where it is throttled and adiabatically expanded to become a gas-liquid two-phase. Next, this refrigerant enters the generator 33, where it is vaporized and becomes a low-temperature, low-pressure refrigerant gas that is circulated to the compressors 30A and 30B.

A bypass pipe 35 that connects the suction pipe 34 to the working chamber of a variable capacity mechanism, which will be described later, built into the variable capacity compressor 308.
A control valve 36 is interposed therein.

A sensor 37 and a low pressure sensor 38 are attached to the suction pipe 34 to detect the pressure or temperature of the refrigerant flowing therein, that is, the refrigeration load.
The output of 8 is input to the controller 40. Selection means 52 and set value input means 51 for selecting an operation mode
A command from is input to the controller 40. and,
The opening degree of the control valve 36 is controlled by the command from the controller 40, and the driving motor 39A of the variable displacement compressor 1130A and the driving motor 39B of the constant displacement carving m 1130B are started or stopped. There is.

FIG. 3 shows the variable capacity mechanism of the variable capacity expansion and compressor 3OA.

In FIG. 3, 1 is a cylinder, 2 is a piston, 3 is a valve plate, 4 is a cylinder head, 5 is a suction cavity, 6 is a suction valve, 7 is a discharge valve, 8 is a discharge chamber, 9 is an unloader cylinder, 10 2 is an unloader piston, 23 is a seal ring, 25 is a piston ring, and 26 is a washer.

The lower end of the unloader cylinder 9 is fixed to the valve plate 3, and the upper end is covered by a cover 20.

An unloader piston 10 is placed inside this unloader cylinder 9.
By sealingly and slidably fitting the unloader piston IO, an operating chamber 6 and a chamber 19 are defined below the unloader piston IO. And this chamber 19 has an opening 18
The working chamber 16 communicates with the discharge chamber 8 through a throttle hole 24 formed in the cover 20 . Further, the working chamber 16 includes a pressure impulse pipe 15, a valve plate 3
It communicates with a bypass pipe 35 via a passage 21 bored in the.

When the piston 2 moves back, the refrigerant gas passes through the suction passage 11 formed in the valve plate 3 from the suction cavity 5, pushes open the suction valve 6, and is sucked into the gas compression chamber 12.

When the piston 2 moves forward, the refrigerant gas in the gas compression chamber 12 is compressed, pushes the discharge valve 7 open, enters the discharge chamber 8 through the passage B13, and is discharged from there through a discharge pipe (not shown).

The refrigerant gas in the gas compression chamber 12 flows into the chamber 19 through the opening 18 . On the other hand, the discharge gas in the discharge chamber 8 flows into the working chamber 16 through the throttle hole 24 . Then, the gas in the working chamber 16 flows out into the suction pipe 34 through the pressure guiding pipe 15, the passage 21, the control valve 36, and the bypass pipe 35.

By controlling the flow rate of gas passing through the bypass pipe 35 with the control valve 36, the pressure within the working chamber 16 can be set to an arbitrary pressure.

Thus, the unloader piston 10 moves up and down depending on the difference between the pressure acting on the working chamber 16 and the average cylinder pressure acting on the chamber 19, and the top formed by the chamber 19 and the opening 18 moves up and down depending on this up and down position. The clearance volume changes, and accordingly, the capacity of the variable capacity expansion-compressor 30A changes continuously and steplessly.

FIG. 2 shows a functional block diagram of the controller 40.

The pressure or temperature of the refrigerant gas flowing in the suction pipe 34 detected by the sensor 37 is determined by the comparison means 4 of the controller 40.
1 and is compared with the setting value input from the setting means 42, thereby calculating the deviation between the two. This deviation is input to the opening degree determining means 43, where the opening degree of the control valve 36 is determined according to the control rule inputted from the storage means 44. Note that the storage means 44 stores control rules (for example, PID control, table comparison control, fuzzy control, etc.) for determining the opening degree of the control valve 36 in accordance with the deviation and its rate of change. The determined opening degree is outputted to the control valve 36 via the output means 45, and the control valve 36 becomes the determined opening degree, and accordingly, the variable displacement compression 11
The capacity of 3OA is determined.

During simultaneous operation of the variable capacity expansion compressor 30A and the constant capacity compressor 30B, the variable capacity expansion compressor 3
The capacity of 0A is automatically changed so that the total compression capacity, which is the sum of the compression capacities of these compressors 30A and 30B, matches the refrigeration load, and the low pressure is maintained constant.

The set pressure input from the set value input means 51 is input to the set value correction means 53 of the controller 40, where it is corrected according to the input from the selection means 52.

For example, if the energy saving operation mode is selected by the selection means 51 when the set pressure is 2/-, the set pressure is 0,3
Eyelids/- When the pressure is corrected to a higher value of 2.3 kg/cj and the freshness operation mode is selected, the set pressure is corrected to a lower value of 1.7 kg/aJ by 0.3 kr/d.

When the simultaneous operation of the variable capacity expansion compressor 30A and the constant capacity compressor 30B continues for a certain period of time preset in the time setting means 46 in a state where the refrigeration load is not known, the variable capacity expansion compressor 30A and the constant capacity expansion compressor 30B are opened in response to a command from the time setting means 46. The control valve 36
It is determined that the opening of the control valve 36 is set to zero for a predetermined period of time preset in the time setting means 46, and this command is outputted to the control valve 36 via the output means 45, and the opening of the control valve 36 becomes zero. . Then, the variable displacement compressor 1!30A is operated at full load for a predetermined period of time, and during this time the variable displacement hydraulic FM machine 30A
The total compression capacity, which is the sum of the compression capacities of the fixed capacity compressor 30B, is greater than the refrigeration load, and the pressure of the refrigerant gas flowing in the suction pipe 34, that is, the low pressure, decreases accordingly.

This pressure is detected by the low pressure pressure sensor 38, and this output is input to the determining means 47. Determine whether or not the load is low.

If the load is not low, the determination result of the determining means 47 is input to the operation mode determining means 48, where the variable capacity expansion compressor 30
The capacity control operation of A and the simultaneous operation of constant capacity compressor 30B are determined. This determination result is output to the drive motors 39A and 39B of the variable capacity expansion compressor 30A and the constant capacity compressor 30B via the output means 49, and the variable capacity expansion compressor 30A and the constant capacity compressor 30B are operated simultaneously. will continue.

However, if the load is low, the operation mode determining means 48 determines to stop the constant capacity compressor 30B in response to the determination result of the determining means 47, and this determination result is sent to the constant capacity compressor 30B via the output means 49. is output to the drive motor 39B, and the constant capacity compressor 30B is stopped.

Thereafter, capacity control operation using only the variable capacity expansion and compressor 30A continues.

When the capacity control operation of only the variable capacity expansion compressor 30A continues for a certain period of time, the variable capacity compression type 113OA is operated at full load for a certain period of time, and the low pressure decreases accordingly. If this low pressure is higher than the set pressure corrected by the set value correcting means 53, the determining means 47 determines that the variable capacity expansion compressor 30A immediately before full load operation is not under low load,
The capacity control operation of only the variable capacity inflation pressure vsm30A continues.

However, if the low pressure is lower than the corrected set pressure, the determining means 47 determines that the load on the variable capacity compression 1!3OA immediately before full load operation is low, and based on this determination result, the operating mode is changed. The determining means 48 is the variable capacity expansion compressor 3
It was decided to stop 0A, and from then on, variable capacity inflation pressure wMI! 30
^ also stops.

During the capacity control operation of only the variable capacity expansion and compressor 30A, if the refrigeration load increases beyond the capacity adjustment range of the variable capacity expansion and compressor 30A, the output from the sensor 37 that detects this increases via the comparison means 41. The opening degree determining means 43 is entered, and the operation mode determining means 48 determines the operation of the constant capacity expansion compressor 30B based on the command from now on. Thus, from now on, the capacity control operation of the variable capacity expansion compressor 30A and the constant capacity compression operation will be explained.
B is operated simultaneously.

In the above embodiment, two compressors 30A and 30B are installed, but three or more compressors can be installed. In this case, two or more variable capacity expansion compressors are installed. In addition, the operating order of the plurality of compressors can be started or stopped in a predetermined order or an appropriately selected order.

In the above embodiment, two types of operation modes, the energy saving operation mode and the freshness operation mode, can be selected by the selection means 52, but three or more types of operation modes can be selected, and the selected operation mode can be selected. The set pressure can be corrected only during arbitrary temperatures depending on the mode.

Further, in the above embodiment, the variable capacity expansion compressor 30A
It is determined whether the load on the variable capacity expansion compressor 3OA immediately before full load operation is low by comparing the crushing pressure during full load operation with the corrected set pressure. It is also possible to compare the output representing the load of the compressor with the corrected setting value and determine the operating mode of the plurality of compressors according to the result.

(Effect of the invention) The present invention includes a selection means for selecting a plurality of types of operation modes, and a set value correction means for automatically correcting a set value in accordance with the operation mode selected by the selection means. , the set value will be automatically corrected if you select the driving mode.

Further, a determining means for determining the load of the compressor based on the set value corrected by the set value correcting means, and an operating mode determining means for determining the operating mode of the plurality of compressors according to the determination result of the determining means. This makes it possible to automatically determine the operating mode of multiple compressors, including a variable capacity expansion compressor whose capacity automatically changes depending on the refrigeration load, according to the selected operating mode. Become.

[Brief explanation of drawings]

Figures 1 to 3 show one embodiment of the present invention, with Figure 1 being a system diagram of the refrigeration system, Figure 2 being a functional block diagram of the controller, and Figure 3 being a partial vertical sectional view of the variable capacity mechanism. It is.

Claims (1)

[Claims] In a refrigeration system in which at least one of multiple compressors installed in parallel in a refrigerant circuit is a variable capacity compressor whose capacity automatically changes according to the refrigeration load, multiple types of operation modes are provided. a selection means for selecting, a set value correction means for automatically correcting the set value in accordance with the operation mode selected by the selection means, and a set value correction means for automatically correcting the set value in accordance with the operating mode selected by the selection means; 1. A refrigeration system comprising a control device having a determining means for determining the load of the compressor, and an operating mode determining means for determining the operating mode of a plurality of compressors according to the determination result of the discriminating means.