JPH0428960A - Freezer device - Google Patents

Abstract

PURPOSE:To enable a capacity of a compressor to be coincided with a load of an evaporator i.e., a freezing load irrespective of a length of a refrigerant pipe ranging from the evaporator to the compressor by a method wherein means for determining a degree of opening of a control valve in response to a load of the compressor is provided and a degree of opening of the control valve determined in response to the refrigerant pressure at an outlet port of the evaporator is corrected. CONSTITUTION:A refrigerant gas pressure at an outlet port of an evaporator 33 detected by a pressure sensor 38 is inputted to a comparing means 41 of a controller 40, compared with a set pressure set in advance in a setting means 42 and then a difference between both values is calculated. This difference is inputted to means for calculating a required degree of opening and then the required degree of opening of a control valve 36 is calculated in accordance with a control rule inputted from a memory means 44. The required degrees of opening are inputted to a degree of opening correction means 66, where a degree of opening determined by a degree of opening determining means 64 is corrected. The corrected degree of opening is outputted to the control valve 36 through an outputting means 45. The control valve 36 shows a corrected degree of opening. Accordingly, the compressor is operated in response to a load of an evaporator, i.e., the capacity of it corresponding to the freezing load irrespective of the length of the refrigerant pipe extending from the evaporator to the compressor.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to refrigeration equipment such as refrigerators, water coolers, air conditioners, and dehumidifiers equipped with reciprocating compressors.

(Prior Art and Section 6) In this type of refrigeration system, refrigerant discharged from a compressor passes through a condenser, a throttling mechanism, and an evaporator in this order, and is circulated to the compressor.

In this refrigeration system, if the capacity of the compressor does not match the refrigeration load, frost may adhere to the evaporator or the evaporation pressure of the refrigerant may become too low, resulting in deterioration of the operating efficiency.

In order to deal with this, the number of rotations of the compressor, that is, the capacity of the compressor, can be continuously and steplessly controlled by using an inverter to change the frequency of the current supplied to the drive motor of the compressor. However, this had the problem that the price of the inverter increased as the capacity of the compressor increased.

In addition, if the temperature or pressure of the refrigerant gas input into the compressor, that is, the load on the compressor, is detected and the capacity of the compressor is controlled accordingly, the refrigerant piping from the evaporator to the compressor can be controlled. If the length is long, there is a problem in that the capacity of the compressor cannot be adjusted to the refrigeration load due to flow resistance when the refrigerant gas flows through the refrigerant pipe.

(Means for Solving the Problems) The present invention was invented to solve the above problems, and its gist is that the refrigerant discharged from the compressor is A refrigeration system in which the compressor is circulated through the compressor in this order is provided with a capacity control mechanism that can continuously and steplessly change the capacity of the compressor by controlling the opening degree of a control valve, and means for determining the opening degree of the control valve according to the load of the machine;
The refrigeration system is characterized in that it includes a control device including means for correcting the determined opening degree of the control valve in accordance with the refrigerant pressure at the outlet of the evaporator.

(Function) Since the present invention has the above configuration, the opening degree of the control valve determined according to the load of the compressor is corrected according to the refrigerant pressure at the outlet of the evaporator. Regardless of the length of the refrigerant piping from the evaporator to the compressor, the evaporator is operated at a capacity corresponding to the evaporator load, that is, the refrigeration load.

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

FIG. 1 shows a system diagram of the refrigeration system.

The high-temperature, high-pressure refrigerant gas discharged from the compressor 30 enters the condenser 31, as shown by the arrow, 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. Then,
This refrigerant enters the evaporator 33 where it is evaporated into a low-temperature gas refrigerant and then circulated to the compressor 30.

A bypass pipe 35 that connects a working chamber of a variable capacity mechanism built into the compressor 30, which will be described later, and a suction pipe 34 of the compressor 30.
A control valve 36 is interposed therein.

A sensor 61 that detects the pressure or temperature of the refrigerant flowing inside the suction pipe 34 and a sensor 37 that detects the flow velocity of this refrigerant are attached to the suction pipe 34 , and the outputs of these sensors 61 and 37 are input to the controller 40 . In addition, the evaporator 33
A pressure sensor 38 for detecting the pressure of the refrigerant gas is attached to the outlet of the refrigerant gas, and its output is used to start or stop the drive motor 39 of the compressor 30.

A capacity control mechanism for compressor 30 is shown in FIG.

In Fig. 3, l 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 is a An[+-dapiston.

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.
A working chamber 16 is defined above the unloader piston 10, and a chamber 19 is defined below the unloader piston 10 by fitting the unloader piston 10 in a sealed and slidable manner. This chamber 19 communicates with the gas compression chamber 12 through the opening 18, and the working chamber 16 is connected to the cover 20.
It communicates with the discharge chamber 8 through a throttle hole 24 bored in the discharge chamber 8 . Further, the working chamber 16 communicates with a bypass pipe 35 via a pressure guiding pipe 15 and a passage 21 bored in the valve plate 3 .

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 13, and is discharged from there through a discharge pipe (not shown).

On the other hand, the gas in the gas compression chamber 12 flows into the chamber 19 through the opening 18, and 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 of the compressor 30 through the pressure guiding pipe 15, the passage 21, the control valve 36, and the bypass pipe 35. The pressure within the working chamber 16 is set to a desired pressure by controlling the gas flow rate control valve 36.

Thus, the unloader piston 10 moves up and down according to the difference between the pressure in the working chamber 16 and the average cylinder pressure in the gas compression chamber 12 acting on the chamber 19, and the unloader piston 10 moves up and down according to the difference between the pressure in the working chamber 16 and the average cylinder pressure in the gas compression chamber 12 acting on the chamber 19. As the clearance volume changes, the capacity of the compressor 30 changes continuously and steplessly.

In addition, in FIG. 3, 23 is the unloader piston 10.
A seal ring 25 is wound around the upper end, a piston ring 25 is wound around the piston 2, and a washer 26 is fixed to the lower end of the unloader cylinder 9.

A functional block diagram of controller 40 is shown in FIG.

The refrigerant temperature or pressure detected by the sensor 61 is input to the comparison means 62 of the controller 40, where it is compared with the set value set in the setting means 63 and the deviation between the two is calculated. This deviation is input to the opening determining means 64, where the opening of the control valve 36 is determined according to the control rule input from the storage means.

Note that the storage means 65 stores control rules (for example, PID control, table comparison control, fuzzy control, etc.) for determining the opening degree in accordance with the deviation and its rate of change.

The determined opening degree is input to the opening degree correction means 66.

On the other hand, the refrigerant gas pressure at the outlet of the evaporator 33 detected by the pressure sensor 38 is determined by the comparison means 41 of the controller 40.
The pressure is inputted to the pressure setting means 42, and compared with the set pressure preset in the setting means 42, and the deviation between the two is calculated. This deviation is input to the required opening calculation means 43, where it is recorded as
The control valve 3 according to the control rule inputted from the means 44
The required opening degree of 6 is calculated. These required opening degrees are input to the opening degree correcting means 66, where the opening degree determined by the relationship determining means 64 is corrected. Then, the corrected opening degree is outputted to the control valve 36 via the output means 45, and the control valve 36 has the corrected opening degree.

On the other hand, the flow rate of the refrigerant detected by the sensor 37 is inputted to the comparison means 47 of the controller 40, where it is input to the setting means 48.
It is compared with the setting value input from. When the flow rate of the refrigerant falls below the set value due to a decrease in the load on the compressor 30, an operation stop command is output to the drive motor 39 of the compressor 30 via the output means 49, and the compressor 30 is stopped. After the operation is stopped, when a certain period of time has elapsed or when the refrigerant pressure in the suction pipe 54 exceeds a predetermined value, the motor 39 is started by a command from the controller 40, and the operation of the compressor 30 is restarted.

In the above embodiment, the flow rate of the refrigerant is detected by the sensor 37, but the rotation speed of the compression VS 30, the electric power supplied to the motor 39, etc. may be detected instead.

(Effects of the Invention) In the present invention, in order to correct the opening degree of the control valve determined according to the load of the compressor according to the refrigerant pressure at the evaporator outlet, the length of the refrigerant piping from the evaporator to the compressor is Regardless of the size, it is possible to match the capacity of the compressor to the load on the evaporator, that is, the refrigeration load.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, FIG. 1 is a system diagram, and FIG. 2 is a system diagram.
The figure is a functional block diagram of the controller, and FIG. 3 is a longitudinal sectional view of the capacity control mechanism. Compressor 30, condenser 31, throttling mechanism 32, evaporator 33, control valve 36, controller 40, opening determining mechanism

Claims (1)

[Claims] In a refrigeration system in which refrigerant discharged from a compressor passes through a condenser, a throttle mechanism, and an evaporator in this order and circulates to the compressor, the capacity of the compressor can be continuously adjusted by controlling the opening degree of a control valve. means for determining the opening degree of the control valve in accordance with the load of the compressor; and means for determining the opening degree of the control valve in accordance with the refrigerant pressure at the outlet of the evaporator; 1. A refrigeration system comprising: a control device having means for correcting the opening degree of the refrigeration system.