JPH04124557A - Operation control of refrigerating plant - Google Patents

Abstract

PURPOSE:To make it possible to operate a refrigerating device under a low temperature condition by detecting an open air temperature when starting an operation after the return of an internal temperature controller, and short- circuiting a low pressure cut-off device forcibly until a suction pressure in operation rises up to a setting pressure or higher at which said low pressure cut-off device returns when the detected temperature fails to exceed the preset temperature. CONSTITUTION:When a condenser or a liquid receiver is installed in a location under a temperature condition lower than an internal temperature of a vaporizer installed, it is necessary to detect an open air temperature after a low pressure cut-off device returns and a solenoid valve installed in front of an expansion valve is opened. When the open air temperature falls to exceed a preset temperature, the low pressure cut-off device must be forcibly short-circuited so as to carry out cooling operation. When the refrigerant gas discharged from a compressor flows gradually and the suction pressure of the compressor rises gradually and reaches the return pressure or higher of the low pressure cut-off device, it is possible to cancel a compulsory short circuit of the low pressure cut-off device and perform a routine cooling operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an operation control method for a refrigeration system in which cooling operation is controlled by a low-pressure pressure cut-off device.

[Conventional technology]

The conventional device detects the outside temperature of the refrigerator and adjusts the lower limit of the suction pressure\force according to the detected outside temperature, as described in Japanese Patent Application Laid-open No. 62-225857 (Refrigerating Machine Capacity Control Method). The compressor is operated by automatically changing the value, but the above-mentioned known examples do not guarantee the suction pressure at startup, so depending on the conditions,
It may not be possible to start.

In the present invention, the outside temperature is below a certain temperature.

Guaranteed startup.

[Problem to be solved by the invention]

The conventional technology does not take into consideration the operating conditions when the condenser and liquid receiver are installed in a place where the temperature is lower than the temperature inside the refrigerator where the evaporator is installed. When the compressor starts after stopping, the pressure in the receiver and the pressure in the evaporator are reversed, so the refrigerant in the receiver flows through the expansion valve to the evaporator. Since the refrigerant suction capacity exceeds the refrigerant suction capacity, the suction pressure drops abnormally, and the compressor is stopped due to the operation of the low-pressure pressure cut-off device, resulting in a situation in which cooling operation is impossible. As a countermeasure for this, conventionally.

Measures were taken to increase the pressure inside the receiver while the refrigeration equipment was stopped, such as by attaching a heater, etc. to the receiver, but this resulted in problems with reliability and wasted voltage. Ta.

The present invention enables refrigeration in low-temperature conditions by disabling the operation of the low pressure cut-off device until the suction pressure rises to the minimum suction pressure necessary for compressor operation, depending on the environmental temperature conditions in which the refrigeration equipment is installed. The purpose is to enable the operation of the device.

[Means to solve the problem]

In order to achieve the above object, the present invention detects the outside air temperature at the start of operation after the indoor temperature regulator returns, and if the temperature is below a preset temperature, the low pressure pressure cutoff device is forced to return to the set pressure. Operate with the low-pressure pressure cut-off device short-circuited,
The pressure inside the condenser and liquid receiver is gradually increased to ensure a differential pressure with the evaporator, making it easy for the refrigerant to flow and achieving stable operating conditions.

[Effect]

Refrigeration system of the present invention! The low-pressure pressure cut-off device operates by short-circuiting the low-pressure pressure cut-off device when the outside air temperature is started at a certain set temperature or lower until the pressure rises to the set pressure at which the low-pressure pressure cut-off device returns. When the compressor operates, the discharge gas of the compressor is introduced into the condenser, and the pressure in the condenser and liquid receiver is gradually increased, making it possible to secure the required differential pressure before and after the expansion valve. Since the refrigerant is smoothly introduced into the evaporator, the suction pressure of the compressor becomes a stable evaporation pressure, so that cooling operation can be performed smoothly.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

A refrigeration cycle is composed of a compressor, a condenser, a liquid receiver, an expansion valve, and an evaporator, and a low-pressure cutoff device is installed on the suction side of the compressor, which closes when the pressure drops below the set pressure. In addition, a solenoid valve is installed in front of the expansion valve.

The above structure will be explained using the cooling operation control flowchart shown in FIG. In normal cooling operation, the temperature inside the refrigerator is controlled by opening and closing the solenoid valve installed in front of the tension valve according to the set temperature of the refrigerator temperature regulator. When the internal temperature reaches the set temperature and the internal temperature controller is activated, the solenoid valve installed in front of the expansion valve closes and refrigerant is introduced into the liquid receiver.

When the suction pressure of the compressor falls below the set pressure at which the low-pressure pressure cut-off device operates, the low-pressure pressure cut-off device is activated.
The compressor stops. After that, the temperature inside the refrigerator rose! When the temperature at which the internal temperature controller returns is reached, the solenoid valve installed before the expansion valve opens, and the suction pressure of the compressor increases, and when the pressure at which the low-pressure pressure cutoff device returns is reached, cooling operation begins. .

With this control, if the condenser and receiver are installed at a temperature lower than the temperature inside the refrigerator where the evaporator is installed,
11 Even if the temperature at which the internal temperature controller returns is reached and an operation command is issued, the internal pressure of the liquid receiver and the internal pressure of the evaporator may be reversed at the expansion valve immediately after the start of operation, causing the refrigerant to The water does not flow into the evaporator as expected. Since the compressor attempts to suck refrigerant at a constant capacity, the suction pressure drops abnormally, and the low-pressure pressure cutoff device is activated, making it impossible to restart the compressor. However, in the refrigeration system devised by Wood, after the low-pressure pressure cut-off device returns and the solenoid valve installed before the 11th valve opens, the outside air temperature A is detected, and the outside air temperature A becomes the set temperature Z. In the following cases.

Cooling operation is performed by forcibly short-circuiting the low-pressure pressure cut-off device. Then, the refrigerant gas discharged by the compressor gradually flows, and the suction pressure B of the compressor gradually increases. When the suction pressure B reaches more than the return pressure Y of the low-pressure pressure cut-off device, a forced short circuit of the low-pressure pressure cut-off device occurs. It becomes possible to cancel the operation and perform normal cooling operation.

〔Effect of the invention〕

The present invention provides that the condenser and liquid receiver of the refrigeration system are installed in an environmental condition with a temperature lower than the temperature condition inside the refrigerator where the evaporator is installed, and that part of the refrigeration equipment can also be operated after being stopped for a long time. , stable operation is possible simply by adding control of the refrigerator. Furthermore, it is not necessary to install a heater, etc., and there is no need to waste electricity, so it is economical.

[Brief explanation of the drawing]

FIG. 1 is a flowchart of operation control showing an embodiment of the present invention. A. Set temperature, 2. Outside temperature, B. Suction pressure, Y...
Low pressure pressure isolation device 100 return pressure, 63 D (L> Low pressure pressure isolation device.

Claims (1)

[Scope of Claims] 1. In a refrigeration system whose operation is controlled by a low-pressure pressure cutoff device, the outside air temperature is detected at the start of operation after the internal temperature controller returns, and if the temperature is below a preset temperature, the operation is stopped. A method for controlling the operation of a refrigeration system, comprising: forcibly short-circuiting the low-pressure pressure cut-off device and performing a cooling operation until the suction pressure of the low-pressure cut-off device rises above a set pressure at which the low-pressure pressure cut-off device returns.