JP2000146328A - Refrigerating and air-conditioning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the damage of a compressor by a method wherein an opening and closing valve, a refrigerant regulating tank and a control valve are arranged while the valves are controlled by an opening and closing controller so that an excessive load is not applied on the compressor upon starting the same and the amount of refrigerant, coping with the load, is supplied as the load becomes that of stationary operation. SOLUTION: When the operation of a refrigerating and air-conditioning cycle 2 is started, an opening and closing valve 11 is opened by a valve opening degree controller 15 and the valve is closed after the number of rotation of a compressor or the supply of oil to respective sliding parts is stabilized. Then, the circulation of carbon dioxide gas refrigerant is started and, after a substantially stationary operating condition is achieved and temperature regulation by a utilizing side heat exchanger 7 is started, the opening degree of opening and closing valves 13, 14 before and after a refrigerant regulating tank 12 are regulated so that the amount of refrigerant in the refrigerating and air-conditioning cycle 2 becomes an amount coping with a load. On the other hand, when the operation of the refrigerating and air- conditioning cycle 2 is to be stopped, the opening degree of the opening and closing valves 13, 14 is regulated prior to the stopping of the compressor 1 to recover the refrigerant into the regulating tank 12 and, thereafter, the opening and closing valve 11 is closed to stop the compressor 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating and air-conditioning system in which a compressor and a heat exchanger are connected with a refrigerant pipe to form a closed refrigerant circulation cycle, and carbon dioxide is used as a working refrigerant in this cycle. About.

[0002]

2. Description of the Related Art Refrigeration and air-conditioning systems such as air conditioners and refrigerators using carbon dioxide as a refrigerant have been improved in some ways to avoid CFC refrigerants and to contribute to environmental safety. The biggest difference between the refrigeration and air conditioning cycle using carbon dioxide as the refrigerant and the refrigeration and air conditioning cycle using CFC or ammonia as the refrigerant, which has been widely used in the past, is that the conventional refrigerant represented by the CFC refrigerant has a pressure less than the critical pressure. On the other hand, in a cycle using carbon dioxide as a refrigerant, the cycle operation is performed under supercritical conditions because the critical temperature of carbon dioxide is as low as −31 ° C.
For this reason, refrigeration / air-conditioning control (hereinafter referred to as temperature control) has conventionally been performed by controlling the mass of refrigerant passing through an evaporator in a refrigeration / air-conditioning cycle by an expansion valve. In a cycle using carbon as a refrigerant,
A uniform control method has not been determined.

In a refrigeration / air-conditioning cycle using carbon dioxide as a refrigerant, the pressure difference between the high pressure side connected to the discharge port of the compressor and the low pressure side connected to the suction port of the compressor is large. Since the size of the refrigerating and air-conditioning cycle is incomparably larger than that of the refrigerant, there is a need to improve the structure of the refrigeration / air-conditioning cycle from the basics and to improve the components of the compressor and the cycle.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and has been made to prevent compressor damage by improving the startability of a compressor in a supercritical vapor compression cycle using carbon dioxide as a refrigerant. At the same time, by providing an adjusting device that exerts a temperature control ability suitable for temperature control and heat load such as cooling and heating, an improved efficiency of carbon dioxide refrigerant (hereinafter abbreviated as carbon dioxide gas refrigerant) is provided. It is to provide a refrigeration and air conditioning system.

[0005]

In order to solve the above-mentioned problems, a refrigeration / air-conditioning apparatus according to claim 1 of the present invention comprises a compressor,
The use side heat exchanger, expansion valve, heat source side heat exchanger, etc. are sequentially airtightly connected by refrigerant pipes to form a refrigeration / air-conditioning cycle. A side pipe connecting the high pressure side refrigerant pipe from the discharge port to the expansion valve and the low pressure side refrigerant pipe from the expansion valve to the suction port of the compressor via an on / off valve is provided. And a controller for controlling the opening and closing of the valve, the valve opening and closing controller opens the on-off valve of the bypass pipe when the compressor is stopped, and at the start of the operation of the compressor, after the operation of the compressor shifts to the steady operation, The on-off valve is operated to be closed.

As a result, when the compressor is started, the compressor is operated with no load or light load, and the lubrication mechanism of the sliding portion and the temperature equilibrium of each part of the machine are shifted to the steady operation state. The on-off valve is later closed to allow circulation of the carbon dioxide gas refrigerant by the normal refrigeration cycle.The high pressure difference for maintaining the refrigeration and air conditioning cycle operation by the carbon dioxide gas refrigerant causes It is possible to prevent the compressor from being damaged due to each part of the machine.

According to a second aspect of the present invention, there is provided a refrigeration / air-conditioning system similar to the first aspect, wherein the high-pressure side refrigerant pipe and the low-pressure side refrigerant pipe communicate with each other via an on-off valve. A refrigerant adjustment tank with a control opening and closing valve and a controller for adjusting the opening of these valves are provided in parallel with the expansion valve, and the valve opening controller opens and closes the bypass pipe when the compressor stops. Open the valve and close the control on-off valve of the refrigerant adjustment tank, close the on-off valve of the bypass pipe after starting operation of the compressor, and air-condition the opening degree of the control on-off valve of the refrigerant adjustment tank. The adjustment is performed so that the amount of the refrigerant according to the load is supplied to the refrigeration / air-conditioning cycle.

[0008] This prevents the compressor from being subjected to a high pressure difference for maintaining the refrigeration / air-conditioning cycle operation by carbon dioxide gas and causing a failure in the compressor, and also controls air and brine for cooling and heating. By appropriately supplying and adjusting the amount of refrigerant according to the heat load such as temperature and refrigeration to the refrigeration and air conditioning cycle, efficient capacity control and temperature control under supercritical vapor compression cycle conditions where operation control is difficult to stabilize It is made possible.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a compressor powered by an electric motor or the like which has been widely used in the past, and compresses and circulates a carbon dioxide gas refrigerant in a refrigeration / air-conditioning cycle 2. The discharge port 3 and the suction port 4 of the compressor 1 are air-tightly connected to a heat source side heat exchanger 6, a use side heat exchanger 7, an expansion valve 8 and the like via a four-way valve 5 via a refrigerant pipe 9, and are refrigerated. The air conditioning cycle 2 is configured. The use side heat exchanger 7 is installed in an environment for air conditioning, and discharges heat of the refrigerant to heat the room, absorbs heat from air or brine around the use side heat exchanger 7, cools the room, and cools the room. The heat source side heat exchanger 6 is installed outdoors to obtain heating heat, or to cool and release heat taken into the refrigeration / air-conditioning cycle 2 to continuously operate the refrigeration / air-conditioning cycle 2. This is a heat exchanger that performs a simple operation.

Reference numeral 10 denotes a side pipe connecting the pipe on the discharge port 3 side of the compressor 1 and the pipe on the suction port 4 via an on-off valve 11, and 12 denotes a side pipe in parallel with the expansion valve 8. Control on-off valve 13, 1
4 is a refrigerant adjustment tank connected via the control valve 4. The control on-off valves 13 and 14, the on-off valve 11 of the bypass pipe 10, and the expansion valve 8 are all electrically connected to a valve opening controller 15. In response to a signal from a sensor 16 provided in the exchanger 7 and an operation signal (not shown) from the compressor 1, the valves 8, 11, 13, and 14 are controlled as follows.

First, when the operation of the compressor 1 is started in order to start the operation of the refrigeration / air-conditioning cycle 2, the valve opening controller 15 starts operation of the on-off valve 11 in the open state, After the number of revolutions of the oil and lubrication of each sliding part are stabilized, the valve 1
1 is closed. Thus, the refrigerating air conditioning cycle 2
After the carbon dioxide gas refrigerant starts to circulate, the operation becomes almost steady, and after the temperature adjustment by the use side heat exchanger 7 is started, the opening of the control on-off valves 13 and 14 of the refrigerant adjustment tank 12 is adjusted. The amount of refrigerant is adjusted by replenishing the refrigerant in the refrigerant adjustment tank 12 into the refrigeration / air-conditioning cycle 2 or returning the refrigerant from the refrigeration / air-conditioning cycle 2 to the refrigerant adjustment tank 12.
When the load is large, the amount of refrigerant in the cycle is increased so that the amount of refrigerant in the refrigeration / air-conditioning cycle 2 matches the load. This is to reduce the amount of refrigerant inside to balance with the refrigeration and air conditioning load.

For example, when the load is small, the sensor 16
Sends a signal to the controller 15 that the temperature control capability is greater than the load, the controller 15 sets the expansion valve 8 in the opening direction, the control on / off valve 13 in the opening direction, and the control on / off valve 14
Are controlled in the closing direction, and the carbon dioxide gas refrigerant is stored in the refrigerant adjustment tank 12, and the amount of the refrigerant in the refrigeration / air-conditioning cycle 2 is reduced so as to be suitable for the load, thereby lowering the temperature control ability. Conversely, when the controller 15 receives a signal from the sensor 16 when the load is large or tends to be large, the control valve 15 is closed in the direction of closing the expansion valve 8 and the control valve 13 is closed. 14 is controlled in the opening direction to supply the refrigerant into the refrigeration / air-conditioning cycle 2 and increase the refrigerant amount, thereby increasing the refrigerant amount in the refrigeration / air-conditioning cycle 2 and adapting to the load.

As described above, the expansion valve 8 is controlled by the controller similarly to the control of the conventional refrigeration / air-conditioning cycle 2. However, since the refrigeration / air-conditioning cycle using the carbon dioxide refrigerant is under the supercritical cycle condition, The refrigerant is in a two-phase mixed state of gas and liquid even in the heat exchanger acting as a condenser, and the capacity control is limited, but as in the present invention, the operation of the compressor in a state where the high and low pressure difference is eliminated To start the compressor 1
After the lubrication of the sliding parts and the temperature equilibrium of each part of the machine have shifted to the steady operation state, the refrigerant adjustment tank 12 is used together with the valve control so as to control the amount of refrigerant. The compressor 1 can be started without imposing an excessive load on the air conditioner, and after the refrigeration / air-conditioning cycle 2 reaches the temperature control operation, the refrigeration / air-conditioning operation with the efficient carbon dioxide refrigerant adapted to the temperature control load is performed. Can be transferred to

Next, when the refrigeration / air-conditioning cycle 2 is stopped, prior to the stop of the compressor 1, the valve opening controller 1
5 adjusts the degree of opening of the control on / off valves 13 and 14 of the refrigerant adjustment tank 12, collects the carbon dioxide refrigerant in the refrigerant adjustment tank 12, reduces the amount of refrigerant in the refrigeration / air-conditioning cycle 2, reduces After the pressure load on the on-off valve 11 of the bypass pipe 10 is reduced, the control on-off valves 13 and 14 are closed, and then the on-off valve 11 is opened to stop the compressor 1. At this time, if the compressor 1 is stopped after the open / close valve 11 is opened, high pressure is not applied after the stop of the compressor 1, but adverse effects such as noise may occur when the open / close valve 11 of the bypass pipe 10 is opened. Conversely, when the on-off valve 11 is opened after the compressor 1 is stopped, there is no harm caused by the opening of the on-off valve 11,
There is a possibility that unexpected adverse effects may occur in the compressor 1. Which one to function first is appropriately selected depending on the use environment of the refrigeration / air-conditioning cycle 2, but the operation stop is ultimately performed by the open state of the on-off valve 11 of the bypass pipe and the refrigerant adjustment tank 12. The control on-off valves 13 and 14 are closed.

Although the above description has been given of the most preferred embodiment of the present invention, the basic idea of the present invention is that the valve opening controller 15 is a so-called valve opening / closing controller. A refrigerant pipe on the high pressure side from the discharge port 3 of the compressor 1 to the expansion valve 8 of the refrigeration / air-conditioning cycle 2 using carbon dioxide refrigerant, and a refrigerant pipe on the low pressure side from the expansion valve 8 to the suction port 4 of the compressor 1 The opening and closing of the on-off valve 11 provided in the bypass pipe 10 communicating with the road is opened when the compressor 1 is stopped, and when the operation of the compressor 1 shifts to the steady operation when the operation of the compressor 1 is started. What is necessary is just to operate so that it may close.

The on-off valve 11 and the control on-off valves 13 and 14 of the refrigerant regulating tank are used to start and stop the operation of the compressor 1.
Each of the pipes is not limited to the configuration shown in FIG.
For example, the on-off valve 11 of the bypass pipe and the refrigerant adjustment tank 12
In any case, a bypass connecting the high pressure side refrigerant pipe from the discharge port 3 of the compressor 1 to the expansion valve 8 and the low pressure side refrigerant pipe from the expansion valve 8 to the suction port 4 of the compressor 1 If provided on the pipe 10, the above-mentioned function can be exhibited, and the on-off valve 1
With regard to 1, the same mechanism as the on-off valve 11 may be incorporated in the compressor 1.

Further, the refrigerant adjustment tank 12 is installed in parallel with the expansion valve 8 as a position most suitable for the exchange of refrigerant between the refrigerant adjustment tank 12 and the refrigeration / air-conditioning cycle 2. As long as it has the above-mentioned function in combination with the on-off valve 11 of the bypass pipe 10, a slight change in the mounting position does not deviate from the gist of the present invention.

Further, two control opening / closing valves 13 and 14 of the refrigerant adjustment tank 12 are not necessarily required, and the above-described functions of the two valves are operated by one valve. Needless to say, even if it is incorporated in the embodiment 12, it is an embodiment of the present invention.

[0020]

As described above, according to the present invention,
In a refrigeration / air-conditioning cycle using carbon dioxide refrigerant, an on-off valve, a refrigerant adjustment tank, and a control valve are provided, and these valves are controlled by an on-off controller for the valve.
When starting the compressor, no excessive load is applied to the compressor, and the amount of refrigerant corresponding to the load is supplied and adjusted to the refrigeration / air-conditioning cycle as the operation becomes steady, simplifying the mechanism of carbon dioxide gas refrigerant. In addition, the startability of the compressor can be improved with less damage to the compressor. In addition, it is possible to provide a carbon dioxide refrigerant refrigeration / air-conditioning apparatus with improved functions, which efficiently performs temperature control suitable for temperature control such as cooling and heating or the heat load of refrigeration. Things. Further, by using such a refrigeration cycle, it is possible to find a possibility that a compressor similar to a compressor using chlorofluorocarbon or the like as a refrigerant can be used for a refrigeration cycle using a carbon dioxide gas refrigerant.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a refrigeration / air-conditioning cycle according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 Refrigeration / air-conditioning cycle 3 Discharge port 4 Suction port 6 Heat source side heat exchanger 7 User side heat exchanger 8 Expansion valve 9 Refrigerant pipe 10 Side pipe 11 Opening / closing valve 12 Refrigerant regulating tank 13, 14 Control opening / closing valve 15 Valve Opening controller

Claims (2)

[Claims] 1. A refrigeration / air-conditioning cycle is constituted by sequentially connecting a compressor, a use side heat exchanger, an expansion valve, a heat source-side heat exchanger and the like in a gas-tight manner with a refrigerant pipe. A bypass line that connects a high-pressure refrigerant line from the compressor discharge port to the expansion valve and a low-pressure side refrigerant line from the expansion valve to the compressor suction port via an on-off valve. A pipe and a controller for controlling the opening and closing of the on-off valve are provided. The valve on-off controller opens the on-off valve of the bypass pipe when the compressor is stopped, and operates the compressor when the compressor starts operating. Is operated so as to close the on-off valve after shifting to a steady operation. 2. A refrigeration / air-conditioning cycle is constituted by sequentially connecting a compressor, a use-side heat exchanger, an expansion valve, a heat source-side heat exchanger and the like in a gas-tight manner with a refrigerant pipe. A bypass line that connects a high-pressure refrigerant line from the compressor discharge port to the expansion valve and a low-pressure side refrigerant line from the expansion valve to the compressor suction port via an on-off valve. A refrigerant adjustment tank with a control opening / closing valve and a controller for adjusting the opening of these valves are provided in parallel with the pipe and the expansion valve, and the valve opening controller controls the opening / closing valve of the bypass pipe when the compressor is stopped. Open and close the control on-off valve of the refrigerant adjustment tank, close the on-off valve of the bypass pipe after the operation of the compressor starts, and supply the refrigerant amount according to the air-conditioning load to the refrigeration air-conditioning cycle. Adjust the opening of the control on / off valve of the refrigerant adjustment tank Refrigeration and air conditioning apparatus according to claim Rukoto.