JPS5852149B2 - Refrigeration equipment capable of cooling and dehumidifying - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses one automatic expansion valve for superheat control for both cooling and dehumidification, and enables cooling and dehumidification that can be operated with a simple circuit configuration and easy operation. Regarding refrigeration equipment.

Conventional so-called multi-connection refrigeration systems, in which multiple indoor units are connected in parallel to one outdoor unit, have a connection between cooling and dehumidification, as illustrated in Figure 1 (only the indoor unit is shown). A solenoid valve (S
In addition, depending on the structure, two expansion valves (EV) or a check valve may be required, increasing the number of attached devices and complicating the circuit structure. However, there was a problem in that the cost of the device was high, and there were other inconveniences such as switching noise.

Furthermore, changes in the state of the refrigerant occur when switching from cooling to dehumidification, or when reducing the air volume of the outdoor coil fan to increase the reheating capacity of the indoor coil used as a reheater instead of a condenser. As a result of not being able to respond immediately to operations, so-called followability deteriorates, resulting in liquid return to the compressor.

Additionally, since the heat exchange area of the condenser is considerably larger than that of the evaporator, the amount of restriction of the pressure reducer must be increased, and as a result, the low pressure force decreases and the evaporator Furthermore, since the amount of refrigerant charged is relatively large, a large amount of liquid refrigerant accumulates on the low pressure side, and there is a problem that liquid refrigerant is likely to occur at startup.

Furthermore, at startup, the refrigerant immediately before the pressure reducer may not be sufficiently subcooled, and flash refrigerant may flow through the pressure reducer, producing unpleasant passing noise.

Furthermore, since the structure does not make it easy to adjust the amount of reheating on the indoor coil side, it is difficult to adjust the amount of reheating on the indoor coil side, resulting in practical defects such as difficulty in adjusting the air to be too cold or too hot.

In addition, the pressure inside the first indoor coil 5', which serves as a reheater during dehumidification and an evaporator during cooling, suddenly changes from high pressure to low pressure when switching between cooling operation and dehumidification operation, especially when switching from cooling operation to dehumidification operation. When switching to the first indoor coil 5', high-pressure refrigerant flows into the first indoor coil 5', and the pressure inside the coil 5' suddenly changes from low to high, and an impact sound is generated due to this pressure change. It also had the disadvantage of causing discomfort to the occupants of the room.

The present invention has been made in an attempt to improve the above-mentioned drawbacks, and the present invention has been made in order to improve the above-mentioned drawbacks. A first indoor coil is connected to the outlet of the expansion valve, and a first indoor coil is connected to the compressor inlet and arranged downstream in the air flow path with respect to the first indoor coil. A connection pipe connecting the second indoor coil in series is arranged in a heat exchange relationship with a pipe leading from the outdoor coil of the outdoor unit to the inlet of the automatic expansion valve, and the degree of superheating of the automatic expansion valve can be controlled to switch between cooling and dehumidification. By adjusting the height in conjunction with the temperature range, cooling operation is performed at low superheat levels, and dehumidification operation is performed at high superheat levels.

The present invention will be described below based on an example device shown in the accompanying drawings.

Fig. 2 is a device circuit diagram of a multi-connection humid air conditioner. Each indoor unit port connected in parallel to, C, 2...
- A first indoor coil 4 that acts as an evaporator during both cooling and dehumidification, a second indoor coil 5 that acts as an evaporator during cooling and a reheater during dehumidification, an indoor fan 11, and an automatic expansion valve for controlling the degree of superheating. 3 (hereinafter abbreviated as expansion valve 3) and a heat exchange device 6.

The outdoor unit has high-pressure on-off valves 150 and 15 for branch connection at both ends of a main circuit consisting of a compressor 1 and a condenser 2 connected in series.
C... and low pressure on/off valve 160.16 bar for branch connection...
The condenser 2 and the high pressure on-off valve 150 are provided respectively.
, 15c... and bypass on-off valve 170, 1
A high-pressure bypass pipe 22 branching out from seven bars is provided.

On the other hand, each indoor unit port C... has the same circuit configuration, and to explain this for each indoor unit port, from the high pressure connection on-off valve 130 to the low pressure connection on-off valve 140, a part of the high pressure pipe 7 is connected. an outer passage 7a of the heat exchange device 6 formed by the expansion valve 3, the first indoor coil 4, and an inner passage 8a of the heat exchange device 6 formed by a part of the communication pipe 8.
The second indoor coil 5 is connected to the pipes in this order, and the temperature sensing tube 9, which is a control element of the expansion valve 3, is attached to the low pressure pipe extending from the second indoor coil 5 to form a refrigeration circuit. There is.

The first indoor coil 4 and the second indoor coil 5 are arranged in parallel such that the first indoor coil 4 is on the upstream side of the air flow path.

The expansion valve 7 and the heat exchange device 6 constitute the main components that characterize the present invention, and the expansion valve T, whose schematic structure is shown in FIG. By mechanically connecting the bellows 18 and the valve body 19,
A spring 20 having an elastic force that presses the valve body 1 in the closing direction
It is built in relation to 9.

The upper chamber of the bellows 18 has a temperature sensing cylinder 9 which is a control element.
forming a pressure chamber 21 for transmitting the refrigerant pressure in the
By connecting the temperature sensing cylinder 9 to this pressure chamber 21,
The temperature sensing cylinder 9 detects the temperature of the low-pressure refrigerant gas exiting the second indoor coil 5, and the expansion valve 3 adjusts the valve opening according to a predetermined degree of superheating.

The opening of the expansion valve 3 is automatically controlled by the balance of three forces as follows.

That is, the force that acts to open and close the valve is a force (pb) corresponding to the pressure inside the temperature sensing cylinder 9, that is, the force that acts on the upper surface of the bellows 18 in the pressure chamber 21 partitioned by the bellows 18 and opens the valve 19. The force acting in the direction and the force equivalent to the evaporation pressure (
pl), that is, the force that acts on the lower surface of the bellows 18 in the direction of closing the valve 19; and the force of the spring 20 (g), that is, the force that transmits the load below the bellows 18 through the stem and acts in the direction of closing the valve 19. The valve opening degree is determined in a state in which these three forces are balanced, that is, in a state in which pb-pl=F.

Now, if you adjust the spring force (g) to be a little stronger than usual, the valve opening will become slightly smaller.

This expansion valve 3 is configured so that the degree of superheating of the low-pressure refrigerant gas is the normal degree of superheating (
(approximately 5°C), for example 20°C.

Therefore, if the force (pb) among the forces acting on the valve 19 of the expansion valve 3 is increased, the valve 19 will open, the valve opening will increase, and the degree of superheating of the low-pressure refrigerant gas can be reduced.

In this way, by increasing the force (pb) by an appropriate amount, the degree of superheating of the low-pressure refrigerant gas can be controlled to an appropriate value.

As a means for increasing this force (pb), the temperature sensing cylinder 9
An indirect electric heater 10 is provided in the temperature sensing cylinder 9, and by adjusting the heating capacity, the pressure inside the temperature sensing cylinder 9 can be changed at will.

The indirect electric heater 10 is constructed by, for example, winding a linear electric heater around the cylindrical body of the temperature-sensing tube 9 or inserting a thin plate electric heater into the contact area between the temperature-sensing tube 9 and the piping 13. It can easily be made into an indirect heating structure.

In this case, the spring force and the heating capacity of the electric heater 10 are set in the following manner.

That is, when the electric heater 10 is heated at its rated capacity, the spring elasticity of the expansion valve 3 is adjusted to the expansion side so that a predetermined degree of superheating, for example 5° C., is obtained for the standard refrigeration load. What is necessary is to increase the static superheat degree of the valve 3.

With this structure, the electric heater 10 can be energized,
If released, the degree of superheat of the low-pressure refrigerant gas can be adjusted in two stages, 5°C and 20°C, forming a variable superheat degree expansion valve that can adjust the degree of superheat in stages from outside the valve body. It is possible.

The case where the cooling operation of the apparatus shown in FIG. 2 described above is performed will be explained.

First, close the cooling/dehumidification switch to the cooling side to energize the electric heater 10, then switch the operation switch to static, strong, or sudden to turn on the compressor, outdoor fan, and indoor fan. Power is supplied to the motor, compressor 1, outdoor fan 1
2 and the indoor fan 11 are respectively driven.

When operated in this way, the compressor 1, the outdoor coil 2 acting as a condenser, the outer passage 7a expansion valve 3 of the heat exchanger 6, the first indoor coil 4 acting as an evaporator, the inner passage 8a of the heat exchanger 6, and the evaporator a second indoor coil 5 that acts as a container;
A cycle is formed in which the refrigerant circulates in the order of the compressor 1, and the temperature-sensing tube 9 that senses the temperature of the refrigerant gas exiting the second indoor coil 5 is also affected by the heat of the electric heater 10, and the degree of superheating is increased to, for example, 20°C. Cooling operation is performed by adjusting the valve opening degree of the expansion valve 3, which is set to a high value, to maintain the temperature of the refrigerant gas sucked into the compressor 1 at a superheat degree of 5°C.

This cooling operation cycle will be further described in detail with reference to the Mollier diagram shown in FIG.

The high-pressure, high-temperature gas refrigerant a that has exited the compressor 1 flows into the indoor coil 2 .

This inflowing refrigerant a is cooled by the flowing outdoor air in the outdoor coil 2 and becomes a liquefied refrigerant.

This liquefied refrigerant flows into the heat exchanger 6 and the outer passage 7
While passing through a, it is supercooled by the low-pressure, low-temperature refrigerant e flowing out from the first indoor coil 4 (to a state at point C), and reaches the expansion valve 3.

The liquid refrigerant, which has been decompressed and expanded by the expansion valve 3 and has become low-pressure and low-temperature (state at point d), flows into the first indoor coil 4, exchanges heat with the indoor air induced by the indoor fan 11, and After some of the liquid refrigerant evaporates while cooling the indoor air (point e), it flows into the heat exchange device 6.

The low-pressure refrigerant that has flowed into the inner passage 8a of the heat exchanger 6 is heated by the high-pressure liquid refrigerant from the outdoor coil 2 to a state f.
After that, it enters the second indoor coil 5, where it exchanges heat with the indoor air that has been further cooled by the first indoor coil 4, and evaporates the indoor air while further cooling it to a predetermined superheat degree, for example, 5°C. It becomes a gas refrigerant (point g) with a superheat degree of , and is sucked into the compressor 1.

The state changes during the refrigerant circulation process are as explained above. The air cooled by the second indoor coil 4.5 is returned to the room to achieve cooling.

During the above cooling cycle, the low-pressure refrigerant leaving the first indoor coil 4 is heated by the high-pressure refrigerant in the heat exchange device 6 (from point e to point f in Figure 4), resulting in a decrease in cooling capacity. However, since the high-pressure liquid refrigerant flowing into the expansion valve 3 is supercooled by the amount equivalent to this amount of heating (from point C to point C in the same figure), the air conditioner is cooled by heat exchange in the heat exchange device 10. The ability does not deteriorate.

Next, the case where the dehumidifying operation is performed will be explained with reference to the Mollier diagram shown in FIG.

The cooling/dehumidification changeover switch is set to the dehumidification operation side, that is, the open side, the electric heater 10 is deactivated, and the operation switch is changed to the quiet, strong, or sudden notch.

By operating in this way, a cycle is formed in which the refrigerant circulates through each device in the same order as the cooling cycle, and dehumidification operation is performed.

This will be further explained in detail using the Mollier diagram shown in FIG.

The high-pressure, high-temperature gas refrigerant (point a' in Figure 5) discharged from the compressor 1 flows into the outdoor coil 2, is cooled by the outdoor air induced by the outdoor fan 3, and partially liquefies (
Point b/ ).

This liquid-gas mixed high-pressure refrigerant flows into the heat exchanger 6, and while passing through the outer passage 7a, it is supercooled by the low-pressure low-temperature refrigerant flowing out from the first indoor coil 4 (point C'), and is supercooled by the expansion valve 3. leading to.

With this N, the electric heater 10 attached to the temperature sensing cylinder 9 of the expansion valve 3
is inactive and does not generate any heat, so its temperature-sensing tube 9 detects only the temperature of the low-pressure refrigerant, and the expansion valve is activated so that the degree of superheat of the refrigerant is higher than during cooling operation, for example, 20°C. do.

Therefore, the opening degree of the expansion valve 3 becomes smaller than during cooling operation.

The low-pressure refrigerant (point d) that has been decompressed and expanded by the expansion valve 3 flows into the first indoor coil 4 and exchanges heat with the indoor air induced by the indoor fan 11, cooling and dehumidifying the indoor air. All of the refrigerant evaporates and flows into the heat exchanger 6 as a gas refrigerant (point e) with a certain degree of superheating, for example, 7°C.

Next, the low-pressure refrigerant that has flowed into the heat exchange device 6 is heated by exchanging heat with the liquid-gas mixed refrigerant flowing out from the outdoor coil 2 while flowing through the inner passage 8a, and is heated to a high temperature, for example, 40
The refrigerant becomes a low-pressure refrigerant (point f') at a temperature of .degree. C. and flows into the second indoor coil 5.

Here, this high-temperature low-pressure refrigerant exchanges heat with the cooled and dehumidified air in the first indoor coil 4, heats the air, and cools the refrigerant itself (point g'). 2
The temperature reaches 0°C and is sucked into the compressor 1.

On the other hand, the indoor air is cooled and dehumidified by the first indoor coil 4, heated to approximately the same temperature as the indoor temperature by the second indoor coil 5, and then returned indoors to perform a dehumidifying operation.

In this way, the refrigeration system of the present invention uses one expansion valve 3 at each indoor unit port, C, etc., and turns on and off the electric heater 10 to check the degree of superheat from outside the valve body. It is possible to switch between cooling operation and dehumidification operation by simply adjusting the height in stages.

In addition, in the above-mentioned device, the motor of the outdoor fan 12 is
If you use a speed type motor and switch the rotation speed of the motor when dehumidifying all indoor units at the same time, you can use a low air volume to dehumidify the outdoor fan with warm air, or a high air volume to dehumidify cold air. It is possible to control.

In addition, when only some indoor units are in dehumidifying operation and other indoor units are in cooling operation, the high-pressure on-off valve 15 corresponding to the indoor unit to be dehumidified is closed, and the corresponding bypass on-off valve 17 is closed. It is only necessary to open it, and by doing so, the dehumidifying capacity can be increased, and dehumidifying operation with slightly heating or cooling is also possible.

The example shown in Figure 2 describes the case where a temperature-sensitive expansion valve widely used in conventional refrigeration equipment is used, but the expansion valve in the device of the present invention changes the acting force exerted on the valve body by changing the electrical input. Special public service available in 1977-186
In the electric automatic expansion valve as disclosed in No. 96, two springs with different spring forces are associated with the valve body, and the spring can be collapsed by manual or electromagnetic actuation from outside the valve body. Needless to say, a variable spring pressure type temperature-sensitive expansion valve that can selectively act on the valve body may be used.

As is clear from the above description, the present invention provides a compressor 1
In a multi-connection type refrigeration system in which a plurality of indoor unit ports, C... are connected in parallel to one outdoor unit A, which has a condenser 2, each of the indoor unit ports, C...
- is an automatic expansion valve 3 for superheat control, a first indoor coil 4,
A second indoor coil 5 is provided on the downstream side of the air flow path with respect to the coil 5, and each of the devices 3, 4, 5 is connected from the condenser 2 outlet side of the outdoor unit 1 to the compressor 1 suction side. In addition, the automatic expansion valve 3 is configured as a variable superheat deformation expansion valve whose superheat degree set value can be adjusted from outside the valve body during refrigeration operation. The communication pipe connecting the coils 4 and 5 and the high pressure pipe connecting to the inlet of the automatic expansion valve 3 are configured in a heat exchange relationship, and the degree of superheating of the automatic expansion valve 3 is controlled by the cooling/dehumidifying switching operation. The configuration is such that the height can be adjusted to the low range side for cooling operation, and the high range side to perform dehumidification operation, so only one expansion valve is required, and a solenoid valve, two-way or three-way switching is required. There is no need for any valves, the circuit can be simplified, and there is no switching noise at all, allowing for quiet operation.

Furthermore, since the circuit system is designed to supercool the refrigerant in front of the automatic expansion valve 3, the high pressure of the outdoor coil 2 does not increase in both cooling and dehumidification, and the amount of heat dissipated is small, especially at the time of startup. There is no abnormal noise caused by the passage of flash refrigerant.

In addition, since the second indoor coil 5 used as a reheater is in the low-pressure refrigerant circuit for both cooling and dehumidifying, the amount of refrigerant charged is reduced compared to conventional devices of this type that function as an evaporator during cooling and as a condenser during dehumidification. Moreover, it has good ability to follow sudden load changes when switching between cooling and dehumidification and when dehumidifying, eliminating the possibility of liquid return.

Furthermore, in the conventional model, the heat exchange area of the condenser was much larger than that of the evaporator, and the amount of restriction in the pressure reducer was large, resulting in a large drop in low pressure and easily forming frost on the evaporator. In contrast, the present invention has the advantage that frost does not occur because the circuit system of the present invention does not cause an extreme drop in temperature.

In particular, the present invention has the advantage that some indoor units can be switched to dehumidifying operation during cooling operation, and each unit can be selectively operated independently.

Furthermore, the amount of reheat during dehumidification can be adjusted by easily changing the degree of superheating of the expansion valve 3 from outside the main body.
The present invention is a refrigeration system that exhibits various excellent effects, such as being able to perform dehumidification at any time for heating or cooling.

[Brief explanation of drawings]

FIG. 1 is a schematic circuit diagram of an indoor unit in a conventional refrigeration system, FIG. 2 is a circuit diagram of an air conditioner according to an embodiment of the present invention, and FIG. The schematic structural diagrams of the valve, FIGS. 4 and 5, are Mollier diagrams showing the operating characteristics of the apparatus of the present invention in a cooling cycle and a dehumidification cycle, respectively. A: Outdoor unit, port, C: Indoor unit, 1: Compressor, 2: Condenser, 3: Overheating Automatic expansion valve for degree control, 4...
...First indoor coil, 5...Second indoor coil.

Claims (1)

[Claims] 1 In a multi-connection refrigeration system in which a plurality of indoor unit ports, C, etc. are connected in parallel to one outdoor unit A, which has a compressor 1 and a condenser 2, each of the indoor unit ports and H . . . is equipped with an automatic expansion valve 3 for superheat degree control, a first indoor coil 4, and a second indoor coil 5 disposed downstream of the coil 4 in the air flow path, and each of these devices 3, 4. .5
In addition, the automatic expansion valve 3 is connected to the outside of the valve body during refrigeration operation when the set value of the degree of superheat is set. This is a variable superheat type expansion valve that can be adjusted in height from 1 to 3. On the other hand, the connecting pipe connecting between the two coils 4 and 5 and the high pressure pipe connecting to the inlet of the automatic expansion valve 3 are configured in a heat exchange relationship. The degree of superheating of the automatic expansion valve 3 is adjusted in height in conjunction with the cooling/dehumidification switching operation, and cooling operation is performed by adjusting it to the low range side, and dehumidification operation is performed by adjusting it to the high range side. Refrigeration equipment capable of cooling and dehumidifying.