JPS5851177B2 - Refrigeration equipment capable of cooling and dehumidifying - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a simple circuit type refrigeration system that can easily perform both cooling and dehumidification operations using only one automatic expansion valve for superheat control without using any fluid controllers such as switching valves. .

Conventional refrigeration equipment of this type capable of cooling and dehumidifying operations uses a solenoid valve S as an on-off valve to switch between cooling and dehumidification, as illustrated in Figure 1 (only the indoor unit is shown).
In addition, depending on the structure, two expansion valves EV or EV may be required, or a reversing valve may be required, increasing the number of accessory devices and complicating the circuit structure, resulting in high equipment costs. There were problems such as switching noise and 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.

Furthermore, since the heat exchange area of the condenser is considerably larger than that of the evaporator, the throttle amount of the pressure reducer must be increased, and as a result, the low pressure force decreases. It is easy to cause frost on the evaporator, and also (because the amount of refrigerant charged is relatively large, a large amount of liquid refrigerant accumulates on the low pressure side,
There is also the problem that liquid returns tend 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 allow for easy adjustment of the amount of reheating on the indoor coil side, practical defects such as the air being too cold or too hot (it is difficult to adjust this) cannot be avoided.

In addition, the pressure inside the first indoor coil 5', which serves as a reheater during dehumidification and an evaporator during cooling, rapidly changes from high pressure to low pressure when switching between cooling operation and dehumidification operation. When switching from cooling operation to dehumidification operation, high-pressure refrigerant flows into the first indoor coil 5', and the pressure inside the coil 5' suddenly changes from low to high pressure, resulting in a shock due to this pressure change. Another drawback was that it generated noise, which caused discomfort to the occupants of the room.

The present invention has been made in an attempt to improve the above-mentioned drawbacks. An outdoor coil is connected to a connecting pipe that connects in series a first indoor coil connected to the expansion valve outlet and a second indoor coil connected to the compressor inlet and arranged downstream in the air flow path with respect to the first indoor coil. By arranging the piping from the coil to the automatic expansion valve inlet in a heat exchange relationship, and adjusting the degree of superheating of the automatic expansion valve in conjunction with the cooling/dehumidification switching operation, cooling is achieved by overheating on the low side. The operation is characterized in that dehumidifying operation is performed at a high degree of superheat.

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

Figure 2 is a device circuit diagram of a separate air conditioner.The outdoor unit has a compressor 1, an air-to-air fish-shaped outdoor coil 2 that acts as a condenser, and an outdoor fan 3, and the indoor unit has a cooling air conditioner. The first indoor coil 4 acts as an evaporator during both air conditioning and dehumidification, and the second indoor coil acts as an evaporator during cooling and as a reheater during dehumidification.
It has an indoor coil 5, an indoor fan 6, an automatic expansion valve 7 for superheat control (hereinafter abbreviated as expansion valve 7), and a heat exchange device 10.

From the discharge port of the compressor 1 to the suction port, an outdoor coil 2,
The outer passage 11a of the heat exchange device, the expansion valve 7, the first indoor coil 4, the inner passage 12 of the heat exchange device 10, and the second indoor coil 5 are connected by piping in this order, and the control element of the expansion valve 7 is A refrigerating circuit is constructed by attaching a temperature sensing tube 8 to a low pressure connecting pipe 13 extending from the second indoor coil 5 to the suction port of the compressor 1.

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 T and the heat exchange device 10 constitute the main components that characterize the present invention, and the expansion valve 7, whose schematic structure is shown in FIG. A spring 16 is built into the valve body 15 and has an elastic force that mechanically connects the bellows 14 and the valve body 15 and presses the valve body 15 in the closing direction.

The upper chamber of the bellows 14 has a temperature sensing cylinder 8 which is a control element.
forming a pressure chamber 17 for transmitting the refrigerant pressure within;
By connecting the temperature sensing cylinder 8 to this pressure chamber 17,
The temperature sensing cylinder 8 detects the temperature of the low-pressure refrigerant gas exiting the second indoor coil 5, and the expansion valve 7 adjusts its opening according to a predetermined degree of superheating.

The opening of the expansion valve 7 is automatically controlled by the balance of three forces as follows.

That is, the force acting to open and close the valve is a force pb corresponding to the pressure inside the temperature sensing cylinder 8, that is, the force acting on the upper surface of the bellows 14 in the pressure chamber 17 partitioned by the bellows 14,
The force acting in the opening direction and the force pz equivalent to the evaporation pressure t
, that is, a force that acts on the lower surface of the bellows 14 in the direction of closing the valve 15, and a force F of the spring 16, that is, a force that transmits the load below the bellows 14 through the stem and acts in the direction of closing the valve 15. , 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.

Here, if the spring force F is adjusted slightly stronger than in the normal case, the valve opening degree becomes slightly smaller.

This expansion valve 5 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 15 of the expansion valve 5 is increased, the valve 15 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, an indirect electric heater 9 is provided in the temperature sensing cylinder 8, and by adjusting the heating capacity, the pressure inside the temperature sensing cylinder 8 can be changed at will.

The indirect electric heater 9 may be implemented by, for example, wrapping a linear electric heater around the cylindrical body of the temperature-sensing cylinder 8, or inserting a thin plate electric heater into the contact area between the temperature-sensing cylinder 8 and the pipe 13. This can be easily achieved as an indirect heating structure.

In this case, the spring force and the heating capacity of the electric heater 9 are set according to the following procedure.

That is, when the electric heater 9 is heated at its rated capacity, the spring elasticity of the expansion valve 7 is adjusted to the enhanced side so that a predetermined standard superheat degree, for example, 5° C., is obtained for the standard refrigeration load, and the expansion is performed. What is necessary is to increase the degree of static superheating of the valve T.

With this structure, the degree of superheating of the low-pressure refrigerant gas can be adjusted to two levels, 5°C and 20°C, by turning on and off the electric heater 9, and the degree of superheating can be adjusted from outside the valve body. It can be formed into a variable superheat deformation expansion valve that can be adjusted in height in stages.

An example of the electric circuit that controls the operation of the air conditioner configured as described above is shown in Fig. 3.
9 and the outdoor fan motor 19 simultaneously, and the indoor fan motor 20 is operated at low speed, medium speed, high speed, or stopped.
A dehumidification changeover switch 22 is provided, and a circuit is constructed in which the switch 22 and the electric heater 9 are connected in series and then connected between the power sources.

The cooling/dehumidification selector switch 22 is closed during cooling operation;
This is a single-pole, single-throw switch that opens when dehumidifying.

In addition, reference numeral 23 in FIG. 3 is a temperature adjustment switch that is opened to stop the compressor motor 19 and the outdoor fan motor 19 when the temperature of the indoor air falls below a predetermined temperature.

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

First, after closing the switch 22 to the cooling side and energizing the electric heater 9, the selection switch 21 is switched to static, strong, or sudden collapse, and power is supplied to each motor 18, 19, 20 for compression. The fan 1, the outdoor fan 3, and the indoor fan 6 are respectively driven.

When operated in this manner, the compressor 1, the outdoor coil 2 acting as a condenser, the outer passage 11a of the heat exchange device 10, and the expansion valve 7
, the first indoor coil 4 acting as an evaporator, the inner passage 12 of the heat exchange device 10, the second indoor coil 5 acting as an evaporator, and the compressor 1, forming a cycle in which the refrigerant circulates in this order. The temperature-sensing cylinder 8 that senses the temperature of the refrigerant gas exiting the compressor 5 is also affected by the heat of the electric heater 9, and adjusts the valve opening of the expansion valve 7 whose superheat degree is set to a high degree of 20'C, for example. The refrigerant gas temperature sucked into 1 is set to a superheat degree of 5℃l.
Cooling operation is performed while this is maintained.

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 outdoor 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 exchange device 10, and while passing through the outer passage 11a, it is supercooled by the low-pressure, low-temperature refrigerant e flowing out from the first indoor coil 4 (state at point C), and reaches the expansion valve 7. .

The liquid refrigerant, which has been decompressed and expanded by the expansion valve 7 and has a low pressure and low temperature (state at point d), flows into the first indoor coil 4 and exchanges heat with the indoor air induced by the indoor fan 6 [7
After the room air is cooled L7 and some of the liquid refrigerant evaporates (point e), it flows into the heat exchange device 10.

The low-pressure refrigerant that has flowed into the inner passage 12 of the heat exchange device 10 is heated by the high-pressure liquid refrigerant O from the outdoor coil 2 and reaches state f, and then enters the second indoor coil 5 and then further into the first indoor coil. It exchanges heat with indoor air cooled by coil 4,
The indoor air is evaporated while being further cooled to become a gas refrigerant (point g) having a predetermined degree of superheating, for example, 5° C., and is sucked into the compressor 11.

The state changes during the refrigerant circulation process are as described above.On the other hand, the air cooled by the first and second indoor coils 4.5 is circulated indoors 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 exchanger 10 (point in FIG. 4).

From point f to point f), one feels that the cooling capacity is decreasing, but since the high-pressure liquid refrigerant flowing into the expansion valve 7 is supercooled by the amount of heating (from point C to point C in the figure) to)
, the cooling capacity does not decrease at all due to the heat exchange in the heat exchange device 10.

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

The selector switch 22 is set to the dehumidifying operation side, that is, the open side, the electric heater 9 is deactivated, and the selection switch 21 is switched to quiet, strong, or sudden.

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 exchange device 10, and while passing through the outer passage 11a, it is supercooled by the low-pressure low-temperature refrigerant flowing out from the first indoor coil 4 (point C').
, to the expansion valve 7.

Here, the electric heater 9 attached to the temperature sensing cylinder 8 of the expansion valve 7 is inactive and does not generate any heat, so the temperature sensing cylinder 8 detects only the temperature of the low pressure refrigerant, and the degree of superheating of the refrigerant is determined by the cooling temperature. The expansion valve operates so that the temperature is higher than during operation, for example, 20°C.

Therefore, the opening degree of the expansion valve 7 becomes smaller than during the cooling operation.

Therefore, the low-pressure refrigerant (point d'
) flows into the first indoor coil 4 and exchanges heat with the indoor air induced by the indoor fan 6 to cool and dehumidify the indoor air, while all the refrigerant evaporates and becomes a gas refrigerant with a constant degree of superheat, for example, 7°C. (point e/) and flows into the heat exchange device 10.

Next, while flowing through the inner passage 12, the low-pressure refrigerant that has flowed into the heat exchange device 10 is heated by exchanging heat with the liquid-gas mixed refrigerant flowing out from the outdoor coil 2, and is heated to a high temperature, e.g.
The refrigerant becomes a low-pressure refrigerant at 0° C. (point f') 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').
The temperature reaches 0°C and the air is sucked into the compressor 1&.

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

In this manner, the refrigeration system of the present invention uses one expansion valve 7 to cool the electric heater 9 by simply turning on and off the electric heater 9 and adjusting the degree of superheat in stages from outside the valve body. It is possible to switch between operation and dehumidification operation.

In addition, if a two-speed type motor is used as the outdoor fan motor 19 in the above-mentioned device, and the rotation speed of the motor 19 is switched during dehumidification operation, the outdoor fan can be set to a low air volume to perform warm air dehumidification or high air volume. It is possible to control the dehumidification with cold air.

Next, FIG. 6 shows an electric circuit according to another example of the device of the present invention. By controlling the phase of the thyristor 27 connected in series with the electric heater 9, the electric heater 9 can be controlled from O to the maximum value. It is configured to apply a continuously variable voltage.

That is, by operating the voltage setting variable resistor 24, the voltage amplifier 2
When the output voltage of the thyristor 5 is adjusted in level, the output of the thyristor 27 is controlled by the phase control circuit 26 which generates a gate signal with a firing angle proportional to the output voltage.

By using the heating circuit, the maximum voltage is applied to the electric heater 9 during cooling operation, and the apparent superheating degree of the expansion valve 7 is set to a predetermined low temperature range, while the electric heater 9 is applied during dehumidification operation. By variously adjusting the voltage value applied to the heater 9 and varying the apparent degree of superheating within the high temperature range, it is possible to select at any time between heating, constant temperature, and cooling dehumidification operations. .

Note that the above example describes the case of a temperature-sensitive expansion valve widely used in conventional refrigeration equipment, but the expansion valve in the device of the present invention can change the acting force exerted on the valve body by changing the electrical input. Possible Japanese Patent Publication No. 46-18696 discloses an electric automatic expansion valve, in which the spring force is mutual (two different springs are associated with the valve body,
Needless to say, a variable spring pressure type temperature-sensitive expansion valve may be used, in which one of the springs can be selected from outside the valve body manually or electromagnetically to act on the valve body.

As described above, the device of the present invention connects the compressor 1 discharge port, the outdoor coil 2, the automatic expansion valve 7 for superheat degree control, the first indoor coil 4, the second indoor coil 5, and the compressor 1 suction port in this order, The expansion valve 7 is formed into a variable superheat deformable expansion valve that can adjust the set value of the degree of superheat stepwise or steplessly (high or low) during refrigeration operation, while the first indoor coil 4 and the second indoor coil 5
A communication pipe connecting the outdoor coil 2 to the automatic expansion valve 7 is configured in a heat exchange relationship, and the degree of superheat of the expansion valve 7 is adjusted in height in conjunction with the cooling/dehumidification switching operation. However, since the configuration is such that cooling operation is achieved by controlling the low range side, and dehumidifying operation is achieved by controlling the high range side, only one expansion valve is required and a solenoid valve, two-way or three-way switching valve is required. This eliminates the need for any switching, simplifies the circuit, and allows for quiet operation with no switching noise.

Furthermore, since the circuit system is designed to subcool the refrigerant in front of the automatic expansion valve 7, the high pressure of the outdoor coil 2 does not rise 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, since it has good ability to follow sudden load changes when switching between cooling and dehumidification and during dehumidification, the risk of liquid return is eliminated.

Furthermore, in the conventional model, the heat exchange area of the condenser was much larger than that of the evaporator, and the amount of throttling in the pressure reducer was large, resulting in a drop in low pressure and easily causing 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.

Furthermore, by simply changing the degree of superheating of the expansion valve 7 from outside the main body, the amount of reheating during dehumidification can be adjusted, and dehumidification with a heating or cooling effect can be performed at any time. This is a refrigeration device with excellent effects.

[Brief explanation of the drawing]

Fig. 1 is an implicit 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 device of the present invention, and Fig. 3 is an electrical circuit diagram of the device shown in Fig. 2. The partial development diagrams, FIGS. 4 and 5, similarly represent the refrigeration cycle during cooling and dehumidification on a Mollier diagram, and FIG. 6 shows the electrical diagram of an air conditioner according to another embodiment of the present invention. It is a developed diagram of the main parts of the circuit. 1...Compressor, 2...Outdoor coil, 4
...First indoor coil, 5...Second indoor coil, 7...Automatic expansion valve for superheat degree control, 8.
...Temperature tube, 9...Heater.

Claims (1)

[Scope of Claims] 1 Compressor 1 discharge port, outdoor coil 2, superheat degree control automatic expansion valve 7, first indoor coil 4, disposed on the downstream side of the first indoor coil 4 in the air flow path The second indoor coil 5 is connected to the suction port of the compressor 1 in this order, and the automatic expansion valve 7 for controlling the degree of superheat is adjusted so that the set value of the degree of superheat is adjusted steplessly or stepwise from outside the valve body during refrigeration operation. While forming an adjustable variable superheat type expansion valve, a connecting pipe connecting the first indoor coil 4 and the second indoor coil 5 and a pipe leading from the outdoor coil 2 to the automatic expansion valve 7 are arranged in a heat exchange relationship. Configure
The degree of superheating of the automatic expansion valve 7 is adjusted in height in conjunction with the cooling/dehumidification switching operation, and is controlled to the low range side for cooling operation, and controlled to the high range side to perform dehumidification operation. Refrigeration equipment capable of cooling and dehumidifying. 2. The cooling/dehumidifying refrigeration system according to claim 1, wherein the automatic expansion valve 7 for controlling the degree of superheat is a variable superheat type expansion valve that can adjust the degree of superheat in two stages. 3. The automatic expansion valve 7 for controlling the degree of superheat described in @ is a variable superheat degree type expansion valve that can adjust the degree of superheat stepwise or steplessly on the high side, and dehumidifies the air with a touch of cold air or air with a touch of warm air. A refrigeration device capable of cooling and dehumidifying according to claim 1.