JP3336896B2 - Air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to outdoor piping control in a heat pump type air conditioner capable of both cooling and heating operations.

[0002]

2. Description of the Related Art A conventional refrigeration cycle of an air conditioner and control of the outside air temperature will be described with reference to FIG.

[0003] Reference numeral 1 denotes an outdoor unit in which a compressor 2, a four-way valve 5, an outdoor heat exchanger 3, and an expansion valve 4 are arranged in an arrangement as shown in the figure, and refrigerant flows during cooling in this order. Indoor unit 7
Head for. Reference numeral 9 denotes a suction sensor for detecting the outdoor air temperature, and reference numeral 11 denotes a pipe temperature sensor provided in the outdoor unit heat exchanger. The indoor unit 7 has a heat exchanger 8, and heat is exchanged by a blower. Reference numeral 6 denotes a sensor for detecting a suction temperature.

[0004] In this air conditioner, the operation during cooling is as described above, but in the heat pump, the refrigerant flows in the opposite flow during the heating operation. That is, the refrigerant flowing out of the compressor 2 is directed to the indoor unit 7 by the four-way valve 4 this time. Here, the heat is deprived (dissipated) and returns to the outdoor unit 1 via the pipe. If this heating operation is continued, in the outdoor unit, frost formation proceeds during heating, and heat exchange gradually becomes impossible. Therefore, it is necessary to reverse the refrigeration cycle (cooling operation) to melt the frost on the heat exchanger surface. The conventional air conditioner of this type was installed at the center of the heat exchanger of the outdoor unit because it did not detect the high pressure and the end of melting of the frost.

[0005]

However, in this position, the detection of the outdoor high pressure during cooling can be detected with considerable accuracy, but the end of melting of frost cannot be detected accurately, and frost may remain. There is.

In view of the above problems, the outside air temperature control of the present invention is
This enables accurate detection of high pressure and accurate detection of the end of defrosting without complicating the configuration of the refrigeration cycle.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an outside air temperature control according to the present invention comprises a variable frequency compressor, a four-way valve, an outdoor unit heat exchanger, an electromagnetic expansion valve which can be electrically controlled. And an indoor unit having an indoor heat exchanger are connected by a connection pipe to form a refrigeration cycle,
The indoor unit is provided with an indoor temperature setting means capable of setting a desired indoor temperature and an indoor temperature detecting means for detecting the indoor temperature.The indoor temperature setting means and the indoor temperature detecting means determine the set indoor temperature and the indoor temperature. A differential temperature calculating means for calculating a differential temperature of the compressor, a compressor frequency control means for controlling the frequency of the variable frequency compressor based on the calculation result, provided in the refrigeration cycle system of the outdoor unit, during cooling operation A temperature detection sensor is provided in a pipe near the heat exchanger outlet of the outdoor unit, and a predetermined value is added to the temperature to calculate a high pressure value during cooling, and the detected temperature is used for heating. During the defrosting operation for defrosting the frost of the outdoor unit heat exchanger generated during the operation, the detection temperature of the end of the defrosting in the method of switching the four-way valve (four-way valve defrosting) also serves as the refrigeration cycle. Multiple configurations Without having to, and makes it possible to accurately detect the defrosting terminates when accurate detection of the pressure.

In the cooling operation, when calculating the high pressure value, the numerical value to be added to the detected temperature is changed according to the outdoor air temperature, thereby enabling more accurate high pressure detection and detection of the completion of defrosting. is there.

In addition, a multi-type air conditioner constituted by a plurality of indoor units can sufficiently exhibit the effect of one outdoor unit.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention of claim 1 comprises an outdoor unit having a variable frequency compressor, a four-way valve, an outdoor heat exchanger, an electromagnetic expansion valve which can be electrically controlled, and an indoor heat exchanger. And an indoor unit having a refrigeration cycle constituted by connecting pipes, wherein the indoor unit is provided with temperature setting means for setting a desired indoor temperature and indoor temperature detecting means for detecting an indoor air temperature. A temperature difference calculating means for calculating a temperature difference between the set indoor temperature and the indoor temperature from the temperature setting means and the indoor temperature detecting means is provided, and the frequency of the variable frequency compressor of the outdoor unit is controlled based on the calculation result. In the refrigeration cycle system of the outdoor unit, a temperature detection sensor is disposed in a pipe near the heat exchanger outlet of the outdoor unit during a cooling operation, and a predetermined temperature is set at this temperature. Add a value to cool The high pressure value is calculated, and the detected temperature is removed by a method of switching the four-way valve during the defrosting operation for removing the frost of the outdoor unit heat exchanger generated during the heating operation (four-way valve defrosting). It becomes possible to also serve as the detection temperature of the end of the frost.

Further, when calculating the high pressure value during the cooling operation, by changing the numerical value to be added to the detected temperature depending on the outdoor air temperature, the high pressure can be detected more accurately.

Further, the same effect as described above can be obtained in an air conditioner comprising a plurality of indoor units with respect to one outdoor unit.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a refrigeration cycle diagram in a first embodiment having an outside air temperature control according to the present invention.

The description of the numbers in the figure which are the same as those in the prior art will be omitted. Here, reference numeral 10 denotes a pipe temperature sensor of the present invention. During the cooling operation, the sensor 10 is located at a point D on the Mollier diagram in FIG. 2 and detects the temperature T1. However, this temperature does not indicate the temperature of the heat exchanger in the refrigeration cycle. This is because the sensible heat of the refrigerant changes from point C to point D in the Mollier diagram (sub-cooling), and the temperature decreases. Therefore, the temperature change ΔT is added to T1 to calculate the high-pressure side heat exchanger temperature. Further, in detecting the completion of defrosting when the frost formed on the outdoor heat exchanger 3 caused by the heating operation is defrosted by the cooling operation, the frost is completely melted because the frost is completely attached to the outlet of the heat exchanger 3. It becomes possible to accurately detect the temperature when the power is turned off. FIGS. 3 and 4 are block diagrams showing these ideas (FIG. 3 shows a cooling operation, and FIG. 4 shows a defrosting operation).
It is.

Next, a second embodiment of the present invention will be described with reference to a Mollier diagram shown in FIG.

Based on the symbols without """and""" in the figure, if the outdoor air temperature becomes low,
This refrigeration cycle moves from the "ABCDAEA" cycle to "A'-B'-C'-D'-E '". At this time, the temperature change ΔT between C and D is C′-D ′
The temperature change is ΔT ′ during the period and is larger than ΔT.

On the other hand, when the outside air temperature is high, "A"-
B "-C" -D "-E""and the temperature change [Delta] T" of C "-D" becomes smaller than [Delta] T.

As described above, the temperature to be added to the detected pipe temperature T1 during the cooling operation can be more accurately obtained by changing the temperature depending on the outside air temperature. FIG. 6 is a block diagram showing this idea. ΔT '
Is expressed as ΔT ′ (t) as a function of the outside air temperature t.

FIG. 7 is a refrigeration cycle diagram when the present invention is applied to a multi-type air conditioner. Here 1
Reference numeral 2 denotes a branch unit for branching. 13 is an electromagnetic expansion valve for adjusting the amount of refrigerant flowing to each indoor unit. Also in this case, the behavior of the refrigeration cycle is the same, and the pipe temperature sensor 10 plays the same role as in the first and second embodiments.

[0021]

As is clear from the above embodiment, according to the present invention, an outdoor unit having a variable frequency compressor, a four-way valve, an outdoor heat exchanger, and an electromagnetic expansion valve which can be electrically controlled is provided. An indoor unit having an indoor heat exchanger is connected by a connection pipe to form a refrigeration cycle, and the indoor unit has a temperature setting unit for setting a desired indoor temperature and an indoor temperature detecting unit for detecting an indoor air temperature. And a temperature difference calculating means for calculating a temperature difference between the set indoor temperature and the indoor temperature from the indoor temperature setting means and the indoor temperature detecting means, and based on the calculation result, the frequency variable type of the outdoor unit. Compressor frequency control means for controlling the frequency of the compressor is provided, and in the refrigeration cycle system of the outdoor unit, a temperature detection sensor is disposed in a pipe near the heat exchanger outlet of the outdoor unit during cooling operation. At this temperature A method of switching the four-way valve during a defrosting operation for defrosting the frost of the outdoor unit heat exchanger generated during the heating operation by calculating a high pressure value during cooling by adding a constant value, (Four-way valve defrosting), it is possible to also serve as the detection temperature of the end of defrosting.

Further, when calculating the high pressure value during the cooling operation, by changing the numerical value to be added to the detected temperature depending on the outdoor temperature, the high pressure can be detected more accurately.

Further, the same effect as described above can be obtained in an air conditioner comprising one indoor unit and a plurality of indoor units.

[Brief description of the drawings]

FIG. 1 is a refrigeration cycle diagram of a first embodiment of the present invention.

FIG. 2 is a Mollier chart showing a behavior of a refrigeration cycle in the embodiment.

FIG. 3 is a block diagram at the time of cooling operation of the embodiment.

FIG. 4 is a block diagram at the time of defrosting of the embodiment.

FIG. 5 is a Mollier diagram showing the behavior of a refrigeration cycle in a second embodiment of the present invention.

FIG. 6 is a block diagram at the time of cooling operation of the embodiment.

FIG. 7 is a refrigeration cycle diagram of a third embodiment of the present invention.

FIG. 8 is a refrigeration cycle diagram of a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 outdoor unit 2 compressor 3 outdoor heat exchanger 4 electromagnetic expansion valve 5 four-way valve 6 outdoor suction sensor 7 indoor unit 8 indoor heat exchanger 9 indoor suction sensor gas side main pipe 10 outdoor pipe temperature sensor 11 outdoor pipe temperature sensor 12 branch unit 13 Solenoid expansion valve

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-8-271016 (JP, A) JP-A-4-251144 (JP, A) JP-A-61-107035 (JP, A) JP-A-61-17035 93359 (JP, A) JP-A-60-155283 (JP, A) JP-A-7-280365 (JP, A) JP-A-1-134170 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F25B 47/02 550

Claims (3)

(57) [Claims] An outdoor unit having a variable frequency compressor, a four-way valve, an outdoor heat exchanger, an electromagnetic expansion valve which can be electrically controlled, and an indoor unit having an indoor heat exchanger are connected by connecting pipes. Connected to form a refrigeration cycle, and to the indoor unit,
A temperature setting means for setting a desired indoor temperature and an indoor temperature detecting means for detecting an indoor air temperature are provided, and a difference between the set indoor temperature and the indoor temperature is calculated from the indoor temperature setting means and the indoor temperature detecting means. Providing a differential temperature calculating means, provided with compressor frequency control means for controlling the frequency of the variable frequency compressor of the outdoor unit based on the calculation result of the differential temperature calculating means, in the refrigeration cycle system of the outdoor unit, A temperature detection sensor is provided in a pipe near the heat exchanger outlet of the outdoor unit during the cooling operation, and a predetermined numerical value is added to this temperature to calculate a high pressure value during cooling. In the system that switches the four-way valve during the defrosting operation for defrosting the frost of the outdoor unit heat exchanger generated during the heating operation (four-way valve defrosting), the detection temperature of the sensor of Air conditioner that doubles 2. The air conditioner according to claim 1, wherein a value to be added to the detected temperature is changed according to the outdoor temperature when calculating a high pressure value during the cooling operation. 3. An air conditioner comprising a plurality of indoor units with respect to one outdoor unit, wherein the air conditioner according to claim 1 and claim 2 is provided.