JP3185791B2 - Control device for 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 the control of an air conditioner, and more particularly to the control of a room temperature and the shutdown of a compressor by performing a dehumidifying operation rather than a cooling operation when a cooling sensible heat load is small. The present invention relates to a control device for an air conditioner which prevents humidity and reduces humidity.

[0002]

2. Description of the Related Art Conventionally, in the dehumidifying operation of an air conditioner, when the room temperature is higher than a set temperature, the number of revolutions of the indoor fan is increased and the number of revolutions of the compressor is increased to quickly approach the set temperature. On the other hand, when the room temperature is close to the set temperature, the dehumidification is performed by lowering the rotation speed of the indoor fan and lowering the rotation speed of the compressor to reduce the sensible heat so as not to stop the operation of the compressor. It has been proposed (see, for example, JP-A-59-185932).

However, since the sensible heat component is not zero, the room temperature gradually decreases, and when the temperature falls below the set temperature, the operation of the compressor stops. In particular, when the outside air temperature is low, the cooling sensible heat load is small, so that the room temperature drops immediately after the operation of the air conditioner is started, the operation time of the compressor is short, and there is a problem that the humidity does not drop sufficiently.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and when the cooling sensible heat load is small, the dehumidifying operation time is extended to increase the humidity. It is an object of the present invention to provide an air conditioner that can reduce air pollution.

[0005]

Means for Solving the Problems To achieve the above object, an invention according to claim 1 of the present invention comprises a variable displacement compressor, a four-way valve, an outdoor heat exchanger, and a pressure reducer. When the outdoor unit and the indoor unit having the variable air flow type indoor fan and the indoor heat exchanger are connected to each other, and the difference temperature ΔT (Tr−Ts) between the room temperature Tr and the set temperature Ts is higher than the predetermined value Tk, the indoor unit The fan is operated at high speed and the compressor is also rotated at high speed to perform cooling operation, and the difference between the room temperature Tr and the set temperature Ts △ T
When (Tr−Ts) becomes smaller than the predetermined value Tk, the outdoor fan provided in the outdoor unit of the air conditioner that performs the dehumidifying operation by reducing the rotation speed of the indoor fan and reducing the rotation speed of the compressor. Control means for changing a preset value Tk for switching between the cooling operation and the dehumidifying operation based on the outside air temperature Tg detected by the temperature detecting means is provided.

Further, the invention according to a second aspect is characterized in that there is provided control means for changing a predetermined value Tk according to a difference (Tg-Ts) between the outside temperature Tg and the set temperature Ts.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a refrigeration cycle of an air conditioner according to the present invention.
The indoor unit 4 is connected via a connection pipe 6.

The outdoor unit 2 includes a variable displacement compressor 8 (hereinafter simply referred to as a compressor) driven by an inverter, a four-way valve 10 for switching between cooling and heating, an outdoor heat exchanger 12, and an electric expansion valve 1.
6 is provided, while the indoor unit 4 has an indoor heat exchanger 18.
Is provided. In the drawing, reference numerals 20 and 22 denote an outdoor fan and an indoor fan provided adjacent to the outdoor heat exchanger 12 and the indoor heat exchanger 18, respectively. Reference numeral 26 denotes a suction temperature sensor provided in the indoor unit 4. , 28 are outside temperature sensors provided in the outdoor unit 2.

In the refrigeration cycle having the above configuration, during the cooling or dehumidifying operation, the refrigerant discharged from the compressor 8 flows through the four-way valve 10 to the outdoor heat exchanger 12, where the refrigerant and the outdoor air exchange heat. The liquid is condensed and liquefied, and then depressurized by passing through the electric expansion valve 16. Since the electric expansion valve 16 is pulse-controlled by a stepping motor or the like so as to have an opening corresponding to the load in the room, the refrigerant Also, the pressure becomes low at a flow rate corresponding to the indoor load, flows into the indoor unit 4 via the connection pipe 6, evaporates in the indoor heat exchanger 18, and then returns to the compressor 8 via the connection pipe 6 and the four-way valve 10. Inhaled.

Next, control of the compressor frequency and the electric expansion valve will be described. FIG. 2 is a block diagram showing the flow of control of the compressor frequency and the electric expansion valve.

First, in the indoor unit 4, the suction temperature sensor 2
The output 6 (room temperature) is sent from the room temperature detection circuit 40 to the operation mode determination circuit 42 as a temperature signal, while the operation setting reception circuit 38 displays the received set temperature and set operation mode in the operation mode. The outdoor temperature signal from the outdoor unit 2 is received by the signal receiving circuit 62 and transmitted to the operation mode determining circuit 42. In the operation mode determination circuit 42, the temperature difference Δt is calculated from the room temperature Tr and the set temperature Ts.
Is determined, and it is determined whether the cooling operation or the dehumidifying operation is to be performed based on the temperature difference Δt and the outside temperature Tg.

Further, the frequency No. (for example, an integer in the range of 0 to 8) is obtained by performing a predetermined calculation from the temperature difference Δt, and the frequency No. is transmitted to the signal transmitting circuit 50. Frequency N to the second signal receiving circuit 52.
Send o. Frequency No. received by the signal receiving circuit 52
Are the compressor frequency calculation circuit 54 and the expansion valve opening calculation circuit 5
6 is sent.

In the compressor frequency calculation circuit 54, the indoor unit 4
The operation frequency of the compressor 8 is determined by performing a predetermined calculation on the basis of the frequency No received from.

Similarly, in the expansion valve opening calculation circuit 56, the opening of the electric expansion valve 16 is determined by performing a predetermined calculation based on the frequency No received from the indoor unit 4.

The calculation results obtained by the compressor frequency calculation circuit 54 and the expansion valve opening calculation circuit 56 are converted to a compressor drive circuit (not shown) and an expansion valve drive circuit (not shown) as a frequency signal and an expansion valve opening signal. (Not shown) to control the frequency of the compressor 8 and the opening degree of the electric expansion valve 16.

Thereafter, at predetermined intervals, the operating frequency of the compressor 8 and the valve opening of the electric expansion valve 16 are calculated based on the frequency No, and the frequency control of the compressor 8 and the opening control of the electric expansion valve 16 are performed. Done.

Since the heating operation is not the main feature of the present invention, its description is omitted.

FIG. 3 shows the indoor unit 4, in which a plurality of suction ports 30 are formed in an upper portion and a front portion of the main body, and an outlet 32 is formed in a lower portion of the main body. An indoor heat exchanger 18 and an indoor fan 22 are provided in an air passage 34 that communicates the suction port 30 and the air outlet 32, and a wind direction changing blade 36 is swingably attached to the air outlet 32. I have. The suction temperature sensor 26 is arranged adjacent to the front of the main body.

Next, the control according to claim 1 of the present invention will be described below. FIG. 4 shows a control flow in the dehumidification mode. First, in step S1, the difference temperature Δt between the room temperature (Tr) detected by the suction temperature sensor 26 and the set temperature (Ts) set by the user is determined. Is calculated.
In step S2, the outside temperature Tg is determined, and T1 is determined.
If it is determined that it is larger than (for example, 25 ° C.), the process proceeds to step S3. In step S3, the temperature difference Tk for switching between the cooling operation and the dehumidifying operation is set to T2 (for example, 2.0
° C).

If it is determined in step S2 that the outside air temperature Tg is smaller than T1, the process proceeds to step S4.
° C). In step S5, the temperature difference Δt is compared with Tk. If the temperature difference is higher than Tk, the process proceeds to step S6 to set the operation mode to the cooling operation. In step 7, the frequency No is determined based on the temperature difference Δt as described above. You.

If Tk is lower than Tk, the operation proceeds to step S8, in which the operation mode is the dehumidification operation, and in step 9, the temperature difference Δ
The frequency No is determined based on t. Step S10
, The operating frequency of the compressor 8 and the electric expansion valve 16
Is transmitted to the outside of the room.

The sampling of the suction temperature is performed every predetermined time (for example, about 1 second), and the operating condition is determined by calculating Δt each time.

Here, in the cooling operation in the dehumidifying mode, when the temperature difference Δt approaches Tk, the compressor frequency decreases extremely (frequency No. is, for example, 3), while the indoor fan 22 is Hi (high speed). ) To Lo (low speed).

The dehumidifying operation is performed according to the frequency No. of the compressor. Is set to 1, for example, while the air volume from the indoor fan 22 is
The sensible heat and the feeling of cool air are reduced by setting the intermediate air volume or the light air smaller than Lo.

FIG. 5 shows a control flow according to a second embodiment of the present invention. First, in step S1, the room temperature (Tr) detected by the suction temperature sensor 26 and the set temperature (Ts) set by the user. Is calculated. In step S2, the difference between the outside air temperature Tg and the set temperature Ts (T
g-Ts), and if it is determined that the difference is greater than T1 (for example, 5 ° C.), the process proceeds to step S3. Subsequent steps are the same as the dehumidification control method in the first aspect, and will not be described.

FIG. 6 shows an example of a time chart when the above-described control according to the present invention is employed. FIG.
As shown in (2), by earlier switching from the cooling operation to the dehumidifying operation, the decrease in the room temperature is delayed, and the humidity can be reduced by keeping the compressor operating.

[0027]

Since the present invention is configured as described above, it has the following effects. According to the invention described in claim 1 of the present invention, the cooling sensible heat load is detected at the outside air temperature, and even when the cooling sensible heat load is small, the operation time of the compressor is increased by expanding the dehumidification operation region. Prolonged, humidity can be reduced.

According to the second aspect of the present invention, the cooling sensible heat load is accurately detected based on the difference between the outside air temperature and the set temperature, and even when the cooling sensible heat load is small, the dehumidifying operation area is expanded. As a result, the operating time of the compressor can be prolonged, and the humidity can be reduced.

[Brief description of the drawings]

FIG. 1 is a piping diagram of a refrigeration cycle of an air conditioner according to the present invention.

FIG. 2 is a block diagram showing a flow of control of a compressor frequency and an electric expansion valve in the refrigeration cycle of FIG. 1;

FIG. 3 is a schematic longitudinal sectional view of an indoor unit.

FIG. 4 is a control flowchart of the control device according to claim 1 of the present invention.

FIG. 5 is a control flowchart of a control device according to a second embodiment of the present invention.

FIG. 6 is a time chart of a case where the control of the present invention is adopted and a time chart of a conventional dehumidification control.

[Explanation of symbols]

 Reference Signs List 2 outdoor unit 4 indoor unit 8 compressor 10 four-way valve 12 outdoor heat exchanger 16 electric expansion valve 18 indoor heat exchanger 20 outdoor fan 22 indoor fan 26 suction temperature sensor 28 outside air temperature sensor 30 suction port 32 blowout port 36 wind direction changing blade

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-185932 (JP, A) JP-A-4-155139 (JP, A) JP-A-4-203739 (JP, A) Jpn. 56633 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F24F 11/02 102 F24F 11/02

Claims (2)

(57) [Claims] An outdoor unit having a variable capacity compressor, a four-way valve, an outdoor heat exchanger and a decompressor, and an indoor unit having a variable air flow type indoor fan and an indoor heat exchanger are connected to each other.
The difference temperature △ T (Tr−Ts) between r and the set temperature Ts is a predetermined value T.
When the temperature is higher than k, the indoor fan is operated at a high speed and the compressor is rotated at a high speed to perform the cooling operation. The difference temperature ΔT (Tr−Ts) between the room temperature Tr and the set temperature Ts is equal to the predetermined value Tk.
When it is smaller than the above, in the air conditioner performing the dehumidifying operation by reducing the rotation speed of the indoor fan and reducing the rotation speed of the compressor, the outside temperature detected by the outdoor temperature detection means provided in the outdoor unit is reduced. A control device for an air conditioner, comprising: control means for changing the predetermined value Tk according to a temperature Tg. 2. An outside air temperature T instead of the control means according to claim 1.
g and the set temperature Ts, the difference value (Tg-Ts) is set to a predetermined value T.
A control device for an air conditioner, comprising a control means for changing k.