JPS61107035A - Air conditioner - Google Patents

Abstract

PURPOSE:To prevent a connecting pipeline from being broken, to improve the effect of saving energy, and make it possible to control the change in indoor temperature, by providing control means that allows lowest frequency operation of a rotational frequency variable compressor when the change in torque is low, and prohibits the operation when the change in torque is high. CONSTITUTION:When the heat exchange temperature Tc is equal to or higher than the set value Tcs (Tc-Tcs>=0), that is, the high pressure side is at or over the prescribed value, it is judged that the compression load is at or over a certain value, and when this is detected by an indoor control section 24, the indoor control section 24 and an outdoor control section 41 control to prohibit the operation of a compressor 11 by the lowest frequency F0 (e.g. 20Hz). On the other hand, when the high pressure side is at or below the prescribed value, it is judged that the compression load is at or below a certain value, and when this is detected by the indoor control section 24, the indoor control section 24 and an outdoor control section 41 control to release the prohibition of the operation by the lowest frequency F0.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an air conditioner having a variable rotation speed compressor.

[Technical background of the invention and its problems]

Generally, an air conditioner is equipped with an inverter circuit and a variable rotation speed compressor whose rotation speed changes according to the output frequency of the electric power output from the inverter circuit, and the output frequency of the inverter circuit is adjusted to the air conditioning load. Some systems are designed to operate at the optimum capacity corresponding to the air conditioning load by changing the air conditioning load accordingly.

By the way, in such an air conditioner, when operating,
There is a problem in that vibrations occur in the variable rotation speed compressor in the low frequency operation region. In other words, FIG. 7 shows the variable rotation speed compressor viewed from above, and shows that the compressor body 1 has vibrations in the rotational direction (dashed line arrow) and normal direction vibration (solid line arrow).
This shows that this occurs. Note that 2 in the figure is a suction cup. As shown in Fig. 8, these rotational direction vibrations and normal direction vibrations have the characteristic that the amplitude increases rapidly and with increasing acceleration as the operating frequency decreases.For example, near the lowest operating frequency 20To, the vibrations cause This causes problems such as pipe breakage and increased set vibration. In particular, rotational vibrations arise from torque fluctuations in the compressor, and at around the lowest operating frequency of 20 Hz, they reach 10 times the normal vibrations caused by the unbalanced amount of refrigerant.

To deal with this situation, in the past, the minimum operating frequency of the compressor was kept to around 30)1z, and in situations where a lower operating frequency was required, the compressor was turned on.

It was off.

However, reducing the range of variable capacity and turning the compressor on and off through frequency control is not desirable in terms of energy conservation, and has the disadvantage of large fluctuations in indoor temperature.If possible, it is recommended to lower the minimum operating frequency to about 208 It is desirable to expand the capacity variable range through frequency control and avoid turning the compressor on and off.

[Purpose of the invention]

This invention was made in view of the above circumstances,
The purpose of this is to suppress compressor vibration while expanding the range of variable capacity through frequency control.This eliminates the need to turn the compressor on and off, prevents breakage of connecting pipes, and improves energy savings. An object of the present invention is to provide an excellent air conditioner that can improve the temperature and suppress indoor temperature fluctuations.

[Summary of the invention]

This invention focuses on the fact that the torque fluctuation of the compressor, which is a factor of vibration in the rotational direction, is proportional to the compression ratio. When the detection result is less than a certain value, that is, the torque fluctuation is small, the variable rotation speed compressor is allowed to operate at the lowest frequency, and when the detection result of the detection means is more than a certain value, that is, the torque fluctuation is large, the variable rotation speed compressor is allowed to operate. A control means is provided to prohibit operation at the lowest frequency.

[Embodiments of the invention]

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

As shown in Fig. 2, variable rotation speed compressor 11° four-way valve 1
2. Outdoor heat exchanger 13', pressure reducing device such as expansion valve 14
．． and an indoor heat exchanger 15 are sequentially connected to form a heat pump type refrigeration cycle. That is, during cooling operation, the refrigerant flows in the direction of the solid arrow shown in the figure, forming a cooling cycle, and during heating operation, the refrigerant flows in the direction of the broken line arrow, forming a heating cycle. At least the variable rotation speed compressor 11. Four-way valve 1
2. Outdoor heat exchanger 13. Expansion valve 14. An outdoor unit A is configured by an outdoor fan 16 and the like. Furthermore, at least the indoor heat exchanger 15' and the indoor fan 1
7 and the like constitute an outdoor unit B.

FIG. 3 shows the control circuit.

First, 20 is a commercial AC power supply. A noise filter 21 is connected to the power supply 2o. Trance 22. and control unit power supply circuit 2
The indoor control section 24 is connected to the indoor control section 24 via the microcomputer 1 and its peripheral circuits.
5. Initialization circuit 26. and a photothyristor 27 are connected. The photothyristor 27 is turned on and off in response to commands from the indoor control section 24, and transfers serial signals corresponding to various information to the outdoor unit A. In addition, 28 is an indoor air temperature sensor (thermistor), and the output of this indoor air temperature sensor is an A/D
The signal is supplied to the indoor control unit 24 via an analog/digital converter 29. 3o is an indoor heat exchanger temperature sensor that detects the temperature of the indoor heat exchanger, and the output of this indoor heat exchanger temperature sensor 30 is supplied to the indoor controller 24 via the A/D converter 31. It looks like this. On the other hand, an indoor fan motor 17M is connected to the power source 2o via an indoor fan motor power supply circuit 32 and a fan motor drive circuit 33. Here, the fan motor drive circuit 33 switches the rotational speed of the indoor fan motor 17M in response to a command from the indoor control section 24. Then, the output of the power source 20 is output from the power relay 34.
It is designed to be supplied to the outdoor unit A via.

This power relay 34 is turned on and off by a relay driver 35 that responds to commands from the indoor control section 24.

Thus, in the outdoor unit A, the power output supplied from the power relay 34 is supplied to the power supply circuit 40, and the output of this power supply circuit 40 is transmitted to the outdoor control section 41. Inverter control circuit 42. and a transistor drive circuit 43, respectively. The outdoor control section 41 consists of a microcomputer and its peripheral circuits, and externally includes a receiving circuit 44. Relay driver 45. and the inverter control circuit 42 mentioned above are connected. Here, the receiving circuit 44 receives a serial signal transferred from the photothyristor 27 of the indoor unit B, and supplies information based on the serial signal to the outdoor control section 41. The inverter control circuit 42 controls the transistor drive circuit 43 in accordance with commands from the outdoor control section 41. Also, 46 is an outdoor air temperature sensor,
The output of this outdoor air temperature sensor is supplied to the outdoor control section 41 via an A/D converter 47. 4
An outdoor heat exchanger temperature sensor 8 detects the temperature of the unexpected heat exchanger 13, and its output is supplied to the outdoor controller 41 via an A/D converter 49. On the other hand, the power output supplied from the power relay 34 is converted into direct current by a converter circuit 50 and supplied to an inverter circuit 51. This inverter circuit 51
has a large number of switching elements, such as transistors, and these transistors drive the transistor drive circuit 4.
3, the converter circuit 50 converts the DC power from the converter circuit 50 into AC power of a predetermined frequency and voltage, and outputs the AC power. Thus, the output of the inverter circuit 51 is supplied to the compressor motor 11M. Further, the power output supplied from the power relay 34 is supplied to the outdoor fan motor 16M and the four-way valve 12 via relays 52 and 53, respectively. The relays 52 and 53 are driven by a relay driver 45 that responds to commands from the outdoor control section 410.

Next, the operation of the above configuration will be explained with reference to the flowchart of FIG.

Assume that heating operation is currently being performed.

At this time, the indoor control unit 24 detects the indoor air temperature using the indoor air temperature sensor 28, and transfers capacity setting command information corresponding to the indoor air temperature, that is, the air conditioning load, to the outdoor control unit 41. The outdoor control unit 41 gives a command to the inverter control circuit 42 based on the transferred capacity setting command information, and causes the inverter circuit 51 to output AC power at a predetermined frequency and voltage. In this case, if the air conditioning load is large, the inverter circuit 51 outputs high frequency and high voltage AC power, and if the air conditioning load is small, the inverter circuit 51 outputs low frequency and low voltage AC power. Therefore, if the air conditioning load is large, the compressor motor 11M operates at a high rotation speed, and high-capacity heating operation is performed. Also, if the air conditioning load is small, the compressor motor 11
M operates at a low rotation speed, and low-capacity heating operation is performed.

However, the indoor control unit 24 detects the temperature of the indoor heat exchanger 15 using the indoor heat exchanger temperature sensor 30, and indirectly detects the high pressure side pressure based on the heat exchanger temperature TO. 11 compression load is indirectly detected. In this case, if the heat exchanger temperature Tc is the same as or higher than the set value TC3 (Tc-Tcs≧O), that is, if the high-pressure side pressure is more than a predetermined value, it is determined that the compression load is above a certain value. to decide. In this way, when the indoor control unit 24 detects that the compression load is equal to or higher than a certain value, the indoor control unit 24 and the outdoor control unit 41 control the
Operation of the compressor 11 at the lowest frequency Fo (for example 20 H2) is prohibited. In other words, even if the air conditioning load is small and operation at the lowest frequency Fo is required, the output frequency of the inverter circuit 51 will never become FO, and the operating frequency F in that case will be F=FO+Δf(-
For example, it is set to 30 Hz).

On the other hand, if the heat exchanger temperature TO is lower than the set value Tcs (T
c - Tcs<Q), that is, if the high pressure side pressure is below a predetermined value, it is determined that the compression load is below a certain value. In this way, when the indoor control unit 24 detects that the compression load is below a certain value, the inhibition of operation at the lowest frequency of 1”o is canceled under the control of the indoor control unit 24 and the outdoor control unit 41. That is, , if the air conditioning load is small and operation at the lowest frequency Fo is required,
The output frequency of the inverter circuit 51 is FO.

In this way, since operation at the lowest frequency Fo is prohibited only when the compression load of the compressor 11 is large and the torque fluctuation is large, it is possible to expand the capacity variable range by frequency control while suppressing rotational direction vibration. can. Therefore, breakage of the connecting pipe can be prevented, and the compressor 11 can be turned on.

There is no need for off-operation, which improves energy-saving effects.
Furthermore, fluctuations in indoor temperature can be reduced.

In addition, although the case where the compression load of the compressor 11 is detected by the temperature of the indoor heat exchanger 15 has been described, this is a case of heating operation, and the compression load is detected by the temperature of the outdoor heat exchanger 13 during cooling operation. do it.

Further, in the above embodiment, the compression load is detected based on the temperature of the heat exchanger, but the compression load may be detected based on the amount W of air blown into the room as shown in FIG. 4.

That is, the indoor control unit 24 controls the speed of the indoor fan motor 17M according to the air conditioning load, etc., and indirectly detects the high-pressure side pressure based on the speed of the indoor fan motor 17M. The compression load of the compressor 11 is indirectly detected. In this case, the indoor fan motor 17
If M is a medium speed or a low speed, it is determined that the high pressure side pressure is equal to or higher than a predetermined value, and thereby it is determined that the compression load is in a situation of equal to or higher than a predetermined value. In this way, when the indoor control unit 24 detects that the compression load is equal to or higher than a certain value, the indoor control unit 24 and the outdoor control unit 41 control the operation of the compressor 11 at the lowest frequency Fo (for example, 20 Hz > On the other hand, indoor fan motor 1
If 7M is a high speed, it is determined that the high pressure side pressure is below a predetermined value, and thereby it is determined that the compression load is below a certain value. In this way, when the indoor control section 24 detects that the compression load is below a certain value, the inhibition of operation by the lowest frequency FO is canceled under the control of the indoor control section 24 and the outdoor control section 41.

Furthermore, as shown in FIG. 5, the compression load may be detected based on the air temperature Ta. That is, during heating operation, the indoor temperature is detected by the indoor air temperature sensor 28, the high pressure side pressure is indirectly detected based on the indoor air temperature, and the compression load of the compressor 11 is indirectly detected based on this high pressure side pressure. . In this case, if the room temperature is high, it is determined that the high-pressure side pressure is at least a predetermined value, and thereby it is determined that the compression load is at a predetermined value or higher. In this way, the indoor control unit 24 indicates that the compression load is above a certain value.
When detected, the indoor control section 24 and outdoor control section 4
1, the lowest frequency FO (e.g. 20 Hz
) is prohibited from operating the compressor 11. On the other hand, if the indoor air temperature is low, it is determined that the high pressure side pressure is below a predetermined value, and thereby it is determined that the compression load is below a certain value.

In this way, when the indoor control section 24 detects that the compression load is below a certain value, the inhibition of operation by the lowest frequency FO is canceled under the control of the indoor control section 24 and the outdoor control section 41. Note that during cooling operation, operation using the lowest frequency FO is prohibited when the outdoor air temperature is high, and the prohibition is canceled when the outdoor air temperature is low.

Furthermore, as shown in FIG. 6, the III control may be performed in two steps, including detection based on the indoor air flow rate W and detection based on the air temperature Ta, thereby improving the reliability of the control.

〔Effect of the invention〕

As described above, according to the present invention, there is provided a detection means for detecting the compression load of the variable rotation speed compressor, and when the detection result of this detection means is below a certain value, the variable rotation speed compressor is operated at the lowest frequency. A control means is provided that allows the variable rotation speed compressor to operate at the lowest frequency when the detection result of the detection means exceeds a certain value, so that the range of capacity variation by frequency control can be increased while suppressing vibrations of the compressor. This allows for expansion of the compressor.

It is possible to provide an excellent air conditioner that does not require off-operation, prevents connection piping from breaking, improves energy saving effects, and suppresses indoor temperature fluctuations.

[Brief explanation of drawings]

FIG. 1 is a flowchart for explaining the operation of an embodiment of the present invention, FIG. 2 is a configuration diagram of a refrigeration cycle in the same embodiment, FIG. 3 is a configuration diagram of a control circuit in the same embodiment, and FIG. 4 , FIG. 5, and FIG. 6 are flowcharts for explaining the operation of other embodiments of the present invention, FIG. 7 is a diagram for explaining the vibration of the variable rotation speed compressor, and FIG. FIG. 3 is a diagram showing the correspondence between the operating frequency and vibration amplitude of the variable compressor. 11...Variable rotation speed compression opening, A...Outdoor unit,
B...Indoor unit, 24...Indoor control section, 28.
... Indoor air temperature sensor, 30... Indoor heat exchanger temperature sensor, 41... Outdoor control unit, 46... All air temperature sensor, 48... Outdoor heat exchanger temperature sensor.

Claims (4)

[Claims] (1) In an air conditioner comprising an inverter circuit and a variable rotation speed compressor whose rotation speed changes according to the output frequency of the inverter circuit, the air conditioner controls the output frequency of the inverter circuit according to the air conditioning load, wherein the compressor a detection means for detecting a compression load; and when the detection result of the detection means is below a certain value, the compressor is allowed to operate at the lowest frequency, and when the detection result of the detection means is above a certain value, the compressor is operated at the lowest frequency. An air conditioner comprising: control means for prohibiting operation of the compressor. (2) Claim 1, characterized in that the detection means detects the compression load based on the temperature of the heat exchanger.
Air conditioner as described in section. (3) The air conditioner according to claim 1, wherein the detection means detects the compression load based on the amount of air blown into the room. (4) The air conditioner according to claim 1, wherein the detection means detects the compression load based on the air temperature.