JPH03251637A - Operation controller for air conditioner - Google Patents

Abstract

PURPOSE:To carry out precise control of superheat degree by a method wherein when pressure of low pressure refrigerant reaches a prescribed value within a detection range of a pressure detecting means, the air volume of a fan is reduced. CONSTITUTION:A user's side heat exchanger 15 is blown by a blowing fan 2b. Suction side pressure of a compressor 11 in a refrigerant circuit 1 is detected by a pressure detecting means 4, and outlet side refrigerant temperature of the heat exchanger 15 is detected by a temperature detecting means 3. Low pressure signals from the detecting means 4 and temperature signals from the detecting means 3 are received by a superheat degree control means 52, which controls an expansion mechanism 14, so that the superheat degree of a refrigerant reaches a prescribed value for adjusting the flow amount of refrigerant. In addition, the detecting means 4 has a set detecting range. A wind volume reducing means 54 receives the low pressure signals from the detecting means 4. In this constitution, when a detected pressure of the detecting means 4 rises up to a prescribed value in the vicinity of the upper limit of the set detection range, the wind volume reducing means 54 reduces the wind volume of the blowing fan 2b. As the result of this, the heat exchange volume is decreased to drop down the pressure of the low pressure refrigerant.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an operation control device for an air conditioner, and in particular,
This relates to measures to control the degree of superheating.

(Prior art) In general, air conditioners are
As disclosed in the publication, a compressor, a condenser,
Some devices include a closed refrigerant circuit in which an expansion valve and an evaporator are sequentially connected through refrigerant piping. Furthermore,
In the refrigerant circuit, a pressure sensor and a temperature sensor are attached to the suction pipe of the compressor, and the pressure sensor detects the low-pressure refrigerant pressure, while the temperature sensor detects the refrigerant temperature.

A refrigerant pressure equivalent saturation temperature is calculated from the pressure detected by the pressure sensor, and the degree of superheating of the refrigerant is detected from the refrigerant pressure equivalent saturation temperature and the temperature detected by the temperature sensor. Furthermore,
The degree of opening of the expansion valve is controlled so that the degree of superheat reaches a predetermined value, for example, 5° C., thereby preventing liquid from returning to the compressor.

(Issue 8 to be solved by the invention) In the operation control device for the air conditioner described above, since the pressure sensor detects the low pressure refrigerant pressure, the detection range is set to a predetermined low pressure range, For example, it is set to 0 to 10 kg/cd.G.

However, this is time-consuming in cases such as when the evaporator's intake air temperature is high, when the compressor is controlled by an inverter and its operating frequency is low, or when the evaporation pressure is set high. However, the low-pressure refrigerant pressure may be outside the detection range of the pressure sensor, for example, 10 kg/c-.G or more, and there is a problem that accurate superheat degree control cannot be performed.

In other words, the pressure detected by the pressure sensor is lower than the actual low-pressure refrigerant pressure, and for example, the actual low-pressure refrigerant pressure is 11 kg.
/c-·G, the pressure detected by the pressure sensor is 10) cg/cd·G, and the calculated degree of superheat is larger than the actual degree of superheat. As a result, the degree of opening of the expansion valve becomes larger than normal control, resulting in wet operation, which causes the compressor to malfunction.

Therefore, it is conceivable to increase the detection range of the pressure sensor, but this poses a problem in that detection accuracy deteriorates and accurate superheat degree control cannot be performed.

The present invention has been made in view of this point, and is designed to prevent the low pressure refrigerant pressure from exceeding the detection range of the pressure detection means,
The purpose of this is to enable accurate superheat degree control.

(Means for Solving the Problems) In order to achieve the above object, the means taken by the present invention is to reduce the fan air volume or reduce the compressor capacity when the low pressure refrigerant pressure reaches a predetermined pressure within the detection range of the pressure detection means. It is designed to increase.

Specifically, as shown in FIG. 1, the measures taken by the invention according to claim (1) first include a compressor (11), a heat source side heat exchanger (12), and an expansion mechanism (14). and a user-side heat exchanger (15) are sequentially connected, and a blower fan (2b) with a variable air volume attached to the heat exchanger (15) serving as an evaporator. This assumes an air conditioner.

and a pressure detection means (4) for detecting the low-pressure refrigerant pressure on the suction side of the compressor (11) of the refrigerant circuit (1) within a preset detection range, and a heat exchanger (15) serving as the evaporator. Temperature detection means (
3) is provided. Furthermore, the pressure detection means (4
) is provided, and superheat degree control means (52) is provided for controlling the degree of superheat of the refrigerant to a predetermined value based on the low pressure signal output by the refrigerant and the temperature signal output by the temperature detection means (3).

In addition, when the pressure detected by the pressure detection means (4) reaches a predetermined pressure value near the upper limit of the detection range in response to the low pressure signal output by the pressure detection means (4), the blower fan (2b)
The configuration includes an air volume reducing means (54) for reducing the air volume.

Further, the means taken by the invention according to claim (2) is such that while the compressor (11) is configured to have a variable capacity,
) In place of the air volume reducing means (54) in the invention, when the pressure detected by the pressure detecting means (4) reaches a predetermined pressure value near the upper limit of the detection range upon receiving a low pressure signal output by the pressure detecting means (4), The compressor is configured to include capacity increasing means (55) for increasing the capacity of the compressor (11).

Further, the means taken by the invention according to claim (3) is that in the operation control device for an air conditioner according to claim (1), the compressor (11) is configured to have a variable capacity; The configuration is such that the capacity increasing means (55) in the invention of 2) is added.

(Function) With the above configuration, in the invention according to claim (1), the refrigerant circulates in the refrigerant circuit (1), for example, in the compressor.

The refrigerant discharged from (11) is condensed in the heat source side heat exchanger (12), then expanded in the expansion mechanism (14), evaporated in the user side heat exchanger (15), and then returned to the compressor (11). It turns out.

In addition, air is blown to the heat exchanger (15) serving as an evaporator, for example, the user-side heat exchanger (15), by a blower fan (2b), while the compressor (11) in the refrigerant circuit (1)
) is detected by the pressure detection means (4), and the refrigerant temperature at the outlet side of the utilization side heat exchanger (15) is detected by the temperature detection means (3).

The superheat degree control means (52) receives the low pressure signal outputted by the pressure detection means (4) and the temperature signal outputted by the temperature detection means (3), and the superheat degree control means (52) controls the superheat degree of the refrigerant. For example, the expansion mechanism (14) is controlled to adjust the refrigerant flow rate so that the degree of superheat becomes 5°C.

Further, the pressure detection means (4) has a detection range set in advance, and the air volume reduction means (54) receives the low pressure signal from the pressure detection means (4), and the air volume reduction means (54) detects the pressure. When the detected pressure of the means (4) reaches a predetermined pressure value near the upper limit within the detection range, the air volume of the blower fan (2b) is reduced. As a result, the amount of heat exchange is reduced and the pressure of the low-pressure refrigerant is lowered.

Further, in the invention according to claim (a), while the capacity of the compressor (11) is controlled, the capacity increasing means (55) receives the low pressure signal from the pressure detecting means (4).
) reaches a predetermined pressure value near the upper limit within the detection range, the capacity increasing means (55) increases the pressure of the compressor (11).
) capacity is increased to increase suction power and reduce low-pressure refrigerant pressure.

Further, in the invention according to claim (3), the pressure detection means (4
) reaches a predetermined pressure value near the upper limit within the detection range, the air volume reducing means (54)
), and the capacity increasing means (55) increases the capacity of the compressor (11) to reduce the low-pressure refrigerant pressure.

(Effect of the invention) Therefore, according to the invention according to claim (1), when the detected pressure of the pressure detecting means (4) approaches the upper limit of the detection range, the air volume of the blower fan (2b) is reduced. Therefore, the low-pressure refrigerant pressure can be maintained within the detection range of the pressure detection means (4), so that the degree of superheat can be detected accurately and the degree of superheat can be controlled with high precision. As a result, wet operation of the compressor (11) can be prevented, so failure of the compressor (11) can be prevented, and reliability of air conditioning operation can be improved.

Moreover, since the detection range of the pressure detection means (4) is not expanded, highly accurate pressure detection can be maintained, and the reliability of superheat degree control can be improved.

Further, according to the invention according to claim (2), the compressor (11
), the low-pressure refrigerant pressure can be reliably lowered and the degree of superheat can be accurately controlled.

Further, according to the invention according to claim (3), the blower fan (
Since the air volume is reduced and the capacity of the compressor (11) is increased as described in 2b), the low-pressure refrigerant pressure can be more reliably reduced, and therefore, the degree of superheat can be controlled more accurately.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

As shown in FIG. 2, (1) is a refrigerant circuit of a bare type air conditioner, which is configured by connecting one indoor unit (IB) to one outdoor unit (IA), and
It is configured as a dedicated cooling circuit that performs only cooling operation.

The refrigerant circuit (1) includes a compressor (11), an outdoor heat exchanger (12) that is a heat source side heat exchanger, and a liquid receiver (13).
An electric expansion valve (14) that is an expansion mechanism, an indoor heat exchanger (15) that is a user-side heat exchanger, and an accumulator (1
6) are sequentially connected by refrigerant piping (17) to form a closed circuit. Then, the outdoor unit (IA
) houses an outdoor heat exchanger (12) and a liquid receiver (13), while the indoor unit (IB) houses a compressor (1
1), an electric expansion valve (14), an indoor heat exchanger (15), and an accumulator (16). Furthermore, each heat exchanger (1
2) and (15) are the container exchangers (12) and (15).
) are attached with an outdoor fan (2a) and an indoor fan (2b), which are fans for blowing air.
a) and (2b) include motors (21a) and (21
b) are directly connected.

Further, the refrigerant circuit (1) is provided with a temperature sensor (3) as a temperature detection means attached to the refrigerant pipe (17) on the outlet side of the indoor heat exchanger (15), and a pressure detection means. A pressure sensor (4) is connected to the refrigerant pipe (17) on the suction side of the compressor (11). The temperature sensor (3) measures the temperature of the gas refrigerant evaporated in the indoor heat exchanger (15), that is, the compressor (1
1), and the pressure sensor (4) detects the pressure of the low-pressure refrigerant sucked into the compressor (11), and each sensor (3).

(4) is connected to the controller (5), and is configured such that each detection signal is input to the controller (5). The detection range of the pressure sensor (4) is set in advance, for example, Okg/cgf・G~10kg
It is configured to detect the low pressure refrigerant pressure within the detection range of /c-.G.

The controller (5) is connected to a motor (not shown) of the compressor (11) via an inverter (6), and also connects to each of the fans (2a).

(2b) is connected to the motors (21a), (21b) and the electric expansion valve (14). The controller (5) is equipped with an inverter control means (51) and a superheat degree control means (52), and a fan control means (52).
53) is provided.

The inverter control means (51) controls the inverter (6) by 9
The capacity of the compressor (11) is variably controlled in stages, and the indoor temperature is controlled by controlling the capacity of the compressor (11).

Further, the superheat degree control means (52) includes a pressure sensor (4).
The saturation temperature corresponding to the evaporation pressure of the refrigerant is calculated from the detected pressure of the refrigerant, the degree of superheating of the refrigerant is detected from the saturation temperature corresponding to the evaporation pressure and the refrigerant temperature of the temperature sensor (3), and the degree of superheating is set to a predetermined value (for example, 5℃).
), and the opening degree of the electric expansion valve (14) is controlled to adjust the refrigerant flow rate. Furthermore,
The fan control means (53) includes each fan (2a).

A control signal is output to the motors (21a) and (21b) of (2b), and for example, the indoor fan (2b) is set to four stages of high speed, medium speed, low speed, and ultra-low speed, and the outdoor fan (2a) is set to high speed. Each fan (2a) is controlled in two stages, low speed and low speed.
The air volume in (2b) is adjusted.

Furthermore, the controller (5) is equipped with an indoor fan (2).
b) Air volume reducing means (54) is provided. When the detected pressure of the pressure sensor (4) reaches a predetermined pressure value near the upper limit within the detection range of the pressure sensor (4), for example, 9.5 kg/cd. A control signal is output to the motor (21b) to reduce the air volume of the fan (2b) by two steps, thereby reducing the amount of heat exchange and lowering the low-pressure refrigerant pressure.

The controller (5) is configured to output an abnormal signal when the pressure detected by the pressure sensor (4) drops abnormally (for example, Okg/cd・G), and the pressure sensor (4) is configured to perform low pressure protection. Also serves as a sensor.

Next, the operation of the refrigerant circuit (1) will be explained.

First, when the compressor (11) is driven, compressed high-pressure refrigerant is discharged from the compressor (11), and the refrigerant undergoes heat exchange and condenses in the outdoor heat exchanger (12). After that, this condensed refrigerant passes through a liquid receiver (13) and an electric expansion valve (14).
), and is evaporated by exchanging heat with an indoor heat exchanger (15). This evaporated refrigerant is then transferred to an accumulator (
16) and returns to the compressor (11), where the above-described operation is repeated.

On the other hand, the capacity of the compressor (11) is adjusted by the inverter control means (51) controlling the inverter (6) based on the indoor temperature, and the capacity of each fan (2a), (2b
) is controlled by a fan control means (53),
Cold air is being blown indoors from the indoor unit (IB).

Further, in the refrigerant circuit (1), a temperature sensor (3)
detects the refrigerant temperature on the outlet side of the indoor heat exchanger (15), while the pressure sensor (4) detects the low-pressure refrigerant pressure on the suction side of the compressor (11).

Then, the superheat degree control means (52) detects the degree of superheat of the refrigerant based on the detection signals of both the sensors (3) and (4), and controls the electric motor so that the degree of superheat becomes a predetermined value (for example, 5° C.). The opening degree of the expansion valve (14) is controlled.

Next, the control operation of the air volume reducing means (54), which is a feature of the present invention, will be explained based on the control flow shown in FIG.

First, in step ST1, the detected pressure of the pressure sensor (4), that is, the low pressure refrigerant pressure, reaches a predetermined pressure value (9.5 kg/cd・G) near the upper limit of the detection range.
It is determined whether or not the predetermined pressure is 9.5k.
It waits at step STI until g/c-ΦG is reached.

Then, the temperature of the intake air of the indoor heat exchanger (15) increases, and the detected pressure of the pressure sensor (4) increases to 9.5.
kg/d・G or more, move from step STI to step ST2, and increase the air volume of the indoor fan (2b) by 2.
The speed is lowered in stages, for example, the high speed state is skipped from the medium speed state to the low speed state, and the amount of heat exchanged by the indoor heat exchanger (15) is reduced.

Thereafter, the process moves from step ST2 to step ST3, where it is determined whether a predetermined time t1 has elapsed, and, for example,
It is determined whether 10 minutes have passed since the fan air volume was reduced, and the process waits in step ST3 until the predetermined time t1 has elapsed. Then, when the predetermined time t1 has elapsed, the process moves from step ST3 to step ST4, and the detected pressure of the pressure sensor (4) is 9. 0) cg/c-・G, and if the detected pressure, that is, the low-pressure refrigerant pressure has decreased to 9.0 kg/cj・G or more, the process moves to step ST5, and the indoor fan The air volume in (2b) is increased by one step, for example, from a low speed state to a medium speed state, and the process returns to step STI. In other words, the indoor fan (2b
) is lowered by two steps, and when the low-pressure refrigerant pressure decreases, the air volume of the indoor fan (2b) is increased again.

Further, in step ST4, the pressure sensor (4)
If the detected pressure of the pressure sensor (4) has not decreased below 9.0 kg/c-.G, the determination is NO and the process returns to step STI, and the detected pressure of the pressure sensor (4) is 9.0 kg/c-.G or less. 5kg/
Determine whether it is more than c-・G, 9.5kg/e-・G
If this is the case, the above-described operation is repeated and the air volume of the indoor fan (4) is further reduced.

Therefore, when the detected pressure of the pressure sensor (4) approaches the upper limit of the detection range, the air volume of the indoor fan (2b) is reduced, so that the low-pressure refrigerant pressure falls within the detection range of the pressure sensor (4). Therefore, the degree of superheat can be detected accurately and the degree of superheat can be controlled with high precision.

As a result, wet operation of the compressor (11) can be prevented, so failure of the compressor (11) can be prevented, and reliability of air conditioning operation can be improved.

In addition, since the detection range of the pressure sensor (4) is not expanded, highly accurate pressure detection can be maintained.
The reliability of superheat degree control can be improved.

FIG. 4 is a control flow showing another embodiment, in which capacity increasing means (55) for increasing the capacity of the compressor (11) is provided in place of the air volume reducing means (54).

Therefore, to explain the structure and operation of the capacity increasing means (55), first, start and step STI
1, the detected pressure of the pressure sensor (4) is 9 and 5.
Determine whether it is more than kg / cd・G, 9.5k
Wait at step STI 1 until g/cd・G,
If the weight exceeds 9.5kg/cd・G, step 5T12
Then, the capacity of the compressor (11) is increased by two steps. Thereafter, the process moves to step STI 3, where it is determined whether or not the predetermined range t1 has elapsed.The process waits at step STI 3 until the predetermined time t1 has elapsed, and when the predetermined time t1 has elapsed, the process moves to step 5T14, where the pressure sensor It is determined whether the detected pressure in (4) has decreased to 9°Okg/c-.G or less.

Then, if the detected pressure has decreased to 9.0 kg/cl-G or less, the process moves to step STI 5, where the compressor (1
1) The capacity is decreased by one step and the process returns to step 5T11, while in step 5T14, the detected pressure is 9.0 kg.
/c-・G, the determination becomes No and the process returns to step 5TII, where the detected pressure is 9.5 kg/
If it remains above c-・G, repeat the above operation,
Furthermore, the capacity of the compressor (11) is increased.

In other words, the low pressure refrigerant pressure is 9. When it becomes 5 kg/cd·G or more, the suction force of the compressor (2) is increased to reduce the pressure of the low-pressure refrigerant.

Therefore, since the capacity of the compressor (11) is increased when the pressure detected by the pressure sensor (4) reaches a predetermined pressure value, the low-pressure refrigerant pressure can be reliably lowered, and the degree of superheat can be controlled accurately. It can be performed.

In each of the above embodiments, either the fan air volume is reduced or the compressor capacity is increased, but the air volume reducing means (54
) and capacity increasing means (55) may be provided.

That is, for example, the detected pressure of the pressure sensor (4) is 9.
5) When the temperature exceeds cg/cj-G, first turn on the indoor fan (
4) The air volume is reduced by two steps, and if the low-pressure refrigerant pressure does not decrease due to this reduction in air volume, the capacity of the compressor (11) is further increased after a predetermined period of time.

This reduces the low pressure refrigerant pressure.

Therefore, when the pressure detected by the pressure sensor (4) reaches a predetermined pressure value, the air volume of the indoor fan (2b) decreases and the compressor (1
Since the capacity increase described in 1) is performed, the low-pressure refrigerant pressure can be more reliably lowered, so that more accurate superheat degree control can be performed.

Furthermore, in each of the above embodiments, the indoor fan (2b) is controlled at 4 speeds, but may be controlled at 3 speeds.

Further, the present invention is not limited to a bare type air conditioner, but may also be a multi-type type, and may also be a refrigerant circuit that is reversible between cooling operation and heating operation.In short, the pressure sensor (4 ) to detect the low-pressure refrigerant pressure and control the degree of superheating.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention. 2 to 4 show embodiments of the present invention, FIG. 2 is a refrigerant circuit diagram, and FIG. 3 is a control flow diagram of the air volume reducing means. FIG. 4 is a control flow diagram of the capacity increasing means showing another embodiment. (1)... Refrigerant circuit (2b)... Indoor fan (3)... Temperature sensor (4)... Pressure sensor (5)... Controller (6)... Inverter (11)... ... Compressor (12) ... Outdoor heat exchanger (14) ... Electric expansion valve (15) ... Indoor heat exchanger (52) ... Superheat degree control means (54) ... Air volume Decreasing means (55): Capacity increasing means. (12) (14) (15) (52) (54) (55) ... Outdoor heat exchanger ... Electric expansion valve Indoor heat exchanger ... Superheat degree control means ... Air volume reduction means, capacity increase means. 2 others 197- Figure 3

Claims (3)

[Claims] (1) A compressor (11), a heat source side heat exchanger (12),
A refrigerant circuit (1) to which an expansion mechanism (14) and a user-side heat exchanger (15) are sequentially connected, and a heat exchanger (15) serving as an evaporator (
In an air conditioner equipped with a variable air volume blower fan (2b) attached to the refrigerant circuit (1) within a preset detection range,
pressure detection means (4) for detecting the low-pressure refrigerant pressure on the suction side of the compressor (11); and temperature detection means (3) for detecting the refrigerant temperature on the outlet side of the heat exchanger (15) serving as the evaporator. , the pressure detection means (
superheat degree control means (52) for controlling the degree of superheat of the refrigerant to a predetermined value based on the low pressure signal outputted by the temperature detection means (4) and the temperature signal outputted by the temperature detection means (3); ) receives a low pressure signal outputted by the pressure detecting means (4) and when the detected pressure of the pressure detecting means (4) reaches a predetermined pressure value near the upper limit of the detection range, an air volume reducing means (54) that reduces the air volume of the blower fan (2b); An operation control device for an air conditioner, comprising: (2) A variable capacity compressor (11), a heat source side heat exchanger (12), an expansion mechanism (14), and a user side heat exchanger (1
5) in an air conditioner equipped with a refrigerant circuit (1) sequentially connected to the refrigerant circuit (1) within a preset detection range.
pressure detection means (4) for detecting the low-pressure refrigerant pressure on the suction side of the compressor (11); and temperature detection means (3) for detecting the refrigerant temperature on the outlet side of the heat exchanger (15) serving as the evaporator. , the pressure detection means (
superheat degree control means (52) for controlling the degree of superheat of the refrigerant to a predetermined value based on the low pressure signal outputted by the temperature detection means (4) and the temperature signal outputted by the temperature detection means (3); ) capacity increasing means (55) for increasing the capacity of the compressor (11) when the detected pressure of the pressure detecting means (4) reaches a predetermined pressure value near the upper limit of the detection range in response to the low pressure signal output by the pressure detecting means (4); An operation control device for an air conditioner, comprising: (3) In the operation control device for an air conditioner according to claim (1), the compressor (11) is configured to have a variable capacity, and the pressure detection means (4) detects the pressure in response to a low pressure signal outputted from the pressure detection means (4). An air conditioner comprising: capacity increasing means (55) for increasing the capacity of the compressor (11) when the detected pressure of the means (4) reaches a predetermined pressure value near the upper limit of the detection range. Operation control device.