JPH01181044A - Air conditioning device - Google Patents

Abstract

PURPOSE:To prevent lowering of a high pressure at a low outside air temperature time to maintain sir conditioning function, by a method wherein a flow rate regulating mechanism is located in a bypass passage for controlling a heating overload, and when, during cooling operation, an outside air temperature is decreased, the flow rate regulating mechanism is opened to bypass delivery gas to the liquid pipe side. CONSTITUTION:Delivery gas is condensed by an outdoor heat exchanger 3, and after it is vaporized by an indoor heat exchanger 7, it is returned to s compressor 1 to perform cooling operation. A bypass passage 11 for controlling a heating overload to force delivery gas to bypass to the liquid pipe 9b side around the gas pipe 9a side is provided, and a second flow rate regulating mechanism 13 is located in the bypass passage 11. When a refrigerant pressure detected by a pressure state detecting means P1 is reduced to a value lower than a given value, the delivery gas is forced to bypass through the bypass passage 11 to the liquid pipe 9b side by means of an opening control means 15. Meanwhile, since first and second flow rate regulating mechanisms 4 and 13 are regulated so that a refrigerant flow rate of the outdoor heat exchanger 3 is throttled to a low value, a high pressure is prevented from lowering due to heat exchange of the outdoor heat exchanger 3 to control a refrigerant pressure so that it is brought into a specified state, and cooling operation at a low outside air temperature time is practicable.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an air conditioner equipped with a heating overload control bypass path, and particularly relates to measures for improving the operating function at low outside temperatures.

(Conventional technology) Conventionally, during cooling operation of an air conditioner, when the outside temperature drops significantly, a high pressure drop occurs, resulting in a capacity shortage due to a decrease in refrigerant flow rate, and depressurization due to flash gas when refrigerant evaporates in liquid pipes. There was a problem in that there was a risk that the mechanism would malfunction and become impossible to operate.

To prevent this problem, for example,
An air conditioner disclosed in Japanese Patent No. 152158 is known. That is, as shown in FIG. 9, the compressor (a),
In a refrigerant circuit (g) in which an outdoor heat exchanger (condenser) (b), a receiver (C), a pressure reduction mechanism (d), and an indoor heat exchanger (evaporator) (e) are connected by refrigerant piping (f), A three-way valve (h) with a flow fl adjustment function at the inlet of the receiver (c)
), the refrigerant circuit (g) is opened by the three-way valve (h).
By restricting the refrigerant flow rate from the outdoor heat exchanger (b) and storing the refrigerant in the outdoor heat exchanger (b), the refrigerant is directly bypassed from the gas pipe side to the liquid pipe side, thereby reducing the high pressure. The aim is to prevent this and perform high pressure constant control.

(Problems to be Solved by the Invention) If the above-mentioned publication is used, no pressure drop occurs in the liquid pipe, so problems such as insufficient air conditioning capacity and generation of flash gas can be effectively prevented.

On the other hand, when the above-mentioned conventional valve is applied to an air conditioner for both cooling and heating, a three-way valve (h) having such a flow rate adjustment function is used, even though it can only be used for cooling operation.
However, there is a problem in that the provision of the device increases the cost of the entire device.

In view of the above, the present invention focuses on the fact that a heating/cooling air conditioner is usually provided with a heating overload control bypass path to prevent an excessive rise in high pressure during heating operation. By using the heating overload control bypass path for constant pressure control during cooling operation, a drop in high pressure is prevented when the outside temperature is low, and the air conditioning function of the device is maintained. It is in.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention includes a compressor (1), an outdoor heat exchanger (3), a first
A refrigerant circuit (10) that connects a flow rate adjustment mechanism (4), a pressure reduction mechanism (8), and an indoor heat exchanger (7), and bypasses the discharged gas from the gas pipe (9a) to the liquid pipe (9b) side. A second flow rate adjustment mechanism (13) arranged in the bypass passage (11) and a pressure state of the refrigerant are detected. When the pressure state detection means (P1) and the refrigerant pressure detected by the pressure detection means (P1) are below a predetermined value, the refrigerant is bypassed from the bypass path (11) to the liquid pipe (9b) side, and the By restricting the refrigerant flow rate of the outdoor heat exchanger (3), the pressure state of the refrigerant is kept constant. The opening control means (15) for adjusting the opening degrees of the second flow rate adjustment mechanisms (4) and (13) is provided.

(Function) With the above configuration, in the present invention, during the cooling operation of the air conditioner, the discharge gas is condensed in the outdoor heat exchanger (3) in the main refrigerant circuit (10), and the pressure is reduced by the pressure reduction mechanism (8). Cooling operation is performed by circulating refrigerant in which the refrigerant is received, evaporated in the indoor heat exchanger (7), and returned to the compressor (1).

In that case, the discharged gas is transferred from the gas pipe (9a) side to the liquid pipe (9b).
) side bypass path for heating overload control (11
), a second flow rate adjustment mechanism (13) is provided in the bypass passage (11), and a pressure state detection means (P1
), when the refrigerant pressure detected in the bypass passage (11) decreases below a predetermined value,
While bypassing the discharged gas from to the liquid pipe (9b) side,
Since the first flow rate adjustment mechanism (4) and the second flow rate adjustment mechanism (13) are adjusted to reduce the refrigerant flow rate of the outdoor heat exchanger (3), the heat exchange of the outdoor heat exchanger (3) is This prevents a drop in the high pressure due to the refrigerant, and the pressure state of the refrigerant can be controlled to be constant. Therefore, with a simple configuration using the heating overload control bypass path (11), it is possible to perform cooling operation at low outside air temperatures.

(Example) Examples of the present invention will be described below with reference to FIGS. 1 to 8.

FIG. 1 shows the overall configuration of an air conditioner according to a first embodiment of the present invention, which is a so-called multi-type air conditioner in which two indoor units (B) and (C) are connected to one outdoor unit (A). It has the following configuration.

The outdoor unit (A) includes a compressor (1), a four-way switching valve (2) that switches as shown by the solid line in the figure during cooling operation and as a broken line in the figure during heating operation, and a condenser during cooling operation. An outdoor heat exchanger (3) that functions as an evaporator during heating operation, and a first electric expansion valve (4) that functions as a first flow rate adjustment mechanism that adjusts the refrigerant flow rate during cooling operation and reduces the pressure of the refrigerant during heating operation. A receiver (5) for storing the condensed liquid refrigerant, and an accumulator (6) for separating the liquid refrigerant from the suction gas are arranged as main equipment. In addition, the above indoor unit (
B) and (C) have the same configuration, and each has an indoor heat exchanger (7) that functions as an evaporator during cooling operation and a condenser during heating operation, and an automatic decompression mechanism that reduces the pressure of the refrigerant during cooling operation. It is equipped with an expansion valve (8). Each of the above-mentioned devices (1) to (8) is connected to refrigerant piping (9).
), the main refrigerant circuit (10) is connected to allow refrigerant flow, and has a so-called heat pump function that supplies heat obtained through heat exchange with outdoor air indoors.

As a feature of the present invention, the outdoor unit (A)
, the gas pipe (9) which is always on the discharge side of the compressor (1)
A bypass path (11) is provided from a) to the liquid pipe (9b) between the first electric expansion valve (4) and the receiver (5), and the bypass path (11) is connected to high pressure during heating operation. It has a function as a heating overload control bypass path that bypasses the refrigerant in the main refrigerant circuit (10) when the refrigerant reaches a certain value or more. The bypass path (11) includes a gas pipe (9a
) side, an auxiliary heat exchanger (12) arranged in parallel with the outdoor heat exchanger (3), and a second electric motor as a second flow rate adjustment mechanism that adjusts the flow rate of the refrigerant in the bypass path (11). An expansion valve (13) is provided.

The air conditioner also includes a control unit (15) that controls the operation of the entire device, and a gas pipe (9a) that is on the discharge side during cooling operation and on the intake side during heating operation.
A pressure sensor (P1) is installed as a pressure state detection means for detecting a condensing pressure equivalent saturation temperature Tc (hereinafter referred to as high pressure) during cooling operation, and the pressure sensor (P1) and the control unit (15) are Connected by signal line. Here, it is also possible to arrange a temperature sensor in place of the pressure sensor (P1) as the pressure state detection means and obtain the saturation pressure corresponding to the condensation temperature of the refrigerant. However, in that case, depending on the position of the temperature sensor, the temperature sensor may detect the discharge gas temperature or the temperature of the supercooled liquid refrigerant, which may cause an error in the detected value, so the pressure sensor (P1) is used. It is.

Then, the control unit (15) controls the first. The opening degrees of the second electric expansion valves (4) and (13) are controlled as follows. That is, during cooling operation, when the intake air temperature detected by the temperature sensor (TH) is below a predetermined value, as shown in the flow chart of FIG. 2, wait for the sampling time to elapse in step S1, and then step High pressure Tc detected by the pressure sensor (P1) in S2
is input, and the opening degree P of the first electric expansion valve (4) is determined in step S3.

Figure 3 shows the relationship between high pressure Tc and target opening PR, and shows the relationship between high pressure Tc and target opening PR.
- When Te1 (for example, a value of about 32℃), fully open, T
When c-Tc2 (for example, a value of about 35° C.), the opening is fully opened, and the target opening PR is set to increase linearly as the high pressure Tc increases during that time.

After determining the target opening PR as described above, in step S4, a deviation ΔP between the target opening P9 and the current opening Pc is calculated, and a control signal ΔP is output to the first electric expansion valve (4).

In addition, instead of the above-mentioned high pressure control, the evaporation pressure equivalent saturation temperature T
e (hereinafter referred to as low pressure) may be detected and low pressure constant control may be performed to maintain the low pressure constant.

In that case, as shown in the flowchart in Figure 4,
Wait for the sampling time to elapse in step S+', input the low pressure Te in step S2', and step 83
', the target opening PR is determined according to the relational expression between the evaporation temperature Te and the target opening PR shown in FIG.
Te is fully closed at Te1 (approximately -3℃), and Te is fully closed at Te2 (about -3℃).
It is set to fully open at around 0°C). However, in this case, the pressure sensor (P1) will be placed on the suction side.

Therefore, when the refrigerant pressure detected by the pressure sensor (pressure state detection means) (Pi) is below a predetermined value, the control unit (15) bypasses the refrigerant from the bypass path (11) to the liquid pipe (9b) side. On the other hand, by throttling the refrigerant flow rate of the outdoor heat exchanger (3), the pressure state of the refrigerant becomes constant. Second flow rate adjustment mechanism (4)
, (13) has a function as an opening degree control means for adjusting the opening degree.

Also, during heating operation of the air conditioner, the four-way switching valve (2) switches to the side shown by the broken line in the figure, and normally the second electric expansion valve (
13) is closed, and the discharged gas is condensed in each indoor heat exchanger (7), (7), evaporated in the outdoor heat exchanger (3), and returned to the compressor (1). . In that case,
When the indoor load in each of the indoor units (B) and (C) is small and the outdoor heat exchanger (3) is overloaded and the high pressure rises, the second
The electric expansion valve (13) gradually opens and the auxiliary heat exchanger (1
In 2), the load is adjusted by condensation, so-called heating overload control.

Therefore, in the above embodiment, although the outside air temperature decreases and the high pressure tends to decrease accordingly, the second electric expansion valve (1
3) is kept fully open and refrigerant flows in from the bypass passage (11), thereby preventing a drop in high pressure.

As a result, as shown in Figure 6 (a), the opening degree of the first electric expansion valve (4) is reduced from the fully open side to the fully closed side as shown in the figure in response to a drop in outside air temperature. Tc is a constant value T'c.

(the straight line indicated by the broken line in the figure). While the high pressure constant control is being performed as described above, the low pressure Te shows a change along the curve (indicated by the broken line in the figure) that slightly rises on the fully open side, as shown in FIG. 6 (b).
The change has converged to an appropriate range. Furthermore, Figure 6 (a),
(B) In the middle, each solid line shows the change characteristics of high pressure with respect to the outside air temperature corresponding to each window opening degree from fully open to fully closed the first electric expansion valve (4). In addition, the straight lines shown by the two dotted lines are the upper limit line Tc-Tcu (or Te57Teu) and the lower limit line Tc-Te1 (or Te-
Te1).

In that case, the amount of heat exchanged by the auxiliary heat exchanger (12) is set smaller than the amount of heat exchanged by the outdoor heat exchanger (3) for the same refrigerant flow rate. (7), The capacity balance with the (7) side will not be disrupted.

In addition, when performing low pressure constant control, as shown in Figure 7 (b), the Te-Tea straight line (the straight line shown by the broken line in the figure)
By changing the first electric expansion valve (4) from fully open to fully closed along
can be changed along the Te-Teo curve in the figure, and an excessive drop can be prevented.

In addition, in the above embodiment, an electric expansion valve (13) was provided in the bypass path (11) to provide a heating overload control function.
The existing heating overload control bypass path can also be used as is. FIG. 8 shows the configuration of an air conditioner according to the second embodiment, in which a high pressure of a predetermined value or higher is installed on the liquid pipe (9b) side of the auxiliary heat exchanger (12) of the bypass path (11). The discharge pressure control valve (15), which opens when
) A check valve (16) to prevent backflow of refrigerant from the side and a capillary tube (17) are provided in sequence, and a solenoid valve (13' ) is provided.

The other configurations are the same as those of the first embodiment.

In this example, as in the first example, when the outside temperature is low, the electromagnetic valve (13') is opened to bypass the discharged gas to the liquid pipe (9b), thereby effectively preventing an excessive drop in high pressure. can be prevented.

(Effects of the Invention) As explained above, according to the air conditioner of the present invention,
A heating overload control bypass path is provided between the discharge pipe and the liquid pipe in parallel with the outdoor heat exchanger, and a flow rate adjustment mechanism is installed in the bypass path to adjust the outside air temperature during cooling operation. When the refrigerant decreases significantly, the flow rate adjustment mechanism is opened and the discharged gas is bypassed to the liquid pipe side, so the high pressure can be controlled to a constant level by adjusting the refrigerant flow rate on the outdoor heat exchanger side. With a simple configuration that utilizes the overload control bypass path, it is possible to prevent an excessive drop in high pressure due to a drop in outside air temperature, and to enable cooling operation at low outside air temperatures.

[Brief explanation of the drawing]

1 to 7 show a first embodiment of the present invention, FIG. 1 is an overall configuration diagram thereof, FIG. 2 is a flowchart showing constant high pressure control, and FIG. 3 is an electric expansion for high pressure at that time. Figure 4 is a flowchart showing constant low pressure control; Figure 5 is a characteristic diagram of the opening of the electric expansion valve for low pressure at that time; Figure 6 (a) is the outside air during constant high pressure control. A characteristic diagram of changes in high pressure and electric expansion valve opening degree with respect to changes in temperature, Figure 6 (B) is a characteristic diagram of changes in low pressure and electric expansion valve opening degree with respect to changes in outside temperature at that time, Figure 7 (A), (B)
6A and 6B are diagrams corresponding to FIGS. 6A and 6B during constant low pressure control. FIG. 8 is a diagram showing the configuration of the second embodiment. Further, FIG. 9 is a diagram showing the configuration of a conventional device. (1)...Compressor, (3)...Outdoor heat exchanger, (4
)...first electric expansion valve (first flow rate adjustment mechanism), (7)
... Indoor heat exchanger, (8) ... Automatic expansion valve (pressure reduction mechanism), (9a) ... Gas pipe, (9b) ... Liquid pipe, (
10) Main refrigerant circuit, (11) Heating overload control loop path, (12) Auxiliary heat exchanger, (1
3)...Second electric expansion valve (second flow rate adjustment mechanism), (1
5)...Control unit (opening control means), (
P1)...Pressure sensor (pressure state detection means). Patent applicant: Daikin Industries, Ltd. ・'1
('□' Agent Patent Attorney 1) Hiroshi/Soru 2
Fig. 5 Fig. 1et,,,,) 182 i ・13 Fig. 4 Fig. 7

Claims (1)

[Claims] (1) Compressor (1), outdoor heat exchanger (3), first flow rate adjustment mechanism (4), pressure reduction mechanism (8), and indoor heat exchanger (7)
), and a heating overload control bypass path (11) for bypassing discharged gas from the gas pipe (9a) to the liquid pipe (9b) side, and the bypass A second flow rate adjustment mechanism (13) disposed in the passage (11), a pressure state detection means (P1) for detecting the pressure state of the refrigerant, and a pressure state detection means (P1) for detecting the refrigerant pressure detected by the pressure state detection means (P1). When the value falls below a predetermined value, the bypass path (
By bypassing the refrigerant from 11) to the liquid pipe (9b) side, and throttling the refrigerant flow rate of the outdoor heat exchanger (3), the first and second flow rates are adjusted so that the pressure state of the refrigerant becomes constant. An air conditioner comprising an opening degree control means (15) that adjusts the opening degrees of the mechanisms (4) and (13).