JPS62299660A - Air conditioner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention (Field of Industrial Application) This invention provides an electric expansion valve as an expansion mechanism in a refrigerant pipe connecting an indoor heat exchanger and an outdoor heat exchanger. The present invention relates to an air conditioner that has an air conditioner.

(Prior art) Conventionally, in air conditioners, medium-sized or large-sized ones, or those with large load fluctuations, it has been difficult to distinguish between a condenser and an evaporator. An expansion valve is provided as an expansion mechanism in the refrigerant pipes connected to each other, and the refrigerant flow rate is adjusted according to load fluctuations.

In recent years, there have been many devices equipped with electrically operated expansion valves, and the devices are configured with increased reliability using electrical control means. The opening degree control of such an electric expansion valve is generally performed by the superheat side fff11 method.
A specific example thereof is described in Japanese Patent Laid-Open No. 60-133269, and FIG. 9 schematically shows a refrigerant circuit of the device. As shown in the figure, this device is a separate air conditioner consisting of an outdoor unit 8 and an indoor unit B, and a compressor 31 installed in the outdoor unit A is connected to a four-way switching valve 3
2, one connection boat of this four-way switching valve 32 is connected to the outdoor heat exchanger 33, and the other connection boat is connected to the indoor heat exchanger 34 provided in the indoor unit B. , are connected by a second gas pipe 36. Then, the outdoor heat exchanger 33 and the indoor pH exchanger 34 are connected to the liquid pipe 3.
7 to form a refrigerant circulation circuit, and this liquid pipe 3
An electrically operated expansion valve 38 is interposed at 7. Note that 39 is a liquid receiver installed in the liquid pipe 37, and an accumulator 41 is installed in the suction pipe 40 that connects the suction boat of the compressor 31 and the four-way switching valve 32.

Further, in order to control the opening degree of the electric expansion valve 38 in the refrigerant circulation circuit as described above, the liquid pipe 37 and the suction pipe 40 are connected by an injection pipe 43 in which a capillary tube 42 is interposed. In addition, a thermistor 44 for measuring the evaporation pressure saturation temperature is installed in the injection pipe 43 on the side of the suction pipe 40 from the capillary tube 42, and a thermistor 45 for measuring the evaporator outlet temperature during cooling is installed in the second gas pipe 36. Each of the piping 40 is provided with a thermistor 46 for measuring the evaporator outlet temperature during heating.

In the device configured as above, the electric expansion valve 38
The opening degree control is performed as follows. For example, during cooling operation, when the refrigerant is circulated in the direction of the solid line arrow in the figure, the indoor heat exchanger 34 acts as an evaporator;
The outlet gas temperature of the refrigerant is measured by the thermistor 45 attached to the second gas pipe 36, while the temperature of the refrigerant that is bypassed from the liquid pipe 37 through the injection pipe 43 and evaporates when passing through the capillary tube 42 is measured by the temperature of the refrigerant that evaporates when passing through the injection pipe 43. The saturation temperature corresponding to the evaporation pressure is measured by a thermistor 44 attached to the evaporation pressure. be. On the other hand, during heating operation, the refrigerant circulates in the direction of the broken line arrow in the figure, and at this time, the outdoor heat exchanger 33 acts as an evaporator, so the thermistor 4 attached to the injection pipe 43
4 and the temperature measured by the thermistor 46 attached to the suction pipe 40 to determine the degree of superheat,
The opening degree of the electric expansion valve 38 is controlled in the same manner as above.

(Problems to be Solved by the Invention) As explained above, in order to control the refrigerant flow rate with the electric expansion valve according to load fluctuations, the capillary tube 4
It is necessary to provide a dedicated injection pipe 43 with an interposed interposed therebetween, and a temperature sensor such as a thermistor for temperature measurement is also required, making the device using an electric expansion valve expensive. Furthermore, in order to bypass the refrigerant through the injection pipe 43 from the liquid pipe 37,
Refrigeration capacity was also reduced.

On the other hand, as an example of using an electric expansion valve without using the superheat degree control method as described above, there is a multi-type air conditioner that connects multiple indoor units to a single outdoor unit. In this case, the opening degree corresponding to the change in the number of operating rooms is set in advance, and the refrigerant flow rate is changed in stages according to the number of operating rooms, so that it can respond to load fluctuations for each room. It's not a thing. Therefore, although it can be constructed at a low cost, the opening degree is not optimal considering load fluctuations in each room, so the refrigerating capacity is not fully demonstrated.

This invention was made in order to solve the above-mentioned conventional problems, and it is possible to control the opening of an electric expansion valve in response to load fluctuations without requiring a special temperature measurement detection circuit. The purpose of the present invention is to provide a simplified air conditioner.

(Means for Solving the Problems) Therefore, in the air conditioner of the present invention, the compressor 1, the indoor heat exchanger 6, and the outdoor heat exchanger 4 are connected so that refrigerant can be circulated, and the indoor heat exchanger 6 Liquid pipe 1 connecting the and outdoor heat exchanger 4
An air conditioner in which an electric expansion valve 13 is interposed in the air conditioner 2,
A first temperature detection means 14 for detecting the temperature on the indoor side and a second temperature detection means 15 for detecting the temperature on the outdoor side are provided. A control means 16 is provided for controlling the opening degree of the electric expansion valve 13 based on the above-mentioned.

(Function) In the air j7J machine of the present invention configured as described above, due to the difference between the temperature on the indoor side and the temperature on the outdoor side,
The h'+ number corresponding to the load in the room to be temperature-controlled is obtained, and the control means 16 determines the appropriate opening degree from the signal and controls the opening degree of the electric expansion valve 13. At this time, there is no need for a special detection circuit such as an injection pipe in the conventional superheat degree control method, and the 12!1 degree detection means 14 for detecting the indoor temperature can be, for example, a room thermometer for indoor temperature control. The indoor thermistor and the outdoor thermistor for defrost control provided in the outdoor heat exchanger 4, for example, can be used as the second temperature detection means 15 for detecting the outdoor temperature. Therefore, no special equipment is required to control the opening degree of the electrically operated expansion valve 13 in response to load fluctuations, so that it can be constructed at low cost. Further, there is no need to bypass the refrigerant as in the conventional superheat degree control system, and thereby the heating and cooling capacity can be improved.

(Example) Next, a specific example of the air conditioner of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a refrigerant circuit diagram of a device configured as a separate air conditioner. In the figure, this device is composed of an outdoor unit X and an indoor unit Y. Four-way switching valve 2 and outdoor fan 3
The indoor unit Y has an outdoor heat exchanger 4 attached with an indoor fan 5, while the indoor unit Y has an indoor heat exchanger 6 attached with an indoor fan 5.
have. The compressor 1 and the four-way switching valve 2 are connected by a discharge pipe 7 and a suction pipe 9 in which an accumulator 8 is interposed, and one connection boat of the four-way switching valve 2 is connected to the first Outdoor heat exchanger 4 via gas pipe 10
It is connected to the. Further, the other connection boat of the four-way switching valve 2 is connected to the indoor heat exchanger 6 through the second gas pipe 11, and the outdoor heat exchanger 4 is connected to the indoor heat exchanger 6 through the liquid pipe 12, thereby forming a refrigerant circulation circuit. ing. An electric expansion valve 13 is interposed in the liquid pipe I2. Further, the indoor unit Y is provided with an indoor thermistor 14 that detects the indoor temperature in order to adjust the room temperature. On the other hand, frost may adhere to the outdoor heat exchanger 4 when the indoor heating operation is performed at low outside temperatures. A thermistor 15 for measuring outside air temperature (hereinafter referred to as outside air thermistor) is attached. The indoor thermistor 14 and the outside air thermistor 15 also serve as first and second temperature detection means that are also used to control the opening degree of the electric expansion valve 13, and their respective detected temperature signals The signal is input to a control device 16 that serves as a control means for controlling the opening degree of the valve 13. The electric expansion valve 13 is of a type driven by a pulse motor, and the control device 16 outputs a pulse train corresponding to the set opening degree to the electric expansion valve 13 as a control signal. On the other hand, the indoor fan 5 attached to the indoor heat exchanger 6 has a fan tap (not shown) that can change the amount of air blown. , that is, an inverter 17 for controlling the compression capacity.
It has the following. The fan tap switching position signal and the inverter frequency signal are further input to the control device 16.

In the apparatus configured as described above, indoor cooling operation is performed by driving the compressor 1 and circulating the refrigerant in the direction of the solid line arrow in the figure by switching the four-way switching valve 2. On the other hand, the refrigerant is circulated in the direction of the dashed line arrow Heating operation is performed by circulating.

In the refrigeration cycle that performs cooling or heating by circulating refrigerant as described above, for example, during cooling operation, the sum of the compression work of the compressor 1 and the amount of heat absorbed from the outside in indoor heat exchange 2: (6) is The refrigerant is circulated in a state that is balanced with the external heat radiation amount in the outdoor heat exchanger 4.The temperature of the indoor air blown to the indoor heat exchanger 6 gradually decreases, and as a result, the temperature of the indoor air blown to the indoor heat exchanger 6 decreases. When the amount of heat exchanged with the air (absorbed heat amount) decreases, the above-mentioned heat balance is disrupted, and, for example, the circulating liquid refrigerant is completely evaporated and is returned to the compressor 1, resulting in wet operation, resulting in an ineffective It becomes impossible to maintain a proper refrigeration cycle.

Therefore, at this time, it is necessary to reduce the amount of circulating refrigerant to restore the above-mentioned heat balance. As shown in the figure, in order to operate the refrigeration cycle efficiently, the amount of heat exchanged between the amount of indoor heat exchanged with the indoor air in the indoor heat exchanger 6 and the amount of outdoor heat exchanged with the outside air in the outdoor heat exchanger 4 is required. It is necessary to adjust the refrigerant flow rate to maintain a balance.By the way, if the outside air temperature is obtained, the relationship between the refrigerant flow rate and the outdoor heat exchanger 9 can be determined, and the temperature of the air blown to the indoor heat exchanger 6 can also be determined. If the relationship between the refrigerant flow rate and the indoor heat exchange amount can be obtained, the relationship between the refrigerant flow rate and the indoor heat exchange amount can be roughly determined, and therefore, if the outside air temperature and the indoor temperature can be obtained, the appropriate heat P balance between the outdoor heat exchange amount and the indoor heat exchange amount can be determined. The refrigerant flow rate can be approximately set.Furthermore, by using the difference between the outside air temperature and the indoor temperature as a parameter that approximately corresponds to the refrigeration load, it is possible to determine the correlation between this parameter and the appropriate refrigerant flow rate.

Therefore, in the above air conditioner, the electric expansion valve 13
In order to control the opening degree, the indoor temperature and the outdoor temperature during operation are detected, and the above-mentioned opening degree control is performed based on the detected temperatures. Next, this control method will be explained.

FIG. 1 is a block diagram of the opening degree control function of the electrically operated expansion valve. The outside air temperature detection temperature signal from the outside air thermistor 15, which serves as a second temperature detection means for detecting the temperature, is input to the control device I6, which serves as a control means for controlling the opening degree of the electric expansion valve 13. Furthermore, the amount of air blown by the indoor fan 5, which has a large effect on the amount of indoor heat exchange, is set to H (strong wind) and L (
A fan tap vJ switching position signal for switching to a weak wind) and a frequency signal of an inverter frequency that affects the compression work of the compressor 1 in the heat balance are input to the control device 16. This control device 16 is composed of an input section 20, an arithmetic section 21, a condition data storage section 22, and an output section 23, and each input signal is first subjected to signal processing such as A/D conversion in the input section 20. The data is then transferred to the calculation unit 21. This calculation unit 21 calculates the difference between the indoor temperature and the outside temperature, and from the result, calculates the appropriate opening value stored in the condition data storage unit 22, which will be described later, and further calculates the difference between the fanta knob signal and the inverter frequency signal. From this, a correction coefficient is obtained from the condition data recording section 22, and the previous appropriate opening degree value is corrected.

Based on this calculation result, an output pulse train corresponding to the value is generated in the output section 23, and this is applied to the electric expansion valve 3 to set the valve opening degree.

3 to 6 schematically show diagrams used when creating the data table stored in the condition data storage section 22, and in FIG. 3, the horizontal axis shows the outside air temperature and the indoor temperature. This graph shows the absolute value of the difference ΔT, the valve opening of the electric expansion valve is plotted on the vertical axis, and the appropriate valve opening during cooling operation is determined using the outside air temperature as a parameter. FIG. 4 is a graph showing the same relationship as FIG. 3 during heating operation, and FIG. 5 shows a graph when the fan tap is H(
Outside air temperature and correction coefficient C in (strong wind) and I, (weak wind)
Figure 6 shows the relationship between outside temperature and correction coefficient 02 when the inverter frequency is changed.From each of the above graphs, for example, for heating operation The final valve opening is determined by multiplying the valve opening by the correction coefficients 01 and C2 obtained in Figs. 5 and 6, respectively.The graph of the above correction coefficient during cooling operation is also shown below. , although not shown, are similarly obtained in advance,
Then, from each graph above, the appropriate valve opening degree and correction coefficient value for each condition are written as a data table, and the condition data is recorded.
It is stored in section a 22.

Next, an explanation will be given based on the control flowchart of FIG. 7. When the air conditioner is started, a start-up process is first executed. During this period, the rotational speed of the compressor 1 is suppressed to release the refrigerant dissolved in the oil and improve the lubricity.
As shown in FIG. 2, during the start-up period T1, a signal is output that fixes the valve opening degree of the electric expansion valve 13 to the initial setting value. Then, after T1 has elapsed, from step S2, step S
3, and the valve opening degree is automatically controlled from steps S3, S4, and S5, and then returns to step S3. That is, in step S3, input signals such as indoor temperature and outside temperature are processed, and in step S4, the necessary valve opening degree is determined based on the input signal, and from this result, step S5
The valve opening degree of the electric expansion valve 13 is controlled by outputting an output pulse train. For example, during heating operation when the outside temperature is 5°C, after startup, the valve opening is maintained at the initial setting at point P shown in FIG. Since the cooling load decreases as the room temperature decreases due to subsequent cooling operation, the valve opening degree is gradually reduced from point B to point 0.

As explained above, the electric expansion valve 13 serves as an expansion mechanism.
When controlling the refrigerant flow rate according to load fluctuations using The valve opening is set to an appropriate valve opening determined in advance based on usage conditions such as tap status and inverter frequency.

Therefore, unlike conventional devices, it is possible to control the valve opening degree substantially in accordance with load fluctuations of the electric expansion valve without requiring a dedicated detection circuit for controlling the electric expansion valve.

Furthermore, in the conventional apparatus, it was necessary to partially bypass the refrigerant, but in the above embodiment, all the refrigerant circulates through the freezing cycle, so that the refrigerating capacity is also improved.

In addition, in application to the above-mentioned multi-type air conditioner, by interposing the above-mentioned electric expansion valve in each pipe leading to each indoor unit, optimal operation control corresponding to load fluctuations in each room can be achieved. This can be carried out without the need for a detection circuit, etc., and even in a configuration in which an electric expansion valve is provided in the main liquid pipe as in the conventional device, it is possible to provide information on the number of operation rooms as well as information on each operation room. By processing the average value of the indoor temperature as the indoor temperature in the above example,
Compared to conventional equipment, it is possible to operate in a manner that is more responsive to load fluctuations.

In the above embodiment, a pulse motor-driven expansion valve is used as the electric expansion valve, but the invention can also be applied to other types of expansion valves. In addition, an indoor thermistor attached to a room thermostat and an outside air thermistor attached to an outdoor heat exchanger were used as indoor and outdoor temperature detection means, but the evaporation temperature of the heat exchanger that acts as an ITo evaporator was also used. It is also possible to configure it by a thermistor that measures the condensation temperature of a heat exchanger that acts as a condenser, and a thermistor that measures the condensation temperature of a heat exchanger that acts as a condenser, and configure it based on these detected temperature thermistors.

(Effects of the Invention) As explained above, in the air conditioner of the present invention, when controlling the opening of the electric expansion valve in order to increase or decrease the flow rate of refrigerant in accordance with load fluctuations, it is possible to There is no need to measure the refrigerant temperature on the inlet and outlet sides of the heat exchanger that acts as an evaporator, and a signal approximately corresponding to the load is obtained based on the temperature difference between the indoor and outdoor sides. Since the appropriate opening degree is selected in advance in the control device, there is no need for a dedicated detection refrigerant circuit or temperature sensor to control the opening degree of the electric expansion valve as in conventional devices. In addition, there is no need to bypass the refrigerant, so that it is possible to construct an apparatus having control functions corresponding to load fluctuations at low cost, and to improve the refrigerating capacity.

[Brief explanation of the drawing]

Fig. 1 is a functional block diagram of the opening control of the electric expansion valve in the air conditioner of this invention, Fig. 2 is a refrigerant circuit diagram showing the overall configuration of a separate type air conditioner that can be used in this invention, and Fig. 3 ~Figure 6 is a graph showing the relationship between the appropriate opening degree of the electric expansion valve and usage conditions, and Figure 7 is a flowchart of operation.
8 is an explanatory diagram showing the operating state over time, and FIG. 9 is a schematic diagram of a refrigerant circuit in a conventional device. 1...Pressure 11if machine, 4...Outdoor heat exchanger, 6...
・Outdoor heat exchanger, 12...Liquid pipe, 13...Electric expansion valve, 14...Indoor thermistor (first temperature detection means)
, 15... outside air thermistor (second temperature detection means), 1
6...Control device (control means). Patent applicant: Daikin Industries, Ltd. Representative: Tadashi Nishimori 1)
17 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. S Fig. 7 Fig. i Fig. 2 Fig. 2

Claims (1)

[Claims] 1. Connect the compressor (1), indoor heat exchanger (6), and outdoor heat exchanger (4) so that refrigerant can circulate, and connect the indoor heat exchanger (
6) and an outdoor heat exchanger (4), an air conditioner in which an electric expansion valve (13) is interposed in a liquid pipe (12),
a first temperature detection means (14) for detecting the temperature on the indoor side;
A second temperature detection means (15) for detecting the temperature outside the room is provided, and the first and second temperature detection means (14) (
Based on the detected temperature difference of the electric expansion valve (13)
) is provided with a control means (16) for controlling the opening degree of the air conditioner.