JP2002081769A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exhibit the performance rise by injection to its maximum by controlling two pieces of throttle devices properly, in a refrigerating cycle which performs injection to a compressor. SOLUTION: This air conditioner detects the number of revolutions of a compressor and outside air temperature, and controls the quantity of throttling of a downstream throttle device, according to the number of revolutions of the compressor and the outside air temperature, and also if it detects liquid injection state from the temperature of a refrigerant discharged from the compressor and the temperature of the refrigerant sucked in the compressor, it opens a downstream expansion valve to prevent the performance drop caused by liquid injection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an air conditioner.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 10-185343 (document) discloses that in an injection refrigeration cycle, an intermediate pressure, which is a pressure in a gas-liquid separator, is measured by some means. Thus, the opening of the expansion valve on the downstream side among the expansion valves provided before and after the pipe of the gas-liquid separator is controlled. Further, there is an example in which the downstream expansion valve of the main refrigerant circuit is controlled so as to have an intermediate pressure or an intermediate temperature corresponding to the maximum flow rate of the intermediate gas refrigerant flowing through the injection circuit. Furthermore, in order to calculate the intermediate pressure, it is described that the outlet temperature of the gas-liquid separator is detected, and the intermediate pressure is calculated based on the detected temperature and the rotation speed of the compressor.

[0003]

In the above prior art, it is necessary to provide a temperature sensor or the like in the gas-liquid separator in order to control the downstream expansion valve. When controlling the intermediate pressure by the gas-liquid separator temperature, if the gas-liquid separator temperature can be accurately detected, the downstream expansion valve can be properly controlled. Of the temperature sensor, the accuracy and resolution of the absolute value of the temperature sensor depend on the control amount. Gas-liquid separator temperature is 1 ℃
If different, the performance will vary by a few percent, which requires an expensive temperature sensor with high accuracy. In practice, it is difficult to detect the temperature of the gas-liquid separator with such high accuracy, so that there is a problem that the downstream expansion valve cannot be properly controlled.

[0004] It is an object of the present invention to maximize the effect of performance improvement by injection by properly controlling the downstream expansion valve.

[0005] Another object of the present invention is to stop the injection under conditions where liquid injection is likely to occur, thereby preventing performance degradation due to liquid injection.

[0006]

In order to achieve the above object, an air conditioner according to a first aspect of the present invention controls a throttle amount of a downstream throttle device according to a compressor speed and an outside air temperature. By doing so, the pressure of the gas-liquid separator was properly maintained.

In order to achieve the above object, the air conditioner according to claim 2 of the present invention opens the throttle on the downstream side as the outside air temperature is lower at the same compressor rotation speed during the cooling operation. During the heating operation, when the compressor speed is the same, control is performed to open the downstream throttle as the outside air temperature increases.

In order to achieve the above object, the air conditioner according to claim 3 of the present invention controls the throttle amount of the downstream throttle device according to the compressor speed, the outside air temperature and the room temperature. Thereby, the pressure of the gas-liquid separator is appropriately maintained.

In order to achieve the above object, the air conditioner according to claim 4 of the present invention is arranged such that, at the time of the cooling operation, the compressor speed and the outside air temperature become higher as the indoor temperature becomes higher. Open the throttle, during heating operation, the same compressor speed,
At the time of the outside air temperature, the control to open the throttle on the downstream side as the room temperature is lower is performed.

According to another aspect of the present invention, there is provided an air conditioner in which the temperature of a refrigerant discharged from a compressor is lower by a predetermined amount than a predetermined value determined according to the number of revolutions of the compressor. When the refrigerant suction refrigerant temperature is higher than a predetermined value determined according to the compressor rotation speed and the outside air temperature by a predetermined amount or more, control is performed to open a predetermined amount of the downstream throttle of the two throttle devices. This prevents the performance from deteriorating due to the injection of the liquid.

According to another aspect of the present invention, there is provided an air conditioner in which the temperature of a refrigerant discharged from a compressor is lower than a predetermined value determined in accordance with the number of rotations of the compressor by a predetermined amount or more. When the compressor suction refrigerant temperature is higher than a predetermined value determined according to the outdoor heat exchanger temperature by a predetermined amount or more,
By performing control to open the downstream throttle by a predetermined amount, performance degradation due to liquid injection is prevented.

In order to achieve the above object, the air conditioner according to claim 7 of the present invention includes a two-way valve that can be opened and closed in the middle of the injection pipe, and is provided when the compressor speed is lower than a predetermined value. The two-way valve was closed.

In order to achieve the above object, the air conditioner according to claim 8 of the present invention is provided with a two-way valve that can be opened and closed in the middle of the injection pipe, and the outside air temperature is lower than a predetermined value during cooling operation. In the case where the outside air temperature is higher than a predetermined value during the heating operation, the two-way valve is closed.

In order to achieve the above object, the air conditioner according to the ninth aspect of the present invention is provided with a two-way valve that can be opened and closed in the middle of the injection pipe so that the indoor suction air temperature can be reduced to a predetermined value during the cooling operation. The two-way valve is closed when the temperature is higher or when the indoor suction air temperature is lower than a predetermined value during the heating operation.

In order to achieve the above object, the air conditioner according to claim 10 of the present invention is provided with a two-way valve that can be opened and closed in the middle of the injection pipe so that the indoor suction air temperature can be reduced to a predetermined value during cooling operation. When it is higher or when the indoor suction air humidity is higher than a predetermined value, the two-way valve is closed.

In order to achieve the above object, in the air conditioner according to claim 11 of the present invention, when the two-way valve is closed, the downstream throttle of the two throttle devices is fully opened. I did it.

In order to achieve the above object, the air conditioner according to claim 12 of the present invention opens the downstream throttle at one time when closing the two-way valve and fully opening the downstream throttle. The opening was restricted, and the downstream throttle was gradually opened fully.

In order to achieve the above object, the air conditioner according to the thirteenth aspect of the present invention is configured such that when the downstream throttle of the two throttle devices is throttled, the throttle amount to be reduced at one time is reduced. It was restricted to a predetermined value or less.

In order to achieve the above object, the air conditioner according to claim 14 of the present invention is provided with a two-way valve that can be opened and closed in the middle of the injection pipe, and the two-way valve is operated for a predetermined time from the start of operation. When the two-way valve is closed and the opening of the downstream throttle is reduced to a predetermined amount when the two-way valve is opened, the throttle amount to be reduced at one time is limited to a predetermined value or less.

According to the above means, by appropriately controlling the throttle amount of the downstream throttle device, the intermediate pressure in the gas-liquid separator is appropriately maintained, and the performance improvement effect by gas injection is maximized. Can be.

Further, by detecting the case where the performance is degraded due to the injection of the liquid refrigerant into the compressor and opening the downstream throttling device, it is possible to prevent the performance from deteriorating due to the injection of the liquid refrigerant.

Further, depending on the conditions of the outside air temperature and the number of revolutions of the compressor, the two-way valve is closed to stop the injection, thereby preventing the performance degradation due to the liquid injection.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in the drawings. FIG. 1 shows a configuration of an air conditioner according to one embodiment (first embodiment) of the present invention.

The first throttle device 4 capable of changing the throttle amount of the compressor 1, the four-way valve 2, the outdoor heat exchanger 3, the electric expansion valve and the like, the throttle amount of the gas-liquid separator 5, the electric expansion valve and the like are changed. The possible second expansion device 6 and the indoor heat exchanger 7 are sequentially connected by a refrigerant pipe to form a main refrigeration cycle. During the cooling operation, the four-way valve 2 is switched as shown by the solid line in FIG. 1, and the refrigerant flows in the direction of the solid line arrow in FIG. 1 to constitute a cooling cycle. During the cooling operation, the refrigerant compressed by the compressor is condensed in the outdoor heat exchanger 3 and radiates heat to the air, and is then decompressed by the first electric expansion valve 4 to have an intermediate pressure between the condensing pressure and the evaporating pressure, The gas-liquid separator 5 separates the refrigerant into a gas refrigerant and a liquid refrigerant. The liquid refrigerant is further decompressed by the second electric expansion valve 6, absorbs heat from air in the indoor heat exchanger 7, and
Return to On the other hand, the gas refrigerant separated by the gas-liquid separator is injected into the compressor 1 through the injection pipe 8. The injection pipe 8 is provided with a two-way valve 9 and the injection can be stopped by closing the two-way valve 9 as necessary.

During the heating operation, the four-way valve 2 is switched as shown by the broken line in FIG. 1, and the refrigerant flows in the direction of the broken arrow. During the heating operation, the refrigerant compressed by the compressor is condensed in the indoor heat exchanger 7 and radiates heat to the air.
At the intermediate pressure between the condensing pressure and the evaporating pressure, and is separated into a gas refrigerant and a liquid refrigerant in the gas-liquid separator 5. The liquid refrigerant is further reduced in pressure by the first electric expansion valve 4, evaporates in the outdoor heat exchanger 3, absorbs heat from the air, and returns to the compressor 1.
On the other hand, the gas refrigerant separated by the gas-liquid separator is injected into the compressor through the injection pipe 8.

A compressor chamber surface temperature sensor 10 is provided in the compressor chamber to detect the chamber temperature at the head of the compressor. Note that a compressor discharge refrigerant pipe temperature sensor may be provided in the refrigerant discharge pipe instead of the compressor chamber temperature sensor. In the following description, the compressor discharge refrigerant pipe temperature or the compressor head chamber surface temperature is referred to as compressor discharge refrigerant temperature. A compressor suction refrigerant pipe temperature sensor 11 is provided in the refrigerant suction pipe of the compressor to detect the temperature of the suction refrigerant. Instead of providing a sensor in the compressor suction pipe, a sensor may be attached to a liquid reservoir (accumulator) or the like provided in the compressor suction section. The outdoor unit has an outside air temperature sensor 12
And an outdoor heat exchanger sensor 13 for detecting the outside air temperature and the outdoor heat exchanger temperature.

The control of the compressor 1, the first electric expansion valve 4, the second electric expansion valve 6, etc., and the taking in of signals from sensors are performed by the control device 14. The control device 14 includes a microcomputer 15 and its peripheral devices. The rotation speed of the compressor 1 is controlled by the control device 14 and the inverter circuit 16. The rotation speed of the compressor is sensed and taken into the microcomputer 15.
The sensing of the compressor rotation speed is performed by a method such as feeding back the output current to the motor. A rotation speed sensor may be attached to the compressor.

Next, the operation of the injection cycle and the improvement of the cycle efficiency will be described with reference to FIG. FIG.
In the Mollier diagram shown in FIG. 7, the horizontal axis represents enthalpy and the vertical axis represents pressure, and represents the characteristics of the refrigeration cycle. The broken line represents the conventional cycle, and the solid line represents the gas injection cycle. In the conventional cycle, the refrigerant is compressed by the compressor from the point A to the point D ', and from the point D' to the point E, the refrigerant is condensed in the condenser and radiates heat to the outside air. From the point E to the point H ′, the refrigerant is expanded by the expansion valve, and from the point H ′ to the point A, the refrigerant evaporates in the evaporator to absorb the heat of the indoor air. In the injection cycle, the compressor starts with B
The refrigerant is compressed at the point, where the gas refrigerant separated in the gas-liquid separator is injected to reach point C and further compressed from point C to point D in the compressor. From point D to point E, the refrigerant condenses in the condenser. From point E to point F, the refrigerant expands at the first electric expansion valve, and the gas-liquid separator at point F, which is an intermediate pressure between the evaporation pressure and the condensation pressure. In, the refrigerant is separated into gas and liquid. The gas is injected into the compressor from the point F to the point C, and the liquid is reduced in pressure from the point G to the point H by the second electric expansion valve, and evaporates from the point H to the point A by the evaporator. In the case of the cooling operation, the evaporation capacity of the conventional cycle, that is, the cooling capacity, is represented by the difference between the enthalpies of the points A and H ', and the evaporation capacity of the injection cycle is represented by the difference of the enthalpies of the points A and H. Since the enthalpy at the point H is smaller than the enthalpy at the point H ', the cooling capacity increases in the injection cycle. In the case of the heating operation, assuming that the refrigerant flow rate of the condenser in the conventional cycle is G and the refrigerant flow rate injected in the gas injection cycle is G1, the refrigerant flow rate flowing through the condenser in the injection cycle is G
+ G1, and the heating capacity, which is the product of the enthalpy difference between the inlet and outlet of the condenser and the flow rate of the refrigerant, increases.

Next, the operation of the refrigeration cycle control in this embodiment will be described with reference to the flowchart of FIG. In the following description, the two electric expansion valves will be referred to as an upstream expansion valve and a downstream expansion valve, respectively. Of the two electric expansion valves, the first electric expansion valve 4 in FIG. 1 is an upstream expansion valve, the second electric expansion valve 6 is a downstream expansion valve during the cooling operation, and the electric expansion valve during the heating operation. 6 is an upstream expansion valve, and the electric expansion valve 4 is a downstream expansion valve. The numerical value of the expansion valve opening is defined as a direction in which the larger the numerical value, the more the expansion valve opens.

FIG. 3 shows a flow in the case of cooling, but the same applies to the case of heating. The case where the calculation formula differs between heating and cooling will be described in the text for each case.

In step 101 of FIG. 3, initialization processing such as initialization of variables is performed.
Start the initial operation timer. In the initial operation, the two-way valve 9 in FIG. 1 is closed and the operation is performed for a predetermined time without performing gas injection, and this timer gives the time. In step 103, the initial values of the upstream and downstream expansion valve openings are set. The downstream expansion valve is normally fully opened, but may be set to an opening corresponding to the compressor speed. Next Step 1
At 04, a timer for giving a sampling time is started. This timer provides an interval (sampling time) for sensing the temperature of the refrigerant discharged from the compressor and controlling two expansion valves. In step 105, the compressor discharge refrigerant temperature Td, the compressor suction refrigerant temperature Ts, the outside air temperature T
o, Read the outdoor heat exchanger temperature Teo and the compressor speed N.
In step 106, the opening change amount of the upstream expansion valve is calculated. The upstream expansion valve is controlled in accordance with the temperature of the refrigerant discharged from the compressor and the amount of change thereof. Next, in step 107, it is determined whether or not the initial operation time has elapsed. If the initial operation time has not been reached, the two-way valve is kept closed in step 108. It is kept fully open. After the elapse of the initial operation time, it is determined in step 110 whether or not to perform gas injection based on the compressor speed and the outside air temperature. In the cooling operation, gas injection is not performed when the compressor speed is equal to or lower than a predetermined value or when the outside air temperature is equal to or lower than a predetermined value, that is, when one of the following equations (1) and (2) is satisfied.

N ≦ Nc0 (1) To ≦ Toc0 (2) where N is the number of rotations of the compressor, To is the outside air temperature, and Nc0 and Toc0 are constants. That is, when the compressor rotation speed is low, it is determined that the operation is low-capacity operation, and when the outside air temperature is low, it is considered that the operation is low because the indoor temperature is not so high.

In the heating operation, the gas injection is not performed when the compressor speed is equal to or lower than a predetermined value or when the outside air temperature is equal to or higher than a predetermined value, that is, when either of the equations (3) and (4) is satisfied. .

N ≦ Nh0 (3) To ≧ Toh0 (4) where Nh0 and Toh0 are constants. As in the case of cooling, when the compressor rotation speed is low, it is determined that the operation is low-capacity operation, and when the outside air temperature is high, it is considered that the operation is low because the room temperature is not so low.

The reason why gas injection is not performed under these conditions is that the evaporation pressure is high under these conditions,
This is because even if gas injection is performed, the injection amount is extremely small and the effect is not so large, and furthermore, liquid injection is liable to occur, and conversely, the performance may be deteriorated.

When the gas injection is not performed, the two-way valve is closed in step 108, and the downstream expansion valve is fully opened in step 109. When the downstream valve is fully opened from the throttled state, it may not be fully opened at once, but may be gradually opened to the full opening. Alternatively, the two-way valve may be closed when the downstream expansion valve is gradually opened and fully opened. By gradually opening the downstream expansion valve, it is possible to avoid a rapid decrease in the refrigerant discharge refrigerant temperature or the compressor suction superheat.

In step 110, the equations (1), (2) or
If the conditions (3) and (4) are not satisfied, step 111
Open the two-way valve to perform gas injection. If the two-way valve is already open, keep the open state.

Next, at step 112, the target value Tds of the compressor discharge refrigerant temperature Td is calculated by the equation (5).

Tds = a1 · N + b1 · To + c1 (5) Here, N is the compressor speed (a value sensed), To is the outside air temperature, and a1, b1, and c1 are constants.

In the next step 113, the compressor suction temperature Ts
Is calculated by the equation (6).

Tss = a2 · N + b2 · To + c2 (6) where a2, b2 and c2 are constants.

The reference value Tss of the compressor suction temperature may be obtained by the equation (7) using the outdoor heat exchanger temperature Teo in consideration of the case where frost forms on the outdoor heat exchanger in the case of heating. .

Tss = a2 ・ N + b2TTeo + c2 (7) In the next step 114, it is determined whether or not the refrigerant to be injected is mixed with liquid. Judgment is an expression
When both (8) and (9) are satisfied at the same time, it is determined that liquid injection has occurred.

Td ≦ Tds−α (8) Ts ≧ Tss + β (9) where Tds is the target value of the compressor discharge refrigerant temperature calculated in step 112, and Tss is the compressor suction temperature calculated in step 113. The reference values of the refrigerant temperature, α and β, are constants. The reason that liquid injection can be determined under such conditions is that when liquid injection occurs, the refrigerant cools the compression chamber refrigerant by the liquid and lowers the refrigerant discharge refrigerant temperature, and the refrigerant accumulates in the gas-liquid separator, resulting in a cycle. This is because the refrigerant in the compressor becomes almost insufficiency, and the refrigerant suction refrigerant temperature rises.

If the condition is satisfied in step 114, it is considered that liquid injection has occurred, and in step 115, the correction value SP (n) of the downstream-side expansion valve opening is determined by a predetermined amount dP2a as shown in equation (10). Add.

SP (n) = SP (n−1) + dP2a (10) The value of dP2a is positive (the value in the direction in which the expansion valve opens). Here, n is a sampling number. By opening the downstream valve, the refrigerant pressure in the gas-liquid separator decreases, so that the liquid injection can be terminated. SP (n−1) is the previous value of the opening correction value, and the description will be made on the assumption that liquid injection is determined when this value is 0. If it is determined that the injection is the liquid injection, the current correction amount is set to dp2a. When it is determined that the liquid injection is still continued next time, the correction amount becomes 2dp2a, and the correction is repeated until the liquid injection stops. That is, integration control of the correction amount is performed. Note that there is a method in which the injection is stopped by closing the two-way valve instead of opening the downstream valve.

In the next step 116, the reference value P2s of the downstream expansion valve opening is calculated by the equation (11).

P2s = a3 · N + b3 · To + c3 +
SP (n) (11) Here, N is the number of rotations of the compressor, To is the outside air temperature, SP (n) is the correction amount of the downstream-side expansion valve opening, and a3, b3, and c3 are constants. In the cooling operation, a3 is positive and b3 is negative, and in the heating operation, a3 is positive and b3 is also positive. Therefore, in the cooling operation, the downstream expansion valve is throttled as the outside air temperature increases, and in the heating operation, the downstream expansion valve is opened as the outside air temperature increases.

The reason will be described. The reason why the opening degree is adjusted in proportion to the compressor rotation speed is that if the rotation speed is high, the amount of circulating refrigerant increases, the liquid refrigerant in the gas-liquid separator increases, and there is a high possibility of liquid injection. This is to prevent liquid injection by opening the valve.

The reason why the opening of the downstream expansion valve is adjusted in accordance with the outside air temperature is that, during cooling, the outdoor heat exchanger acts as a condenser, and if the outside air temperature rises rapidly,
As the temperature of the condenser increases and the amount of condensate decreases, the proportion of the gas refrigerant increases. For this reason, the pressure of the condenser increases.
A pressure increase in the condenser results in a pressure increase throughout the cycle. At this time, the intermediate pressure in the compressor also increases, so if the intermediate pressure in the gas-liquid separator is not increased, the amount of gas injection will decrease and the COP will decrease. Is performed. On the other hand, during heating, the outdoor unit functions as an evaporator. When the outside air temperature increases, the evaporator temperature also increases, and the amount of evaporation increases. For this reason, the pressure in the evaporator increases, and the suction pressure of the compressor increases. An increase in the suction pressure means an increase in the density of the gas refrigerant sucked into the compressor.Therefore, the amount of the refrigerant compressed by the compressor increases, and as a result, the refrigerant circulation amount increases. Means At this time, since the pressure increase in the gas-liquid separator is larger than the pressure increase in the injection port of the compressor, the liquid volume in the gas-liquid separator may increase and the liquid may return. For this reason, the downstream expansion valve is opened to prevent the liquid from returning.

In the next step 117, the downstream expansion valve opening degree P2 (n-1) at the previous sampling time is set in order to limit the throttle amount of the downstream expansion valve at one time to a predetermined value dP2max or less. The difference from the downstream expansion valve opening P2s calculated in 116 is obtained, and if it is equal to or less than dP2max, in step 118, the downstream expansion valve opening P2 (n) is set to P2s. Otherwise, in step 119, the downstream-side expansion valve opening P2 (n) is set to a value obtained by subtracting dP2max from the previous opening. The reason for limiting the amount of squeezing at one time is
This is because if the downstream expansion valve is suddenly throttled, the intermediate pressure rises and liquid injection is likely to occur, and the compressor discharge temperature rises rapidly and control stability is impaired.

In the next step 120, the amount of change in the degree of opening of the downstream expansion valve is determined. In step 121, a pulse is output to the expansion valve coil to operate the upstream and downstream expansion valves. In step 122, the sampling time is counted. When the sampling time has been reached, the process returns to step 104 and the following series of operations is repeated.

According to the present embodiment, the intermediate pressure can be appropriately maintained by controlling the degree of opening of the downstream expansion valve according to the compressor speed and the outside air temperature, so that the performance improvement by gas injection is large. Further, since the liquid injection is determined based on the compressor discharge refrigerant temperature and the compressor suction refrigerant temperature and the downstream expansion valve opening is adjusted, the performance degradation due to the liquid injection can be prevented. Further, according to the present embodiment, according to the compressor rotation speed and the outside air temperature,
Since the control for closing the two-way valve to stop the injection is performed, the performance degradation due to the liquid injection hardly occurs.

Another Embodiment of the Present Invention (Second Embodiment)
FIG. 4 shows the configuration of the air conditioner of FIG. The configuration of the refrigeration cycle in this embodiment is the same as that of the first embodiment,
The indoor unit is provided with an indoor intake air temperature sensor and an indoor heat exchanger sensor. The operation of the refrigeration cycle control in this embodiment will be described with reference to the flowchart of FIG.
Since the basic flow of the control operation is the same as that of the first embodiment, the description of the present embodiment will be made only for the portions different from the first embodiment.

In step 205, the refrigerant discharge refrigerant temperature
The indoor suction air temperature Ti and the indoor heat exchanger temperature Tei are read in addition to Td, the compressor suction refrigerant temperature Ts, the outside air temperature To, and the outdoor heat exchanger temperature Teo. When the indoor intake air temperature and the indoor heat exchanger temperature cannot be directly taken into the control unit of the outdoor unit, the data may be taken into the control unit provided in the indoor unit and sent to the control unit of the outdoor unit. .

In the determination as to whether or not to perform the gas injection in step 210, in the cooling operation, the equation (12) is used.
If any of (14) is satisfied, gas injection is not performed.

N ≦ Nc0 (12) To ≦ Toc0 (13) Ti ≧ Tic0 (14) where N is the compressor rotation speed, To is the outside air temperature, Ti is the indoor suction air temperature, Nc0, Toc0, and Tic0 are constants. It is. Further, an indoor suction air humidity sensor may be provided to close the two-way valve even when the indoor suction air humidity is equal to or higher than a predetermined value.

In the heating operation, if any of the equations (15) to (17) holds, the gas injection is not performed.

N ≦ Nh0 (15) To ≧ Toh0 (16) Ti ≦ Tih0 (17) Here, Nh0, Toh0, and Tih0 are constants.

In step 213, in the case of the cooling operation, the reference value Tss of the compressor suction refrigerant temperature Ts is calculated by the equation (18).

Tss = a2 · N + b2 · Tei + c2 (18) where a2, b2 and c2 are constants. In the present embodiment, the temperature of the indoor heat exchanger is used to calculate the reference value of the compressor suction refrigerant temperature. In the case of the heating operation, similarly to the first embodiment, the compressor suction temperature reference value is obtained by the above-described equation (6) or (7).

In step 216, the reference value of the downstream-side expansion valve opening is obtained by equation (19).

P2s = a3 · N + b3 · To + c3 · Ti + d3 + SP (n) (19) Here, the indoor intake air temperature is also used for calculating the downstream expansion valve opening.

According to the present embodiment, the intermediate pressure can be more appropriately maintained by controlling the opening degree of the downstream expansion valve in accordance with not only the rotational speed of the compressor and the temperature of the outside air but also the temperature of the intake air in the room. Therefore, the effect of performance improvement by gas injection is maximized. Further, according to the present embodiment, since the control for closing the two-way valve and stopping the injection is performed based on the indoor suction air temperature in addition to the compressor rotation speed and the outside air temperature, the performance is not easily reduced by the liquid injection. ing.

[0065]

As described above in detail, according to the present invention, the effect of improving the performance by gas injection can be maximized. According to the present invention,
By stopping the injection by closing the two-way valve depending on the conditions of the outside air temperature and the number of rotations of the compressor, it is possible to prevent performance degradation due to liquid injection.

[Brief description of the drawings]

FIG. 1 is a configuration of an air conditioner according to an embodiment of the present invention.

FIG. 2 is a Mollier diagram showing an operation of a gas injection cycle.

FIG. 3 is a flowchart of expansion valve control.

FIG. 4 is a configuration of an air conditioner according to a second embodiment of the present invention.

FIG. 5 is a flowchart of an expansion valve control of the air conditioner according to the second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... 4-way valve, 3 ... Outdoor heat exchanger, 4 ... First
Squeezing device, 5 ... gas-liquid separator, 6 ... second squeezing device, 7
... indoor heat exchanger, 8 ... injection piping, 10 ... compressor chamber surface temperature sensor, 11 ... compressor suction refrigerant piping temperature sensor, 12 ... outside air temperature sensor, 14 ... control device.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Hiroshi Shinozaki, 800, Tomita, Ohira-machi, Ohira-machi, Shimotsuga-gun, Tochigi Prefecture Inside the Cooling Division, Hitachi, Ltd. 3L060 AA03 CC02 CC03 CC04 CC19 DD02 EE02 EE09 EE45

Claims (16)

[Claims] 1. A compressor, an outdoor heat exchanger, a first throttle device having an adjustable opening, a gas-liquid separator, a second throttle device having an adjustable opening, and an indoor device. A means for detecting a compressor rotation speed in an air conditioner having an injection pipe for supplying a refrigerant from the gas-liquid separator to the compressor by sequentially connecting a heat exchanger and forming a refrigeration cycle; An air conditioner comprising: a means for detecting a temperature; and a means for controlling a throttle amount of a downstream throttle device of the two throttle devices according to the detected compressor rotation speed and outside air temperature. 2. The cooling device according to claim 1, wherein at the time of the cooling operation, at the same compressor rotation speed, as the outside air temperature is lower, the downstream throttle of the two expansion devices is opened, and at the time of the heating operation, the same compressor is opened. An air conditioner having a function of performing control to open a throttle on the downstream side of the two throttle devices as the outside air temperature increases at a rotation speed. 3. A compressor, an outdoor heat exchanger, a first throttle device whose opening can be adjusted, a gas-liquid separator, a second throttle device whose opening can be adjusted, and an indoor device. A heat exchanger is sequentially connected to form a refrigeration cycle, and in an air conditioner having an injection pipe for supplying a refrigerant from the gas-liquid separator to the compressor, a means for detecting a compressor speed, Means for detecting the intake air temperature, means for detecting the outside air temperature, and the throttle amount of the downstream throttle device of the two throttle devices in accordance with the detected compressor speed, room temperature and outside air temperature. An air conditioner comprising: a control unit. 4. The cooling device according to claim 3, wherein during cooling operation, at the same compressor rotation speed and the same outside air temperature, as the room temperature increases, the downstream throttle of the two throttle devices is opened, and the same compressor is opened. When the rotation speed and the same room temperature are the same, the lower the outside air temperature, the lower the downstream throttle of the two expansion devices is controlled to open, and during the heating operation, the same compressor rotation speed and the same outside air temperature, As the indoor temperature is lower, the downstream throttle of the two throttle devices is opened, and when the compressor speed is the same and the room temperature is the same, the downstream throttle of the two throttle devices is higher as the outside air temperature is higher. The air conditioner that controls the opening. 5. A compressor, an outdoor heat exchanger, a first throttle device whose opening can be adjusted, a gas-liquid separator, a second throttle device whose opening can be adjusted, and an indoor device. A means for detecting a compressor rotation speed in an air conditioner having an injection pipe for supplying a refrigerant from the gas-liquid separator to the compressor by sequentially connecting a heat exchanger and forming a refrigeration cycle; A means for detecting a compressor discharge refrigerant temperature, a means for detecting a compressor suction refrigerant temperature, and a means for detecting an outside air temperature,
The compressor discharge refrigerant temperature is at least a predetermined amount lower than a predetermined value determined according to both the compressor rotation speed and the outside air temperature or only the compressor rotation speed, and the compressor suction refrigerant temperature is lower than the compressor rotation speed and the outside air temperature. An air conditioner that performs control to open a downstream throttle of the two throttle devices by a predetermined amount when the speed is higher by a predetermined amount than a predetermined value determined in accordance with both or only the compressor speed. 6. A compressor, an outdoor heat exchanger, a first throttle device whose opening can be adjusted, a gas-liquid separator, a second throttle device whose opening can be adjusted, and an indoor device. A means for detecting a compressor rotation speed in an air conditioner having an injection pipe for supplying a refrigerant from the gas-liquid separator to the compressor by sequentially connecting a heat exchanger and forming a refrigeration cycle; A means for detecting a compressor discharge refrigerant temperature, a means for detecting a compressor suction refrigerant temperature, and a means for detecting an outdoor heat exchanger temperature, wherein the compressor discharge refrigerant temperature is both a compressor rotation speed and an outside air temperature or The compressor suction refrigerant temperature is determined according to both the outdoor heat exchanger temperature and the compressor rotation speed or only the outdoor heat exchanger temperature, which is lower than a predetermined value determined only by the compressor rotation speed by a predetermined amount or more. If the value is higher than the predetermined value by a predetermined amount or more, An air conditioning apparatus performs a predetermined amount open controls the aperture of the downstream side of the device. 7. A compressor, an outdoor heat exchanger, a first throttle device whose opening can be adjusted, a gas-liquid separator, a second throttle device whose opening can be adjusted, and an indoor device. A means for detecting a compressor rotation speed in an air conditioner comprising an injection pipe for supplying a refrigerant from the gas-liquid separator to the compressor by sequentially connecting a heat exchanger and forming a refrigeration cycle; An air conditioner comprising a two-way valve that can be opened and closed in the middle of a pipe, wherein the two-way valve is closed when the compressor rotation speed is lower than a predetermined value. 8. A compressor, an outdoor heat exchanger, a first throttle device whose opening can be adjusted, a gas-liquid separator, a second throttle device whose opening can be adjusted, and an indoor device. A heat exchanger is sequentially connected to form a refrigeration cycle, and in an air conditioner having an injection pipe for supplying a refrigerant from the gas-liquid separator to the compressor, a means for detecting an outside air temperature; An air conditioner including a two-way valve that can be opened and closed on the way, wherein the two-way valve is closed when the outside air temperature is lower than a predetermined value during a cooling operation or when the outside air temperature is higher than a predetermined value during a heating operation. 9. A compressor, an outdoor heat exchanger, a first throttle device whose opening can be adjusted, a gas-liquid separator, a second throttle device whose opening can be adjusted, and an indoor device. A means for detecting the indoor suction air temperature in an air conditioner having an injection pipe for supplying a refrigerant from the gas-liquid separator to the compressor by sequentially connecting a heat exchanger and forming a refrigeration cycle; A two-way valve that can be opened and closed in the middle of the pipe is provided, and when the indoor suction air temperature is higher than a predetermined value during the cooling operation or when the indoor suction air temperature is lower than the predetermined value during the heating operation, the two-way valve is closed. Air conditioner. 10. A compressor, an outdoor heat exchanger, a first throttle device whose opening can be adjusted, a gas-liquid separator, a second throttle device whose opening can be adjusted, and an indoor device. A means for detecting the indoor suction air temperature in an air conditioner comprising an injection pipe for supplying a refrigerant from the gas-liquid separator to the compressor by sequentially connecting a heat exchanger and a refrigeration cycle; A means for detecting the suction air humidity and a two-way valve that can be opened and closed in the middle of the injection pipe, and when the indoor suction air temperature is higher than a predetermined value during cooling operation or when the indoor suction air humidity is higher than a predetermined value, An air conditioner with a two-way valve closed. 11. The air conditioner according to claim 7, wherein when the two-way valve is closed, a downstream throttle of the two throttle devices is fully opened. 12. The method according to claim 11, wherein when the two-way valve is closed to fully open the downstream throttle, a limit is provided on the opening degree at which the downstream throttle is opened at one time, and the downstream throttle is gradually opened fully. Air conditioner. 13. An air conditioner according to claim 1, wherein, when the downstream throttle of the two throttle devices is throttled, the throttle amount reduced at one time is limited to a predetermined value or less. . 14. A compressor, an outdoor heat exchanger, a first throttle device whose opening can be adjusted, a gas-liquid separator, a second throttle device whose opening can be adjusted, and an indoor device. A heat exchanger is sequentially connected to form a refrigeration cycle, and in an air conditioner having an injection pipe for supplying a refrigerant from the gas-liquid separator to the compressor, a two-way valve that can be opened and closed in the middle of the injection pipe. When the two-way valve is closed for a predetermined time from the start of operation, and when the two-way valve is opened, when the degree of opening of the downstream throttle is reduced to a predetermined amount, the amount of throttle that is reduced at one time is restricted to a predetermined value or less. Harmony equipment. 15. An air conditioner according to claim 5, wherein the temperature of the chamber surface at the head of the compressor is detected instead of the temperature of the refrigerant discharged from the compressor. 16. An air conditioner according to claim 5, wherein a surface temperature of an accumulator provided in a compressor suction part is detected instead of a compressor suction refrigerant temperature.