JP2009092337A - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent accumulation of oil for a compressor in an indoor heat exchanger due to liquefaction and accumulation of a refrigerant in the indoor heat exchanger in starting of heating operation, and to prevent shortage of the oil for the compressor in an air conditioner having a throttling mechanism for diversion in the indoor heat exchanger. <P>SOLUTION: In a refrigerating cycle having throttling mechanisms 7, 8 for diversion in a rotational frequency variable compressor 1 and the indoor heat exchanger 3, a center part temperature sensor 9 is arranged in the neighborhood of a center part of the indoor heat exchanger 3, an outlet part temperature sensor 11 is arranged in an outlet part 10, a rotational frequency of an indoor fan 12 is determined such that a temperature difference between the both is provided within a predetermined temperature range in starting of heating operation, and a merging unit 7 of the indoor heat exchanger 3 is arranged such that it is positioned lower than a refrigerant inlet piping 7a of a lowermost part of an inlet part in heating of the indoor heat exchanger 3. By this, accumulation of liquefied refrigerant in the indoor heat exchanger is eliminated, and shortage of the oil for the compressor is prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique for preventing an air conditioner having a diversion throttle mechanism in an indoor heat exchanger from causing excessive refrigerant to remain in the indoor heat exchanger at the start of heating operation and damaging the compressor. .

  Conventionally, this type of general air conditioner ensures reliability by lowering the compressor operating frequency when the compressor is exposed to a low temperature and the refrigerant is stagnant in the oil in the compressor. Control is known.

The compressor 101 is driven by an inverter, the compressor pressure detector 113 detects the pressure in the compressor, the compressor temperature detector 115 detects the temperature in the compressor, and the temperature of the outdoor heat exchanger 103. An outdoor heat exchanger temperature detector 112 to detect, an indoor heat exchanger temperature detector 114 to detect the temperature of the indoor heat exchanger 107, and a compressor internal pressure based on the pressure in the compressor detected by the compressor pressure detector 113. , A means for determining the stagnation of the refrigerant into the compressor 101 based on the temperature in the compressor, the saturation temperature in the compressor, and the temperature of the heat exchanger on the condensation side, and at the start of operation, In the case where it is determined that there is a stagnation of the refrigerant, there is provided means for reducing the frequency increase rate of the inverter. As a result, by detecting the temperature and pressure in the compressor at the time of start-up and the temperature of the outdoor heat exchanger, it is possible to accurately grasp the stagnation state of the liquid refrigerant in the compressor. Even with incompatible refrigeration oils and refrigerants, sudden fluctuations in the load on the bearings can be suppressed, and if it is determined that they can be avoided from the stagnation situation, normal control is immediately performed. Since it is possible to shift, damage to the compressor bearing can be prevented without impairing comfort due to changes in room temperature or the like (see, for example, Patent Document 1).
JP-A-10-227533

  However, in the above-described conventional configuration, when the indoor heat exchanger has a diversion throttle mechanism, refrigerant stagnation occurs in the indoor heat exchanger at the start of heating operation, and compressor oil is transferred to the indoor heat exchanger. It has a problem that it may accumulate and cause a shortage of oil inside the compressor.

  An object of the present invention is to solve the above-described conventional problems, and to provide an air conditioner having a control method for preventing liquefied refrigerant from staying in an indoor heat exchanger.

  In order to solve the above-described conventional problems, an air conditioner according to the present invention includes an indoor heat exchanger, an indoor fan, an indoor fan motor capable of changing the number of rotations, and an indoor temperature sensor that detects an indoor suction temperature. A central temperature sensor for detecting the temperature in the vicinity of the central portion of the indoor heat exchanger, an outlet temperature sensor for detecting an outlet temperature during heating operation of the indoor heat exchanger, and the indoor heat exchanger A refrigerant diversion throttle mechanism and a merger, and the merger is arranged to be positioned below the lowermost refrigerant inlet pipe of the heating inlet of the indoor heat exchanger at the start of heating operation The rotation speed of the indoor fan motor is stopped or rotated at a low speed so that the difference between the detected temperature of the central temperature sensor and the detected temperature of the outlet temperature sensor is within a predetermined temperature. As a result, the refrigerant does not liquefy and stay in the indoor heat exchanger, and the oil shortage of the compressor can be prevented.

  The air conditioner of the present invention can prevent oil shortage in the compressor at the start of heating operation.

  In a first aspect of the present invention, in a refrigeration cycle in which a compressor having a variable number of revolutions and an indoor heat exchanger have a diversion throttle mechanism, a central temperature sensor near the central portion of the indoor heat exchanger and an outlet temperature sensor at the outlet And the number of rotations of the indoor fan is determined so that the temperature difference between the two is within a predetermined temperature range at the start of heating operation, and the merger of the indoor heat exchanger is set during heating of the indoor heat exchanger By arranging so as to be located below the lowermost refrigerant inlet pipe of the inlet portion, the liquefied refrigerant is not retained in the indoor heat exchanger, and the oil shortage of the compressor can be prevented.

  According to a second aspect of the present invention, in a refrigeration cycle having a compressor having a variable number of rotations and an indoor heat exchanger having a shunting mechanism for diversion, the difference between the temperature at the center of the indoor heat exchanger and the outlet temperature is determined within a predetermined temperature range when heating operation starts The number of rotations of the indoor fan is determined so as to be within, and the junction of the indoor heat exchanger is disposed below the refrigerant inlet pipe at the bottom of the heating inlet of the indoor heat exchanger. As a result, the liquefied refrigerant is not retained in the indoor heat exchanger, and the shortage of oil in the compressor can be avoided.

  In particular, the third aspect of the invention suppresses the liquefied refrigerant from staying in the indoor heat exchanger of the first or second aspect of the invention by suppressing the air volume by closing the indoor outlet with the left / right or up / down air direction change blades in the room, It is possible to prevent oil from running out of the compressor.

  In the fourth aspect of the invention, in particular, the stagnation of the liquefied refrigerant in the indoor heat exchanger of the first or second aspect of the invention is prevented, and the compressor is prevented from running out of oil by closing the indoor outlet with a panel covering the indoor outlet. Can be realized.

  In particular, the fifth aspect of the invention suppresses the liquefied refrigerant from staying in the indoor heat exchanger according to the first or second aspect of the invention by suppressing the air volume by closing the indoor suction port with a panel that covers the indoor suction port. It is possible to prevent the machine from running out of oil.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a refrigeration cycle diagram of the air conditioner according to the first embodiment of the present invention, and FIG. 2 is a control flowchart of the air conditioner. In the embodiment of the present invention, a floor-mounted inverter air conditioner will be described as an example, but the same applies to a wall-mounted type and ceiling built-in type air conditioner when the indoor heat exchanger has a diversion throttle mechanism.

FIG. 1 shows a refrigeration cycle diagram of a basic heat pump of an air conditioner composed of an indoor unit A and an outdoor unit B. The compressor 1 compresses the refrigerant, the four-way valve 2 changes the refrigerant flow, An indoor heat exchanger 3 that is a condenser in which high-pressure and high-temperature refrigerant is condensed during heating, a throttling device 4 that decompresses the condensed refrigerant, and an evaporator 5 that evaporates the decompressed refrigerant are connected in order by piping. In the first embodiment, the heating inlet of the indoor heat exchanger 3 is divided into four paths, and the outlet 7 is connected to a capillary tube 8 that is a throttle mechanism for adjusting the refrigerant flow rate in each path. It merges at the merger 9. Thereafter, the refrigerant is again introduced into the supercooling section 3a of the indoor heat exchanger 3 to promote the supercooling of the refrigerant. Moreover, the central part temperature sensor 10 is provided in piping near the center part of the indoor heat exchanger 3, and the outlet part temperature sensor 11 is provided after the merger 9 as outlet part temperature. further,
The indoor unit A includes an indoor fan 12, an indoor fan motor 13, and an indoor temperature sensor 14, and the outdoor unit B includes an outdoor fan 15 and an outdoor fan motor 16.

  The vicinity of the central portion of the indoor heat exchanger 3 may be around one-third of the middle portion of the flow path of one path that flows through the interior of the indoor heat exchanger 3. . Further, the outlet temperature sensor 11 may be provided after the supercooling unit 3a, and the supercooling unit 3a is not always necessary.

  In FIG. 2, when the air conditioner receives a heating operation instruction from a remote controller (not shown) (step 1), first, the indoor fan 12 is stopped (step 2) and the heating operation is started to rotate the indoor fan 12. The determination as to whether or not to be performed is performed based on the central temperature TC of the indoor heat exchanger 3 (step 3). This is performed so that the indoor heat exchanger 3 is not sufficiently heated at the start of the heating operation, and cold air is not blown out. Although details of the control are not described in the embodiment of the present invention, the indoor fan 12 is set at a rotation speed set in advance according to the temperature detected by the center temperature sensor 10 attached to the center of the indoor heat exchanger 3. It is something to drive. Here, the indoor fan 12 is not rotated until the temperature detected by the central temperature sensor 10 attached in the vicinity of the central portion of the indoor heat exchanger 3 reaches 20 ° C. or higher.

If the central temperature TC is 20 ° C. or higher, the indoor fan 12 is operated at a predetermined low speed (X ₀ ) (step 4). In the first embodiment, the initial rotational speed (X ₀ ) is the lowest rotational speed allowed for the indoor fan motor 13, and the initial rotational speed is 100 r / min. After a predetermined time has elapsed, the rotational speed of the indoor fan 12 is increased by ΔX ₁ (step 5). In the first embodiment, ΔX _{1 is set} to 10 r / min, and the rotation speed is increased by 10 r / min every 10 seconds. After the rotation speed of the indoor fan 12 is increased, the detected temperature of the central temperature sensor 10 attached to the central part of the indoor heat exchanger 3 and the temperature of the outlet temperature sensor 11 attached to the outlet part 7 of the indoor heat exchanger 3. The difference is compared, and if the center temperature TC is higher than the outlet temperature TO by a predetermined temperature ΔT1 or more (5K or more in the present invention), the rotation speed of the indoor fan 12 is stopped and held as it is (step 6). If not, the number of rotations of the indoor fan 12 is increased again after a predetermined time (step 5). Thereafter, the process is repeated until a predetermined time A (5 minutes in the present invention) elapses after the heating operation is started (steps 6 and 7).

  By doing so, the rotational speed of the indoor fan 12 is too high, and the refrigerant is condensed and liquefied in the indoor heat exchanger 3 immediately after the start of the heating operation, so that the liquid refrigerant stays at the outlet portion 7 of the indoor heat exchanger 3. Can be prevented.

  FIG. 3 is a front sectional view showing the inside of the indoor unit of the air conditioner of the present invention, and FIG. 4 is a side sectional view. As shown in FIGS. 3 and 4, the merger 9 of the indoor heat exchanger 3 is disposed below the lowermost refrigerant inlet pipe 6 a of the heating inlet 6.

  At the start of the heating operation, the compressor 1 is controlled by an inverter, so that the compressor 1 is stabilized at a low frequency (about 30 Hz) for a few minutes after startup, and then the frequency is slowly increased. In general, floor-standing models have many diversion paths (4-6 paths, etc.), and the circulation amount per pipe tends to be small. As described above, since there is protection control at the time of start-up, the amount of refrigerant circulating through the pipe is further small, and the flow rate of the refrigerant is extremely low. As a result, the gas-liquid two-phase refrigerant tends to be separated into a gas phase and a liquid phase before entering the merger 9. When the refrigerant inlet 6 is at a lower position below the merger 9, the separated liquid layer stays in the pipe of the indoor heat exchanger 3 because the flow rate of the refrigerant is low.

In Embodiment 1 of the present invention, in order to suppress the liquid refrigerant stagnation, the position of the merger 9 is set to a low position, so that the liquid refrigerant stagnation in the pipe described above can be suppressed. At the same time, the stagnation of oil discharged from the compressor 1 together with the refrigerant can be suppressed, and the oil out of the compressor 1 can be avoided.

  According to the present invention, the reliability can be ensured only by the control change at the start-up without causing any trouble during the normal cooling / heating operation. In the present embodiment, the indoor fan 12 is not rotated until the temperature detected by the central temperature sensor 10 is 20 ° C. or higher at the start of heating operation. However, depending on conditions, the indoor fan 12 may be operated at a low speed. Absent.

(Embodiment 2)
FIG. 5 is a control flowchart of the second embodiment of the present invention. In Embodiment 1, in order to suppress the liquid refrigerant staying in the indoor heat exchanger 3, it is necessary to add the outlet temperature sensor 11 to the outlet portion 7 of the indoor heat exchanger. Can be determined in advance under the most severe conditions.

  Specifically, it is left overnight (12 hours or more) at an indoor temperature of 20 ° C. and an outdoor unit temperature of −15 ° C. (a temperature with a safety margin added to the minimum temperature in the product specifications), and the oil is allowed to sleep in the oil. When the heating operation was started, the rotational speed of the indoor fan 12 was determined on condition that the oil in the compressor 1 would not run out. The connection pipe had the same length (15 m) as that of the maximum pipe in actual use, and predetermined equipment was used for the indoor unit and the outdoor unit. Under such conditions, the heating operation is started, the compressor oil runs out, the temperature difference between the central portion of the indoor heat exchanger 3 and the outlet is checked, and a predetermined indoor fan 12 rotation speed at which no oil runs out is determined. To do.

  The number of rotations of the indoor fan 12 determined by the experiment is recorded in the electronic control unit and used at the start of the heating operation. By doing so, the reliability of the compressor 1 can be ensured without adding the outlet temperature sensor 11 to the outlet portion 7 of the indoor heat exchanger 3.

(Embodiment 3)
FIG. 6 is a side sectional view showing the inside of the indoor unit of the air conditioner according to the third embodiment of the present invention, and shows a state in which the indoor outlet 17 is closed by the up-and-down air direction changing blades 18. Normally, when the heating operation is started, the up / down air direction change 18 is opened at a predetermined angle, the indoor fan 12 is rotated, and the wind is sent out from the indoor outlet 17 into the room. However, in the embodiment of the present invention, the amount of air passing through the indoor heat exchanger 3 is suppressed by delaying the timing for opening the up / down air direction change 18 at the start of the heating operation (about 3 minutes). The liquid refrigerant stagnating in the indoor heat exchanger 3 can be suppressed from the same principle as described in FIG.

  Here, the same effect can be obtained by closing the indoor outlet 17 by delaying the timing of changing the left and right air direction changing blades 19 to a predetermined angle instead of the up and down air direction changing blades 18.

  Further, as shown in FIG. 7, there is an air outlet panel 20 that closes the indoor air outlet 17 of the indoor unit A when the operation is stopped. Normally, the outlet panel 20 is opened as the heating operation starts. However, the liquid refrigerant staying in the indoor heat exchanger 3 can be suppressed from the same principle as described above by delaying the opening timing.

  The same effect can be obtained also by the timing of opening and closing a suction port panel (not shown) that closes the indoor suction port 21 when the operation is stopped.

Refrigeration cycle diagram of the air conditioner in Embodiment 1 of the present invention Control flow chart of air conditioner in Embodiment 1 of the present invention Front sectional drawing which shows the inside of the indoor unit of the air conditioner in Embodiment 1 of this invention Side surface sectional drawing which shows the inside of the indoor unit of the air conditioner in Embodiment 1 of this invention Control flow chart of air conditioner in Embodiment 2 of the present invention Side surface sectional drawing which shows the inside of the indoor unit of the air conditioner in Embodiment 3 of this invention Side surface sectional drawing at the time of the blower outlet panel closure of the indoor unit of the air conditioner in Embodiment 3 of this invention Refrigeration cycle diagram of a conventional air conditioner

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compressor 2 Outdoor four-way valve 3 Indoor heat exchanger 4 Outdoor throttle mechanism 5 Outdoor heat exchanger 6 Heating inlet 6a Bottom refrigerant inlet piping 7 Outlet 8 Capillary tube 9 Merger 10 Central temperature sensor 11 Outlet Temperature sensor 12 Indoor fan 13 Indoor fan motor 14 Indoor temperature sensor 17 Indoor air outlet 18 Up / down air direction change vane 19 Left / right air direction change vane 20 Outlet panel 21 Indoor air inlet

Claims (5)

An indoor heat exchanger and an indoor fan in the indoor unit, an indoor fan motor capable of changing the rotation speed, an indoor temperature sensor that detects the indoor suction temperature, and a central temperature that detects the temperature near the central part of the indoor heat exchanger A sensor, an outlet temperature sensor for detecting an outlet temperature during heating operation of the indoor heat exchanger, a throttle mechanism for adjusting a refrigerant flow rate to the indoor heat exchanger, and a merger, and the merger Is disposed below the lowermost refrigerant inlet pipe of the heating inlet of the indoor heat exchanger, and the number of rotations of the indoor fan motor at the start of heating operation is determined by the central temperature sensor. An air conditioner that is stopped or rotated at a low speed so that a difference between a detected temperature and a detected temperature of the outlet temperature sensor is within a predetermined temperature. Sensor that detects indoor suction temperature, sensor that detects indoor heat exchanger temperature, throttle mechanism and merger for refrigerant distribution in indoor heat exchanger, indoor fan motor with variable rotation speed, variable frequency A compressor, an outdoor throttle mechanism, an outdoor air blowing mechanism, an outdoor heat exchanger, and an outdoor four-way valve, and the merging device is more than the refrigerant inlet pipe at the bottom of the heating inlet portion of the indoor heat exchanger. Rotation is arranged so as to be positioned below, and the rotation speed of the indoor fan motor at the start of heating operation is determined so that the temperature in the vicinity of the center of the indoor heat exchanger and the outlet temperature are within a predetermined temperature difference An air conditioner characterized by its number. The air conditioner according to claim 1 or 2, wherein the indoor air outlet is closed by the indoor right / left or up / down air direction changing blade. The air conditioner according to claim 1 or 2, wherein the indoor air outlet is closed with a panel that covers the indoor air outlet. The air conditioner according to claim 1 or 2, wherein the indoor suction port is closed with a panel that covers the indoor suction port.