JP2006153397A - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air conditioner capable of determining the probability of frosting on an indoor unit by comparing cooling capacity calculated from an operating state of the indoor unit with cooling capacity calculated from an operating state of an outdoor unit. <P>SOLUTION: This air conditioner comprises an indoor differential temperature operating means for operating differential temperature between an indoor temperature and an indoor heat exchanger temperature in a cooling operation, a refrigerant-side cooling capacity function obtained by functionizing the relationship of a prescribed indoor humidity, cooling capacity under a prescribed indoor fan air volume and an outside air temperature while applying an operational frequency of a compressor as a parameter in advance, an air-side cooling capacity function obtained by functionizing the relationship of cooling capacity and a result of the operation by the indoor differential temperature operating means while applying the determined air volume of the indoor fan as a parameter in advance, and a cooling capacity comparing means for comparing the refrigerant-side cooling capacity derived from the refrigerant-side cooling capacity function and the air-side cooling capacity derived from the air-side cooling capacity function during the cooling operation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an air conditioner, and more particularly to an air conditioner provided with a means for preventing dew condensation on an indoor unit or an abnormality detecting means for a refrigeration cycle.

Conventionally, this type of air conditioner calculates the difference between the indoor temperature and the indoor heat exchanger temperature as the temperature difference of the blowout part, and the room temperature and the indoor heat that cause the blowout part to be exposed depending on the indoor humidity. Calculate the limit value of the temperature difference with the exchanger temperature as the dew temperature difference, compare the blower temperature difference with the dew temperature difference, and if the blower temperature difference exceeds the dew temperature difference, the compressor There is one provided with a dew prevention means for limiting the operation frequency (see, for example, Patent Document 1).

  FIG. 5 is a graph showing the relationship among the operating frequency of the compressor by the conventional air conditioner described in Patent Document 1, the room temperature, the temperature difference of the blowing section, and the room humidity.

  In FIG. 5, the horizontal axis is the indoor humidity H, and the vertical axis is the blowing portion temperature difference Δd calculated as the difference between the indoor temperature DI and the indoor heat exchanger temperature DE. Downward straight lines f = 100 Hz, 80 Hz, 60 Hz, 40 Hz, and 20 Hz are values obtained by connecting the values of the indoor humidity H and the blower temperature difference Δd with a straight line when the operation frequency f of the compressor is fixed to each frequency. It is.

  Here, the straight line Lo: Δd = d0 is a value of the limit blowing portion temperature difference d0 that does not depend on the indoor humidity and causes dew at the indoor humidity H2.

  Therefore, in the indoor humidity H2, dew condensation occurs when the blowing portion temperature difference Δd exceeds d0, but dew condensation does not occur when the blowing portion temperature Δd is less than d0.

  On the other hand, a straight line L1: Δd = aH + b is obtained by connecting the values of the limit blowing temperature difference Δd at which dew is generated at each indoor humidity with a straight line. The straight line L1 is a straight line that descends to the right as shown in the figure. As the indoor humidity H increases, the dew temperature difference decreases.

  That is, as the indoor humidity H increases, dew is more likely to occur, and dew is generated even if the temperature difference Δd between the indoor heat exchanger and the room temperature is small.

  Such a straight line l1 is obtained by measuring the indoor temperature DI, the indoor heat exchanger temperature DE, and the operating frequency f of the compressor in a limit state where dew is actually generated at each indoor humidity H. The constants a and b can be determined from the measurement result.

In other words, the limit of the occurrence of dew in the indoor unit is determined as a function according to the indoor humidity H and the operating frequency f, and when the limit is exceeded, control is performed so as to limit the operating frequency of the compressor. Even when the operating frequency of the compressor is higher than before, the cooling capacity can be increased without causing dew, and the room temperature can be brought close to the target temperature quickly.
JP 2001-221484 A

  However, the above-described conventional configuration has a problem that a humidity sensor is required to detect indoor humidity, and the cost is high when used only for the purpose.

  The present invention solves the above-described conventional problems, and without using a humidity sensor, estimates the indoor humidity based on the characteristics of the refrigeration cycle, and determines whether there is a risk of dew condensation and whether there is an abnormality in the refrigeration cycle. An object of the present invention is to provide an air conditioner that can be used.

  In order to solve the conventional problems, an air conditioner according to the present invention includes an outdoor unit including at least a compressor and an outdoor heat exchanger, an indoor unit including at least an indoor fan and an indoor heat exchanger, and the outdoor unit. An outside air temperature sensor that detects an outside air temperature around the unit, an indoor temperature sensor that detects an indoor temperature around the indoor unit, an indoor heat exchanger temperature sensor that detects the temperature of the indoor heat exchanger, an indoor temperature and an indoor temperature An indoor differential temperature calculation means for calculating the differential temperature of the heat exchanger temperature, and a function of the relationship between the cooling capacity and the outside air temperature at a predetermined indoor humidity and a predetermined indoor fan air volume setting in advance using the operating frequency of the compressor as a parameter The refrigerant-side cooling capacity function, the air-side cooling capacity function obtained by functionalizing the relationship between the cooling capacity and the calculation result of the indoor differential temperature calculation means in advance using the set air volume of the indoor fan as a parameter, and during the cooling operation, Is obtained by a structure having a cooling capacity comparing means for comparing the air-side cooling capacity is derived as the refrigerant cooling capacity is derived by medium side cooling ability function by the air-side cooling ability function.

  As a result, operating conditions with the risk of dew condensation inside the air conditioning equipment are provided as a function, and the operation frequency of the compressor can be controlled based on the function, so dew condensation does not occur even without a humidity sensor. It is possible to operate at an operating frequency close to the limit, and to quickly bring the room temperature close to the target temperature.

  Further, the air conditioner of the present invention includes a filter clogging determination unit that determines the degree of clogging of the intake air filter of the indoor unit based on the calculation result of the cooling capacity comparison unit.

  As a result, when the air volume of the indoor unit is reduced to a predetermined value or less with respect to the set air volume, it can be determined that the filter is clogged and the predetermined air volume is not output.

  The air conditioner of the present invention further includes expansion valve operation determination means for determining whether or not the expansion valve is operating normally based on the calculation result of the cooling capacity comparison means.

  As a result, it is possible to determine an abnormal state in which the expansion valve is not operating when the expansion valve is open.

  Further, the air conditioner of the present invention includes a refrigerant amount determination unit that determines whether or not the refrigerant amount is appropriate based on the calculation result of the cooling capacity comparison unit.

  As a result, the refrigerant amount becomes extremely small, and an abnormal state where the evaporation temperature does not decrease with respect to the operation of the compressor can be determined.

  The air conditioner of the present invention realizes determining the presence or absence of the risk of dew condensation and the presence or absence of abnormality in the refrigeration cycle by estimating the indoor humidity from the characteristics of the refrigeration cycle without using a humidity sensor. Can do.

A first invention includes an outdoor unit including at least a compressor and an outdoor heat exchanger, an indoor unit including at least an indoor fan and an indoor heat exchanger, and an outdoor air temperature sensor that detects an outdoor air temperature around the outdoor unit; An indoor temperature sensor for detecting an indoor temperature around the indoor unit, an indoor heat exchanger temperature sensor for detecting the temperature of the indoor heat exchanger, and an indoor difference for calculating a difference between the indoor temperature and the indoor heat exchanger temperature A temperature calculation means, a refrigerant side cooling capacity function obtained by functionalizing a relationship between a cooling capacity and an outside air temperature in a predetermined indoor humidity and a predetermined indoor fan air volume setting in advance using the operating frequency of the compressor as a parameter, and the indoor fan in advance The air-side cooling capacity function obtained by functionalizing the relationship between the cooling capacity and the calculation result of the indoor differential temperature calculation means with the set air volume as a parameter, and the refrigerant side derived from the refrigerant-side cooling capacity function during cooling operation By providing a cooling capacity comparison means for comparing the cooling capacity and the air-side cooling capacity derived from the air-side cooling capacity function, the air conditioner has an operating condition with a risk of dew condensation as a function, Since the operating frequency of the compressor can be controlled based on the function, it is possible to operate at an operating frequency close to the limit at which dew does not occur even without a humidity sensor, and the room temperature can be quickly brought close to the target temperature.

In particular, the second invention uses the calculation result of the cooling capacity comparison means of the first invention as a filter clogging determination means for determining the degree of clogging of the intake air filter of the indoor unit.
When the air volume of the indoor unit has decreased to a predetermined value or less with respect to the set air volume, it can be determined that the filter has been clogged and the predetermined air volume has not been output.

  In particular, the third invention uses the calculation result of the cooling capacity comparison means of the first invention as an expansion valve operation determination means for determining whether or not the expansion valve is operating normally, thereby opening the expansion valve. It is possible to determine an abnormal state that does not work in a state where the operation has occurred.

  In the fourth aspect of the invention, in particular, the calculation result of the cooling capacity comparison unit of the first aspect is used for the refrigerant amount determination unit for determining whether or not the refrigerant amount is appropriate. It is possible to determine an abnormal state in which the evaporation temperature does not decrease with respect to the operation of the machine.

  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 control block diagram of the air conditioner according to the first embodiment of the present invention.

  In FIG. 1, the compressor 1 is driven by an inverter 21 at a predetermined operating frequency F, and is connected to a four-way valve 2, an outdoor heat exchanger 3, an expansion valve 4, and an indoor heat exchanger 5 in an annular refrigerant pipe to be refrigerated. Form a cycle. The indoor heat exchanger 5 and the indoor fan 6 are provided in the same housing and form an indoor unit 12.

  The outside air temperature sensor 7 is attached to the outdoor unit 11 and detects the outside air temperature To around the outdoor unit 11.

  The indoor temperature sensor 8 is attached to the indoor unit 12 and detects the indoor temperature Ta around the indoor unit 12.

  The indoor heat exchanger temperature sensor 9 detects the temperature Te of the indoor heat exchanger 5. The indoor temperature difference calculating means 22 calculates a difference temperature ΔT between the detected temperature Ta of the indoor temperature sensor 8 and the detected temperature Te of the indoor heat exchanger temperature sensor 9, and the air temperature cooling capacity function 23 together with the set air volume qi of the indoor fan 6. Is transmitted.

  The detection value To of the outside air temperature sensor 7 is transmitted to the refrigerant side cooling capacity function 24 together with the operating frequency F of the inverter 21.

  The air-side cooling capacity Qair determined by the air-side cooling capacity function 23 and the refrigerant-side cooling capacity Qref determined by the refrigerant-side cooling capacity function 24 are transmitted to the cooling capacity comparison means 25, and the dew determination means 26 is the cooling function. The risk of dew is determined based on the comparison result of the capability comparison means 25, and control is performed so as to suppress the operating frequency of the inverter 21.

  About the air conditioner comprised as mentioned above, the operation | movement and an effect | action are demonstrated below using FIG. 2 and FIG.

  FIG. 2 shows the concept of the function stored in the air side cooling capacity function 23.

  The air-side cooling capacity function 23 is different from the cooling capacity QairL in a condition in which there is a risk of dew condensation in the indoor unit 12 in advance (for example, the indoor dry bulb temperature is 27 ° C., the indoor relative humidity is 85%, and the indoor fan is set at low wind). The relationship of the temperature ΔT is stored as a linear function approximate expression QairL = a3 * ΔT + b3.

  Similarly, an approximate expression QairM = a2 * ΔT + b2 of a linear function in indoor fan medium wind setting and an approximate expression QairH = a1 * ΔT + b1 in indoor fan strong wind setting are also stored.

  For example, when the temperature difference ΔT between the indoor temperature Ta and the indoor heat exchanger temperature Te is 15K in the setting of the indoor fan weak wind, the calculation is always performed based on the input from each temperature sensor from the start of the cooling operation. The air-side cooling capacity Qair = Qair1 at that time is calculated.

  FIG. 3 shows the concept of the function stored in the refrigerant side cooling capacity function 24.

  The refrigerant-side cooling capacity function 24 is a binary linear function Qref = c when the operating frequency F and the outside air temperature To are changed under indoor conditions equivalent to the conditions for which the air-side cooling capacity function 23 is set. * T0 + d * F + e is stored.

  Although the cooling capacity Qref varies depending on the indoor fan setting, here, the cooling capacity when the indoor fan is set at low wind with a high risk of dew is Qref.

  For example, when the operation frequency F = 40 Hz and the outside air temperature To = 27 ° C., the refrigerant side cooling capacity Qref = at that time is calculated based on the input from each temperature sensor. Qref1 is calculated.

  Especially under conditions of high indoor humidity where there is a risk of dew condensation, the sensible heat ratio becomes small, the difference between the indoor temperature Ta and the indoor heat exchanger temperature Te becomes small, and the air-side cooling calculated by the air-side cooling capacity function 23 is performed. The capacity Qair is calculated to be smaller than the operation under the condition of low indoor humidity where there is no danger of dew.

  FIG. 4 shows, on the wet air diagram, a line segment A1-B indicating an operating state where there is a risk of dew and a line segment A2-C indicating an operating state where there is no risk of dew.

When the intake air temperature is A ° C at both points A1 and A2, and the enthalpy difference indicating the cooling capacity is equal in both conditions, the difference temperature ΔT of the line segment A1-B indicating the operating state where there is a risk of dew condensation Is A-B ° C, the temperature difference ΔT of the line A2-C showing the operating state without danger of dew is A-C ° C
Thus, the operating state A1-B with the risk of dew is smaller.

  Even in the air-side cooling capacity Qair calculated from the temperature difference ΔT, it is obvious that the operating state with the risk of dew is smaller.

  Here, the cooling capacity at the limit at which the danger of dew condensation is determined by the refrigerant-side cooling capacity function 24, and compared with the air-side cooling capacity Qair calculated by the air-side cooling capacity function 23 during the cooling operation, By determining that there is a risk of actual dew formation when Qair <Qref, the operating frequency F is suppressed before dew generation occurs without using a humidity sensor. Can be prevented.

  Further, in the present embodiment, when the indoor fan air volume decreases with respect to the set air volume, the temperature difference ΔT between the room temperature Ta and the indoor heat exchanger temperature Te increases, and the air-side cooling capacity calculated from the temperature difference ΔT. Since Qair also increases, the air-side cooling capacity Qair calculated by the air-side cooling capacity function 23 during the cooling operation is compared with the refrigerant-side cooling capacity Qref, and when Qair> Qref + predetermined value, the indoor air volume decreases. That is, filter clogging can also be determined.

  In the present embodiment, the temperature difference ΔT between the indoor temperature Ta and the indoor heat exchanger temperature Te in an abnormal state in which the expansion valve is in an open state and in an abnormal state in which the refrigerant is extremely low. Since the air-side cooling capacity Qair calculated from the temperature difference ΔT is extremely small, the air-side cooling capacity Qair and the refrigerant-side cooling capacity Qref calculated by the air-side cooling capacity function 23 during the cooling operation are also reduced. It is also possible to determine whether the expansion valve is abnormal or the refrigerant amount is abnormal when Qair <Qref−predetermined value.

  As described above, the air conditioner according to the present invention does not use a humidity sensor and estimates the indoor humidity based on the characteristics of the refrigeration cycle to determine whether there is a risk of dew condensation and whether there is an abnormality in the refrigeration cycle. Therefore, the present invention can also be applied to applications such as complementation of abnormality by the protective operation of the refrigeration cycle for discharge temperature protection and current protection.

Control block diagram according to Embodiment 1 of the present invention The figure which shows the example of a setting of the air side cooling capability function in Embodiment 1 of this invention The figure which shows the example of a setting of the refrigerant | coolant side cooling capability function in Embodiment 1 of this invention Wet air diagram illustrating the operation of the first embodiment of the present invention Relationship diagram between operating frequency of conventional compressor, indoor temperature, temperature difference of outlet and indoor temperature

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compressor 2 Four-way valve 3 Outdoor heat exchanger 4 Expansion valve 5 Indoor heat exchanger 6 Indoor fan 7 Outside temperature sensor 8 Indoor temperature sensor 9 Indoor heat exchanger temperature sensor 11 Outdoor unit 12 Indoor unit 21 Inverter 22 Indoor temperature difference calculation Means 23 Air-side cooling capacity function 24 Refrigerant-side cooling capacity function 25 Cooling capacity comparison means 26 Dew determination means

Claims (4)

An outdoor unit provided with at least a compressor and an outdoor heat exchanger; an indoor unit provided with at least an indoor fan and an indoor heat exchanger; an outdoor temperature sensor for detecting an outdoor temperature around the outdoor unit; and An indoor temperature sensor for detecting the indoor temperature, an indoor heat exchanger temperature sensor for detecting the temperature of the indoor heat exchanger, an indoor differential temperature calculating means for calculating a differential temperature between the indoor temperature and the indoor heat exchanger temperature, Using the operating frequency of the compressor as a parameter, the refrigerant-side cooling capacity function that functions as a function of the relationship between the cooling capacity and the outside air temperature at a predetermined indoor humidity and a predetermined indoor fan air volume setting, and the preset air volume of the indoor fan as a parameter. An air-side cooling capacity function obtained by functionalizing the relationship between the cooling capacity and the calculation result of the indoor differential temperature calculation means; the refrigerant-side cooling capacity derived from the refrigerant-side cooling capacity function during cooling operation; Cooling capacity comparison means for comparing the air-side cooling capacity derived by the air-side cooling capacity function is provided, and it is determined whether there is a risk of dew condensation on the indoor unit based on the calculation result of the cooling capacity comparison means. An air conditioner equipped with dew determination means. The air conditioner according to claim 1, further comprising a filter clogging determination unit that determines a degree of clogging of the suction air filter of the indoor unit based on a calculation result of the cooling capacity comparison unit. The air conditioner according to claim 1, further comprising expansion valve operation determination means for determining whether or not the expansion valve is operating normally based on a calculation result of the cooling capacity comparison means. The air conditioner according to claim 1, further comprising a refrigerant amount determination unit that determines whether or not the refrigerant amount is appropriate based on a calculation result of the cooling capacity comparison unit.

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