JP2006145204A - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air conditioner which controls humidity without using a humidity sensor in order to reduce costs. <P>SOLUTION: This air conditioner is provided with a target evaporator temperature determining means S2 for determining a target evaporator temperature corresponding to a target relative humidity of a room from a temperature α of the room detected by an indoor sucked air temperature sensor, and frequency control means S12, S19 and S6 for controlling operation frequencies of a compressor so that the temperature of the evaporator comes within the target evaporator temperature based on the evaporator temperature β detected by an indoor heat exchanger sensor and the target evaporator temperature. In determining the target evaporator temperature, the target evaporator temperature determining means S2 performs the calculation using correlation among room temperature, evaporator temperature, and relative humidity, or refers to a look-up table where the evaporator temperature and room temperature for obtaining target relative humidity are associated with each other in a one-to-one manner. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an air conditioner, and more particularly to humidity control during a dehumidifying operation of an air conditioner.

  Recently, air conditioners employing a dehumidification method called a reheat dehumidification (dry) method in which cold air that has been dampened is heated by a reheater and sent out are becoming mainstream.

  In such a conventional air conditioner, humidity control is performed using a humidity sensor during reheat dehumidification operation (see, for example, Patent Document 1). As an example of humidity control, the output from the humidity sensor is A / D converted into a digital value, and the relative humidity is obtained by calculation with a microcomputer (hereinafter referred to as “microcomputer”). Based on the deviation, the operation frequency of the compressor is controlled so that the relative humidity of the room becomes the set relative humidity.

However, in humidity control using a humidity sensor, the amount of computation by a microcomputer for obtaining the relative humidity is large, and the humidity sensor itself used only for obtaining the relative humidity of the room is an expensive electrical component. For these reasons, humidity control using a humidity sensor increases the manufacturing cost of the air conditioner.
JP 2000-088319 A

  Therefore, an object of the present invention is to provide an air conditioner that performs humidity control without using a humidity sensor in order to reduce costs.

In order to achieve the above object, the present invention provides an air conditioner including a compressor, a condenser, and an evaporator.
Indoor temperature detection means;
Evaporator temperature detection means;
A correlation between the room temperature, the evaporator temperature, and the relative humidity is used to calculate or refer to a look-up table that has a one-to-one correspondence between the evaporator temperature and the room temperature to obtain the target relative humidity. A target evaporator temperature determining means for determining a target evaporator temperature corresponding to the target relative humidity of the room from the temperature of the room detected by the room temperature detecting means;
Based on the evaporator temperature detected by the evaporator temperature detecting means and the target evaporator temperature determined by the target evaporator temperature determining means, the temperature of the evaporator becomes the target evaporator temperature. A frequency control means for controlling the operating frequency of the compressor is provided, and the humidity control of the room is performed without detecting the actual humidity of the room.

  There is a correlation between the room temperature, that is, the room temperature, the relative humidity of the room, and the evaporator temperature. FIG. 4 shows the relationship among room temperature, evaporator temperature, and relative humidity based on the results of tests conducted by the inventors. This test was conducted using a 2.8 kW class air conditioner in a 10 tatami room. In FIG. 4, broken lines a, b, c, and d are lines of relative humidity (RH%) 40%, 45%, 50%, and 55% obtained from the test results, respectively. Also, solid lines A, B, C, and D are lines in the primary approximation formula obtained based on the RH% lines a, b, c, and d from the test results, respectively. The straight lines A, B, C, and D have the same slope 15/16. From this figure, it can be seen that if the room temperature and relative humidity are determined, the evaporator temperature is uniquely determined. The present invention has been made paying attention to this point. In FIG. 4, test results other than relative humidity of 40%, 45%, 50%, and 55% are omitted for easy viewing of the graph.

  In the air conditioner of the present invention, during normal cooling operation or dehumidifying operation, the room temperature detecting means detects the temperature of the room, while the evaporator temperature detecting means detects the temperature of the evaporator (indoor heat exchanger). . Then, the target evaporator temperature determining means determines a target evaporator temperature corresponding to the target relative humidity of the room from the detected room temperature. Then, the frequency control means controls the operation frequency of the compressor based on the detected evaporator temperature and the determined target evaporator temperature so that the evaporator temperature becomes the target evaporator temperature. In this way, the humidity is controlled.

  When the target evaporator temperature is determined, the target evaporator temperature determining means calculates using the correlation between the room temperature, the evaporator temperature, and the relative humidity, or obtains the target relative humidity. For this reason, a look-up table in which the evaporator temperature and the room temperature are associated with each other on a one-to-one basis is referred to.

  As can be seen from FIG. 4, the target evaporator temperature with respect to a certain room temperature can be easily obtained by using a linear expression of the slope a (for example, 15/16) representing the target relative humidity line. Therefore, the target evaporator temperature can be calculated with a small calculation amount.

  Also, a look-up table in which the room temperature and the evaporator temperature for obtaining the target relative humidity are associated with each other on a one-to-one basis may be mounted on the air conditioner.

  According to the present invention, only the temperature of the room and the temperature of the evaporator should be detected for humidity control, and the detection means is an indoor temperature detection means such as a thermistor that is almost always installed in an air conditioner. Only the evaporator temperature detection means is required. An expensive humidity sensor is unnecessary. Therefore, the air conditioner of the present invention can be manufactured at low cost.

  In one embodiment, the air conditioner has a reheat dehumidifying function, a first indoor heat exchanger that functions as a condenser during a reheat dehumidifying operation, and a second indoor heat exchanger that functions as an evaporator. In the reheat dehumidifying operation, the evaporator temperature detecting means detects the temperature of the second indoor heat exchanger functioning as an evaporator as the evaporator temperature, and the frequency control means is configured to detect the second indoor heat. The operation frequency of the compressor is controlled so that the temperature of the exchanger becomes the target evaporator temperature.

  In normal cooling operation, particularly at the initial stage of the operation, wind having a temperature significantly different from the temperature of the indoor air is blown out, so that the indoor temperature is likely to be uneven, and the accuracy of humidity control is likely to be reduced accordingly. On the other hand, in the reheat dehumidifying operation, the room air is sucked and the dehumidified air having the same temperature as that of the room temperature is blown out and circulated. Since the temperature of the intake air, that is, the room temperature is constant, humidity control can be performed with high accuracy.

  The air conditioner of the present invention further includes a comparison means for comparing the detected evaporator temperature with the target evaporator temperature, the target evaporator temperature has an upper limit and a lower limit, and the comparison means is detected. The evaporator temperature is compared with the upper limit and lower limit of the target evaporator temperature, and the frequency control means determines that the evaporator temperature is between the upper limit and lower limit of the target evaporator temperature based on the comparison result by the comparison means. You may make it control the operating frequency of a compressor so that it may enter.

As an example of such control, the frequency control means is
When the detected evaporator temperature is equal to or higher than the upper limit of the target evaporator temperature, the operation frequency of the compressor is increased by a certain amount (for example, 2 Hz) every predetermined time (for example, 10 minutes),
When the detected evaporator temperature is less than the lower limit of the target evaporator temperature, the operation frequency of the compressor is decreased by a certain amount (for example, 2 Hz) every predetermined time (for example, 10 minutes),
When the detected evaporator temperature is equal to or higher than the lower limit and lower than the upper limit of the target evaporator temperature, control for maintaining the current operating frequency of the compressor may be performed.

In order to control the target relative humidity to about 40% to 70%, when the upper and lower limits of the target evaporator temperature are Km1 and Km2, respectively, and the room temperature is α, Km1 and Km2 are respectively Km1 = α × a + b1 (° C.), Km2 = α × a + b2 (° C.)
(However, 12/16 ≦ a ≦ 31/32, −22 ≦ b1 ≦ −2, b1-4 ≦ b2 ≦ b1-1) may be set.

  As described above, the slopes of the straight lines A, B, C, and D shown in FIG. 4 based on the test results are 15/16. Therefore, in one example, a = 15/16, b1 = −12, and b2 = −14. That is, the upper limit and the lower limit of the target evaporator temperature are set to α × 15 / 16-12 (° C.) and α × 15 / 16-14 (° C.), respectively. As a result, the relative humidity of the room can be converged to around 50% which is comfortable for human beings.

  Next, the present invention will be described with reference to the illustrated embodiments.

  FIG. 1 is a refrigeration cycle block diagram of an air conditioner having a reheat dehumidification function according to an embodiment of the present invention. In FIG. 1, 1 is a compressor, 2 is a four-way valve, 3 is an outdoor heat exchanger, 4 is an outdoor fan, 5 is an outdoor fan motor, 6 is an electric expansion valve, and 7 and 8 are closing valves. Reference numerals 9 and 10 denote first and second indoor heat exchangers, 11 a reheat dehumidification capillary, 12 a two-way valve, 13 an indoor fan, and 14 an indoor fan motor. Further, 15 represents the outdoor unit side piping collectively, and 16 represents the indoor unit side piping collectively. Reference numeral 17 denotes a connection pipe for connecting the outdoor unit side pipe 15 and the indoor unit side pipe 16. Reference numeral 22 denotes an indoor suction temperature sensor as indoor temperature detection means, 23 denotes an indoor heat exchanger temperature sensor as evaporator temperature detection means, 32 denotes an outdoor suction temperature sensor, and 33 denotes an outdoor heat exchanger temperature sensor. A solid line arrow indicates the direction of refrigerant flow during cooling and reheat dehumidification operation, and a broken line arrow indicates the direction of refrigerant flow during heating operation.

  During normal cooling operation, the four-way valve 2 is switched to a switching position indicated by a solid line, the electric expansion valve 6 is throttled, the two-way valve 12 is fully opened, and the outdoor heat exchanger 3 functions as a condenser. 1 and 2nd indoor heat exchangers 9 and 10 function as an evaporator. In the reheat dehumidifying operation, the electric expansion valve 6 is fully opened and the two-way valve 12 is closed, so that the outdoor heat exchanger 3 and the first indoor heat exchanger 9 function as a condenser. The indoor heat exchanger 10 functions as an evaporator. On the other hand, during the heating operation, the four-way valve 2 is switched to the switching position indicated by the dotted line, the two-way valve 12 is fully opened, the electric expansion valve 6 is throttled, and the first and second indoor heat exchangers 9 and 10 are condensed. The outdoor heat exchanger 3 functions as an evaporator.

  FIG. 2 is a block diagram showing a control system of the air conditioner. As shown in FIG. 2, the air conditioner includes an indoor control unit 20 configured by a microcomputer mounted on the indoor unit and an outdoor control unit 30 configured by a microcomputer mounted on the outdoor unit. The indoor control unit 20 includes a target evaporator temperature determination unit that determines a target evaporator temperature, a comparison unit that compares the detected evaporator temperature and the target evaporator temperature, and the evaporator based on the comparison result. In addition to having frequency control means for controlling the operating frequency of the compressor 1 so that the temperature becomes the target evaporator temperature, the outdoor control unit 30 operates the compressor 1 in cooperation with the frequency control means of the indoor control unit 20. Frequency control means for controlling the frequency is provided. The indoor control unit 20 and the outdoor control unit 30 exchange data and control signals with each other.

  Further, the indoor control unit 20 receives a signal indicating the room temperature (temperature of the intake air by the indoor unit) from the indoor suction temperature sensor 22, and the evaporator temperature (cooling and reheat dehumidifying operation) from the indoor heat exchanger temperature sensor 23. A signal indicating the temperature of the second indoor heat exchanger 10 functioning as an evaporator) and a control signal from a remote controller (hereinafter referred to as remote controller) 21 are input.

  On the other hand, the outdoor control unit 30 has a signal indicating the outside air temperature from the outdoor unit suction temperature sensor 32 (the temperature of the intake air by the outdoor unit), a signal indicating the outdoor heat exchanger temperature from the outdoor heat exchanger temperature sensor 33, And the signal from CT (current transformer) sensor 34 is inputted.

  The indoor control unit 20 controls the rotational speed of the indoor fan motor 14 via the speed control circuit 25 according to the input signal, and also controls the abnormal operation display circuit 18 that displays that the operation is abnormal. On the other hand, the outdoor control unit 30 controls the rotational speed of the outdoor fan motor 5 through the speed control circuit 35 according to the input signal, and switches the four-way valve 2 according to the operation mode and the electric expansion valve 6. Controls opening and closing. Further, the operation frequency of the compressor 1 is controlled through the control of the inverter circuit 19.

  In this air conditioner, during the reheat dehumidifying operation, the rotation speed of the compressor, that is, the operation frequency is controlled in three humidity zones according to the evaporator temperature as shown in FIG. In FIG. 5, the RC zone is the frequency up zone, the RA zone is the frequency down zone, and the RB zone between the evaporator temperatures Km1 and Km2 is the frequency status maintenance zone. As an example of control, in this embodiment, in the RC zone, the frequency is increased by one step (F1 = 2 Hz) every 10 minutes, and in the RA zone, the frequency is decreased by one step (F2 = 2 Hz) every 10 minutes. I do. At the start of operation, the frequency up zone is controlled. Here, the target relative humidity is set to around 50%.

  Next, a humidity control program during the reheat dehumidifying operation will be described with reference to FIG.

  First, in step S1, the temperature of the intake air, that is, the room temperature α is detected by the indoor intake temperature sensor 22, and the temperature of the second indoor heat exchanger 10, that is, the evaporator temperature β is detected by the indoor heat exchanger temperature sensor 23. Is done.

Next, in step S2, the range of the target evaporator temperature, that is, the upper limit Km1 and the lower limit Km2 are calculated by the indoor control unit 20 using the following linear expressions (1) and (2).
Km1 = α × a + b1 (° C.). . . (1)
Km2 = α × a + b2 (° C.). . . (2)

Here, b1 and b2 are values that change according to the target relative humidity, the installation position of the indoor heat exchanger temperature sensor 23, and the like, and are values that are determined when the target relative humidity is determined. A takes a value in the range of 12/16 to 31/32. Further, b2 is set to a temperature 1 to 4 ° C. lower than b1. In this embodiment, in order to set the target relative humidity in the vicinity of 50%, a is set to 15/16, b1 is set to -12 ° C, and b2 is set to -14 ° C. Therefore, the upper limit Km1 and the lower limit Km2 of the target evaporator temperature are expressed by the equations (1) ′ and (2) ′, respectively.
Km1 = α × 15 / 16-12 (° C.). . . (1) '
Km2 = α × 15 / 16-14 (° C.). . . (2) '
Is obtained by substituting the room temperature value detected in step 1 for α.

  Next, in step S3, the detected evaporator temperature β is compared with the upper limit Km1 of the target evaporator temperature. As a result of the comparison, if the evaporator temperature β is equal to or higher than the upper limit Km1 of the target evaporator temperature, in order to control the RC zone (frequency up zone) shown in FIG. ) To clear the timer T2 for measuring the predetermined time in step S8, and to determine whether or not the timer T1 for measuring the predetermined time in the RC zone (here, 10 minutes) is cleared in step S8. If cleared, the timer T1 is set in step S9 to start counting for a predetermined time of 10 minutes, and the process returns to step S1.

  When the process proceeds to step S8 in the same manner as described above, since the timer T1 is not cleared this time, the process proceeds to step S10. In step S10, it is determined whether the timer T1 has finished counting. While 10 minutes have not elapsed, the program proceeds to step S11 and the counting by the timer T1 is continued.

  And when 10 minutes which are predetermined time passes, it will progress to step S12 from step S10, and the command which raises the operating frequency of a compressor by 1 step (F1 = 2Hz) will be given with respect to the outdoor control part 30. FIG. Then, in the next step S13, the timer T1 is set again, the time measurement for a predetermined time of 10 minutes is started, and the process returns to step S1. Receiving a command to increase the operating frequency of the compressor by one step (F1), the outdoor control unit 30 sends a control signal to the inverter circuit 19 to increase the frequency and increase the rotational speed of the compressor 1. By repeating the above process, the humidity gradually decreases.

  On the other hand, if it is determined in step S3 that the evaporator temperature β is not equal to or higher than the upper limit Km1 of the target evaporator temperature, the evaporator temperature β is compared with the lower limit Km2 of the target evaporator temperature in step S4. As a result of the comparison, if it is determined that the evaporator temperature β is lower than the lower limit Km2 of the target evaporator temperature, the routine proceeds to step S14 to control the RA zone (frequency down zone) shown in FIG. In addition to clearing T1, it is determined in step S8 whether or not the timer T2 for measuring a predetermined time (here, 10 minutes) in the RA zone has been cleared. T2 is set to start counting for a predetermined time of 10 minutes, and the process returns to step S1.

  When the process proceeds to step S15 in the same manner as described above, since the timer T2 is not cleared this time, the process proceeds to step S17. In step S17, it is determined whether the timer T2 has finished counting. While 10 minutes have not elapsed, the program proceeds to step S18 and the counting by the timer T2 is continued.

  And when 10 minutes which are predetermined time passes, it will progress to step S19 from step S17, and the command which decreases the operating frequency of a compressor by 1 step (F2 = 2Hz) will be given with respect to the outdoor control part 30. FIG. Then, in the next step S20, the timer T2 is set again, the time measurement for a predetermined time of 10 minutes is started, and the process returns to step S1. The outdoor control unit 30 that has received a command to reduce the operating frequency of the compressor by one step (F2) sends a control signal to the inverter circuit 19 to reduce the frequency and reduce the rotational speed of the compressor 1. By repeating the above process, the humidity gradually increases.

  On the other hand, if it is determined in step S4 that the evaporator temperature β is not lower than the lower limit Km2 of the target evaporator temperature, the process proceeds to step S5. In this case, since the evaporator temperature β is within the target evaporator temperature range (Km2 ≦ β <Km1), both timers T1 and T2 are cleared, and the operation frequency of the compressor is maintained as it is in S6. A command is issued to the outdoor control unit 30. Receiving this command, the outdoor control unit 30 performs control to maintain the rotational speed of the compressor 1 via the inverter circuit 19.

  By performing the above processing, the indoor relative humidity is converged to around 50%, which is the target relative humidity.

  In this embodiment, all the steps described in FIG. 3 are performed by the indoor control unit 20, but signals representing the temperatures α and β detected in step S1 are transmitted from the indoor control unit 20 to the outdoor. By sending it to the control unit 30, the outdoor control unit 30 can perform the processing after step S2. In that case, the compressor frequency command in steps S12, S19, and S6 is directly output to the inverter circuit 19.

  Further, in the present embodiment, control is performed so that the target evaporator temperature has a range. The target evaporator temperature does not necessarily have a width, but a wider control can be performed with a wider width.

  In the present embodiment, the target relative humidity in the room is around 50%, but other numerical values may be set. When the target relative humidity is set to a different value, a, b1, and b2 in the above linear expressions (1) and (2) may be set to values corresponding to the target relative humidity. When the target relative humidity is about 40% to 70% RH, 12/16 ≦ a ≦ 31/32, −22 ≦ b1 ≦ −2, and b1-4 ≦ b2 ≦ b1-1 are satisfied. The upper limit Km1 and the lower limit Km2 of the target evaporator temperature may be set.

  Further, in the present embodiment, the target evaporator temperature is obtained by calculation, but a look-up table in which the room temperature and the evaporator temperature for obtaining the target relative humidity are associated one-to-one is used for the air conditioner. It may be installed. In that case, step S2 in FIG. 3 is a step of referring to this lookup table.

  Moreover, although the air conditioner of this Embodiment was equipped with the 1st, 2nd indoor heat exchanger and had a reheat dehumidification function, this invention is an air conditioner which does not have a reheat dehumidification function. Can also be used.

It is a refrigeration cycle block diagram in an example of an air conditioner to which the present invention is applied. It is a block diagram which shows the control system of the air conditioner of FIG. 3 is a flowchart of humidity control executed by the control system shown in FIG. 2. It is a graph showing the relationship between room temperature, evaporator temperature, and relative humidity. It is a figure explaining the three control zones of the compressor frequency in the air conditioner of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compressor 2 Four-way valve 3 Outdoor heat exchanger 4 Outdoor fan 5 Fan motor 6 Electric expansion valve 7, 8 Shut-off valve 9 1st indoor heat exchanger 10 2nd indoor heat exchanger 11 Reheat dehumidification capillary 12 Two-way valve 13 Indoor Fan 14 Fan Motor 15 Outdoor Unit Side Piping 16 Indoor Unit Side Piping 17 Communication Piping

Claims (4)

In an air conditioner equipped with a compressor (1), a condenser and an evaporator,
Indoor temperature detection means (22);
An evaporator temperature detecting means (23);
A correlation between the room temperature, the evaporator temperature, and the relative humidity is used to calculate or refer to a look-up table that has a one-to-one correspondence between the evaporator temperature and the room temperature to obtain the target relative humidity. Thus, the target evaporator temperature determining means (20, 2) for determining the target evaporator temperature (Km1, Km2) corresponding to the target relative humidity of the room from the room temperature detected by the room temperature detecting means (22). S2)
Based on the evaporator temperature (β) detected by the evaporator temperature detecting means (23) and the target evaporator temperature determined by the target evaporator temperature determining means, the temperature of the evaporator is changed to the target evaporation. Frequency control means (20, 30, S6, S12, S19) for controlling the operating frequency of the compressor (1) so as to reach the chamber temperature, without detecting the actual humidity of the room. An air conditioner characterized by humidity control. In the air conditioner according to claim 1,
Has a reheat dehumidification function,
A first indoor heat exchanger (9) that functions as a condenser during reheat dehumidifying operation, and a second indoor heat exchanger (10) that functions as an evaporator,
During the reheat dehumidifying operation, the evaporator temperature detection means detects the temperature of the second indoor heat exchanger (10) functioning as an evaporator as the evaporator temperature, and the frequency control means (20, 30, S6, S12 and S19) are air conditioners that control the operating frequency of the compressor (1) so that the temperature of the second indoor heat exchanger (10) becomes the target evaporator temperature. In the air conditioner according to claim 1 or 2,
Comparing means (20, S3, S4) for comparing the detected evaporator temperature (β) with the target evaporator temperature (Km1, Km2) is further provided. The target evaporator temperature has an upper limit (Km1) and a lower limit (Km2). )
The comparison means compares the detected evaporator temperature with the upper limit and lower limit of the target evaporator temperature,
The frequency control means controls the operating frequency of the compressor so that the evaporator temperature falls between the upper limit and the lower limit of the target evaporator temperature based on the comparison result by the comparison means. . In the air conditioner according to claim 3,
The frequency control means (20, 30, S6, S12, S19)
When the detected evaporator temperature (β) is equal to or higher than the upper limit (Km1) of the target evaporator temperature, control is performed to increase the operating frequency of the compressor by a certain amount every predetermined time,
When the detected evaporator temperature (β) is less than the lower limit (Km2) of the target evaporator temperature, control is performed to decrease the operating frequency of the compressor by a certain amount every predetermined time,
The air conditioning is characterized in that when the detected evaporator temperature (β) is not less than the lower limit (Km2) of the target evaporator temperature and less than the upper limit (Km1), control is performed to maintain the current operating frequency of the compressor. Machine.

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