JP2000018679A - Controller for air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve dehumidifying effect while contriving the prevention of freezing in an indoor heat exchanger through the increase or decrease of the flow rate of indoor air by a method wherein a reference temperature for regulating the flow rate of indoor air by a detecting temperature of a heat medium is changed upon cooling operation and dehumidifying operation. SOLUTION: Upon deciding whether the increase or the decrease of the number of rotation of an indoor fan is effected or not during cooling operation, a lower limit reference value T1, deciding whether the number of rotation to obtain the lower limit of a heat medium temperature is increased or not, or an upper limit reference value T2, deciding whether the number of rotation to obtain the upper limit of the same temperature is decreased or not, is determined (step 103), then, the reference values T1, T2 of the heat medium temperature, which are different upon dehumidifying operation and cooling operation, are determined (step 104). A heat medium temperature Te is decided whether the same is lower than the lower limit reference value T1 or not (step 106) and when the temperature Te is lower than the reference value T1, the number of rotation of an indoor fan is increased (step 107). When the heat medium temperature Te is higher than the reference value T1, whether the temperature Te is higher than the upper limit value T2 or not is decided (step 108) and when the temperature Te is higher than the upper limit reference value T2, the number of rotation of the indoor fan is reduced by a predetermined number of rotation (step 109).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an air conditioner for preventing freezing of an indoor heat exchanger and wear of a compressor. In particular, the present invention relates to a control device for an air conditioner that prevents the freezing of an indoor heat exchanger and the wear of a compressor while maintaining the comfort of indoor air conditioning during a dehumidifying operation.

[0002]

2. Description of the Related Art In a cooling operation and a dehumidifying operation of an air conditioner, it is necessary to lower the temperature of a heat medium in an indoor heat exchanger (hereinafter simply referred to as a heat medium temperature). In order to maximize the latent heat capacity (the ability to lower the humidity) while minimizing (the ability to lower the temperature of the room) as much as possible, keep the temperature of the heating medium as low as possible without freezing, and in order not to lower the perceived temperature, It is desirable to set the indoor air volume as small as possible. However, when the heat medium temperature is set low and the amount of indoor air is set small, there is a problem that the indoor heat exchanger is easily frozen. Therefore, in the conventional air conditioner, when the heat medium temperature has reached a predetermined reference value or less, the problem has been solved by increasing the indoor air flow by a predetermined set value. And this heat medium temperature reference value is the same without distinction of cooling operation and dehumidification operation,
The set value of the amount of room air, which is the increase, was constant regardless of the cooling operation and the dehumidifying operation.

[0003] In particular, during the dehumidifying operation, the compressor is continuously operated at a low frequency in order to keep the heat medium circulation amount low. However, as a result, there is a problem that the oil level of the refrigerating machine oil of the compressor is reduced and the compressor is easily worn out. In response to this, when the compressor is continuously operated at a low frequency for a certain time, In order to recover the oil level by collecting the refrigerating machine oil, the frequency of the compressor is temporarily increased to a predetermined frequency, and the operation of opening the expansion valve to a predetermined large opening (refrigerating machine oil collecting operation) is periodically performed. We have tried to solve the problem. However, the compressor frequency and the expansion valve opening during the refrigerating machine oil recovery operation were merely changed to fixed values stored in advance regardless of the frequency and the opening before the operation.

[0004]

Although increasing the indoor air volume is effective for preventing the indoor heat exchanger from freezing, the same reference value of the heat medium temperature as in the cooling operation in the dehumidifying operation as in the cooling operation is used. Moreover, if the indoor air volume is increased by the same amount as the air volume during the cooling operation, the temperature of the heat medium during the dehumidifying operation cannot be sufficiently lowered, and the dehumidifying effect becomes insufficient, and the indoor air volume during the dehumidifying operation is too large. However, there has been a problem that the perceived temperature drops rapidly and the comfort is impaired.

[0005] Further, while the refrigerating machine oil recovery operation is effective in preventing compressor abrasion, the compressor frequency and the expansion valve opening during the oil recovery operation are fixed values irrespective of those before the oil recovery operation. Therefore, there is a problem that the room temperature can be extremely changed before and after the refrigerating machine oil recovery operation.

[0006]

According to a first aspect of the present invention, there is provided:
When the heat medium temperature detected by the heat medium temperature detecting means reaches a predetermined reference temperature, the indoor air flow rate controlling means includes a heat medium temperature detecting means arranged near the heat medium inlet of the indoor heat exchanger. In the air conditioner control device for controlling the indoor air flow rate by controlling the indoor air flow rate control means, the reference temperature is changed between a cooling operation and a dehumidifying operation.

A second embodiment of the present invention includes indoor air flow control means and a heat medium temperature detecting means disposed near a heat medium inlet of an indoor heat exchanger, and is detected by the heat medium temperature detecting means. In the control device of the air conditioner, which adjusts the indoor air flow rate by controlling the indoor air flow rate control means when the heat medium temperature reaches a predetermined reference temperature, the indoor air flow rate adjusted during the cooling operation is calculated based on the indoor air flow rate adjusted during the dehumidification operation. Is also set to be large.

According to a third aspect of the present invention, there is provided a control device for an air conditioner including a compressor and an expansion valve, in which the compressor is operated from a predetermined time to a first predetermined time (T1). When the frequency is lower than the predetermined frequency (F), the frequency of the compressor is increased by a predetermined frequency and the expansion valve is opened by a predetermined opening for a second predetermined time (T2).

[0009]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an air conditioner for cooling and heating. The air conditioner generally includes an indoor unit 1 arranged in a space to be air-conditioned and an outdoor unit 2 arranged outdoors.
And a circulation path 3 for a heat medium (refrigerant).

The outdoor unit 1 includes an outdoor heat exchanger 4 for exchanging heat between a heat medium and outdoor air by a refrigeration cycle, a compressor 5 for compressing the heat medium, and a flow of the heat medium between a cooling operation and a heating operation. It has a four-way valve 6 for switching and an expansion valve 7 for lowering the pressure of the heat medium. The indoor unit 2 includes an indoor heat exchanger 8 for exchanging heat between a heat medium and indoor air by a refrigeration cycle, a power switch 9 for turning on / off a power supply, and an operation mode for setting operation modes (cooling, heating, and dehumidification). An input unit 11 including a switch 10 and a heat medium temperature sensor 12 arranged near a heat medium inlet of the indoor heat exchanger 8
And an indoor fan 13 for controlling the amount of indoor air, an operation control unit 14 for controlling the compressor 5, the expansion valve 7, and the indoor fan 13, and processing of information from the input unit 11, the heat medium temperature sensor 12, and the operation control unit 14. And a central control unit 15 (see FIG. 2) for transmitting a control signal to the operation control unit 14.

(Embodiment 1) FIG. 2 is a block diagram showing a control circuit of an air conditioner according to an embodiment of the present invention.
In this control circuit, the main body control unit 16 includes the input unit 1
The operation mode information input by the operation mode switch 10 and the heat medium temperature information detected by the heat medium temperature sensor 12 are sent to the central control unit 15, and the central control unit 15 A control signal for driving the indoor fan 13 is transmitted to the operation control unit 14 based on the reference value of the heat medium temperature and the information such as the set value of the indoor air volume stored in the table storage unit 17 in advance. I have.

First, referring to the flowchart of FIG. 3, the central control unit 15 sets the indoor fan 13 at different reference values of the heat medium temperature depending on the case of the cooling operation and the case of the dehumidifying operation.
Will be described. When the power switch 9 of the input unit 11 is pressed, an operation mode signal is transmitted to the central control unit 15 together with an operation start signal. When the central control unit 15 detects the input of the operation start signal, the air conditioning operation is started by driving the indoor fan 13 and the like via the operation control unit 14 (step 100).

The central controller 15 first determines in step 101 whether the operation mode is the cooling operation. If it is determined that the cooling operation is being performed, the central control
Retrieves the heating medium temperature-indoor fan rotation speed table from the table storage unit 17, and determines a reference value (threshold) of the heating medium temperature for determining whether to increase or decrease the indoor fan rotation speed. Here, T1 is a lower limit reference value for determining whether to increase the indoor fan speed, and T2 is an upper limit reference value for determining whether to decrease the indoor fan speed.

If it is determined in step 101 that the cooling operation is not being performed, the central control unit 15 determines in step 102 whether the dehumidifying operation is being performed. Then, during the dehumidifying operation, the central control unit 15 calls up the heating medium temperature-indoor fan rotation speed table from the table storage unit 17 as in the cooling operation, and the lower limit reference value (T) of the heating medium temperature during the dehumidifying operation.
1) and an upper limit reference value (T2) are determined (step 1).
04). The reference values (T1, T2) of the heat medium temperature during the cooling operation and the dehumidifying operation are set to different values as shown in Table 1, for example.

[0015]

[Table 1]

If it is determined in step 102 that the operation is not the dehumidifying operation (that is, the heating operation), the air conditioning control of the present invention ends.

After the reference values (T1, T2) of the heat medium temperature are determined, the heat medium temperature (Te) is detected by the heat medium temperature sensor 12 in step 105.

In step 106, the central control unit 15 determines whether or not the heat medium temperature (Te) is equal to or lower than the lower limit reference value (T1) of the heat medium temperature. As a result of the determination, when the heat medium temperature (Te) is equal to or lower than the lower limit reference value (T1), the central control unit 15 sends a control signal to the operation control unit 14 so as to increase the rotation speed of the indoor fan 13 by a predetermined rotation speed. Send (step 107).
As the number of rotations of the indoor fan increases, the temperature of the heat medium (Te) increases. Conversely, the heat medium temperature (Te) is lower than the lower reference value (T1).
If it is higher, in step 108, the central control unit 15 determines whether the heat medium temperature (Te) is higher than the upper limit reference value (T2) of the heat medium temperature. If the heat medium temperature (Te) is higher than the upper reference value (T2), the rotation speed of the indoor fan is reduced by a predetermined rotation speed (step 109). Thereby, the heat medium temperature (Te) decreases. And the heating medium temperature (Te)
Is smaller than or equal to the upper limit reference value (T2), the process returns to Step 106, and Steps 106 to 10 are performed.
Step 9 is repeated thereafter. Thus, the heating medium temperature (T
e) is controlled to be maintained between the lower reference value (T1) and the upper reference value (T2). According to the example of Table 1, during the cooling operation, the heat medium temperature (Te) is between 4 ° C. and 7 ° C. In the range, the dehumidification temperature is maintained in the lower range of 0 ° C to 3 ° C.

Next, a procedure in which the central control unit 15 controls the indoor fan 13 with different set values of the indoor air flow according to the case of the cooling operation and the case of the dehumidifying operation will be described with reference to the flowchart of FIG. I do. When the power switch 9 of the input unit 11 is pressed, the operation mode signal is transmitted to the central control unit 15 together with the operation start signal. When detecting the input of the operation start signal, the central control unit 15 drives the air volume control fan 13 and the like via the operation control unit 14 to start the air conditioning operation (Step 200).

In steps 201 and 202, the central control unit 15 determines whether the operation mode is the cooling operation or the dehumidification operation. If it is the heating operation, the air conditioning control of the present invention is ended. The central control unit 15 determines in step 203 that the table storage unit 17
, A heating medium temperature-indoor fan speed table is called, and a predetermined increase / decrease speed (W1) of the indoor fan speed during the cooling operation is determined. If it is determined that the dehumidifying operation is being performed, a predetermined increase / decrease rotational speed (W2) of the indoor fan rotational speed during the dehumidifying operation is determined in step 204. The predetermined increase / decrease rotational speed (W1) of the indoor fan during the cooling operation is equal to the predetermined increase / decrease rotational speed (W1) during the dehumidification operation.
2) Set a larger value (W1> W2).

A predetermined increase / decrease speed (W) of the indoor fan speed
After determining (1, W2), the heat medium temperature (Te) is detected by the heat medium temperature sensor 12 in step 205.

The processing from step 206 to step 209 is the same as the processing from step 106 to step 109 described above. However, since the predetermined increase / decrease speed of the indoor fan speed is set to be larger in the cooling operation than in the dehumidifying operation, the air volume is smaller in the dehumidifying operation than in the cooling operation (slight wind). Also, there is no possibility that the sensed temperature is suddenly lowered and the comfort is impaired.

(Embodiment 2) FIG. 5 is a block diagram showing a control circuit of an air conditioner according to another embodiment of the present invention. In this control circuit, the main body control unit 15 sends information on the operating frequency of the compressor 5 controlled by the operation control unit 14 to the central control unit 15 via the operation control unit 14, and this information and the table storage unit 17 On the basis of the information of the predetermined compressor operating frequency (F) stored in advance, the timer 18 sets a predetermined time (T
Every time 1) is measured, the central control unit 15 is configured to send a control signal for increasing the opening degree (v) of the expansion valve 7 and the operating frequency (f) of the compressor 5 to the operation control unit 14. .

First, referring to the flowchart of FIG. 6, the central control unit 15 changes the compressor operating frequency (f) and the expansion valve opening (v) for a predetermined time (T2) each time a predetermined time (T1) elapses from a predetermined time. ) Will be described.

In step 400, when the power switch 9 of the input unit 11 is pressed, an operation start signal is transmitted to the central control unit 15. When the central control unit 15 detects the input of the operation start signal, the operation start signal is transmitted via the operation control unit 14. Compressor 5, expansion valve 7
And the like to start the air-conditioning operation.

In step 401, the timer 18 starts measuring time (t = t ₀ ). Next, at step 402, the operation control unit 14 detects the operation frequency (f ₀ ) of the compressor 5 and transmits the operation frequency information to the central control unit 15.
In step 403, the central control unit 15 determines whether the detected operating frequency (f ₀ ) is lower than a predetermined frequency (F) stored in the table storage unit 17 in advance. When determining the operating frequency (f ₀₎ is less than the predetermined frequency (F), the process proceeds to step 404, if the operating frequency (f ₀₎ is determined to be a predetermined frequency (F) or to step 401 Returning, the timer 18 resets the time measurement and restarts the time measurement (t = t ₀ ). Then, in step 404, the timer 18 counts time (t = t ₁ ), and in step 405, the central control unit 15 determines whether a predetermined time (T1) has elapsed since the start of timing first (T1).
≤ t _1- t ₀ ). If it is determined that the predetermined time (T1) has elapsed, the process proceeds to step 406; otherwise, the process returns to step 402 for detecting the operating frequency. By the processing from steps 401 to 405 described above, the central control unit 15 sets the operating frequency of the compressor 5 to the predetermined time (T
It is determined whether the frequency is lower than the predetermined frequency (F) over 1).

At step 406, when it is determined that the operating frequency of the compressor 5 has been lower than the predetermined frequency (F) for a predetermined time (T1), the operation control unit 14 sets the operating frequency ( f ₁ ) and the opening degree (v ₁ ) of the expansion valve 7 are detected, and the detected information is sent to the central control unit 15.

In step 407, the central control unit 15 operates the compressor 5 at a frequency (f ₁ + Δf) obtained by adding a predetermined increase frequency (Δf) to the operation frequency (f ₁ ), and also controls the expansion valve opening ( v ₁ ) with a predetermined increase opening (Δ
A control signal is sent to the operation control unit 14 so as to open the expansion valve 7 to the opening (v ₁ + Δv) to which v) is added. As described above, the refrigerating machine oil recovery operation is realized by increasing the frequency of the compressor 5 and widening the expansion valve 7.

Further, at the same time that the central control unit 15 sends this control signal to the operation control unit 14, the timer 18 counts in step 408, and in step 409, the central control unit 15 starts counting for a predetermined time (T2 ) Is determined (T2 ≦ t ₂ −t ₁ ).

If it is determined in step 409 that the predetermined time (T2) has elapsed, then in step 410, the central control unit 15
Sends a control signal to the operation control unit 14 to return the compressor 5 and the expansion valve 7 to the operation state before the oil recovery operation (f ₁ , v ₁ ). Then, the above steps 401 to 410
Is repeated, the refrigerating machine oil recovery operation can be performed for a predetermined time (T2) every predetermined time (T1).
The predetermined time (T1) is about several hours, and the predetermined time (T2) is about several minutes.

Thus, as shown in the timing chart of FIG. 7, when it is determined that the compressor 5 has continued the low frequency operation lower than the predetermined frequency (F) for the predetermined time (T1), Compressor 5 at the time of the judgment
Is controlled to a value obtained by adding a predetermined increasing frequency and an increasing opening degree (Δf, Δv) based on the operating frequency of the expansion valve 7 and the opening degree (f ₁ , v ₁ ) of the expansion valve 7. (F
_{Even if (1} , v ₁ ) is an extremely low value, the room temperature does not fluctuate extremely before and after the refrigerating machine oil recovery operation, and the refrigerating machine oil recovery operation can be performed while maintaining comfort.

[0032]

As is apparent from the above embodiment, the first aspect of the present invention is to increase or decrease the amount of indoor air at a reference temperature of a heat medium temperature different from that during the cooling operation during the dehumidifying operation. Thereby, while preventing freezing of the indoor heat exchanger 8, the sensible heat ratio can be suppressed as much as possible to sufficiently enhance the dehumidifying effect.

According to the second aspect of the present invention, the amount of indoor air that increases or decreases to prevent freezing of the indoor heat exchanger 8 during the dehumidifying operation is set to a value different from that during the cooling operation. It is possible to prevent the indoor heat exchanger from freezing while maintaining comfort without lowering the temperature.

Further, according to the third aspect of the present invention, the compressor frequency and the expansion valve opening during the refrigerating machine oil recovery operation are set to values obtained by adding a predetermined increment to those before the operation. It is possible to prevent the compressor 5 from being worn while maintaining the comfort without extremely changing the indoor temperature before and after the refrigerating machine oil recovery operation.

[Brief description of the drawings]

FIG. 1 is a schematic view of an indoor unit and an outdoor unit of an air conditioner according to an embodiment of the present invention.

FIG. 2 is a configuration block diagram illustrating a control circuit of the air conditioner according to the first embodiment of the present invention.

FIG. 3 is a flowchart showing a control method of the air conditioner.

FIG. 4 is a flowchart showing a control method of the air conditioner.

FIG. 5 is a configuration block diagram illustrating a control circuit of an air conditioner according to a second embodiment of the present invention.

FIG. 6 is a flowchart showing a control method of the air conditioner.

FIG. 7 is a timing chart showing changes over time of the compressor operating frequency and the expansion valve opening when the control method of the air conditioner is executed.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Outdoor unit, 2 ... Indoor unit, 3 ... Circulation path, 4 ... Outdoor heat exchanger, 5 ... Compressor, 6 ... Four-way valve, 7 ... Expansion valve, 8 ...
Indoor heat exchanger, 9 power switch, 10 operation mode switch, 11 input unit, 12 heat medium temperature sensor, 13
... indoor fan, 14 ... operation control unit, 15 ... central control unit,
16: body control unit, 17: table storage unit, 18: timer

Continued on the front page (72) Inventor Masaki Yamamukai 1006 Kadoma Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. (72) Inventor Shigeru Shigeru 1006 Odakadoma Kadoma, Osaka Pref. ) Inventor Fujio Teruo 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (reference) 3L060 AA01 CC04 CC08 CC19 DD02 DD05 EE04 EE05 EE09

Claims (3)

[Claims] 1. An indoor air volume control means, and a heat medium temperature detecting means arranged near a heat medium inlet of an indoor heat exchanger, wherein a heat medium temperature detected by the heat medium temperature detecting means is a predetermined value. A control device for an air conditioner that controls indoor air flow control means to adjust indoor air flow when a reference temperature is reached, wherein the reference temperature is changed between a cooling operation and a dehumidifying operation. Air conditioner control device. 2. An indoor air volume control means and a heat medium temperature detecting means arranged near a heat medium inlet of an indoor heat exchanger, wherein a heat medium temperature detected by the heat medium temperature detecting means is a predetermined value. An air conditioner control device for controlling an indoor air flow rate control means when a reference temperature is reached to adjust an indoor air flow rate, wherein an indoor air flow rate adjusted during a cooling operation is set to be larger than an indoor air flow adjusted during a dehumidification operation. A control device for an air conditioner, comprising: 3. A control device for an air conditioner including a compressor and an expansion valve, wherein the control device includes a first predetermined time (T
When the operating frequency for operating the compressor over 1) is smaller than the predetermined frequency (F), the second predetermined time (T2)
A control device for an air conditioner, wherein a frequency of a compressor is increased by a predetermined frequency and an expansion valve is opened by a predetermined opening.