JP2760226B2 - Operation control device for air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation control device of an air conditioner provided with an inverter for variably adjusting an operation frequency of a compressor, and more particularly to a measure for improving a continuous operation function.

[0002]

2. Description of the Related Art Conventionally, as an operation control device of a refrigeration system provided with an inverter for variably adjusting the operation frequency of a compressor, for example, the present applicant has filed Japanese Patent Application No.
As proposed in No. 9, when the compressor is started, the inverter frequency is accelerated at a constant acceleration rate, and when an overcurrent state of the inverter is detected, the inverter frequency is reduced, and then the inverter frequency acceleration rate is reduced. In some cases, the so-called drooping control is performed to eliminate the overcurrent state and thereby improve the reliability.

[0003]

By the way, a high current flows through an inverter module on which electric components such as a power transistor of an inverter circuit are mounted, so that the temperature tends to be high. Therefore, a radiation fin is attached to the inverter module, and the inverter module is installed in the ventilation path of the outdoor fan. In the design, care is taken to prevent abnormally high temperatures that adversely affect the quality of electrical components, and if the inverter module overheats abnormally due to poor cooling of the radiating fins due to failure of the outdoor fan, etc. Detects that condition with fin thermo,
When the fin thermometer operates, the operation of the air conditioner is stopped.

That is, as shown in FIGS. 5A to 5C, when the fin temperature Tf reaches an upper limit value (for example, a temperature of about 90 ° C.) at a certain time ta (see FIG. 5A). ,
The fin thermostat is activated (see FIG. 3B), and the inverter frequency (step value) N is set to “0”, that is, the operation of the air conditioner is stopped (see FIG. 3C). Then, after that, when the fin temperature Tf reaches a return temperature (for example, a temperature of about 80 ° C.) lower than the upper limit value (90 ° C.) at time tb (see (a) of FIG. 4), the operation of the fin thermostat is stopped. (See (b) in the figure). After that, the inverter frequency N is set to "0" as it is when the air conditioner is abnormally stopped, and is automatically controlled again to a frequency value by capacity control or the like when performing retry control.

As described above, it is considered that such an overheated state of the inverter module does not occur under normal conditions. When the inverter module is overheated, it is considered that some apparatus is abnormal. Abnormal stoppage of the air conditioner without applying inverter frequency reduction control such as technology proposed by the present applicant to the fin temperature is not so inconvenient.

However, the inverter module may be overheated even under special conditions such as the condition of the installation location of the air conditioner and the weather. For example, under special conditions, such as when the outside air temperature becomes abnormally high in the summer, the outdoor unit is installed in a place where strong solar radiation is received, or the weeds block the air suction port of the outdoor unit.

In such a case, overheating of the inverter module is often limited to a short time in a day, and in most cases, normal operation becomes possible after sunset.
Therefore, there is a problem that the comfort of the air conditioning is impaired only by abnormally stopping the operation of the air conditioner in accordance with the operation of the fin thermostat.

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing, and an object of the present invention is to detect a temperature of a radiation fin itself by a temperature sensor and to determine a predetermined temperature lower than a temperature at which the air conditioner is abnormally stopped. , The inverter frequency is reduced, thereby lowering the fin temperature and ensuring continuous operation of the air conditioner.
An object of the present invention is to maintain good air conditioning comfort.

[0009]

In order to achieve the above-mentioned object, a means according to the first aspect of the present invention, as shown in FIG. 1, is to change the operating frequency of a compressor in a ventilation path of an outdoor fan of an outdoor unit. It is assumed that the air conditioner is provided with an inverter (1) for adjusting the temperature and a radiating fin (2) for radiating heat of a power transistor and the like of the inverter (1).

As an operation control device of the air conditioner, a fin temperature sensor (Thf) attached to the radiating fin (2) for detecting a fin temperature, and receiving an output of the fin temperature sensor (Thf), Is greater than or equal to a first set value, abnormal stop control means (52) for controlling operation of the air conditioner to abnormally stop, and an output of the fin temperature sensor (Thf), and the fin temperature is set to the first set value. If the fin temperature becomes lower than the second setting value, the inverter frequency is reduced by a predetermined frequency, and then the inverter frequency is reduced by a predetermined frequency until the fin temperature becomes lower than the second setting value. And a frequency reduction control means (51) for performing control so as to reduce the noise level at a time.

As shown by the broken line in FIG. 1, the means adopted by the second aspect of the present invention is the fin temperature sensor according to the first aspect of the present invention, wherein the frequency reduction control means (51) reduces the inverter frequency. When the detected value of (Thf) becomes equal to or less than the second set value, a rise restriction control means (53) for controlling the rise of the inverter frequency to be restricted for a predetermined time is provided.

[0012]

With the above arrangement, according to the first aspect of the present invention, when the fin temperature exceeds the first set value during the normal operation of the air conditioner, the operation of the air conditioner is stopped by the abnormal stop control means (52). Although the air conditioner is stopped abnormally, there is a possibility that the air conditioning feeling is deteriorated, for example, the air conditioning is interrupted due to the abnormal stop of the air conditioner, or the air conditioner is stopped immediately even after the automatic recovery.

Here, according to the present invention, when the fin temperature becomes equal to or higher than the second set value lower than the first set value, the frequency reduction control means (51) operates until the fin temperature becomes lower than the second set value. Since the frequency of the inverter (1) is controlled so as to decrease by a constant frequency at regular intervals, the current of the electric components of the inverter circuit is reduced, and the excessive rise of the fin temperature is suppressed, and the first set value is reached. Things are avoided as much as possible. That is, the operation of the abnormal stop control means (52) is avoided, and continuous operation of the air conditioner is ensured.

According to a second aspect of the present invention, in the operation of the first aspect of the present invention, when the fin temperature becomes equal to or less than the second set value during the control by the frequency reduction control means (51), the rise restriction control means (53) controls the fin temperature. Since the rise in the inverter frequency is limited, the fin temperature is stabilized, and frequent repetition of frequency reduction control—normal control—frequency reduction control—that is, hunting of control is avoided.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

FIGS. 2 and 3 show the structure of an inverter module (1) according to an embodiment of the present invention. On a radiating fin (2), a resistance circuit component (3) such as a shunt resistor and a discharge resistor of the inverter is provided. And a diode module (4) in which the components of the diode circuit are integrated, and a power transistor module (5) in which the components of the power transistor circuit are integrated. That is, although not shown, the inverter module (1) is installed in the ventilation path of the outdoor fan in the casing of the outdoor unit of the air conditioner, and heat exchange with the outdoor air at the radiation fin (2) causes The heat generated from the electric components is radiated.

A fin temperature sensor (Thf) for detecting a fin temperature Tf is provided at the center of the surface of the radiating fin (2).
The signal of hf) is connected to the controller of the air conditioner (not shown).

FIG. 4 shows an inverter frequency (step value) N based on the fin temperature Tf performed by the controller.
FIG. 7A is a time chart showing the time change of the fin temperature Tf, and FIG. 7B is a time chart showing the time change of the inverter frequency N corresponding thereto.

The inverter frequency step value N
Is obtained by dividing the range from the lowest frequency to the highest frequency into about 20 steps at intervals of several hertz.

During operation of the air conditioner, if the fin temperature Tf exceeds a second set value Ts2 (for example, a temperature value of about 80 ° C.) while the inverter frequency is controlled in accordance with the required capacity or the like, this state is not changed. It is determined that there is a possibility that the air conditioner may be stopped abnormally, and the inverter frequency N
Is reduced by two steps corresponding to a certain frequency (time t1 in the figure), and is operated for a certain time (5 minutes),
After that, when five minutes have elapsed, the inverter frequency N is further reduced by two steps (time t2 in the figure). Then, operation is performed with this capacity for 5 minutes, and after 5 minutes, the inverter frequency N is reduced by two steps (time t3 in the figure).

On the other hand, when the inverter frequency N is reduced, the amount of heat generated by the inverter module (1) is reduced, and the fin temperature Tf is reduced to a value equal to or lower than the second set value Ts2 (time t4 in the figure). During the time (15 minutes), the inverter frequency N is maintained at or below the step value at that time, that is, the rise of the inverter frequency N is limited, and after a certain period of time, the inverter frequency N is controlled according to the required capacity. The control is switched to the normal control (time t5 in the figure).

When the fin temperature Tf becomes equal to or higher than the second set value Ts2 after switching to the normal control, the drooping control is repeated.

In addition, the fin temperature Tf rises without lowering by the drooping control, and increases to the first set value (for example, 90 ° C.).
When the temperature of the air conditioner reaches a certain temperature value, it is determined that there is some uncontrollable trouble, and the operation of the air conditioner itself is abnormally stopped.

Further, the reduction of the inverter frequency by the frequency reduction control means (51) is limited until N = 4. A further reduction in frequency significantly reduces the air-conditioning capacity, which may cause a deterioration in air-conditioning feeling. In the above time chart, when the fin temperature Tf becomes equal to or higher than the second set value Ts2, The frequency reduction control means (51) according to the present invention is configured by the control of reducing the fin temperature Tf by two steps at regular time intervals until the fin temperature Tf becomes lower than the second set value Ts2.
The control for abnormally stopping the operation of the air conditioner when the set value Ts1 is reached is achieved, and the abnormal stop control means (5
2) is configured. Further, the control for limiting the rise of the fin temperature Tf below the second set value Ts2 for a certain time after the fin temperature Tf has fallen below the second set value Ts2 constitutes a rise restriction control means (53) according to the second aspect of the present invention.

Therefore, in the above embodiment, during the normal operation of the air conditioner, the fin temperature Tf is set to the first set value Ts1.
When the temperature exceeds 90 ° C. in the above embodiment, the operation of the air conditioner is abnormally stopped by the abnormal stop control means (52). In general, the shape of the radiation fin (2) and the amount of air flow to the radiation fin (2) are designed so as not to impair the quality of electric components on the radiation fin (2). In this case, the fin temperature Tf rarely rises excessively, but for example, when the outside air temperature is abnormally high in the summer, or a special state in which weeds are growing and blocking the air inlet can occur. Under such conditions, an excessive rise in the temperature of the radiating fins (2) cannot be suppressed only by design measures, so that abnormal stoppage prevents deterioration of the quality of electric components.

[0026] However, a desired air-conditioning effect cannot be obtained, for example, when the air-conditioning apparatus is abnormally stopped, the air-conditioning is interrupted, or the air-conditioning apparatus is immediately stopped abnormally even after automatic recovery. Moreover, such an abnormal increase in the fin temperature Tf is often only during a few hours during the day, especially when the outside air temperature is high, and it is inconvenient if air conditioning cannot be continued.

Here, in the above embodiment, the fin temperature Tf
Is equal to or higher than a second set value Ts2 (80 ° C. in the above embodiment) lower than the first set value Ts1, the frequency reduction control means (51) increases the inverter frequency by a predetermined frequency (two steps in the above embodiment). After that, the inverter frequency N is reduced by a constant frequency (two steps in the above embodiment) every fixed time (5 minutes in the above embodiment) until the fin temperature Tf becomes lower than the second set value Ts2. Therefore, the current of the power transistor and the like is reduced, and an excessive rise in the fin temperature Tf is suppressed. Therefore, continuous operation of the air conditioner is secured, and comfort of air conditioning is maintained.

In this case, the cause of such an increase in the fin temperature Tf still exists. However, by performing the drooping control only once at most for several tens of minutes, the fin temperature Tf can be set to about 87 to 89 ° C. at the maximum. Will be maintained. In addition, when the time period during which the outside air temperature is particularly high during the day passes or at night, there is no possibility that the inverter module (1) will be abnormally overheated even if the normal control is performed.

In particular, when the fin temperature Tf falls below the second set value Ts2 during the control of the frequency reduction control means (51),
The inverter frequency N
, There is an advantage that frequent repetition of droop control—normal control—droop control—that is, hunting of control can be prevented.

In the above embodiment, the inverter frequency N is reduced by two steps every five minutes.
The present invention is not limited to such an embodiment. However, if the time is too short, it will be in a hunting state,
On the other hand, if the fixed time is too long, a state may occur in which the fin temperature Tf cannot be sufficiently reduced. Therefore,
Normally, it is appropriate that the fixed time is about several minutes, and the predetermined time for limiting the increase of the inverter frequency N is about 15 minutes.

Further, by providing a lower limit value (N = 4) to the inverter frequency N in the drooping control as in the above-described embodiment, it is possible to suppress deterioration of the air conditioning feeling due to extreme shortage of capacity.

[0032]

As described above, according to the first aspect of the present invention, the inverter for variably adjusting the operating frequency of the compressor and the heat of the inverter are radiated to the ventilation path of the outdoor fan of the outdoor unit. As an operation control device of an air conditioner having the heat dissipating fins,
A fin temperature sensor for detecting a fin temperature is attached, and when the fin temperature becomes equal to or higher than a first set value, the operation of the air conditioner is abnormally stopped, and when the fin temperature becomes equal to or more than a second set lower than the first set value, After the inverter frequency is reduced by a predetermined frequency and until the fin temperature becomes lower than the second set value, the inverter frequency is reduced by a fixed frequency at regular intervals, so that the fin temperature is equal to or less than the first set value. , The abnormal stop of the air conditioner can be avoided as much as possible, and the continuous operation of the air conditioner can be ensured. Therefore, the comfort of the air conditioning can be favorably maintained.

According to the second aspect of the present invention, in the first aspect of the present invention, if the fin temperature falls below the second set value during the stepwise reduction of the inverter frequency, the inverter frequency is increased for a predetermined time thereafter. Since the fin temperature is stabilized, the hunting of the control due to frequent repetition of the frequency reduction control—normal control—frequency reduction control— can be effectively prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a plan view of the inverter module according to the embodiment.

FIG. 3 is a side view of the inverter module.

FIG. 4 is a time chart showing a time change of a fin temperature and an inverter frequency in the droop control.

FIG. 5 shows a fin temperature in a conventional fin thermo control,
It is a time chart figure which shows a time change of an abnormal signal and an inverter frequency.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inverter 2 Heat radiation fin 51 Frequency reduction control means 52 Abnormal stop control means 53 Ascent limit control means Thf fin temperature sensor

──────────────────────────────────────────────────続 き Continuation of the front page (72) Kenji Miyata 1304 Kanaokacho, Sakai-shi, Osaka Daikin Industries, Ltd. Sakai Works Kanaoka Factory (56) References JP-A-60-121991 (JP, A) JP-A-4-317594 (JP, A) JP-A-3-59340 (JP, A) Japanese Utility Model Application Sho 60-129896 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F25B 1 / 00 F24F 11/02 102 F25B 49/02 560

Claims (2)

(57) [Claims] An inverter (1) for variably adjusting the operating frequency of a compressor, and a radiating fin (24) for radiating heat of a power transistor and the like of the inverter (1) in a ventilation path of an outdoor fan of the outdoor unit. 2), the fin temperature sensor (Thf) attached to the radiation fin (2) and detecting the fin temperature; and receiving the output of the fin temperature sensor (Thf) to receive the fin temperature. Is greater than or equal to a first set value, abnormal stop control means (52) for controlling the operation of the air conditioner to abnormally stop, and receiving an output of the fin temperature sensor (Thf), and setting the fin temperature to the first set value. Above the second setting lower than
Frequency reduction control means for controlling the frequency of the inverter (1) to be reduced by a predetermined frequency at regular intervals until the fin temperature becomes lower than the second set value after the frequency of the inverter (1) is reduced by the predetermined frequency. (51) An operation control device for an air conditioner, comprising: 2. The operation control device for an air conditioner according to claim 1, wherein the detected value of the fin temperature sensor (Thf) is equal to or less than a second set value while the frequency reduction control means (51) reduces the inverter frequency. Then, a rise restriction control means (53) for controlling the rise of the inverter frequency to be restricted for a predetermined time.
An operation control device for an air conditioner, comprising: