KR100270723B1 - Air conditioner - Google Patents

Abstract

The present invention relates to a heat pump type air conditioner, which is designed to reduce power consumption and improve comfort during heating by executing defrosting operation at an appropriate time regardless of outside temperature or compressor rotation speed. If the defrosting time has elapsed, set the defrosting prohibition time not to perform defrosting operation after the start of heating operation or the end of defrosting operation. The defrosting operation is performed when the detected temperature of the outdoor heat exchanger drops below the set defrosting start outdoor heat exchanger temperature.

By doing so, the defrosting prohibition time is changed in accordance with the outside air temperature and the defrosting start outdoor heat exchanger temperature is changed in accordance with the outside air temperature and the number of revolutions of the compressor. It is effective in improving comfort by reducing the temperature and preventing room temperature decrease.

Description

Air conditioner

TECHNICAL FIELD The present invention relates to a heat pump type air conditioner, and more particularly, to defrost control of an outdoor heat exchanger during heating operation.

In recent years, air-conditioning room air conditioners are required to have a better heating capacity during heating. One of the causes of the deterioration of the heating capacity during heating is the state in which the temperature of the outdoor heat exchanger installed in the outdoor unit and acting as an evaporator during heating decreases, and moisture in the air adheres to the outdoor heat exchanger and freezes. And defrost control, which is a control for releasing the implanted state. In this defrost control, the flow of the refrigerant in the refrigerating cycle is reversed from heating, and the high-temperature, high-pressure gas refrigerant discharged from the compressor is introduced into an outdoor heat exchanger with frost to melt frost. During the defrost control period, the indoor heat exchanger flows into the indoor heat exchanger via an expansion valve, so that the refrigerant in a low-temperature, low-pressure two-phase flow state flows in, thereby stopping the indoor fan to prevent the room temperature from dropping. That is, there is a problem in that the room can not be heated during the defrost operation period. Therefore, it is necessary not to intrude into defrost operation unintentionally.

By the way, in order to prevent the frost from entering the defrost operation even though the frost is not attached, the start timing of the defrost operation is identified by attaching a frost sensor to the outdoor heat exchanger and grasping the frost attachment situation where the heating capacity decreases at a predetermined rate. Although it is considered to determine the performance of the frost sensor, it can be adopted in terms of performance and price. In addition, although it is also conceivable for the user to visually recognize the frost attachment situation and start the defrost operation manually, it is very inconvenient.

In addition, the reason for performing the defrost control is that the heating capacity due to frost (the difference in the refrigerant suction temperature and the discharge temperature of the indoor unit can be calculated by integrating the rotation speed of the compressor of the outdoor unit by integrating the specific heat of the refrigerant and the refrigerant density. It is also possible to consider the construction of a control system that monitors the heating capacity of the air conditioner sequentially and starts the defrost operation when the capacity decreases by a predetermined ratio, since the recovery of the lowering (lower capacity of the outdoor heat exchanger) is restored. However, the heating capacity of an air conditioner depends on other factors, such as a decrease in the number of revolutions of an indoor fan, for example, and it is difficult to establish a control system that uniquely derives that this decrease is caused by frost. There was a problem.

However, if frost adheres to the outdoor heat exchanger, the heat transfer rate on the fin surface decreases and the endothermic amount decreases, so that the refrigerant does not sufficiently evaporate and the gas liquid mixed refrigerant is directed to the compressor inlet. For this reason, the gas liquid mixed refrigerant is sucked into the compressor and the liquid refrigerant evaporates at the cylinder inlet part, so that the temperature is lowered, and as a result, the outlet refrigerant temperature of the compressor is also lowered. When the sensor detects that the compressor discharge temperature has dropped, the control system tightens the expansion valve to return to its original state. When the expansion valve is tightened, the compressor suction pressure decreases, and the temperature of the outdoor heat exchanger decreases. It is known to perform defrost operation by judging that it is with frost by sensing the fall of the temperature of this outdoor heat exchanger. For example, in the examples described in Japanese Patent Laid-Open No. 55-160248 and Japanese Patent Laid-Open No. 61-153332, the defrost is performed when the difference between the outdoor heat exchanger temperature and the outside air temperature becomes a certain value or more.

In the case of performing the defrost control by detecting the temperature of the outdoor heat exchanger in this way, for example, when the number of revolutions of the compressor is increased in response to a control request, the pressure difference before and after the compressor increases, so that the pressure of the outdoor heat exchanger decreases and the outdoor heat exchanger temperature is reduced. Even if the amount of frost is reduced, the defrosting operation may be started even though the frost attachment amount is small, and when the airflow of the indoor fan is increased, the condensation cloud is lowered due to the increase of the capacity of the indoor heat exchanger and the pressure of the indoor heat exchanger. The lowering of the expansion valve also lowers the temperature of the outdoor heat exchanger, and the defrosting operation may be started even though the amount of frost deposition is small.

To solve this problem, Japanese Patent Laid-Open No. 60-169038 describes the provision of a defrost prohibit timer to prohibit the unnecessary defrost operation.

In the above prior art, when the setting time of the timer is short, the number of times to enter the defrost operation increases, resulting in a decrease in the heating capacity, and thus there is a problem that the setting of the time is difficult. In addition, the start timing during the defrost operation also depends on the accuracy of the temperature sensor attached to the outdoor heat exchanger.

In addition, when the determination of the defrost operation is performed in accordance with the difference between the outside air temperature and the outdoor heat exchanger temperature, accurate determination cannot be made when the outside temperature detector and the outdoor heat exchanger are thermally connected due to snow or frost growth. There is a problem.

It is a first object of the present invention to provide an air conditioner capable of eliminating unnecessary defrost operation.

A second object of the present invention is to provide an air conditioner capable of determining the start timing of the defrost operation without being influenced by the accuracy of the temperature sensor attached to the outdoor heat exchanger.

Further, a third object of the present invention is to provide an air conditioner capable of determining the defrost operation even when the outside temperature detector is thermally connected to the outdoor heat exchanger.

1 is a diagram showing the configuration of an air conditioner according to an embodiment of the present invention.

2 is a diagram showing an algorithm of defrost control of the present invention.

3 is a diagram showing the relationship between the outside air temperature and the defrost prohibition time in the defrost control.

4 is a view showing the relationship between the outside air temperature and the defrost start outdoor heat exchanger temperature in the defrost control of the present invention.

5 is a diagram showing the relationship between the compressor rotation speed and the defrost start outdoor heat exchanger temperature in the defrost control of the present invention.

6 is a diagram showing the configuration of an air conditioner according to a second embodiment of the present invention.

7 shows an algorithm of defrost control of the second embodiment.

Fig. 8 is a diagram showing an algorithm of defrost control in the third embodiment of the present invention.

Fig. 9 is a diagram showing an algorithm of defrost control in the fourth embodiment of the present invention.

Fig. 10 is a diagram showing an algorithm of defrost control in the fifth embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

1: compressor 2: indoor heat exchanger

3: expansion mechanism 4: outdoor heat exchanger

5: four-way valve 6: outdoor heat exchanger temperature sensor

7: outside temperature sensor 8: control device

13: speed sensor

The first object is a compressor, an indoor heat exchanger connected to the compressor, an outdoor heat exchanger connected to the indoor heat exchanger via a decompression means, an outdoor heat exchanger temperature detection means for detecting a temperature of the outdoor heat exchanger, and in the compressor When the discharged refrigerant flows through in order of the indoor heat exchanger and the outdoor heat exchanger, the refrigerant flow direction is reversed in accordance with the output of the outdoor heat exchanger temperature detection means during the operation of suctioning the refrigerant to the compressor. A reverse rotation command generation means for generating a command, an outside temperature detection means for detecting an outside air temperature, a timekeeping means for indicating a set time that changes according to the outside air temperature, and when the set time has elapsed and the reverse rotation command is generated It is achieved by providing means for reverse rotation of the refrigerant flow direction.

The second object is a compressor, an indoor heat exchanger connected to the compressor, an outdoor heat exchanger connected to the indoor heat exchanger via a decompression means, an outdoor heat exchanger temperature detection means for detecting a temperature of the outdoor heat exchanger, and the The output of the outdoor heat exchanger temperature detection means and the output of the outdoor heat exchanger temperature detection means after the set time has elapsed during the operation of flowing the refrigerant discharged from the compressor into the indoor heat exchanger and the outdoor heat exchanger in order to suck the refrigerant. It is achieved by providing means for reversing the refrigerant flow direction when the difference in output becomes larger than the set value.

The third object is a compressor, an indoor heat exchanger connected to the compressor, an outdoor heat exchanger connected to the indoor heat exchanger via a decompression means, an outdoor heat exchanger temperature detection means for detecting a temperature of the outdoor heat exchanger, The outdoor heat exchanger is provided at a position close to the outdoor heat exchanger and detects the outside air temperature and the refrigerant discharged from the compressor flows in the order of the indoor heat exchanger and the outdoor heat exchanger and sucks the compressor to the compressor. And a means for reversely rotating the refrigerant flow direction when the difference between the output of the air temperature detecting means and the output of the outside air temperature detecting means becomes smaller than a set value.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated by the Example shown in drawing. 1 is a diagram showing the outline of the configuration of the air conditioner of Embodiment 1 (First Embodiment) of the present invention. During the heating operation, the compressor 1, the indoor heat exchanger 2, the expansion mechanism 3, which is a pressure reducing means such as an electric expansion valve, the outdoor heat exchanger 4 and the four-way valve 5 are sequentially connected by refrigerant piping. A refrigeration cycle is constructed. The control device 8 is equipped with a microcomputer, and controls the compressor 1, the indoor fan 11, the outdoor fan 12, the electric expansion valve 3, the four-way valve 5 and the like. The number of revolutions of the compressor 1 can be controlled by the inverter 9, and the controller 8 controls the frequency to the inverter 9 in accordance with the intake air temperature detected by the intake air temperature sensor 10 and the like. Print the command.

In the heating operation, the four-way valve 5 maintains the connected state indicated by the solid line in FIG. 1, and the coolant flows in the direction of the arrow in the solid line in FIG. 1 to form a heating cycle. In the defrost operation, the four-way valve is switched to the dotted line connection state, the refrigerant flows in the direction of the dotted line arrow to form a cooling cycle, and the indoor blower 11 and the outdoor blower 12 are decelerated or stopped. The outdoor heat exchanger temperature sensor 6 is attached to the refrigerant pipe of the outdoor heat exchanger 4 and detects the refrigerant temperature of the outdoor heat exchanger 4. In addition, the outside air temperature of the outside air temperature sensor 7 attached to the intake side of the outdoor heat exchanger 4 is detected. The controller 8 is an outdoor heat exchanger temperature which is a temperature detected by the outdoor heat exchanger temperature sensor 6, an outdoor air temperature which is a temperature detected by the outside air temperature sensor 7, and a compressor (1) detected by the rotation speed sensor 13. Decide on the start of the defrost operation according to the number of revolutions. Instead of detecting the rotation speed of the compressor 1, the command value of the compressor rotation speed of the control device may be used.

The algorithm of defrost control is shown in FIG. In step 101, the microcomputer possessed by the control device 8 reads the outside temperature T _o , and in step 102 calculates the defrost prohibition time tau _dc corresponding to the outside temperature T _o by the following equation. Defrost operation is not executed until the defrost prohibition time has elapsed.

[Equation 1]

τ _dc = AT _O + B

A and B in the above formulas are appropriate integers, and A < An upper limit value and a lower limit value are provided for the defrosting prohibition time. If the value of Equation 1 exceeds the upper limit value, the defrost prohibition time is the upper limit value. If the value of Equation 1 is less than the lower limit value, the defrost prohibition time is the lower limit value. .

In step 103, the defrost prohibition time timer provided in the control device 8 is started (operated). The control device 8 is a sensor 7 the outdoor temperature T _o, the outdoor heat exchanger temperature sensor 6, the outdoor heat exchanger T _o and a rotational speed sensor 13 is detected by the detection by the outside temperature in step 104 The compressor rotation speed N detected by the lead is read. Instead of the compressor rotation speed, a frequency detection circuit may be provided in the inverter and the frequency may be used. It may also be an inverter frequency command value. Next, the outdoor heat exchanger temperature (defrost start outdoor heat exchanger temperature) T _ed at the start of defrost is calculated by the following equation (2) (step 105).

[Equation 2]

T _ed = _{aT o} + bN + c

Where a, b, and c are integers and a > 0 and b <

T _ed is greater than when the value of the couple of Formula 2 provided the upper and lower limits the upper limit value or below the upper limit, and lower limit value are to a lower limit value. For compressor rotation speed, outdoor heat exchanger temperature, and outside temperature, it is better to perform the calculation of Equation 2 using several sampling averages to avoid the effects of temporary or sudden fluctuations. There is also a method of validating their data only when several sampling values fall within a certain range.

Next, in step 106, it is determined whether or not the value τ of the defrost prohibition time timer has passed a predetermined time τ _dc (defrost prohibition time). If the predetermined time has elapsed, the outdoor heat exchanger temperature T _e is increased in step 107. Determines whether or not it has fallen below T _ed . When the outdoor heat exchanger temperature decreases as the frost is attached to the outdoor heat exchanger, and if the outdoor heat exchanger temperature T _e falls below T _ed , in step 108, the four-way valve 5 is switched from the heating cycle to the cooling cycle, and the defrost operation is performed. Plunge into In step 109, the defrost operation time timer is started, and in step 110, if the defrost operation time tau _df exceeds the predetermined time tau _dfmax , the defrost operation is terminated (step 112). That is, the four-way valve is switched to heating operation. In addition, the τ _df the end the predetermined time defrosting operation, even if increased, even if they are not exceeding the _dfmax τ at the step 111 is also the outdoor heat exchanger temperature T _e above T _eh. T _eh may be changed by the outdoor heat exchanger temperature or the outside air temperature at the start of defrosting. If the defrost operation is completed, the defrost operation time timer is reset (step 113), and the defrost prohibition time timer is also reset (step 114).

3 shows the relationship between the outside air temperature and the defrost prohibition time in the defrost control of this embodiment. When the outside temperature is low, the absolute humidity of the outside air is low, so the defrosting interval or the defrosting time is set long. On the contrary, when the outside temperature is high, the dehumidifying time is short because the absolute humidity of the outside air is high. In addition, the upper limit value and the lower limit value are provided in the defrost prohibition time. If the upper limit value is provided, if it is stopped by a power failure or the like when the conception proceeds and there is a lot of frost, and restarted immediately, the timer is reset and the clock is started again. This is to prevent the ability from significantly deteriorating. The lower limit value is, for example, when the lower limit value is 0, as described above, the start timing of the defrost operation by the outdoor heat exchanger temperature is prioritized, and thus the unexpected defrost operation is started. In other words, if the outside temperature sensor is unable to measure the outside air temperature normally and measures to a higher temperature than the original outside temperature, for example, the outside air temperature is low, If there is an outside air temperature sensor, it is to prevent the defrosting operation from being performed at all because it is mis-measured as a very high temperature where it is heated by sunlight and no implantation occurs. In addition, even when the external air temperature sensor is implanted, the external air temperature sensor does not operate normally, resulting in an error in output, but it is possible to avoid that the defrost operation is not performed at all.

This upper limit is set to 70 minutes at a temperature of -5 DEG C or lower, and the lower limit to 45 minutes at a temperature of 0 DEG C or higher. In addition, the slope of the prohibition time with respect to the outside temperature between the upper limit value and the lower limit value shown in FIG. 3 starts heating operation under the conditions most likely to be assumed, namely, humidity of 90% and compressor rotational speed of 8000 rpm (heating capacity 100). The prohibition time until the heating capacity drops to 88% in%) is calculated by connecting each outside temperature with a line. In general, however, there are few operations under such conditions, so in most cases, the prohibition time elapses (times up) before defrosting is required, and then a defrost operation start command is issued due to a decrease in the outdoor heat exchanger temperature. Defrost operation is started. In addition, if the temperature of the outdoor heat exchanger suddenly decreases for some reason, or if it is judged that the temperature has decreased due to the error of the output of the outdoor heat exchanger temperature sensor, the defrost operation start command is immediately issued. By setting the lower limit, the defrosting operation can be prevented from starting even though it is not conceived.

In addition, although the prohibition time was computed by the outdoor air temperature in the said Example, the same effect can be acquired even if it uses the outdoor air humidity and the outdoor air temperature and the outdoor air humidity.

In the embodiment shown in FIG. 2, after the frost removal prohibition time has elapsed in step 106, it is determined whether or not defrost is started according to the outdoor heat exchanger temperature in step 107. The same effect can be obtained by determining whether the defrosting prohibition time has elapsed when it is necessary to judge the presence or absence of the defrosting. The same applies to the embodiments described below.

Next, the defrost start condition in the defrost control of this embodiment will be described. Fig. 4 shows the relationship between the outside air temperature T _o and the defrosting start outdoor heat exchanger temperature T _{ed using} the compressor rotation speed N as a parameter. 5 shows the relationship between the compressor rotation speed N and the defrosting start outdoor heat exchanger T _{ed using} the outside temperature T _o as a parameter. 4 and 5 show Equation 2 described above in the drawings. The method of claim 4 _{also, N 1, N 2, N} 3 represents the number of revolutions of another compressor, a N ₁ <N ₂ <N _3. In FIG. 4, only three types of rotation speed are shown for convenience. In practice, the rotation speed changes much finer, but the same considerations apply. In FIG. 5, T _o1 , T _o2 , and T _o3 represent different outside temperatures and are T _o1 > T _o2 > T _o3 . In FIG. 5, only three types of outside air temperature are shown for convenience. In practice, the outside temperature changes continuously, but the method of consideration is the same. The defrost operation is performed when the outdoor heat exchanger temperature falls below the solid line (control line) corresponding to each condition in FIG. 4 or FIG. As shown in FIG. 4, the lower the outside air temperature, the lower the start of defrosting the outdoor heat exchanger temperature, and the higher the outside air temperature, the higher the defrosting start the outdoor heat exchanger temperature is set. This is because the lower the outside temperature, the lower the evaporation temperature of the refrigerant is. Even if the outside temperature is lower, the defrosting operation is carried out in the low defrosting period unless the external heat exchanger temperature is lowered. This is because a decrease in consumption and comfort occurs. On the contrary, when the outside temperature is high, the evaporation temperature of the refrigerant is high, so if defrosting is not performed at a high outdoor heat exchanger temperature, the amount of frosting becomes excessive and the defrosting operation takes time, resulting in an increase in power consumption or a decrease in indoor temperature. Because it is caused. In addition, as shown in FIG. 5, the higher the rotational speed of the compressor is, the lower the outdoor heat exchanger temperature at the start of defrosting, and the lower the rotational speed of the compressor is, the higher the outdoor heat exchanger temperature is at the start of defrosting. This is because when the outside temperature is the same, even if the same amount of frosting, the evaporation temperature of the refrigerant is lower as the number of rotations is higher. This is because unpleasantness is caused by unnecessary power consumption and a decrease in room temperature. On the contrary, when the number of revolutions of the compressor is low, the evaporation temperature of the refrigerant is high, and if the defrosting is not performed at a high outdoor heat exchanger temperature, the amount of frosting becomes excessive and the defrosting operation takes a long time, resulting in an increase in power consumption or room temperature. This is because it causes a decrease.

Further, in the fourth diagram, when the outdoor heat exchanger temperature is also disclosed remove frost has appointed the upper and lower limits, the value of T is less than T _{e1 e1 ed} lower limit value T, as shown in, and when the upper limit value T _e2 or more was as T _e2. The reason why the upper limit is provided is that no frosting occurs when the outdoor heat exchanger temperature exceeds a certain temperature. The reason why the lower limit is provided is that if the outdoor heat exchanger temperature is lower than a certain temperature, it is more likely to be carried out, and even if the outdoor air temperature sensor is not working normally, When the outdoor heat exchanger temperature is lowered to the lower limit by the defrosting operation, the defrosting operation is not performed at all, and thus the heating capacity can be remarkably lowered. That is, the upper limit value is if the compressor rotational speed N ₃ of the case when the outside temperature over 5 ℃, the N ₁ is an outdoor heat exchanger temperature is also set to at least 2 ℃ -4 ℃, and the lower limit value is set to the number of revolutions N ₁ Compressor the outside temperature The temperature of the outdoor heat exchanger is set to -19 ° C at -10 ° C or less and N ₃ at -7 ° C or less.

In a situation where the snow is falling in large quantities, when the position of the outside air temperature sensor is close to the outdoor heat exchanger, snow or frost accumulates between the outside air temperature sensor and the outdoor heat exchanger, and heat transfer is performed through the snow or frost. Close to the outdoor heat exchanger temperature may occur. In such a case, even if the outside temperature is detected lower than the actual temperature due to the heat conduction from the outside temperature sensor to the outdoor heat exchanger, it may not enter the defrost operation even if the outdoor heat exchanger is placed in a large amount. In order to avoid this, when outside temperature T _o and the outdoor heat exchange temperature is also the difference between the T _e it is less than a certain value dT that is,

[Equation 3]

T _o -Te <dT (dT is an integer)

When is established, the defrosting operation is executed after a predetermined time (after defrosting time) τ _dc after the start of operation or after a predetermined time (after frost removing time) τ _dc after the end of the defrosting operation. The constant value dT may be a set value of about 2 to 3 ° C. Outside temperature during the defrost prohibition time elapses even T _o and the outdoor heat exchanger temperature even without the use of outside temperature when the difference between T _e is less than a certain predetermined value dT, if the outdoor heat temperature also decreases below a certain temperature of the defrosting operation You may switch to. Instead of using the difference between the outside air temperature and the outdoor heat exchanger temperature, the amount of decrease within a predetermined time of the outside air temperature may be used. When the outside air temperature is lowered by a predetermined amount within a predetermined time, it is determined that frost is attached between the outside air temperature sensor and the outdoor heat exchanger, and the defrost operation is executed.

By performing the defrost control as described above, no defrosting operation is started or excessively landed in the outdoor heat exchanger. Therefore, unnecessary power consumption or room temperature decrease, resulting in a loss of comfort. none. Even if the detection error of outdoor heat exchanger temperature is large, the defrosting prohibition time that does not perform the minimum defrosting operation is changed according to the outside temperature, so unnecessary defrosting operation can be avoided, unnecessary power consumption or room temperature decreases. The comfort can be prevented. In addition, even when snow or frost is clogged between the outside air temperature sensor and the outdoor heat exchanger, the defrosting operation can be performed properly, so that the heating capacity is not significantly reduced.

Since the rotational speed of the compressor varies depending on various factors, it is difficult to determine which rotational speed of the compressor is to be introduced after defrosting or starting of heating operation. Therefore, although the rotation speed of the compressor cannot be controlled and only the outside air temperature and the outdoor heat exchanger can be used, at this time, the lower the outside air temperature, the higher the rotation speed of the compressor is to perform the control as indicated by the dashed-dotted line in FIG. The effect similar to the case where the rotation speed of a compressor is introduced by this can be acquired. In this case, although the control line is shown by a straight line in FIG. 4, the effect can be further improved by using a broken line or another curve. Also in the embodiments described below, it is not necessary to introduce an element of the compressor rotational speed.

According to the present embodiment, the lower the ambient temperature, the lower the absolute humidity even at the same relative humidity. Therefore, in addition to judging the idea by the temperature of the outdoor heat exchanger by using the slowing the idea of the rate of heating to the outdoor heat exchanger during heating. If the outside temperature is lowered and the frost removal prohibition time is extended, defrosting is not performed during the minimum time without defrosting, so the detection error of the outdoor heat exchanger temperature sensor becomes large or a deviation occurs in the attachment state. In addition, unnecessary defrosting operation can be avoided, so that unnecessary power consumption or room temperature decreases, and the comfort is not impaired.

In addition, by changing the frost removal prohibition time according to the outside temperature, the minimum frost removal time is not only ensured even when the detection error of the outdoor heat exchanger temperature sensor becomes large or the attachment state is bad. Since the outdoor heat exchanger temperature at the time of starting defrost is determined by the number of revolutions, defrost operation is executed at a more appropriate timing. Moreover, since the upper limit is provided in the outdoor heat exchanger temperature which starts defrost, when the surface temperature of a heat exchanger is high and frost does not adhere, defrost operation is not performed. In addition, since a lower limit is provided at the outdoor heat exchanger temperature at which defrosting is started, for example, even when snow accumulates between the outdoor air temperature sensor and the outdoor heat exchanger that is snowing, and the outdoor air temperature is not accurately detected, some degree of conception is achieved. Since the defrosting operation is carried out in the quantity, the heating capacity does not significantly decrease.

In addition, since the upper limit value and the lower limit value are provided during the defrosting prohibition time, even if the vehicle is stopped and restarted immediately due to a power failure or the like, the outdoor heat exchanger is excessively implanted, resulting in no significant drop in heating capacity. In addition, even when the outside temperature sensor is not operating normally, for example, when the outside air temperature sensor is installed, the defrosting operation is not performed at all.

The defrosting operation is also performed when the difference between the outside air temperature and the outdoor heat exchanger temperature is equal to or less than a predetermined value. For example, since it is snowing and snow can accumulate between an outside air temperature sensor and an outdoor heat exchanger as mentioned above, an outside air temperature cannot be detected correctly, defrosting operation is performed suitably also in such a case.

6 shows a configuration of an air conditioner according to another embodiment (second embodiment) of the present invention. In this embodiment, outside air humidity sensor 14 is provided in addition to the configuration of the first embodiment. Since other configurations are the same as those in the first embodiment, the description is omitted. 7 shows the defrost control algorithm of this embodiment. In step 202, the microcomputer possessed by the controller 8 leads to the outside air temperature T _o , the outdoor heat exchanger temperature _Te , the compressor rotation speed N and the outside air humidity RH _o . Next, the outdoor heat exchanger temperature (defrost start outdoor heat exchanger temperature) T _ed at the start of the defrost operation is calculated by the following equation (4) (step 203).

[Equation 4]

_{T ed = a · T o +} b · N + c · RH o + d

Here, a, b, c, and d are integers, and a> 0, b> 0, c> 0.

The higher the outside air humidity is, the higher the outdoor heat exchanger temperature is to perform the defrost operation (ie c> 0). This is because the higher the outside humidity, the larger the amount of implantation and the higher the evaporation temperature. Similarly to the first embodiment, T _ed is provided with an upper limit value and a lower limit value.

Step 204 in determining whether or not the lapse of the defrost prohibition time, and cooling cycle switch the outdoor heat exchanger temperature is also T _e has descended below the T _ed side four-way valve in step 205. In the heating cycle (step 206) Frost Enter the removal operation. The following parts are the same as in the first embodiment.

In the case where the outside temperature sensor is provided, the defrosting prohibition time during which the defrosting operation is not performed after the start of heating operation or immediately after the end of the defrosting operation may be changed by the outside humidity. For example, the defrost prohibition time tau _dc is set by the following equation.

[Equation 5]

τ _dc = (A · T _o2 + B · T _o + C) · RH _o + D

Here, T _o is outside temperature, RH _o is the ambient relative humidity, A, B, C, D are constant.

In this embodiment, the influence of the outside air humidity in addition to the outside air temperature, the compressor rotation speed, and the outdoor heat exchanger temperature is used for the determination of the defrosting start, so that a more precise idea of detection can be detected, thus reducing power consumption and comfort during heating. Has a great effect on the improvement.

8 shows an algorithm of defrost control in still another embodiment (third embodiment). The structure of this embodiment is the same as that of the first embodiment (FIG. 1). In FIG. 8, the outside air temperature T _o , the outdoor heat exchanger temperature T _e , and the compressor rotation speed N in step 032 are read. In step 303, when the elapsed time τ is an arbitrary set time τ _s , the outside air temperature and Remember the compressor speed. τ _s is shorter than the defrosting prohibition time and is set to 10 to 20 minutes as a time when the heating capacity is close to the peak. At this time, the outside air temperature is T _o1 and the compressor rotation speed is N ₁ . If the defrost prohibition time has elapsed in step 305, the defrost start outdoor heat exchanger temperature is calculated by the following formula (6) in step 306.

[Equation 6]

T _ed = _{aT o} + bN + c + d D T _o + e D

△ T _o = T _o -T _o1

△ N = NN ₁

Here, a, b, c, d and e are integers, and a> 0 and b <0.

In the defrosting start outdoor heat exchanger temperature, the first terms a to T _o to the third c of the right side in the formula (6) are the same as in the first embodiment. The fourth term d · ΔT _{o on the} right side is a correction term of the outdoor heat exchanger temperature at the start of defrosting due to the change of the outside air temperature. When the outside air temperature changes, the speed of conception changes so that its influence is corrected. Claim 5e.ΔN is a correction term for the defrosting start of the outdoor heat exchanger temperature caused by the change of the rotational speed of the compressor. When the rotational speed of the compressor changes, the speed of conception also changes, so that its influence is corrected. Of claim 4 wherein d · △ T _o or 5 e · only either one may be added in the △ N. In addition, the same correction term can be added to the second and third embodiments. Here, after the start of the heating operation or the end of the defrosting operation, the correction was performed using the outside air temperature at a predetermined time τ _s and the number of revolutions of the compressor, but when the deviation of the measured value is taken into consideration, the value sampled several times since τ _{s has} elapsed. The average value of is good. In addition, the calculation of Equation 6 may be performed using the average value of several times of sampling to avoid the influence of temporary or sudden fluctuations on the rotational speed of the compressor, the outdoor heat exchanger temperature, and the outside temperature at the time of the defrost start determination. In addition, almost the same effect can be expected even if the correction by the rotation speed of the compressor is left, leaving only the correction of the outside temperature.

According to the present embodiment, the defrosting operation is performed at the defrosting start outdoor heat exchanger temperature, which becomes a more appropriate implantation amount even when the outside air temperature or the compressor rotational speed is greatly changed, so that the power consumption is further reduced and the room temperature at the defrosting operation is further reduced. A fall can be suppressed and a comfort is improved.

In the present embodiment, as in the first embodiment, the defrosting prohibition time is provided to change the defrosting prohibition time by the outside temperature, thereby ensuring the minimum defrosting operation interval even when the detection error of the outdoor heat exchanger temperature is large. This can avoid the deterioration of comfort caused by frequent defrost operation.

According to this embodiment, the outside air temperature and the number of revolutions of the compressor when the predetermined time has elapsed after the start of the heating operation or the end of the defrost operation are stored in the controller, and the outdoor heat exchanger temperature when the defrost is started after the start of the heating operation or the frost is started. After a certain time has elapsed since the end of the removal operation, the difference between the outside temperature at the determination of the defrost start and after the start of the heating operation or after a certain time has elapsed after the end of the defrost operation, To correct. This correction makes it possible to properly compensate for the influence of the change in the frosting speed of the outdoor heat exchanger even when the outside air temperature is greatly changed or when the rotation speed of the compressor is greatly changed. Power is reduced and comfort during heating is improved.

9 shows an algorithm of defrost control in still another embodiment (fourth embodiment). The structure of the apparatus of this embodiment is the same as that of the first embodiment (FIG. 1).

In the defrosting control of this embodiment, the defrosting start is determined based on the amount of change in the outdoor heat exchanger temperature since a certain time has elapsed after the start of the heating operation or the end of the defrosting operation.

In step 402 of FIG. 9, the outside temperature T _o , the outdoor heat exchanger temperature _Te and the compressor rotation speed N are read, and in step 403, the elapsed time τ after the start of operation or immediately before the defrost operation is terminated is a predetermined time τ. When it becomes _s , in step 404, the outdoor heat exchanger temperature, the outside air temperature, and the rotation speed of the compressor are stored. τ _s is a time shorter than the defrosting prohibition time and the heating capacity is close to the peak, and is set to 10 to 20 minutes. The outdoor heat exchanger temperature at this time is T _e1 , the outside temperature is T _o1 , and the compressor rotation speed is N ₁ . When the defrosting prohibition time has elapsed in step 405, the defrosting start outdoor heat exchanger temperature change amount? T _ed is calculated by the following equation (7) in step 406.

[Equation 7]

ΔT _ed = _{aT O} + b D N + c

△ T _o = T _o -T _o1

△ N = NN ₁

Here, a, b, and c are integers.

In the calculation formula of ΔT _ed , the right side term 1a · ΔT _o is a term due to a change in the outside air temperature, and thus, the rate of conception changes when the outside air temperature changes, and thus its influence is shown. Claim 2b * (DELTA) N is a term | item by the change of the rotation speed of a compressor, and when the rotation speed of a compressor changes, since the speed of conception changes, it shows the influence. If the outdoor heat exchanger temperature change amount? T _e = T _e = T _e1 is equal to or less than? T _{ed in} step 407, the four-way valve is switched from the heating cycle to the cooling cycle in step 408, and the frost removal operation is started. Note that the sign of the outdoor heat exchanger temperature change amount ΔT _e is negative and the smaller this value is, the larger the absolute value of the change amount is. Since the following procedure is the same as that of 1st Example, description is abbreviate | omitted. Here, when considering the variation in the heating operation start or the defrosting operation ends after a predetermined time τ _s elapsed when the temperature of outside air assist compressor rotational speed by using, but executing the calculation of equation 7, the measured value, the number of times sampling from the time of τ _s elapsed Use the average of the values. In addition, in order to avoid the influence of temporary or sudden fluctuations on the compressor rotation speed, the outdoor heat exchanger temperature, and the outside temperature at the time of the defrosting start determination, it is preferable to calculate the equation (7) using the average value of several samplings.

According to this embodiment, since the influence of the change in the outside air temperature and the compressor rotational speed is considered in the determination using the temperature decrease of the outdoor heat exchanger, the defrosting operation is performed at the start of the defrosting of the outdoor heat exchanger temperature, which is an appropriate amount of implantation. The reduction in power consumption and defrost operation are effective in improving the comfort by preventing the lowering of the room temperature. In addition, in this embodiment, the defrost determination is executed by using the change amount of the outdoor heat exchanger temperature. Therefore, even if there is a deviation (nonuniformity) in the attachment state of the outdoor heat exchanger temperature sensor or the detection error of the outdoor heat exchanger temperature sensor is large. The error due to temperature change is small and defrosting is performed properly. In addition, since the change amount is also used for the outside air temperature and the compressor rotation speed, the error of the absolute value is canceled and the accuracy is improved. Moreover, even if the model is changed by using the change amount of the outdoor heat exchanger temperature, there is an advantage that it is not necessary to change the parameter of the defrost start determination condition, or even a slight change may be sufficient.

Also in this embodiment, as in the first embodiment, by providing a defrosting prohibition time and changing the defrosting prohibition time by the outside temperature, the minimum defrosting operation interval is ensured even when the detection error of the outdoor heat exchanger temperature is large. It is possible to avoid the deterioration of comfort caused by frequent defrost operation.

According to the present embodiment, the control device stores the outdoor heat exchanger temperature, the outside air temperature, and the compressor rotation speed set by the control device when a predetermined time has elapsed after the start of the heating operation or the end of the defrost operation at the time of heating operation. Defrost operation should be executed when the amount of change in outdoor heat exchanger temperature from the start of defrosting start or after the end of defrost operation is over the set value of defrost start outdoor heat exchanger temperature. At this time, the amount of change in the outdoor heat exchanger temperature at the start of defrost is the change in the outside temperature from the time after the start of the heating operation or the end of the defrost operation to the determination of the start of the defrost and the end of the defrost operation. According to the amount of change in the number of revolutions of the compressor from a certain time after Although the defrosting start is judged using the change amounts of the outdoor heat exchanger temperature, the compressor rotation speed, and the outside temperature in this way, the influence of the error of the absolute value of the sensor is avoided and the defrosting start is performed with high precision. You can decide when.

Fig. 10 shows an algorithm of defrost control in another embodiment (embodiment of Fig. 5). The structure of the apparatus of this embodiment is the same as that of the first embodiment (FIG. 1). In the defrost control of the present embodiment, as in the fourth embodiment, the defrost start is determined by the amount of change in the outdoor heat exchanger temperature after a certain time has elapsed after the start of the heating operation or the end of the defrost operation. 10, the outdoor air temperature T _o , the outdoor heat exchanger temperature T _e , and the compressor rotation speed N are read in step 502, and the outdoor heat exchanger temperature in step 504 when the elapsed time τ is any set time τ _{s in} step 503. Remember the temperature and the outside temperature and the compressor speed. The time τ _s is shorter than the defrost prohibition time and sets when the heating capacity is close to the peak. The outdoor heat exchanger temperature at this time is T _e1 , the outside temperature is T _o1 , and the compressor rotation speed is N ₁ . If the defrosting prohibition time has elapsed in step 505, the defrosting start outdoor heat exchanger temperature change amount? _Ted is calculated in step 506 by the following equation (8).

[Equation 8]

ΔT _ed = a T _o + b D N + c + d T _o + e N

△ T _o = T _o -T _o1

△ N = NN ₁

Here, a, b, c, d and e are integers.

In Formula 8 of ΔT _ed , the first terms aa ΔT _o to 3c of the right side are the same as those in the fourth embodiment, and the first terms a · ΔT _o are the terms according to the change of the outside air temperature. 2bb (DELTA) N represents a term due to a change in the compressor rotation speed. Of claim 4 wherein d · T _o and claim 5 wherein e · N represents the outside temperature impact and the number of revolutions on the outdoor heat exchanger temperature discloses removing frost also change the compressor at the time of the determination start remove frost. By adding these terms, it is possible to determine the implantation state more accurately than in the fourth embodiment. If the amount of change in the outdoor heat exchanger temperature? T _e = T _e -T _e1 is equal to or less than? T _{ed in} step 507, the four-way valve is switched from the heating cycle to the cooling cycle in step 508 to start the defrost operation. Note that the sign of the change amount of the outdoor heat exchanger temperature? T _e is negative, and the smaller this value is, the larger the absolute value of the change amount is. Since the following procedure is the same as that of 1st Example, description is abbreviate | omitted. Here, when considering the variation in the heating operation start or the defrosting operation ends after a predetermined time τ _s elapsed when the temperature of outside air assist compressor rotational speed by using, but executing the calculation of equation (8), the measured value, the number of times sampling from the time of τ _s elapsed Use the average of the values. In addition, in order to avoid the influence of a temporary fluctuation or a sudden fluctuation also in the compressor rotation speed, the outdoor heat exchanger temperature, and the outdoor temperature at the time of the defrosting start determination, Equation 8 may be calculated using several sampling average values.

According to the present embodiment, the influence of the change in the outside air temperature, the change in the compressor rotational speed, the outside air temperature in the determination of the defrosting start and the compressor rotation speed in the determination of the defrost start are determined in the determination using the temperature drop of the outdoor heat exchanger. Since it is considered, an appropriate defrosting operation is performed according to the determination of the defrosting start according to the more precise evaluation of the amount of implantation, and it is effective in improving comfort by reducing power consumption and preventing room temperature drop during the defrosting operation. . Moreover, even if the model is changed by using the change amount of the outdoor heat exchanger temperature, there is an advantage that it is not necessary to change the parameter of the defrost start determination condition or it is good to make a slight change.

Also in this embodiment, as in the first embodiment, the defrosting prohibition time is provided, and the minimum defrosting operation interval is ensured even when the detection error of the outdoor heat exchanger temperature is large by changing by the outside temperature of the defrosting prohibition time. It is possible to avoid the deterioration of comfort caused by frequent defrost operation.

According to this embodiment, the temperature change amount of the outdoor heat exchanger when the defrost operation is executed is the change amount of the outside air temperature, the change amount of the compressor rotation speed, the outside air temperature when the defrost start determination is made, and the compressor rotation speed when the defrost start determination is made. In this case, the defrosting start determination can be carried out according to a more strict evaluation of the amount of implantation.

In addition, since the defrosting prohibition time for not performing the defrosting operation for a predetermined time after the start of the heating operation or the end of the defrosting operation is provided, and the defrosting prohibition time is set according to the outside temperature and the outside humidity, the minimum defrosting operation is performed. The time not to execute is set more appropriately.

As described in detail above, according to the air conditioner of the present invention, the defrosting prohibition time is changed in accordance with the outside air temperature, and the defrosting start outdoor heat exchanger temperature is changed in accordance with the outside air temperature and the compressor rotation speed. Defrost operation is performed at an appropriate time, which is effective in reducing the power consumption and preventing the lowering of room temperature. Further, defrosting operation is appropriately performed even when frost is attached to the outdoor heat exchanger temperature sensor due to snow or when the installation state of the outdoor heat exchanger temperature sensor is unstable.

Claims (4)

compressor; An indoor heat exchanger connected to the compressor; An outdoor heat exchanger connected to the indoor heat exchanger via decompression means; Outdoor heat exchanger temperature detection means for detecting a temperature of the outdoor heat exchanger; In the operation of flowing the refrigerant discharged from the compressor in the order of the indoor heat exchanger and the outdoor heat exchanger to suck the refrigerant into the compressor, a command to reverse the refrigerant flow direction in accordance with the output of the outdoor heat exchanger temperature detection means is issued. Generating reverse command; Outside temperature detecting means for detecting outside temperature; Time means for indicating a set time which changes in accordance with the outside air temperature; Means for reverse rotating the refrigerant flow direction when the set time has elapsed and the reverse rotation command is generated; Means for outputting the rotational speed of the compressor, wherein the reverse rotation command generating means generates the reverse rotation command according to the compressor rotational speed output by the compressor rotational speed output means and the outdoor heat exchanger temperature. Air conditioning device characterized in that. compressor; An indoor heat exchanger connected to the compressor; An outdoor heat exchanger connected to the indoor heat exchanger via decompression means; Outdoor heat exchanger temperature detection means for detecting a temperature of the outdoor heat exchanger; In the operation of flowing the refrigerant discharged from the compressor in the order of the indoor heat exchanger and the outdoor heat exchanger to suck the refrigerant into the compressor, a command to reverse the refrigerant flow direction in accordance with the output of the outdoor heat exchanger temperature detection means is issued. Generating reverse command; Outside temperature detecting means for detecting outside temperature; Time means for indicating a set time which changes in accordance with the outside air temperature; Means for reverse rotating the refrigerant flow direction when the set time has elapsed and the reverse rotation command is generated; A humidity detecting means for detecting an outside air humidity is provided, and the reverse rotation command generating means sets the outdoor heat exchanger temperature to start frost removal as the outside air humidity detected by the humidity detecting means is higher. Device. compressor; An indoor heat exchanger connected to the compressor; An outdoor heat exchanger connected to the indoor heat exchanger via decompression means; An outdoor heat exchanger temperature detection means for detecting a temperature of the outdoor heat exchanger; And an outdoor air temperature detecting means for detecting an outside air temperature, wherein the refrigerant discharged from the compressor is supplied to the indoor heat exchanger and the outdoor heat exchanger in a sequential refrigerant flow direction or in a reverse direction to the refrigerant flow direction. An air conditioner capable of reversely rotating a refrigerant flow direction in one of a refrigerant flow direction of an indoor heat exchanger, wherein the refrigerant discharged from the compressor is passed in order of the indoor heat exchanger and the outdoor heat exchanger. The refrigerant flow direction is changed when the detection temperature of the outdoor heat exchanger temperature detection means is a temperature at which the refrigerant flow direction is reversed after a set time that changes according to the outside temperature detected by the outside air temperature detection means at the time of operation. Means for counter-rotating and means for outputting the number of revolutions of the compressor, for counter-rotating the refrigerant flow direction; It means an air conditioner, characterized in that one of changing the outdoor heat exchanger refrigerant throughflow direction to rotate the station according to at least one of during the revolution rate and the outdoor temperature of the compressor. compressor; An indoor heat exchanger connected to the compressor; An outdoor heat exchanger connected to the indoor heat exchanger via decompression means; Outdoor heat exchanger temperature detection means for detecting a temperature of the outdoor heat exchanger; An outdoor air temperature detecting means provided at a position close to the outdoor heat exchanger and detecting an outdoor air temperature; The difference between the output of the outdoor heat exchanger temperature detection means and the output of the outside air temperature detection means is set at the time of allowing the refrigerant discharged from the compressor to flow through the indoor heat exchanger and the outdoor heat exchanger in order to suck the refrigerant into the compressor. And a means for reversely rotating said refrigerant flow direction when it becomes smaller.

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