JPH03199850A - Indoor unit of air conditioner - Google Patents

Abstract

PURPOSE:To reduce a change in a blowoff temperature even when a room temperature changes by increasing an initial voltage applied to a fan driving motor as the room temperature rises and controlling a voltage applied to the motor so that a refrigerant temperature is between upper limit and lower limit refrigerant temperatures. CONSTITUTION:After an initial voltage is applied to a motor 3, when a blowoff temperature calculated from a refrigerant temperature obtained from refrigerant temperature detecting means 6 is equal to or above an upper limit blowoff temperature, a voltage higher than the one applied now is applied to the motor 3. When the blowoff temperature is below a lower limit blowoff temperature, the voltage lower than that applied now is applied to the motor 3. Therefore, the width of a change in the blowoff temperature can be restricted within a prescribed range even when the room temperature changes. Further, when the temperature width of a divided temperature zone is reduced by making an upper limit blowoff temperature TOL approach the maximum blowoff temperature T1 at a design point as near as possible and making a lower limit blowoff temperature TOS approach the minimum blowoff temperature (T1- T1) at a design point as near as possible, the width of a change in the blowout temperature can be reduced, so that it is easy to remove the sense of the change from a body sense.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an indoor unit of an air conditioner that performs heating using a refrigerant as a working fluid.

2. Description of the Related Art A conventional indoor unit of this type consists of a heat exchanger 1, a fan 2, a motor 3, etc., as shown in FIG.
A refrigerant temperature detection means 5 is provided on the surface of the heat exchanger tube 4 . In the case of heating operation, the heat exchanger 1 functions as a condenser, but the fan 2 and motor 3 are stopped immediately after the start of operation, and when the refrigerant temperature detection means 5 detects a temperature higher than a certain set temperature, the heat exchanger 1 functions as a condenser. A voltage is applied to the motor 3, and the fan 2 rotates.

Problems to be Solved by the Invention Generally, the room temperature is low for a while after heating starts. However, in the configuration shown in FIG. 4, as soon as the refrigerant temperature detection means 5 detects a temperature higher than a certain set temperature, voltage is applied to the motor 3 and the fan 2 rotates in the set air volume mode selected at that time. do. At this time, the room temperature is still low, so the blowing temperature is also low. In particular, when a set air volume mode with a large air volume is selected, warm air with a cool air feeling that is not much different from room temperature is blown out, causing a serious problem in comfort.

Further, for a while after the heating starts, IJL air with a feeling of cold air, which is not much different from the room temperature, is blown out as described above, and as the room temperature rises, it cools down and warm air with a feeling of heating is blown out. As described above, it takes time for hot air with a heating feeling to come out, and there is a problem in immediate heating. There was also the problem that the performance changed due to clogging of the filter and variations in each component device.

Furthermore, when a set air volume mode with a small air volume is selected, the heating capacity changes (reduces) to protect the equipment when the room temperature rises slightly.

As a result, the temperature of the air outlet changes, the heating capacity is insufficient, and there are problems with comfort.

In FIG. 6, the horizontal axis shows the room temperature after the start of heating, and the vertical axis shows the detected refrigerant temperature TR obtained from the refrigerant temperature detection means 5, the voltage V applied to the motor 3, the rotation speed n of the fan 2, and the heating capacity. Q and the blowout temperature T0 are taken, and the detected refrigerant temperature, the voltage applied to the motor 3, the rotation speed of the fan 2, the heating capacity, and the change in the blowout temperature are shown as the room temperature changes after heating starts. In the figure, the solid line indicates when a large air volume mode is selected when a plurality of air volume modes are selectable, and the dotted line indicates when a small air volume mode is selected. First, in the case of a large air volume shown by the solid line, as can be seen from the figure, when the fan 2 starts rotating, the detected temperature TR, that is, the temperature 11 degrees, drops rapidly. For this reason, the blowing temperature is low and it takes a long time for warm air with a feeling of heating to come out, resulting in the above-mentioned problems.

Next, in the case of a small air volume as shown by the dotted line, as can be seen from the figure, even if the fan 2 starts rotating, the blowing temperature does not drop suddenly, but as the room temperature rises, the heat exchanger The pressure and temperature of the refrigerant inside 1 increase.

Therefore, in order to protect the entire air conditioner, the heating operation must be stopped or the heating capacity must be reduced. As a result, as shown in the figure, the heating capacity changes significantly, and the blowout temperature also changes significantly, resulting in the above-mentioned problems.

The present invention solves such conventional problems, and aims to improve comfort and quick heating by controlling the voltage applied to the motor that drives the fan according to the room temperature and refrigerant temperature. shall be.

Means for Solving the Problems In order to solve the above problems, the indoor unit of the air conditioner of the present invention roughly and appropriately divides the temperature range to be compared with the room temperature obtained from the room temperature detection means, and divides each divided temperature range. Now, a preset initial applied voltage is applied to the motor such that the initial applied voltage to the motor increases as the temperature of the divided temperature range increases, and furthermore, the preset refrigerant upper limit temperature and The refrigerant lower limit temperature is compared with the refrigerant temperature obtained from the refrigerant temperature detection means provided on the surface of the heat exchanger tube or refrigerant inlet pipe of the heat exchanger, and if the refrigerant temperature is higher than the refrigerant upper limit temperature, the refrigerant is transferred to the motor. The control means increases the voltage applied to the motor, and decreases the voltage applied to the motor when the refrigerant temperature is lower than the lower limit temperature of the refrigerant.

Effect of the Invention With the above configuration, the present invention increases the initial voltage applied to the motor that drives the fan as the room temperature increases, and further increases the voltage applied to the motor so that the refrigerant temperature is between the upper refrigerant temperature and the refrigerant lower limit temperature. Since the applied voltage is controlled, even if the room temperature changes, the change in the blowing temperature can be reduced.

Embodiments Hereinafter, embodiments of the present invention will be described based on the accompanying drawings.

In FIG. 1, 1 is a heat exchanger, 2 is a fan, and a motor 3 drives this fan 2. In FIG. moreover,
A refrigerant temperature detection means 6 is provided on the surface of the heat transfer tube 4 of the heat exchanger 1 or on the surface of the refrigerant inlet pipe 5 of the heat exchanger 1, and a refrigerant temperature detection means 6 is provided on the windward side of the heat exchanger 1. A room temperature detection means 7 is provided for detecting the temperature. The control means 8 is configured to control the motor drive means 9 that generates the voltage applied to the motor 3 based on the signals from the refrigerant temperature detection means 6 and the room temperature detection means 7.

First, when heating operation is started, as in the case of the conventional example shown in FIG. Rotate.

However, the initial voltage applied to the motor 3 at this time is determined as follows.

In FIG. 2, the horizontal axis shows the room temperature after heating starts, and the vertical axis shows the detected refrigerant temperature TR and the voltage applied to the motor 3.

Fan 2 rotation speed n, heating capacity Q and blowout temperature T
. This shows the changes in the detected refrigerant temperature, the voltage applied to the motor 3, the rotation speed of the fan 2, the heating capacity, and the blowout temperature as the room temperature changes after heating starts.

In FIG. 2, the room temperature, which is the horizontal axis, is divided appropriately as shown by dotted lines, and the maximum temperature of the air outlet temperature is set as T1. Room temperature T, and T shown in the same figure.

The explanation will be given by taking as an example the divided temperature zone ΔT determined by .

Generally, heating capacity is expressed by the following formula.

Q=CpXV, Xδx (T, -Tr) -(
1) However, Q is the heating capacity, Cp is the specific heat at constant pressure, Va is the air volume, δ is the specific weight, To is the blowout temperature, and T8 is the suction temperature (room temperature).

Therefore, using the upper limit temperature T of the divided temperature zone ΔT8 and the maximum blowout temperature T1, the required air volume in this divided temperature zone ΔT is as follows.

L = Q/ (Cpxδx (TI TL ) l
(2) In the same divided temperature zone ΔT, if the air volume shown in equation (2) is constant, the room temperature is the blowout temperature T at the lower limit temperature Ts of the divided temperature zone ΔT8. is (1) and equation (2)
Using , it becomes as follows.

T0=, T1 (Tt Ts)
(3) In other words, the temperature is lower than the maximum blowing temperature T1 by the temperature width of the divided temperature zone (TL-Ts). After all, by reducing the temperature width of the divided temperature zones, the temperature difference in the blowout temperatures can also be reduced.

By the way, FIG. 3 shows the relationship between the air volume and the voltage applied to the motor 3, with the horizontal axis representing the air volume v8 and the vertical axis representing the voltage applied to the motor 3.

That is, if the relationship shown in FIG. 3 is determined in advance, the required applied voltage for the required air volume can be easily determined.

However, in reality, it is difficult to always operate according to the above calculation. In other words, even if the air conditioner is designed according to the above calculations, in reality, there may be variations in the performance of each element that makes up the air conditioner, and there may be dust or other particles on the filter or heat exchanger that may accumulate over time. Figure 2.

In some cases, it may not be possible to obtain the characteristics shown in the characteristic diagram shown in FIG.

By the way, if the blowing temperature changes significantly or if the blowing temperature is too low or too high, comfort and operation guarantee may be impaired.

Now, the condensation temperature of the refrigerant in heat exchanger 1 is TR1, and the blowout temperature is T. Then, the relationship TR#To+K□(4) approximately holds true. Although K is not a constant, it is safe to assume that its change is constant based on human experience. Therefore, if you roughly determine the value of K by experiment, the blowout temperature T
. T, ! =i T, −K −(5)
In the end, in order to control the blowout temperature T0, it is sufficient to control the condensation temperature T of the refrigerant.

In Figure 4, the horizontal axis shows the room temperature T, and the vertical axis shows the air outlet temperature (
The figure shows the change in the blowout temperature and the motor applied voltage with respect to room temperature, taking the motor applied voltage as T, =TR-K) and the motor applied voltage. In the figure, T is the maximum blowout temperature at the design point, T1-ΔT.

is the blowout temperature (
(minimum blowout temperature at the design point).

Furthermore, TOL and Tos are an upper limit temperature and a lower limit temperature, respectively. Immediately after the start of operation of the air conditioner, the control means 8 is activated according to the room temperature obtained from the room temperature detection means 7.
The motor drive means 9 is operated, and the initial applied voltage shown in FIG. 2 is applied to the motor 3, thereby driving the fan 2. and,
If the blowing temperature is between the blowing upper limit temperature and the blowing lower limit temperature, the initial applied voltage for each divided temperature zone shown in FIG. 2 is applied to the motor 3. However, the blowout temperature calculated from the refrigerant temperature obtained from the refrigerant temperature detection means 6 as at points A and B in FIG. 4 is the blowout upper limit temperature T. If the temperature exceeds L, the control means 8 operates the motor drive means 9 to apply a voltage one level higher than the currently applied voltage, and furthermore, as shown at point C in the figure, the control means 8 operates the motor drive means 9 to apply a voltage one step higher than the voltage currently applied. The blowout temperature calculated from the refrigerant temperature obtained from is the blowout lower limit temperature T. , if it is less than
The control means 8 operates the motor drive means 9 to apply a voltage one step lower than the currently applied voltage.

Here, the blowout upper limit temperature T. Make L as close as possible to the maximum blowout temperature TI at the design point (may be equal to it), and further set the blowout minimum temperature T. 3 as close as possible to the minimum blowout temperature (T1-ΔTi) at the design point, and by reducing the temperature width ΔT of the divided temperature zones as described above, the temperature difference in the blowout temperatures can also be reduced.

As can be seen from the above explanation, the upper limit temperature T of the divided temperature zone
Air volume Vs determined from L and maximum blowout temperature T
After applying the initial applied voltage determined from the relationship shown in FIG. 3 to the motor in order to obtain (Equation (2)),
If the blowout temperature calculated from the refrigerant temperature obtained from the refrigerant temperature is equal to or higher than the blowout upper limit temperature, a voltage one step higher than the currently applied voltage is applied, and if the blowout temperature is below the blowout lower limit temperature, the currently applied voltage is Since a voltage one step lower than the current voltage is applied, even if the room temperature changes, the range of change in the blowout temperature can be kept within a certain range. Furthermore, if the upper limit temperature of the air outlet is as close as possible to the maximum temperature of the air outlet at the design point, and the lower limit temperature of the air outlet is as close as possible to the minimum temperature of the air outlet at the design point, the temperature width of the divided temperature bands is reduced.
Since the range of change in the blowout temperature can be made small, it is easy to make the change not perceivable. Furthermore, by increasing the set value of the maximum blowout temperature T, a sufficiently high temperature air blowout can be obtained.

1 In the end, if the temperature width of the divided temperature zone, the maximum blowout temperature, the blowout upper limit temperature, and the blowout lower limit temperature at the design point are set appropriately, warm air with a sufficient heating feeling can be maintained even if the room temperature changes. There is an effect. Furthermore, since the same can be said immediately after heating operation, there is also the effect of good immediate heating. Furthermore, as the room temperature rises, the air volume also increases, which guarantees heating capacity and improves comfort. In addition, since the voltage applied to the motor is controlled so as to eliminate the influence of variations in the various elemental devices that make up the air conditioner, as well as dust that accumulates in the filter and heat exchanger, it also has the effect of guaranteeing operation and improving comfort.

Effects of the Invention As described above, the indoor unit of the air conditioner of the present invention provides the following effects.

(1) As long as the temperature width of each divided temperature zone of the room temperature and the maximum blowout temperature, upper limit temperature, and lower limit temperature of the blowout at the design point are appropriately set, a sufficiently high blowout temperature can be obtained regardless of the room temperature. Second, since the temperature of the air outlet is approximately the same in terms of sensation, it has the effect of providing a sufficient feeling of heating and improving comfort.

(2) Furthermore, since the same applies immediately after heating starts, there is also the effect of good immediate heating.

(3) Since the air volume basically increases as the room temperature rises, maximum heating capacity is always guaranteed and comfort is improved.

(4) Furthermore, since the voltage applied to the motor is controlled so as to eliminate the effects of variations in each element of the air conditioner and the effects of dust accumulated on the filter and heat exchanger, there is an effect of guaranteeing operation and improving comfort.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a configuration diagram of the interior of an indoor unit of an air conditioner showing an embodiment of the present invention, and Fig. 2 shows 5 models of detected refrigerant temperatures with respect to room temperature after the start of heating operation in the same embodiment. An explanatory diagram showing changes in the initial applied voltage, fan rotation speed, heating capacity, and outlet temperature. Figure 3 is an explanatory diagram showing the relationship between air volume and motor applied voltage. Figure 4 is after the heating operation of the same example starts. Explanatory diagram showing changes in blowout temperature and motor applied voltage with respect to room temperature, 5th
The figure shows the internal configuration of the indoor unit of a conventional air conditioner, and Figure 6 shows the changes in the detected refrigerant temperature, motor applied voltage, fan rotation speed heating capacity, and blowout temperature with respect to the room temperature after the start of heating operation in the conventional example. FIG. 1...Heat exchanger, 2...Fan, 3.
... Motor, 4 ... Heat exchanger tube, 5 ...
... Refrigerant artificial pipe, 6 ... Refrigerant temperature detection means, 7
...Room temperature detection means, 8...Control means,
9...Motor drive means.

Claims (1)

[Claims] It consists of a heat exchanger, room temperature detection means, a fan, a motor, a motor drive means that can switch the applied voltage in multiple stages, a refrigerant temperature detection means provided on the surface of the refrigerant inlet pipe or heat transfer tube of the heat exchanger, etc. The temperature zone to be compared with the room temperature obtained from the detection means is divided into appropriate sections in advance, and in each divided temperature zone, the initially applied voltage to the motor is set to be larger as the divided temperature zone becomes higher. An air conditioner configured to apply an initial setting applied voltage to the motor, wherein a refrigerant upper limit temperature and a refrigerant lower limit temperature are set in advance in each divided temperature zone;
Comparing the refrigerant temperature obtained from the refrigerant temperature detection means, if the refrigerant temperature is higher than the upper limit temperature of the refrigerant, increase the voltage applied to the motor, and if the temperature of the refrigerant is lower than the lower limit temperature of the refrigerant. For example, an indoor unit of an air conditioner having a control means for reducing the voltage applied to the motor.