JP2722968B2 - Condensation prevention control device for indoor 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 indoor air conditioner, and more particularly to a dew condensation prevention control device for an indoor air conditioner employing a mesh fin heat exchanger.

[0002]

2. Description of the Related Art In a mesh fin heat exchanger, for example, a large number of heat transfer tubes having an outer diameter of 1 to 4 mm are arranged at a pitch of, for example, 10 to 20 mm, and mesh fins through which air can flow through the outer surfaces thereof are formed along the longitudinal direction. It has the advantage that water droplets condensed on the surface do not fall even if the fan is arranged at a considerable inclination when the wind speed of the fan is high, since it is flexible and easily formed into various curved surfaces. Therefore, in this mesh fin heat exchanger, the arrangement of the heat exchanger is spatial,
For indoor air conditioners such as ceiling-embedded type
It has been widely used recently and contributes to downsizing, lower noise and cost reduction of indoor units.

[0003]

However, the above mesh fin heat exchanger has a small diameter (1 to 4 mm) having a large pressure loss.
Because of the use of heat transfer tubes, it is necessary to diverge from a large-diameter tube to 10 or more in order to reduce pressure loss and to form multiple passes. , A difference occurs in the refrigerant flow rate. Then, the refrigerant evaporating in the heat transfer tube with a high refrigerant flow rate has a high degree of wetness, and the refrigerant evaporating in the heat transfer tube with a low refrigerant flow rate has a high degree of superheat. The passed indoor air reaches the downstream fan in a wet state without being sufficiently cooled, and contacts the uniformly cooled fan during the cooling operation to form dew. In other words, the conventional dew condensation prevention control targets a normal heat exchanger having a large-diameter heat transfer tube with no drift, and when the room temperature drops to near the dew point,
This is merely a method of preventing the condensation on the fan and casing of the indoor unit by simply stopping the cooling operation.Therefore, with such control, the condensation of the indoor unit using a new type of mesh fin heat exchanger that easily causes drift Can not be prevented,
There is a problem that water droplets condensed on the fan and the outlet are blown into the room. Also, simply stopping the cooling operation when the room temperature approaches the dew point does not detect the gradual leakage of the refrigerant from the refrigeration circuit system, and the leakage reduces the amount of circulating refrigerant, and the refrigerant evaporates in the heat exchanger. As described above, there is a problem in that when the indoor air is near the dew point, dew condensation occurs on the fan.

Accordingly, an object of the present invention is to determine the possibility of dew condensation based on parameters such as room temperature, outside air temperature, fan air flow rate, compressor rotation speed, etc., and change the fan air flow rate, compressor rotation speed, etc. to change heat exchange. By properly controlling the degree of superheat of the refrigerant evaporating in the heat exchanger, dew condensation in an indoor unit employing a mesh fin heat exchanger or the like in which drift is likely to occur or in an indoor unit in which the refrigerant leaks is also prevented. An object of the present invention is to provide a dew condensation preventing device for an indoor air conditioner that can improve versatility.

[0005]

In order to achieve the above object, a dew condensation prevention control device for an indoor air conditioner according to the present invention comprises a suction port 11a and an opening / closing flap 1 as illustrated in FIG.
Indoor air conditioner in which a heat exchanger 7 for evaporating the refrigerant discharged from the compressor 2 of the refrigeration circuit 1 and a fan 8 capable of changing the blown air amount Q are accommodated in a casing 11 having an air outlet 11b having an air outlet 2. , The outside air temperature To and the room temperature Ti are respectively equal to or less than predetermined values T ₁ and T ₂ , and the room temperature Ti and the set temperature T
If the absolute value │Ts-Ti│ difference s is less than the predetermined value T _3,
A first detecting means 14 for detecting an air flow amount Q of the fan 8, an opening degree の of the opening / closing flap 12, and an operating frequency f of the compressor 2, and an air flow amount Q detected by the first detecting means 14. When the operating frequency f is small (L) and the operating frequency f is the minimum fmin, the air flow rate Q and the operating frequency f are both changed to medium (M, f <fm). , The opening degree 変 化 is changed to a medium value (Θ <Θm) to increase the degree of superheat of the refrigerant in the heat exchanger 7 so as to eliminate condensation in the casing 11.
When the air flow rate Q detected by the first detection means 14 is large (H) and the operating frequency f is the maximum fmax, the air flow rate Q and the operating frequency f are both medium (M, fm <f ), And when the detected opening degree で is the maximum Θmax, the opening degree 中 is changed to medium (Θm <、) to reduce the degree of superheat of the refrigerant in the heat exchanger 7. A second control means 14 for controlling dew condensation in the fan 8 is provided. In addition, the first detection means 14 is further made to detect the temperature Th of the heat exchanger 7 as a second detection means 14 ', and the second control means 14 detects the temperature Th by the second detection means 14'. even when the temperature Th of the heat exchanger 7 that is less than or equal to a predetermined value T _4, air volume Q and in both the operating frequency f (M, f <fm) third control means so as to vary the 1
It can be 4 '.

[0006]

The indoor air conditioner includes a heat exchanger 7 in which a refrigerant discharged from the compressor 2 of the refrigeration circuit 1 evaporates in a casing 11 having an inlet 11a and an outlet 11b having an opening / closing flap 12. The fan 8 which can change the blowing amount Q is accommodated. The first detecting means 14 of the dew condensation prevention control device according to claim 1, wherein the outside air temperature To and the room temperature Ti are set to predetermined values T ₁ , T _2.
And the absolute value | T of the difference between the room temperature Ti and the set temperature Ts
If s−Ti | is equal to or less than the predetermined value T ₃ , it is determined that the dew point is approaching on the psychrometric chart, and the blowing amount Q of the fan 8, the opening degree Θ of the opening / closing flap 12, and the operating frequency f of the compressor 2 are detected. . The first control means 14 of the above-mentioned device, when the blown air amount Q detected by the first detection means 14 is small (L) and the operating frequency f is the minimum fmin, wets the refrigerant evaporated in the heat exchanger 7. As the air temperature is high and the air is insufficiently cooled and dew condensation is likely to occur, both the air flow rate Q and the operating frequency f are changed to medium (M, f <fm).
Subsequently, when the detected opening Θ is the minimum Θmin,
The opening Θ is changed to a medium (Θ <Θm), assuming that the cool air stagnates at the outlet 11b to promote dew condensation. Thereby, the dryness of the refrigerant evaporating in the heat exchanger 7 increases, the air is sufficiently cooled, the speed increases, and the cool air does not stagnate at the outlet 11b, thereby preventing condensation on the casing 11 near the outlet. You. On the other hand, the second control means 14 of the device
When the blowing amount Q detected by the detecting means 14 is large (H) and the operating frequency f is the maximum fmax, the degree of superheat of the refrigerant evaporated in the heat exchanger 7 is high, and the local temperature accompanying the drift of the refrigerant is high. Assuming that the fan 8 tends to form dew due to insufficient cooling of the air,
Both the blowing amount Q and the operating frequency f are changed to medium (M, fm <f), and when the detected opening degree で is the maximum Θmax, the dew condensation of the fan 8 is promoted by the increase of the blowing air amount. Therefore, the opening degree 変 化 is changed to medium (Θm <Θ). As a result, the degree of superheat of the refrigerant evaporating in the heat exchanger 7 is reduced, so that there is no local lack of cooling due to drift, and the amount of blown air is reduced, thereby preventing condensation on the fan 8.

In the second aspect of the present invention, the dew condensation preventing device further includes a second detecting means 14 'which causes the first detecting means 14 to further detect the temperature Th of the heat exchanger 7. comprising a first control means 14, the second control means 14 according to claim 1, even when the temperature Th of the heat exchanger 7 as detected by the second detecting means 14 'is less than the predetermined value T _4, The third control means 14 'is configured to change both the air flow rate Q and the operating frequency f to medium (M, fm <f). Therefore,
The second detecting means 14 'of this device detects the temperature Th of the heat exchanger 7 in addition to the operation of the first detecting means 14 described above. The first control means 14 'of the above device operates in the same manner as the above-described first control means 14, and prevents dew condensation on the casing 11. On the other hand, the third control means 14 'of the device operates in the same manner as the above-described second control means 14 to prevent condensation on the fan 8 and to prevent the heat exchanger detected by the second detection means 14'. when the temperature Th of 7 is equal to or less than the predetermined value T _4,
Heat exchanger 7 due to leakage of refrigerant from refrigeration circuit system 1
As the degree of superheat of the refrigerant evaporating in the air increases, and the fan 8 tends to form dew due to local insufficient cooling of the air due to the drift of the refrigerant, it is assumed that both the blowing amount Q and the operating frequency f are medium (M, fm <f).
To change. Thereby, dew condensation on the fan 8 due to leakage of the refrigerant from the refrigeration circuit system 1 is also prevented.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. FIG. 1 is a cross-sectional view illustrating an example of an indoor air conditioner employing the dew condensation prevention device of the present invention, and a circuit diagram illustrating a refrigeration circuit including the indoor air conditioner. The refrigeration circuit 1
As shown in FIG. 1 (A), a compressor 2, an outdoor heat exchanger 4 having an outdoor fan 5, an expansion valve 6 and an indoor heat exchanger 7 having an indoor fan 8 are sequentially piped as shown in FIG. The four-way switching valve 3 is switched to a path indicated by a solid line and a broken line to cool and heat the room R, respectively. As shown in FIG. 1B, the indoor air conditioner 10 has an air outlet 11b having a suction port 11a and an opening / closing flap 12.
The above-mentioned indoor heat exchanger 7 (hereinafter abbreviated as “heat exchanger”) having a drain pan 13 below in a casing 11 having: The indoor fan 8 (hereinafter, abbreviated as “fan”) that can change the air volume Q to small, medium, and large is housed. The heat exchanger 7
Is a mesh fin heat exchanger, and as shown in FIG. 2, the opening / closing flap 12 is changed by a servomotor (not shown) from the minimum opening degree Θmin to the maximum opening degree Θmax.

FIG. 1A shows a dew condensation preventing device for preventing dew condensation on the casing 11 and the fan 8 of the indoor air conditioner 10.
(Hereinafter abbreviated as "microcomputer").
, Also serves as first detection means, first control means, and second control means described later. That is, the microcomputer 14 has the first
As detection means, an outside air temperature sensor 15 and a room temperature sensor 16
Receiving a detection signal from outside air temperature To is below the predetermined value T _1, at room temperature Ti is less than a predetermined value T _2, and the absolute value of the difference between the set temperature Ts set in the room temperature Ti and the indoor unit │Ts- Ti│
If There it is determined that the predetermined value or less T ₃ (see S1 in FIG. 3),
In response to signals from the motor of the fan 8, the servomotor of the opening / closing flap 12, and the compressor 2, the blown air amount Q of the fan is small, medium,
It is determined whether the opening degree フ of the flap is large or the operating frequency f of the compressor. In addition,
The above judgment (S1 in FIG. 3) involves an error of about 2 ° C. because the temperature detection accuracy of the sensors 15 and 16 varies.

The microcomputer 14 operates as a first control means so that the detected air volume Q is small (L) and the operating frequency f
Is the minimum fmin (see S2 in FIG. 3),
And the operating frequency f is changed to medium (M, f <fm) (see S3), and when the detected opening degree で is the minimum Θmin
(See S4), change the opening Θ to medium (Θ <中 m)
(Refer to S5), control is performed to increase the degree of superheat of the refrigerant evaporated in the heat exchanger 7 to eliminate condensation in the casing 11. In addition, the microcomputer 14 is provided as a second control unit,
Detected air volume Q is large (H) and operating frequency f is maximum fmax
(See S6 in FIG. 3), the air flow rate Q and the operating frequency f are both changed to medium (M, fm <f) (see S7), and the detected opening degree で is a maximum Θmax. At some point (see step S8), the opening degree 変 化 is changed to medium (Θm <Θ) (see step S9), and the degree of superheat of the refrigerant evaporated in the heat exchanger 7 is reduced to eliminate condensation in the fan 8. Control is performed as follows.

The above-mentioned fm and Δm represent an intermediate value between the maximum and minimum operating frequencies fmax and fmin of the compressor 2 and an intermediate value between the maximum and minimum opening degrees Δmax and Δmin of the opening / closing flap 12, respectively. Accordingly, f <fm means that the operating frequency f is set to a medium value smaller than the intermediate value fm, and 、 m <Θ means that the opening Θ is set to a medium value larger than the intermediate value Θm. The detection and control processing by the microcomputer 14, which also serves as the first detection means, the first control means, and the second control means described above, is as shown in the table of FIG.

The operation of the dew condensation prevention control device for an indoor air conditioner according to the first aspect of the present invention will be described below with reference to FIG. Now, the four-way switching valve 3 of the refrigeration circuit 1 of FIG.
Is switched to the path indicated by the solid line in the drawing, and the compressor 2, the outdoor fan 5 and the fan 8 are driven, and the indoor R is cooled by the heat exchanger 7 functioning as an evaporator. The microcomputer 14, which is the dew condensation prevention control device, receives the detection signals from the outside air temperature sensor 15 and the room temperature sensor 16, and in step S1 in FIG. 3, sets the outside air temperature To to a predetermined value T _1.
Or less and room temperature Ti is the predetermined value T ₂ or less, and the absolute value │Ts-Ti│ the difference between the set temperature Ts and the ambient temperature Ti which is set in the indoor unit
There it is determined whether a predetermined value T ₃ below, when it is determined that affirmation, as close to the dew point on the diagram psychrometric, in response to a signal from the motor of the fan 8, the compressor 2 and the opening and closing flaps 12, It detects whether the air flow amount Q of the fan 8 is small, medium, or large (L, M, H taps), what the operating frequency f of the compressor 2 is, and what the flap opening Θ is.

Next, in step S2, it is determined whether the detected air volume Q is small (L) and the operating frequency f is the minimum fmin, and if the determination is affirmative, the refrigerant evaporating in the heat exchanger 7 is determined. Since the humidity of the air is high and the air is insufficiently cooled and dew condensation easily occurs on the casing, the process proceeds to step S3, in which a control signal is sent to both motors to set both the air flow rate Q and the operating frequency f to medium (M, f <f).
m). Subsequently, in step S4, it is determined whether or not the detected opening degree で is the minimum Θmin. If the determination is affirmative, the cool air stagnates at the outlet 11b to promote dew condensation, and the process proceeds to step S5. Then, a control signal is sent to the servomotor to change the opening Θ of the opening / closing flap 12 to a medium (Θ <Θm). By these controls, the dryness of the refrigerant evaporating in the mesh fin type heat exchanger 7 increases, the air is sufficiently cooled, the wind speed increases, and the cool air does not stagnate at the outlet 11b.
Condensation on the casing 11 near the outlet is prevented.

If the answer is NO in step S2, the process proceeds to step S6, in which it is determined whether the detected air volume Q is large (H) and the operating frequency f is the maximum fmax. The degree of superheating of the refrigerant evaporating in the heat exchanger 7 is high and the fan 8
Proceeds to step S7, and sends a signal to each motor to set the air flow rate Q and the operating frequency f to the middle (M, fm <
f). Subsequently, in step S8, it is determined whether or not the detected opening Θ is the maximum Θmax. If the determination is affirmative, condensation of the fan 8 is promoted by an increase in the amount of blown air, and the process proceeds to step S9. Then, a signal is sent to the servomotor to change the opening Θ of the opening / closing flap 12 to a medium (Θm <Θ). By these controls, the degree of superheat of the refrigerant evaporating in the mesh fin type heat exchanger 7 is reduced, so that there is no local lack of cooling due to drift, and the amount of blown air is reduced to prevent dew condensation on the fan 8.

FIG. 4 is a flowchart showing the control of the dew condensation preventing device according to the second aspect of the present invention. This dew condensation preventing device has a microcomputer 1 similar to that described with reference to FIG. 1A and serving as a second detecting means, a first controlling means, and a third controlling means.
4 '. That is, the microcomputer 14 ′, as the second detecting means, in addition to the temperature sensors 15 and 16 described above,
When a detection signal from the temperature sensor 17 provided in contact with the heat exchanger 7 is also received and the result of the above-described determination is affirmative in S1 in FIG. 3 (see S11 in FIG. 4), the air flow rate Q, the flap Opening Θ,
It detects how much the temperature Th of the heat exchanger 7 is in addition to the operating frequency f. Further, the microcomputer 14 'performs the same control as described in S2 to S5 in FIG. 3 as the first control means (S12 to S15 in FIG. 4), and as the third control means, the air flow amount Q is large ( H) and the operating frequency f is the maximum fmax
In addition, when the temperature Th of the heat exchanger 7 becomes a predetermined value T ₄
If the air flow rate Q and the operating frequency f are both
(M, fm <f) (see S16 in FIG. 4). Other controls (S17 to S19 in FIG. 4) are the same as steps S7 to S9 described in FIG.

Accordingly, the microcomputer 14 'prevents condensation on the casing 11 in steps S11 to S15 in FIG. 4 by the same control as in steps S1 to S5 in FIG. Further, when the air blowing amount Q is large (H) and the operating frequency f is the maximum fmax, in steps S16 to S19 in FIG.
The same control as ～S9, thereby preventing condensation of the fan 8, at step S16, when the temperature Th of the heat exchanger 7 of the mesh fin is equal to or less than the predetermined value T _4, the leakage of the refrigerant from the refrigeration circuit 1 Assuming that the degree of superheat of the refrigerant evaporating in the heat exchanger 7 is increased due to the above reasons, and that the fan 8 tends to form dew due to local insufficient cooling of the air due to the drift of the refrigerant, the process proceeds to step 17 and the flow rate Q The operating frequency f is changed to medium (M, fm <f). By these controls, the degree of superheat of the refrigerant evaporating in the mesh fin type heat exchanger 7 is reduced, so that there is no local lack of cooling due to the drift, and the amount of blown air is reduced, thereby preventing dew condensation on the fan 8 and freezing. Dew condensation on the fan 8 due to an increase in the degree of superheat due to leakage of the refrigerant from the circuit 1 is also prevented.

[0017]

As is apparent from the above description, the dew condensation prevention control apparatus for an indoor air conditioner according to the present invention provides a heat exchange system in which refrigerant from a compressor evaporates in a casing having an outlet having an opening / closing flap. In the indoor air conditioner containing a fan with a variable air flow rate, when the outside air temperature and the room temperature are equal to or less than a predetermined value and the absolute value of the difference between the room temperature and the set temperature is equal to or less than a predetermined value, Detects the air flow, flap opening and compressor operating frequency, and when the detected air flow is small and the operating frequency is minimum or flap opening is minimum,
While the first control means changes both of them to inside to eliminate the condensation of the casing due to an increase in the degree of superheat, when the detected air volume is large and the operation frequency is maximum or the flap opening is maximum, (2) The control unit changes both of them to the inside so that dew condensation of the fan is eliminated due to a decrease in the degree of superheat. Therefore, even in an indoor unit employing a mesh fin heat exchanger in which drift tends to occur, the fan and the casing can be used. It is possible to effectively prevent dew condensation on the indoor unit, and to increase the versatility of such an indoor unit, which can be made compact, reduce noise, and reduce costs because of the mesh fins. Further, the first detection means of the dew condensation prevention control device further detects the temperature of the heat exchanger, and the second control means causes the air flow rate to be increased even when the detected temperature of the heat exchanger is equal to or lower than a predetermined value. If both the operating frequency and the operating frequency are changed to medium, it is possible to prevent condensation on the fan due to an increase in the degree of superheat due to leakage of the refrigerant from the refrigeration circuit.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of an indoor air conditioner employing a condensation prevention control device of the present invention, and a circuit diagram showing a refrigeration circuit including the indoor heat exchanger.

FIG. 2 is a table showing a detection and control process of an example of the dew-prevention device according to claim 1 of the present invention.

FIG. 3 is a flowchart showing a control flow of an example of the above dew condensation preventing device.

FIG. 4 is a flowchart showing a control flow of an example of a dew condensation prevention control device according to claim 2 of the present invention.

[Explanation of symbols]

1: Refrigeration circuit, 2: compressor, 7: (indoor) heat exchanger, 8:
(Indoor) Fans, 9a-9f: Pipe, 10: Indoor air conditioner, 11: Casing, 12: Opening / closing flap, 14, 1
4 ': microcomputer, 15: outside air temperature sensor, 16: room temperature sensor, 17: temperature sensor.

Claims (2)

(57) [Claims] 1. A suction port (11a) and an opening / closing flap (12).
In a casing (11) having an outlet (11b) having
A heat exchanger (7) for evaporating the refrigerant discharged from the compressor (2) of the refrigeration circuit (1), and a fan (8) capable of changing the air volume (Q)
In condensation prevention control device of the indoor air conditioner accommodating the door, the outside air temperature (To) and room temperature (Ti) is respective predetermined values (T _1, T ₂₎ or less, and the room temperature (Ti) and the set temperature ( Ts) Absolute value of difference
When (| Ts−Ti |) is equal to or less than a predetermined value (T ₃ ), the blowing amount (Q) of the fan (8) and the opening degree of the opening / closing flap (12)
(Θ) and a first method for detecting the operating frequency (f) of the compressor (2)
Detecting means (14), when the air flow rate (Q) detected by the first detection means (14) is small (L) and the operating frequency (f) is minimum (fmin), Q) and operating frequency (f)
Are changed to medium (M, f <fm), and when the detected opening (Θ) is the minimum (Θmin), the opening (Θ) is changed to medium (中
<Θm) to increase the degree of superheating of the refrigerant in the heat exchanger (7) so as to eliminate condensation in the casing (11); and the first detection means.
When the air volume (Q) detected in (14) is large (H) and the operating frequency (f) is the maximum (fmax), both the air volume (Q) and the operating frequency (f) are medium ( M, fm <f), and when the detected opening (Θ) is the maximum (Θmax), the opening (Θ) is changed to medium (Θm <Θ), A dew-prevention control device for an indoor air conditioner, comprising second control means (14) for controlling the degree of superheat of the refrigerant in the exchanger (7) to eliminate dew condensation in the fan (8). . 2. An inlet (11a) and an opening / closing flap (12).
In a casing (11) having an outlet (11b) having
A heat exchanger (7) for evaporating the refrigerant discharged from the compressor (2) of the refrigeration circuit (1), and a fan (8) capable of changing the air volume (Q)
In condensation prevention control device of the indoor air conditioner accommodating the door, the outside air temperature (To) and room temperature (Ti) is respective predetermined values (T _1, T ₂₎ or less, and the room temperature (Ti) and the set temperature ( Ts) Absolute value of difference
When (| Ts−Ti |) is equal to or less than a predetermined value (T ₃ ), the blowing amount (Q) of the fan (8) and the opening degree of the opening / closing flap (12)
(Θ), the operating frequency (f) of the compressor (2) and the heat exchanger
(7) a second detecting means (14 ') for detecting the temperature (Th), and the air flow (Q) detected by the second detecting means (14') is small (L) and the operating frequency ( When f) is the minimum (fmin), the air flow rate (Q) and the operating frequency (f) are both medium (M, f <f
m), and then the detected opening (Θ) is minimized.
(Θmin), the opening (Θ) is changed to medium (中 <Θm) to increase the degree of superheat of the refrigerant in the heat exchanger (7) so as to eliminate condensation in the casing (11). The first air flow rate (Q) detected by the second control means (14 ') is large (H) and the operating frequency (f)
When is the temperature of the maximum (fmax) or the heat exchanger (7) (Th) is below a predetermined value (T _4), the air volume (Q) and the operating frequency (f) through the both (M, fm < f), and then when the detected opening (Θ) is the maximum (Θmax), this opening
(Θ) is changed to medium (変 化 m <Θ) to reduce the degree of superheat of the refrigerant in the heat exchanger (7) so as to eliminate condensation in the fan (8). A dew prevention control device for an indoor air conditioner, comprising: