JPH0631715B2 - Air conditioner - Google Patents

Description

TECHNICAL FIELD The present invention relates to a room air conditioner, and more particularly to an outdoor heat exchanger suitable for a heat pump type room air conditioner.

[Background of the Invention]

A heat exchanger of a conventional heat pump type room air conditioner will be described with reference to FIGS. 1 to 5.

1 is a base, 2 is a cabinet, 3 is a right side plate, 4 is a left side plate, and these 4 parts form an outer box body.
On top of that, electric components such as a compressor 5 and a heat exchanger 8 6 are arranged. Reference numeral 7 is a cycle pipe that connects the compressor 5, the heat exchanger 6, and other devices. 9 is a blower motor,
10 is a fan for blowers.

In addition to the outdoor unit having these configurations, the room air conditioner is configured by the indoor unit, the piping connecting the outdoor unit and the indoor unit, and the like. When this air conditioner is operated by heat pump type heating, the indoor unit becomes the condensation side of the refrigerant that radiates heat to the indoor air, and the outdoor unit becomes the evaporation side of the refrigerant that absorbs heat from the outdoor air. The characteristics of the heat pump heating operation will be described with reference to FIG. 3. The vertical axis represents temperature, and the horizontal axis represents the time course of operation from left to right. Here, E is the blown air temperature of the indoor unit, and F is the refrigerant temperature at the outlet of the heat exchanger 6 of the outdoor unit. Further, the surface of the heat exchanger 6 of the outdoor unit is composed of fins made of metal such as aluminum having excellent thermal conductivity.
A is a fin on the windward side, and 6B is a fin on the leeward side. Further, 6C and 6D are pipes through which the refrigerant passes, and they penetrate the fins 6A and 6B by pressure bonding. These fins 6
When A and 6B absorb heat from the air, the air reaches the stall temperature or lower and a dewdrop is formed on the surfaces of the fins 6A and 6B. When the outside air temperature is low, the temperature of the heat exchanger 6 becomes 0 ° C. or lower, and frost or ice is formed on the surfaces of the fins 6A and 6B. When this frost or ice adheres, the evaporator and the condenser of the refrigeration cycle are made to act in reverse at the point A in FIG. 3 by the defrosting thermostat that senses the temperature of the heat exchanger 6. That is, the outdoor heat exchanger 6 is switched to the condenser, and the defrost operation for melting the frosted frost starts. The temperature of frosted heat exchanger 6 is raised up to point A1, then the frost is melted, and heating operation is restored at point A2.

After returning to heating operation again, continue heating operation B → C →
The defrost operation is repeated again after the point D → A. At the initial point B after returning to the heating operation, the frost 11 starts on the fins 6A as shown in FIG. At this point, the temperature F at the outlet of the outdoor heat exchanger 6 and the blown air temperature E of the indoor unit are almost in the same state as after the heating operation is restored, and the heating capacity is sufficient. However, the operation is further continued, and the heat absorption in the heat exchanger 6 begins to decrease at the point C where the frost on the heat exchanger 6 has grown, and when the point reaches the point D, the fins 6A as shown in FIG.
The frost on the side grows, the amount of air passing through becomes extremely small, and the heat exchanger outlet temperature F decreases more and more. It was Further, in some cases, the frost becomes low-temperature ice and the defrost time is long, and there is a drawback that heating operation cannot be performed during this time. Furthermore, there is a defect that the noise of the blower becomes high because the resistance of the wind passing through the heat exchanger 6 increases.

Conventionally, in order to eliminate the above defects, the fin pitch of the first fin 6A and the second fin 6B has also been increased, but the surface area of the heat exchanger 6 is reduced and the heating performance is reduced, or heat exchange is performed. There was a defect that the container 6 became large and the size of the whole product became large.

When the outside air temperature is not so low, the heat exchanger 6
Dewdrops are generated on the surfaces of the fins 6A and 6B, and since many dewdrops also adhere to the windward side of the fins 6A, it is difficult for the wind to pass through, and the fins 6B do not act sufficiently and the heating capacity decreases. There was a phenomenon such as an increase in noise.

[Object of the Invention]

An object of the present invention is to provide, as a heat exchanger for a heat pump type room air conditioner, a heat exchanger that is highly efficient, has little performance deterioration even when exposed to frost and dew, and is inexpensive.

[Outline of Invention]

In the outdoor heat exchanger of the heat pump type room air conditioner, the radiation fins are divided into first fins and second fins, the pitch of the first fins is made larger than the pitch of the second fins, and the first fins are set to the windward side, It prevents deterioration of performance due to frost formation, and the inner surface smooth pipe, the second
An inner grooved tube is used on the fin side to provide a highly efficient and inexpensive heat exchanger.

Example of Invention

An embodiment of the present invention will be described below with reference to FIGS. 2 and 6 to 1.
This will be described with reference to FIG.

7 and 8, 6a is the first fin of the heat exchanger 6, 6b is the second fin, and the fin pitch of the first fin 6a is made larger than the fin pitch of the second fin 6b. Reference numerals 6c and 6d denote pipes through which the refrigerant passes, which are crimped to and penetrate the fins 6a and 6b, respectively.
Reference numeral c is an inner surface smooth tube, and pipe 6d is an inner surface grooved tube having grooves 14 for improving the internal heat transfer coefficient. 11a is a dewdrop, and in a normal heating operation, since the humidity of the air 13 passing through the heat exchanger 6 is removed on the first fin 6a side, the second fin 6b does not have much dew. Also, the first fin 6a
Even if there is a dewdrop, the fin pitch is wide, so the dewdrop flows easily, and the wind easily passes through it. It can be replaced, and the heating capacity will not decrease. When the outside air temperature is very low, frost adheres to the windward first fins 6a as shown in FIG. But,
Since the first fin 6a has a large fin pitch, the wind sufficiently passes therethrough, and the decrease in the amount of air due to frosting is small, and sufficient heat exchange is performed on the second fin 6b side using the inner grooved tube. Therefore, the temperature drop of the heat exchanger due to frost is small, frost does not grow into ice, efficient heating operation can be performed, and the fin pitch on the side of the first fin 6a with a lot of frost is also present during defrosting. As a result, the defrost time is shortened and the heating efficiency is improved.

The above situation will be described with reference to FIG. 6. The vertical axis represents the temperature of each part of the room air conditioner, the horizontal axis represents the operation elapsed time, b is the outdoor heat exchanger outlet refrigerant temperature, and e is the discharge air temperature of the indoor unit. During heating operation, the vehicle enters defrost at point a as in the conventional case. Up to a _1, it is the time to raise the temperature of the outdoor heat exchanger 6, but as described above, in the heat exchanger of the present invention, the decrease in the air volume during frosting is reduced, so the outdoor heat exchanger 6 The temperature is higher than before and the time is shorter. Further raising the temperature of the heat exchanger 6, but to completely return to normal heating operation at a _2-point performs defrost,
The defrost time from a to a _{1 to} a ₂ is about half that of the conventional one. FIG. 9 shows that for the pitch of the second fin 6b,
This is a relationship between the pitch ratio of the first fins 6a and the air volume, and the air volume increases until the pitch of the first fins 6a becomes about 1.5 times that of the second fins 6b, and above that, the air volume hardly increases. FIG. 10 shows the relationship between the pitch of the second fins 6b and the pitch of the first fins 6a and noise, until the pitch of the first fins 6a becomes about 1.5 times the pitch of the second fins 6b. , The noise is reduced, above which the noise is hardly reduced.

From the above points, the pitch of the first fins 6a and the second fins 6a
The pitch ratio of b is about 1.5 times, that is, the first fin 6a
Pitch of 3 mm, the pitch of the second fin 6b is 1.8-2.0 mm
It is better to use it in some degree, and the efficiency is also improved. However, since this value changes depending on the shape of the fins, the combination with the blower, etc., it is preferable to find and use the optimum value suitable for each.

Further, as the refrigerant passage pipes 6c and 6d which are crimped to and penetrate the first fin 6a and the second fin 6b, there is a method in which both inner surface smooth tubes or inner surface grooved tubes are used. However, when both inner tubes are smooth tubes, the heat dissipation efficiency of the entire heat exchanger is reduced, and when both inner tube grooves are used, the price is high. Therefore, as described above, the first fin 6a
If an inner grooved tube having a good heat transfer coefficient is used for the pipe on the second fin 6b side in order to secure heat radiation on the second fin 6b side when frost is formed on the second fin 6b side, the heat radiation efficiency is low and the cost is low. A heat exchanger can be provided.

〔The invention's effect〕

According to the present invention, the fins of the heat pump type room air conditioner outdoor heat exchanger are divided into first fins and second fins,
The pitch of the first fin is larger than the pitch of the second fin,
By using an inner surface smooth pipe for the first fin side pipe and an inner grooved pipe for the second fin side pipe, and installing the first fin on the windward side of the blower, performance during heating operation can be improved and it is inexpensive. It is possible to provide a simple heat exchanger.

[Brief description of drawings]

Fig. 1 is an external view of an outdoor unit of a separate room air conditioner, Fig. 2 is an exploded view of Fig. 1, Fig. 3 is a characteristic diagram of a conventional air conditioner, and Figs. 4 and 5 are conventional heat exchangers. FIG. 6 is a state diagram of frost formation, FIG. 6 is a characteristic diagram of the air conditioner of the present invention, FIGS. 7 and 8 are state diagrams of frost formation in the heat exchanger of the present invention, and FIG. 9 is a first fin and a second fin. 10 is a relationship diagram between the pitch ratio and the air volume, and FIG. 10 is a relationship diagram between the pitch ratio of the first fin and the second fin and noise. 1 ... Base, 2 ... Cabinet, 3 ... Right side plate, 4
...... Left side plate, 5 ...... Compressor, 6 ...... Heat exchanger, 6a ......
1st fin, 6b ... 2nd fin, 7 ... Cycle pipe, 8 ... Electrical component, 9 ... Blower motor, 10 ...
Blower fan, 11 ... Dewdrop and frost, 12 ... Frost and ice, 12a ... Frost.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hitoshi Yamashita 800 Tomita, Ohira-cho, Shimotsuga-gun, Tochigi Prefecture Tochigi Plant, Hitachi Ltd. (56) Reference JP-A-53-80042 (JP, A) -116971 (JP, U)

Claims (1)

[Claims] 1. In an outdoor heat exchanger, a radiation fin is divided into a first fin and a second fin, a pitch of the first fin is made larger than a pitch of the second fin, and an inner surface of a pipe on the first fin side is smooth. An air conditioner in which an inner grooved pipe is used for the pipe and the pipe on the second fin side, and the first fin is installed on the windward side of the blower.