JPS6139593B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of an evaporator for a refrigerator that is subject to frost formation.

An evaporator is installed as part of the refrigeration cycle in refrigerators, freezers for storing food at low temperatures, and refrigerators in low-temperature air conditioners. Because it is used in the following, it is accompanied by frosting phenomenon. For this reason, in addition to the refrigerant pipes and fin cooling equipment, a defrosting device using a defrosting heater is incorporated to prevent increases in ventilation resistance and thermal resistance due to frost formation. The structure must be designed so that the entire evaporator can be defrosted uniformly, the surrounding area can be heated by heat loss caused by the heater, and no local residual frost can be formed.

The forced draft type evaporator for refrigerators, which has been widely used in the past, consists of a cross-finch tube heat exchanger with hairpin-shaped pipes passed through a group of parallel fins, with heaters installed on both sides. This conventional example will be explained with reference to FIGS. 1 to 4. 1 is a long fin, 2 is a short fin, and 3 is a cylindrical shape provided on the long fin 1 and the short fin 2. , 4 is a U-shaped groove cut into the long fin 1 and short fin 2, 5 is a hairpin-shaped tube, 6 is a U-shaped tube, and 7 is a heater tube that generates heat inside. A line (not shown) is incorporated. Reference numeral 8 indicates a plug for preventing moisture from entering into the heater tube 7 during defrosting, 9 is a lead wire, 10 is an inner wall of the refrigerator around the evaporator, and 11 is a partition plate inside the refrigerator.

To construct an evaporator using these parts, first, the long fins 1 and the short fins 2 are arranged alternately so that the fin pitches are coarse on the airflow inflow side and dense on the airflow inflow side. A hairpin-shaped tube 5 is passed through the collar 5, and a U-shaped tube 6 is welded to the end face of the collar 5, so that the refrigerant flow path inside the tube is configured to be meandering. Thereafter, the heater tube 7 is bent into a serpentine shape so that the airflow inflow side is dense and the airflow outflow side is rough, and it is press-fitted into the U-shaped groove 4 to complete the process.

In such an evaporator, the long fins 1 and the short fins 2 must be arranged alternately, which makes automation difficult, and the fins 1 and 2 are arranged closer to the airflow outlet than the airflow inflow side. Since the fins are continuous, a temperature boundary layer develops between the fins, and the heat transfer coefficient on the air side becomes disadvantageous. Further, since the hairpin tube 5 and the U-shaped tube 6 are welded, problems such as an increase in the number of machining steps, quality control in production due to poor machining, and a shortened service life due to corrosion are caused, which is further disadvantageous.

On the other hand, the heater tube 7 has a complicated meandering structure with sparse and dense pipe pitches, which increases the overall length, makes it difficult to work, and increases production costs.Also, because it is constructed around the outer periphery of the evaporator, In addition to heating the fins 1 and 2 during defrosting, the air around the evaporator is heated which causes heat loss, which increases the temperature of the food during defrosting, causing quality deterioration, and the extra heat required for recooling. There was a defect that required refrigeration capacity.

The present invention has been made to improve the above defects.

That is, the small piece fins are inserted into the meandering refrigerant pipe and the heater pipe, and the insertion pitch of the small piece fins is made rough on the airflow inflow side and dense on the airflow outflow side, and the insertion pitch of the small piece fins is made coarse on the airflow inflow side and dense on the airflow outflow side, and This evaporator for a refrigerator is characterized in that the heater wattage is high on the airflow inflow side and low on the airflow outflow side.

An embodiment of the present invention will be described with reference to FIGS. 5 to 10. Reference numeral 12 indicates a small piece fin, 13 a cylindrical collar formed on the small piece fin 12, and 14 a U-shaped collar formed on the small piece fin 12. In the groove, the collar 13 and the U-shaped groove 14 are arranged in the same row. Reference numeral 15 represents a refrigerant pipe, and reference numeral 16 represents a heater pipe, within which heating wires (not shown) are installed with the wattage being partially varied. 17 is a waterproof plug at the end of the heater tube 16; 18 is a lead wire connected to the heating wire;
19 is a side plate.

To construct the evaporator of the present invention using such parts, first arrange the small fins 12 with a gap of the required size for the meandering of the refrigerant pipe 15 and the heater pipe 16 as shown in FIG. They are arranged in advance so that they are coarse on the airflow inflow side and gradually denser on the airflow outflow side.

Furthermore, the refrigerant pipe 15 is passed through the collar 13, and at the same time, the heater pipe 16 is press-fitted into the U-shaped groove 14. Here, the refrigerant pipes 15 and the heater pipes 16 in the non-arranged portions of the small piece fins 12 are alternately bent into a meandering shape and the side plates 19 are attached. When a concave surface is provided on the inner wall 10 in order to increase the airflow resistance and reduce ventilation resistance due to frost formation, the gap between the small piece fins 12 is made large on the inflow side and the gap between the small piece fins 12 is made large on the inflow side and Although attempts have been made to make the frost distribution uniform by gradually decreasing the frost distribution, it is insufficient, and in order to compensate for this and achieve uniform defrosting, it is necessary to change the heat generation distribution of the heater tube 16. Since the structure of the heater tube 16 according to the present invention has the same number of heater tubes 16 in each stage, it is difficult to use conventional means, and it is difficult to achieve the purpose by changing the wattage of the internal heating wire. The airflow inlet side has a high wattage, the opposite side has a low wattage, and the opposite side has a low wattage in proportion to the frost distribution. Especially from the coarse entrance of the fin pitch to the first stage where the fin pitch becomes denser, and the inner wall 1.
If 0 constitutes a concave surface, frost formation will be large up to the height of the concave surface, and it will be necessary to generate heat at a high wattage.

The evaporator configured as described above has a small piece fin 1.
2 does not require two types of long fins 1 and short fins 2 as in the conventional example described above (in some cases, two or more types are required).
It is possible to configure coarse and dense fin pitches with only the arrangement of fins 2 and 2. Moreover, it is possible to freely configure many types of fin pitches using the same type of small piece fins 12. The typical heat transfer dimensions of the fins 12 are narrow, the development of a temperature boundary layer is small, and the heat transfer coefficient on the air side can be increased.

In addition, the refrigerant pipe 15 has no welded parts, which is advantageous in terms of man-hours, quality control, and service life.

Since the heater tube 16 is placed in the center of the evaporator, there is less heating of the air around the inside of the freezer, which prevents deterioration of food quality and loss of refrigerating capacity, and the simple bending structure of the heater tube 16 ensures uniform heating. It has a low material cost, is easy to process, and can reduce cost.

On the other hand, when used in low-temperature air conditioners, U
In many cases, the rising edge of the groove 14 is made flat to allow the airflow to pass from the direction B. In this case, the frost distribution will be uniform in each stage, the fin pitch can be the same in all stages, and the heater wattage can be made uniform, so it is possible to use a wide variety of It has a wide range of applications and is extremely effective as an evaporator for refrigerators.

[Brief explanation of the drawing]

Figure 1 is a front view of a long fin of a conventional evaporator, Figure 2 is a front view of a short fin, and Figure 3 is a front view of a long fin of a conventional evaporator.
4 is a side view of the conventional evaporator, FIG. 5 is a front view of the fin of the evaporator of the present invention, FIG. 6 is a side view of FIG. 5, and FIG. 7 is a front view of the conventional evaporator. 8 is a front view of the evaporator of the invention, FIG. 9 is a side view of FIG. 8, and FIG. 10 is an illustration of another embodiment of the evaporator of the invention. It is a front view. 1... Long fin, 2... Short fin, 3... Collar, 4... U-shaped groove, 5... Hairpin-shaped tube, 6... U
Shape tube, 7... Heater tube, 8... Plug, 9... Lead wire, 10... Inner wall, 11... Partition plate, 12... Small piece fin, 13... Collar, 14... U-shaped groove, 15... Refrigerant pipe, 16... Heater tube, 17...plug, 18...lead wire, 19...side plate.

Claims (1)

[Scope of Claims] 1. A small piece fin inserted into a meandering refrigerant pipe and a heater pipe, and the insertion pitch of the small piece fin is made rough on the airflow inflow side and dense on the airflow outflow side. An evaporator for a refrigerator, characterized in that the heater wattage of the heater tube is high on the airflow inflow side and low on the airflow outflow side. 2 The airflow is blown in a direction perpendicular to the meandering direction of the refrigerant pipe 15 and the heater pipe 16 and parallel to the surface of the small piece fin 12. In this case, the heating wire watt density is uniform in each stage, and the small piece fin The evaporator for a refrigerator according to claim 1, wherein the 12 fin pitches are also the same.