JPH02238272A - Laminated type evaporator - Google Patents

Abstract

PURPOSE:To disperse an overheating region and to improve thermal exchanging efficiency by disposing the downstream end regions of U-shaped and inverted U-shaped flat passages at the same side with respect to air passing direction to an evaporator. CONSTITUTION:A refrigerant distribution passage 14 composed of a series of tanks 13 is split into upper and lower passages of disposition of U-shaped and inverted U-shaped tubes 10a, 10b, refrigerant is split into upper and lower air discharge sides to an evaporator body. The refrigerants finished to evaporate while being introduced from a rear face to a front face with respect to an air flow via the tube elements 10 are again gathered by a refrigerant collecting passage 15 split into upper and lower air flow sides of tube element disposition formed of tanks 13 group, and sucked into a compressor through upper and lower branch tubes 34 opposed to the inlet side branch tube and refrigerant discharge tubes 6. In this case, the overheating regions of the elements are dispersed vertically and laterally to eliminate irregular thermal distribution of the evaporator to be entirely made uniform. Thus, the thermal exchanging efficiency can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a stacked evaporator such as an evaporator used, for example, in an automobile air conditioner.

(Prior art) In order to increase the capacity of a heat exchanger, the fluid is divided into thin tubes and passed through them. This increases the surface area and shortens the distance from the center of the fluid to the tube wall, increasing heat exchange efficiency. This is commonly done.

In the laminated heat exchanger used in the evaporator of an automobile air conditioner, the above-mentioned effect is obtained by dividing the heat into mainly about 8 to 10 parts inside the exchanger.

However, increasing the number of branched flows causes uneven flow, creating areas where the flow becomes difficult and resulting in a deterioration of the overall heat distribution.

Therefore, before the refrigerant enters the evaporator main body, the refrigerant distribution channel is divided into two, and the number of branches handled by each distribution channel is not increased, but by doubling the overall number of branches, Measures have been taken to increase heat exchange efficiency while preventing uniform distribution.

The refrigerant is evaporated inside the evaporator, and the heat of evaporation cools the air passing through it. The temperature in the refrigerant evaporation section of the evaporator is approximately 0°C, and the heat distribution is good.

by the way. The area near the refrigerant outlet of the evaporator is the overheating area (
The temperature of this part is set at 5 to 10 degrees Celsius because it is necessary to completely vaporize the refrigerant. Where in the evaporator this overheating area is located greatly affects the overall heat distribution, and ultimately the temperature distribution and cooling temperature of the air supplied to the vehicle.

An example of a conventional stacked evaporator with two flow paths is disclosed in Japanese Patent Application Laid-Open No. 82-119373. The overheating region of this evaporator is shown by the shaded area in FIG.

(Problems to be Solved by the Invention) In the case of automobile evaporators, unlike those for home use, there are changes in compressor rotation speed due to changes in engine rotation speed, changes in the speed and volume of condenser cooling air due to changes in vehicle speed, and changes in condenser cooling air. Because it is subject to large disturbances such as wind temperature changes, the temperature control range of the expansion valve may sometimes be exceeded, and the degree of superheat may further increase. In this case, the air that has passed through the overheated area is not cooled sufficiently and is rapidly mixed with the air that has passed through areas other than the overheated area on the air outlet side of the evaporator. At this time, the moisture contained in the air that passes through the superheated region, which is hotter and more humid than the air that has passed through other parts, condenses, causing a problem in which mist-like air called white smoke is supplied into the vehicle.

Therefore, an object of the present invention is to provide a novel stacked evaporator that eliminates the above-mentioned problems.

(Means for solving the problems by the invention) The stacked evaporator of the present invention is as follows. A first tube element having a refrigerant inlet and a refrigerant outlet at one end, and a U-shaped flat flow path communicating between the two. A large number of second tube elements each having a refrigerant inlet and a refrigerant outlet at the other end and forming an inverted U-shaped flat flow path communicating these inside are stacked and welded together at least every other. Then,
It is characterized in that the downstream end regions of the U-shaped and inverted U-shaped flat channels are arranged on the same side with respect to the evaporator in the air passage direction.

Each refrigerant inlet and each refrigerant outlet of the first tube element are communicated with each other through an enlarged portion, and a refrigerant distribution path and a refrigerant collection path are formed in the stacking direction on the one end side. Each refrigerant inlet and each refrigerant outlet of the second tube element are communicated through an enlarged portion, and a refrigerant distribution path and a refrigerant collection path are formed in the stacking direction on the other end side, and each of the refrigerant distribution paths on both ends It is preferable that a refrigerant inlet pipe is connected to the passage, and a refrigerant discharge pipe is connected to each of the collecting passages on both ends.

Preferably, the refrigerant distribution channels on both ends are formed on the air outflow side of the evaporator.

Furthermore, the refrigerant introduction pipe arranged on the air inflow side of the evaporator passes through the evaporator at the center of the evaporator and is branched to each refrigerant distribution path formed at both ends of the air outflow side of the evaporator. In addition, a refrigerant discharge pipe disposed close to the refrigerant introduction pipe on the air inflow side of the evaporator can be branched and connected to each refrigerant collection path formed at both ends of the air inflow side of the evaporator.

Furthermore, it is also preferable that the cross-sectional area of the flat flow path of the first and second tube elements is set to 1/2 of the cross-sectional area of the flat flow path in the case where the refrigerant distribution path and the refrigerant collecting path are not divided into two.

Regarding the arrangement of the tube elements, it is possible to arrange the first and second tube elements alternately. It is also possible to arrange a second tube element for every second element.

(Function) The refrigerant introduced into the upper and lower distribution channels from the refrigerant introduction pipe flows through the U-shaped tubes assigned to each distribution channel, where the refrigerant evaporates and the air is cooled by the heat of evaporation. Since the first and second tube elements are arranged alternately, the overheating area of each tube element is distributed vertically and horizontally (see the shaded area in Figure 5). This eliminates the uneven distribution of heat in the evaporator and makes it uniform throughout.

In addition, in this arrangement, overheating areas and non-overheating areas exist adjacent to each other alternately. A stable refrigeration cycle can be performed by suppressing further overheating caused by external disturbances.

The expanded portion may be constituted by a tank portion that projects from one end of the tube element in the stacking direction of the tube elements and is integrally formed with the tube element.

Furthermore, by connecting the tank parts and arranging the first and second tube elements, refrigerant distribution paths can be formed at both ends of the evaporator, and these distribution paths can be placed on the air outflow side of the evaporator. preferable.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. 1st
The figure is an external view of the laminated evaporator of this embodiment.

This evaporator 20 includes a tube element 10,
A large number of bellows-shaped corrugated fins 27 are connected alternately,
It is a laminated type with side plates 2 attached to both ends.

One tube element, that is, the U-shaped tube 10a
As shown in Fig. 8, is a flat tube plate member made by laminating two main plates 1, which have an extremely shallow tray shape as a whole, in a skin shape in the middle. A U-shaped flow path 9 is formed by a partition wall 30 that divides the protruding space into two, leaving a portion of the space.

As shown in FIG. 3, the main plate 1 has a refrigerant inlet 7 and a refrigerant outlet 8 on its end side, which are communicated through the U-shaped passage 9. Reference numeral 11 denotes a group of small ribs oriented obliquely to give the refrigerant flow path a labyrinth shape and improve heat exchange efficiency.

A plate 1 connected to the inlet port 7 and the outlet port 8, respectively.
Projections 12 are defined at the upper end in the stacking direction, and two tanks 13a are formed by bonding plates together.

Further, on the other end side of the plate 1, two tanks 13b are formed by bonding the plates 1 together, separated from the U-shaped flow path 9, with the same configuration as described above.

The second tube element, namely the inverted U-shaped tube 10
b can be constructed by arranging this tube element 10a upside down. As a result, the refrigerant inlet and outlet are moved to the lower side, the lower tank is moved to the upper side, and the U-shaped flow path is formed into an inverted U-shape.

These one and two tube elements lOa and lOb
are arranged adjacent to each other alternately as shown in FIG.

There is one through hole on each tank side of the tube element.
2a and 12b' are opened and the side surfaces of adjacent tanks are bonded to each other, so that a refrigerant distribution path l4 and a refrigerant collection path l5 are respectively formed by the tank 13 on the upper and lower end sides of the evaporator. These refrigerant flow paths l4 and 15 are such that the distribution path 14 is on the downstream side with respect to the air flow direction 16, and the collecting path l4 is on the downstream side with respect to the air flow direction 16.
5 is placed on the upstream side.

The flow path configuration of this tank is as follows. Since the flow path diameter is very large compared to other flow paths, the flow path resistance is so small that it does not pose a problem, and this does not alienate the flow of the fluid and cause non-uniform flow.

The side plate 2 is a plate member that protects both ends of the evaporator, and its -1 lower end step portion 2a constitutes a mounting portion for a refrigerant introduction and discharge block. A through hole is provided on one side corresponding to the refrigerant flow path connection of the introduction/discharge block.

The refrigerant introduction pipe 5 is connected to the evaporator 2 as shown in FIG.
0, its passage portion 5a passes through the corrugated fin portion of the evaporator 20, and its tip portion 5b
is connected to the upper and lower branch pipes 31 via a refrigerant dividing section 28 arranged on the air outflow side.

The tips of the upper and lower branch pipes 31 are connected to refrigerant introduction blocks 3a and 3b, respectively, and the insides of these blocks 3a and 3b are communicated with upper and lower distribution channels 14 located on the air outflow side through through holes 32 and 33, respectively. ing.

The passage portion 5a is pressed into a rectangular tube shape, and each side thereof is in close contact with the corrugated fins 27 and the tube element 10. This eliminates gaps, preventing cooling air from leaking, and allows for stronger brazing compared to round pipes.

The refrigerant introduced from the refrigerant introduction pipe 5 is divided into two into upper and lower distribution passages 14 by the dividing portion 28 and the upper and lower branch pipes 31.

With a similar configuration, as shown in FIG.
Upper and lower refrigerant collecting passages 15 located on the air inflow side via 4
It is connected to the.

FIG. 7 shows another embodiment of the piping, in which the inlet pipe that wraps around the rear (air outflow side) in FIG. 1 is placed on the same front (air inflow side) as the discharge pipe.

In FIG. 7(A), the vibrator 51 in the refrigerant introduction part is bent at the front end of the evaporator via the horizontally bent part 51a, so the air flow 1B toward the cooling core is not alienated. However, the overall external size of the evaporator becomes larger.

Figure 7(B) is. It differs from the one shown in FIG. 7'(A) in that a vertically bent portion 52a is used, and in this case, although the external shape is not increased, the air flow is somewhat restricted.

In FIG. 7(C), piping 58 is installed from outside the cooling core area in order to avoid alienation of air flow. In this case, although the above-mentioned alienation avoidance is achieved, the overall size tends to become larger.

In manufacturing the evaporator 20 having the above structure, each component is formed by pressing a thin metal plate such as aluminum with good thermal conductivity, the surface is coated with a brazing material in advance, and the piping is connected. Each component is joined together by temporarily assembling each component, and then fixing this state with a jig and placing it in a brazing furnace heated to the melting temperature of the brazing material (e.g. around 600℃). It is.

(Effects of Example) Figure 3N2 shows the flow of refrigerant. After passing through the receiver, the liquid refrigerant condensed by the condenser is introduced into the evaporator through an expansion valve. Here, refrigerant is introduced into the evaporator main body from the front side in the air flow direction 16 through the refrigerant introduction pipe 5 that goes around the rear side. A refrigerant distribution path 14 constituted by a series of tanks l3 includes a U-shaped tube 10a.
The refrigerant is divided into upper and lower parts due to the arrangement of the and inverted U-shaped tubes 10b, and the refrigerant is divided into two systems, upper and lower, on the rear side (air outflow side) in the figure, and flows into the evaporator main body. The evaporator main body is constructed by alternately connecting tube elements IO and corrugated fins 27, which are formed with the main plate 1 facing each other, and the refrigerant is evenly distributed to the tube elements in charge of each distribution path. The air flows through the ribbed interior and evaporates, and the latent heat of evaporation is removed from the air through the corrugated fins 27. This cools the air.

The evaporation temperature of the refrigerant is usually set around θ°C to prevent the evaporator from freezing.

The refrigerant that has finished evaporating while being guided from the rear to the front with respect to the air flow by the tube element 10 is transferred to the tank 13.
A refrigerant collection path 1 formed by a group and divided into upper and lower sections on the front side (air inflow side) by the tube element arrangement configuration.
5, the refrigerant is collected again by the refrigerant discharge pipe 6 through the upper and lower branch pipes 34 facing the inlet branch pipe, and is sucked into the compressor by the refrigerant discharge pipe 6.

The refrigerant outlet temperature is set by an expansion valve (not shown) to be 5 to 10° C. higher than the evaporation temperature in order to prevent liquid compression in the compressor.

FIG. 5 shows the distribution of overheated regions 17 (shaded areas). 16 indicates the air flow direction, and the illustration shows that the air flow is from the front side to the back side of the drawing.

The refrigerant introduced into the lower distribution path 14b from the upper and lower branch pipes 31 flows into each inverted U-shaped tube fob with which this distribution path 14b and the inlet 7 communicate. The refrigerant in this tube 10b circulates from the lower part of the back surface to the upper part in FIG.
A lower collecting passage 15b that flows out from the drain port 8 and communicates with these discharge ports 8
are collected in. The vicinity of each discharge port 8 forms a superheating region 17b, and these superheating regions 17b are connected to the inverted U-shaped tube 10b.
It is distributed to the left and right at the bottom of the evaporator.

Similarly, the refrigerant introduced into the upper distribution path L4a is passed from this distribution path 14a through the inlet 7 to each U-shaped tube l.
Flows into the tube lOa, flows from the upper part of the back side to the lower part in Fig. 5, and from the lower part of the back side to the lower part of the front side,
Further, it moves to the upper part of the surface, flows out from the discharge port 8, and is collected in the upper collection path 15a.

The vicinity of the discharge port of the U-shaped tube 10a forms overheating regions 17a, and these overheating regions 17a are distributed to the left and right in the upper part of the evaporator by the U-shaped tube 10a.

The flat channel overheating area of each tube element is formed into an overheating area and a non-overheating area alternately depending on the arrangement of these tube elements.

(Effects of the Invention) The stacked evaporator of the present invention can distribute the superheated region by the arrangement of the tube elements, thereby achieving uniform air cooling, and alternately divides the superheated region and non-superheated region. Excessive overheating can be suppressed by forming an arrangement.

In addition, since this evaporator has a configuration in which the refrigerant is introduced in two parts, twice the number of divided flows than before is ensured without causing uneven flow, and the heat exchange efficiency of the refrigerant can be greatly increased. At the same time, the flow path resistance is also significantly reduced.

Furthermore, according to the evaporator of item 5, in addition to the above effects, the film heat transfer coefficient can be increased.

When the refrigerant is introduced in two parts and the flow rate is constant, the flow rate of the refrigerant flowing inside the tube is 1/2. When the flow rate becomes 1/2, the film heat transfer coefficient tends to decrease. Therefore, the above-mentioned problem can be solved by reducing the cross-sectional area of the flat flow path to 1/2, thereby keeping the flow velocity the same.

This makes it possible to further improve heat exchange efficiency.

[Brief explanation of drawings]

Figure 1 is an external view of a stacked evaporator showing an embodiment of the present invention, Figure 2 is a diagram showing the flow of refrigerant in the evaporator, Figure 3 is a front view of the main plate,
(A) is a sectional view common to the A-A line and C-C line in FIG. 3, FIG. 4(B) is a sectional view taken along the B-B line in FIG. 3, and FIG. Figure 6, a partially omitted front view of the evaporator showing the distribution of the overheating area (hatched area), shows the distribution of the overheating area (shaded area) of the conventional overheating area (
Fig. 7 shows another embodiment of the piping, and Fig. 7(A) shows the horizontally bent part.
) Figure shows an example in which connections are made using vertical bends, Figure 7 (C) shows an example in which connections are made from outside the cooling core area without using bends, and Figure 8 shows an example in which connections are made from outside the cooling core area without using bends. FIG. 9 is an exploded view of the U-shaped tube, and an exploded view showing the connection configuration of the introduction pipe. 1... Main plate 5... Refrigerant inlet pipe 10... Tube element l3... Tank ■5... Refrigerant collection path 27... Corrugated pipe 2... Side plate 6... Refrigerant discharge Pipe l4... Refrigerant distribution line l7... Overheating area No. 3 (2I) Figure 8

Claims (5)

[Claims] (1) A first tube element having a refrigerant inlet and a refrigerant outlet at one end and a U-shaped flat flow path communicating between them, and a refrigerant inlet and a refrigerant outlet at the other end. A large number of second tube elements each having an inverted U-shaped flat channel having an outlet and communicating with each other are stacked and welded together at least every other. U
1. A stacked evaporator characterized in that the downstream end regions of the letter-shaped flat channels are arranged on the same side of the evaporator in the air passage direction. (2) Each refrigerant inlet and each refrigerant outlet of the first tube element are connected to each other via an enlarged portion, and a refrigerant distribution path and a refrigerant collection path are formed in the stacking direction on the one end side, and Each refrigerant inlet and each refrigerant outlet of the second tube element are communicated through an enlarged portion, and a refrigerant distribution path and a refrigerant collection path are formed in the stacking direction at the other end side, and each distribution path at both ends is connected to each other through an enlarged portion. 2. The laminated evaporator according to claim 1, wherein the refrigerant inlet pipe is connected to each of the collecting passages on both ends of the refrigerant discharge pipe. (3) The stacked evaporator according to claim 1 or 2, wherein each of the refrigerant distribution channels on both end sides is formed on an air outflow side of the evaporator. (4) The refrigerant introduction pipe arranged on the air inflow side of the evaporator passes through the evaporator at the center of the evaporator and branches into each refrigerant distribution path formed at both ends of the air outflow side of the evaporator. 3. A refrigerant discharge pipe arranged close to the refrigerant introduction pipe on the air inflow side of the evaporator is branched and connected to each refrigerant collection path formed on both ends of the air inflow side of the evaporator. The stacked evaporator described. (5) The cross-sectional area of the flat flow path of the first and second tube elements is set to 1/2 of the cross-sectional area of the flat flow path in the case where the refrigerant distribution path and the refrigerant collection path are not divided into two. The stacked evaporator described.