JPH08236975A - Heat exchange acceleration device - Google Patents

Abstract

PURPOSE: To provide a heat exchange acceleration device wherein strong air flow along a housing wall surface can be generated and an installation place is limited little. CONSTITUTION: Centrifugal impellers 2, 3 are attached to the inside and outside of a housing wall 1 respectively. A blade 12 of each impeller is fixed to a main board 10 which is rotated by a rotating shaft 4 passing through the housing wall 1 and is covered with a side board 14. The blade 12 has a tilting surface 13 which becomes lower toward an outer circumferential side. An inner surface 15 of the side board 14 also forms the same angle as the tilting surface 13 of the blade 12 and covers the blade 12. When an interval between an end part position on the housing wall 1 side in an air outlet of an impeller and a wall surface of the housing wall 1 is (d) and the outer diameter of an impeller is D, d/D<=0.05 for each impeller and the angle formed by the wall surface of the housing wall 1 and the inner surface 15 of the side board 14 of an impeller is in the range of 10 to 30 deg. for each impeller.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchange promoting device which is effective for efficiently dissipating the heat inside the housing to the outside in a housing having a heat source inside.

[0002]

2. Description of the Related Art Since a control panel of various machines has a portion that generates heat, it is necessary to cool the inside of the control panel to a certain temperature or lower in order to protect semiconductors and circuit boards.

The simplest cooling method for this type of housing is to replace the air inside the hot housing with air outside the cold housing. However, this method is not suitable for cooling the control panel or the like, because the inside of the housing may be contaminated by dust or oil mist contained in the outside air.

For this reason, the control panel may use a heat exchanger that only exchanges heat between the high temperature air inside the housing and the low temperature air outside the housing. Among these, some of which utilize the heat exchange function of the heat pipe are also adopted, but the entire cooling device becomes large, and it is also disadvantageous in terms of price.

Further, as a heat absorbing portion and a heat radiating portion,
There is a rotary heat exchanger that uses two rotary impellers and connects them with a heat conduction member (Jpn. Kohei 2-16195).
No., Jikken 6-4229). These rotary heat exchangers are suitable for cooling the control panel because they have a large capacity for their size and external air containing dust does not enter the inside of the housing. The recently developed rotary heat exchanger for control panel is
It has a capacity of about 40 W / ° C and can be used for a control panel having a heat source of about 1 kW or less.

[0006]

However, the rotary heat exchanger has the following problems: -The heat dissipating portion is easily polluted and the maintainability is poor. -If the impeller becomes dirty, the heat exchange efficiency will decrease. -The size of the device protruding from the housing wall is large, and the installation position is restricted when installed on an existing control panel. There are drawbacks such as.

Different from the above-mentioned heat exchanger for housing, there has been proposed a device for promoting heat exchange action through the housing wall itself. This type of heat exchange accelerating device is considered to be effective when the housing is made of metal with good heat conduction, the internal heat source is relatively small, and the housing is large (see Japanese Utility Model Publication No. 1-60597). In this device, impellers are arranged inside and outside the housing wall, and the rotating shafts of both impellers are configured by a single common rotating shaft that penetrates the housing wall. These impellers generate airflows along the inner and outer surfaces of the housing wall to increase the heat transfer rate of the housing wall from about 5 W / (m ² · ° C) to 1
It aims at the effect of increasing the temperature to 0 W / (m ² · ° C.) or more and the effect that the impeller inside the housing agitates the air inside the housing to average the temperature inside the housing.

However, this type of heat exchange promoting device has a limited range of use as described above, and has a structure and a device for generating an air flow for increasing heat transfer through the housing wall.
The shape and the structure of the impeller for downsizing the device have not yet been known.

An object of the present invention is to provide a heat exchange promoting device which can generate a strong air flow along the wall surface of the housing and has a small number of restrictions on the installation place.

[0010]

The heat exchange promoting device of the present invention has a centrifugal impeller having side plates, and the rotation axis of this impeller is perpendicular to the mounting surface. In the heat exchange promoting device thus mounted on the mounting surface, the distance between the mounting surface side end position of the air outlet of the impeller and the mounting surface is d, and the outer diameter of the impeller is D. When d
/D≦0.05, and the angle between the mounting surface and the inner surface of the impeller side plate is in the range of 10 ° to 30 °.

In the above, d / D is more preferably 0.04 or less, and the angle between the mounting surface and the inner surface of the impeller side plate is more preferably in the range of 10 ° to 25 °.

The heat exchange promoting device is preferably attached to the wall surface having the largest area among the wall surfaces of the housing.

Further, the width of the air outlet of the impeller in the direction of the rotation axis is b, the air velocity in the radial direction of the impeller is v,
When the kinematic viscosity of air is ν and the Reynolds number is Re, it is preferable that Re = bv / ν> 2 × 10 ³ .

[0014]

The heat exchange promoting device of the present invention produces a radial air flow along the wall surface. This air flow adheres to the wall surface over a wide area of about 5 to 10 times the impeller diameter due to the Coanda effect, so that the heat transfer coefficient between the wall surface and the air increases.

Since the impeller of the present invention is a centrifugal impeller, the amount of protrusion from the housing wall is small, there are few restrictions on the mounting on the housing, and it becomes a small and powerful heat exchange promoting device. .

Next, when the distance between the mounting surface side end position at the air outlet of the impeller and the mounting surface is d, and the outer diameter of the impeller is D, d / D≤0.05. A region having a large heat transfer coefficient is increased in the wall surface on which the heat exchange promoting device is attached, and heat exchange through the housing wall is promoted. d
When / D becomes larger than the above, air flows away from the wall surface and does not contribute to increasing the heat transfer coefficient of the wall surface.

Further, according to the present invention, the angle between the mounting surface and the inner surface of the impeller side plate is in the range of 10 ° to 30 °, so that the air flow velocity and the flow rate are balanced, and the air flow from the impeller is effective. To promote heat transfer from the wall surface. If the inclination angle of the inner surface of the side plate is too large, that is, if the air outlet width is too small relative to the air inlet width, the outlet flow velocity increases, but the flow resistance increases due to the increase in velocity, and the air volume decreases.

With the above structure, the air discharged from the heat exchange promoting device of the present invention has a high flow velocity and flows along the wall surface of the housing, so that the heat passage rate in the housing wall becomes large.
The capacity of the heat exchange promoting device is improved.

By mounting the heat exchange promoting device on the wall surface having the largest area among the wall surfaces in the housing, heat exchange through the housing wall can be performed more effectively.

Further, the width of the air outlet of the impeller in the direction of the rotation axis is b, the air velocity in the radial direction of the impeller is v,
When the kinematic viscosity of air is ν and the Reynolds number is Re, by configuring so that Re = bv / ν> 2 × 10 ³ , the air flow becomes turbulent, so that the heat transfer coefficient can be increased. .

[0021]

1 is a vertical sectional view showing a heat exchange promoting apparatus according to an embodiment of the present invention, and FIG. 2 is a front view showing a blade fixed to a main plate.

Impellers 2 and 3 are attached to the inside and outside of the housing wall 1, respectively. The rotary shafts of both impellers 2 and 3 are configured by a single common rotary shaft 4, and the rotary shaft 4 is the housing wall 1
It extends through the mounting hole 5 formed in the inside and outside of the housing wall 1.

The rotating shaft 4 is rotatably supported by a bearing 6, and a cylindrical main body 7a of a bearing box 7 accommodating the bearing 6 is inserted into a mounting hole 5 of the housing wall 1 and is provided on the outer periphery of the main body 7a. The formed flange 7b is fixed to the outer surface of the housing wall 1.

Next, the outer impeller 2 will be described.
The cylindrical portion 8a of the cylindrical member 8 is concentrically arranged on the outside of the cylindrical main body 7a of the bearing box 7, and projects from the bearing box 7 at the center of the bottom plate portion 8b that closes the outer end face opening of the cylindrical portion 8a. The rotary shaft 4 is fixed through, and the cylindrical member 8 is rotated together with the rotation of the rotary shaft 4.

A circular ring-shaped main plate 10 of the main plate member 9 is concentrically arranged outside the cylindrical portion 8a of the cylindrical member 8, and a cylindrical boss portion formed upright on the inner peripheral portion of the main plate 10. 11 is inserted and fixed to the outer periphery of the cylindrical portion 8 a of the cylindrical member 8. Therefore, the main plate 10 is rotated together with the rotation of the rotating shaft 4.

A plurality of blades 12 (see FIG. 2) are erected and fixed on the outer peripheral side portion of the surface of the main plate 10 opposite to the housing wall 1. These blades 12 are centrifugal blades that apply a centrifugal force to air to increase pressure and speed, and are formed in a forward direction with respect to the rotation direction (the arrow direction in FIG. 2 indicates the rotation direction). . Further, both ends of the blade 12 are formed in a straight line shape, and an intermediate portion is formed in an arc shape. By providing the straight blade portion on the outer peripheral side end portion, it is possible to obtain the action of adjusting the wind direction at the blade outlet.
The radial length of the straight blade portion is 20 to the radial length of the blade.
The range may be 40%. The outlet angle θ of the blade 12 (angle in the rotation direction between the tangent to the blade outer circle of the impeller and the blade extension line, see FIG. 2) is preferably in the range of 90 ° to 160 °. The reason for this is that the blade outlet wind speed decreases below the lower limit, and the air volume decreases below the lower limit. Further, the height of the blade 12 is formed so as to gradually decrease from the inner peripheral side toward the outer peripheral side, and the end surface of the blade 12 forms an inclined surface 13.

The blade 12 is covered with a side plate 14 on the opposite side of the main plate 10. The side plate 14 is a frustoconical plate member that covers the blade 12 portion. The inner surface 15 is a frusto-conical surface, and the inclination angle from the inner peripheral side to the outer peripheral side is the same as that of the inclined surface 13 of the blade 12. The outer surface has an inner peripheral portion formed on a flat surface 16a perpendicular to the rotary shaft 4, and the outer peripheral portion formed on a truncated cone surface 16b. The side plate 14 covers the blades 12 so as to cover the entire plurality of blades 12, and the inner surface 15 of the side plate 14 is abutted on and fixed to the inclined surface 13 of the blade 12.

Therefore, the blade 1 in the direction of the rotation axis 4
Both sides of 2 are covered with a main plate 10 and side plates 14, and an air passage 17 extending radially from the blade inlet 17a to the blade outlet 17b is formed between the blades 12. Since the cross-sectional area of the air passage 17 gradually decreases from the blade inlet 17a toward the blade outlet 17b, that is, toward the outer peripheral side, a high-speed flow can be obtained at the blade outlet 17b.
Further, an airflow is generated which is guided by the inclined inner surface 15 of the side plate 14 and goes from the blade outlet 17b to the outer surface of the housing wall 1.

The impeller 3 on the inner side of the housing wall 1 has the same structure as the impeller 2 on the outer side. However, the inner impeller 3 side is not provided with a motor or a cover described later,
The side plate 14 is composed of a frustoconical plate member having a uniform thickness. The inner impeller 3 is arranged so as to generate an air flow from the blade outlet 17b toward the inner surface of the housing wall 1.

In the present invention, the impellers 2, 3
Between the air outlet, that is, the end position of the blade outlet 17b on the housing wall 1 side and the wall surface of the housing wall 1 (the outer wall surface in the outer blade wheel 2 and the inner wall surface in the inner blade wheel 3). Where d is the outer diameter of the impellers 2 and 3, and D is the outer diameter of the impellers 2.
3, d / D ≦ 0.05, and the angle between the wall surface of the housing wall 1 and the inner surface 15 of the side plate 14 of the impellers 2 and 3 is 10 ° to 30 for each impeller 2 and 3. It is in the range of °.

The width of the air outlets of the impellers 2 and 3, that is, the blade outlets 17b in the direction of the rotation axis 4 is b, the air velocity in the radial direction of the impellers 2 and 3 is v, the kinematic viscosity of air is ν, and the Reynolds is When the number is Re, each impeller 2 and ³ is configured so that Re = bv / ν> 2 × 10 ³ , and air is blown out from each impeller 2 and 3 in a turbulent state. .

Next, a motor for rotating the impellers 2 and 3 will be described. The motor 23 is a DC brushless motor, and includes a magnet rotor 18 fixed to the side plate 14 of the outer impeller 2 and the magnet rotor 18.
Stator (driving coil) 1 that is arranged inside the machine
9 and 9. The magnet rotor 18 has a plurality of magnets 21 fixed to the inner peripheral surface of a circular ring-shaped rotor 20a arranged concentrically with the rotating shaft 4, and is formed on the inner periphery of the inner end portion of the rotor 20a. Flange 20
b is fixed to the flat surface 16a on the outer surface of the side plate 14. The stator (driving coil) 19 is fixed to the outer circumference of a circular ring-shaped fixed plate 22a arranged concentrically with the rotating shaft 4, and the flange 22b formed on the outer circumference of the outer end of the fixed plate 22a is It is fixed to a flange 24b of a cover 24 described later.

The motor 23 may be provided on the inner side of the impeller 3.

The cover 24 includes the outer impeller 2 and the motor 23.
And a flange 24b formed on the inner periphery of the outer end of the tubular portion 24a, and is fixed to the outer surface of the housing wall 1. An opening inside the flange 24b constitutes an air intake port 25, and a blowout port 26 is formed at a position facing the blade 12 in the tubular portion 24a over substantially the entire circumference.

The heat exchange promoting device is attached to the wall surface having the largest area of the wall surfaces of the housing. For example, when the housing has a rectangular parallelepiped shape, it is attached to one of the four wall surfaces having a large area.

The operation will be described below. When the rotating shaft 4 is rotationally driven by the motor 23 and both impellers 2 and 3 are rotated, air passes through the air passage 17 between the impellers 17 and 2 of the impellers 2 and 3 and passes through the inner impeller 3 Then, it is blown out in a turbulent state from the blade outlet 17b in the radial direction,
In the outer impeller 2, it is blown out in a turbulent flow state in the radial direction through the blade outlet 17b and the outlet 26.

At this time, since the cross-sectional area of the air passage 17 between the blades 12 is gradually reduced toward the outer peripheral side, the air blown out from the blade outlet 17b is blown out as a high-speed flow. Then, in the present invention, the angle between the wall surface of the housing wall 1 and the inner surface 15 of the side plate 14 of the impellers 2 and 3 is 10 ° to 3 °.
Since the range is 0 °, the air flow velocity and the flow rate are balanced, and the air flow from the impellers 2 and 3 effectively promotes heat transfer from the wall surface.

Also, since the inner surface 15 of the side plate 14 forming the air passage 17 is formed as an inclined surface which approaches the main plate 10 side toward the outer peripheral side, the air guided toward the inner surface 15 toward the housing wall 1 is formed. A flow occurs. Then, in the present invention, the distance between the wall position of the housing wall 1 and the end position on the housing wall 1 side at the air outlets of the impellers 2 and 3, that is, the blade outlet 17b is d
When the outer diameter of the impellers 2 and 3 is D, d / D ≦ 0.05
Therefore, the area of the wall surface of the housing wall 1 having a large heat transfer coefficient is increased, and heat exchange through the housing wall 1 is promoted.

Therefore, the air blown out from both impellers 2 and 3 collides with the wall surface of the casing wall 1 at a high speed in a turbulent flow and flows along the wall surface, so that it is blown out from both impellers 2 and 3. The air flow effectively increases the heat transfer coefficient of the wall surface and increases the heat transmission rate in the housing wall 1. Therefore, the heat inside the housing is efficiently radiated to the outside through the housing wall 1.

Two tests conducted to clarify the effect of the present invention will be described below.

(Test 1) A 1.4 m × 1.4 m steel plate was used as a test wall surface. On the wall surface under test, a heater with adjustable electric power is bonded to the center of one surface, and a temperature sensor is bonded to both surfaces. Next, various heat exchange accelerating devices having different ratios (d / D) of the distance d between the end position on the mounting surface side at the air outlet and the mounting surface and the outer diameter D of the impeller are used. It was attached to the central part and the heat exchange promoting device was operated while heating one side with a heater, and the temperature difference between both sides was measured. Regarding the heat exchange amount in the test, the electric power of the heater was adjusted so that the temperature difference between both surfaces of the sample wall surface in the equilibrium state was kept constant, and the heater electric power at that time was taken as the heat exchange amount.

The specifications of the impeller used are as follows. Rotation speed: 2000 rpm Impeller shaft axial length: 20 mm Blade outer diameter: 200 mm Blade inner diameter: 108 mm Number of blades: 24 Angle β: 15 °

The results are shown in Table 1.

[0044]

Table 1 shows the ratio (d / d) of the distance d between the mounting surface side end position of the air outlet and the mounting surface and the outer diameter D of the impeller.
D) of 0.05 or less shows a large heat exchange amount, which is advantageous. Further, it can be seen that when it exceeds 0.04, the heat exchange amount is greatly reduced.

(Test 2) Inclination angle β of the inner surface of the impeller side plate
In order to know the effect of the heat transfer amount on the heat transfer amount, the amount of heat exchange was measured by the same method as in Test 1 using the impeller in which the inner surface of the side plate had various inclination angles.

The specifications of the impeller used are as follows. Rotational speed: 2310 rpm Impeller air outlet width: 8 mm Blade outer diameter: 200 mm (b / D): (8/200) Blade inner diameter: 108 mm Number of blades: 24 Edge position and mounting surface at air outlet Distance d: 7.5 mm

The results are shown in Table 2.

[0049]

Table 2 shows that when the inclination angle β of the inner surface of the impeller side plate is in the range of 10 ° to 30 °, the amount of heat exchange is large, which is advantageous. Further, the inclination angle β is 10 ° to
It can be seen that when the temperature exceeds the range of 25 °, the heat exchange amount greatly decreases.

[0051]

As described above, the heat exchange promoting device of the present invention can generate a strong air flow along the wall surface of the housing.
Since it can be made small, there are few restrictions on the installation place.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a heat exchange promotion device according to an embodiment of the present invention.

FIG. 2 is a front view showing a blade fixed to a main plate.

[Explanation of reference numerals] 1 housing wall 2, 3 impeller 4 rotating shaft 5 mounting hole 6 bearing 7 bearing box 7a bearing box body 7b flange 8 cylindrical member 8a cylindrical portion 8b bottom plate portion 9 main plate member 10 main plate 11 boss portion 12 blades 13 inclined surface 14 side plate 15 inner surface 16a flat surface 16b frustoconical surface 17 air passage 17a blade inlet 17b blade outlet 18 magnet rotor 19 stator (driving coil) 20a rotor 20b flange 21 magnet 22a fixed plate 22b flange 23 motor 24 cover 24a tube Part 24b Flange 25 Inlet 26 Outlet

Claims (3)

[Claims] 1. A heat exchange accelerating device having a centrifugal impeller having side plates, the impeller being attached to a mounting surface such that a rotation axis of the impeller is perpendicular to the mounting surface. When the distance between the end surface of the air outlet of the impeller on the side of the mounting surface and the mounting surface is d and the outer diameter of the impeller is D,
d / D ≦ 0.05, and the angle between the mounting surface and the inner surface of the impeller side plate is 10 ° to
A heat exchange promoting device characterized by being in a range of 30 °. 2. The heat exchange promoting device according to claim 1, wherein the mounting surface is a wall surface having the largest area among the wall surfaces of the housing. 3. When the width of the air outlet of the impeller in the rotational axis direction is b, the air velocity in the radial direction of the impeller is v, the kinematic viscosity of air is ν, and the Reynolds number is Re, R
The heat exchange promoting device according to claim 1, wherein e = bv / ν> 2 × 10 ³ .