阅读说明：本技术 一种电子设备 (Electronic equipment ) 是由 徐麟 于 2020-12-23 设计创作，主要内容包括：本发明的实施例提供了一种电子设备,包括：壳体,所述壳体内装设发热元件,所述壳体表面开设进风口和出风口,所述进风口和出风口分别位于所述发热元件相对的两侧；一对离心风扇,相互独立运转的一对离心风扇对称地设置于所述发热元件的同一侧,且与所述进风口位于所述发热元件的同一侧,一对离心风扇的出风方向朝向所述出风口、并且于发热元件的表面相交形成第一夹角,以汇聚形成覆盖所述发热元件的表面的散热气流,所述散热气流的方向关联于一对离心风扇的出风量。(An embodiment of the present invention provides an electronic device, including: the heating device comprises a shell, a heating element is arranged in the shell, an air inlet and an air outlet are formed in the surface of the shell, and the air inlet and the air outlet are respectively positioned on two opposite sides of the heating element; the centrifugal fans which run independently are symmetrically arranged on the same side of the heating element, the centrifugal fans and the air inlet are positioned on the same side of the heating element, the air outlet directions of the centrifugal fans face the air outlet and form a first included angle by intersecting the surface of the heating element so as to converge to form heat dissipation airflow covering the surface of the heating element, and the direction of the heat dissipation airflow is related to the air outlet amount of the centrifugal fans.)

1. An electronic device, comprising:

the heating device comprises a shell (10), wherein a heating element (1) is arranged in the shell (10), an air inlet (11) and an air outlet (12) are formed in the surface of the shell (10), and the air inlet (11) and the air outlet (12) are respectively positioned on two opposite sides of the heating element (1);

the pair of centrifugal fans (21,22) which run independently are symmetrically arranged on the same side of the heating element (1), and are located on the same side of the heating element (1) with the air inlet (11), the air outlet direction of the pair of centrifugal fans (21,22) faces the air outlet (12) and forms a first included angle in the surface intersection of the heating element (1) so as to converge to form a heat dissipation airflow (3) covering the surface of the heating element (1), and the direction of the heat dissipation airflow (3) is related to the air outlet amount of the pair of centrifugal fans (21, 22).

2. The electronic device of claim 1, further comprising a scroll (30), the scroll (30) being mounted within the housing (10), the scroll (30) comprising:

the centrifugal fan comprises a pair of fan cavities (31), wherein one centrifugal fan is arranged in each fan cavity (31), and each fan cavity (31) is provided with a fan air inlet (32) arranged on one side of the centrifugal fan in the axial direction;

a connecting portion (33), wherein the connecting portion (33) is arranged between the pair of fan cavities (31) so as to connect the pair of fan cavities (31) into a whole; and

each air outlet channel (34) is communicated with a corresponding fan cavity (31) in the circumferential direction of the centrifugal fan (21,22), each air outlet channel (34) is provided with a fan air outlet (35) arranged on the end face of the connecting portion (33), and the central axes of the air outlet channels (34) intersect on the surface of the heating element (1) to form a first included angle.

3. The electronic device of claim 2, wherein the scroll (30) further comprises:

and the backflow preventing flange (36) extends outwards from the end face of the connecting part (33) to abut against the inner surface of the shell (10).

4. Electronic device according to claim 3, characterized in that the cavity inside the housing (10) is divided into a front cavity (1a) and a back cavity (1b) by a backflow prevention collar (36),

the centrifugal fans (21,22) and the air inlet (11) are positioned in the front cavity (1a), and the heating element (1) and the air outlet (12) are positioned in the rear cavity (1 b).

5. The electronic device according to any of claims 2 to 4, wherein the axis of the centrifugal fan (21,22) is perpendicular to the bottom surface of the housing (10).

6. The electronic device according to claim 5, wherein the air inlet (11) opens at a bottom surface of the housing (10),

the fan air inlet (32) is formed in the bottom surface of the fan cavity (31) and aligned with the air inlet (11).

7. The electronic device according to claim 5, wherein the air inlet (11) opens at a side wall of the housing (10),

the fan air inlet (32) is arranged on the top surface of the fan cavity (31), and the bottom surface of the fan cavity (31) is attached to the bottom surface of the shell (10) inside the shell (10).

8. The electronic apparatus according to claim 2, wherein the scroll (30) includes a scroll upper cover (30a) and a scroll lower cover (30b) which are fitted to each other along an axial direction of the centrifugal fan (21, 22).

9. The electronic device of claim 1 or 2, wherein the first angle is in a range of 30 ° to 120 °.

10. Electronic device according to claim 1, characterized in that the air output of the centrifugal fan (21,22) is related to the rotational speed and/or rotational direction of the centrifugal fan (21).

Technical Field

The present invention relates to the field of electronic devices.

Background

With the progress of the industry, small server devices are continuously developed in the directions of high intelligence, high power consumption, miniaturization and high integration, and the heat dissipation problem of the small server devices is often an important concern in the reliability design of the whole machine. The main conventional heat dissipation method of such product form is to actively dissipate heat by using a fan.

Currently, axial flow or centrifugal fans are generally used for driving ambient air to enter and exit the cavity of the equipment in active heat dissipation, and the flowing air carries heat away from the equipment after passing through a heat sink contacted with a heat source. When the mode is used for heat dissipation, the equipment is usually provided with an air inlet and an air outlet, the fans control the rotating speed in a unified mode, the fan walls are formed by the multiple fans, the whole cavity is blown or drafted by the aid of the multiple fans side by side, air flow is guided by the aid of structures such as the air guide cover, and heat of a heating source in a specific area is dissipated in a centralized mode. The mode needs a plurality of fans, the rotation directions of the fans are basically uniform, the rotation directions of the fan blades are the same, the generated air flow deviates to one side, an air guide cover is additionally arranged for guiding the air, the cost is high, and the flexibility is poor.

Disclosure of Invention

In view of the above, an object of the present invention is to provide an electronic apparatus, which can control the direction of the heat dissipation airflow only by controlling the rotation speed of the fan, without additionally providing a wind scooper with a complicated structure.

One embodiment of the present invention provides an electronic device including:

the heating device comprises a shell, a heating element is arranged in the shell, an air inlet and an air outlet are formed in the surface of the shell, and the air inlet and the air outlet are respectively positioned on two opposite sides of the heating element;

the centrifugal fans which run independently are symmetrically arranged on the same side of the heating element, the centrifugal fans and the air inlet are positioned on the same side of the heating element, the air outlet directions of the centrifugal fans face the air outlet and form a first included angle by intersecting the surface of the heating element so as to converge to form heat dissipation airflow covering the surface of the heating element, and the direction of the heat dissipation airflow is related to the air outlet amount of the centrifugal fans.

In one embodiment, further comprising a scroll mounted within the housing, the scroll comprising:

the centrifugal fan comprises a pair of fan cavities, a pair of fan cavities and a fan control device, wherein a centrifugal fan is arranged in each fan cavity, and each fan cavity is provided with a fan air inlet arranged on one side of the centrifugal fan in the axial direction;

the connecting part is arranged between the pair of fan cavities so as to connect the pair of fan cavities into a whole; and

each air outlet channel is communicated with a corresponding fan cavity from the circumferential direction of the centrifugal fan, each air outlet channel is provided with a fan air outlet arranged on the end face of the connecting part, and the central axes of the air outlet channels intersect on the surface of the heating element to form a first included angle.

In one embodiment, the volute further comprises:

and the backflow prevention flanging extends outwards from the end surface of the connecting part to abut against the inner surface of the shell.

In one embodiment, the cavity in the shell is divided into a front cavity and a rear cavity by the backflow preventing flanging,

the centrifugal fan and the air inlet are positioned in the front cavity, and the heating element and the air outlet are positioned in the rear cavity.

In one embodiment, the axis of the centrifugal fan is perpendicular to the bottom surface of the housing.

In one embodiment, the air inlet is arranged on the bottom surface of the shell,

the fan air inlet is formed in the bottom surface of the fan cavity and aligned with the air inlet.

In one embodiment, the air inlet is opened on the side wall of the shell,

the fan air inlet is arranged on the top surface of the fan cavity, and the bottom surface of the fan cavity is attached to the bottom surface of the shell from the inside of the shell.

In one embodiment, the scroll includes a scroll upper cover and a scroll lower cover which are fitted to each other in an axial direction of the centrifugal fan.

In one embodiment, the first angle is in the range of 30 ° to 120 °.

In one embodiment, the air output of the centrifugal fan is related to the rotational speed and/or the rotational direction of the centrifugal fan.

As can be seen from the above technical solutions, in the present embodiment, the heat dissipation fan is in the form of a centrifugal fan, wherein the centrifugal fan is in the form of axial air inlet and circumferential air outlet, and the air inlet direction and the air outlet direction are perpendicular to each other, rather than being coincident or parallel, so that the thickness of the electronic device using the centrifugal fan in the present embodiment can be minimized to be the thickness (length in the axial direction) of the centrifugal fans 21 and 22, rather than the diameter of the centrifugal fan as in the electronic device using the axial flow fan. In a preferred embodiment, the present electronic device can be implemented as an ultra-thin server with a thickness of 1U (1.75 inches, about 44.45 millimeters) and less.

The heat dissipation airflow in this embodiment is formed by converging airflows of two centrifugal fans, of which the air outlet directions intersect to form an included angle, instead of combining airflows of the fans arranged in sequence. The centrifugal fans 21 and 22 are operated independently, that is, the wind speeds and the turning directions thereof may be the same or different, and the direction of the heat dissipating airflow 3 may be adjusted by controlling the air output of the centrifugal fans 21 and 22, so that the heat dissipating airflow 3 can face the heating element with the largest heat generation amount, thereby improving the heat dissipating efficiency of the electronic device of the present embodiment as much as possible.

Accordingly, when heat dissipation is required for components in a specific area on the main board (the heat generating element 1), the rotational speed, the rotational direction, and the like of the two centrifugal fans 21 and 22 can be controlled according to the temperature feedback of the components or the temperature feedback of the sensor provided on the main board, and the direction of the heat dissipation airflow 3 can be adjusted to control the temperature of the heat generating components in the specific area.

Drawings

The following drawings are only schematic illustrations and explanations of the present invention, and do not limit the scope of the present invention.

Fig. 1 is a schematic structural diagram of a first embodiment of the electronic device of the present invention.

Fig. 2 is a layout view of the centrifugal fan of fig. 1.

Fig. 3a and 3b are diagrams of the heat dissipating airflow of the first embodiment of the electronic device of the present invention.

Fig. 4a and 4b are schematic views of a flow field simulation of a first embodiment of the electronic device of the present invention.

Fig. 5 is a schematic structural view of a scroll in a second embodiment of the electronic apparatus of the present invention.

Fig. 6 is a schematic structural view of a scroll in a third embodiment of the electronic apparatus of the present invention.

Fig. 7 is a distribution diagram of heat dissipation airflow of a third embodiment of the electronic device of the present invention.

Fig. 8 is a schematic structural diagram of a fourth embodiment of the electronic device of the present invention.

Fig. 9 is a schematic structural view of a scroll in a fourth embodiment of the electronic apparatus of the present invention.

Fig. 10 is a distribution diagram of a heat dissipating airflow of the fourth embodiment of the electronic apparatus of the present invention.

Detailed Description

In order to more clearly understand the technical features, objects, and effects of the present invention, embodiments of the present invention will now be described with reference to the accompanying drawings, in which like reference numerals refer to like parts throughout.

"exemplary" means "serving as an example, instance, or illustration" herein, and any illustration, embodiment, or steps described as "exemplary" herein should not be construed as a preferred or advantageous alternative.

For the sake of simplicity, the drawings are only schematic representations of the parts relevant to the invention, and do not represent the actual structure of the product. In addition, in order to make the drawings concise and understandable, components having the same structure or function in some of the drawings are only schematically illustrated or only labeled.

The invention aims to provide electronic equipment, which can realize the direction control of heat dissipation airflow only by controlling the rotating speed of a fan without additionally arranging a wind scooper with a complex structure.

Fig. 1 is a schematic structural diagram of a first embodiment of the electronic device of the present invention. Fig. 2 is a layout view of the centrifugal fan of fig. 1. As shown in fig. 1 and 2, the present invention provides an electronic device including:

the heating element comprises a shell 10, wherein a heating element 1 is arranged in the shell 10, an air inlet 11 and an air outlet 12 are formed in the surface of the shell 10, and the air inlet 11 and the air outlet 12 are respectively positioned at two opposite sides of the heating element 1;

a pair of centrifugal fans 21 and 22, the centrifugal fans 21 and 22 operating independently are symmetrically disposed on the same side of the heat generating component 1, and are located on the same side of the heat generating component 1 as the air inlet 11, the air outlet direction of the centrifugal fans 21 and 22 faces the air outlet 12, and intersects with the surface of the heat generating component 1 to form a first included angle, so as to converge to form a heat dissipating airflow 3 covering the surface of the heat generating component 1 as shown in fig. 3a or 3b, and the direction of the heat dissipating airflow 3 is related to the air outlet volume of the centrifugal fans 21 and 22.

In the present embodiment, the heat dissipation fan is in the form of a centrifugal fan, wherein the centrifugal fan is in the form of axial air inlet and circumferential air outlet, and the air inlet direction and the air outlet direction thereof are perpendicular to each other, rather than being uniform or parallel, and therefore, the thickness of the electronic apparatus using the centrifugal fan of the present embodiment can be formed to be the thickness (length in the axial direction) of the centrifugal fans 21 and 22, rather than the thickness thereof being formed to be the diameter of the centrifugal fan, as in the electronic apparatus using the axial flow fan. In a preferred embodiment, the present electronic device can be implemented as an ultra-thin server with a thickness of 1U (1.75 inches, about 44.45 millimeters) and less.

Further, as shown in fig. 3a and 3b, the heat dissipation airflow in this embodiment is formed by converging airflows of two centrifugal fans, which intersect in the air outlet direction to form an included angle, instead of combining airflows of fans arranged in sequence. The centrifugal fans 21 and 22 are operated independently, that is, the wind speeds and the turning directions thereof may be the same or different, and the direction of the heat dissipating airflow 3 may be adjusted by controlling the air output of the centrifugal fans 21 and 22, so that the heat dissipating airflow 3 can face the heating element with the largest heat generation amount, thereby improving the heat dissipating efficiency of the electronic device of the present embodiment as much as possible.

Among them, the centrifugal fans 21 and 22 are symmetrically disposed on the same side of the heat generating element 1, for example, they are symmetrically disposed about the center line direction of the heat generating element 1. The air outlet direction of each centrifugal fan and the central line direction of the heating element 1 form an included angle, so that the air outlets of the two centrifugal fans 21 and 22 can meet each other, and then the air outlets are converged to form the heat dissipation airflow 3.

Specifically, as shown in fig. 3a, when the two centrifugal fans 21 and 22 rotate at the same speed and rotate in opposite directions, the heat dissipation airflow 3 converges at the center line position and flows out from the air outlet 12 along the center line direction. As shown in fig. 3b, when the rotation speed of the fan on one side is greater than that of the fan on the other side, the heat dissipation airflow 3 converges at the center and then flows mainly along the airflow flowing direction of the centrifugal fan with the greater rotation speed.

Accordingly, when heat dissipation is required for components in a specific area on the main board (the heat generating element 1), the rotational speed, the rotational direction, and the like of the two centrifugal fans 21 and 22 can be controlled according to the temperature feedback of the components or the temperature feedback of the sensor provided on the main board, and the direction of the heat dissipation airflow 3 can be adjusted to control the temperature of the heat generating components in the specific area. The heat dissipation structure of the electronic equipment in the embodiment can realize the direction control of the heat dissipation airflow only by controlling the rotating speed of the centrifugal fan, thereby avoiding the design of the wind scooper with a complex structure and greatly simplifying the structural complexity of the electronic equipment.

Specifically, as shown in fig. 4a and 4b, the flow field of the heat dissipation airflow 3 of fig. 3a to the heat generating element 1 is as shown in fig. 4a, the direction of the heat dissipation airflow is along the midline direction, and the air volume is much larger than that of a single fan. Whereas the flow field of the heat dissipating air flow to the heat generating element 1 of fig. 3b is as shown in fig. 4b, since the rotational speed of the centrifugal fan 22 is greater than the rotational speed of the centrifugal fan 21, the direction of the heat dissipating air flow 3 is mainly along the air flow direction of the centrifugal fan 22.

The symmetrical design of the two centrifugal fans 21 and 22 can ensure that the heat dissipation airflow 3 is converged at the center line position and flows out along the center line direction when the rotating speeds of the two centrifugal fans 21 and 22 are the same and the rotating directions are opposite, so that the direction adjustment of the heat dissipation airflow 3 is conveniently realized.

In a preferred embodiment, as shown in fig. 5, the centrifugal fans 21 and 22 are frameless fans, and further include a scroll 30, the scroll 30 is installed in the casing 10, and the scroll 30 includes:

a pair of fan chambers 31, each fan chamber 31 being provided therein with one centrifugal fan 21,22, respectively, each fan chamber 31 having a fan inlet 32 opened at one side of the centrifugal fan 21,22 in the axial direction;

a connection part 33, the connection part 33 being disposed between the pair of fan chambers 31 to integrally connect the pair of fan chambers 31; and

each air outlet channel 34 is communicated with a corresponding fan cavity 31 from the circumferential direction of the centrifugal fan 21,22, each air outlet channel 34 is provided with a fan air outlet 35 arranged on the end surface of the connecting part 33, and the central axes of the air outlet channels 34 intersect on the surface of the heating element 1 to form a first included angle.

The extending direction of the air outlet channel 34 is the extending direction of the central axis thereof, and determines the air outlet direction of the centrifugal fans 21 and 22.

The fan cavity 31 is used for installing and sealing the centrifugal fans 21 and 22, and includes an annular side wall surrounding the centrifugal fan from the circumferential direction and a pair of circular side walls sealing the centrifugal fan from both sides of the axial direction of the centrifugal fan, wherein one of the circular side walls is provided with a fan inlet 32, and the annular side wall is communicated with an air outlet channel 34, so that the outlet air of the centrifugal fan is discharged from the fan cavity 31 to the surface of the heating element 1 through the air outlet channel 34, and is discharged from the air outlet 12 out of the casing of the electronic device.

The fan cavity 31 and the air outlet channel 34 are arranged to maximize the air volume of the centrifugal fan and guide the outlet air of the centrifugal fan. The pair of air outlet channels 34 are symmetrically disposed about the center line of the heating element 1, and are inclined at an angle toward the center line. The range of a first included angle formed between the air outlet channels is 30-120 degrees, and the first included angle can be determined according to the length size of a product.

Since the electronic apparatus of the present embodiment is particularly suitable for an apparatus having a small thickness, in a preferred embodiment, the housing 10 may be formed by joining an upper cover 10a and a lower cover 10b, wherein the upper cover 10a may be formed by a top surface and a pair of side walls (e.g., left and right side walls) connected to a pair of opposite side edges of the top surface, and the lower cover 10b may be formed by a bottom surface and a pair of side walls (e.g., front and rear side walls) connected to a pair of opposite side edges of the bottom surface. The upper cover 10a and the lower cover 10b are joined to form the housing 10.

In a preferred embodiment, as shown in fig. 5, the scroll 30 includes a scroll upper cover 30a and a scroll lower cover 30b which are split with each other along the axial direction of the centrifugal fans 21, 22.

The scroll upper cover 30a and the scroll lower cover 30b each have a structure corresponding to the fan cavity 31, the air outlet passage 34, and the connecting portion 33, and the corresponding fan cavity 31, the air outlet passage 34, and the connecting portion 33 are formed by being spliced with each other, so that the centrifugal fan can be conveniently fixed in the fan cavity 31. Alternatively, the connecting portion 33 may have a hollow cavity, and the interior of the hollow cavity may be used for installing components such as a controller.

The air output of the centrifugal fans 21,22 may be related to the rotational speed and/or the rotational direction of the centrifugal fans. Besides the rotational speed, the direction of rotation can also have an influence on the air output. As shown in fig. 3a and 3b, the peak position of the air volume discharged from the air outlet channel 34 by the centrifugal fan is related to the rotation direction. When the centrifugal fan 22 rotates in the counterclockwise direction, the peak value of the air output is located on the left wall of the right air outlet channel 34, and if the centrifugal fan 22 rotates in the clockwise direction, the peak value of the air output is located on the right wall of the right air outlet channel 34. Further, the peak position of the air output affects the direction of the heat dissipating air flow 3.

In a preferred embodiment, the axes of the centrifugal fans 21,22 are perpendicular to the bottom surface of the casing 10. That is, the thickness direction of the centrifugal fans 21 and 22 coincides with the thickness direction of the casing 10.

As shown in fig. 5, the scroll 30 further includes:

and a backflow preventing flange 36, wherein the backflow preventing flange 36 extends outwards from the end face of the connecting part 33 to abut against the inner surface of the shell 10.

The backflow preventing flanges 36 may extend upward to the top surface of the housing 10, downward to the bottom surface of the housing 10, and left and right sidewalls abutting against the housing 10.

Referring to fig. 3a and 3b, the cavity inside the housing 10 is divided into a front cavity 1a and a rear cavity 1b by a backflow preventing flange 36, wherein the centrifugal fans 21 and 22 and the air inlet 11 are located in the front cavity 1a, and the heating element 1 and the air outlet 12 are located in the rear cavity 1 b.

The electronic equipment of this embodiment separates the internal cavity for antechamber and back chamber through centrifugal fan's volute to locate different cavities with air intake and components and parts branch, can avoid the dust to cause the pollution to the components and parts of back intracavity. Further, the centrifugal fans 21 and 22 and the heating element 1 are separately disposed in different cavities, so that the heat generated by the operation of the centrifugal fans can be prevented from affecting the ambient temperature of the heating element 1.

As shown in fig. 1, 6 and 7, in an embodiment of the electronic device of the present invention, the air inlet 11 is opened on the bottom surface of the housing 10, and the fan inlet 32 is opened on the bottom surface of the fan cavity 31 and aligned with the air inlet 11.

In this embodiment, the airflow direction in the electronic device is that, the centrifugal fans 21 and 22 operate to suck air into the fan cavity 31 from the air inlet 11 and discharge the air from the air outlet channel 34 to converge to form the heat dissipating airflow 3, and the heat dissipating airflow 3 passes through the surface of the heating element 1 and takes away heat dissipated by the heating element, and then is discharged from the air outlet 12, thereby implementing a heat dissipating cycle.

As shown in fig. 8, 9 and 10, in an embodiment of the electronic device of the present invention, the air inlet 11 is opened on a side wall of the housing 10, the fan inlet 32 is opened on a top surface of the fan cavity 31, and a bottom surface of the fan cavity 31 is attached to the bottom surface of the housing 10 from the inside of the housing 10.

In this embodiment, the airflow direction in the electronic device is that, the centrifugal fans 21 and 22 operate to suck air into the front cavity 1a of the housing 10 from the air inlet 11, then enter the fan cavity 31 from the fan air inlet 32, and are discharged from the air outlet channel 34 to converge to form the heat dissipation airflow 3, and the heat dissipation airflow 3 passes through the surface of the heating element 1 and takes away heat dissipated therefrom, and then is discharged from the air outlet 12, thereby implementing a heat dissipation cycle.

As can be seen from the above technical solutions, in the present embodiment, the heat dissipation fan is in the form of a centrifugal fan, wherein the centrifugal fan is in the form of axial air inlet and circumferential air outlet, and the air inlet direction and the air outlet direction are perpendicular to each other, rather than being coincident or parallel, so that the thickness of the electronic device using the centrifugal fan in the present embodiment can be minimized to be the thickness (length in the axial direction) of the centrifugal fans 21 and 22, rather than the diameter of the centrifugal fan as in the electronic device using the axial flow fan. In a preferred embodiment, the present electronic device can be implemented as an ultra-thin server with a thickness of 1U (1.75 inches, about 44.45 millimeters) and less.

The heat dissipation airflow in this embodiment is formed by converging airflows of two centrifugal fans, of which the air outlet directions intersect to form an included angle, instead of combining airflows of the fans arranged in sequence. The centrifugal fans 21 and 22 are operated independently, that is, the wind speeds and the turning directions thereof may be the same or different, and the direction of the heat dissipating airflow 3 may be adjusted by controlling the air output of the centrifugal fans 21 and 22, so that the heat dissipating airflow 3 can face the heating element with the largest heat generation amount, thereby improving the heat dissipating efficiency of the electronic device of the present embodiment as much as possible.

Accordingly, when heat dissipation is required for components in a specific area on the main board (the heat generating element 1), the rotational speed, the rotational direction, and the like of the two centrifugal fans 21 and 22 can be controlled according to the temperature feedback of the components or the temperature feedback of the sensor provided on the main board, and the direction of the heat dissipation airflow 3 can be adjusted to control the temperature of the heat generating components in the specific area.

In this document, "a" does not mean that the number of the relevant portions of the present invention is limited to "only one", and "a" does not mean that the number of the relevant portions of the present invention "more than one" is excluded.

Unless otherwise indicated, numerical ranges herein include not only the entire range within its two endpoints, but also several sub-ranges subsumed therein.

The above-listed detailed description is only a specific description of a possible embodiment of the present invention and is not intended to limit the scope of the present invention, and equivalent embodiments or modifications such as combinations, divisions or repetitions of the features without departing from the technical spirit of the present invention are included in the scope of the present invention.