阅读说明：本技术 一种静电吸附式轴流旋风空气过滤装置及系统 (Electrostatic adsorption type axial flow cyclone air filtering device and system ) 是由 敖顺荣 罗军 尤彬彬 杨晓明 张鹏飞 于 2020-11-17 设计创作，主要内容包括：本发明公开了一种静电吸附式轴流旋风空气过滤装置及系统,该装置包括外筒,所述外筒包括静电吸附部,所述静电吸附部用于对位于其内侧的荷电颗粒物形成有吸引作用的库仑力以便对超细颗粒物达到目标过滤效率。该装置采用了导电材质的静电吸附部并接地,以此增加了旋转运动的荷电颗粒物与静电吸附部内壁之间的吸附库仑力,使得荷电颗粒物更容易贴附在静电吸附部内壁上向前运动,同时增强了异极性荷电颗粒物之间的凝并效果,从而大大提高了轴流旋风除尘装置对含尘空气中细小颗粒物的过滤效率。(The invention discloses an electrostatic adsorption type axial flow cyclone air filtering device and system, wherein the device comprises an outer cylinder, the outer cylinder comprises an electrostatic adsorption part, and the electrostatic adsorption part is used for forming coulomb force with an attraction effect on charged particles positioned on the inner side of the electrostatic adsorption part so as to achieve target filtering efficiency on ultrafine particles. The device has adopted electrically conductive material's electrostatic adsorption portion and ground connection to this adsorption coulomb force between the lotus electric particle thing that has increased rotary motion and the electrostatic adsorption portion inner wall makes lotus electric particle thing more easily attached and moves forward on the electrostatic adsorption portion inner wall, has strengthened the coagulation effect between the heteropolarity lotus electric particle thing simultaneously, thereby has improved axial compressor cyclone dust collector to the filtration efficiency of tiny particulate matter in the dirty air greatly.)

1. An electrostatic adsorption type axial flow cyclone air filter device, comprising:

the outer cylinder comprises an electrostatic adsorption part, and the electrostatic adsorption part is used for forming coulomb force with attraction action on the charged particles positioned at the inner side of the electrostatic adsorption part so as to achieve the target filtering efficiency on the ultrafine particles.

2. The electrostatic adsorption type axial flow cyclone air filter device according to claim 1, wherein the electrostatic adsorption part is made of a conductive material, and the electrostatic adsorption part is electrically connected with the ground to make the electrostatic adsorption part in a zero potential state.

3. The electrostatic adsorption type axial flow cyclone air filtering device according to claim 2, wherein the outer cylinder includes an insulating part, and a guide body and guide vanes are formed on an inner side of the outer cylinder; the guide vane is positioned at the joint of the air inlet side of the outer barrel, the insulating part and the electrostatic adsorption part.

4. The electrostatic adsorption type axial flow cyclone air filtering device according to claim 3, further comprising an air outlet cylinder, wherein both ends of the air outlet cylinder are open, the air outlet cylinder is arranged coaxially with the electrostatic adsorption part, and one end of the air outlet cylinder extends to the inside of the electrostatic adsorption part; an annular baffle is formed at one end, close to the electrostatic adsorption part, of the outer wall of the air outlet cylinder; the annular baffle is used for blocking an airflow channel which is arranged between the inner side of the electrostatic adsorption part and the outer side of the air outlet cylinder and circulates along the axial direction of the electrostatic adsorption part.

5. The electrostatic adsorption type axial flow cyclone air filtering device according to claim 4, wherein the flow guiding body, the flow guiding blades, the air outlet barrel and the annular baffle are all made of insulating materials.

6. The electrostatic adsorption type axial flow cyclone air filtering device according to claim 2, wherein the conductive material is any one of a metal material and a non-metal conductive material.

7. A system comprising the electrostatic adsorption axial flow cyclonic air filtration device of any one of claims 1 to 6, wherein the system comprises:

at least one set of the electrostatic adsorption type axial flow cyclone air filtering device;

the charging device is used for providing airflow to be filtered containing charged particles to at least one set of the electrostatic adsorption type axial flow cyclone air filtering device.

8. The system of claim 7, comprising at least two sets of said electrostatic adsorption axial flow cyclonic air filtration devices; at least two sets of the electrostatic adsorption type axial flow cyclone air filtering devices are coaxially arranged, and the electrostatic adsorption parts respectively contained in two adjacent sets of the electrostatic adsorption type axial flow cyclone air filtering devices are connected through conductive connecting ribs.

9. The system of claim 7, wherein the charging device is a heteropolar charging device.

Technical Field

The invention relates to the technical field of air purification and environmental protection, in particular to an electrostatic adsorption type axial flow cyclone air filtering device and system with excellent filtering efficiency on ultrafine particulate matters (PM 2.5).

Background

With the increasing awareness of the importance of air quality and the increasing requirement of industrial production on the cleanliness of the surrounding environment, air filtration has become the most basic requirement for air treatment of industrial buildings. According to the difference of pollutant species, concentration, particle size, specific gravity and purification degree, various air filtering and dust removing equipment and technologies also appear, and according to the regulations of national standard GB/T14295-2008 air filter and GB/T13554-2008 high-efficiency air filter, the air filtering and dust removing equipment and technologies can be divided into the following parts according to the filtering performance: coarse efficiency, medium efficiency, high and medium efficiency, sub-high efficiency and high efficiency, filters with different filtering levels can be equipped or used in series according to different occasions in engineering, so as to improve the filtering efficiency and dust holding capacity.

Generally speaking, for dust-containing air with larger particle size or specific gravity, only coarse effect or medium effect is needed, and the filters have the advantages of multiple types, simple structure, low price and stable effect. However, for particles with a particle size of 1 μm or less, it is required to use at least a filter of a high or medium efficiency class or more, and among such filters, a high efficiency filter made of a fibrous material and a two-zone electrostatic filter using electrostatic action as a technique are most commonly used. In practical application, the two filters can reach the preset filtering efficiency, but in the occasion with high dust concentration, the high-efficiency filter needs to be frequently replaced after running for a period of time, the ventilation resistance can reach more than 500Pa, the electrostatic filter needs to be frequently cleaned due to small dust holding capacity, and otherwise, the filtering efficiency is sharply reduced.

In order to solve the problems that the conventional high-efficiency filter needs to be frequently replaced after running for a period of time and the double-zone type electrostatic filter is inconvenient to clean and maintain, the inventor of the invention provides an axial flow cyclone coalescence type air filtering device, which is disclosed in the patent number: ZL 201920371093.7. The invention adds a heteropolar charge area on the air inlet side of the axial flow cyclone filter, so that particles in the air are charged with heteropolar charges and are coagulated into large particles in the axial flow cyclone, thereby increasing the centrifugal force of the particles in the cyclone and further improving the filtering efficiency. Experimental tests show that: compared with the traditional axial flow cyclone dust removal device, the counting and filtering efficiency of the technology of the invention on the particles with the particle size of more than or equal to 0.5 mu m is improved by more than 15 percent. According to the national standard GB/T14295-2008, the traditional axial flow cyclone dust removal device belongs to the filtration grade of 'coarse efficiency 1'; after the technology of the invention is adopted, the axial flow cyclone dust collector can reach the filtering level of 'middle efficiency 2'.

In order to further improve the air filtration efficiency of the axial flow cyclone dust removal device, the device is continuously improved on the basis of the device related to the original patent, and the aim of the device is to further improve the filtration efficiency of the axial flow cyclone dust removal device on ultrafine particles (PM 2.5).

Disclosure of Invention

The invention provides an electrostatic adsorption type axial flow cyclone air filtering device and system. The filtering efficiency of the ultrafine particles (PM2.5) in the air can be effectively improved, so that the application occasion of the axial flow cyclone dust removal device is expanded. Experimental tests show that: by adopting the scheme provided by the application, the filtering level of the axial flow cyclone dust collector can be further promoted to a high-efficiency level, and the axial flow cyclone dust collector can be widely applied to the fields of ventilation air-conditioning systems and industrial dust collection.

The invention provides the following scheme:

an electrostatic adsorption type axial flow cyclone air filtering device comprising:

the outer cylinder comprises an electrostatic adsorption part, and the electrostatic adsorption part is used for forming coulomb force with attraction action on the charged particles positioned at the inner side of the electrostatic adsorption part so as to achieve the target filtering efficiency on the ultrafine particles.

Preferably: the electrostatic adsorption part is made of conductive materials and is connected with the earth to enable the electrostatic adsorption part to be in a zero potential state.

Preferably: the outer cylinder comprises an insulating part, and a flow guide body and flow guide blades are formed on the inner side of the outer cylinder; the guide vane is positioned at the joint of the air inlet side of the outer barrel, the insulating part and the electrostatic adsorption part.

Preferably: the air outlet cylinder is coaxially arranged with the electrostatic adsorption part, and one end of the air outlet cylinder extends to the inside of the electrostatic adsorption part; an annular baffle is formed at one end, close to the electrostatic adsorption part, of the outer wall of the air outlet cylinder; the annular baffle is used for blocking an airflow channel which is arranged between the inner side of the electrostatic adsorption part and the outer side of the air outlet cylinder and circulates along the axial direction of the electrostatic adsorption part.

Preferably: the material of the flow guide body, the flow guide blades, the air outlet barrel and the annular baffle is insulating material.

Preferably: the conductive material is any one of a metal material and a nonmetal conductive material.

A system comprising the electrostatic adsorption type axial flow cyclone air filtering device, the system comprising:

at least one set of the electrostatic adsorption type axial flow cyclone air filtering device;

the charging device is used for providing airflow to be filtered containing charged particles to at least one set of the electrostatic adsorption type axial flow cyclone air filtering device.

Preferably: the electrostatic adsorption type axial flow cyclone air filtering device comprises at least two sets of electrostatic adsorption type axial flow cyclone air filtering devices; at least two sets of the electrostatic adsorption type axial flow cyclone air filtering devices are coaxially arranged, and the electrostatic adsorption parts respectively contained in two adjacent sets of the electrostatic adsorption type axial flow cyclone air filtering devices are connected through conductive connecting ribs.

Preferably: the charging device is a heteropolar charging device.

According to the specific embodiment provided by the invention, the invention discloses the following technical effects:

through the invention, an electrostatic adsorption type axial flow cyclone air filtering device and system can be realized, and in an implementation mode, the device can comprise an outer cylinder, wherein the outer cylinder comprises an electrostatic adsorption part, and the electrostatic adsorption part is used for forming coulomb force with an attraction effect on charged particles positioned on the inner side of the electrostatic adsorption part so as to achieve target filtering efficiency on ultrafine particles. The device has adopted electrically conductive material's electrostatic adsorption portion and ground connection to this adsorption coulomb force between the lotus electric particle thing that has increased rotary motion and the electrostatic adsorption portion inner wall makes lotus electric particle thing more easily attached and moves forward on the electrostatic adsorption portion inner wall, has strengthened the coagulation effect between the heteropolarity lotus electric particle thing simultaneously, thereby has improved axial compressor cyclone dust collector to the filtration efficiency of tiny particulate matter in the dirty air greatly.

Of course, it is not necessary for any product in which the invention is practiced to achieve all of the above-described advantages at the same time.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is a schematic structural diagram of an electrostatic adsorption type axial flow cyclone air filtering device according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a system including the electrostatic adsorption type axial flow cyclone air filtering device according to an embodiment of the present invention;

fig. 3 is a schematic structural diagram of a charging device according to an embodiment of the present invention;

fig. 4 is a schematic structural diagram of a system provided by an embodiment of the invention, which includes a plurality of sets of the electrostatic adsorption type axial flow cyclone air filtering devices.

In the figure: the device comprises an outer cylinder 1, an electrostatic adsorption part 11, an insulating part 12, a flow guide body 2, flow guide blades 3, an air outlet cylinder 4, an annular baffle 5, a charging device 6, a power supply 61, a positive corona electrode 62, a negative corona electrode 63, a grounding plate 64, an insulating terminal 65, a V-shaped flow guide plate 66, a conductive connecting rib 7 and a dust exhaust groove 8.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments that can be derived by one of ordinary skill in the art from the embodiments given herein are intended to be within the scope of the present invention.

Examples

Referring to fig. 1, an electrostatic adsorption type axial flow cyclone air filtering apparatus provided for an embodiment of the present invention, as shown in fig. 1, includes an outer cylinder 1, where the outer cylinder 1 includes an electrostatic adsorption part 11, and the electrostatic adsorption part 11 is configured to form coulomb force having an attraction effect on charged particles located inside the electrostatic adsorption part so as to achieve a target filtering efficiency on ultrafine particles.

The working principle of the axial flow cyclone air filtering device is that particles in the air are charged after flowing through the charging device, then the charged particles are attached to the inner surface of the outer cylinder to move forwards in the axial flow cyclone dust removing device under the double action of centrifugal force and coulomb force, and are separated from the air flow at the air outlet cylinder of the axial flow cyclone dust removing device and fall into the dust exhaust groove. In the scheme that this application provided, make a part of urceolus 1 form electrostatic absorption portion 11, the point position of this electrostatic absorption portion can be zero, because electrostatic absorption portion is in zero potential state, is formed with the coulomb force of attraction between lotus electric particle thing and the electrostatic absorption portion, greatly increased the attached moving speed of lotus electric particle thing to electrostatic absorption portion internal surface. Specifically, the conductive material is any one of a metal material and a nonmetal conductive material. The material is preferably made of metal or conductive plastic, and can be selected according to different application occasions.

Further, in order to make the electrostatic adsorption part realize zero potential, the material of the electrostatic adsorption part 11 is conductive, and the electrostatic adsorption part 11 is electrically connected to the ground to make the electrostatic adsorption part 11 in a zero potential state. Specifically, the outer cylinder 1 comprises an insulating part 12, and a flow guide body 2 and a flow guide blade 3 are formed on the inner side of the outer cylinder 1; one end of the guide vane 3, which is positioned at the air inlet side of the outer cylinder 1, coincides with the joint of the insulating part 12 and the electrostatic adsorption part 11. The outer barrel provided by the application forms two sections of the insulating part and the electrostatic adsorption part, so that charged particles can not be attracted by the insulating part before being guided by the guide body and the guide vanes. The charged particles are ensured to enter the inner side of the electrostatic adsorption part as much as possible, and the aim of improving the filtering effect is fulfilled.

Further, the air-out device also comprises an air-out cylinder 4, wherein two ends of the air-out cylinder 4 are both open, the air-out cylinder 4 and the electrostatic adsorption part 11 are coaxially arranged, and one end of the air-out cylinder 4 extends into the electrostatic adsorption part 11; an annular baffle 5 is formed at one end, close to the electrostatic adsorption part 11, of the outer wall of the air outlet cylinder 4; the annular baffle 5 is used for blocking an airflow channel which is arranged between the inner side of the electrostatic adsorption part 11 and the outer side of the air outlet cylinder 4 and circulates along the axial direction of the electrostatic adsorption part 11. The material of the flow guide body 2, the flow guide blades 3, the air outlet cylinder 4 and the annular baffle 5 is insulating material. Other components of the outer barrel except the electrostatic adsorption part are made of insulating materials, so that the charged particles can be prevented from being attracted by other components, and the charged particles can be adsorbed on the surface of the electrostatic adsorption part.

The device has adopted electrically conductive material's electrostatic adsorption portion and ground connection to this adsorption coulomb force between the lotus electric particle thing that has increased rotary motion and the electrostatic adsorption portion inner wall makes lotus electric particle thing more easily attached and moves forward on the electrostatic adsorption portion inner wall, has strengthened the coagulation effect between the heteropolarity lotus electric particle thing simultaneously, thereby has improved axial compressor cyclone dust collector to the filtration efficiency of tiny particulate matter in the dirty air greatly.

Experimental test comparative data according to the above apparatus are as follows:

from the above experimental data it can be seen that: compared with the traditional axial flow cyclone dust collector or the axial flow cyclone dust collector with the charging device, the filtering device provided by the application has the advantage that the counting and filtering efficiency of the particles with the particle size less than or equal to 5.0 mu m is obviously improved.

Referring to fig. 2, 3 and 4, embodiments of the present application may further provide a system including the electrostatic adsorption type axial flow cyclone air filtering device, as shown in fig. 2, the system including:

at least one set of the electrostatic adsorption type axial flow cyclone air filtering device; the electrostatic adsorption type axial flow cyclone air filtering device can determine the using quantity according to the requirements of application occasions, installation position sizes and the like, can adopt one set of electrostatic adsorption type axial flow cyclone air filtering device to correspond to one set of charging device, and also can adopt a mode that one set of charging device is used for a plurality of sets of electrostatic adsorption type axial flow cyclone air filtering devices.

The charging device 6 is used for providing an air flow to be filtered containing charged particles to at least one set of the electrostatic adsorption type axial flow cyclone air filtering devices. The charging device 6 is a heteropolar charging device. So as to improve the coagulation effect of the particles in the air in the movement process of the axial flow cyclone dust collector.

The electrostatic adsorption type axial flow cyclone air filtering device comprises at least two sets of electrostatic adsorption type axial flow cyclone air filtering devices; at least two sets of the electrostatic adsorption type axial flow cyclone air filtering devices are coaxially arranged, and the electrostatic adsorption parts 11 respectively contained in two adjacent sets of the electrostatic adsorption type axial flow cyclone air filtering devices are connected through conductive connecting ribs 7.

The system provided by the application is explained in detail by the electrostatic adsorption type axial flow cyclone air filtering device and the charging device with detailed structures. It should be noted that the system provided by the present application further includes any necessary control components and electrical connection components.

The system can comprise a charging device and an electrostatic axial flow cyclone dust removal device in practical application, wherein the charging device is arranged on the air inlet side of the electrostatic axial flow cyclone dust removal device.

As shown in fig. 3, the charging device 6 includes a positive and negative ion generator including a power supply 61, a positive corona electrode 62, a negative corona electrode 63, and a ground plate 64, wherein the positive corona electrode 62 and the negative corona electrode 63 are alternately arranged on both sides of the ground plate to form a positive corona region and a negative corona region adjacent to each other. The power line is connected with each grounding plate by an insulated terminal 65. By adopting the heteropolarity charging device, the coagulation effect of particles in the air in the movement process of the axial flow cyclone dust collector can be improved.

When the particles in the air flow through the adjacent positive and negative corona regions in the charging device, the particles collide with positive ions and negative ions in the electric field and are respectively charged with positive charges and negative charges. In order to ensure that the proportion of positive and load electric particles flowing into each electrostatic axial flow cyclone dust collector is uniform, a V-shaped guide plate 66 can be arranged on the air outlet side of the positive and negative corona regions, so that the mixing of positive and negative ions is enhanced. The system can be provided with various types of centralized dust collection boxes according to application occasions, so that dust can be collected and treated conveniently.

As shown in fig. 1, the electrostatic axial flow cyclone dust collector includes an outer cylinder 1, a flow guide body 2, a flow guide vane 3, an air outlet cylinder 4 and a formed dust exhaust groove 8, wherein the outer cylinder 1 forms two sections of an electrostatic adsorption part 11 and an insulation part 12. Guide vane 3 fixes on baffle 2, is located the static and adsorbs the portion inside, play chimney 4 is fixed in the air-out side of static adsorption portion 11, and the external diameter of play chimney 4 is less than the internal diameter of static adsorption portion 11 to leave the determining deviation. The flow guide body 2, the electrostatic adsorption part 11 and the air outlet cylinder 4 are coaxial. The front end of the flow guide body 2 close to the air inlet is a hemisphere, the middle section of the flow guide body 2 is a cylinder, and the rear end of the flow guide body 2 is a streamline platform body; the outer diameter of the rear end of the flow guide body 2 is gradually reduced along the horizontal axis direction; the front end, the middle section and the rear end of the flow guide body 2 are all positioned on the same axis; the guide vane 3 is positioned at the rear part of the hemisphere of the guide body 2 and at the front end of the cylinder. The front end of the flow guide body 2 close to the air inlet is in a hemispherical shape and is used for reducing the resistance of the overflowing air and diffusing the air to the guide vane. The middle section of the flow guide body 2 is a cylinder, an annular cavity with a certain length is formed between the flow guide body and the electrostatic adsorption part, and the rotating airflow drives the charged particles to move to the inner wall of the electrostatic adsorption part under the double actions of centrifugal force and coulomb force. The outer diameter of the rear end of the flow guide body 2 is gradually reduced along the horizontal axis direction, and the rear end is a streamline platform body.

The guide vanes 3, the flow guide body 2, the air outlet barrel 4 and other parts are all formed in one step, PPS (polyphenylene sulfide) plastic or ABS (acrylonitrile-butadiene-styrene) plastic is adopted as a material, the weight is lighter, the surface is smoother, the air resistance can be reduced, meanwhile, the adhesion of particles can be reduced, and the invalid discharge of charged particles at the parts can be prevented. The electrostatic adsorption part 11 is made of metal or conductive plastic, and can be selected according to different application occasions, for example, the high-temperature flue gas treatment part can be made of metal such as stainless steel, and the air treatment part can be made of corrosion-resistant conductive plastic.

As shown in fig. 4, in practical application, a plurality of electrostatic axial flow cyclone dust collectors can be assembled in a modularized manner according to the flow rate of the processing air and the installation space. Namely, a plurality of sets of electrostatic axial flow cyclone dust removing devices can be installed in parallel after being arranged in the same axial direction, and when the electrostatic axial flow cyclone dust removing devices comprise a plurality of sets of electrostatic axial flow cyclone dust removing devices, the adjacent electrostatic adsorption parts 11 are connected by the conductive connecting ribs 7, so that equipotential is formed among the plurality of electrostatic adsorption parts 11, and grounding treatment is performed. The air outlet cylinder 4 and the annular baffle 5 divide the space into an air outlet cylinder inner cavity and a dust exhaust groove 8, the air outlet cylinder inner cavity of each electrostatic axial flow cyclone dust removal device is independently separated, and the dust exhaust grooves 8 of each electrostatic axial flow cyclone dust removal device can be communicated with each other.

The specific working principle of the system is as follows:

firstly, under the action of external fan power, the dusty airflow firstly passes through the charging device 6, and then particles in the air are respectively charged with positive charges and negative charges after being collided with positive ions and negative ions in an electric field in a positive corona area and a negative corona area which are adjacent to each other.

And secondly, the particles with positive and negative charges flow into the electrostatic axial flow cyclone dust collector along with air, and rotate under the action of the flow guide body 2 and the flow guide blades 3, and the rotating airflow generates centrifugal force, so that the charged particles are transferred to the electrostatic adsorption part. And mixing, compressing, colliding and airflow rotating are carried out in an annular cavity formed by the guide vanes 3, the electrostatic adsorption part 11 and the guide body 2, so that the collision probability among particles is increased, and the particles with positive and load electricity are condensed into large particles under the action of centrifugal force and coulomb force.

And thirdly, simultaneously, attaching the coagulated large particles to the inner wall of the electrostatic adsorption part 11 under the attraction action of centrifugal force, inertia force and coulomb force of the electrostatic adsorption part to form a forward spiral annular dust layer, and transferring the carried residual charges to the grounded electrostatic adsorption part 11. In this process, since the electrostatic adsorption part 11 is grounded in a zero potential state, a coulomb force with an attraction effect is formed between the charged particles and the electrostatic adsorption part 11, and a moving speed of the charged particles attached to the inner surface of the electrostatic adsorption part 11 is greatly increased. Dust falls into the dust exhaust groove 8 after striking the annular baffle 5 that is located air outlet cylinder outer wall afterbody along with rotatory air current, and clean air is discharged by the air outlet cylinder inner chamber to axial flow cyclone's filtration efficiency has been improved. The scheme that this application provided promotes a grade again with traditional axial compressor cyclone to superfine particulate matter's filtration efficiency.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.