阅读说明：本技术 热管预埋效果的无损表面状态红外检测系统、控制方法 (Nondestructive surface state infrared detection system and control method for heat pipe embedding effect ) 是由 钱婧 韩昌佩 孙丽崴 赵月中 郑建丽 王凤丽 刘贵 吴春亮 丁雷 于 2020-12-02 设计创作，主要内容包括：本发明属于航天热控技术领域,公开了一种热管预埋效果的无损表面状态红外检测系统、控制方法,柔性加热板放在柔性涂层保护层的上表面,覆盖在内埋热管的一端；柔性加热板上侧固定有测温元件,测温元件与温控器连接；柔性涂层保护层上侧覆盖有保温层,柔性涂层保护层上方设置有红外热成像仪,红外热成像仪固定在支撑架上。本发明不对被测试件表面状态造成损伤,可实时获得被测试件表面的温度分布,直观判断内埋热管的预埋效果,定位整个被埋件预埋效果差的区域；支撑架具有6自由度的调节能力,可实现3个维度的平移和转动,调整红外热成像仪的观测范围,红外热成像仪可实时在线测量。(The invention belongs to the technical field of aerospace thermal control, and discloses a nondestructive surface state infrared detection system with a heat pipe embedding effect and a control method, wherein a flexible heating plate is arranged on the upper surface of a flexible coating protective layer and covers one end of an embedded heat pipe; the upper side of the flexible heating plate is fixed with a temperature measuring element which is connected with a temperature controller; the side of the flexible coating protective layer is covered with a heat preservation layer, an infrared thermal imager is arranged above the flexible coating protective layer, and the infrared thermal imager is fixed on the support frame. The invention does not damage the surface state of the tested piece, can obtain the temperature distribution of the surface of the tested piece in real time, intuitively judges the embedded effect of the embedded heat pipe, and positions the area with poor embedded effect of the whole embedded piece; the support frame has 6 degrees of freedom's controllability, can realize the translation and the rotation of 3 dimensions, adjusts infrared thermal imager's observation scope, and infrared thermal imager can real-time on-line measuring.)

1. A nondestructive surface state infrared detection method for a heat pipe embedding effect is characterized by comprising the following steps:

covering the surface of the detected piece with a coating protection layer to ensure that the protection layer is closely attached to the surface of the detected piece under the action of electrostatic adsorption;

confirming the position of the pre-buried heat pipe, and placing the flexible heating plate on a coating protective layer of the heat pipe area;

coating an insulating layer on the outermost layer of the whole tested piece;

confirming the position of the support frame according to the observation range of the infrared imager, and fixing the infrared imager on the support frame;

the flexible heating plate is electrified and heated, and the temperature control point is lower than the maximum allowable temperature of the embedded heat pipe;

when the measured piece is in thermal equilibrium, uncovering the heat-insulating layer, and observing and collecting the surface temperature of the measured piece;

and judging the pre-burying effect of the embedded heat pipe, and determining the position of poor contact between the heat pipe and the surface of the embedded part.

2. The infrared detection method for the lossless surface state of the embedded effect of the heat pipe as claimed in claim 1, wherein the judging the embedded effect of the embedded heat pipe and the determining the position of the surface contact failure of the heat pipe and the embedded part comprises:

(1) extracting temperatures A1 and A2 and a middle section temperature A3 of an embedded heat pipe and temperatures B1, B2, B3, C1, C2 and C3 of a peripheral non-heat pipe area according to temperature data of an infrared thermal imager;

(2) b is a temperature difference design value of a heat pipe area of the embedded part: if the absolute value of A1-A2 is less than B, the embedded heat pipe is well contacted with the surface of an embedded part, and the embedding effect is good; if the absolute value of A1-A2 absolute value of B is larger than B, the contact between the embedded heat pipe and the embedded part is poor, the embedding effect is poor, and the position with poor contact needs to be positioned;

(3) if the absolute value of A1-A3 absolute value > B, the poor contact position is positioned between the middle section and the heating end, and if the absolute value of A2-A3 absolute value > B, the poor contact position is positioned between the unheated section and the middle section;

(4) c is a designed temperature difference value between an embedded heat pipe area and a non-embedded heat pipe area, if | B1-A1|, | C1-A1|, | B2-A2|, | C2-A2|, | B3-A3|, and | C3-A3|, and the like are all smaller than C, the embedded part has a good embedding effect, and if the value is larger than C, if | B1-A1| > C, the non-embedded heat pipe area between A1 and B1 is not in good contact.

3. The nondestructive surface state infrared detection method for the pre-burying effect of the heat pipe according to claim 1, characterized in that the nondestructive surface state infrared detection method for the pre-burying effect of the heat pipe obtains the evaluation of the pre-burying effect of the heat pipe by acquiring and processing the test data of the tested piece, and can quickly locate the unqualified area; the temperature control and acquisition system is directly contacted with the surface of the tested piece; the flexible coating protective layer is uniformly attached to the detected piece by utilizing the electrostatic adsorption effect, so that the measured temperature of the infrared imager is ensured to be close to the real temperature of the detected piece, and the surface state of the detected piece is not damaged; one end of the embedded heat pipe is heated, the surface temperature condition of the whole detected piece is detected, and the embedded effect of the embedded heat pipe is judged according to the embedded effect criterion.

4. A nondestructive surface state infrared detection system for a heat pipe embedding effect, which implements the nondestructive surface state infrared detection method for the heat pipe embedding effect according to any one of claims 1 to 3, is characterized in that the nondestructive surface state infrared detection system for the heat pipe embedding effect is provided with:

a flexible heating plate;

the flexible heating plate is arranged on the upper surface of the flexible coating protective layer and covers one end of the embedded heat pipe;

the upper side of the flexible heating plate is fixed with a temperature measuring element which is connected with a temperature controller;

the flexible coating protective layer upside covers there is the heat preservation, and flexible coating protective layer top is provided with infrared thermal imager, and infrared thermal imager fixes at the support frame upside.

5. The infrared detection system for the lossless surface state of the embedded effect of the heat pipe as recited in claim 4, wherein the flexible heating plate is a bendable heating sheet;

the flexible heating plate is a silicon rubber heating plate, the thickness of the flexible heating plate is 2mm, and a black thermal control coating is sprayed on the outer surface of the flexible heating plate.

6. The infrared detection system for the lossless surface state of the embedded effect of the heat pipe as recited in claim 1, wherein the flexible coating protective layer covers the surface of the structural member to be detected, and the outer surface of the protective layer is provided with a thermal control coating;

the temperature measuring element is a temperature measuring resistor or a thermocouple.

7. The infrared detection system for the lossless surface state of the pre-buried effect of the heat pipe as in claim 1, wherein the heat preservation layer is 10 units of multi-layer heat insulation assemblies, and each unit of heat insulation assembly is composed of a layer of double-sided aluminum-plated film and a layer of polyester net.

8. The heat pipe embedding effect nondestructive surface state infrared detection system of claim 1, characterized in that the infrared thermal imager is connected with the data acquisition and processing system through a data line;

the temperature measuring element and the flexible heating plate are integrated into a whole.

9. A method for enhancing heat transfer capability of a structural member is characterized in that the method for enhancing heat transfer capability of the structural member uses the nondestructive surface state infrared detection method of the heat pipe embedding effect of any one of claims 1 to 3.

10. A method for improving temperature uniformity of a structural member is characterized in that the method for improving temperature uniformity of the structural member uses the nondestructive surface state infrared detection method for the embedding effect of the heat pipe according to any one of claims 1 to 3.

Technical Field

The invention belongs to the technical field of aerospace thermal control, and particularly relates to a nondestructive surface state infrared detection system with a heat pipe embedding effect and a control method.

Background

At present, a method for pre-embedding a heat pipe in a structural member to enhance the heat transfer capability of the structural member or improve the temperature uniformity of the structural member has become a common process in the aerospace thermal control technology. And detecting the heat transfer capacity of the structural part formed by embedding the heat pipe, and judging whether the embedding effect meets the design requirement. If the pre-embedding effect does not meet the design requirement, reworking and re-embedding are needed.

In the current stage, the embedded effect is detected by adhering a heater at one end with an embedded heat pipe in an area where the heat pipe is embedded on the outer surface of the structural part, uniformly adhering temperature measuring elements on the structural part, and observing the temperature condition of the temperature measuring elements after heating. The heater and the temperature measuring elements are directly adhered to the structural member, after the surface treatment and the coating implementation are carried out on the outer surface of the structural member, the surface state of the structural member can be damaged by the direct contact type test, the temperature measuring elements are distributed on the structural member in a dotted manner, the positions of the temperature measuring elements are determined by the experience of detection personnel, test data are related to the number and the positions of the temperature measuring elements, and the integral embedded effect of the structural member cannot be intuitively obtained.

Through the above analysis, the problems and defects of the prior art are as follows: the existing direct contact type testing device can damage the surface state of a structural part, temperature measuring elements are distributed on the structural part in a dotted manner, the positions of the temperature measuring elements are determined by the experience of detection personnel, and the test data are related to the number and the positions of the temperature measuring elements, so that the integral embedded effect of the structural part cannot be intuitively obtained.

The overall embedded effect of the structural member is obtained under the condition that the surface of the structural member is not damaged, which is contradictory to the current contact type measuring method, and the current measuring method needs to be changed. The invention provides a non-contact measuring method, which can obtain the whole temperature field of a structural member without directly contacting the surface of the structural member, and an inexperienced person can quickly judge the whole embedded effect of the structural member.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides the nondestructive surface state infrared detection system with the heat pipe embedding effect and the control method, the surface state of the structural part is not damaged, the carrying is convenient, and the measurement precision is high.

The invention is realized in such a way that the nondestructive surface state infrared detection method of the heat pipe embedding effect comprises the following steps:

covering the surface of the detected piece with a coating protection layer to ensure that the protection layer is closely attached to the surface of the detected piece under the action of electrostatic adsorption;

confirming the position of the pre-buried heat pipe, and placing the flexible heating plate on a coating protective layer of the heat pipe area;

coating an insulating layer on the outermost layer of the whole tested piece;

confirming the position of the support frame according to the observation range of the infrared imager, and fixing the infrared imager on the support frame;

the flexible heating plate is electrified and heated, and the temperature control point is lower than the maximum allowable temperature of the embedded heat pipe;

when the measured piece is in thermal equilibrium, uncovering the heat-insulating layer, and observing and collecting the surface temperature of the measured piece;

and judging the pre-burying effect of the embedded heat pipe, and determining the position of poor contact between the heat pipe and the surface of the embedded part.

Further, the judging the pre-buried effect of the embedded heat pipe and determining the position of the heat pipe with the surface of the embedded part with poor contact comprises:

(1) extracting temperatures A1 and A2 and a middle section temperature A3 of an embedded heat pipe and temperatures B1, B2, B3, C1, C2 and C3 of a peripheral non-heat pipe area according to temperature data of an infrared thermal imager;

(2) b is a temperature difference design value of a heat pipe area of the embedded part: if the absolute value of A1-A2 is less than B, the embedded heat pipe is well contacted with the surface of an embedded part, and the embedding effect is good; if the absolute value of A1-A2 absolute value of B is larger than B, the contact between the embedded heat pipe and the embedded part is poor, the embedding effect is poor, and the position with poor contact needs to be positioned;

(3) if the absolute value of A1-A3 absolute value > B, the poor contact position is positioned between the middle section and the heating end, and if the absolute value of A2-A3 absolute value > B, the poor contact position is positioned between the unheated section and the middle section;

(4) c is a designed temperature difference value between an embedded heat pipe area and a non-embedded heat pipe area, if | B1-A1|, | C1-A1|, | B2-A2|, | C2-A2|, | B3-A3|, and | C3-A3|, and the like are all smaller than C, the embedded part has a good embedding effect, and if the value is larger than C, if | B1-A1| > C, the non-embedded heat pipe area between A1 and B1 is not in good contact.

Furthermore, the nondestructive surface state infrared detection method for the heat pipe embedding effect acquires and processes test data of a tested piece to obtain the evaluation of the heat pipe embedding effect, and can quickly position an unqualified area; the temperature control and acquisition system is directly contacted with the surface of the tested piece; the flexible coating protective layer is uniformly attached to the detected piece by utilizing the electrostatic adsorption effect, so that the measured temperature of the infrared imager is ensured to be close to the real temperature of the detected piece, and the surface state of the detected piece is not damaged; one end of the embedded heat pipe is heated, the surface temperature condition of the whole detected piece is detected, and the embedded effect of the embedded heat pipe is judged according to the embedded effect criterion.

Another object of the present invention is to provide a nondestructive surface state infrared detection system for a heat pipe embedding effect, which implements the nondestructive surface state infrared detection method for a heat pipe embedding effect, the nondestructive surface state infrared detection system for a heat pipe embedding effect is provided with:

a flexible heating plate;

the flexible heating plate is arranged on the upper surface of the flexible coating protective layer and covers one end of the embedded heat pipe;

the upper side of the flexible heating plate is fixed with a temperature measuring element which is connected with a temperature controller;

the flexible coating protective layer upside covers there is the heat preservation, and flexible coating protective layer top is provided with infrared thermal imager, and infrared thermal imager fixes and is fixed with infrared thermal imager at the support frame upside.

Further, the flexible heating plate is a bendable heating sheet;

the flexible heating plate is a silicon rubber heating plate, the thickness of the flexible heating plate is 2mm, and a black thermal control coating is sprayed on the outer surface of the flexible heating plate.

Further, the flexible coating protective layer covers the surface of the detected structural part, and a spraying thermal control coating is arranged on the outer surface of the protective layer;

the temperature measuring element is a temperature measuring resistor or a thermocouple.

Furthermore, the heat preservation layer is a 10-unit multi-layer heat insulation assembly, and each unit heat insulation assembly consists of a layer of double-sided aluminum-plated film and a layer of polyester net.

Further, the infrared thermal imager is connected with the data acquisition and processing system through a data line;

the temperature measuring element and the flexible heating plate are integrated into a whole.

The invention also aims to provide a method for enhancing the heat transfer capability of the structural part, which uses the nondestructive surface state infrared detection method of the heat pipe embedding effect.

The invention also aims to provide a method for improving the temperature uniformity of the structural part, which uses the nondestructive surface state infrared detection method of the heat pipe embedding effect.

By combining all the technical schemes, the invention has the advantages and positive effects that: the invention does not damage the tested piece, can obtain the temperature distribution of the surface of the tested piece in real time, intuitively judges the embedded effect of the embedded heat pipe, and positions the area with poor embedded effect of the whole embedded piece; the support frame has 6 degrees of freedom's controllability, can realize the translation and the rotation of 3 dimensions, adjusts infrared thermal imager's observation scope, and infrared thermal imager can real-time on-line measuring. The temperature control and acquisition system does not directly contact the surface of the tested piece, the surface state of the tested piece is not damaged in the whole testing process, and personnel without pre-embedding experience can quickly, accurately and safely judge the pre-embedding effect of the heat pipe according to the invention.

Test method	Contact mode	Number of surface measurement points	Judging region	Residue of the reaction
					Prior Art	Direct contact	Not less than 4	Near the measuring point	Residual glue
The technical scheme	Not in direct contact with	0	Whole plate	Is free of

The flexible heating plate is a bendable heating sheet, and when the surface of the tested piece is a curved surface, the heating sheet can be well attached to the surface. The flexible heating plate is a silicon rubber heating plate, the thickness of the flexible heating plate is 2mm, the black thermal control coating is sprayed on the outer surface of the flexible heating plate, and the emissivity is larger than 0.85. The flexible coating protective layer covers the surface of the detected structural member, the outer surface of the protective layer is provided with a spray thermal control coating, and the emissivity is greater than 0.85; and meanwhile, black extinction paint is sprayed on the surface of the flexible coating protective layer, so that the water accumulation film with the electrostatic adsorption function is formed.

The temperature measuring element in the invention is a temperature measuring resistor or a thermocouple. The heat-insulating layer is a 10-unit multi-layer heat-insulating assembly, each unit of heat-insulating assembly consists of a layer of double-sided aluminum-plated film and a layer of polyester net, so that the temperature control effect of the heating plate is ensured, and a tested piece can quickly enter a thermal equilibrium state. According to the invention, the infrared thermal imager is connected with the data acquisition and processing system through the data line, and the infrared thermal imager can perform real-time online measurement. The temperature measuring element and the flexible heating plate are integrated into a whole, so that the temperature detection is realized.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained from the drawings without creative efforts.

FIG. 1 is a schematic structural diagram of a nondestructive surface state infrared detection system for embedded effect of a heat pipe according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of an insulation layer provided by an embodiment of the present invention;

in the figure: 1. a flexible coating protective layer; 2. a flexible heating plate; 3. a temperature measuring element; 4. a temperature controller; 5. an infrared thermal imager; 6. a support frame; 7. a data acquisition and processing system; 8. and (7) an insulating layer.

Fig. 3 is a cloud diagram of measured temperatures provided by an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Aiming at the problems in the prior art, the invention provides a nondestructive surface state infrared detection system with a heat pipe embedding effect and a control method, and the invention is described in detail below with reference to the accompanying drawings.

The first embodiment is as follows:

as shown in fig. 1 and fig. 2, the nondestructive surface state infrared detection system with the heat pipe embedding effect provided by the embodiment of the present invention is provided with a temperature control structure and a temperature measurement structure.

Temperature control structure: a flexible coating protective layer 1, a flexible heating plate 2, a temperature measuring element 3, a temperature controller 4 and a heat insulation layer 8.

Temperature measurement structure: the system comprises an infrared thermal imager 5, a support frame 6 and a data acquisition and processing system 7.

The flexible heating plate 2 is placed on the upper surface of the flexible coating protective layer 1 and covers one end of the embedded heat pipe; the flexible heating plate 2 is a bendable heating sheet, and when the surface of the tested piece is a curved surface, the heating sheet can be well attached to the surface. The flexible heating plate 2 is a silicon rubber heating plate with the thickness of 2mm, the outer surface is sprayed with a black thermal control coating, and the emissivity is larger than 0.85. The flexible coating protective layer 1 is a flexible electrostatic adsorption material and covers the surface of the detected structural part, a thermal control coating is sprayed on the outer surface of the protective layer, and the emissivity is greater than 0.85. And meanwhile, black extinction paint is sprayed on the surface of the flexible coating protection layer 1, and the water accumulation film with the electrostatic adsorption function is formed.

The upper side of the flexible heating plate 2 is fixed with a temperature measuring element 3, the temperature measuring element 3 and the flexible heating plate 2 are integrated into a whole, and the temperature measuring element 3 is connected with a temperature controller 4 and matched with the temperature controller to control the temperature of the heating plate. Wherein, the temperature measuring element 3 is Pt100, and the temperature controller is a PID temperature controller. The upper side of the flexible coating protection layer 1 is covered with a heat preservation layer 8, the heat preservation layer 8 is a 10-unit multi-layer heat insulation assembly, and each unit heat insulation assembly consists of a double-sided aluminum-plated film and a polyester net; and the heat preservation layer 8 ensures the temperature control effect of the heating plate, so that the tested piece can quickly enter a heat balance state.

An infrared thermal imager 5 is fixed on the upper side of the support frame 6, and the model is FLIR ETS 320. The thermal infrared imager 5 is positioned above the detected structural part, the support frame 6 has multi-dimensional adjusting capability, each dimension can realize translation and rotation, and the thermal infrared imager 5 is assisted to comprehensively observe the surface of the detected structural part.

The infrared thermal imager 5 is connected with the data acquisition and processing system 7 through a data line, the data acquisition and processing system 7 can acquire observation data in real time, and meanwhile, data processing is carried out according to pre-buried effect criteria to judge the pre-buried effect. Wherein, the data acquisition and processing system 7 is an industrial personal computer.

The technical solution of the present invention is further described with reference to the following specific examples.

The embodiment of the invention provides a nondestructive surface state infrared detection method for a heat pipe embedding effect, which comprises the following steps:

step a, covering a coating protection layer on the surface of a detected piece to ensure that the protection layer is closely attached to the surface of the detected piece under the action of electrostatic adsorption;

b, confirming the position of the pre-buried heat pipe, and placing the flexible heating plate on a coating protection layer of the heat pipe area;

step c, coating an insulating layer on the outermost layer of the whole tested piece;

d, confirming the position of the support frame according to the observation range of the infrared imager, and fixing the infrared imager on the support frame;

e, electrifying the flexible heating plate for heating, wherein the temperature control point is lower than the maximum allowable temperature of the embedded heat pipe;

f, when the measured piece is in thermal balance, uncovering the heat-insulating layer, and observing and collecting the surface temperature of the measured piece;

and g, judging the pre-burying effect of the embedded heat pipe, and determining the position of poor contact between the heat pipe and the surface of the embedded part.

The step g of the nondestructive surface state infrared detection method for the pre-buried effect of the heat pipe comprises the following steps:

step g1, extracting the temperatures A1 and A2 of the two ends and the temperature A3 of the embedded heat pipe, and the temperatures B1, B2, B3, C1, C2 and C3 of the peripheral non-heat pipe area according to the temperature data of the infrared thermal imager;

step g2, B is a temperature difference design value of the heat pipe area of the embedded part: if the absolute value of A1-A2 is less than B, the embedded heat pipe is well contacted with the surface of an embedded part, and the embedding effect is good; if the absolute value of A1-A2 absolute value of B is larger than B, the contact between the embedded heat pipe and the embedded part is poor, the embedding effect is poor, and the position with poor contact needs to be positioned;

g3, if | A1-A3| > B, the position of poor contact is located between the middle section and the heating end, and if | A2-A3| > B, the position of poor contact is located between the unheated section and the middle section;

step g4, C is a designed value of the temperature difference between the embedded heat pipe area and the non-embedded heat pipe area, if | B1-A1|, | C1-A1|, | B2-A2|, | C2-A2|, | B3-A3|, and | C3-A3| are all smaller than C, the embedded part has a good embedding effect, and if the value is larger than C, if | B1-A1| > C, the non-embedded heat pipe area between A1 and B1 does not contact well. In this example, B, C is an empirical value, B ═ C ═ 1 ℃.

The second embodiment is as follows:

the present embodiment is different from the first embodiment in that: the infrared thermal imager 5 is hand-held and is of the FLIR E8 type without the need for a support stand 6.

The step g of the nondestructive surface state infrared detection method for the pre-buried effect of the heat pipe comprises the following steps:

step g1, extracting an embedded heat pipe area according to the temperature data of the infrared thermal imager, wherein the temperature A12 at two ends of the embedded heat pipe is 24.9 ℃, A2 is 24.7 ℃, the temperature A3 at a middle section is 24.8 ℃, the temperature B1 at a peripheral non-heat pipe area is 23.9 ℃, B2 is 24.3 ℃, B3 is 23.9 ℃, C1 is 23.8 ℃, C2 is 23.4 ℃ and C3 is 4 ℃;

step g2, B is a temperature difference design value of the heat pipe area of the embedded part: if | A1-A2|, 0.2 ℃ <1 ℃, the embedded heat pipe is in good contact with the surface of the embedded part, and the embedding effect is good. Therefore, steps g3 and g4 are not required.

Fig. 3 is a cloud chart of the measured temperature in the present embodiment.

The working principle of the invention is as follows: by collecting and processing the test data of the tested piece, the evaluation of the pre-embedding effect of the heat pipe is obtained, and the unqualified area can be quickly positioned. The temperature control and acquisition system provided by the invention is in direct contact with the surface of the tested piece, the surface state of the tested piece is not damaged in the whole testing process, and the pre-embedding effect of the heat pipe can be judged quickly, accurately and safely. The flexible coating protective layer 1 is uniformly attached to the detected piece by utilizing the electrostatic adsorption effect, so that the measurement temperature of the infrared imager 5 is ensured to be close to the real temperature of the detected piece, and the surface state of the detected piece is not damaged. One end of the embedded heat pipe is heated, the surface temperature condition of the whole detected piece is detected, and the embedded effect of the embedded heat pipe is judged according to the embedded effect criterion.

In the description of the present invention, "a plurality" means two or more unless otherwise specified; the terms "upper", "lower", "left", "right", "inner", "outer", "front", "rear", "head", "tail", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, should not be construed as limiting the invention. Furthermore, the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

The above description is only for the purpose of illustrating the present invention and the appended claims are not to be construed as limiting the scope of the invention, which is intended to cover all modifications, equivalents and improvements that are within the spirit and scope of the invention as defined by the appended claims.