阅读说明：本技术 分子泵轴承结构 (Molecular pump bearing structure ) 是由 宁远涛 黄涛 张延顺 景加荣 黄佳荣 吴晓鹏 于 2019-11-13 设计创作，主要内容包括：本发明提供了一种分子泵轴承结构,包括纵向弹簧、弹簧压盖、减振环、轴承座、侧向弹簧圈、吸能胶圈、紧固件、底部压盖、轴承以及主轴；轴承座内部设置有轴承安装腔,轴承设置于轴承安装腔内并能够相对轴承安装腔轴向运动,轴承外圈与轴承安装腔的内壁间隙配合,轴承内圈通过紧固件固定于主轴上,主轴通过轴承支撑在轴承座上；轴承外圈过盈套设于减震环内,减振环套设于侧向弹簧圈与吸能胶圈连接形成的散热胶圈内,散热胶圈与轴承安装腔内壁连接；所述轴承座的一端与底部压盖匹配连接,轴承座的另一端设置有弹簧压盖,弹簧压盖与减振环的端面之间设置有一个或多个纵向弹簧。本发明可明显减小轴承振动,有效的帮助轴承散热,从而延长轴承寿命。(The invention provides a molecular pump bearing structure which comprises a longitudinal spring, a spring gland, a vibration damping ring, a bearing seat, a lateral spring ring, an energy absorption rubber ring, a fastener, a bottom gland, a bearing and a main shaft, wherein the longitudinal spring is arranged on the bearing seat; a bearing installation cavity is arranged in the bearing seat, the bearing is arranged in the bearing installation cavity and can axially move relative to the bearing installation cavity, the outer ring of the bearing is in clearance fit with the inner wall of the bearing installation cavity, the inner ring of the bearing is fixed on the main shaft through a fastening piece, and the main shaft is supported on the bearing seat through the bearing; the bearing outer ring is sleeved in the damping ring in an interference manner, the damping ring is sleeved in a heat dissipation rubber ring formed by connecting the lateral spring ring and the energy absorption rubber ring, and the heat dissipation rubber ring is connected with the inner wall of the bearing installation cavity; one end of the bearing seat is connected with the bottom gland in a matching mode, the other end of the bearing seat is provided with a spring gland, and one or more longitudinal springs are arranged between the spring gland and the end face of the vibration damping ring. The invention can obviously reduce the vibration of the bearing and effectively help the bearing to dissipate heat, thereby prolonging the service life of the bearing.)

1. A molecular pump bearing structure is characterized by comprising a longitudinal spring (1), a spring gland (2), a damping ring (3), a bearing seat (4), a lateral spring ring (5), an energy absorption rubber ring (6), a fastener (7), a bottom gland (8), a bearing (11) and a main shaft (12);

a bearing installation cavity is arranged in the bearing seat (4), a bearing (11) is arranged in the bearing installation cavity and can axially move relative to the bearing installation cavity, the outer ring of the bearing (11) is in clearance fit with the inner wall of the bearing installation cavity, the inner ring of the bearing (11) is fixed on a main shaft (12) through a fastener (7), and the main shaft (12) is supported on the bearing seat (4) through the bearing (11);

the outer ring of the bearing (11) is sleeved in the damping ring (3) in an interference manner, the damping ring (3) is sleeved in a heat dissipation rubber ring formed by connecting the lateral spring ring (5) with the energy absorption rubber ring (6), and the heat dissipation rubber ring is connected with the inner wall of the bearing installation cavity;

one end of the bearing seat (4) is connected with the bottom gland (8) in a matching mode, the other end of the bearing seat (4) is provided with the spring gland (2), and one or more longitudinal springs (1) are arranged between the spring gland (2) and the end face of the damping ring (3).

2. The molecular pump bearing structure according to claim 1, characterized in that the lateral spring ring (5) has a sawtooth wave shape in cross section, the energy-absorbing rubber ring (6) is annular, a groove corresponding to the shape of the lateral spring ring (5) is arranged between the annular inner ring and the annular outer ring of the energy-absorbing rubber ring (6), the lateral spring ring (5) is arranged in the groove of the energy-absorbing rubber ring (6), and the thickness of the energy-absorbing rubber ring (6) at the connection position with the shape of the wave crest and the wave trough of the lateral spring ring (5) does not influence the elastic performance of the lateral spring (5).

3. The molecular pump bearing structure according to claim 1, characterized in that the lateral spring ring (5) has a cross section in the shape of a sawtooth wave, the crests and troughs of which are flat;

the energy-absorbing rubber ring (6) comprises a plurality of outer ring arc-shaped blocks and inner ring arc-shaped blocks, one end of each outer ring arc-shaped block is arc-shaped, and the other end of each outer ring arc-shaped block is in a single sawtooth wave shape matched with the outer ring shape of the lateral spring ring (5); one end of the inner ring arc-shaped block is arc-shaped, and the other end of the inner ring arc-shaped block is in a single sawtooth wave shape matched with the shape of the inner ring of the lateral spring ring (5);

the sawtooth wave shape breach one-by-one of side direction spring ring (5) outer lane is filled and is connected through gluing to a plurality of outer lane arc pieces, a plurality of inner circle arc pieces are filled the sawtooth wave shape breach one-by-one of side direction spring ring (5) inner circle and are connected through gluing, fill the interior outer lane of side direction spring (5) through outer lane arc piece and inner circle arc piece and form annular heat dissipation rubber ring, wherein the plane of side direction spring ring (5) sawtooth wave shape crest and trough department is not filled, the plane of side direction spring ring (5) sawtooth wave shape crest and trough department is the outer lane of heat dissipation rubber ring and the partly of inner circle respectively.

4. Molecular pump bearing structure according to claim 1, characterized in that the lateral spring ring (5) is made of a tin-copper material.

5. Molecular pump bearing structure according to claim 1, characterized in that the longitudinal spring (4) is a coil spring made of tin-copper; the longitudinal springs (4) are uniformly distributed on the end face of the vibration reduction ring (3).

6. Molecular pump bearing structure according to claim 1, characterized in that a temperature sensor (13) is arranged on the damping ring (3) and/or the spring gland (2), the temperature sensor (13) alarming when the temperature of the damping ring (3) and the spring gland (2) exceeds a preset upper temperature limit of the temperature sensor (13).

7. The molecular pump bearing structure according to claim 1, wherein a cooling water structure is further designed inside the bearing seat (4), the cooling water structure comprises a cooling water channel, the cooling water channel is circumferentially arranged along the inner wall of the bearing installation cavity, and a water inlet and a water outlet are arranged on the cooling water channel.

8. The molecular pump bearing structure of claim 7, wherein the cooling water structure further comprises a water bar (10), the water bar (10) sealing the cooling water channel.

9. The molecular pump bearing structure of claim 8, wherein the water bar (10) and the bearing seat (4) are made of stainless steel, and the water bar (10) is welded inside the bearing seat (4).

10. Molecular pump bearing structure according to claim 1, characterized in that a sealing ring (9) is arranged between the bearing housing (4) and the bottom gland (8).

Technical Field

The invention relates to the field of vacuum equipment, in particular to a molecular pump bearing structure, and particularly relates to a long-service-life structure of a molecular pump bearing.

Background

The molecular pump is used as vacuum obtaining equipment, the working rotating speed of a rotor generally reaches tens of thousands of revolutions per minute, the unbalanced mass of the rotor at high rotating speed can cause bending vibration, torsional vibration and the like of the rotor, and the vibration is finally transmitted on a molecular pump bearing to influence the performance of the molecular pump bearing, so that the service life is reduced. The bearings at two ends of the main shaft generate huge heat due to friction under the condition of high-speed operation, if the heat is not dissipated in time, rapid temperature rise is caused, after the temperature range of the bearings in normal use is exceeded, grease is denatured, the bearings are broken down, or the bearings work at a higher temperature for a long time, and the service life is shortened.

Generally, an elastic material is adopted for vibration reduction to prolong the service life of a molecular pump bearing. Chinese patent document No. CN201461516U of limited liability company for technical development of beijing chinese science instruments discloses a bearing seat of a molecular pump, which comprises a bearing seat body, wherein an inner cavity matched with a bearing outer ring is arranged on the bearing seat body, and a grease injection hole communicated with a gap between the inner cavity wall of the bearing seat body and the bearing outer ring is also arranged on the bearing seat body. This technical scheme carries out the damping through the damping rubber ring in order to improve the life of molecular pump bearing frame, but the thermal conductivity can not be enough when damping rubber ring lateral vibration isolation, can't in time dispel the heat on the bearing.

The Chinese patent document with patent publication number CN103470539B of Beijing Zhongkeke instrument technology development, Inc. discloses a vibration damping and heat dissipating device of a rolling bearing, which comprises a bearing seat, a bearing gland, a rotating shaft, a vibration damping rubber ring, a wave spring and a rolling bearing; the connection relationship is that a damping rubber ring is embedded in the bearing seat and the bearing gland; the rolling bearing is arranged on the rotating shaft, and the rotating shaft is supported in the bearing seat through the rolling bearing; a wave spring is arranged in a gap between the side surface of the rolling bearing and the bearing seat, and the upper end surface and the lower end surface of the rolling bearing are in contact with the bearing seat and a vibration damping rubber ring in a bearing gland; the bearing gland is arranged above the bearing seat and compresses the rolling bearing. According to the technical scheme, the vibration impact of the rolling bearing is reduced through the wave spring made of the beryllium bronze material, although the wave spring made of the beryllium bronze material is good in heat conductivity, the beryllium bronze material is overlarge in rigidity and limited in energy absorption effect, and the vibration of the bearing is even increased after the vibration exceeds a certain frequency.

In addition, the above two patents have the following three disadvantages:

(1) the adopted springs are all thin-wall hollow structures, so that the stress concentration points are many, the stability is poor, the impact resistance is weak, and plastic deformation is easy to generate to cause damage;

(2) the temperature sensor is not arranged for closed-loop detection, and once the damage occurs, the repair cannot be carried out;

(3) a cooling water path cooling structure is not arranged, and after a certain rotating speed is exceeded, the heat of the bearing cannot be timely dissipated, so that the service life is influenced.

Disclosure of Invention

In view of the defects in the prior art, the invention aims to provide a molecular pump bearing structure.

The molecular pump bearing structure provided by the invention comprises a longitudinal spring, a spring gland, a vibration damping ring, a bearing seat, a lateral spring ring, an energy absorption rubber ring, a fastener, a bottom gland, a bearing and a main shaft;

a bearing installation cavity is arranged in the bearing seat, the bearing is arranged in the bearing installation cavity and can axially move relative to the bearing installation cavity, a bearing outer ring is in clearance fit with the inner wall of the bearing installation cavity, a bearing inner ring is fixed on the main shaft through a fastening piece, and the main shaft is supported on the bearing seat through the bearing;

the bearing outer ring is sleeved in the damping ring in an interference manner, the damping ring is sleeved in a heat dissipation rubber ring formed by connecting the lateral spring ring and the energy absorption rubber ring, and the heat dissipation rubber ring is connected with the inner wall of the bearing installation cavity;

one end of the bearing seat is connected with the bottom gland in a matching mode, the other end of the bearing seat is provided with a spring gland, and one or more longitudinal springs are arranged between the spring gland and the end face of the vibration damping ring.

Preferably, the cross section of the lateral spring ring is in a sawtooth wave shape, the energy-absorbing rubber ring is in a ring shape, a groove corresponding to the lateral spring ring in shape is formed between the inner ring and the outer ring of the energy-absorbing rubber ring in the ring shape, the lateral spring ring is arranged in the groove of the energy-absorbing rubber ring, and the thickness of the connection part of the energy-absorbing rubber ring and the wave crest and wave trough shapes of the lateral spring ring does not influence the elastic performance of the lateral spring.

Preferably, the cross section of the lateral spring ring is in a sawtooth wave shape, and the wave crests and the wave troughs of the sawtooth wave shape are planes;

the energy-absorbing rubber ring comprises a plurality of outer ring arc-shaped blocks and inner ring arc-shaped blocks, one end of each outer ring arc-shaped block is arc-shaped, and the other end of each outer ring arc-shaped block is in a single sawtooth wave shape matched with the shape of the outer ring of the lateral spring ring; one end of the inner ring arc-shaped block is arc-shaped, and the other end of the inner ring arc-shaped block is in a single sawtooth wave shape matched with the shape of the inner ring of the lateral spring ring;

a plurality of outer lane arc pieces are packed the sawtooth wave form breach of side direction spring ring outer lane one by one and are connected through gluing, a plurality of inner circle arc pieces are packed the sawtooth wave form breach of side direction spring ring inner circle one by one and are connected through gluing, pack the interior outer lane of side direction spring through outer lane arc piece and inner circle arc piece and form annular heat dissipation rubber ring, and wherein the plane of the wavy crest of side direction spring ring sawtooth and trough department is not filled, the plane of the wavy crest of side direction spring ring sawtooth and trough department is the outer lane of heat dissipation rubber ring and the partly of inner circle respectively.

Preferably, the lateral spring ring is made of a tin-copper material.

Preferably, the longitudinal spring is a coil spring made of tin copper; the plurality of longitudinal springs are uniformly distributed on the end face of the vibration reduction ring.

Preferably, the damping ring and/or the spring gland are/is provided with a temperature sensor, and when the temperature of the damping ring and the spring gland exceeds the preset upper temperature limit of the temperature sensor, the temperature sensor gives an alarm.

Preferably, the inside cooling water structure that has still designed of bearing frame, the cooling water structure includes the cooling water course, the inner wall circumference setting of bearing installation cavity is followed to the cooling water course, set up water inlet and delivery port on the cooling water course.

Preferably, the cooling water structure further comprises a water bar which seals the cooling water channel.

Preferably, the water bar and the bearing seat are made of stainless steel materials, and the water bar is welded inside the bearing seat.

Preferably, a sealing ring is arranged between the bearing seat and the bottom gland.

Compared with the prior art, the invention has the following beneficial effects:

1. according to the molecular pump bearing structure provided by the invention, the lateral spring ring is made of the tin-copper elastic material with good rigidity and heat conductivity, so that after the lateral spring ring is combined with a rubber material, vibration reduction, heat conductivity and stability can be simultaneously considered.

2. The molecular pump bearing structure provided by the invention adopts the longitudinal spring arranged between the spring gland and the damping ring, gives a certain pretightening force to the bearing, further enhances the heat conduction capability, and eliminates certain vibration through internal friction energy absorption.

3. The molecular pump bearing structure provided by the invention is provided with a temperature sensor for closed-loop detection, and a temperature upper limit alarm is set, so that the maintenance can be reminded in time, and the service life of the bearing is further prolonged;

4. the molecular pump bearing structure provided by the invention is provided with the cooling water path cooling structure, so that the heat of the bearing can be dissipated in time even if the rotating speed exceeds a certain rotating speed, and the service life of the bearing is not influenced.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

fig. 1 is a schematic view of the overall structure of the present invention.

Fig. 2 is a front view of a lateral zigzag spring.

Fig. 3 is a schematic perspective view of a lateral zigzag spring.

FIG. 4 is a front view of the combination of the lateral spring and the energy absorbing rubber ring.

FIG. 5 is a schematic perspective view of a combination of a lateral spring and an energy absorbing rubber ring.

Fig. 6 is a schematic view of a water path on the bearing seat.

The figures show that:

1-longitudinal spring 6-energy-absorbing rubber ring 10-water bar

2-spring gland 7-fastener 11-bearing

3-damping ring 8-bottom gland 12-main shaft

4-bearing seat 9-sealing ring 13-temperature sensor

5-lateral spring ring

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.

In the description of the present application, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application.

According to the molecular pump bearing structure provided by the invention, the outer side of the bearing is laterally combined by the sawtooth springs and the rubber material, the four spiral springs are axially used, the temperature sensor is arranged for closed-loop detection, and the cooling water path is arranged for cooling, so that the radial and axial vibration of the bearing is reduced, the heat dissipation capacity of the inner bearing is enhanced, and the service life of the bearing is greatly prolonged.

The molecular pump bearing structure provided by the invention comprises a longitudinal spring 1, a spring gland 2, a damping ring 3, a bearing seat 4, a lateral spring ring 5, an energy-absorbing rubber ring 6, a fastener 7, a bottom gland 8, a bearing 11 and a main shaft 12; a bearing installation cavity is arranged in the bearing seat 4, the bearing 11 is arranged in the bearing installation cavity and can axially move relative to the bearing installation cavity, the outer ring of the bearing 11 is in clearance fit with the inner wall of the bearing installation cavity, the inner ring of the bearing 11 is fixed on the main shaft 12 through a fastener 7, and the main shaft 12 is supported on the bearing seat 4 through the bearing 11; the outer ring of the bearing 11 is sleeved in the damping ring 3 in an interference manner, the damping ring 3 is sleeved in a heat dissipation rubber ring formed by connecting the lateral spring ring 5 with the energy absorption rubber ring 6, and the heat dissipation rubber ring is connected with the inner wall of the bearing installation cavity; one end of the bearing seat 4 is connected with the bottom gland 8 in a matching mode, the other end of the bearing seat 4 is provided with the spring gland 2, and one or more longitudinal springs 1 are arranged between the spring gland 2 and the end face of the damping ring 3.

The cross section of the lateral spring ring 5 is in a sawtooth wave shape, the energy-absorbing rubber ring 6 is in an annular shape, a groove corresponding to the shape of the lateral spring ring 5 is formed between the annular inner ring and the annular outer ring of the energy-absorbing rubber ring 6, the lateral spring ring 5 is arranged in the groove of the energy-absorbing rubber ring 6, the thickness of the connecting part of the energy-absorbing rubber ring 6 and the shape of the wave crest and the wave trough of the lateral spring ring 5 does not influence the elastic performance of the lateral spring 5, and preferably, the thickness of the connecting part of the energy-absorbing rubber ring 6 and the shape of the wave crest and the wave trough of. Or the cross section of the lateral spring ring 5 is in a sawtooth wave shape, and the wave crests and the wave troughs of the sawtooth wave shape are planes; the energy-absorbing rubber ring 6 comprises a plurality of outer ring arc-shaped blocks and inner ring arc-shaped blocks, one end of each outer ring arc-shaped block is arc-shaped, and the other end of each outer ring arc-shaped block is in a single sawtooth wave shape matched with the shape of the outer ring of the lateral spring ring 5; one end of the inner ring arc-shaped block is arc-shaped, and the other end of the inner ring arc-shaped block is in a single sawtooth wave shape matched with the shape of the inner ring of the lateral spring ring 5; a plurality of outer lane arc pieces are filled the sawtooth wave form breach one by one of 5 outer lanes in side direction spring ring and are connected through gluing, a plurality of inner circle arc pieces are filled the sawtooth wave form breach one by one of 5 inner lanes in side direction spring ring and are connected through gluing, fill the 5 interior outer lane of side direction spring through outer lane arc piece and inner circle arc piece and form annular heat dissipation rubber ring, and wherein the plane of 5 wavy crests of side direction spring ring and trough department is not filled, the plane of 5 wavy crests of side direction spring ring and trough department is the outer lane of heat dissipation rubber ring and the partly of inner circle respectively. The lateral spring ring 5 is made of tin-copper material.

When the molecular pump works, the motor drives the main shaft 12 and the inner ring of the bearing 11 to rotate at a high speed, the balls of the bearing 11 rub with the inner ring and the outer ring to generate a large amount of heat, and meanwhile, due to the existence of unbalance, the bearing 11 bears vibration to a certain degree, so that the service life of the bearing 11 is influenced. According to the invention, a large amount of vibration energy in the radial direction of the bearing 11 and heat energy generated by high-speed rotation are eliminated by adopting a mode of combining the lateral spring ring 5 and the energy-absorbing rubber ring 6, and the lateral spring ring 5 is made of high-quality tin-copper spring material and has excellent elasticity and heat conduction properties. The lateral spring ring 5 is designed to be in a sawtooth shape, and is in close contact with the vibration damping ring 3 and the bearing seat 4 at the same time, so that the heat dissipation of the bearing 11 is effectively facilitated, the energy absorption rubber ring 6 is designed to be connected with the lateral spring ring 5, sawtooth wavy gaps of the lateral spring ring 5 are filled, and the limiting and energy absorption effects are achieved by utilizing the property of the viscoelastic material of the energy absorption rubber ring 6; one or more longitudinal springs 1 are arranged between the spring gland 2 and the end face of the damping ring 3, a certain pretightening force is given to the bearing 11, and certain vibration is eliminated through internal friction energy absorption. Preferably, the fastener 7 is a locking screw. Preferably, the spring gland 2 is screwed to the bearing block 4.

The longitudinal spring 4 is a coil spring made of tin and copper; a plurality of longitudinal springs 4 are evenly distributed on the end face of the damping ring 3. And the damping ring 3 and/or the spring gland 2 are/is provided with a temperature sensor 13, and when the temperature of the damping ring 3 and the spring gland 2 exceeds the preset upper temperature limit of the temperature sensor 13, the temperature sensor 13 gives an alarm. And a temperature sensor 13 is arranged on the damping ring 3 and/or the spring gland 2, and the temperature upper limit alarm is set, so that the maintenance can be reminded in time, and the service life of the bearing 11 is further prolonged. Preferably, the temperature sensor 13 is bonded to the damping ring 3 and/or the spring cover 2 using silicon rubber.

The bearing seat 4 is internally provided with a cooling water structure, the cooling water structure comprises a cooling water channel, the cooling water channel is arranged along the circumferential direction of the inner wall of the bearing installation cavity, and the cooling water channel is provided with a water inlet and a water outlet. The cooling water structure further comprises a water retaining strip 10, and the cooling water channel is sealed by the water retaining strip 10. The water bar 10 and the bearing seat 4 are made of stainless steel materials, and the water bar 10 is welded inside the bearing seat 4. And a sealing ring 9 is arranged between the bearing seat 4 and the bottom gland 8. According to the invention, the cooling water structure is designed in the bearing seat 4, so that the temperature is effectively reduced, and the heat of the bearing can be dissipated in time after the bearing 11 exceeds a certain rotating speed, thereby prolonging the service life of the bearing. The water bar 10 can prevent the cooling water in the cooling water channel from leaking, and the bottom gland 8 can prevent the components in the bearing base 4 from falling off. Through above-mentioned structure, can obviously reduce bearing 11 vibration, the effectual bearing 11 heat dissipation of helping to prolong bearing 11 life-span, increase molecular pump life cycle.

Preferably, the damping ring 3 adopts H59 high-strength high-thermal conductivity T2 red copper, the thermal conductivity coefficient reaches 386.4w/(m.k), the inner cylindrical surface of the damping ring 3 adopts grinding processing, the smoothness is better than 0.4, the damping ring is in interference fit with the bearing 11, and the unilateral interference range is 0.01 mm-0.02 mm; the main shaft 12 is made of high-strength 38CrMoAl, and is subjected to quenching and tempering after rough machining, and finally is subjected to fine machining and fine grinding; the locking nut 7 is made of high-strength H59 brass, and the thread connected with the main shaft 12 is an M10 fine thread, so that the structural stability is ensured; the number of the longitudinal springs 1 is 4, the longitudinal springs 1 are spiral springs made of tin-copper with good elasticity and thermal conductivity and are arranged between the spring gland 2 and the damping ring 3, the outer rings are positioned, the rigidity of the longitudinal springs 1 is 4N/mm, certain pre-tightening force can be given to the bearing 11, the heat conduction effect is good, and certain vibration is eliminated through internal friction energy absorption. Lateral spring ring 5 adopts elasticity and the good tin copper material of heat conductivity, and the cross sectional structure is 0.5mm sawtooth wave, simultaneously with damping ring 3 and bearing frame 4 in close contact with, the heat conduction is effectual, energy-absorbing rubber ring 6 designs for the sawtooth breach shape, splices with lateral spring ring 5, fills up the space of 5 cockscomb structures in lateral spring ring, utilizes viscoelastic material's attribute to play spacing and energy-absorbing effect. A cooling water channel is designed in the bearing seat 4, the water bar 10 is welded to ensure that leakage is avoided, and the bearing seat 4 and the water bar 10 are both made of 304 stainless steel materials which are easy to weld.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.