阅读说明：本技术 一种方便封装的新能源汽车用薄膜电容 (Thin film capacitor convenient to package and used for new energy automobile ) 是由 廖东明 孙宇 张淮鑫 于 2020-12-16 设计创作，主要内容包括：本发明涉及薄膜电容技术领域,且公开了一种方便封装的新能源汽车用薄膜电容,包括壳体,壳体的顶部固定设置有输入正极母排和输入负极母排,壳体的四侧均固定卡接有导热板,导热板的外侧固定连接有多个导热套筒,导热套筒内插套有薄膜电容本体,壳体的上下两端均固定连接有散热板,两个散热板相向一侧均固定连接有卡套在薄膜电容本体两端的散热套,散热板的内部开设有蛇形冷却水道,蛇形冷却水道的两端均贯穿散热板的侧壁,散热板的侧壁固定连接有连接螺筒。该方便封装的新能源汽车用薄膜电容,具备能够将薄膜电容本体使用过中产生的热量快速带走且能够实现对薄膜电容本体的快速稳固的固定安装,便于封装使用的优点。(The invention relates to the technical field of thin film capacitors and discloses a thin film capacitor convenient to package for a new energy automobile, which comprises a shell, wherein an input positive electrode bus bar and an input negative electrode bus bar are fixedly arranged at the top of the shell, heat conducting plates are fixedly clamped on four sides of the shell, a plurality of heat conducting sleeves are fixedly connected to the outer sides of the heat conducting plates, a thin film capacitor body is inserted in each heat conducting sleeve, heat radiating plates are fixedly connected to the upper end and the lower end of the shell, heat radiating sleeves clamped at the two ends of the thin film capacitor body are fixedly connected to opposite sides of the two heat radiating plates, a serpentine cooling water channel is formed in each heat radiating plate, the two ends of the serpentine cooling water channel penetrate through the side walls of the. This film capacitor for new energy automobile of convenient encapsulation possesses and takes away the heat that produces in can using the film capacitor body fast and can realize the quick firm fixed mounting to the film capacitor body, the advantage of convenient to encapsulate and use.)

1. The utility model provides a film capacitor for new energy automobile of convenient encapsulation, includes casing (1), its characterized in that: the top of the shell (1) is fixedly provided with an input positive busbar (2) and an input negative busbar (3), heat-conducting plates (4) are fixedly clamped on four sides of the shell (1), a plurality of heat-conducting sleeves (5) are fixedly connected to the outer sides of the heat-conducting plates (4), thin-film capacitor bodies (6) are inserted in the heat-conducting sleeves (5), heat-radiating plates (7) are fixedly connected to the upper end and the lower end of the shell (1), heat-radiating sleeves (8) which are clamped and sleeved at two ends of each thin-film capacitor body (6) are fixedly connected to opposite sides of the two heat-radiating plates (7), a snake-shaped cooling water channel (9) is formed in each heat-radiating plate (7), two ends of each snake-shaped cooling water channel (9) penetrate through the side wall of each heat-radiating plate (7), and connecting screw cylinders (10) corresponding to two ends of each snake-, a fixed screw cylinder (11) is sleeved on the external thread of the connecting screw cylinder (10), and a cooling water pipe (12) is fixedly connected to the rear end of the fixed screw cylinder (11);

two locating pieces (13) of rear side symmetry fixedly connected with of heat-conducting plate (4), the bar opening that the rear end of locating piece (13) was seted up through casing (1) lateral wall runs through in casing (1), the inner wall fixedly connected with of casing (1) is located fixed block (14) between two locating pieces (13), through the fixed joint of positioning mechanism between fixed block (14) and locating piece (13).

2. The easy-to-package thin film capacitor for the new energy automobile as claimed in claim 1, wherein: the thin film capacitor bodies (6) are arranged in parallel.

3. The easy-to-package thin film capacitor for the new energy automobile as claimed in claim 1, wherein: the one end outer wall of fixed spiral shell section of thick bamboo (11) is fixed to be cup jointed and is expanded crown plate (15) outward, a plurality of jacks that are the annular distribution and set up and jack internalization are evenly seted up on the surface of expanding crown plate (15) outward and are inserted and be equipped with chucking inserted bar (16), a plurality of chucking slots (17) that correspond the grafting with chucking inserted bar (16) are seted up in the outside of heating panel (7), many the same annular arm-tie (18) of one end fixedly connected with of chucking inserted bar (16), annular arm-tie (18) and outer crown plate (15) expand crown plate (15) one side fixedly connected with a plurality of covers and establish chucking spring (19) outside chucking inserted bar (16).

4. The easy-to-package thin film capacitor for the new energy automobile as claimed in claim 1, wherein: positioning mechanism is including offering inside cavity (20) in the middle of fixed block (14), cavity (20) relative one side inner wall from top to bottom is rotated through ball bearing and is connected with same bull stick (21), the lower extreme of bull stick (21) runs through the lower extreme and fixedly connected with bull stick (22) that stretch out fixed block (14), the pole wall of bull stick (21) is fixed to be cup jointed a plurality of initiative bevel gear (23), a plurality of logical groove (24) that correspond with initiative bevel gear (23) are all seted up to the both sides of carrying on the back of the body of fixed block (14), it has cup jointed adjusting screw (25) to rotate through ball bearing in logical groove (24), the one end fixedly connected with of adjusting screw (25) and driven bevel gear (26) of initiative bevel gear (23) meshing, the other end pole wall external screw thread of adjusting screw (25) has cup jointed location barrel (27), a plurality of locating hole (28) that cup joint with location barrel (27) screw thread are seted up to the lateral wall of ).

5. The conveniently-packaged thin-film capacitor for the new energy automobile as claimed in claim 4, wherein: the through groove (24) and the positioning screw cylinder (27) are of corresponding rectangular structures.

6. The conveniently-packaged thin-film capacitor for the new energy automobile as claimed in claim 4, wherein: the lower extreme fixedly connected with of fixed block (14) is located fixed axle (29) of commentaries on classics piece (22) one side, the lower extreme of fixed axle (29) rotates through ball bearing and is connected with baffle (30) of crimping at commentaries on classics piece (22) downside, the surface of baffle (30) has been seted up two jacks and jack internalization and has been inserted and be equipped with spacing inserted bar (31), the lower extreme of commentaries on classics piece (22) is seted up and is corresponded spacing slot (32) of pegging graft with spacing inserted bar (31), two the same arm-tie (33) that resets of lower extreme fixedly connected with of spacing inserted bar (31), reset arm-tie (33) and baffle (30) are established in spacing inserted bar (31) outer spacing spring (34) in two fixedly connected with covers in one side.

7. The easy-to-package thin film capacitor for the new energy automobile as claimed in claim 1, wherein: the heat conducting plate (4) and the heat conducting sleeve (5) are both made of copper alloy.

8. The easy-to-package thin film capacitor for the new energy automobile as claimed in claim 1, wherein: the input positive busbar (2) and the input negative busbar (3) are electrically connected with the thin film capacitor body (6) in a welding mode.

9. The conveniently-packaged thin-film capacitor for the new energy automobile as claimed in claim 4, wherein: the outer wall of the rotating block (22) is coated with a layer of anti-skid and wear-resistant rubber pad.

Technical Field

The invention relates to the technical field of thin film capacitors, in particular to a thin film capacitor convenient to package and used for a new energy automobile.

Background

The film capacitor is a capacitor having a structure in which a metal foil is used as an electrode, and the metal foil is laminated with a plastic film such as polyethylene, polypropylene, polystyrene, or polycarbonate from both ends thereof, and then wound into a cylindrical shape. The plastic film is also called a poly (ethyl ester) capacitor (also called a Mylar) capacitor, a polypropylene capacitor (also called a PP capacitor), a polystyrene capacitor (also called a PS capacitor) and a polycarbonate capacitor, respectively, depending on the type of the plastic film.

In the design of a power supply part of a new energy automobile, a high-voltage-withstanding film capacitor needs to be adopted for smoothing and filtering, and with the increasing use of new energy electric automobiles, the development and production of high-voltage large-capacity film capacitors are paid more and more attention by more and more people. The quality and the service life of a new energy automobile power supply are directly influenced by the electrical performance, the safety performance and the applicability of a high-temperature environment of the capacitor, however, the existing capacitor has low safety performance and weak capability of bearing surge current and mechanical impact; meanwhile, the inductance of the device is large, and the oscillation effect is serious under high frequency; in addition, the shell and the potting material of the conventional capacitor are easy to crack under a high-temperature environment; and the whole capacitor has complex manufacturing process and cannot meet the requirements of the use and development of new energy automobile power supplies.

Patent with patent grant publication number CN 210272089U proposes a film capacitor for new energy automobile, which is characterized in that: the thin film capacitor comprises a shell, a thin film capacitor assembly, an input positive busbar and an input negative busbar; the thin film capacitor assembly comprises a plurality of thin film capacitors connected in parallel, and the thin film capacitors are fixedly arranged on the outer side of the shell; the input positive busbar and the input negative busbar respectively comprise pin terminals and sheet terminals, and the input positive busbar and the input negative busbar are fixedly arranged at the top of the shell; the thin film capacitor assembly is respectively electrically connected with the input positive busbar and the input negative busbar, and the input ends of the independent IGBTs are respectively connected with pin terminals of the input positive busbar or pin terminals of the input negative busbar, for example, the independent IGBTs can be connected in a welding mode, so that direct current electric transmission processed by capacitance can be conducted into the independent IGBTs and converted into alternating current to be output. And then through adopting independent IGBT, reduce the high price of encapsulation IGBT module and give the cost pressure that relevant manufacturing enterprise brought, nevertheless the casing does not have fine fixed establishment to film capacitor, leads to connecting the steadiness relatively poor, causes the problem that drops easily, and film capacitor can produce great heat when using, if can not take away the heat and can influence film capacitor's normal use.

Disclosure of Invention

Technical problem to be solved

Aiming at the defects of the prior art, the invention provides the film capacitor for the new energy automobile, which is convenient to package, has the advantages of being capable of quickly taking away heat generated in the use of a film capacitor body and realizing the quick and stable fixed installation of the film capacitor body, is convenient to package and use, and solves the problems that a shell does not have a good fixing mechanism for the film capacitor, so that the connection stability is poor, and the falling is easily caused, and the film capacitor can generate larger heat in the use process, and the normal use of the film capacitor can be influenced if the heat cannot be taken away.

(II) technical scheme

In order to realize the purposes of quickly taking away heat generated in the use of the thin film capacitor body, quickly and stably fixing and mounting the thin film capacitor body and facilitating packaging and use, the invention provides the following technical scheme: a thin film capacitor for a new energy automobile convenient to package comprises a shell, wherein an input positive busbar and an input negative busbar are fixedly arranged at the top of the shell, the four sides of the shell are fixedly clamped with heat conducting plates, the outer sides of the heat conducting plates are fixedly connected with a plurality of heat conducting sleeves, a thin film capacitor body is inserted in the heat conducting sleeve, the upper end and the lower end of the shell are fixedly connected with heat dissipation plates, the opposite sides of the two heat dissipation plates are fixedly connected with heat dissipation sleeves which are clamped and sleeved at the two ends of the thin film capacitor body, a snakelike cooling water channel is arranged inside the heat dissipation plate, two ends of the snakelike cooling water channel penetrate through the side wall of the heat dissipation plate, the side wall of the heat dissipation plate is fixedly connected with connecting screw cylinders corresponding to two ends of the serpentine cooling water channel, the external threads of the connecting screw cylinders are sleeved with fixed screw cylinders, and the rear ends of the fixed screw cylinders are fixedly connected with cooling water pipes;

two locating pieces of the rear side symmetry fixedly connected with of heat-conducting plate, the bar opening that the rear end of locating piece was seted up through the casing lateral wall runs through in the casing, the inner wall fixedly connected with of casing is located the fixed block between two locating pieces, through the fixed joint of positioning mechanism between fixed block and the locating piece.

Preferably, a plurality of the thin film capacitor bodies are arranged in parallel.

Preferably, the fixed cover of the one end outer wall of fixed spiral shell section of thick bamboo has connect outer ring expansion plate, a plurality of jacks that are the annular distribution setting and jack internalization are evenly seted up on the surface of outer ring expansion plate and are inserted and be equipped with the chucking inserted bar, a plurality of chucking slots that correspond the grafting with the chucking inserted bar are seted up in the outside of heating panel, many the same annular arm-tie of one end fixedly connected with of chucking inserted bar, annular arm-tie and outer ring expansion plate one side fixedly connected with a plurality of covers establish the chucking spring outside the chucking inserted bar in opposite directions.

Preferably, positioning mechanism is including seting up the inside cavity in the middle of the fixed block, the cavity is relative one side inner wall from top to bottom and is rotated through ball bearing and is connected with same bull stick, the lower extreme of bull stick runs through the lower extreme and the fixedly connected with bull stick that stretch out the fixed block, a plurality of initiative bevel gear have been cup jointed to the pole wall of bull stick fixed, a plurality of logical grooves that correspond with initiative bevel gear have all been seted up to the back of the body both sides of carrying on the back of the body of fixed block, it has cup jointed adjusting screw to rotate through ball bearing in the logical inslot, adjusting screw's one end fixedly connected with and initiative bevel gear engaged from the bevel gear, adjusting screw's other end pole wall external screw thread has cup jointed the location spiral shell, a plurality of locating holes.

Preferably, the through groove and the positioning screw cylinder are of corresponding rectangular structures.

Preferably, the lower extreme fixedly connected with of fixed block is located the fixed axle of commentaries on classics piece one side, the lower extreme of fixed axle rotates through ball bearing and is connected with the baffle of crimping in commentaries on classics piece downside, the surface of baffle has been seted up two jacks and jack internalization and has been inserted and be equipped with spacing inserted bar, the lower extreme of commentaries on classics piece is seted up and is corresponded the spacing slot of pegging graft with spacing inserted bar, two the same arm-tie that resets of lower extreme fixedly connected with of spacing inserted bar, the arm-tie that resets and two covers of baffle opposite one side fixedly connected with cover are established at the spacing spring outside.

Preferably, the heat conducting plate and the heat conducting sleeve are made of copper alloy.

Preferably, the input positive busbar and the input negative busbar are electrically connected with the thin film capacitor body in a welding mode.

Preferably, the outer wall of the rotating block is coated with a layer of anti-skid and wear-resistant rubber pad.

(III) advantageous effects

Compared with the prior art, the invention provides the film capacitor for the new energy automobile, which is convenient to package, and has the following beneficial effects:

1. this film capacitor for new energy automobile of convenient encapsulation, through the casing that is equipped with, the fixed joint high-speed joint that the heat-conducting plate passes through locating piece and fixed block is outside the casing, again with film capacitor body plug bush in the heat conduction sleeve, the heat dissipation cover card cover of two upper and lower heating panel lateral walls is at the both ends of film capacitor body, can take away the heat that produces in using film capacitor body fast and can realize the quick firm fixed mounting to film capacitor body, the encapsulation of being convenient for is used, through condenser tube to the snakelike cooling water course injection recirculated cooling water in the heating panel, can effectively improve the heat dispersion of heating panel, the thermal diffusivity to film capacitor body has been guaranteed.

2. This film capacitor for new energy automobile of convenient encapsulation, through fixed block and the locating piece that is equipped with, again with the heat-conducting plate joint behind the casing outside, two locating pieces keep off and connect in the both sides of fixed block, rotate the commentaries on classics piece, the commentaries on classics piece passes through the bull stick and drives the rotation of drive bevel gear, the meshing effect of rethread drive bevel gear and driven bevel gear drives many adjusting screw synchronous rotations, the screw cup joints the effect through adjusting screw and location spiral shell and makes the location spiral shell stretch out the fixed block and block in the locating hole of locating piece lateral wall, can realize fixing the quick firm of heat-conducting plate, and convenient to use.

3. This film capacitor for new energy automobile of convenient encapsulation, through the connection spiral shell section of thick bamboo and the fixed spiral shell section of thick bamboo that is equipped with, threaded connection effect through connection spiral shell section of thick bamboo and fixed spiral shell section of thick bamboo makes condenser tube and snakelike cooling water course high-speed joint be in the same place, expand the crown plate outward this moment and support the outside at the heating panel, the chucking slot is aimed at to the chucking inserted bar, chucking spring pullback annular arm-tie, annular arm-tie can realize in advancing the chucking slot with the chucking inserted bar and stabilize spacingly to fixed spiral shell section of thick bamboo, connection structure's steadiness has been guaranteed.

Drawings

Fig. 1 is a schematic structural diagram of a thin film capacitor for a new energy vehicle, which is provided by the invention and is convenient to package;

fig. 2 is a schematic structural diagram of connection between a fixing block and a positioning block of a conveniently packaged thin film capacitor for a new energy vehicle according to the present invention;

fig. 3 is a schematic top sectional view of a heat sink plate of a thin film capacitor for a new energy vehicle, which is provided by the present invention and is convenient to package;

fig. 4 is an enlarged view of a portion a of the thin film capacitor in fig. 2 for a new energy vehicle, which is convenient to package according to the present invention;

fig. 5 is an enlarged view of a portion B of the thin film capacitor for the new energy vehicle, which is provided by the present invention and is easy to package.

In the figure: the device comprises a shell 1, a 2-input positive busbar, a 3-input negative busbar, a 4-heat conducting plate, a 5-heat conducting sleeve, a 6-film capacitor body, a 7-heat radiating plate, a 8-heat radiating sleeve, a 9-snake-shaped cooling water channel, a 10-connecting screw cylinder, a 11-fixing screw cylinder, a 12-cooling water pipe, a 13-positioning block, a 14-fixing block, a 15-outer expanding ring plate, a 16-clamping insertion rod, a 17-clamping insertion groove, a 18-annular pulling plate, a 19-clamping spring, a 20-cavity, a 21-rotating rod, a 22-rotating block, a 23-driving bevel gear, a 24-through groove, a 25-adjusting screw, a 26-driven bevel gear, a 27-positioning screw cylinder, a 28-positioning hole.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1-5, a thin film capacitor for a new energy vehicle convenient to package includes a housing 1, the top of the housing 1 is fixedly provided with an input positive busbar 2 and an input negative busbar 3, four sides of the housing 1 are fixedly clamped with heat conducting plates 4, the outer sides of the heat conducting plates 4 are fixedly connected with a plurality of heat conducting sleeves 5, the heat conducting sleeves 5 are inserted and sleeved with a thin film capacitor body 6, the upper and lower ends of the housing 1 are fixedly connected with heat radiating plates 7, opposite sides of the two heat radiating plates 7 are fixedly connected with heat radiating sleeves 8 clamped and sleeved at two ends of the thin film capacitor body 6, the inside of the heat radiating plates 7 is provided with a serpentine cooling water channel 9, two ends of the serpentine cooling water channel 9 penetrate through the side walls of the heat radiating plates 7, the side walls of the heat radiating plates 7 are fixedly connected with connecting screw cylinders 10 corresponding to two ends of the serpentine cooling water channel 9, external threads of the connecting;

two positioning blocks 13 are symmetrically and fixedly connected to the rear side of the heat conducting plate 4, a strip-shaped opening formed in the side wall of the shell 1 penetrates through the shell 1 at the rear end of each positioning block 13, a fixing block 14 located between the two positioning blocks 13 is fixedly connected to the inner wall of the shell 1, and the fixing blocks 14 and the positioning blocks 13 are fixedly clamped through a positioning mechanism.

The plurality of thin film capacitor bodies 6 are arranged in parallel.

The fixed cover of the one end outer wall of fixed spiral shell section of thick bamboo 11 has connect and expands crown plate 15 outward, expand crown plate 15's surface evenly to offer a plurality of jacks that are the annular distribution setting and jack internalization insert and be equipped with chucking inserted bar 16, the outside of heating panel 7 is offered a plurality of chucking slots 17 that correspond the grafting with chucking inserted bar 16, the same annular arm-tie 18 of one end fixedly connected with of many chucking inserted bar 16, annular arm-tie 18 and expand crown plate 15 one side fixedly connected with a plurality of cover and establish chucking spring 19 outside chucking inserted bar 16 outward.

Positioning mechanism is including seting up at inside cavity 20 in the middle of fixed block 14, cavity 20 relative one side inner wall rotates through ball bearing and is connected with same bull stick 21 from top to bottom, the lower extreme of bull stick 21 runs through the lower extreme and the fixedly connected with bull stick 22 that stretch out fixed block 14, the pole wall of bull stick 21 is fixed to be cup jointed a plurality of initiative bevel gear 23, a plurality of logical grooves 24 that correspond with initiative bevel gear 23 have all been seted up to the back of the body both sides that carry on the back of the body of fixed block 14, it has cup jointed adjusting screw 25 to rotate through ball bearing in the logical groove 24, adjusting screw 25's one end fixedly connected with and the driven bevel gear 26 of initiative bevel gear 23 meshing, adjusting screw 25's other end pole wall external screw thread has cup jointed location spiral shell 27, a plurality of locating hole 28 with.

The through groove 24 and the positioning screw cylinder 27 are of corresponding rectangular structures.

The lower extreme fixedly connected with of fixed block 14 is located the fixed axle 29 of changeing piece 22 one side, the lower extreme of fixed axle 29 rotates through ball bearing and is connected with the baffle 30 of crimping in changeing the piece 22 downside, two jacks and jack internalization have been seted up on the surface of baffle 30 and have been inserted and be equipped with spacing inserted bar 31, the lower extreme of changeing piece 22 is seted up and is corresponded the spacing slot 32 of pegging graft with spacing inserted bar 31, the same arm-tie 33 that resets of lower extreme fixedly connected with of two spacing inserted bars 31, reset arm-tie 33 and baffle 30 opposite side fixedly connected with two cover establish spacing spring 34 outside spacing inserted bar 31.

The heat conducting plate 4 and the heat conducting sleeve 5 are made of copper alloy.

The input positive busbar 2 and the input negative busbar 3 are electrically connected with the thin film capacitor body 6 in a welding mode.

The outer wall of the rotating block 22 is coated with a layer of anti-skid and wear-resistant rubber pad.

In summary, the conveniently packaged thin film capacitor for the new energy automobile is characterized in that the heat conducting plate 4 is quickly connected to the outside of the casing 1 through the fixed clamping of the positioning blocks 13 and the fixing blocks 14 through the casing 1, the thin film capacitor body 6 is inserted and sleeved in the heat conducting sleeve 5, the heat radiating sleeves 8 on the side walls of the upper heat radiating plate 7 and the lower heat radiating plate 7 are clamped and sleeved at two ends of the thin film capacitor body 6, heat generated during the use of the thin film capacitor body 6 can be quickly taken away, the thin film capacitor body 6 can be quickly and stably fixedly mounted, the packaging use is convenient, circulating cooling water is injected into the snakelike cooling water channel 9 in the heat radiating plate 7 through the cooling water pipe 12, the heat radiating performance of the heat radiating plate 7 can be effectively improved, the heat radiating performance of the thin film capacitor body 6 is ensured, the heat conducting plate 4 is clamped to the outside of the casing 1 through the fixing blocks 14, the rotating block 22 is rotated, the rotating block 22 drives the driving bevel gear 23 to rotate through the rotating rod 21, the plurality of adjusting screw rods 25 are driven to synchronously rotate through the meshing action of the driving bevel gear 23 and the driven bevel gear 26, the positioning screw cylinders 27 extend out of the fixing blocks 14 and are clamped into the positioning holes 28 in the side walls of the positioning blocks 13 through the threaded sleeve function of the adjusting screw rods 25 and the positioning screw cylinders 27, the heat conducting plate 4 can be quickly and stably fixed and is convenient to use, the cooling water pipe 12 and the serpentine cooling water channel 9 are quickly connected together through the threaded connection action of the connecting screw cylinders 10 and the fixing screw cylinders 11 through the arrangement of the connecting screw cylinders 10 and the fixing screw cylinders 11, the outer expanding ring plate 15 is abutted against the outer side of the heat radiating plate 7, the clamping inserting rod 16 is aligned with the clamping slot 17, the clamping spring 19 pulls the annular pulling plate 18 back, the annular pulling plate 18 pushes the clamping inserting rod 16 into the clamping slot 17, and then the fixing screw cylinders, the stability of the connecting structure is ensured.

It is to be noted that 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.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.