Disclosure of Invention
The invention provides a liquid helium transfer pipe joint device, a liquid helium transfer pipe and an assembly method, which are used for solving the defects that a liquid helium infusion pipe in the prior art is not expandable, and time and labor are wasted and cost is increased due to redesign or purchase for normal operation of experiments or engineering.
The invention provides a liquid helium transfer line interface device, comprising:
The external connection assembly comprises a switching part and two external connection parts, wherein the switching part and the two external connection parts enclose an installation space, the two external connection parts are arranged at intervals and are respectively used for connecting two liquid helium transmission pipes, the external connection parts comprise a connecting pipe and a heat insulation pipe, the connecting pipe is used for connecting an outer pipe of the liquid helium transmission pipe, the heat insulation pipe is connected to the inner wall of the connecting pipe, and the heat insulation pipe is provided with a connecting hole for the inner pipe of the liquid helium transmission pipe to pass through;
The inner connecting assembly comprises an inner connecting part and an adsorption piece, wherein the inner connecting part is used for connecting the inner pipes of the two liquid helium transmission pipes, and the adsorption piece is used for adsorbing impurity gas in the installation space so that the installation space is in a vacuum environment.
According to the liquid helium transport pipe joint device provided by the embodiment of the invention, the switching component comprises two compression end covers and a switching pipe detachably connected between the two compression end covers, and the two compression end covers are respectively arranged on the connecting pipes of the two external connecting components.
According to the liquid helium transmission pipe joint device provided by the embodiment of the invention, the compression end cover is in threaded connection with the switching pipe.
According to the liquid helium transport pipe joint device provided by the embodiment of the invention, the compression end cover is provided with the threaded blind hole, and the adapter pipe is provided with the external thread matched with the threaded blind hole.
According to the liquid helium transmission pipe joint device provided by the embodiment of the invention, a sealing element is arranged between the transfer pipe and the connecting pipe.
According to the liquid helium transport pipe joint device provided by the embodiment of the invention, the heat insulation pipe comprises at least one radial heat insulation pipe section and at least one axial heat insulation pipe section, the radial heat insulation pipe section and the axial heat insulation pipe section are alternately connected, and the radial heat insulation pipe section or the axial heat insulation pipe section farthest from the connecting pipe is provided with the connecting hole.
According to the liquid helium transfer pipe joint device provided by the embodiment of the invention, the inner connecting assembly comprises two sealing flanges which are respectively used for being connected with the two inner pipes.
According to an embodiment of the present invention, there is provided a liquid helium transporting pipe joint device, wherein the adsorbing member comprises an activated carbon ring or a molecular sieve ring for being mounted to the inner pipe.
The invention also provides a liquid helium transmission pipeline which comprises at least two liquid helium transmission pipes and any liquid helium transmission pipe interface device, wherein two adjacent liquid helium transmission pipes are connected through the liquid helium transmission pipe interface device.
The invention also provides a liquid helium transmission pipeline assembly method based on the liquid helium transmission pipeline, which comprises the following steps:
The inner pipes of two adjacent liquid helium transmission pipes are connected in a sealing way through an inner connecting assembly, and an adsorption piece is arranged on the inner pipes;
Connecting the connecting pipes of the two outer connecting parts with the outer pipes of the two liquid helium transmission pipes respectively, and sleeving the heat insulation pipes of the two outer connecting parts with the inner pipes of the two liquid helium transmission pipes;
the connecting pipes of the two outer connecting parts are detachably connected through the adapting part.
According to the liquid helium transmission pipe interface device, the connecting pipes of the two outer connecting parts are connected to the outer pipes of the two liquid helium transmission pipes, the inner walls of the connecting pipes are connected with the heat-insulation pipes through which the inner pipes of the liquid helium transmission pipes pass, the heat-insulation pipes can seal a vacuum interlayer between the outer pipes and the inner pipes of the liquid helium transmission pipes, the two outer connecting parts are detachably connected through the switching parts so as to realize the disassembly and assembly of the two outer connecting parts, the inner pipes of the two liquid helium transmission pipes are connected through the inner connecting parts, so that the disassembly and assembly of the two liquid helium transmission pipes are realized, the length of a liquid helium transmission pipeline is changed, the length of the liquid helium transmission pipeline can be expanded according to the length requirement of the liquid helium transmission pipe in an experiment or engineering, the experiment efficiency is improved, and the experiment cost is reduced.
Detailed Description
Embodiments of the present invention are described in further detail below with reference to the accompanying drawings and examples. The following examples are illustrative of the invention but are not intended to limit the scope of the invention.
In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the apparatus or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the embodiments of the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In describing embodiments of the present invention, it should be noted that, unless explicitly stated or limited otherwise, the terms "connected," "connected," and "coupled" should be construed broadly, and may be, for example, fixedly connected, detachably connected, integrally connected, mechanically connected, electrically connected, directly connected, or indirectly connected via an intermediate medium. The specific meaning of the above terms in embodiments of the present invention will be understood in detail by those of ordinary skill in the art.
In embodiments of the invention, unless expressly specified and limited otherwise, a first feature "up" or "down" on a second feature may be that the first and second features are in direct contact, or that the first and second features are in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the embodiments of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
An embodiment of the present invention proposes a liquid helium delivery tube interface device for connecting two liquid helium delivery tubes, as shown in fig. 1, comprising an outer connection assembly and an inner connection assembly.
The outer connecting component is used for connecting the outer tubes of the two liquid helium transmission tubes and comprises a switching component and two outer connecting components, wherein the switching component and the two outer connecting components enclose an installation space, the two outer connecting components are arranged at intervals relatively and are respectively used for connecting the outer tubes of the two liquid helium transmission tubes, and the switching component can be detachably connected to the two outer connecting components so as to realize connection and separation of the two outer connecting components.
The inner connection assembly comprises an inner connection part 9 for connecting the inner tubes of the two liquid helium delivery pipes, the two outer connection parts are connected through the switching part to realize the outer tube connection of the two liquid helium delivery pipes, and the inner tubes of the two liquid helium delivery pipes are connected through the inner connection part 9.
The outer connecting part comprises a connecting pipe and a heat insulation pipe, the connecting pipe is used for connecting an outer pipe of the liquid helium transmission pipe, the heat insulation pipe is connected to the inner wall of the connecting pipe, the heat insulation pipe is provided with a connecting hole through which an inner pipe of the liquid helium transmission pipe passes, when the connecting pipe is connected with the outer pipe of the liquid helium transmission pipe, the inner pipe of the liquid helium transmission pipe passes through the connecting hole of the heat insulation pipe, and the heat insulation pipe can seal a vacuum interlayer between the outer pipe and the inner pipe of the liquid helium transmission pipe.
When the outer pipes of the two liquid helium delivery pipes are connected by the outer connecting component and the inner pipes of the two liquid helium delivery pipes are connected by the inner connecting component 9, the inner pipes of the two liquid helium delivery pipes are positioned in the installation space formed by the outer connecting component, and if the installation space is in an atmospheric environment, the low-temperature liquid helium can be lost when the inner pipes positioned in the installation space are delivered. Therefore, the connecting assembly in this embodiment further includes an adsorption member for adsorbing impurity gas in the installation space so as to make the installation space in a vacuum environment, thereby avoiding liquid helium loss when cryogenic liquid helium is transferred from the inner tube located in the installation space.
When the length of the liquid helium transmission pipes needs to be increased, the two liquid helium transmission pipes with the outer connecting parts at the ends are arranged oppositely, the inner pipes of the two liquid helium transmission pipes extend out of the heat insulation pipes, the inner pipes of the two liquid helium transmission pipes are connected through the inner connecting parts 9, and after the inner pipes of the two liquid helium transmission pipes are connected through the inner connecting parts 9, the outer connecting parts on the outer pipes of the two liquid helium transmission pipes are connected through the switching parts, so that the connection of the two liquid helium transmission pipes is completed.
When the length of the liquid helium delivery pipes needs to be shortened, the outer connecting parts on the outer pipes of the two liquid helium delivery pipes are separated through the switching parts, and then the inner pipes of the two liquid helium delivery pipes are separated through the inner connecting parts 9, so that the connection of the two liquid helium delivery pipes is removed.
According to the liquid helium transmission tube interface device provided by the embodiment of the invention, the connecting tube of the two outer connecting parts is connected with the outer tubes of the two liquid helium transmission tubes, the inner wall of the connecting tube is connected with the heat insulation tube through which the inner tube of the liquid helium transmission tube passes, the heat insulation tube can seal the vacuum interlayer between the outer tube and the inner tube of the liquid helium transmission tube, the two outer connecting parts are detachably connected through the switching part so as to realize the disassembly and assembly of the two outer connecting parts, the inner tubes of the two liquid helium transmission tubes are connected through the inner connecting part 9, so that the disassembly and assembly of the two liquid helium transmission tubes are realized, the change of the length of a liquid helium transmission pipeline is realized, the length of the liquid helium transmission pipeline can be expanded according to the length requirement of the liquid helium transmission tube in an experiment or engineering, the experiment efficiency is improved, and the experiment cost is reduced.
In one embodiment of the invention, the adapter part comprises two compression end caps and an adapter tube 6 detachably connected between the two compression end caps, the two compression end caps being arranged on the connecting tubes of the two outer connecting parts, respectively.
It can be understood that the connecting pipe is connected with the compression end cover, and is connected with the two compression end covers through the adapter pipe 6, so that the adapter pipe 6 is connected with the two compression end covers, and then the connection of the outer pipes of the two liquid helium transmission pipes on the compression end covers is realized.
In the embodiment of the invention, the compression end cap is screwed with the adapter tube 6. It can be understood that the adapter tube 6 is assembled between the outer tubes of the two liquid helium delivery tubes, the compression end covers are assembled on the connecting tubes connected to the outer tubes of the two liquid helium delivery tubes, the two compression end covers are made to be close to each other, so that the two compression end covers and the adapter tube 6 are connected, the two outer connecting parts are connected with the adapter part, namely, the outer tubes of the two liquid helium delivery tubes are connected through the outer connecting assembly, and the two compression end covers are made to be far away from each other, so that the two compression end covers and the adapter tube 6 are separated, and the outer tubes of the two liquid helium delivery tubes are separated.
According to the liquid helium transmission pipe interface device provided by the embodiment of the invention, the switching part is realized through the two compression end covers and the switching pipe 6 which is detachably connected, so that the outer pipes of the two liquid helium transmission pipes can be quickly disassembled and assembled, and the device has the characteristics of compact structure and convenience in disassembly and assembly.
Further, the compression end cover is provided with a threaded blind hole, and the adapter tube 6 is provided with external threads matched with the threaded blind hole.
Illustratively, the outer end surface of the compression end cover is provided with a threaded blind hole, and the outer side surface of the adapter tube 6 is provided with external threads matched with the threaded blind hole.
It can be understood that the compression end cover is assembled on the connecting pipe, the compression end cover can rotate relative to the connecting pipe, when the outer pipes of the two liquid helium transmission pipes are connected, the compression end covers on the outer pipes of the two liquid helium transmission pipes are oppositely arranged, that is, the threaded blind holes of the two compression end covers are close to each other, the adapter pipe 6 is lapped between the two connecting pipes, the two ends of the adapter pipe 6 are arranged at the threaded blind holes of the two compression end covers, and the bottom surface of the threaded blind holes realizes the limiting of the axial position of the adapter pipe 6.
Still further, be provided with the sealing member between adapter tube 6 and the connecting pipe, realize the sealing connection between adapter tube 6 and the connecting pipe, and then realize the sealing to the installation room. The sealing element is, for example, a sealing ring 7 arranged between the adapter tube 6 and the connecting tube, preferably, for improving the tightness, two sealing rings 7 are arranged at intervals.
In one embodiment of the invention, the adsorption element comprises an active carbon ring or a molecular sieve ring which is positioned in the installation room and is arranged on the inner pipe, so that impurity gas in the installation room is absorbed, a high-vacuum pipeline interlayer is further obtained, heat leakage in the liquid helium transmission process is reduced, and the transmission efficiency of low-temperature liquid is ensured.
It should be noted that, the active carbon ring can be dismantled and set up in the inner tube, and the active carbon ring can be installed to the inner tube fast when needs, can dismantle fast when not needing, toasts the degasification to realize reuse.
In one embodiment of the invention, the inner connection assembly comprises two sealing flanges for connection to the two inner tubes, respectively.
In one embodiment of the invention, the insulating tube comprises at least one radial insulating tube section and at least one axial insulating tube section, the radial insulating tube section and the axial insulating tube section being alternately connected, the radial insulating tube section or the axial insulating tube section furthest from the connecting tube having a connecting hole. The connecting hole is formed in the radial heat-insulating pipe section when the connecting pipe is farthest from the radial heat-insulating pipe section, and the connecting hole is formed in the axial heat-insulating pipe section when the connecting pipe is farthest from the axial heat-insulating pipe section.
It is understood that the heat insulation plate adopts a mode of alternately connecting radial heat insulation pipe sections and axial heat insulation pipe sections, so that the heat insulation plate is similar to a labyrinth structure, and by utilizing the structure, lower heat leakage between the inner pipe and the outer pipe of the liquid helium transmission pipe can be realized, and meanwhile, the vacuum in the installation space is ensured not to be leaked.
For example, as shown in fig. 1, the heat-insulating tube includes two radial heat-insulating tube sections and one axial heat-insulating tube section, and then the heat-insulating tube includes a radial heat-insulating tube section, an axial heat-insulating tube section and a radial heat-insulating tube section that are sequentially connected, and then one end of one radial heat-insulating tube section is connected to the connecting tube, the other end of one radial heat-insulating tube section is connected to one end of the axial heat-insulating tube section, the other end of the other radial heat-insulating tube section is connected to one end of the other radial heat-insulating tube section, and the other end of the other radial heat-insulating tube section is provided with a connecting hole and is coaxially sleeved on the inner tube of the liquid helium transmission tube.
The embodiment of the invention also provides a liquid helium transmission pipeline, as shown in fig. 1, which comprises at least two liquid helium transmission pipes and the liquid helium transmission pipe interface device provided by any embodiment, wherein two adjacent liquid helium transmission pipes are connected through the liquid helium transmission pipe interface device.
The outer pipes of the two liquid helium transmission pipes are connected through an outer connecting component, the outer connecting component comprises two outer connecting parts and a switching part, and the two outer connecting parts are respectively connected with the outer pipes of the two liquid helium transmission pipes.
The liquid helium transmission pipe is connected with a connecting pipe coaxially arranged at the outer side of the inner pipe, the inner wall of the connecting pipe is provided with a heat insulation pipe, the inner pipe of the liquid helium transmission pipe penetrates out of a connecting hole of the heat insulation pipe, and the heat insulation pipe is connected with the inner pipe of the liquid helium transmission pipe in a sealing mode.
The transfer component comprises two compression end covers and transfer pipes 6, each connecting pipe is provided with a compression end cover, the connection of the transfer pipes 6 and the two compression end covers is realized by the connection of the outer pipes of the two liquid helium transmission pipes, and the separation of the transfer pipes 6 and the two compression end covers is realized by the separation of the outer pipes of the two liquid helium transmission pipes. In this embodiment, the adapter tube 6 is in threaded connection with the two compression end covers, so that the adapter tube 6 and the compression end covers are convenient to connect and separate.
Wherein, the inner pipes of the two liquid helium delivery pipes are connected through the inner connecting part 9, and then the inner connecting part 9 comprises two matched inner connecting pieces, and the inner connecting pieces are connected at the end parts of the inner pipes of the liquid helium delivery pipes. For example, the inner connecting part 9 adopts a low-temperature sealing flange, the low-temperature sealing flange comprises two sealing flanges (inner connecting parts) which are matched, one end of the inner pipe extending out of the heat insulation pipe is connected with the sealing flanges, and the connection and the separation of the inner pipes of the two liquid helium transmission pipes are realized through the connection and the separation of the sealing flanges on the two inner pipes.
According to the liquid helium transmission pipeline provided by the embodiment of the invention, the two liquid helium transmission pipes are detachably connected through the liquid helium transmission pipe joint device, so that the expansion of the liquid helium transmission pipe on the length of the flexible pipeline can be realized, the length of the liquid helium transmission pipeline can be prolonged or shortened at any time according to requirements, and the liquid helium transmission pipeline has excellent expansibility, so that the smooth progress of a scientific experiment is ensured, the experimental efficiency is greatly improved, the experimental cost is reduced, and the expansibility of the liquid helium transmission pipeline is improved.
In one embodiment of the present invention, the interface device is used to connect two liquid helium delivery tubes, the liquid helium delivery tube interface device comprising an outer connection assembly and an inner connection assembly.
As shown in fig. 1, the two liquid helium transfer pipes are denoted as a first liquid helium transfer pipe and a second liquid helium transfer pipe, the first liquid helium transfer pipe comprises a first inner pipe 2 and a first outer pipe 1 coaxially arranged outside the first inner pipe 2, the second liquid helium transfer pipe comprises a second inner pipe 14 and a second outer pipe 15 coaxially arranged outside the second inner pipe 14, and the first outer pipe 1 and the second outer pipe 15 are both infusion hoses.
The external connection component comprises a switching component and two external connection components, wherein the external connection components comprise a connecting pipe and a heat insulation pipe, the heat insulation pipe is connected to the inner wall of the connecting pipe, and the heat insulation pipe is provided with a connecting hole through which the inner pipe of the liquid helium transmission pipe passes.
The two outer connecting parts are respectively marked as a first outer connecting part and a second outer connecting part, the first connecting part comprises a first connecting pipe 3 and a first heat insulation pipe 4, the first connecting pipe 3 is connected to the end part of the first outer pipe 1, the first inner pipe 2 coaxially penetrates through the connecting hole of the first heat insulation pipe 4, the second connecting part comprises a second connecting pipe 13 and a second heat insulation pipe 12, the second connecting pipe 13 is connected to the end part of the second outer pipe 15, and the second inner pipe 14 coaxially penetrates through the connecting hole of the second heat insulation pipe 12. The first connection pipe 3 and the second connection pipe 13 are both hard connection pipes.
The adapting part comprises two compression end covers and an adapting tube 6 which is detachably connected between the two compression end covers, the two compression end covers are respectively a first compression end cover 5 and a second compression end cover 11, the first compression end cover 5 is arranged on the first connecting tube 3, the second compression end cover 11 is arranged on the second connecting tube 13, the adapting tube 6 adopts a hard tube structure, external threads are arranged at two ends of the adapting tube 6, a first threaded blind hole matched with the external threads is formed in the outer end face of the first compression end cover 5, a second threaded blind hole matched with the external threads is formed in the outer end of the second compression end cover 11, and then the first compression end cover 5 and the second compression end cover 11 adopt a compression nut structure.
When the outer pipes of the two liquid helium transmission pipes are connected, the first connecting pipe 3 and the second connecting pipe 13 are coaxially arranged at intervals, the transfer pipe 6 is arranged between the first connecting pipe 3 and the second connecting pipe 13, O-shaped sealing rings are arranged between the transfer pipe 6 and the first connecting pipe 3 and between the transfer pipe 6 and the second connecting pipe 13, and the transfer pipe 6 is tightly pressed between the first connecting pipe 3 and the second connecting pipe 13 by rotating one or two of the first pressing end cover 5 and the second pressing end cover 11. It should be noted that, the first compression end cap 5 is connected to the first connecting pipe 3, the second compression end cap 11 is connected to the second connecting pipe 13, and the connection and separation of the adapter pipe 6 and the two compression end caps are realized by rotating the first compression end cap 5, or rotating the second compression end cap 11, or simultaneously rotating the first compression end cap 5 and the second compression end cap 11, so as to change the distance between the first compression end cap 5 and the second compression end cap 11, thereby realizing the connection and separation of the outer pipes of the two liquid helium transmission pipes.
The inner connecting assembly comprises an inner connecting part 9 and an adsorbing part, wherein the inner connecting part 9 comprises a first flange plate and a second flange plate which are matched, the first flange plate is suitable for being installed on the first inner pipe 2, the second flange plate is suitable for being installed on the second inner pipe 14, the first inner pipe 2 and the second inner pipe 14 can be connected and separated through the connection and the separation of the first flange plate and the second flange plate, and the adsorbing part comprises two active carbon rings which are arranged close to the inner connecting part 9, namely a first active carbon ring 8 arranged on the first inner pipe 2 and a second active carbon ring 10 arranged on the second inner pipe 14.
When the length of the liquid helium transmission pipeline is required to be changed through experiments, the required liquid helium transmission pipe can be quickly assembled and disassembled through the switching part, and when the inner pipe in the switching part passes low-temperature liquid helium, the active carbon ring attached to the surface of the inner pipe can adsorb impurity gas in the pipeline interlayer, so that higher vacuum is obtained, leakage heat is reduced, and further liquid helium loss in the low-temperature liquid helium transmission process is reduced.
Based on the liquid helium transmission pipeline provided in the above embodiment, the embodiment of the invention further provides a method for assembling the liquid helium transmission pipeline, as shown in fig. 2, comprising the following steps:
And 100, hermetically connecting the inner pipes of two adjacent liquid helium delivery pipes through the inner connecting assembly, and arranging the adsorption piece on the inner pipe.
Step 200, connecting the connecting pipes of the two outer connecting parts to the outer pipes of the two liquid helium transmission pipes respectively, and sleeving the heat insulation pipes of the two outer connecting parts on the inner pipes of the two liquid helium transmission pipes.
Step 300, detachably connecting the connecting pipes of the two outer connecting parts through the adapting part.
For example, firstly, the inner pipes of two adjacent liquid helium transmission pipes are connected in a sealing way through an inner connecting component, a VCR joint is adopted for sealing connection, the sealing performance at low temperature can be guaranteed, then an activated active carbon ring is installed on the infusion inner pipe, then the transfer pipe 6 is connected with a threaded blind hole of one compression end cover in a threaded way, the transfer pipe 6 is arranged between the first connecting pipe 3 and the second connecting pipe 13, O-shaped sealing rings are arranged between the transfer pipe 6 and the first connecting pipe 3 and between the transfer pipe 6 and the second connecting pipe 13, and the transfer pipe 6 is compressed between the first connecting pipe 3 and the second connecting pipe 13 through rotating the compression end cover. Here, the outer tube end of the liquid helium transfer tube is equipped with an outer connecting member, that is, the outer tube of the liquid helium transfer tube is connected with a connecting tube, and the inner wall of the connecting tube is connected with a heat insulation tube sealed and sleeved on the inner tube, so that the connection and separation of the outer tubes of the two liquid helium transfer tubes are realized only through the switching part.
In the experimental or engineering process, the liquid helium transmission pipe is respectively inserted into the liquid helium Dewar and experimental equipment for transfusion operation, when the inner pipe flows through low-temperature liquid helium, the adsorption capacity of the active carbon ring can be enhanced under the low-temperature condition, so that impurity gas in the pipeline interlayer is absorbed, a high-vacuum pipeline interlayer is obtained, the heat leakage in the liquid helium transmission process is reduced, and the transmission efficiency of low-temperature liquid is ensured.
It should be noted that the above-mentioned embodiments are merely for illustrating the technical solution of the present invention, and not for limiting the same, and although the present invention has been described in detail with reference to the above-mentioned embodiments, it should be understood by those skilled in the art that the technical solution described in the above-mentioned embodiments may be modified or some technical features may be equivalently replaced, and these modifications or substitutions do not make the essence of the corresponding technical solution deviate from the spirit and scope of the technical solution of the embodiments of the present invention.