JP5646004B2 - Radial sliding seal element for a weighing device and a weighing device having such a radial sliding seal element - Google Patents

Description

  The present invention relates to a radial sliding seal subassembly comprising a sealing element and at least one pretensioning element cooperating therewith, the sealing element being an axially and circumferentially extending sealing Having a section on which a first radially facing sealing surface is formed for sealing and for at least axial sliding contact with a working surface extending axially and circumferentially And a second radially facing pretensioning surface opposite to the first radial direction for engaging a pretensioning element for transmitting a radial pretensioning force. Is formed.

  Such radial sliding seal subassemblies are used in particular in metering devices including piston-cylinder instruments. Such metering devices are, for example, syringes, pipette devices and the like.

  In such metering devices, a common type of radial sliding seal subassembly generally serves to seal the radial gap between the cylinder wall and the wall of the piston rod that moves relative to the cylinder.

  Since these radial gaps generally extend in a complete circle in the circumferential direction, the sealing section, in particular the sealing surface formed on itself, together with the working surface, preferably in the circumferential direction It extends in a circle.

  In prior known metering devices, the sealing element flips over the O-ring and slides frequently as a radial sliding seal subassembly, which in the assembled state of the radial sliding seal subassembly is Apply radial pretensioning force. The O-ring simultaneously presses the pretensioning surface of the sealing section, thereby radially pretensioning the sealing surface opposite to the pretensioning surface in the radial direction.

  The disadvantages of these known types of radial sliding seal subassemblies are that, in part, the radial pretensioning force exerted by the O-ring as a pretensioning element can cause large dimensional errors and The fact is that it changes significantly due to large fluctuations in the material properties of the decision.

  The object of the present invention is thus to provide a universal radial pretensioning force that is as reproducible as possible and that can be used to apply radial pretensioning to the sealing surface. It is to realize a sliding seal subassembly.

  The above object is achieved according to the invention by means of a radial sliding seal subassembly of the type mentioned at the outset, in which the pretensioning element is at least radially on the spring carrier and on the spring carrier. And a plurality of separately formed radial spring segments that are elastically supported on each other.

  By providing a plurality of separately formed radial spring segments, a fixed radial pretension force can be provided, or for each circumferential section of the pretension surface associated with the radial spring segment You can even adjust to.

  In order to support the radial pretensioning force applied by the radial spring segment to the sealing element, the radial spring segment is supported on the spring carrier of the pretensioning element. The spring carrier can therefore absorb the reaction forces against the pretensioning forces applied by the individual radial spring segments.

  As used herein, whenever a radial spring segment is “radially elastically supported” on a spring carrier, at least one section of the radial spring segment that transmits the pretension force is A section of a radial spring segment that is elastically displaceable in the radial direction under the action of a radial force due to the variable or constant spring stiffness of the associated radial spring segment and transmits the pretension force Is intended to mean that it is substantially restored to its unloaded position after the action of the force has ended. In this regard, it is not excluded that the radial spring segments can also be elastically supported or movable in further directions.

  In principle, in a reasonably preferred embodiment, the radial spring segment can be formed using a helical compression spring or tension bolt spring of variable length in the radial direction. A very precisely adjustable radial pretensioning force on each individual radial spring segment can be achieved with such a helical spring, but this results in considerable and often unnecessary installation costs.

  In principle, the sealing element can also be pretensioned radially by a plurality of pretensioning elements. In this case, it is advantageous for the individual pretensioning elements to have the same shape in order to avoid unnecessarily high production costs, so that only one type of pretensioning element is produced. Good.

  If multiple pretensioning elements are desired, the individual pretensioning elements can be arranged alternately in the axial direction. In this regard, axially adjacent pretensioning elements or groups of pretensioning elements can be provided in the same or opposite direction. In this way, well-defined radial pretension conditions can be achieved in different ways, adapted to different sealing element geometries.

  A radial sliding seal subassembly with very small geometrical dimensions and at the same time very low production and / or assembly costs, the at least one radial spring segment is in relation to the spring carrier in one of its longitudinal regions It can be obtained when formed with a pretensioned axial section that is connected and is axially spaced from the longitudinal end for contact with the pretensioned surface. In this case, the radial spring segment can protrude axially from the spring carrier in the form of a leaf spring and, by means of its free longitudinal end, has a known operating configuration from an ideally clamped beam. Accordingly, elasticity may be provided in the radial direction. In this connection, the pretension axial section is provided on the radial spring segment, preferably on the area comprising the longitudinal end of the radial spring segment. However, this is not necessarily the case and the leaf spring-like radial spring segment is suitably shaped so that it is between the longitudinal end connected to the spring carrier and the free longitudinal end of the radial spring segment. The radial section present in can also be designed as a pre-tensioned axial segment, and as far as this shape is concerned, it is designed for contact with the pre-tension surface of the sealing element, i.e. the built-in state of the radial sliding seal subassembly In fact, it exists in contact with the pretension surface.

  For the effective use of the radial pretensioning force, the pretensioning surface can be arranged axially in the axial region where the sealing surface is also arranged or the two surfaces overlap in the axial direction. It is advantageous. But that doesn't have to be the case.

  A spring carrier generally can perform multiple functional tasks, one of which is holding a radial spring segment, so that the spring carrier for holding the radial spring segment has a circumferentially extending carrier section. From which at least one radial spring segment projects axially.

  As mentioned in the introduction, the sealing surface is generally designed to extend completely circular in the circumferential direction, so that the carrier section is also advantageously designed to extend completely circular in the circumferential direction. It is.

  In order to keep the required number of elements for forming the radial sliding seal subassembly according to the invention as low as possible, as many, preferably all, radial spring segments as possible in the axial section of the carrier It is advantageous to project from.

  In this regard, it is preferable to allow a radial pretensioning force to act on the sealing element over the widest possible axial region, in which case the radial spring segment projects from the carrier section in the opposite axial direction. It is possible to make it possible.

  A preferred pretensioning element (because its axial dimension is as small as possible) can however be obtained if the radial spring segments protruding from the carrier section all protrude in the same axial direction. Due to the preferred use of the radial sliding seal subassembly described herein in a metering device, if the radial spring segment protrudes axially away from the variable hollow space from the carrier section, it is normally provided in the metering device. The variable volume can be made as large as possible.

  Furthermore, in a reasonably preferred embodiment, it is conceivable to arrange the radial spring segments in an axial offset with respect to each other. However, this is less preferred because of the resulting large axial structural length of the pretensioning element.

  If the radial spring segments are arranged adjacent to one another in the circumferential direction, it is possible to ensure that the radial pre-tensioning force is exerted by the individual radial spring segments on the sealing element over substantially the entire extent of the sealing section in the circumferential direction. .

  Provide at least a radial sliding seal subassembly (which can be formed from as few individual parts as possible) if at least a portion, preferably all, of the radial spring segment is integrally formed with the carrier segment be able to. For this purpose, the entire pretensioning element can particularly preferably be formed as an integral element.

  Structurally, the pretensioning element (especially when it is formed as a unitary element) has a cylindrical section with a plurality of circumferentially adjacent axial slits for simplicity of design and construction But its axial length is shorter than that of the tubular section, and it preferably starts from one longitudinal end of the tubular section and the other of the tubular section in each case Extends to the longitudinal end. The tubular section can be designed in a “crown shape” with a ring as a carrier section and a leaf spring-like radial spring segment protruding therefrom in the same axial direction.

  In order to ensure that the pre-tensioning element of the radial sliding seal subassembly incorporated exerts the desired radial pre-tensioning force on the sealing section of the sealing element, the pre-tensioning element is It can be structurally formed such that the axial segment protrudes beyond the carrier section in the radial pretensioning direction. The radial sliding seal subassembly is generally designed such that it is provided on an element that it can move jointly with respect to other elements.

  In the use of the radial sliding seal subassembly according to the invention in a metering device with a piston-cylinder instrument, in particular in the example considered here, the radial sliding seal subassembly therefore consists of a cylinder and a piston or a piston rod It can be fixed with respect to one of the elements and can move with it relative to the individual other elements consisting of cylinders and pistons or piston rods.

  In particular, if the radial spring segment is at least partially formed in a spring leaf shape as described above, at least a portion of the radial spring segment has a radial stopper on its side facing away from the pretensioned surface in the assembled state. With the aid of a radial spring segment, the pretensioning element, and thus the radial sliding seal subassembly as a whole, is very simple and advantageous on the carrier element that holds the radial sliding seal subassembly as a whole. Can be placed in a rock king style.

  In particular, therefore, if the pretensioning axial section projects in the radial pretensioning direction with respect to the carrier section in the unloaded state, as previously described as an advantageous variant of the invention, the pretensioning element Takes advantage of the radial elastic mobility of the radial spring segments by means of the radial stop projections on at least a part of the radial spring segments, preferably on all radial spring segments, in a locking manner, for example The force that can be placed on a carrier part, such as a piston rod with a suitable stopper dimension shape, to release the lock and thus to separate the pretensioning element and the carrier element is fully integrated. In the desired direction of action of the radial pretension force To realize a radial pretension force opposite to, if the pretensioning axial section is forced against the material and / or dimensional elasticity from the working surface, is to further increase. Thus, the radial pretensioning force with which the radial spring segment presses the sealing section of the sealing element against the working surface simultaneously functions as a locking force for the pretensioning element on the carrier element that supports it.

  While the radial sliding seal subassembly is functioning, the sealing element and the pretensioning element substantially maintain their intended axial relative position, i.e. they do not displace or ignore relative to each other in the axial direction. In order to ensure that it is displaced as much as possible, it is also conceivable that the pretensioning element has a fixing device for fixing the relative position of the sealing element and the pretensioning element at least in the axial direction. In this regard, axial fixation takes precedence. This is because the sealing surface of the sealing element is in any case relatively movable in the axial direction with respect to the working surface on which it rests. As already known from the prior art, the fixation device can be designed as at least one fixation protrusion, preferably a plurality of fixation protrusions. They can project radially in a tooth-like manner from the pretensioning element and optionally from the pretensioning element to the sealing element, also for good rearward engagement with the axial element. Such a fixing projection can advantageously extend in the circumferential direction over the entire length of the pretensioning element, i.e. from the manufacturing point of view, i.e. it can be formed completely circular in the pretensioning part.

  According to a further advantageous variant of the invention, the fixing device in the region of the pretension axial section can be provided on one or more radial spring segments, so that the radial spring segments are sealed. A radial pretensioning force that presses against the element increases the positional safety of the sealing element and the pretensioning element relative to each other.

  Instead of or in addition to the above attachment of the pretensioning element to the carrier element, for this purpose the pretensioning element extends radially to attach the pretensioning element to a main structure such as a metering device. It is conceivable to have an existing mounting section. The main structure mentioned here may be identical to the carrier element. The radial attachment section can guarantee a very secure attachment to the main structure with very little axial expansion. For example, the mounting section can be formed as a radial flange, which advantageously extends over the entire circumference of the pretensioning element and is particularly preferably provided in a completely circular shape in the circumferential direction.

  A further significant drawback of the previously known rubber elastic pretensioning element is its temperature characteristics. The pretensioning element described here has a very wide temperature range, for example if the pretensioning element is formed from metal at least in the region of the radial spring segment, preferably also in the region of the spring carrier. It can be used in a functionally reliable manner at operating temperatures up to 200 ° C.

  The sealing element is preferably formed entirely from a flexible elastic material such as an elastomer or a thermoplastic, at least in the sealing section.

  According to an advantageous variant of the invention, which can be used in particular when the sealing surface of the sealing element is pressed against the working surface with a particularly large force or pressure, the radial sliding seal subassembly is And a clamping force generating element movable with respect to the pretensioning element. In this regard, the clamping force generating element is preferably in the first position (in this position the clamping force generating element cooperates with the pretensioning element so that the pretensioning element applies a smaller radial pretensioning force to the sealing element. And the second position (in this position, the clamping force generating element cooperates with the pretensioning element so that the pretensioning element applies a larger radial pretensioning force to the sealing element). At least moveable relative to the element. The pretension force in the first position may also be zero.

  In this regard, because of the built-in space-saving structure, the clamping force generating element can be formed in a simple manner as a ring surrounding the pretensioning element, at least in the region of its radial spring segment. For a good determination of the radial pretensioning force that can be generated by the clamping force generating element, the radial protrusion is preferably formed on the clamping force generating element formed as a ring, Projects from the clamping force generating element into the pretensioning element.

  For a particularly simple operation of the clamping force generating element, it is further possible to form at least part of the radial spring segment on its surface facing away from the sealing element, preferably all of which are inclined axially As a result of this, the axial displacement of the clamping force generating element formed as a ring varies in various ways, depending on the displacement path, into the sealing element when in contact with the axially inclined, radial spring segment face Apply a large radial pretension force.

  The present invention further comprises a cylinder and a piston rod, both of which extend along the axial direction and are movable relative to each other in this axial direction, and the radial sliding seal subassembly described above. For metering devices, in particular syringes, pipette piston-cylinder devices and the like. In this regard, according to a first possible embodiment, the working surface can be formed inside the cylinder facing the piston rod. In this case, the radial sliding seal subassembly can be used to seal the piston or piston rod against the cylinder so that the sealing element defines a metering cavity that can be changed by relative movement of the piston rod and cylinder. The metering cavity is in this case bounded by a section of the cylinder wall, the front of the cylinder with outlet / inlet openings and just the sealing element. At least the sealing element can contribute to the compartment of the metering cavity.

  For this purpose, it is conceivable to attach a pretensioning element in the region of the metering longitudinal end of the piston rod protruding into the cylinder to the rod for joint operation. In this case, as already mentioned at the outset, if a radial spring segment is provided and is arranged to protrude from the carrier section in a direction away from the metering cavity, the metering cavity has as large an effective volume as possible. Can be designed as

  In addition to or instead of the already mentioned possibility of locking the pretensioning element on the piston or on the piston rod of a metering device with a piston-cylinder device, a pretensioning element (especially the radial flange mentioned above is used) ) Can be riveted to the piston rod. In addition or alternatively, the section of the pretensioning element can be contracted to the piston rod or piston if it forms a circumferentially closed ring. Again, for optimum use of the installation space, it is advantageous that radial spring segments are provided and are arranged to protrude from the carrier section away from the metering cavity.

  Where further reduction in the number of elements required to form the metering device described herein is desired, the pretensioning element is formed at least partially, preferably completely, integrally with the section of the rod. Is also possible.

  Alternatively or additionally, in the metering device, the working surface can be formed on the outside of the piston rod facing the inner wall of the cylinder. For example, it is desirable if it is not the metering cavity to be sealed by the radial sliding seal subassembly, but instead is the exit point of the piston rod from the cylinder. In this case, the radial sliding seal subassembly according to the invention is arranged on the longitudinal end of the cylinder opposite the longitudinal end of the cylinder with the metering opening.

  Hereinafter, the present invention will be described using examples and with reference to the drawings.

1 is a longitudinal cross-sectional view of a first embodiment of a radial sliding seal subassembly according to the present invention, disposed on a longitudinal end of a piston rod not shown in cross section. FIG. FIG. 2 is a partial (non-cross-sectional) perspective view of the first embodiment of FIG. 1. FIG. 6 is a longitudinal cross-sectional view of a metering device with a second embodiment of a radial sliding seal subassembly according to the present invention. FIG. 4 is a longitudinal sectional view of a detail IV in FIG. 3. FIG. 6 is a perspective view of a second embodiment of a radial sliding seal subassembly provided on a piston rod. FIG. 6 is a longitudinal cross-sectional view of a metering device with a third embodiment of a radial sliding seal subassembly according to the present invention. FIG. 7 is a longitudinal cross-sectional view of a metering device with a fourth embodiment of a radial sliding seal subassembly according to the present invention. FIG. 7 is a longitudinal cross-sectional view of a metering device with a fifth embodiment of a radial sliding seal subassembly according to the present invention.

  In FIG. 1, a first embodiment of a radial sliding seal subassembly according to the present invention, shown in longitudinal section, is indicated generally by the reference numeral 10. This comprises a pot-shaped sealing element 12 surrounding the pretensioning element 14 from the outside.

  The sealing element 12 has a sealing section 16 in the region of its open longitudinal end 12a, which is on its radially outer surface a sealing surface that is perfectly circular in the circumferential direction and projects a predetermined amount in the axial direction. 18 and a pretensioning surface 20 is formed in the region of the sealing section 16 on the radially opposite surface, on which a plurality of radial spring segments each having a pretensioning axial section 24 22 is on it.

  The pretensioning element 14 has a spring carrier 26 in addition to the radial spring segment 22, but the radial spring segment 22 is integrally formed by its carrier section 27 which is axially adjacent to the radial spring segment. And protrudes in the direction of the longitudinal axis L of the piston rod 28. All radial spring segments 22 (adjacently arranged about the longitudinal axis L in the circumferential direction) protrude from the spring carrier 26 in the same direction.

  As can be more easily appreciated from FIG. 2, the pretensioning element 14 is crown-shaped and comprises a tubular section 30, where the radial spring segments 22 are separated from one another by slits 32, whose axis The length of the direction is shorter than that of the tubular section 30, so that the tubular section 30 can be formed from a tubular unfinished article by introducing a slit 32.

  The pretensioning element 14 further comprises a radially inwardly directed radial flange 34 which serves to attach the pretensioning element to the longitudinal end 28a of the piston rod 28, which Projects into the cylinder when assembled. For this purpose, a generally central opening 36 is provided in the radial flange 34, which can be used to rive the pretensioning element 14 to the longitudinal end 28 a of the piston rod 28.

  Further, a radial protrusion 38 indicated by a dotted line can be provided on the surface of the radial spring segment 22 facing radially away from the pretension surface 20, but this protrusion is formed as a stopper head. , Can function to lock the pretensioning element 14 on the longitudinal end 28a of the piston rod 28;

  In order to generate a pretensioning force acting radially outward in FIG. 1, radial spring segments 22 are provided elastically supported on a spring carrier 26, but with their free longitudinal ends in the radial direction. The part (see the double arrow R) is associated with the central longitudinal axis L of the piston rod 28.

  As already mentioned, in the assembled state, the longitudinal end 28a of the piston rod 28 (which is also formed for the above-mentioned possibility of locking the pretensioning element 14 thereon and continues in the axial direction. The shoulder section 28b (having a larger diameter) is securely inserted inside the metering device cylinder (not shown). The front surface 12b of the elastic sealing element 12 thereby defines the metering cavity of the metering device.

  In order to ensure the positional fixation of the metering element 12 on the pretensioning element 14, the projections 40 arranged in a completely circular manner in the circumferential direction are in this example in the region of the spring carrier 26 on the pretensioning element 14. Is provided. In the assembled state shown in FIG. 1, they penetrate the elastic material of the sealing element 12.

  This positional locking effect is also an alternative or in addition, in the region of the pretensioned axial section 16 on the surface of the radial spring segment 22, so that a further fixing element faces the sealing element 12 in the assembled state. It can be strengthened when it is provided.

  The embodiment of the radial sliding seal subassembly 10 shown in FIG. 1 is shown in perspective view in FIG. 2, with the sealing element 12 omitted.

  From this figure, the pre-tensioned axial section 24 of the radial spring segment 22 in the undeformed state of FIG. 2 extends beyond the outer diameter of the spring carrier 26 radially in the direction of pretensioning, ie in this example radial. It is clear that it protrudes outward.

  Moreover, when the sealing element 12 slides at least with its sealing section 16 on the pretension axial section of the pretensioning element 14, the radial spring segment 22 is bent radially inward against its material elasticity, The pretensioning surface 20 is then pressed radially outwardly by a spring force (pretensioning force) that can be adjusted accordingly, so that the sealing surface 18 of the sealing element 12 is radially outwards in the desired manner. Pretension is added to the.

  FIG. 3 shows a second embodiment of a radial sliding seal subassembly according to the invention as incorporated in a metering device.

  In the second embodiment of FIGS. 3 to 5, the same structural parts as in the first embodiment of FIGS. 1 and 2 are given the same reference numerals, but increased by 100 in each case. . The second embodiment will be described only with respect to differences from the first embodiment, but reference is made to the description in other respects.

  In FIG. 3, the metering device is generally indicated by reference numeral 141. The device comprises a cylinder 142 in which a piston rod 128 is accommodated so as to be movable relative to the cylinder along the longitudinal axis L of the piston rod. The longitudinal axis L of the piston rod is also the longitudinal axis of the cylinder 142 at the same time.

  The cylinder 142 is formed from a plurality of parts with a cylinder body 145 and a closure / integration subassembly 146, which is connected to the cylinder body 145 on the exit side of the piston rod 128 from the cylinder 142. In FIG. 4, it can be seen that the working surface 144 is formed by the outer surface of the piston rod 128, for which, therefore, of the sealing element 112 facing radially inward, ie facing the piston rod longitudinal axis L. A sealing surface 118 rests.

  Accordingly, the pretension surface 120 of the sealing element 112 of the second embodiment faces radially outward. The radial spring segment 122 exists with its pre-tension axial section 124 abutting against the pre-tension surface 120 of the sealing element 112 and presses the sealing section 116 of the sealing element 112 against the working surface 144.

  The pretension force applied by the radial sliding seal subassembly 110 of the second embodiment thus acts in the opposite radial direction compared to the first embodiment.

  Accordingly, the pretensioning element 114 comprises a mounting flange 134 facing radially outward. The same is also true for the sealing element 112, but its front face 112b is formed on a retaining flange 148 extending radially outwardly in a complete circle.

  The radial sliding seal subassembly of the second embodiment resists radial projections 150 that point axially, in this example in the direction of withdrawal of the piston rod 128 from the cylinder 142, radially inward of the enclosure and built-in subassembly 146. With the addition of the radial mounting flange 134, it can be very easily attached to the weighing device 141 in a sandwich-like manner. In the opposite axial direction, the retaining flange 148 (which consists of an elastic material, together with the remaining integral sealing element 112) rests on the mounting flange 134, so that the flange structure contacts the radial projection 150. It can be fixed and pretensioned by the axial end 145a of the cylinder body 145 in contact. Fixing can be easily accomplished, for example, by screwing the enclosure and isolation assembly 146 into the cylinder body, thereby allowing the sealing element 112 and pretension on the metering device 141 due to the flexible elasticity of the elastic sealing element material. Not only is the fixing of the element 114 realized, but also the locking on the cylinder body 145 and the fixing of the built-in subassembly 146 is also realized by the “action = reaction” principle.

  FIG. 5 is a partial cross-sectional perspective view of the second embodiment with the cylinder 142 omitted.

  FIG. 6 shows a metering device with a third embodiment of a radial sliding seal subassembly according to the invention. The same structural parts as in the second embodiment of FIGS. 4 and 5 are given the same reference numerals in FIG. Other references are clearly made to the description of FIGS.

  Since the third embodiment of FIG. 6 substantially corresponds to the second embodiment, only differences from the second embodiment already described will be described.

  The difference between the third and second embodiments of the radial sliding seal subassembly is that on the one hand the radial surface 252 of the radial spring segment 222 facing away from the sealing element 212 is the longitudinal axis of the piston rod 228. It is formed to be inclined with respect to the direction axis L. In the example shown in FIG. 6, the outer radial surface 252 is conical and the outer diameter of the assembly formed by the radial spring segments 222 increases toward the cylinder body 245.

  Furthermore, the pretensioning element 214 is surrounded radially outwardly by a clamp ring 254 in the region of the radial spring segment 222, and its longitudinal end 254 a deeper in the metering device 241 has a radial spring A radial projection 256 is formed that faces the outer radial surface 252 of the segment 222.

  The clamp ring 254 is movable in the direction of the longitudinal axis L of the piston rod 228 at least during installation of the metering device 241. When the clamp ring 254 is inserted into the metering device, ie, displaced toward the left side of FIG. 6, the radial protrusion 256 is in contact with the conical radial surface 252 of the radial spring segment 222, resulting in Upon further displacement of the clamp ring 254 into the metering device 241, the radial spring segment 222 is increasingly pressed against the piston rod 228 by the radial protrusion 256, thereby causing the radial spring segment 222. Increases the radial pretensioning force applied to the sealing element 212.

  The clamping ring 254, or generally the clamping force generating element, in this case, once the desired radial pretensioning force is obtained by the clamping force generating element, in order to ensure that the radial pretensioning force is constantly applied on the sealing element. Once fixed, it can be fixed in its original position with respect to the pretensioning element, for example by gluing or welding.

  FIG. 7 shows a longitudinal section through a fourth embodiment of a radial sliding seal subassembly according to the invention, similar to the first embodiment, arranged on a piston rod.

  The same structural parts as in FIG. 1 are given the same reference numerals but increased by 300.

  The fourth embodiment of FIG. 7 will be described only with respect to differences from the first embodiment of FIGS. 1 and 2, but the reference is made clear to this description.

  The pretensioning element 314 of FIG. 7 is completely identical to the pretensioning element of FIG. 1 except that the sealing element 312 can accommodate two pretensioning elements 314 in opposite axial orientations. . This structure of the pretension element 314 is also referred to as an X structure. Because, in the longitudinal section of FIG. 7, the radial spring segments 322 of the two pretensioning elements 314 are both spaced from the longitudinal axis L of the piston rod 328, starting from the attachment point 360 using the rivet 362. This is because they are arranged and aligned so as to extend in the axial direction.

  With the structure shown in FIG. 7, a sealing section of the sealing element 312 that is very long in the axial direction can be realized on the working surface not shown in FIG.

  In FIG. 8, the radial sliding seal subassembly on the piston rod is again shown in cross section. Again, the elements of this radial sliding seal subassembly of the fifth embodiment are very similar to those of the first and fourth embodiments. Accordingly, the same structural parts in the fourth embodiment are given the same reference numerals as in FIGS. 1, 2 and 7, but increased by 400 or 100 respectively. Other references are clearly made to the description of the first and fourth embodiments.

  Hereinafter, the fifth embodiment of FIG. 8 will be described only with respect to differences from the first and fourth embodiments already described.

  The fifth embodiment of FIG. 8 also shows a radial sliding seal subassembly with two pretensioning elements 414, which are different from the pretensioning elements 14 and 314 of the first and fourth embodiments, respectively. Are completely identical.

  In contrast to the fourth embodiment of FIG. 7, the pretensioning element 414 and the sealing element 412 connected thereto are not adjacent to each other in the front face, but the free longitudinal ends of their radial spring segments 422 are used. It is arranged with it. Starting from these free longitudinal ends of the radial spring segments 422 that are in close proximity to each other, both radial spring segments extend in each case axially to the longitudinal axis L of the piston rod 428. This is why the structure shown in FIG. 8 is also called an O structure. The rivet 462 is correspondingly longer formed and the sleeve 464 is a front surface (radial flange 434) of the pretensioning element 414 (which serves to secure the right pretensioning element 414 of FIG. 8 by the left side pretensioning element 414). And rivet head 462c. These sections of the rivet 462 that are simply surrounded by the radial flange 434 and in the case of the right sealing element 412 and also by the sealing material are not surrounded by the sleeve 464. These sections are identified in FIG. 8 by reference numerals 462a and 462b.

  Again, a very long sealing surface in the axial direction is realized by the fifth embodiment shown in FIG.

10 radial sliding seal subassembly 12 pot-shaped sealing element 12a open longitudinal end 14 pretensioning element 16 sealing section 18 sealing surface 20 pretensioning surface 22 radial spring segment 24 pretension axial section 26 spring carrier 27 carrier section 28 piston Rod 28a Longitudinal end 28b Shoulder section 30 Cylindrical section 32 Slit 34 Radial flange 36 Opening 38 Radial protrusion 40 Protrusion

Claims (30)

A radial gap between the wall of the cylinder (142) and the wall of the piston rod (28; 128; 228; 328; 428) movable with respect to the cylinder (142), comprising a piston-cylinder device A metering device comprising a radial sliding seal subassembly (10; 110; 210; 310; 410) for sealing the sealing element (12; 112; 212; 313; 412) and cooperating therewith. At least one pretensioning element (14; 114; 214; 314; 414) acting, said sealing element (12; 112; 212; 312; 412) extending axially and circumferentially An existing sealing section (16; 116; 216) on which the first Sealing surface radially facing (18; 118; 318; 418) is sealing, and working surface that extends in the axial direction and the circumferential direction; formed for sliding contact at least the axial direction between (144 244) and, and, on its pretensioning surface facing the second radius direction opposite the first radial direction (20; 120) is, the pre-tensioning for the transmission of the semi-radial pretension force Formed for engagement with the element (14; 114; 214; 314; 414);
The metering device comprises a plurality of identically formed pretensioning elements (14; 114; 214; 314; 414) arranged sequentially in the axial direction, each pretensioning element (14; 114; 214; 314; 414) a spring carrier (26; 126) and a plurality of separately formed radial spring segments (22; 122; 222; supported at least radially elastically on the spring carrier (26; 126). 322; 422).   The axially adjacent pretensioning elements (14; 114; 214; 314; 414) or groups of pretensioning elements (14; 114; 214; 314; 414) are oriented in the same direction The metering device according to claim 1.   The axially adjacent pretensioning elements (14; 114; 214; 314; 414) or groups of pretensioning elements (14; 114; 214; 314; 414) are provided facing in opposite directions The metering device according to claim 1.   At least one radial spring segment (22; 122; 222; 322; 422) is connected to the spring carrier (26; 126) in one region at its longitudinal end and Characterized in that it is formed using a pretensioned axial section (24; 124) spaced axially from the longitudinal end for contact with the tension surface (20; 120). The weighing device according to any one of claims 1 to 3.   The spring carrier (26; 126) comprises a circumferentially extending carrier section (27; 127; 227) from which at least one radial spring segment (22; 122; 222; 322; 422). 5) projecting in the axial direction.   6. Metering device according to claim 5, characterized in that the carrier section (27; 127; 227) extends completely circularly in the circumferential direction.   7. Metering device according to claim 5 or 6, characterized in that the plurality of radial spring segments (22; 122; 222; 322; 422) project axially.   8. A metering device according to claim 7, characterized in that all radial spring segments (22; 122; 222; 322; 422) protrude axially.   9. Metering device according to claim 7 or 8, characterized in that the radial spring segments (22; 122; 222; 322; 422) project in the same axial direction.   10. A weighing device according to any one of the preceding claims, characterized in that the radial spring segments (22; 122; 222; 322; 422) are arranged adjacent in the circumferential direction.   At least a portion of the radial spring segment (22; 122; 222; 322; 422) or all of the radial spring segment (22; 122; 222; 322; 422) is the carrier section (27; 127; 227). 11. The weighing device according to claim 5, wherein the weighing device is formed integrally with the weighing device.   12. Metering device according to claim 11, characterized in that the pretensioning element (14; 114; 214; 314; 414) is an integral element.   The pretensioning element (14; 114; 214; 314; 414) comprises a cylindrical section (30; 130) having a plurality of circumferentially adjacent axial slits (32; 132) in the axial direction. 13. A weighing device according to any one of the preceding claims, characterized in that the length of the weighing device is shorter than that of the tubular section (30; 130).   The axial slit (32; 132) starts from one longitudinal end of the tubular section (30; 130), and has another longitudinal end of the tubular section (30; 130). 14. The metering device according to claim 13, wherein the metering device extends into a section.   5. The pretensioned axial section (24; 124) in an unloaded state projects relative to the carrier section (27; 127; 227) in the radial pretensioning direction. 14. A metering device according to any one of claims 4 to 13, which cites and claim 5.   At least a portion of the radial spring segment (22; 122; 222; 322; 422) has a radial snap-lock protrusion on its surface that faces away from the pretensioning surface (20; 120) when assembled. The weighing device according to any one of claims 1 to 15, further comprising (38).   The pretensioning element (14; 114; 214; 314; 414) is at least axially of the sealing element (12; 112; 212; 312; 412) and the pretensioning element (14; 114; 214; 314; 414). 17. A weighing device according to any one of the preceding claims, characterized in that it comprises a fixing device (40) for fixing the relative position in.   18. A metering device according to claim 17, characterized in that the fixing device (40) is in the form of a fixing protrusion (40).   The pre-tensioning element (14; 114; 214; 314; 414) is radial for attaching the pre-tensioning element (14; 114; 214; 314; 414) to the main structure (141; 241). 19. A metering device according to any one of the preceding claims, characterized in that it comprises a mounting section (34; 134; 434) extending in the direction.   20. Metering device according to claim 19, characterized in that the mounting section (34; 134; 434) is formed as a radial flange (34; 134; 434).   2. The pretensioning element (14; 114; 214; 314; 414) is made of metal at least in the region of the radial spring segment (22; 122; 222; 322; 422). The weighing device according to any one of claims 20 to 20.   22. The metering device according to claim 21, wherein the pretensioning element (14; 114; 214; 314; 414) is also made of metal in the region of the spring carrier (26; 126).   A clamping force generating element (254) movable relative to said pretensioning element (14; 114; 214; 314; 414), which comprises said pretensioning element (14; 114; 214; 314; A first position in which the clamping force generating element cooperates with the pretensioning element (14; 114; 214; 314; 414) such that 414) applies a smaller radial pretensioning force to the sealing element; The clamping force generating element is applied to the pretensioning element (14; 114; 214; 314) so that the pretensioning element (14; 114; 214; 314; 414) applies a greater radial pretensioning force to the sealing element. 414) and a second position cooperating with said pretensioning element (14); 114; 214; 314; 414), characterized in that at least moveable relative to claims 1 to metering device according to any one of claims 22. 24. A cylinder (142) and a piston rod (28; 128; 228; 328; 428) according to any one of claims 1 to 23, both extending along the axial direction, and A weighing device (141; 241) movable relative to each other in the direction,
Metering device (141; 241) characterized in that the working surface is formed on the inside of the cylinder (142) facing the piston rod (28; 128; 228; 328; 428).   25. A metering device according to claim 24, which is a syringe or pipette piston-cylinder instrument.   Projecting into the cylinder, the pretensioning element (14; 314; 414) in the region of the metering longitudinal end (28a; 328a) of the piston rod (28; 328; 428) 26. A metering device according to claim 24 or claim 25, wherein the metering device is fixed relative to.   The pretensioning element (14; 114; 214; 314; 414) is riveted and / or shrink-fitted to the piston rod (28; 128; 228; 328; 428). 26. A weighing device according to claim 24 or claim 25.   The pretensioning element (14; 114; 214; 314; 414) is at least partially formed integrally with a section of the piston rod (28; 128; 228; 328; 428). 26. A metering device according to claim 24 or claim 25.   29. The pretensioning element (14; 114; 214; 314; 414) as a whole is integrally formed with the section of the piston rod (28; 128; 228; 328; 428). A weighing device as described in.   25. Preamble part according to claim 24, characterized in that the working surface (144; 244) is formed on the outside of the piston rod (28; 128; 228; 328; 428) facing the inner wall of the cylinder. Or a metering device according to claim 24 or claim 25.

Images