Inflatable sealing

Abstract

To provide a module type sealing capable of quickly and easily removing and installing the sealing at a relatively accurate position to a load introducing member.SOLUTION: The invention relates to a modular seal for a balance, the load-introducing element of which transmits the weight force in the height direction Z, wherein the seal comprises a closure module with a sealing element, which forms a chamber that can be acted upon by pressure, and an end support with a sealing surface, wherein the chamber can be acted upon by a medium in such a way that the sealing section bears against the sealing surface in the height direction Z.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a sealing for a balance, weighing cell or force sensor, hereinafter referred to for short as a "balance". Such scales typically include a protective housing through which a load introduction member (also called a load introduction bolt) passes in a contactless manner and into the housing, transmitting the load to be weighed. In the case of scales with an underfloor load output, the load-introducing member is loaded in tension with the force to be measured and protrudes through the underside of the housing.

[0002] In order to avoid erroneous weighing, contact between the load-introducing member and the housing (force shunting) must be avoided during operation. At the same time, particularly in the production of food and pharmaceutical products, it is often necessary to clean the scales during periods of inactivity, which can be done with hot or aggressive liquids or by means of steam injectors. In such a case, it is important to reliably close the gap between the load-introducing member and the housing with a seal in order to protect the interior of the housing from the intrusion of the cleaning agent.

[0003] Furthermore, it is desirable to lock the load-introducing member during periods of rest to avoid unintended or excessively high loads on the delicate weighing cell inside the housing. Furthermore, removal and installation of the sealing for maintenance or repair purposes and during production should be possible when necessary (even for the operator himself) quickly, easily and in the correct position relative to the load-introducing member.

[0004] Additionally, even during normal operation, it is desirable to avoid the ingress of dirt through gaps and the accumulation of dirt in the area of ​​the housing openings. [Background technology]

[0005] From EP 1 146 322 B1 a balance is known with an expandable seal in which an expandable bellows attached to the housing extends radially, and therefore transversely to the load-introducing direction, towards a movable part connected to the load-introducing element, thereby closing the gap located between them. In this case, the locking of the load introducing member is not sufficiently stable, and maintenance is troublesome. Furthermore, this type of sealing is not suitable for scales with underfloor load outputs. This is because the upwardly opening labyrinth sealing collects dirt which cannot be removed without incurring high costs. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] European Patent No. 1146322B1 Summary of the Invention [Means for solving the problem]

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to eliminate the above-mentioned drawbacks of scales with underfloor load outputs. This problem is solved by a modular sealing according to claim 1, a balance according to claim 11, a method according to claim 13 and a sealing element according to claim 15.

[0008] The invention is based on the finding that a particularly effective seal can be achieved by extending the sealing element parallel to the longitudinal extension of the load-introducing element and in the direction of load introduction, while at the same time locking the load-introducing element. The seal then introduces forces in two mutually perpendicular directions into the end support linked to the load-introducing element, which end support thereby ensures a particularly secure seal and stable locking.

[0009] The modular sealing according to the invention is provided for balances in which the load-introducing members project downwards from the housing of the balance along a vertical height direction Z. At this time, the sealing is aligned along the long axis Z extending in the height direction Z. A The closure module preferably has a rotational symmetry and extends about a center. This closure module is then intended to be fixed to the balance housing as the first main component of the sealing in the area where the load-introducing member is inserted into said housing. The closure module has a central holder opening through which the load-introducing member of the balance can project or projects when assembled with the balance.

[0010] The retainer and the fluid expandable and extensible seal member housed in the retainer are parts of the closure module. The seal member has a major axis Z A Preferably, the suction tube is configured as an expandable bead or tube surrounding the suction tube. By varying the internal pressure, the seal member can be selectively transitioned from a resting state to a sealing state and vice versa by expanding (sealing state) or contracting (resting state). Preferably, compressed air is applied to the sealing member, but more preferably, it is compressible, although any other fluid is also contemplated.

[0011] As a second major component of the sealing, the sealing further includes an end support cooperating with the sealing member that is provided for attachment to the load-introducing member. According to the invention, the sealing section of the sealing member is configured to abut against the sealing surface of the end support when in the sealing state, thereby sealing any gap that exists between the sealing surface and the sealing member when in the rest state. For this purpose, the end support, and with it the load-introducing member, is biased, preferably in a completely circular manner, by the sealing member in the sealed state. This biasing serves, on the one hand, to ensure that any gaps present when in the rest state are sealed, protecting the balance housing against the ingress of dirt, dust, moisture, liquids or other undesirable substances. On the other hand, the load-introducing member is subjected by the sealing member to a stabilizing force for protection against unintentional impact forces.

[0012] In an embodiment of the present invention, the sealing is designed to hermetically seal the gap between the seal member and the end support. In this case, for example, if an explosive gas is found in a factory, the sealing can be operated as necessary to prevent the intrusion of flammable gas into the scale housing. Of course, the opposite can also be true, providing protection around the balance housing against unwanted leakage of gas from the balance housing.

[0013] In order to introduce particularly effective force into the end support, according to the invention, the sealing surface is arranged below the sealing element in the height direction Z so that, as the sealing element stretches in the height direction Z when transitioning from the rest state to the sealing state, it abuts with a section against the sealing surface located below it and exerts a sealing-assisting force on the end support. In this case, unlike the prior art, according to the present invention the load-introducing member is intentionally biased in the direction of load introduction, i.e. in the direction in which the load to be measured is further transmitted along the load-introducing member to the measuring cell inside the scale housing.

[0014] In this case, the invention intentionally sacrifices the load of the load-introducing element in exchange for a particularly effective seal and, at the same time, preferably a secure and risk-free locking of the load-introducing element for the measuring cell. At the same time, the end support is urged by the sealing member with a pressure force so as to rotate in the radial direction as well, thereby ensuring reliable centering and stable positioning during sealing.

[0015] In a preferred embodiment of the present invention, the holder has a coupling means by which it can be coupled directly or indirectly to the scale housing, and it is intended that the coupling means be configured to center the holder opening relative to the load-introducing member protruding from the scale housing. To this end, the holder has suitable centering means which can cooperate with the balance housing. This may be, for example, one or more centering pins, or a centering collar (preferably configured concentrically around the holder opening) that cooperates with a complementary configured section of the scale housing. The purpose of centering is to accurately align the holder opening or holder relative to the balance housing or to the load-introducing element projecting downward from the balance housing. Accurate centering is important to ensure that the bias of the seal members against the end supports is as uniform as possible in the circumferential direction when in a sealed state. Furthermore, the centering means facilitates easy installation of the seal during manufacturing as well as replacement and reinstallation without the need for measurements / adjustments therefor.

[0016] In a particularly preferred embodiment, the coupling means comprises a thread configured centrally relative to the holder opening for screwing with a corresponding thread on the balance housing. The screw thread or the corresponding screw thread then goes around the load-introducing element or the extension linked to it and at the same time serves to center the holder and the balance housing or the load-introducing element relative to one another. Preferably, the retaining portion includes external threads that are threadable into matching internal threads on the scale housing, or vice versa. The screw thread allows the holding part to be screwed in particularly easily (without adjustment) as part of the sealing according to the invention, with a precise fit relative to the balance housing or the load-introducing element, and allows for centering, i.e. time-saving assembly and disassembly.

[0017] The holding portion in this embodiment includes a bottom surface on the top surface facing away from the end support. When the sealing is in the assembled state, the top surface of the base faces towards the balance housing, whereas the seal member is located on the bottom surface of the base facing away from the balance housing. At this time, at least one supply passage, particularly a hole, leads from the inside of the seal member to the communication portion on the upper surface of the bottom surface. The supply passage then serves to preferably supply or apply fluid to the seal member through the bottom surface. In this case, the communication portion of the supply passage on the upper surface of the bottom surface is located between two sealing means that preferably concentrically surround the holding portion opening, and these sealing means are preferably seated in grooves provided for this purpose.

[0018] In particular, the sealing means may be an O-ring that can be inserted into a groove. When the retaining portion is coupled to the scale housing (particularly via the screw fastening described above), the bottom surface is pressed against the scale housing, thereby slightly compressing the sealing means or the O-ring located in the groove. The sealing means thereby seals the area of ​​the communication radially outwards and inwards, so that fluid cannot escape in these directions.

[0019] More than two grooves, preferably extending concentrically with one another and provided with suitable sealing means for this purpose, may also be advantageous, for example in order to achieve a particularly good seal in the radial direction.

[0020] The sealing means preferably delimit an annular passage located radially therebetween and in communication with at least one supply passage. In this case, the fluid for the sealing member can propagate along the annular passage when it is supplied into the annular passage and can flow through at least one, preferably multiple, supply passages through the bottom surface and into the sealing member.

[0021] More than one such annular passage may be advantageous to ensure a supply of fluid to the seal member. The annular passages preferably extend concentrically with one another and are fluidically connected to one another radially and / or by housing passages leading into each from the balance housing.

[0022] Furthermore, it is conceivable to provide the annular passageway at the same time as a receiving section for the sealing element, so that the groove for receiving the sealing means forms part of the annular passageway. For example, a groove (preferably flat and / or rectangular in cross section) circumferential about the longitudinal axis having inner and outer (preferably cylindrical) wall surfaces is also conceivable, which groove forms an annular passage and at the same time is suitable for accommodating, for example, a circumferential sealing means (in particular an O-ring) abutting the inner and outer wall surfaces. In that case, there is no need to provide a separate groove for the sealing means. Furthermore, it is conceivable that such an annular passage be configured in the region of the inner and outer wall surfaces in a groove-like step to accommodate the sealing means, or be configured to be radially deeper than the area located between them, which in that case forms the actual annular passage. This allows the sealing means inserted into the deeper step to be better fixed in the radial direction.

[0023] It is also conceivable to insert into the aforementioned (preferably flat and / or rectangular in cross section) groove a sealing means, for example an annular flat sealing, which fills the groove substantially completely, and which flat sealing is arranged along the longitudinal axis Z.A The inner wall of the ... The annular notch penetrates the flat ceiling completely in the height direction Z, thereby dividing it into two parts. Alternatively, the annular notch may be configured as a groove in the interior of the flat sealing, not passing all the way through it. In both cases, from the annular channel thus formed, one or more supply channels are led in the height direction Z to the sealing element as well.

[0024] Preferably, fluid is supplied to the annular passage directly through the wall of the balance housing. To this end, in this embodiment, the fluid for sealing can be provided via a housing passage formed in the balance housing, which has a compressed air connection inside the balance housing that can be closed if required. The compressed air can be guided through the housing passage to the underside of the balance housing, where it can be communicated from the balance housing in the region of the annular passage. In this case, it has the particular advantage that the holding part is screwed onto the balance housing, and this is the only way that the sealing element is connected to the fluid, in particular to compressed air. This makes it possible for the modular sealing according to the invention to be assembled in a particularly simple and rapid manner. The housing passage or compressed air connection can be opened or closed through appropriate controls to apply compressed air to the seal member, causing it to expand, relax, or even actively contract.

[0025] Instead of providing fluid via a housing passage in the balance housing, the holding portion or annular passage may have suitable connections for separate fluid lines provided and connected separately from the balance housing.

[0026] In this embodiment, the annular passage is formed in the bottom surface of the holding part together with sealing means or grooves that radially separate it on both sides, and the annular passage and groove are cut into the upper surface of the bottom surface facing away from the end support or facing the scale housing and are configured to open upward. When the retaining portion is connected to the underside of the balance housing, in particular when screwed, the balance housing closes the annular passage with its underside at its upper side and at the same time also seals it radially through contact with the sealing means in the groove. Thus, if the annular passage and groove are configured over the entire bottom surface of the holder, the balance housing may be configured without a separate groove or annular passage at that point, but instead be substantially flat.

[0027] Alternatively, it is conceivable to configure the groove and annular passage entirely on the underside of the scale housing facing the bottom surface, whereas the upper surface of the bottom surface of the holding part may be configured as a substantially flat surface. In this case too, when the holding part is screwed with its bottom surface to the balance housing, the annular passage is covered vertically and sealed radially via the sealing means in the groove.

[0028] It is further conceivable that the groove is configured in the bottom surface and the annular passage is configured in the balance housing, or vice versa, or even that the groove and / or the annular passage are configured partly in the bottom surface and partly in the balance housing. In both cases, it is crucial that the annular passage is completely closed or sealed by the connection between the holder and the balance housing.

[0029] Finally, a further alternative is to provide a flange-like intermediate piece between the holder and the balance housing, in which the above-mentioned groove and / or annular passage are partially or completely formed. By assembling the intermediate part between the upper surface of the holder and the lower surface of the balance housing, the annular passage formed in the intermediate part is closed in a ready-for-operation manner. The intermediate part may have centering means (in particular a centering collar or a centering pin) which cooperate with complementary centering means arranged on the holding part and / or on the balance housing. For example, a connecting tube provided on the holder can serve to center the intermediate part and at the same time can be provided with a thread for screwing into a corresponding thread on the balance housing.

[0030] As explained above, even when using the intermediate piece described above, a separate groove is not necessarily required due to the configuration of the annular passage in the bottom surface of the holder or in the housing of the balance.

[0031] In another embodiment of the present invention, the sealing surface is A It is intended that the structure be configured (preferably rotationally symmetric) around the center. At the same time, the seal surface is A The seal member has at least one contact area extending obliquely relative to the surface of the seal member, against which the seal member abuts when in a sealed state. Such an obliquely shaped contact area has several advantages according to the invention compared to, for example, a horizontally extending sealing surface.

[0032] On the one hand, dirt that would make the necessary sealing difficult is less likely to remain on the sealing surface but rather slides down the slope, allowing the sealing element to abut cleanly against the sealing surface without any interfering dirt.

[0033] On the other hand, when a fluid is applied to the sealing member, causing it to stretch downward in the Z direction, it generates a crimping force on the oblique sealing surface which can be divided into a Z-direction component and a radial lateral component extending perpendicular thereto. The lateral biasing allows the end support to be centered on any side relative to the surrounding sealing element and to be fixed exactly in its lateral position (forces acting in opposite directions radially from two opposite sides on the end support or its sealing surface are thereby cancelled out).

[0034] A force acting on the end support in the Z direction may result in the end support (and the load-applying member supporting the end support) moving to a certain extent in the Z direction. Taking advantage of this effect, in another embodiment of the present invention, a stopper that acts in the opposite direction to the Z direction is provided to design-wise limit the movement of the load introducing member in the Z direction. This offers the particular advantage that in the sealed state the load-carrying element is pressed against this stop by the expanding sealing element, possibly against a spring force, and is held there. The stopper acts so that any gradually increasing biasing force or any shock to the load-introducing member that is unintentionally generated during cleaning is absorbed by the stopper rather than being transmitted to the delicate measuring cell in the balance housing.

[0035] The contact area increases along the major axis Z as the Z-distance from the closure module increases. A Preferably, the distance between the first and second electrodes is increased obliquely. In that case, the contact area has, at least in area, the shape of a cone or a pyramid. Alternatively, the contact area may have a notched or other surface that in either case expands radially with increasing distance from the closure module. Such a shape ensures that any dirt that may have accumulated on the contact area slides off over the oblique contact area. In that case, the dirt will slide off the side of the end support and will not be able to interact with the sealing.

[0036] Alternatively, it is conceivable to configure the contact area in a substantially funnel-like shape, whereby the contact area tapers towards the longitudinal axis with increasing distance from the closure module. In that case, the dirt will slide down in the Z direction and simultaneously radially inwards over the contact area. The lower end of the contact area could be provided with an opening for draining dirt.

[0037] In another embodiment of the invention, the retaining part is intended to have at least one support area for supporting the sealing member in the radial direction or for blocking unwanted strong stretching in this direction. This is because the seal member and the long axis Z A and as an inner support area that blocks the sealing member against unintended radially inward extension or further undesired contact with the load-introducing member. A The wall may be preferably cylindrical and arranged concentrically with respect to the base. Additionally, the inner support section prevents or reduces creasing of the seal member radially inwardly upon inflation. This is because, without this, the material of the seal member expanding radially inward would be compressed and could form folds.

[0038] Additionally or alternatively, an outer support area may be provided on the radially outer surface of the seal member facing away from the longitudinal axis. The support section supports or blocks the seal member against unintentional radially outward stretching. The outer support zone is also A Preferably, the wall is configured as a cylindrical wall extending concentrically with respect to the base.

[0039] These respective support areas also serve to facilitate and guide the expansion of the sealing element primarily in the Z direction, whereas radial expansion transverse thereto should be prevented as much as possible. Both support sections can jointly, for example as concentric cylindrical sections, form a groove between them circumferentially about the longitudinal axis, which groove accommodates the sealing member and is bounded upwards in the Z direction by the bottom surface of the holding section. In this case, the outer support section is configured to be longer in the Z direction than the inner support section. This has the advantage that both support areas are adapted to the contact surfaces of the end supports which slope downward obliquely outwards. Therefore, to prevent the expanding seal member from deflecting or deforming radially outward after contacting the oblique seal surface, the outer support area can extend lower in the Z direction than the inner support area, as shown in FIG. 2.

[0040] The holder is preferably open at its underside facing away from the bottom surface, which prevents dirt from accumulating within the holder.

[0041] The seal member has a longitudinal axis Z A Preferably, the core has a shape-stable core which surrounds the core, preferably in an annular shape. In particular, the core serves to provide a dimensionally stable support for the sealing element therein. Furthermore, the core is preferably connectable, in particular screwable, to the holding part (core screwing part), thereby fixing the sealing member to the holding part. The core is preferably made from aluminum. Other materials are also conceivable, and the production of the seal according to the invention or its individual components or composites thereof can take place, for example, by turning, milling, injection molding or 3D printing (additive manufacturing).

[0042] It is also preferred that the core provides at least one fluid connection leading from the interior of the sealing member to the above-mentioned supply passage arranged in the holding part. The ends of the supply passages preferably communicate radially between the maximum outer dimension and the minimum inner dimension of the annular core, most preferably on a partial circle having a radius r exactly at the center between them (central position).

[0043] In this embodiment, it is further contemplated that the lower surface of the core facing the end support is configured in a corrugated shape when viewed in vertical cross section. The wave shape is then selected so that the holes leading through the core into the sealing member, which serve for attachment of the core to the retaining portion by the core screw fastening portion or serve as supply passages, communicate at the troughs of the waves. This avoids contact or further damage between the material of the sealing element, which is stress-relieved when at rest, and possibly sharp bore connections of the bores or passages. The crests of the seal member, which are preferably chamfered and adjacent to the troughs of the waves, support the seal member on either side of the passage or hole and keep it clear thereof.

[0044] The wave trough is preferably at the central location, where the supply passage or mounting hole communicates. Due to the chamfered crests of the core, the core does not have any sharp edges or protrusions that could endanger the sealing element, especially in the unpressurized state.

[0045] In order to be able to influence the deformation of the sealing member in a precise manner, in this embodiment the sealing member has special properties. Accordingly, the integrally constructed sealing member comprises a head region facing the end support and including a sealing area, and wall regions radially inwardly and outwardly adjoining the head region. The wall region extends primarily in the Z direction, whereas the head region is configured substantially transverse thereto. The wall thickness of the sealing member is then greater in the head region than in the at least one wall region. In this case, such a relatively thin wall region can be stretched in the Z direction less stably or more easily in response to tensile forces in the height direction than would be the case for a relatively thick and therefore more stable head region. This is especially true when the seal member is made from a uniform material. This results in that when fluid is applied to the sealing member, in accordance with the present invention, primarily at least one relatively thin wall region is stretched in the Z direction towards the end support while further reducing its wall thickness, i.e. the head region moves or displaces in a substantially linear Z direction towards the end support. This is achieved if both wall regions on either side of the head region are constructed according to this principle. In this case, the seal member expands downward in a direction parallel to the Z direction. The optional support areas described above simultaneously prevent radial expansion of the sealing member.

[0046] The scale according to the present invention includes the sealing described above and a load introducing member that extends contactlessly through the holder opening and is coupled to the end support. In this case, the sealing area prevents foreign matter from entering the balance housing by biasing the sealing surface when in the sealed state. The stops that are preferably provided, against which the end supports or load-introducing members are movable, protect the measuring cell arranged in the balance housing from unintentional or shock-induced high loads. The balance may in particular operate according to the principle of electromagnetic force compensation. Other measurement principles are also conceivable, for example strain gauges or vibrating strings.

[0047] The seal member is made resiliently so as to expand or stretch under pressure until it seals. In contrast, in the relaxed state, the seal preferably shrinks at least to the extent that it no longer contacts the end support, most preferably creating a gap having a settable minimum width.

[0048] In order to ensure that the end supports are free to move or are no longer contacted by the sealing member when in the rest state, in another embodiment of the invention it is contemplated that a negative pressure relative to ambient pressure can be applied to the interior of the sealing member. The contraction of the sealing member for the transition to the rest state can thus be actively actuated. This is because the fluid injected into the seal member is properly sucked out therefrom. As a result, a tensile force directed away from the sealing surface is generated in the sealing area in contact with the sealing surface, and the area of ​​the sealing element that may be attached to the end support can thereby be precisely lifted or separated from it, avoiding a shunt of forces. The risk of damage to the sealing element is non-existent if the core is configured corrugated and without sharp edges.

[0049] Furthermore, monitoring the pressure generated in the seal member can be used to recognize a faulty sealing or its adhesion to the end support.

[0050] The modular sealing according to the invention is a compact, space-saving module. The modules are supplied as fully assembled mounting sets for each path of the scale and are assembled into the scale housing ready for use within seconds. No special adjustments or external inspections are required and there are no loose individual parts. This module includes a thread for centering and screwing into the balance housing, preferably already ready for installation, for quick installation in the exact position of the holder, two O-rings for sealing the annular passage in the balance housing, and a sealing member in which the core is located. Furthermore, the outer surface of the holding part is preferably provided with a wrench surface so that a common tool (open-end wrench, box wrench) can be screwed into the balance housing and tightened, preferably with a precisely defined torque.

[0051] The sealing according to the present invention is intended for scales having an underfloor load output, where the load introducing member typically extends vertically downwardly out of the scale housing. In principle, however, it is also suitable, in one alternative, for this sealing to be used for balances in which the load-introducing members project laterally from the balance housing in horizontal direction. In this case, the load to be detected by the balance is preferably also introduced horizontally or along the longitudinal extension of the load-introducing element into the balance housing. In this regard, one need only imagine rotating the embodiment shown in each drawing by 90 degrees to the side.

[0052] The sealing according to the invention is also particularly suitable for multi-track balances which are positioned closely next to each other. The advantage is that the sealing elements each extend vertically, so that only a small amount of extension space is required transversely, i.e. in the direction of the adjacent balance. The assembly of the seal can be carried out using a simple tool, such as a box wrench, that can be connected to the holding part in the height direction Z, so that lateral space next to the scale housing does not have to be used for the tool or for its operation. The holding part can have a suitable spanner surface for this purpose.

[0053] The sealing member (within which the core is located) can be the subject of a partial application, independent of the scale or end support. All features of the sealing member and the core described in the present application (including the description of the drawings and claim 15) are applicable here, either alone or in any combination. These requirements include, among others:

[0054] The sealing element is rotationally symmetrical. The sealing member is an expandable bead. The sealing member has a head region and at least one, preferably two, wall regions with a reduced wall thickness relative to the head region. The core is configured to secure the sealing member to the retainer. The core engages with at least one mounting area on the inner surface of the sealing element with a projection that is complementary in shape to said mounting area in order to fix the sealing element. The sealing element has, on its preferably flat outer surface facing away from the core, at least one recess in the height direction Z that faces a projection of the core in the height direction Z. When the retaining portion and the core are attached, particularly when screwed together, the projection is pressed against the area of ​​the inner surface of the sealing member that has a recess on the outside. This causes the recess to be expanded and flattened, preferably until the recess disappears and a flat abutment surface is formed on the retaining portion. This results in a more widely distributed clamping force in the radial direction. the core has a corrugated surface at least in areas to avoid contact with the inner surface of the sealing member at sharp edges; The core has at least one hole leading from the interior of the sealing element, by means of which the sealing element can be supplied with a fluid or attached to a retainer.

[0055] Next, the present embodiment will be described in detail with reference to the accompanying drawings. The drawings show: [Brief explanation of the drawings]

[0056] [Figure 1] A scale with two underfloor load outputs and two ceilings according to the invention. [Figure 2] 1 is a simplified cross-sectional view showing a modular sealing according to the present invention; [Figure 3] FIG. 10 is a simplified detail view showing the retainer with a seal member inserted therein. [Figure 4]FIG. DETAILED DESCRIPTION OF THE INVENTION

[0057] FIG. 1 shows in perspective view the housing C of a multi-track (two-track) scale W having two sensors, not shown in detail, arranged inside the housing C for detecting the force of the weight. The scale is provided with an underfloor load output, whereby for each sensor, a unique load introduction member is connected to the underside of the scale and to a unique housing opening O in the housing C. G and is loaded on the outside of the housing by the force to be measured. For each load-introducing member (also called a load receptor, load-introducing bolt, or load bolt), an associated longitudinal axis Z extends in the height direction Z. A A modular sealing M according to the invention is provided, which extends substantially rotationally symmetrically about the center.

[0058] FIG. 2 shows in cross section a detail of a modular sealing M according to the invention, which is coupled to the lower horizontal section of the housing C of a balance. Housing opening O on the underside of housing C G The load introducing member L protrudes downward from the housing in the height direction Z through the housing. The force to be measured can be introduced as a tensile force in the height direction Z to the load introducing member L via a member not shown in detail, and from there it can be transmitted upward into the interior of the scale housing C to the force sensor. The load introducing member L in this embodiment includes at least two members that can be screwed together in the height direction Z.

[0059] The closure module V is part of the modular sealing system and has a longitudinal axis Z. A The balance housing C includes a holding portion H having a flange-shaped bottom surface B facing the balance housing C and configured rotationally symmetrically about the center. As shown in FIG. 4, a connecting pipe protruding upward from the center of the bottom surface B is provided with a screw thread N1 (male screw). The connecting tube is screwed into a matching thread (internal thread) on the bottom of the housing C. By screwing in this way, the holding portion H is G and is automatically centered with respect to the load-introducing member L. In order to enable the holding part H to be screwed particularly easily and with a predetermined torque into the balance housing C, its outer circumference is provided with a spanner surface S for engagement with a suitable tool, in particular an open-end or box spanner. F is provided. In this regard, see Figure 4.

[0060] The bottom surface B facing away from the scale housing C is attached to the long axis Z. A Two cylindrical support areas H extending concentrically in the height direction Z i ,H A These form grooves between each other in the radial direction, circumferentially around the long axis. A fluid-applied, annular, bead-shaped, elastic seal member D is disposed in the groove. Inner support area H i divides the holding portion H radially inward and serves to prevent the sealing member D from expanding in the direction toward the load introducing member L in particular. an outer support area H protruding downwards from the sealing element D in the height direction Z; a delimits the holding portion H radially outward, preventing stretching of the sealing member D in this direction. Furthermore, both of these support areas serve to support and guide the sealing element D in the height direction Z.

[0061] Below the holding part H, the long axis Z A An end support G extends which is configured rotationally symmetrically about the center and is attached to the lower free end of the load-introducing member L via a screw connection which is not shown in detail. The end support has a tapered sealing surface F facing the retainer. G It has the following characteristics. As the distance in the Z direction from the holding part H increases, the end support G or the sealing surface F G The radius of increases.

[0062] In the rest state shown in Figure 2, the seal member D and the seal surface F G There is a gap S between them. In this state, the load introducing member L can move in the height direction Z together with the end support G relative to the holding portion H without any shunting of force, and the load can be transmitted to the inside of the scale housing C without any hindrance. For maintenance or repair purposes, the gap S can be closed to seal and protect the interior of the scale housing. This means that, according to the present invention, a fluid is applied to the sealing element L inserted in the holding part H, and thereby the sealing surface F is formed with the sealing area A in the height direction Z or in the direction towards the end support G. G This is done by stretching the clamping member until it abuts against the clamping member or until it is biased with a pressure force F. The modular seal then seals the housing opening O. G is sealed from the surroundings due to the closed gap S. At this time, it is preferable that the end support G is displaced downward to the extent that the expanded flange of the load introduction member L abuts against a stopper R provided on the inner surface of the scale housing C, thereby fixing it in the vertical direction.

[0063] When the fluid pressure inside the sealing element L is reduced again, the sealing area A of the sealing element L moves in the opposite height direction Z to the sealing surface F G , and then pulled back upwards again, whereby the gap S is re-established and the end support together with its load-carrying member L is thereby released for normal use.

[0064] The supply of fluid (in the simplest case compressed air) to the sealing element will now be described with particular reference to FIG. Here, in an enlarged cross-sectional view, the line of sight of Figure 2 is the long axis Z. A 1. A portion of the retaining portion H on the right side of FIG. Inner support member H i and the outer support member H a , and the elastic sealing member D can be seen enclosed between the longitudinal axis Z A The bead extends as an annular bead centered at the center, and has a spherical crown-shaped cross section on the underside facing away from the bottom surface B. In this region, the sealing element D includes a head region P1 which merges radially inwardly and radially outwardly into a wall region P2 in an integrated manner. In the head region P1, the sealing member D has a greater wall thickness than in both wall regions P2. Due to the relatively small wall thickness, the wall region P2 is more easily extensible in the Z direction than the head region P1. Therefore, when the sealing member D is pressed, the wall region P2 extends downward in the height direction Z, and in addition, the support region H i and H a Guided by. The head region P1 with its sealing area A is thereby moved substantially linearly downwards in the height direction Z towards the end support G.

[0065] Inside the sealing element D, as can be seen in Figures 2, 3 and 4, an annular core E is arranged, which serves, among other things, to stabilize the sealing element D and to attach it at its upper end to the bottom surface B. The core E is provided with a plurality of vertical holes in the circumferential direction on a partial circle having a radius r. Some of these holes are provided with threads for screwing the core E with the holding part H (core screwing part N2).

[0066] In addition, a plurality of through holes are provided in the height direction Z on the aforementioned partial circle, which extend from the inside of the sealing member D through the bottom surfaces of the core E and the retaining portion H toward the underside of the scale housing C, as can be seen particularly in the left-hand portions of Figures 3 and 4. These holes each form a supply passage U through which a fluid can be supplied and applied to the interior of the seal member D. On the upper surface of the bottom surface B, the supply passage U is connected to the communication part T along the long axis Z. A It communicates with an annular passage K which is concentrically formed with respect to the center. In the example of FIGS. 3 and 4, the annular passage K is provided on the bottom surface of the holding portion H. FIG. 2 shows an alternative arrangement of an annular passage K on the underside of the scale housing C.

[0067] Compressed air can be supplied to the annular passage K via a housing passage Q configured in the balance housing C, from where it passes through the core E via individual supply passages U and reaches the interior of the sealing member D. The annular passage K is sealed by means of two O-rings arranged in two radially concentric grooves. These grooves limit the maximum usable size of the annular passage K radially inwards and outwards and are engraved in the upper surface of the bottom surface B (alternatively, it is conceivable to form the annular passage K and / or the grooves partly or entirely in the lower surface of the balance housing C or in a flange-like intermediate part located therebetween). In this case, the upper surface of the bottom surface B can be configured to be substantially flat except for the core screw fastening portion N2 and the supply passage U).

[0068] As can be seen in Figures 2 and 3, the housing passage Q coming from the upper balance housing C communicates radially with the annular passage K between both O-rings or grooves. The O-ring is biased by the lower surface of the scale housing C and the upper surface of the bottom surface B when the modular seal is installed, thereby sealing the annular passage K completely.

[0069] As can be seen in Figures 2 to 4, the core E is configured in a corrugated form on its underside facing towards the head region P1. At this time, the wave troughs J provided on a partial circle having a radius r are in contact with the wave crests toward the inside and outside in the radial direction. The chamfered wave crests are intended to prevent the head region P1 of the sealing element D, with its inner surface facing the core E, from coming into contact with the possibly sharp areas of the hole (for the core screw fastening portion N2 or the supply passage U) and being damaged thereby. Therefore, these holes communicate at the wave trough J, and the head region P1 cannot come into contact with the wave trough since it is supported by the adjacent wave crest in the unpressurized state.

[0070] In the sealed state (not shown in the drawings), the load-introducing member L of the scale moves downward in the height direction Z, preferably towards the stopper R, against the force of a spring (not shown) due to the force F of the expanded sealing member D. A specially selected or adjusted spring force ensures that the mechanism / sensor inside the balance is only slightly loaded and is subjected to at most this spring force.

[0071] FIG. 3 shows two annular protrusions E1 provided on the core E and extending in the height direction Z. Two annular recesses P3 are provided on the upper surface of the seal member D, and these face the protrusions E1 in the height direction Z. When the core E is screwed to the retaining portion H, the protrusion E1 is pressed upward in the height direction Z against the sealing member D, thereby deforming the recess P3 so that it becomes flat, and at the same time, the clamping force on the retaining portion H is expanded or expanded radially, thereby being equalized. Without such recess P3, a high clamping force would occur in the sealing member D against the relatively thin annular area above the projection E1, which is prevented by the recess P3. At the same time, the protrusion E1 also stabilizes the seal member D in the radial direction. This is because the seal member surrounds the projection E1 from both sides in the radial direction. [Explanation of symbols]

[0072] A: Sealing area of ​​the sealing member B...Bottom surface C ···Scale housing D. Sealing material E...Core E1: Protrusion of core E F...force F G Sealing surface F S Wrench face G End Support H...Holding part H a ...outer support area H i ...inner support area J Wave trough K Circular passage L: Load introduction member M ··· Modular sealing N1...Thread N2...Core screw fastening part O...Holding part opening O G Housing opening P1: Head area of ​​the seal member P2: Wall area of ​​the seal member P3: Recess of seal member D Q Housing passage r: Radius of the partial circle R Stopper S...gap T...Communication section U...supply passage V... Closure module W...Weigher Z: Height direction Z A...long axis in the height direction

Claims

1. A modular sealing (M) for a balance, comprising: A load introducing member (L) of the scale protrudes downward from the housing (C) of the scale along a vertical height direction (Z), a) the sealing (M) preferably comprises a rotationally symmetrical closing module (V), the closing module (V) having a longitudinal axis (Z) extending in the height direction (Z); Ａ ) and has a central holding portion opening (O) through which the load introducing member (L) projects, b) the closure module (V) comprises a holding portion (H) and a fluid-expandable, extensible seal member (D) accommodated in the holding portion (H), the seal member (D) being selectively transitionable from the rest state to the sealing state or vice versa by a change in its internal pressure; c) the ceiling (M) further comprises end supports (G) for attachment to the load-introducing member (L); d) The sealing area (A) of the sealing member (D) is in a sealed state with the sealing surface (F) of the end support (G). Ｇ ) and thereby when at rest, said sealing surface (F Ｇ ) and the sealing member (D) to seal the gap (S) that exists between the sealing member (D), In modular sealing (M), e) the sealing surface (F Ｇ ) is arranged below the sealing element (D) in the height direction (Z), so that the sealing element (D) can move with the sealing area (A) by the extension in the height direction (Z) when it transitions from the rest state to the sealing state, and the sealing surface (F) located thereunder. Ｇ ) abutting against the modular sealing (M).

2. The holding part (H) has a coupling means, The coupling means can be directly or indirectly coupled to the balance housing (C), 10. A modular sealing (M) according to the preceding claim, characterized in that the coupling means are configured for centering the holder opening (O) of the holder (H) relative to a load-introducing element (L) protruding from the balance housing (C) and / or a housing opening.

3. The coupling means comprises a thread (N) configured in the center of the holder opening (O) for screwing with a corresponding thread on the balance housing (C). １ ), 10. A modular sealing (M) according to the preceding claim, wherein the corresponding thread circumscribes the load-introducing element (L), and the centering is achieved by the screw fastening.

4. The holding portion (H) has a bottom surface (B) on an upper surface facing away from the end support (G), At least one supply passage (U), particularly a hole, extends from the interior of the sealing member (D) to a communication portion (T) on the upper surface of the bottom surface, The communication portion (T) is radially connected to the holding portion opening (O) and / or the housing opening (O ｇ 10. A modular sealing (M) according to any one of the preceding claims, located between two sealing means and / or grooves which preferably concentrically surround the sealing means (M).

5. The sealing means, preferably configured as O-rings, inserted into the grooves radially delimit an annular passage (K) located between them, and the grooves and / or the annular passage (K) located between the sealing means are a) on the upper surface of the bottom surface (B), and / or b) on the underside of the balance housing facing the bottom surface (B), 10. A modular sealing according to the preceding claims, comprising:

6. The annular passage (K) is connected by a connection, in particular by a screw thread (N １ 10. The modular sealing (M) according to the preceding claim, wherein the sealing is effected by screwing the holding part (H) onto the balance housing (C) by means of a screw.

7. The sealing surface (F Ｇ ) is the long axis (Z Ａ ) and extends around the long axis (Z Ａ 10. A modular sealing (M) according to claim 9, characterized in that it has at least one contact area extending obliquely to the sealing area (A) against which the sealing area (A) abuts in the sealed state.

8. When the sealing member (D) is in a sealed state, the end support (G) is moved by a force along the longitudinal axis (Z Ａ 10. A modular sealing (M) according to claim 9, characterized in that it applies pressure both in a radial direction towards the outer periphery of the seal (M) and in a height direction (Z) perpendicular thereto.

9. The holding portion (H) is a) a preferably cylindrical inner support area (H) for blocking and supporting said sealing element (D) against unintentional radial inward extension; ｉ ) and / or d) a preferably cylindrical outer support area (H) for blocking and supporting said sealing element (D) against unintentional radially outward extension; ａ 10. A modular sealing (M) according to any one of the preceding claims, characterized in that it comprises a

10. The sealing member (D) has a longitudinal axis (Z Ａ ) and configured as an expandable bead or tube around the longitudinal axis (Z Ａ ) preferably has a core (E) that surrounds the core (E) in an annular shape, a) The core can be coupled to the holding part (H), and in particular the core screw fixing part (N ２ ) by means of which the sealing member (D) is fixed to the holding part (H), and / or b) said core (E) provides at least one fluid connection from the interior of said sealing member (D) to a supply passage (U) arranged in said holding part (H); and / or c) The lower surface of the core (E) facing the end support (G) is configured to have a wave shape when viewed in vertical cross section, and recesses carved into the core (E) as wave troughs (J) are formed in the core (E) and are used as the core screw fastening parts (N) that connect the core (E) to the holding parts (H). ２ ) along the major axis (Z Ａ ) and / or d) the sealing member has a head region (P) facing the end support (G) and including the sealing area (A); １ ) and the head region (P １ ) adjacent wall region (P ２ ) and the head region (P １ The wall thickness of the sealing member in at least one of the wall regions (P ２ ) so that when the sealing member (D) is subjected to a fluid, the sealing member (D) is mainly in at least one of the wall regions (P ２ 10. A modular sealing (M) according to any one of the preceding claims, characterized in that the end support (G) extends in the Z direction with a decreasing wall thickness towards the end support (G).

11. A balance (W) comprising a sealing (M) according to any one of the preceding claims and a load-introducing element (L) which extends contactlessly through the holder opening (O) and is connected to the end support (G), The sealing area (A) is in a sealed state when the sealing surface (F Ｇ ) to partially or completely prevent the intrusion of foreign matter into the holder opening (O) and into the scale housing (C).

12. Scale according to the preceding claim, characterized in that the sealing (D) is configured to move the load-introducing member (L) by a force (F), preferably against a spring force, in the height direction (Z), preferably towards a stop R.

13. A method for assembling a modular sealing according to any one of claims 5 to 10 to a balance according to claim 11 or 12, comprising the steps of: Next method steps: i) The holding part (H) has its thread (N １ ) into a matching corresponding thread of said balance housing (C), wherein said threading simultaneously a) The holder opening (O) is connected to the housing opening (O) of the balance. Ｇ ) and / or centered relative to the load-introducing member (L), and b) at least one of said annular passages (K) is closed in the height direction (Z) by said balance housing with its upper surface facing towards said balance and is sealed in the radial direction by a sealing means clamped between said bottom surface (B) and said balance housing (C); A method comprising the steps of:

14. At the same time, by the screwing, c) the method according to the preceding claims, characterized in that the annular passage (K) is fluidically connected to a connection of a housing passage (Q) which is led out at the underside of the balance housing (C) and provides fluid for the sealing element.

15. A sealing element (D) for modular sealing (M) according to any one of claims 1 to 10, The sealing member (D) is a reversibly elastic, fluid-applicable bead having a longitudinal axis (Z) extending in the height direction (Z). ａ ) and the seal member has a rotational symmetry about the major axis (Z Ａ ) has a core (E) that is rotationally symmetric with respect to: a) the core (E) engages with at least one mounting area of ​​the sealing element (D) by means of a projection shaped complementarily to the mounting area in order to fix the sealing element (D) to the holding portion (H); b) the core (E) has a corrugated surface at least in areas to avoid sharp contact with the inner surface of the sealing element (D), and / or c) the core (E) has at least one hole leading from the interior of the sealing element, by means of which a fluid can be supplied to the sealing element or which can be attached to a holding part (H), and / or d) The sealing member has a projection (E) of the core (E) on its preferably flat outer surface facing away from the core (E). １ ) in the height direction Z. ３ ) a sealing member (D).

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