INFLATABLE SEAL

Abstract

The invention relates to a modular seal for scales, having a load application element which transmits a weight force in a vertical direction Z. The seal includes a closure module with a sealing element that forms a chamber that may be acted on by pressure, and a counterbearing that includes a sealing surface. The chamber may be acted on by a medium in such a way that a sealing section rests against the sealing surface in the vertical direction z.

Claims

1. A modular seal (M) for scales, having a load application element (L) that protrudes downwardly from a housing (C) of the scales along a vertical direction (Z), a) the seal (M) including a preferably rotationally symmetrical closure module (V) that extends about a longitudinal axis (Z.sub.A) running in the vertical direction (Z), and a central holder opening (0) through which the load application element (L) can protrude, b) wherein the closure module (V) includes a holder (H) and an expandable sealing element (D) that is accommodated by the holder (H) and inflatable with fluid, and that is selectively transferable from a rest state into a sealing state or back by changing the internal pressure of the sealing element, c) the seal (M) further including a counterbearing (G) for fastening to the load application element (L), d) wherein a sealing section (A) of the sealing element (D) is designed to rest against a sealing surface (F.sub.G) of the counterbearing (G) in the sealing state, thereby sealing off a gap(S) that is present between the sealing surface (F.sub.G) and the sealing element (D) in the rest state, characterized in that e) the sealing surface (F.sub.G) is situated below the sealing element (D) in the vertical direction (Z) in such a way that, during the transition from the rest state into the sealing state, the sealing element (D), due to its expansion in the vertical direction (Z), rests with its sealing section (A) against the underlying sealing surface (F.sub.G).

2. The modular seal (M) according to claim 1, characterized in that the holder (H) has connection means via which the holder is directly or indirectly connectable to a scale housing (C), the connection means being designed to center the holder opening (0) of the holder (H) relative to a load application element (L) that protrudes from the scale housing (C), and/or relative to the housing opening.

3. The modular seal (M) according to claim 2, wherein the connection means have a thread (N.sub.1), provided centrally with respect to the holder opening (O), for a screw connection to a mating thread of the scale housing (C), wherein the mating thread encircles the load application element (L) and the centering takes place by means of the screw connection.

4. The modular seal (M) according to claim 1, wherein the holder (H) has a base (B) on its top side facing away from the counterbearing (G), and at least one feed channel (U), in particular a borehole, leads out from the interior of the sealing element (D) to an opening (T) on the top side of the base, and the opening (T) is situated between two sealing means and/or grooves that preferably concentrically surround the holder opening (0) and/or the housing opening (O.sub.g).

5. The modular seal (M) according to claim 4, wherein the sealing means, which are preferably inserted into the grooves and also are preferably designed as O-rings, radially delimit an annular channel (K) situated in between, and wherein the grooves and/or the annular channel (K) situated between the sealing means are/is formed a) in the top side of the base (B) and/or b) in a bottom side of a scale housing facing the base (B).

6. The modular seal (M) according to claim 5, wherein the annular channel (K) is sealed off by connecting, in particular screwing down or screwing in the holder (H) into a scale housing (C) by means of a thread (N.sub.1).

7. The modular seal (M) according to claim 1, characterized in that the sealing surface (F.sub.G) extends circumferentially about the longitudinal axis (Z.sub.A) and has at least one contact area, extending at an angle to the longitudinal axis (Z.sub.A), against which the sealing element (A) rests in the sealing state.

8. The modular seal (M) according to claim 1, characterized in that the sealing element (D) in the sealing state acts on the counterbearing (G) with a force radially in the direction of the longitudinal axis (Z.sub.A), and also orthogonally thereto in the vertical direction (Z).

9. The modular seal (M) according to claim 1, characterized in that the holder (H) includes a) an inner, preferably cylindrical, support section (H.sub.i) that radially inwardly blocks and supports the sealing element (D) against unintentional expansion, and/or d) an outer, preferably cylindrical, support section (H.sub.a) that radially outwardly blocks and supports the sealing element (D) against unintentional expansion.

10. The modular seal (M) according to claim 1, characterized in that the sealing element (D) is designed as an inflatable ridge or tube that extends circumferentially about the longitudinal axis (Z.sub.A), and in its interior has a dimensionally stable core (E) which preferably circularly extends about the longitudinal axis (Z.sub.A), a) wherein the core is connectable to the holder (H), in particular screwable via a core screw connection (N.sub.2), in order to fix the sealing element (D) to the holder (H), and/or b) wherein the core (E) provides at least one fluidic connection from the interior of the sealing element (D) to a feed channel (U) that is formed in the holder (H), and/or c) wherein a bottom side of the core (E) facing the counterbearing (G) has an undulating design in the vertical cross section, and an indentation incorporated into the core (E) as a wave trough (J) has the same radial distance from the longitudinal axis (Z.sub.A) as a core screw connection (N.sub.2) that connects the core (E) to the holder (H), and/or d) wherein the sealing element has a head region (P.sub.1) that faces the counterbearing (G) and surrounds the sealing section (A), and wall regions (P.sub.2) that adjoin the head region (P.sub.1) on the inside and on the outside in the radial direction, wherein the wall thickness of the sealing element at the head region (P.sub.1) is greater than at at least one wall region (P.sub.2), so that when the sealing element (D) is acted on by fluid, primarily the at least one wall region (P.sub.2) is stretched toward the counterbearing (G) in the Z direction, with reduction of its wall thickness.

11. Scales (W) having a seal (M) according to claim 1 and having a load application element (L) that extends through the holder opening (0) without contact and that is connected to the counterbearing (G), wherein in the sealing state, by impingement on the sealing surface (F.sub.G) the sealing section (A) partially or completely prevents penetration of foreign matter into the holder opening (0) and into the scale housing (C).

12. Scales according to claim 11, characterized in that the seal (D) is designed to move the load application element (L) in the vertical direction (Z), preferably against a stop (R), by means of the force (F), preferably against an elastic force.

13. A method for installing a modular seal, comprising: i) providing a modular seal (M) for scales, having a load application element (L) that protrudes downwardly from a housing (C) of the scales along a vertical direction (Z), a) the seal (M) including a preferably rotationally symmetrical closure module (V) that extends about a longitudinal axis (Z.sub.A) running in the vertical direction (Z), and a central holder opening (O) through which the load application element (L) can protrude, b) wherein the closure module (V) includes a holder (H) and an expandable sealing element (D) that is accommodated by the holder (H) and inflatable with fluid, and that is selectively transferable from a rest state into a sealing state or back by changing the internal pressure of the sealing element, c) the seal (M) further including a counterbearing (G) for fastening to the load application element (L), d) wherein a sealing section (A) of the sealing element (D) is designed to rest against a sealing surface (F.sub.G) of the counterbearing (G) in the sealing state, thereby sealing off a gap(S) that is present between the sealing surface (F.sub.G) and the sealing element (D) in the rest state, characterized in that e) the sealing surface (F.sub.G) is situated below the sealing element (D) in the vertical direction (Z) in such a way that, during the transition from the rest state into the sealing state, the sealing element (D), due to its expansion in the vertical direction (Z), rests with its sealing section (A) against the underlying sealing surface (F.sub.G); ii) screwing the holder (H) with its thread (N.sub.1) into a matching mating thread in the scale housing (C), wherein simultaneously with the screwing a) the holder opening (O) is centered relative to the housing opening (O.sub.G) in the scales and/or to the load application element (L), and b) on its top side facing the scales, the at least one annular channel (K) is closed in the vertical direction (Z) by the scale housing, and is sealed off in the radial direction by the sealing means that are clamped between the base (B) and the scale housing (C).

14. The method according to claim 13, characterized in that as a result of the screwing, at the same time c) the annular channel (K) is also fluidically connected to the opening of a housing channel (Q) which is led out on the bottom side of the scale housing (C) and which provides the fluid for the sealing element.

15. A sealing element (D) for a modular seal (M) according to claim 1, wherein the sealing element (D) is designed as a reversibly elastic ridge that may be acted on by a fluid, and that is rotationally symmetrical about a longitudinal axis (Z.sub.a) and extends in a vertical direction (Z), and wherein the sealing element in its interior has a core (E) that is rotationally symmetrical with respect to the longitudinal axis (Z.sub.A): a) wherein the core (E), for fixing the sealing element (D) to a holder (H), encompasses at least one mounting section of the sealing element, with a protrusion that is shaped to complement the mounting section, and/or b) wherein the core (E) has an undulating surface, at least in sections, to avoid sharp-edged contact with the inner side of the sealing element (D), and/or c) wherein the core (E) has at least one borehole leading out from the interior of the sealing element, via which the sealing element may be supplied with fluid or fastened to a holder (H), and/or d) wherein on a preferably flat outer surface facing away from the core (E), the sealing element has at least one indentation (P.sub.3) that is situated opposite from a protrusion (E.sub.1) of the core in the vertical direction (Z).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0062] One embodiment of the invention is explained in greater detail below based on examples in the figures, as follows:

[0063] FIG. 1 shows scales with two underfloor load outputs and two seals according to the invention,

[0064] FIG. 2 shows a simplified sectional illustration of a modular seal according to the invention in the rest state,

[0065] FIG. 3 shows a simplified detailed view of the holder with a sealing element inserted therein, and

[0066] FIG. 4 shows a partially cutaway oblique view of the holder.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0067] FIG. 1 shows a perspective illustration of the housing C of multitrack (dual-track) scales W, which include two sensors, situated inside the housing C and not illustrated in greater detail, for detecting a weight force. The scales are equipped with an underfloor load output, so that for each sensor a dedicated load application element on the bottom side of the scales protrudes downwardly through a separate housing opening O.sub.G in the housing C in order to be acted on, outside the housing, by a force to be measured. For each load application element (also referred to as a load receptor, load application bolt, or load bolt), a modular seal M according to the invention is provided which extends essentially rotationally symmetrically in each case about an associated longitudinal axis Z.sub.A running in the vertical direction Z.

[0068] FIG. 2 shows a sectional illustration of details of a modular seal M according to the invention, which is connected to a lower, horizontal section of the housing C of the scales. A load application element L protrudes downwardly in the vertical direction Z, through the housing opening O.sub.G in the bottom side of the housing C and out of the housing. Via elements not illustrated in greater detail, a force to be measured may be introduced as a tensile force into the load application element L in the vertical direction Z, and conducted upwardly by the load application element into the interior of the scale housing C to a force sensor. In this embodiment, the load application element L includes at least two elements that are screwable to one another in the vertical direction z.

[0069] A closure module V, as part of the modular seal, includes a holder H having a rotationally symmetrical design about the longitudinal axis Z.sub.A, and a flange-like base B facing the scale housing C. A thread N.sub.1 (external thread) is provided on a connecting piece that upwardly and centrally protrudes from the base B, as also shown in FIG. 4. The connecting piece is screwed into a matching mating thread (internal thread) in the base of the housing C. The holder H is automatically centered relative to the housing opening O.sub.G and to the load application element L by this screw connection. To allow the holder H to be screwed into the scale housing C in a particularly easy manner and preferably with a predefined torque, wrench flats F.sub.S are provided at the outer circumference of the scale housing for engagement with a suitable tool, in particular an open-end wrench or socket wrench (see FIG. 4).

[0070] On the bottom side of the base B facing away from the scale housing C, two cylindrical support sections H.sub.i, H.sub.a that extend in the vertical direction Z, concentrically with respect to the longitudinal axis Z.sub.A, are provided, which in the radial direction form between them a groove extending circumferentially about the longitudinal axis. An annular, ridge-like elastic sealing element D that is impingeable by fluid is situated in this groove. The inner support section H.sub.i borders the holder H on the inside in the radial direction, and is used in particular to prevent expansion of the sealing element D in the direction of the load application element L. The outer support section H.sub.a, which protrudes downwardly beyond the sealing element D in the vertical direction Z, borders the holder H on the outside in the radial direction and prevents expansion of the sealing element D in this direction. Both support sections are also used to support and guide the sealing element D in the vertical direction z.

[0071] A counterbearing G having a rotationally symmetrical design about the longitudinal axis Z.sub.A extends below the holder H, and is fastened to a bottom free end of the load application element L via a screw connection, not illustrated in greater detail. The counterbearing has a conical sealing surface F.sub.G facing the holder. The radius of the counterbearing G or of the sealing surface F.sub.G increases with increasing distance Z from the holder H.

[0072] In the rest state illustrated in FIG. 2, a gap S exists between the sealing element D and the sealing surface F.sub.G. In this state, the load application element L together with the counterbearing G can move relative to the holder H in the vertical direction Z, free of shunt force, and can transfer a load unhindered into the interior of the scale housing C. For maintenance or cleaning purposes the interior of the scale housing may be sealed off and protected by closing the gap S. According to the invention, this takes place by impinging the sealing element L, which is inserted into the holder H, with a fluid, and the sealing element is thus expanded in the vertical direction Z or toward the counterbearing G until it rests with a sealing section A against the sealing surface F.sub.G or acts on it with a contact force F. The modular seal is then in the sealing state, and due to the closed gap S the housing opening O.sub.G is sealed off from the surroundings. The counterbearing G is preferably moved downwardly far enough that the load application element L with an extended flange strikes against a stop R provided at the inner side of the scale housing C, and is thus fixed in the vertical direction.

[0073] When the fluid pressure inside the sealing element L is once again reduced, the sealing section A of the sealing element L retracts upwardly once again from the sealing surface F.sub.G in the opposite vertical direction z, thus once again forming the gap S and freeing up the counterbearing together with its load application element L for regular operation.

[0074] Supplying the sealing element with a fluid (in the simplest case, compressed air) is explained in particular with reference to FIG. 3. Shown there is an enlarged sectional illustration of the portion of the holder H situated to the right of the longitudinal axis Z.sub.A according to FIG. 2. Shown is the elastic sealing element D, which is enclosed between the inner support element H.sub.1 and the outer support element H.sub.a, and which extends as an annular ridge about the longitudinal axis Z.sub.A and has a dome-like cross section on the bottom side facing away from the base B. In this area the sealing element D includes a head region P.sub.1, which in the radial direction transitions in one piece, to the inside and to the outside in each case, into a wall region P.sub.2. The sealing element D has a greater wall thickness in the head region P.sub.1 than in the two wall regions P.sub.2. Due to the smaller wall thickness, the wall regions P.sub.2 are more extendable in the Z direction than is the head region P.sub.1. When the sealing element D is acted on by pressure, the wall regions P.sub.2 are thus preferably stretched downwardly in the vertical direction Z, additionally guided by the support sections H.sub.i and H.sub.a. As a result, the head region P.sub.1 together with its sealing section A moves essentially straight down in the vertical direction Z, toward the counterbearing G.

[0075] As shown in FIGS. 2, 3, and 4, situated inside the sealing element D is an annular core E that is used in particular to stabilize the sealing element D and fasten it at its upper end to the base B. In the circumferential direction, multiple vertical boreholes are provided in the core E, on a pitch circle having a radius r. Some of the boreholes are provided with a thread for screwing the core E to the holder H (core screw connection N.sub.2). In addition, multiple through holes are provided on the above-mentioned pitch circle in the vertical direction Z, which lead from the interior of the sealing element D through the core E and the base of the holder H, toward the bottom side of the scale housing C, as is apparent in particular in FIG. 3 and in the left portion of FIG. 4. Each of these boreholes forms a feed channel U through which the interior of the sealing element D may be supplied with and impinged by fluid. On the top side of the base B, the feed channel U at the opening T opens into an annular channel K that is concentric with respect to the longitudinal axis Z.sub.A. In the example in FIGS. 3 and 4, this annular channel K is provided in the base of the holder H. As an alternative, FIG. 2 shows the provision of the annular channel K in the bottom side of the scale housing C.

[0076] Compressed air may be fed into the annular channel K via a housing channel Q that is provided in the scale housing C, and from the annular channel passes through the core E via the individual feed channels U and into the interior of the sealing element D. In the radial direction the annular channel K is sealed off by means of two O-rings situated in two mutually concentric grooves. The grooves limit the maximum usable size of the annular channel K in the radial direction on the outside and on the inside, and are introduced into the top side of the base B. (Alternatively, it is conceivable to provide the annular channel K and/or the grooves partially or completely in the bottom side of the scale housing C or in an intervening, flange-like intermediate piece. Then, for example, the top side of the base B, except for the core screw connections N.sub.2 and the feed channels U, could have an essentially flat design).

[0077] As shown in FIGS. 2 and 3, the housing channel Q coming from the scale housing C from above opens into the annular channel K, in the radial direction between the two O-rings or grooves. In the installed state of the modular seal, the O-rings are impinged from the bottom side of the scale housing C and the top side of the base B, thus completely sealing the annular channel K.

[0078] It is apparent In FIGS. 2 through 4 that the core E has an undulating design on its bottom side facing the head region P.sub.1. A wave trough J provided on the pitch circle having a radius r in each case adjoins a wave crest on the inside and on the outside in the radial direction. The rounded wave crests are intended to prevent the head region P.sub.1 of the sealing element D, with its inner side facing the core E, from contacting the possibly sharp-edged region of a borehole (for a core screw connection N.sub.2 or a feed channel U) and thus sustaining damage. Therefore, these boreholes open into the wave trough J, which in the pressureless state, supported by the adjoining wave crests, the head region P.sub.1 cannot contact.

[0079] In the sealing state (not illustrated in the figure), the load application element L of the scales is moved downwardly in the vertical direction Z, preferably against the stop R, by the force F of the inflated sealing element D, preferably against the force of a spring (not illustrated). Due to a specifically selected or set elastic force, the mechanism/sensor system situated inside the scales is subjected to little stress, at most by this elastic force.

[0080] FIG. 3 shows two annular protrusions E.sub.1, extending in the vertical direction Z, which are provided at the core E. On the top side of the sealing element D, two annular indentations P.sub.3 situated opposite from the protrusions E.sub.1 in the vertical direction Z are provided in the sealing element. Due to the screw connection of the core E to the holder H, the protrusions E.sub.1 press upwardly on the sealing element D in the vertical direction Z, as a result of which the indentations P.sub.3 are deformed with flattening, and at the same time the clamping force on the holder H is extended or broadened in the radial direction and thus equalized. Without such indentations P.sub.3, a high clamping force could result on a relatively narrow area above the protrusions E.sub.1 in the sealing element D, which is thus prevented by the indentations P.sub.3. At the same time, the protrusions E.sub.1 also bring about radial stabilization of the sealing element D, since it encloses the protrusions E.sub.1 on both sides in the radial direction.

LIST OF REFERENCE SYMBOLS

[0081] A sealing section of the sealing element [0082] B base [0083] C scale housing [0084] D sealing element [0085] E core [0086] E.sub.1 protrusion at the core E [0087] F force [0088] F.sub.G sealing surface [0089] F.sub.S wrench flat [0090] G counterbearing [0091] H holder [0092] H.sub.a outer support section [0093] H.sub.i inner support section [0094] J wave trough [0095] K annular channel [0096] L load application element [0097] M modular seal [0098] N.sub.1 thread [0099] N.sub.2 core screw connection [0100] O holder opening [0101] O.sub.G housing opening [0102] P.sub.1 head region of the sealing element [0103] P.sub.2 wall region of the sealing element [0104] P.sub.3 indentation in the sealing element D [0105] Q housing channel [0106] r pitch circle radius [0107] R stop [0108] S gap [0109] T opening [0110] U feed channel [0111] V closure module [0112] W scales [0113] Z vertical direction [0114] Z.sub.A longitudinal axis in the vertical direction