Fluid measuring or fluid control device

Abstract

A fluid measuring or fluid control device has a housing the housing parts of which are fastened to each other by at least one screwed connection, in which a screw engages through an opening in a peripheral wall of the first housing part and is screwed into a threaded opening in the second housing part. An elastic seal is arranged between the housing parts. The first housing part has a first resting face, and the second housing part has a second resting face which are both in peripherally circumferential contact with the seal. The screw shank and an edge of the opening have cooperating frustoconical surfaces which are oriented such that the second housing part is displaced in the direction towards the first housing part when the screw is screwed into the threaded opening, the resting faces coming into contact with the seal.

Claims

1. A fluid measuring or fluid control device, having a housing including a first and a second housing part fastened to each other by at least one screwed connection, the screwed connection comprising a screw having a screw shank and a screw head, an opening in a peripheral wall of the first housing part through which the screw shank engages, and a threaded opening in the second housing part which receives the screw shank, wherein an elastic seal having a peripherally circumferential edge region is arranged between the housing parts, and the first housing part has a first resting face and the second housing part has a second resting face, wherein in a non-assembled initial position, one of the housing parts has its resting face resting against the seal, and wherein the screw shank and an edge of the opening have cooperating frustoconical surfaces, wherein in the initial position, the opening in the peripheral wall and the threaded opening are radially offset to each other with their central axes and the frustoconical surfaces are oriented such that upon screwing-in, the frustoconical surfaces displace the two housing parts laterally to each other so that the resting face presses against and elastically deforms the seal.

2. The fluid measuring or fluid control device according to claim 1, wherein the first resting face on the first housing part is a peripherally circumferential projection which engages in the seal in a fully tightened position of the screwed connection.

3. The fluid measuring or fluid control device according to claim 2, wherein a displacement path (d) of the housing parts from the initial position to the fully tightened position is larger than an extension of the projection along a direction of displacement (L).

4. The fluid measuring or fluid control device claim 1, wherein the second resting face on the second housing part is a peripherally circumferential annular groove into which the seal is inserted.

5. The fluid measuring or fluid control device claim 1, wherein the frustoconical surface on the screw shank is arranged between a screw head of the screw and a threaded section on the screw shank.

6. The fluid measuring or fluid control device claim 1, wherein a plurality of screwed connections is provided along a periphery of the first housing part.

7. The fluid measuring or fluid control device claim 1, wherein the threaded opening in the second housing part is provided in a fastening block which extends into an interior of the first housing part.

8. The fluid measuring or fluid control device claim 1, wherein a seal is provided on the screw at a lower end of the screw head.

9. The fluid measuring or fluid control device claim 1, wherein the first housing part is a housing body and the second housing part is a cover which closes the housing body from the environment.

10. The fluid measuring or fluid control device claim 1, wherein the fluid measuring or fluid control device is part of a mass flow meter according to the Coriolis principle, which includes two fluid connections and a measuring tube through which fluid flows and which fluidically connects the two fluid connections to each other.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic lateral view of a fluid measuring or fluid control device according to the invention;

(2) FIG. 2 is a schematic perspective exploded view of the fluid measuring or fluid control device from FIG. 1;

(3) FIGS. 3 to 5 are schematic sectional views of a screwed connection of the fluid measuring or fluid control device from FIG. 1 along the line III-III during tightening of the screwed connection; and

(4) FIG. 6 is a detail of the housing of the fluid measuring or fluid control device in the region of a screwed connection in a sectional view.

DETAILED DESCRIPTION

(5) FIGS. 1 and 2 show a fluid measuring or fluid control device 10 having a housing 12.

(6) In this example, the fluid measuring or fluid control device 10 is a mass flow meter operating in accordance with the Coriolis principle. To this end, two fluid connections 14 are provided in a lower section of the housing 12 in FIGS. 1 and 2 (each closed by plugs in the figures) and are fluidically connected by a measuring tube 16 which is indicated by a dashed line in FIG. 1 and is caused to vibrate in a known manner, which permits the determination of a fluid flow through the measuring tube 16, for example.

(7) The invention may of course also be used for any other types of fluid measuring or fluid control devices.

(8) The housing 12 includes a first housing part 18 and a second housing part 20 connected thereto. The first housing part 18 here forms a housing body, and the second housing part 20 forms a cover, which closes the first housing part 18 from the environment.

(9) The first housing part 18 is here formed to be cylindrical with a rectangular cross-section and defines a longitudinal direction L. Along the longitudinal direction L, the second housing part 20 is clearly shorter than the first housing part 18 and has a cover surface 22 which is oriented perpendicularly to the longitudinal direction L and the form of which approximately corresponds to the cross-section of the first housing part 18.

(10) Both the measuring tube 16 and a suitable control and evaluation electronics (not shown) are for example accommodated in the interior of the first housing part 18. Connections 24 for electric and control lines are provided laterally on one of the narrow sides of the first housing part 18 and are sealed from the environment.

(11) Two openings 30 which are arranged close to a peripheral edge 32 of a peripheral wall 28 are respectively provided on the two opposite broad sides 26 of the peripheral wall 28 of the first housing part 18. The openings 30 of the two sides 26 are opposite each other. The peripheral wall 28 extends parallel to the longitudinal direction L and is circumferentially closed with respect thereto.

(12) A corresponding threaded opening 34 is respectively provided on the second housing part 20 for each of the openings 30, wherein the openings 30 and the threaded openings 34 overlap when the second housing part 20 is placed onto the first housing part 18 (cf. FIGS. 3 to 5).

(13) In this example, two threaded openings 34 are respectively arranged opposite each other in a fastening block 36, which protrudes perpendicularly from the cover surface 22 of the second housing part 20 (cf. FIG. 2).

(14) One opening 30 and one threaded opening 34 along with a screw 38 respectively form a screwed connection 40. The second housing part 20 is firmly and sealingly connected to the first housing part 18 by tightening all screwed connections 40, in this example a total of four screwed connections.

(15) A first resting face 42, here a peripherally circumferential projection extending in the longitudinal direction L, is formed on the peripheral edge 32. A second resting face 46, here in the form of a peripherally circumferential annular groove, which is opposite the projection, is provided on a cover peripheral edge 44 of the second housing part 18 which faces the peripheral edge 32 of the first housing part 18.

(16) A seal 48 is inserted in the annular groove, which includes a peripherally circumferential edge region 49 the outer contour of which follows the peripheral edge 32.

(17) In this example, the seal 48 is a flat seal which is adapted to the cross-sectional shape of the housing 12 and to the components accommodated in the interior of the housing 12 (cf. FIG. 2).

(18) It would of course also be possible to provide the projection on the second housing part 20 and the annular groove on the first housing part 18, as long as a resting face 42, 46 is arranged on each of the housing parts, such that a circumferential linear or planar contact with the seal 48 is obtained.

(19) The screw 38 comprises a screw head 50 and a screw shank 52. A threaded section 54 which is adapted to the thread of the threaded opening 34 and which can be screwed therein is provided at the free end of the screw shank 52.

(20) Between the screw head 50 and the threaded section 54, the screw 38 includes a frustoconical surface 56 which is widened in the direction towards the screw head 50. Here, an end 58 of the frustoconical surface 56 away from the screw head approximately has the diameter of the threaded section 54.

(21) The opening 30 is completely guided through the peripheral wall 28.

(22) FIG. 6 shows a cross-section through the peripheral wall 28 in the area of the opening 30. In the example shown here, as seen from the interior of the housing, a first section 60 of the edge 62 of the opening 30 is circular cylindrical with a diameter only slightly larger than that of the threaded section 54 of the screw 38. The latter is adjoined by a frustoconical surface 64 which widens towards the exterior side of the housing. The other, wider end of the frustoconical surface 64 is surrounded by a first counterbore 66, which in turn is surrounded by a second counterbore 68 of lesser depth (relative to the exterior side of the housing).

(23) The inclinations of the two frustoconical surfaces 56, 64 on the screw shank 52 and on the edge 62 of the opening 30 have the same inclination, for example about 30° with respect to the longitudinal axis L.sub.S of the screw shank 52 or the longitudinal axis L.sub.Ō of the opening 30.

(24) The frustoconical surface 56 on the screw shank 52 is here significantly longer than the frustoconical surface 64 on the edge 62 of the opening 30, e.g., by a factor of 3 to 10.

(25) In this example, a second annular groove 72 is furthermore provided on the underside 70 of the screw head 50 facing the screw shank, into which a second seal 74, in this case an O-ring, is inserted.

(26) To connect the second housing part 20 to the first housing part 18, the second housing part 20 is placed on the first housing part 18 in an initial position shown in FIG. 3, and for each of the screwed connections 40, a screw 38 is inserted through one of the openings 30 into the threaded opening 34.

(27) In the initial position, an edge of the screw head 50 close to the second housing part 20 is located outside the second counterbore 68 with respect to the longitudinal direction L.sub.S of the screw shank 52, but is level with the edge 76 of the second counterbore 68 which faces the second housing part 20 with respect to the longitudinal direction L of the housing 12 (cf. FIG. 3).

(28) The frustoconical surface 56 on the screw shank 52 is in contact with the frustoconical surface 64 on the edge 62 of the opening 30, but only in a region facing the second housing part 20. On the opposite side, the frustoconical surface 56 on the screw shank 52 is spaced from the frustoconical surface 64 on the opening 30.

(29) The central axis, i.e., the longitudinal axis L.sub.S of the screw shank 52 and the central axis, i.e., the longitudinal axis L.sub.Ō of the opening 30 are parallel to each other, but are radially offset from each other as seen in the longitudinal direction L of the housing 12, the longitudinal axis L.sub.S of the screw shank 52 being offset in the direction towards the second housing part 20. This offset also corresponds to the relative displacement path d of the housing parts 18, 20 relative to each other. The screw shank 52 is of course coaxial with the threaded opening 34, since it is screwed therein.

(30) In this position, the seal 48 in the annular groove on the second housing part 20 is not, or only just, in contact with the projection on the peripheral edge 32 of the first housing part 18, so that the screws 38 can be inserted into the openings 30 and initially screwed into the threaded openings 34 without deforming the seal 48.

(31) This is achieved by appropriately dimensioning the length of the fastening blocks 36 or, more generally, the distance between the threaded opening 34, the resting faces 42, 46, the seal 48 and the position of the openings 30.

(32) If the screw 38 is tightened further, i.e., screwed further into the threaded opening 34, the frustoconical surfaces 56, 64 on the screw shank 52 and on the edge 62 of the opening 30 slide against each other, causing the housing parts 18, 20 to be displaced laterally relative to each other, the second housing part 20 being moved closer to the first housing part 18 in a direction of displacement V along the longitudinal direction L. This is shown in FIG. 4.

(33) As a result, the frustoconical surface 56 on the screw shank 52 moves further towards the peripheral wall 28 of the first housing part 18, so that the screw head 50 begins to dip into the second counterbore 68.

(34) The first resting face 42, i.e., here the projection, is pressed into the seal 48 due to the tensile force that the screw 38 exerts along the longitudinal direction L on the fastening block 36 and via the latter on the entire second housing part 20.

(35) In addition, the material of the second seal 74 below the screw head 50 is elastically deformed and spreads out in the first counterbore 66.

(36) This movement continues until the screw 38 and thus also the screwed connection 40 has reached its fully tightened position, in which further tightening of the screw 38 is no longer possible, as the two frustoconical surfaces 56, 64 lie flat against each other. In this example, the underside 70 of the screw head 50 also rests against the bottom of the second counterbore 68, which serves as a stop, so to speak, for the end of the screwing movement. The two housing parts 18, 20 have travelled the complete displacement path d towards each other, so that now the longitudinal axes L.sub.S, L.sub.Ō coincide on a straight line. This fully tightened position is shown in FIG. 5.

(37) The displacement path d is determined here by the length of the frustoconical surface 56 on the screw shank 52, while the frustoconical surface 64 on the edge 62 of the opening 30 acts as a guide.

(38) It follows from these specifications that a smallest diameter of the opening 30 here is larger than a diameter of the end 58 of the frustoconical surface 56 of the screw 38 away from the screw head.

(39) The displacement path d is dependent on the cosine of the angle of the frustoconical surface 56 with the longitudinal axis L.sub.S of the screw shank 52, and is therefore always shorter than an axial length of the frustoconical surface 56.

(40) The length over which the projection engages into the seal 48 is chosen to be slightly shorter than the displacement path d, so that the second housing part 20 can be placed on the first housing part 18 in the fitted position without being obstructed by the projection of the first resting face 42.

(41) In this way, all screwed connections 40 on the housing 12 are tightened up to their fully tightened position.

(42) This arrangement ensures a dustproof and watertight connection between the two housing parts 18, 20, which fulfils the requirements of protection rating IP65 and even protection rating IP67.

(43) If the housing 12 is to be opened, all screwed connections 40 are loosened again and the screws 38 removed, as a result of which the second housing part 20 can be removed from the first housing part 18. The two housing parts 18, 20 can be reconnected in the way described above, the seal 48 having to be replaced if necessary.