FLOW TUBE FOR A FLOW SENSOR AND PROCESS FOR MANUFACTURING A FLOW TUBE

Abstract

A flow tube (10) has a housing (12, 14) including at least a first housing half (12) and a second housing half (14). Each housing half (12, 14) has a connection surface (20, 22) intended for combination with the other housing half (12, 14). The connection surfaces (20, 22) enclose a mounting gap (30) for an orifice element (16). Outside of the mounting gap (30) the connection surfaces (20, 22) butt against each other in some sections by respective abutting surface portions (32, 34), and outside of the mounting gap (30) and outside of the abutting surface portions (32, 34) the housing halves (12, 14) are integrally combined with each other. A method is provided for producing the flow tube, namely for integrally joining the housing halves (12, 14).

Claims

1. A flow tube with a housing comprising at least a first housing half and a second housing half, wherein each housing half has a connection surface which is configured to combine with the respective other housing half, wherein the connection surfaces of the two housing halves combined with one another enclose a mounting gap for a diaphragm element functioning as a flow body in a flow duct (24) defined by the housing, wherein the connection surfaces of the two housing halves combined with one another abut against one another in some sections outside of the mounting gap and in this respect each connection surface comprises an abutting surface section, wherein the housing halves are combined with one another by connection in substance in a connection in substance area outside of the mounting gap and outside of the abutting surface section, wherein at least one of the two housing halves is laser transparent in the area of the connection in substance area, and wherein the two housing halves are combined with one another by connection in substance, in the connection in substance area, by laser welding.

2. A flow tube in accordance with claim 1, wherein one of the housing halves has at least one connection surface projection and the other housing half has at least one connection surface recess configured to receive the projection, and wherein the housing halves are combined with one another by connection in substance by means of the projection and the recess by surfaces or surface sections of the projection and of the recess coming into contact with one another during the joining of the housing halves forming the connection in substance area.

3. A flow tube in accordance with claim 2, wherein the mounting gap, the abutting surface sections as well as the projection and the recess are arranged on the connection surfaces in a radial direction such that the mounting gap is located in front of the abutting surface sections in relation to the abutting surface sections and the projection and the recess are located behind the abutting surface sections in relation to the abutting surface sections.

4. A flow tube in accordance with claim 2, wherein the projection and the recess are connected to one another by connection in substance in the area of a radially outermost common contact surface.

5. A flow tube in accordance with claim 2, wherein the at least one projection is a radially extending projection and the at least one recess is a radially extending recess.

6. A flow tube in accordance with claim 1, wherein the two housing halves are connected by connection in substance by means of a laser beam expanded onto a cone envelope active along an entire perimeter thereof.

7. A flow sensor comprising a flow tube, the flow tube comprising: a first housing portion with a first portion connection surface; and a second housing portion with a second housing portion connection surface configured to combine with the first portion connection surface and to enclose a mounting gap for a diaphragm element as a flow body in a flow duct defined by the housing wherein the first portion connection surface comprises a first abutting surface section abutting against a second abutting surface section of the second portion connection surface with said first housing portion combined with said second housing portion and a connection in substance area is provided outside of the mounting gap and outside of the abutting surface section with said first housing portion combined with said second housing portion and at least one of the first housing portion and the second housing portion is laser transparent in the area of the connection in substance area and the first housing portion and the second housing portion are combined with one another by connection in substance, in the connection in substance area, by laser welding.

8. A process for manufacturing a flow tube comprising a first housing half with a first portion connection surface and a second housing half with a second housing portion connection surface configured to combine with the first portion connection surface and to enclose a mounting gap for a diaphragm element as a flow body in a flow duct defined by the housing wherein the first portion connection surface comprises a first abutting surface section abutting against a second abutting surface section of the second portion connection surface with said first housing half combined with said second housing half and a connection in substance area is provided outside of the mounting gap and outside of the abutting surface section with said first housing half combined with said second housing half and at least one of the first housing half and the second housing half is laser transparent in the connection in substance area, wherein the process comprises the following steps: joining the two housing halves such that the diaphragm element is enclosed by the two housing halves in the mounting gap and the two housing halves abut against one another outside of the mounting gap in the area of the abutting surface section; and combining by connection in substance of the housing halves by laser welding outside of the mounting gap and outside of the abutting surface sections.

9. A process in accordance with claim 8, wherein the process step of joining the two housing halves comprises the partial step of the insertion of the projection into the recess and correspondingly the joining of the two housing halves takes place such that the diaphragm element is enclosed by the two housing halves in the mounting gap, and the two housing halves abut against one another outside of the mounting gap in the area of the abutting surface sections and the projection meshes with the recess.

10. A process in accordance with claim 9, wherein the two housing halves are connected in substance to one another by the projection meshing with the recess being connected to the recess by laser welding.

11. A process in accordance with claim 10, wherein for the laser welding a laser beam is expanded in a cone envelope by means of a first optical device and is deflected by means of a second optical device in direction of a connection in substance area enclosed by the two loosely joined housing halves, and wherein the radially extending projection is connected in substance by laser welding to the radially extending recess by means of the laser beam at the same time along an entire perimeter thereof.

12. A process in accordance with claim 11, wherein the joined housing halves are fixed in an axial direction aligned collinearly with a central longitudinal axis of a bundle of beams with an expansion of the laser beam, wherein the housing half facing away from a source of the laser beam in the beam path is fixed in the axial direction, and the housing half facing towards the source of the laser beam in the beam path is fixed by means of a laser-transparent plate on the other housing half, wherein a plane of the laser-transparent plate is at right angles to a central longitudinal axis of the two housing halves, which central longitudinal axis runs through the source of the laser beam.

13. A process in accordance with claim 8, wherein the laser beam penetrates the laser-transparent housing half during the laser welding and the other housing half absorbs the energy of the laser beam.

14. A flow sensor according to claim 7 in combination with a medical device part to provide a medical device with the at least one flow tube.

15. A flow sensor in accordance with claim 7, wherein one of the housing halves has at least one connection surface projection and the other housing half has at least one connection surface recess configured to receive the projection, and wherein the housing halves are combined with one another by connection in substance by means of the projection and the recess by surfaces or surface sections of the projection and of the recess coming into contact with one another during the joining of the housing halves forming the connection in substance area.

16. A flow sensor in accordance with claim 15, wherein the mounting gap, the abutting surface sections as well as the projection and the recess are arranged on the connection surfaces in a radial direction such that the mounting gap is located in front of the abutting surface sections in relation to the abutting surface sections and the projection and the recess are located behind the abutting surface sections in relation to the abutting surface sections.

17. A flow sensor in accordance with claim 15, wherein the projection and the recess are connected to one another by connection in substance in the area of a radially outermost common contact surface.

18. A flow sensor in accordance with claim 15, wherein the at least one projection is a radially extending projection and the at least one recess is a radially extending recess.

19. A flow sensor in accordance with claim 1, wherein the two housing halves are connected by connection in substance by means of a laser beam expanded onto a cone envelope active along an entire perimeter thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In the drawings:

[0038] FIG. 1 is a perspective exploded view showing a flow tube with two housing halves forming a housing of the flow tube and with a diaphragm element between the housing halves;

[0039] FIG. 2 is a sectional view through the housing halves; and

[0040] FIG. 3 is a schematic view of an arrangement for manufacturing a flow tube according to FIG. 1 and FIG. 2.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0041] Referring to the drawings, the view in FIG. 1 shows a flow tube 10 and a flow sensor formed with the flow tube 10 as a key component in a schematically simplified manner. The flow tube 10 comprises in a manner that is basically known per se two housing halves 12, 14, especially a first housing half 12 and a second housing half 14 as well as a diaphragm element 16 enclosed between the two housing halves 12, 14. Each housing half 12, 14 has a flange area and a connection surface 20, 22 as a surface of the flange area. The connection surfaces 20, 22 of the two housing halves 12, 14 together form a housing 12, 14 of the flow tube 10 and define a flow duct 24. In a manner basically known per se, the flow tube 10 is part of a pipeline 26, 28, especially of a pipeline 26, 28 functioning as a gas line, for example, of a gas line of a ventilator or of another medical device. The pipeline 26, 28 adjoins the flow duct 24 upstream and downstream of the flow tube 10 in the interior of the flow tube 10.

[0042] The view in FIG. 2 shows a section through the flange areas of the two housing halves 12, 14 of the flow tube 10, which housing halves are combined (joined) with one another, with a sectional plane obliquely to the longitudinal axis of the flow tube 10. The surfaces of the flange area of the two housing halves 12, 14, which surfaces face one another and function as connection surfaces, define a mounting gap 30 for the diaphragm element 16 and enclose the diaphragm element 16 in this mounting gap 30 and by means of this mounting gap 30.

[0043] The view in FIG. 2 already shows a structuring of the connection surfaces 20, 22 according to a special embodiment of the innovation being proposed here. Generally and regardless of the special embodiment shown, provisions are made in case of the concrete flow tube 10 for the connection surfaces 20, 22 of the two housing halves 12, 14 combined with one another to abut against one another in some sections outside of the mounting gap 30 and for each connection surface 20, 22 to comprise an abutting surface section 32, 34 in this respect and for the housing halves 12, 14 to be combined with one another by connection in substance in at least one connection in substance area 36 outside of the mounting gap 30 and outside of the abutting surface sections 32, 34.

[0044] In the embodiment being shown, a contact surface between at least one projection 40 arising on the connection surface 20 of the first housing half 12 and at least one recess 42 in the connection surface 22 of the second housing half 14, which recess is intended for receiving the projection 40, functions as a connection in substance area 36. It should be expressly pointed out here that this special location of the connection in substance area 36 belongs to the special embodiment shown and that generally, on the one hand, the distance in space of the connection in substance area 36 from the abutting surface sections 32, 34 and, on the other hand, the distance in space of the connection in substance area 36 from the mounting gap 30 are of special importance.

[0045] Instead of at least one projection 40 and at least one recess 42 intended for receiving it, a plurality of such projections 40 and recesses 42, especially projections 40 and recesses 42 arranged along a circular line, preferably projections 40 and recesses 42, which are arranged equidistantly along such a circular line, i.e., to some extent pins (projections 40) on the connection surface 20 of the first housing half 12 and blind holes (recesses 42) in the connection surface 22 of the second housing half 14, come into consideration.

[0046] In the embodiment being shown, the recess 42 is an annular groove 42 extending in the connection surface 22 of the second housing half 14. The projection 40 is an annular spring 40 extending on the connection surface 20 of the first housing half 12. The annular groove 42 is intended for the receiving of the annular spring 40 and corresponding positions on the connection surfaces 20, 22 of the two housing halves 12, 14 guarantee the ability of the annular spring 40 to be inserted into the annular groove 42, wherein at least one lateral surface of the annular spring 40 comes into contact with a lateral surface of the annular groove 42, such that the lateral surfaces in question abut against one another. The lateral surfaces of the annular spring 40 and the annular groove 42 abutting against one another form the location of the connection in substance area 36 and in the embodiment shown the lateral surfaces of the annular spring 40 and the annular groove 42 abutting against one another in the radial direction are at a maximum distance from the mounting gap 30.

[0047] Starting from a central longitudinal axis of the housing halves 12, 14 (from a central longitudinal axis through the flow duct 24 defined by the housing halves 12, 14), the sequence of the mentioned structural details of the flow tube 10 is as follows: Mounting gap 30 (inside), abutting surface sections 32, 34 (center), projection 40/recess 42 or annular spring 40/annular groove 42 (outside). There is a distance between each of these structural details in the embodiment shown, i.e., the structural details following one another in the radial direction do not directly border on each other. The connection in substance of the two housing halves 12, 14 takes place in the area of the radially outermost structural details mentioned above, especially in the area of the radially outermost common contact surface of these structural details, i.e., of the radially outermost common contact surface of the projection 40 and the recess 42 or of the annular spring 40 and the annular groove 42.

[0048] When the two housing halves 12, 14 are joined, the connection surfaces 20, 22 come into contact in the area of the abutting surface sections 32, 34 and abut against one another there. This guarantees a defined width of the mounting gap 30. A connection in substance of the two housing halves 12, 14 in the connection in substance area 36, which is spaced apart from the mounting gap 30, on the one hand, and from the abutting surface sections 32, 34, on the other hand, guarantees the defined width of the mounting gap 30 even during and after establishing the connection in substance. This defined width of the mounting gap 30 guarantees either a defined clamping or a defined loose mounting of the diaphragm element 16 by the two housing halves 12, 14 and thus a defined and reproducible opening characteristic of the diaphragm element 16 in the flow duct 24 as a function of the flow direction in the flow duct 24. Consequently, the flow tube 10 can be used bidirectionally and thus comes into consideration for a bidirectional flow sensor.

[0049] The view in FIG. 3 shows in a schematically simplified manner a top view of an arrangement for manufacturing a flow tube 10 according to FIG. 2, namely an arrangement for the connection in substance of the two housing halves 12, 14 of the flow tube 10.

[0050] The connection in substance of the two housing halves 12, 14 takes place by means of the joining process offered by laser welding by means of the arrangement according to FIG. 3. Correspondingly, the view in FIG. 3 shows a laser beam 50 and a bundle of beams 52 of the laser beam 50. The bundle of beams 52 is generated from the laser beam 50 by means of a first optical device 54, especially by means of a processing head 54 (axicon for ring generation and focusing lens) with collimation lens, which expands the laser beam 50 in a cone envelope. The bundle of beams 52 resulting as a result of the expansion is deflected onto the two housing halves 12, 14 by means of a second optical device 56, especially by means of a ring mirror 56 for simultaneous ring welding.

[0051] In case of a ring mirror 56, the reflecting surface 58 is for this purpose sloped against the plane of the ring mirror 56, for example, by 55. By means of such a surface 58, the beams of the bundle of beams 52 impacting the ring mirror 56 are deflected in the direction towards the center of the ring mirror 56 and impact the two housing halves 12, 14 in the case of a pair of housing halves 12, 14 arranged and loosely joined there.

[0052] A ring mirror 56 as a second optical device 56 is oriented within the arrangement such that a plane E defined by the ring mirror 56 is at right angles to the (not expanded) laser beam 50 or is at right angles to a central longitudinal axis A of the cone envelope-shaped bundle of beams 52. The two initially loosely joined housing halves 12, 14 are located in the center of the ring mirror 56 in an orientation, in which a longitudinal axis B of the housing halves 12, 14 (a central longitudinal axis through the flow duct 24) coincides with the central longitudinal axis A of the cone envelope-shaped bundle of beams 52. The individual beams of the bundle of beams 52 impact the plane E of the ring mirror 56 as a function of the distance between the processing head 54 and the ring mirror 56 at an angle of less than 90 up to asymptotically close to 90. The reflecting surface 58 of the ring mirror 56 is sloped against the plane of the ring mirror 56, for example, by an angle of 55 or an angle in the range of 55. When for the sake of simpler conditions, it is assumed that the beams of the bundle of beams 52 impact the plane of the ring mirror 56 at a right angle, a deflection of the beams of the bundle of beams 52 precisely in the plane of the ring mirror 56 and in the direction towards the center of the ring mirror 56 takes place in case of a reflecting surface 58 of the ring mirror 56, which reflecting surface is sloped against the plane of the ring mirror 56 by an angle of 45. In the case of beams of the bundle of beams 52 impacting the plane of the ring mirror 56 at an angle of less 90 and in case of a reflecting surface 58 sloped against the plane of the ring mirror 56 at an angle of 45, the beams falling on the ring mirror 56 are not accurately deflected into the plane of the ring mirror 56. A deflection accurately into the plane of the ring mirror 56 can be achieved by a corresponding adaptation of the slope of the reflecting surface 58 of the ring mirror 56, for example, a slope of 55. This is optionally possible, but not absolutely necessary. It is important that the two housing halves 12, 14 are placed in the center of the ring mirror 56 such that the connection in substance area 36 is located in the beam path of the bundle of beams 52 deflected by the surface 58 of the ring mirror 56, as this is shown in the view in FIG. 3. The individual beams of the bundle of beams 52 then impact one of the housing halves 12, 14 along the perimeter thereof. The connection in substance area 36 is located in the interior of the initially loosely joined housing halves 12, 14. The housing half 14 located on the outside (in the direction towards the ring mirror 56) with the recess 42, especially with a recess 42 in the form of an annular groove 42, shadows the connection in substance area 36 against the beam path. So that the laser beams can reach the connection in substance area 36 (FIG. 2), the shadowing housing half 12 is made of a transparent material, especially of a laser-transparent plastic and thus has a laser-transparent configuration or has a laser-transparent configuration at least in the area of the beam path. The other housing half 14 absorbs the energy of the laser beam 50 and is made of a corresponding material, especially of a corresponding plastic. Which of the two housing halves 12, 14 is the shadowing housing half 12, 14 which is located on the outside and consequently has an entirely or partially laser-transparent configuration depends on the configuration of the housing halves 12, 14 of the flow tube 10. Because of the absorption of the laser energy by the housing half 14, which is not laser transparent or is at least not laser transparent in the connection in substance area 36, a circular weld seam is formed in the connection in substance area 36. In this case, the housing half 14, which is not laser transparent or at least not laser transparent in the connection in substance area 36 is plasticized in the connection in substance area 36 by the energy of the laser beam 50. Due to heat conduction, the material of the other housing half 12 is also plasticized in the connection in substance area 36. A connection in substance and positive-locking connection as well as gastight connection between the housing halves 12, 14 is thus formed in the connection in substance area 36.

[0053] According to FIG. 3, in a preferred embodiment of the arrangement, a laser-transparent, plane-parallel plate 62, especially a plane-parallel glass plate, belongs to the arrangement intended for the manufacture of a flow tube 10, namely for the connection in substance of the two housing halves 12, 14. Such a laser-transparent plate 62 fixes the two housing halves 12, 14 relative to one another and holds the two at first loosely joined housing halves 12, 14 for connection in substance during the connection in substance. For this purpose, the housing half 14 facing away in the beam path (the housing half 14 at the furthest distance from the source of the laser beam 50 along the beam path) is fixed, for example, clamped or placed onto a pin protruding into the interior of the housing half 14 at the free end of the housing half 14 or is inserted into a sleeve extending around the free end of the housing half 14. At any rate, this housing half 14, which is designated below briefly as housing half 14 facing away in the beam path, is fixed in relation to the ring mirror 56 in the axial and radial directions, wherein the fixing in the radial direction means that a central longitudinal axis B of this housing half 14 coincides with a central longitudinal axis A of the bundle of beams 52 impacting the ring mirror 56 (the housing half 14 is located in the radial direction in the center of the ring mirror 56). The other housing half 12, which is designated below as the housing half 12 facing toward the beam path, can at first be loosely placed onto such a fixed housing half 14 facing away in the beam path. Here, the projection 40 and the recess 42, especially the annular spring 40 and the annular groove 42, are meshed with one another. The laser-transparent plate 62 is provided for fixing this housing half 12 facing toward the beam path. This laser-transparent plate 62 is in contact with the housing half 12 facing toward the beam path at the free end thereof. The central longitudinal axes B of the two housing halves 12, 14 are collinear and collinear with the central longitudinal axis A of the bundle of beams 52 (thus also collinear with the laser beam 50). The central longitudinal axes A, B are at right angles to a plane E of the ring mirror 56. The boundary line of the free end of the housing half 12 facing toward the beam path is located in a plane parallel to the plane E of the ring mirror 56. A plane F of the laser-transparent plate 62 lying on or in contact with the boundary line of the free end of the housing half 12 facing toward the beam path is thus likewise parallel to the plane E of the ring mirror 56 and a central longitudinal axis A of the bundle of beams 52 is also at right angles to the plane F of the laser-transparent plate 62. All beams of the bundle of beams 52 experience the same refraction due to the laser-transparent plate 62 because of the homogeneous material and because of the arrangement in the bundle of beams 52. The laser-transparent plate 62 thus functions as an advantageous device for fixing the housing half 12 (the housing half 12 facing toward the beam path) at first loosely combined with the other housing half 14 (the housing half 14 facing away in the beam path).

[0054] The laser-transparent plate 62 is displaceable in a movable manner obliquely to its plane F for the purpose of such a fixing optionally in a housing 64 of the arrangement. For welding together two housing halves 12, 14, the housing halves 12, 14 are placed in the area of the ring mirror 56 in the manner described above. Optionally, at least the housing half 14 facing away in the beam path is in this case likewise held by means of the housing 64 or this housing half 14 is held by means of a fixing device (not shown), wherein the housing 64 is fixed relative to the fixing device. Before the housing halves 12, 14 are placed in the area of the ring mirror 56, the laser-transparent plate 62 is thus displaced until the housing half 12 facing toward the beam path is fixed by means of the laser-transparent plate 62. A guide comprised by the housing 64, which allows the translatory moving operations described, is provided for moving the laser-transparent plate 62.

[0055] Finally, individual prominent aspects of the description submitted here can be summarized briefly as follows: Proposed are a flow tube 10 and a process for manufacturing a concrete flow tube 10. The flow tube 10 comprises an at least two-part housing with a first and a second housing half 12, 14, wherein each housing half 12, 14 has a connection surface 20, 22 intended for the combination with the respective other housing half 12, 14. The connection surfaces 20, 22 of the two housing halves 12, 14 combined with one another enclose a mounting gap 30 for a diaphragm element 16. The diaphragm element 16 functions as a flow body in a flow duct 24 defined by the housing 12, 14. The connection surfaces 20, 22 of the two housing halves 12, 14 combined with one another abut against one another in some sections outside of the mounting gap 30 (at a distance in space from the mounting gap 30). In this respect, each connection surface 20, 22 comprises an abutting surface section 32, 34 located at a spaced location from the mounting gap 30. The two housing halves 12, 14 are combined with one another by connection in substance, namely by laser welding, outside of the mounting gap 30 (at a distance in space from the mounting gap 30) and outside of the abutting surface sections 32, 34 (at a distance in space from the abutting surface sections 32, 34).

[0056] While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.