Vaporizer

Abstract

A vaporizer for an exhaust system of an internal combustion engine has a vaporizer tube and a holding sleeve in which the vaporizer tube is inserted. A clamping sleeve sits on the vaporizer tube. The vaporizer tube includes two circumferentially surrounding clamping surfaces which protrude in a radial direction and cooperate with the holding sleeve and the clamping sleeve such that the clamping surfaces are clamped between the holding sleeve and the clamping sleeve by an axial clamping force to be gastight. At least one of the holding sleeve and the clamping sleeve includes a surrounding sealing edge which rests against the respective clamping surface via a line contact and forms an annular sealing seat. The vaporizer further includes a device preventing relative rotation between the holding sleeve and the vaporizer tube. A heater of the vaporizer is attached to the vaporizer tube using a resistance welding method.

Claims

1. A vaporizer for an exhaust system of an internal combustion engine, comprising: a vaporizer tube; a holding sleeve in which the vaporizer tube is inserted, wherein the holding sleeve is associated with an exhaust pipe, and wherein a form-fitting anti-rotation device is provided which prevents the vaporizer tube and the holding sleeve from rotating relative to each other; and a clamping sleeve which sits on the vaporizer tube wherein the vaporizer tube includes two circumferentially surrounding clamping surfaces which protrude in a radial direction and cooperate with the holding sleeve and the clamping sleeve such that the clamping surfaces are clamped between the holding sleeve and the clamping sleeve by an axial clamping force to be gastight, and wherein at least one of the holding sleeve and the clamping sleeve includes a surrounding sealing edge which rests against the respective clamping surface via line contact and forms an annular sealing seat.

2. The vaporizer according to claim 1, wherein the sealing edge has a sharp edge that digs into the clamping surface for sealing.

3. The vaporizer according to claim 1, wherein the clamping surfaces are elastically movable relative to each other in an axial direction.

4. The vaporizer according to claim 1, wherein the two clamping surfaces extend at different angles in relation to the radial direction.

5. The vaporizer according to claim 1, wherein at least one of the clamping sleeve and the holding sleeve includes a conical tensioning surface.

6. The vaporizer according to claim 1, wherein the holding sleeve includes an internal thread and the clamping sleeve includes an external thread complementary thereto.

7. The vaporizer according to claim 1, wherein the anti-rotation device is formed by a flat portion of an otherwise circular cross-section of the vaporizer tube.

8. The vaporizer according to claim 1, wherein the anti-rotation device includes a plate-shaped retaining part having a section that is firmly connected with one of the vaporizer tube and the holding sleeve, and having a second section that engages in a recess on one of the holding sleeve and the vaporizer tube.

9. The vaporizer according to claim 1, wherein the holding sleeve has a first end and a second end with an internal bore extending from the first end to the second end to define a center axis, and wherein the vaporizer tube is received within the internal bore such that the vaporizer tube extends axially beyond the first and second ends of the holding sleeve.

10. The vaporizer according to claim 1, wherein the holding sleeve has an outer surface that is configured to be fixed to the exhaust pipe and an inner surface that defines a center axis.

11. The vaporizer according to claim 10, wherein the two circumferentially surrounding clamping surfaces comprise a first clamping surface extending in a first plane that is substantially perpendicular to the central axis and a second clamping surface extending at an obtuse angle relative to the center axis, and wherein the second clamping surface cooperates with the clamping sleeve.

12. The vaporizer according to claim 11, wherein the sealing edge has a sharp edge that digs into the first clamping surface.

13. A vaporizer for an exhaust system of an internal combustion engine, comprising: a vaporizer tube; a holding sleeve in which the vaporizer tube is inserted; and a clamping sleeve which sits on the vaporizer tube, wherein at least one of the clamping sleeve and the holding sleeve includes a conical tensioning surface, and wherein the vaporizer tube includes two circumferentially surrounding clamping surfaces which protrude in a radial direction and cooperate with the holding sleeve and the clamping sleeve such that the clamping surfaces are clamped between the holding sleeve and the clamping sleeve by an axial clamping force to be gastight, and wherein at least one of the holding sleeve and the clamping sleeve includes a surrounding sealing edge which rests against the respective clamping surface via line contact and forms an annular sealing seat, and wherein the holding sleeve is inserted in an exhaust pipe and one of the clamping surfaces forms an inclined clamping surface, and the conical tensioning surface and the inclined clamping surface are arranged such that cones open toward an inside of the exhaust pipe.

14. The vaporizer according to claim 13, wherein the holding sleeve includes an internal thread and the clamping sleeve includes an external thread complementary thereto, and wherein the angles of inclination of thread flanks of the internal thread and of the external thread and angles of inclination of the conical tensioning surface and of the inclined clamping surface, each viewed in relation to a center axis of the holding sleeve, are the same.

15. A method of manufacturing a vaporizer, in particular a vaporizer comprising: a vaporizer tube; a holding sleeve in which the vaporizer tube is inserted; a clamping sleeve which sits on the vaporizer tube wherein the vaporizer tube includes two circumferentially surrounding clamping surfaces which protrude in a radial direction and cooperate with the holding sleeve and the clamping sleeve such that the clamping surfaces are clamped between the holding sleeve and the clamping sleeve by an axial clamping force to be gastight, and wherein at least one of the holding sleeve and the clamping sleeve includes a surrounding sealing edge which rests against the respective clamping surface via line contact and forms an annular sealing seat and wherein a heater is inserted in the vaporizer tube, and wherein an outer surface of a holder of the heater and an inner surface of the vaporizer tube are connected with each other by a resistance welding method.

16. The method according to claim 15, wherein an outer surface of a holder of the heater and an inner surface of the vaporizer tube are connected with each other by capacitor discharge welding.

17. A vaporizer for an exhaust system of an internal combustion engine, comprising: a vaporizer tube that includes an end section which is flared in a funnel shape and in which a heater is inserted, the heater has a holder with a cylindrical section and an outer edge of the cylindrical section is welded to an inside of the end section; a holding sleeve in which the vaporizer tube is inserted; and a clamping sleeve which sits on the vaporizer tube wherein the vaporizer tube includes two circumferentially surrounding clamping surfaces which protrude in a radial direction and cooperate with the holding sleeve and the clamping sleeve such that the clamping surfaces are clamped between the holding sleeve and the clamping sleeve by an axial clamping force to be gastight, and wherein at least one of the holding sleeve and the clamping sleeve includes a surrounding sealing edge which rests against the respective clamping surface via line contact and forms an annular sealing seat.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be described in more detail below on the basis of several embodiments and with reference to the accompanying drawings, in which:

(2) FIG. 1 shows a schematic exploded side view of a vaporizer according to the invention;

(3) FIG. 2 shows a schematic partial sectional view of a portion of a vaporizer according to the invention;

(4) FIG. 3 shows a schematic sectional view of a portion of the vaporizer according to the invention, showing the attachment of the vaporizer tube;

(5) FIG. 4 shows a schematic perspective view of a holding sleeve with an anti-rotation device according to a first variant for a vaporizer according to the invention;

(6) FIG. 5 shows a schematic sectional view of a vaporizer according to the invention, with an anti-rotation device according to a first variant;

(7) FIGS. 6 to 9 show various schematic perspective views of a vaporizer according to the invention, with an anti-rotation device according to a second embodiment;

(8) FIG. 10 shows a schematic side view of a vaporizer according to the invention, with an associated heater prior to attachment of the heating means;

(9) FIG. 11 shows a schematic perspective view, partly in section, of the assembly of FIG. 10; and

(10) FIG. 12 shows a schematic partial sectional view of a portion of a vaporizer according to a further embodiment of the invention.

DETAILED DESCRIPTION

(11) FIGS. 1 and 2 show a vaporizer 10 which in this example includes a vaporizer tube 12 bent at right angles, which is surrounded in the circumferential direction by a clamping structure in the form of a holding sleeve 14 and a clamping sleeve 16 (see FIG. 3).

(12) The vaporizer tube 12 need not be bent as illustrated here. It could also be completely straight or be designed with a curvature profile different from the one shown.

(13) A heater 18, here shown separately from the vaporizer tube 12, is attached to one end of the vaporizer tube, also referred to as the upper end here. In this example, the heater 18 is a known glow plug. At its other end, the vaporizer tube 12 includes an outlet 20 for the liquid vaporized by the heater 18.

(14) The liquid to be vaporized, for example liquid fuel as is also used for the internal combustion engine in the exhaust system of which the vaporizer 10 is employed, is introduced into the vaporizer tube 12 through a supply pipe 22 which is connected to an opening 24 in the vaporizer tube 12 (see FIG. 2), where the liquid is heated by the heater 18 and vaporized. The vaporized liquid exits the vaporizer tube 12 through the outlet 20 and thus reaches the exhaust gas flow.

(15) FIG. 3 shows the clamping device with the holding sleeve 14 and the clamping sleeve 16 in detail.

(16) Two clamping surfaces 26, 28 are formed on the vaporizer tube 12, at the level of the holding sleeve 14 and the clamping sleeve 16.

(17) In this example, the first clamping surface 26 is in the form of an annular surface which is oriented substantially in a plane perpendicular to the axial direction A of the vaporizer tube 12.

(18) The second clamping surface 28 (in FIG. 3 the upper clamping surface), on the other hand, has the shape of a truncated cone. The internal angle defining the cone lies on the side facing away from the first clamping surface on the center axis of the vaporizer tube 12 and opens toward the interior of the exhaust pipe 30. As seen in section, the second clamping surface 28 is oriented here at an angle of between 45 degrees and 60 degrees to the axial direction A. But the angle may, of course, also be selected differently.

(19) The two clamping surfaces 26, 28 are produced by an axial upsetting along with a simultaneous radial widening of the vaporizer tube 12. Under the action of the axial force, the wall of the vaporizer tube 12 bulges radially outward, accompanied by the formation of the two clamping surfaces 26, 28, partly extending flatly, on the outside of the vaporizer tube 12.

(20) The deformation of the vaporizer tube 12 is performed such that those wall sections of the inside of the vaporizer tube 12 which correspond to the clamping surfaces 26, 28 do not lie on top of each other, but have an axial distance.

(21) The wall thickness of the vaporizer tube 12 is selected such that the two clamping surfaces 26, 28 can be elastically moved relative to each other axially when the clamped connection is produced. However, the wall thickness of the vaporizer tube 12 is preferably greater than 0.9 mm, so that the vaporizer tube 12 has a sufficient stability by itself, without any further aids having to be provided for stabilization in particular in the area of the clamped connection. Above all, no further inner or outer tube is provided. In the examples described here, the vaporizer 10 consists of the components shown in the Figures.

(22) The holding sleeve 14 is welded into a wall of an exhaust pipe 30 which is part of the exhaust system of the internal combustion engine. As a result, the holding sleeve 14 is fastened to be stationary.

(23) The vaporizer tube 12 protrudes through the holding sleeve 14 such that its outlet 20 opens into the interior of the exhaust pipe 30.

(24) The holding sleeve 14 has an annular seat 32 which, in the assembled state, is arranged immediately below the first clamping surface 26 and here rests against the outer wall of the vaporizer tube 12. On its side facing the clamping surface 26, this seat 32 has a surrounding, sharp sealing edge 34 which is arranged radially at the level of the clamping surface 26. Sharp means here that the sealing edge 34 is configured without the otherwise usual edge radii or has a very small edge radius, so that a high contact surface pressure is obtained upon contact with the clamping surface.

(25) In FIG. 3, the clamping sleeve 16 is positioned above the upper clamping surface 28 and includes a conical tensioning surface 36 which is arranged at its lower end in FIG. 3 and which, in the assembled condition, rests against the clamping surface 28. In the completely tightened condition of the clamped connection, the inclinations of the conical tensioning surface 36 and the clamping surface 28 are substantially the same.

(26) The two clamping surfaces 26, 28 therefore lie between the sealing edge 34 of the seat 32 of the holding sleeve 14 and the conical tensioning surface 36 of the clamping sleeve 16.

(27) The holding sleeve 14 includes an internal thread 38 while the clamping sleeve 16, which is in the form of a hollow bolt here, has an external thread 40.

(28) The angles of inclination of the thread flanks of the internal thread 38 and of the external thread 40 and the angles of inclination of the clamping surface 28 and of the conical tensioning surface 36, each viewed relative to the center axis, may be selected to be the same. In this example, however, the clamping surface 28 has an angle of inclination of 45 degrees, while the threads 38, 40 have an angle of inclination of 60 degrees.

(29) To attach the vaporizer tube 12, it is inserted with the clamping sleeve 16 placed thereon into the holding sleeve 14, which preferably has previously been attached to the exhaust pipe 30, so that the lower clamping surface 26 rests on the sealing edge 34 of the holding sleeve 14. Then the clamping sleeve 16 is threaded into the thread 38 of the holding sleeve 14, the conical tensioning surface 36 coming into contact with the upper clamping surface 28, so that the two clamping surfaces 26, 28 are firmly clamped between the holding sleeve 14 and the clamping sleeve 16. In this process, the two clamping surfaces 26, 28 are slightly compressed in the axial direction A.

(30) In addition, since the sealing edge 34 is made with a sharp edge, it cuts into the lower clamping surface 26 along a surrounding line, so that a gastight connection is produced here between the holding sleeve 14 and the clamping surface 26 and thus the vaporizer tube 12 by the sealing edge 34 penetrating the material of the clamping surface 26. As a result, there is a gastight connection between the vaporizer tube 12 and the exhaust pipe 30.

(31) The vaporizer 10 has an anti-rotation device provided thereon which, in the installed state, prevents the vaporizer tube 12 from rotating in relation to the exhaust pipe 30.

(32) In the variant shown in FIGS. 4 and 5, the otherwise circular cross-section of the vaporizer tube 12 is deformed at one point of the circumference below the first clamping surface 26 so as to form a flat portion 42. In this example, the flat portion extends approximately over an inscribed angle (sector) of 60 degrees.

(33) Below the sealing edge 34, the holding sleeve 14 includes a projection 44 which is directed radially inwards and the contour of which matches that of the flat portion 42 in the vaporizer tube.

(34) When the vaporizer tube 12 is inserted into the holding sleeve 14 such that the flat portion 42 rests against the projection 44, this results in a form fit which prevents the vaporizer tube 12 from rotating in relation to the holding sleeve 14 and thus in relation to the exhaust pipe 30. Moreover, the combination of the flat portion 42 and the projection 44 makes sure that the vaporizer tube 12 can only be installed in exactly this single predefined position with respect to a holding sleeve 14 that is already attached in the exhaust pipe 30.

(35) FIGS. 6 to 9 show a second variant of an anti-rotation device.

(36) In this case, provision is made for a retaining part 50 which is in the form of a partly bent, stamped sheet metal part and is located outside of the vaporizer tube 12 and the holding sleeve 14, and which is separate from these components. At the lower end in FIGS. 6 and 7, a first section 52 of the retaining part 50 is shaped into a flattened web which engages in an only slightly wider recess 54 in the outer circumference of the holding sleeve 14. This produces a form-fitting push-in connection.

(37) The end of the retaining part 50 which is the upper end in FIGS. 6 and 7 constitutes a second section 56 in the form of a plate-shaped widening which here rests against the outer wall of the vaporizer tube 12 in the region of the curvature thereof and is firmly connected, for example welded, to the outer wall.

(38) The retaining part 50 is slightly curved in front of the second section 56, so that a mechanical prestress exists between the first section 52 and the second section 56, as a result of which the first section 52 is fixed in place in the recess 54.

(39) In the examples shown here, the heater 18 and the vaporizer tube 12 are attached to one another by a resistance welding method or resistance pressure welding method, in particular by capacitor discharge or pulse welding or annular projection welding.

(40) At one end, the heater 18 has a metallic holder 60 which has a rod-shaped heating source 66 inserted therein and attached thereto. The heating source 66 is a conventional glow plug here, which is closed to the outside by a glow tube, for example. Any additional housing for the heating source is not provided. The free end of the heating source 66 projects from the holder 60. At its end facing the free end of the heating source 66, the holder 60 includes a cylindrical section 62, which has a larger diameter than the heating source 66.

(41) The upper end of the vaporizer tube 12 is conically flared, as is apparent in particular from FIGS. 2, 9, 10 and 11. The diameter of the vaporizer tube 12 at the start of the end section 64 flared in a funnel shape is smaller than the diameter of the cylindrical section 62, whereas the upper end of the flared end section 64 has a larger diameter than the cylindrical section 62. Consequently, the heating means 18 is automatically centered when it is inserted into the vaporizer tube 12, and a line contact is produced between the sharp edge of the cylindrical section 62 and the inner wall of the vaporizer tube 12. This contact line encircling the entire circumference is made use of for the capacitor discharge welding in order to produce a welded joint at this location.

(42) When the heater has been attached, the heating source 66 projects into the vaporizer tube 12 and is spaced away from the inside of the vaporizer tube 12 over its entire circumference.

(43) FIG. 12 shows a variant in which the holder 60 of the heater 18 includes a conical section 64 whereas, in return, the edge of the opening of the vaporizer tube 12 forms a sharp, circular ring shaped edge 62. In this case, too, a self-centering of the heater 18 is effected upon insertion into the open end of the vaporizer tube 12, so that a circumferentially encircling line contact is produced between the vaporizer tube 12 and the holder 60. This geometry is also suited for a connection by capacitor discharge welding.

(44) Both the vaporizer tube 12 and the holder 60 of the heater 18 are made from metal, so that a good electrical conductivity for capacitor discharge welding is given.

(45) The principle set out above of a sharp circular edge and a conically shaped contact surface to produce a geometry that is well suited for capacitor discharge welding can also be applied to the attachment of the supply pipe 22 in the opening 24 in the vaporizer tube 12. The edge of the opening 24 is preferably beveled here, and the end of the supply pipe 22 has a circular ring shaped edge.

(46) All of the features described herein may be combined with or exchanged for each other at the discretion of a person skilled in the art.

(47) The various aspects of the invention, more specifically the attachment of the vaporizer 10 to the vaporizer tube 12, the holding sleeve 14 and the clamping sleeve 16 by a clamped connection using clamping surfaces 26, 28, the provision of an anti-rotation device for the vaporizer tube 12, and the attachment of the heater 18 to the vaporizer tube 12 by capacitor discharge welding may be realized both separately on any desired vaporizers or may also be employed jointly on one vaporizer.

(48) Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this disclosure. For that reason, the following claims should be studied to determine the true scope and content of this disclosure.