Internally cooled valve having a valve bottom, and method for the production thereof

Abstract

A method for manufacturing an internally cooled valve (2), includes providing a valve body (4) having a valve stem (6) that ends in a valve head (8). The valve body (4) has a cavity (10) that is open toward the valve head (8) and with a valve base element (12) by friction welding the valve base element (12) to the valve head (8). The valve bottom element (12) is preferably a sintered component.

Claims

1. A method for manufacturing an internally cooled valve, comprising providing a valve body having a valve stem that ends in a valve head, wherein the valve body has a cavity that is open toward the valve head, providing a valve base element, and closing the cavity with the valve base element by friction welding the valve base element to the valve head, wherein the valve base element and/or the valve body have/has an engagement structure with which the valve base element and/or the valve body are/is centrally clamped, and/or a torque is transmitted to the valve base element and/or to the valve body, and wherein the valve base element is fabricated as a green compact or brown compact by metal powder injection molding and sintered and wherein the valve base element is provided with a cooling rib structure and/or flow-influencing structure on a surface facing the cavity.

2. The method according to claim 1, wherein the friction welding is carried out as inductive friction welding.

3. The method according to claim 1, further comprising at least partially filling the cavity with a coolant before the cavity is closed by friction welding.

4. The method according to claim 3, wherein the coolant is selected from sodium or a sodium-containing coolant.

5. The method according to claim 1, wherein the engagement structure is subsequently removed and/or ablated.

6. The method according to claim 1, wherein the valve base element and the valve body have a welding surface contour, which in the friction welding operation produces a weld expulsion in the cavity in a desired shape of a cooling rib.

7. The method according to claim 6, wherein an outer portion of the weld expulsion is subsequently removed.

8. An internally cooled valve having a valve body that includes a valve head and a valve stem, the valve body having a cavity extending into the valve head the cavity being closed by a valve base that is joined to the valve head by friction welding, the valve base element and/or the valve body have/has an engagement structure with which the valve base element and/or the valve body may be centrally clamped, and a torque may be transmitted to the valve base element and/or to the valve body, the valve base element being provided with a cooling rib structure and/or flow-influencing on a surface facing the cavity, and wherein the valve base element is produced by sintering from a valve base element green compact or brown compact valve base element that is produced by metal powder injection molding.

9. The internally cooled valve according to claim 8, including a friction weld expulsion on an inner side of the cavity having the shape of a cooling rib which allows improved heat transfer from the valve head to the coolant.

10. The internally cooled valve according to one of claim 8, wherein the valve base element is produced by sintering.

Description

THE DRAWINGS

(1) The invention is explained in greater detail below with reference to schematic figures.

(2) FIGS. 1 and 2 show a perspective view of a valve base element.

(3) FIGS. 3 and 4 respectively illustrate a perspective view and a sectional view of a valve body.

(4) FIGS. 5 and 6 respectively show a beginning and an end of a friction welding operation according to the invention.

(5) FIGS. 7 and 8 respectively illustrate a partial sectional view and a partial perspective view of a valve according to the invention.

(6) FIG. 9 illustrates a valve base element that is mounted on a friction welding mandrel.

DETAILED DESCRIPTION

(7) Identical or similar reference numerals are used in the description and in the figures to denote identical or similar elements or components.

(8) FIG. 1 shows a perspective view of a valve base element 12. In the view in FIG. 1, a subsequent inner side 20 of the valve base element 12 and a cooling rib structure/flow-influencing structure 14 are illustrated, which are intended to uniformly distribute a coolant, flowing from above from a hollow valve stem, in the valve head. An engagement structure 16 or torque transmission element via which a torque may be transmitted to the valve base element 12 during a friction welding operation is apparent at the bottom of the valve base element 12. In a departure from the illustration, a sawtooth profile may also be used to allow even better torque transmission, even with low axial pressing or friction welding pressures.

(9) FIG. 2 shows the valve base element 12 from FIG. 1 in a bottom view, the engagement structure 18 or the torque transmission element being apparent here as flank toothing. In the center, a borehole as a centering element 18 is situated on a bottom side of the valve base element 12.

(10) FIGS. 3 and 4 respectively illustrate a perspective view and a sectional view of a valve body. The valve bodies 4 each include a valve stem 6 and a valve disk 8. A cavity 10 for a coolant such as sodium or a sodium-containing material that is liquid at operating temperature opens from the side of the valve disk 8. Due to the opening at the valve base, on the one hand a structurally stable valve may be very easily manufactured, and on the other hand a cavity that extends over a large area of a diameter of the valve head 8 may be very easily produced in the valve body.

(11) FIGS. 5 and 6 respectively show a beginning and an end of a friction welding operation according to the invention. In FIG. 5, the valve base element 12 together with the cooling rib structure/flow-influencing structure 14, facing the cavity 10 of the valve body 4, is attached to the valve body. The valve base element 12 is fixed or mounted on a friction welding mandrel 24, while the valve body 4 itself is clamped to the valve stem 6. At the beginning of the method, the friction welding mandrel 24 is set in rotation, resulting in heating of the contact surface between the valve base element 12 and the valve body 4 due to frictional heat. Further heating may also be provided using an additional induction heater.

(12) FIG. 6 illustrates an end of a friction welding operation according to the invention. The valve base element 12 has been pressed into the valve body 4 after the particular metals have heated enough to achieve sufficient deformability. A friction weld expulsion is not illustrated here for the sake of clarity.

(13) FIG. 7 illustrates a partial sectional view of the head of a valve 2 according to the invention. A protruding residual portion of the valve base element 12 has been removed in a machining operation, thus achieving an essentially flat valve base. The valve base element 12 is joined to the valve body 4 and the valve head 8 via the weld area or the heat influencing zone 20. A friction weld expulsion occurring on an outer side has likewise been removed. A friction weld expulsion extends at an inner side 20 or in the cavity 10. The friction weld expulsion 22 has been produced in the form of a cooling rib by use of suitable process parameters and an appropriate selection of material. This may likewise improve the heat transfer from the valve head 8 to a coolant (not illustrated) situated in the cavity 10.

(14) FIG. 8 shows a partial perspective view of a valve 2 according to the invention. The valve stem 6 ends in the valve head 8. The opening in the cavity from FIG. 3 is closed by the valve base element 12. The engagement elements of the valve base element 12 from FIG. 2 have been removed. Only a portion of the borehole of the centering element 18 is still discernible at the base of the valve head. The weld area/heat influencing zone is indicated by dashed lines.

(15) FIG. 9 illustrates a valve base element 12 that is mounted on a friction welding mandrel 24. The friction welding mandrel 24 is provided with structures that are complementary to the engagement element 16 of the valve base element 12 for transmitting a torque, and that are complementary to the centering element 18 of the valve base element 12. The shape of the engagement element/centering element determines how, and how much, torque can be transmitted, and whether the 16 [sic] valve base element 12 should or must be further clamped. Unlike the illustration, sawtooth-shaped flank toothing is preferred in order to allow the torque to be transmitted from the friction welding mandrel 24 to the valve base element 12, independently of an axial force component.