CN110945214A

CN110945214A - Method for manufacturing internally-cooled valve having cooling structure and valve manufactured by same

Info

Publication number: CN110945214A
Application number: CN201880043843.6A
Authority: CN
Inventors: 索思腾·马提亚斯; 安东尼奥斯·沃金; 吉多·贝亚德; 阿里夫·卢特菲
Original assignee: Federal Mogul Valvetrain GmbH
Current assignee: Federal Mogul Valvetrain GmbH
Priority date: 2017-06-29
Filing date: 2018-02-28
Publication date: 2020-03-31
Also published as: JP2020527662A; WO2019001779A1; DE102017114554A1; EP3585986B1; EP3585986A1; KR20200020811A; US20200149442A1; PL3585986T3

Abstract

The present invention relates to a method of manufacturing an internally cooled valve, the method comprising: providing an at least partially cylindrical outer semi-finished product (2), forming or increasing the depth of the at least partially cylindrical cavity in the semi-finished product (2) using a punch during hot working, thereby forming a valve blank; during hot working, the depressions in the end face of the male form structures at the bottom of the cavity.

Description

Method for manufacturing internally-cooled valve having cooling structure and valve manufactured by same

Technical Field

The invention relates to a method for producing an internally cooled valve, in the cavity of which a cooling structure is mounted on a valve seat. The invention also relates to a valve manufactured using the method according to the invention.

Background

Internally cooled valves have been known for a considerable time in which a cavity extends in the valve stem and in which sodium transfers heat from the valve head towards the valve stem which is cooled by the engine cylinder head, by so-called "oscillatory cooling".

It is also known to arrange a cooling structure inside the cavity via an insertable valve seat, in order to improve the heat transfer from the valve seat to the coolant in the cavity. However, since the material of the valve is weakened by the weld joining the separate valve seat to the valve head, valve failure and catastrophic engine damage can occur when the weld fails and coolant leaks into the combustion chamber, or the entire valve seat falls into the combustion chamber. Furthermore, welding is a technically complex, costly process step.

Disclosure of Invention

It is therefore desirable to have a method with which the cooling structure can be mounted inside the coolant chamber in the region of the valve seat without the need for a separate weld in the region of the valve seat or the valve head.

According to the present invention there is provided a method of manufacturing an internally cooled valve, the method comprising providing a semi-finished product having an at least partially cylindrical outer portion, and creating or deepening an at least partially cylindrical cavity in the semi-finished product by thermoforming and using embossing, thereby producing a valve blank. According to the invention, the method is characterized in that the end face of the imprint is provided with at least one recess by means of which a structure is formed on the base of the cavity during thermoforming. Thus, the cooling structure is printed from above to the inside of the valve seat by the area subsequently formed in the valve stem. After a period of time, the diameter of the portion subsequently forming the valve stem is reduced, so that in the subsequent valve there is a cavity, the diameter of which in the valve head is greater than in the valve stem. By using this method, any type of weld in the region of the valve head or valve seat can be dispensed with. Briefly, the method may be described as printing a structure into a cavity in the valve seat area, followed by the step of forming a portion of a valve blank into a valve stem without substantially altering the structure in the valve seat.

This initial step can be applied directly during the forming from a disc-shaped or cylindrical semifinished product, which is shaped into a bowl-shaped valve blank. However, for already bowl-shaped semifinished products, the cooling structure can also be printed onto the valve seat in a further processing step, likewise at least partially deepening the recess.

In one exemplary embodiment for an internally cooled valve manufacturing method, the forming includes back extrusion. In such a design, the valve blank may be pressed in a single step from an otherwise cylindrical or disc-shaped semi-finished product. Further processing steps are then used to form the valve or disc valve from the valve blank and introduce a coolant, such as sodium, into the cavity of the valve or disc valve.

In another exemplary embodiment of the present manufacturing method, the forming includes forging. The valve disks may also be integrally formed by forging and back extrusion.

In another embodiment of the present manufacturing method, the structure comprises cooling ribs extending in a circle or star shape. The cooling ribs extend in a circle or star from the axis of the valve blank.

Another embodiment of the present manufacturing method uses an imprint that presses a structure in the form of a pin, cone or truncated cone into a cavity at a valve seat as a cooling element. In particular, cooling elements having a rod, cone or truncated cone shape may allow for a higher heat transfer due to their larger surface area. Likewise, it is preferred to use a truncated cone at the edge of the piston base and a conical cooling element in the middle. The conical cooling element located on the axis of symmetry of the valve or valve blank may also effect a change in the coolant flow from moving in the axial direction to moving in the radial direction towards the disc rim to improve cooling of the valve head.

In another embodiment of the manufacturing method, the structure comprises guide vanes which allow the coolant in the valve to move in the cavity and to rotate around the symmetry axis of the valve. The guide vanes may be arranged similar to a radial compressor turbine.

In another embodiment, the method may further comprise integrally forming the valve head on the valve blank during or after forming. The lower part of the semi-finished product or valve blank is thereby widened and shaped into a valve disk or a valve disk edge.

In another embodiment of the manufacturing method for an internally cooled valve, after forming the valve head, the diameter of the valve blank beside the valve head is reduced in the axial direction, thereby forming the valve stem. The bowl-shaped valve blank must undergo further shaping to function as a disc valve. The invention is based on the fact that: a depression with a diameter greater than the diameter of the subsequent valve stem is pressed into the semifinished product, wherein a structure is pressed into the bottom of the depression, which improves the cooling of the subsequent valve seat. This is particularly advantageous when the subsequent cavity in the valve has a particularly large diameter to allow a particularly large amount of heat to be absorbed by the valve seat. Due to the larger diameter of the recess, the proposed method allows to mount or emboss the cooling structure inside the valve seat, since in this position the ratio of the embossed diameter to the height is smaller, which allows a larger force transmission. This is not possible with conventional hollow valves, since the embossing necessary for this purpose has a very unfavourable length to diameter ratio and may yield sideways during the embossing operation.

In another embodiment of the method of manufacturing an internally cooled valve, the valve stem is formed by sectional rolling or rotary forging, preferably by hot or cold hammering on a mandrel. The forging tool applies a radial impact to the workpiece resulting in a smaller cross-section of the workpiece being machined. The elongation of the material is higher than the quality of the machining. By using a mandrel, it is possible to ensure that the cavity inside the workpiece has the desired inner diameter.

In another embodiment, the method of manufacture includes rolling or wedge rolling on a mandrel, the valve stem being formed by rolling.

According to another aspect of the present invention, there is provided an internally cooled valve manufactured using one of the above methods.

Drawings

The invention is explained below with reference to a non-limiting schematic drawing.

Fig. 1A to 1F show, by way of example, cross-sectional views of various parts for manufacturing an internally-cooled valve according to the present invention.

Detailed Description

The same or similar reference numbers are used in the description and drawings to refer to the same or like parts or elements.

Fig. 1A shows a cross-sectional view of a cylindrical semifinished product 2, which is used as starting material for the manufacture of an internally cooled disc valve.

Fig. 1B shows a cross-sectional view of the semi-finished product 45 formed into a bowl shape. The bowl-shaped semifinished product 4 is formed from above into a bowl shape by stamping (not shown). The forming may be performed by hot forming or cold forming. In this case, counter-extrusion is used, so that the height of the shaped semifinished product 4 is considerably increased compared to the unformed semifinished product 2 in fig. 1. The embossed depressions are pressed into ribs or risers at the base of the shaped cavity. These ribs or elevations form a cooling structure 6, by means of which structure 6 the surface area of the depression is significantly increased in order to increase the heat transfer from the subsequent valve seat to the coolant.

A good diameter to length ratio allows the use of counter-extrusion without the risk of the stamp being subjected to transverse deformation.

Fig. 1C shows a bowl-shaped formed blank 4, which has been further formed into a first valve blank 8. A similar embossing may be used to form the valve head 16 by lateral extrusion and counter extrusion, with the cooling structure 6 still located in the recess. As a result of the lateral pressing, the diameter of the first valve blank 8 in the region of the valve head 16 can be increased, and the thickness of the valve seat 18 is also greatly reduced in this step. By counter-pressing the components, the length of the stem portion 20 can be increased simultaneously, wherein the diameter of the stem portion is not increased.

The semifinished product from fig. 1A can likewise be formed directly into the first valve blank 8. The first valve blank 8 can thus also be formed in a separate step from the originally cylindrical semifinished product, wherein in this method the steps shown in fig. 1B are skipped or omitted.

Fig. 1D shows a first valve blank 8 which is further processed by rolling, wedge rolling or hammering in the stem region 22 to reduce the stem diameter and increase the stem length, thus producing a second valve blank 10. Also in this process step, the cooling structure 6 is not or only slightly deformed.

Fig. 1E shows the second valve blank 10 of fig. 1D further processed by rolling, cross-wedge rolling or hammering in the valve stem region 24, thereby further reducing the diameter of the valve stem 24 and further increasing the length of the valve stem 24. As a result of these working steps, the second valve blank 10 has been formed into a third valve blank 12. Also in this machining step, there is little or no deformation of the cooling structure 6 in the region of the valve seat 18 of the cavity 30.

Fig. 1E shows the third valve blank 12 after further processing by rolling, cross-wedge rolling or hammering at the transition between the valve stem region 24 and the valve disc 16. The outer diameter of the valve stem 26 may reach or actually reach the final dimension in the last step. The valve stem or cavity 32 or recess may now be filled with coolant (not shown) and the cavity closed. Reducing the diameter of valve stem 26 also increases the length of valve stem 26 to or beyond its final size. In addition, the valve stem and valve head may be finish machined or milled. In the last working step, the cooling structure 6 in the region of the valve seat 18 of the chamber 30 is also easy to form. Overall, however, a comparatively large cavity also remains in the region of the valve head 16, which cavity also has the cooling structure 6, and which allows a greater heat transfer from the valve seat to the coolant in the cavity 32.

The scope of protection is defined by the claims.

List of reference numerals:

2 semi-finished product

4 bowl-shaped semi-finished product

6 cooling structure

8 first valve blank

10 second valve blank

12 third valve blank

14 valve blank

16 valve disk

18 valve blank

20 stem of a first valve blank

22 stem of a second valve blank

24 valve stem of third valve blank

26 stem of a first valve blank

30 cavities/recesses for coolant

Claims

1. A method of manufacturing an internally cooled valve comprising:

providing a semifinished product (2) having an at least partially cylindrical outer portion, and

-forming or deepening an at least partially cylindrical cavity in the semi-finished product (2) by thermoforming and by embossing, thereby producing a valve blank,

it is characterized in that the preparation method is characterized in that,

during thermoforming, a structure is formed on the base of the cavity by the depression at the stamping end face.

2. The method of claim 1, wherein thermoforming comprises back extrusion.

3. The method of claim 1, wherein hot forming comprises forging.

4. A method according to claim 1, 2 or 3, wherein the structure comprises cooling ribs extending in a circle or star shape.

5. A method according to claim 1, 2 or 3, wherein the structure comprises a pin, cone or truncated cone serving as a cooling element.

6. A method according to claim 1, 2 or 3, wherein the structure comprises a vane capable of rotating the coolant in the valve.

7. A method according to any one of claims 1 to 6, wherein the valve head is integrally formed on the valve blank during or after thermoforming.

8. A method of manufacturing an internally cooled valve in which, after the valve head is formed, the diameter of the valve blank immediately adjacent the valve head is reduced in the axial direction to form a valve stem.

9. A method of manufacturing an internally cooled valve in which a valve stem is formed by rolling or rotary forging, preferably by hot or cold hammering on a mandrel.

10. A method of manufacturing an internally cooled valve in which a valve stem is formed by rolling, preferably by rolling on a mandrel or cross-wedge rolling.

11. An internally cooled valve manufactured by a method according to any one of claims 1 to 10.