U.S. patent application number 11/576302 was filed with the patent office on 2010-11-04 for simple frictional weld.
This patent application is currently assigned to KS KOLBENSCHMIDT GMBH. Invention is credited to Josef Dambacher, Volker Gniesmer, Peter Kolbe, Gerhard Luz, Jochen Muller, Christian Schaller, Ernst Peter Schmitz.
Application Number | 20100275873 11/576302 |
Document ID | / |
Family ID | 35666190 |
Filed Date | 2010-11-04 |
United States Patent
Application |
20100275873 |
Kind Code |
A1 |
Gniesmer; Volker ; et
al. |
November 4, 2010 |
SIMPLE FRICTIONAL WELD
Abstract
A cooling channel piston for an internal combustion engine which
includes a piston bottom and a piston shaft that are joined thereto
of a friction welding process. The piston bottom and the piston
shaft jointly form a cooling channel. An annular wall which
radially delimits the cooling channel towards the outside is formed
by the piston bottom and/or the piston shaft. The annular wall can
be sealed by a welding process once the piston bottom and the
piston shaft have been joined together.
Inventors: |
Gniesmer; Volker; (Alfeld,
DE) ; Luz; Gerhard; (Nordheim, DE) ; Muller;
Jochen; (Neuenstein, DE) ; Schaller; Christian;
(Billigheim, DE) ; Schmitz; Ernst Peter;
(Abstgmund, DE) ; Kolbe; Peter; (Aalen, DE)
; Dambacher; Josef; (Nereseheim, DE) |
Correspondence
Address: |
YOUNG BASILE
3001 WEST BIG BEAVER ROAD, SUITE 624
TROY
MI
48084
US
|
Assignee: |
KS KOLBENSCHMIDT GMBH
Neckarsulm
DE
|
Family ID: |
35666190 |
Appl. No.: |
11/576302 |
Filed: |
September 29, 2005 |
PCT Filed: |
September 29, 2005 |
PCT NO: |
PCT/EP05/10535 |
371 Date: |
September 8, 2009 |
Current U.S.
Class: |
123/193.6 ;
29/888.04 |
Current CPC
Class: |
F02F 3/003 20130101;
F02F 3/20 20130101; Y10T 29/49249 20150115; B23K 20/129 20130101;
F02F 3/22 20130101; F02F 2200/04 20130101; F01P 3/10 20130101; B23K
2101/003 20180801; B23K 31/02 20130101; F02F 2003/0061
20130101 |
Class at
Publication: |
123/193.6 ;
29/888.04 |
International
Class: |
F02F 3/02 20060101
F02F003/02; B23P 15/10 20060101 B23P015/10 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 29, 2004 |
DE |
10 2004 047 842.2 |
Dec 22, 2004 |
DE |
10 2004 061 778.3 |
Claims
1. The cooling channel piston for a combustion engine, comprising:
a piston crown and a piston skirt attached thereto by means of a
weld which together form a cooling channel: a ring wall delimiting
the cooling channel radially outward at least formed by one of the
piston crown or the piston skirt and the ring wall closed to form a
seal by one of an interference and a positive fit after piston
crown and piston skirt have been joined; and a face of the ring
wall below a ring belt and an adjoining face of a ring side above
the piston skirt both have a matching shoulder.
2. The cooling channel piston of claim 1, wherein the ring wall is
closed to form a positive fit by means of a another weld.
3. The cooling channel piston claim 1 wherein the face of the ring
wall below the ring belt and the adjacent face of the ring side
above the piston skirt are configured in the shape of a groove.
4. The cooling channel piston of claim 3, wherein a circumferential
groove in the lower face of the ring belt has a lesser depth (X)
than a circumferential tongue has height (Y), the tongue (17) being
deformable after the piston crown and piston skirt have been
joined.
5. The cooling channel piston of claim 1 wherein in an inner area
of the cooling channel piston at least one additional, radially
circumferential web is disposed to form at least one additional
cooling channel.
6. The cooling channel piston of claim 1, where the weld is one of
a friction weld and a resistance weld.
7. The cooling channel piston of claim 2, wherein the another weld
is a non-friction weld.
8. The cooling channel of claim 1, wherein the face of the ring
wall below the ring belt and the adjacent face of the ring side
above the piston skirt have matching grooves.
Description
[0001] The invention relates to a one-piece, steel welded
cooling-channel piston of forged steel in accordance with the
features of the preamble of claim 1.
[0002] The object of the invention is to develop a piston
surpassing the prior art in which the cooling channel or cooling
cavity is tightly sealed. A piston of this type is described, for
example, in the unpublished German patent application DE 10 2004
038 465.7.
[0003] A cooling channel piston is known from the previously
published German patent application DE 102 44 512 A1 having the
features which constitute the genre. The upper part of the piston
has circumferential radial webs running coaxially behind the ring
belt which are joined to corresponding webs on the piston skirt by
means of friction welding. After the joining of piston upper part
and piston lower part, the lower face of the ring belt is located
adjacent the upper circumferential radial face of the piston skirt.
In the state when piston upper and lower parts are joined, the
outer piston wall areas between both parts of the piston form a
contact surface which is characterized by a gap a few tenths of a
millimeter wide. It can remain open or be sealed by means of a
temperature-resistant sealing ring which is positioned before the
joining of both parts of the piston on one of the contact surfaces,
for example that of the lower part of the piston. A sealing ring of
this kind has the advantage that the cooling channel is then closed
to form a seal, but in a disadvantageous manner it represents an
additional component which has to be produced and correctly
positioned when the two parts of the piston are joined. In
addition, the sealing ring, just like the few tenths of a
millimeter wide gap without a sealing ring, has the disadvantage
that the upper part of the piston (piston crown) cannot be
supported on the lower part of the piston (piston skirt) while the
piston is operating. While operating, the piston crown is deformed
in a disadvantageous manner by the combustion pressures acting on
it so that the strength and durability of the piston are
compromised.
[0004] A cooling channel piston for a combustion engine is known
from EP-A-1 061 249, having a piston crown and a piston skirt
joined by means of friction welding, which together form a cooling
channel, where a ring wall delimiting the cooling channel radially
outward is formed by the piston crown and/or the piston skirt and
the ring wall can be closed to form a seal by an interference fit
and/or positive fit after piston crown and piston skirt have been
joined. As shown in FIGS. 2 to 5, the surfaces of the ring belt and
of the piston skirt facing each other are radially circumferential
and coplanar with each other. The mutually coplanar facing surfaces
on the lower edge of the ring belt and the upper edge of the piston
skirt do not have any type of shoulder so that when the cooling
channel piston is operating, there is no adequate support for the
piston crown on the piston skirt. Only in FIG. 6 is it shown that
the upwardly facing termination of the piston skirt has a single
shoulder with which the coplanar aligned lower part of the ring
belt can come into contact. This certainly improves the supporting
effect, but not optimally. In addition, the inwardly directed
L-shape of the shoulder at the upper end of the piston skirt is
extremely difficult and expensive to manufacture with the required
precision, so that no practical solution can be derived from EP-A-1
061 249.
[0005] Generic cooling channel pistons are also known from US
2004/144247 A1 and US-B1-6698391 in which, however, the
circumferential radial lower edge of the ring belt and the upper
edge of the piston skirt coming into contact therewith are also
only configured coplanar so that the supporting effect is not
disclosed.
[0006] The object of the invention is therefore to prepare a
cooling channel piston which effectively avoids the disadvantages
described initially.
[0007] The object of the invention is achieved to the extent that
the upper and lower part of the cooling channel steel piston are
first joined by means of friction welding or resistance press
welding where a ring wall delimiting the cooling channel in an
outward direction does not initially form a material bond and the
tight sealing of the ring wall of the cooling channel is achieved
by means of an interference and/or positive fit, specifically a
subsequent welding process. An advantageous joining and closing of
the cooling channel is now possible through the design of the
cooling channel piston in accordance with the invention, wherein
the joined parts, that is, piston crown and piston skirt, are
joined by means of friction welding or resistance press welding.
The subsequent external welding (not friction welding), or the
corresponding shaping of the ring wall respectively, affects the
cooling channel to the extent that no flashes from friction welding
extend into the cooling channel in the area of the ring wall.
Through the subsequent welding of the outer ring wall, or generally
through the interference and/or positive fit, the piston is
supported in the area of the ring belt, that is, the forces acting
on the piston crown can be transferred to the piston skirt, which
considerably increases the strength and durability of the cooling
channel piston. At the same time, the welding also counteracts
deformation in the skirt area, particularly in its upper area. In
addition, manufacturing tolerances between the upper and lower part
are compensated. In addition, provision is made in accordance with
the invention for both the face of the ring wall below the ring
belt and also the adjoining face of the ring side above the piston
skirt to have a matching shoulder. As a result, both in the case of
the interference fit and in the case of the positive fit connection
the cooling channel is dosed and the support of the piston crown on
the piston skirt is optimized in the contact or joint area.
[0008] Additional welded-in parts can be dispensed with due to the
piston being formed only of piston crown and piston skirt, which
considerably simplifies the manufacture of a cooling channel piston
in accordance with the invention. Additionally, one advantage of
the invention is that, depending on the configuration of the joint
area around the ring wall, this joint area can serve to lend
rigidity to and position the joined parts during the friction
welding. A cost saving results at the same time because welded-in
parts can be dispensed with in the area of the cooling channel.
[0009] The invention will be described hereinafter with reference
to an embodiment to which the invention is not restricted and
explained by the FIGS. 1 to 4.
[0010] FIG. 1 shows the section through a one-piece, welded cooling
channel piston, specifically of forged steel.
[0011] One half of a sectioned view of a piston and specifically of
a cooling channel piston for a combustion engine is shown In FIG.
1. The cooling channel piston 1 shown here consists of a piston
crown 2 and a piston skirt 3 which are joined by means of friction
welding which results in a friction welding seam 4. The piston
crown 2 is formed from a combustion bowl 5, an upper land 6, a ring
belt 7 and one part of a cooling channel 8. The area of the piston
skirt 3 comprises an outer skirt surface 9 of the cooling channel
piston 1, a piston pin bore 10 and a lower part 11 of the cooling
channel. The cooling channel 8 is consequently formed of an upper
and a lower area 11 of the piston crown 2 and the piston skirt 3
and a recessed, circumferential web of the piston crown 2 and the
piston skirt 3.
[0012] In this embodiment an additional groove 12 is introduced
into the outer surface of the piston 1 below the ring belt 7. After
the piston crown 2 and the piston skirt 3 have been joined by
friction welding, the two parts of the piston 2, 3 merely abut each
other in the area of the ring wall 13 without the existence of a
material bond and/or tight connection in the area of this ring wall
13. The joining of the ring wall 13 is carried out in a subsequent,
supplementary welding process. Here, the widest variety of welding
processes (but not friction welding), such as for example, electron
beam welding, WIG welding, MIG welding, MAG welding, laser welding,
etc. is conceivable.
[0013] In this embodiment, a shoulder 14 is incorporated in the
joint area of the ring wall 13 which has the advantage that when
welding the ring wall 13, the weld seam root does not extend into
the cooling channel 8 and in addition, a tight weld is made
possible by welding up the shoulder and a clean, pore-free root is
created.
[0014] The design of the shoulder 14 is not restricted to this
embodiment, but rather the creation of other shoulder shapes 14 in
the area of the ring wall 13 is conceivable which either assist the
subsequent welding process or have a positive effect on the
friction welding.
[0015] An additional advantage of welding the ring wall 13
afterwards is that until immediately before the final joining of
the piston crown 2 and the piston skirt 3, inert gases can
penetrate through the gap in the ring wall 13 into the area of the
friction weld seam which in turn have a positive effect on the
material structure in the friction weld seam 4. The location of the
shoulder 14 in the area of the ring wall 13 is placed exactly in
the center of the groove 12 only as an example. This shoulder 14
lies advantageously below the ring belt 7 and above the lower end
15 of the cooling piston channel. It is also conceivable in
accordance with the invention not to introduce a groove 12 into the
piston 1 and to form the ring wall 13 only with the surface of the
skirt 9.
[0016] With a view to FIG. 1, it should be pointed out once more
that the ring wall 13 is formed by the lower face of the ring belt
7 and the upper shoulder of the piston skirt 3. Because of the
geometry in the area of the ring wall 13 shown in FIG. 1, the
welding procedure can be performed particularly conveniently. The
matching shoulders of the opposing faces, as already explained,
prevent the weld seam from forming towards the cooling channel 8.
Besides that, the advantage of the welding process to be performed
radially on the outside remains, specifically that the weld seam
projecting radially outward can be removed, for example by
machining. In addition to this ring wall 13 geometry shown in FIG.
1, it is also conceivable that the upper part of the piston skirt 3
has a plateau which the lower face of the ring belt 7 contacts
after the friction welding process. It is also conceivable that the
ring belt 7 is located on the piston skirt and comes into contact
with a lower face below the upper land 6. The advantages described
initially remain with these geometries as well. The basic principle
of the present invention is important and advantageous, namely
that) that the piston crown 2 and the piston skirt 3 have webs
recessed from the outer surface running radially circumferential
which are joined by means of friction welding while the ring wall
13, which is shaped so that the faces of the ring wall 13 bordering
each other (of the piston crown 2 and/or of the piston skirt 3) do
not yet form a material joint in the friction welding process, is
directly on the outer surface of the cooling channel piston 1. The
welding of the adjacent faces of the ring wall 13 takes place in an
additional step from the outside only after piston crown 2 and
piston skirt 3 have been joined through their internal webs by
means of friction welding.
[0017] FIG. 2 shows the area of the ring wall 13 where the part of
the face of the ring belt 7 projecting downward is configured in a
grooved shape into which a radially circumferential shoulder facing
upwards engages above the face of the piston skirt 9. Here too,
welding the adjacent faces of the ring wall 13 is subsequently
carried out from the outside. This closes the cooling channel 8
completely, the ring belt 7 is supported against deformation when
the cooling channel piston 1 is operating, and the piston skirt is
supported against deformation, in particular in the upper area.
[0018] FIG. 3 shows a section of the area of the ring wall 13 where
the lower circumferential section of the ring belt 7 and the upper
circumferential section of the piston skirt 9 are shown. In the
design in accordance with FIG. 3, the face of the ring wall 13
below the ring belt 7 and the adjacent face of the ring side 13
above the piston skirt 9 are configured in the manner of a groove,
similar to FIG. 2, but with the particular feature that the
circumferential tongue 17 has a height X which is greater than the
depth Y of the groove 16. The procedure during manufacture of the
cooling channel piston 1 is that piston crown 2 and piston skirt 3,
as already described, are joined by means of friction welding or
resistance press welding and thereby the two faces of the ring wall
13 from FIG. 3 (are at a distance (with a gap) and do not contact
each other. Subsequently the cooling channel piston 1 is pressed
together from above and from below, in the axial direction of the
piston stroke. The opposed faces of the underside of the ring belt
7 and of the upper side of the piston skirt 9 come into contact,
where simultaneously the radially circumferential tongue 17 is
deformed inside the radially circumferential groove 16 so that an
interference fit and a positive fit result in the area of the ring
wall 13, which ensures that the cooling channel 8 is closed to form
a seal and at the same time the piston crown 2 can rest on the
piston skirt 9. In a preferred embodiment, this interference and
positive fit is sufficient, although it is also conceivable to
reinforce the contact area additionally in the area of the ring
wall 13 through a material bond by means of a welding
procedure.
[0019] Something similar applies in the embodiment in accordance
with FIG. 4, where the face of the ring wall 13 below the ring belt
7 and the adjacent face of the ring side 13 above the piston skirt
9 both have a matching shoulder. In this instance also, the
opposing faces are not in initial contact after the piston crown 2
and piston skirt 3 have been joined, but a gap has formed instead.
To eliminate the gap to achieve sealing of the cooling channel 8
and absorption of force for the piston crown 2 on the piston skirt
3, the cooling channel piston 1 is again exposed to a force from
above and from below so that in the area of the contact surfaces an
interference or a positive fit results. The cooling channel 8 is
sealed and absorption of force is provided so that in contrast to
the embodiment from FIG. 1, a welding procedure in the area of the
ring wall 13 can be omitted.
[0020] In summary, it must be pointed out once again that initially
the piston crown 2 is joined to the piston skirt 3 by means of
friction welding or resistance press welding. This joining takes
place in an area clearly set back from the ring belt 7 which is
located coaxially between the back side of the ring belt 7 and the
outer circumference of the combustion bowl 5 to achieve sufficient
rigidity. Following this joining of piston crown 2 and piston skirt
3, the ring wall 13 (the area below the ring belt 7 and above the
piston skirt 9) is closed by means of an interference and/or
positive fit such that on the one hand the cooling channel 8 is
sealed and on the other hand the piston crown 2 can rest on the
piston skirt 3 in such a way that deformation of the piston crown 2
when the cooling channel piston 1 is operating is clearly reduced
since the combustion pressures or forces acting on the piston crown
2 can be transferred to the piston skirt (9). In this case the
contact area in the region of the ring wall 13 can still be
materially joined by means of a welding process, but this can
normally be dispensed with.
[0021] Alternatively, or additionally, the geometric relationships
after the joining of piston crown 2 and piston skirt 3 are such
that the faces below the ring belt 7 and above the piston skirt 9
are not yet in contact, but a gap has formed. In order to seal the
cooling channel 8 and to ensure the absorption of forces from the
piston crown 2 to the piston skirt 3, this area of the ring wall 13
is closed in a manner in accordance with the invention as a
positive fit by means of a welding procedure, as already described.
The opposing faces can be configured planar or be configured from
other geometric shapes (as for example step-shaped in accordance
with FIG. 3 or tongue-and-groove as in FIG. 3.
[0022] With reference to FIG. 1, it must be pointed out
supplementary that in the internal region of the cooling channel
piston 1 there may be, but does not have to be, an additional,
radially circumferential web 18. This web 18, which can be
manufactured with the cooling channel piston 1 or as a separate
component which can be joined to the cooling channel piston 1, then
forms at least one further cooling channel 19, where in addition to
the two cooling channels 8, 19, which can also be described as
cooling chambers, a cooling medium can be introduced centrally in
the interior area of the cooling channel piston 1, permanently or
circulating. Not shown, but present, are on the one hand means with
which the cooling medium can be sprayed into the cooling channel or
cooling channels, and on the other hand the necessary orifices, as
for example holes on the underside of the interior area or also
inside the webs separating the cooling channels.
REFERENCE NUMERAL LIST
[0023] 1. Cooling channel piston [0024] 2. Piston crown [0025] 3.
Piston skirt [0026] 4. Friction welding seam [0027] 5. Combustion
bowl [0028] 6. Top land [0029] 7. Ring belt [0030] 8. Cooling
channel [0031] 9. Skirt surface [0032] 10. Piston pin hole [0033]
11. Lower area [0034] 12. Groove [0035] 13. Ring wall [0036] 14.
Shoulder [0037] 15. Lower end [0038] 16. Groove [0039] 17. Tongue
[0040] 18. Web [0041] 19. Cooling channel
* * * * *