U.S. patent application number 09/816027 was filed with the patent office on 2001-10-04 for one-piece piston.
This patent application is currently assigned to MAHLE GmbH. Invention is credited to Kemnitz, Peter, Kortas, Jochen.
Application Number | 20010025568 09/816027 |
Document ID | / |
Family ID | 7636692 |
Filed Date | 2001-10-04 |
United States Patent
Application |
20010025568 |
Kind Code |
A1 |
Kemnitz, Peter ; et
al. |
October 4, 2001 |
One-piece piston
Abstract
A one-piece piston comprises a piston crown made of steel and a
bottom component made of forged steel, and a cooling channel that
is formed by welding the crown and the bottom component of the
piston together. The cooling channel is located radially behind the
annular grooves. The crown and the bottom component of the piston
jointly form a central cooling chamber whose lower limiting wall is
forged as one piece with the bottom component of the piston. The
welding seams joining the crown and the bottom component of the
piston are friction welding seams. The piston provides for superior
cooling of the crown of the piston and simplifies the production of
the welding seams.
Inventors: |
Kemnitz, Peter; (Leutenbach,
DE) ; Kortas, Jochen; (Stuttgart, DE) |
Correspondence
Address: |
COLLARD & ROE, P.C.
1077 Northern Boulevard
Roslyn
NY
11576
US
|
Assignee: |
MAHLE GmbH
|
Family ID: |
7636692 |
Appl. No.: |
09/816027 |
Filed: |
March 23, 2001 |
Current U.S.
Class: |
92/186 ;
92/231 |
Current CPC
Class: |
F02F 3/003 20130101;
F02F 3/22 20130101; F02F 2200/04 20130101; F02F 2003/0061 20130101;
F05C 2201/0448 20130101 |
Class at
Publication: |
92/186 ;
92/231 |
International
Class: |
F01B 031/08 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 28, 2000 |
DE |
100 15 377.1 |
Claims
What is claimed is:
1. A one-piece piston with annular grooves for receiving piston
rings, comprising: a piston crown made of steel; a lower piston
component made of forged steel; a cooling channel for receiving
cooling oil, said cooling channel being formed by two welding seams
formed by friction welding, said seams joining the piston head and
the lower piston component with each other and being arranged at
least partially in a radial manner behind the annular grooves; and
a central cooling chamber for receiving cooling oil formed jointly
by said piston crown and lower piston component, said central
cooling chamber having a lower limiting wall that is forged so as
to form one piece with the lower piston component.
2. The one-piece piston according to claim 1, wherein overflow
openings are provided between the cooling channel and the central
cooling chamber.
3. The one-piece piston according to claim 2, wherein at least one
drain opening for the cooling oil is provided in the central
cooling chamber.
4. The one-piece piston according to claim 1, wherein the piston
crown is made of a highly heat-resistant material.
5. The one-piece piston according to claim 4, wherein the piston
crown is made of valve-type steel.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to a one-piece piston with annular
grooves for receiving piston rings, having a piston crown made of
steel and a lower piston component made of forged steel. There is a
cooling channel for receiving cooling oil and formed by welding
seams formed by friction welding that join the piston crown and
lower piston component. A central cooling chamber is formed jointly
by the piston crown and the lower piston component, where the floor
of the chamber is forged to be one piece with the lower piston
component.
[0003] 2. The Prior Art
[0004] One-piece pistons are known from German Patent No. 30 32 671
A, FIG. 2. The known piston consists of a bottom steel component
and a top steel component, which are joined with each other by
welding, forming a cooling channel. No detailed statements are made
concerning the welding method employed in this process. The
representation of the welding seams suggests that conventional
welding methods are used, for example such as the MAG welding
method.
[0005] One drawback of the known piston is that the piston crown is
not cooled within the radial inner zone or in the trough. A further
drawback is that welding effects cannot excluded in conjunction
with conventional welding methods, and that access is made more
difficult for the welding torch especially if the combustion
troughs are deep.
[0006] German Patent No. DE 41 34 528 discloses that, in
conjunction with multi-component pistons, in particular with
pendulum shaft-type pistons, it is possible to produce a closed
cooling channel by friction welding. Moreover, it is known from
French Patent No. 15 89 247, FIG. 4, to produce a central, closed
cooling chamber by friction welding.
SUMMARY OF THE INVENTION
[0007] It is an object of the invention to provide a piston that
allows for cooling the crown of the piston in a simple yet
effective manner, as well as of simplifying the manufacture of the
piston.
[0008] This object is accomplished according to the invention by a
one-piece piston with annular grooves for receiving piston rings,
comprising a piston crown made of steel and a lower piston
component made of forged steel. An outer cooling channel for
receiving cooling oil is formed by two welding seams formed by
friction welding that join the piston head with the lower
component. The cooling channel is arranged at least partially
radially behind the annular grooves.
[0009] The piston crown and lower piston component jointly form a
central cooling chamber for receiving cooling oil. The lower
limiting wall (bottom) of the cooling chamber is forged to form one
piece with the lower piston component.
[0010] The special advantage of pistons as defined by the invention
is that a separate lower sheet metal cover that must be joined with
the piston by clamping, welding, flanging or in some other way to
form a bottom for a cooling chamber or cooling channel, is not
required either for the outer channel or for the inner cooling
chamber.
[0011] The cooling oil is supplied to the outer cooling channel,
subsequently flows through overflow openings in a radially inward
manner into the central cooling chamber, and then exits from the
piston via one or several openings located in the lower wall
defining the central cooling chamber.
[0012] The edge of the piston's combustion trough can be optionally
provided with a reinforcement, which is produced by friction
welding from highly heat-resistant steel, for example from a
valve-type steel. In this way, cracking is prevented from occurring
around the edge of the trough.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Other objects and features of the present invention will
become apparent from the following detailed description considered
in connection with the accompanying drawings. It is to be
understood, however, that the drawings are designed as an
illustration only and not as a definition of the limits of the
invention.
[0014] In the drawings, wherein similar reference characters denote
similar elements throughout the views:
[0015] FIG. 1 shows the cross section of a piston as defined by the
invention in the direction of the piston pin; and
[0016] FIG. 2 shows the cross section of a piston as defined by the
invention in the thrust-counterthrust direction.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0017] FIGS. 1 and 2 show a one-piece piston 1, which comprises a
piston crown 2 and a lower piston component 3. The two components
are joined with each other by welding. forged or flow-pressed
steel. A cooling channel 5 is located in the radially outer zone of
the piston behind annular grooves 4. Cooling channel 5 is produced
by joining crown 2 and lower component 3 of the piston by welding.
The welding beads, which are not turned, illustrate that the two
welding seams 6 and 7 are seams of friction welding. A cooling
chamber 8 is located at about the level of cooling channel 5 in the
interior of the piston below the combustion trough.
[0018] Lower limiting wall 9 of cooling chamber 8 is at least
partially forged or flow-pressed so as to form one piece with lower
component 3 of the piston, and is consequently not formed by a
separate sheet metal component that is joined with the piston, for
example by clamping, as it is frequently described in the prior
art. Overflow openings 10 are drilled into lower component 3 of the
piston between cooling channel 5 and cooling chamber 8.
[0019] The filling level within cooling channel 5 and in cooling
chamber 8 can be adjusted by vertical tubes known in the prior
art.
[0020] Accordingly, while only one embodiment of the present
invention has been shown and described, it is obvious that many
changes and modifications may be made thereunto without departing
from the spirit and scope of the invention.
* * * * *