U.S. patent application number 12/783604 was filed with the patent office on 2010-12-09 for rocker arm for a valve train of an internal combustion engine.
This patent application is currently assigned to SCHAEFFLER TECHNOLOGIES GMBH & CO. KG. Invention is credited to Robert Kamm, Rainer Schwinn.
Application Number | 20100307437 12/783604 |
Document ID | / |
Family ID | 43299828 |
Filed Date | 2010-12-09 |
United States Patent
Application |
20100307437 |
Kind Code |
A1 |
Kamm; Robert ; et
al. |
December 9, 2010 |
ROCKER ARM FOR A VALVE TRAIN OF AN INTERNAL COMBUSTION ENGINE
Abstract
A rocker arm (1a to 1f) for a valve train of an internal
combustion engine is provided having an elongate lever body (2a to
2f) formed out of sheet metal and including a first end section
(3), a second end section (5) and a center section (4) formed by
two spaced apart, parallel side walls (6a to 6f), having aligned
axle-receiving bores (7). The first end section includes a crossbar
(11a to 11f) connecting the side walls to each other and two
contact surfaces (12) for a simultaneous actuation of two gas
exchange valves of the internal combustion engine, and the first
end section is configured substantially wider than the center
section. The contact surfaces extend on the crossbar while being
spaced in transverse direction from the side walls.
Inventors: |
Kamm; Robert; (Veitsbronn,
DE) ; Schwinn; Rainer; (Nurnberg, DE) |
Correspondence
Address: |
VOLPE AND KOENIG, P.C.
UNITED PLAZA, 30 SOUTH 17TH STREET
PHILADELPHIA
PA
19103
US
|
Assignee: |
SCHAEFFLER TECHNOLOGIES GMBH &
CO. KG
Herzogenaurach
DE
|
Family ID: |
43299828 |
Appl. No.: |
12/783604 |
Filed: |
May 20, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61184426 |
Jun 5, 2009 |
|
|
|
Current U.S.
Class: |
123/90.39 |
Current CPC
Class: |
F01L 1/26 20130101; F01L
1/185 20130101; F01L 2305/00 20200501 |
Class at
Publication: |
123/90.39 |
International
Class: |
F01L 1/18 20060101
F01L001/18 |
Claims
1. A rocker arm for a valve train of an internal combustion engine,
comprising an elongate lever body formed of sheet metal and
including a first end section, a second end section and a center
section formed by two spaced apart, parallel side walls having
aligned axle-receiving bores, the first end section including a
crossbar connecting the side walls to each other and two contact
surfaces for a simultaneous actuation of two gas exchange valves of
the internal combustion engine, said first end section being
configured substantially wider than the center section, and the
contact surfaces extend on the crossbar while being spaced in a
transverse direction from the side walls.
2. The rocker arm according to claim 1, wherein the second end
section of the lever body comprises a joint socket for mounting the
rocker arm on a stationary joint head arranged in the internal
combustion engine, the rocker arm further comprising a roller
mounted on a roller axle fixed in the axle-receiving bores.
3. The rocker arm according to claim 1, wherein the lever body has
a substantially T-shaped configuration viewed in a direction
perpendicular to the contact surfaces.
4. The rocker arm according to claim 3, wherein the crossbar
comprises an inner section which is connected to lower edges of the
side walls facing the gas exchange valves while extending between
the side walls and further comprises two outer sections which are
connected to upper edges of the side walls turned away from the gas
exchange valves and extend away from each other.
5. The rocker arm according to claim 4, wherein inner ends of the
outer sections are bent through 180.degree. and connected to the
upper edges of the side walls while extending parallel to the side
walls and slightly spaced from or in bearing relationship to the
side walls.
6. The rocker arm according to claim 5, wherein the inner ends of
the outer sections are welded to the side walls in a region of the
lower edges of the side walls.
7. The rocker arm according to claim 4, wherein outer ends of the
outer sections are bent at a right angle in a direction of the gas
exchange valves to engage around the gas exchange valves and serve
as a transverse guide of the rocker arm relative to the gas
exchange valves.
8. The rocker arm according to claim 3, wherein the first end
section, together with the side walls widening into a T-shape and
the crossbar, forms a substantially H-shaped or U-shaped
cross-sectional profile.
9. The rocker arm according to claim 8, wherein the U-shaped
cross-sectional profile is open in a direction of the gas exchange
valves to engage around the gas exchange valves and serves as a
transverse guide of the rocker arm relative to the gas exchange
valves.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/184,426, filed Jun. 5, 2009, which is
incorporated herein by reference as if fully set forth.
BACKGROUND
[0002] The invention concerns a rocker arm of a valve train of an
internal combustion engine. The rocker arm comprises an elongate
lever body formed out of a sheet metal and comprising a first end
section, a second end section and a center section formed by two
spaced apart, parallel side walls comprising aligned axle-receiving
bores, the first end section comprising a crossbar connecting the
side walls to each other and two contact surfaces for a
simultaneous actuation of two gas exchange valves of the internal
combustion engine, and said first end section is configured
substantially wider than the center section.
[0003] A double rocker arm of the above-noted type is known from
the document DE 196 18 417 A1, which is considered to be generic,
and, besides the low manufacturing costs incurred by using a
shaping method, it is characterized by an advantageous high-quality
light-weight characteristic because the lever body possesses a
width matched to the distance between the two gas exchange valves
only on the valve-side first end section, whereas the remaining
lever geometry corresponds to that of a standard rocker arm for
actuation of only one gas exchange valve i.e., of a single rocker
arm. In contrast, the double rocker arm proposed in the document DE
43 36 360 C2 possesses a clearly larger mass and a correspondingly
high mass moment of inertia about its fulcrum because the
considerable valve-side width of the lever extends over the first
end section and over the entire center section up to the second end
section.
[0004] A drawback of the generic double rocker arm of the
first-cited document, however, is the arrangement of the contact
surfaces actuating the gas exchange valves on the valve-side lower
edges of the side walls of the lever body. This arrangement
requires namely that the wall thickness of the side walls must be
matched to the required width of the contact surfaces and thus to
the diameter of the valve stems in contact therewith. Starting from
the typical ratio of the valve stem diameter to the lever wall
thickness in an order of magnitude of 2:1 in standard single rocker
arms, the wall thickness of the generic double rocker arm would be
clearly too large either locally in the region of the contact
surfaces or uniformly all-over. Whereas the required local
enhancement of the wall thickness by a shaping method would be at
least considerably difficult, the uniform wall thickness would
result in an overdimensioning of the lever with regard to its
mechanical strength with a correspondingly superfluous mass.
SUMMARY
[0005] The object of the present invention is therefore to improve
a rocker arm of the above-noted type, so that the aforesaid
drawback is eliminated with simple measures and the rocker arm,
while retaining its simple manufacturability, possesses a
high-quality light-weight characteristic.
[0006] This objective is achieved according to the invention, with
advantageous developments and further features of the invention
being described in detail below and in the claims. According to the
invention, the contact surfaces extend on the crossbar while being
spaced in transverse direction from the side walls. As a result,
the dimensioning of the side wall thickness can be completely
uncoupled from the required width of the contact surfaces and
matched first and foremost to the required strength/rigidity of the
lever body.
[0007] According to a further aspect of the invention, the second
end section of the lever body comprises a joint socket for mounting
the rocker arm on a stationary joint head arranged in the internal
combustion engine, the rocker arm comprising a roller mounted on a
roller axle fixed in the axle-receiving bores. While the present
embodiment concerns the currently predominantly used valve train
kinematics including a rocker arm frequently also referred to as a
roller finger lever (as known, the roller serves as a low-friction
contact surface for a cam of a camshaft), it is possible,
alternatively, to also use a centrally mounted rocker arm whose
axle-receiving bores engage around a stationary rocker arm axle
arranged in the internal combustion engine, said rocker arm then
comprising, on its second end section, a cam-contacting surface
likewise in the form of a roller or a rigid sliding contacting
surface.
[0008] Besides this, as viewed in perpendicular direction to the
contact surfaces, the lever body can have a substantially T-shaped
configuration in that the crossbar comprises an inner section which
is connected to lower edges of the side walls facing the gas
exchange valves while extending between the side walls, and further
comprises two outer sections which are connected to upper edges of
the side walls turned away from the gas exchange valves and extend
away from each other.
[0009] The inner ends of the outer sections can be bent through
180.degree. and connected to the upper edges of the side walls
while extending parallel to the side walls and slightly spaced from
or in bearing relationship to the side walls. For achieving an
enhanced bending strength of the outer sections in direction of the
gas exchange valves, the inner ends of the outer sections are
welded to the side walls in the region of the lower edges of the
side walls.
[0010] Should a guidance of the rocker arm be required in
transverse direction, this can be realized on one or both of the
valve stems, in the first case particularly through provision of
valve guiding webs known form the prior art on both sides of one of
the contact surfaces. In the second case, it is possible either to
use an inner guidance of the rocker arm through valve guiding webs
extending within the intermediate space between the valve stems on
their opposing inner sides, or an outer guidance of the rocker arm
using valve guiding webs extending outside of the intermediate
space between the valve stems on their outer sides turned away from
each other. In the case of inner guidance, the side walls can serve
as valve guiding webs engaging between the inner sides of the valve
stems and, in the case of outer guidance, the valve guiding webs
can be formed by bending the outer ends of the outer sections of
the crossbar at a right angle in direction of the gas exchange
valves to engage around the gas exchange valves and serve as a
transverse guide of the rocker arm relative to the gas exchange
valves.
[0011] In an alternative embodiment of the rocker arm, the first
end section, together with the side walls widening into a T-shape
and the crossbar, forms a substantially H-shaped or U-shaped
cross-sectional profile. With regard to the aforesaid outer
guidance of the rocker arm, the invention preferably proposes that
the U-shaped cross-sectional profile be open in direction of the
gas exchange valves to engage around the gas exchange valves and
serve as a transverse guide of the rocker arm relative to the gas
exchange valves.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Further features of the invention will become apparent from
the following description and the appended drawings which
illustrate examples of embodiment of the invention. In the
drawings:
[0013] FIG. 1 is a perspective view of an embodiment of a rocker
arm according to the invention.
[0014] FIG. 2 is a perspective view of another embodiment of a
rocker arm according to the invention.
[0015] FIG. 3 is a perspective view of another embodiment of a
rocker arm according to the invention.
[0016] FIG. 4 is a perspective view of another embodiment of a
rocker arm according to the invention.
[0017] FIG. 5 is a perspective view of another embodiment of a
rocker arm showing only the lever body.
[0018] FIG. 6 is a perspective view of another embodiment of a
rocker arm according to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] If not otherwise stated, identical or functionally identical
features or components are designated by the same reference
numerals, or the reference numerals of these features or components
are omitted in individual figures.
[0020] The rocker arms identified at la to if in FIGS. 1 to 6 serve
for a simultaneous actuation of two gas exchange valves of an
internal combustion engine and comprise respectively, an elongate
lever body 2a to 2f formed in one piece by cold shaping out of
sheet metal and comprising a first end section 3, a center section
4 and a second end section 5. The center section 4 is formed by two
side walls 6a to 6f which, in this region, extend parallel to each
other and comprise aligned axle receiving bores 7, (see FIG. 5). A
roller axle 8 is fixed by staking, in a manner known per se, in the
axle receiving bores 7. The roller axle 8 serves to mount a roller
9 as a low-friction contacting surface for a cam of a camshaft. The
second end section 5 comprises a semispherical joint socket 10 for
a pivotal mounting of one end of the rocker arm 1a-1f on a
semispherical joint head of a support element that is arranged
stationary in the internal combustion engine. The first end section
3 comprises a crossbar 11a to 11f which connects the side walls
6a-6f and comprises two contact surfaces 12 for the valve stems.
The contact surfaces 12 extending in the figures on the underside
of the crossbars 11a to 11f are configured with a convex shape, in
a manner known per se, in the longitudinal direction of the lever
bodies 2a-2f and, according to the invention, extend spaced from
the side walls 6a to 6f in transverse direction.
[0021] Viewed in a direction perpendicular to the contact surfaces
12, i.e. in a top view, all the lever bodies 2a-2f are T-shaped due
to the fact that the first end section 3 is substantially wider
than the center section 4. The width of the center section 4 is
comprised only of the width of the roller 9, the axial lash of the
roller 9 between the side walls 6a to 6f and twice the wall
thickness of the side walls 6a to 6f. In contrast, as will be
elucidated later in connection with the rocker arms 1b, 1d and 1e,
the width of the first end section 3 corresponds at least to the
sum of the distance between the gas exchange valves, their valve
stem diameters and, where appropriate, also the valve guiding
webs.
[0022] In the rocker arms 1a-1d, the crossbar 11a-11d is formed by
one inner section 13a to 13d and two outer sections 14a to 14d. The
inner section 13a-13d extends between the side walls 6a to 6d and
connects these to each other in that it is connected to lower edges
of the side walls 6a to 6d facing the gas exchange valves. The two
outer sections 14a-14d which comprise a profile corresponding to
the convex contact surfaces 12 (see, in particular, FIG. 1) are
connected to upper edges of the side walls 6a-6d turned away from
the gas exchange valves and extend away from each other in
transverse direction of the rocker arm.
[0023] While the outer sections 14a, 14b of the lever bodies 2a, 2b
are bent through 90.degree. from the upper edges of the side walls
6a, 6b, the lever bodies 2c, 2d comprise outer sections 14c, 14d
whose inner ends, bent through 180.degree. , are connected to the
upper edges of the side walls 6c, 6d and extend at first in
parallel and in bearing relationship to the side walls 6c, 6d down
to the level of the inner sections 13c, 13d. A gaping-open of the
double-backed sheet metal produced by the valve forces acting on
the outer sections 14c, 14d is prevented by the fact that the inner
ends of the outer sections 14c, 14d are welded to the lower edges
of the side walls 6c, 6d. The weld joint identified at 15 in FIG. 4
is represented only symbolically.
[0024] The rocker arm 1e of FIG. 5--represented is only its lever
body 2e--comprises side walls 6e which widen in the region of the
first end section 3 into a T-shape and, together with the crossbar
11e which extends between the side walls 6e and is connected to the
upper edges of the side walls 6e, form a U-shaped cross-sectional
profile which is open toward the gas exchange valves. The guidance
of the rocker arm le in transverse direction is affected through
outer guidance by the fact that the U-shaped cross-sectional
profile of the lever body 2e engages around the valve stems.
[0025] The invention also provides an outer guidance relative to
the gas exchange valves in the case of the rocker arms 1b and 1d.
For this purpose, the outer ends of the outer sections 14b, 14d are
bent at right angles in direction of the gas exchange valves to
serve as valve guiding webs engaging around the outer sides of the
valve stems. In contrast, the transverse guidance of the rocker arm
la is realized through inner guidance on the side walls 6a which
engage in the region of the first end section 3 between the inner
sides of the valve stems.
[0026] The rocker arm if illustrated in FIG. 6 comprises a
beam-like straight crossbar 11f that is connected to the lower
edges of the side walls 6f.
LIST OF REFERENCE NUMERALS
[0027] 1 Rocker arm [0028] 2 Lever body [0029] 3 First end section
[0030] 4 Center section [0031] 5 Second end section [0032] 6 Side
wall [0033] 7 Axle-receiving bore [0034] 8 Roller axle [0035] 9
Roller [0036] 10 Joint socket [0037] 11 Crossbar [0038] 12 Contact
surface [0039] 13 Inner section of crossbar [0040] 14 Outer section
of crossbar [0041] 15 Weld joint
* * * * *