U.S. patent application number 13/192881 was filed with the patent office on 2012-02-09 for internal combustion engine.
This patent application is currently assigned to Dr. Ing. h.c. F. Porche Aktiengesellschaft. Invention is credited to Joachim Grunberger, Frank Ickinger.
Application Number | 20120031361 13/192881 |
Document ID | / |
Family ID | 45494974 |
Filed Date | 2012-02-09 |
United States Patent
Application |
20120031361 |
Kind Code |
A1 |
Ickinger; Frank ; et
al. |
February 9, 2012 |
INTERNAL COMBUSTION ENGINE
Abstract
Disclosed herein is an internal combustion engine having a
plurality of cylinders, a crankcase, a cylinder head and a
cylinder-head cover, the cylinder head being formed from a
cylinder-head lower part and a camshaft housing which is positioned
between the cylinder-head cover and the cylinder-head lower part,
and at least one camshaft and one sliding cam which can be
displaced axially on the camshaft and has a slotted-guide section
being provided for actuating gas exchange valves of the internal
combustion engine, an actuator with an actuable pin being provided
for bringing about an axial displacement of the sliding cam. The
camshaft and the sliding cam are positioned in the camshaft
housing. The camshaft, which is mounted rotatably for valve
actuation, is arranged with the axially displaceable sliding cam in
the camshaft housing in such a way that they can be attached to the
cylinder-head lower part as one preassembled unit.
Inventors: |
Ickinger; Frank;
(Pleidelsheim, DE) ; Grunberger; Joachim;
(Sachsenheim, DE) |
Assignee: |
Dr. Ing. h.c. F. Porche
Aktiengesellschaft
Stuttgart
DE
|
Family ID: |
45494974 |
Appl. No.: |
13/192881 |
Filed: |
July 28, 2011 |
Current U.S.
Class: |
123/90.18 |
Current CPC
Class: |
F01L 13/0042 20130101;
F01L 1/053 20130101 |
Class at
Publication: |
123/90.18 |
International
Class: |
F01L 1/34 20060101
F01L001/34 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 6, 2010 |
DE |
102010036899.7 |
Claims
1.-9. (canceled)
10. An internal combustion engine comprising: a plurality of
cylinders, a crankcase, a cylinder head and a cylinder-head cover,
the cylinder head being formed from a cylinder-head lower part and
a camshaft housing which is positioned between the cylinder-head
cover and the cylinder-head lower part, and at least one camshaft;
at least one sliding cam which is configured to be displaced
axially on the at least one camshaft and has a slotted-guide
section for actuating gas exchange valves of the internal
combustion engine; and at least one actuator with an actuable pin
for bringing about an axial displacement of the at least one
sliding cam; wherein the camshaft and the sliding cam are
positioned in the camshaft housing, wherein the camshaft, which is
mounted rotatably for valve actuation, is configured to be
assembled with the axially displaceable sliding cam in the camshaft
housing in such a way that the camshaft, the sliding cam and the
camshaft housing form one preassembled unit which is configured to
be attached to the cylinder-head lower part.
11. The internal combustion engine as claimed in claim 10, wherein
the actuator which is provided for bringing about the axial
displacement of the sliding cam is arranged in a lateral region of
the camshaft housing.
12. The internal combustion engine as claimed in claim 10, wherein
the camshaft housing includes a plurality of laterally positioned
openings for receiving the actuator.
13. The internal combustion engine as claimed in claim 10, wherein
each sliding cam is assigned an individual actuator per cylinder
for the actuation of inlet-side gas exchange valves or outlet-side
gas exchange valves, the sliding cam and the actuator being
positioned in the camshaft housing spatially between two bearing
points of the camshaft.
14. The internal combustion engine as claimed in claim 10, wherein
at least two gas exchange valves are configured to be actuated by
way of one sliding cam, wherein the slotted-guide section that is
arranged on the sliding cam is positioned between two cam sections
which, in each case, serve for actuating the gas exchange valves
and, in each case, have a plurality of cam tracks.
15. The internal combustion engine as claimed in claim 10, wherein
a camshaft adjusting device and/or at least one drive wheel are/is
attached at one end of the camshaft.
16. The internal combustion engine as claimed in claim 15, wherein
the camshaft adjusting device and the drive wheel are connected to
the camshaft and are arranged in the camshaft housing in order to
form a part of the preassembled unit.
17. The internal combustion engine as claimed in claim 15, wherein
the camshaft adjusting device is driven electrically.
18. The internal combustion engine as claimed in claim 10, wherein
the camshaft housing has a plurality of bearing devices for
mounting a plurality of camshafts, which bearing devices are
configured in one piece with the camshaft housing.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This U.S. patent application claims priority to German
Patent Application DE102010036899.7, filed Aug. 6, 2010, which is
incorporated by reference herein in its entirety.
FIELD OF THE INVENTION
[0002] The invention relates to an internal combustion engine
having a plurality of cylinders.
BACKGROUND OF THE INVENTION
[0003] In modern internal combustion engines, variable valve timing
mechanisms are used to optimize the charge movement in the
combustion chamber, by way of which variable valve timing
mechanisms different valve strokes can be set for the gas exchange
valves of the internal combustion engine. DE 196 11 641 C1, which
is incorporated by reference herein, has disclosed a valve timing
mechanism of an internal combustion engine, by way of which valve
timing mechanism the actuation of a gas exchange valve with a
plurality of different lifting cams is made possible. To this end,
a sliding cam with a plurality of cam tracks is mounted fixedly on
the camshaft so as to rotate with it but so as to be displaceable
axially, which sliding cam has a lifting contour, into which an
actuating element engages in the form of a pin for generating an
axial displacement of the cam. As a result of the axial
displacement of the cam, a different valve stroke is set for the
respective gas exchange valve.
[0004] DE 10 2007 027 979 A1, which is incorporated by reference
herein, has described a valve timing mechanism for gas exchange
valves of an internal combustion engine with a camshaft tunnel
bearing, which valve timing mechanism comprises cam pieces which
can be displaced on a camshaft, a radial bearing of the camshaft
being positioned between two sliding-cam pieces which are provided
for the actuation of gas exchange valves of a cylinder. The
previously known mountings of a valve timing mechanism with a
sliding-cam assembly are complicated and afford restricted
flexibility.
SUMMARY OF THE INVENTION
[0005] Disclosed herein is a simplified arrangement of a valve
timing mechanism in a cylinder head of an internal combustion
engine, in particular with regard to the positioning and the
mounting of a sliding-cam system in the cylinder head.
[0006] According to one aspect of the invention, an internal
combustion engine has a plurality of cylinders, a crankcase, a
cylinder head and a cylinder-head cover, the cylinder head being
formed from a cylinder-head lower part and a camshaft housing which
is positioned between the cylinder-head cover and the cylinder-head
lower part, and at least one camshaft and one sliding cam which can
be displaced axially on the camshaft and has a slotted-guide
section being provided for actuating gas exchange valves of the
internal combustion engine, an actuator with an actuable pin being
provided for bringing about an axial displacement of the sliding
cam, characterized in that the camshaft and the sliding cam are
positioned in the camshaft housing, it being possible for the
camshaft which is mounted rotatably for valve actuation to be
assembled with the axially displaceable sliding cam in the camshaft
housing in such a way that the camshaft, the sliding cam and the
camshaft housing form one preassembled unit which can be attached
to the cylinder-head lower part.
[0007] The internal combustion engine is distinguished by the fact
that the camshafts and the sliding cams are positioned in the
camshaft housing, it being possible for the camshaft which is
mounted rotatably for valve actuation to be assembled with the
axially displaceable sliding cam in the camshaft housing in such a
way that the camshaft, the sliding cam and the camshaft housing
together form one preassembled unit which can be attached to the
cylinder-head lower part. Advantageous accommodation of a valve
timing mechanism therefore takes place with a compact sliding-cam
device for the actuation of the gas exchange valves of a cylinder
in a camshaft housing, which can be preassembled before the
attachment of the camshaft housing to the cylinder-head lower part
is carried out. This leads to simplified assembly of the internal
combustion engine and therefore makes reliable, quality-assured and
inexpensive production of the internal combustion engine possible
on account of the simplified handling and the unit which is tested
in advance and is preassembled.
[0008] As claimed in one refinement of the invention, the actuators
which are provided for bringing about the axial displacement of the
sliding cam are arranged in a lateral region of the camshaft
housing. To this end, a lateral wall of the camshaft housing is
expediently provided with a plurality of openings arranged in it
for receiving the actuators. As a result of the lateral arrangement
of the actuators, they can be introduced into the camshaft housing
with less outlay than previously and the construction tolerances
can be reduced, the said actuators then being accommodated in such
a way that an overall height of a cylinder head is reduced to a
minimum. This therefore brings about a particularly compact and
simplified arrangement of the internal combustion engine, the
connecting options of the actuators, for example to a control unit
of the internal combustion engine, being simplified by the lateral
openings which are provided to accommodate the actuators. Moreover,
the design of the cylinder-head cover, in particular, can be of
simplified configuration.
[0009] As claimed in one preferred refinement of the invention,
each sliding cam is assigned an individual actuator per cylinder
for the actuation of the inlet-side or outlet-side gas exchange
valves. In particular, the sliding cam and the actuator are
positioned in the camshaft housing spatially between two bearing
points of the camshaft. At least two or three gas exchange valves
can preferably be actuated by way of one sliding cam per cylinder,
the slotted-guide section which is arranged on the sliding cam
being positioned between two cam sections which in each case serve
for the actuation of the gas exchange valves and in each case have
a plurality of cam tracks. As a result, there is a compact
sliding-cam form, by way of which the actuation of two gas exchange
valves which are positioned close to one another can be brought
about in a functionally reliable manner.
[0010] In a further refinement of the invention, the camshaft
adjusting device and the drive wheel are connected to the camshaft,
are arranged in the camshaft housing and advantageously form a part
of the preassembled unit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Further features and combinations of features result from
the description. Concrete exemplary embodiments of the invention
are shown in simplified form in the drawing and are explained in
greater detail in the following description. In the drawing:
[0012] FIG. 1 shows a diagrammatically illustrated internal
combustion engine of the boxer type,
[0013] FIG. 2 shows a sectional view of the cylinder head of the
internal combustion engine from FIG. 1,
[0014] FIG. 3 shows a further sectional view of the cylinder head
of the internal combustion engine from FIG. 1,
[0015] FIG. 4 shows a perspective view of a camshaft housing of the
internal combustion engine from FIG. 1 according to a first
embodiment,
[0016] FIG. 5 shows a further perspective view of the internal
combustion engine from FIG. 1 according to the first
embodiment,
[0017] FIG. 6 shows a perspective view of a camshaft housing of the
internal combustion engine as shown in FIG. 1, according to a
second embodiment, and
[0018] FIG. 7 shows a perspective view of the camshaft housing of
the internal combustion engine as shown in FIG. 1, with bearing
devices which are configured integrally on the camshaft
housing.
DETAILED DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 shows an internal combustion engine 1 of the boxer
type which is formed from two cylinder rows 1a and 1b which are
arranged horizontally. The internal combustion engine 1 comprises a
crankcase 2 and in each case one cylinder head 3 per cylinder row
1a and 1b, which cylinder head 3 is delimited to the outside by a
cylinder-head cover 4. The cylinder head 3 is assembled from a
cylinder-head lower part 5 and a camshaft housing 6.
[0020] As shown in FIG. 2, an inlet camshaft 7 and an outlet
camshaft 8 are mounted in the camshaft housing 6 for controlling
gas exchange valves of the internal combustion engine 1. The
camshaft housing 6 is attached as one preassembled unit to the
cylinder-head lower part 5 and is screwed to the latter. After the
mounting of the camshaft housing 6 on the cylinder-head lower part
5, the cylinder-head cover 4 is attached to the camshaft housing 6.
A plurality of bolts 12 are provided for fastening the
cylinder-head cover 4 to the camshaft housing 6.
[0021] Two inlet valves 9 and two outlet valves 10 are provided per
cylinder, the inlet valves 9 being actuated in a controlled manner
by the inlet camshaft 7 in a known way. The outlet valves 10 are
actuated in a controlled manner by the outlet camshaft 8. To this
end, the inlet camshaft 7 and the outlet camshaft 8 mounted in the
camshaft housing 6 in each case have a plurality of sliding cams
13. FIG. 3 shows a sectional view through the inlet camshaft 7
which actuates the two inlet valves 9 with the aid of roller drag
levers 21. As shown in FIG. 3, the sliding cam 13 is formed from a
slotted-guide section 15 which is positioned in the center and two
outer cam sections 14. Each outer cam section 14 comprises three
cam tracks 17, by way of each of which a different valve stroke is
set. As an alternative, two cam tracks can be arranged instead of
three on each outer cam section 14.
[0022] As can be seen in FIG. 4 or 5, each sliding cam 13 is
assigned an actuator 16 which has an extendable pin (not shown)
which interacts with the slotted-guide section 15. As a result, an
axial displacement of the sliding cam 13 takes place in a region
between two camshaft bearings. As a result of the axial
displacement of the sliding cam 13, the respective valve is
actuated in a targeted manner by way of a defined cam track, with
the result that a different valve stroke setting takes place. The
function of the displaceable cam 13 can be designed, for example,
as described in document DE 196 11 641 C1.
[0023] The sliding cam 13 which is shown in FIG. 3 comprises three
cam tracks 17 which are axially displaceable for each valve. As an
alternative, two cam tracks instead of three can be arranged for
each valve. In each case one camshaft adjusting device 18 and one
drive wheel 19 as shown in FIG. 4 are attached at one end of each
camshaft 7, 8. The camshaft adjusting device 18 is actuated
hydraulically or electrically, by way of which a camshaft angle is
adjusted, in order to change the control times of the internal
combustion engine. The drive wheel 19 is configured as a chain
sprocket and serves to drive the respective camshaft. To this end,
the drive wheel 19 is coupled via a drive chain (not shown) to a
crankshaft (not shown) of the internal combustion engine 1.
[0024] In order to mount the camshafts 7 and 8, in each case three
radial bearing devices 20 are provided, for example, which comprise
a lower bearing-ring body 23 which is configured in one piece with
the camshaft housing 6. In the case of an internal combustion
engine of V design with 8 cylinders, four radial bearing devices 20
are provided, for example. Furthermore, each radial bearing device
20 comprises an individual bearing cap 22 which is fastened with
the lower ring to the camshaft housing 6 with the aid of, for
example, two bolts. As an alternative, the individual bearing caps
as shown in FIG. 7 are configured in one piece with the camshaft
housing 6. In this case, there is a tunnel-like radial bearing
device 20a. Here, the respective camshaft 7 or 8 is pushed in
through a corresponding opening 28 for mounting on the camshaft
housing 6. The sliding cams 13 are brought into position at the
corresponding point between the respective radial bearing devices
20a, in such a way that the respective camshaft 7 or 8 is then
pushed into them.
[0025] The camshafts 7 and 8 are preassembled on the camshaft
housing 6 and are connected to the respective camshaft adjuster 18
and the drive wheel 19. After this, there is a preassembled
camshaft housing unit which is attached to the cylinder-head lower
part 5 in a single mounting step.
[0026] The camshaft housing 6 comprises two end sections 24 and 25,
between which two lateral walls or edge parts 26 and 27 extend. The
camshafts 7 and 8 extend in the axial direction parallel to the
lateral walls 26 and 27 and are delimited in the axial direction by
the two end sections 24 and 25.
[0027] FIG. 4 shows a first exemplary embodiment of the present
invention. FIG. 4 shows the preassembled camshaft housing 6
together with the camshafts 7 and 8. The parts cylinder-head cover
4, camshaft housing 6 and cylinder-head lower part 5 which are
screwed together are shown in FIG. 2. In each case one individual
sliding cam 13 is provided for each cylinder both on the inlet
camshaft 7 and on the outlet camshaft 8, between which sliding cam
13 and the respective gas exchange valve in each case one roller
drag lever 21 is arranged.
[0028] The sliding cams 13 which are connected fixedly to the
respective camshaft so as to rotate with it make a valve stroke
adjustment possible. The camshaft angle can be changed by the
respective camshaft adjusting device. The camshaft 7 and 8 is
driven by the drive wheel 19. Depending on the operating point of
the internal combustion engine 1, targeted adjustment of the valve
stroke and/or of the camshaft angle is performed, in order to
achieve a best possible degree of efficiency of the internal
combustion engine 1 at the respective operating point.
[0029] In the exemplary embodiment which is shown in FIG. 4 and
FIG. 5, the actuators 16 are positioned laterally in the camshaft
housing 6, preferably in the respective lateral wall 26 and 27. To
this end, as shown in FIG. 5, in each case one corresponding
opening 29 is provided on the lateral wall 26 and 27 of the
camshaft housing 6, through which opening 29 the respective
actuator 16 is pushed in. As a result of the lateral arrangement of
the actuators 16, an overall height of the camshaft housing 6 is
reduced to a minimum. An arrangement of this type is advantageous,
in particular, in boxer engines, since they have cylinders which
lie horizontally in the vehicle and require more installation space
in the width direction than, for example, inline engines or V
engines.
[0030] FIG. 6 shows a second exemplary embodiment of the present
invention, in which the actuators 16 are positioned in the camshaft
housing 6 above the camshafts 7 and 8. An arrangement of this type
is suitable, in particular, for internal combustion engines of V
design or inline design.
[0031] The alternative which is shown in FIG. 7 is suitable for
both exemplary embodiments of the invention. Here, the individual
bearing caps as shown in FIG. 7 are configured in one piece with
the camshaft housing 6, with the result that the respective radial
bearing device is of tunnel-like configuration.
[0032] A three-stage sliding-cam system for an internal combustion
engine 1 with simplified assembly is provided by way of the present
invention, in which sliding-cam system a sufficient bearing width
of the radial bearings 20 can be provided for the camshafts 7 and 8
in the case of low or small valve and cylinder spacings. As a
result of the accommodation of the actuators 16 in the camshaft
housing 6, the tolerances for the function of the sliding cams 13
can be kept low, since the machining of the camshaft bearings 20
and the machining operations for receiving the actuator system and
the camshaft adjusting device 18 can be carried out in one
component. Moreover, the camshaft housing 6 can be delivered with
the preassembled camshafts 7, 8 and actuators 16 as one unit during
the production of the internal combustion engine 1.
* * * * *