U.S. patent application number 14/047382 was filed with the patent office on 2014-04-17 for sliding cam arrangement for variable actuating gas exchange valves of an internal combustion engine.
This patent application is currently assigned to Dr. Ing. h.c. F. Porsche Aktiengesellschaft. The applicant listed for this patent is Dr. Ing. h.c. F. Porsche Aktiengesellschaft. Invention is credited to Frank Ickinger, Steffen Matthias Kappler.
Application Number | 20140102391 14/047382 |
Document ID | / |
Family ID | 50383043 |
Filed Date | 2014-04-17 |
United States Patent
Application |
20140102391 |
Kind Code |
A1 |
Kappler; Steffen Matthias ;
et al. |
April 17, 2014 |
SLIDING CAM ARRANGEMENT FOR VARIABLE ACTUATING GAS EXCHANGE VALVES
OF AN INTERNAL COMBUSTION ENGINE
Abstract
A sliding cam arrangement for the variable actuation of gas
exchange valves of an internal combustion engine, having a camshaft
which has toothing regions with an external toothing, wherein the
toothing regions mesh in each case with an internal toothing of a
cam carrier, wherein the ratio of base circle radius R2 of the cam
carrier to tip circle radius R1 of the toothing of the camshaft
satisfies the following criteria: R2/R1<1.55.
Inventors: |
Kappler; Steffen Matthias;
(Neidlingen, DE) ; Ickinger; Frank; (Pleidelsheim,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Dr. Ing. h.c. F. Porsche Aktiengesellschaft |
Stuttgart |
|
DE |
|
|
Assignee: |
Dr. Ing. h.c. F. Porsche
Aktiengesellschaft
Stuttgart
DE
|
Family ID: |
50383043 |
Appl. No.: |
14/047382 |
Filed: |
October 7, 2013 |
Current U.S.
Class: |
123/90.17 |
Current CPC
Class: |
F01L 13/0036 20130101;
F01L 2001/0473 20130101; F01L 1/34413 20130101; F01L 2013/0052
20130101 |
Class at
Publication: |
123/90.17 |
International
Class: |
F01L 1/344 20060101
F01L001/344 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 11, 2012 |
DE |
102012109690.2 |
Claims
1. A sliding cam arrangement for variable actuation of gas exchange
valves of an internal combustion engine, comprising a camshaft
having toothing regions with an external toothing, wherein the
toothing regions mesh with an internal toothing of a cam carrier,
wherein a ratio of a base circle radius R2 of the cam carrier to a
tip circle radius R1 of the toothing of the camshaft is less than
1.55.
2. The sliding cam arrangement as claimed in claim 1, wherein the
ratio is between 1.2 and 1.55.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to German Patent
Application No. 10 2012 109 690.2, filed Oct. 11, 2012, which is
incorporated by reference herein in its entirety.
FIELD OF THE INVENTION
[0002] The invention relates to a sliding cam arrangement for the
variable actuation of gas exchange valves of an internal combustion
engine, having a camshaft which has toothing regions with an
external toothing, wherein the toothing regions mesh in each case
with an internal toothing of a cam carrier.
BACKGROUND OF THE INVENTION
[0003] Sliding cam arrangements of said type are well known from
the prior art. For example, DE 10 2008 035 935 A1, which is
incorporated by reference herein, discloses a sliding cam
arrangement which has a camshaft with toothing regions, on which
camshaft there are provided in each case cam carriers with two cams
which engage with a respective gas exchange valve. To effect a
displacement of the respective cam carrier, actuators are provided
which, by means of drivers and grooves provided on the cam
carriers, permit a displacement of the cam carriers in an axial
direction. In the automotive field, the optimization of
installation space and weight is of ever greater importance in
particular against the background of increasing engine efficiency.
Against this background, efforts made for the optimization of
camshaft arrangements have been directed in particular to material
optimization and improvements. It has nevertheless been found that
the existing sliding cam arrangements have a considerable need for
improvement in particular with regard to the adverse effects of the
mass moment of inertia of the cam carriers.
SUMMARY OF THE INVENTION
[0004] Described herein is a sliding cam arrangement which exhibits
improved dynamic behavior in an inexpensive manner which is
expedient with regard to assembly.
[0005] The ratio of a base circle radius R2 of the cam carrier to a
tip circle radius R1 of the toothing of the camshaft satisfies the
following criteria: R2/R1<1.55. The mass inertia behavior of the
sliding cam arrangement can be improved significantly in this way.
Furthermore, the actuators require less power to displace the
respective cam carrier, which yields an installation space
reduction and cost savings with regard to the actuators too. Also,
a camshaft which must possibly be produced with a relatively large
diameter, because predefined spacings to the gas exchange valves
must be maintained in the cylinder head, does not have an adverse
effect on the overall performance of the sliding cam arrangement
according to the invention. It has proven to be particularly
advantageous for the ratio R2 to R1 to lie in the range from 1.2 to
1.55.
BRIEF DESCRIPTION OF THE DRAWING
[0006] The invention will be explained in more detail below on the
basis of a drawing, in which:
[0007] FIG. 1 shows a top view of a sliding cam arrangement for a
part of a six-cylinder V-configuration engine,
[0008] FIG. 2 shows a sectional view through a sliding cam
arrangement in the region of a cam carrier according to the prior
art, and
[0009] FIG. 3 shows a section through a sliding arrangement
according to the invention in the region of a cam carrier.
DETAILED DESCRIPTION OF THE DRAWING
[0010] FIG. 1 shows a top view of a sliding cam arrangement 2 for
one bank of a six-cylinder V-configuration engine, of which three
cylinders 4 are illustrated here. In a known way, toothing regions
10 which have an external toothing 12 (in this regard, see FIGS. 2
and 3) and which mesh in each case with an internal toothing 14 of
a cam carrier 16 are provided, between bearings 8, on a camshaft 6.
In the present exemplary embodiment, a cam carrier is provided for
two gas inlet valves (not illustrated in any more detail) and in
this case has grooves 18 which interact with drivers 20 of an
actuator 22 such that the respective cam carriers 16 are
displaceable in the axial direction on the camshaft 6. Each cam
carrier 16 also has a cam pair 24, 26 with cams 28, 30 which can in
each case be placed in engagement with the associated gas exchange
valve and accordingly generate a different lift characteristic of
the gas exchange valve. For completeness, it is also pointed out
that the component denoted by reference signs 32 is a sprocket for
driving the camshaft 6.
[0011] FIG. 2 now shows a sectional view through a sliding cam
arrangement 2 according to the prior art. It is possible here to
clearly see the camshaft 6 on which the cam carrier 16 with the cam
30 is arranged. The camshaft has an external toothing 12 which
meshes with the internal toothing 14 of the cam carrier 16.
Reference 34 denotes the tip circle of the toothing. In the case of
a sliding cam arrangement according to the prior art, the ratio of
R2 (base circle radius) to R1 (tip circle radius of the toothing)
is generally in any case >1.5, and in particular 1.6 to 1.8. It
should be clear that R1 denotes the radius from the central point
of the camshaft 6 to the tip circle of the external toothing 12,
and R2 denotes the radius from the central point of the camshaft 6
to the base circle of the cam carrier 16.
[0012] FIG. 3 now shows the ratio of R2 to R1 in the case of the
sliding cam arrangement 2 according to the invention. Here, the
ratio, in the case of a corresponding base circle radius R2, is
<1.55, and in the exemplary embodiment is 1.33. Even though the
camshaft has a relatively high weight as a result of the increased
diameter, the sliding cam arrangement 2 as a whole exhibits
significantly improved dynamic behavior, wherein it was possible to
realize a considerable weight saving as a result of the modified
cam carriers 16. It should be clear that, where permitted by the
installation-space-specific and engine-specific situation, the
camshaft 6 may self-evidently also be formed with a smaller
diameter, wherein an even greater weight optimization can be
attained while maintaining the ratio R2 to R1.
* * * * *