U.S. patent application number 09/747076 was filed with the patent office on 2001-10-18 for device for changing the control timing of the gas exchange valves of an internal combustion engine, in particular a hydraulic camshaft adjustment device of the rotary piston type.
Invention is credited to Kapp, Matthias, Schafer, Jens, Scheidt, Martin, Steigerwald, Martin.
Application Number | 20010029914 09/747076 |
Document ID | / |
Family ID | 7934484 |
Filed Date | 2001-10-18 |
United States Patent
Application |
20010029914 |
Kind Code |
A1 |
Scheidt, Martin ; et
al. |
October 18, 2001 |
Device for changing the control timing of the gas exchange valves
of an internal combustion engine, in particular a hydraulic
camshaft adjustment device of the rotary piston type
Abstract
A hydraulic camshaft-adjusting device of the rotary piston type
having a drive gear (2) and an impeller. The drive gear (2) has a
cavity formed from a perimeter wall and two side walls (5, 6)
inside of which at least one hydraulic working chamber is formed
from at least two boundary walls (8). The impeller has a wheel hub
(10) with at least one vane that extends into a working chamber,
dividing the chamber into two associated hydraulic pressure
chambers. The pressure medium feed to and from the pressure
chambers is done using a pressure medium tap (16) on the side
facing a camshaft as well as using pressure medium channels (17)
incorporated into the axial sides (14, 15) of the wheel hub (10) of
the impeller, which are connected to the pressure medium tap
through a pressure medium distributor (20). The pressure medium tap
(16) and the pressure medium distributor (20) are encircled at the
head (19) and the outer surface (21) by a respective penetration
(22, 23) in the side walls (5, 6) of the drive gear (2). The gaps
between the head (19) of the pressure medium distributor (20) at
the penetration (22) of the one side wall (5) of the drive gear (2)
and/or between the outer surface (21) of the pressure medium tap
(16) and the penetration (23) at the other side wall (6) of the
drive gear (2) are sealed off through wear-resistant sealing media
against pressure medium leakage
Inventors: |
Scheidt, Martin;
(Beethovenstr, DE) ; Schafer, Jens;
(Herzogenaurach, DE) ; Kapp, Matthias; (Nurnbeg,
DE) ; Steigerwald, Martin; (Herzogenaurach,
DE) |
Correspondence
Address: |
VOLPE AND KOENIG, P.C.
SUITE 400, ONE PENN CENTER
1617 JOHN F. KENNEDY BOULEVARD
PHILADELPHIA
PA
19103
US
|
Family ID: |
7934484 |
Appl. No.: |
09/747076 |
Filed: |
December 22, 2000 |
Current U.S.
Class: |
123/90.15 |
Current CPC
Class: |
F01L 1/3442 20130101;
F16D 3/10 20130101; Y10T 74/2102 20150115 |
Class at
Publication: |
123/90.15 |
International
Class: |
F01L 001/34 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 24, 1999 |
DE |
199 62 981.1 |
Claims
What is claimed is:
1. A device for changing the control timing of gas exchange valves
of an internal combustion engine, comprising: a drive gear (2)
adapted for direct connection to a crankshaft of the internal
combustion engine and an impeller (3) adapted for direct connection
to a camshaft of the internal combustion engine, the drive gear (2)
has a cavity (7) formed by a hollow cylindrical perimeter wall (4)
and two side walls (5, 6) inside of which at least one hydraulic
working chamber (9) is formed by at least two boundary walls (8),
the impeller (3) has a wheel hub (10) with at least one vane (11)
at a perimeter thereof that extends radially into the working
chamber (9) of the drive gear (2) that divides the working chamber
(9) into two respective hydraulic pressure chambers (12, 13) that
counteract one another, the pressure chambers (12, 13) are adapted
to effect a pivoting motion or a fixing of the impeller (3) with
respect to the drive gear (2), and thus of the camshaft with
respect to the crankshaft, by selective or simultaneous application
of pressure through a hydraulic pressure medium feed, a pressure
medium tap (16) lying at the axial side (14 or 15) of the wheel hub
(10) of the impeller (3) facing toward or away from the camshaft
and pressure medium channels (17, 18) located in both axial sides
(14, 15) of the wheel hub (10) of the impeller (3) that form the
pressure medium feed to and from the pressure chambers (12, 13),
the pressure medium tap (16) and the pressure medium channels (17,
18) are connected to one another through a pressure medium
distributor (20) penetrating the impeller (3) along a longitudinal
axis thereof and lying by means of a head (19) against the axial
side (15 or 14) of the wheel hub (10) of the impeller (3) facing
away from or toward the camshaft, the pressure medium tap (16) and
the pressure medium distributor (20) are adapted to be connected
directly to the camshaft and are partially enclosed at the head
(19) and the outer surface (21) by a respective coaxial penetration
(22, 23) in the side walls (5, 6) of the drive gear (2), wherein,
wear-resistant sealing media are used to seal a gap located between
the head (19) of the pressure medium distributor (20) and the
penetration (22) of the one side wall (5) of the drive gear (2)
and/or between the outer surface (21) of the pressure medium tap
(16) and the penetration (23) of the other side wall (6) of the
drive gear (2) against external pressure medium leakage.
2. A device according to claim 1, wherein the sealing media is
found as a slitted steel sealing ring (24, 25) or as a lamellar
sealing ring that is located in a circular radial notch (26, 27)
located in the head (19) of the pressure medium distributor (20)
and/or in the outer surface (21) of the pressure medium tap
(16).
3. A device according to claim 1, wherein the sealing media is
formed as a circular sealing washer (28, 29) located in a circular
axial notch (30, 31) formed as a recess at the penetration (22, 23)
of the side walls (5, 6) and at the head (19) of the pressure
medium distributor (20) and/or at the outer surface (21) of the
pressure medium tap (16).
Description
BACKGROUND
[0001] The invention pertains to a device for changing the control
timing of gas exchange valves of an internal combustion engine
according to the features of the preamble of claim 1, which is
particularly advantageous for application in hydraulic camshaft
adjusting devices of the rotary piston type.
[0002] A device of this type is known from German patent DE 198 08
619 A1, which generally defines this class. This device, designed
as a so-called vane-cell positioning device is formed essentially
of a drive gear directly connected to a crankshaft of the internal
combustion engine and an impeller that is directly connected to a
camshaft of the internal combustion engine. The drive gear has a
cavity formed by a hollow cylindrical perimeter wall and two
sidewalls, inside of which four hydraulic working chambers are
formed from four boundary walls. The impeller has at the perimeter
of its wheel hub four vanes, each of which extends radially into a
working chamber of the drive gear. These four vanes divide each of
the working chambers into two counteracting hydraulic pressure
chambers. By selectively or simultaneously applying pressure using
a hydraulic pressure medium, these pressure chambers effect a
pivoting motion or a fixing of the impeller with respect to the
drive gear, and thus the camshaft with respect to the crankshaft.
The pressure medium feed to and from the pressure chambers of this
device is done by means of a pressure medium tap lying at the axial
side of the wheel hub of the impeller facing the camshaft, which is
designed as a specialized pressure medium adapter, from a camshaft
bearing in the cylinder head of the internal combustion engine. It
is also done using pressure medium channels incorporated into both
axial sides of the wheel hub of the impeller. These pressure medium
channels are connected to the pressure medium tap through a
pressure medium distributor penetrating the impeller along its
longitudinal axis that is designed in this device as a specialized
pressure medium feed bushing. One end of the bushing lies against
the axial side of the wheel hub of the impeller that is facing away
from the camshaft. The pressure medium tap and the pressure medium
distributor are, just as the impeller is, directly bolted to the
camshaft by means of a central fastening screw and are each
partially enclosed at the head and at the outer surface by a
coaxial penetration in the side walls of the drive gear. The gap
between the head of the pressure medium distributor and the
penetration in the one side wall of the drive gear is sealed
against external pressure media leakage by an O-ring in an annular
notch in the head of the pressure medium distributor, whereas the
gap between the outer surface of the pressure medium tap and the
penetration in the other side wall of the drive gear is designed as
a sealing gap.
[0003] The disadvantage in this known device is that, on the one
hand, relatively large play must exist between the head of the
pressure medium distributor and the penetration in the one side
wall of the drive gear as well as between the outer surface of the
pressure medium tap and the penetration in the other side wall of
the drive gear so as to prevent a bearing site from occurring at
these places. On the other hand, however, the external pressure
medium leakages through the gaps at these places are limited,
mainly so that less pressure medium has to be fed in the controlled
positions of the camshaft-adjusting device. In practice, the
O-rings used and the sealing gaps have proven to be unsuitable as a
means to seal gaps since the pressure medium channels to the
pressure chambers of the device are incorporated into the axial
sides of the wheel hub of the impeller. Thus, the pressure of the
pressure medium is felt repeatedly at the perimeter of the gaps
depending on the number of pressure chambers. As a result, in
sealing gaps, the external pressure medium leakages are always
still too high, whereas O-rings are so highly compressed by the
pressure of the pressure medium that the friction between the
pressure medium distributor and the side wall of the drive gear
increases. This then leads to higher wear of the O-rings and in the
worst case to a worsening of the adjustment speed of the
camshaft-adjustment device. Moreover, O-rings have also been shown
to be disadvantageous with respect to their embrittlement at high
and low temperatures as well as with respect to their incidence of
tears and other damage.
SUMMARY
[0004] The object of this invention is to provide a device for
changing the control timing of gas exchange valves of an internal
combustion engine, in particular a hydraulic camshaft adjustment
device of the rotary piston type, whereby the disadvantages of the
known state of the art, are avoided, such as the external pressure
medium leakages through the gap between the head of the pressure
medium distributor and the penetration of the one side wall of the
drive gear and between the outer surface of the pressure medium tap
and the penetration of the other side wall of the drive gear are
reduced to a minimum.
[0005] According to the invention, this object is met by a device
according to the preamble of claim 1 in that the gap between the
head of the pressure medium distributor and the penetration of the
one side wall of the drive gear and between the outer surface of
the pressure medium tap and the penetration of the other side wall
of the drive gear are sealed off against pressure medium leakage
using wear-resistant sealing media.
[0006] In a first advantageous embodiment of the device according
to the invention, these sealing media are provided preferably as
slitted steel sealing rings or as lamellar sealing rings which are
each placed in a circular radial notch in the head of the pressure
medium distributor and in the outer surface of the pressure medium
tap.
[0007] Here, the pressure medium distributor is preferably formed
from a specialized pressure medium guide bushing that coaxially
penetrates the impeller. This feed bushing has at one end a bushing
head in which the one radial circular notch for the steel or
lamellar sealing ring is located. On the other hand, the pressure
medium tap is preferred to be formed by a pressure medium adapter
placed onto the other end of the pressure medium feed bushing. It
has in its outer surface the other radial circular notch for the
steel or lamellar sealing rings. With the help of a central
fastening screw passing through the pressure medium feed bushing,
the pressure medium tapped from the pressure medium adapter, for
example directly from a camshaft bearing in the cylinder head of
the internal combustion engine, can on the one hand be thereby
passed on along the outside and on the other hand along the inside
of the pressure medium feed bushing in respective circular channels
incorporated into the axial sides of the wheel hub of the impeller.
These channels are connected to the pressure chambers of the device
through other pressure medium channels on the wheel hub of the
impeller.
[0008] However, it is also possible to form the pressure medium
distributor, instead of through a specialized pressure medium feed
bushing, by the fastening screw itself, drilled out axially hollow,
and to incorporate one of the radial circular notches for the steel
or lamellar sealing rings into the head of this screw and/or
instead of a specialized pressure medium adapter to design the
drive end of the camshaft itself as a pressure medium tap. The
other radial circular notch for the steel or lamellar sealing rings
is then located in its outer surface. The pressure medium feed to
the pressure chambers of the device is done in the same manner as
in the described design described previously, wherein the pressure
medium tap for both designs can come not only directly from a
bearing of the camshaft, but also indirectly from another
non-rotating pressure medium feed at the cylinder head of the
internal combustion engine. Independent of the respective design of
the pressure medium distributor and the pressure medium tap, it is
moreover also possible to incorporate the surrounding radial
circular notches for the steel or lamellar sealing rings into the
respective coaxial penetrations in the sidewalls of the drive gear.
In the preferably used slitted steel sealing rings, those with
straight, slanted or overlapping joints as well as those with
cylindrical or hooked joints can be used, with the latter being
characterized by an increase in density. The cross sections of the
steel sealing rings are preferred here to be square, trapezoidal,
round or oval, where the to contact surfaces of the steel sealing
rings can be designed flat or round. In contrast, depending on the
required density, either simple lamellar sealing rings as well as
double or multiple layer sealing rings can be used. It is, however,
also possible to use un-slitted sealing rings, in particular those
made of plastic or similar, as wear-resistant sealing media in the
radial circular notches.
[0009] As a second advantageous form of the device according to the
invention, it is moreover suggested that the sealing media be
preferably provided as circular sealing washers that cover the gap
between the head of the pressure medium distributor and the
penetration in the one side wall of the drive gear and between the
outer surface of the pressure medium tap and the penetration in the
other side wall of the drive gear by placing them into
corresponding circular axial notches. The circular axial notches
for the sealing washers are formed by machining out recesses in the
penetrations of the sidewalls both at the head of the pressure
medium distributor and at the outer surface of the pressure medium
tap.
[0010] In this embodiment, as well, it has proven advantageous to
construct the pressure medium distributor as a pressure medium
guide bushing that coaxially penetrates the impeller with a bushing
head, on whose axial surface lying against the wheel hub of the
impeller a recess is machined that forms one part of the one axial
circular notch. In using a hollow-drilled fastening screw as the
pressure medium distributor, which is also possible here, the
recess forming one part of the circular axial notch can be
incorporated into the axial surface of the screw head lying against
the wheel hub of the impeller in an equivalent manner. The other
part of the circular axial notch is, however, formed from a
complementary recess in the penetration of the one side wall of the
drive gear encircling the bushing head, independent in either case
of the design of the pressure medium distributor. A recess
incorporated into the penetration of the other sidewall of the
drive gear in the same manner forms one part of the other circular
axial notch, moreover, whereas the complementary other part of this
circular axial notch is formed into the axial surface of a
specialized pressure medium adapter, also preferred to be used as a
pressure medium tap here, which lies against the wheel hub of the
impeller. It can also be formed into the axial surface of the drive
end of the camshaft itself.
[0011] The circular sealing washers used in this embodiment are
preferably made as steel sealing washers with a square cross
sectional profile. However, sealing washers made of other
materials, such as sintered steel, cast iron brass, copper,
aluminum, plastics, Teflon or the like can be used with
trapezoidal, round or oval cross sectional profiles. It is also
possible to provide the circular sealing washers with surface
treatments or layers by selective phosphating, ferro-oxidation,
tinning, copper plating, nitrating, nitrocarborization, chromating
or by molybdenum or plastic layering. These layers can also be
designed as metallic, ceramic or metal-ceramic mixed layers. Also,
those types of devices should be included under the protective
scope of the invention that are a combination of the first and
second embodiments described used as the sealing medium. Moreover,
the invention is suitable not only for installation in any kind of
rotary piston positioner, but also for those types of camshaft
adjusters that pertain to the principle of an orbiting slow-moving
hydromotor.
[0012] Thus, the device designed according to the invention to
change the control timing of gas exchange valves of an internal
combustion engine, in particular a hydraulic camshaft adjustment
device of the rotary piston type, has, in both suggested
embodiments, the advantage as compared to devices known from the
state of the art in that by using wear-resistant sealing rings or
sealing washers, the external pressure medium leakages through the
gap between the head of the pressure medium distributor and the
penetration of the one side wall of the drive gear and between the
outer surface of the pressure medium tap and the penetration of the
other side wall of the drive gear are reduced considerably. This
has the advantage in that to hold the camshaft adjustment device in
its controlled position, less pressure medium has to be fed and
that at the same time its stability increases since the friction
between the sealing rings or sealing washers and their contact
surfaces is considerably less than previously known O-rings, in
particular at higher compression at the tolerance limits. Moreover,
the sealing rings or sealing washers arranged according to the
invention make installation of the device easier since they can not
twist when installed, in contrast to O-rings, and in addition are
subject neither to tears or other damage nor to embrittlement at
high or low temperatures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The invention is explained in more detail below based on the
two preferred embodiments disclosed herein. In the appended
drawings, the following is shown:
[0014] FIG. 1 is a front view of a camshaft adjustment device
according to the invention taken along section A-A of FIG. 2;
[0015] FIG. 2 is a section taken along line B-B of FIG. 1 with a
first embodiment of a camshaft adjustment device according to the
invention.
[0016] FIG. 3 is a section taken along line B-B of FIG. 1 with a
second embodiment of a camshaft adjustment device according to the
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] FIG. 1 shows a device 1 designed as a hydraulic camshaft
adjustment device of the rotary piston type that is used to change
the control timing of gas exchange valves of an internal combustion
engine. This device 1 is formed essentially of a drive gear 2
directly connected to a crankshaft (not shown) of an internal
combustion engine and of an impeller directly connected to a
camshaft (also not shown) of the internal combustion engine. The
drive gear 2 has, as seen in FIGS. 1 and 2, a cavity 7 formed from
a hollow cylindrical perimeter wall 4 and two side walls 5, 6,
inside of which four working chambers 9 are formed from four
boundary walls 8. The impeller 3 has at the perimeter of its wheel
hub 10 four vanes 11 extending radially into the working chambers 9
of the drive gear 2. These vanes divide each of the working
chambers into two hydraulic pressure chambers, 12 and 13, which
counteract each other. These pressure chambers 12, 13 effect a
pivoting motion or a fixing of the impeller 3 with respect to the
drive gear 2, and thus of the camshaft with respect to the
crankshaft, by selectively or simultaneously applying pressure
through a hydraulic medium.
[0018] Further, it can be seen from FIGS. 1 and 2, that the
pressure medium feed to and from the pressure chambers 12 and 13 of
the device 1 is done by means of a pressure medium tap 16 lying
against the axial side 15 of the wheel hub 10 of the impeller 3
facing the camshaft, which is designed as a specialized pressure
medium adapter, as well as by means of pressure medium channels 17,
18 incorporated into both axial sides 14, 15 of the wheel hub 10 of
the impeller 3. The pressure medium tap 16 and the pressure medium
channels 17, 18 are connected to one another through a pressure
medium distributor 20 that penetrates the impeller 3 along its
longitudinal axis and that is designed as a specialized pressure
medium feed bushing. The head 19 of this pressure medium
distributor lies against the axial side 14 of the wheel hub 10 of
the impeller 3 facing away from the camshaft. Then, using a central
fastening screw, not shown, the pressure medium tap 16 and the
pressure medium distributor 20 are bolted together with the
impeller 3 to the camshaft, whereupon they are partially enclosed
at the head 19 and the outer surface 21 by an associated coaxial
through penetration 22, 23 in the side walls 5, 6 of the drive gear
2.
[0019] To prevent external pressure medium leakages through the gap
between the head 19 of the pressure medium distributor 20 and the
penetration 22 of the one side wall 5 of the drive gear 2, as well
as between the outer surface 21 of the pressure medium tap 16 and
the penetration 23 of the other side wall 6 of the drive gear 2,
these gaps are sealed off using wear-resistant sealing media
according to the invention.
[0020] The sectional representation of the device 1 shown in FIG. 2
shows that these sealing media are designed in a first embodiment
as slitted steel sealing rings 24, 25 that are each placed into a
circular radial notch 26, 27 in the head 19 of the pressure medium
distributor 20 and in the outer surface 24 of the pressure medium
tap 16. The embodiment shown individually in the lower part of FIG.
2 has proven to be the most cost-effective, and includes by a
straight joint as well as a square cross sectional profile with a
flat contact surface.
[0021] In the alternative embodiment shown in FIG. 3, the sealing
media are, in contrast, provided as circular sealing washers 28, 29
of the specialized depicted type again shown in the lower part of
FIG. 3. These cover the gap between the head 19 of the pressure
medium distributor 20 and the penetration 22 of the one side wall 5
as well as between the outer surface 21 of the pressure medium tap
16 and the penetration 23 of the other side wall 6. These circular
sealing washers, 28 and 29, formed in a cost-effective form of
steel and having a square cross sectional profile, are placed into
circular axial notches 30, 31 that are formed by machining out
recesses at the penetrations 22, 23 of the side walls 5, 6 as well
as at the head 19 of the pressure medium distributor 20 and at the
outer surface 21 of the pressure medium tap 16.
Reference List
[0022] 1 Device
[0023] 2 Drive gear
[0024] 3 Impeller
[0025] 4 Perimeter wall
[0026] 5 Side wall
[0027] 6 Side wall
[0028] 7 Cavity
[0029] 8 Boundary walls
[0030] 9 Working chamber
[0031] 10 Wheel hub
[0032] 11 Vane
[0033] 12 Pressure chamber
[0034] 13 Pressure chamber
[0035] 14 Axial side facing away from the camshaft
[0036] 15 Axial side facing toward the camshaft
[0037] 16 Pressure medium tap
[0038] 17 Pressure medium channel
[0039] 18 Pressure medium channel
[0040] 19 Head
[0041] 20 Pressure medium distributor
[0042] 21 Outer surface
[0043] 22 Penetration
[0044] 23 Penetration
[0045] 24 Steel sealing ring
[0046] 25 Steel sealing ring
[0047] 26 Radial circular notch
[0048] 27 Radial circular notch
[0049] 28 Circular sealing washer
[0050] 29 Circular sealing washer
[0051] 30 Circular axial notch
[0052] 31 Circular axial notch
* * * * *