U.S. patent application number 09/746218 was filed with the patent office on 2001-08-30 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 Dietz, Joachim, Golbach, Hermann, Kapp, Matthias, Schafer, Jens, Steigerwald, Martin.
Application Number | 20010017117 09/746218 |
Document ID | / |
Family ID | 7934562 |
Filed Date | 2001-08-30 |
United States Patent
Application |
20010017117 |
Kind Code |
A1 |
Golbach, Hermann ; et
al. |
August 30, 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
that includes of a drive gear (2) directly connected to a
crankshaft and an impeller that is directly connected to a camshaft
(3). The drive gear (2) has a cavity formed from a perimeter wall
(5) and two side walls (5, 6) inside of which at least one
hydraulic working chamber is formed from at least two boundary
walls. The impeller has at least one radial vane (12) and each vane
(12) divides one hydraulic work chamber into two hydraulic pressure
chambers. The outer end (18) of each vane (12) of the impeller is
pressed radially against the perimeter wall (5) of the drive gear
(2) as a result of the force of a spring element (17) located at
the inner end (15) of the vane. The spring elements (17) located at
the inner end (15) of the vanes (12) have, at unchanged space
requirements, a spring force that is greater than the pressure
force of the hydraulic pressure medium acting on the outer end (18)
of the vanes (12) in the respective actuated pressure chamber of
the device (1).
Inventors: |
Golbach, Hermann; (Erlangen,
DE) ; Steigerwald, Martin; (Herzogenaurach, DE)
; Schafer, Jens; (Herzogenaurach, DE) ; Kapp,
Matthias; (Nurnberg, DE) ; Dietz, Joachim;
(Frensdorf, DE) |
Correspondence
Address: |
VOLPE AND KOENIG, P.C.
SUITE 400, ONE PENN CENTER
1617 JOHN F. KENNEDY BOULEVARD
PHILADELPHIA
PA
19103
US
|
Family ID: |
7934562 |
Appl. No.: |
09/746218 |
Filed: |
December 22, 2000 |
Current U.S.
Class: |
123/90.16 ;
123/90.15 |
Current CPC
Class: |
F01L 1/3442 20130101;
F01L 2001/34479 20130101; Y10T 74/2102 20150115 |
Class at
Publication: |
123/90.16 ;
123/90.15 |
International
Class: |
F01L 001/34 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 24, 1999 |
DE |
199 63 094.1 |
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 to be directly connected to a crankshaft of the internal
combustion engine and an impeller (4) adapted to be directly
connected to a camshaft (3) of the internal combustion engine, the
drive gear (2) has a cavity (8) formed by a hollow cylindrical
perimeter wall (5) and two side walls (6, 7) inside of which at
least one hydraulic working chamber (10) is formed from at least
two boundary walls (9), the impeller (4) has a wheel hub (11) with
at least one vane (12) at the perimeter thereof extending radially
into a working chamber (10) of the drive gear (2) that divides the
chamber into two respective hydraulic pressure chambers (13, 14)
that counteract one another, an outer end (18) of each vane (12) of
the impeller (4) is radially pressed against the perimeter wall (5)
of the drive gear (2) as a result of force of a spring element (17)
located in an axial retaining notch (16) at an inner end (15) of
the vane, the pressure chambers (13, 14) adapted to effect a
pivoting motion or a fixing of the impeller (4) with respect to the
drive gear (2), and thus of the camshaft (3) with respect to the
crankshaft, by selective or simultaneous application of pressure
with a hydraulic medium, wherein, the spring elements (17) located
at the inner end (15) of the vanes (12) have, at unchanged space
requirements, a spring force that is higher than a maximum pressure
force of the hydraulic medium acting on the outer end (18) of the
vanes (12) in the associated actuated pressure chamber (13, 14) of
the device (1).
2. A device according to claim 1, wherein the spring elements (17)
comprise radial, wave-shaped, bent spring packets made of at least
two flat profile springs (19, 20) that have a concave middle (21)
and two convex ends (22, 23) along an axial length thereof.
3. A device according to claim 1, wherein the spring elements (17)
comprise radial, wave-shaped, bent round profile springs (24) with
at least two spring sides (25, 26) that extend parallel next to one
another and that have a concave center (27) and two convex ends
(28, 29) along an axial length thereof.
4. A device according to claim 1, wherein the spring elements (17)
comprise radial Z-shaped bent riser, upright springs (30) that each
includes an axially straight, eyelet-shaped base (31) and an
axially straight, eyelet-shaped head (32) extending parallel to the
base, which are connected together by a slanted spring stem
(33).
5. A device according to claim 1, wherein the spring elements (17)
comprise radial convex bent hairpin springs (34) having spring
sides (35, 36) that are located parallel one on top of the other
and lying against one another that are connected together by a
hairpin eyelet (37).
6. A device according to claim 1, wherein the spring elements (17)
comprise lose coil springs (38) that have approximately twice an
axial length as an axial retaining notch (16) length of the vanes
(12) and can be placed as a continuous loop that is radially
compacted into the retaining notches (16) of the vanes (12).
7. A device according to claim 1, wherein the spring elements (17)
comprise spring cushions (39) made of an elastic temperature,
resistant material that has a length and width that corresponds to
a length and width approximately of the axial retaining notches
(16) of the vanes (12) and has a height that is a bit larger than a
distance between the base of the notch of the axial retaining
notches (16) and the inner end (15) of the vanes (12).
Description
BACKGROUND
[0001] The invention relates 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, and it is
particularly advantageous for application in hydraulic camshaft
adjusting devices of the rotary piston type.
[0002] A device of this type is already known from European patent
EP 0 816 610 A2, which generally defines this class. This device,
designed as a so-called vane-cell positioner, 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 five hydraulic working chambers are
formed from five boundary walls. Accordingly, the impeller has at
the perimeter of its wheel hub five vanes, each of which extends
radially into a working chamber of the drive gear. These five vanes
divide each of the working chambers into two counteracting
hydraulic pressure chambers. The outer end of each vane of the
impeller is radially pressed against the inside of the perimeter
wall of the drive gear from the force of a spring element located
in an axial retaining notch at the inner end of the vane. This
seals off the pressure chambers of each hydraulic working chamber
from one another and effects, by selectively or simultaneously
applying pressure using a hydraulic pressure medium, a pivoting
motion or a fixing of the impeller with respect to the drive gear
and thus the camshaft with respect to the crankshaft.
[0003] The disadvantage in this known device is that when pressure
is applied to one or both pressure chamber (s) of each hydraulic
working chamber, a buildup of pressure results in the sealing gap
between the outer end of each vane and the inside of the perimeter
wall of the drive gear. If the force of the pressure exceeds the
value of the spring force of the spring element located at the
inner end of each vane, a so-called "vane dipping" can occur
despite these spring elements, i.e. the vane can radially shift
against the force of the spring element. This then results in
increased pressure medium leakage between the individual pressure
chambers of the hydraulic working chamber so that a poorer
hydraulic lock of the impeller with respect to the drive gear
results. Moreover, this increased pressure medium leakage is the
cause of larger deviations in the prescribed positioning angle
between the camshaft and the crankshaft as well as of slower
positioning times of the device.
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 radial shift of the
vanes against the force of their spring elements resulting from the
pressure buildup in the sealing gap between the outer end of each
vane of the impeller and the inside of the perimeter wall of the
drive gear is effectively eliminated.
[0005] According to the invention, this object is met by a device
according to the preamble of claim 1 in that the spring elements at
the inner end of the vanes have a spring force, at constant space
requirements, that is higher than the maximum pressure force by the
hydraulic pressure medium acting on the outer end of the vanes in
the respective actuated pressure chamber of the device.
[0006] The maximum pressure force of the hydraulic pressure medium
is equal to the pressure peaks that arise according to operation
and act on one or the other axial side of the outer ends of the
vanes according to which pressure chamber of the device is
actuated. Also, when both pressure chambers are simultaneously
actuated, these pressure peaks act on the entire surface area of
the outer ends of the vanes. However, since the spring force of the
spring elements is aided by the centrifugal forces acting on the
vanes when the engine is running as well as by the pressure force
of the hydraulic pressure medium that also acts on half or all of
the surface of the inner ends of the vanes, it has proven to be
sufficient in preventing the disadvantageous vane dipping if the
spring elements have a minimum spring force that is approximately
equal to the maximum pressure force of the hydraulic pressure
medium. The implementation of this minimum spring force by
appropriately dimensioning the spring elements is, however, subject
to certain limits due to the generally very limited space in the
retaining notches of the spring elements.
[0007] One way to nevertheless increase the spring force of the
spring elements to the required minimum spring force is the special
geometric structuring of the spring elements along their axial
length. In a first preferred embodiment, the spring elements are
therefore provided as radially wave-shaped bent spring packets made
of at least two flat profile springs that each have a concave
center and two convex ends along their axial length. However, up to
a limit determined by space requirements, it is also possible to
arrange more than two of these types of flat profile springs on top
of one another that are connected together an adhesive or the like
to make installation easier. The concave center of these spring
packets lies preferably on the base of the notch of the axial
retaining notches of the vanes, whereas their convex ends lie
against the axial edges of the inner ends of the vanes. It is,
however, also possible to place the spring packets in reverse into
the retaining notches of the vanes so that each of the spring
packets' center lies against the inner end of the vane and the ends
of the spring packets lie on the base of the notch of the retaining
notch of the vane.
[0008] A second preferred embodiment of geometrically spring-force
enhanced spring elements is the suggestion of providing the spring
elements as radial wave-shaped bent round profile springs with at
least two spring sides running parallel with one another, each of
which also has a concave center and two convex ends along its axial
length. The number of spring sides running next to one another,
however, is also subject to limits of space requirements in this
embodiment as well, for which the concave center of the round
profile springs is also preferred to lie on the base of the notch
of the axial retaining notches and their convex ends are preferred
to lie against the inner ends of the vanes.
[0009] A third embodiment whose goal is to equip spring elements of
the vanes with the required minimum spring force using special
geometric shapes provides the spring elements as radial Z-shaped
bent riser, upright springs. These upright springs each include an
axially straight, eyelet-shaped base and a head that is parallel to
it and similarly shaped, which are connected together through a
slanted spring stem. The base of these upright springs lies flat on
the base of the notch of the axial retaining notches, whereas its
head lies flat against the inner ends of the vanes. The special
advantage of these types of springs is that they apply a relatively
large contact force on the vanes and at the same time can smooth
out larger tolerance differences.
[0010] A fourth preferred embodiment of geometrically spring-force
enhanced spring elements is suggested in which they are provided as
radial convex bent hairpin springs whose spring sides are
positioned parallel one on top of the other and lying against one
another and are connected together through a hairpin eyelet. One
end of this hairpin spring formed by the hairpin eyelet and its
opposite other end are placed in the axial retaining notches on the
base of the notch of the axial retaining notches, whereas its
center lies against the center of the inner end of the vane. It
would also be conceivable, however, to have a reverse arrangement
of springs in the axial retaining notches of the vanes.
[0011] A fifth preferred embodiment of geometrically spring-force
enhanced spring elements is suggested in which the spring elements
are provided as loose coil springs that have approximately twice
the axial length as the axial retaining notches of the vanes and
are placed into the retaining notches of the vanes as a continuous
loop that is radially compacted. Here, the high radial spring force
of the individual spring windings of coil springs is used mainly to
be able to apply a large contact force onto the vanes.
[0012] Finally, a sixth preferred embodiment of geometrically
spring-force enhanced spring elements is suggested in which the
spring elements are provided as spring cushions made of an elastic
temperature resistant material. These spring cushions correspond in
length and width approximately with the dimensions of the axial
retaining notches of the vanes and have a height that is a bit
larger than the distance between the base of the notch of the axial
retaining notches and the inner ends of the vanes lying against the
perimeter wall of the drive gear. The higher the spring cushions
are designed, the higher the contact force that is applied to the
vanes. As material for the spring cushions, rubber or elastomers
have proven to be especially advantageous, but foam plastics or the
like can also be used.
[0013] The device according to the invention 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, has the advantage in comparison to known
devices from the state of the art in that spring elements located
at the inner end of the vanes exhibit, in all embodiments
described, a sufficient minimum spring force to prevent the radial
shift of the vanes resulting from the pressure buildup in the
sealing gap between the outer end of each vane of the impeller and
the inside of the perimeter wall of the drive gear. This reduces
the internal pressure medium leakage between the individual
pressure chambers of the hydraulic working chambers to a minimum
and improves the hydraulic locking of the impeller with respect to
the drive gear as well as the maintaining of prescribed positioning
angles between the camshaft and the crankshaft.
[0014] Moreover, the enhanced spring elements according to the
invention are not just suitable for pressing the vanes of the
impeller against the perimeter wall of the drive gear of a
vane-cell positioning device, but are also applicable as spring
element sealing strips to an impeller of a so-called pivoting vane
positioning device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The invention is explained in more detail below with
reference to the preferred embodiments. In the associated drawings,
the following is shown:
[0016] FIG. 1 is a cross-section taken along line A-A of FIG. 2
through a camshaft adjustment device according to the
invention.
[0017] FIG. 2 is a longitudinal section taken along line of B-B of
FIG. 1 with a first embodiment of a camshaft adjustment device
according to the invention.
[0018] FIG. 3 is a detail view of the area X in FIG. 2 with a
second embodiment of a camshaft adjustment device according to the
invention.
[0019] FIG. 4 is a detail view of the area X in FIG. 2 with a third
embodiment of a camshaft adjustment device according to the
invention.
[0020] FIG. 5 is a detail view of the area X in FIG. 2 with a
fourth embodiment of a camshaft adjustment device according to the
invention.
[0021] FIG. 6 is a detail view of the area X in FIG. 2 with a fifth
embodiment of a camshaft adjustment device according to the
invention.
[0022] FIG. 7 is a detail view of the area view X in to FIG. 2 with
a sixth embodiment of a camshaft adjustment device according to the
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] FIGS. 1 and 2 clearly show 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 focused from a drive
gear 2 directly connected to a crankshaft (not shown) of an
internal combustion engine and of an impeller 3 directly connected
to a camshaft of the internal combustion engine. The drive gear 2
has a cavity 8 formed from a hollow cylindrical perimeter wall 5
and two sidewalls 6, 7, inside of which four hydraulic working
chambers 10 are formed from four boundary walls 9. The impeller 4
at the perimeter of its wheel hub 11 includes four vanes 12 that
extend radially into the working chambers 10 of the drive gear 2.
These vanes divide each of the working chambers 10 into two
hydraulic pressure chambers 13, 14 that counteract each other. It
can be clearly seen in FIG. 2 that the outer end 18 of each vane 12
of the impeller 4 is radially pressed against the inside of the
perimeter wall 5 of the drive gear 2 by the force of a spring
element located in an axial retaining notch 16 at its inner end 15
so that the pressure chambers 13, 14 are sealed off from one
another. By selectively or simultaneously applying pressure using a
hydraulic pressure medium, a pivoting or fixing of the impeller 4
with respect to the drive gear 2, and thus of the camshaft with
respect to the crankshaft, is effected.
[0024] In order to prevent "vane dipping", which results from the
pressure buildup in the sealing gap between the outer end 18 of
each vane 12 and the inside of the perimeter wall 5 of the drive
gear 2 when pressure is applied to one or both pressure chamber (s)
13, 14 of each hydraulic working chamber 10 of the device 1, the
spring elements 17 located on the inside end 15 of the vane 12 are,
according to the invention, designed with a spring force at
unchanged space requirements that is higher than the maximum
pressure force of the hydraulic pressure medium in the respective
activated pressure chamber 13, 14 of the device acting on the
outside end 18 of the vane 12.
[0025] This is realized in the first embodiment shown in FIG. 2 of
a device according to the invention by pivoting the spring elements
17 as radial wave-shaped bent spring packets made of two flat
profile springs 19, 20 that each have a concave center 21 and two
convex ends 22, 23, along their axial length. In so doing, the
concave center 21 of these spring packets lies at the base of the
notch of the axial retaining notches 16 of the vanes 12, whereas
the convex ends 22, 23 lie at the inner ends 15 of the vanes.
[0026] A second embodiment of a device 1 according to the invention
is shown in FIG. 3. In this embodiment, the spring elements 17 are
provided as radial wave-shaped bent round profile springs 24 that
also have a concave center 27 lying at the base of the notch of the
axial retaining notch 16 along its axial length, and two convex
ends 28, 29 lying against the inner ends 15 of the vanes 12. The
top views of these round profile springs 24 in FIG. 3 clarifies
that they are designed with at least two spring sides 25, 26
running parallel next to one another, wherein their number can be
expanded in the manner indicated below up to a limit determined by
available space.
[0027] In the third embodiment shown in FIG. 4 of a device 1
according to the invention, the spring elements 17 are provided as
Z-shaped bent riser, upright springs 30 that are also depicted as
individual parts in perspective representation. It is clear to see
that the upright springs 30 include an axially straight,
eyelet-shaped base 31 and a head 32 running parallel to it and
formed in a similar manner, which are connected through a slanted
spring stem 33.
[0028] A fourth embodiment of a device 1 according to the invention
is shown in FIG. 5. In this representation, it is clear to see that
the spring elements 17 are provided as convex bent hairpin springs
34 whose spring sides 35, 36 that are located parallel, one on top
of the other, and lying against one another, and are connected to
one another through a hairpin eyelet 37. One end formed by the
hairpin eyelet 37 and the opposite other end of this hairpin spring
34 lie on the base of the notch of the axial retaining notches 16
of the vanes 12 so that their convex center can lie against the
inner end 15 of the vanes 12.
[0029] As the fifth embodiment of a device 1 according to the
invention, FIG. 6 shows an embodiment in which the spring elements
17 are provided as loose coil springs 38. These coil springs 38
have approximately twice the axial length as the axial retaining
notches 16 of the vanes 12 and are placed into the axial retaining
notches 16 of the vanes 12 as a continuous loop radially compacted
in the manner shown in the drawing.
[0030] In FIG. 7, a sixth embodiment of the device 1 according to
the invention is shown in which the spring elements 17 are provided
as spring cushions 39 made of elastic, temperature resistant
rubber. These spring cushions 39 correspond in length and width
approximately with the dimensions of the axial retaining notches 16
of the vanes 12 and have a height that is a bit larger than the
distance between the base of the notch of the axial retaining
notches 16 and the inner ends 15 of the vanes 12 lying against the
perimeter wall 4 of the drive gear 2.
* * * * *