U.S. patent application number 09/915871 was filed with the patent office on 2002-01-31 for device for varying valve timing of gas exchange valves of internal combustion engines, particularly a hydraulic camshaft adjusting device of a rotary piston type.
Invention is credited to Haag, Michael, Scheidt, Martin, Strauss, Andreas.
Application Number | 20020011226 09/915871 |
Document ID | / |
Family ID | 7650370 |
Filed Date | 2002-01-31 |
United States Patent
Application |
20020011226 |
Kind Code |
A1 |
Scheidt, Martin ; et
al. |
January 31, 2002 |
Device for varying valve timing of gas exchange valves of internal
combustion engines, particularly a hydraulic camshaft adjusting
device of a rotary piston type
Abstract
The invention concerns a device for varying valve timing of gas
exchange valves of an internal combustion engine, particularly a
hydraulic camshaft adjusting device of a rotary piston type, said
device comprising a drive pinion (2) connected in driving
relationship to a crankshaft of the internal combustion engine and
a winged wheel (3) connected rotationally fast to a camshaft of the
internal combustion engine. The drive pinion (2) comprises a hollow
space formed by a circumferential wall (4) and two side walls (5,
6), at least one hydraulic working chamber (10) being formed in the
hollow space by at least two limiting walls (8, 9). The winged
wheel (3) comprises at least one radial wing (12), and with each
wing (12) it divides one hydraulic working chamber (10) into two
hydraulic pressure chambers (13, 14) which, when pressurized by a
hydraulic pressure medium effect a pivoting or a fixing of the
winged wheel (3) relative to the drive pinion (2). When the
internal combustion engine is switched off, the camshaft is rotated
into a preferred basic position for starting the internal
combustion engine, and in this position, the winged wheel (3) can
be mechanically coupled to the drive pinion (2) by a lock. The
novel lock is configured as a cage-guided free-wheel (16) arranged
between the winged wheel (3) and the drive pinion (2) and comprises
at least one clamping body (17) that blocks the direction of
rotation of the winged wheel (3) opposed to the basic position of
the camshaft. The cage (18) of the free-wheel (16) is configured at
least partly as a pressure application surface (19) for the
hydraulic pressure medium for unlocking the free-wheel (16).
Inventors: |
Scheidt, Martin; (Adelsdorf,
DE) ; Strauss, Andreas; (Forchheim, DE) ;
Haag, Michael; (Nurnberg, DE) |
Correspondence
Address: |
BIERMAN MUSERLIAN AND LUCAS
600 THIRD AVENUE
NEW YORK
NY
10016
|
Family ID: |
7650370 |
Appl. No.: |
09/915871 |
Filed: |
July 26, 2001 |
Current U.S.
Class: |
123/90.17 ;
123/90.15 |
Current CPC
Class: |
F01L 1/3442
20130101 |
Class at
Publication: |
123/90.17 ;
123/90.15 |
International
Class: |
F01L 001/34 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 27, 2000 |
DE |
100 36 546.9 |
Claims
What is claimed is:
1. A hydraulic camshaft adjusting device of a rotary piston type
for varying valve timing of gas exchange valve in an internal
combustion engine, said device comprising: a drive pinion connected
in driving relationship to a crankshaft of the internal combustion
engine and a winged wheel connected rotationally fast to a camshaft
of the internal combustion engine, said drive pinion comprising a
hollow space formed by a hollow cylindrical circumferential wall
and two side walls, at least one hydraulic working chamber being
formed in the hollow space by at least two radial limiting walls,
at least one wing arranged on an outer periphery of a wheel hub of
the winged wheel extending radially into the at least one working
chamber and dividing this working chamber into two oppositely
acting hydraulic pressure chambers, by a selective or simultaneous
pressurizing by a hydraulic pressure medium, the pressure chambers
effect a pivoting or a fixing of the winged wheel relative to the
drive pinion, and thus, of the camshaft relative to the crankshaft,
on switching-off of the internal combustion engine, an auxiliary
energy acting between the winged wheel and the drive pinion rotates
the camshaft into a preferred basic position for starting the
internal combustion engine, in the basic position of the camshaft,
the winged wheel can be mechanically coupled to the drive pinion by
a lock that can be hydraulically unlocked again upon renewed
pressurizing of the device, wherein the lock for mechanically
coupling the winged wheel to the drive pinion is formed by at least
one cage-guided free-wheel arranged between the winged wheel and
the drive pinion, said lock comprises at least one clamping body
that blocks a direction of rotation of the winged wheel opposed to
the basic position of the camshaft, and at least parts of a surface
of a cage of the free-wheel are configured as a pressure
application surface for the hydraulic pressure medium for a
hydraulic unlocking of the free-wheel.
2. A device of claim 1 wherein the lock of the device is formed by
only one cage-guided free-wheel that comprises only one clamping
body that is configured as a rolling bearing needle roller, the
cage being made of a heat-resistant plastic.
3. A device of claim 1 wherein the cage of the free-wheel has an
L-shaped cross-sectional profile and is arranged within a likewise
L-shaped angular recess made at least partly in a radial end face
and at least partly in a wing stop surface of one of the limiting
walls of the drive pinion.
4. A device of claim 3 wherein the pressure application surface for
the pressure medium is configured on one side of a first profile
leg of the cage of the free-wheel, while another side of the first
profile leg is operatively connected to a spring means that is
supported on a recessed portion of the wing stop surface of the
limiting wall and acts in locking direction of the free-wheel.
5. A device of claim 3 wherein a collar having a circular
cross-sectional profile is formed on a free end of the first
profile leg of the cage of the free-wheel, and the collar serves to
positively arrest the free-wheel in an additional circular groove
made in the recessed portion of the wing stop surface of the
limiting wall.
6. A device of claim 3 wherein the clamping body is mounted in a
second profile leg of the cage of the free-wheel while being
arranged between an outer peripheral surface of the wheel hub of
the free-wheel and a recessed portion of the radial end face of the
limiting wall of the drive pinion, which recessed portion tapers
conically in locking direction of the free-wheel.
7. A device of claim 6 wherein a hollow space formed behind the
clamping body in unlocking direction of the free-wheel between the
recessed portion of the radial end face of the limiting wall of the
drive pinion and the outer peripheral surface of the wheel hub of
the free-wheel can be depressurized through an additional vent duct
made in the form of a radial groove in one of the side walls of the
drive pinion.
Description
FIELD OF THE INVENTION
[0001] The invention concerns a device for varying valve timing of
gas exchange valve of an internal combustion engine, particularly a
hydraulic camshaft adjusting device of a rotary piston type
comprising:
[0002] a drive pinion connected in driving relationship to a
crankshaft of the internal combustion engine and a winged wheel
connected rotationally fast to a camshaft of the internal
combustion engine,
[0003] said drive pinion comprising a hollow space formed by a
hollow cylindrical circumferential wall and two side walls, at
least one hydraulic working chamber being formed in the hollow
space by at least two radial limiting walls,
[0004] at least one wing arranged on an outer periphery of a wheel
hub of the winged wheel extending radially into the at least one
working chamber and dividing this working chamber into two
oppositely acting hydraulic pressure chambers,
[0005] by a selective or simultaneous pressurizing by a hydraulic
pressure medium, the pressure chambers effect a pivoting or a
fixing of the winged wheel relative to the drive pinion, and thus,
of the camshaft relative to the crankshaft,
[0006] on switching-off of the internal combustion engine, an
auxiliary energy acting between the winged wheel and the drive
pinion rotates the camshaft into a preferred basic position for
starting the internal combustion engine,
[0007] in the basic position of the camshaft, the winged wheel can
be mechanically coupled to the drive pinion by a lock that can be
hydraulically unlocked again upon renewed pressurizing of the
device.
BACKGROUND OF THE INVENTION
[0008] A generic device of the pre-cited type is known from DE 198
44 473 A1. This device configured as a so-called vane-type
adjusting device essentially comprises a drive pinion connected in
driving relationship to a crankshaft of the internal combustion
engine and a winged wheel connected rotationally fast to a camshaft
of the internal combustion engine. The drive pinion comprises a
hollow space formed by a hollow cylindrical circumferential wall
and two side walls, four hydraulic working chambers being formed in
this hollow space by four radial limiting walls. On the periphery
of its wheel hub, the winged wheel correspondingly comprises four
wings each of which extends radially into one of the working
chambers of the drive pinion and divides the working chamber into
two oppositely acting hydraulic pressure chambers. When selectively
or simultaneously pressurized by a hydraulic pressure medium, these
pressure chambers effect a pivoting or a fixing respectively, of
the winged wheel relative to the drive pinion, and thus, of the
camshaft relative to the crankshaft. When the internal combustion
engine is switched off, an auxiliary energy acting between the
winged wheel and the drive pinion rotates the camshaft into a
preferred basic position for starting the internal combustion
engine, in which position, the winged wheel can be mechanically
coupled to the drive pinion by a lock. The lock of this device is a
spring-loaded locking pin that is movably arranged in a radial bore
of a limiting wall of the drive pinion and that, in the basic
position of the camshaft, snaps into a radial reception bore
arranged in the wheel hub of the winged wheel between two wings.
The reception bore is in hydraulic communication with the pressure
medium supply to those pressure chambers that have a minimized
volume in the basic position of the camshaft so that, due to the
pressure loading of these pressure chambers at a re-starting of the
internal combustion engine, the locked locking pin is pushed
against the action of its spring load into the radial bore in the
limiting wall and is thus hydraulically unlocked again.
[0009] Another possibility of mechanically coupling the winged
wheel to the drive pinion of a camshaft adjusting device of a
rotary piston type is known from the device disclosed in DE-OS 196
23 818. The structure of this device configured as a so-called
pivoting wing adjuster corresponds basically to that of the
vane-type adjuster described above except that the wings of its
winged wheel are more massive and that it generally comprises only
two to three hydraulic working chambers. The mechanical coupling of
the winged wheel to the drive pinion is effected in this device by
a likewise spring-loaded locking pin that is slidably arranged in
an axial bore in a wing of the winged wheel and that, in the basic
position of the camshaft, snaps into an axial reception bore in one
of the side walls of the drive pinion. Similar to the previously
described device, this reception bore communicates with the
pressure medium supply of the hydraulic pressure chambers of the
device acting in one direction so that, when these pressure
chambers are pressurized, the locked locking pin is hydraulically
unlocked again in a similar manner and is pushed into the axial
bore in the wing of the winged wheel.
[0010] These locks in the form of a radial locking pin and an axial
locking pin for coupling the winged wheel and the drive pinion of a
camshaft adjusting device of a rotary piston type, however, have
the drawback of being comprised of a plurality of additional,
separate parts and additional pressure medium ducts and reception
bores that unfavorably increase the fabrication and assembly costs
and, thus, the overall manufacturing costs of such a device. A
further drawback of such locks is that the end face of the locking
pin usable as a pressure application surface for unlocking is
relatively small so that a pressure medium pressure sufficient for
unlocking takes a relatively long time to build up and thus
prolongs the unlocking time of the device. Moreover, in these
devices, the basic danger exists that the pressure medium pressure
desired in the pressure chambers in communication with the locking
pin is built up earlier in the pressure chambers themselves than on
the pin and thus produces a bracing torque between the winged wheel
and the drive pinion which causes a clamping of the locking pin in
its locking position so that an adjustment of the device is
rendered impossible.
OBJECTS OF THE INVENTION
[0011] It is an object of the invention to provide a device for
varying the valve timing of gas exchange valves of an internal
combustion engine, and more particularly to provide a hydraulic
camshaft adjusting device of a rotary piston type in which the
winged wheel and the drive pinion can be coupled mechanically to
each other by a lock, the device being distinguished by the small
number of its individual parts and by low fabrication and assembly
costs while being configured with a pressure application surface
that is large enough to assure a quick hydraulic unlocking.
[0012] This and other objects and advantages of the invention will
obvious from the following detailed description.
SUMMARY OF THE INVENTION
[0013] The invention achieves the above objects by the fact that
the lock for mechanically coupling the winged wheel to the drive
pinion is formed by at least one cage-guided free-wheel that is
arranged between the winged wheel and the drive pinion and
comprises at least one clamping body that blocks the direction of
rotation of the winged wheel opposed to the basic position of the
camshaft, at least parts of the surface of the cage of the
free-wheel being configured as a pressure application surface for
the hydraulic pressure medium for a hydraulic unlocking of the
free-wheel.
[0014] In a particularly preferred embodiment of the invention, it
has proved to be sufficient if the lock of the device comprises
only one free-wheel made according to the invention and only one
clamping body is guided by its cage because this reduces the
fabrication and assembly costs of the lock to a minimum. For a
further reduction of costs for the lock of the device,
advantageously, the clamping body of the free-wheel is configured
as a simple rolling bearing needle roller and the cage of the
free-wheel is made of a heat-resistant plastic. However, the
invention also includes solutions in which the free-wheel comprises
a plurality of clamping bodies, for example, two or more rolling
bearing balls arranged next to one another and/or in which the cage
is made of a material other than a plastic.
[0015] According to a further advantageous proposition of the
invention, the cage of the free-wheel preferably has an L-shaped
cross-sectional profile and is arranged in an angular recess which
likewise has an L-shaped cross-sectional profile and is made in a
limiting wall of the drive pinion. This angular recess is made at
least partly in the radial end face of the limiting wall and at
least partly in one of the two wing stop surfaces of the limiting
wall so that the entire free-wheel is received within the original
contour of the limiting wall. The wing stop surface in which the
angular recess is made is preferably that lateral surface of the
limiting wall which, in the pivoted position of the winged wheel
corresponding to the basic position of the camshaft, delimits one
of those pressure chambers of the device that are pressurized on
starting of the internal combustion engine. Moreover, it is
advantageous from the fabrication point of view to configure the
angular recess for the free-wheel in the limiting wall over the
entire axial width of the drive pinion. Although the length of the
two legs of the angular recess can be chosen at will, it is
advantageous to retain a smaller part of the wing stop surface of
the limiting wall starting from the circumferential wall of the
drive pinion and as large a part of the radial end face of the of
the limiting wall in their original contours. This assures on the
one hand that a stop still exists for the wing of the winged wheel
that is in operative contact with this side of the limiting wall
and, on the other hand, that the leak gap between the radial end
face of this limiting wall and the wheel hub of the winged wheel
still has an adequate length for sealing the adjoining hydraulic
pressure chambers.
[0016] In an alternative configuration of the angular recess in the
limiting wall of the drive pinion it is, however, also possible to
configure this recess narrower than the axial width of the drive
pinion so as to extend only over a part of the axial width of the
drive pinion into the limiting wall. In this case it would also be
conceivable to have that leg of the angular recess that is made in
the wing stop surface of the limiting wall extend over the entire
height of the limiting wall because the remaining part of the axial
width of the limiting wall can then act as a wing stop surface for
the wing of winged wheel. But such a leg of the angular recess
extending over the entire height of the limiting wall is basically
also possible in the preferred configuration of the angular recess
extending over the entire axial width of the drive pinion because
the end position of the wing in operative contact with this
limiting wall is jointly defined also by the stop surfaces for the
other wings of the winged wheel.
[0017] According to a further advantageous proposition of the
invention, the first profile leg of the L-shaped cage of the
free-wheel is configured on one side as a pressure application
surface for the hydraulic pressure medium and, on the other side,
it cooperates with a spring means that is supported on the recessed
portion of the wing stop surface of the limiting wall and acts in
locking direction of the free-wheel. The pressure application
surface on this first profile leg is formed by that one of its two
lateral surfaces that is oriented towards the pressure chamber that
is pressurized on starting of the internal combustion engine. The
size of this pressure application surface is determined by the
choice of the above-mentioned alternatives of configuration of the
angular recess because, to avoid an undesired pressure build-up
behind the free-wheel, the first profile leg of the cage of the
freewheel arranged in the recessed portion of the wing stop surface
must seal the angular recess as pressure-medium tightly as
possible, which means that its pressure application surface must
basically have approximately the same dimensions as the recessed
portion of the wing stop surface of the limiting wall. Besides the
aforesaid advantages obtained in fabrication by making the angular
recess extend in the limiting wall over the entire axial width of
the drive pinion, with a cage of corresponding configuration
inserted into this angular recess, this has also proved to be of
advantage for obtaining as large a pressure application surface as
possible on the first profile leg of the cage because, in this way,
already upon a slight pressure build-up in the pressure chambers of
the device that are pressurized on starting of the internal
combustion engine, an adequate force for the hydraulic unlocking of
the free-wheel is applied to the pressure application surface.
[0018] If the cage is made of a plastic or even as a bent stamping,
the spring means acting in the locking direction of the free-wheel
can be formed particularly advantageously by one or more spring
tongues formed integrally on and at an acute angle to the lateral
surface of the first profile leg situated opposite from the
pressure application surface. The spring force of these spring
tongues can be defined by their angular position and/or by their
material thickness. Alternatively, separately made spring means,
for example, flat bent springs, coiled compression springs or
elastomer pads and the like may also be used. These may be fixed on
the recessed portion of the wing stop surface of the limiting wall
or on the first profile leg of the cage and be supported on the
respective opposite surface. According to a further proposed
feature of the first profile leg of the cage of the free-wheel, the
free end of this leg has an integrally formed collar with a
circular profile cross-section with which the cage of the
free-wheel can be positively arrested in a circular groove
additionally provided in the recessed portion of the wing stop
surface of the limiting wall. This circular groove is preferably
arranged near the hollow angle formed by the angular recess in the
wing stop surface, and similar to the angular recess, this groove,
too, is made in the limiting wall over the entire axial width of
the drive pinion. The collar with the circular profile crosssection
is offset at an angle of about 45.degree. to this profile leg
preferably by bending the edge portion of the first profile leg, so
that, after the mounting of the cage by sideward pushing into the
circular groove, an intermediate space is formed between the
profile leg and the recessed portion of the wing stop surface for
receiving the spring means of the free-wheel and the required
freedom of the cage to pivot within its catch is guaranteed at the
same time. It is, however, also conceivable to configure the first
profile leg of the cage with its end portion bent into a Z-shaped
profile and fix it by screwing or the like in the recessed portion
of the wing stop surface on the limiting wall. The central bar of
the Z-shaped profile could then also form the spring means of the
free-wheel.
[0019] According to a further feature of the device of the
invention, the second profile leg of the cage of the free-wheel is
inserted into that part of the angular recess that is made in the
radial end face of the limiting wall of the drive pinion, so that
the clamping body of the free-wheel mounted in this profile leg is
arranged between the outer peripheral surface of the wheel hub of
the winged wheel and the recessed portion of the radial end face of
the limiting wall. For enabling the locking action of the
free-wheel, the distance of the limiting-wall-side end region of
the recessed portion of the radial end face of the limiting wall
from the outer peripheral surface of the wheel hub of the winged
wheel is larger than the diameter of clamping body of the free
wheel, while the distance of the pressure-chamber-side end region
of the recessed portion of the radial end face from the outer
peripheral surface of the wheel hub of the winged wheel is smaller
than the diameter of the clamping body. The resulting conical taper
of the part of the angular recess thus formed in the radial end
face of the limiting wall extends in the locking direction of the
free-wheel and is preferably configured with an angle lying within
the self-locking range of the clamping body of the free-wheel. In
this way, when the internal combustion engine is switched off, or
when the pressure medium pressure in the pressure chamber of the
device delimited by the free-wheel falls short of a certain value,
the clamping body of the free-wheel is displaced by the spring
means arranged on the cage of the free-wheel out of its unlocking
position in the limiting-wall-side end region of the recessed
portion of the radial end face of the limiting wall, in which
position the clamping body is retained till then by the pressure
medium pressure, into its locking position in the
pressure-chamber-side end region of the recessed portion of the
radial end face and braces the drive pinion and the winged wheel of
the device against each other, that is to say, the drive pinion and
the winged wheel are thus coupled mechanically to each other. If,
at this moment, the pivoted position of the winged wheel does not
correspond to the preferred basic position of the camshaft for a
re-starting of the internal combustion engine, the alternating
torques of the camshaft persisting during the run-out phase of the
internal combustion engine at the same time form the auxiliary
energy for displacing the winged wheel into this basic position due
to the fact that the component of the alternating torques acting
against the locking direction of the free-wheel and not impeded by
this, is utilized for pivoting the winged wheel toward the basic
position, while the component of the alternating torques acting in
the locking direction of the free-wheel is impeded or cut off by
the free-wheel.
[0020] Finally, according to a further feature of device of the
invention, the hollow space formed in unlocking direction behind
the clamping body between the recessed portion of the radial end
face of the limiting wall of the drive pinion and the outer
peripheral surface of the wheel hub of the winged wheel can be
depressurized preferably through an additional vent duct. This vent
duct is preferably configured as a radial groove made in one of the
side walls of the drive pinion, which groove begins as a
continuation of the radial step formed in this limiting wall by the
angular recess in the radial end face of the limiting wall and
opens within the device into a pressure medium duct leading into
the cylinder head of the internal combustion engine. The vent duct
assures that no leakage-caused pressure medium bolster is formed in
the hollow space behind the clamping body, which bolster would
render more difficult or even prevent a movement of the free-wheel
into its unlocking position when the internal combustion engine is
started or when the pressure chamber delimited by the free-wheel is
pressurized, and further assures that the hydraulic pressure medium
collecting in this hollow space is constantly discharged from the
device as a leakage. To further improve the pressure relief in the
hollow space arranged behind the clamping body, it is also possible
to provide such radial grooves acting as vent ducts not only in one
of the side walls but in both side walls of the drive pinion.
[0021] The device of the invention for varying the valve timing of
gas exchange valves of an internal combustion engine, particularly
a hydraulic camshaft adjusting device of a rotary piston type
therefore possesses the advantage over known prior art devices that
the lock for the mechanical coupling of the drive pinion to the
winged wheel is embodied in a free-wheel of a simple structure that
is distinguished by a minimum number of individual parts and low
fabrication and assembly costs and therefore permits an extremely
economic manufacturing of the device of the invention. Besides
this, in a device having such a locking arrangement, the entire
surface of the first profile leg of the L-shaped cage of the
free-wheel is configured as a pressure application surface that can
be used for unlocking the device so that the pressure required for
unlocking is built up as rapidly as possible and, compared to
mechanical locking arrangements, the unlocking time is shortened.
Moreover, due to the structure and the mode of operation of the
free-wheel lock of the device of the invention, a pressure medium
pressure acting in the pressure chambers that are the first to be
pressurized upon starting of the internal combustion engine cannot
produce a bracing torque between the drive pinion and the winged
wheel that would obstruct an adjustment of the device, so that the
locking and unlocking reliability of the free-wheel lock of the
invention is higher than that of known mechanical locks.
[0022] The invention will now be described more closely with
reference to an example of embodiment and the appended
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a top view of a rotary piston type camshaft
adjusting device of the invention, with the side wall situated
opposite from the camshaft removed;
[0024] FIG. 2 is an enlarged view of the detail X of FIG. 1 showing
the freewheel lock of the camshaft adjusting device of the
invention.
DETAILED DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 clearly shows a device 1 configured as a rotary
piston type hydraulic camshaft adjusting device which serves to
vary the opening and closing times of gas exchange valves of an
internal combustion engine. This device 1 generally comprises a
drive pinion 2 that is in driving relationship to a crankshaft, not
shown, of the internal combustion engine and a winged wheel 3 that
is connected rotationally fast to a camshaft, also not shown, of
the internal combustion engine. The drive pinion 2 comprises a
hollow space 7 defined by a hollow cylindrical circumferential wall
4 and two side walls 5, 6, roughly indicated in FIG. 2. Five
hydraulic working chambers 10 are formed in the hollow space 7 by
five radial limiting walls 8, 9. FIG. 1 further shows that five
wings. 12, each of which extends radially into one of the working
chambers 10 of the drive pinion 2, are arranged on the periphery of
the wheel hub 11 of the winged wheel 3. The wings 12 divide each
working chamber 10 into two oppositely acting pressure chambers 13,
14 which, when selectively or simultaneously pressurized by a
hydraulic pressure medium, effect a pivoting or a fixing,
respectively, of the winged wheel 3 relative to the drive pinion 2
and, thus also, of the camshaft relative to the crankshaft.
[0026] A further feature of the device 1 represented in FIG. 1 is
that, when the internal combustion engine is switched off, the
camshaft is rotated by an auxiliary energy acting between the
winged wheel 3 and the drive pinion 2 into a preferred basic
position for starting the engine. In this position, the winged
wheel 3 can be mechanically coupled to the drive pinion 2 by a lock
15 that can be unlocked again hydraulically upon a renewed
pressurization of the device 1. According to the invention, this
lock 15 is formed in the present embodiment of the device 1 by a
cage-guided free-wheel 16, shown in detail in FIG. 2, that is
arranged between the drive pinion 2 and the winged wheel 3. The
free-wheel 16 comprises a clamping body 17 that blocks the
direction of rotation of the winged wheel 3 opposed to the basic
position of the camshaft, at least parts of the surface of the cage
18 of the free-wheel 16 forming, at the same time, a pressure
application surface 19 for the hydraulic pressure medium for the
hydraulic unlocking of the free-wheel 16. The device 1 shown in the
drawings, is represented by way of example as a vane-type adjusting
device that is mounted on an inlet camshaft and whose winged wheel
3 can be coupled to the drive pinion 2 in the basic position
indicated by an arrow in FIG. 1 and corresponding to a "retard
position" of the camshaft. The free-wheel 16 of this device
comprises a clamping body 17 in the form of a rolling bearing
needle roller and a cage 18 made of a heat-resistant plastic.
[0027] FIG. 2 further clearly shows that the cage 18 of the
free-wheel 16 has an L-shaped cross-sectional profile and is
arranged within a likewise L-shaped angular recess 23 that is made
partly in the radial end face 20 and partly in the wing stop
surface 21 of a limiting wall 9 of the drive pinion 2 and extends
over the entire axial width of the drive pinion 2. In a device 1
mounted on an outlet camshaft, the angular recess 23 would be made
laterally reversed in the wing stop surface 22 and in the radial
end face 20 of a limiting wall 8.
[0028] The pressure application surface 19 for the hydraulic
pressure medium is configured on that lateral surface of the first
profile leg 24 of the cage 18 of the free-wheel 16 that is oriented
towards that pressure chamber 13 which is pressurized upon starting
of the internal combustion engine, while on the opposite lateral
surface of the first profile leg 24 a spring means 25 is arranged
that is supported on the recessed portion of the wing stop surface
21 of the limiting wall 9 and acts in locking direction of the
free-wheel 16. This spring means 25 is configured as a plastic
spring tongue that is integrally formed at an acute angle on this
profile leg 24 and likewise extends over the entire axial width of
the drive pinion 2. A collar 26 having a circular cross-sectional
profile is formed on the free end of the first profile leg 24 of
the cage 18 of the free-wheel 16 and is bent at a small angle to
the end region of the profile leg 24. With this collar 26, the
freewheel 16 can be positively arrested in a circular groove 27
made in the recessed portion of the wing stop surface 21 of the
limiting wall 9.
[0029] As can also be clearly seen in FIG. 2, the second profile
leg 28 of the cage 18 of the free-wheel 16 thus extends into the
part of the angular recess 23 that is situated in the radial end
face 20 of the limiting wall 9 of the drive pinion 2 so that the
clamping body 17 of the free-wheel 16 mounted in this second
profile leg 28 is situated between the outer peripheral surface 29
of the wheel hub 11 of the winged wheel 3 and the recessed portion
of the radial end face 20 of the limiting wall 9 of the drive
pinion 2. The recessed portion of the radial end face 20 of the
limiting wall 9 is configured with a conical taper in the locking
direction of the free-wheel 16, so that, after the internal
combustion engine has been switched off, the clamping body 17 of
the free-wheel 16 is displaced by the spring means 25 arranged on
the cage 18 of the free-wheel 16 out of its unlocking position in
the limiting-wall-side end region of the recessed portion of the
radial end face 20 of the limiting wall 9 into its locking position
in the pressure-chamber-side end region of the recessed portion of
the radial end face 20 and braces the drive pinion 2 and the winged
wheel 3 of the device 1 against each other. The hollow space 30
formed in unlocking direction of the free-wheel 16 behind the
clamping body 17 between the recessed portion of the radial end
face 20 of the limiting wall 9 of the drive pinion 2 and the outer
peripheral surface 29 of the wheel hub 11 of the winged wheel 3 can
be depressurized through a vent duct 31, roughly indicated in FIG.
2, that is configured as a radial groove in the side wall 5 of the
drive pinion 2 and serves to discharge leaked pressure medium
collecting in the hollow space 30.
* * * * *