U.S. patent application number 11/419301 was filed with the patent office on 2006-11-23 for apparatus for the variable setting of the control times of gas exchange valves of an internal combustion engine.
This patent application is currently assigned to SCHAEFFLER KG. Invention is credited to Olaf Boese, Rainer Ottersbach, Gerhard Scheidig, Andreas Strauss.
Application Number | 20060260578 11/419301 |
Document ID | / |
Family ID | 37447162 |
Filed Date | 2006-11-23 |
United States Patent
Application |
20060260578 |
Kind Code |
A1 |
Boese; Olaf ; et
al. |
November 23, 2006 |
Apparatus for the variable setting of the control times of gas
exchange valves of an internal combustion engine
Abstract
The invention relates to an apparatus (1) for the variable
setting of the control times of gas exchange valves of an internal
combustion engine, having a stator (2) and an output element (3)
which is arranged coaxially with respect to the former, the two
components being mounted such that they can rotate with respect to
one another, and having a housing (11) which is configured
separately with respect to the stator (2) and with respect to the
output element (3) and which surrounds the stator (2) and the
output element (3) at least partly and prevents engine oil escaping
from the apparatus (1), an outer circumferential surface of the
stator (2) being configured in the circumferential direction with a
radial profile, into which the housing (11) protrudes in such a way
that a form-fitting connection of both components is produced in
the circumferential direction.
Inventors: |
Boese; Olaf; (Nurnberg,
DE) ; Scheidig; Gerhard; (Nurnberg, DE) ;
Strauss; Andreas; (Forchheim, DE) ; Ottersbach;
Rainer; (Aurachtal, DE) |
Correspondence
Address: |
LUCAS & MERCANTI, LLP
475 PARK AVENUE SOUTH
15TH FLOOR
NEW YORK
NY
10016
US
|
Assignee: |
SCHAEFFLER KG
Industriestrasse 1-3
Herzogenaurach
DE
|
Family ID: |
37447162 |
Appl. No.: |
11/419301 |
Filed: |
May 19, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60682885 |
May 20, 2005 |
|
|
|
Current U.S.
Class: |
123/90.17 |
Current CPC
Class: |
F01L 2301/00 20200501;
F01L 1/022 20130101; F01L 2001/34469 20130101; F01L 2001/34496
20130101; F01L 1/024 20130101; F01L 1/3442 20130101; F01L 2303/00
20200501; F01L 1/026 20130101 |
Class at
Publication: |
123/090.17 |
International
Class: |
F01L 1/34 20060101
F01L001/34 |
Claims
1. Apparatus for the variable setting of the control times of gas
exchange valves of an internal combustion engine, comprising: a
stator and an output element which is arranged coaxially with
respect to the stator, the stator and the output element being
mounted such that they can rotate with respect to one another, a
housing which is configured separately with respect to the stator
and with respect to the output element and which surrounds the
stator and the output element at least partly, wherein an outer
circumferential surface of the stator is configured in the
circumferential direction with a radial profile, into which the
housing protrudes in such a way that a form-fitting connection of
both components is produced in the circumferential direction.
2. Apparatus according to claim 1, the housing prevents pressure
medium from escaping from the apparatus.
3. Apparatus according to claim 1, wherein at least one pressure
space is formed between the stator and the output element, the
housing comprises at least two housing elements, and at least one
flat section of the housing which stands perpendicularly with
respect to the axial direction of the apparatus acts as a sealing
face for the pressure space in the axial direction.
4. Apparatus according to claim 1, wherein the stator is configured
as a sheet-metal part which is formed without cutting.
5. Apparatus according to claim 4, wherein the stator is
manufactured by a deep-drawing process.
6. Apparatus according to claim 3, wherein at least one of the
housing elements configured as a sheet-metal part which is formed
without cutting.
7. Apparatus according to claim 6, wherein at least one housing
element is manufactured by a deep-drawing process.
8. Apparatus according to claim 1, wherein the two housing elements
are connected to one another by means of a welded connection.
9. Apparatus according to claim 1, wherein a cylindrical section
which extends in the axial direction is formed on the housing for
sealing off the apparatus with respect to a radial shaft sealing
ring.
10. Apparatus according to claim 9, wherein a camshaft engages into
the section, and in that a gap is formed between the internal
diameter of the section and the camshaft.
11. Apparatus according to claim 1, wherein shaped elements are
formed on at least one of the housing elements in order to increase
the surface area.
12. Apparatus according to claim 1, wherein a locking device is
provided, a locking pin engaging into a slotted guide which is
formed on a sealing washer, and the sealing washer being composed
of a hardenable steel.
Description
FIELD OF THE INVENTION
[0001] The invention relates to an apparatus for the variable
setting of the control times of gas exchange valves of an internal
combustion engine, having a stator and an output element which is
arranged coaxially with respect to the former, the two components
being mounted such that they can rotate with respect to one
another, and having a housing which is configured separately with
respect to the stator and with respect to the output element and
which surrounds the stator and the output element at least
partly.
[0002] In internal combustion engines, camshafts are used to
actuate the gas exchange valves. Camshafts are attached in the
internal combustion engine in such a way that cams which are
attached to them bear against cam followers, for example cup
tappets, drag levers or valve rockers. If a camshaft is set in
rotation, the cams roll on the cam followers which in turn actuate
the gas exchange valves. Both the opening duration and the opening
amplitude, and also the opening and closing times of the gas
exchange valves, are therefore fixed by the position and the shape
of the cams.
[0003] Modern engine concepts tend to design the valve timing
mechanism in a variable manner. Firstly, the valve stroke and the
valve opening duration are to be designed to be variable, extending
as far as the complete switching-off of individual cylinders. For
this purpose, concepts are provided such as switchable cam
followers or electrohydraulic or electric valve actuating systems.
Furthermore, it has proven advantageous to be able to influence the
opening and closing times of the gas exchange valves during
operation of the internal combustion engine. Here, it is
particularly desirable to be able to influence the opening and
closing times of the inlet and the outlet valves separately, in
order, for example, to set a defined valve overlap in a targeted
manner. As a result of the setting of the opening and closing times
of the gas exchange valves as a function of the current range of
the characteristic diagram of the engine, for example as a function
of the current rotational speed or the current load, the specific
fuel consumption can be reduced, the exhaust-gas behaviour can be
influenced positively, and the engine efficiency, the maximum
torque and the maximum power output can be increased.
[0004] The above-described variability of the valve control times
is achieved by a relative change in the phase position of the
camshaft with respect to the crankshaft. Here, the camshaft is
usually drive-connected to the crankshaft via a chain drive, belt
drive, gearwheel drive, or drive concepts which function in an
identical manner. An apparatus for changing the control times of an
internal combustion engine, also called a camshaft adjuster in the
following text, is attached between the chain drive, belt drive or
gearwheel drive which is driven by the crankshaft and the camshaft,
which apparatus transmits the torque from the crankshaft to the
camshaft. Here, this apparatus is configured in such a way that,
during operation of the internal combustion engine, the phase
position between the crankshaft and the camshaft is maintained
reliably and, if desired, the camshaft can be rotated in a defined
angular range with respect to the crankshaft.
[0005] Belt-driven camshaft adjusters are usually arranged outside
the cylinder head. It is to be noted here that the camshaft
adjuster must be sealed off completely with respect to the
surroundings, in order to prevent leakage of engine oil into the
engine compartment. Any leakage oil which occurs must be collected
and led back into the cylinder head.
[0006] In internal combustion engines having in each case one
camshaft for the inlet valves and one camshaft for the outlet
valves, the said camshafts can be equipped with in each case one
camshaft adjuster. As a result, the opening and closing times of
the inlet and outlet valves can be shifted temporally relative to
one another and the valve overlaps can be set in a targeted
manner.
[0007] Modern camshaft adjusters are usually seated at the
drive-side end of the camshaft. However, the camshaft adjuster can
also be arranged on an intermediate shaft, a non-rotating component
or the crankshaft. The said camshaft adjuster comprises a drive
wheel which is driven by the crankshaft and maintains a fixed phase
relationship with respect to the latter, an output part which is
drive-connected to the camshaft and an adjusting mechanism which
transmits the torque from the drive wheel to the output part. In
the case of a camshaft adjuster which is not arranged on the
crankshaft, the drive wheel can be configured as a chain sprocket,
a belt pulley or a gearwheel and is driven by the crankshaft by
means of a chain drive, a belt drive or a gearwheel drive. The
adjusting mechanism can be operated electrically (by means of a
driven three-shafted gear mechanism), hydraulically or
pneumatically.
[0008] One preferred embodiment of hydraulic camshaft adjusters is
what is known as the rotary piston adjuster. In the latter, the
drive wheel is connected fixedly in terms of rotation to a stator.
The stator and an output element are arranged concentrically with
respect to one another, the output element being connected to a
camshaft, an extension of the camshaft or an intermediate shaft
with a force-transmitting, form-fitting or material-to-material
connection, for example by means of a press fit, a screw connection
or welded connection. A plurality of hollow spaces which are spaced
apart in the circumferential direction and extend radially outwards
starting from the output element are formed in the stator. The
hollow spaces are delimited in a pressure-tight manner in the axial
direction by side covers. A vane which is connected to the output
element and divides every hollow space into two pressure chambers
extends into each of these hollow spaces. The phase of the camshaft
relative to the crankshaft can be set or maintained by targeted
connection of the individual pressure chambers to a pressure-medium
pump or to a tank.
[0009] In order to control the camshaft adjuster, sensors detect
the characteristic data of the engine, such as the load state and
the rotational speed. This data is fed to an electronic control
unit which, after comparison of the data with an engine data map of
the internal combustion engine, controls the inflow and the outflow
of pressure medium to and from the different pressure chambers.
[0010] In order to adjust the phase position of the camshaft with
respect to the crankshaft, in hydraulic camshaft adjusters one of
the two pressure chambers, which act against one another, of a
hollow space is connected to a pressure-medium pump and the other
is connected to the tank. As a result, the vane is displaced and
the camshaft is therefore rotated directly with respect to the
crankshaft by the application of pressure to one chamber and by the
pressure relief of the other chamber. In order to maintain the
phase position, both pressure chambers are either connected to the
pressure-medium pump or are disconnected both from the
pressure-medium pump and from the tank.
[0011] The pressure-medium flows to and from the pressure chambers
are controlled by means of a control valve, usually a 4/3-way
proportional valve. A valve housing is provided with in each case
one connection for the pressure chambers (working connection), one
connection to the pressure-medium pump and at least one connection
to a tank. An axially displaceable control piston is arranged
within the valve housing which is of substantially
hollow-cylindrical configuration. The control piston can be moved
axially into every position between two defined end positions by
means of an electromagnetic actuator counter to the spring force of
a spring element. Furthermore, the control piston is provided with
annular grooves and control edges, as a result of which the
individual pressure chambers can be connected optionally to the
pressure-medium pump or the tank. A position of the control piston
can likewise be provided, in which position the pressure chambers
are disconnected both from the pressure-medium pump and also from
the pressure-medium tank.
[0012] DE 199 08 934 A1 has disclosed an apparatus of this type.
Here, it is an apparatus of the rotary piston construction type. A
stator is mounted rotatably on an output element which is connected
fixedly in terms of rotation to a camshaft. The stator is
configured with recesses which are open towards the output element.
Compensation washers are provided in the axial direction of the
apparatus, which compensation washers delimit the recesses in the
axial direction in a sealing manner. The recesses are closed in a
pressure-tight manner by the stator, the output element and the
compensation washers and therefore form pressure spaces. Vanes
which extend into the recesses are formed on the outer
circumferential face of the output element. The vanes are
configured in such a way that they divide the pressure spaces into
in each case two pressure chambers which act against one another.
The phase position of the output element with respect to the stator
and therefore of the camshaft with respect to the crankshaft can be
maintained or adjusted optionally by introducing or discharging
pressure medium to or from the pressure chambers. For this purpose,
a device is provided for supplying pressure medium having
pressure-medium lines and a control valve.
[0013] The stator, the output element and the compensation washers
are encapsulated by a two-part housing which is connected fixedly
in terms of rotation to a drive wheel which is configured as a
toothed belt pulley by means of fastening means.
[0014] The flat bases of the housing halves ensure pressure-tight
contact of the compensation washers with the stator and the output
element.
[0015] Furthermore, the drive torque of the crankshaft is
transmitted with a friction fit to the stator via the drive wheel
and the bases of the compensation washers. As an alternative, it is
proposed that the side faces of the stator have a profile, as a
result of which an additional form-fitting connection can be
attained.
[0016] In this embodiment, a large number of components are
required to realize the apparatus, as a result of which increased
assembly expenditure and therefore manufacturing costs occur.
Furthermore, the above-described transmission of the torque from
the drive wheel to the stator involves increased manufacturing
expenditure which has a negative effect on the costs of the
apparatus.
SUMMARY OF THE INVENTION
[0017] The invention is therefore based on the object of avoiding
these described disadvantages and therefore of proposing an
apparatus for the variable setting of the control times of gas
exchange valves of an internal combustion engine, in which the
number of components and therefore the assembly complexity and the
manufacturing costs of the apparatus are reduced. Furthermore, the
apparatus is to be improved in such a way that the transmission of
the torque of the crankshaft to the stator is improved and is
achieved with less expensive measures.
[0018] According to the invention, the object is achieved in that
an outer circumferential surface of the stator is configured in the
circumferential direction with a radial profile, into which the
housing protrudes in such a way that a form-fitting connection of
both components is produced in the circumferential direction.
[0019] Apparatuses of this type can be provided with a chain
sprocket, a belt pulley or a gearwheel and can be drive-connected
to the crankshaft via a chain drive, a toothed-belt drive or a
gearwheel drive.
[0020] If the apparatus is to be driven by means of a toothed belt,
the housing is to be configured in such a way that it prevents
pressure-medium escaping from the apparatus.
[0021] Here, there can be provision for at least one pressure space
to be formed between the stator and the output element, the housing
to comprise at least two housing elements, and at least one flat
section of the housing which stands perpendicularly with respect to
the axial direction of the apparatus to act as a sealing face for
the pressure space in the axial direction.
[0022] In developments of the invention, the stator and/or at least
one of the housing elements can be configured as a sheet-metal part
which is formed without cutting. As an alternative, the stator can
be of solid configuration, for example as a sintered component.
[0023] If the stator and/or the at least one housing element are
configured as a sheet-metal part which is formed without cutting,
these components can be manufactured by a deep-drawing process.
[0024] The two housing elements can be connected to one another by
means of a welded connection, as a result of which the housing
prevents pressure medium escaping from the apparatus.
[0025] In one advantageous development of the invention, there can
be provision for a cylindrical section which extends in the axial
direction to be formed on the housing for sealing off the apparatus
with respect to a radial shaft sealing ring. In addition, there can
be provision for a camshaft to engage into the section, and for a
gap to be formed between the internal diameter of the section and
the camshaft. As a result, the apparatus can be arranged outside
the cylinder head, the section engaging into an opening of the
cylinder head and being sealed off with respect to the latter by
means of the radial shaft seal. Leakage oil which occurs can be
guided back into the cylinder head and therefore into the crankcase
via the gap between the section and the camshaft.
[0026] In a further advantageous development of the invention,
there is provision for shaped elements to be formed on at least one
of the housing elements in order to increase the surface area.
These shaped elements serve firstly to reinforce the housing, and
secondly to increase its surface area, which leads to improved
cooling of the apparatus. The shaped elements can be configured,
for example, as cooling fins.
[0027] The following two objects, inter alia, are achieved by the
encapsulation of the stator and the output element by way of a
housing. Firstly, the housing serves to close the pressure spaces
in the axial direction of the apparatus in a pressure-tight manner.
This can take place either indirectly, by pressing sealing washers
against the stator, or directly, by the formation of sealing faces
on the housing. In the case of apparatuses which are driven by
toothed belts and are usually arranged outside the cylinder head,
the housing additionally serves as an encapsulation of the
apparatus which prevents pressure medium escaping from the
apparatus into the engine compartment. Any leakage oil which occurs
is collected within the housing and guided back into the engine
compartment via an axial section. The output element is usually
configured as a sintered component in these embodiments, which
sintered component has to be sealed in a work step which follows
the shaping process. This work step is usually very time-intensive
and therefore cost-intensive.
[0028] Sealing work steps of this type can be dispensed with by the
configuration of the housing as a sheet-metal part which is formed
without cutting and is inherently oil-tight. Furthermore, the
number of connecting points to be sealed will be reduced from at
least two (between the side covers and the stator) to one (between
the housing halves).
[0029] In comparison with the apparatus which is described in the
prior art, a cost advantage can be achieved by the fact that at
least the function of one of the sealing washers is integrated into
the housing. To this end, at least one base of a section of the
housing of cup-shaped configuration is configured to be flat. This
base bears in a pressure-tight manner both against the stator and
against the output element in the axial direction.
[0030] The housing comprises two housing elements, into which the
stator and the output element can be placed. Here, both housing
elements can be of cup-shaped configuration. An embodiment with a
cup-shaped housing element and a flat housing element is likewise
conceivable. The housing elements can be connected to one another
by means of connecting means, such as screws or bolts, or with a
force-fitting or material-to-material fit. The base of at least one
of the cup-shaped sections is flat and configured in such a way
that it delimits the pressure spaces which are formed between the
stator and the output element in a pressure-tight manner in an
axial direction. It is likewise conceivable that the pressure
spaces are delimited in both axial directions by flat sections of
the housing which stand perpendicularly with respect to the axial
direction of the apparatus.
[0031] The costs of the apparatus can be reduced considerably by
the reduction in the number of components and the associated lower
assembly expenditure. Here, the inexpensive manufacture of the
housing elements by way of a forming process without cutting, for
example a deep-drawing process, likewise has a positive effect.
[0032] The use of a stator which is manufactured from a sheet-metal
blank in a forming process without cutting is likewise conceivable.
A radial profile is formed in the circumferential direction of the
stator by the configuration of the stator as a thin-walled shaped
sheet-metal part. In this case, the stator comprises radially outer
circumferential walls, radially inner circumferential walls and
side walls which in each case connect an inner circumferential wall
to an outer circumferential wall. This profile can be used to
transmit the torque, which is transmitted from the drive wheel to
the housing, to the stator. To this end, the internal diameter of
the circumferential surface of the cup-shaped section or sections
is adapted to the external diameter of the outer circumferential
walls. As a consequence, the stator can be accommodated in the
housing, the said stator being centred at the same time relative to
the housing. Formed recesses are provided between the outer
circumferential walls of the stator on the cup-shaped section or
sections of the housing element or housing elements, which formed
recesses are configured in such a way that they bear against the
respective side walls. As a result, a form-fitting connection is
produced in the circumferential direction, via which the torque can
be transmitted from the housing to the stator. The stator can be
manufactured so as to be thinner and therefore lighter and less
expensive as a result of the transmission of the torque by means of
surfaces which are in contact in the circumferential direction and
the increased contact surface area. Moreover, this type of
connection can be manufactured considerably more reliably.
[0033] Furthermore, the formed recesses in the housing can be used
for the engagement of the drive wheel. A connection which is
form-fitting in the circumferential direction can also be produced
at this point by the shaping of an internal circumferential surface
of the drive wheel which is complementary to the external
circumferential surface of the housing.
[0034] The use of this form-fitting connection between the housing
and a stator of solid configuration, for example made from sintered
metal, is likewise conceivable. For this purpose, the profile of
the external circumferential surface of the stator is
advantageously taken into consideration as early as in the shaping
die. As a result, no additional costs are produced, whereas the
quality of the connection between the stator and the housing can be
improved considerably.
[0035] The invention is of course also conceivable in apparatuses
which are driven by chain sprockets or gearwheels.
[0036] In one advantageous development of the invention, a locking
device is provided, a locking pin engaging into a slotted guide
which is formed on a sealing washer, and the sealing washer being
composed of a hardenable steel.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] Further features of the invention result from the following
description and the drawings, in which exemplary embodiments of the
invention are shown in a simplified manner and in which:
[0038] FIG. 1a shows an internal combustion engine in a purely
diagrammatic manner,
[0039] FIG. 1 shows a longitudinal section through an apparatus
according to the invention,
[0040] FIG. 2 shows a plan view of the apparatus according to the
invention from FIG. 1, along the line II-II,
[0041] FIG. 3 shows a perspective view of a housing element of the
apparatus according to the invention according to FIG. 1, and
[0042] FIG. 4 shows a plan view of the further apparatus according
to the invention, in an analogous manner to that from FIG. 1, along
the line II-II.
DETAILED DESCRIPTION OF THE DRAWINGS
[0043] FIG. 1a outlines an internal combustion engine 100, a piston
102 which sits on a crankshaft 101 being indicated in a cylinder
103. In the embodiment shown, the crankshaft 101 is connected to an
inlet camshaft 106 and an outlet camshaft 107 via in each case one
flexible drive 104 and 105, respectively, it being possible for a
first and a second apparatus 1 to ensure a relative rotation
between the crankshaft 101 and the camshafts 106, 107. Cams 108,
109 of the camshafts 106, 107 actuate an inlet gas exchange valve
110 and the outlet gas exchange valve 111. There can likewise be
provision to equip only one of the camshafts 106, 107 with an
apparatus 1, or to provide only one camshaft 106, 107 which is
provided with an apparatus 1.
[0044] FIGS. 1 and 2 show a first embodiment of an apparatus 1 for
the variable setting of the control times of gas exchange valves of
an internal combustion engine. In the following text, the invention
will be explained using an apparatus 1 which is driven by a belt.
Apparatuses which are driven by chains or gearwheels are likewise
conceivable. The special feature of the apparatuses which are
driven by belts lies in their pressure-medium-tight encapsulation
which is not necessary in the other embodiments. An adjusting
apparatus 1a essentially comprises a stator 2 and an output element
3 which is arranged concentrically with respect to the former. FIG.
2 shows a plan view of a sealing washer 12, components which lie
behind the said sealing washer 12 being indicated by dashed
lines.
[0045] The output element 3 comprises a wheel hub 4, on the outer
circumference of which axially extending vane slots 5 are formed,
and five vanes 6 which are arranged in the vane slots 5 and extend
radially outwards. Furthermore, the output element 3 is provided
with a stepped central hole 4a, into which a camshaft (not shown)
engages in the mounted state of the apparatus 1, from the right in
FIG. 1. In the mounted state of the apparatus 1, the latter is
connected fixedly in terms of rotation to the camshaft, for example
by means of a force-transmitting, frictional, form-fitting or
material-to-material connection, or by means of fastening
means.
[0046] The stator 2 is configured as a thin-walled sheet-metal
part, the latter comprising inner circumferential walls 7 and outer
circumferential walls 8 which are connected to one another via side
walls 9. The inner and the outer circumferential walls 7, 8 extend
substantially in the circumferential direction, whereas the side
walls 9 extend substantially in the radial direction. The stator 2
is manufactured in one piece from a sheet-metal blank, by means of
a forming process without cutting. Here, there can be provision to
manufacture the stator 2 without cutting by means of a deep-drawing
method, for example from a steel sheet. The stator 2 is mounted
rotatably on the output element 3 via the inner circumferential
walls 7 which bear against a cylindrical circumferential wall of
the output element 3. Starting from the inner circumferential walls
7, the side walls 9 extend substantially in the radial direction
outwards and merge into the outer circumferential walls 8. As a
result of this construction, a plurality of pressure spaces 10,
five in the embodiment shown, are formed which, as described in the
following text, are closed off in a pressure-tight manner in the
axial direction by a housing 11 or by a sealing washer 12.
[0047] The vanes 6 are arranged on the outer circumferential
surface of the output element 3 in such a way that in each case one
vane 6 extends into a pressure space 10. Here, the vanes 6 bear in
a pressure-tight manner against the outer circumferential walls 8
of the stator 2 in the radial direction. For this purpose, spring
elements 13 which displace the vanes 6 radially outwards are
arranged in the vane slots 5. The width of the vanes 6 is
configured in such a way that the vanes 6 bear against the housing
11 or the sealing washer 12 in the axial direction. As a result, it
is achieved that each vane 6 divides a pressure space 10 into two
pressure chambers 14, 15 which act against one another.
[0048] The stator 2 and the output element 3 are arranged within
the housing 11 which is configured in such a way that it
encapsulates these components in an oil-tight manner. The housing
11 comprises a first housing element 16 which is of substantially
cup-shaped configuration and a disc-shaped second housing element
17. The connecting point of the housing elements 16, 17 can be
sealed by means of a sealing medium (not shown) or by means of
sealing joining processes. In the embodiment shown, a welded
connection 16a is provided which runs in the circumferential
direction. The first housing element 16 is arranged on that side of
the apparatus 1 which faces the camshaft. A flat section, which
stands perpendicularly with respect to the axial direction of the
apparatus 1, of a cup-shaped section of the first housing element
16, called the base 18 in the following text, is positioned
symmetrically with respect to the rotational axis of the first
housing element 16, a cylindrical section 19 which extends in the
axial direction being formed. The section 19 serves firstly to
accommodate the camshaft (not shown) or a pressure-medium
distributor. Secondly, the outer circumferential surface of the
cylindrical section 19 can be used as a seat for a radial shaft
seal 20 in the case of a belt-driven apparatus 1, which radial
shaft seal 20 seals the apparatus 1 with respect to a cylinder head
(not shown).
[0049] The internal diameter of the substantially cylindrical
circumferential surface of the cup-shaped section of the first
housing element 16 is adapted to the external diameter of the outer
circumferential walls 8 of the stator 2. This ensures a centered
accommodation of the stator 2 in the first housing element 16.
Furthermore, the substantially cylindrical circumferential surface
of the first housing element 16 is provided with formed recesses 21
which extend radially inwards between adjacent outer
circumferential walls 8 of the stator 2. The formed recesses 21 are
configured in such a way that they bear against the respective two
side walls 9 of the stator 2 in the circumferential direction. As a
result, a form-fitting connection is produced in the
circumferential direction between the stator 2 and the housing 11,
as a result of which the two components are connected to one
another fixedly in terms of rotation. Here, there can be provision
for the formed recesses 21 to extend as far as the inner
circumferential walls 7 of the stator 2, or for the formed recesses
21 to engage only partly into this hollow space.
[0050] Furthermore, a radially extending collar 22, in which holes
23 are formed, is formed on that end of the first housing element
16 which faces away from the camshaft.
[0051] The second housing element 17 is arranged coaxially with
respect to the first housing element 16, the outer circumferential
surface of the second housing element 17 being configured in a
complementary manner to the collar 22 of the first housing element
16. The two housing elements 16, 17 and a drive wheel 24 which is
configured as a belt pulley are connected to one another fixedly in
terms of rotation by means of connecting means 24, screws in the
exemplary embodiment shown. As an alternative, force-transmitting
or material-to-material connecting methods can also be provided. In
addition, the inner circumferential surface of the drive wheel 24
can be configured in a complementary manner to the outer
circumferential surface of the first housing element 16, as a
result of which the drive wheel 24 engages into the formed recesses
21 of the first housing element 16 and the two components are
therefore connected in a form-fitting manner in the circumferential
direction. The introduction of the torque which is transmitted from
the crankshaft to the drive wheel 24 can then be transmitted via
the form-fitting connections between the drive wheel 24 and the
formed recesses 21 of the first housing element 16 and,
furthermore, via the form-fitting connections between the formed
recesses 21 and the stator 2 to the latter. This form-fitting
connection of the components in the circumferential direction
replaces the frictional connection which is described in the prior
art between the bases of the housing elements and an axial side
face of the stator 2. The transmitted forces therefore act in the
direction of the connection between the components and over a
considerably greater surface area, as a result of which the forces
can be transmitted reliably. The transmitted force is distributed
to a greater connecting surface area, as a result of which the
stator 2 can be configured with thinner walls. As a result, in
addition to the functional safety of the torque transmission, the
weight of the apparatus 1 and therefore its moment of inertia and
also the costs are reduced.
[0052] As shown in FIG. 1, the second housing element 17 can be
provided with a central opening 17a. In one embodiment of the
apparatus 1, in which the output element 3 is fastened to the
camshaft by means of a central screw, this opening 17a serves as an
engagement opening for a tool in order to tighten the central
screw. In this case, the opening 17a can be closed in an oil-tight
manner by means of a cover (not shown) after assembly of the
apparatus 1 on the camshaft.
[0053] Embodiments of the apparatus 1 are likewise conceivable, in
which the second housing element 17 is configured without an
opening 17a.
[0054] Shaped elements 11a are formed on the second housing element
17, which firstly reinforce the component and secondly increase the
surface area of the housing 11 and therefore contribute to improved
cooling. An embodiment of the shaped elements 11a as cooling fins
is particularly advantageous.
[0055] FIG. 3 shows a perspective view of the first housing element
16. The formed recesses 21 are clearly visible, which engage
inwardly into the hollow spaces of the stator 2 in the radial
direction. On the outer circumferential surface, the formed
recesses 21 likewise make engagement of the drive wheel 24
possible, the inner circumferential surface of the drive wheel 24
advantageously being adapted to the outer circumferential surface
of the first housing element 16.
[0056] As can be seen in FIG. 1, the pressure spaces 10 are closed
in a pressure-tight manner in the axial direction on that side of
the apparatus 1 which faces the camshaft by the base 18 of the
first housing element 16. For this purpose, the base 18 of the
first housing element 16 is of flat configuration and is arranged
in such a way that it adjoins the output element 3 or the stator 2
directly in the axial direction. A sealing washer 12 is arranged on
that side of the apparatus 1 which faces away from the camshaft
between the second housing element 17 and the stator 2 or the
output element 3. The outer circumference of the sealing washer 12
is adapted to the inner contour of the first housing element 16, as
a result of which the latter is connected fixedly in terms of
rotation to the housing 11 and therefore to the stator 2. It bears
both against the output element 3 and against the stator 2, at
least in the region of the pressure spaces, and is pressed against
the stator 2 by means of the second housing element 17, as a result
of which the pressure spaces 10 are closed in a pressure-tight
manner in this axial direction. As an alternative, it is likewise
conceivable to omit this sealing washer 12 and to seal the pressure
spaces 10 axially by way of the second housing element 17. For this
purpose, this second housing element 17 would likewise have to be
of flat configuration.
[0057] As a result of the fact that the base 18 of the first
housing element 16 is used as a sealing face for the pressure
spaces 10 in the axial direction, a second sealing washer can be
omitted, as a result of which the number of components and
therefore the assembly expenditure and the costs of the apparatus 1
can be reduced. These advantages could be increased by virtue of
the fact that the sealing washer 12 is likewise omitted and the
pressure spaces are likewise sealed in this axial direction by the
second housing element 17.
[0058] Furthermore, the apparatus 1 is provided with two groups of
pressure-medium lines 25, 26 which, starting from the central hole
4a of the output element 3, extend outwards in the radial
direction. Here, the first pressure-medium lines 25 open into the
first pressure chambers 14, whereas the second pressure-medium
lines 26 open into the second pressure chambers 15. Pressure medium
can be optionally fed to or guided away from the first or the
second pressure chambers 14, 15 by means of a pressure-medium
distributor which is arranged in the central hole 4a of the output
element 3, or alternatively by means of a control valve, via the
pressure-medium lines 25, 26. A pressure gradient can therefore be
built up between the first and second pressure chambers 14, 15, as
a result of which the vanes 6 are displaced in the circumferential
direction and the relative phase position of the output element 3
with respect to the stator 2 can therefore optionally be set in a
variable manner or maintained. As a result of the adjustment of the
phase position between the output element 3 which is connected
fixedly in terms of rotation to the camshaft and the stator 2 which
is drive-connected to the crankshaft, the phase position between
the crankshaft and the camshaft can be influenced in a targeted
manner and the control times of the gas exchange valves can
therefore be influenced relative to the position of the
crankshaft.
[0059] Furthermore, FIG. 2 shows an apparatus 27 for restricting
the angle of rotation, which is realized by a pin 28 which is
connected fixedly in terms of rotation to the output element 3 and
a cut-out 29 which is formed on the sealing washer 12. The pin 28
engages into the cut-out 29, the cut-out 29 extending in the
circumferential direction in such a way that the pin 28 comes to
bear against a substantially radially extending wall of the cut-out
29 in both extreme positions of the output element 3 with respect
to the stator 2. As a result, it is prevented that the vanes 6 dip
into the transition region between the outer circumferential walls
8 and the side walls 9. This prevents the vanes 6 from jamming on
the radii which are formed there.
[0060] In the event of insufficient pressure-medium supply to the
apparatus 1, for example during the starting phase of the internal
combustion engine or during idling, the output element 3 is moved
in an uncontrolled manner relative to the stator 2 on account of
the alternating torques and drag torques which the camshaft exerts
on the said output element 3. In a first phase, the drag torques of
the camshaft displace the output element 3 relative to the stator 2
in the circumferential direction which lies opposite to the
rotational direction of the stator 2, until this movement is
stopped by the apparatus 27 for restricting the angle of rotation.
Subsequently, the alternating torques which the camshaft exerts on
the output element 3 lead to the output element 3 and therefore the
vanes 6 oscillating to and fro in the pressure spaces 10, until at
least one of the pressure chambers 14, 15 is filled completely with
pressure medium. This leads to higher wear and to noise development
in the apparatus 1. Furthermore, the phase position between the
output element 3 and the stator 2 oscillates at a high amplitude in
this operational phase, which leads to irregular operation of the
internal combustion engine. In order to prevent this, a locking
device 30 is provided in the apparatus 1. The said locking device
30 comprises a locking pin 31 which is arranged in a recess of the
output element 3 and is displaced in the direction of the sealing
washer 12 by means of a spring. A slotted guide 32 is formed on the
sealing washer 12, into which slotted guide 32 the locking pin 31
is displaced in a maximum early position or a maximum late position
of the output element 3 with respect to the stator 2. In this case,
the locking pin 31 bears against the radial delimiting walls of the
slotted guide 32, the said locking pin 31 extending at the same
time into the receptacle which is formed on the output element 3.
As a result, a form-fitting, mechanical connection is produced
between the output element 3 and the stator 2 in a relative phase
position which corresponds to an optimum position for starting
and/or idling of the internal combustion engine. In addition to the
locking of the output element 3 to the stator 2 in one of the
maximum end positions, there can also be provision for both
components to be locked relative to one another in a centre
position. The sealing washer 12 is advantageously configured from a
hardenable steel. The sealing washer 12 is subjected to a hardening
process after being formed, as a result of which it can absorb the
forces which are transmitted via the locking pin 31 in a
functionally reliable way. This leads to an increased service life
of the apparatus 1.
[0061] Furthermore, means are provided, in order to displace the
locking pin 31 back into the receptacle when the apparatus 1 is
supplied sufficiently with pressure medium, and therefore to cancel
the locking action. In the embodiment shown, there is provision for
pressure medium to act on the slotted guide 32 via pressure-medium
channels 33. The pressure-medium channels 33 are configured as
grooves which are formed in the side face of the output element 3
and extend from at least one of the pressure chambers 14, 15 as far
as the slotted guide 32.
[0062] The pressure medium which is guided into the slotted guide
32 displaces the locking pin 31 back into the receptacle counter to
the force of the spring, as a result of which the fixed phase
relationship between the output element 3 and the stator 2 is
cancelled.
[0063] Here, there is provision for the pressure-medium channels 33
to communicate with the slotted guide 32 only in a defined small
angular interval of the phase position between the stator 2 and the
output element 3.
[0064] The housing 11 is advantageously configured as a sheet-metal
housing, the two housing elements 16, 17 being manufactured from a
sheet-metal blank by means of in each case one forming process
without cutting. Here, techniques such as deep-drawing processes
are to be considered, for example. The reliable sealing action of
the apparatus 1 is ensured by the formation of the housing 11 from
a steel-sheet blank, as a result of which the apparatus 1 can be
used as a belt-driven camshaft adjuster. Camshaft adjusters of this
type are usually arranged outside the cylinder head, as a result of
which reliable sealing of the apparatus 1 becomes necessary.
Leakage oil which occurs is collected by the formation of the
housing 11 as a sheet-metal formed part within the apparatus 1, and
can be returned into the cylinder head by channels which are formed
on the cylindrical section 19. As an alternative, an annular gap
can be formed between the section 19 and the camshaft, in order to
guide leakage oil back into the cylinder head. The first housing
element 16 is advantageously sealed relative to the cylinder head
via a radial shaft seal 20 which is arranged on the section 19.
[0065] Expensive post-treatment for sealing the output element 3
which is normally configured as a porous sintered component can be
omitted as a result of the encapsulation of the stator 2 and the
output element 3 within the housing 11. Any small leakage which
occurs as a result of the sintered material or at the sealing
locations is held within the apparatus 1 by the housing 11 and can
be returned into the cylinder head.
[0066] In the embodiment in which the pressure spaces 10 are closed
in a pressure-tight manner by means of a sealing washer 12 on that
side of the apparatus 1 which faces away from the camshaft, this
sealing washer 12 can at the same time serve as a compensation
washer, in order to compensate for any tolerances which occur of
the two housing elements 16, 17.
[0067] FIG. 4 shows a further embodiment of an apparatus 1
according to the invention. In this illustration, the sealing
washer 12 has been removed. This embodiment is largely identical to
the first embodiment, for which reason identical components have
been provided with identical reference numerals. In contrast to the
first embodiment, the stator 2a is not configured here as a
thin-walled sheet-metal formed part, but as a solid component.
Here, this can be, for example, a stator 2a made from a sintered
material. In this embodiment, the housing 11 fulfils the same
functions as in the first embodiment (torque transmission, sealing
of the pressure spaces 10), as a result of which the same
advantages are attained. The formed recesses 21 engage into
indentations 21a which are formed on the stator 2a. These
indentations can be formed on the sintered component without
additional costs by virtue of them already being taken into
consideration in the forming die.
LIST OF REFERENCE NUMERALS
[0068] 1 Apparatus [0069] 1a Adjusting apparatus [0070] 2 Stator
[0071] 2a Stator [0072] 3 Output element [0073] 4 Wheel hub [0074]
4a Central hole [0075] 5 Vane slot [0076] 6 Vane [0077] 7 Inner
circumferential wall [0078] 8 Outer circumferential wall [0079] 9
Side wall [0080] 10 Pressure space [0081] 11 Housing [0082] 11a
Shaped element [0083] 12 Sealing washer [0084] 13 Spring element
[0085] 14 First pressure chamber [0086] 15 Second pressure chamber
[0087] 16 First housing element [0088] 16a Welded connection [0089]
17 Second housing element [0090] 17a Opening [0091] 18 Base [0092]
19 Section [0093] 20 Radial shaft seal [0094] 21 Formed recesses
[0095] 22 Collar [0096] 23 Holes [0097] 24 Drive wheel [0098] 25
First pressure-medium line [0099] 26 Second pressure-medium line
[0100] 27 Apparatus for restricting the angle of rotation [0101] 28
Pin [0102] 29 Cut-out [0103] 30 Locking device [0104] 31 Locking
pin [0105] 32 Slotted guide [0106] 33 Pressure-medium channel
[0107] 100 Internal combustion engine [0108] 101 Crankshaft [0109]
102 Piston [0110] 103 Cylinder [0111] 104 Flexible drive [0112] 105
Flexible drive [0113] 106 Inlet camshaft [0114] 107 Outlet camshaft
[0115] 108 Cam [0116] 109 Cam [0117] 110 Inlet gas exchange valve
[0118] 111 Outlet gas exchange valve
* * * * *