U.S. patent application number 12/616428 was filed with the patent office on 2010-05-13 for rotary piston adjuster having a torsion spring.
This patent application is currently assigned to SCHAEFFLER KG. Invention is credited to Mario Arnold, Sven Weisser.
Application Number | 20100116233 12/616428 |
Document ID | / |
Family ID | 41692037 |
Filed Date | 2010-05-13 |
United States Patent
Application |
20100116233 |
Kind Code |
A1 |
Weisser; Sven ; et
al. |
May 13, 2010 |
ROTARY PISTON ADJUSTER HAVING A TORSION SPRING
Abstract
A rotary piston adjuster for an internal combustion engine that
includes an outer rotor which can be drive-connected to a
crankshaft, an inner rotor which can be connected to a camshaft,
and a torsion spring which is connected to the outer and inner
rotors. The rotors can be adjusted rotationally about a common
rotational axis, and a rotary angle position of the inner rotor
with respect to the outer rotor can be adjusted by means of a
hydraulic actuating mechanism. The torsion spring is connected by
way of a hook-shaped first end section to a first connecting
element which is connected in a rotationally fixed manner to the
inner rotor. A pair of first supporting elements are connected to
the inner rotor for supporting the torsion spring, which first
supporting elements are arranged at an angular spacing in a range
from 90.degree. to 270.degree. from the first connecting
element.
Inventors: |
Weisser; Sven; (Weisendorf,
DE) ; Arnold; Mario; (Aurachtal, DE) |
Correspondence
Address: |
JAMES D. STEVENS;REISING ETHINGTON P.C.
P.O. BOX 4390
TROY
MI
48099
US
|
Assignee: |
SCHAEFFLER KG
Herzogenaurach
DE
|
Family ID: |
41692037 |
Appl. No.: |
12/616428 |
Filed: |
November 11, 2009 |
Current U.S.
Class: |
123/90.17 |
Current CPC
Class: |
F01L 1/3442 20130101;
F01L 2001/34483 20130101; F01L 1/344 20130101 |
Class at
Publication: |
123/90.17 |
International
Class: |
F01L 1/34 20060101
F01L001/34 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 11, 2008 |
DE |
102008056796.5 |
Claims
1. A rotary piston adjuster for an internal combustion engine,
which rotary piston adjuster comprises the following: an outer
rotor which can be drive-connected to a crankshaft; an inner rotor
which can be connected in a rotationally fixed manner to a
camshaft, the outer and inner rotors being mounted such that they
can be adjusted rotationally about a common rotational axis, and it
being possible for a rotary angle position of the inner rotor with
respect to the outer rotor to be adjusted by means of a hydraulic
actuating mechanism which comprises at least one pair of pressure
chambers which act counter to one another; a torsion spring which
is rotationally coupled to the outer and inner rotors in such a way
that the inner rotor is prestressed in an adjusting direction with
respect to the outer rotor, the torsion spring being connected by
way of a hook-shaped first end section to a first connecting
element which is connected in a rotationally fixed manner to the
inner rotor; and at least two first supporting elements which are
connected in a rotationally fixed manner to the inner rotor for
supporting the torsion spring, which first supporting elements are
arranged at an angular spacing in the angular range from 90.degree.
to 270.degree. from the first connecting element.
2. The rotary piston adjuster as defined in claim 1, wherein a
first supporting element is arranged at least approximately at an
angular spacing of 180.degree. from the first connecting
element.
3. The rotary piston adjuster as defined in claim 1, wherein the
number of first supporting elements is two.
4. The rotary piston adjuster as defined in claim 3, wherein one of
the first supporting elements is at least approximately half as
great an angular spacing from the first connecting element as the
other first supporting element.
5. The rotary piston adjuster as defined in claim 3, wherein one of
the first supporting elements is at an angular spacing of greater
than 180.degree. from the first connecting element.
6. The rotary piston adjuster as defined in claim 1, wherein the
first supporting elements are at an at least approximately
identical radial spacing from the common rotational axis as the
first connecting element.
7. The rotary piston adjuster as defined in claim 1, wherein the
torsion spring is connected by way of a hook-shaped second end
section to a second connecting element which is connected in a
rotationally fixed manner to the outer rotor.
8. The rotary piston adjuster as defined in claim 7, further
comprising at least one second supporting element which is
connected in a rotationally fixed manner to the outer rotor for
supporting the torsion spring.
9. The rotary piston adjuster as defined in claim 8, wherein the at
least one second supporting element is at an at least approximately
identical radial spacing from the common rotational axis as the
second connecting element.
10. The rotary piston adjuster as defined in claim 1, wherein the
hook-shaped first end section of the torsion spring is bent away at
a bending angle of at most 90.degree. in relation to an extending
direction of a spring section which immediately adjoins the first
end section.
11. The rotary piston adjuster as defined in claim 1, wherein the
torsion spring is configured in the form of a helical spring.
12. The rotary piston adjuster as defined in claim 1, wherein the
torsion spring is arranged on a side of a side plate which faces
away from the inner rotor, in order to close the at least one pair
of pressure chambers in an axially pressure-tight manner.
13. The rotary piston adjuster as defined in claim 1, wherein the
connecting elements are configured in pin form.
14. The rotary piston adjuster as defined in claim 1, wherein the
supporting elements are configured in pin form.
15. An internal combustion engine having at least one rotary piston
adjuster as defined in claim 1.
Description
TECHNICAL FIELD
[0001] The invention is in the technical field of internal
combustion engines and generally relates to a rotary piston
adjuster for an internal combustion engine.
BACKGROUND OF THE INVENTION
[0002] In internal combustion engines with a mechanical valve
actuating mechanism, gas exchange valves are actuated by the cams
of a camshaft which is driven by a crankshaft, it being possible to
use the arrangement and the shape of the cams to fix the control
times of the valves for a defined phase relation between the
crankshaft and the camshaft. The control times of the valves can be
influenced via a change in the phase relation between the
crankshaft and the camshaft as a function of the instantaneous
operating state of the internal combustion engine, as a result of
which advantageous effects can be achieved, such as a reduction in
fuel consumption and pollutant generation. The use of special
apparatuses for optionally adjusting the phase relation between the
crankshaft and the camshaft is sufficiently well known, which
special apparatuses are usually called "camshaft adjusters".
[0003] In general, camshaft adjusters comprise a drive part which
is drive-connected to the crankshaft via a drive wheel, an output
part which is fixed to the camshaft, and an actuating mechanism
which is connected between the drive part and the output part,
which activating mechanism transmits the torque from the drive part
to the output part and makes it possible to adjust and fix the
phase relation between the two.
[0004] In a conventional design as a hydraulic rotary piston
adjuster, the drive part is configured as an outer rotor and the
output part is configured as an inner rotor, the outer and inner
rotors being arranged concentrically with regard to a common
rotational axis and such that they can be adjusted rotationally
with respect to one another. In the radial intermediate space
between the outer and inner rotors, at least one pressure space is
formed by one of the two rotors, into which pressure space a vane
which is connected to the respectively other rotor extends, as a
result of which the pressure space is divided into a pair of
pressure chambers which act counter to one another. The outer and
inner rotors can be rotated relative to one another by targeted
pressure loading of the pressure chambers, in order to bring about
a change in the phase relation between the crankshaft and the
camshaft as a result. Similarly, a phase relation can be maintained
by hydraulic stressing.
[0005] Alternating torques then occur on the camshaft during the
operation of the internal combustion engine, which alternating
torques, in the case of insufficient pressure medium supply, as is
the case, for example, during the starting phase or when idling,
lead to the inner and outer rotors being moved with respect to one
another in an uncontrolled manner. This can have the result that
the vanes strike to and fro within the pressure spaces, as a result
of which wear is increased and unpleasant noise is caused. In
addition, the phase relation between the crankshaft and the
camshaft varies to a pronounced extent in this case, with the
result that the internal combustion engine does not start or runs
uneasily.
[0006] In order to avoid this, hydraulic rotary piston adjusters
are equipped with a locking device for the rotationally fixed
locking of the outer and inner rotors, locking taking place in a
phase relation which is denoted as a basic position and is
favorable thermodynamically for starting the internal combustion
engine. The selection of the basic position depends on the concrete
design of the internal combustion engine and can be an early, late
or intermediate position, the late position corresponding to
maximum adjustment of the inner rotor in the trailing direction,
the early position corresponding to maximum adjustment of the inner
rotor in the leading direction and the intermediate position
corresponding to a rotary angle position between said two end
rotary positions, in relation to the rotational direction of the
camshaft. A rotary angle position of the inner rotor relative to
the outer rotor which is situated at least approximately in the
middle between the early and the late position is denoted as middle
position. In a corresponding way, adjustment of the inner rotor in
the direction of the early position is called early adjustment, and
adjustment in the opposite direction is called late adjustment.
[0007] The locking device for locking the outer and inner rotors in
the basic position in a rotationally fixed manner typically
comprises one or more bolts which are received in one of the two
rotors, can be moved, in the basic position, into positively
locking engagement with the respectively other rotor and can be
unlocked hydraulically in order to release the rotational
adjustability of the outer and inner rotors.
[0008] Hydraulic rotary piston adjusters having a locking device
for locking the outer and inner rotors in the basic position in a
rotationally fixed manner are described in detail, for example, in
documents DE 202005008264 U1, EP 1596040 A2, DE 102005013141 A1, DE
19908934 A1 and WO 2006/039966 from the applicant.
[0009] If the basic position is not reached during switching off of
the internal combustion engine, for example by "stalling" of the
engine, the inner rotor is adjusted automatically into the late
position on account of the frictional moments of the camshaft, with
the result that special precautionary measures are to be made for
locking in a basic position which is different than the late
position, by which precautionary measures the inner rotor is
adjusted in the early direction relative to the outer rotor, in the
direction of the basic position. In addition, the adjusting speed
in the two adjusting directions differs on account of the
frictional moments which act in the "late" direction, with the
result that matching of the adjusting speeds is desirable.
[0010] For this purpose, restoring or compensation springs are
installed which prestress the inner rotor with respect to the outer
rotor in the "early" direction. For example, German laid-open
specifications DE 10007200 A1 and DE 10215879 A1 describe in each
case rotary piston adjusters having restoring springs, by which the
inner rotor is prestressed with respect to the outer rotor in an
adjusting direction in order to reach the basic position.
[0011] Different variants which are used by the applicant in
industrial series production for the arrangement of restoring
springs in a rotary piston adjuster will now be described with
reference to FIGS. 3A-3C.
[0012] FIG. 3A is to be considered first of all, in which a first
variant for the arrangement of a helical spring 105 in a rotary
piston adjuster 101 is shown in a diagrammatic axial section
illustration. Accordingly, the rotary piston adjuster 101 which is
attached on the end side of a camshaft 104 comprises an outer rotor
102 which is drive-connected to a crankshaft (not shown) and an
inner rotor 103 which is connected in a rotationally fixed manner
to the camshaft 104, the outer and inner rotors being arranged
concentrically with respect to a common rotational axis 114 and
such that they can be adjusted rotationally with respect to one
another. A relative rotary angle position of the outer and inner
rotors can be changed or fixed by a hydraulic actuating mechanism
(not shown in greater detail). In addition, rotationally fixed
locking of the outer and inner rotors in a basic position which is
different than the late position is possible by way of a locking
device (likewise not shown in greater detail).
[0013] The helical spring 105 which comprises a plurality of radial
windings is connected by way of an inner hook 106 to a first
connecting pin 108 which projects axially from the inner rotor 103,
the inner hook 106 being bent away at a bending angle of
approximately 180.degree. with regard to a tangential extent
direction of the end of an inner winding 113. Furthermore, said
helical spring 105 is connected by way of an outer hook 107 to a
second connecting pin 109 which projects axially from the outer
rotor 102, the outer hook 107 being bent away at a bending angle of
approximately 90.degree. with regard to an extent direction of an
outer winding 112, with a curvature direction which changes with
regard to the helical spring 105.
[0014] Via a first supporting pin 110 which projects axially from
the inner rotor 103 and is at approximately the same radial spacing
from the rotational axis 114 of the camshaft 104 as the first
connecting pin 108, and by way of a second supporting pin 111 which
protrudes axially from the outer rotor 102 and is at approximately
the same radial spacing from the rotational axis 114 of the
camshaft 104 as the second connecting pin 109, the inner winding
113 and the outer winding 112 of the helical spring 105 are fixed
in their respective position, in order to prevent the hooked action
of the inner hook 106 with the first connecting pin 108 and that of
the outer hook 107 with the second connecting pin 109 becoming
released. In relation to the common rotational axis 114, both the
first connecting pin 108 and the first supporting pin 110 and also
the second connecting pin 109 and the second supporting pin 111 are
at in each case an angular spacing measured in the circumferential
direction of less than 90.degree..
[0015] A disadvantage of the arrangement which is shown in FIG. 3A
is, in particular, the fact that, in the case of a wraparound angle
of approximately 180.degree. of the inner hook 106, the radial
installation space requirement is increased on account of the
doubly placed inner winding 113. In addition, a rotational center
(not denoted in greater detail) of the helical spring 105 lies
outside the common rotational axis 114 of the arrangement, with the
result that an unbalance occurs in an undesirable way on account of
the eccentricity of the helical spring 105 caused by this.
[0016] FIG. 3B shows a second variant for the arrangement of the
helical spring 105. In order to avoid unnecessary repetitions, only
the differences from the first variant of FIG. 3A will be
explained, reference otherwise being made to the above comments
with respect to FIG. 3A. Accordingly, an at least approximately
symmetrical four-cornered shaft 115 is provided which is connected
in a rotationally fixed manner to the inner rotor 103, an inner
winding 113 of the helical spring 105 surrounding an outer face of
the four-cornered shaft 115 on three sides, as a result of which a
positively locking, rotationally fixed connection is formed between
the helical spring 105 and the four-cornered shaft 115. The
four-cornered shaft 115 is arranged in a manner which is centered
with respect to the rotational axis 114 of the camshaft 104, with
the result that the generation of an unbalance is avoided. However,
the four-cornered shaft 115 increases the radial installation space
requirement of the arrangement in an undesirable manner, and the
manufacturing costs for the camshaft adjuster 101 increase as a
result of the greater material requirement for the helical spring
105.
[0017] Finally, FIG. 3C shows a third variant for the arrangement
of the helical spring 105. In order to avoid unnecessary
repetitions, once again only the differences from the first variant
of FIG. 3A will be explained, reference being made otherwise to the
above comments on FIG. 3A. Accordingly, a cylindrical journal 116
is provided which is connected in a rotationally fixed manner to
the inner rotor 103 and is provided with an axial connecting groove
117, to which the inner hook 106 is connected. The inner winding
113 of the helical spring 105 bears largely against the journal
116, as a result of which a positively locking connection is
produced between the inner winding 113 and the journal 116. The
journal 116 is arranged coaxially with respect to the camshaft 104,
as a result of which an unbalance is avoided. However, in
industrial serial production, the shaping of the journal 116
requires an additional manufacturing step for turning and/or
milling of the inner rotor 103 and/or for the attachment of an
additional component on the inner rotor 103, as a result of which
the manufacturing costs for the rotary piston adjuster 101 are
increased. In addition, the component weight for the inner rotor
103 is increased.
SUMMARY OF THE INVENTION
[0018] It is an object of the present invention to provide a rotary
piston adjuster for which the disadvantages (explained above in
conjunction with FIGS. 3A-3C) of conventional rotary piston
adjusters can be avoided.
[0019] According to one aspect of the invention, there is provided
a rotary piston adjuster for adjusting the phase relation of the
crankshaft and the camshaft of an internal combustion engine. The
rotary piston adjuster comprises an outer rotor which can be
drive-connected to a crankshaft (or is fixed to the crankshaft) and
an inner rotor which can be connected in a rotationally fixed
manner to a camshaft (or is fixed to the camshaft). The rotors are
mounted in a concentric arrangement about a common rotational axis
such that they can be adjusted rotationally about the common axis.
The rotary angular position of the inner rotor with respect to the
outer rotor can be adjusted by means of a hydraulic actuating
mechanism which comprises at least one pair of pressure chambers
which act counter to one another.
[0020] Furthermore, the rotary piston adjuster comprises a torsion
spring which is rotationally coupled to the outer and inner rotors
in such a way that the inner rotor is prestressed in an adjusting
direction with respect to the outer rotor. The torsion spring is
connected by way of a hook-shaped, first end section to a first
connecting element which is connected in a rotationally fixed
manner to the inner rotor. In one embodiment, the torsion spring
can be advantageously configured in the form of a helical spring
with a plurality of radial spring windings, the spring plane being
directed perpendicularly with respect to the common rotational axis
of the outer and inner rotors.
[0021] The rotary piston adjuster includes at least two first
supporting elements which are connected in a rotationally fixed
manner to the inner rotor for supporting the torsion spring, which
first supporting elements are arranged at an angular spacing in the
angular range of from 90.degree. inclusive to 270.degree. inclusive
with respect to the first connecting element. In the context of the
present invention, the expression "angular spacing" relates to an
angular difference in the circumferential direction between radial
connecting lines which connect respective elements (connecting
and/or supporting elements) to the common rotational axis.
[0022] Release of the hook-shaped, first end section from its
hooked connection with the first connecting element can be
prevented by the first supporting elements, with the result that a
radial dimension of the rotary piston adjuster can advantageously
be reduced by the material thickness of the torsion spring.
[0023] According to one preferred embodiment of the rotary piston
adjuster according to the invention, a first supporting element for
supporting the torsion spring is arranged at least approximately at
an angular spacing of 180.degree. from the first connecting
element, as a result of which release of the hook-shaped, first end
section from its hooked connection with the first connecting
element can be prevented in a particularly effective way.
[0024] According to a further embodiment of the rotary piston
adjuster according to the invention, which embodiment is preferred,
in particular, with regard to the manufacturing costs, two first
supporting elements are provided for supporting the torsion spring,
which is to be preferred, in particular, when a first supporting
element is at an angular spacing of more than 180.degree. from the
first connecting element, in order in this way to ensure sufficient
support of the torsion spring with relatively low manufacturing
costs, even in the case of high torques. In this case, it can be
advantageous if a first supporting element is at least
approximately half as great an angular spacing from the first
connecting element as the other first supporting element, as a
result of which symmetrical support of the torsion spring can be
achieved.
[0025] According to a further preferred embodiment of the rotary
piston adjuster according to the invention, the first supporting
elements are at an at least approximately identical radial spacing
from the common rotational axis as the first connecting element,
with the result that the torsion spring can be arranged in a
centered manner with respect to the common rotational axis of the
outer and inner rotors, in order to avoid an unbalance in this way.
In this case, it can be advantageous if the rotary piston adjuster
is provided with at least one second supporting element which is
connected in a rotationally fixed manner to the outer rotor, for
supporting the torsion spring, in order, as a result, to prevent
release of the hook-shaped, second end section from its hooked
connection with the second connecting element. It can be
particularly preferred here if the at least one second supporting
element is at an at least approximately identical radial spacing
from the common rotational axis as the second connecting element,
in order to achieve an orientation of the torsion spring in a
simple way, which orientation is centered with respect to the
common rotational axis of the outer and inner rotors.
[0026] According to a further preferred embodiment of the rotary
piston adjuster according to the invention, the hook-shaped, first
end section of the torsion spring is bent away at a bending angle
of at most 90.degree. in relation to a (tangential) extent
direction of a spring section which is immediately adjacent to the
first end section.
[0027] In a further advantageous embodiment of the rotary piston
adjuster according to the invention, the torsion spring is arranged
on a side of a side plate which faces away from the inner rotor, in
order to close the at least one pair of pressure chambers in an
axially pressure-tight manner. In this case, in particular, it can
be advantageous if the connecting elements and/or supporting
elements are configured in each case in pin form, for example as
axial extensions of fastening screws for fastening the side plate
to a part of the outer rotor which forms the at least one pressure
space.
[0028] Furthermore, the invention can include an internal
combustion engine which is provided with at least one rotary piston
adjuster as described above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The invention will now be described in greater detail using
exemplary embodiments, reference being made to the appended
drawings. Elements which are identical and/or have the identical
action are denoted by the same designations in the drawings, in
which:
[0030] FIG. 1 shows a diagrammatic perspective axial view of a
first exemplary embodiment of the rotary piston adjuster according
to the invention, in order to illustrate the arrangement of a
restoring spring;
[0031] FIG. 2 shows a diagrammatic perspective axial view of a
second exemplary embodiment of the rotary piston adjuster according
to the invention, in order to illustrate the arrangement of a
restoring spring; and
[0032] FIGS. 3A-3C show diagrammatic perspective axial views of
conventional rotary piston adjusters, in order to illustrate the
arrangement of a restoring spring.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0033] FIG. 1 diagrammatically shows, in a perspective axial view,
a first exemplary embodiment of the rotary piston adjuster 1
according to the invention with early locking (locking in the early
position or leading direction as basic position).
[0034] The rotary piston adjuster 1 comprises an outer rotor 2
which is drive-connected to a crankshaft (not shown) via a chain
sprocket 16 and a chain drive (not shown), and an inner rotor 3
which is connected in a rotationally fixed manner to a camshaft 4,
the outer and inner rotors being arranged concentrically with
regard to a common rotational axis 15 of the camshaft 4 and such
that they can be adjusted rotationally with respect to one another.
The rotary piston adjuster 1 is fastened to the end side of the
camshaft 4, for example by means of a central screw.
[0035] A plurality of pressure spaces (not shown) are formed by the
outer rotor 2 in the radial intermediate space between the outer
and inner rotors, into which pressure spaces in each case a vane
extends which is connected to the inner rotor 3, as a result of
which each pressure space is divided into a pair of pressure
chambers which act counter to one another. By targeted pressure
loading of the pressure chambers which act counter to one another,
a rotary angular position of the inner rotor 3 with respect to the
outer rotor 4 can be changed or fixed by hydraulic clamping. Here,
the outer rotor 2 forms a pressure-tight housing for the rotary
piston adjuster 1, the pressure chambers being closed in an axially
pressure-tight manner by two side plates which are arranged on the
end side and of which only one side plate 17 can be seen in FIG. 1.
The side plate 17 is attached to a housing part 20 which forms the
pressure spaces and supports the chain sprocket 16, by a plurality
of axial fastening screws 18 which are distributed uniformly in the
circumferential direction. Furthermore, the side plate 17 is
provided with a circular aperture 19 which is centered with respect
to the rotational axis 15 of the camshaft 4 and releases the inner
rotor 3 or an attachment component which is connected in a
rotationally fixed manner to the inner rotor 3.
[0036] For locking the outer and inner rotors in the middle
position in a rotationally fixed manner, at least one axial or
radial locking pin (not shown) is provided in a conventional way
which is received, for example, in the inner rotor 3, is displaced
out of its receptacle in the axial or radial direction by a
compression coil spring, and can engage positively into a locking
guide which is formed by the outer rotor 2. In order to unlock the
locking pin, it can be loaded on the end side with pressure medium
and displaced back into its receptacle.
[0037] The precise construction of a rotary piston adjuster of this
type is sufficiently well known to a person skilled in the art, for
example from the documents which are cited in the introduction,
with the result that it does not have to be explained in greater
detail here.
[0038] Furthermore, the rotary piston adjuster 1 is provided with a
flat helical spring 5 which is arranged with its spring plane
perpendicular with respect to the axial direction, on that side of
the side plate 17 which faces away from the inner rotor 3. The
helical spring 5 is provided with a plurality of radial windings
which surround an imaginary axial extension of the camshaft 4. A
hook-shaped, first end section is formed as outer hook 6 on the
helical spring 5 and a hook-shaped, second end section is formed as
inner hook 7.
[0039] The inner hook 7 is connected to a first connecting pin 8
which projects from the inner rotor 3, the inner hook 7 being
formed in such a way that it surrounds the first connecting pin 8
partly positively. Here, the inner hook is bent at a bending angle
of approximately 90.degree. in the curvature direction of the
helical spring 5 (corner angle) with regard to a tangential extent
direction of a first spring section 21 of the inner winding 14,
which first spring section 21 immediately adjoins the inner hook 7,
which results in a wraparound angle of approximately 90.degree.
which describes the positive connection between the inner hook 7
and the first connecting pin 8.
[0040] Via a first supporting pin 10 which projects from the inner
rotor 3 and via a second supporting pin 11 which projects from the
inner rotor 3, which supporting pins 10, 11 are both in each case
at approximately the same radial spacing from the rotational axis
15 of the camshaft 4 as the first connecting pin 8, an inner wall
14 is fixed in such a way that release of the hooked connection of
the inner hook 7 with the first connecting pin 8 is prevented.
[0041] In relation to the common rotational axis 15, the first
connecting pin 8, the first supporting pin 10 and the second
supporting pin 11 (or their radial connecting lines to the
rotational axis 15) are arranged in an angular range of
approximately 270.degree., viewed in the counterclockwise
direction, however, beginning at the first connecting pin 8. In
particular, the first supporting pin 10 is arranged at least
approximately in the opposite position to the first connecting pin
8, according to an angular spacing A1 of approximately 180.degree.
between the first connecting pin 8 and the first supporting pin 10.
The second supporting pin 11 is arranged at an angular spacing A2
of approximately 270.degree. from the first connecting pin 8.
[0042] The outer hook 6 is connected to a second connecting pin 9
which projects from the outer rotor 2 and is formed as an axial
extension of a fastening screw 18, the outer hook 6 being formed in
such a way that it surrounds the second connecting pin 9 partly
positively. Here, the outer hook 6 is bent away at a bending angle
of approximately 170.degree. counter to the curvature direction of
the helical spring 5, with regard to a tangential extent direction
of a second spring section 22 of the outer winding 13, which second
spring section 22 immediately adjoins the outer hook 6. Via a third
supporting pin 12 which projects from the outer rotor 2, is formed
as an axial extension of a fastening screw 18 and is at
approximately the same radial spacing from the rotational axis 15
of the camshaft 4 as the second connecting pin 9, the outer winding
13 is fixed in such a way that release of the hooked connection of
the outer hook 6 with the second connecting pin 9 is prevented. In
relation to the rotational axis 15 of the camshaft 4, the second
connecting pin 9 and the third supporting pin 12 (or their radial
connecting lines to the rotational axis 15) are arranged in an
angular range of approximately 90.degree., as viewed in the
clockwise direction, beginning at the second connecting pin 9.
[0043] The helical spring 5 which is shown in FIG. 1 prestresses
the inner rotor 3 with respect to the outer rotor 2 in the "early"
direction, in order firstly to match the adjusting speeds in the
two adjusting directions and secondly to adjust the inner rotor 3
correspondingly in the "early" direction in order to reach the
basic position. As a result of the inner hook 7 which is bent away
at a bending angle of approximately 90.degree. with respect to the
extent direction of the helical spring 5, the radial dimension of
the rotary piston adjuster 1 can be reduced by the amount of the
material thickness of the helical spring 5 with respect to the
conventional connection (shown in FIG. 3A) of the helical spring 5.
The helical spring 5 is held centered with respect to the common
rotational axis 15 by the uniform support in the circumferential
direction of the helical spring 5 by means of three inner
supporting points, described by the first connecting pin 8, the
first supporting pin 10 and the second supporting pin 11, with the
result that an eccentric position of the helical spring 5 can be
avoided. In particular, this can reduce spring hysteresis and
ensure the freedom of movement with respect to the camshaft 4.
[0044] FIG. 2 shows, diagrammatically in an axial view, a second
exemplary embodiment of the rotary piston adjuster 1 according to
the invention with early locking (locking in the leading direction
as basic position).
[0045] In order to avoid unnecessary repetitions, only the
differences from the first exemplary embodiment shown in FIG. 1
will be explained, reference otherwise being made to the comments
made there.
[0046] Accordingly, the rotary piston adjuster 1 is provided with a
helical spring 5 which has an opposed winding direction of its
windings corresponding to a rotational direction of the camshaft 4
which is different than FIG. 1. Here, the first connecting pin 8,
the first supporting pin 10 and the second supporting pin 11 (or
radial connecting lines of them with the rotational axis 15) are
arranged within an angular range of approximately 270.degree.. In
the exemplary embodiment which is shown, the angular range begins
at the first connecting pin 8 and is measured in the clockwise
direction, in a corresponding manner to the radially increasing
course of the helical spring 5. In particular, the first supporting
pin 10 is arranged at least approximately in the opposite position
to the first connecting pin 8, according to a rotary angular
spacing A1 of approximately 180.degree. from the first connecting
pin 8. The second supporting pin 11 is arranged at least
approximately in the region of the bisector between the first
connecting pin 8 and the first supporting pin 10, corresponding to
a rotary angular spacing A2 of approximately 90.degree. from the
first connecting pin 8, as a result of which support of the helical
spring 5 is achieved which is particularly reliable with regard to
a hooked connection of the inner hook 7 with the first connecting
pin 8 and is suitable in equal measure for low and high
torques.
[0047] Although an inner support of the inner winding 14 of the
helical spring 5 by means of three supporting points is illustrated
in the exemplary embodiments, it is conceivable to provide only two
supporting points which lie at least approximately opposite one
another (that is to say, a hooked connection of the inner hook 7 on
the first connecting pin 8, and a first supporting pin 10 which is
arranged at a rotary angular spacing of approximately 180.degree.
from the first connecting pin 8) or more than three inner
supporting points, three inner supporting points being preferred
from the aspect of manufacturing costs. Instead of a helical spring
5, another torsion spring which is suitable for the rotational
adjustment of the outer and inner rotors, for example a torsion
coil spring, can likewise be provided.
* * * * *