U.S. patent number 10,385,933 [Application Number 15/244,213] was granted by the patent office on 2019-08-20 for freewheel and freewheel arrangement comprising such a freewheel.
This patent grant is currently assigned to BorgWarner Inc.. The grantee listed for this patent is BorgWarner Inc.. Invention is credited to Dirk Achim Schmitt, Florian Schneider, Matthias Gerhard Veit.
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United States Patent |
10,385,933 |
Schneider , et al. |
August 20, 2019 |
Freewheel and freewheel arrangement comprising such a freewheel
Abstract
The present invention relates to a freewheel comprising an outer
ring, an inner ring, and at least one clamping element which is
between the outer ring and the inner ring, which is moveable from a
clamping position into a release position along a race on the outer
ring in a first circumferential direction relative to the outer
ring, wherein the race has a clamping section, and a release
section following the clamping section in the first circumferential
direction on which the clamping element is supportable. A first
tangent through at least one support point on the clamping section
defines a first inner angle, which is greater than 180.degree.,
with a second tangent through at least one support point on the
release section. In addition, the present invention relates to a
freewheel arrangement for a motor vehicle comprising such a
freewheel.
Inventors: |
Schneider; Florian (Heilbad
Heiligenstadt, DE), Veit; Matthias Gerhard
(Oftersheim, DE), Schmitt; Dirk Achim (Leimen,
DE) |
Applicant: |
Name |
City |
State |
Country |
Type |
BorgWarner Inc. |
Auburn Hills |
MI |
US |
|
|
Assignee: |
BorgWarner Inc. (Auburn Hills,
MI)
|
Family
ID: |
58011017 |
Appl.
No.: |
15/244,213 |
Filed: |
August 23, 2016 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20170058970 A1 |
Mar 2, 2017 |
|
Foreign Application Priority Data
|
|
|
|
|
Aug 29, 2015 [DE] |
|
|
10 2015 011 415 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F16D
41/066 (20130101); F02N 15/023 (20130101); F02N
11/00 (20130101) |
Current International
Class: |
F02N
15/02 (20060101); F16D 41/066 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Scott; Jacob S.
Attorney, Agent or Firm: Miller, Matthias & Hull LLP
Claims
The invention claimed is:
1. A freewheel comprising an outer ring, an inner ring having a
circular counter-race, and at least one clamping element which is
between the outer ring and the inner ring, which is moveable from a
clamping position into a release position along a race on the outer
ring in a first circumferential direction relative to the outer
ring, wherein the race has a clamping section, and a release
section following the clamping section in the first circumferential
direction on which the clamping element is supportable,
characterized in that a first tangent through at least one support
point on the clamping section defines a first inner angle, which is
greater than 180.degree., with a second tangent through at least
one support point on the release section; wherein: the inner ring
comprises the circular counter-race; the clamping element engages
the circular counter-race when the clamping element is positioned
within the clamping section; and the release section has a radius
greater than a radius of the at least one clamping element.
2. The freewheel as recited in claim 1, wherein the race has a
transition section at the transition between the clamping section
and the release section, wherein the transition section has a
continuous or discontinuous course.
3. The freewheel according to claim 2, wherein the transition
section has a course curved outward in a circular are in the radial
direction with respect to the first circumferential direction.
4. The freewheel according to claim 1, wherein the clamping section
is designed at least partially straight and/or has a course curved
inward in an arch in the radial direction with respect to the first
circumferential direction.
5. The freewheel according to claim 1, wherein the release section
is designed at least partially straight and/or has a course curved
inward in a spiral in the radial direction with respect to the
first circumferential direction.
6. The freewheel according to claim 1, wherein the first inner
angle is greater than 185.degree..
7. The freewheel according to claim 1, wherein the second tangent
defines a release angle on a circumference with a tangent through
an intersection, at which a radial extending to a center of the
clamping element crosses the circumference, said release angle
being greater than twice the clamping angle of the freewheel when
the clamping element is supported on the support point, through
which the second tangent-extends.
8. The freewheel according to claim 1, wherein the race
additionally has a retaining section following the release section
in the first circumferential direction, on which retaining section
the clamping element is supportable, wherein a third tangent
defines a second or a third inner angle, which is 180.degree. or
less, with the second tangent or with the first tangent.
9. The freewheel according to claim 1, wherein the clamping element
is designed as a clamping roller, wherein the ratio between a width
and an outer diameter of the clamping roller is equal to 1:5, and
the clamping roller is pretensioned in the clamping position by
means of a spring element which is supportable on the outer
ring.
10. A freewheel arrangement for a motor vehicle comprising a
freewheel according to claim 1, wherein an output side of a starter
motor is in permanent rotary driving connection with the inner
ring, whereas an output side of an internal combustion engine of
the motor vehicle is in or can be brought into rotary driving
connection with the outer ring.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of German Patent Application
No. 102015011415.8 filed Aug. 29, 2015, the disclosure of which is
herein incorporated by reference in its entirety.
FIELD OF THE DISCLOSURE
The invention relates to a freewheel with an outer ring, an inner
ring, and at least one clamping element which is between the outer
ring and the inner ring and can be moved from a clamping position
into a release position and vice versa along a race on the outer
ring in a first circumferential direction relative to the outer
ring. In addition, the present invention relates to a freewheel
arrangement for a motor vehicle comprising such a freewheel.
BACKGROUND OF THE DISCLOSURE
Freewheel arrangements for motor vehicles are known from practice,
and they function to couple the output side of a starter motor to
the output side of an internal combustion engine, thus, for
example, to a camshaft. The known freewheel arrangements have a
freewheel which essentially comprises an outer ring, an inner ring,
and multiple clamping elements between the outer ring and the inner
ring. The clamping elements may each be moved from a clamping
position into a release position and vice versa along a race on the
outer ring in a circumferentially direction relative to the outer
ring. Within the scope of this movement from the clamping position
into the release position and vice versa, the clamping element is
supportable on the race of the outer ring. The race thereby has,
relative to the first circumferential direction, in which the
clamping element is moveable from the clamping position into the
release position, in general, a course curved inward in an arc in
the radial direction; however, races are also known from practice
which have a straight course.
The known freewheels have proven themselves; however, it has been
demonstrated that the known freewheels within such a freewheel
arrangement, in particular during the starting process and/or in
the range of the idle speed, may lead to an increased noise
development and oscillations of the system.
It is therefore the object of the present invention to create a
freewheel in which the noise and oscillation development is
reduced, in particular the noise and oscillation development within
the context of a starting process and or in the range of the idle
speed. In addition, the underlying object of the present invention
is to create a freewheel arrangement with an advantageous freewheel
of this type.
The solution to this problem is carried out by the features listed
in Patent Claims 1 or 10. Advantageous embodiments of the invention
are the subject matter of the subclaims.
SUMMARY OF THE DISCLOSURE
The freewheel according to the invention has an outer ring, an
inner ring, and at least one clamping element between the outer
ring and the inner ring. Thus, a clearance formed in the radial
direction between the outer ring and the inner ring for
accommodating the clamping element may also be designated as a
clamping gap. The clamping element may be, for example, a clamping
roller, a clamping body, or the like. Even though a clamping
element or at least one clamping element is always discussed here,
it is preferred if multiple clamping elements are arranged between
the outer ring and the inner ring and are particularly preferably
spaced apart uniformly from one another in the circumferential
direction. The at least one clamping element may be moved from a
clamping position into a release position and vice versa along a
race on the outer ring in a first circumferential direction
relative to the outer ring. The race on the outer ring thereby has
a clamping section and a release section following the clamping
section in the first circumferential direction, wherein the
clamping element is supportable on the clamping section and on the
release section. It is hereby further preferred if a counter-race,
formed with an annular shape, is provided on the inner ring. A
first tangent through at least one support point, preferably
through all support points, on the clamping section, defines a
first inner angle, which is greater than 180.degree., with a second
tangent through at least one support point, preferably all support
points, on the release section. This angle is here designated as
the inner angle, particularly as this is enclosed between the sides
of the first and second tangents facing the clamping gap. A support
point is here, as well as subsequently, preferably a point on the
respective section at which the clamping element is actually
supportable.
It has been demonstrated that noise development may be reduced by
the cited inner angle, wherein the freewheel tends, in particular,
to lower oscillations. This is traced back to the fact that the
clamping element is more strongly prevented from reverting into the
clamping position after reaching the release section due to the
slope of the race in the release section, such that even during the
starting process or in the range of the idle speed, an undesired
striking of the clamping element on the counter-race of the inner
ring may be prevented. These brief strikes on the counter-race of
the inner ring appear to occur sometimes, in the case of
conventional freewheel arrangements inside of motor vehicles, and
to be responsible for noise development when the internal
combustion engine is in a compression stroke or in a combustion
stroke. In this respect, the release section, which is
correspondingly curved opposite to the clamping section, limits the
movement range of the clamping element, or shortens the same, in
order to prevent the noise and oscillation generating strikings of
the clamping element on the inner ring in this operating range of
the internal combustion engine, wherein this is traced back to the
increase of the radial force component acting outwardly on the
clamping element.
In a preferred embodiment of the freewheel according to the
invention, the race has a transition section at the transition
between the clamping section and the release section, wherein the
transition section may have a continuous or discontinuous course.
Even though one transition section is always discussed herein at
the transition between the clamping section and the release
section, it should be clarified that subsections of the transition
section may form a subsection of the clamping section and/or the
release section. A continuous course of the transition section is
hereby basically preferred; however, the transition section may
also have a discontinuous course in the simplest configuration
variants thereof, for example, a bent course, which would simplify
the manufacturing of the freewheel. The continuous course results,
in contrast, in a desired fluent movement of the clamping element
between the clamping section and the release section, wherein the
risk of damage to the transition section and/or the clamping
element is also reduced.
In a particularly preferred embodiment of the freewheel according
to the invention, the transition section has a course curved
outward in the radial direction in relation to the first
circumferential direction. In this embodiment, a transition section
arched inward in the radial direction may be discussed due to the
course curved outward in the radial direction in relation to the
first circumferential direction. In this embodiment, it is
furthermore preferred if the transition section has a course curved
outward in the radial direction in an arch, in a circular arc, or
in a spiral. Thus, in this embodiment variant, a transition section
curved inward in the radial direction in an arch, in a circular
arc, or in a spiral, may also be discussed. The course curved in
the circular arc or the spiral has hereby the advantage of the
previously discussed continuous course of the transition section,
which enables a fluent and/or uniform movement of the clamping
element between the clamping section and the release section, and
vice versa, and prevents damage to the freewheel.
In an advantageous embodiment of the freewheel according to the
invention, the clamping section is designed to be at least
partially straight.
Alternatively or supplementally to the previously described
embodiment, the clamping section has a course curved inward in the
radial direction in relation to the first circumferential direction
in another advantageous embodiment of the freewheel according to
the invention. It may thus also be stated in this embodiment that
the clamping section is formed curved outward in the radial
direction. It is also preferred in this embodiment if the clamping
section has a course curved inward in an arch, in a circular arc,
or in a spiral in the radial direction with respect to the first
circumferential direction. Thus, it may also be stated in this
embodiment variant, that the clamping section is curved outward in
the radial direction in an arch, in a circular arc, or in a spiral.
Against the background of reducing noise and oscillations, a course
curved inward in the radial direction with respect to the first
circumferential direction has proven advantageous, even though the
primary effect of the noise and oscillation reduction may be traced
back to the previously mentioned inner angle between the first
tangent of the clamping section and the second tangent of the
release section.
In another advantageous embodiment of the freewheel according to
the invention, the release section is designed to be at least
partially straight.
Alternatively or supplementally to the previously described
embodiment, the release section of the race on the outer ring has a
course curved inward in the radial direction in relation to the
first circumferential direction in another advantageous embodiment
of the freewheel according to the invention. It may thus also be
stated that the release section, which has a course curved inward
in the radial direction in relation to the first circumferential
direction, is curved outward in the radial direction. In this
embodiment, it is preferred in turn if the release section has a
course curved inward in an arch, in a circular arc, or in a spiral
in the radial direction with respect to the first circumferential
direction, wherein it may also be stated that the release section
is curved outward in the radial direction in an arch, in a circular
arc, or in a spiral, in this embodiment variant.
In another preferred embodiment of the freewheel according to the
invention, the first inner angle is greater than 185.degree.,
wherein it is furthermore preferred if the first inner angle is
190.degree. or more in order to particularly effectively inhibit
noise and oscillation development.
In order to particularly effectively suppress noises and
oscillations, the first inner angle in a particularly advantageous
embodiment of the freewheel according to the invention is
dimensioned in such a way that the second tangent defines a release
angle on a circumference with a tangent through an intersection
point at which a radial extending to a center point of the clamping
element crosses the circumference; the release angle is twice as
large as the clamping angle of the freewheel, when the clamping
element is supported on the support point through which the second
tangent extends. The clamping angle of the freewheel hereby
designates a predetermined size of the freewheel, which is
pre-specified by the dimensioning and shaping of the clamping
element, the outer ring, and the inner ring, when the clamping
element is located in the clamping position thereof. The center
point is preferably the center of gravity of the clamping element
and/or arranged on the center axis or axis of rotation of the
clamping element. In this embodiment, it has been demonstrated that
noises and oscillations may be particularly advantageously
suppressed when the cited release angle is at least 1.1 times the
clamping angle, preferably at least 1.5 times or 2 times the
clamping angle, particularly preferably at least 2.5 times the
clamping angle. However, in order to additionally safely achieve a
desired movement of the clamping element between the clamping
position and the release position, and vice versa, it is
additionally preferred in this embodiment, if the release angle is
not more than 3 times the clamping angle.
In another advantageous embodiment of the freewheel according to
the invention, the race on the outer ring additionally has a
retaining section, which follows the release section in the first
circumferential direction, and on which the clamping element is
supportable in order to safely retain or support the clamping
element on the race in the first circumferential direction, when
said clamping element has released from the counter-race on the
inner ring.
According to another advantageous embodiment of the freewheel
according to the invention, a third tangent through at least one
support point on the retaining section defines a second and/or
third inner angle with the second tangent and/or with the first
tangent, said second and/or third inner angle is 180.degree. or
less. A second and/or third inner angle has hereby proven to be
advantageous which is 135.degree., preferably 100.degree. or less,
in order to guarantee a safe support and/or retaining of the
clamping element on the retaining section.
In another preferred embodiment of the freewheel according to the
invention, the clamping element is designed as a clamping roller.
Clamping rollers are understood in this context to be clamping
elements with a circular circumference or a circular outer contour,
which are additionally preferably designed as cylinders.
In another advantageous embodiment of the freewheel according to
the invention, the ratio between a width and an outer diameter of
the clamping roller is equal to or less than 1:3, preferably equal
to or less than 1:4, particularly preferably equal to or less than
1:5. Due to the width being particularly small relative to the
axial extension and the relatively large outer diameter of the
clamping roller, said clamping roller is particularly suited for
use in connection with the race designed according to the invention
with clamping sections and release sections.
In another advantageous embodiment of the freewheel according to
the invention, the clamping roller is pretensioned in the clamping
position by means of a spring element which is particularly
preferably supported or is supportable on the outer ring. In this
embodiment, it is further preferred if each individual clamping
roller is pretensioned in the clamping position by means of a
separate spring element. Basically any spring element is possible
for use as the spring element, for example, a helical spring;
however, an accordion spring, particularly with a wave-like course
in the radial direction, and/or a sheet metal spring has proven
advantageous.
The freewheel arrangement according to the invention is conceived
of for a motor vehicle and has a freewheel of the previously
described type according to the invention. In the freewheel
arrangement, an output side of a starter motor, thus for example
the starter pinion of a starter motor, is in permanent rotary
driving connection with the inner ring of the freewheel, whereas an
output side of an internal combustion engine of the motor vehicle
is in rotary driving connection, or can be brought into rotary
driving connection, with the outer ring of the freewheel. The outer
ring is hereby preferably connected or connectable rotationally
fixed to the output side of the internal combustion engine.
BRIEF DESCRIPTION OF THE DRAWING
The invention will be subsequently described in greater detail by
means of exemplary embodiments with reference to the attached
figures.
FIG. 1 shows a partial side view of a freewheel arrangement inside
of a motor vehicle in a cutaway view;
FIG. 2 shows a view along line A-A in FIG. 1 with the freewheel in
a first embodiment and the clamping element in the clamping
position;
FIG. 3 shows the freewheel from FIG. 2 with the clamping element in
a first release position;
FIG. 4 shows the freewheel from FIG. 3 with the clamping element in
a second release position;
FIG. 5 shows the freewheel from FIG. 4 with the clamping element in
a third release position;
FIG. 6 shows a view along line A-A of FIG. 1 in a second embodiment
variant of the freewheel;
FIG. 7 shows a view along line A-A of FIG. 1 in a third embodiment
of the freewheel; and
FIG. 8 shows a view along line A-A of FIG. 1 in a fourth embodiment
of the freewheel.
DETAILED DESCRIPTION OF THE DISCLOSURE
FIG. 1 shows a freewheel arrangement 2 inside of a motor vehicle.
Freewheel arrangement 2 essentially has a freewheel 4, a starter 6,
and an internal combustion engine 8. Starter 6 has a starter motor
10 with an output side 12 which is essentially formed by a starter
pinion 14 drivable by starter motor 10. Of internal combustion
engine 8, an output side 16 is represented in the form of a
driveshaft or crankshaft 18 which is connected rotationally fixed
to a flywheel 20 in the embodiment shown. In FIG. 1, the opposing
axial directions 22, 24, the opposing radial directions 26, 28, and
the opposing circumferential directions 30, 32 of freewheel
arrangement 2 and of freewheel 4 are indicated by means of
corresponding arrows, wherein circumferential direction 30 is
subsequently designated as first circumferential direction 30 and
circumferential direction 32 is subsequently designated as second
circumferential direction 32. The axis of rotation 34 of output
side 16 and of freewheel 4 extends in axial directions 22, 24.
First and second circumferential directions 30, 32 may also be
designated as first and second directions of rotation.
Output side 12 in the form of starter pinion 14 is arranged in
radial direction 26 outside of freewheel 4 such that an output side
12 of starter 6 lying radially exterior may be stated with respect
to freewheel 4. Output side 12 of starter motor 10 is permanently
in rotary driving connection with a starter gear 36, wherein
starter gear 36 has a rotary driving contour 38 for this purpose
which is permanently in rotary driving connection with starter
pinion 14. Starter gear 36 is connected rotationally fixed to an
inner ring 42 of freewheel 4 via a starter wheel 40 which extends,
starting from starter gear 36, inward in radial direction 28. An
outer ring 44 of freewheel 4 surrounding inner ring 42 of freewheel
4 outwardly in radial direction 26 is, in contrast, connected
rotationally fixed to output side 16 of internal combustion engine
8, wherein outer ring 44 in the embodiment shown is connected
rotationally fixed to driveshaft 18 forming output side 16 of
internal combustion engine 8 via flywheel 20.
Inner ring 42 is supported directly or indirectly in radial
directions 26, 28 on output side 16, in this case, on driveshaft
18, to be rotatable in circumferential direction 30, 32.
Alternatively, inner ring 42 may also be supported directly or
indirectly in radial directions 26, 28 to be rotatable on a
stationary housing, for example, on the housing 46 of internal
combustion engine 8 indicated in FIG. 1. In order to affect the
rotatable support, this is carried out preferably via a radial
bearing, particularly preferably via a rolling bearing or plain
bearing 48, as this is indicated in FIG. 1. In the embodiment
shown, freewheel 4 is designed as a dry-running freewheel.
Alternatively, however, freewheel 4 may also be designed as a
wet-running freewheel, the supply of coolant and/or lubricant in
this case is preferably carried out via the coolant and/or
lubricant supply of the internal combustion engine 8.
Inner ring 42 and outer ring 44 are arranged nested in radial
directions 26, 28 such that a circumferential clamping gap 50 is
formed between the same in circumferential directions 30, 32.
Multiple clamping elements 52 are arranged within clamping gap 50
spaced uniformly apart from one another in circumferential
directions 30, 32, wherein clamping elements 52 are designed as
clamping rollers in the embodiment shown which therefore have a
circular circumference or a circular outer contour 54. Outer ring
44 has a race 56 facing inward in radial direction 28 toward
clamping elements 52, wherein a race 56 of this type, which has a
course deviating from a pure circular arc, is respectively assigned
to each of clamping elements 52. Inner ring 42 has, in contrast, a
counter-race 58 facing toward clamping elements 52 and outward in
radial direction 26. Counter-race 58 designed circumferentially in
circumferential directions 30, 32 is designed with a circular
shape. Due to race 56 deviating from a circular path on the one
side and the circular shape of counter-race 58 on the other side, a
clamping gap 50 is created which tapers in second circumferential
direction 32 in the region of respective clamping element 52, which
will be introduced again in more detail with reference to FIGS. 2
to 8.
Clamping elements 52 designed as clamping rollers have a width b
and an outer diameter a with respect to axial directions 22, 24.
The ratio between width b and outer diameter a of the respective
clamping elements 52 designed as clamping rollers is equal to or
less than 1:3, preferably equal to or less than 1:4, particularly
preferably equal to or less than 1:5. In other words, coin shaped
clamping elements 52 or clamping rollers may also be discussed
which enable a particularly short axial structure of freewheel 4.
Clamping gap 50 is delimited in axial direction 22 by a first side
wall 60 and in axial direction 24 by a second side wall 62, wherein
first side wall 60 is formed in the embodiment shown by a section
of flywheel 20, whereas second side wall 62 is formed separately
from flywheel 20 and as an annular disk. First side wall 60 and
second side wall 62 are fixed rotationally fixed to outer ring 44
of freewheel 4, which may be carried out, by way of example, by
means of the screw connection (no reference numeral) shown in FIG.
1.
The further structure of freewheel arrangement 2 and freewheel 4 in
FIG. 1 will be subsequently described with reference to FIGS. 1 to
5, wherein FIGS. 2 to 5 show a first embodiment of freewheel 4.
Each clamping element 52 may be moved along race 56 on outer ring
44 in first circumferential direction 30 relative to outer ring 44
from a clamping position, which is shown in FIG. 2, into a release
position, which is shown in FIGS. 3 to 5. Clamping element 52 is
thereby moved from the clamping position into the release position
counter to the reset force of a spring element 64, which is
supported or is supportable on the one side in first
circumferential direction 30 on outer ring 44 and on the other side
in second circumferential direction 32 on clamping element 52. In
other words, clamping element 52 designed as a clamping roller is
pretensioned by spring element 64 in the clamping position shown in
FIG. 2.
In the clamping position shown in FIG. 2, outer contour 54 of
clamping element 52 is supported both on race 56 and on
counter-race 58, wherein a rotation of outer ring 44 in first
circumferential direction 30 relative to inner ring 42 is
prevented. In the clamping position, outer ring 44 and thus also
output side 16 of internal combustion engine 8 in the form of
driveshaft 18 may be driven with the aid of flywheel 20 by starter
6, which rotates inner ring 42 of freewheel 4 in second
circumferential direction 32 by means of starter gear 36 and
starter wheel 40. If internal combustion engine 8 starts as a
result of this starting process, such that outer ring 44 driven by
output side 16 of internal combustion engine 8 overtakes inner ring
42 of freewheel 4 in second circumferential direction 32, then
clamping element 52 moves along race 56 as a result of centrifugal
and inertial forces into the release position shown in FIGS. 3 to
5. Therefore, freewheel 4 in the basic structure is a so-called
one-way coupling.
Race 56 on outer ring 44 has essentially a clamping section 66, a
transition section 68 following clamping section 66 in first
circumferential direction 30, a release section 70 following
transition section 68 in first circumferential direction 30, and a
retaining section 72 following release section 70 in first
circumferential direction, wherein transition section 68 is
provided at the transition between clamping section 66 and release
section 70. Transition section 68 may thereby be assigned partially
or completely to clamping section 66 and/or partially or completely
to release section 70. Clamping element 52 is supportable via its
outer contour 54 at support points on clamping section 66,
transition section 68, release section 70, and retaining section 72
respectively. Support points are thereby preferably understood as
those points on the respective section, at which the clamping
element is actually supportable for structural reasons.
In the first embodiment according to FIGS. 2 to 5, clamping section
66 is designed to be at least partially or completely straight.
Alternatively or supplementally, however, clamping section 66 may
also have a curved course, as is indicated in FIG. 7. Thus,
clamping section 66 in the embodiment according to FIG. 7 has a
course curved inward in radial direction 28 in an arch, in a
circular arc, or in a spiral with respect to first circumferential
direction 30. It may also be stated here that clamping section is
designed, according to the embodiment according to FIG. 7, curved
outward in radial direction 26, preferably in an arch, in a
circular arc, or in a spiral.
Transition section 68 may basically have a continuous course, as
this is shown in the embodiments according to FIGS. 2 to 5, 7 and
8, or a discontinuous course, as this is indicated in FIG. 6 in the
context of a second embodiment of freewheel 4. In this second
embodiment, transition section 68 analogously has a bent course.
Regardless of whether transition section 68 has a continuous or
discontinuous course, transition sections 68 in all of the
embodiments shown according to FIGS. 2 to 8 have a course curved
outward in radial direction 26 relative to first circumferential
direction 30, wherein it may also be stated that transition section
68--continuous or discontinuous--is curved inward in radial
direction 28. It is hereby preferred if transition section 68, as
is shown in FIGS. 2 to 5 and 7 to 8, has a course curved outward in
radial direction 26 in an arch, in a circular arc, or in a spiral,
wherein it may also be stated that transition section 68 is curved
inward in radial direction 28 in an arch, in a circular arc, or in
a spiral in these embodiments.
Release section 70 may be designed to be at least partially or
completely straight. Alternatively or supplementally, however,
release section 70 may also have a course curved inward in radial
direction 28, preferably in an arch, in a circular arc, or in a
spiral with respect to first circumferential direction 30. In other
words, release section 70 may be designed curved outward in radial
direction 26, preferably in an arch, in a circular arc, or in a
spiral. In the embodiments shown, release section 70 has a first
subsection 74 and a second subsection 76 following first subsection
74 in first circumferential direction 30, wherein first subsection
74 is designed to be straight, whereas second subsection 76 has a
course curved inward in radial direction 28, preferably in an arch,
in a circular arc, or in a spiral with respect to first
circumferential direction 30.
Retaining section 72 following release section 70 has, in turn a
course curved inward in radial direction 28, preferably in an arch,
in a circular arc, or in a spiral with respect to first
circumferential direction 30, wherein it may be stated in turn that
retaining section 72 has a course a course curved outward in radial
direction 26, preferably in an arch, in a circular arc, or in a
spiral. In the embodiments shown according to FIGS. 2 to 8, both
second subsection 76 of release section 70 and retaining section 72
are curved in a circular arc, wherein this has a circular arc
radius r.sub.1 or r.sub.2. Circular arc radius r.sub.1 preferably
corresponds to circular arc radius r.sub.2. Alternatively, however,
circular arc radius r.sub.2 may be designed to be greater than
circular arc radius r.sub.1. It is also preferred if circular arc
radius r.sub.2 of the circular arc formed by retaining section 72,
regardless of whether this corresponds to circular arc radius
r.sub.1 of second subsection 76 or whether second subsection 76 is
even designed as a circular arc, is greater than the radius of
clamping element 52 designed as a clamping roller, such that
preferably a/2<r.sub.2 applies. It should also be noted at this
point that release section 70 may be formed completely from
straight first subsection 74 or from curved second subsection 76,
even though the division into first and second subsections 74, 76
shown in FIGS. 2 to 8 is preferred.
In order to effectively suppress noise development during the
starting process and/or in the range or the idle speed, a first
tangent 78 through at least one support point 80 on clamping
section 66 of race 56 defines a first inner angle .alpha. 1, which
is greater than 180.degree., with a second tangent 82 through at
least one support point 84 on release section 70. It has hereby
proven advantageous, if the cited first inner angle .alpha. 1 is
greater than 185.degree., particularly preferably 190.degree. or
more. It is also preferred if the cited first inner angle .alpha. 1
exists proportionally between all possible support points of
clamping element 52 on clamping section 66 and all possible support
points on release section 70.
In addition, retaining section 72 is designed in such a way that a
third tangent 86 through at least one support point 88 on retaining
section 72 defines a second inner angle .alpha.2 and/or a third
inner angle .alpha.3, which is 180.degree. or less, with second
tangent 82 and/or with first tangent 78.
On the basis of the preceding description, it is apparent that race
56 has a course, on the basis of correspondingly formed first inner
angle .alpha.1, which deviates from the conventional course 90,
indicated in the figures with dashed lines, in order to effectively
suppress noise development during the starting process and/or in
the range of idle speed, wherein, in contrast to conventional
course 90, a depression 92 is analogously created in the region of
release section 70 and retaining section 72. The functionality of
freewheel arrangement 2 and freewheel 4 shall be subsequently
introduced in greater detail with reference to FIGS. 2 to 5.
In FIG. 2, clamping element 52 is in the clamping position thereof.
In the clamping position of clamping element 52, outer contour 52
[sic: should read 54] thereof is supported both in radial direction
26 outward on clamping section 66 and in radial direction 28 inward
on counter-race 58, wherein clamping element is retained in the
clamping position via spring element 64. For structural reasons,
freewheel 4 has a predetermined clamping angle .alpha., which is
indicated twice in FIG. 2. During the starting process, inner ring
42 is initially driven in second circumferential direction 32 via
starter 6, wherein, due to the clamping position of clamping
element 52, a rotary driving connection exists between inner ring
42 and outer ring 44 by means of clamping element 52. Therefore,
outer ring 44 and, via outer ring 44, flywheel 20 and output side
16 of internal combustion engine 8, and internal combustion engine
8 or driveshaft 18 thereof, are also driven.
In the combustion cycles of internal combustion engine 8, outer
ring 44 is additionally driven--somewhat intermittently--in second
circumferential direction 32, such that clamping element 52 moves
along race 56, more exactly stated, along clamping section 66,
transition section 68 (FIG. 3), release section 70 (FIG. 4), and
retaining section 72 (FIG. 5), wherein this occurs as a result of
centrifugal and inertial forces counter to the reset force of
spring element 64.
In the compression cycles of internal combustion engine 8, however,
the speed of outer ring 44 rotating in second circumferential
direction 32 is reduced such that clamping element 52 is moved back
in second circumferential direction 32 relative to outer ring 44
due to the reset force of spring element 64 and due to the decrease
in the centrifugal force affecting clamping element 52. However, in
the course of this movement of clamping element 52 in second
circumferential direction 32 relative to outer ring 44, clamping
element 52 supports itself on release section 70 of race 56, as
this is shown in FIG. 4, wherein the previously mentioned first
inner angle .alpha.1, which is designed to be greater than
180.degree., prevents a further movement of clamping element 52 in
second circumferential direction 32 relative to outer ring 44, such
that it may be avoided that clamping element 52 is moved further
along race 56 in second circumferential direction 32 relative to
outer ring 44 and ultimately strikes counter-race 58 of inner ring
42 inward in radial direction 28. Thus, both noise development and
also oscillation development may be prevented by this means.
In this context, it has proven particularly advantageous if
previously mentioned second tangent 82 (see also FIG. 4) through
support point 84 defines a release angle .beta. on a circumference
with a tangent 94 through an intersection point 96, at which a
radial 100 extending to a center point 98 of clamping element 98
intersects the circumference--here the circular counter-race 58--,
which angle .beta. is greater than twice clamping angle .alpha. of
freewheel 4 when clamping element 52 is supported on support point
84, through which second tangent 82 extends. It has additionally
proven hereby advantageous, if release angle .beta. is at least 1.1
times or 1.5 times clamping angle .alpha., particularly preferably
at least 2 times or 2.5 times clamping angle .alpha.. As an upper
limit for release angle .beta., however, it has proven advantageous
if release angle .beta. is not more than 3 times clamping angle
.alpha..
The preceding description of the first embodiment according to
FIGS. 1 to 5 applies analogously to the additional embodiments
according to FIGS. 6, 7, and 8, such that reference is made with
respect to the preceding description. Whereas reference has already
been made to the second embodiment according to FIG. 6 and to the
third embodiment according to FIG. 7, fourth embodiment according
to FIG. 8 shall subsequently be supplementally introduced. In
contrast to the preceding embodiments, retaining section 72 in the
fourth embodiment according to FIG. 8 is designed to be essentially
straight. Thus, retaining section 72 has two straight subsections,
connected to each other, however, at a bend. In general, the
preceding description of embodiments 1 to 3 applies
accordingly.
* * * * *