1
1
FIELD OF THE DISCLOSURE --
The present disclosure generally relates to clutch assemblies used for transmitting
torque from a prime mover to a driven member. More particularly, the present
disclosure relates to a one-way clutch assembly.
BACKGROUND
A transmission assembly includes a clutch assembly for transmission of torque from a
driving shaft coupled with a prime mover to a driven member. The driven member
@ further transmits torque to a drive wheel or any other rotatable member. Generally, a
one-way clutch assembly is used to transmit the torque in one direction while
restricting transmition of the torque in a reverse direction. Thus, as the driving shaft
rotates in one direction, the one-way clutch transmits torque from the driving shaft to
the driven member. On the other hand, as the driving shaft rotates in an opposite
direction, freewheeling of the driving shaft takes place and the torque is not
transmitted to the driven member.
A conventional one-way clutch assembly includes an inner member and an outer
member having complicated profiles and a set of rolling elements/cams and springs
located therein. Typically, the inner member is mounted on the driving shaft and the
outer member cooperates with the driven member. Engagement between the inner
member and the outer member is achieved with the help of the rolling elements 1
cams, plurality of springs and plurality of complicated profiles in the outer member,
such that, torque is transmitted from the driving shaft to the driven member. However,
conventional one-way clutch assembly having complicated multiple profiles along
with the additional components for achieving engagement between the inner member
and the outer member are plagued with several drawbacks. One of the drawbacks of
the conventional one-way clutch assembly is that it is complex in the structure and
hence is difficult to assemble during manufacturing. Further, the conventional oneway
clutch assemblies are less reliable, susceptible to frequent breakdowns and
require regular maintenance. Furthermore, the conventional one-way clutch
assemblies fail to achieve complete disengagement during free-wheeling.
Additionally, the conventional one-way clutch assemblies fail to effectively transmit
torque and lead to higher power consumption. Further, the conventional one-way
clutch assembly is expensive and has reduced service life.
Hence there is felt a need for a one-way clutch assembly that alleviates the drawbacks
associated with conventional one-way clutch assemblies.
OBJECTS OF THE DISCLOSURE
0
Some of the objects of the present disclosure which at least one embodiment is able to
satisfy are described herein below:
It is an object of the present disclosure to ameliorate one or more problems of the prior
art or to at least provide a useful alternative.
An object of the present disclosure is to provide a one-way clutch assembly that is
simple in construction.
e
Another object of the present disclosure is to provide a one-way clutch assembly that
requires reduced number of parts.
Still another object of the present disclosure is to provide a one-way clutch assembly
that is reliable.
Yet another object of the present disclosure is to provide a one-way clutch assembly
that eliminates the need for complicated multiple profiles.
I
Another object of the present
achieves complete disengagement during freewheeling.
Still another object of the present disclosure is to provide a one-way clutch assembly
that can effectively transmit torque.
Another object of the present disclosure is to provide a one-way clutch assembly that
consumes less power.
Still another object of the present disclosure is to provide a one-way clutch assembly
@ that exhibits enhanced service life.
Another object of the present disclosure is to provide a one-way clutch assembly that
is cost effective.
SUMMARY
A one-way clutch assembly for selectively transmitting torque from a prime mover to
a driven member is disclosed. The assembly includes:
a driven element torque-transmittingly cooperating with the driven member;
a threaded shaft adapted to receive torque form the prime mover; and
a driving element threadably displaceable on the threaded shaft in an axial
direction to be selectively in an engaged configuration and a disengaged
configuration with the driven element,
wherein the driving element is adapted to transmit torque from the threaded
shaft to the driven element in the engaged configuration.
In accordance with an embodiment of the present disclosure, the one-way clutch
assembly may further optionally includes at least one positional spring(s) adapted to
rotationally constrain the driving element to be displaced in the axial direction to
enable the engaged configuration.
The engaged configuration is achieved by virtue of difference in inertia of the
threaded shaft and the driving element and the disengaged configuration is achieved
by a resultant force resulting due to relative motion of the driving element and the
driven element.
Typically, the threaded shaft is provided with threads along at least a portion thereof,
the threads being at least internal threads and external threads.
The driving element has matching threads complementary to the threads of the
threaded shaft and has a shape selected from the group consisting of a frustum shape
@ and an annular disc shape.
Typically, the driven element has a shape selected from the group consisting of a cup
shaped and disc shaped.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The assembly of the present disclosure will now be explained in relation to the
accompanying drawings, in which:
Figure la illustrates an assembled view of a one-way clutch assembly in accordance
with an embodiment of the present disclosure;
Figure l b illustrates an exploded view of the one-way clutch assembly of the Figure
la;
Figure 2a illustrates the assembled view of a one-way clutch assembly having a
driving element in the shape of an annular disk and a driven element in the shape of a
disc, in accordance with an alternative embodiment of the present disclosure;
Figure 2b illustrates the exploded view of the one-way clutch assembly of Figure 2a;
5
L'RIGINWL
4
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Figure 3a illustrates the assembled view of a one-way clutch assembly in accordance
with an embodiment of the present disclosure;
Figure 3b illustrates the exploded view of the one- way clutch assembly of Figure
3a;
Figure 4a illustrates the assembled view of a one-way clutch assembly having a
driving element in the shape of an annular disk and a driven element in the shape of a
disc, in accordance with another embodiment of the present disclosure;
@ Figure 4b illustrates the exploded view of the one-way clutch assembly of Figure 4a;
and
Figure 5a to Figure 5c illustrates alternative placement and configuration of a spring
in the one-way clutch assembly in accordance with the present disclosure.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The disclosure will now be described with reference to the accompanying drawings
which do not limit the scope and ambit of the disclosure. The description provided is
purely by way of example and illustration.
The embodiments herein and the various features and advantageous details thereof are
explained with reference to the non-limiting embodiments in the following
description. Descriptions of well-known components and processing techniques are
omitted so as to not unnecessarily obscure the embodiments herein. The examples
used herein are intended merely to facilitate an understanding of ways in which the
embodiments herein may be practiced and to further enable those of skill in the art to
practice the embodiments herein. Accordingly, the examples should not be construed
as limiting the scope of the embodiments herein.
Figure la illustrates an assembled view of a one-way clutch assembly 100 in
accordance with an embodiment of the present disclosure. Figure lb illustrates an
exploded view of the one-way clutch assembly 100. The one way-clutch assembly 100
includes a threaded shaft 10, at least one optional positional spring(s) 20, a driving
element 30, and a driven element 40. The one-way clutch assembly 100, illustrated in
Figure la, is a cone clutch assembly, wherein the driving element 30 is in the shape
of a frustum of a cone and the driven element 40 is cup shaped. The driving element
30 has internal threads configured within an axial opening defined on the driving
element 30. The threaded shaft 10 is driven by a prime mover that includes but is not
limited to an engine or a motor. The threaded shaft 10 has external threads configured
@ thereon. The internal threads and the external threads of the driving element 30 and
the threaded shaft 10 respectively are complementary to each other. The driving
element 30 is threadably displaceable in an axial direction on the threaded shaft 10 by
the cooperation between the internal threads and the external threads of the driving
element 30 and the threaded shaft 10 respectively. When the threaded shaft 10 is
provided with torque, the driving element 30 is momentary stationary on account of
inertia of rest. On account of the inertia of rest of the driving element 30 with respect
to the rotational motion provided to the threaded shaft 10 by the torque from the
prime-mover, the driving element 30 is subjected to an axial thrust. The axial thrust
along with cooperation between the internal threads and the external threads of the
driving element 30 and the threaded shaft 10 respectively, causes the driving element
30 to move towards the driven element 40. This enables achieving engaged
configuration between the driving element 30 and the driven element 40.
The positional spring 20 is optionally provided for rotationally constraining the
driving element 30 from rotating along with the threaded shaft 10. The positional
spring 20 is positioned between the driving element 30 and an axial constraint (not
shown in Figure), typically a square plate provided for supporting the threaded shaft
10. Prior to the initiation of axial displacement of the driving element 30 to the
engaged configuration, the positional spring 20 is in compressed state. Thus, the
positional spring 20 provides a rotational constraint on the driving element 30 to
ORIGINAL ,
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restrict its rotation along with the threaded shaft 10
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untilCfhe driving element 30 is in
the engaged configuration to enable transmitting of a predetermined torque to the
driven element 40.
In the engaged configuration, the one way clutch assembly 100 transmits torque from
the threaded shaft 10 to the driven element 40 via the driving element 30. In the
engaged configuration, negative clearance exists between the driven element 40 and
the driving element 30. In the engaged configuration, the driving element 30 rotates at
the rotational speed equal to the rotational speed of the threaded shaft 10, thus
transmitting the predetermined torque to the driven element 40.
In the event when the transmission of torque to the driven element 40 is required to be
terminated, the rotation of the threaded shaft 100 is stopped while the driven element
40 continues to rotate at a speed corresponding to the predetermined torque. When the
rotation of the threaded shaft is stopped, the speed of rotation of the driving element
30 with respect to the driven element 40 decreases since it is threadably coupled to the
threaded shaft 10. The relative difference in the speed of rotation of the driving
element 30 and the driven element 40 generates a resultant thrust which causes the
driving element 30 to be axially displaced away from the driven element 40. This
enables achieving disengaged configuration between the driving element 30 and the
1 driven element 40, thereby preventing transmission of torque from the driving element
30 to the driven element 40.
Thus, disengagement configuration is achieved by the resultant thrust transmitted to
the driving element 30. The resultant thrust combined with the co-operation between
the internal threads and the external threads of the driving element 30 and the threaded
shaft 10 respectively, causes the driving element 30 to be displaced away from the
driven element 40. This enables creation of a positive clearance between the driving
element 30 and the driven element 40. When the driving element 30 is displaced
away from the driven element 40 in the disengaged configuration, the driving element
30 provides a compressive force on the positional spring 20. Due to the positive
ORIGINAL
-, 6 2
clearance attained in the disengaged configuration, freewheeling of the threaded shaft
10 occurs.
In accordance with an embodiment of the present disclosure, the engaged
configuration of the driving element 30 and the driven element 40 is independent of
the positional spring 20 and operates by virtue of difference in inertia between the
threaded shaft 10 and the driving element 30.
In accordance with another embodiment of the present disclosure, the one-way clutch
assembly 200 is a disc or plate clutch assembly. As illustrated in Figure 2a and
@ Figure 2b, a one-way clutch assembly 200 comprises a driving element 210 which is
in the shape of an annular disc and a driven element 220 which is in the shape of a
disc. The driving element 210 is threadably displaceable on a threaded shaft 240 and
is coupled to a positional spring 230.
Figure 3a illustrates an assembled view of a one-way clutch assembly 300 in
accordance with another embodiment of the present disclosure. Figure 3b illustrates
an exploded view of the one-way clutch assembly 300. A threaded shaft 310 defines a
hollow. The threaded shaft 310 receives torque from the prime mover. The threaded
shaft 310 has internal threads configured thereon. A driving element 340 is threadably
0 displaceable inside the threaded shaft 310 to enable an engaged configuration and a
disengaged configuration with a driven element 330 respectively. A positional spring
320 is provided to exert a rotational constraint to the driving element 340 from
rotating with the rotation of the threaded shaft 10, thereby ensuring axial displacement
of the driving element 340 on the internal threads of the threaded shaft 310. The
driving element 340 is threadably displaced towards the driven element 330 so as to
cooperate with the driven element 330 in the engaged configuration. As soon as the
engagement configuration is achieved between the driving element 340 and the driven
element 330, the driving element 340 starts rotating at a rotational speed equal to the
rotational speed of the threaded shaft 310, thereby transmitting torque to the driven
element 330. In the event when the transmission of torque to the driven element 330 is
required to be terminated, the rotation of the threaded shaft 310 is stopped while the
driven element 330 continues to rotate at a speed corresponding to the predetermined
torque. When the rotation of the threaded shaft 310 is stopped, the speed of rotation of
the driving element 340 decreases since it is threadably coupled to the threaded shaft
310. The relative difference in the speed of rotation of the driving element 340 and the
driven element 330 generates a resultant force which causes the driving element 340
to be axially displaced away from the driven element 330. The resultant force enables
in achieving the disengaged configuration between the driving element 340 and the
driven element 330.
@ In accordance with another embodiment of the present disclosure, the one-way clutch
assembly 400 is a disc or plate clutch assembly. As illustrated in Figure 4a and 4b, a
one-way clutch assembly 400 comprises a driving element 410 which is in the shape
of an annular disc and a driven element 420 which is in the shape of a disc. The
driving element 410 is threadably displaceable on a threaded shaft 440 and is coupled
to a positional spring 430.
In accordance with an embodiment of the present disclosure, the positional spring 20
is a helical spring, a belleville spring and a disc type spring. However, the positional
spring 20 is not limited to the aforementioned springs and any kind of a compression
@ spring may be used. Further, the placement and configuration of the positional spring
20 may vary as illustrated in Figures 5a - Figure 5c. The positional spring 20 may
be placed at the larger diameter side of the driving element 30 as illustrated in Figure
5a, at the smaller diameter side of the driving element 30 as illustrated in Figure 5b or
at both sides of the driving element 30 as illustrated in Figure 5c.
In determining torque transmission by the one way clutch assembly illustrated in
Figure la, the equations for force, energy and torque requirements with regard to a
particular driving element 30 and a driven element 40 are required to be obtained.
Initially, there is no constraint on the rotational motion of the driving element 30 with
the threaded shaft 10. The driving element 30 tends to rotate with the threaded shaft
tLB- Y.\ .LG INAL
- 1 6 DEC 20C)
10 at the same speed as that 6f the threaded shaft 10. Therefore, energy (E,,,) of the
driving element 30 when the threaded shaft 10 starts rotating is determined by the
following equation:
As it is known in the art, wherein CG,,,, is determined by:
Assuming that pitch radius of the thread of the threaded shaft 10 (rp, = 0.01 16 and
mean radius at the outer (r,,) = 0.02665. The values of rp and r,, are obtained from the
C design and are not limited to aforementioned values. The values may vary in
accordance with the design for a particular application of the one-way clutch assembly
of the present disclosure.
Based on equation 1 and equation 2
EcQng= 0.0494Nn1.. ............( 4)
C Therefore, based on the aforementioned equations, energy of the cone is 0.494 N-m.
In order to provide constraint on rotational motion of the driving element 30 with the
threaded shaft 10, work is done by the positional spring 20, which is determined as
indicated in the following equation:
p * [K * (Ax)] * CCCone = a1 * E,, ,,,, --------------- (5), wherein
a1 is a factor of safety and is assumed to be 2; K is a positional spring constant and Ax
is the displacement of positional spring 20. The factor of safety a1 is indicative of the
minimum energy required for the positional spring 20 in order to provide the
rotational constraint to the driving element 30 effectively. Therefore, factor of safety
alrepresents the positional spring 20 force to overcome the energy available at the
driving element 30.
I
a 2 1 6 DEC a013 Based on equation 3 and equation 4, work done WSpi,, by the spring is determine as
indicated in equation 5 mentioned herein below.
W, = 0.0988Nm ........................ (6)
The one end of the positional spring 20 is attached to the driving element 30 and the
other end of the positional spring 20 is abutting a fixed surface having a friction coefficient
(p) as 0.10. Therefore,
0.0988
K * (Ax) = = 51.4M
0.1 * 0.0192 .............. (7)
C The threadably engaged driving element 30 and the threaded shaft 10 define a power
screw that is utilized to convert a rotary motion to a linear motion for power
transmission. More specifically, an axial force is applied on the driving element 30 by
the threaded shaft 10 which is determined by the equation 7, mentioned herein below.
Wherein Tmise is the torque required to raise a load (F) by the power screw and is
given by the below mentioned equation 9.
C wherein, assuming p = 0.1 and dm = 0.022 is obtained from the design calculation.
Generally, during torque transmission as soon as the threaded shaft 10, the driving
element 30 and the driven element 40 are in engaged configuration, then work is done
against the load of engine components to reach a required revolutions per minute
(RPM) in order to crank the engine. Hence, the threaded shaft 10 acts as a power
screw in order to bear load of engine components to crank the engine.
Therefore, based on equation 7 and equation 8, the force applied on the driving
element 30 is determined as follows:
F = 3.72 kN . .
The axial force
..........
applied
... (11)
on the driving element
a 4
enables
- - , ~ . ; ? T { ~ ~ p i f i f
-c.*a L3q,~:i -%L
the engagement of the
driving element 30 with the driven element 40 due to which torque is transmitted by
the driving element 30 to the driven element 40. The maximum torque transmissible
by the driving element 30 to the driven element 40 is determined in accordance with a
uniform pressure theory as described in the equations mentioned herein below:
2pF(r: - $1
T =
3 sin a (r,Z - t;Z).. ............... (12 )
In operative condition, torque is transmitted from a prime mover to the driving
element 30 which transmits the torque further to the driven element 40 due to
interference therebetween. In the operative condition, energy of the driving element
30 is:
1
Econe) R = 5 mco ne * (atone ,n 1' * CCGconeI2
Wherein, m,,,, = 0.112, ~,,,,= 157 and CG,,,, = 0.0 192Hence,
@ Econe, R = 0.5088 Nm
Therefore,
Econa,s W+inr < Ec0w.1~
Since.
0.494Nm < 0.0988Nm < 0.5088 Nm
Thus, the one way clutch assembly of the present disclosure utilises the principle of
inertia and resultant force arising out of relative motion to achieve the engaged
configuration and the disengaged configuration between the driving element and the
driven element. The one way clutch assembly of the present disclosure is simple in
construction and efficient in operation.
1
TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE
The present disclosure has several technical advantages including but not limited to
the realization of:
a one-way clutch assembly that is simple in construction;
a one-way clutch assembly that requires lesser number of parts;
a one-way clutch assembly that is reliable;
a one-way clutch assembly that eliminates the need for complicated multiple
profiles as required in conventional clutches and is simple to manufacture;
a one-way clutch assembly that achieves complete disengagement during freewheeling;
a one-way clutch assembly that can effectively transmit more torque;
a one-way clutch assembly that consumes less power;
a one-way clutch assembly that exhibits enhanced service life; and
a one-way clutch assembly that is inexpensive.
The numerical values given of various physical parameters, dimensions and quantities
are only approximate values and it is envisaged that the values higher or lower than
the numerical value assigned to the physical parameters, dimensions and quantities
C fall within the scope of the disclosure and the claims unless there is a statement in the
specification to the contrary.
Throughout this specification the word "comprise", or variations such as "comprises"
or "comprising", will be understood to imply the inclusion of a stated element, integer
or step, or group of elements, integers or steps, but not the exclusion of any other
element, integer or step, or group of elements, integers or steps.
The use of the expression "at least" or "at least one" suggests the use of one or more
elements or ingredients or quantities, as the use may be in the embodiment of the
disclosure to achieve one or more of the desired objects or results.
I
6-?7--- r: Any discussion of documents, acts, materials, devices, articles or the like that has b e k i ' i - - ~ ~.. -
included in this specification is solely for the purpose of providing a context for the
disclosure. It is not to be taken as an admission that any or all of these matters form a
part of the prior art base or were common general knowledge in the field relevant to
the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or
quantities are only approximations and it is envisaged that the values higherllower
than the numerical values assigned to the parameters, dimensions or quantities fall
within the scope of the disclosure, unless there is a statement in the specification
C specific to the contrary.
The foregoing description of the specific embodiments will so fully reveal the general
nature of the embodiments herein that others can, by applying current knowledge,
readily modifL and/or adapt for various applications such specific embodiments
without departing from the generic concept, and, therefore, such adaptations and
modifications should and are intended to be comprehended within the meaning and
range of equivalents of the disclosed embodiments. It is to be understood that the
phraseology or terminology employed herein is for the purpose of description and not
of limitation. Therefore, while the embodiments herein have been described in terms
of preferred embodiments, those skilled in the art will recognize that the embodiments
@ herein can be practiced with modification within the spirit and scope of the
embodiments as described herein.

WE CLAIM:
1. A one-way clutch assembly for selectively transmitting torque from a prime
mover to a driven member, said assembly comprising:
a driven element torque-transmittingly cooperating with the driven member;
a threaded shaft adapted to receive torque form the prime mover; and
a driving element threadably displaceable on said threaded shaft in an axial
direction to be selectively in an engaged configuration and a disengaged
configuration with said driven element, said driving element adapted to
transmit torque from the threaded shaft to the driven element in said
engaged configuration.
2. The assembly as claimed in claim 1 further optionally comprises at least one
positional spring adapted to rotationally constrain the driving element to be
displaced in said axial direction to enable said engaged configuration.
3. The assembly as claimed in claim 1, wherein said engaged configuration is
achieved by virtue of difference in inertia of said threaded shaft and said
driving element.
@ 4. The assembly as claimed in claim 1, wherein said disengaged configuration is
achieved by a resultant force resulting due to relative motion of said driving
element and said driven element.
5. The assembly as claimed in claim 1, wherein said threaded shaft is provided
with threads along at least a portion thereof, said threads being at least an
internal threads and an external threads.
6. The assembly as claimed in claim 1 and claim 3, wherein said driving element
has matching threads complementary to said threads of said threaded shaft.
7. The assembly as claimed in claim 1, wherein said driving element has a shape
selected from the group consisting of a frustum shape and an annular disc
shape.
8. The assembly as claimed in claim 1, wherein said driven element has a shape
selected from the group consisting of a cup shaped and disc shaped.