TECHNICAL FIELD
The present disclosure generally relates clutches and in particular relates to a magnetic one-way clutch assembly.
BACKGROUND
A clutch is a device that facilitates transmission of power and therefore usually motion from one component (a driving member) to another (a driven member), in an engaged position. Also, a clutch is adapted to disengage a driving member form a driven member as per the requirement.
Clutches are used whenever transmission of power or motion needs to be controlled either in amount or over time. In the simplest application, clutches connect and disconnect two rotating shafts (drive shafts). In these devices, one shaft is typically attached to a motor or other power unit (the driving means) while the other shaft (the driven means) provides output power for work.
A one-way clutch is particular type of clutch that transmits torque when rotated in one direction and adapted to freewheel when turned in the opposite direction. In a one-way clutch, transmission of power from one component (a driving element) to another (the driven element) is same as in case of a typical clutch. However, if the driven element starts rotating at a higher speed, the driving element disengages from the driven element. This disengagement is caused by the one-way clutch, which transmits power from driving element to the driven element, but not the opposite way.
For engagement/disengagement purposes, conventional one-way clutches have also employed permanent magnets. Further, one-way clutches employ multiple rollers/cams for torque transmission and multiple profiles and springs at different locations for supporting these rollers/cams. A limitation of the existing magnetic one-way clutches is that they require a number of magnets of smaller dimensions, and facilitate very low torque transmission. Further, conventional one-way clutches do not allow complete disengagement during freewheeling.
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OBJECTS
Some of the objects of the present disclosure aimed to ameliorate one or more problems of the prior art or to at least provide a useful alternative are described herein below:
An object of the subject matter described in present disclosure is to provide a magnetic one-way clutch that is easy to manufacture.
Another object is to provide a magnetic one-way clutch that is capable of transmitting comparatively higher torque than existing one-way clutches.
One more object is to provide a magnetic one-way clutch that is adapted to completely disengage during freewheeling.
Another object is to provide a magnetic one-way clutch that provides comparatively longer life.
Another object is to provide a magnetic one-way clutch that is cost efficient and reliable.
Other objects and advantages of the system of the present disclosure will be more apparent from the following description when read in conjunction with the accompanying figures, which are not intended to limit the scope of the present disclosure.
SUMMARY
Described herein is a magnetic one-way clutch assembly comprising a pair of annular-shaped, relatively rotatable members one enclosing the other with space therebetween, at least a coil wound around an outer of the relatively rotatable members, wherein the coil is adapted to carry electric current therethrough; plurality of circumferentially extending slots provided on an inner of the relatively rotatable members, wherein each slot is capable of accommodating a metallic core; and a locking plate placed at a distance from the inner and in front of outer free surfaces of the metallic cores, wherein the locking plate is mounted on a driven member.
In an embodiment, the metallic core is of a height less than a depth of anyone of the slots.
In an embodiment, the outer and the inner are made of a metal.
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In an embodiment, the outer and the inner are made of a non-metal.
In an embodiment, the locking plate is made of iron.
In an embodiment, each of the metallic cores is attached to an inner wall of a corresponding slot via at least one spring.
In an embodiment, the number of slots is two or more.
In an embodiment, the slots are cylindrical in shape.
In an embodiment, the slots are C-shaped.
In an embodiment, the coil is wound in a groove-like portion of the outer.
BRIEF DESCRIPTION OF DRAWINGS
A magnetic one-way clutch assembly of the present disclosure will now be explained in relation to the non-limiting accompanying drawings, in which:
FIGURES 1a and 1b illustrate a side view and a front view of a magnetic one-way clutch assembly, respectively, in accordance with one embodiment of the present disclosure;
FIGURES 2a and 2b illustrate a side view and a top view of a magnetic one-way clutch assembly, respectively, in accordance with another embodiment of the present disclosure;
FIGURE 3 illustrates a side exploded view of the magnetic one-way clutch assembly of Fig. 1, along with a locking plate.
FIGURES 4 and 5 illustrate front exploded views of the magnetic one-way clutch assembly in the two embodiments depicted in Fig. 1 and Fig. 2, respectively, depicting two different configurations of metallic cores in conjunction with two different locking plates.
FIGURES 6 and 7 illustrate side views of the locking plate in two embodiments depicted in FIGURES 4 and 5.
DETAILED DESCRIPTION
A magnetic one-way clutch assembly of the present disclosure will now be described with reference to the accompanying drawings which do not limit the scope
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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.
The description hereinafter, of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify 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.
The present disclosure envisages a magnetic one-way clutch to overcome the drawbacks of the prior art. The magnetic one-way clutch as described herein uses the concept of electromagnetism for facilitating engaged and disengaged configurations. In particular, a number of metallic cores placed within a body of the magnetic one-way clutch gets magnetized when current passes through a coil wound around the body, and gets attached to a driven element of the one-way clutch to transmit torque/motion. When the current stops, the magnetic field ceases to exist and the cores get demagnetized and release the driven element. As against conventional one-way clutches, there are no rolling elements as such in the present one-way clutch, and therefore the transmission losses are comparatively lower. Also, the present magnetic
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one-way clutch limits the number of components required and is thus easy to manufacture. Additionally, the magnetic one-way clutch of the present disclosure is adapted to be completely disengaged during freewheeling.
Referring to FIGURES 1 to 5, a magnetic one-way clutch 100 is disclosed, in accordance with various embodiments of the subject matter. In the embodiments shown, the magnetic one-way clutch 100 includes two relatively rotatable members, for example, a stationary outer 105 securely fastened against movement by appropriate means (not shown) and a rotatable inner 110, which is adapted to be keyed to a rotatable shaft (not shown). In an embodiment, the stationary outer 105, hereinafter referred to as outer 105, and the rotatable inner 110, hereinafter referred to as inner 110, are made of metal such as steel. The outer 105 and the inner 110, in another embodiment, may be made of a non-metal such as Bakelite. Further, the outer 105 is provided with a groove like portion 107.
The outer 105 and the inner 110 are of annular form, the inner surface of the outer 105 closely surrounding the inner 110, but out of contact therewith. Further, one or more a coil 115 is wound around the periphery of the outer, in the groove-like portion 107. The coil 115 is connected to an external power source (not shown). When electric power is supplied to the coil 115, the coil 115 produces a magnetic field in and around the empty spaces of the magnetic one-way clutch 100. When the power supply is stopped, the current stops and the magnetic field cease to exist.
Further, the inner 110 is provided with two or more circumferentially extending slots or recesses 120. Within each of these slots 120, a metallic core 125 is provided. The metallic cores 125 of the embodiment shown in Fig. 1 are cylindrical in shape, while the metallic cores 125 of the embodiment shown in Fig. 2 are C-shaped. In an exemplary embodiment, the metallic cores 125 are made of soft iron. However, it will be appreciated by those skilled in the art that the shape and the number of the metallic cores 125 may vary according to the torque requirement and/or intended application. In an embodiment, a height of the metallic core 125 is less than or equal to a depth of the slots 120.
Further, each of the metallic cores 125 is attached to an inner wall of each of the corresponding slots 120 through a spring 130. For example, a spring 130 may be
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attached to an inner wall of a slot 120 and an inner flat surface of a corresponding core 125. Further a locking plate 305 is placed at a distance from the inner 110, in front of the slots 120. The locking plate 305 is further mounted onto a driven member.
The locking plate has a flat surface 605, 705, on which a number of protrusions 610, 710 are provided. The scheme of the protrusions 610, 710 on the locking plate 305 is as per the configuration of the one-way clutches shown in Fig. 1 and Fig. 2. For example, for a one-way clutch having n number of metallic cores 125, there may be equal number of protrusions 610, 710 on the locking plate 305. The protrusions 610, 710 are, at one end, thick wall regions that taper down till the flat face 605, 705 of the locking plate 305.
In operation, the inner 110 mounted on a drive shaft (now shown) of a driver means, such as a motor, starts rotating at a speed of the drive shaft when the driver means is powered ON. Simultaneously, the coil 115 also provided with electric power using the same electric source, for example, using a starter switch or from the same power source. This in turn magnetizes the metallic cores 125 placed inside the slots 120 of the inner 110. Once magnetized, the metallic cores 125 get attracted to the locking plate 305. The metallic cores 125, through their respective outer free surfaces 125ʹ, get attached to a flat face 605, 705 of the locking plate 305 and create an engagement between the inner 110 and the locking plate 305, which in turn is mounted on the driven member.
In an embodiment, the engagement between the locking plate 305 and the metallic cores 125 is strengthened by protrusions 610, 710 provided on the locking plate 305. When the metallic cores 125 come into contact with the thick wall regions of the protrusions 610, 710, a mechanical locking is created between the metallic cores 125 and the protrusions 610, 710. The metallic cores 125, with the help of such mechanical locking, transmit torque to the locking plate 305 and, in turn, to the driven member. The driven member thus starts rotating at the speed of the inner 110 as one piece with the inner 105. When a speed of the driven member becomes more than that of the inner 110, the metallic cores 125 slip onto the tapered faces of the protrusions 610, 710, thus causing slipping and discontinuance of torque.
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Further, when the magnetic field ceases upon stopping the current to the coil 115, the springs 130 pull the metallic cores 125 back into the slots 120, thereby disengaging the locking plate 305 from the inner 110. Such disengagement or ‘no contact’ between the drive member (comprised of the inner 110) and the driven member (comprised of the locking plate 305) is in totality and complete.
The following calculations can be made to ascertain a magnetic pull force B that is applied on an exemplary metallic core 125 of a particular material and of certain shape and dimension, under ideal conditions.
Magnetic Reluctance,
AlAlRgrel00
, where Aʹ is the area of the outer, μ0 is permeability in free space, μrel is relative permeability of the material of the metallic core, l is length of a metallic core, and lg is the space between an outer end face of the metallic core and the flat surface of locking plate that comes into contact with that outer end face of the metallic core.
Further, Iʹ=Ni, where Iʹ is the effective current in ampere, N is the number of turns in the coil, and i is the actual current.
Further, magnetic Flux can be calculated as
RIF
Also, magnetic Field can be calculated as
AB
Accordingly, magnetic Pull force can be calculated as
relBAF022.
, where A is the area of the metallic core.
TECHNICAL ADVANCEMENTS AND ECONOMIC SIGNIFICANCE
The magnetic one-way clutch, in accordance with the present disclosure described herein above has several technical advantages including but not limited to the realization of:
 a magnetic one-way clutch that is easier to manufacture - due to less number of parts and simple construction;
 a magnetic one-way clutch that is capable of transmitting comparatively more torque - as there is less transmission loss;
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 a magnetic one-way clutch that is adapted to provide complete disengagement during freewheeling - as the magnetic field ceases when an electric current stops flowing through the solenoid coils;
 a magnetic one-way clutch that consumes comparatively less power - as there is minimum losses and minimum number of parts used for operation;
 a magnetic one-way clutch that provides comparatively longer life - due to simple construction;
 a magnetic one-way clutch that is comparatively cost efficient - due to simple construction and less number of parts;
 a magnetic one-way clutch that is comparatively reliable - as it has simple construction; and
 a magnetic one-way clutch that facilities material savings - due to less number of parts are used.
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.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower 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 specific to the contrary.

WE CLAIM:
1. A magnetic one-way clutch assembly comprising:
a pair of annular-shaped, relatively rotatable members (105, 110) one enclosing the other with space therebetween;
at least a coil (115) wound around an outer (105) of the relatively rotatable members, wherein the coil is adapted to carry electric current therethrough;
plurality of circumferentially extending slots (120) provided on an inner (110) of the relatively rotatable members, wherein each slot is capable of accommodating a metallic core (125); and
a locking plate (305) placed at a distance from the inner and in front of outer free surfaces (125ʹ) of the metallic cores, wherein the locking plate is mounted on a driven member.
2. The one-way clutch assembly as claimed in claim 1, wherein the metallic core is of a height less than a depth of anyone of the slots 120.
3. The one-way clutch assembly as claimed in claim 1, wherein the outer and the inner are made of a metal.
4. The one-way clutch assembly as claimed in claim 1, wherein the outer and the inner are made of a non-metal.
5. The one-way clutch assembly as claimed in claim 1, wherein the locking plate is made of iron.
6. The one-way clutch assembly as claimed in claim 1, wherein each of the metallic cores is attached to an inner wall of a corresponding slot via at least one spring.
7. The one-way clutch assembly as claimed in claim 1, wherein the number of slots is two
or more.
8. The one-way clutch assembly as claimed in claim 1, wherein the slots are cylindrical in
shape.
9. The one-way clutch assembly as claimed in claim l, wherein the slots are C-shaped.
10. The one-way clutch assembly as claimed in claim l, wherein the coil is wound in a
groove-like portion (107) of the outer.