1. Technical Field of the Invention
The present invention relates to a magnetic repulsion coupling for transmission of a rotational movement from a driving member to a driven member without relative contact.
2. Description of the Prior Art
It is known in the technical sector relating to the transmission of rotational movements from a driving member to a driven member that there is the need to dampen, during transmission, the vibrations which are produced by the driving member and could damage the driven member and/or the device to which it is connected.
It is also known that, in order to find a solution to the problem, magnetically driven transmission couplings have been devised, these being able to avoid direct contact between the driving member and driven member and consequently absorb the vibrations transmitted by the former to the latter.
These known couplings are based on the provision of permanent magnets with opposite polarities N-S, arranged in planes perpendicular to the axis of rotation and respectively situated on the driving member and on the driven member so as to be frontally facing each other.
This solution, however, has drawbacks arising from the fact that only very low torque values are possible with the coupling and, in the event of relative slipping of the driving member and driven member, there is a drastic reduction in the said torque value since the N-S permanent magnets are angularly out-of-phase and, no longer being situated opposite each other, reduce considerably the relative magnetic attraction.
In addition to this, once slipping has occurred, the speed of relative rotation is such that it is no longer possible to re-establish the angular phasing unless the device is stopped and reset to its initial condition.
The technical problem which is posed, therefore, is to provide a coupling for transmission of a rotational movement from a driving member to a driven member, able to produce a substantial reduction in the vibrations transmitted from the former to the latter, so as to achieve higher drive torque values for the same dimensions and prevent irreversible angular dephasing of the driving member with respect to the driven member with a reduction in the drive torque.
In connection with this problem it is also required that this device should have small dimensions, be easy and inexpensive to produce and assemble and be able to be easily installed at any user facility using normal standardised connection means.
These results are achieved according to the present invention by a coupling for transmission of a rotational movement from a driving member to a driven member, comprising permanent magnets which are respectively integral with the driving member and the driven member, said permanent magnets having the same polarity and lying in respective radial planes parallel to the axis of rotation and situated opposite each other so that each pair of facing magnets produces a corresponding magnetic repulsion force.
Further details may be obtained from the following description of a non-limiting example of embodiment of the subject of the present invention provided with reference to the accompanying drawings in which:
As shown in
On the opposite side to the pulley 11, the driving member 10 has a plurality of axial projections 12—three in number in the example, arranged at 120°—each of which has formed internally a seat 12a able to contain a permanent magnet 13 which is arranged in a radial plane parallel to the axis of rotation.
The driving member 10 has internally a cylindrical through-seat or opening 14 able to allow the insertion of a sleeve 24 integral with the hub 21 of a driven member 20 in turn provided with radial projections 22 which are integral with the hub 21 and which have formed therein a respective seat 22a able to contain a magnetic element 23 in turn arranged in a plane radial and parallel to the axis of rotation and with a polarity matching that of the corresponding permanent magnet 13 of the driving member.
Assembly of the coupling (
As shown in
An example of this device consists of an alternator of motor vehicles.
With this configuration the operating principle of the coupling is as follows:
As shown, it is envisioned that the coupling can be mono-directional, namely with magnets of the driving member arranged solely on the side of the radial projection 12 situated in the same direction as the direction of rotation (
According to preferred embodiments of the invention, it is envisaged moreover being able to provide a safety stop between driving member and driven member; in the example according to
As shown in
In both cases it is preferred to alternate pairs with one polarity (N-N) with pairs having an opposite polarity (S-S) so that the magnets inserted in the same radial projection 12,22 are attracted to each other, increasing the force which opposes their separation.
In the case of all the embodiments described it is envisaged moreover that the driving member and the driven member may reverse their roles should it be required to connect the device (belt or the like) for transmission of the main movement to the inner driven member instead of to the outer driven member.
In addition, it is envisaged that the bearing 3 may be replaced by an equivalent part such as a bushing or the like.
It is therefore clear how the coupling according to the invention, which acts by means of magnetic repulsion driving, allows the drive torque to be increased considerably compared to that which can be obtained by a coupling based on attraction, since the matching polarity of the permanent magnets tends to increase the relative repulsion force in the event of relative angular slipping of the driving member and driven member, moreover avoiding the need to stop the coupling in order to re-establish the relative angular phasing; in fact, in the rest condition, the matching polarity of the permanent magnets situated opposite each other will tend to bring the coupling back into the angular equilibrium condition.
Number | Date | Country | Kind |
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MI2007A000438 | Mar 2007 | IT | national |