JPH0238103Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electromagnetic coupling device that is used in, for example, a copying machine and includes a hub made of resin.

Conventionally, as this type of electromagnetic coupling device, one shown in FIG. 1 has been adopted, and this will be briefly explained based on the same figure. That is, FIG. 1 shows an electromagnetic clutch which is an example of an electromagnetic coupling device. 1 is a stator with a built-in coil 2, 3 is a rotor to which a lining 4 is fixed, and a key 5 connects the driven shaft 6 to the rotor. It is provided. Reference numeral 7 denotes a hub made of thermoplastic resin having a gear 8, through which a driven shaft 6 is inserted and in sliding contact with each other, so that the hubs are rotatable. Further, screw holes 9 are provided in the hub 7 at equal intervals in the circumferential direction. Reference numeral 10 denotes a return leaf spring, which is fixed to the hub 7 by a screw 11 screwed into the screw hole 9. An armature 12 is fixed to a portion of the leaf spring 10 facing the lining 4 by a rivet 13. A constant gap g is maintained between this armature 12 and the rotor 3.

Therefore, when a current is passed through the coil 2, a magnetic flux φ is generated as shown by the broken line in the figure, forming a magnetic circuit, and the armature 12 is attracted to the rotor 3 against the elastic force of the leaf spring 10. . The rotation on the drive side is transmitted to the driven shaft 6 via the gear 8, leaf spring 10, armature 12, lining 4, rotor 3, and key 5.

On the other hand, when the current is cut off, the magnetic flux disappears and the armature 12 is separated from the rotor 3 due to the elastic force of the leaf spring 10 and rotation is stopped.

However, in the conventional electromagnetic clutch, since the hub 7 is made of resin, its contraction and expansion are large, which loosens the screw 11 and causes the leaf spring 1 to loosen.
Either the clamping force of 0 is lost and the leaf spring 10 is damaged, or the elastic force of the leaf spring 10 no longer acts on the armature 12, causing the rotor 3 and the armature 12 to fail even though the coil 2 is de-energized. The disadvantage is that they come in contact with each other.

Therefore, it is conceivable to use iron-based rivets instead of the screws 11 to secure the leaf spring 10 to the hub 7, but in this case there is a problem that the members on the hub 7 side may be damaged by the clamping pressure. In addition, in this type of small torque microlatch used in copying machines, etc., the leaf spring 10 is very thin.
Since the attractive force of the coil 2 is also small, the elastic force of the leaf spring 10 fluctuates significantly depending on the tightening force of the screw 11, and the resilient performance of the leaf spring 10 is unstable.

The present invention was developed in view of these circumstances, and includes protruding protrusions integrally on a resin hub, drilling mounting holes in the leaf spring, and inserting the protrusions into the mounting holes to prevent thermal deformation. To provide an extremely simple structure in which a leaf spring is fixed to a hub by fixing the leaf spring to the hub, which can be manufactured at low cost, and which can securely fix the leaf spring to the hub, and also to stabilize the elastic performance of the leaf spring. The present invention provides an electromagnetic coupling device that can perform the following functions. Hereinafter, the configuration and the like will be explained in detail by referring to embodiments shown in the drawings.

FIG. 2 is a sectional view showing an electromagnetic clutch according to the present invention, and the same members as in FIG. In the same figure,
The hub 21 has a gear 22 and is connected to the hub 7.
It is made of thermoplastic resin as well, and a plurality of protrusions 23 are integrally protruded from the portion on the rotor 3 side at equal intervals in the circumferential direction. The leaf spring 10 is provided with a plurality of mounting holes 24 at positions corresponding to the protrusions 23.

Therefore, in order to securely attach the leaf spring 10 to the hub 21, first the protrusion 23 of the hub 7 is fitted into the mounting hole 24 of the leaf spring 10. Next, the leaf spring 10 and the hub 21
is held between the sonic poles of an ultrasonic welding device (not shown). Then, ultrasonic vibrations are applied to both members 10 and 21 while applying pressure. In this manner, the plate spring 10 can be reliably attached to the hub 21 by thermally deforming the projections 23 and fixing them in the attachment holes 24.

As explained above, according to the present invention, a plurality of protrusions are integrally provided at intervals on a resin hub, mounting holes are bored in the leaf spring, and these protrusions are inserted into the mounting holes. Since the leaf spring is fixed to the hub by being inserted and thermally deformed, the leaf spring can be firmly fixed without damaging the hub-side components, and the leaf spring has sufficient ability to fix to the hub. Guaranteed. In addition, since the fixation is not done by screws as in the past, there is no need for screw machining, which makes it possible to streamline assembly, and the elastic force does not fluctuate significantly, making the elastic performance of the leaf spring more stable. can be achieved. Furthermore, since the hub is made of resin, not only is the material cost low, but there is no need to provide a bearing between the hub and the driven shaft, and the number of parts can be reduced, resulting in lower costs.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional electromagnetic clutch, and FIG. 2 is a sectional view of an electromagnetic clutch according to the present invention. 10... leaf spring, 12... amateur, 21...
...Hub, 23...Protrusion, 24...Mounting hole.

Claims (1)

[Scope of utility model registration request] A hub made of synthetic resin and rotatably supported with its center slidingly in contact with a shaft; a plurality of protrusions integrally formed on the hub at intervals in the circumferential direction;
The invention is characterized by comprising a leaf spring that is fitted into the plurality of protrusions and fixed by thermally deforming each of the protrusions, and an armature that is attached to the leaf spring and forms one connecting surface. Electromagnetic coupling device.