JPH0536095Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electromagnetic clutch, particularly an electromagnetic clutch suitable as a low torque transmission clutch used in office equipment.

[Conventional technology]

A stationary coil type electromagnetic clutch is known as a type of electromagnetic clutch.

FIG. 4 is a longitudinal sectional view of a conventional coil stationary electromagnetic clutch of this type. This will be explained based on the figure. A field core 5 consisting of a core 2 having an annular groove having a U-shaped cross section and an excitation coil 4 disposed inside the annular groove via a coil bobbin 3 is rotatably supported via a bearing 6, This field core 5 has a bearing 6
Movement in the axial direction is restricted by a snap spring (not shown) provided at one end of the inner ring. A lead wire 7 connects the excitation coil 4 and a power source, and is supported by the core 2 via a rubber bush 8. This electromagnetic clutch is of a stationary coil type, and the field core 5 is fixed to a fixed member of the device via a detent plate 9 punched out using a press.

On the other hand, a gear 10 drivingly connected to the driving side is rotatably supported on the protruding end of the rotating shaft 1 via a bearing 11. , 6, and a rotor 13 and a collar 12 interposed between the rotor 12 and the rotor 13 restrict movement in the axial direction. The rotor 13 is equipped with a flange 13a that functions as a magnetic attraction surface, and between this flange 13a and the gear 10,
An annular armature 14 is riveted and interposed on an annular leaf spring 15 fixed to the end face of the gear 10.

With this configuration, when the excitation coil 4 is demagnetized, the armature 1
4 is spaced apart from the flange 13a of the rotor 13, and the gear 10 driven from the driving side is connected to the rotating shaft 1.
It is idling at the top, and the rotating shaft 1 is stopped. and,
When the excitation coil 4 is excited, a magnetic flux is formed,
Since the armature 14 elastically deforms the leaf spring 15 and is magnetically attracted to the flange 13a, the rotor 1 integrated with the rotating shaft 1 is connected to the rotor 1 through the armature 14.
3 is transmitted with the rotation of the gear 10, and the rotating shaft 1 rotates.

However, such conventional electromagnetic clutches do not necessarily satisfy the recent demands for structural simplification, and there is a problem that they cannot be provided at low cost.

An electromagnetic clutch disclosed in US Pat. No. 4,346,616 has been proposed as a solution to these problems, and this will be explained based on the longitudinal sectional view shown in FIG. In the figure, a rotor 42 made of iron-based sintered alloy and treated with steam is fixed on a rotating shaft 41 that is supported on the equipment fixing part 40 side, and an annular groove 42 of the rotor 42 is fixed.
A stator 43, which is made of a magnetic material and is made of an oil-impregnated iron-based sintered alloy, and which includes a hollow cylindrical flange portion 43a and a cylindrical portion 43b is disposed within the stator 43 so as to be relatively rotatable. A synthetic resin holder 44 having an annular protrusion 44a and around which an excitation coil 45 is wound is fitted and fixed to the cylindrical portion 43b of the stator 43, and a lock pin 46 protrudes from the holder 44 to the outside. is engaged with a fixing member 47 on the device side. 48 is a rotor 42 and a stator 43
It is a tightening ring to prevent it from coming off. By doing this, the rotor 42 and the rotating shaft 41 are
and rotate as one. On the other hand, on the rotating shaft 41 is a sprocket 49 that is drivingly connected to the driving side.
is located between the fixing part 40 and the rotor 42 and is rotatably fitted therein, and an armature 50 is fixed in the rotational direction and supported slidably in the axial direction on the end surface of the rotor 42. has been done. 51 is interposed between the armature 50 and the pin 52 on the rotating shaft 45 side, and connects the armature 50 to the sprocket 4.
This is a spring member that urges the 9 side. Reference numeral 42b denotes a demagnetizing portion provided on the rotor 42, and an air gap g is formed between the rotor 42 and the armature 50.

With this configuration, when the excitation coil 45 is demagnetized, an air gap g is formed, and the sprocket 49 idles on the rotating shaft 41 which is stopped. Then, when the excitation coil 45 is excited, the armature 50 is moved by the spring member 51 due to the formation of magnetic flux.
The rotor 42 that is integrated with the rotating shaft 41 is elastically deformed and is attracted to the friction surface 42c of the rotor 42.
However, the sprocket 49 is connected via the armature 50.
The rotation of the rotating shaft 41 is transmitted, and the rotating shaft 41 rotates.

[Problem that the invention attempts to solve]

However, in such a conventional electromagnetic clutch, when the rotating shaft 41 rotates, the inner circumferential surface of the stator 43 formed of an oil-impregnated iron-based sintered alloy and the rotor formed of an iron-based sintered alloy and subjected to steam treatment are removed. The problem is that the rotating fitting surfaces formed by the outer circumferential surface of 42 are made of the same iron-based material, and even if one side is oil-impregnated, the locking phenomenon due to lack of oil is likely to occur, making it impossible to ensure a long service life. It was hot. Further, such a configuration is not necessarily satisfactory in terms of reducing the size and weight of the device. In particular, conventional electromagnetic clutches have the disadvantage that they are not suitable for use in office equipment that requires quietness, as no measures have been taken to prevent the impact noise generated when energized and de-energized.

[Means for solving problems]

In order to solve such problems, the present invention includes a gear to which an armature is attached, a rotor that is fixed to a shaft and has an annular groove opening on a side surface with the armature side as a magnetic attraction surface, and an annular groove of this rotor. In an electromagnetic clutch comprising a resin coil bobbin that is rotatably supported in a groove and has a detent flange at one end, the gear to which the armature is attached is made of resin, and the flange of the resin coil bobbin is An annular member made of a magnetic material is integrally embedded in the coil bobbin, and a snap spring that restricts movement of the coil bobbin in the axial direction is brought into contact with the flange and engaged with the boss of the rotor.

[Effect]

According to the present invention, when the excitation coil is in a non-excited state, the armature is spaced apart from the rotor, so the rotation of the gear is not transmitted to the rotor, and the armature idles on the shaft of the gear. On the other hand, when the excitation coil is excited, the magnetic flux is formed and the armature causes the leaf spring to elastically deform and is attracted to the rotor, so the rotor fixed to the shaft controls the rotation of the gear via the armature. is transmitted and the shaft rotates. When the excitation coil becomes de-energized again, the armature separates from the rotor due to the elastic return force of the leaf spring, and the leaf spring collides with the gear and the flange of the coil bobbin collides with the snap ring.

〔Example〕

1 to 3 show an example in which the electromagnetic clutch according to the present invention is implemented in a facsimile paper feeding device, FIG. 1 is a longitudinal sectional view thereof, and FIG. 2 is an A of FIG.
-A sectional view, and FIG. 3 is a side view of the rotor viewed from B. In these figures, a rotating shaft 22 protruding from a fixing member 21 of a facsimile paper feeding device has a rotor 2 having an annular groove 23a having a U-shaped cross section.
3 is fitted with a boss 23b and fixed with a set screw, and on the protruding end of the rotating shaft 22, a gear 24 made of synthetic resin that is drivingly connected to the driving side is connected with a snap spring (not shown) or the like. It is rotatably supported in a state where movement in the axial direction is restricted. 2
Reference numeral 5 denotes an armature formed in an annular shape and riveted to the same annular leaf spring 26. The armature 5 is elastically supported by the gear 24 by fixing the leaf spring 26 to the gear 24 with a plurality of setscrews 27. There is. This armature 25 is connected to the magnetic attraction surface 23 of the rotor 23.
It is interposed between the rotor 23 and the gear 24 with a predetermined gap g between the rotor 23 and the gear 24. The whole code is 28
The coil bobbin shown in 2 has a coil holding part 28b having an annular groove 28a opening in the outer radial direction and a flange 28c projecting from one end of the coil holding part 28b integrally molded with synthetic resin. It is rotatably supported on the boss 23b of the rotor 23 by fitting into the annular groove 23a. Further, the coil bobbin 28 is prevented from rotating by engaging the pin hole 28d of the flange 28c with the rotation stopper pin 29 on the fixing member 21 side, and is also prevented from rotating by the snap spring 30 and the bottom surface of the annular groove 23a. Movement in the axial direction is restricted. Here, since the coil bobbin 28 is rotatably supported by the boss 23b of the rotor 23, there is a slight clearance in the axial direction between the snap spring 30 and the bottom surface of the annular groove 23a. Furthermore, when the coil bobbin 28 is molded, an annular member 31 made of a magnetic material is insert-molded and embedded integrally therein.
The lead wire 33 of the excitation coil 32 installed in the annular groove 28a is connected to the notch 31 facing the annular member 31.
After the wires are connected in the coil bobbin 28, the wires are connected to the outside through a hole 28e provided in the coil bobbin 28.
functions as a button.

With the above configuration, when the excitation coil 32 is demagnetized, the armature 25 is separated from the end face of the rotor by the gap g, and the gear 24 driven from the driving side is connected to the rotating shaft 22.
The rotating shaft 22 is idle and stopped at the top. On the other hand, when the excitation coil 32 is excited, the magnetic flux is formed, which causes the armature 25 to move toward the leaf spring 26.
by elastically deforming the magnetic adsorption surface 23c of the rotor 23.
Since the rotor 23 is fixed to the rotating shaft 22, the rotation of the gear 24 is transmitted through the armature 25, and the rotating shaft rotates together with the gear 24. During this rotation transmission, the rotor 23 is idling on a synthetic resin coil bobbin 28 fixed to the device fixing part. Then, when the excitation coil 32 is demagnetized again, the armature 25 is separated from the end surface of the rotor 23 due to the elastic restoring force of the leaf spring 26. At this time, the leaf spring 26 which has elastically returned to the gear 2
7 collides with the end face of the coil bobbin 28.
moves slightly in the axial direction by the clearance, and the end face of the flange 28c collides with the snap spring 30. However, the gear 24 is made of synthetic resin while the plate spring 26 is made of metal, and the annular member 31 made of a magnetic material is attached to the flange 2 made of a resin material.
8c, and is configured so that the annular member 31 does not directly collide with the snap spring 30, so that noise such as squeaks caused by metals hitting each other is not generated, and collision noise is reduced.

[Effect of idea]

As explained above, according to the electromagnetic clutch according to the present invention, the gear to which the armature is attached is made of resin, and an annular member made of a magnetic material is integrally buried within the flange of the resin coil bobbin. Since the snap spring that restricts movement in the axial direction is attached to the boss of the rotor in opposition to the flange, the structure is simple, compact, and lightweight. In addition, since there are no parts where metal comes into direct contact with each other except between the armature and rotor, it is quieter and is ideal as an electromagnetic clutch used in office equipment where mechanical noise is a problem, especially in offices. can provide something. Furthermore, the inner member of the annular member that makes up the coil bobbin has a cylindrical shape, making it difficult for the coil bobbin to deform under its own weight, making it comfortable to drive without causing unpleasant chattering noises. This also has the effect of not increasing resistance.

[Brief explanation of the drawing]

1 to 3 show an embodiment of the electromagnetic clutch according to the present invention, FIG. 1 is a longitudinal sectional view thereof, and FIG.
The figure is a sectional view taken along line A-A in Figure 1, and Figure 3 is a cross-sectional view of the rotor.
The side view, FIGS. 4 and 5 are longitudinal sectional views of a conventional electromagnetic clutch, respectively. 22... Rotating shaft, 23... Rotor, 23a...
Annular groove, 23b... Boss, 23c... Magnetic attraction surface, 25... Armature, 28... Coil bobbin, 28a... Annular groove, 28b... Coil holding portion, 28c... Flange, 29... Detent pin, 31... Annular member, 32... Excitation coil.

Claims (1)

[Scope of utility model registration request] A gear 24 is rotatably supported on a shaft 22 and has an armature 25 attached to one side via a spring 26.
and the armature 25 fixed to the shaft 22.
A rotor 23 having a magnetic attraction surface 23c on one side and an annular groove 23a opening on the other side, and a resin coil bobbin 28 rotatably supported in the annular groove 23a of the rotor and having a detent flange 28c at one end. In the electromagnetic clutch equipped with the above, the gear 24 to which the armature 25 is attached is made of resin, and the coil bobbin 28 is made of resin.
An annular member 3 made of a magnetic material is disposed within the flange 28c of the
A snap spring 30 is embedded in the coil bobbin 28 and restricts movement of the coil bobbin 28 in the axial direction.
An electromagnetic clutch characterized in that it is engaged with the boss 23b of the rotor 23 in opposition to the flange 28c.