JPH08210387A - Electromagntic clutch - Google Patents

Abstract

PURPOSE: To provide an electromagnetic clutch capable of preventing the shut-off of the transmission of the rotation by the prescribed driving torque, and surely shutting off the transmission of the rotation only when the temperature rises to the prescribed value or above. CONSTITUTION: A semi-circularly extended fixing piece 7a is formed on a free end part of a leaf spring where a base end part is fixed to a flange part 5a of an armature hub 5, and the leaf spring 7 and an armature 9 are integratedly fixed to each other by rivets 8 made of synthetic resin which are inserted into stepped through holes of the armature 9 from through holes of the fixing piece 7a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic clutch in which a rivet for integrally fixing a leaf spring and an armature is melted by a temperature rise caused by slip rotation.

[0002]

2. Description of the Related Art An electromagnetic clutch proposed in Japanese Utility Model Laid-Open No. 4-97124 has a structure in which a rivet integrally fixing a leaf spring and an armature is melted when the temperature rises due to heat generated by slip rotation. .

[0003]

In the conventional electromagnetic clutch, it has been described that a rivet is formed of a fuse metal material. However, the mechanical strength is such that the rivet is not broken by a predetermined driving torque and the temperature rises by a predetermined value or more. It is difficult to design a rivet composed of material properties that will melt. An object of the present invention is to provide an electromagnetic clutch in which the transmission of rotation due to a predetermined driving torque is prevented from being interrupted, and the transmission of rotation is reliably interrupted only when the temperature rises above a predetermined value.

[0004]

In order to achieve such an object, in the electromagnetic clutch of the present invention, a leaf spring having a base end fixed to an armature hub and a free end of the leaf spring are formed. A fixing piece extending in the circumferential direction, a rivet made of a synthetic resin material individually inserted into a plurality of through holes formed in the fixing piece, and the tip of the rivet is inserted into a stepped through hole. The leaf spring and the armature are integrally fixed by thermally deforming the tip of the rivet in the stepped through hole of the armature.

[0005]

With the electromagnetic clutch, the rotation of the rotor to which the driving force of the engine is input is transmitted to the compressor via the armature, the leaf spring, and the armature hub. When the compressor is locked and the armature and rotor slip rotate, the heat generated causes the temperature of the armature to rise above a certain value, so the rivets that fix the leaf spring and armature are melted, and the rotation is not transmitted to the compressor. Be cut off.

[0006]

1 is a front view showing an embodiment of an electromagnetic clutch of the present invention. 2 is a sectional view taken along the line AA of FIG.
The electromagnetic clutch shown in these drawings is mounted on the air conditioner compressor 1 and used as a device for transmitting the rotation by the driving force of the engine. The housing of the compressor 1 supports a field core 3 in which an electromagnetic coil 2 is installed, and the cylindrical protrusion of the compressor 1 has a rotor 4 in which the field core 3 is loosely fitted via a bearing. It is rotatably supported. An endless belt (not shown) is hung on the outer peripheral surface of the rotor 4 V
The V-shaped belt groove 4a is integrally formed.

The rotary shaft of the compressor 1 is fitted with an armature hub 5 fitted with serrations and prevented from coming off. A flange 5a of the armature hub 5 is fitted with a metal rivet 6 at the base end of a leaf spring 7. The part is fixed. At the free end of the leaf spring 7 in which the bending portion is rectangular,
A circular arc-shaped fixing piece 7a (may be an annular fixing piece) extending in the circumferential direction is formed. In addition, a plurality of (three) through holes are formed in the fixing piece 7a at equal intervals at positions on the same circumference, and a rivet made of a synthetic resin material is inserted from each through hole. By thermally deforming the tip of 8 in the stepped through hole 9a of the armature 9,
The leaf spring 7 and the armature 9 are integrally fixed. Reference numeral 10 is a stopper rubber interposed between the flange portion 5a of the armature hub 5 and the armature 9, and only the head portion is shown in FIG.

In the electromagnetic clutch having such a structure, when the armature 9 is magnetically attracted to the rotor 4 by energizing the electromagnetic coil 2, a plurality of rivets 8 and a leaf spring 7 and an armature hub 5 are used to connect the rotor 4 to the rotor 4. The rotation is transmitted to the rotating shaft to drive the compressor 1. When the electromagnetic coil 2 is de-energized, the armature 9 is separated from the rotor 4 by the spring force of the leaf spring 7, so that the transmission of rotation to the rotary shaft is cut off. When the electromagnetic coil 2 is energized without noticing the locked state of the compressor 1, heat is generated by slip rotation of the armature 9 and the rotor 4. When this heat reaches a temperature equal to or higher than a predetermined value, the rivet 8 is melted and the transmission of rotation to the rotary shaft is cut off.

[0009]

As described above, in the electromagnetic clutch of the present invention, the leaf spring having the base end fixed to the armature hub and the fixing piece extending in the circumferential direction formed at the free end of the leaf spring are provided. The rivet includes a rivet made of a synthetic resin material which is individually inserted into a plurality of through holes formed in the fixing piece, and an armature in which a tip of the rivet is inserted into a stepped through hole. The leaf spring and the armature are integrally fixed by thermally deforming the tip of the armature in the stepped through hole of the armature, so that the design condition of the function as the thermal fuse is satisfied by the number of rivets. be able to. Further, the distance between the base end portion and the free end portion (deflection portion) of the leaf spring is set equal to the distance between the base end portion and the free end portion of the conventional leaf spring. The function of the thermal fuse can be configured without changing the spring characteristics (such as bending stress).

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of an electromagnetic clutch of the present invention.

FIG. 2 is a sectional view of the electromagnetic clutch of FIG. 1 taken along the line AA.

[Explanation of symbols]

5 ... Armature hub, 7 ... Leaf spring, 8 ... Synthetic resin rivet, 9 ... Armature.

Claims (1)

[Claims] 1. A leaf spring having a base end portion fixed to an armature hub, a circumferentially extending fixing piece formed on a free end portion of the leaf spring, and a plurality of holes formed in the fixing piece. The synthetic resin material rivet individually inserted into the through hole, and the armature having the tip of the rivet inserted into the stepped through hole, the tip of the rivet, the stepped through hole of the armature. An electromagnetic clutch in which the leaf spring and the armature are integrally fixed by being thermally deformed inside.