Electromagnetic clutch and manufacturing method thereof

Patent metadata

Field	Value
Publication number	US-9500239-B2
Application number	US-201414761734-A
Country	US
Kind code	B2
Filing date	Jan 21, 2014
Priority date	Jan 23, 2013
Publication date	Nov 22, 2016
Grant date	Nov 22, 2016

Abstract

An end surface portion of a rotor includes a friction surface and an end surface, which are spaced from each other in an axial direction. The armature is attracted and attached to the friction surface of the rotor by an electromagnetic attractive force when a solenoid coil is energized. The stator is opposed to the end surface of the end surface portion. A thermal fuse is held by a portion of a resin member located in an opening of the stator and is melted and disconnected to cut supply of an electric current to the solenoid coil when a temperature of the thermal fuse is equal to or higher than a predetermined temperature. The resin member has a recess that is formed in a predetermined position of a surface of the resin member, which is adjacent to the thermal fuse.

First claim

What is claimed is:

1. An electromagnetic clutch comprising:
an electromagnetic coil that generates an electromagnetic attractive force when the electromagnetic coil is energized;
a rotor that is rotated about a rotational center axis when the rotor receives a rotational drive force from a drive source, wherein the rotor includes a first surface and a second surface, which are spaced away from each other in an axial direction of the rotational center axis, and the first surface and the second surface extend in a direction perpendicular to the axial direction;
an armature that is connectable with a rotatable shaft of a driven-side device, wherein the armature is attracted and attached to the first surface of the rotor by the electromagnetic attractive force when the electromagnetic coil is energized, and the armature is detached from the first surface of the rotor when the electromagnetic coil is not energized;
a stator that is opposed to the second surface of the rotor in the axial direction and forms a space between the stator and the second surface, wherein the stator has an opening on a side wherein the second surface is located, and the stator receives the electromagnetic coil in an inside space of the stator, which is communicated with the opening;
a resin member that closes the opening of the stator and seals the electromagnetic coil in the inside space of the stator; and
a thermal fuse that is held by a portion of the resin member located in the opening of the stator and is melted and disconnected to cut supply of an electric current to the electromagnetic coil when a temperature of the thermal fuse is equal to or higher than a predetermined temperature; and
the resin member has a recess that is formed in a predetermined position of a surface of the resin member, which is adjacent to the thermal fuse and is located on the side where the second surface is placed.

2. The electromagnetic clutch according to claim 1 , wherein the recess is formed in the surface of the resin member on each of one side and another side of the thermal fuse.

3. The electromagnetic clutch according to claim 1 , wherein:
the rotor has a slit, which extends through the rotor between the first surface and the second surface; and
with respect to an imaginary line, which connects between the slit and a center of a cross section of the thermal fuse by a shortest distance in an imaginary plane that is perpendicular to an axial direction of the thermal fuse, an outer edge portion of the recess is placed on a side of the imaginary line, which is opposite from the second surface.

4. The electromagnetic clutch according to claim 1 , wherein the thermal fuse is covered by a thin film portion of the resin member, which is placed between the recess and the thermal fuse.

5. The electromagnetic clutch according to claim 4 , wherein:
the thermal fuse includes a fusible material, which is melted and disconnected by heat, and a case, which receives the fusible material;
the case has an exposed portion, which is exposed from the thin film portion; and
the exposed portion of the case is covered with a coating film, and a value of absorbance of the coating film is higher than a value of absorbance of the case in a wavelength range of a radiant heat.

6. The electromagnetic clutch according to claim 1 , wherein at least one half of a circumferential extent of an outer peripheral surface of the thermal fuse is exposed from the resin member and forms an exposed portion of the thermal fuse.

7. The electromagnetic clutch according to claim 6 , wherein:
the thermal fuse includes a fusible material, which is melted and disconnected by heat, and a case, which receives the fusible material;
the case has an exposed portion, which is exposed from the resin member; and
the exposed portion of the case is covered with a coating film, and a value of absorbance of the coating film is higher than a value of absorbance of the case in a wavelength range of a radiant heat.

8. The electromagnetic clutch according to claim 1 , wherein the recess is recessed at least to a depth that corresponds to a location of a center of a cross section of the thermal fuse in an imaginary plane that is perpendicular to an axial direction of the thermal fuse.

9. The electromagnetic clutch according to claim 1 , comprising a support portion that is placed on a side of the thermal fuse, which is opposite from the second surface, wherein:
the support portion includes a first support arm and a second support arm, which project toward the thermal fuse;
the first support arm and the second support arm are resiliently deformable away from each other;
a portion of an outer peripheral surface of the thermal fuse is received in a receiving groove formed between the first support arm and the second support arm;
a cross-sectional area of the receiving groove is tapered in a direction away from the thermal fuse; and
a space is formed between a bottom portion of the receiving groove and the outer peripheral surface of the thermal fuse.

10. The electromagnetic clutch according to claim 9 , wherein at least one half of a circumferential extent of the outer peripheral surface of the thermal fuse is exposed from the receiving groove.

11. The electromagnetic clutch according to claim 1 , further comprising a support portion that is placed on a side of the thermal fuse, which is opposite from the second surface, wherein the support portion is made of elastomer and supports a portion of an outer peripheral surface of the thermal fuse.

12. A manufacturing method for the electromagnetic clutch of claim 1 , comprising:
placing the electromagnetic coil and the thermal fuse configured into a cylindrical form in the inside space of the stator;
placing a die over the thermal fuse and contacting a recessed surface of the die to an outer peripheral surface of the thermal fuse, wherein the recessed surface is recessed from a projection of the die to form an arcuately curved surface that has a radius of curvature, which is equal to or larger than a radius of curvature of the outer peripheral surface of the thermal fuse; and
filling a resin material in a molten state into the inside space of the stator to mold the resin member having the recess formed by the projection of the die.

13. The manufacturing method according to claim 12 , wherein the contacting of the recessed surface of the die to the outer peripheral surface of the thermal fuse includes contacting the recessed surface of the die, which has the radius of curvature larger than the radius of curvature of the outer peripheral surface of the thermal fuse, to the outer peripheral surface of the thermal fuse.

Assignees

• Denso Corp

Inventors

• Fukumura Yoshinori
• Tabuchi Yasuo

Classifications

• F16D27/112 Primary

  with flat friction surfaces, e.g. discs · CPC title

• F16D2250/00

  Manufacturing; Assembly · CPC title

• F16D9/02

  by thermal means, e.g. melting member · CPC title

• F16D2300/02

  Overheat protection, i.e. means for protection against overheating · CPC title

• F16D27/14

  Details · CPC title