Magnetic viscous fluid damper and manufacturing method of coil assembly used therefor
A magnetic viscous fluid damper includes: a cylinder; a piston that is slidably interposed within the cylinder; two fluid chambers that are partitioned by the piston; a hollow rod that is coupled to the piston; an electromagnetic coil that is formed with a magnet wire wound around the piston; two lead wires that extend from both ends of the magnet wire; and a coil assembly in which the electromagnetic coil and the two lead wires are embedded in a mold resin. The piston includes a hollow first core coupled to the rod and a second core that sandwiches the coil assembly with the first core. The two lead wires are passed through the inside of the first core and are electrically continuous with an electric wire passed through the inside of the rod.
1. A magnetic viscous fluid damper using a magnetic viscous fluid, comprising:
a cylinder that the magnetic viscous fluid is sealed in;
a piston that is slidably disposed within the cylinder;
two fluid chambers that are partitioned by the piston;
a hollow rod that is coupled to the piston and protrudes to an outside of the cylinder;
an electromagnetic coil having a magnet wire wound around the piston;
two lead wires that extend from both ends of the magnet wire; and
a coil assembly in which the electromagnetic coil and the two lead wires are embedded in a mold resin,
wherein the piston includes a hollow first core coupled to the rod and a second core that sandwiches the coil assembly with the first core,
wherein the two lead wires are passed through an inside of the first core and are electrically continuous with an electric wire passed through an inside of the rod,
wherein the coil assembly includes a primary mold member that is molded such that the two lead wires are embedded, and the electromagnetic coil is wound around an outer circumference of the primary mold member and a secondary mold member that is molded such that the electromagnetic coil is embedded between the primary mold member and the secondary mold member after the primary mold member is assembled on the first core and the first core is set in molds, and
wherein a flow path via which the magnetic viscous fluid flows between the two fluid chambers is defined by an outer circumferential surface of the secondary mold member.
2. The magnetic viscous fluid damper according to claim 1 , wherein:
the coil assembly includes a ring-shaped bobbin portion around which the electromagnetic coil is wound, a plug portion that is inserted into an inside of the first core and a bridge portion that couples the bobbin portion and the plug portion together; and
the two lead wires extend over the bobbin portion, the bridge portion and the plug portion.
3. The magnetic viscous fluid damper according to claim 2 , wherein:
the first core includes a bridge holding concave portion that holds the bridge portion and two semi-cylindrical shaft portions that sandwich the bridge holding concave portion and extend; and
the second core includes a cylindrical yoke portion that is coupled to an outer circumference of the two semi-cylindrical shaft portions and is provided side by side with the electromagnetic coil along an axial direction of the piston.
4. The magnetic viscous fluid damper according to claim 3 , wherein:
the piston includes a male screw that is formed in the outer circumference of the two semi-cylindrical shaft portions and a female screw that is formed in an inner circumference of the yoke portion and is screwed to the male screw.
5. The magnetic viscous fluid damper according to claim 3 , wherein:
the second core is fitted to the outer circumference of the two semi-cylindrical shaft portions;
the piston includes a male screw that is formed in the outer circumference of the two semi-cylindrical shaft portions and a nut that is screwed to the male screw; and
the coil assembly and the second core are interposed between the nut and the first core.
6. The magnetic viscous fluid damper according to claim 3 , wherein:
the second core is fitted to the outer circumference of the two semi-cylindrical shaft portions;
the piston includes a ring-shaped groove that is formed in the outer circumference of the two semi-cylindrical shaft portions and a stopper that is fitted to the ring-shaped groove; and
the coil assembly and the second core are interposed between the stopper and the first core.
7. The magnetic viscous fluid damper according to claim 3 , wherein:
the second core is fitted to the outer circumference of the two semi-cylindrical shaft portions;
the piston includes a female screw that is formed in the inner circumference of the two semi-cylindrical shaft portions and a bolt that is screwed to the female screw; and
the coil assembly and the second core are interposed between the bolt and the first core.
8. A manufacturing method of the coil assembly used in the magnetic viscous fluid damper according to claim 1 , the method comprising:
a primary molding step of molding a primary mold member in which the two lead wires are embedded;
a coil winding step of winding the magnet wire around an outer circumference of the primary mold member to form the electromagnetic coil; and
a secondary molding step of molding a secondary mold member such that the electromagnetic coil is embedded between the primary mold member and the secondary mold member.
9. The manufacturing method of the coil assembly according to claim 8 , wherein:
in the secondary molding step, the first core to which the primary mold member is assembled is put into a mold, and the secondary mold member is molded.
10. The manufacturing method of the coil assembly according to claim 8 , wherein:
in the secondary molding step, the first core and the second core to which the primary mold member is assembled are put into a mold, and the secondary mold member is molded.