BALANCE RING FOR A VEHICULAR ELECTRIC MACHINE
An electric machine for deployment in a vehicle, with the electric machine having a housing is provided. The electric machine comprises a stator assembly coupled to the housing, and a rotor assembly disposed within the stator assembly and configured to rotate relative thereto. A balance ring is coupled to an end of the rotor assembly and is configured to rotate therewith. The balance ring comprises an annular base layer having a first planar surface, and an annular magnetic shielding layer having a second planar surface clad to the first planar surface
1 . An electric machine for deployment in a vehicle, the electric machine having a housing, the electric machine comprising:
a stator assembly coupled to the housing;
a rotor assembly disposed within the stator assembly and configured to rotate relative thereto; and
a balance ring coupled to an end of the rotor assembly and configured to rotate therewith, the balance ring comprising:
an annular base layer having a first planar surface; and
an annular magnetic shielding layer having a second planar surface clad to the first planar surface.
2 . An electric machine according to claim 1 , wherein the annular magnetic shielding layer further comprises a third planar surface coupled adjacent the end of the rotor assembly.
3 . An electric machine according to claim 1 , wherein the annular magnetic shielding layer comprises a material selected from a group consisting of titanium, aluminum, stainless steel, copper, magnesium, chromium, zinc, manganese, molybdenum, and alloys thereof.
4 . An electric machine according to claim 1 , wherein the annular base layer comprises carbon steel.
5 . An electric machine according to claim 1 , wherein the annular magnetic shielding layer has a magnetic permeability of from about 1 to about 2 times the magnetic permeability of a vacuum.
6 . An electric machine according to claim 5 , wherein the annular magnetic shielding layer has a magnetic permeability of from about 1 to about 1.2 times the magnetic permeability of a vacuum.
7 . An electric machine according to claim 1 , wherein the annular base layer has a thickness of from about 1 mm to about 20 mm.
8 . An electric machine according to claim 1 , wherein the annular magnetic shielding layer has a thickness of from about 0.1 mm to about 10 mm.
9 . A balance ring comprising:
a first annular layer comprised of a high strength material, the first annular layer having a first planar surface; and
a second annular layer comprised of a low magnetic permeability material, the second annular layer having a second planar surface clad to the first planar surface.
10 . A balance ring according to claim 9 , wherein the second annular layer has a composition selected from a group consisting of titanium, aluminum, stainless steel, copper, magnesium, chromium, zinc, manganese, molybdenum, and alloys thereof.
11 . A balance ring according to claim 9 , wherein the first annular layer comprises carbon steel.
12 . A balance ring according to claim 9 , wherein the second annular layer has a magnetic permeability of from about 1 to about 2 times the magnetic permeability of a vacuum.
13 . A balance ring according to claim 12 , wherein the second annular layer has a magnetic permeability of from about 1 to about 1.2 times the magnetic permeability of a vacuum.
14 . A method for fabricating a balance ring for a vehicular electric machine, the method comprising the steps of:
providing a first metal layer having a first planar surface;
providing a second metal layer having a second planar surface;
cladding the second planar surface to the first planar surface to form a composite structure; and
removing a portion of the composite structure to form an annular ring.
15 . A method according to claim 14 , wherein the step of providing a second metal layer comprises providing a second metal layer comprised of a low magnetic permeability material.
16 . A method according to claim 15 , wherein the step of providing a second metal layer comprised of a low magnetic permeability material comprises providing a second metal layer comprised of a material having a magnetic permeability of from about 1 to about 2 times the magnetic permeability of a vacuum.
17 . A method according to claim 14 , wherein the step of removing comprises removing by stamping.
18 . A method according to claim 15 , wherein the step of providing a second metal layer comprised of a material having a low magnetic permeability comprises providing a second metal layer comprised of aluminum.
19 . A method according to claim 14 , further comprising the step of machining the annular ring to form the balance ring.
20 . A method according to claim 19 , wherein the vehicular electric machine further comprises a rotor having an end, and further comprising the step of mounting the balance ring on the end of the rotor.