A reactor includes a laminated core formed by laminating soft-magnetic ribbons in a lamination direction. The laminated core has a gap formed across a magnetic path direction in the laminated core. The laminated core also has a flat facing surface that faces the gap and a pair of flat side surfaces that are respectively on opposite sides of the facing surface in the lamination direction. The laminated core further has a pair of first corner curved surfaces that are formed between the facing surface and the pair of side surfaces. Each of the first corner curved surfaces has a width in the lamination direction greater than the thickness of each of the soft-magnetic ribbons. For each of the first corner curved surfaces, a length of the first corner curved surface in the magnetic path direction is greater than the width of the first corner curved surface in the lamination direction.
1. A reactor comprising:
a laminated core formed of a plurality of soft-magnetic ribbons that are laminated in a lamination direction; and
a coil wound around the laminated core,
wherein
the laminated core has a gap that is formed in the laminated core across a magnetic path direction along which magnetic flux flows in the laminated core,
the laminated core also has a flat facing surface that faces the gap and a pair of flat side surfaces that are respectively on opposite sides of the facing surface in the lamination direction,
the laminated core further has a pair of first corner curved surfaces that are respectively formed between the facing surface and one of the side surfaces and between the facing surface and the other side surface,
each of the first corner curved surfaces has a width in the lamination direction greater than a thickness of each of the soft-magnetic ribbons forming the laminated core,
for each of the first corner curved surfaces, a length of the first corner curved surface in the magnetic path direction is greater than the width of the first corner curved surface in the lamination direction,
the laminated core has a substantially annular shape such that the lamination direction coincides with an inside-outside direction of the laminated core,
the first corner curved surfaces comprise an inner first corner curved surface that is on the inner side of the facing surface and an outer first corner curved surface that is on the outer side of the facing surface,
the inner first corner curved surface has a different shape from the outer first corner curved surface, and
the length of the inner first corner curved surface in the magnetic path direction is greater than the length of the outer first corner curved surface in the magnetic path direction,
when viewed along a height direction perpendicular to both the lamination direction and the magnetic path direction, each of the first corner curved surfaces has a shape that is determined by the following Equation (1) on an x-y coordinate plane:
y
=
gab
x
+
W
-
h
g
+
g
(
1
-
a
)
(
1
)
where the x-y coordinate plane has its x-axis set to a line that extends in the lamination direction through a center of the gap and its y-axis set to a line that extends in the magnetic path direction and is equidistant from the side surfaces of the laminated core, g is half of the size of the gap, h is half of the distance between the side surfaces of the laminated core, W is the width of the first corner curved surface in the lamination direction, a is a positive constant, b is a positive constant greater than 1, and (h-W)<x<h.
2. The reactor as set forth in claim 1 , wherein the laminated core also has a pair of flat end surfaces that are respectively on opposite sides of the facing surface in a height direction of the laminated core, the height direction being perpendicular to both the lamination direction and the magnetic path direction,
the laminated core further has a pair of second corner curved surfaces that are respectively formed between the facing surface and one of the end surfaces and between the facing surface and the other end surface, and
for each of the second corner curved surfaces, a length of the second corner curved surface in the magnetic path direction is greater than a width of the second corner curved surface in the height direction.
3. The reactor as set forth in claim 1 , wherein for each of the first corner curved surfaces, those soft-magnetic ribbons which together constitute the first corner curved surface are laminated so that distal ends of those soft-magnetic ribbons are offset from one another in the magnetic path direction.