A drone for triggering naval mines, which drone includes a drive having an electric motor for locomotion in the water, wherein the electric motor can be used additionally to trigger the naval mines during operation of the drone, by an external magnetic field formed by the operation of the electric motor. The electric motor includes a stationary stator and a rotor, which is mounted for rotation relative to the stator. The stator includes at least one magnetic and/or electromagnetic element for forming an excitation field. The rotor includes at least one armature winding, which electromagnetically interacts with the excitation field during operation of the electric motor, whereby a superordinate magnetic field is formed. The external magnetic field formed outside of the electric motor during operation is in the form of a constant magnetic field.

A drone for triggering naval mines, which drone includes a drive having an electric motor for locomotion in the water, wherein the electric motor can be used additionally to trigger the naval mines during operation of the drone, by an external magnetic field formed by the operation of the electric motor. The electric motor includes a stationary stator and a rotor, which is mounted for rotation relative to the stator. The stator includes at least one magnetic and/or electromagnetic element for forming an excitation field. The rotor includes at least one armature winding, which electromagnetically interacts with the excitation field during operation of the electric motor, whereby a superordinate magnetic field is formed. The external magnetic field formed outside of the electric motor during operation is in the form of a constant magnetic field.

A motor includes a rotary shaft, an armature part, a frame including a tubular portion surrounding the armature part, and a plurality of magnets. The tubular portion is formed of a magnetic body. The tubular portion includes a plurality of flat parts and a plurality of curved parts. Each of the plurality of flat parts and each of the plurality of curved parts being alternately arranged in a peripheral direction. On an inner surface of the tubular portion in each of the plurality of curved parts, a plurality of magnetic poles are provided. A magnetic gap is provided in a radial direction, the magnetic gap being formed by the inner surface of the tubular portion in each of the plurality of flat parts and the armature part.

A motor includes a rotary shaft, an armature part, a frame including a tubular portion surrounding the armature part, and a plurality of magnets. The tubular portion is formed of a magnetic body. The tubular portion includes a plurality of flat parts and a plurality of curved parts. Each of the plurality of flat parts and each of the plurality of curved parts being alternately arranged in a peripheral direction. On an inner surface of the tubular portion in each of the plurality of curved parts, a plurality of magnetic poles are provided. A magnetic gap is provided in a radial direction, the magnetic gap being formed by the inner surface of the tubular portion in each of the plurality of flat parts and the armature part.

An electric motor includes a cylindrical rotor with a plurality of wires parallel to the cylindrical axis nested between two cylinders of magnets in a stator. The cylinders of magnets may be a solid magnet, a plurality of bar magnets, a plurality of coils generating magnetic fields or other magnets or generated magnetic fields. A nested electric motor includes a first electric motor additionally including a first shaft, which first electric motor nests within the hollow center of a second larger electric motor additionally including a second shaft. The first shaft is coaxial with the second shaft.

Provided is a ferrite sintered magnet including a ferrite phase having a magnetoplumbite-type crystal structure. x, y, and m satisfy the following Equations (1), (2), and (3) when composition of the ferrite sintered magnet is represented by R.sub.1-xA.sub.xFe.sub.m-yCo.sub.y, where R denotes at least one kind of element selected from rare earth elements including Y and A denotes Ca or Ca and elements including at least one kind selected from Sr or Ba. The content of B in the ferrite sintered magnet is from 0.1% to 0.6% by mass in terms of B.sub.2O.sub.3.
0.2≤x≤0.8  (1)
0.1≤y≤0.65  (2)
3≤m<14  (3)

A fluid pump includes an electric motor having an armature with a commutator and a motor frame which supports a pair of permanent magnets which are located radially outward from the armature. The motor frame has a support stem extending axially in a direction away from the commutator. A pump section is rotationally coupled to the electric motor and pumps the fluid. First and second motor brushes deliver electricity to the commutator and are urged into electrical contact with the commutator by a first and second springs. The first and second springs are mechanically grounded to a brush spring retainer fixed to the motor frame. The brush spring retainer includes a central portion having an opening within which the support stem is received in an interference fit. A support arm extends from the central portion such that the first and second springs are mechanically grounded to the support arm.

A fluid pump includes an electric motor having an armature with a commutator and a motor frame which supports a pair of permanent magnets which are located radially outward from the armature. The motor frame has a support stem extending axially in a direction away from the commutator. A pump section is rotationally coupled to the electric motor and pumps the fluid. First and second motor brushes deliver electricity to the commutator and are urged into electrical contact with the commutator by a first and second springs. The first and second springs are mechanically grounded to a brush spring retainer fixed to the motor frame. The brush spring retainer includes a central portion having an opening within which the support stem is received in an interference fit. A support arm extends from the central portion such that the first and second springs are mechanically grounded to the support arm.

A small DC motor includes a motor frame having a cylindrical portion, the cylindrical portion having a constant thickness and having a cross section in a shape that comprises four sides and connecting portions, each of the connecting portions connecting adjacent two of the four sides and being located inward from a corresponding corner in a quadrangle comprising the four sides; and a magnet having a circumferential surface on an inside thereof and having conformable contact with the motor frame on an outside thereof.

A small DC motor includes a motor frame having a cylindrical portion, the cylindrical portion having a constant thickness and having a cross section in a shape that comprises four sides and connecting portions, each of the connecting portions connecting adjacent two of the four sides and being located inward from a corresponding corner in a quadrangle comprising the four sides; and a magnet having a circumferential surface on an inside thereof and having conformable contact with the motor frame on an outside thereof.