In-wheel motor and electrically driven vehicle

1. An in-wheel motor installed inside a wheel disk of a wheel to rotationally drive the wheel around a shaft of the wheel by way of applying a current thereto, the in-wheel motor comprising:

a coreless cylindrical coil body to which a lead wire for applying a current is connected, the shaft being inserted in an inner circumferential side of the coil body, the coil body supported at an inner car body end by a disk-shaped coil body support member that is fixed to the shaft;

a cylindrical outer yoke that is disposed on an outer circumferential side of the coil body, and an outer wheel-disk end thereof is fixed to the wheel disk, an inner car body end of the outer yoke further being fixed to a cover disk that covers an inner car body side of the in-wheel motor and is journalled for rotation about the shaft;

a cylindrical inner yoke that is disposed on an inner circumferential side of the coil body and has an outer wheel-disk end thereof attached to the outer wheel-disk end of the outer yoke, an inner car body end of the inner yoke further being fixed to a support disk rotatable around the shaft, wherein the outer yoke, the inner yoke, the support disk and the cover disk together rotate as a rotor around the coil body and provide a hermetic seal around the coil body so as to prevent water and foreign matter from reaching the coil body;

a magnet that is fixed to rotate with the rotor immediately adjacent a circumferential face of the coil body;

a brake disk that is fixed to an inner circumferential side of the inner yoke; and

a caliper that is provided on the inner circumferential side of the inner yoke to brake the brake disk.

2. The in-wheel motor according to claim 1 , wherein the outer wheel-disk end of the outer yoke includes a bent circumferential side edge thereof fixed to the outer wheel-disk end of the inner yoke and to the wheel disk.

3. The in-wheel motor according to claim 1 , wherein the caliper is fixed to a caliper support disk which is fixed to the shaft at a location inside of the wheel disk, and the caliper support disk extends radially outward farther than a central vent hole formed in the wheel disk such that air may circulate to the brake disk.

4. An electrically driven vehicle comprising at least one in-wheel motor according to claim 1 .

5. The in-wheel motor according to claim 1 , wherein the magnet is fixed on an inner circumferential face of the outer yoke.

6. The in-wheel motor according to claim 1 , wherein the magnet is fixed on an outer circumferential face of the inner yoke.

7. A motor comprising:

a coreless cylindrical coil body including two ring-shaped ends, a hollow cylindrical wall defining the two ring-shaped ends and configured to encircle an external wheel shaft externally extending into the coreless cylindrical coil body, and a lead wire for supplying current to the coreless cylindrical coil body;

a coil body support member located at one of the two ring-shaped ends of the coreless cylindrical coil body, configured to be fixed to the external wheel shaft, and fixedly supporting the coreless cylindrical coil body;

a cylindrical outer yoke including a cylindrical wall having an inner and an outer cylindrical surface, loosely fit over the coreless cylindrical coil body, and configured to be fixed to an external wheel disk and to rotate together with the external wheel disk relatively to the external wheel shaft;

a cylindrical inner yoke including a cylindrical wall having an inner and an outer cylindrical surface, loosely fit in the coreless cylindrical coil body, and configured to rotate around the external wheel shaft;

a magnet fixed to rotate around the external wheel shaft and immediately adjacent to and directly facing the coreless cylindrical coil body;

a brake disk that is fixed to an inner circumferential side of the inner yoke; and

a caliper that is provided on the inner circumferential side of the inner yoke to brake the brake disk.

8. The in-wheel motor according to claim 7 , wherein the magnet is fixed on the inner cylindrical surface of the outer yoke and directly faces an outer cylindrical wall of the coreless cylindrical coil body.

9. The in-wheel motor according to claim 7 , wherein the magnet is fixed on the outer cylindrical surface of the inner yoke and directly faces the hollow cylindrical wall of the coreless cylindrical coil body.

10. An electrically driven vehicle comprising at least one in-wheel motor according to claim 7 .