Compact halbach electrical generator for integration in a solid body

1. An electric generator, said generator comprising:

a rotor with permanent magnets, configured for rotating about a rotation axis;

at least one magnetic yoke with at least two arms extending axially inside or outside of the rotor so as to be adjacent to the radial inner or outer side, respectively, of the rotor;

wherein the permanent magnets are arranged according to a Halbach array so as to maximize the magnetic field on the radial side of the rotor adjacent to the arms of the at least one yoke;

wherein the generator comprises a wall forming a cavity housing the rotor, the arms of the at least one yoke being out of the cavity; and

wherein the wall forming the cavity is made of solid material, the arms of the at least one yoke extending inside the solid material.

2. The electric generator according to claim 1 , wherein the permanent magnets are arranged so as to show magnetic orientations which successively rotate by 90° along the circumference of the rotor.

3. The electric generator according to claim 1 , wherein the generator comprises at least one coil arranged distant of the arms of the at least one yoke, so as to be in a variable magnetic field produced by a rotation of the rotor relative to the at least one yoke.

4. The electric generator according to claim 1 , wherein each of the at least one yoke further comprises at least one bridge interconnecting diametrically opposed arms of the yoke.

5. The electric generator according to claim 4 , wherein the at least one yoke comprises a first yoke and a second yoke, wherein the arms of the first yoke are angularly offset relative to the arms of the second yoke.

6. The electric generator according to claim 5 , wherein the at least one coil is sandwiched between the bridges of the first and second yokes.

7. The electric generator according to claim 1 , wherein the material of the wall is non-ferromagnetic.

8. The electric generator of claim 7 , wherein the non-ferromagnetic material comprises at least one of austenitic stainless steel, aluminium, copper, brass, thermosetting plastic or thermoplastic.

9. The electric generator according to claim 1 , further comprising a turbine wheel mechanically coupled to the rotor.

10. The electric generator according to claim 9 , further comprising a shaft supporting the rotor and the turbine wheel, and bearings at each end of the shaft.

11. The electric generator according to claim 9 , wherein the turbine wheel is located axially on the rotor and surrounds the rotor.

12. The electric generator according to claim 9 , wherein the turbine wheel is an axial turbine wheel comprising blades extending radially and configured for converting an annular axial flow through the blades into a rotational movement of the turbine wheel and the rotor.

13. The electric generator according to claim 1 , wherein the cavity houses a turbine wheel.

14. The electric generator according to claim 1 , wherein at least one of the arms of the at least one magnetic yoke comprises at least one slit extending lengthwise.

15. A valve for gas cylinder, said valve comprising:

a body with an inlet, an outlet and a passage interconnecting the inlet and outlet;

a flow control device mounted on the body and controlling the flow of gas in the passage;

an electric generator with a turbine wheel located in the passage, configured for outputting electric power when the gas flow in the passage rotates the turbine wheel;

wherein the electric generator comprises:

a rotor with permanent magnets, configured for rotating about a rotation axis;

at least one magnetic yoke with at least two arms extending axially inside or outside of the rotor so as to be adjacent to the radial inner or outer side, respectively, of the rotor;

wherein the permanent magnets are arranged according to an Halbach array so as to maximize the magnetic field on the radial side of the rotor adjacent to the arms of the at least one yoke; and

wherein the generator comprises a wall forming a cavity housing the rotor, the arms of the at least one yoke being out of the cavity, the wall being formed by the material of the body.

16. A conduit with a wall delimiting a passage for a fluid and with an electric generator with a turbine wheel located in the passage so as to be driven when the fluid flows, wherein the electric generator comprises:

a rotor with permanent magnets, configured for rotating about a rotation axis;

at least one magnetic yoke with at least two arms extending axially inside or outside of the rotor so as to be adjacent to the radial inner or outer side, respectively, of the rotor;

wherein the permanent magnets are arranged according to an Halbach array so as to maximize the magnetic field on the radial side of the rotor adjacent to the arms of the at least one yoke; and

wherein the electric generator further comprises a wall forming a cavity housing the rotor, the arms of the at least one yoke being out of the cavity, the wall being formed by the material of the body.

17. An electric generator, said generator comprising:

a rotor with permanent magnets, configured for rotating about a rotation axis;

at least one magnetic yoke with at least two arms extending axially inside or outside of the rotor so as to be adjacent to the radial inner or outer side, respectively, of the rotor;

wherein the permanent magnets are arranged according to a Halbach array so as to maximize the magnetic field on the radial side of the rotor adjacent to the arms of the at least one yoke; and

wherein at least one of the at least two arms of the at least one magnetic yoke comprises at least one slit extending lengthwise.