1. A marine propeller, comprising:
a propeller hub;
a plurality of propeller blades each having a leading blade face and a trailing blade face carried by said propeller hub; and
a reverse thrust cup provided in said trailing blade face of each of said plurality of propeller blades.
2. The marine propeller of claim 1 wherein said reverse thrust cup comprises a cup lip provided in said trailing blade face.
3. The marine propeller of claim 2 wherein said cup lip comprises a radial lip portion extending generally radially with respect to said propeller hub and an outer lip portion extending from said radial lip portion.
4. The marine propeller of claim 3 further comprising a generally convex cup surface extending from said cup lip.
5. The marine propeller of claim 3 further comprising a trailing cup edge extending from said outer lip portion.
6. The marine propeller of claim 3 further comprising a water flow path between said radial lip portion of said cup lip and said propeller hub.
7. The marine propeller of claim 6 wherein said radial lip portion comprises a tapered radial lip portion.
8. The marine propeller of claim 6 wherein said radial lip portion comprises a truncated radial lip portion.
9. A marine propeller, comprising:
a propeller hub;
a plurality of propeller blades each having a leading blade face, a trailing blade face, a leading blade edge, an outer blade edge and a trailing blade edge carried by said propeller hub; and
a reverse thrust cup provided in said trailing blade face of each of said plurality of propeller blades and bounded by said outer blade edge and said trailing blade edge.
10. The marine propeller of claim 9 wherein said reverse thrust cup comprises a cup lip provided in said trailing blade face and wherein said reverse thrust cup is further bounded by said cup lip.
11. The marine propeller of claim 10 further comprising a generally convex cup surface extending from said cup lip.
12. The marine propeller of claim 10 wherein said cup lip comprises a radial lip portion extending generally radially with respect to said propeller hub and an outer lip portion extending from said radial lip portion.
13. The marine propeller of claim 12 further comprising a trailing cup edge extending from said outer lip portion.
14. The marine propeller of claim 12 further comprising a water flow path between said radial lip portion of said cup lip and said propeller hub.
15. The marine propeller of claim 14 wherein said radial lip portion comprises a tapered radial lip portion.
16. The marine propeller of claim 14 wherein said radial lip portion comprises a truncated radial lip portion.
17. A marine propeller, comprising:
a propeller hub;
a plurality of propeller blades each having a leading blade face, a trailing blade face, a leading blade edge, an outer blade edge and a trailing blade edge carried by said propeller hub; and
a reverse thrust cup provided in said trailing blade face of each of said plurality of propeller blades; and
wherein said reverse thrust cup includes a cup lip having a radial lip portion generally parallel and spaced-apart with respect to said leading blade edge and an outer lip portion generally spaced-apart with respect to the outer blade edge, and a cup lip bounded by said cup lip, said outer blade edge and said trailing blade edge.
18. The marine propeller of claim 17 further comprising a water flow path between said radial lip portion of said cup lip and said propeller hub.
19. The marine propeller of claim 18 wherein said radial lip portion comprises a tapered radial lip portion.
20. The marine propeller of claim 18 wherein said radial lip portion comprises a truncated radial lip portion.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An inductive power transmitter for transmitting electrical power to a device by electromagnetic induction, the transmitter being configured to receive power conductively by way of a current via an electrical conduit from an external power source, the transmitter comprising:
a field generator configured to generate a fluctuating electromagnetic field having a fundamental frequency; and
at least one impedance element connected along an electrical path of the transmitter configured to carry said current, the impedance element or a combination of the impedance elements has a high enough impedance at the fundamental frequency such that, in use, electromagnetic noise experienced at the power source is substantially suppressed, such noise arising from coupling between the electromagnetic field and a circuit having said path and linking the power source to the transmitter.
2. A transmitter as claimed in claim 1, wherein:
said fundamental frequency is a first fundamental frequency;
said current has a second fundamental frequency different from said first fundamental frequency; and
the impedance element or the combination of the impedance elements has a low enough impedance at the second fundamental frequency such that said power is predominantly conveyed to the field generator without loss in that impedance.
3. A transmitter as claimed in claim 1, wherein said current is an AC current.
4. A transmitter as claimed in claim 1, wherein said power source is a mains power source.
5. A transmitter as claimed in claim 1, wherein the element comprises an inductor.
6. A transmitter as claimed in claim 1, further comprising a mains cable, wherein the impedance element or at least one of combination of impedance elements is part of the mains cable.
7. A transmitter as claimed in claim 6, wherein the transmitter has a main body, the mains cable extending externally therefrom when in use, and wherein the impedance element or at least one of the combination of impedance elements is located within the main body.
8. A transmitter as claimed in claim 6, wherein the mains cable is detachable from a part of the transmitter.
9. A transmitter as claimed in claim 1, configured such that the impedance element or at least one of the combination of impedance elements is shielded from said electromagnetic field.
10. A transmitter as claimed in claim 1, comprising two of the impedance elements, and wherein:
said current is carried along first and second connections; and
said elements are located along different said connections from one another or along the same connection as one another.
11. A transmitter as claimed in claim 1, comprising two of the impedance elements, and wherein:
the impedance elements each comprise an inductor; and
the inductors are configured to have opposite orientations relative to one another such that coupling from the field generator by way of the electromagnetic field to one said inductor cancels out such coupling to the other said inductor.
12. A transmitter as claimed in claim 6, wherein the inductors are arranged such that there is substantially no mutual coupling between them.
13. A transmitter as claimed in claim 12, further comprising a filter located between the mains cable and the field generating means and configured to substantially block frequency components at the fundamental frequency of the electromagnetic field.
14. A transmitter as claimed in claim 1, wherein the field generator comprises a coil and driving means operable to drive a fluctuating current through the coil, and wherein both ends of the coil are decoupled from the driving means such that in use a voltage level at each end of the coil fluctuates with time.
15. An electrical conduit configured to convey power conductively by way of a current from a power source to a field generator of an inductive power transmitter, the field generator being operable to generate a fluctuating electromagnetic field having a fundamental frequency for transmitting electrical power to a device by electromagnetic induction, the conduit comprising:
at least one impedance element connected along an electrical path of the conduit configured to carry said current, the impedance element or a combination of the impedance elements has a high enough impedance at the fundamental frequency such that, in use, electromagnetic noise experienced at the power source is substantially suppressed, such noise arising from coupling between the electromagnetic field and a circuit having said path and linking the power source to the transmitter.
16. A conduit as claimed in claim 15, wherein:
said fundamental frequency is a first fundamental frequency;
said current has a second fundamental frequency different from said first fundamental frequency; and
the impedance element or the combination of the impedance elements has a low enough impedance at the second fundamental frequency such that said power is predominantly conveyed to the field generator without loss in that impedance.
17. A conduit as claimed in claim 15, wherein the conduit is a mains cable.
18. Equipment for use in the vicinity of an inductive power transmitter, the transmitter being for transmitting electrical power to a device by electromagnetic induction and comprising a field generator configured to generate a fluctuating electromagnetic field having a fundamental frequency, the equipment being configured to receive power conductively by way of a current via an electrical conduit from an external power source, the equipment comprising:
at least one impedance element connected along an electrical path of the equipment configured to carry said current, the impedance element or a combination of the impedance elements having a high enough impedance at the fundamental frequency such that, in use, electromagnetic noise experienced at the power source is substantially suppressed, such noise arising from coupling between the electromagnetic field and a circuit having said path and linking the power source to the equipment.
19. A method of configuring an inductive power transmitter, the transmitter being for transmitting electrical power to a device by electromagnetic induction and being configured to receive power conductively via an electrical conduit by way of a current from an external power source, the transmitter comprising a field generator configured to generate a fluctuating electromagnetic field having a fundamental frequency, the method comprising:
connecting at least one impedance element along an electrical path of the transmitter configured to carry said current, the impedance element or a combination of the impedance elements having a high enough impedance at the fundamental frequency such that, in use, electromagnetic noise experienced at the power source is substantially suppressed, such noise arising from coupling between the electromagnetic field and a circuit having said path and linking the power source to the transmitter.