1. A starter for starting an engine, the starter comprising:
a motor;
an output shaft driven by the motor, the output shaft having first helical splines that are formed on an outer periphery of the output shaft;
a pinion gear provided on the output shaft, the pinion gear having second helical splines that are formed on an inner periphery of the pinion gear to engage with the first helical splines of the output shaft; and
a shifter that shifts the pinion gear along the output shaft through the engagement between the first and second helical splines, thereby bringing the pinion gear into mesh with a ring gear of the engine to start the engine,
wherein
X<Y, where X is a clearance between a bottom of the first helical splines and a top of the second helical splines, and Y is a backlash between a flank of the first helical splines and a flank of the second helical splines.
2. The starter as set forth in claim 1, wherein the output shaft further includes a cylindrical portion that is formed adjacent to the first helical splines and to be located closer to the ring gear of the engine than the first helical splines,
the cylindrical portion has an outer diameter equal to a diameter of the bottom of the first helical splines, and
when the pinion gear is brought into mesh with the ring gear of the engine, only part of the second helical splines of the pinion gear engages with the first helical splines of the output shaft, with the remaining part of the second helical splines being supported on the cylindrical portion of the output shaft.
3. The starter as set forth in claim 1, wherein the pinion gear has a first end and a second end that is opposite to the first end in an axial direction of the pinion gear and to be located closer to the ring gear of the engine than the first end, and
the pinion gear also includes a collar portion that is formed at the second end of the pinion gear to occupy an entire circumference of the pinion gear and has an inner diameter equal to a diameter of the top of the second helical splines.
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 apparatus for the intended use of levitating a magnetic element, comprising:
a superconducting element capable of being placed in a superconducting state in accordance with a field cooling protocol and levitating the magnetic element;
a structure including a wall defining a first chamber in which the superconducting element is positioned, said first chamber thermally isolating the superconducting element from the wall; and
a cooling source thermally linked to the superconducting element,
wherein a gap is provided between said superconducting element and an inner surface of said wall of approximately 0.01 to 5 millimeters.
2. The apparatus according to claim 1, wherein the first chamber is evacuated or insulated to minimize thermal transfer to the wall and provide the desired thermal isolation.
3. The apparatus according to claim 2, wherein the first chamber is evacuated to a vacuum pressure of at least 10\u22123 torr.
4. The apparatus according to claim 1, wherein said superconducting element is a high temperature superconducting element.
5. The apparatus according to claim 1, wherein by way of the thermal link, said cooling source maintains the superconducting element at a temperature of between 4.2 to 130 Kelvin.
6. The apparatus according to claim 1, wherein the structure is a cryostat, said wall is the outer wall of the cryostat, a second chamber is positioned within the wall defining said first chamber, and said cooling source is a liquid cryogen in the second chamber.
7. The apparatus according to claim 1, wherein the cooling source is a liquid cryogen and further including a refrigerator capable of maintaining the superconducting element in a superconducting state, whereby the refrigerator serves as a primary cooling source and the liquid cryogen is a back-up or reserve cooling source.
8. An apparatus for the intended use of levitating a magnetic element, comprising:
a superconducting element capable of being placed in a superconducting state in accordance with a field cooling protocol;
a structure including a wall defining a chamber in which the superconducting element is positioned, said chamber thermally isolating the superconducting element from the wall; and
a refrigerator thermally linked to the superconducting element.
9. The apparatus according to claim 8, wherein the chamber is evacuated or insulated to minimize thermal transfer to said wall and provide the desired thermal isolation.
10. The apparatus according to claim 9, wherein the chamber is evacuated to a vacuum pressure of at least 10\u22123 torr.
11. The apparatus according to claim 8, wherein said superconducting element is a high temperature superconducting element.
12. The apparatus according to claim 8, wherein said refrigerator maintains the superconducting element at a temperature of between 4.2 to 130 Kelvin.
13. The apparatus according to claim 9, wherein the thermal linking is provided by a rod extending between the superconducting element and said refrigerator.
14. The apparatus according to claim 13, wherein said rod includes an engagement surface that is in contact with the entire area of an adjacent surface of the superconducting element to maximize thermal transfer.
15. The apparatus according to claim 8, wherein a gap is provided between the superconducting element and an inner surface of said wall of approximately 0.01 to 5 millimeters.
16. The apparatus according to claim 8, further including a second structure capable of holding a liquid cryogen in contact with the thermal link, whereby the second structure containing the liquid cryogen may serve as a backup or reserve cooling source for the superconducting element.
17. The apparatus according to claim 8, wherein the refrigerator is a closed-cycle refrigerator.
18. An apparatus for supplying a levitating force for a magnetic element, in a fluid-containing vessel, comprising:
a superconducting element capable of being placed in a superconducting state in accordance with a field cooling protocol and levitating the magnetic element;
a stable support structure for the vessel, said structure including a wall defining a first chamber in which the superconducting element is positioned, said first chamber being evacuated or insulated for thermally isolating the superconducting element from the wall;
a cooling source selected from the group consisting of: (a) a liquid cryogen held in second chamber in the structure; and (b) a refrigerator; and
a link for thermally linking said superconducting element to said cooling source.
19. The apparatus according to claim 18, wherein the link is a rod extending between the cooling source and the superconducting element, said rod having an engagement surface that is in contact with the entire area of an adjacent surface of the superconducting element to maximize thermal transfer.
20. The apparatus according to claim 18, wherein the refrigerator is a closed-cycle refrigerator.
21. The apparatus according to claim 18, including both the second chamber holding the liquid cryogen and the refrigerator.
22. A method for levitating a rotatable magnetic pumping or mixing element held in a vessel capable of receiving or holding a fluid using the apparatus of claim 18.
23. An apparatus for the intended use of levitating a magnetic element, comprising:
a superconducting element capable of being placed in a superconducting state in accordance with a field cooling protocol and levitating the magnetic element;
a structure including a wall defining a first chamber in which the superconducting element is positioned, said first chamber thermally isolating the superconducting element from the wall;
a cooling source; and
a rod extending between the superconducting element and the cooling source, said rod including an engagement surface contacting the entire area of an adjacent surface of the superconducting element to maximize thermal transfer.
24. A levitation apparatus, comprising:
a superconducting element capable of being placed in a superconducting state in accordance with a field cooling protocol;
a structure including a wall defining a first chamber in which the superconducting element is positioned, said first chamber thermally isolating the superconducting element from the wall;
a cooling source thermally linked to the superconducting element; and
a magnetic element positioned adjacent the wall and levitated by said superconducting element.