Fluid transfer coupling

A fluid transfer coupling comprising:

• a first shaft assembly;
• a second shaft assembly;
• and
• a seal assembly,
• the first shaft assembly comprising:
• a first shaft;
• and
• an annular fin attached to the first shaft, the annular fin having one or more internal passages extending therethrough, the or each internal passage connecting a centre portion of the first shaft to a radially outwardly facing side of the annular fin,
• the second shaft assembly comprising:
• a second shaft;
• and
• an annular trough extending radially outwardly of the second shaft,
• wherein the first shaft is concentrically accommodated within the second shaft with the annular fin accommodated within the annular trough, the seal assembly seals the annular trough, and
• in use, a fluid is delivered to the annular trough, the first shaft assembly rotates at a first rotational speed and the second shaft assembly rotates at a second rotational speed, the second rotational speed being greater than the first rotational speed, the difference between the second rotational speed and the first rotational speed causes the fluid contained within the annular trough to be driven radially inwardly through the or each internal passage to the centre portion of the first shaft,
• wherein the seal assembly comprises a first sealing element on a first end of the annular trough, and a second sealing element on a second axially opposite end of the annular trough, with the fluid being delivered to the annular trough between the first and second sealing elements,
• wherein each of the sealing elements is a lift-off seal.

A fluid transfer coupling comprising:

• a first shaft assembly;
• a second shaft assembly;
• and
• a seal assembly,
• the first shaft assembly comprising:
• a first shaft;
• and
• an annular fin attached to the first shaft, the annular fin having one or more internal passages extending therethrough, the or each internal passage connecting a centre portion of the first shaft to a radially outwardly facing side of the annular fin,
• the second shaft assembly comprising:
• a second shaft;
• and
• an annular trough extending radially outwardly of the second shaft,
• wherein the first shaft is concentrically accommodated within the second shaft with the annular fin accommodated within the annular trough, the seal assembly seals the annular trough, and
• in use, a fluid is delivered to the annular trough, the first shaft assembly rotates at a first rotational speed and the second shaft assembly rotates at a second rotational speed, the second rotational speed being greater than the first rotational speed, the difference between the second rotational speed and the first rotational speed causes the fluid contained within the annular trough to be driven radially inwardly through the or each internal passage to the centre portion of the first shaft,
• wherein the seal assembly comprises a first sealing element on a first end of the annular trough, and second and third sealing elements on a second axially opposite end of the annular trough, with the fluid being delivered to the annular trough between the second and third sealing elements.

A method of using a fluid transfer coupling, the fluid transfer coupling comprising a first shaft assembly, a second shaft assembly, and a seal assembly, the first shaft assembly comprising a first shaft and an annular fin attached to the first shaft, the annular fin having one or more internal passages extending therethrough, the or each internal passage connecting a centre portion of the first shaft to a radially outwardly facing side of the annular fin, the second shaft assembly comprising a second shaft and an annular trough extending radially outwardly of the second shaft, the method comprising:

• arranging the first shaft assembly concentrically within the second shaft assembly with the annular fin being accommodated within the annular trough, and with the seal assembly sealing the annular trough against a radially outwardly facing surface of the first shaft assembly;
• introducing a supply of fluid to the annular trough through one or more static oil jets positioned radially outwardly of the first shaft;
• and
• driving the first shaft assembly at a first rotational speed and the second shaft assembly at a second rotational speed, where the second rotational speed is greater than the first rotational speed;
• and
• the difference between the second rotational speed and the first rotational speed causing the fluid to be driven radially inwardly from the trough through the or each internal passage to the centre of the first shaft.