GB1590443A - Electrical rotary contact device for providing an electrically conductive path between rotatable and stationary conductive members - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO AN ELECTRICAL ROTARY CONTACT DEVICE FOR PROVIDING AN ELECTRICALLY CONDUCTIVE PATH BETWEEN ROTATABLE AND STATIONARY CONDUCTIVE MEMBERS (71) We, THE GENERAL ELECTRIC COMPANY LIMITED, of 1 Stanhope Gate, London W1A 1EH, a British Company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: l his invention relates to an electrical rotary contact device for providing an electrically conductive path between rotatable and stationary conductive members and has an important application in providing electrical connections to the rotating parts of a dynamo-electric machine.

According to the present invention there is provided an electrical rotary contact device comprising a rotatable electrically conductive member and a stationary electrically conductive member, the stationary conductive member being formed with an inwardly open annular channel coaxial with the axis of rotation of the rotatable member and the rotatable conductive member being formed with an annular projection coaxial with the said axis and projecting in the radially outward direction into the said channel, the facing surfaces of the projection and the channel defining an annular space disposed round the radially outermost part of the projection, in which annular space a quantity of electrically conductive liquid introduced into the channel can be compelled by rotation of the rotatable member to form an annulus in contact with both the said facing surfaces and thereby establish a conductive path between such surfaces, the facing surfaces also defining, at each side of the projection, a plurality of serially connected annular chambers tapered in cross-section in a direction pointing away from the axis of rotation, each annular chamber having its narrower part connected to a wider part of the adjacent radially outward chamber or, in the case of the radially outermost chamber at each side of the projection, connected to the annular space, so that droplets of conductive liquid leaving the annular space during rotation of the rotatable member are trapped in the annular chambers and are impelled by centrifugal forces back towards the annular space.

Preferably, where possible, the surfaces of the annular chambers formed on the rotatable member extend substantially radially of the axis of rotation thereby to obtain the maximum effects of centrifugal forces.

The wider parts of the annular chambers, that is the parts nearer the axis of rotation, are preferably provided with annular troughs or wells designed to collect the droplets of conductive liquid and to bring them into contact with the rotatable surfaces of the chambers.

The conductive liquid may be introduced into the channel through an inlet in the stationary member near the wider part of the radially outermost chamber at one side of the projection, and may be removed through an outlet in the stationary member communicating with the annular space. The conductive liquid, which may comprise a liquid metal such as a galliumlindium alloy, may be circulated through apparatus for removing impurities as described and claimed in U.K. Patent No. 1317478 or in U.K. Patent No. 1452230. To this end a suitable electrolyte may be circulated, with the liquid metal, through at least the radially outermost annular chambers at each side of the projection.

The contact device may also be provided with a dynamic gas seal by passing a blanket gas, such as argon, helium or nitrogen into the radially innermost annular chamber at each side of the projection and extracting the gas from the radially outermost annular chamber at one or both sides of the projection. The gaps may be chosen so that the gas flow is laminar at the required rotation speed.

The invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is an end elevation of part of a dynamo-electric machine provided with an electrical rotary contact device in accordance with the invention; Figure 2 is a section taken on the line II-II in Figure 1 looking in the direction of the arrows; Figure 3 is a section taken on the line III III in Figure 2 but showing only a stationary part of the rotary contact device; and Figure 4 is a fragmentary section taken on the line IV-IV in Figure 3 looking in the direction of the arrows.

Referring to the drawings, the dynamoelectric machine comprises a cylindrical rotor 1 mounted for rotation about its longitudinal axis 2 within an annular stator 3.

Electrical connection between an external circuit and a winding (not shown) on the rotor body 4 is afforded by a rotary contact device or slip ring assembly 5 comprising an electrically conductive member, formed with an annular projection 6, rotationally fast with but electrically insulated from the rotor body 4, the projection 6 projecting in the radially outward direction into an inwardly open annular channel 7 formed in a surrounding electrically conductive annular member 8. The annular member 8 is secured to the stator 3 by bolts 9 so that the annular channel 7 is coaxial with the axis of rotation 2 and with the annular projection 6.

The slip ring assembly 5 is surrounded by a gas-tight housing (not shown) also mounted on the stator 3.

The outer surface 10 of the annular projection 6 and the facing inner surface 11 of the annular channel 7 are suitable profiled to define an annular space 12 disposed round the radially outermost part of the projection 6, so that a quantity of electrically conductive liquid metal comprising a gallium/indium alloy introduced into the channel 7 can be compelled by rotation of the rotor 1 to form an annulus in contact with both the outer surface 10 and the facing inner surface 11 and thereby establish a conductive path between those surfaces.

The facing surfaces also define three serially-connected annular chambers 13, 14 and 15 at one side of the projection 6 and three similar but not identical seriallyconnected annular chambers 16, 17 and 18 at the other side of the projection 6. Each of the chambers 13 to 18 tapers in crosssection in a direction pointing away from the axis of rotation 2 and terminates at its radially outer end in a narrow annular passage 19.

The narrower parts of the radially innermost annular chambers 13 and 16 at each side of the projection 6 are respectively connected to the wider parts of the annular chambers 14 and 17 by their narrow passages 19. The narrower parts of the annular chambers 14 and 17 are respectively connected to the wider parts of the annular chambers 15 and 18 by their narrow passages 19. The narrower parts of the radially outermost annular chambers 15 and 18 at each side of the projection 6 are respectively connected to opposite sides of the annular space 12 by their narrow passages 19. The wider parts of the radially innermost chambers 13 and I6 at each side of the projection 6 communicate with the interior of the gastight housing through annular gaps 20 which provide the clearance between the stationary annular member 8 and the rotatable member which is formed with the projection 6.

The surfaces of the annular chambers 13, 14, 16, 17 and 18 formed on the rotatable member, i.e. by the projection 6, are, as far as is possible, arranged to extend substantially radially to the axis of rotation 2, although the wider parts of the chamber, that is the parts nearer the axis of rotation, are provided with annular troughs or wells 21 extending into the projection 6 and the annular member 8. An inlet 22 located in the lower part of the annular member 8 as shown in Figure 1 but indicated in dotted line in Figure 2, is arranged to open into the part of the annular channel 7 which forms the annular chamber 18, and is connected to means (not shown) for supplying the conductive liquid to the annular space 12 and maintaining it there in a quantity sufficient, during rotation of the rotor 1 and projection 6, to form an annulus in contact with both the facing surfaces 10 and 11 where they define the annular space 12 and thus to provide an electrically conductive path between them. An outlet 23 located in the upper part of the annular member 8 is arranged to communicate with the annular space 12 to remove the conductive liquid. A deflector plate 24 of molybdenum secured to the annular member 8 near to the outlet 23 is arranged to prevent erosion of the adjacent surfaces by the conductive liquid.

The conductive liquid leaving the annular space 12 through the outlet 23 may be circulated through clean-up apparatus for removing impurities as described and claimed in U.K. Patent No. 1317478 or in U.K. Patent No. 1452230. To this end a suitable electrolyte, such as an aqueous sodium hydroxide solution in the case of the gallium/indium alloy mentioned above, may be passed through the two radially outermost chambers at each side of the projection 6 and may be conveyed with the conductive liquid through the outlet 23 to the clean-up apparatus for removing the impurities.

The rotary contact device or slip ring assembly 5 may also be provided with a dynamic gas seal by passing a suitable blanket gas, such as argon, helium or nitrogen into the gas-tight housing and extracting the blanket gas through an outlet 26 located in the lower part of the annular member 8 as shown in Figure 1 and arranged to communicate with the annular chamber 15 as indicated in dotted line in Figure 2. The blanket gas within the housing enters the radially innermost annular chambers 13 and 16 through the annular gaps 20 and flows through the annular chambers 14, 17 and 18 to the outlet 26 in the annular chamber 15.

At high running speeds it may be preferable to pass some or all of the blanket gas out through the outlet 23 along with the conductive liquid and the electrolyte. The ratio of the flow of blanket gas through the outlet 26 to the flow of blanket gas through the outlet 23 may be adjusted to suit the running speed by throttling the outlet 26, or by applying negative pressures to the outlets 23 and 26.

In use of the dynamo-electric machine the rotation of the rotor 1 compels the conductive liquid in the channel 7 to form an annulus in the annular space 12 affording a conductive path between the tip of the projection 6 and the adjacent part of the annular member 8. Any droplets of conductive liquid leaving the annular space 12 must have a trajectory such as to pass through the narrow passages 19 in order to reach the annular chambers 13 to 18. Droplets entering any of the chambers 13 to 18 will tend to be collected in the troughs 21 and will eventually be brought into contact with the rotating surfaces of the projection 6 and impelled towards the annular space 12 by centrifugal force. Removal of the droplets is assisted by the electrolyte which washes the surfaces of the projection 6 and the channel 7 during its flow through the chambers 14, 15, 17 and 18 to the outlet 23. The gas seal prevents the escape of droplets through the annular gaps 20.

WHAT WE CLAIM IS: 1. An electrical rotary contact device comprising a rotatable electrically conductive member and a stationary electrically conductive member, the stationary conductive member being formed with an inwardly open annular channel coaxial with the axis of rotation of the rotatable member and the rotatable conductive member being formed with an annular projection coaxial with the said axis and projecting in the radially outward direction into the said channel, the facing surfaces of the projection and the channel defining an annular space disposed round the radially outermost part of the projection, in which annular space a quantity of electrically conductive liquid introduced into the channel can be compelled by rotation of the rotatable member to form an annulus in contact with both the said facing surfaces and thereby establish a conductive path between such surfaces, the facing surfaces also defining, at each side of the projection, a plurality of serially connected annular chambers tapered in cross-section in a direction pointing away from the axis of rotation, each annular chamber having its narrower part connected to a wider part of the adjacent radially outward annular chamber or, in the case of the radially outermost chamber at each side of the projection, connected to the annular space, so that droplets of conductive liquid leaving the annular space during rotation of the rotatable member are trapped in the annular chambers and are impelled by centrifugal forces back towards the annular space.

2. A rotary contact device as claimed in Claim 1, wherein surfaces of the said annular chambers formed on the rotatable member extend substantially radially of the axis of rotation thereby to obtain the maximum effects of centrifugal forces.

3. A rotary contact device as claimed in either of claims 1 and 2, wherein the wider parts of the annular chambers, that is the parts nearer the axis of rotation, are provided with annular troughs or wells designed to collect the droplets of conductive liquid and bring them into contact with the rotatable surfaces of the chambers.

4. A rotary contact device as claimed in any preceding claim, wherein the stationary member is provided with a conductiveliquid inlet opening into the annular channel and with a conductive-liquid outlet opening out of the annular channel at a greater radial distance from the axis of rotation and near the maximum radial distance of the annular space from the axis.

5. A rotary contact device as claimed in any preceding claim and provided with means for supplying to the said channel and maintaining there a quantity of a conductive liquid sufficient, during rotation of the rotatable member, to form an annulus in contact with both the said facing surfaces where they define the said annular space and thereby to provide an electrically conductive path therebetween.

6. A rotary contact device as claimed in Claim 5, and provided with clean-up means for circulation of the conductive liquid therethrough for removing impurities from the conductive liquid.

7. A rotary contact device as claimed in Claim 6, including means for circulating a suitable electrolyte through at least the radially outermost annular chambers at each side of the projection and then to the said clean-up means.

8. A rotary contact device as claimed in any preceding claim, including means for passing a suitable gas, such as argon, helium or nitrogen into the radially innermost annular chamber at each side of the projection and extracting the gas from the radially outermost chamber at one or both sides of the projection.

9. An electrical rotary contact device for providing an electrically conductive path

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. indicated in dotted line in Figure 2. The blanket gas within the housing enters the radially innermost annular chambers 13 and 16 through the annular gaps 20 and flows through the annular chambers 14, 17 and 18 to the outlet 26 in the annular chamber 15. At high running speeds it may be preferable to pass some or all of the blanket gas out through the outlet 23 along with the conductive liquid and the electrolyte. The ratio of the flow of blanket gas through the outlet 26 to the flow of blanket gas through the outlet 23 may be adjusted to suit the running speed by throttling the outlet 26, or by applying negative pressures to the outlets 23 and 26. In use of the dynamo-electric machine the rotation of the rotor 1 compels the conductive liquid in the channel 7 to form an annulus in the annular space 12 affording a conductive path between the tip of the projection 6 and the adjacent part of the annular member 8. Any droplets of conductive liquid leaving the annular space 12 must have a trajectory such as to pass through the narrow passages 19 in order to reach the annular chambers 13 to 18. Droplets entering any of the chambers 13 to 18 will tend to be collected in the troughs 21 and will eventually be brought into contact with the rotating surfaces of the projection 6 and impelled towards the annular space 12 by centrifugal force. Removal of the droplets is assisted by the electrolyte which washes the surfaces of the projection 6 and the channel 7 during its flow through the chambers 14, 15, 17 and 18 to the outlet 23. The gas seal prevents the escape of droplets through the annular gaps 20. WHAT WE CLAIM IS:

1. An electrical rotary contact device comprising a rotatable electrically conductive member and a stationary electrically conductive member, the stationary conductive member being formed with an inwardly open annular channel coaxial with the axis of rotation of the rotatable member and the rotatable conductive member being formed with an annular projection coaxial with the said axis and projecting in the radially outward direction into the said channel, the facing surfaces of the projection and the channel defining an annular space disposed round the radially outermost part of the projection, in which annular space a quantity of electrically conductive liquid introduced into the channel can be compelled by rotation of the rotatable member to form an annulus in contact with both the said facing surfaces and thereby establish a conductive path between such surfaces, the facing surfaces also defining, at each side of the projection, a plurality of serially connected annular chambers tapered in cross-section in a direction pointing away from the axis of rotation, each annular chamber having its narrower part connected to a wider part of the adjacent radially outward annular chamber or, in the case of the radially outermost chamber at each side of the projection, connected to the annular space, so that droplets of conductive liquid leaving the annular space during rotation of the rotatable member are trapped in the annular chambers and are impelled by centrifugal forces back towards the annular space.

2. A rotary contact device as claimed in Claim 1, wherein surfaces of the said annular chambers formed on the rotatable member extend substantially radially of the axis of rotation thereby to obtain the maximum effects of centrifugal forces.

3. A rotary contact device as claimed in either of claims 1 and 2, wherein the wider parts of the annular chambers, that is the parts nearer the axis of rotation, are provided with annular troughs or wells designed to collect the droplets of conductive liquid and bring them into contact with the rotatable surfaces of the chambers.

4. A rotary contact device as claimed in any preceding claim, wherein the stationary member is provided with a conductiveliquid inlet opening into the annular channel and with a conductive-liquid outlet opening out of the annular channel at a greater radial distance from the axis of rotation and near the maximum radial distance of the annular space from the axis.

5. A rotary contact device as claimed in any preceding claim and provided with means for supplying to the said channel and maintaining there a quantity of a conductive liquid sufficient, during rotation of the rotatable member, to form an annulus in contact with both the said facing surfaces where they define the said annular space and thereby to provide an electrically conductive path therebetween.

6. A rotary contact device as claimed in Claim 5, and provided with clean-up means for circulation of the conductive liquid therethrough for removing impurities from the conductive liquid.

7. A rotary contact device as claimed in Claim 6, including means for circulating a suitable electrolyte through at least the radially outermost annular chambers at each side of the projection and then to the said clean-up means.

8. A rotary contact device as claimed in any preceding claim, including means for passing a suitable gas, such as argon, helium or nitrogen into the radially innermost annular chamber at each side of the projection and extracting the gas from the radially outermost chamber at one or both sides of the projection.

9. An electrical rotary contact device for providing an electrically conductive path

between a rotatable conductive member and a stationary conductive member substantially as hereinbefore described with reference to the accompanying drawings.