Abstract
A vibration exciter apparatus includes an exciter housing, and two bearing means, each supporting a driven shaft carrying eccentric mass means. The driven shafts carrying intermeshing gears. The exciter housing having an array of bore passages extending from an upper wall to a lower wall of the exciter housing, and a mounting structure plate securable to mineral processing or handling equipment intended to be vibrated by the exciter apparatus. Each of the bearing means and the intermeshing gears having separated lubrication liquid sumps. The exciter housing further having the mounting structure plate with an array of fastener receiving zones, whereby elongated fastener means can pass through the bore passages from the upper wall to be engaged in the fastener receiving zones.
Claims
1. A vibration exciter apparatus configured, in use, to impose a vibration regime to vibration processing or handling equipment, said exciter apparatus comprising: an exciter housing; first bearing means and second bearing means positioned in said exciter housing, each first and second bearing means supporting a driven shaft carrying eccentric mass means externally of said exciter housing; a pair of intermeshing gears, each gear being carried by a respective driven shaft for rotation therewith; a first liquid lubricant sump for a first one of said bearing means located within said exciter housing; a second liquid lubricant sump for a second one of said bearing means located within said exciter housing, whereby said second liquid lubricant sump is separate from said first liquid lubricant sump; and a third liquid lubricant sump for said intermeshing gears located within said exciter housing, said third liquid lubricant sump being separate from said first and said second liquid lubricant sumps.
2. The vibration exciter apparatus according to claim 1, wherein, in use, said first bearing means is partially immersed in liquid lubricant located in said first liquid lubricant sump and said second bearing means is partially immersed in liquid lubricant located in said second liquid lubricant sump.
3. The vibration exciter apparatus according to claim 1, wherein, in use, at least one of said intermeshing gears is partially immersed in liquid lubricant in said third liquid lubricant sump.
4. The vibration exciter apparatus according to claim 1, wherein the first bearing means includes at least two bearing members, one said bearing member being a spherical roller bearing and a second bearing members being a toroidal roller bearing member.
5. The vibration exciter apparatus according to claim 1, wherein an interior region of said exciter housing is divided by an intermediary wall portion into two compartment zones, one of said two compartment zones mounting the first bearing means, and a second one of said two compartment zones mounting the second bearing means, each of said two compartment zones being positioned adjacent a first side face of said exciter housing.
6. The vibration exciter apparatus according to claim 5, wherein the interior region of said exciter housing includes a third compartment zone housing said intermeshing gears, said third compartment zone being positioned between said two compartment zones and a second side face of said exciter housing opposite said first side face of said exciter housing.
7. The vibration exciter apparatus according to claim 5, or wherein said exciter housing includes an exciter casing with an upper wall, a lower wall, and two opposed end walls connected to said upper and said lower walls, at least said second side face of said exciter casing is substantially open being closable by a first side wall securable to the upper wall, the lower wall and said end walls by a plurality of first fastener elements.
8. The vibration exciter apparatus according to claim 7, wherein the first side face of said exciter casing is substantially open and is closable by a second side wall securable to the upper wall, the lower wall and said end walls by a plurality of second fastener elements.
9. The vibration exciter apparatus according to claim 7, wherein said exciter casing has an intermediary open region between said two compartment zones and said third compartment zone, an intermediary dividing wall being securable to said exciter casing to separate said third compartment zone from said two compartment zones.
10. The vibration exciter apparatus according to claim 1, wherein first inlet means is provided allowing liquid lubricant to be introduced into said first liquid lubricant sump.
11. The vibration exciter apparatus according to claim 10, further comprising first drain means allowing liquid lubricant to be withdrawn from said first liquid lubricant sump.
12. The vibration exciter apparatus according to claim 11, further comprising an enlarged particulate debris collection zone in said first liquid lubricant sump immediately adjacent said first drain means.
13. The vibration exciter apparatus according to claim 10, further comprising a liquid lubricant level indicating sensor positioned to sense and report liquid lubricant level in said first liquid lubricant sump.
14. The vibration exciter apparatus according to claim 1, wherein second inlet means is provided allowing liquid lubricant to be introduced into said second liquid lubricant sump.
15. The vibration exciter apparatus according to claim 14, further comprising a second drain means allowing liquid lubricant to be withdrawn from said second liquid lubricant sump.
16. The vibration exciter apparatus according to claim 15, further comprising an enlarged particulate debris collection zone in said second liquid lubricant sump immediately adjacent said second drain means.
17. The vibration exciter apparatus according to claim 14, further comprising a liquid lubricant level indicating sensor positioned to sense and report a liquid lubricant level in said second liquid lubricant sump.
18. The vibration exciter apparatus according to claim 1, wherein third inlet means is provided allowing liquid lubricant to be introduced into said third liquid lubricant sump.
19. The vibration exciter apparatus according to claim 18, further comprising a third drain means allowing liquid lubricant to be withdrawn from said third liquid lubricant sump.
20. The vibration exciter apparatus according to claim 19, further comprising an enlarged particulate debris collection zone in said third liquid lubricant sump immediately adjacent said third drain means.
21. The vibration exciter apparatus according to claim 18, further comprising a liquid lubricant level indicating sensor positioned to sense and report liquid lubricant level in said third liquid lubricant sump.
22. The vibration exciter apparatus according to claim 7, wherein said exciter housing includes at least one fastener receivable passage means extending from said upper wall to said lower wall through at least each said end wall, and through an intermediary part of said exciter housing between said first and second liquid lubricant sumps.
23. The vibration exciter apparatus according to claim 22, wherein either said upper wall or said lower wall is positioned closer to said vibration processing or handling equipment when said vibration exciter apparatus is mounted thereto.
24. A vibration exciter apparatus casing for use in vibration exciter apparatus intended, in use, to impose a vibration regime to vibration processing or handling equipment, said vibration exciter apparatus casing comprising a substantially continuous wall structure with an upper wall portion, an opposed lower wall portion, two mutually spaced and opposed end wall portions, and two mutually spaced side faces together defining an internal zone, said internal zone including two bearing mounting compartments separated by a transversely disposed intermediate wall structure extending from a first said side face, each said bearing mounting compartment including a bearing lubricating liquid sump zone separate from the other said bearing mounting compartment, said transversely disposed intermediate wall structure and said bearing mounting compartments being spaced from a second said side face opposed to said first side face whereby a gearing mounting compartment and an associated gearing lubricating liquid sump zone are positioned adjacent said second side face.
25. The vibration exciter apparatus casing according to claim 24, wherein at least one fastener receivable bore passage passes through each said end wall portion and said intermediate wall structure from said upper wall portion to said lower wall portion.
26. The vibration exciter apparatus according to claim 25, wherein at least two fastener receivable bore passages are provided through each said end wall portion.
27. The vibration exciter apparatus according to claim 26, wherein the at least two fastener receivable bore passages are provided through said intermediate wall passage.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0044] FIG. 1 is a perspective view of a DF6xx series prior art exciter apparatus;
[0045] FIG. 2 is a perspective view of the exciter apparatus casing utilised in the exciter apparatus of FIG. 1;
[0046] FIG. 3 is a partially exploded perspective view of the exciter apparatus shown in FIG. 1;
[0047] FIG. 4 is a transverse horizontal section view through both driven shafts of FIG. 1;
[0048] FIG. 5 is a perspective view of a preferred embodiment of exciter apparatus constructed in accordance with the developments of this disclosure;
[0049] FIG. 6 is a perspective view similar to FIG. 5 but with the eccentric masses removed from the driven shafts;
[0050] FIG. 7 is a perspective view of the exciter apparatus of FIG. 6 taken from the opposite side;
[0051] FIG. 8 is a perspective view similar to FIG. 7 but with a side closure plate removed;
[0052] FIGS. 9 and 10 are side elevation views similar to FIG. 8 showing potential differing installation positions of the exciter apparatus, from the intermeshing gear side of the exciter apparatus;
[0053] FIG. 11 is a perspective view similar to FIG. 1 but with the side closure plates removed revealing bearing means supporting the driven shafts;
[0054] FIGS. 12 and 13 are side elevation views similar to FIG. 11 showing potential differing installation positions of the exciter apparatus, from the bearing means side of the exciter apparatus;
[0055] FIG. 14 is a perspective view similar to FIGS. 7 and 8 but with the gearing element compartment closure plate and the gearing elements removed with closure plates closing bearing compartments housing bearings supporting the driven shafts;
[0056] FIG. 15 is a view similar to FIG. 14 with the bearing compartment closure plates removed showing bearings in the bearing compartments;
[0057] FIG. 16 is a perspective view similar to FIG. 6 but with the exciter apparatus casing shown in ghosted outline to reveal aspects of the elongated fastener elements;
[0058] FIG. 17 is a horizontally sectioned perspective view through the driven shafts of the exciter apparatus of FIG. 5;
[0059] FIG. 18 is a vertical section view of the exciter apparatus passing through the short driven shaft;
[0060] FIG. 19 is a section view along line X-X of FIG. 18;
[0061] FIG. 20 is a horizontal section in plan view of the exciter apparatus generally through the driven shafts; and
[0062] FIG. 21 is a perspective view of an exciter apparatus casing generally as utilised in earlier FIGS. 5 to 17 and 18 to 20.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0063] Improvements in exciter apparatus 40 and associated parts such as an exciter apparatus casing 50 and an adapter mounting plate 60 are described in the following. The exciter apparatus casing 50 is shown in many of FIGS. 5 to 17 and 18 to 20 but is represented specifically in FIG. 21 as a single piece, typically constructed as a metallic casting. The exciter apparatus casing 50 has an upper wall 51 with an upwardly facing surface 52, a lower wall 53 with a downwardly facing surface 54, and two opposed end walls 55, 56 continuously formed with the upper wall 51 and the lower wall 53. The exciter apparatus casing 50 further includes a first side face 57 and a second side face 58, facing in opposite directions.
[0064] As can be seen in FIG. 21, the exciter apparatus casing 50 has a first bearing mounting compartment 59 adjacent to and inwardly positioned relative to an end wall 55, and a second bearing mounting compartment 61 adjacent to and inwardly positioned relative to the other end wall 56. An intermediate wall structure 62 connected to the upper wall 51 and the lower wall 52 is positioned between the first and second bearing compartments 59, 61. A seal surface 63 is located in the first side face 57 and forms part of the intermediate wall structure 62 and surrounds the first and the second bearing compartments 59, 61. As can be seen in FIGS. 5, 6 and other drawings, closure plate members 64, 65 are mounted to and sealed to the seal surface 63 by a plurality of fastener members of any suitable type. The closure plate members 64, 65 include central openings 66, 67 which accommodate respectively a short driven shaft 68 and a long driven shaft 69 with suitable seals (not shown) engaging with the shafts 68, 69 to maintain sealed conditions within the exciter apparatus 40.
[0065] As also can be seen in FIG. 21 an enlarged region forming a first bearing lubricating liquid sump zone 70 is positioned between the first bearing mounting compartment 59 and the closure plate member 64. A similar enlarged region forming a second bearing liquid sump zone 71 is positioned between the second bearing mounting compartment 61 and the closure plate 65. In the assembled configuration of the exciter apparatus 40, the first and the second bearing liquid sump zones 70, 71 are maintained completely separate from one another whereby it is possible to prevent contaminants from the gear liquid sump entering the bearing liquid sumps, also to select and use lubricating liquids in the respective sump zones 70 and 71 that have differing characteristics, such as viscosity, that are best selected for operation of the exciter apparatus 40, particularly to improve performance of same and to extend periods between potential maintenance stages.
[0066] FIG. 19 illustrates a drain passage 74 leading from the first bearing liquid lubricant sump zone 70 to a drain point 73 whereby, during a maintenance stage, used liquid lubricant can be removed from the first bearing liquid sump zone 70. Similarly, a drain passage 72 leading from the second bearing liquid lubricant sump zone 71 to a drain point 75 is provided whereby during a maintenance stage, used liquid lubricant can be removed from the second bearing liquid lubricant sump zone 71. Suitable inlet port means are provided through the upper wall 51 to allow original or replacement liquid lubricant to be introduced into either the first or the second bearing liquid lubricant sumps 70, 71. As can be seen in FIG. 21, and other drawings, each of the first and the second bearing liquid lubricant sump zones 70, 71 have a triangular shaped bulge or extension region 76, 77 approaching the entrances to drain passages 72, 74 acting as a collection zone for the liquid lubricant and potentially any particulate debris that might enter or be formed within the exciter apparatus such that it might be removed with any used or spent liquid lubricant.
[0067] FIGS. 20, 21 illustrate that each of the first and the second bearing mounting compartments 59, 61 end part way towards the second side face 58. The second side face 58 has a seal surface 78 generally surrounding a gearing mounting compartment 79 configured to house separate intermeshing gears 80, 81 that are mounted on the driven shafts 68, 69. Closure plates 82, 83 (FIG. 14) are sealed to the first and second bearing mounting compartments 59, 61 internally of the exciter apparatus 40. The closure plates 82, 83 have central openings 84, 85 through which the driven shafts 68, 69 pass, the closure plates 82, 83 having suitable seal means to prevent liquid lubricant and other materials to pass along the shafts.
[0068] As shown, for example, in FIGS. 17, 18 and 20, bearing means 108 may be provided to support the driven shafts 68, 69 in the first and the second bearing mounting compartments 59, 61. The bearing means 108, in each case, may comprise a pair of side by side bearing members 109 and 110. The bearing member 109 is conveniently a toroidal roller bearing and the bearing member 110 is a spherical roller bearing (SRB). While the drawings represent two driven shafts 68, 69 and a consequent supporting bearing arrangement as illustrated, in some embodiments one driven shaft only might be provided and more than two driven shafts might be provided.
[0069] The gearing mounting compartment 79 has a liquid lubricant introduction port in the upper wall 51 whereby liquid lubricant of a desired type or characteristics can be introduced into the compartment 79 either before use or during a later maintenance stage of the exciter apparatus 40. A drain port 86 (FIG. 8) is provided with a communicating drain passage leading to a lower region of the gearing mounting compartment 79. Conveniently, the gearing mounting compartment 79 includes an enlarged triangular bulge portion 87 leading to the drain passage at a low portion of the compartment 79. The compartment 79 provides a gearing lubricating liquid sump zone 101. Conveniently, an outer closure plate 88 closes the gearing mounting compartment 79 by sealing means and multiple fastener members pressing an edge face region of the outer closure plate 88 against the seal surface 78. Again the closure plate 88 includes central openings 89, 90 and seal means cooperating with the driven shafts 68, 69 (FIG. 7).
[0070] Referring again to FIG. 21, the exciter apparatus casing 50 incudes a plurality of elongated fastener receiving bore means 91 positioned vertically extending through the casing 50. Each of the fastener receiving bore means 91 includes a first end zone 92 disposed at or adjacent to the upwardly facing surface 52 of the upper wall 51, and a second end zone 93 disposed at or adjacent to the downwardly facing surface 54 of the lower wall 53. Preferably, the fastener receiving bore means 91 includes a continuous bore passage from the first end zone 92 to the second end zone 93. Alternatively, at least some of the fastener receiving bore means 91 include a first bore passage section adjacent the first end zone 92 with a continuous bore passage section aligned with a second bore passage section adjacent the second end zone 93 with a continuous bore passage section. In this latter option, seal means operating between a cooperating elongated fastener and the fastener receiving bore means 91 at the upper level of the exciter apparatus casing 50 and at the lower level of the exciter apparatus housing would be required.
[0071] In the illustrated preferred embodiment show in in FIG. 21 and other figures, the fastener receiving bore means 91 are disposed in a defined array, consisting of six bore passages 91, each being adapted to receive an elongated bolt, rod or other suitable fastener 99. Two such bore passages are located on a transverse mid point axis of the exciter apparatus casing 50 and two each are located extending through a respective end wall 55 and 56. In some cases, the two centrally located bore passages might be replaced by a single bore passage centrally located. Other possible arrangements of bore passages in the array are possible, however it is desirable to have the bore passages symmetrically disposed about a central transverse axis. Both of the first end zone 92 and the second end zone 93 may include physical formation means such as the illustrated raised annular ring 130 that is complementary shaped with physical formation means on the adapter mounting plate 60 to prevent or minimise lateral movement when engaged.
[0072] If desired the annular ring formations 92a/93a in both the upper wall 51 and the lower wall 52 of the exciter casing 50 may include inclined surfaces to assist movement of the bores 91 into alignment with fastener element engagement regions positioned on the adapter mounting plate 60.
[0073] Preferably, both the upper wall 51 and the lower wall 52 includes upstanding flange members 94 with apertures 95 to assist lifting means to be connected to the exciter apparatus 40 when installing or removing such exciter apparatus from an operative position.
[0074] Referring to the drawings, the adapter mounting plate 60 includes a central section 96 and edge sections 97 with spaced bores and fasteners 97a along its length each being adapted to receive a suitable fastener member. In the illustrated embodiments, the bores with fasteners 97a in edge sections 97 are positioned to allow the adapter mounting plate 60 to be mounted to a fixing position in Schenck Process mineral processing or handling equipment constructed to install an existing DF6xx series exciter apparatus, for example, constructed according to FIGS. 1 to 4. In the case of some other existing exciter apparatus that might need to be replaced, the configuration of the adapter mounting plate and the holes or bores for mounting same might vary to be consistent with the existing structures. The adapter mounting plate 60 further includes long bolt or rod fastening positions 98 that may comprise an array of upraised boss formations along the central section 96 configured to correspond and be complementary to the first end zones 92 and the second end zones 93 provided on the upper wall 51 and the lower wall 53 of the exciter apparatus casing 50.
[0075] Each of the upraised boss formations include fastening bore means or any other connection means forming the long bolt or rod fastening positions 98 engageable with an end of an elongated fastening bolt, rod or the like 99 passing through an elongated fastener receiving bore means 91. The boss formations may also include formation means cooperable with and complementary to the physical formation means on the first end zone 92 and the second end zone 93 of the fastener receiving bore means 91. Alternatively, the adapter mounting plate 60 may include recessed zones to form the long bolt or rod fastening position 98 engageable with either the first zones 92 or the second end zones 93 of the fastener receiving bore means 91.
[0076] FIGS. 9/10 and FIGS. 12/13 illustrate the effect of mounting the exciter apparatus 40 and the associated adapter mounting plate 60 at differing angles of inclination and particularly when the exciter apparatus is partially inverted as shown in FIGS. 10 and 13. FIGS. 9/10 show the exciter apparatus from the gearing side of the exciter apparatus 40 with the outer closure plate 88 removed. FIGS. 12/13 show the exciter apparatus 40 from the bearing side of the exciter apparatus 40 with the two outer closure plates 64, 65 removed. As shown in FIG. 9, the lower wall 53 of the exciter apparatus casing 50 faces toward the adapter mounting plate 60 with the second end zones 93 of the fastener receiving bore means 91 in engagement with a respective long bolt or rod fastening position 98. In the partially inclined and inverted position shown in FIG. 10 the first end zones 92 of the upper wall 51 are positioned in engagement with a fastening position 98 on the adapter mounting plate 60. In either positional location represented in FIGS. 9 and 10 an elongated fastener member 99 passes through the fastener receiving bore means 91 to secure the exciter apparatus 40 to the adapter mounting plate 60 and thereby to the processing or handling equipment (not shown). FIGS. 9 and 10 illustrate the lubricating liquid pool 100 collected in the gearing lubricating liquid sump zone 101 formed by the compartment 79. The lubricating liquid pool 100 is collected in the region of the enlarged bulge portion 87 and a stationary, semi-permanent, level measuring probe 102 is provided to provide automatically a signal indicative of the liquid level, and thereby, the volume of lubricating liquid in the gearing mounting compartment 79. If the mounting inclination angle is reversed, then the illustrated structures permit the exciter apparatus 40 to be rotated about a central vertical axis such that the lubricating liquid pool 100 will always form in the region of enlarged bulge portion 87 and the level measuring probe 102. In this manner, it is possible to achieve consistent measuring of lubricating liquid volumes in the gearing mounting compartment.
[0077] FIGS. 12 and 13 show the effects discussed in the preceding paragraph from the bearing side of the exciter apparatus 40. It is apparent from these drawings that separate lubricating liquid pools 103 and 104 are maintained in the first bearing liquid lubricant sump zone 70 and the second lubricant liquid sump zone 71 with the pools 103, 104 being located in the region of the extension or bulged regions 76, 77. In addition separate liquid level measuring probes 105, 106 are installed in these zones.
[0078] FIGS. 9/10 and 12/13 represent the vibration exciter housing 50 mounted in an upwardly extending inclined position (FIGS. 9/12) and an underslung downwardly extending position (FIGS. 10/13). It will of course be appreciated that the angle of inclination of the mounting position could be reversed such that the end wall portions of the exciter housing 50 forming the lowest one of the end wall portions in FIGS. 9/10 and 12/13 would become the higher of the two end wall portions. This would of course be problematic in that the liquid lubricant pools would change position and the liquid lubricant level sensors 102, 105, 106, may not be correctly immersed in the liquid lubricant pools. To avoid this difficultly, the first array of fastener element positioning locations (bores 91) on the upper or lower walls of the exciter housing 50 are positioned whereby the exciter housing 50 can be rotated about a vertical intermediate axis such that the end wall represented as the lower most one in FIGS. 9/10 and 12/13 will always remain the lower most end wall whereby the liquid lubricant pools in the respective sump zones will remain in the same position (as illustrated in FIGS. 9/10 and 12/13). This can be achieved by arranging the fastener receiving bores 91 to be in an array whereby the bores 91 on one side of a central transverse axis is a mirror image of the bores 91 on the other side of the central transverse axis 143 such that regardless of rotating the position of the exciter housing 50, the bores 91 will continue to align with fastener receiving connection zones in the adapter mounting plate 60 or the vibration processing or handling equipment itself. In the illustrated embodiment, three pairs of fastener receiving bores 91 are illustrated with the central pair of fastener receiving bores 91 being positioned on the aforesaid transverse axis 143. Other configurations, are of course, possible.
[0079] Generally, the exciter apparatus 40 will carry eccentric masses 107 carried on the driven shafts 68, 69 (FIG. 5). In the proposed design, the one eccentric mass 107 is carried at each end zone of the driven shafts 68, 69 which overlap, in use when the driven shafts 68, 69 are rotated. Dynamic guard shields would also be provided (not illustrated) mounted from the exciter apparatus casing 50, however, because of the design arrangements previously described, access to the elongated fastener means 99 is not obstructed. This enables the dynamic guard shields to remain attached to the exciter apparatus 40 if the exciter apparatus 40 is to be removed for any purpose.
[0080] FIGS. 17, 18 and 20 and other drawings illustrate one preferred cooling means 150 for cooling the liquid lubricant in the lubricating liquid pools 103, 104 and the bearing means 108. In this proposal, one or multiple cooling element cartridges 151 are installed in a bore or passage 152 axially extending fully through the or each driven shaft 68/69, or at least from a position underlying each bearing means 108 to a position external of the exciter housing 50. Each cooling element cartridge 151 includes a heat receiving mounting part 153 at one end and a heat dissipating part 154 at an external end. Alternatively, in a one piece assembly, a central heat receiving mounting part 153 might be provided with two opposed heat dissipating parts 154 at distal ends of the assembly. Each of the cooling element cartridges 151 further includes at least one and preferably multiple heat pipes 155 as described previously. A heat flow path is thereby established from the bearing means 108 through a respective driven shaft 68 or 69 to a heat receiving mounting part 153 along the heat pipe or pipes 155 to the heat dissipating mounting part 154 positioned externally of the exciter housing 50. Thus, generated heat can be moved to an external location and dissipated therefrom. The heat dissipation process may be helped by providing fan means mounted on a driven shaft, on each driven shaft, or elsewhere in the vibration apparatus 40.
[0081] Other possible options might also be used for cooling parts of the exciter apparatus 40, to lower operating temperatures to effectively extend periods of time between maintenance down times. The disclosure proposes, as indicated previously, separate lubricating liquid sump zones with an expectation that these configurations will result in higher heat transfer out of the bearings that occur with current designs. A second option is to utilise high thermal conductivity materials, in the exciter apparatus casing structures, particularly in bearing compartment closure covers. A third potential option is to provide a cooling fan on one or both driven shafts to increase air flow onto the exciter apparatus casing walls. A fourth option is to provide high thermal conductivity inserts into the exciter apparatus walls or the driven shafts. A fifth option is to position heat flow pipes for passage of cooling air flow or liquid flow in the housing walls and the driven shafts. Of course, multiple such options might be utilised. FIGS. 16, 17, 18 and 19 illustrate options for locating heat movement or transfer cartridges 151 in the driven shafts 68, 69.
[0082] The foregoing describes various preferred embodiments of exciter apparatus for imposing a vibration regime to mineral processing or handling equipment and to parts of such exciter apparatus. Improvement features, in some instances, also relate to and may be applied to other known exciter apparatus by skilled persons in this art. Features disclosed specifically in relation to one embodiment might equally apply to other exciter apparatus, and parts of same, within the context of the annexed patent claims.
