Abstract
An adaptor for connecting a generator to a prime mover. The adaptor includes a first flange member for connection to the prime mover, a second flange member for connection to the generator, and a plurality of angled cross members between the first and second flange members. By providing a plurality of angled cross members between the first and second members, the adaptor may use less material for a given stiffness.
Claims
1. An adaptor arranged to connect a generator to a prime mover, the adaptor comprising: a first flange member arranged to connect to the prime mover; a second flange member arranged to connect to the generator; a plurality of pairs of cross members which connect the first flange member and the second flange member such that the first flange member and the second flange member are substantially concentric and spaced apart axially, and a first opening between a first cross member and a second cross member of one of the pairs of cross members, wherein a second opening between two pairs of cross members is larger than the first opening, wherein the cross members are angled such that one end of a cross member is offset circumferentially with respect to another end of said cross member, and wherein the pairs of the cross members are V-shaped with one cross member of a pair angled in the opposite direction circumferentially to the other cross member of the pair.
2. An adaptor according to claim 1, wherein the cross members are angled with respect to a line lying parallel with the axis of the generator.
3. An adaptor according to claim 1, wherein the ends of the cross members are adjacent to bolt holes in at least one of the first flange member or the second flange member.
4. An adaptor according to claim 1, wherein a cross member extends between a location adjacent to a bolt hole in the first flange member and a location adjacent to a bolt hole in the second flange member.
5. An adaptor according to claim 1, wherein the cross members of a pair have first ends located adjacent to separate bolt holes in the first flange member, and second ends located adjacent to the same bolt hole in the second flange member.
6. An adaptor according to claim 1, wherein: the base of the V is adjacent to a bolt hole in the second flange member; and the ends of the V are adjacent to separate bolt holes in the first flange member.
7. An adaptor according to claim 1, wherein a bolt hole in the second flange member lies circumferentially between two bolt holes in the first flange member.
8. An adaptor according to claim 1, wherein at least one of the first flange member or the second flange member is substantially ring-shaped.
9. An adaptor according to claim 1, wherein at least one of the first flange member or the second flange member comprises protrusions which extend radially outwards from the circumference of the respective flange member, and bolt holes are located in the protrusions.
10. An adaptor according to claim 1, wherein the diameter of the first flange member is larger than the diameter of the second flange member, and wherein the cross members are connected on a radially inwards side of the first flange member and a radially outwards side of the second flange member.
11. An adaptor according to claim 1, wherein the cross members are connected to protrusions which extend radially outwards from the circumference of the second flange member.
12. An adaptor according to claim 1, wherein the first flange member includes a recess between two cross members of a pair.
13. An adaptor according to claim 1, wherein the adaptor is arranged to accommodate a fan, and a cross member presents a progressive cutting edge to the blade of the fan.
14. An adaptor according to claim 1, wherein the adaptor is arranged to be cast without using a core.
15. A power generation system comprising: a prime mover; a generator; and an adaptor comprising a first flange member connected to the prime mover, a second flange member connected to the generator, a plurality of pairs of cross members which connect the first flange member and the second flange member such that the first flange member and the second flange member are substantially concentric and spaced apart axially, and a first opening between a first cross member and a second cross member of a pair of cross members, wherein a second opening between two pairs of cross members is larger than the first opening, wherein the cross members are angled such that one end of a cross member is offset circumferentially with respect to another end of said cross member, and wherein the pairs of the cross members are V-shaped with one cross member of a pair angled in the opposite direction circumferentially to the other cross member of the pair.
Description
(1) Preferred features of the present invention will now be described, purely by way of example, with reference to the accompanying drawings, in which;
(2) FIG. 1 shows schematically a generating set comprising an engine coupled to a generator;
(3) FIG. 2 shows a previously considered adaptor;
(4) FIG. 3 shows parts of a partially assembled generator set;
(5) FIGS. 4 and 5 show an adaptor in an embodiment of the present invention;
(6) FIG. 6 is a top view of the adaptor of FIGS. 4 and 5;
(7) FIGS. 7A to 7C show side views of various adaptor designs;
(8) FIG. 8 shows an end view of part of the adaptor of FIGS. 4 and 5;
(9) FIG. 9 shows a cross section through part of the adaptor of FIGS. 4 and 5;
(10) FIG. 10 shows part of the adaptor of FIGS. 4 and 5 viewed from the inside;
(11) FIG. 11 shows an end view of part of the adaptor of FIGS. 4 and 5; and
(12) FIGS. 12A and 12B shows the adaptor of FIGS. 4 and 5 with a fan located inside.
OVERVIEW
(13) FIG. 1 shows schematically a generating set comprising an engine 10 coupled to a generator (alternator) 12. The engine 10 is typically an internal combustion engine such as a petrol or diesel engine. The generator 12 may be any type of electrical generator, such as a synchronous generator or a permanent magnet generator. The engine 10 and generator 12 are both mounted on a bed frame 14. The crankshaft of the engine (not shown) is mechanically coupled to the rotor of the generator (not shown). In operation, mechanical energy produced by the engine 10 is transferred to the generator 12 in order to generate the electrical output.
(14) In the arrangement of FIG. 1 the engine 10 comprises a flywheel located in a fly wheel housing 16. An adaptor 18 is used to connect the engine 10 to the generator 12. The adaptor 18 helps to prevent relative movement between the engine and the generator.
(15) FIG. 2 shows a previously considered adaptor design for connecting a generator to an engine. Referring to FIG. 2, the adaptor 20 is generally cylindrical and is formed from a single cast piece of metal. Flanges at each end allow the adaptor to be bolted to the flywheel housing on one side and the generator on the other side. Openings 22 are provided in the adaptor. The openings 22 allow access to the interior of the adaptor, which allows an operator to connect the rotating parts once the generator has been brought into alignment with the engine.
(16) FIG. 3 shows parts of a partially assembled generator set. Referring to FIG. 3, the partially assembled generator set comprises a generator 12 to which is attached an adaptor 20. The generator comprises a generator shaft 24 on which is mounted a fan 26 and a coupling plate 28. During assembly, the generator 12 and adaptor 20 are brought into alignment with the engine. As shown in FIG. 3, the openings 22 allow an operator to access to the coupling plate 28. This allows the operator to bolt the coupling plate 28 to the engine flywheel.
(17) The previously considered adaptor shown in FIGS. 2 and 3 may be effective in ensuring a stiff connection between the generator and the engine. However various problems have been identified in the previously considered adaptor, as discussed below.
(18) The adaptor shown in FIGS. 2 and 3 is cast from a single piece of metal. However the casting process requires a core, which increases the manufacturing cost and complexity.
(19) As can be seen in FIG. 3, the openings 22 only provide a limited space for the operator to insert bolts in the coupling plate 28. If an attempt were made to increase the size of the openings, then this would reduce the stiffness of the adaptor, and increase the risk of defects arising during the casting process.
(20) It has also been found that the adaptor of FIGS. 2 and 3 is relatively heavy, thereby adding to the overall weight of the generating set. It would also be desirable to reduce the overall amount of material used, in order to reduce the cost of manufacture.
(21) Furthermore, it has been found that the openings 22 in the adaptor can lead to fan noise, with a consequential negative impact on the operating environment.
(22) Adaptor Design
(23) Embodiments of the present invention are directed to adaptor designs which may maximize the stiffness to weight ratio of the adaptor, simplify the casting process, provide greater access for an operator to connect rotating parts, and/or reduce fan noise, in comparison to previously considered designs.
(24) FIGS. 4 and 5 show an adaptor in an embodiment of the present invention for connecting a generator to an engine. FIG. 4 shows the adaptor from the generator side while FIG. 5 shows the adaptor from the engine side.
(25) Referring to FIGS. 4 and 5, the adaptor 30 comprises a first flange member 32, a second flange member 34, and a number of cross members 36, 38. The first flange member 32 and the second flange member 34 are both essentially ring-shaped, with the flange member 32 having a radius which is larger than that of the second flange member 34. The first flange member 32 has a flat surface 33 which interfaces with a fly wheel housing. The second flange member 34 has a flat surface 35 which interfaces with a generator frame.
(26) The first flange member 32 is provided with a number of bolt holes 40. The bolt holes 40 are located in protrusions 42 which extend radially outwards from the circumference of the first flange member 32. The second flange member 34 is provided with bolt holes 44. The bolt holes 44 are located in protrusions 46 which extend radially outwards from the circumference of the second flange member 34. The bolt holes 40 in the first flange member are arranged for connecting the adaptor 30 to a flywheel housing, while the bolt holes 44 in the second flange member 34 are arranged for connecting the adaptor 30 to a generator frame. The number and location of the bolt holes 40, 44 may be governed by standard requirements, such as SAE (Society of Automotive Engineers) standards. In this embodiment the first flange member 32 has 12 bolt holes and the second flange member 34 has 6 bolt holes, although of course the number of the bolt holes and their locations may be varied in dependence on the particular engine and generator to which the adaptor is to be connected.
(27) In the arrangement of FIGS. 4 and 5, the cross members 36, 38 connect the first flange member 32 and the second flange member 34 in such a way that the first flange member and the second flange member are substantially concentric, but spaced apart axially. The cross members 36, 38 also maintain a small radial separation between the first and second flange members. This may be achieved at least in part by connecting each cross member 36, 38 to a radially inward part of the first flange member 32 and to a radially outward part of the second flange member 34. Furthermore, the cross members 36, 38 connect the first flange member 32 and the second flange member 34 in such a way that each bolt hole 44 in the second flange member 34 lies circumferentially between two bolt holes 40 in the first flange member 32.
(28) Still referring to FIGS. 4 and 5, it can be seen that, rather than lying parallel to the axis of rotation of the generator, each cross member 36, 38 lies at an angle relative to the axis of rotation. Some cross members 36 are angled in one direction relative to the axis of rotation, while other cross members 38 are angled in the opposite direction relate to the axis of rotation. The cross members are grouped together in pairs, with each pair forming a “V” configuration. In this embodiment the base of a “V” is connected to the second flange member 34 in the vicinity of a bolt hole 44, while the ends of the “V” are connected to the first flange member 32 in the vicinity of bolt holes 40. The V-shaped cross member design results in a large opening 50 between two pairs of cross members, and a small opening 52 between two cross members of a pair.
(29) During assembly of the generator set, the first flange member 32 is bolted to the engine's flywheel housing, and the second flange member 34 is bolted to the generator frame.
(30) FIG. 6 is a top view of the adaptor 30 showing a pair of cross members 36, 38. Referring to FIG. 6, the value of the angle α is typically between 40° and 70°. The width w of the cross members 36, 38 is typically between 20 mm and 35 mm. The width b of the base of the “V” is typically between 20 mm and 40 mm. The distance d.sub.1 between two cross members at the point where they connect with the first flange member 32 is typically 50 mm to 70 mm. The radius of curvature r on the inside of the “V” is typically between 6 mm and 12 mm. Of course, any of these values may be varied, and different values may be used as appropriate.
(31) Stiffness
(32) Referring to FIGS. 4 and 5, it can be seen that the V-shaped design of the cross members provides a direct connection between the bolt holes 40 in the first flange member 32 and the bolt holes 44 in the second flange member 34. Thus this arrangement can allow an effective transfer of force from the engine mounting points to the generator mounting points, with a minimum distance between load point and reaction point. This can allow a required stiffness to be achieved using a minimum amount of material. Thus the overall amount of material can be reduced for a given stiffness, thereby reducing the cost of manufacture and reducing the weight of the generator set, in comparison to the previously considered adaptor design. For example in one embodiment, it has been found that the stiffness of the adaptor can be maintained or increased while reducing the amount of material by 50%.
(33) Size of Window
(34) Referring again to FIGS. 4 and 5, it can be seen that the V-shaped cross member design allows the size of the openings 50 between two adjacent pairs of cross members to be increased towards the second flange member 34. This allows increased hand room for an operator to couple the generator to the engine during assembly of the generator set. Furthermore the open cross member design provides greater visibility of the rotating components, thereby facilitating assembly. These features in turn help to reduce the assembly time and make the design more acceptable to the end user.
(35) FIG. 7A shows a side view of the adaptor 30 in the embodiment of FIGS. 4 and 5. Referring to FIG. 7A, in this embodiment the distances d.sub.1 and d.sub.3 are each approximately 65 mm. However the distance d.sub.2 between two adjacent pairs of cross members at their widest point (where they meet the second flange member) is approximately 138 mm. This allows a larger opening to be achieved than that in the previously considered adaptor design, thereby facilitating assembly of the generator set.
(36) FIG. 7B shows a side view of an adaptor in another embodiment of the invention. In this embodiment the angle of the cross members is slightly less than that in the embodiment of FIG. 7A. The distance d.sub.3 between two adjacent pairs of cross members at their narrowest point (where they meet the first flange member) is approximately 78 mm. The distance d.sub.2 between two adjacent pairs of cross members at their widest point (where they meet the second flange member) is approximately 130 mm. Thus this arrangement can provide a wider opening near the first flange member.
(37) FIG. 7C shows a side view of an adaptor in another embodiment of the invention. In this embodiment the pairs of cross members are spaced further apart. The distance d.sub.3 between two adjacent pairs of cross members at their narrowest point (where they meet the first flange member) is approximately 130 mm. The distance d.sub.2 between two adjacent pairs of cross members at their widest point (where they meet the second flange member) is approximately 164 mm. Thus this arrangement can provide a wider opening at the expense of reduced stiffness.
(38) In each of FIGS. 7A to 7C the distance d.sub.4 between the first flange member and the second flange member is approximately 75 mm.
(39) It will be appreciated that the above dimensions are given by way of example only, and each of the values may be adjusted as appropriate to the circumstances.
(40) FIG. 8 shows an end view of part of the adaptor 30, viewed from the side of the second flange member 34. Referring to FIG. 8, it can be seen that the cross members 36, 38 maintain a small radial separation g between the first flange member 32 and the second flange member 34. This is achieved by connecting the cross members 36, 38 to a radially inward part of the first flange member 32 and a radially outward part of the second flange member 34. In this case the cross members 36, 38 are connected to the radial protrusions 46 on the second flange member 34. The cross members 36, 38 may also be inclined.
(41) The radial separation g between the first and second flange members increases the size of the opening, leaving additional hand room for assembly. Furthermore, the smaller diameter of the second flange member allows access to the coupling plate at a more acute angle to the axis of the machine, thereby facilitating connection of the coupling plate to the engine.
(42) Weight
(43) As discussed above, the V-shaped cross member design can allow a required stiffness to be achieved using a minimum amount of material. This in turn can allow the weight of the adaptor to be reduced. Other features of the design also contribute to a reduction in the amount of material and hence a reduction in the weight, as discussed below.
(44) Referring in particular to FIGS. 4, 5 and 8, it can be seen that the bolt holes 40 are provided in protrusions 42 which extend radially outwards from the perimeter of the first flange member 32. This can allow the first flange member 32 to have a reduced diameter for most of its circumference, with extra material only being provided where it is needed for the bolt holes 40. The addition of material only around the bolt holes can help to reduce amount of material used for the first flange member, and thus reduce the overall cost and weight of the adaptor.
(45) FIG. 9 shows a cross section through part of the adaptor 30 at a point where it connects with the generator. A bolt 54 is used to connect the second flange member 34 with the generator frame 56. The adaptor includes a taper 58 on the outer diameter of the second flange member 34. The taper 58 reduces the amount of material used for the second flange member 34, and thus contributes to a reduction in the overall weight of the adaptor.
(46) FIG. 10 shows part of the adaptor 30 viewed from the inside. Referring to FIG. 10, the second flange member 34 includes pads 60 on its inside surface at locations where the cross members 36, 38 meet the second flange member 34. The pads 60 are thus provided in locations where the bolt holes 44 are to be drilled. It has been found that, by providing the pads 60 only in locations where machining is expected, the thickness of the second flange member 34 can be reduced elsewhere. This can further reduce the overall cost and weight of the adaptor.
(47) FIG. 11 shows an end view of part of the adaptor 30, viewed from the side of the first flange member 32. Referring to FIGS. 10 and 11, the first flange member 32 includes recesses or pockets 62 on its radially inwards edge between the points where two cross members 36, 38 of a pair meet the first flange member 32. It has been found that the V-shaped cross members 36, 38 help to strengthen the first flange member 32, and accordingly that less material need be used in locations between the two cross members. Thus provision of the recesses 62 can help to reduce the overall cost and weight of the adaptor.
(48) Coreless Casting
(49) The previously considered adaptor design requires a core to be used in the casting process in order to produce the required internal cavities and re-entrant angles. This increases the cost and complexity of the manufacturing process.
(50) It has been found that provision of the recesses 62 facilitates flow of material through the mould during casting. The casting process is further facilitated by the tapered nature of the adaptor design. It has been found that, as a consequence, it may be possible to cast the adaptor without requiring a core. This can therefore reduce the cost and complexity of the manufacturing process, as well as reducing the weight of the adaptor.
(51) Fan Noise
(52) Generator sets typically include a fan in order to force cooling air through the generator. The fan is typically mounted on the generator shaft, inside the adaptor.
(53) As discussed above, it is necessary to provide openings in the adaptor to allow an operator to bolt the coupling plate to the engine. However the openings may lead to fan noise being transmitted to the exterior, with negative consequences for the working environment.
(54) FIGS. 12A and 12B shows the adaptor 30 with a fan 64 located inside. In operation the fan 64 rotates inside the adaptor 30 as shown in FIG. 12A. Rotation of the fan 64 forces air against the cross members 36, 38 and through the openings 50, 52.
(55) In the previously considered adaptor design, the openings in the adaptor present a substantially parallel edge to the blades of the fan. By contrast, the cross members of the present embodiment lie at an angle β to the fan blades, as shown in FIG. 12B. Thus the cross members of the present embodiment present a progressive cutting edge against the fan blades during rotation of the fan. It has been found that the magnitude of the noise generated with this design is less than in the case where the side of the opening is straight and the fan blade cuts it instantaneously.
(56) Thus the V-shaped cross member design of the present embodiment also contributes to lower fan noise, thereby improving the operating environment.
(57) It will be appreciated that embodiments of the invention have been described above by way of example only, and variations in the design are possible. For example, various modifications of the cross member design are possible while still maintaining at least some of the advantages discussed above. In one example, rather than being grouped in pairs, the cross members are spaced apart around the adaptor.
(58) In general, at least some of the advantages of the present invention can be achieved by providing a plurality of angled crossings between the first flange member and the second flange member. The angled crossings can be provided in various different configurations, such as a “bird's nest” configuration, an evenly spaced configuration, a V-shaped configuration, an X-shaped configuration, or any combination thereof, or any other appropriate configuration.
(59) Although embodiments of the invention have been described with reference to a generator set, the present invention may be used with any type of power generation system where it is desired to connect a prime mover to a generator.
