AU2010235957A1 - An engine mounting arrangement - Google Patents

Description

1 P/00/011 Regulation 3.2 AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Invention Title: AN ENGINE MOUNTING ARRANGEMENT Applicant: Pacific Marine Batteries Pty Limited The following statement is a full description of this invention, including the best method of performing it known to me: 6067 DG 2 AN ENGINE MOUNTING ARRANGEMENT FIELD OF INVENTION The present invention relates to submarines and will generally be described in 5 this context. It is to be appreciated, however, that the invention may have application to other watercraft or other possible applications. The invention has particular application to the mounting of a diesel engine and/or ancillary equipment in a conventionally powered submarine. 10 BACKGROUND OF THE INVENTION Generally speaking, conventionally powered submarines are equipped with one or more diesel engines, which are connected to one or more generators. The electricity generated by the generator(s) supply electrical power to the various submarine operating systems, as well as to one or more electric motor(s) provided for 15 driving the submarine propeller(s) and may be stored in large, purpose built batteries within the submarine. The batteries may have overall mass of 100 tonnes or more. It is to be appreciated that a conventional submarine may be equipped with more than one diesel engine. The following discussion will be generally in the context of one diesel engine being provided, although such discussion may be equally 20 pertinent to a submarine equipped with two or more diesel engines. An important consideration in submarine design is to minimise the transfer of engine vibration into the surrounding water and to limit the transfer of vibrations into the submarine's own acoustic sensors either via direct transmission through the hull, onto which the acoustic sensors are mounted, or indirectly through the water. 25 Reducing the vibrations reduces the range at which an adversary can detect the submarine. Transmission of vibrations into the submarine's own acoustic sensors causes high background noise and reduces the ability of these sensors to detect other vessels and acoustic sources during the time the engines are running. In general terms, there are four mechanisms by which engine vibration can be 30 transmitted to the hull and the seawater: 1. Direct transmission of structural vibrations from the crankcase/mountings to the hull structure via any intermediate vibration mountings. 2. Transmission of airborne vibrations from the engine to the hull. 3. Transmission of vibrations of the engine assembly through hoses, cables 35 and other equipment that is connected to the engine at one end and the hull or an adjacent equipment platform, known as "noise short circuits".

3 4. Pressure pulsations from ancillary equipment through the fluid within pipes connecting the engine and surrounding hull and platforms. Mufflers may be fitted to reduce the pressure pulsations and these mufflers are desirably vibration isolated from the hull. 5 As will be understood, completely isolating or decoupling the engine from the hull structure would prevent any engine vibration being transmitted to the surrounding water. However, such an arrangement is impractical and thus engine vibration must be suitably dissipated away from the engine if the engine is to avoid sustaining 10 damage caused by engine vibration. Commercial engines have been designed for a particular level of vibration that the manufacturer selects. Substantial development effort is then expended to ensure that the engine and all its ancillary equipment are reliable; and engine installations must mount the engine in a way so as to fall within that tested vibration envelope in order to achieve reliable operation. Additionally the 15 mountings provide isolation of the diesel engine or other equipment and hull motion in response to external shocks (explosions). Consequently a compromise in the vibration isolation mounting design must be made between several design requirements. One prior art approach for reducing the transmission of vibration from the engine(s) to the hull includes a vibration isolation arrangement consisting of a system 20 of masses, springs and dampers. While an optimum configuration can often be theoretically designed, the available weight and space allocations within a submarine (particularly in the case of a conventional submarine) may be limited and thus impose limitations on the size and weight of the isolation mass. It would therefore be desirable to provide an arrangement whereby the level of engine vibration transmitted to the hull 25 is reduced, through the use of mass which is already contained and accounted for in the system. The use of inertial masses located either at each individual mounting point using single or double resilient isolators possibly in combination with a fixed inertial mass as part of the hull structure is well understood by the applicant. However, such 30 arrangements require the design of the mountings which involve a compromise between available space and weight allowances in the submarine design, reduction of the transmission of vibration from the engine to the hull and the maximum acceptable vibration of the engine. The compromise is necessary because the resilient mounts and structure absorb a relatively small proportion of the energy within the vibrations 35 generated, meaning that this energy must be either transmitted away from the engine or partially "retained" in the engine in the form of increased amplitude of vibration. As 4 such, vibration levels increase to levels where naturally energy dissipation mechanisms do absorb this energy, which in practical systems can exceed the desirable design envelope of the engine or vibrating equipment. Unfortunately, the size and mass of suitable inertial masses may be limited by available space, weight, 5 buoyancy and cost considerations which limit the possible technical solutions available to the vessel designer. It would be desirable to provide an engine mounting mechanism which mitigates, at least to some extent, one or more of the above-described mechanisms by which engine vibration can be transmitted to the surrounding water. In this respect, it 10 would be desirable to provide an engine mounting mechanism which either directly influences the noise signature(s) of the engine, or which provides a structural arrangement which ameliorates the size and mass limitations of prior art approaches without unduly compromising space, weight, buoyancy and cost considerations. The discussion of the background to the invention herein is included to explain 15 the context of the invention. This is not to be taken as an admission that any of the material referred to was published, known or part of the common general knowledge as at the priority date of this application. SUMMARY OF THE INVENTION According to one aspect of the present invention, there is provided a machinery 20 mounting arrangement for mounting machinery within a hull of a submarine. The mounting arrangement includes a mounting frame provided within the hull. The frame includes a machinery mounting surface for mounting the machinery thereon. The frame further includes an isolating mass (or inertial mass) supporting surface provided on the frame for mounting an isolating mass for at least partially isolating the vibration 25 generated by operation of the machinery. The isolating mass is in the form of at least one submarine battery. The mounting frame is mounted within the submarine hull by way of a vibration isolation arrangement extending between the frame and the hull. The at least one submarine battery may be mounted so as to contribute to the stiffness and/or strength of the mounting structure. 30 In a preferred form, the arrangement is provided for mounting one or more engines within the hull of a submarine. The mounting frame may be in the form of a raft or platform. The at least one submarine battery will typically comprise a high capacity lead acid battery, but batteries of other chemistry and technology may equally be used.

5 As will be explained in more detail following, in one embodiment the machinery is in the form of an engine, and the least one submarine battery includes plural lead acid batteries providing a combined mass of at least the same mass as the engine, generator, muffler and noise hood combined weight. It is to be appreciated, however, 5 that the combined mass of the batteries may be selected as desired, and so may be more or less than the amount referred to above. A battery mass of approximately twice that of the combined machinery mass or more is desirably achieved to maximise the effectiveness of the vibration isolation and is readily achieved using lead-acid batteries due to the relatively high density of such. 10 In the context of the present invention (and where the machinery is in the form of an engine), ancillary equipment mounted with the engine, or which is necessary for the engine's operation, may also be mounted on the mounting arrangement as this equipment contributes to the overall vibration spectrum. The type of engine contemplated would be a diesel engine, although the 15 invention contemplates use with other engine types and is equally suitable for improved isolation of any type of equipment that generates vibration such pumps, refrigeration units, air compressors, valves, motor driven equipment etc. The isolating mass supporting surface may merely support the isolating mass thereon. Alternatively, it may include a mounting arrangement for mounting the 20 isolating mass thereto, to secure the isolating mass in place. It is envisaged that the use of one or more of the submarine batteries as an isolating mass, may provide an effective way of limiting or even removing the possibility of any resonant frequencies of the engine (or other machinery) being excited and potentially causing damage to the engine. At the same time, it may substantially 25 limit the amount of vibration transmitted through the hull to the water. By increasing the limitations on the inertial mass from a standard configuration greater design freedom can be obtained; such that the system can be more effective over a wide range of engine operating speeds, and particularly at higher (or other specific) engine operating speeds. 30 In a preferred form, a vibration isolation arrangement is provided between the machinery mounting surface and the machinery for damping vibration generated by the machinery during operation thereof. Preferably, the frame includes an isolating mass supporting surface for supporting the isolating mass thereon. 35 Reference has, so far been made to the isolating mass including at least one battery of the type used to store the electricity generated by the submarine 6 generator(s). However, in a preferred form, the isolating mass includes a plurality of such batteries, with the particular number of batteries selected being at least partly dependent on the weight and size of the batteries and the total isolating mass required. One advantage in using the at least one submarine battery as an isolating mass is that 5 existing arrangements (not utilising batteries as an isolating mass) are limited due to space and weight constraints. Use of one or more submarine batteries as an isolating mass may require re design or at least modification of the lead-acid type batteries conventionally used in submarines, such that the batteries can withstand vibration generated by the 10 machinery. Design of the battery compartment structure would also have to be considered to ensure the vibration energy did not affect the performance of the battery, and that ancillary equipment and attachments to the isolated structure and the batteries did not cause noise shorts between the system and the hull. In one form, the isolating mass supporting surface is provided generally below 15 the machinery mounting surface for supporting the isolating mass below the machinery. Such a location is particularly suitable when the submarine batteries are used as the isolating mass. This is because in at least a number of existing conventionally powered submarines the batteries are located in the submarine at a level generally beneath that of the engine(s) and other machinery. 20 The isolating mass supporting surface may be configured as part of a cradle or compartment located below the machinery mounting surface such that the energy from the machinery is transferred to the cradle and energy dissipated via the movement of the mass and damper system The weight of the isolating mass may be selected as required, and may differ 25 depending on, for example, the specific weight of the machinery in question and particular mounting frame design adopted. It is envisaged that the weight of the isolating mass may be in the order of at least one times the machinery weight. In the context of the machinery being an engine, reference to 'engine weight', is generally understood to be the weight of the engine, 30 generator and component parts attached thereto, as well as the weight of any other components located on the engine mounting surface. In one particularly preferred form, the weight of the isolating mass is in the order of three times the weight of the machinery. It is to be appreciated, however, that the specific isolating mass weight may be selected to limit (or remove) the possibility of 35 the machinery being excited and damaged by resonant frequencies caused by the 7 machinery operation; while at the same time minimising the amount of machinery vibration transmitted outwardly fro the submarine into the surrounding water. The invention has so far been described in the context of a machinery mounting arrangement, and specifically an engine mounting arrangement configured for 5 mounting a single engine thereon. It may be desirable to mount two or more engines thereon, given that many existing submarine have more than one engine for powering the submarine generator(s). In such an arrangement, the weight of the isolating mass may be at least one times the combined weight of the engines. In one specific form, the weight of the isolating mass may be in the order of three times the combined 10 weight of the engines. Generally, conventional submarines include a large number of batteries, each weighing in the order of hundreds of kilograms or more. Thus, the combined weight of a suitable number of batteries would be sufficient to act as an isolating mass for two or more engines. In another embodiment, it may be that separate engine mounting arrangements 15 are provided for each of the submarine engines (or other machinery). In such an arrangement, a suitable number of batteries would separately act as an isolating mass for each of the engine assemblies. It is envisaged that the machinery mounting surface may be part of a machinery mounting platform. In such a configuration, a platform damping (or stiffening) 20 arrangement may be provided that extends between the mounting platform and the hull to further limit the potential of the submarine hull resonating in response to other stimuli. This arrangement is in preference to the machinery mounting platform extending all the way across the hull, and being connected at either side to the inside surface of the hull. This is because the proposed new arrangement provides the 25 potential to limit the amount of machinery vibration transmitted to the hull and then to the water surrounding the submarine, whilst concurrently retaining sufficient stiffness and energy absorption (either passive or active) to control hull vibrations. The mounting frame for the batteries may additionally be designed to provide compression to the plural battery cells which may assist with cell life and also holds or 30 "grips" the batteries in a tightly packed arrangement, in lieu of present methods of retaining plural battery cells against shock and submarine platform motion, such as wedging or bolting. In addition to gripping or holding the plural batteries in a tightly packed arrangement, the compression may also apply an external pressure to the case or housing of each battery which may have the effect of moving or displacing the 35 relative position of the internal plates of each battery by pushing or "squeezing" the plates together. It is envisaged that such an effect may assist in further improving the 8 resiliency and durability of the batteries in terms of their ability to withstand vibration. For example, the external pressure may generate an internal plate compression within each battery which may help "bind" the plates together and hold them against the case. In addition, the compression may also assist with retaining or holding the active 5 material onto the respective plates. Preferably, the engines are enclosed within noise hoods, which provide reduction of airborne noise transmitted to the hull and into the sea-water. The noise hood may be mounted to the engine or base frame such that the engine and noise hood are collectively mounted onto vibration and shock isolating mounting elements. 10 This improves the effectiveness of the noise hood in preventing transmission of noise and vibration to the hull but increases the weight of the vibration isolated equipment. In consequence, the size and weight of the corresponding vibration isolation elements and associated masses must also be increased to achieve the desired level of vibration isolation. Additionally it may be desirable to mount the engine muffler and 15 exhaust system onto the engine and noise hood assembly. This adds further additional mass and compounds further the effect of requiring increased mass of the vibration isolation masses. 20 DESCRIPTION OF THE DRAWINGS It will be convenient to hereinafter describe a preferred embodiment of the invention with reference to the accompanying drawings. The particularity of the drawings is to be understood as not limiting the preceding broad description of the invention. 25 Figure 1 illustrates a sectional end view of submarine incorporating an engine mounting arrangement in accordance with one aspect of the present invention. Figure 2 illustrates a sectional perspective view of the submarine and engine mounting arrangement of Fig. 1. Figure 3 illustrates a perspective view of one battery container arrangement in 30 accordance with the present invention. Figure 4 illustrates plan view of the arrangement illustrated in Fig. 3. Figure 5 illustrates a magnified view of the arrangement of Fig. 3. Figure 5a illustrates a slightly magnified side view of a wedge for use with the battery container arrangement illustrated in Figure 3. 35 Figure 6 is a plan view of a portion of a battery container arrangement in accordance with another embodiment of the present invention.

9 Figure 7 illustrates a perspective schematic view of another battery container arrangement in accordance with the present invention. Figure 8 illustrates a perspective view of another battery container arrangement in accordance with the present invention. 5 Figure 9 illustrates a perspective view of another battery container arrangement in accordance with the present invention. Figure 10 illustrates a magnified plan view of a portion of Fig. 9. Figure 11 illustrates a magnified perspective view of a portion of Fig. 9. Figure 12 illustrates a plan view of another battery container arrangement in 10 accordance with the present invention. Figure 13 illustrates a magnified view of a portion of Fig. 12. Figure 14 illustrates a perspective view of another battery container arrangement in accordance with the present invention. Figure 15 illustrates a perspective view of yet another battery container 15 arrangement in accordance with the present invention. Figure 16 illustrates a sectional side view of the arrangement of Fig. 15. Figure 17 illustrates a magnified perspective view of a portion of Fig. 15. Figure 18 illustrates a perspective view of submarine incorporating an engine mounting arrangement in accordance with another embodiment of the present 20 invention. Figure 19 illustrates a perspective view of submarine incorporating an engine mounting arrangement in accordance with yet another embodiment of the present invention. 25 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the Figures, there is illustrated a machinery mounting arrangement according to one possible form of the present invention. The arrangement is specifically configured as an engine mounting arrangement 10, although it may be configured for mounting other machinery. The mounting arrangement 10 is provided for 30 mounting the two illustrated diesel engines 12, 14 within a hull 16 of a submarine. Two engines 12, 14 are illustrated, but it is to be appreciated that the invention may be adapted for use with any practical number of engines (or other machinery) and in any specific layout within the submarine. The mounting arrangement 10 includes a mounting frame 18 provided within 35 the hull 16. The mounting frame 18 may be in the form of a steel fabricated raft or platform. The frame 18 includes an engine mounting platform 20 having a mounting 10 surface 22 for mounting the engines 12, 14 thereon. The platform may also be used to mount additional equipment 15, possibly including battery breaker cabinets and noise generating equipment. The mounting arrangement 10 is provided for reducing the transfer of engine 5 vibration to the water surrounding the submarine hull 16, as well as limiting any fundamental resonant frequencies of the engine from being excited and potentially causing damage to the engines 12, 14. The frame 18 also includes an isolating mass supporting surface 24 for supporting or, if preferred, suitably mounting an isolating mass 26 thereon. 10 The isolating mass 26 is comprised of a suitable number of batteries 28, typically these will be large lead-acid cells of the type generally used in submarines. The batteries 28 are used to store electrical energy generated by the submarine generator(s) for operation of the various operating systems and powering the electric motor(s) provided for turning the submarine propeller(s). 15 The specific design of the batteries 28 may be selected to ensure that their integrity isn't affected by being subjected to engine vibrations. The specific number of batteries 28 required to act as an isolating mass 26 would, in part, be dependant upon the weight of the engines 12, 14 in question and the weight and size of the batteries. The frame 18 is mounted within the submarine hull 16 by way of a vibration 20 isolation (or damping) arrangement 30 extending between the frame 18 and the hull 16. The precise form of the isolation arrangement 30 may be selected as desired within design limits of the isolators. It may, for example, include one or a combination of an anti-vibration engine mount, a vibration dampener (such as a rubber, hydraulic or other dampener), a vibration damping plate or the like. The isolation arrangement 30 may 25 also include one or more springs or spring-like members. It is envisaged that the use of an isolating mass 26 and isolation arrangement 30, at least at some engine operating speeds, may provide an effective way of limiting the amount of vibration transmitted through the hull 16 to the water. At the same time, the arrangement potentially reduces the level of vibration exposed to the engines 30 12,14, thereby reducing the likelihood of engine damage being caused as a result of those vibrations and exciting of associated resonant frequencies. A second vibration isolation arrangement 32 is provided between the engine mounting surface 22 and the engines 12,14 for additional isolation of the vibration generated by the engines during operation thereof. The isolation arrangement 32 may 35 adopt any suitable form.

11 Noise hoods may be directly mounted onto the isolation arrangement 32, or may be mounted onto the frame 18. It can be seen that the batteries 28 are provided in a cradle 34 generally below the engine mounting platform 20. Such a location is particularly suitable because, in at 5 least a number of existing conventionally powered submarines, the batteries are located in the submarine at a level generally beneath that of the engine(s). Thus, significant reconfiguration of a submarine interior may not be required to incorporate the invention. As such, the invention could be provided in new submarines, as well as potentially retro-fitted to existing submarines. The batteries 28 are packed in the cradle 10 34 to form a sufficiently rigid arrangement to effectively provide the isolating mass 26. It is envisaged that the weight of the batteries may be in the order of one to three times the combined weight of the engines (possibly including noise hoods, mufflers and possibly other items located on the surface 22). Again, the specific isolating mass weight may be selected to maximise the amount of vibration reduction 15 from the engines 12, 14 so as to reduce the vibration exposure of the engines 12,14; while at the same time minimising the amount of engine vibration transmitted outwardly from the submarine into the hull and surrounding water. A platform vibration isolation (or stiffening) arrangement 36 may optionally be provided that extends between the mounting platform 20 and the hull 16, so as to 20 further limit the potential of the hull 16 resonating at certain engine operating speeds. A flexible element may be provided to allow integration into the submarine. In this regard, a flexible rubber flat strap 37 forms a continuous part of the battery compartment and allows the engine mounted batteries 28 to be within the same physical space as the batteries that are mounted in a fixed arrangement on the hull 16. 25 The open hatch 37a would be part of the fixed section of the battery compartment, attached directly to the hull 16. An advantage of having all of the batteries 28 in the same physical space is that battery ventilation and maintenance access is common. Various preliminary calculations have been made to ascertain to potential effectiveness of the invention. Some of these are provided below, and include a 30 comparison of the present invention (identified herein as 'inertia block') with other possible arrangements (separately identified as 'single isolator' and 'double isolator'). These calculations include assessment of the affect of the mounting arrangements described herein and provide the stated improvement in vibration isolation in the case where the hull is effectively rigid and in the case where the hull is flexible and with 35 resonant frequencies within the range of interest.

12 Example vibration isolation element: Limits of damped isolation Assumptions - Gen-set speed 1500 rpm - Lowest excitation: M speed = 750 rpm;f= 12.5 Hz - Gen-set mass 15 t; distributed over 6 isolators - Maximum static deflection $ = ug/A 23 nni [Ref: Trelleborg Metalastic Super D] - Results - Lowest achievable natural frequency = -Hz - Lowest frequency ratio i=f/~ 3.8 " - Minimum transmissibility at 750 rpm. F /F= 0.08 (Q- 0.05) - Maximum attenuation at 750 rpm: 1 - F/F = 92% 13 inertia Block Tsolator f= Fsiiin(w) Assumptions S- 15 t gen-set - static deflections of all isolators same as for single isolator; 5t - 20 mm, say k koc (i.e., 3.5 H z) A44-- 2% isolator damping - it battery units , I + *- Investigate - mass ratios ./=- 1.5 and 3 (i.e, 20 or 40 battery units with supporting structure) Mass "Ma" represents battery system Mass "M" represents the engine and mounted on the raft or platform generator and associated equipment 40 twin-cell layout Metalastic 6 x Super D 15 t 17-1737 55H Alternative 14 x Super D 8 x Equi-Freq 45t 17-1738 55H 17-1472 60H CG-mounting CG-mounting 2m x 6m e- . 17 imi 4 12 ImmIII 4 =-3.8 ILz = 4.5 1z 14 Inertia block isolator TRANSMISSIBILITY: =0.02, I = 1.291. Ii. 1.5 10 ------ Inertia block 1.5 iglel Isolator 10 Alt, IL. -10 10 '10 10~ 10 Frequency ratio r~I 0 tnortin bloc smnCre igoiaor I R Ratio: 0.02, a fIr1 1.291, fMI a 1.5 10' 10 / - Oletler, thanf brigle -~ i 2ilor above 'N ~a10 10 10 10 Frequency ratio itIu 'no 2 r; 15 Inertia block considerably better than others above 6 Hz . Inertia block has lightly-damped peaks in force transmissibility at 3 Hz and 6 Hz - Gen-set motion amplitudes with inertia block are 25% higher at low frequencies (because of lower static stiffness), but are the same for all isolators at high frequencies (motion is then inertia controlled) - At high frequencies, inertia-block motion amplitudes are 1/45-th of double-isolator block amplitudes: hence superior force transmissibility Force transmissibility Fh / F Rigid hull 40 S--Double Isolator 20 --- - A-Single isolator Inertia block -20 -1 0 0 - -- - --- - -60 Effecst of solato

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20 - 1 4 0 -. .....7 RICIld hLJI 41,, 100...Effect of isolator ~. -*--I -14 10"1 100 101 10 10 Frequency f (Hz) Above slide shows comparison between ihe following designs 16 F F F M - Al 31 Af k k 0 cc 0 k=2k- c=2cO kkc 0 k 2co M

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k.=(I+p/)k 0 e pe 2% h 1 ~ Single Isolutor Double Isolator Inertia Block Indicative possible noise hood Non Rigid Hull mounting arrangement Force transmissibility Fh I F (Beam 6) 0O- Double isolator -X- Single isolator 0 ... ... ....-.- - -Inertia block -20 -..-.-............. S -40 ----- - ... . --- -- --- -- 4 ... - LL S -60 --- .

... ..... .. -80 Low frequency beam Bea 6 8T 2 Z[ -100

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0 ffect of isolator -140 10 10 10 10 10 Frequency f (Hz) 17 5 2 Gen-set (Y) and Intermediate-m ass (Y )dIsplacement response 5 10 ~ ~ I~:Raft vibration levels are 102 <111O,OOth of engine In 0 .10 ............. --- 1 0 -- --- - -- -- .. ... .I-- - - Double isolator Y 16 i 5 -Single Isolator Y ;r Battery Raft 1a 10s nrtia block Y ............. ~**. I.' response ----- Inertia block Y 1'100 101 1021 Frequencyf(Hz)_.

20 Calculated response: Caterpillar 3516 (2200kW/) pn Battery Raft Corhwilson oft~iei#atmForrnuellswalar Mass 25 .. Automotive lead-aci atr 1.OOE-0 -.... performance test range 0 ~.tofstor UnGOT 9uely AOjspbo,,artoark Ung FueTan(AVy3T) 30 1 .0OE-04 1.OOE-05 I .0OE-06 12 22 32 42 52 62 72 82 92 FrequnQ, (z) j: Raft vibration levels are order of 35 magnitude less than a full tank of fuel of same volume; 2 orders less (empty) 18 Figures 3, 4, 5 and 5a illustrate a possible wedging arrangement that allows the batteries (or cells) to be formed into wedged configuration. This arrangement positively retains the batteries within the cradle (not shown in these figures). In such an arrangement, the individual battery containers 38 contribute to the overall strength and 5 stiffness of the structure. The arrangement illustrated (which may be modified to suit a specific application) includes wedges 40 fitted in the grooves 41 provided at each corner of the containers 38. It is to be appreciated that more than one battery (or cell) may be contained in each container 38. The wedges 40 may have any suitable shape, taper and overall dimensions. 10 It is to be appreciated that the wedges 40 and retaining caps 43 are provided at the corner of each container. This provides advantages over more conventional wedging arrangements, wherein wedges fitted between containers mid-way along the container sidewalls. In this regard, minimal additional space is required within the cradle 34 (i.e. battery compartment) to accommodate the wedges, thereby more fully 15 utilizing the space in the cradle for the storage of batteries. Corner wedging utilizes the space usually left vacant at the corner of the containers 38. This is because typical battery manufacturing dimensions have container corners with a radius in the order of 5mm. Another potential advantage of corner wedging arrangements is that existing 20 arrangements can undesirably apply a high lateral force to retain the batteries within the cradle 34. Friction between the containers 38 is relied on to prevent the cells from moving under inverted or high roll/pitch angle operation. The corner wedging applies a physical retaining mechanism at each container 38. The wedging force required is much less, since friction is no longer the mechanism keeping the containers 38 in 25 place. The same type of wedge 40 and retaining cap 41 can be used along the walls of the cradle 34 to keep the batteries fully retained to the cradle walls (suitable mating shapes would typically be required in the cradle walls to match the positions of the wedges 40. It is to be noted that the wedges 40 would typically be installed by placing 30 a container 38 and then positioning the wedges prior to the next container being placed in position. That is, the wedges wouldn't typically be installed vertically from above, since there is insufficient height in the cradle 34. Instead, containers are packed in the cradle 34 with loosely fitted wedges, until the last container is lowered through an open hatch (not shown) into the cradle 34. The final wedges are then placed in position 35 through the open hatch.

19 Corner wedging of the containers 38 requires a relatively low wedging force, since the wedges need only be applied with sufficient force to remove clearances. That is, there is no need for friction to be used to hold the containers 38 in place within the cradle 34. This can be achieved by applying a simple downwards force on the wedges 5 40 and allowing any minor vibration or movement to tighten the fit of each wedge 40. Figure 6 illustrates a sample confirmation in which the corners of four separate containers 38a meet, with free space indicated by 45 there between. Figure 7 illustrates one possible layout of a mounting frame 18, in the form of a steel fabricated raft. The raft is slung underneath machinery (such as a diesel 10 engine(s)). The raft is configured to provide sufficient stiffness to provide the vibration isolation desired but may allow a significant degree of flexibility in twisting and bending. The raft is suspended on multiple flexible isolating mounts indicated by example reaction force locations 42. Figure 7 also illustrates battery containers 38b, located within a battery 15 compartment 39, with the compartment being manufactured from a fabricated steel structure and mounted to a raft 35. The containers 38 must either withstand the amount of twisting and bending of the raft 35 and compartment assembly, or be attached sufficiently strongly to the raft 35 to contribute to the overall stiffness and strength. The containers 38b may be 20 designed to fit tightly together but avoid abrasions by using either a "fiberglass spacer" option, or other wedging options, but with the wedge material being flexible (eg. rubber or plastic). The use of a flexible material would contribute to the overall damping of the structure. In one preferred form, the containers 38b are manufactured from fiberglass, which would provide useful stiffness to the arrangement, in addition to the wedging 25 arrangements referred to above. In one particularly preferred form, the compartment 39 may be of a fabricated steel construction, possibly having light-weight steel sheeting to fully enclose the batteries. The containers 38b may be attached to the side panels of the compartment 39. 30 Figure 8 illustrates one possible layout of the battery raft assembly, with the batteries fitted. All batteries (and wedges) are installed down through the hatch 44. A panel 46 covering the cradle 34 (ie. battery compartment) is illustrated elevated, but would typically be permanently fitted in position flush with the machinery mounting platform 20. 35 Figures 9, 10 and 11 illustrate another possible arrangement, whereby vertical separators 48 are used between the batteries/containers 38c. The separators 48 are 20 parallel sided strips that are placed between containers 38c at locations where the containers 38c are stiff, such as near the container corners and internal separator ribs, thereby transferring load to the container 38c. The separators 48 allow possible relative movement between the containers 38c, but without the containers 38c rubbing 5 and abrading. It is envisaged that wedges (not illustrated) would also be fitted between the outer layer of containers 38c and the adjacent wall. The function of the separators 48 may be similar to that of the wedges 40 illustrated in Figures 3 to 6 or may be parallel items, transferring twisting and bending forces from the cradle (not shown) to the containers 38c. The separators 48 are shaped to allow some rolling contact 10 between the separator 48 and the container 38c, without abrasion occurring between adjacent containers because of relative movement there between. The separators 48 are placed in a vertical groove 50 provided in the outer side of the container walls 52. The groove 50 may be approximately semi-circular, and the cross-sectional shape of the separators 48 may be approximately elliptical, or with a 15 smaller tip radius than the groove 50. Figures 12 and 13 illustrates another possible wedging arrangement with aligned and tapered wedging slots 52a,52b provided in the sidewalls of adjacent containers 38d for receiving a wedge 40d. This arrangement seeks to hold the containers together as a single mass, rather than wedging them outwardly towards to 20 surrounding cradle (or container) walls. The containers 38d would typically be manufactured from plastic reinforced fibre. Suitable strengthening of the container walls may be provided, particularly at/adjacent the slots 52a,52b. With wedges fitted into slots, a cam locking arrangement (or similar) in the form of a bolted plate arrangement 54 could then fitted to prevent loosening and separation 25 of adjacent containers 38a,38b, as illustrated in Figure 14. A more complex locking arrangement is illustrated in Figures 15, 16 and 17, wherein the lower corners 56 of adjacent containers 38e are received in foot-wells (or shoes) 58 provided on the underlying cradle floor 60e. The corners of adjacent containers 38e are then secured together by way of a locking bolt 62 extending 30 downwardly and being fastened to an upwardly facing threaded bore 64 integrally formed on the foot-well 58, thereby preventing relative movement of the containers 38e. Figure 18 illustrates a further possible arrangement, whereby the cradle floor 60f approximately follows the curvature of the hull 16f. 35 Figure 19 illustrates another possible arrangement in which three diesel engines are mounted side-by-side, with each engine provided with a separate battery 21 cradle 34g, 34h, 34i. The cradles 34g, 34h, 34i may be rigidly connected together (using any suitable arrangement), such that the cradles display the characteristics of a single cradle. Alternatively, the cradles 34g, 34h, 34i may not be connected together but individually mounted via springs or resilient mounts to the submarine hull. 5 The present invention potentially provides an arrangement whereby potentially harmful engine vibration is at least partially transferred away from the engine. The invention also potentially provides an arrangement whereby engine vibration is isolated to the extent that it is at least partially prevented from being transmitted to the surrounding water, thereby making the submarine potentially more 10 difficult to detect when at sea. During submarine design, it may not possible to fit a noise hood over the diesel engines because of the placement of the engines, the lack of available space surrounding the engines and the lack of a suitably vibration isolated structure on which to mount the noise hood itself (since energy transmitted into the noise hood will at least 15 partially be transmitted to its own mounting arrangement and must be isolated from hull structure). The present invention advantageously allows for noise hoods to be fitted over the engines either individually or as a group, due to the size and mass of the battery-based inertial mass, that is substantially greater than would be possible using fixed inertial mass alone and provides a simpler arrangement for mounting such a 20 noise hood than individual mounting of engines. The invention may allow reduction of noise short circuits. Hoses, cables, exhaust ducting and the like that connect to the generator and the diesel engine are necessarily quite large and stiff in order to carry out their primary function. This allows vibrations to travel though these cables and attachments to other equipment, platforms 25 and hull. Particular examples include the exhaust piping, large cables required for carrying the electrical current and possible seawater cooling pipes to pumps and/or hull outlets. These are necessarily stiff to perform their primary function but most preferably must not provide a noise or vibration short circuit. Using one or more of the submarine batteries as an isolating mass desirably reduces the amount of noise/vibration 30 transmitted through the cables. This is because the cables are not connected to batteries which are physically closely coupled to the hull, or to cables that are mounted on adjacent platforms or hull structure before they connect to the batteries. This would allow the main cables that connect the battery (as part of the isolation system) to the hull to potentially have to handle only the relative motion/vibration between the battery 35 isolating mass and the hull, which is very much less than then between a diesel 22 engine/generator and the hull. This principle is applicable to other fluid and electrical systems. Finally, it is to be understood that the invention may also be applied to mounting of any equipment that produces vibrations and that various alterations, 5 modifications and/or additions may be introduced into the construction and arrangement of the parts previously described without departing from the spirit or ambit of this invention.

Claims (23)

1. A machinery mounting arrangement for mounting machinery within a hull of a submarine, the mounting arrangement including: 5 - a mounting frame provided within the hull, the frame including a machinery mounting surface for mounting the machinery thereon; - an isolating mass supporting surface provided on the frame for supporting an isolating mass in the form of at least one submarine battery, the isolating mass provided for reducing the transmission of vibration from he machinery to the 10 hull; and - the mounting frame mounted within the submarine hull by way of a vibration isolation arrangement extending between the frame and the hull.

2. A machinery mounting arrangement according to claim 1, wherein the 15 arrangement is for mounting at least one engine within the hull of a submarine.

3. A machinery mounting arrangement according to claim 1 or 2, wherein the mounting frame includes a raft or platform. 20

4. A machinery mounting arrangement according to any one of the preceding claims, including a vibration isolation system between the machinery mounting surface and the machinery for reducing the transmission of vibration generated by the machinery during operation thereof. 25

5. A machinery mounting arrangement according to any one of the preceding claims, wherein the isolating mass supporting surface is provided generally below the machinery mounting surface for supporting the isolating mass below the machinery.

6. A machinery mounting arrangement according to claim 5, wherein the isolating 30 mass supporting surface is configured as a cradle or compartment located below the machinery mounting surface.

7. A machinery mounting system according to any one of the preceding claims, including machinery in the form of an engine or engine assembly, mounted on the 35 machinery mounting surface and an isolating mass supported on the isolating mass 24 supporting surface, wherein the isolating mass has a weight at least one half times the weight of the engine or engine assembly.

8. A machinery mounting system according to claim 7, wherein the weight of the 5 isolating mass is up to approximately three times the weight of the engine or engine assembly.

9. A machinery mounting system according to claim 7 or 8, including a plurality of engines or engine assemblies mounted on the engine mounting surface. 10

10. A machinery mounting arrangement according to claim 9 when dependent directly or indirectly on claim 6, wherein each engine or engine assembly is provided with a separate mounting surface, with each mounting surface having a respective cradle. 15

11. A machinery mounting system according to claim 9 or 10, wherein the weight of the isolating mass is up to approximately three times the combined weight of the engines or engine assemblies. 20

12. A machinery mounting system according to any one of claims 1 to 6, including machinery mounted on the machinery mounting surface and an isolating mass supported on the isolating mass supporting surface, wherein the isolating mass has a weight at least one half times the weight of the machinery. 25

13. A machinery mounting system according to claim 12, wherein the weight of the isolating mass is up to approximately three times the weight of the machinery.

14. A machinery mounting system according to any one of the preceding claims, wherein the isolating mass includes a plurality of batteries. 30

15. A machinery mounting system according to any one of the preceding claims, wherein the machinery mounting surface forms part of a machinery mounting platform, the machinery mounting system further including a platform vibration isolation arrangement extending between the mounting platform and the hull. 35 25

16. A machinery mounting system according to any one of claims 1 to 15 wherein the at least one submarine battery is mounted to contribute to the stiffness and/or strength of the mounting structure. 5

17. A machinery mounting system according to any one of claims 1 to 16 wherein the at least one submarine battery includes a plurality of batteries arranged in a tightly packed configuration to form a single mass unit.

18. A machinery mounting system according to claim 6, or any one of claims 7 to 10 17 when appended to claim 6, wherein the at least one submarine battery includes plural batteries, and wherein the mounting cradle or compartment is sized to exert a holding force on the plural batteries, said holding force for restricting movement of the plural batteries caused by vibration. 15

19. A machinery mounting system according to claim 18 wherein the holding force compresses the case of each battery at least to some extent.

20. A machinery mounting system according to claim 6, or any one of claims 7 to 19 when appended to claim 6, wherein one or more adjacent batteries are secured 20 together within the cradle to limit relative movement of the batteries.

21. A machinery mounting system substantially as herein described and illustrated.

22. A method of providing a mounting arrangement for mounting machinery within 25 a hull of a submarine, the method including: providing a mounting frame within the hull, the frame including a machinery mounting surface for mounting the machinery thereon; providing an isolating mass supporting surface on the frame for supporting an isolating mass in the form of at least one submarine battery, the isolating mass for 30 reducing the transmission of vibration from the machinery to the hull; and mounting machinery on the mounting surface.

23. A method according to claim 22 further including configuring the combined mass and/or arrangement of the at least one or submarine battery to provide an 35 effective vibration isolation arrangement between the frame and the hull for attenuating vibration generated by the machinery when in use.