Abstract:
A lubrication apparatus for lubricating a surface of at least one component of a piece of equipment, which includes a lubrication mist generating unit in which air and a lubricant are combined to form a lubricant mist. A device is included for directly connecting the lubrication mist generating unit to the equipment at a position adjacent the surface to be lubricated.

Description:
FIELD OF INVENTION  
       [0001]    The present invention relates to the lubricating of bearings with an oil mist formed by combining oil and air. 
       BACKGROUND OF THE INVENTION 
       [0002]    For many years centralised oil mist lubrication systems have been used to provide continuous lubrication to rotating equipment bearings. Oil mist lubrication gives benefits over other lubrication methods, providing:
       reduced heat generation by the rotating elements   reduced equipment power consumption   reduced wear of the rotating and stationary elements   lower oil consumption, and   positive pressurisation of the bearing housing to prevent the ingress of particulate contaminant and moisture.       
 
         [0008]    Oil mist lubrication is of use in many situations including with modern bearing seals such as magnetic face seals. 
         [0009]    However, oil mist systems may be difficult to justify because of their cost, complexity and commissioning time. 
         [0010]    U.S. Pat. No. 5,318,152 discloses a lubricating system in which a plurality of bearings of one or more bearing equipped items are lubricated from a centralised oil mist generator. This system includes an oil mist generator, a distribution assembly for distributing the oil mist from the oil mist generator to the bearings, a collective device for collecting excess oil and oil mist from the bearings and a return assembly through which excess oil and oil mist are returned to an oil mist collection/supply vessel for re-use. 
         [0011]    This system therefore relies on components, which are additional to the bearing housing. This centralised approach is not only costly, as it requires the additional components, but it also:
       takes up considerable physical space,   requires extensive commissioning time and expertise,   gives rise to costs to run distribution pipework, in industry, in excess of US$100 per foot, given all the resources required not only to plan and approve such a pipework network but also maintain it.   represents a compromise solution given that oil mist is distributed from a centralised system to multiple types of equipment, such as electric motors, pumps, and gearboxes. Since the lubrication requirements of each type of equipment vary with bearing size, number of rolling elements and speed of operation, a compromised/non-idealised oil mist flow must be selected. This also means that the base oil type selection has to be compromised, since some types of equipment require different oil characteristics, for example, gearboxes may need oil anti-spalling and/or wear properties, pumps may need reduced rust formation properties, and motors may need an oxidisation inhibitor.   when equipment is replaced with different sized equipment, centralised systems offer little flexibility, or oil misting conditions are never changed in practice to meet the requirements for the replaced equipment.   centralised systems, containing venturi/vortex generation heads are often over sized since engineers wish to anticipate the future additional equipment needs. Unfortunately, this creates a far from ideal operation, and mist delivery is compromised as large generator heads create larger oil mist particles which then coalesce in the pipework before reaching the equipment   coalescing oil can interfere with the mist distribution in a centralised oil mist system, leading to blockage at the source. Clearly as the centralised systems supply multiple pieces of equipment a blockage leads to these multiple pieces of equipment failing which is clearly a very risky and costly operation.   distribution pipework, from a centralised system, must be inclined from the source, so to allow coalesced oil mist to run back to the source under gravity. This requirement causes practical difficulties in an industrial plant with equipment positioned in different three-dimensional locations. It is practically impossible to implement a suitably inclined pipe distribution system, which satisfactorily meets this requirement.   centralised systems can only feed equipment in an approximate 500 m radius given that oil mist coalesces at the interior surface of the pipework prohibiting longer distribution runs.   multiple reclassifier nozzles lead to confusion, misapplication and installation errors. Many oil mist installations fail because of simple errors from the system suppliers and those involved in selection, set-up and configuration. Laws of probability state that complex systems create more problems. Centralised systems can only be described as complex.       
 
       STATEMENTS OF THE INVENTION  
       [0022]    Thus according to the invention, there is provided a lubrication system for lubricating the surfaces of one or more components of a piece of equipment, the system comprising a lubrication mist generating unit, in which air and a lubricant are combined to form a lubricant mist, and a means for directly connecting the unit to said piece of equipment at a position adjacent to said surfaces. 
         [0023]    Thus, there are no intervening conduits or other items between the housing within which the oil mist is generated and the equipment to be lubricated apart from, for instance, as outlet from the housing which makes a screw-threaded or other connection with an inlet of the equipment. 
         [0024]    Preferably, the piece of equipment is a bearing structure which includes a bearing bushing and one or more bearings for supporting a rotating shaft of, for instance a pump. Preferably, said two or more surfaces are counter-moving and said lubricant mist provides lubrication to said surfaces. 
         [0025]    Preferably, said counter-moving surfaces are in the form of a bearing 
         [0026]    Preferably, said lubrication mist generating unit is attached directly to the bearing housing, containing a bearing and a longitudinal shaft 
         [0027]    Preferably, said lubrication mist generating unit is adapted to be directly connectable to a port provided in the radial wall of the bearing housing. In conventional systems, such as is shown in  FIG. 1 , a port or orifice is provided within the wall of the bearing housing in order to allow for the filling and maintenance of lubricant levels with the housing. This port may be capped or fitted with an expansion device. 
         [0028]    Preferably, said lubrication mist generating unit includes a conduit or pipe, which extends from said unit to a lubricant reservoir located within the piece of equipment. Preferably, said reservoir is an integral part of the bearing housing. 
         [0029]    Preferably, the system includes a lubricant mist return which extends from the bearing housing to the mist generation unit, thereby creating a substantially closed loop system wherein the used lubricant mist is re-circulated to the lubricant mist generating unit. 
         [0030]    Accordingly, the present invention provides apparatus designed to connect directly into an existing bearing housing structure, thus providing individual and local oil mist generation for each item of rotating equipment. 
         [0031]    This system of the invention removes the need for:
       additional components, for example, vessels for storage of the lubricant and/or generated oil mist.   costly distribution and return (if applicable) pipework systems, involving planning and commissioning are eliminated, as are the impracticalities of having to incline said pipework from the central source.   the ideal/correct oil grade can be individually selected to suit each item of rotating equipment, without compromise.   the complexity and misplacement of localised reclassifiers in a centralised system is eliminated.   baffle blockage from wax formation, thermal decomposition or sludge is eliminated/reduced, as is the risk of failing multiple items of rotating equipment from a centralised blockage, and   issues and drawbacks surrounding oversizing of a centralised system to accommodate future plant expansion needs.       
 
         [0038]    It is also of advantage if the localised system of the inventions further provides:
       an integral oil mist debris catcher   localised oil reservoir for a quick start supply to the application   washable, life-long filtration, not material based filtration with a finite short life expectancy, and   integral non-return valve, preventing filtered flow of air/mist to escape to atmosphere when in operation, but the prevention of air and moisture entry when system is not in operation, thus replacing the need for a separate expansion chamber when oil mist supply is not required. A modular unit which can either be employed to generate oil mist or to be used as an expansion chamber provides technical and commercial advantages to the user and supplier.       
 
         [0043]    For clarity, the terms reservoir, lubricant sump and lubricant reservoir are synonymous as used herein. 
         [0044]    In one embodiment of the present invention, a reservoir unit is directly connectable into the mist generating unit. 
         [0045]    In another embodiment of the invention, a reservoir unit is directly connectable into the bearing housing. 
         [0046]    Preferably, the reservoir has a clear, see-through construction, so that a user can determine the lubricant level within said reservoir. 
         [0047]    Preferably, lubricant mist is provided by air entering a vortex device within the lubrication mist generating unit on oil supply being provided adjacent to the vortex device whereby vortexed air mixes with the oil and forms a mist. 
         [0048]    Preferably, an air feed means extends between the vortex device and an air supply, more preferably in the form of at least one constricted channel, said constricted channel entering said vortex device in a substantially tangential manner. 
         [0049]    The sides of said constricted channel may be substantially parallel in width and depth, or they may be inclined to each other. 
         [0050]    Preferably, two or more air vortex means are provided in the lubricant mist generating unit. 
         [0051]    Preferably, lubricant mist is provided by air entering a venturi of the lubrication mist generating unit, and adjacent to said venturi is an oil supply, said venturied air being mixed with said oil and forming a mist. 
         [0052]    Preferably, said mist directly communicates with the innermost radial surfaces of said bearing housing. 
         [0053]    Preferably, said oil is contained in a reservoir adjacent to said mist generation means. 
         [0054]    Preferably, the means for re-circulation of the used lubricant mist comprises a second air stream which creates a low pressure within the lubricant mist generating unit inducing a flow of the lubricant mist back into the unit. 
         [0055]    Preferably, said lubricant mist generating unit contains a mist return orifice which communicates to a venturi cavity, said venturi cavity also communicating with the second air stream. 
         [0056]    Preferably, said venturi cavity contains at least one substantially conical surface. 
         [0057]    Preferably, said air supply is delivered through the innermost radial surface of said venturi cavity and said lubricant mist return is delivered to the outermost radial surface of said venturi cavity. 
         [0058]    Preferably, the apparatus includes a filter, through which the lubricant mist must pass in order to escape to atmosphere. Preferably, said filter is an integral member of the lubricant mist generating unit. 
         [0059]    Preferably, said filter is of substantially metallic construction, more preferably of micron size porosity between its innermost and outermost surface. Preferably, said filter coalesces said lubricant mist into a lubricant fluid. 
         [0060]    Preferably, a non-return means is provided adjacent to said filter, so that filtered mist/air can vent, yet atmospheric air/moisture can not enter past said non-return means. 
         [0061]    Preferably, a communication means is provided to allow said coalesced lubricant fluid to return to the reservoir. 
         [0062]    Preferably, at least one magnet is provided in said reservoir to attract any metallic debris in said lubricant. 
         [0063]    Preferably, an intelligent lubrication system is provides by the use of at least one monitoring device which detects a system upset and alerts the user. 
         [0064]    Preferably, said monitoring device monitors the flow of the returned mist back into the lubricant mist generating unit and provides an alert when a no/low flow is detected. 
         [0065]    Preferably, said monitoring device monitors the level of the lubricant in the reservoir and provides an alert when a low lubricant level is detected. 
         [0066]    More preferably, the system is intelligent and auto-corrective and the detection of a no/low mist return flow activates a regulator, which increases the air flow/pressure to the mist generation unit which thus increases the mist return flow and resets the low flow monitoring device. 
         [0067]    Most preferably, the system is intelligent and auto-corrective and the detection of a low lubricant level in the reservoir induces corrective flow of replacement lubricant into the system, which thus increases the lubricant level and resets the low level monitoring device. 
         [0068]    Preferably an adjustable throttling means is provided to regulate the air supply and/or mist flow. 
         [0069]    Preferably, an air filtration system is provided to control the quality of the air supply to the lubrication mist generating unit. 
         [0070]    Preferably, a lubricant refill means is provided in the lubricant mist generation unit, said refill means consists of a communication channel from the outermost surface of said mist generation unit to the bearing housing and/or reservoir. 
         [0071]    Preferably, the apparatus contains no moving parts. 
         [0072]    Preferably, the apparatus of the invention is employed on a bearing housing which contains sealing elements which contain the lubrication mist within said bearing housing. 
         [0073]    In a preferred embodiment, the above described apparatus employed with the reservoir of the bearing housing, removes the need for additional vessels for the storage of the lubricant and/or generated mist, distribution piping for the lubricant and lubricant mist and connection means between the distribution piping and the aforesaid vessels. 
         [0074]    Oil mist generated in the system of the invention comprises oil mist droplets of 1-10 microns in size, preferably in the range of from 1-3 microns in size. As a result of this small droplet size the contaminants that can cause bearing failure will not remain in the lubricant mist suspension and the oil mist has therefore been described as the ultimate oil filter. 
         [0075]    In addition pure oil mist has been found to deposit a wear resistant, carbonaceous dry film on the wear surface of the bearings. This carbonaceous layer enables the machinery to operate safely for up to 8 hours even when the flow of oil mist fails. 
         [0076]    Oil mist can be applied in two formats; Pure mist, dry reservoir, or where the lubricant fluid level below the bearing and no splash lubrication means provided, or 
         [0077]    Purge mist, wet reservoir lubrication, where the lubricant fluid level is in contact with the bearing or where the lubricant fluid is below the bearing and a splash lubrication means is provided. 
         [0078]    In the apparatus, according to the present invention, the bearing housing is filled with a combination of fluid lubricant in the reservoir and an aerosol/mist of the lubricant above the fluid level and provided by the lubricant mist generating unit. The level of the liquid lubricant within the housing of the invention determines whether the system operates in purge or pure mode. 
         [0079]    In one embodiment of the invention the apparatus operates in the pure mode. In an alternative embodiment of the invention the system operates in the purge mode. In a further preferred embodiment of the invention the operation of the apparatus is switchable between the pure and the purge modes and this is dependent on the level of liquid lubricant present. 
         [0080]    In some modes of operation it may be preferable for the air and/or lubricant to be pre-conditioned prior to entry into the lubricant mist-generating unit. For example the air and/or lubricant is heated, cooled or filtered prior to entry into the lubricant mist generating unit and the system is provided with appropriate means for doing this. 
         [0081]    In a preferred embodiment of the invention, the lubricant provided within the system is oil and since each reservoir is equipment specific, each lubrication media, or grades of media/oil, can be selected according to the specific equipment requirements. 
         [0082]    The lubricant mist-generating unit is preferably connected into the top of the bearing housing to form a lubricant mist-generating head. Alternatively the lubricant mist-generating unit is connected into a sidewall of the bearing housing. 
         [0083]    According to a further aspect of the invention there is provided a method for lubricating a bearing with a lubricant mist comprising the steps of;
       i) connecting a lubricant mist generating means directly into a bearing housing;   ii) connecting an air supply to the mist generating means;   iii) connecting a lubricant media feed means to the mist generating means, and, optionally, connecting a mist return means to the mist generating means;   iv) filling the reservoir with the lubricant media;   v) activating the air supply to the mist generating means.       
 
         [0089]    By means described above, the present invention removes a substantial amount of costs, complexity, risk and commissioning time to the user compared to traditionally centralised misting systems. Additionally the inherent design allows for a direct migration path for the user from traditional lubrication to a purge or pure system, and back again, if deemed necessary, without major cost or major system/equipment modifications. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0090]      FIG. 1  shows a part longitudinal cross section of the bearing chamber of a centrifugal pump with traditional non-contacting labyrinth seals, with inlet orifice in said chamber for mist entry; 
           [0091]      FIG. 2  corresponds to  FIG. 1  and shows a longitudinal cross section of the bearing chamber of a centrifugal pump, with apparatus of the invention attached to said inlet orifice; 
           [0092]      FIG. 3  corresponds to  FIG. 2  and shows an alternative configuration of the invention with apparatus of the invention attached to another bearing housing orifice, providing mist purge means through the bearings; 
           [0093]      FIG. 4  shows a longitudinal part cross section of an electric motor with the apparatus of the invention attached to a reservoir, in turn attached to the motor; 
           [0094]      FIG. 5  shows a longitudinal part cross section of a pillow block with apparatus of the invention attached to an upper orifice, a reservoir being attached to the bearing housing; 
           [0095]      FIG. 6  shows a longitudinal cross section of the mist generation unit of the invention; 
           [0096]      FIG. 7  corresponds to  FIG. 6  and shows the view on Section X-X; 
           [0097]      FIG. 8  also corresponds to  FIG. 6  and shows an alternate view on Section X-X; 
           [0098]      FIG. 9  shows a longitudinal cross section of an alternate mist generation unit of the invention; 
           [0099]      FIG. 10  corresponds to  FIG. 9  and shows the view on Section Y-Y; 
           [0100]      FIG. 11  corresponds to  FIG. 6  and shows an option to remotely add lubricant fluid into the system to increase the lubricant fluid level in the reservoir; and 
           [0101]      FIG. 12  corresponds to  FIG. 6  and shows an option to add a mist return flow-monitoring device which detects a no/low flow condition and alerts the user. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0102]    The invention will now be described, by way of examples only, with reference to the accompanying drawings. 
         [0103]      FIG. 1  shows an item of rotating equipment, such as a centrifugal pump  10  (not shown), with a rotating shaft  11  and a stationary bearing housing  12 . The bearing housing  12  houses bearings  13  and  14  which are radially connected to the shaft  11 . The shaft  11  is also rotationally coupled to bearing seals  16  and  17  and said bearing housing  12  contains a bearing lubricant fluid in traditionally supplied mist form  18 , which lubricates and cools the bearings  13  and  14  during dynamic operation of the rotating equipment  10 . 
         [0104]      FIG. 2  is similar to  FIG. 1  and illustrates a first embodiment of the invention, in which a lubricant mist generating unit  21  is attached directly to the bearing housing  12  via an appropriate orifice  22 . 
         [0105]    At the bottom of the bearing housing  12  is an integral reservoir  23  which is commonplace in most items of rotating equipment. Bearing lubricant fluid  24  is added to the reservoir until the desired fluid level is reach, depending if the application is intended to run in pure or purge mode. 
         [0106]    An air supply  30  is connected to the lubricant mist generating unit  21 , and feed line  31  is connected from the lubricant mist generating unit  21  to communicate with the fluid in the reservoir  23 . 
         [0107]    Preferably, although not essentially, a mist return line  32  is connected from the bearing housing  12  to the lubricant mist generating unit  21 . 
         [0108]    Preferably, seals  33  and  34  are employed to retain the lubricant mist  35  in the bearing housing  12 . 
         [0109]    In operation, air  30  is fed to the lubricant mist generating unit  21 . The mechanisms inside the lubricant mist generating unit  21  create a puffing action to suck the lubrication fluid  24 , in the form of an oil, from the reservoir  23  along the feed line  31  to the lubricant mist generating unit  21 . 
         [0110]    Oil  24  is then mixed with the air  30  inside the lubricant mist generating unit  21  and oil mist  32  is formed. The mist  32  then enters the bearing housing  12  and lubricates the bearings  13  and  14 . 
         [0111]    Oil mist  24  is encouraged to return back to the lubricant mist generating unit  21  via the return line  32 . The returned oil mist  32  is filtered and coalesed fluid oil  24  returns via gravity to the reservoir  23 . 
         [0112]    The above described configuration is a closed loop oil mist system operating with a blanket mode; the oil mist  32  fills the bearing housing  12  and is not forced through the bearings. 
         [0113]      FIG. 3  shows a second embodiment of the invention, in which the lubrication system, as previously described, has the lubricant mist generating unit  21  connected to one longitudinal side of the bearing  13 . 
         [0114]    The mist return line  40  is connected to the opposite longitudinal side of the other bearing  14 . 
         [0115]    Therefore, oil mist  41  entering the bearing house  42  is forced through both sets of bearings  13  and  14  before it can return back to the lubricant mist generating unit  21  via the return line  40 . 
         [0116]      FIG. 4  shows a longitudinal part cross section of an electric motor  45  with the lubrication system of the invention  46  attached to a reservoir  47 , which is in turn attached to the motor  45 . 
         [0117]    A limited number of types of equipment do not have the integral reservoir option. In such cases, the embodiment of the invention provides for an attached equipment reservoir  47  substantially adjacent and beneath the lubricant mist generating unit  48 . The system thus provides local mist  49  supply to the equipment bearings  50  and  51 , then is returned back to the lubricant mist generating unit  48 . 
         [0118]    Preferably, the attached equipment reservoir  47  is manufactured from a see through material such as transparent UV stable plastic. This provides the user with a visual check to determine the level of the lubrication fluid  52  in the reservoir  47 . 
         [0119]      FIG. 5  shows, by way of example only, a longitudinal part cross section of a pillow block  60  with the lubrication system of the invention  61  attached to an upper orifice  62  of the pillow block  60  and an attached equipment reservoir  63  attached to the lower orifice  64  of the pillow block  60 . 
         [0120]      FIG. 6  shows a longitudinal cross section of a mist generation unit  70 , suitable for use in the above described embodiments. 
         [0121]    The mist generation unit  70  incorporates a outer body  71  and an end cap  72 . Preferably, the end cap  72  is attached to the outer body  71  by a suitable detachable means. As shown, by way of example only, said end cap  72  is screwed  69  into the body  71  and two flats  73  are provided and the end cap to assist both parts to be tightened together. 
         [0122]    Located in the outer body  71  is a vortex plate  75  which is preferably sealed to said outer body  71  by elastomer  76 . 
         [0123]    Clamp plate  77  sits adjacent to the vortex plate  75  and again is preferably sealed to the outer body  71  by elastomer  78 . 
         [0124]    The vortex plate  75  incorporates a substantially conical hole  79  in its most radially inner portion. At least one enclosed communication slot  80  feeds air  81 , entering the assembly through a suitable first outer body orifice  82 , into the conical hole  79 . 
         [0125]    Simultaneously, a second air flow  85  is directed through the innermost radial portion  86  of venturi nozzle  87  creating a pressure differential to the outermost radial portion  88  of venturi nozzle  87 . Preferably venturi nozzle  87  is sealed to outer body  71  by elastomer  83 . 
         [0126]    A second outer body orifice  89  communicates with the most outer radial portion  88  of venturi nozzle  87 . A mist return line  90  is connected to said second outer body orifice and a suitable orifice on the bearing housing (not shown). 
         [0127]    An oil feed line (not shown) is connected from a third outer body orifice  91  to the reservoir (not shown). 
         [0128]    In operation, the air  81  increases in velocity as it travels through the conical hole  79  and into communication orifice  84  and the bearing housing (not shown). This in turn has a pulling effect on the lubrication fluid from the reservoir, thus pulling it through the feed line, through the third outer body orifice  91  and into the oil second reservoir  92 , which is a radially extending recess in outer body  71 . 
         [0129]    Preferably inserted in said recess is at least one magnet  93  which acts to attract any metallic debris in the lubrication fluid thus filtering it. 
         [0130]    As the oil level in the second reservoir  92  increases, it comes in contact with the air  81  flowing through the conical hole  79  of vortex plate  75 . As the air  81  and oil mix, a fine oil mist  94  is created, and travels into the communication orifice  84  and the bearing housing (not shown). 
         [0131]    When oil mist  94  exits the bearing it travels through the return line (not shown) and into orifice  89 . The returned oil mist  94  then mixes with the second air flow  85  and is moved adjacent to the filter  97  which is sealed to the outer body  71  by elastomers  98 ,  99  and  100 . 
         [0132]    As the oil mist  94  is pushed through the filter  97  it coalesces the oil mist  94  back into liquid form. The liquid oil then runs down the inner most radial surface of the filter  97  and through communication orifice  101  and orifice  84  back into the bearing chamber and reservoir (not shown). 
         [0133]    The filtered air  85  travels through orifice  105  and past the non-return valve  106  to vent to atmosphere. 
         [0134]      FIG. 7  corresponds to  FIG. 6  and shows the view on Section X-X, specifically the enclosed substantially parallel communication channels  80  in vortex plate  75 , and how they enter the conical hole  79  in a substantially tangential manner. 
         [0135]      FIG. 8  also corresponds to  FIG. 6  and shows an alternate view on Section X-X, whereby the surfaces  110  and  111  of the enclosed communication channels  112  in vortex plate  113 , are substantially inclined, being divergent in a radially outwards direction. 
         [0136]      FIG. 9  shows a longitudinal cross section of an alternate mist generation unit  115  of the invention. As shown, the vortex plate  116  has multiple conical orifices  117  and  118 , therefore generating more oil mist from a substantially modular unit to that previously shown. 
         [0137]      FIG. 10  corresponds to  FIG. 9  and shows the view on Section Y-Y whereby the multiple conical orifices  117  and  118  are fed tangentially by multiple communication channels  119 ,  120  and  121  in vortex plate  116 . 
         [0138]      FIG. 11  corresponds to  FIG. 6  and shows, by way of example only, the option to remotely, via inlet cap  125 , add lubricant fluid into reservoir (not shown) in order to increase the lubricant fluid level in the reservoir. 
         [0139]      FIG. 12  corresponds to  FIG. 6  and shows, by way of example only, the option to add a mist return flow-monitoring device  130  which detects a no/low flow condition and alerts the user.