Patent Document

CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to British Patent Application No. 1010626.8, filed Jun. 24, 2010, which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The technical invention relates to a filter assembly employed for filtering a lubricating oil of an internal combustion engine of a motor vehicle, principally the lubricating oil which is fed to a turbocharger of a turbocharged internal combustion engine. 
     BACKGROUND 
     It is known that the internal combustion engines comprise a lubrication circuit suitable for lubricating the rotating or sliding components of the engine. This lubrication circuit generally comprises an oil pump driven by the engine, which draws lubricating oil from a sump and delivers it under pressure through a main oil gallery that is realized in the cylinder block. The main oil gallery is connected via respective pipes to a plurality of exit holes for lubricating crankshaft bearings (main bearings and big-end bearings), camshaft bearings operating the valves, tappets, and the like. 
     The lubrication circuit of the turbocharged internal combustion engines further comprises a feeding pipe connecting the main oil gallery to the turbocharger, so as to lubricate the bearings of the rotating shaft connecting the compressor and the turbine of the turbocharger. Due to the very small clearances between the rotating shaft and its bearings, the lubricating oil fed to the turbocharger should be substantially devoid of contaminants, in order to prevent any bearing seizure. For this reason, it is known to locate an additional lubricating oil filter in the feeding pipe connecting the main oil gallery to the turbocharger. 
     A lubricating oil filter of this kind is realized by integrating a small filter element directly inside a banjo-bolt that is employed for joining the turbocharger feeding pipe to the main oil gallery of the cylinder block. This filter element is currently designed to be effective for the entire life of the internal combustion engine, in order to realize a “for-life filter”. Nonetheless, a clogging of the filter element may occur anyway, due for example to unusually big contaminant particles coming from the lubrication circuit. A clogging of the filter element is very dangerous because it reduces the flow rate of the lubricating oil fed to the turbocharger, thereby increasing the probability of a bearing seizure. The above mentioned “banjo-bolt solution” is unable to handle a clogging of the filter element, so that the turbocharger can be heavily damaged. 
     In view of the above, it is at least on object to solve this drawback, with a simple, rational and rather inexpensive solution. In addition, other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background. 
     SUMMARY 
     An embodiment provides a lubricating oil filter assembly for an internal combustion engine, which comprises a body provided with an oil inlet, an oil outlet, a conduit connecting the oil inlet to the oil outlet, and a chamber suitable for accommodating a filter element, the chamber being in communication with the oil inlet and with the oil outlet. 
     The lubricating oil filter assembly further comprises a movable valve member and a spring. The movable valve member is located in the conduit, so that the pressure of the lubricating oil at the oil inlet pushes the valve member towards an opening position, in which the valve member keeps said conduit open. The spring is arranged so as to push the valve member towards a closing position, in which the valve member keeps said conduit closed. With this solution, if a clogging of the filter element occurs, the pressure of the lubricating oil at the oil inlet increases and causes the valve member to open the conduit connecting the oil inlet to the oil outlet, so that the lubricating oil bypasses the filter element, thereby reaching the devices located downstream the lubricating oil filter assembly. According to an embodiment, the above mentioned conduit bypasses the chamber. This solution simplifies the realization of the body of the lubricating filter assembly. 
     According to an alternative embodiment, the chamber is located in the conduit, and the valve member is the filter element accommodated in the chamber, which is movable between the closing position, in which it hydraulically separates the oil inlet from the oil outlet of the body, and the opening position, in which it opens a passage that directly connects the oil inlet to the oil outlet. This solution advantageously allows a reduction in the dimensions of the body, thereby simplifying the packaging of the entire lubricating oil filter assembly. 
     According to another an embodiment, the lubricating oil filter assembly comprises a housing that accommodates the above mentioned body. The housing is provided with an inlet communicating with the oil inlet of the body, and with an outlet communicating with the oil outlet of the body. This solution has the advantage that the body, the filter element, the valve member and the spring are arranged so as to form a single removable cartridge, which can be entirely demounted from the housing, thereby simplifying the maintenance of the lubricating oil filter assembly. 
     According to an embodiment, the housing comprises a cup-shaped body and a bonnet, which is fixed to said cup-shaped body so as to enclose the body. This solution generally simplifies the realization of the mentioned housing. 
     According to an alternative embodiment of the invention, the lubricating oil filter assembly comprising a housing for the filter element. This housing is provided with an internal chamber and with an inlet and an outlet communicating with the internal chamber. The filter element is accommodated inside the internal chamber of the housing, so as to hydraulically separate the inlet from the outlet. The housing is accommodated inside the chamber of the body, so that the oil inlet of the body communicates with the inlet of the housing and the oil outlet of the body communicates with the outlet of the housing. This solution has the advantage that the housing and the filter element are arranged so as to form a removable cartridge, which can be demounted from the body independently from the valve member and the spring, thereby allowing a simple replacing of the sole filter element. As a consequence, this removable cartridge can be even designed as a disposable part. 
     According to another embodiment, the housing comprises a portion jutting out from the body. This solution simplifies the disassembly and the reassembly of the removable cartridge. According to another embodiment, the housing can be a banjo-bolt. As a matter of fact, a banjo-bolt is a cheap and largely available component, by means of which it is possible to realize a removable cartridge very simple and economic. 
     A lubricating oil filter assembly according to any of the preceding embodiment can further comprise a sensor for detecting the movable valve member in opening position. This sensor can be connected to an Engine Control Unit (ECU) of a vehicle on which the lubricating oil filter assembly is mounted, so as to indicate to the ECU and/or to the driver that the filter element is clogged. 
     Another embodiment provides the lubricating oil filter assembly disclosed above, which further comprises the filter element accommodated in the chamber of the body, so as to hydraulically separate the oil inlet from the oil outlet. 
     Still another embodiment provides an internal combustion engine comprising a lubrication circuit and the lubricating oil filter assembly disclosed above, which is located in the lubrication circuit. In this way, the lubricating oil filter assembly can be effectively used for filtering the lubricating oil upstream a critical device of the internal combustion engine. According to another of this embodiment, the lubricating oil filter assembly is located in a feeding line of the lubrication circuit, which is provided for delivering the lubricating oil into a turbocharger. This advantageously allows protection of the turbocharger against the bearing seizure. 
     According to another embodiment, the lubricating oil filter assembly is fixed to a cylinder block of the internal combustion engine. This embodiment has the advantage of preserve the original layout of the internal combustion engine. Alternatively, the lubricating oil filter assembly can be fixed to a housing of the turbocharger. This embodiment has the advantage that a single kind of lubricating oil filter assembly can be employed for different kinds of internal combustion engine. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and: 
         FIG. 1  is a partial view of a turbocharged internal combustion engine equipped with a lubricating oil filter assembly according to an embodiment; 
         FIG. 2  is a section II-II indicated in  FIG. 1 ; 
         FIG. 3  is a partial view of a turbocharged internal combustion engine equipped with a lubricating oil filter assembly according to another embodiment; 
         FIG. 4  is a section IV-IV indicated in  FIG. 3 ; 
         FIG. 5  is a partial view of a turbocharged internal combustion engine equipped with a lubricating oil filter assembly according to a further embodiment; 
         FIG. 6  is a section VI-VI indicated in  FIG. 5 ; and 
         FIG. 7  is a section VII-VII indicated in  FIG. 6 . 
         FIG. 8  is a partial view of a turbocharged internal combustion engine equipped with a lubricating oil filter assembly according to still another embodiment. 
         FIG. 9  is a section IX-IX indicated in  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is merely exemplary in nature and is not intended to limit application and uses. Furthermore, there is no intention to be bound by any theory presented in the preceding background or summary or the following detailed description. 
       FIG. 1  shows a conventional internal combustion engine  10  equipped with a turbocharger  20 . The internal combustion engine  10  is further conventionally equipped with a lubrication circuit  30 , which is only partially visible in the  FIG. 1 . The lubrication circuit  30  generally comprises an oil pump driven by the internal combustion engine  10 , which draws a lubricating oil from a sump and delivers it under pressure through a main oil gallery that is realized in the cylinder block  11  of the internal combustion engine  10 . 
     The main oil gallery is connected via respective pipes to a plurality of exit holes for lubricating crankshaft bearings (main bearings and big-end bearings), camshaft bearings operating the valves, tappets, and the like. The oil pump, the sump, the main oil gallery as well as the pipes connecting the main oil gallery to the above mentioned exit holes are not shown, because they are of conventional kind and therefore widely known to the skilled man. 
     The lubrication circuit  30  further comprises a feeding line  31  that hydraulically connects the main oil gallery of the cylinder block  11  to the turbocharger  20 , so as to lubricate the bearings of the rotating shaft connecting the compressor and the turbine of the turbocharger. The compressor, the turbine, the rotating shaft as well as the above mentioned bearings of the turbocharger  20  are not shown, because they are of conventional kind and therefore widely known to one of ordinary skilled in the art. 
     In order to filter the lubricating oil to be fed into the turbocharger  20 , a lubricating oil filter assembly  40  is located in the feeding line  31 . The lubricating oil filter assembly  40  comprises a body  50  and a removable filter cartridge  60  coupled to the body  50 . 
     As shown in  FIG. 2 , the body  50  is realized in a single casting comprising an oil inlet  51 , an oil outlet  52  and a cylindrical internal chamber  53 . The upper side of the chamber  53  is open to the exterior of the body  50 , while its lateral side is internally threaded. The oil inlet  51  communicates with the chamber  53  through a machined hole  54  that leads to the bottom side of the chamber  53 . The oil outlet  52  communicates with the chamber  53  through a rough channel  55  that leads to the lateral side of the chamber  53 . The removable filter cartridge  60  comprises a housing  61  containing a filter element  62 . 
     The housing  61  is defined by a conventional banjo-bolt having an head portion  63 , a threaded stem  64 , and an internal chamber  65  communicating with the exterior of the housing  61  through an inlet  66 , realized in the bottom side of the stem  64 , and an outlet  67 , realized in the lateral side of the stem  64 . 
     The filter element  62  has a cylindrical shape and is accommodated inside the internal chamber  65  of the housing  61 , so as to hydraulically separate the inlet  66  from the outlet  67 , with the aid of a gasket  68 . The stem  64  of the housing  61  is screwed into the chamber  53  of the body  50 , while the head portion  63  juts out from the body  50 . A gasket  69  is interposed between the head portion  63  and the body  50 , so as to guarantee the hermetical closure of the chamber  53 . 
     As long as the removable filter cartridge  60  is coupled with the body  50 , the oil inlet  51  of the body  50  communicates with the inlet  66  of the housing  61 , while the oil outlet  52  of the body  50  communicates with the outlet  67  of the housing  61 . The body  50  further comprises an internal conduit  56  connecting the oil inlet  51  to the oil outlet  52 , bypassing the chamber  53 . The body  50  further accommodates a movable valve member  57 , in this case a valve ball, which is located in the conduit  56 , and a spring  58 , which pushes the valve member  57  against a valve seat  59 , so as to hermetically close the conduit  56 . 
     The valve member  57 , the spring  58  and the valve seat  59  are arranged so that the pressure of the lubricating oil at the oil inlet  51  pushes the valve member  57  against the spring  58 , so as to open the conduit  56 . The spring  58  is preloaded by means of a plug  49  that is screwed into a threaded hole, through which the valve member  57  and the spring  58  are mounted into the conduit  56 . 
     As shown in  FIG. 1 , the body  50  of the lubricating oil filter assembly  40  is fixed to a housing  21  of the compressor of the turbocharger  20 , by means of a bracket  22 . The feeding line  31  comprises a first rigid pipe  32  connecting the main gallery of the cylinder block  11  to the oil inlet  51  of the body  50 , and a second rigid pipe  33  connecting the oil outlet  52  of the body  50  to a lubricating oil inlet of the turbocharger  20 . 
     In greater details, an extremity of the first rigid pipe  32  is connected to the main gallery of the cylinder block  11  by means of a conventional banjo fitting  34 , while the opposite extremity of the first rigid pipe  32  is brazed into the oil inlet  51  of the body  50  (see  FIG. 2 ). Similarly, an extremity of the second rigid pipe  33  is brazed into the oil outlet  52  of the body  50 , while the opposite extremity of the second rigid pipe  33  is connected to the lubricating oil inlet of the turbocharger  20  by means of another conventional banjo fitting  35 . During the operation of the internal combustion engine  10 , the lubricating oil flows in the feeding line  31  from the main oil gallery of the cylinder block  11  towards the turbocharger  20 , thereby passing inside the lubricating oil filter assembly  40 . 
     As long as the filter element  62  is sufficiently clean, the pressure of the lubricating oil at the oil inlet  51  is unable to overcome the preload of the spring  58 , so that the valve member  57  keeps the conduit  56  closed. As a consequence, the lubricating oil is forced to flow through the filter element  62 . Conversely, if a clogging of the filter element  62  occurs, the pressure of the lubricating oil at the oil inlet  51  increases and causes the valve member  57  to open the conduit  56 , so that the lubricating oil bypasses the filter element  62 , thereby reaching the turbocharger  20  anyway. As a matter of fact, the valve member  57  opens the conduit  56  once the pressure of the lubricating oil at the oil inlet  51  exceeds the preload of the spring  58 . 
     A sensor  80  is provided for detecting the valve member  57  in opening position. Subsequently, the removable filter cartridge  60  can be unscrewed from the body  50 , so as to allow the replacing of the clogged filter element  62 . 
       FIG. 3  and  FIG. 4  show a lubricating oil filter assembly  40  according to another embodiment of the invention, which is destined to be directly fixed to the cylinder block  11  of the internal combustion engine  10 . As a matter of fact, this lubricating oil filter assembly  40  differs from the preceding one only in that the body  50  comprises an hollow protruding nose  70 , which defines the oil inlet  51  and which is shaped so as to be directly inserted into an hole  12  of the cylinder block  11 , which leads into the main oil gallery. A gasket  71  is interposed between the protruding nose  70  and the hole  12 , so as to guarantee the hermetical closure of the main oil gallery. 
     In the present embodiment, the feeding line  31  is defined by a single rigid pipe  36  having a first extremity brazed into the oil outlet  52  of the body  50 , and a second extremity connected to the lubricating oil inlet of the turbocharger  20  by means of the conventional banjo fitting  37 . In use, the lubricating oil filter assembly  40  according to the present embodiment operates the same way as that previously described. 
       FIG. 6  shows a lubricating oil filter assembly  240  according to another embodiment. The lubricating oil filter assembly  240  comprises an external housing  250  enclosing a removable filter cartridge  260 . The housing  250  comprises a cup-shaped body  251  and a bonnet  252 , which is screwed to the cup-shaped body  251  so as to define a closed internal chamber  253 , in which the removable filter cartridge  260  is accommodated. 
     While the cup-shaped body  251  comprises an outlet  254 , the bonnet  252  comprises an inlet  255  coaxially aligned with the outlet  254 . Both the inlet  255  and the outlet  254  communicate with the internal chamber  253 . The removable filter cartridge  260  comprises a body  261  and a filter element  262  associated to said body  261 . 
     The body  261  has a cylindrical shape with a protruding flange  263  located at a first extremity. The body  261  further comprises an internal chamber  264  communicating with the exterior of the body  261  through an oil inlet  265 , realized at the first extremity of the body  261 , and an oil outlet  266 , realized at the opposite extremity of the body  261 , as clearly shown in  FIG. 7 . 
     The filter element  262  has a cylindrical shape and is accommodated inside the chamber  264  of the body  261 , so as to hydraulically separate the oil inlet  265  from the oil outlet  266 , with the aid of a gasket  267 . The body  261  comprises an additional conduit  268  connecting the oil inlet  265  to the oil outlet  266 . 
     The body  261  further accommodates a movable valve member  269 , in this case a valve ball, which is located in the conduit  268 , and a spring  270 , which pushes the valve member  269  against a valve seat  271 , so as to hermetically close the conduit  268 . The valve member  269 , the spring  270  and the valve seat  271  are arranged so that the pressure of the lubricating oil at the oil inlet  265  pushes the valve member  269  against the spring  270 , so as to open the conduit  268 . The spring  270  is preloaded by means of a plug  272  screwed into a threaded hole of the body  261 , through which the valve member  269  and the spring  270  are mounted inside the conduit  268 . The body  261  is inserted into the cup-shaped body  251  of the housing  250 , so as to be completely enclosed inside the internal chamber  253 , with the protruding flange  263  resting against the perimetrical edge of the opening of the cup shaped-body  251 . As long as the removable filter cartridge  260  is coupled with the housing  250 , the inlet  255  of the housing  250  communicates with the oil inlet  265  of the body  261 , while the outlet  254  of the housing  250  communicates with the oil outlet  266  of the body  261 . 
     As shown in  FIG. 5 , the housing  250  of the lubricating oil filter assembly  240  is fixed to the housing  21  of the compressor of the turbocharger  20 , by means of a bracket  222 . The feeding line  31  comprises a first rigid pipe  232  connecting the main gallery of the cylinder block  11  to the inlet  255  of the housing  250 , and a second rigid pipe  233  connecting the outlet  254  of the housing  250  to the lubricating oil inlet of the turbocharger  20 . In greater detail, an extremity of the first rigid pipe  232  is connected to the main gallery of the cylinder block  11  by means of a conventional banjo fitting  234 , while the opposite extremity of the first rigid pipe  232  is inserted into the inlet  255  of the housing  250 . 
     As shown in  FIG. 6 , this opposite extremity of the first rigid pipe  232  comprises a flange  235  that is interposed between an internal shoulder  273  of the bonnet  252  and the protruding flange  263  of the body  261  of the removable filter cartridge  260 . The first rigid pipe  232  is inserted into the inlet  255  of the housing  250  with a certain clearance, so that the bonnet  252  can axially move along the first rigid pipe  232 . 
     When the bonnet  252  is screwed to the cup-shaped body  251 , the shoulder  273  presses the protruding flange  263  of the body  261  of the removable filter cartridge  260  between the flange  235  of the first rigid pipe  232  and the edge of the opening of the cup-shaped body  251 , so as to guarantee the hermetical closure of the housing  250 , eventually with the aid of a gasket. Conversely, the second rigid pipe  233  has an extremity that is brazed into the outlet  254  of the housing  250 , and an opposite extremity that is connected to the lubricating oil inlet of the turbocharger  20  by means of another conventional banjo fitting  236 . 
     During the operation of the internal combustion engine  10 , as long as the filter element  262  is sufficiently clean, the pressure of the lubricating oil at the inlet  255  is unable to overcome the preload of the spring  270 , so that the valve member  269  keeps the conduit  268  closed. As a consequence, the lubricating oil is forced to flow trough the filter element  262 . Conversely, if a clogging of the filter element  262  occurs, the pressure of the lubricating oil at the inlet  255  increases and causes the valve member  269  to open the conduit  268 , so that the lubricating oil bypasses the filter element  262 , to thereby reaching the turbocharger  20  anyway. As a matter of fact, the valve member  269  opens the conduit  268  once the pressure of the lubricating oil at the inlet  255  exceeds the preload of the spring  270 . A sensor  280  is provided for detecting the valve member  269  in opening position. Subsequently, the bonnet  252  of the housing  250  can be unscrewed from the cup-shaped body  251 , allowing the removable filter cartridge  260  to be removed, so as to replace the clogged filter element  262  with a clean one. 
       FIG. 8  and  FIG. 9  show a lubricating oil filter assembly  240  according to another embodiment, which differs from the last one, only in that the removable filter cartridge  260 , is replaced by a removable filter cartridge  360  having a different design. As shown in  FIG. 9 , the removable filter cartridge  360  comprises a body  361  containing a filter element  362 . 
     The body  361  has a cylindrical shape with a protruding flange  363  located at a first extremity. The body  361  further comprises an internal chamber  364  communicating with the exterior of the body  361  through an oil inlet  365 , realized at the first extremity of the body  361 , and an oil outlet  366 , which is realized at the opposite extremity of the body  361 . 
     The chamber  364 , the oil inlet  365  and the oil outlet  366  define a single conduit globally indicated as  368 . The filter element  362  is accommodated inside the chamber  364  of the body  361 , and is pushed by a spring  367  against a valve seat  369  so as to hydraulically close the oil inlet  365  with respect to the oil outlet  366 . The filter element  362 , the spring  367  and the valve seat  369  are arranged so that the pressure of the lubricating oil at the oil inlet  365  pushes the filter element  362  against the spring  367 , so as to open a passage  370  that hydraulically connects the oil inlet  365  to the oil outlet  366 . In particular, this passage  370  is provided by a clearance between the lateral side of the filter element  362  and the lateral surface of the chamber  364 . 
     The body  361  is inserted into the cup-shaped body  251  of the housing  250 , so as to be completely enclosed inside the internal chamber, with the protruding flange  363  resting against the perimetrical edge of the opening of the cup-shaped body  251 . As long as the removable filter cartridge  360  is coupled with the housing  250 , the inlet  255  of the housing  250  communicates with the oil inlet  365  of the body  361 , while the outlet  254  of the housing  250  communicates with the oil outlet  366  of the body  261 . In this way, as long as the filter element  362  is sufficiently clean, the pressure of the lubricating oil at the inlet  255  is unable to overcome the preload of the spring  367 , so that the filter element  362  keeps the oil inlet  365  closed. As a consequence, the lubricating oil is forced to flow trough the filter element  362 . Conversely, if a clogging of the filter element  362  occurs, the pressure of the lubricating oil at the oil inlet  355  increases and causes the filter element  362  to open the oil inlet  365 , so that the lubricating oil bypasses the filter element  362 , to thereby reaching the turbocharger  20  anyway. 
     As a matter of fact, the filter element  362  works also as a valve member, which keeps the first opening  355  in direct communication with the second opening  356 , once the pressure of the lubricating oil at the oil inlet  355  exceeds the preload of the spring  367 . A sensor  380  is provided for detecting the filter element  362  in opening position. 
     While at least one exemplary embodiment has been presented in the foregoing summary and detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the forgoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and in their legal equivalents.

Technology Category: 2