Oil has been a must for lubrication and cooling of an internal combustion engine. The quality of the oil plays an important roll for the service-life and the operation of the engine. Besides the quality of the oil, particles, especially metallic particle (basically ferrous metal particles), which are generated during the operation of the engine are also a factor that affects the service life of the engine. These metal particles are destructive to the engine, for they circulate with the oil to the moving parts of the engine and cause wearing and abrasion on the moving parts which in turn generate more ferrous metal particles. To overcome such a problem, an oil filter is devised to filter and clean the oil. The oil filter has been well known and being improved for may years. In general, an oil filter comprises a canister housing inside which filtering means, such as filtering paper or other porous material which allows the oil to flow through but stops the ferrous metal particles and thus cleans the oil. An example is disclosed in Taiwan patent publication No. 170,160.
Oil filters of this structure have been a standard for many years. However, due to the requirement of the minimum flow rate of the oil for lubrication and cooling of the engine, this oil filter structure is incapable to filter out minute particles, for it must have large enough openings to establish the required oil flow rate.
To overcome such a problem, magnet means has been disposed inside the oil filter to attract and thus remove the minute ferrous metal particles out of the oil flow. Some examples of the magnetic oil filters are demonstrated in U.S. Pat. Nos. 4,450,075, 4,613,435, 4,826,592, 4,851,116, 5,078,871 and 5,228,990 and Taiwan patent publication Nos. 165,334, 181,638 (which is corresponding to U.S. Pat. No. 5,228,990) and 195,840. All these patents comprise magnet means in different forms disposed inside the oil filter canister for removing ferrous metal particle out of oil flow within the canister.
Although the conventional magnetic oil filters mentioned above do work well in removing minute metal particles from the oil flow, they have at least one major problem, namely, these oil filters comprise no metal particle collection means to allow the particles to be collected and securely held. Without the particle collection means, the ferrous metal particles that are attracted by the magnet means will gather around the magnet means and held thereon only by the magnetic force. The gathering of the metal particles may form a blockage to the oil flow.
Furthermore, since the metal particles are only held by the magnetic force and since the magnetic force to some extent may be overcome by the vibration and shake of the engine or the automobile on which the engine is mounted during their operations, the ferrous metal particles that are attracted around the magnet means may re-enter the oil flow. This reduces the effectiveness of the conventional magnetic oil filters.
An even more serious problem caused by the metal particles that are shaken to release from the magnet means and re-enter the oilflow is that these particles may be magnetized to some degree by the magnet means during their contact engagement with the magnet means and thus in their re-circulation within the engine, they may attract each other and form a large particle which causes a more serious damage to the engine if allowed to circulate with the oil flow.
Moreover, in some of the conventional magnetic oil filters, such as U.S. Pat. No. 5,228,990, the magnet means is fixed inside the canister by means of adhesive. Due to the high temperature condition during the normal operation of the engine, the oil flow that is thus maintained in a substantial high temperature deteriorates the adhesive and thus may cause failure of the adhesive. The failure of the adhesive results in un-securing the magnet means and thus damaging the oil filter. In certain conditions, the un-secured magnet means may also block the oil outlet and this causes an even more dangerous problem to the operation of the engine.
In some other magnetic oil filters, the magnetic means and the related parts are held inside the filter canister by means of frictional force provided by elastic deformation of the parts. However, due to the fact that to avoid unnecessary magnetization of the parts, some of the parts are made of aluminum which, as is generally well known, is less flexible and thus may not be able to provide desired elastic deformation for the provision of frictional force to hold the parts in position. As a result, the vibration and shake of the engine and/or the automobile may cause the magnet means and the related parts to disengage and thus damage the function of the oil filter.