Background Art Generally, oil is mainly used as lubricant in industrial fields or vehicles. However, abrasive particles and impurities are contained in oil circulating through an engine system, so the life span of an engine is shortened. Due to the abrasive particles and impurities contained in oil, not only is the engine insufficiently lubricated, but also it is required to frequently exchange oil. Thus, the cost is increased and an environmental problem is resulted caused by the great amount of waste oil.

In order to expand the life span of oil by filtering abrasive particles and impurities from oil, an oil filter is provided in the engine having lubricant of oil.

The oil filter is used in various industrial fields. Hereinafter, an oil filter used in an internal combustion engine of a vehicle will be described.

An engine of the internal combustion engine has various components, which are interacted with each other while generating friction therebetween and exposed to the high temperature combustion heat. To this end, oil is supplied to the engine so as to reduce the frictional resistance and to cool the engine having the high temperature.

Engine oil stored in an oil pan is pumped through an oil screen by an oil pump, which is driven by a rotational force of a crankshaft, and is cooled through an oil cooler. Then, after filtering impurities contained in engine oil through an oil filter, engine oil is supplied into each moving component, such as the crankshaft, a connecting rod, a piston, a crankshaft bearing and a valve unit, so as to lubricate and cool the moving components.

Oil contains abrasive particles and impurities while passing through the various components of the engine, so it is required to filter the abrasive particles and impurities by using the oil filter. However, if great amount of the abrasive particles and impurities are

contained in oil, the life span of the oil filter is shortened so that it is required to frequently exchange the oil filter. In addition, the cleanliness of oil is lowered due to the contaminated oil filter, so it is difficult to effectively lubricate and cool the engine, thereby shortening the life span of oil and the engine.

Disclosure of the Invention The present invention has been made to solve the above problems of the related art, therefore, it is an object of the present invention to provide an auxiliary oil refining apparatus which is positioned between an oil pump and an oil filter so as to refine oil for lubricating and cooling an engine together with oil filter, thereby extending the exchange period of oil and the oil filter and the life span of the engine.

Another object of the present invention is to provide an auxiliary oil refining apparatus capable of saving the cost by exchanging only an oil filter when it is required to exchange the auxiliary oil refining apparatus.

To achieve the above objects, there is provided an auxiliary oil refining apparatus positioned between an oil pump and an oil filter to supply a part of oil to an engine by refining the part of oil through bypassing the part of oil, the auxiliary oil refining apparatus comprising: a housing having a suction nipple coupled at a lower surface thereof, an upper surface of the housing being opened; an elastic means accommodated in the housing; a filter rested on an upper surface of the elastic means and accommodated in the housing such that a space section is formed between an inner wall of the housing and the filter, and having a plurality of perforation holes at upper and lower surfaces thereof for filtering abrasive particles and impurities contained in oil; and a cover provided at an upper portion of the filter so as to be fixedly coupled with the housing by interposing an oil ring therebetween and having an exhaust nipple coupled to an upper surface thereof.

A spiral slot is formed at the inner wall of the housing to allow oil to rapidly flow by applying a rotational force to oil.

The filter includes a cylindrical case provided at upper and lower surfaces thereof with upper and lower caps having a plurality of perforation holes and a plurality of unit filtering members accommodated in the case for filtering oil. The filtering members include a pure cotton layer formed at a lower portion of the case adjacent to the lower cap, a supporting layer formed on an upper surface of the pure cotton layer and having an elastic member for

support the unit filtering member stacked on an upper surface of the elastic member, a first cotton yarn layer formed on the supporting layer so as to filter impurities having a size above 100 from oil, a second cotton yarn layer formed on the first cotton yarn layer so as to filter impurities having a size above 50Mm from oil, a wet absorbing layer formed on the second cotton yarn layer for removing wet contained in oil with a chemical reaction, a chemical treating layer including chemical additive of a minute particle and formed on the wet absorbing layer so as to improve a function of oil by being dissolved in oil, a filtering layer including high purity absorbent cotton and formed on the chemical treating layer to filter impurities having a size of 1 to lopm from oil, and a non-woven fabric layer and a filtering net layer which are formed on the filtering layer to control a flow rate and pressure of oil and to prevent the filtering layer from being protruded through the perforation holes of the upper cap.

A protruding part is downwardly protruded from one side of the upper cap in opposition to the filtering net layer formed in the case of the filter. An end of the protruding part is smoothly bent towards a center of the upper cap so as to have an elastic force. The filtering net layer is elastically and fixedly inserted into the protruding part.

The filtering net layer is positioned closely adjacent to the lower surface of the upper cap and a predetermined peripheral portion of the filtering net layer is electrically welded to the upper cap.

The filtering net layer formed in the case of the filter is provided at one side thereof with a snap ring having a diameter larger than an inner diameter of the case. The snap ring supports the filtering net by closely attaching the filtering net layer to the upper cap.

A lateral protruding part is formed in an inner peripheral portion of the case adjacent to the upper cap along a circumferential direction of the case. The filtering net layer is elastically inserted into the lateral protruding part so as to be closely adjacent to the upper cap.

A ring shaped magnetic member for filtering metallic impurities from oil is provided between the elastic means accommodated in the housing and the lower cap of the filter. The elastic means is fixedly attached to a peripheral portion of the ring shaped magnetic member so that the elastic means is constantly positioned in a predetermined position on the lower cap.

The ring shaped magnetic member is fixedly attached to an outer peripheral portion of a flange of the lower cap.

The suction nipple of the auxiliary oil refining apparatus is connected to a branching

unit formed between the oil pump and the oil filter through a bypass pipe. The branching unit includes: a branching member adjacent to the oil pump and the oil filter and having a plurality of holes communicated with the perforation holes of the oil pump and oil filter at a circumferential direction of the thereof ; a horizontal nipple coupled to a center of one side of the branching member by passing through the branching member, the oil filter is being screw- coupled to one end of the horizontal nipple and the oil pump is being screw-coupled to the other end of the horizontal nipple so as to re-introduce oil filtered by the oil filter to the oil pump; and a vertical nipple coupled to a peripheral portion of the branching member so as to communicate with the holes of branching member, one end of the vertical nipple being communicated with the suction nipple of the auxiliary oil refining apparatus through the bypass pipe to bypass a part of oil supplied from the oil pump to the oil filter towards the auxiliary oil refining apparatus.

The exhaust nipple of the auxiliary oil refining apparatus is connected to a coupling unit formed in the engine through a supplying pipe. A large diameter section of a supplying nipple is connected to the supplying pipe and a small diameter section of the supplying nipple is connected to an oil cap screw-coupled to the engine. A cap washer having an opened lower surface is provided at the small diameter section of the supplying nipple formed at an upper surface of the oil cap by interposing an oil ring therebetween. A key washer is provided at the small diameter section of the supplying nipple adjacent to a lower surface of the oil cap by interposing an oil ring therebetween.

Brief Description of the Drawings The above objects, and other features and advantages of the present invention will become more apparent by describing preferred embodiments thereof with reference to the attached drawings in which: FIG. 1 is a schematic view showing an oil refining system equipped with an auxiliary oil refining system of the present invention installed in an engine; FIG. 2 is an exploded perspective view of an auxiliary oil refining system of the present invention; FIG. 3 is a half-sectional perspective view of an auxiliary oil refining system of the present invention; FIG. 4 is a half-sectional exploded perspective view of an auxiliary oil refining

system of the present invention; FIG 5 is an enlarged view of"A"portion shown in FIG. 1; FIG. 6 is a sectional view showing a branching unit of an auxiliary oil refining apparatus of the present invention; FIG 7 is a perspective view showing a branching unit of an auxiliary oil refining apparatus of the present invention; FIG 8A is a sectional view showing a filtering net fixed to an upper cap of a filter; FIG 8B is a sectional view showing a filtering net electrically welded to an upper cap of a filter ; FIG 8C is a sectional view showing a filtering net fixed to an upper cap by means of a snap ring; FIG 8D is a sectional view showing a filtering net fixed to a case; and FIG 9 is a graph showing the filtering efficiency of a cotton yarn filter of the present invention and other filtering members as a function of a particle size.

Best Mode for Carrying Out the Invention Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIGS. 1 to 8 are views showing an auxiliary oil refining apparatus according to the present invention.

Referring to FIG. 1, an oil tank 2 is provided at a lower portion of an engine 1. Oil contained in the oil tank 2 is pumped through an oil pump 4 installed at one side of the engine 1 and supplied to each component of the engine 1 by way of an oil filter 5.

An auxiliary oil refining apparatus 10 is provided between the oil pump 4 and the engine 1 so as to refine oil in a separate way from the oil filter 5. The auxiliary oil refining apparatus 10 is connected to the oil pump 4 and the engine 1 through a bypass pipe 7 and a supplying pipe 8, respectively.

FIGS. 2 to 4 show the auxiliary oil refining apparatus of the present invention. The auxiliary oil refining apparatus 10 of the present invention mainly includes a housing 11, a filter 20 and a cover 26 The housing 11 has a hollow cylindrical shape, in which an upper surface thereof is

opened. An annular slot 12 is formed at the upper surface of the housing 11 to receive an oil ring 17 for improving a sealing efficiency of the auxiliary oil refining apparatus 10.

In addition, a plurality of flanges 13 having a screw hole are protruded at an right angle from an upper peripheral portion of the housing 11 adjacent to the annular slot 12.

A suction nipple 16 is detachably screw-coupled to a center of a bottom of the housing 11. The suction nipple 16 is vertically bent and coupled to the housing 11 from an outside of the housing 11. A spiral slot 14 is formed in an inner wall of the housing 11 so as to apply a rotational force to oil introduced into the housing 11 to allow oil to rapidly flow in the housing 11.

A space section 15 is formed between an inner wall of the housing 11 and the filter 20. Oil flows through the space section 15 so as to cool the auxiliary oil refining apparatus 10.

In addition, thought it is not illustrated, cooling fins can be installed at an outer periphery portion of the housing 10 so as to improve the cooling efficiency of the auxiliary oil refining apparatus 10. In addition, a fixing bracket can be installed at a predetermined portion of the engine 1.

An elastic device 18 including a compression coil spring is provided in the housing 11. The elastic device 18 is fixed to a flange 25a of a lower cap 25 of the filter 20 through a ring-shaped magnetic member 19.

That is, the ring-shaped magnetic member 19 is fixedly attached to an outer wall of the flange 25a, which is outwardly bent from a lower cap 25 of the filter 20, and the elastic device 18 surrounds the outer wall of the magnetic member 19 so that the elastic device 18 is fixedly positioned at a center of the bottom of the filter 20.

The ring-shaped magnetic member 19 has a magnetic force above 1500 gauss and filters metallic particles contained in oil before oil introduced into the housing 11 through the suction nipple 16 passes through the filter 20.

In addition, the filter 20 for filtering abrasive particles and impurities from oil is installed on upper surfaces of the ring-shaped magnetic member 19 and the elastic device 18, in such a manner that the filter 20 is spaced from the inner wall of the housing 11 to form the space 15 therebetween. The cover 26 is provided on an upper surface of the filter 20.

A reinforcement rib 28 is integrally formed with an upper surface of the cover 26 so as to reinforce the strength of the cover 26. A plurality of flanges 27 corresponding to the flanges 13 of the housing 11 are formed at a peripheral portion of the cover 26. A perforation

hole is formed at each flange 27.

Thus, the flanges 27 are coupled with stud bolts 31, which are screw-coupled to the flanges 13 of the housing and a washer 30 and a butterfly nut 32 are coupled to the stud bolt from an upper portion of the cover 26, so that the cover 26 is fixedly coupled to the housing 11. Since the oil ring 17 inserted into the annular slot 12 is interposed between the cover 26 and the housing 11, the sealing effect of the auxiliary oil refining apparatus 10 can be improved.

In addition, an exhaust nipple 29 is s detachably screw-coupled to a center of the upper surface of the cover 26 so as to communicate with the housing 11. The exhaust nipple 29 is vertically bent and coupled to the cover 26 from an outside of the cover 26. One end of the exhaust nipple 29 is communicated with a connection device 40 of the engine through the supplying pipe 8.

The filter 20 includes a cylindrical hollow case 21 having an outer diameter smaller than an inner diameter of the housing 11. Upper and lower caps 22 and 25 having a plurality of perforation holes 22'and 25', respectively, are fixed to upper and lower surfaces of the case 21. A plurality of unit filtering members are stacked in the case 21 so as to sequentially filter abrasive particles and impurities contained in oil through several times.

The filtering members provided in the filter 20 include a pure cotton layer 20a formed at a lower portion of the case 21 adjacent to the lower cap 25, a supporting layer 20b formed on an upper surface of the pure cotton layer 20a and having an elastic member 20b' including a compression spring for biasing the unit filtering member stacked on an upper surface of the elastic member towards the upper cap 22, a first cotton yarn layer 20c formed on the supporting layer 20b so as to filter impurities having a size above 100, can from oil, a second cotton yarn layer 20d formed on the first cotton yarn layer 20c so as to filter impurities having a size above 50jus from oil, a wet absorbing layer 20e formed on the second cotton yarn layer 20d for removing wet contained in oil with a chemical reaction, a chemical treating layer 20f including chemical additive of a minute particle and formed on the wet absorbing layer 20e so as to improve the function of oil by being dissolved in oil, a filtering layer 20g including high purity absorbent cotton and formed on the chemical treating layer 20f to filter impurities having a size of 1 to 10, can from oil, and a non-woven fabric layer 20h and a filtering net layer 20i which are formed on the filtering layer 20g to control the flow rate and pressure of oil and to prevent the filtering layer 20g from being protruded through the

perforation holes 22'of the upper cap 22.

The filtering net layer 20i has pores having 40 to 60 mesh sizes so as to control the flow rate and pressure of oil passing through the filtering net layer 20i.

In addition, chemical additive, such as an anti-foam agent, a viscosity index improver, an anti-friction-abrasion agent, and an oxidation stabilizer, is added to the chemical treating layer 20f in a form of a minute gel in order to prevent oil from being aged and to improve the lubricating performance.

The elastic member 20b'including the compression spring forming the supporting layer 20b prevents the unit filtering member from being sagged by elastically compensating for the variation of the volume of the unit filtering member, which is created because the filtering action is continuously carried out in the case 21.

In addition, the exchanging period of the filter 20 can be remarkably extended due to the oxidation and aging phenomenon of oil can be restricted. Since the impurities contained in oil are sequentially filtered, the friction between the impurities and the components of the engine 1 can be reduced, so the abrasion of the components of the engine 1 can be reduced, thereby extending the life span of the engine 1.

The first and second cotton yarn layers 20c and 20d are very important for determining the performance of the filter 20. FIG. 9 and table 1 show the test result for the filtering efficiency of the first and second cotton yarn layers 20c and 20d and other filtering member.

Table 1-characteristic according to the sorts of filtering member Paper Cotton yarn Chemical yarn Metal net Weight (g/m2) 134 135 132 200 Thickness (mm) 0. 7 0. 7 0. 7 0. 3 Max size of 60 50 50 68 filtering hole (tan) Mean size of 45 38 38 45 filtering hole (,) As shown in the table 1, the paper, chemical yarn, cotton yarn and metal net are

selected as the filtering members. Then, oil containing the same impurities flows into the filtering members with the same flow rate.

At this time, the unit area of the paper is 28. 26 inch2, the unit area of the cotton yarn is 28 inch2, the unit area of the chemical yarn is 29 inch2, and the unit area of the metal net is 30 inch2.

The test result based on the above conditions is shown in FIG. 9, as a graph.

As is understood from the graph of FIG. 9, when measuring the filtering efficiency with passing oil having impurities through each filtering members, it is presented that the filtering efficiency of the cotton yarn is superior to the filtering efficiency of the chemical yarn, the paper, and the metal net.

FIGS. 8A to 8C shows the coupling state of the filtering net layer of the filter fixed adjacent to the upper cap.

Referring to FIG. 8A, a protruding part 22a is downwardly protruded from a lower surface of the upper cap 22 opposite to the filtering net layer 20i. A lower end of the protruding part 22a is smoothly curved towards a center of the upper cap 22 so that the protruding part 22a has a predetermined elastic force. The filtering net layer 20i is elastically inserted into the inner portion of the protruding part 22a.

The protruding part 22a can be formed on the upper cap while spacing from one side of the upper cap 22 by a predetermined distance or can be integrally formed with the upper cap 22 along the circumference of the upper cap 22.

Thus, since the upper cap 22 is integrally formed with the protruding part 22a, the productivity can be improved and the manufacturing cost can be saved.

Referring to FIG. 8B, according to another embodiment of the present invention, the filtering net layer 20i is provided closely adjacent to a lower surface of the upper cap 22. At this time, one side of the filtering net layer 20i is electrically welded to the upper cap 22.

In addition, referring to FIG. 8C, a snap ring 24 having a diameter larger than an inner diameter of the case 21 is inserted into the case 21 in a compression state and is closely attached to the lower surface of the filtering net layer 20i accommodated in the case 21 of the filter 20. Then, the filtering net layer 20i is closely adjacent to the upper cap 22 by releasing the compression state of the snap ring 24.

Referring to FIG. 8D, a lateral protruding part 21a is formed at an inner upper peripheral portion of the case 21 adjacent to the upper cap 22. The filtering net layer 20i is

elastically coupled with the lateral protruding part 21a so that the filtering net layer 20i is fixedly attached to the upper cap 22.

FIGS. 6 and 7 show a branching unit according to the present invention. The branching unit 50 is provided between the oil pump 4 and the oil filter 5 and is communicated with the suction nipple 16 of the auxiliary oil refining apparatus 10 through a bypass pipe 7.

Both sides of the branching unit 50 are respectively adjacent to the oil pump 4 and the oil filter 5. A center portion of the both sides of the branching unit 50 is recessed by a predetermined angle. A branching member 51 is positioned at one side of the branching unit 50. A plurality of holes 52 communicated with the perforation holes 4a and 5a of the oil pump 4 and the oil filter 5 are formed in a circumference direction of the branching member 51.

In addition, a horizontal nipple 53 is provided at a center of the branching member 51 so as to guide oil filtered by the oil filter 5 towards the oil pump 4.

One end of the horizontal nipple 53 is coupled to one side of the branching member 51 by passing through the branching member. The oil filter 5 is screw-coupled to one end of the horizontal nipple 53 and the oil pump 4 is screw-coupled to the other end of the horizontal nipple 53.

In addition, a vertical nipple 54 is provided at a peripheral portion of the branching member 51 in order to bypass a part of oil, which is supplied from the oil pump 4 to the oil filter 5, towards the auxiliary oil refining apparatus 10.

One end of the vertical nipple 54 is coupled to a peripheral portion of the branching member 51 to communicate with the hole 52 of the branching member 51 and the other end of the vertical nipple 54 is communicated with the suction nipple 16 of the auxiliary oil refining apparatus 10 through a bypass pipe 7.

Reference number 6 represents a filter accommodated in the oil filter 5, and reference numbers 55 and 56 represent oil rings, which are provided at both sides of the branching member 51 to seal between the branching member 51 and the oil pump 4 and between the branching member 51 and the oil filter 5.

FIG. 5 shows a coupling unit for the supplying pipe 8 and the engine 1. The coupling unit 40 connects the supplying pipe 8 communicated with the exhaust nipple 29 of the auxiliary oil refining apparatus 10 to the engine 1.

Bt the coupling unit 40, a large diameter section 41a of a supplying nipple 41 is communicated with the supplying pipe 8 and a small diameter section 41b of the supplying

nipple 41 passes through an oil cap 3 screw-coupled to the engine 1.

A cap washer 42 having a""shape is provided at the small diameter section 41b of the supplying nipple 41 formed at an upper surface of the oil cap 3 by interposing an oil ring 43 therebetween. A key washer 44 is provided at the small diameter section 41b of the supplying nipple 41 adjacent to a lower surface of the oil cap 3 by interposing an oil ring 45 therebetween.

Thus, oil flowing through the supplying pipe 8 or flowing into the engine 1 can be prevented from being leaked.

According to the auxiliary oil refining apparatus 10 of the present invention, the ring-shaped magnetic member 19 is attached to the flange 25a, which is downwardly bent from a center of the lower cap 25 of the filter 20. In addition, the elastic device 18 including the compression coil spring is attached to an outer peripheral portion of the ring-shaped magnetic member 19. Thus, the ring-shaped magnetic member 19 and the elastic device 18 are fixedly positioned at the lower surface of the filter 20.

Then, the filter 20 and the elastic device 18 are inserted into the housing 11 such that the elastic device 18 makes contact with the bottom surface of the housing 11, so the space section 15 is formed between the housing 11 and the filter 20 corresponding to a height of the elastic member 18.

On the other hand, the filter 20 inserted into the housing 11 is smaller than the inner diameter of the housing 11, so the space section 15 is also formed between the filter 20 and the inner wall of the housing 11.

The fluid passage formed in the suction nipple 16 coupled to the lower surface of the housing 11 can be positioned within an area of the elastic member 18 though the filter 20 is moved in left or right direction due to the space section 15 formed between the filter 20 and the housing 11. That is, the diameter of the elastic device 18 should be designed by considering the diameters of the housing 11 and the filter 20, such that the suction nipple 16 can be accommodated in the elastic member 18.

In addition, the cover 26 is provided on the upper surface of the housing 11 having the filter 20 therein. The exhaust nipple 29 is fixedly coupled to an upper center portion of the cover 26. The flanges 27 formed at the peripheral portion of the cover 26 is coupled with the stud bolts 31, which are screw-coupled with the flanges of the housing 11, and the butterfly nuts 32 are screw-coupled to the stud bolts 31 protruded out of the flanges 27 through the

washers 30, so that the cover 26 can be fixedly coupled to the upper surface of the housing 11.

According to the auxiliary oil refining apparatus 10 having the above construction, the bypass pipe 7 and the supplying pipe 8 are respectively connected to the suction nipple 16 and the exhaust nipple 29. In addition, the bypass pipe 7 and the supplying pipe 8 are respectively connected to the branching unit 50 and the coupling unit 40 provided in the engine 1, so the auxiliary oil refining apparatus 10 is connected to the engine 1.

When the oil pump 4 operates by the driving force of the engine 1, oil stored in the oil tank 2 provided at a lower portion of the engine 1 is introduced into the oil filter 5 through the oil pump 4.

At this time, a part of oil introduced into the oil filter 5 is flowing into the auxiliary oil refining apparatus 10 through the branching unit 50 formed between the oil pump 4 and the oil filter 5. Oil discharged through the perforation hole 4a of the oil pump 4 is flowing through the holes 52 of the branching member 51 and filtered through the perforation hole 5a of the oil filter 5. Then, oil is introduced into the oil pump 4 by passing through the horizontal nipple 53 of the branching member 51 and is supplied to each part of the engine 1.

On the other hand, a part of oil passing through the holes 52 of the branching member 51 is branched after flowing into the vertical nipple 54 communicated with the holes 52 of the branching member 51, and oil introduced into the vertical nipple 54 is flowing into the auxiliary oil refining apparatus 10 by passing through the bypass pipe 7.

Oil introduced into the auxiliary oil refining apparatus 10 through the bypass pipe 7 is flowing into the housing 11 through the suction nipple 16 coupled to the lower surface of the housing 11.

When oil is continuously supplied into the housing 11, the surface of oil rises while filling the space section 15 formed between the filter 20 and the housing 11 with oil ; so oil is introduced into the filter 20.

Oil introduced into the filter 20 passes through the elastic device 18 and the magnetic member 19. At this time, metallic impurities contained in oil can be filtered when oil passes through the magnetic member 19.

Then, oil, in which the metallic impurities are filtered, is introduced into the case 21 of the filter through the perforation hole 25'of the lower cap 25 and passes through the pure cotton layer 20a provided at a lower end of the case 21. Impurities contained in oil and having a relatively large size are filtered by the pure cotton layer 20a so that the impurities are

prevented from being introduced into the case 21.

Oil passing through the pure cotton layer 20a is introduced into the supporting layer 20b having the elastic member 20b'including a compression spring and sequentially passes through the first and second cotton yarn layers 20c and 20d.

At this time, impurities having a size above 100, un are filtered when oil passes through the first cotton layer 20c and impurities having a size above 5 cam are filtered when oil passes through the second cotton layer 20d.

Then, oil is subject to a chemical reaction when oil passes through the wet absorbing layer 20e, so that wet contained in oil can be removed.

Oil that has passed through the wet absorbing layer 20e is introduced into the chemical treating layer 20f. At this time, chemical additive in a form of a minute gel, such as an anti-foam agent, a viscosity index improver, an anti-friction-abrasion agent, and an oxidation stabilizer, is added to oil in order to improve the lubricating function of oil.

Oil passing through the chemical treating layer 20f is introduced into the filtering layer 20g including the high-purity absorbent cotton. When passing through the filtering layer 20g, impurities having a size of 1-10mm are filtered by the filtering layer 20g. Oil passing through the filtering layer 20g is sequentially introduced into the non-woven fabric layer 20h and the filtering net layer 20i and is discharged out of the housing 11 through the perforation hole 22'of the upper cap 22.

As shown in FI. G 8, the filtering net layer 20i having a mesh structure is fixed adjacent to the upper cap 22 by the protruding part 22a of the upper cap 22, the electric welding 23, the snap ring 24 or the lateral protruding part 21a of the case 21. Together with the elastic member 20b', the filtering net layer 20i supports the plural unit filtering members for filtering oil to constantly maintain the volume of the unit filtering members and to prevent the unit filtering members from being protruded through the perforation hole 22'of the upper cap 22.

In addition, a rotational force is applied to oil when oil is introduced into the space section 15 formed between the housing 11 and the filter 20 due to the spiral slot 14 formed at the inner wall of the housing 11, so oil can cool the auxiliary oil refining apparatus 1 while rapidly flowing through the space section 15.

Thus, oil filtered by the filter 20 is discharged to the exterior of the auxiliary oil refining apparatus 10 through the exhaust nipple 29 provided in the cover 26. Discharged oil

is supplied to the engine 1 through the supplying pipe 8 and the supplying nipple 41 of the coupling unit 40.

The supplying nipple 41 of the coupling unit 40 coupled to the oil cap 3 by passing through the oil cap 3, which is detachably coupled to the engine 1. The sealing between the oil cap 3 and the supplying nipple 41 can be maintained by means of the cap washer 42 and the oil ring 43, and the key washer 44 and the oil ring 45.

As mentioned above, oil refined by the auxiliary oil refining apparatus 10 is supplied into the engine together with oil filtered by the oil filter to lubricate and cool the components ofthe engine 1.

When it is required to exchange the auxiliary oil refining apparatus 10, the butterfly nut 32 formed in the cover 26 is released to separate the cover 26 from the housing 11 and only the filter 20 is economically exchanged.

In addition, when the cover 26 is separated from the housing 11, the filter 20 is upwardly biased by means of the elastic device 18 compressed at the lower portion of the filter 20 so the space section 15 formed between the filter 20 and the housing 11 is enlarged.

Accordingly, the filter 20 can be simply exchanged while preventing oil remaining in the housing 11 from being over-flown.

The auxiliary oil refining apparatus 10 can filter oil together with the oil filter 5, so the cleanliness of oil can be improved. Accordingly, the life span of oil, the filter 5 and the engine 1 can be lengthened. In addition, the filter 20 is only exchanged when it is required to exchange the auxiliary oil refining apparatus 10, so the exchange work for the auxiliary oil refining apparatus 10 can be simply carried out with a high economical effect.

Industrial Applicability As described above, the auxiliary oil refining apparatus of the present invention filters oil together with the oil filter, so the cleanliness of oil can be improved, the exchange period of oil and the oil filter can be extended, and the life span of the engine can be lengthened.

In addition, according to the auxiliary oil refining apparatus of the present invention, the filter accommodated in the auxiliary oil refining apparatus is only exchanged when it is required to exchange the auxiliary oil refining apparatus, so the

auxiliary oil refining apparatus can be semi-permanently used and the cost thereof can be saved.

It should be understood to those skilled in the art that various changes, substitutions and alterations can be made hereto without departing from the scope of the invention as defined by the appended claims.