JP5992784B2 - Oil strainer - Google Patents

Description

  The present invention relates to an oil strainer used for an oil circulation system or the like in a transmission such as an automatic transmission (AT) or an automatic continuously variable transmission (CVT) of an automobile.

  As an oil strainer mounted on an oil circulation system in an automatic transmission of an automobile or the like, there is conventionally known an oil strainer as shown in FIG.

  That is, in this type of oil strainer, a lower case 101 having an inflow port 101a and an upper case 102 having an outflow port 102a opened at a different position in the plane direction from the inflow port 101a are vibration welded between the outer peripheral flanges 101b and 102b. In the internal space of the case 100, a sheet-like material made of nonwoven fabric or the like is formed so as to partition the internal space into a lower chamber S1 on the lower case 101 side (inlet 101a side) and an upper chamber S2 on the upper case 102 side (outlet 102a side). A structure in which the filter medium 103 is arranged is provided (see, for example, Patent Document 1 below).

  This oil strainer is installed in the oil pan 200, and an outlet 102a provided in the upper case 102 is connected to a suction hose 201 that extends to a suction port of an oil pump (not shown). For this reason, oil (engine oil) O in the oil pan 200 flows into the lower chamber S1 in the case 100 from the inlet 101a, passes through the filter medium 103 into the upper chamber S2, and is filtered, and then suctioned from the outlet 102a. It is sucked into the oil pump through the hose 201.

  However, since oil is swirled at high speed by a gear or the like inside the automatic transmission, the oil O in the oil pan 200 contains many fine bubbles AB, and these bubbles AB have a specific gravity over time. Although it floats to the oil surface due to the difference and disappears, a part of the oil accumulates below the outer peripheral flange 101b of the lower case 101, or flows into the lower chamber S1 together with the oil O and accumulates on the lower surface of the filter medium 103. The bubbles AB accumulated on the lower surface of the filter medium 103 hinder the flow of the oil O to the oil pump, so that not only the amount of oil is insufficient, but also the bubbles AB that have passed through the filter medium 103 flow to the oil pump. It is also pointed out that this bubble collapses by being compressed by, and the oil pump is damaged by the shock wave generated at that time.

  Further, in Patent Document 1, a notch is provided in the outer peripheral flange 101b of the case 100 in order to facilitate the extraction of the air bubble AB, and such a notch extracts the air bubbles AB accumulated under the outer peripheral flange 101b of the lower case 101. However, the bubbles AB accumulated on the lower surface of the filter medium 103 cannot be removed.

  On the other hand, measures against air bubbles by adding an antifoaming agent (antifoaming agent) to oil are also known, but there is a problem that the performance of the oil deteriorates when a large amount of antifoaming agent is added.

JP 2001-124188 A

  The present invention has been made in view of the above points, and its technical problem is to provide an oil strainer capable of effectively preventing air bubbles in oil from staying in a filter medium or the like. It is in.

As means for effectively solving the technical problem described above, an oil strainer according to the invention of claim 1 includes a case in which an inlet is opened on the lower side and an outlet is opened on the upper side, and an inner chamber of the case. A main filter medium provided so as to be divided into a lower chamber on the inlet side and an upper chamber on the outlet side, and an outer end of the inlet is provided so as to protrude to the outside of the inlet. It is covered with a sub-filter medium, and has an attachment flange that extends upward and is covered with the sub-filter medium at the outer end of the inlet, and an expansion chamber is provided between the attachment flange and the sub-filter medium. is there. With such a configuration, in the process of oil flowing into the inlet, bubbles in the oil are captured by the sub-filter medium provided at the outer end of the inlet, so that the bubbles flow into the lower chamber in the case. Thus, accumulation on the lower surface of the main filter medium can be prevented. Since the auxiliary filter medium is provided so as to protrude outside the inflow port, the trapped bubbles are easily lifted by the buoyancy and are easily separated from the auxiliary filter medium, and thus the bubbles are prevented from staying in the auxiliary filter medium. Moreover, even if a part of the air bubbles passes through the sub-filter medium, the air bubbles are separated from the oil by buoyancy in the expansion chamber between the mounting flange and the sub-filter medium and float up. Therefore, it is possible to prevent bubbles from flowing into the lower chamber in the case from the inlet and collecting on the lower surface of the main filter medium.

  An oil strainer according to a second aspect of the present invention is the structure according to the first aspect, wherein the sub-filter medium has a gradient. With such a configuration, the retention of bubbles in the sub-filter medium is more reliably prevented.

  An oil strainer according to a third aspect of the present invention is the oil strainer according to the first or second aspect, wherein the auxiliary filter medium is coarser than the main filter medium. With such a configuration, first, bubbles in the oil are captured in the sub-filter medium, and only fine foreign matters that have passed through the sub-filter medium are captured in the main filter medium.

An oil strainer according to a fourth aspect of the present invention is the oil strainer according to any one of the first to third aspects, wherein the sub-filter medium is a non-woven fabric, and a restraining portion is formed by integrally molding a rubber-like elastic material on the sub-filter medium. Formed. With such a configuration, even if the sub-filter medium is made of a nonwoven fabric, the restraining portion restrains the fibers of the nonwoven fabric, so that it is possible to prevent the occurrence of contamination due to the dropping of the fibers.

An oil strainer according to a fifth aspect of the present invention is the oil strainer according to the fourth aspect , wherein the restraining portions are formed at intervals shorter than the fiber length of the nonwoven fabric. With such a configuration, it is possible to more reliably prevent the occurrence of contamination due to fiber dropping.

The oil strainer according to the invention of claim 6 is the structure according to any one of claims 1 to 5 , wherein the sub-filter medium is made of a highly lipophilic material. With such a configuration, the effect of removing air bubbles by the sub-filter medium is further improved, and the oil preferentially permeates by improving the wettability of the sub-filter medium with respect to the oil, so that the filtration time can be shortened.

  According to the oil strainer according to the present invention, it is possible to effectively prevent bubbles in the oil from staying on the lower surface of the filter medium, and to reduce the flow rate of oil to the oil pump due to the bubbles on the lower surface of the filter medium. The bad influence by the bubble which passed to oil pump with oil can be prevented.

It is sectional drawing which shows 1st embodiment of the oil strainer which concerns on this invention. It is sectional drawing of the use condition which shows 1st embodiment of the oil strainer which concerns on this invention. It is sectional drawing which shows 2nd embodiment of the oil strainer which concerns on this invention. It is sectional drawing which shows 3rd embodiment of the oil strainer which concerns on this invention. FIG. 5 is a view in the direction of the arrow V in FIG. 4, in which the left side of the alternate long and short dash line indicates a state in which the auxiliary filter medium is attached, and the right side indicates a state in which the auxiliary filter medium is excluded. It is sectional drawing of the use condition which shows 3rd embodiment of the oil strainer which concerns on this invention. It is sectional drawing which shows 4th embodiment of the oil strainer which concerns on this invention. FIG. 8 is an arrow view in the VIII direction in FIG. 7. It is sectional drawing which shows 5th Embodiment of the oil strainer which concerns on this invention. It is sectional drawing which shows 6th Embodiment of the oil strainer which concerns on this invention. In the XI direction view in FIG. 10, the left side of the alternate long and short dash line shows a state where the sub-filter medium is attached, and the right side shows a state where the sub-filter medium is excluded. It is explanatory drawing which shows the example of a change of the sub filter medium in 6th Embodiment. It is explanatory drawing which shows the other example of a change of the sub filter medium in 6th Embodiment. It is explanatory drawing which shows the other example of a change of the sub filter medium in 6th Embodiment. It is a figure for substituting and explaining lipophilicity with the contact angle (wetting angle) of the water with respect to a film. It is explanatory drawing which shows the method of a performance test schematically. It is sectional drawing of the use condition which shows the conventional oil strainer.

  Hereinafter, preferred embodiments of an oil strainer according to the present invention will be described in detail with reference to the drawings. First, FIG. 1 shows a first embodiment.

  The oil strainer 1 according to the first embodiment shown in FIG. 1 includes a case 10 in which an inlet 11 is opened on the lower side and an outlet 12 is opened on the upper side, and an inner chamber of the case 10 is connected to the inlet 11 side. And a main filter medium 20 provided so as to be partitioned into an upper chamber S2 on the outlet 12 side, and an outer end of the inlet 11 is provided so as to protrude to the outside of the inlet 11. The secondary filter medium 30 is covered.

  Specifically, the case 10 is formed of a synthetic resin material, and has a dish-like lower case 13 having a cylindrical opening 13a facing downward and a dish-like shape having a cylindrical opening 14a forming an outlet 12. The upper case 14 includes a cylindrical case 15 that is attached to the cylindrical opening 13 a of the lower case 13 via a packing 16 and extends substantially perpendicular to the bottom surface of the lower case 13 to form the inlet 11.

  The main filter medium 20 and the sub filter medium 30 may be made of a non-woven fabric having high heat resistance and lipophilicity, a metal mesh, or a porous plate having high heat resistance and lipophilicity, and the main filter medium may be used. The outer peripheral edge 21 is sandwiched between the outer peripheral flange 13b of the lower case 13 and the inner peripheral part of the outer peripheral flange 14b of the upper case 14 which are joined to each other by vibration welding or the like. It can be captured. On the other hand, the sub-filter medium 30 is coarser than the main filter medium 20 and is arranged so as to cover the inflow port 11 from the outside (lower side), and the outer peripheral portion 32 forms the inflow port 11. The casing 15 is fitted into an annular groove 151a formed on the mounting flange 151 at the outer end of the case 15, and is attached by means such as adhesion, so that mainly bubbles in the oil can be captured.

  Further, the mounting flange 151 at the outer end of the cylindrical case 15 is formed obliquely with respect to the extending direction of the cylindrical case 15, and as a result, is inclined with respect to the bottom surface of the lower case 13, so that the sub-filter medium attached thereto 30 is also inclined.

  When the sub-filter medium 30 is made of a metal mesh, the outer peripheral portion 32 is preformed into the illustrated bent shape, and is fitted or caulked and fixed to the outer peripheral surface of the mounting flange 151 of the cylindrical case 15.

  As shown in FIG. 2, the oil strainer 1 having the above-described configuration is installed substantially horizontally while being immersed in oil (engine oil) O stored in an oil pan. The side outlet 12 is connected to a suction hose 2 that extends to an inlet of an oil pump (not shown). For this reason, the oil O in the oil pan is in the process of flowing into the inflow port 11 by the drive of the oil pump, first the bubbles AB are captured by the sub filter medium 30, and further in the process of flowing into the upper chamber S2 from the lower chamber S1. Fine foreign matter is captured by the main filter medium 20 and is sucked into the oil pump from the outlet 12 via the suction hose 2.

  That is, according to the oil strainer 1, the bubbles AB in the oil O are first captured by the sub-filter medium 30, so that the bubbles AB are prevented from flowing into the lower chamber S 1 in the case 10 and collecting on the lower surface of the main filter medium 20. can do. Further, since the secondary filter medium 30 protrudes from the mounting flange 151 of the cylindrical case 15 to the outside of the inflow port 11 and has an appropriate gradient, the trapped air bubbles AB are lifted by buoyancy and separated from the secondary filter medium 30. Further, the retention of the bubbles AB on the lower surface of the sub filter medium 30 is also prevented.

  Therefore, the flow rate of the oil O is reduced due to the bubbles AB remaining on the lower surfaces of the main filter medium 20 and the sub-filter medium 30, and hence the flow rate of the oil O to the oil pump is decreased, and the bubbles AB pass through the main filter medium 20. An adverse effect on the oil pump caused by flowing to the oil pump together with the oil O can be prevented. For this reason, since it is not necessary to add a large amount of antifoaming agent (antifoaming agent) to the oil, it is possible to prevent deterioration of the performance of the oil.

  In the first embodiment, since the secondary filter medium 30 is provided so as to protrude to the outside of the inflow port 11, the trapped bubbles AB are formed on the lower surface of the secondary filter medium 30 even when it is substantially horizontal. Does not stay, so it does not necessarily have to be inclined as shown.

  Next, FIG. 3 shows a second embodiment of the oil strainer according to the present invention. In the oil strainer 1 of the second embodiment, the difference from the first embodiment is that the case 10 is provided with a plurality of inlets 11 by the cylindrical case 15. That is, a plurality of cylindrical openings 13 a are formed in the lower case 13 of the case 10, and a cylindrical case 15 is attached to each of the cylindrical openings 13 a via the packing 16, and the outer end of each cylindrical case 15 is inclined. The auxiliary filter medium 30 is attached to the attachment flange 151 in the same manner as in the first embodiment.

  In this way, the filtration area by the sub-filter medium 30 is increased, so that the bubble removal capability can be improved as compared with the first embodiment.

  Next, FIG. 4 is a sectional view showing a third embodiment of the oil strainer according to the present invention, and FIG. 5 is a view in the direction of the arrow V in FIG.

  In the oil strainer 1 of the third embodiment, the difference from the first embodiment is that a mounting flange 152 extending obliquely upward is formed at the outer end of the cylindrical case 15 forming the inflow port 11 and the mounting flange 152. A plurality of ribs 153 projecting from each other, and an extension chamber S3 extending in the vertical direction along the ribs 153 is provided between the mounting flange 152 and the sub-filter medium 30.

  Specifically, the inlet 11 formed by the cylindrical case 15 attached to the cylindrical opening 13a of the lower case 13 in the case 10 via the packing 16 has a portion 11a extending substantially perpendicular to the bottom surface of the lower case 13, The outer end opening 11b is opened from the lower part in a substantially horizontal direction. The outer end opening 11b is located at the lower center of the mounting flange 152 developed from the outer end of the cylindrical case 15, and is shown in FIG. As shown, the outer peripheral edge 152a of the mounting flange 152 is formed along a virtual plane that is moderately inclined.

  The sub filter medium 30 that is coarser than the main filter medium 20 protrudes to the outside of the inflow port 11 so as to cover the front side of the mounting flange 152 including the outer end opening 11b of the inflow port 11 from the outside (lower side). The outer peripheral portion 32 is fitted into an annular groove 152b formed on the outer peripheral edge 152a of the mounting flange 152 and attached by means such as adhesion. Therefore, this sub filter medium 30 is also inclined moderately.

  The secondary filter medium 30 is supported in a state of being separated from the mounting flange 152 by a plurality of ribs 153 that protrude from the front surface of the mounting flange 152 and extend in the vertical direction. The expansion chamber S3 is inflow port by the rib 153. 11 is formed so as to extend above the outer end opening 11b.

  As shown in FIG. 6, according to the oil strainer 1, as in the first embodiment, the air bubbles AB in the oil O can be captured by the sub filter medium 30, and the sub filter medium 30 has a cylindrical case. Since it is provided on the mounting flange 152 that largely protrudes from the outer end of 15, the filtration area is large and, therefore, the bubble removing ability is high. Further, since the secondary filter medium 30 protrudes from the mounting flange 152 of the cylindrical case 15 to the outside of the inflow port 11 and has an appropriate gradient, the trapped air bubbles AB are lifted by buoyancy and separated from the secondary filter medium 30. Further, the retention of the bubbles AB on the lower surface of the sub filter medium 30 is also prevented.

  Moreover, even if some of the bubbles AB pass through the sub-filter medium 30, the bubbles AB are separated from the oil O by buoyancy in the expansion chamber S3 behind the sub-filter medium 30, and float along the ribs 153. It is difficult to flow into the outer end opening 11b of the inflow port 11 opened at the lower part of the chamber S3, and therefore, the bubbles AB are more reliably prevented from flowing into the lower chamber S1 in the case 10 and collecting on the lower surface of the main filter medium 20. be able to.

  Also, the bubbles AB accumulated in the upper part of the expansion chamber S3 due to buoyancy are discharged from the upper part of the coarse filter medium 30 to the outside (in the oil pan).

  Next, FIG. 7 is a sectional view showing a fourth embodiment of the oil strainer according to the present invention, and FIG. 8 is a view taken in the direction of arrow VIII in FIG.

In the oil strainer 1 of the fourth embodiment, the difference from the first embodiment shown in FIG. 1 is that the main body portion 31 of the sub-filter medium 30 is made of non-woven fabric, and the outer peripheral portion 32 is rubber-like elastic. It consists of a material (rubber material or synthetic resin material having rubber-like elasticity). That is, the outer peripheral portion 32 of the sub-filter medium 30 in which the main body portion 31 is made of a nonwoven fabric is impregnated with a rubber-like elastic material and is formed into a bent shape having a substantially L-shaped cross section. The outer peripheral portion 32 corresponds to the restraint portion described in claim 4 and closely contacts an annular groove 151 a formed in the mounting flange 151 at the outer end of the cylindrical case 15 forming the inflow port 11. It is attached by fitting.

  According to the oil strainer 1 having the above configuration, in addition to the effect of the first embodiment shown in FIG. 1, the sub filter medium 30 is firmly fixed to the mounting flange 151 of the cylindrical case 15 to ensure the required sealing performance and strength. can do. In addition, in the case where the main body portion 31 of the sub-filter medium 30 is made of a nonwoven fabric, some of the fibers may be separated and become contaminated. According to the above configuration, the outer peripheral portion 32 is impregnated with a rubber-like elastic material. Therefore, the occurrence of such contamination can be suppressed.

  FIG. 9 shows a fifth embodiment of an oil strainer according to the present invention, and FIGS. 10 and 11 show a sixth embodiment. Among these, the fifth embodiment shown in FIG. 9 is obtained by applying the configuration of the sub-filter medium 30 according to the fourth embodiment to the second embodiment shown in FIG. The sixth embodiment shown in FIG. 11 is obtained by applying the configuration of the sub-filter medium 30 according to the fourth embodiment to the third embodiment shown in FIG. Therefore, in addition to the effects of the second embodiment or the third embodiment, the required sealing performance and strength of the sub-filter medium 30 are ensured and the occurrence of contamination is obtained.

  Moreover, FIGS. 12-14 shows the modification for raising the intensity | strength of the sub filter medium 30 in which the main-body part 31 consists of a nonwoven fabric in 6th Embodiment shown in FIG.10 and FIG.11, respectively.

  Of these, the example shown in FIG. 12 is one in which restraint portions 33 impregnated with a rubber-like elastic material are formed in lattice points on a main body portion 31 of a sub-filter medium 30 made of nonwoven fabric. Preferably, the interval between the restraining portions 33 is shorter than the fiber length of the nonwoven fabric in the main body portion 31. Although the nonwoven fabric of the main-body part 31 has a short fiber length, and what is formed only by the entanglement of a fiber, according to the structure shown in FIG. 12, it is based on the outer peripheral part 32 impregnated with the rubber-like elastic material. In addition to the restraint of the fibers, the restraint portions 33 formed in the main body portion 31 at intervals shorter than the fiber length restrain the fibers of the nonwoven fabric, so that the occurrence of contamination due to the dropping of the fibers can be prevented.

  Further, in the example shown in FIG. 13, a plurality of restraining portions 33 impregnated with the elastic material are connected to the body portion 31 of the sub-filter medium 30 made of nonwoven fabric continuously from the outer peripheral portion 32 impregnated with the rubber-like elastic material. They are formed in parallel straight lines. Some nonwoven fabrics have fiber directionality. In such a case, the restraint portions 33 shown in FIG. 13 are formed so as to be orthogonal to the fiber direction and at intervals shorter than the fiber length. Therefore, it is possible to prevent the occurrence of contamination due to fiber dropping.

  Further, in the example shown in FIG. 14, a plurality of constraining portions 33 impregnated with the elastic material are latticed on the main body portion 31 of the sub-filter medium 30 made of nonwoven fabric from the outer peripheral portion 32 impregnated with the rubber-like elastic material. It is formed in a shape. Also in this example, the fibers of the nonwoven fabric can be reliably restrained by forming the spacing of the restraining portions 33 at an interval shorter than the fiber length.

  In any of the examples shown in FIGS. 12 to 14, the restraining portion 33 can be formed simultaneously with the outer peripheral portion 32, and the same material and thickness as the outer peripheral portion 32 or different materials and thicknesses may be used. Moreover, the restraint part 33 can be similarly formed even if the main body part 31 of the sub-filter medium 30 is other than a non-woven fabric, for example, a woven or mesh-like one.

  Further, such a restraining portion 33 can be applied to the embodiment shown in FIGS. 7 and 9.

  In the illustrated embodiments, as described above, the sub-filter medium 30 is made of a non-woven fabric having high heat resistance and lipophilicity, made of a metal mesh, or porous having high heat resistance and lipophilicity. A plate or the like can be suitably used.

Of these, when the filter medium 13 is made of a nonwoven fabric, the nonwoven fabric is a highly lipophilic nonwoven fabric such as PE (Polyethylene), PS (Polystyrene), PP (Polypropylene), carbon fiber, PET (Polyethylene).
terephthalate) fibers and PP-PE core-sheath fibers are used. The fiber of PP-PE core-sheath structure has a double structure in which the center of each fiber is PP and the outer periphery is PE.

  Here, “highly lipophilic” is substituted with a water contact angle (wetting angle) with respect to the film, and when this wetting angle is 70 ° or more, this film is defined as having high lipophilicity. In addition, as shown in FIG. 15, the wetting angle means that when a water droplet w is placed on the surface of the film f, the tangent to the surface of the edge of the water droplet w that intersects the surface of the film f is relative to the surface of the film f. This is the angle θ formed.

The fact that the oil contact angle can be substituted by water wettability can be explained by the idea of critical surface tension. I.e.
Wa = cos θ = 1 + b (γc−γL)
Wa: Adhesion work (work that separates liquid from solid surface of unit area)
θ: contact angle γc: surface tension of solid γL: surface tension of liquid is high in lipophilicity (large work of adhesion of oil to solid surface) means that the surface tension of solid is as small as oil, that is, solid This means that the difference between the surface tension γc of the liquid and the surface tension γL of the liquid (oil) (γc−γL) is small, in other words, the difference between the surface tension with water and the cosθ is small. That is, the contact angle θ with water is large. For example, when the liquid is replaced with paraffin oil → water, the surface tension of paraffin oil is 26 dyne / cm, whereas the surface tension of water is 72 dyne / cm, so the difference between γc and γL in comparison with oil Is large, that is, the contact angle θ is large (wetting property is small).

  When the sub-filter medium 30 is made of a porous plate having high heat resistance and high lipophilicity, the porous plate is made of a sintered porous plate of non-oxide ceramic particles such as silicon carbide (SiC) and has a porosity of 30% or more is used. The thickness of the porous plate is preferably 0.5 to 3.0 mm. This is because the strength is insufficient when the thickness is less than 0.5 mm, and the filtration flow rate of oil becomes insufficient when the thickness exceeds 3.0 mm. Moreover, the hole diameter of a perforated plate is 0.1-10 micrometers. This is because if the pore diameter is less than 0.1 μm, the filtration flow rate of the oil is insufficient, and if it exceeds 10 μm, the strength is insufficient.

  Conventionally, wire mesh such as expanded metal or non-woven fabric of organic fibers has been used as filter material for oil strainers. However, if the filter media is made of wire mesh, the filter media when the oil becomes hot is used. While heat resistance is ensured, bubbles are likely to pass through due to large openings, and when the wire mesh is made of stainless steel, the stainless steel is insufficiently lipophilic, so if bubbles accumulate on the filter medium surface, There is a possibility that the filtration of the water is hindered.

  On the other hand, when the secondary filter medium 30 is made of a porous plate having high heat resistance and lipophilicity, such as a carbon fiber nonwoven fabric or a sintered porous plate of non-oxide ceramic particles, the wettability of the secondary filter medium 30 with respect to oil is improved. Oil can permeate preferentially. For this reason, even when a large amount of bubbles are contained in the oil, oil filtration is less likely to be hindered, and a shortage of the amount of oil supplied to the oil pump can be prevented.

  Next, the results of the performance test of the oil strainer of the present invention will be described.

  In this test, as shown in FIG. 16, oil O is circulated between a container 501 and a transparent observation container 502 installed outside thereof using an oil pump 503, and the homogenizer is added to the oil in the container 501. The case where cavitation bubbles are generated by the vibrator 504a using the vibrator 504 and the oil O traveling from the container 501 to the observation container 502 is filtered by the oil strainer 505 installed in the container 501 and when the oil strainer 505 is not attached. Then, the presence or absence of inflow of bubbles into the observation container 502 was observed. Reference numeral 506 is an observation camera, and reference numeral 507 is a negative pressure gauge for confirming oil permeability by measuring a pressure loss caused by an oil strainer 505 (filter medium).

As the filter medium of the oil strainer 505, a lipophilic nonwoven fabric having the characteristics shown in Table 1 was used. The oil flow rate by the oil pump 503 was 2.2 to 2.3 L / min.

  As a result of the test, when the oil strainer 505 is attached, there are almost no bubbles in the oil O in the observation vessel 502, and when the oil strainer 505 is not attached, the oil O in the observation vessel 502 is clouded by a large amount of bubbles. Was.

  Next, the effect was compared between the case where a lipophilic nonwoven fabric was used for the filter medium of the oil strainer 505 and the case where a non-lipophilic nonwoven fabric was used. Specifically, as an example, a non-lipophilic non-woven fabric made of a single PET fiber is used as a filter medium as a filter medium, and a non-lipophilic non-woven cloth made of a single PET fiber is used as a filter medium as a comparative example. It was.

  As a result of this comparative test, a non-woven fabric made of PE, PS, PP, carbon fiber having a water contact angle of 70 ° or more, or a non-woven fabric made of a mixture of PET fibers and PP-PE core-sheath structure fibers was used as a filter medium. The oil O in the observation container 502 was transparent, almost no bubbles were observed, and the oil permeability was good, but a comparison using a non-lipophilic nonwoven fabric made of a single PET fiber having a water contact angle of less than 70 ° In the example, white turbidity due to mixing of bubbles was confirmed in the oil O in the observation container 502. Therefore, it was confirmed that the example using the lipophilic non-woven fabric having a water contact angle of 70 ° or more is excellent in air bubble removal and oil permeability.

  Therefore, since the effect of removing bubbles in the oil is improved by using a lipophilic nonwoven fabric or a ceramic porous plate for the sub-filter medium 30 of the oil strainer according to the present invention, the bubbles stay on the lower surface of the main filter medium 20. A decrease in the filtration flow rate of the oil O can be prevented, and the required flow rate of the oil O can be ensured because the nonwoven fabric or ceramic porous plate having lipophilicity is excellent in oil permeability.

  In addition, from the above test results, even if the PET fiber alone is low in lipophilicity, the oil O in the observation container 502 is transparent when the nonwoven fabric obtained by mixing the fibers of the PP-PE core-sheath structure is used as a filter medium. Since almost no air bubbles were seen, even with low lipophilic fibers, mixing with high lipophilic PE, PS, PP, carbon fiber, etc. can provide excellent bubble removal and oil permeability. all right.

DESCRIPTION OF SYMBOLS 1 Oil strainer 10 Case 11 Inlet 11b Outer end opening 12 Outlet 15 Cylindrical cases 151, 152 Mounting flange 153 Rib 20 Main filter medium 30 Sub filter medium 32 Outer peripheral part (restraint part)
33 Restraint section S1 Lower chamber S2 Upper chamber S3 Expansion chamber

Claims (6)

A case in which an inlet is opened on the lower side and an outlet is opened on the upper side, and a main filter medium provided to partition an inner chamber of the case into a lower chamber on the inlet side and an upper chamber on the outlet side; And an outer end of the inlet is covered with a sub-filter medium provided so as to protrude outward from the inlet, and the outer end of the inlet is extended upward and covered with the sub-filter medium. An oil strainer having a flange, wherein an expansion chamber is provided between the mounting flange and the sub-filter medium .   The oil strainer according to claim 1, wherein the sub-filter medium has a gradient.   The oil strainer according to claim 1 or 2, wherein a filter medium coarser than the main filter medium is used as the sub-filter medium. The oil strainer according to any one of claims 1 to 3, wherein the sub-filter medium is made of a nonwoven fabric, and a restraint portion is formed on the sub-filter medium by integrally molding a rubber-like elastic material . The oil strainer according to claim 4 , wherein the restraining portions are formed at intervals shorter than the fiber length of the nonwoven fabric . The oil strainer according to any one of claims 1 to 5, wherein the sub-filter medium is made of a highly lipophilic material .

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