Oil mist separation device

Abstract

The present invention provides an oil mist separator that can suppress performance degradation due to element clogging and improve the layout flexibility of the oil mist separator. [Solution] The oil mist separation device comprises: at least one filter-type mist separator having an element for removing oil mist from a gas; a centrifugal separator provided upstream of the at least one filter-type mist separator in the direction of gas flow, having blades that rotate when hydraulic oil is supplied, and separating oil mist from the gas by the blades; a hydraulic oil supply line for guiding hydraulic oil to the centrifugal separator; and piping for guiding gas from the centrifugal separator to at least one filter-type mist separator.

Description

Technical Field

[0001] The present disclosure relates to an oil mist separator for removing oil mist from gas.

Background Art

[0002] Some internal combustion engines are equipped with a blow-by gas reflux device that refluxes blow-by gas leaking from between the cylinder and the piston to the intake passage (see, for example, Patent Document 1). The blow-by gas reflux device includes a reflux passage connecting the crankcase and the intake passage, and a blow-by valve provided in the middle of the reflux passage. Further, a mist separator for capturing and separating the oil mist contained in the blow-by gas may be provided in the middle of the reflux passage.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Patent Document 1 discloses capturing oil mist using a filter element housed within a casing. Generally, it is preferable to reduce the amount of oil mist contained in the blow-by gas introduced into the filter element beforehand in order to suppress clogging of the filter element. The invention described in Patent Document 1 aims to reduce the amount of oil mist contained in the blow-by gas by forming a swirling passage within the casing that causes the blow-by gas to swirl by natural convection, but the amount of oil mist that can be reduced by swirling the blow-by gas by natural convection is small. Furthermore, in the invention described in Patent Document 1, since a swirling passage and a filter element are provided within the casing, it leads to a larger casing, making it difficult to place around the internal combustion engine body to which various devices are attached.

[0005] In view of the circumstances described above, at least one embodiment of the present disclosure aims to provide an oil mist separation device that can suppress performance degradation due to element clogging and improve the layoutability of the oil mist separation device. [Means for solving the problem]

[0006] An oil mist separation apparatus according to at least one embodiment of the present disclosure is A filter-type mist separator having an element configured to remove oil mist from a gas, A centrifugal mist separator provided upstream of the at least one filter-type mist separator in the direction of gas flow, having blades that rotate when hydraulic fluid is supplied, and configured to separate the oil mist from the gas by the blades, A hydraulic fluid supply line for guiding the hydraulic fluid to the centrifugal mist separator, The system includes piping for guiding the gas from the centrifugal mist separator to at least one filter-type mist separator. [Effects of the Invention]

[0007] According to at least one embodiment of the present disclosure, an oil mist separator is provided that can suppress performance degradation due to element clogging and improve the layoutability of the oil mist separator. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram of an internal combustion engine system equipped with an oil mist separator according to one embodiment of the present disclosure. [Figure 2] This is a schematic diagram of an oil mist separation apparatus according to one embodiment of the present disclosure. [Figure 3] This is a schematic diagram of an oil mist separation apparatus according to one embodiment of the present disclosure. [Figure 4] This is a schematic cross-sectional view of a filter-type mist separator in one embodiment of the present disclosure. [Modes for carrying out the invention]

[0009] Hereinafter, several embodiments of this disclosure will be described with reference to the attached drawings. However, the dimensions, materials, shapes, relative arrangements, etc., of the components described or shown in the drawings as embodiments are not intended to limit the scope of this disclosure, but are merely illustrative examples.

[0010] (Internal combustion engine system) Figure 1 is a schematic diagram of an internal combustion engine system 100 equipped with an oil mist separator 1 according to one embodiment of the present disclosure. The oil mist separator 1 according to several embodiments is mounted on the internal combustion engine system 100. As shown in Figure 1, the internal combustion engine system 100 includes an internal combustion engine (internal combustion engine body) 101 having a combustion chamber 102, an intake passage 103 for supplying combustion gas to the combustion chamber 102, an exhaust passage 104 for discharging exhaust gas from the combustion chamber 102, and a blow-by gas recirculation device 105 configured to recirculate blow-by gas leaked from the combustion chamber 102 to the intake passage 103. Examples of combustion gases include fresh air, EGR gas, blow-by gas, and mixtures thereof.

[0011] As shown in Figure 1, the internal combustion engine body 101 includes a cylinder 106 having a cylindrical bore 107, a piston 108 housed in the bore 107 of the cylinder 106 and reciprocating in a direction along the axis LA of the bore 107 inside the bore 107, a crankshaft 110 connected to the piston 108 via a connecting rod 109 and converting the reciprocating motion of the piston 108 into rotational motion, and a crankcase 111 having an internal space 112 that houses the crankshaft 110.

[0012] The combustion chamber 102 is defined by the bore 107 of the cylinder 106 and the piston 108. The internal combustion engine body 101 further includes an ignition device (ignition coil) 113 having a spark plug that ignites the mixture of fuel and combustion gas in the combustion chamber 102, as shown in Figure 1. Unburned mixture and other gases may leak from the combustion chamber 102 into the internal space 112 of the crankcase 111. The gas leaked from the combustion chamber 102 is called blow-by gas.

[0013] The blow-by gas recirculation device 105 includes a recirculation passage 114 and a blow-by valve 115. One end of the recirculation passage 114 is connected to the internal space 112 of the crankcase 111, and the other end is connected to the intake passage 103. Blow-by gas is guided from the internal space 112 to the intake passage 103 through the recirculation passage 114. The blow-by valve 115 is provided in the recirculation passage 114 and has an opening / closing mechanism that opens and closes the recirculation passage 114 by an actuator (not shown), and the flow rate of blow-by gas flowing through the recirculation passage 114 can be adjusted by opening and closing the opening / closing mechanism. The oil mist separation device 1 described above is provided in the recirculation passage 114 and is configured to remove oil mist (oil components) contained in the blow-by gas.

[0014] Furthermore, the oil mist separator 1 is not limited to one installed in the internal combustion engine system 100. Also, the gas from which the oil mist separator 1 removes oil mist is not limited to blow-by gas.

[0015] Figures 2 and 3 are schematic diagrams of an oil mist separation device 1 according to one embodiment of the present disclosure. As shown in Figures 2 and 3, an oil mist separation device 1 according to several embodiments comprises at least one (multiple in the illustrated example) filter-type mist separator 2, a centrifugal separator 3 provided upstream of the at least one filter-type mist separator 2 in the gas flow direction, and piping 4 for guiding gas (e.g., blow-by gas) from the centrifugal separator 3 to the at least one filter-type mist separator 2.

[0016] In the embodiments shown in Figures 2 and 3, the return passage 114 includes a pipe 5 for guiding gas from the internal space 112 of the crankcase 111 to the centrifugal mist separator 3, and a pipe 6 for guiding gas discharged from the at least one filter-type mist separator 2. The oil mist separator 1 further includes a hydraulic fluid supply line 7 for guiding hydraulic fluid to the centrifugal mist separator 3, and a hydraulic fluid discharge line 8 for discharging hydraulic fluid from the centrifugal mist separator 3. The hydraulic fluid supply line 7 and the hydraulic fluid discharge line 8 are not limited to pipes, but can each form a flow path for the hydraulic fluid.

[0017] (Filter-type mist separator) Figure 4 is a schematic cross-sectional view of a filter-type mist separator 2 in one embodiment of the present disclosure. Each of the plurality of filter-type mist separators 2 has an element 21 configured to remove oil mist from a gas, as shown in Figures 2 to 4, and a casing 22 having an internal space 25 (see Figure 4) that houses the element 21.

[0018] In the embodiment shown in FIG. 4, the casing 22 includes a cylindrical portion 221 formed in a cylindrical shape extending in the vertical direction along the central axis CA1 of the filter type mist separator 2, an upper lid portion 222 closing the upper opening of the cylindrical portion 221, and a lower lid portion 223 closing the lower opening of the cylindrical portion 221. The internal space 25 of the casing 22 is defined by the cylindrical portion 221, the upper lid portion 222, and the lower lid portion 223.

[0019] A gas inlet 23 for guiding gas from the outside to the inside of the casing 22 is formed in the lower lid portion 223 of the casing 22. The gas inlet 23 opens downward. A gas outlet 24 for discharging gas from the inside to the outside of the casing 22 is formed in the upper lid portion 222 of the casing 22. The gas outlet 24 opens upward.

[0020] When the gas passes through the internal space 25 formed inside the casing 22 from the gas inlet 23 to the gas outlet 24, it passes through the element 21. The element 21 includes a fiber layer such as a non-woven fabric, and adsorbs and removes oil mist from the gas (e.g., blow-by gas) passing through the fiber layer.

[0021] In the embodiment shown in FIG. 4, the element 21 is formed in a cylindrical shape extending in the vertical direction along the central axis CA1 of the filter type mist separator 2. The internal space 25 of the casing 22 is partitioned by an inner space 25A formed radially inside the element 21, an outer space 25B formed radially outside the element 21, and a member housed in the casing 22. The inner space 25A communicates with the gas inlet 23, and the outer space 25B communicates with the gas outlet 24. The inner space 25A communicates with the outer space 25B through the element 21.

[0022] The gas introduced from the outside of the casing 22 into the inner space 25A through the gas inlet 23 passes through the element 21 and is introduced into the outer space 25B. The gas introduced into the outer space 25B is discharged to the outside of the casing 22 (piping 6) through the gas outlet 24.

[0023] Furthermore, since liquid (water droplets) may accumulate on the bottom surface of the lower cover portion 223 facing the outer space 25B, a drain hole 26 is formed on the bottom surface for draining the liquid (water droplets). The drain hole 26 opens downwards.

[0024] (Centrifugal Mist Separator) As shown in Figures 2 and 3, the centrifugal mist separator 3 is installed upstream of the multiple filter-type mist separators 2 (2A, 2B) in the direction of gas flow. The centrifugal mist separator 3 has blades 31 that rotate when hydraulic fluid is supplied, and is configured to separate oil mist from the gas by the blades 31.

[0025] In the embodiments shown in Figures 2 and 3, the centrifugal mist separator 3 includes a rotating shaft 311 extending vertically along the central axis CA2 of the centrifugal mist separator 3, a pair of bearings 312 that rotatably support the rotating shaft 311 on one side and the other side of the rotating shaft 311, a plurality of blades 31 attached to the rotating shaft 311, which are spaced apart in the direction of extension of the rotating shaft 311, and a casing 32 that houses the rotating shaft 311, the pair of bearings 312, and the plurality of blades 31.

[0026] The casing 32 has an upper internal space 35 that rotatably accommodates a plurality of blades 31, and a lower internal space 38 located directly below the upper internal space 35, which rotates the rotating shaft 311 using hydraulic fluid. The casing 32 has a partition wall 321 that extends horizontally and separates the upper internal space 35 and the lower internal space 38. The partition wall 321 has at least one communication hole 322 that connects the upper internal space 35 and the lower internal space 38.

[0027] The casing 32 has a gas inlet 33 for guiding gas from the outside of the casing 32 into the upper internal space 35, and a gas outlet 34 for discharging gas from the upper internal space 35 of the casing 22 to the outside. The gas inlet 33 is connected to the aforementioned piping 5, and the gas outlet 34 opens upward and is connected to the aforementioned piping 4. The gas inlet 33 communicates with the upper internal space 35 and is designed to guide gas into the upper internal space 35 from above. The gas outlet 34 communicates with the upper internal space 35 and is designed to guide gas, from which oil mist has been separated by multiple blades 31, into the piping 4.

[0028] In the embodiments shown in Figures 2 and 3, each of the multiple blades 31 includes an inner circumferential portion 313 extending horizontally outward in the radial direction of the rotating shaft 311 from one end connected to the rotating shaft 311, and an outer circumferential portion 314 that slopes upward from the outer circumferential end of the inner circumferential portion 313 as it extends outward in the radial direction of the rotating shaft 311. The centrifugal force generated by rotating the multiple blades 31 separates the oil mist from the gas flowing in the upper internal space 35. As the multiple blades 31 rotate, the gas flowing in the upper internal space 35 is pushed toward the piping 4.

[0029] The oil separated from the gas in the upper internal space 35 is guided to the lower internal space 38 through the aforementioned communication hole 322.

[0030] The casing 32 is provided with a hydraulic fluid inlet 36 for guiding hydraulic fluid from the outside of the casing 32 into the lower internal space 38, and a hydraulic fluid outlet 37 for discharging hydraulic fluid from the lower internal space 38 of the casing 32 to the outside.

[0031] The hydraulic fluid inlet 36 is connected to one side of the hydraulic fluid supply line 7 described above, and the hydraulic fluid outlet 37 is connected to one side of the hydraulic fluid discharge line 8 described above. In the illustrated embodiment, the other side of the hydraulic fluid supply line 7 and the other side of the hydraulic fluid discharge line 8 are connected to a hydraulic fluid storage device (e.g., a hydraulic fluid storage tank) 9 configured to store hydraulic fluid. The hydraulic fluid supply line 7 is provided with a pump 71 for extracting hydraulic fluid from the hydraulic fluid storage device 9 and sending it to the aforementioned one side of the hydraulic fluid supply line 7.

[0032] The hydraulic fluid inlet 36 communicates with the lower internal space 38 and guides hydraulic fluid to the rotating shaft 311 housed in the lower internal space 38. The rotating shaft 311 has a pressure receiving section 39 that receives pressure from the hydraulic fluid guided into the lower internal space 38 through the hydraulic fluid inlet 36 and generates a rotational force that rotates the rotating shaft 311. Multiple blades 31 rotate together with the rotating shaft 311 which is rotated by the hydraulic fluid. The hydraulic fluid outlet 37 communicates with the lower internal space 38 and discharges the hydraulic fluid that has rotated the rotating shaft 311 and the oil guided into the lower internal space 38 through the communication hole 322 to the outside of the casing 32.

[0033] An oil mist separation device 1 according to several embodiments, as shown in Figures 2 and 3, comprises at least one filter-type mist separator 2 described above, a centrifugal separation type mist separator 3 described above, piping 4 described above, and a hydraulic fluid supply line 7 described above. One end of piping 4 is connected to the gas outlet 34 of the centrifugal separation type mist separator 3, and the other end is connected to the gas inlet 23 of the filter-type mist separator 2.

[0034] The centrifugal separator 3 separates oil mist from the gas using blades 31 that rotate when hydraulic fluid is supplied, resulting in higher oil mist collection efficiency compared to structures that separate oil mist from the gas by utilizing gas flow, such as by swirling the gas. The gas from which the oil mist has been separated by the centrifugal separator 3 is guided to the filter-type mist separator 2. The oil mist separation device 1 can reduce the amount of oil mist contained in the gas guided to the filter-type mist separator 2 by the centrifugal separator 3, thereby suppressing performance degradation due to clogging of the element 21 and reducing the frequency of element 21 replacement.

[0035] Furthermore, the oil mist separation device 1 connects the filter-type mist separator 2 and the centrifugal separator 3 with piping 4, allowing them to be positioned at a distance from each other. Compared to a case where the filter-type mist separator 2 and the centrifugal separator 3 are integrated, this oil mist separation device 1 can suppress the increase in size of the components constituting the oil mist separation device 1 (filter-type mist separator 2, centrifugal separator 3), and offers greater flexibility in the arrangement of these components, thereby improving the layout flexibility of the oil mist separation device 1.

[0036] In some embodiments of the oil mist separation apparatus 1, as shown in Figures 2 and 3, the above-described at least one filter-type mist separator 2 includes a first filter-type mist separator 2A and a second filter-type mist separator 2B. Each of the first filter-type mist separator 2A and the second filter-type mist separator 2B includes the above-described element 21 (21A, 21B) and a casing 22 (22A, 22B) housing the element 21.

[0037] The piping 4 described above includes a first pipe 4A for guiding gas from the centrifugal mist separator 3 to the first filter-type mist separator 2A, and a second pipe 4B that branches off from the first pipe 4A and guides gas to the second filter-type mist separator 2B. One end of the first pipe 4A is connected to the gas outlet 34 of the centrifugal mist separator 3, and the other end is connected to the gas inlet 23A (23) of the first filter-type mist separator 2A. One end of the second pipe 4B is connected to the branch section 40 of the first pipe 4A, and the other end is connected to the gas inlet 23B (23) of the second filter-type mist separator 2B. The gas outlets 24 (24A, 24B) of the first filter-type mist separator 2A and the second filter-type mist separator 2B are connected to the piping 6.

[0038] The gas from which the oil mist has been separated by the centrifugal mist separator 3 is guided to either the first filter-type mist separator 2A or the second filter-type mist separator 2B. In this case, the oil mist can be removed from the gas by the respective elements 21 (21A, 21B) of the first filter-type mist separator 2A and the second filter-type mist separator 2B, thus increasing the amount of oil mist that can be removed compared to an integrated mist separator with the same total capacity of elements 21. Furthermore, even if one element 21 of the first filter-type mist separator 2A or the second filter-type mist separator 2B becomes clogged, the other element 21 can still remove the oil mist from the gas, thus suppressing a decrease in the overall performance of the filter-type mist separator 2.

[0039] In this embodiment, the oil mist separation device 1 connects the first filter-type mist separator 2A and the second filter-type mist separator 2B by a part of the first pipe 4A (the other end of the branching section 40) and the second pipe 4B, thereby allowing the first filter-type mist separator 2A and the second filter-type mist separator 2B to be spaced apart from each other. Compared to the case where the first filter-type mist separator 2A and the second filter-type mist separator 2B are provided as a single unit, this oil mist separation device 1 can suppress the increase in size of the components (2A, 2B) that make up the mist separator 2, and also offers greater flexibility in the arrangement of these components, thus improving the layoutability of the oil mist separation device 1.

[0040] In some embodiments of the oil mist separation device 1, as shown in Figures 2 and 3, the length of the second pipe 4B is equal to the length between the connection point of the first pipe 4A to the second pipe 4B and the first filter-type mist separator 2A. Here, "equal lengths" does not mean that the lengths are exactly the same, but rather that the length of one (the second pipe 4B) satisfies the condition of being 90% or more and 110% or less when the length of the other (the length between the connection point of the first pipe 4A to the second pipe 4B and the first filter-type mist separator 2A) is taken as 100%.

[0041] By making the length of the second pipe 4B equal to the length between the connection point of the first pipe 4A to the second pipe 4B and the first filter-type mist separator 2A (making the pipe lengths the same), it is possible to suppress the uneven distribution of gas flowing to the first filter-type mist separator 2A and the second filter-type mist separator 2B. By suppressing the uneven distribution of gas flowing to the first filter-type mist separator 2A and the second filter-type mist separator 2B, it is possible to suppress the premature clogging of the elements 21 of these mist separators 2 (2A, 2B).

[0042] In the illustrated embodiment, the second filter-type mist separator 2B is the same size and shape as the first filter-type mist separator 2A, and the capacity of the element 21 is also the same. The inner diameter of the second pipe 4B is the same as the inner diameter of the first pipe 4A. In some other embodiments, the second filter-type mist separator 2B may differ in size and shape from the first filter-type mist separator 2A, or the capacity of the element 21 may differ. Also, the inner diameter of the second pipe 4B may differ from the inner diameter of the first pipe 4A.

[0043] In some embodiments of the oil mist separation apparatus 1, as shown in Figures 2 and 3, the piping 4 described above is configured to gradually increase in intensity from the centrifugal mist separator (3) to at least one (multiple in the illustrated example) filter-type mist separator 2.

[0044] In the embodiments shown in Figures 2 and 3, the piping 4 is composed of a combination of a plurality of straight pipe sections 41, 42, 43, 44, and 45 extending in a straight line, and curved sections 46, 47, and 48 that are formed in a curved shape and connect the straight pipe sections aligned in the direction of gas flow. One end of the first straight pipe section 41 is connected to the gas outlet 34, and the other end is connected to the upstream end of the first curved section 46. One end of the second straight pipe section 42 is connected to the downstream end of the first curved section 46, and the other end is connected to the upstream end of the second curved section 47. One end of the third straight pipe section 43 is connected to the downstream end of the second curved section 47. One end of the fourth straight pipe section 44 is connected to the other end of the third straight pipe section 43, and the other end is connected to the upstream end of the third curved section 48. The fifth straight pipe section 45 has one end connected to the downstream end of the third curved section 48 and the other end connected to the gas inlet 23. Each of the multiple straight pipe sections 41, 42, 43, 44, and 45 is inclined with respect to the horizontal direction or extends horizontally, so as it approaches the filter-type mist separator 2, it gradually becomes higher.

[0045] In the embodiments shown in Figures 2 and 3, the first straight pipe section 41, the third straight pipe section 43, and the fifth straight pipe section 45 each extend along the vertical direction, with their other ends positioned above one end. In the embodiment shown in Figure 2, the second straight pipe section 42 and the fourth straight pipe section 44 each extend along the horizontal direction. In the embodiment shown in Figure 3, the second straight pipe section 42 and the fourth straight pipe section 44 each are inclined with respect to the vertical direction such that their other ends are positioned above one end.

[0046] For example, when an internal combustion engine is stopped, the gas inside the pipe 4 cools down, and condensed water may form inside the pipe 4. In the oil mist separation device 1 according to this embodiment, the pipe 4 is configured so that the temperature gradually increases from the centrifugal mist separator 3 to the filter-type mist separator 2, thereby suppressing the accumulation of oil inside the pipe 4. This suppresses the formation of emulsions caused by the mixing of oil and water inside the pipe 4.

[0047] In some embodiments of the oil mist separation apparatus 1, as shown in Figure 3, the piping 4 described above is composed of vertical sections (straight pipe sections 41, 43, 45) extending along the vertical direction, inclined sections (straight pipe sections 42, 44) that are inclined such that the side on which the centrifugal separation mist separator 3 is located is lower than the filter-type mist separator 2 with respect to the vertical direction, and curved sections (46, 47, 48) that are formed in a curved shape and connect the vertical section and the inclined section.

[0048] By configuring the piping 4 with the vertical section, the inclined section, and the curved section, the liquefied oil inside the piping 4 can be guided to the centrifugal mist separator 3. In this case, the accumulation of oil inside the piping 4 can be effectively suppressed.

[0049] In some embodiments of the oil mist separation device 1, as shown in Figures 2 and 3, the hydraulic fluid supply line 7 and the hydraulic fluid discharge line 8 are located below the piping 4. Here, "located below" means that the upper vertical ends of the hydraulic fluid supply line 7 and the hydraulic fluid discharge line 8 are located below the lower vertical end of the piping 4. By locating the hydraulic fluid supply line 7 and the hydraulic fluid discharge line 8 below the piping 4, even if an oil leak occurs in the hydraulic fluid supply line 7 or the hydraulic fluid discharge line 8, the risk of the piping 4 acting as a heat source and igniting the leaked oil can be reduced. Furthermore, in order to reduce the risk of the intake passage 103 and exhaust passage 104 of the internal combustion engine 101 acting as a heat source and igniting the leaked oil, it is preferable to locate the hydraulic fluid supply line 7 and the hydraulic fluid discharge line 8 below the intake passage 103 and exhaust passage 104 of the internal combustion engine 101.

[0050] In some embodiments of the oil mist separator 1, as shown in Figures 2 and 3, the hydraulic fluid supply line 7 and the hydraulic fluid discharge line 8 are located below the ignition device 113 of the internal combustion engine 101. In Figures 2 and 3, the ignition device 113 is shown at a position shifted from its actual position (see Figure 1) (a position away from the internal combustion engine 101) to indicate the height of the ignition device 113. Here, "located below" means that the upper vertical ends of the hydraulic fluid supply line 7 and the hydraulic fluid discharge line 8 are located below the lower vertical end of the ignition device 113. In the embodiments shown in Figures 2 and 3, the hydraulic fluid supply line 7 and the hydraulic fluid discharge line 8 are located below the electrical components connected to the ignition device 113. By positioning the hydraulic fluid supply line 7 and the hydraulic fluid discharge line 8 below the ignition device 113 of the internal combustion engine 101 and the electrical components connected to the ignition device 113, even if an oil leak occurs in the hydraulic fluid supply line 7 or the hydraulic fluid discharge line 8, the risk of the ignition device 113 of the internal combustion engine 101 acting as an ignition source and igniting the leaked oil can be reduced.

[0051] In the oil mist separation apparatus 1 according to several embodiments, when the length of the pipe 4 described above is defined as L and the inner diameter of the pipe 4 is defined as D, the ratio L / D of the length L to the inner diameter D of the pipe 4 is configured to be L / D ≥ 10. Here, when the pipe 4 is connected to multiple filter-type mist separators 2, the length of the pipe 4 between the filter-type mist separator 2 that minimizes the length L of the pipe 4 from the centrifugal mist separator 3 and the centrifugal mist separator 3 is defined as L. The length L of the pipe 4 is the total length obtained by summing the lengths of multiple straight sections and multiple curved sections (for example, the length of the central axis from one end to the other). If the inner diameter of the pipe 4 is not constant, the average value of the inner diameters of the pipe 4 is defined as the inner diameter D.

[0052] By making the length L of the piping 4 long enough to satisfy the condition L / D ≥ 10, the degree of freedom in arranging the components constituting the oil mist separation device 1 (filter-type mist separator 2, centrifugal mist separator 3) can be increased, thereby improving the layoutability of the oil mist separation device 1. In some other embodiments, the ratio L / D of the length L to the inner diameter D of the piping 4 may be configured such that L / D < 10.

[0053] In some embodiments of the oil mist separator 1, as shown in Figure 1, the gas introduced into the oil mist separator 1 is blow-by gas leaking from the combustion chamber 102 of the internal combustion engine 101. The oil mist separator 1 can effectively remove oil mist contained in the blow-by gas leaking from the combustion chamber 102 of the internal combustion engine 101. By providing a high degree of freedom in the arrangement of the components constituting the oil mist separator 1, these components can be arranged around the internal combustion engine 101, thereby suppressing the cooling of the gas guided to these components by the heat generated during the operation of the internal combustion engine 101.

[0054] In this specification, expressions describing relative or absolute arrangements such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" shall not only describe such arrangements strictly, but also describe states of relative displacement with tolerances or angles or distances that allow for the same function to be achieved. For example, expressions such as "identical," "equal," and "homogeneous" that describe things being in an equal state not only describe a state of being strictly equal, but also describe a state in which there is a tolerance or a difference that is sufficient to achieve the same function. Furthermore, in this specification, expressions describing shapes such as quadrilaterals and cylindrical shapes shall not only represent geometrically precise quadrilaterals and cylindrical shapes, but also shapes that include uneven surfaces, chamfered surfaces, etc., to the extent that the same effect can be achieved. Furthermore, in this specification, the expressions “equipment,” “includes,” or “possess” of a component are not exclusive expressions that exclude the existence of other components.

[0055] This disclosure is not limited to the embodiments described above, but also includes modified forms of the embodiments described above, as well as forms that combine these forms as appropriate.

[0056] The contents described in some of the embodiments above can be understood, for example, as follows:

[0057] 1) An oil mist separation apparatus (1) according to at least one embodiment of the present disclosure is: A filter-type mist separator (2) having an element (21) configured to remove oil mist from a gas, A centrifugal separator (3) is provided upstream of the at least one filter-type mist separator (2) in the direction of gas flow, and has a blade (31) that rotates when hydraulic fluid is supplied, and is configured to separate the oil mist from the gas by the blade (31), A hydraulic fluid supply line (7) for guiding the hydraulic fluid to the centrifugal mist separator (3), The system includes a pipe (4) for guiding the gas from the centrifugal mist separator (3) to the at least one filter-type mist separator (2).

[0058] According to the configuration described in 1) above, the centrifugal mist separator (3) separates oil mist from the gas by using blades (31) that rotate when hydraulic fluid is supplied, resulting in a higher oil mist collection efficiency compared to structures that separate oil mist from the gas by utilizing the flow of gas, such as by swirling the gas. The gas from which the oil mist has been separated by the centrifugal mist separator (3) is led to the filter-type mist separator (2). By reducing the amount of oil mist contained in the gas led to the filter-type mist separator (2), performance degradation due to clogging of the element (21) can be suppressed, and the frequency of element (21) replacement can be reduced.

[0059] Furthermore, according to the configuration described in 1) above, by connecting the filter-type mist separator (2) and the centrifugal-type mist separator (3) with piping (4), the filter-type mist separator (2) and the centrifugal-type mist separator (3) can be arranged at a distance from each other. Compared to the case where the filter-type mist separator (2) and the centrifugal-type mist separator (3) are provided as a single unit, this oil mist separation device (1) can suppress the increase in size of the components constituting the oil mist separation device (1) (filter-type mist separator 2, centrifugal-type mist separator 3), and the layout flexibility of the oil mist separation device (1) can be improved because there is a high degree of freedom in the arrangement of these components.

[0060] 2) In some embodiments, the oil mist separation apparatus (1) described in 1) above, The at least one filter-type mist separator (2) includes a first filter-type mist separator (2A) and a second filter-type mist separator (2B), The aforementioned piping (4) is A first pipe (4A) for guiding the gas from the centrifugal mist separator (3) to the first filter-type mist separator (2A), The system includes a second pipe (4B) that branches off from the first pipe (4A) and guides the gas to the second filter-type mist separator (2B).

[0061] According to the configuration described in 2) above, the gas from which the oil mist has been separated by the centrifugal mist separator (3) is guided to either the first filter-type mist separator (2A) or the second filter-type mist separator (2B). In this case, since the oil mist can be removed from the gas by the respective elements (21) of the first filter-type mist separator (2A) and the second filter-type mist separator (2B), the amount of oil mist that can be removed can be increased compared to an integrated mist separator with the same total capacity of elements (21). Furthermore, even if one of the elements (21) of the first filter-type mist separator (2A) or the second filter-type mist separator (2B) becomes clogged, the other element (21) can still remove the oil mist from the gas, thus suppressing a decrease in the overall performance of the filter-type mist separator (2).

[0062] Furthermore, according to the configuration described in 2) above, the first filter-type mist separator (2A) and the second filter-type mist separator (2B) can be connected by a part of the first piping (4A) and the second piping (4B), allowing them to be spaced apart from each other. Compared to the case where the first filter-type mist separator (2A) and the second filter-type mist separator (2B) are provided as a single unit, this oil mist separation device (1) can suppress the increase in size of the components (2A, 2B) that make up the mist separator (2), and also offers greater flexibility in the arrangement of these components, thus improving the layout flexibility of the oil mist separation device (1).

[0063] 3) In some embodiments, the oil mist separation apparatus (1) described in 2) above, The length of the second pipe (4B) is equal to the length between the connection point of the first pipe (4A) to the second pipe (4B) and the first filter-type mist separator (2A).

[0064] According to the configuration described in 3) above, by making the length of the second pipe (4B) equal to the length between the connection point of the first pipe (4A) to the second pipe (4B) and the first filter-type mist separator (2A), it is possible to suppress the uneven distribution of gas flowing to the first filter-type mist separator (2A) and the second filter-type mist separator (2B).

[0065] 4) In some embodiments, the oil mist separation apparatus (1) described in any of 1) to 3) above, The piping (4) is configured to gradually increase in intensity as it moves from the centrifugal mist separator (3) towards the at least one filter-type mist separator (2).

[0066] According to the configuration described in 4) above, for example, when the internal combustion engine (101) is stopped, the gas present inside the piping (4) cools down, and condensed water may form inside the piping (4). By configuring the piping (4) so ​​that the pressure gradually increases from the centrifugal mist separator (3) to the filter-type mist separator (2), the accumulation of oil inside the piping (4) can be suppressed. This suppresses the formation of emulsions caused by the mixing of oil and water inside the piping (4).

[0067] 5) In some embodiments, the oil mist separation apparatus (1) described in 4) above, The piping (4) is composed of a vertical section (straight pipe sections 41, 43, 45 in Figure 3) extending along the vertical direction, an inclined section (straight pipe sections 42, 44 in Figure 3) that slopes downward with respect to the vertical direction such that the side on which the centrifugal mist separator (3) is located is positioned downward, and a curved section (curved sections 46, 47, 48 in Figure 3) that is formed in a curved shape and connects the vertical section and the inclined section.

[0068] According to the configuration described in 5) above, by configuring the piping (4) with the vertical section and the inclined section, the oil that has liquefied inside the piping (4) can be guided to the centrifugal mist separator. In this case, the accumulation of oil inside the piping (4) can be effectively suppressed.

[0069] 6) In some embodiments, the oil mist separation apparatus (1) described in any of 1) to 5) above, The centrifugal mist separator (3) is further provided with a hydraulic fluid discharge line (8) for discharging the hydraulic fluid, The hydraulic fluid supply line (7) and the hydraulic fluid discharge line (8) are each located below the piping (4).

[0070] According to the configuration in 6) above, by placing the hydraulic fluid supply line (7) and the hydraulic fluid discharge line (8) below the piping (4), even if an oil leak occurs in the hydraulic fluid supply line (7) or the hydraulic fluid discharge line (8), the risk of the piping (4) acting as a heat source and igniting the leaked oil can be reduced.

[0071] 7) In some embodiments, the oil mist separation apparatus (1) described in 6) above, The hydraulic fluid supply line (7) and the hydraulic fluid discharge line (8) are each located below the ignition device (113) of the internal combustion engine (101).

[0072] According to the configuration described in 7) above, by locating the hydraulic fluid supply line (7) and the hydraulic fluid discharge line (8) below the ignition device (113) of the internal combustion engine (101), even if an oil leak occurs in the hydraulic fluid supply line (7) or the hydraulic fluid discharge line (8), the risk of the ignition device (113) of the internal combustion engine (101) acting as an ignition source and igniting the leaked oil can be reduced.

[0073] 8) In some embodiments, the oil mist separation apparatus (1) described in 6) or 7) above, The hydraulic fluid supply line (7) and the hydraulic fluid discharge line (8) are located below the intake passage (103) for supplying combustion gas to the combustion chamber (102) of the internal combustion engine (101) and the exhaust passage (104) for discharging exhaust gas from the combustion chamber (102).

[0074] According to the configuration described in 8) above, by placing the hydraulic fluid supply line (7) and the hydraulic fluid discharge line (8) below the intake passage (103) and the exhaust passage (104), even if an oil leak occurs in the hydraulic fluid supply line (7) or the hydraulic fluid discharge line (8), the risk of the hydraulic fluid supply line (7) and the hydraulic fluid discharge line (8) acting as a heat source and igniting the leaked oil can be reduced.

[0075] 9) In some embodiments, the oil mist separation apparatus (1) described in any of 1) to 8) above, When the length of the pipe (4) is defined as L and the inner diameter of the pipe (4) is defined as D, the ratio of the length L to the inner diameter D of the pipe (4), L / D, is configured such that L / D ≥ 10.

[0076] According to the configuration described in 9) above, by making the length L of the piping (4) long enough to satisfy the condition L / D ≥ 10, the degree of freedom in arranging the components constituting the oil mist separation device (1) (filter-type mist separator 2, centrifugal separation-type mist separator 3) can be increased, thereby improving the layoutability of the oil mist separation device (1).

[0077] 10) In some embodiments, the oil mist separation apparatus (1) described in any of 1) to 9) above, The aforementioned gas is blow-by gas leaking from the combustion chamber (102) of the internal combustion engine (101).

[0078] According to the configuration described in 10) above, the oil mist separator (1) can effectively remove oil mist contained in the blow-by gas leaking from the combustion chamber (102) of the internal combustion engine (101). By allowing a high degree of freedom in the arrangement of the components of the oil mist separator (1), these components can be arranged around the internal combustion engine (101), thereby suppressing the cooling of the gas guided to these components by the heat generated during the operation of the internal combustion engine (101). [Explanation of symbols]

[0079] 1. Oil mist separation device 2. Filter-type mist separator 2A First filter type mist separator 2B Second filter type mist separator 21 elements 22 Casing 23 Gas Inlet 24 Gas outlet 3. Centrifugal Mist Separator 31 Wings 32 Casing 33 Gas Inlet 34 Gas outlet 35 Upper internal space 36 Hydraulic oil supply port 37 Hydraulic oil outlet 38 Lower interior space 4 Piping 4A First Piping 4B Second Piping 7. Hydraulic fluid supply line 8. Hydraulic fluid discharge line 9. Hydraulic fluid storage device 100 Internal Combustion Engine Systems 101 Internal Combustion Engine 102 Combustion chamber 113 Ignition system

Claims

1. A filter-type mist separator having an element configured to remove oil mist from a gas, A centrifugal mist separator provided upstream of the at least one filter-type mist separator in the direction of gas flow, having blades that rotate when hydraulic fluid is supplied, and configured to separate the oil mist from the gas by the blades, A hydraulic fluid supply line for guiding the hydraulic fluid to the centrifugal mist separator, The system includes piping for guiding the gas from the centrifugal mist separator to at least one filter-type mist separator. Oil mist separation device.

2. The at least one filter-type mist separator includes a first filter-type mist separator and a second filter-type mist separator. The aforementioned piping is A first pipe for guiding the gas from the centrifugal mist separator to the first filter-type mist separator, The system includes a second pipe that branches off from the first pipe and guides the gas to the second filter-type mist separator, The oil mist separation apparatus according to claim 1.

3. The oil mist separation apparatus according to claim 2, wherein the length of the second pipe is equal to the length between the connection portion of the first pipe to the second pipe and the first filter-type mist separator.

4. The piping is configured such that the temperature gradually increases from the centrifugal mist separator towards the at least one filter-type mist separator. An oil mist separation apparatus according to any one of claims 1 to 3.

5. The piping comprises a vertical section extending along the vertical direction, an inclined section that slopes downward with respect to the vertical direction such that the side on which the centrifugal mist separator is located is downward, and a curved section formed in a curved shape that connects the vertical section and the inclined section. Composed of, The oil mist separation apparatus according to claim 4.

6. The system further comprises a hydraulic fluid discharge line for discharging the hydraulic fluid from the centrifugal mist separator. The hydraulic fluid supply line and the hydraulic fluid discharge line are each located below the piping, An oil mist separation apparatus according to any one of claims 1 to 3.

7. The aforementioned hydraulic fluid supply line and the aforementioned hydraulic fluid discharge line are each located below the ignition device of the internal combustion engine. The oil mist separation apparatus according to claim 6.

8. The aforementioned hydraulic fluid supply line and the aforementioned hydraulic fluid discharge line are located below the intake passage for supplying combustion gas to the combustion chamber of the internal combustion engine and the exhaust passage for discharging exhaust gas from the combustion chamber. The oil mist separation apparatus according to claim 6.

9. When the length of the pipe is defined as L and the inner diameter of the pipe is defined as D, the ratio of the length L to the inner diameter D of the pipe, L / D, is configured such that L / D ≥ 10. An oil mist separation apparatus according to any one of claims 1 to 3.

10. The aforementioned gas is blow-by gas leaking from the combustion chamber of an internal combustion engine. An oil mist separation apparatus according to any one of claims 1 to 3.

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