Blow-by gas recirculation device and head cover

Abstract

To provide a blowby gas recirculation device which achieves the suppression of condensation of water vapor in a blowby gas in a branched recirculation passage.SOLUTION: A blowby gas recirculation device 20 makes a blowby gas generated in an engine 1 having a plurality of cylinders recirculate to an intake system of the engine 1. The blowby gas recirculation device 20 comprises a distribution part 13 arranged in a head cover 3 of the engine 1, and distributing the blowby gas to intake paths of the cylinder. The distribution part 13 comprises an introduction part 13a into which the blowby gas is introduced, and a plurality of branched paths 13c communicating with the introduction part 13a, branched from the introduction part 13a, and communicating with the intake paths.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a blow-by gas recirculation device and a head cover. [Background technology]

[0002] Conventionally, blow-by gas recirculation devices have been known that have a structure that recirculates blow-by gas from the crankcase through an intake manifold to the intake port of the engine in order to prevent air pollution and deterioration of lubricating oil caused by blow-by gas leaking from the engine's combustion chamber into the crankcase.

[0003] In cold climates, the blow-by gas is introduced into the intake manifold while it is still cold when the engine is started, and the water vapor contained in the blow-by gas can be rapidly cooled and condensed to form ice blocks, which can be sucked into the engine combustion chamber and cause misfires.

[0004] Therefore, in order to suppress the condensation of water vapor in the blow-by gas, it is necessary to recirculate the blow-by gas to each cylinder near the combustion chamber, which is slow to cool and easy to warm up quickly. At the same time, it is also necessary to recirculate the blow-by gas uniformly between each cylinder to suppress variations in intake air quality between the cylinders.

[0005] As a technology created based on these requirements, Patent Document 1, previously filed by the applicant, discloses a structure including a blow-by gas passage including a return pipe that returns blow-by gas from the crankcase to the head cover, an introduction portion that communicates from the head cover to the mating surface between the intake manifold and the cylinder head, a first gas passage formed in the mating surface, which communicates with the downstream end of the introduction portion and extends between the multiple intake branch pipes of the intake manifold, and multiple second gas passages that branch off from the first gas passage and communicate with each intake branch pipe. This structure makes it possible to return blow-by gas to each intake port of the cylinder head via the branched return passages (i.e., multiple second gas passages) formed in the mating surface between the intake manifold and the cylinder head. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Utility Model Registration No. 2592095 Summary of the Invention [Problem to be solved by the invention]

[0007] In the above structure, the return passage is branched at the mating surface between the intake manifold and the cylinder head to suppress the condensation of water vapor in the blow-by gas. However, it is unavoidable that heat escapes to the intake manifold as the blow-by gas passes through the branched return passage formed at the mating surface, and there is still room for improvement in suppressing the condensation of water vapor.

[0008] The present invention has been made in consideration of the above circumstances, and has an object to provide a blow-by gas recirculation device that can suppress condensation of water vapor in blow-by gas in a branched recirculation passage. [Means for solving the problem]

[0009] In order to solve the above problems, the blow-by gas recirculation device of the present invention is a blow-by gas recirculation device that recirculates blow-by gas generated in an engine having a plurality of cylinders to an intake system of the engine, and is provided with a distribution section that is provided in a head cover of the engine and distributes the blow-by gas to the intake paths of each cylinder, and the distribution section is provided with an introduction section into which the blow-by gas is introduced, and a plurality of branch passages that communicate with the introduction section and are branched from the introduction section and communicate with each intake path. The plurality of branch paths have a tournament structure in which they branch off from the introduction section in a plurality of stages, and the distribution section has one narrow section for each branch section at which two of the branch paths branch off in the tournament structure, which narrows the flow path of one of the two branch paths. It is characterized by:

[0010] According to this configuration, a head cover of an engine having multiple cylinders is provided with an inlet through which blow-by gas is introduced and a distributor that is connected to the inlet and has multiple branch passages branching off from the inlet. Therefore, even in cold climates, the head cover warms up quickly when the engine is started, and the blow-by gas that passes through the inlet and the multiple branch passages of the distributor in the head cover is also quickly warmed and distributed to the intake paths of each cylinder for recirculation. This makes it possible to prevent condensation of water vapor contained in the blow-by gas in the branched recirculation passages. In the above-described blow-by gas recirculation device, the plurality of branch passages have a tournament structure in which they branch off from the introduction portion in a plurality of stages. This configuration allows for multiple branch passages to branch from a single inlet in the limited space inside the head cover. This structure also allows for multiple branch passages to be provided without changing the width of the branch passages, making it possible to distribute blow-by gas efficiently. Furthermore, in the above-mentioned blow-by gas recirculation device, the distribution section has one narrow section at each branching section where the two branching sections branch off in the tournament structure, which narrows the flow path of one of the two branching sections. In this configuration, at the branching point where the two branch passages of the tournament structure in the distributor branch off, one of the two branch passages can be narrowed by a single narrowing section, thereby reducing the flow rate of blow-by gas. This makes it possible to individually adjust the flow rate of blow-by gas in each of the branch passages that branch off at multiple stages in the tournament structure. As a result, it becomes possible to evenly deliver blow-by gas to the intake paths of multiple cylinders while maintaining high uniformity, thereby suppressing variations in the air-fuel ratio between the cylinders.

[0011] The above-described blow-by gas recirculation device preferably further comprises a communication passage inside the cylinder head of the engine, the communication passage connecting an intake port constituting the intake path of the cylinder with an outlet of the branch passage.

[0012] With this configuration, the blow-by gas distributed by the distribution section inside the head cover can be introduced directly into the intake port through a connecting passage inside the cylinder head, where the temperature rises rapidly, making it possible to supply the blow-by gas to the cylinder while reliably preventing condensation and freezing of water vapor in the blow-by gas.

[0015] In the above blow-by gas recirculation device, it is preferable that the plurality of branch passages of the tournament structure are arranged with a center at a middle position in the direction in which the plurality of cylinders are arranged.

[0016] This simple configuration allows blow-by gas to be evenly distributed to the intake paths of multiple cylinders. Also, this tournament structure makes it easier to design the distribution section.

[0019] In the above-described blow-by gas recirculation device, the narrow portion is preferably formed by a partition wall that partially separates the inside of the branch passage.

[0020] In this configuration, by providing a partition wall that partially separates the inside of the branch passage as the narrow portion, it becomes possible to more accurately set the flow rate of blow-by gas flowing through each branch passage.

[0021] The above-described blow-by gas recirculation device preferably further comprises a lubricating oil passage arranged adjacent to the distributor and through which lubricating oil supplied to a valve train of the engine flows.

[0022] With this configuration, immediately after the engine starts, the lubricating oil supplied to the engine's valve train flows through the lubricating oil passage adjacent to the distribution section, and the heat of the lubricating oil warms the distribution section, allowing the ice in the branch passage to be immediately thawed. Furthermore, even after the engine is subsequently stopped temporarily (i.e., after soaking), the blow-by gas remaining inside the distribution section is warmed by the heat of the lubricating oil, making it possible to suppress condensation of water vapor contained in the blow-by gas.

[0023] The above-described blow-by gas recirculation device preferably further includes a separation section provided within the head cover, communicating with the introduction section, and separating oil contained in the blow-by gas.

[0024] With this configuration, after the separation section separates oil from the blow-by gas and purifies the blow-by gas, the distribution section can distribute the purified blow-by gas into multiple branch paths after it passes through the introduction section, making it possible to prevent oil from adhering to the branch paths.In addition, since the separation section is provided inside the head cover, it is possible for the separation section to separate oil in the blow-by gas that has been warmed inside the head cover, even in cold regions, improving separation efficiency.

[0025] In the above-mentioned blow-by gas recirculation device, it is preferable that the separation section extends within the head cover in the arrangement direction of the plurality of cylinders and is arranged on the exhaust path side of the plurality of cylinders, the distribution section extends within the head cover in the arrangement direction and is arranged on the intake path side of the plurality of cylinders, the outlet of the separation section and the inlet of the distribution section are arranged at the end on the same side in the arrangement direction within the head cover, and the device further includes a recirculation pipe extending in a direction perpendicular to the arrangement direction and connecting the outlet of the separation section and the inlet of the distribution section.

[0026] With this configuration, the return pipe extends in a direction perpendicular to the arrangement direction of the multiple cylinders and connects the outlet of the separation section to the inlet of the distribution section, making it possible to shorten the length of the return pipe, suppressing the temperature drop of the blow-by gas as it moves from the separation section to the distribution section, and further suppressing condensation of water vapor contained in the blow-by gas.

[0027] In the above-described blow-by gas recirculation device, it is preferable that the recirculation pipe is provided with a regulating section that allows the blow-by gas to flow from the separation section to the distribution section and regulates the flow from the distribution section to the separation section.

[0028] With this configuration, when the engine is operating in the supercharging region, the pressure in the distribution section is higher than that in the separation section, but the regulating section of the return pipe can regulate the backflow of blow-by gas from the distribution section to the separation section.

[0029] The head cover of the present invention is characterized by including the above-mentioned distributor.

[0030] According to this head cover configuration, the above-mentioned distribution section, i.e., a distribution section provided in the head cover of an engine having multiple cylinders, includes an inlet section through which blow-by gas is introduced and multiple branch passages that communicate with the inlet section and branch off from the inlet section. Therefore, even in cold regions, the head cover warms up quickly when the engine is started, and the blow-by gas passing through the inlet section and the multiple branch passages of the distribution section in the head cover is also quickly warmed, allowing it to be distributed and returned to the intake paths of each cylinder. This makes it possible to prevent condensation of water vapor contained in the blow-by gas in the branched return passages. [Effects of the Invention]

[0031] As described above, the blow-by gas recirculation device and head cover of the present invention can suppress condensation of water vapor in the blow-by gas in the branched recirculation passages. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a perspective view showing the overall configuration of an engine having a structure in which a blow-by gas recirculation device according to an embodiment of the present invention is provided in a head cover; [Figure 2] FIG. 2 is a plan view of the head cover and its surroundings in FIG. [Figure 3] 2 is a perspective explanatory view showing the positional relationship between an oil separation section and a distribution section in the head cover of FIG. 1 and peripheral components. FIG. [Figure 4] 2 is an explanatory plan view showing the positional relationship between the oil separation section and the distribution section in the head cover of FIG. 1 and the peripheral components thereof. FIG. [Figure 5] FIG. 5 is a cross-sectional view taken along line VV in FIG. [Figure 6] 4 is a perspective explanatory view showing a plurality of communication passages respectively connecting a plurality of intake ports of the cylinder head of FIG. 3 with a plurality of outlet ports of a distributor in a head cover. FIG. [Figure 7] 2 is a diagram showing a specific configuration of an oil separation section and a distribution section inside the head cover when viewed from the bottom side of the head cover in FIG. 1. FIG. [Figure 8] 4 is an explanatory cross-sectional view showing a lubricating oil passage adjacent to the cylinder head side (lower side) of the oil separation section and distribution section of FIG. 3. FIG. [Figure 9] 4 is a bottom view of the lubricating oil passages adjacent to the oil separation section and distribution section of FIG. 3. FIG. [Figure 10] FIG. 2 is a block diagram showing the structure of the engine and its intake system in FIG. 1, and is an explanatory diagram showing the gas flows in the return pipe (PCV hose), ventilation hose, and breather hose when the engine is operating in the naturally aspirated region. [Figure 11] FIG. 2 is a block diagram showing the structure of the engine and its intake system in FIG. 1, and is an explanatory diagram showing the gas flow in the return pipe, ventilation hose, and breather hose when the engine is operating in the supercharging region. DETAILED DESCRIPTION OF THE INVENTION

[0033] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A blow-by gas recirculation device according to an embodiment of the present invention will be described in detail below with reference to the drawings.

[0034] As shown in Figures 1 and 10, a system related to an engine 1 having multiple cylinders (Figure 1 shows an in-line six-cylinder engine) and its intake system includes the engine 1 having a cylinder head 2, a head cover 3 that covers the upper part of the cylinder head 2, and a cylinder block 4 connected to the lower part of the cylinder head 2, an intake manifold 5 having multiple intake passages that are respectively connected to the multiple intake ports 2a (see Figure 3) of the cylinder head 2, an introduction pipe 6 connected to an air cleaner box (not shown) of the engine 1, an intake pipe 7 whose downstream end is connected to the intake manifold 5, and a turbocharger 8 connected to the upstream end of the intake pipe 7 and that supercharges the intake air in the introduction pipe 6.

[0035] Furthermore, as shown in FIG. 1, this system includes a ventilation hose 9 connecting the head cover 3 (specifically, an oil separation section 12 inside the head cover 3, which will be described later) and the intake path upstream of the turbocharger 8, a breather hose 10 connecting the cylinder block 4 and the intake path upstream of the turbocharger 8, an air cleaner 21 connected to the intake path upstream of the turbocharger 8, and a throttle valve 22 arranged between the turbocharger 8 and the intake manifold 5.

[0036] The engine 1 is provided with a blow-by gas recirculation device 20 (see FIGS. 3 to 5) for recirculating blow-by gas generated in the engine 1 to each intake port 2a that is an intake system of the engine 1.

[0037] 3 to 5, the blow-by gas recirculation device 20 specifically includes an oil separation section 12 that separates oil contained in the blow-by gas, a distribution section 13 that distributes the blow-by gas to each cylinder, a plurality of communication passages 14 (see FIG. 6) that connect the distribution section 13 to each intake port 2a, a recirculation pipe 11 that connects the oil separation section 12 to the distribution section 13, and lubricating oil passages 15 and 16 that are arranged adjacent to the oil separation section 12 and the distribution section 13, respectively. The oil separation section 12, the distribution section 13, and the lubricating oil passages 15 and 16 are housed within the cylinder head cover 3. The communication passage 14 is formed to vertically penetrate the cylinder head 2.

[0038] The return pipe 11 of this embodiment is attached to the upper surface of the head cover 3 and is arranged to pass outside the head cover 3.

[0039] In the above-described blow-by gas recirculation device 20, blow-by gas generated in the crankcase (not shown) of the engine 1 is recirculated into the head cover 3 through an oil separator inlet (not shown). Inside the head cover 3, the blow-by gas is sent to an oil separation section 12 where the oil in the blow-by gas is separated, and then sent to a distribution section 13 through a recirculation pipe 11. After being distributed in the distribution section 13, the blow-by gas is recirculated to each intake port 2a through a communication passage 14. Such a blow-by gas recirculation device 20 is called a PCV system (Positive Crankcase Ventilation System), and enables separation of the oil in the blow-by gas as well as uniform distribution of the blow-by gas to each intake port 2a.

[0040] The specific configuration of each component of the blow-by gas recirculation device 20 will be described in more detail below.

[0041] As shown in FIGS. 2 to 5 and 7 to 9, the distributor 13 is provided inside the head cover 3 and has a configuration for distributing blow-by gas to the intake paths of the cylinders.

[0042] As shown in Figure 7, the distribution section 13 includes an inlet section 13a having an inlet through which blow-by gas is introduced, multiple branch passages 13c having a tournament structure branching off in multiple stages from the inlet section 13a, a discharge section 13b communicating with the downstream ends of each of the multiple branch passages 13c in the final stage (i.e., the outlets of the multiple branch passages 13c), and a partition wall 13e serving as a narrowing section that partially narrows some of the multiple branch passages 13c.

[0043] The multiple branch passages 13c are configured to communicate with the introduction section 13a and branch off from the introduction section 13a to communicate with each intake path, and among such configurations, this embodiment particularly has a tournament structure in which branches off at multiple stages from the introduction section 13a as described above.

[0044] Here, a tournament structure is a structure in which one inlet 13a branches into multiple outlets 13b, and the number of branching paths 13c and branching sections 13d increases gradually as one moves from the inlet 13a to the outlet 13b without having a closed loop, and is a structure that can be represented by a tree diagram or a dendrogram.

[0045] In this embodiment, as shown in FIG. 7, the plurality of branch passages 13c in the tournament structure are arranged with the center at the middle position in the arrangement direction X of the plurality of cylinders.

[0046] 7, the partition wall 13e acts as a narrow portion that narrows the flow path of one of the two branch paths 13c at a branch portion 13d where the two branch paths 13c branch off in the tournament structure, thereby partially dividing the inside of the branch path 13c. Specifically, the partition wall 13e protrudes in the cross-sectional direction into the inside of the branch path 13c.

[0047] For example, the partition wall 13e is provided on one of the two branch passages 13c where it is desired to reduce the flow rate of blow-by gas. Specifically, if one branch passage 13c is a straight branch passage and the other is a branch passage 13c that bends at a branch portion 13d, the partition wall 13e is provided on the straight branch passage 13c.

[0048] In addition, in the portion of the two branch passages 13c where it is required to send a large amount of blow-by gas in the direction with the larger number of final stage discharge sections 13b, by providing a labyrinth-structured partition 13e combining multiple small partitions 13e1, 13e2 in the opposite branch passage 13c, it is possible to significantly reduce the flow rate of blow-by gas in the opposite branch passage 13c and send a large amount of blow-by gas to the desired branch passage 13c.

[0049] 5, 8 and 9, the distribution section 13 is produced by overlapping a top plate 131 constituting the outer wall of the head cover 3 with a middle plate 132 inside the head cover 3, and forming a tournament chamber 133, which is a space including a plurality of branch passages 13c having the tournament structure described above, between the top plate 131 and the middle plate 132. The head cover 3 of this embodiment is provided with the distribution section 13 described above. In other words, it can be said that the head cover 3 equipped with the distribution section 13 constitutes a part of the blow-by gas recirculation device 20.

[0050] 5 and 6, a plurality of communication passages 14 are formed to vertically penetrate the cylinder head 2. Each communication passage 14 connects the intake port 2a constituting the intake path of each cylinder inside the cylinder head 2 of the engine 1 with each discharge section 13b (see FIGS. 5 and 7) at the outlet of each of the branch passages 13c of the distributor 13.

[0051] 2 to 5 and 7 to 9, the oil separation unit 12 is provided in the head cover 3, communicates with the inlet 13a of the distribution unit 13 through the return pipe 11, and is disposed upstream of the distribution unit 13 in the flow direction of the blow-by gas. The oil separation unit 12 has a configuration for separating oil contained in the blow-by gas, and, for example, as shown in FIG. 7, includes an inlet 12a into which the blow-by gas is introduced, an outlet 12b from which the blow-by gas is discharged, and an oil collecting unit, such as a space that suddenly expands the flow path and a filter that adsorbs oil, provided between the inlet 12a and the outlet 12b.

[0052] As shown in Figures 5, 8 and 9, the oil separation section 12 is produced by stacking a top plate 121 and a middle plate 122 that form the outer wall of the head cover 3, and forming a separator chamber 123 between the top plate 121 and the middle plate 122, which has a space for separating the oil, a filter, etc.

[0053] In this embodiment, the oil separation section 12 extends in the arrangement direction X of the multiple cylinders within the head cover 3 and is arranged on the exhaust path side of the multiple cylinders (the upper side in Figures 2 to 4, i.e., the side opposite to the side where the intake port 2a in Figures 3 and 5 is provided).

[0054] The distributor 13 extends in the arrangement direction X inside the head cover 3 and is disposed on the side of the intake paths (the lower side in FIGS. 2 to 4, ie, the side where the intake ports 2a in FIGS. 3 and 5 are provided).

[0055] As shown in FIG. 7, the outlet 12b of the oil separation section 12 and the inlet section 13a of the distribution section 13 are arranged at the end on the same side in the arrangement direction X within the head cover 3 (the right end in FIG. 7).

[0056] 2 to 4, the return pipe 11 extends in a direction Y perpendicular to the arrangement direction X, and connects the outlet 12b of the oil separation section 12 shown in Fig. 7 with the inlet section 13a of the distribution section 13. The return pipe 11 is a hose that constitutes the blow-by gas return device of the PCV system and is called a PCV hose.

[0057] 11, the return pipe 11 is provided with a one-way valve 11b (a so-called PCV valve) as a regulating part that regulates the flow of blow-by gas in one direction. The one-way valve 11b is configured to function as a regulating part that allows the flow of blow-by gas from the oil separation part 12 to the distribution part 13 and regulates the flow from the distribution part 13 to the oil separation part 12.

[0058] When the pressure inside the head cover 3 increases, the one-way valve 11 b closes, and the flow of blow-by gas through the return pipe 11 can be restricted.

[0059] The lubricating oil passages 15, 16 are disposed adjacent to the oil separation section 12 and the distribution section 13, respectively, and are configured to allow the flow of lubricating oil supplied to the engine's valve train (i.e., the opening and closing mechanisms of the intake valves and exhaust valves). In this embodiment, as shown in Figs. 5, 8 and 9, the lubricating oil passage 15 is formed in the shape of a flow path with a rectangular cross section by overlapping the middle plate 122 and bottom plate 151 that constitute the oil separation section 12. As a result, the lubricating oil passage 15 is disposed adjacent to the lower side of the oil separation section 12, with the middle plate 122 sandwiched between them.

[0060] The lubricating oil passage 16 is formed in the shape of a flow path with a rectangular cross section by overlapping the middle plate 132 and the bottom plate 161 that constitute the distribution section 13. As a result, the lubricating oil passage 16 is disposed adjacent to the lower side of the distribution section 13 with the middle plate 132 sandwiched therebetween.

[0061] In the engine 1 and intake system equipped with the blow-by gas recirculation device 20 configured as described above, as shown in FIG. 10, when the engine 1 operates within the naturally aspirated range, the turbocharger 8 is not activated and the intake port 2a of the engine 1 takes in air naturally. As a result, the intake port 2a is under negative pressure, and air flows through the air cleaner 21, turbocharger 8, throttle valve 22, intake manifold 5, and intake port 2a. At this time, the distribution section 13 in the head cover 3 is under negative pressure together with the intake port 2a through the connecting passage 14, so the one-way valve 11b, which is the restriction section of the recirculation pipe 11, allows the blow-by gas to flow from the oil separation section 12 to the distribution section 13. Therefore, the blow-by gas in the head cover 3 can be recirculated to the intake port 2a through the oil separation section 12, the recirculation pipe 11, the distribution section 13, and the connecting passage 14.

[0062] 10, when the engine is operating in the naturally aspirated range, negative pressure is created inside the cylinder block 4 and the one-way valve 24 provided in the breather hose 10 allows air to flow, making it possible to send fresh air from the air cleaner 21, which is open to the outside air and at atmospheric pressure, to the cylinder block 4 of the engine 1 via the breather hose 10. On the other hand, the one-way valve 23 provided in the ventilation hose 9 restricts the flow of gas because the intake path upstream of the turbocharger 8 is not in the specified negative pressure state. This makes it possible to restrict the return of blow-by gas from the oil separation section 12 of the head cover 3 to the upstream side of the turbocharger 8 via the ventilation hose 9.

[0063] On the other hand, when the engine 1 is operating within the supercharging range, the turbocharger 8 supercharges the intake port 2a, creating a positive pressure in the intake port 2a. At this time, the distribution section 13 in the head cover 3 becomes positive pressure together with the intake port 2a through the communication passage 14, so the one-way valve 11b in the return pipe 11 can restrict the backflow of blow-by gas from the distribution section 13 to the oil separation section 12.

[0064] 11, the one-way valve 24 provided in the breather hose 10 restricts the flow of gas, making it possible to restrict the flow of blow-by gas before oil separation from the cylinder block 4 of the engine 1 to the turbocharger via the breather hose 10. On the other hand, the one-way valve 23 provided in the ventilation hose 9 allows the flow of gas because the intake path upstream of the turbocharger 8 is at a predetermined negative pressure or higher, making it possible to return the blow-by gas from the oil separation section 12 of the head cover 3 to the turbocharger 8 via the ventilation hose 9.

[0065] (Features of this embodiment) (1) 7, in the blow-by gas recirculation device 20 of this embodiment, a head cover 3 of an engine having multiple cylinders is provided with a distribution section 13 including an inlet 13a into which blow-by gas is introduced and multiple branch passages 13c that communicate with the inlet 13a and branch off from the inlet 13a. Therefore, even in cold climates, the head cover 3 warms up quickly when the engine is started, and the blow-by gas passing through the inlet 13a and multiple branch passages 13c of the distribution section 13 in the head cover 3 is also quickly warmed and can be distributed and recirculated to the intake paths of each cylinder. This makes it possible to prevent water vapor contained in the blow-by gas from condensing in the branched recirculation passages.

[0066] (2) 5, the blow-by gas recirculation device 20 of this embodiment further includes a communication passage 14 that connects the intake port 2a, which constitutes the intake path of the cylinder, with the discharge portion 13b at the outlet of the branch passage 13c inside the cylinder head 2 of the engine. With this configuration, the blow-by gas distributed by the distributor 13 inside the head cover 3 can be directly introduced into the intake port 2a through the communication passage 14 inside the cylinder head 2, where the temperature rise is high, so that the blow-by gas can be supplied to the cylinder while reliably preventing condensation and freezing of water vapor in the blow-by gas.

[0067] (3) In the blow-by gas recirculation device 20 of this embodiment, as shown in FIG. 7, the multiple branch passages 13c have a tournament structure in which they branch off from the inlet portion 13a in multiple stages. This configuration makes it possible to branch off from one inlet portion 13a into multiple branch passages 13c in the limited space inside the head cover 3. This structure also makes it possible to provide multiple branch passages 13c without changing the width of the branch passages 13c, thereby enabling efficient distribution of blow-by gas. Furthermore, since the multiple branch passages 13c have a tournament structure, the degree of freedom in layout of the blow-by gas passage is improved.

[0068] (4) In the blow-by gas recirculation device 20 of this embodiment, as shown in Fig. 7, the multiple branch passages 13c in the tournament structure are arranged around the center of the middle position in the arrangement direction X of the multiple cylinders. This configuration makes it possible to send blow-by gas evenly to the intake paths of the multiple cylinders with a simple structure. In addition, using such a tournament structure makes it easier to design the distribution section 13.

[0069] (5) In the blow-by gas recirculation device 20 of this embodiment, as shown in FIG. 7 , the distributor 13 includes a partition wall 13e at a branching portion 13d where two branch passages 13c branch off in a tournament structure, as a narrowing portion that narrows one of the two branch passages 13c. This configuration narrows one of the two branch passages 13c at the branching portion 13d where the two branch passages 13c branch off in a tournament structure in the distributor 13, thereby reducing the flow rate of blow-by gas. This makes it possible to individually adjust the flow rate of blow-by gas in each of the branch passages 13c that branch off at multiple stages in the tournament structure. As a result, blow-by gas can be evenly delivered to the intake paths of multiple cylinders while maintaining high uniformity, thereby suppressing variations in the air-fuel ratio between the cylinders.

[0070] (6) In the blow-by gas recirculation device 20 of this embodiment, the narrow portion is formed by a partition wall 13e that partially separates the inside of the branch passage 13c. In this configuration, by providing the partition wall 13e that partially separates the inside of the branch passage 13c as the narrow portion, it becomes possible to more accurately set the flow rate of the blow-by gas that flows through each branch passage 13c.

[0071] In addition, the narrow portion may have any other configuration other than the above-mentioned partition wall 3e as long as it narrows the flow path area of ​​the branch path 13c, and the narrow portion may be configured by narrowing the width of the branch path 13c or inserting a perforated plate into the branch path 13c.

[0072] (7) As shown in Fig. 5, 8 and 9, the blow-by gas recirculation device 20 of this embodiment is disposed adjacent to the distribution unit 13 and includes a lubricating oil passage 15 through which lubricating oil supplied to the valve train of the engine flows. With this configuration, immediately after the engine is started, the lubricating oil supplied to the valve train of the engine flows through the lubricating oil passage 15 adjacent to the distribution unit 13, and the heat of the lubricating oil warms the distribution unit 13, thereby immediately thawing any ice formed in the branch passage 13c. Therefore, even after the engine is subsequently temporarily stopped (i.e., after a soak), the blow-by gas remaining inside the distribution unit 13 is warmed by the heat of the lubricating oil, making it possible to suppress condensation of water vapor contained in the blow-by gas.

[0073] Furthermore, in this embodiment, the lubricating oil passage 16 is arranged adjacent to the oil separation section 12, which makes it possible to further warm the blow-by gas with the heat of the lubricating oil, thereby improving the separation efficiency of the oil contained in the blow-by gas and further suppressing the condensation of water vapor contained in the blow-by gas.

[0074] (8) 2 to 5 and 7 to 9, the blow-by gas recirculation device 20 of this embodiment is provided in the head cover 3, communicates with the inlet 13a of the distributor 13, and includes an oil separator 12 that separates oil contained in the blow-by gas. With this configuration, after the oil separator 12 separates oil from the blow-by gas to purify the blow-by gas, the distributor 13 distributes the purified blow-by gas through multiple branch paths 13c after passing through the inlet 13a, thereby preventing oil from adhering to the branch paths 13c. Furthermore, because the oil separator 12 is provided in the head cover 3, the oil separator 12 can separate oil from the blow-by gas warmed inside the head cover 3 even in cold climates, improving separation efficiency.

[0075] (9) 2 to 5, in the blow-by gas recirculation device 20 of this embodiment, the oil separation unit 12 extends in the arrangement direction X of the multiple cylinders within the head cover 3 and is arranged on the exhaust path side of the multiple cylinders. The distribution unit 13 extends in the arrangement direction X within the head cover 3 and is arranged on the intake path side. The outlet 12b of the oil separation unit 12 and the introduction portion 13a of the distribution unit 13 are arranged at the end on the same side in the arrangement direction X within the head cover 3. The recirculation pipe 11 extends in a direction Y perpendicular to the arrangement direction X and connects the outlet 12b of the oil separation unit 12 and the introduction portion 13a of the distribution unit 13.

[0076] According to this configuration, the return pipe 11 extends in a direction Y perpendicular to the arrangement direction X of the multiple cylinders and connects the outlet 12b of the oil separation section 12 and the inlet section 13a of the distribution section 13, so that the length of the return pipe 11 can be shortened, and it is possible to suppress a decrease in the temperature of the blow-by gas while it is moving from the oil separation section 12 to the distribution section 13, and it is possible to further suppress condensation of water vapor contained in the blow-by gas.

[0077] In this embodiment, the return pipe 11 is provided outside the head cover 3, but it may be provided inside the head cover 3.

[0078] (10) 10, in the blow-by gas recirculation device 20 of this embodiment, the recirculation pipe 11 is provided with a one-way valve 11b (PCV valve) as a regulating unit that allows the flow of blow-by gas from the oil separation unit 12 to the distribution unit 13 and regulates the flow from the distribution unit 13 to the oil separation unit 12. With this configuration, when the engine is operating in the supercharging range, the pressure in the distribution unit 13 is higher than that in the oil separation unit 12, but the one-way valve 11b, which is the regulating unit of the recirculation pipe 11, can regulate the backflow of blow-by gas from the distribution unit 13 to the oil separation unit 12.

[0079] (11) According to the configuration of the head cover 3 of this embodiment, the above-mentioned distribution unit 13, that is, the distribution unit 13 is provided in the head cover 3 of an engine having multiple cylinders and includes an inlet 13a into which blow-by gas is introduced and multiple branch passages 13c that communicate with the inlet 13a and branch off from the inlet 13a. Therefore, even in cold regions, the head cover 3 warms up quickly when the engine starts, and the blow-by gas that passes through the inlet 13a and multiple branch passages 13c of the distribution unit 13 in the head cover 3 is also quickly warmed and can be distributed and returned to the intake paths of each cylinder. This makes it possible to prevent condensation of water vapor contained in the blow-by gas in the branched return passages. [Explanation of symbols]

[0080] 1 engine 2. Cylinder head 2a intake port 3 Headcover 4 Cylinder block 5. Intake manifold 6 Intake exhaust pipe 7 Intake pipe 8 Turbocharger 9 Ventilation hose 10 Breather Hose 11 Reflux tube 12 Separation part 12a Introduction 12b Outlet 13 Distribution section 13a Introduction 13b Discharge section 13c Fork in the road 13d Branching part 13e Bulkhead (narrow part) 14 Communication path 15, 16 Lubricating oil path 20 Blow-by gas recirculation device

Claims

1. A blow-by gas recirculation device for recirculating blow-by gas generated in an engine having multiple cylinders to an intake system of the engine, a distributor provided in a head cover of the engine for distributing the blow-by gas to the intake paths of the cylinders; the distributor includes an introduction section into which the blow-by gas is introduced, and a plurality of branch passages that communicate with the introduction section and branch off from the introduction section to communicate with each intake path, the plurality of branching paths have a tournament structure branching at a plurality of stages from the introduction section, The distributor includes a narrow portion for each branching portion where the two branching paths branch off in the tournament structure, the narrow portion narrowing a flow path of one of the two branching paths. A blow-by gas recirculation device characterized by:

2. 2. The blow-by gas recirculation device according to claim 1, The engine further includes a communication passage that communicates an intake port that constitutes the intake path of the cylinder with an outlet of the branch passage inside the cylinder head of the engine. A blow-by gas recirculation device characterized by:

3. 2. The blow-by gas recirculation device according to claim 1, The plurality of branch paths of the tournament structure are arranged around a middle position in an arrangement direction of the plurality of cylinders. A blow-by gas recirculation device characterized by:

4. 2. The blow-by gas recirculation device according to claim 1, The narrow portion is formed by a partition wall that partially separates the inside of the branch path. A blow-by gas recirculation device characterized by:

5. The blow-by gas recirculation device according to any one of claims 1 to 4, The engine further includes a lubricating oil passage disposed adjacent to the distribution section, through which lubricating oil flows to be supplied to a valve train of the engine. A blow-by gas recirculation device characterized by:

6. The blow-by gas recirculation device according to any one of claims 1 to 4, a separation section provided in the head cover, communicating with the introduction section, and separating oil contained in the blow-by gas; A blow-by gas recirculation device characterized by:

7. 7. The blow-by gas recirculation device according to claim 6, the separation portion extends in the cylinder head cover in the direction of arrangement of the cylinders and is disposed on the exhaust path side of the cylinders, the distributor extends in the arrangement direction within the head cover and is disposed on a side of the plurality of intake paths, the outlet of the separation section and the inlet of the distribution section are disposed at an end portion on the same side in the arrangement direction within the head cover, The separator further includes a reflux pipe extending in a direction perpendicular to the arrangement direction and communicating an outlet of the separator with the introduction portion of the distributor. A blow-by gas recirculation device characterized by:

8. The blow-by gas recirculation device according to claim 7, the return pipe includes a restriction portion that allows the blow-by gas to flow from the separation portion to the distribution portion and restricts the flow from the distribution portion to the separation portion. A blow-by gas recirculation device characterized by:

9. A head cover comprising the distributor according to claim 1.

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