JP2010285996A - Structure for inhibiting sludge adhesion in internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit generation, adhesion and accumulation of sludge at parts where oil is not always spread. <P>SOLUTION: In a structure for inhibiting sludge adhesion in an internal combustion engine, a sludge inhibitory layer 35B for inhibiting generation or adhesion of sludge is formed on the surfaces of the parts inside the internal combustion engine, where oil is not always spread and with which oil mist contacts. The sludge inhibitory layer 35B is preferably formed of solid alkaline substance and is formed on inner surfaces 36B, 37B of an oil separator chamber 25B which is provided on a head cover 6 and separates oil from blow-by gas. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a sludge adhesion suppressing structure for an internal combustion engine, and more particularly to a structure for suppressing sludge adhesion at a specific part of an internal combustion engine.

  In internal combustion engines for automobiles and the like, it is known that sludge is generated due to deterioration of oil as lubricating oil, and this has various adverse effects on various parts of the engine. Sludge is mainly composed of olefins contained in oil, NOx and SOx contained in blow-by gas, and water. These main components react by the power of heat and acid, and precursors such as sludge precursor and sludge binder are added. It is generated after. The sludge is visually a mud or sludge-like substance, and for example, when it accumulates in a passage inside the internal combustion engine, it causes a problem that the passage is blocked.

  In particular, an acidic substance produced by a reaction between water generated by dew condensation or the like inside the internal combustion engine and NOx or SOx contained in blow-by gas serves as a catalyst for generating sludge. The mixing of such acidic substances into the oil accelerates the generation of sludge, accelerates the deterioration of the oil, and lowers the functions of the lubricating oil.

  Conventionally, an additive called a metal-based detergent is added to the lubricating oil to neutralize the acidic substance generated in the oil, thereby suppressing the generation of sludge. Means are taken. In addition, a weak cationic surfactant is added to the oil to enhance the function of dispersing the sludge in the oil (see, for example, Patent Document 1).

JP-A-9-13066

  By the way, the said prior art suppresses generation | occurrence | production of sludge by neutralizing and removing the acidic substance contained in oil. In other words, the above-mentioned prior art mainly aims to reduce the amount of sludge that is dispersed and diffused in the oil and to suppress the deterioration of the oil itself.

  On the other hand, there is a problem that sludge adheres and accumulates at a site where the oil inside the internal combustion engine does not always spread. In other words, if the oil is constantly distributed, even if sludge is generated, the sludge is washed away with the oil, so that adhesion and accumulation are unlikely to occur. However, if the oil is not constantly distributed, the effect of washing off such sludge cannot be expected, and a problem of adhesion / deposition may occur.

  Accordingly, the present invention has been made in view of the above-described problems, and an object of the present invention is to provide a sludge adhesion suppressing structure for an internal combustion engine that can suppress the generation or adhesion of sludge in a region where oil does not always spread.

In order to achieve the above object, the first invention provides:
A sludge suppression layer for suppressing the generation or adhesion of sludge is formed on the surface of the internal combustion engine where oil as a liquid does not always flow and where oil mist as a gas is contacted A sludge adhesion suppressing structure for an internal combustion engine characterized by the following.

  According to this, it becomes possible to suppress the generation | occurrence | production or adhesion of the sludge on the surface of the site | part to which oil does not always spread and oil mist contacts by a sludge suppression layer.

The second invention is the first invention, wherein
The surface of the part is an inner surface of a part having an outer surface exposed to outside air.

  As described above, an acidic substance is generated by the reaction of water, NOx, and SOx, and this acidic substance serves as a catalyst for promoting the generation of sludge. On the other hand, on the inner surface of the portion having the outer surface exposed to the outside air, dew condensation water that is a raw material of the acidic substance is likely to be generated, and therefore sludge is likely to be generated or adhered. However, according to the second invention, since the sludge suppressing layer is formed on the inner surface of such a portion, it is possible to effectively suppress the generation or adhesion of sludge on the surface where sludge generation or adhesion is likely to occur.

The third invention is the second invention, wherein
The surface of the part is at least one of an inner surface of a head cover that covers a cylinder head, an inner surface of a chain cover that covers a timing chain, and an inner surface of an oil separator chamber that separates oil from blow-by gas.

  Any of the head cover, the chain cover, and the oil separator chamber is easily cooled by being exposed to the outside air, and condensed water is likely to be generated inside. Therefore, by providing a sludge suppression layer on at least one of these inner surfaces, sludge generation or adhesion on a surface where sludge generation or adhesion tends to occur can be effectively suppressed.

Further, a fourth invention is any one of the first to third inventions,
The sludge suppression layer is made of a solid alkaline substance.

  According to this, the acidic substance produced | generated on the surface of the said site | part can be neutralized by chemically reacting with an alkaline substance. Therefore, it is possible to neutralize and remove the acidic substance as a catalyst for promoting sludge generation, thereby suppressing the generation and adhesion of sludge.

The fifth invention is the fourth invention, wherein
The alkaline substance is made of calcium carbonate.

Also, a sixth invention is any one of the first to fifth inventions,
The surface of the sludge suppression layer is formed in an uneven shape.

  According to this, compared with the case where the surface of a sludge suppression layer is made into a flat plane, the surface area of a sludge suppression layer can be increased substantially and the neutralization reaction of an acidic substance can be accelerated | stimulated.

The seventh invention is the sixth invention, wherein
The sludge suppressing layer is composed of at least one of a combination of a large number of particles and a foam-like substance.

  In this case, the contact area or reaction area between the sludge suppression layer and the acidic substance can be expanded to promote the neutralization reaction of the acidic substance, and the acidic substance can be physically absorbed or adsorbed and removed. It becomes.

Further, an eighth invention is any one of the first to fifth inventions,
The sludge suppression layer is formed by coating.

  This makes it possible to form the sludge suppression layer relatively easily.

  According to the present invention, an excellent effect is exhibited in that generation, adhesion, and accumulation of sludge at a portion where oil does not constantly spread can be suppressed.

1 is a schematic cross-sectional view of an internal combustion engine according to an embodiment of the present invention. 1 is a partially assembled perspective view of an internal combustion engine according to an embodiment of the present invention. It is a perspective view when a head cover is seen from the lower back side. It is a perspective view when a baffle plate is seen from the upper part. It is a fragmentary sectional view showing an oil separator room. It is an expanded sectional view which shows the formation method of a sludge suppression layer, and its structure. 1 is a schematic configuration diagram of a dry sump engine to which the present invention is applicable.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows an internal combustion engine to which the present invention is applied, particularly a blow-by gas recirculation device. As shown in the drawing, the engine 1 includes a cylinder block 2, a piston 3, a crankcase 4, a cylinder head 5, a head cover 6 that covers the cylinder head 5 from above, and an oil pan 7. The blow-by gas is a gas that leaks into the crankcase 4 from the gap between the piston ring and the cylinder bore of the cylinder block 2. This blow-by gas contains a large amount of hydrocarbons and moisture. For this reason, if it is too much, it will cause early deterioration of engine oil and rust inside the engine. Further, since hydrocarbons are contained, it is not environmentally preferable to release it to the atmosphere as it is. Therefore, blow-by gas is forcibly returned to the intake system through a route described later using intake negative pressure. The flow of blow-by gas and fresh air when the engine is lightly loaded is indicated by arrows.

  A throttle valve 9 is provided in the intake passage 8, and the intake passage 8 on the downstream side of the throttle valve 9 and the inside of the head cover 6 are communicated with each other by a PCV passage 10. Here, PCV is an abbreviation for Positive Crankcase Ventilation. The intake passage 8 on the upstream side of the throttle valve 9 and the inside of the head cover 6 are communicated with each other by an atmospheric passage 11. A PCV valve 12 that opens and closes the PCV passage 10 is provided. The PCV valve 12 opens and closes according to the magnitude of the intake negative pressure to change the flow rate, and is fixed to the head cover 6 in this embodiment.

  The cylinder block 2 and the cylinder head 5 are provided with an oil dropping passage 13 that allows the inside of the head cover 6 and the inside of the crankcase 4 to communicate with each other. The oil dropping passage 13 of the present embodiment is a passage for dropping the oil remaining on the cylinder head 5 after finishing the lubrication of the valve system toward the oil pan 7, and at the same time, the blow-by gas in the crankcase 4 is removed. This is a passage for ascending and moving toward the inside of the head cover 6. The blow-by gas that moves upward from the crankcase 4 toward the head cover 6 includes oil mist generated by stirring and evaporation of the oil in the crankcase 4.

  As shown in the drawing, when the engine is lightly loaded, the PCV valve 12 is opened, and the blow-by gas in the crankcase 4 is returned to the intake passage 8 through the oil drop passage 13, the head cover 6, and the PCV passage 10 in this order. Thereafter, it is burned in a combustion chamber in the cylinder block 2. On the other hand, at this time, the atmosphere is introduced into the head cover 6 through the atmosphere passage 11, and this atmosphere appropriately dilutes the blow-by gas in the head cover 6.

  On the other hand, although not shown, the PCV valve 12 is closed and the blow-by gas in the head cover 6 is returned to the intake passage 8 through the atmospheric passage 11 when the engine is heavily loaded.

  In this way, the blow-by gas in the crankcase 4 is introduced into the head cover 6 and then returned to the intake passage 8 and burned. The blow-by gas includes HC (hydrocarbon) as a fuel component, NOx and SOx contained in the already burned gas, moisture, and oil mist as a gas generated by stirring and evaporating oil in the crankcase 4. Yes. For this reason, if the blow-by gas is simply circulated to the intake side, the oil is also burned at the same time, which increases the amount of oil consumed and causes white smoke due to oil combustion.

  Therefore, an oil separator chamber for separating oil from blow-by gas is defined in the head cover 6 as will be described in detail later. With this oil separator chamber, the oil can be separated and recovered before the blow-by gas is returned to the intake system, and the above problem can be solved.

  FIG. 2 shows the appearance of the engine 1. As shown in the drawing, at one end portion of the engine 1 in the crankshaft direction, the two camshafts 14I and 14E on the intake side and the exhaust side are rotationally driven by a crankshaft (not shown) via a timing chain 15. . The timing chain 15 is supplied with oil ejected from an oil jet 16 provided in the cylinder block 2. The timing chain 15 is covered from the side by a chain cover 17, and the chain cover 17 is fastened to the cylinder block 2 and the crankcase 4. The head cover 6 is partially fastened to the upper end surface of the chain cover 17, and the oil pan 7 is partially fastened to the lower end surface of the chain cover 17. As a result, a space partitioned from the outside is formed in the chain cover 17.

  The head cover 6 has the same number of plug holes 20 as the number of cylinders (four cylinders in the present embodiment) provided along the longitudinal direction thereof, and an oil supply port 21 that is releasably closed by a cap (not shown). In addition, the PCV valve 12 described above is attached to the head cover 6, and a pipe joint 22 to which a pipe forming the atmospheric passage 11 is connected is attached.

  FIG. 3 shows a perspective view when the head cover 6 is viewed from the back side. As shown in the drawing, two grooves 23A and 23B for partitioning and forming the oil separator chamber described above are provided in the upper part on the back side of the head cover 6. These grooves 23A and 23B are extended in the longitudinal direction L of the head cover 6, and are provided on one side and the other side in the width direction W with the plug hole 20 therebetween. Hereinafter, the side on which one groove 23A in the width direction W is provided is referred to as “front”, and the side on which the other groove 23B is provided is referred to as “rear”. These directions correspond to the longitudinal direction of the vehicle when the engine 1 is placed horizontally on the vehicle as shown in FIG.

  These front and rear grooves 23A and 23B are closed by two substantially rectangular baffle plates 24A and 24B as shown in FIG. Thus, one oil separator chamber 25A defined by the groove 23A and the baffle plate 24A is formed in the front part of the head cover 6, and the rear part of the head cover 6 is defined by the groove 23B and the baffle plate 24B. One oil separator chamber 25B is formed. These front and rear oil separator chambers 25A and 25B are separate and independent.

  After the baffle plates 24A and 24B are inverted vertically and horizontally from the illustrated state, their peripheral portions are joined to the rectangular frame-like joining surfaces 26A and 26B formed on the peripheral portions of the grooves 23A and 23B of the head cover 6, respectively. The head cover 6 is fixed by fastening means such as welding and bolting. Positioning pins 27A and 27B provided on the joint surfaces 26A and 26B and positioning holes 28A and 28B provided on the baffle plates 24A and 24B are used for the alignment of both. The oil separator chambers 25A and 25B thus formed are basically closed spaces except for a gas inlet / outlet portion described later.

  In the head cover 6, a plurality of baffle plates 29A and 29B standing up from the bottoms of the grooves 23A and 23B are integrally provided at a predetermined interval in the longitudinal direction. On the other hand, the upper surfaces of the baffle plates 24A and 24B are also formed therefrom. A plurality of standing baffles 30A and 30B are provided at predetermined intervals in the longitudinal direction. Referring to FIG. 5, these upper and lower baffle plates 29A, 29B and 30A, 30B are alternately arranged in the longitudinal direction L when the baffle plates 24A, 24B are assembled, and blow-by gas flows in the longitudinal direction L. Defines a serpentine passage of time. As a result, when the blowby gas flows in the longitudinal direction of the oil separator chambers 25A and 25B, the blowby gas flows while being bent, thereby promoting the separation of the oil from the blowby gas. There are various known passage structures for the oil separator chamber, such as a meandering structure up and down, a meandering structure left and right, a combination of both, and a more complicated labyrinth structure. . The present invention can be applied to any passage structure.

  As shown in FIG. 3, with respect to the oil separator chamber 25A in the front portion, an air inlet 31A is formed on the right end surface of the groove 23A, and this air inlet 31A is connected to the pipe joint 22 to form an air intake port. Become. Further, as shown in FIG. 4, an atmospheric outlet hole 32A is formed at the left end portion (the right end portion in FIG. 4) of the front baffle plate 24A attached.

  Therefore, when the atmosphere is introduced into the head cover 6, the atmosphere first enters the front oil separator chamber 25A from the atmosphere introduction port 31A, as indicated by the white arrows in FIGS. 3 and 4, and the front oil separator. It flows in the chamber 25A from the right to the left in the figure, and flows out from the outlet hole 32A. In addition, when the engine is under a high load, when the blow-by gas passes through the front oil separator chamber 25A and returns to the intake side, the flow direction is reversed, and the blow-by gas enters the oil separator chamber 25A from the outlet hole 32A. Flowing from left to right in the figure, oil is separated from blow-by gas. The blow-by gas after oil separation flows out from the air inlet 31A to the air passage 11, and the separated oil is dropped from the outlet hole 32A.

  On the other hand, as for the rear oil separator chamber 25B, as shown in FIG. 4, an inlet groove 31B for blow-by gas is formed at the right end portion (left end portion in FIG. 4) when the baffle plate 24B is attached. The inlet groove 31B also serves as a pit for oil accumulated in the oil separator chamber 25B. Further, as shown in FIG. 3, a blow-by gas outlet hole 32 </ b> B is formed at the left end of the groove 23 </ b> B, and the outlet hole 32 </ b> B is connected to the PCV valve 12.

  Therefore, when the blow-by gas is returned to the intake side, as indicated by black arrows in FIGS. 3 and 4, the blow-by gas enters the rear oil separator chamber 25B from the inlet groove 31B and moves from the right to the left in the chamber. At this time, oil is separated from the blow-by gas. The blow-by gas after oil separation flows out from the outlet hole 32B to the PCV passage 10, and the separated oil is dropped from the inlet groove 31B.

  By the way, the oil separator chambers 25A and 25B have oil mist as gas contained in the blow-by gas, and the oil mist is in contact with the inner wall of the oil separator chamber 25A, 25B. It is not a part where oil flows positively. Accordingly, sludge is likely to be generated, adhered and accumulated on the inner surfaces of the oil separator chambers 25A and 25B.

  More specifically, an acidic substance formed by a reaction between NOx or SOx contained in blow-by gas and water generated by condensation or the like serves as a catalyst for generating sludge. On the other hand, the blow-by gas in the oil separator chambers 25A and 25B contains NOx and SOx, and the head cover 6 is difficult to transmit heat from the engine and the outer surface is exposed to the outside air and cooled by cooling air or the like. Therefore, condensed water due to condensation or the like tends to be generated on the inner surface of the head cover 6. Therefore, acidic substances are easily formed in the oil separator chambers 25A and 25B. As a result, sludge is easily generated, and adhesion and accumulation are likely to occur. In addition, since it is not a part where oil flows actively, the effect of washing off the generated sludge cannot be expected.

  When sludge adheres and accumulates on the inner surfaces of the oil separator chambers 25A and 25B, the blow-by gas passage formed in the chambers is partially closed, resulting in a decrease in oil separation performance. As a result, a large amount of oil mist in the blow-by gas is taken into the intake side. This causes problems such as increased oil consumption and generation of white smoke due to oil combustion.

  Therefore, in the present embodiment, a sludge suppression layer is formed on the surface of the part in order to suppress the generation or adhesion of sludge in a part where oil does not basically spread, such as the oil separator chambers 25A and 25B. . The sludge suppression layer is shown in FIG. 3 and FIG.

The sludge suppression layer is preferably made of a solid alkaline substance, and for example, calcium carbonate (CaCO ₃ ) is used as the alkaline substance. For example, in the rear oil separator chamber 25B, the sludge suppression layer 35B is formed on the bottom surface of the groove 23B serving as the inner surface of the head cover 6 and the upper surface of the baffle plate 24B, that is, as shown in FIG. The upper surface (ceiling surface) 36B and the lower surface (floor surface) 37B are formed in the chamber 25B.

  In the present embodiment, the sludge suppression layer 35B is provided on the entire upper surface 36B and lower surface 37B in the oil separator chamber 25B, but may be provided partially. When the sludge suppression layer 35B is provided, the passage area in the room is reduced by the thickness, so in this embodiment, the sludge suppression layer 35B is formed on the baffles 29B and 30B in order to minimize the reduction of the passage area. It has not been. However, forming this is optional. As shown in FIG. 4, the sludge suppression layer 35 </ b> B is not provided on the periphery of the upper surface of the baffle plate 24 </ b> B that is bonded to the bonding surfaces 26 </ b> A and 26 </ b> B of the head cover 6.

  Since the upper surface 36B of the oil separator chamber 25B is the back surface or the inner surface of the outer surface of the head cover that is exposed to the outside air, as shown by the phantom line in FIG. It is easy to drop on 37B. Therefore, the upper surface 36B and the lower surface 37B are likely to form an acidic substance due to the reaction between water M, NOx, and SOx, but in this embodiment, the sludge suppression layer 35A is formed on the upper surface 36B and the lower surface 37B, and thus generated therein. Acidic substances can be neutralized effectively and sludge generation and adhesion can be suppressed.

  On the other hand, the oil separator chamber 25A in the front part has the same configuration, and the sludge suppression layer 35A extends over only the upper surface (ceiling surface) 36A and the lower surface (floor surface) 37A of the oil separator chamber 25A. Formed.

  As described above, when the sludge suppression layers 35A and 35B made of an alkaline substance are provided on the inner surfaces of the oil separator chambers 25A and 25B where the oil is not always distributed and the oil mist is contacted, the generated acidic substance reacts with the alkaline substance. Can be neutralized. Accordingly, it is possible to remove acidic substances that promote the generation of sludge, thereby suppressing the generation of sludge and suppressing the adhesion and accumulation thereof.

  Further, since the generated acidic substance is neutralized and removed, it is possible to simultaneously suppress the acidic substance from being dissolved in the oil and deteriorating the oil.

  In this embodiment, as shown in FIG. 3, a sludge suppression layer 35C is also formed on the inner surface of the head cover other than the front and rear oil separator chambers 25A and 25B. Since the entire head cover 6 is easily cooled, it is preferable to form the sludge suppression layer 35C on the inner surface of the head cover other than the oil separator chambers 25A and 25B as in this embodiment.

  As can be understood from the above description, the present embodiment is provided with a sludge suppression layer that neutralizes acidic substances on the surface of the part where oil does not always spread and the oil mist contacts. Therefore, the prior art as described in Patent Document 1 in which an additive is mixed in the oil to neutralize the acidic substance mixed in the oil is fundamentally different from the present embodiment.

  As a method for forming the sludge suppression layers 35A and 35B, for example, the following method is available. For example, as shown in FIG. 6A, there is a method in which a large number of particles 38 made of an alkaline substance are dispersedly arranged on a target surface 39 and bonded and fixed with an adhesive. Thus, the sludge suppressing layers 35A and 35B are composed of a combination of a large number of particles. In the illustrated example, solid particles 38 are used, but hollow particles may be used. Alternatively, as shown in FIG. 6B, the alkaline substance 42 is dispersed in the solution, applied to the target surface 39 in the form of foam or mousse, and then the solution is dried to target the alkaline substance 42. There is a method of fixing to the surface 39. In this case, the sludge suppression layers 35A and 35B are made of a foam material. Alternatively, as shown in FIG. 6C, an alkaline substance plate 41 (such as a pumice plate) having a large number of pores 40 inside is prepared in advance, and this plate 41 is applied to the target surface 39. There is a way to fix. Also in this case, the sludge suppression layers 35A and 35B are made of a foam-like substance. Alternatively, as shown in FIG. 6D, there is a method in which the alkaline substance 42 is fixed to the target surface 39 by applying a solution in which the alkaline substance is dispersed to the target surface 39 by brush or spray, and then drying the solution. is there. In this case, the sludge suppression layers 35A and 35B are formed of a single layer substantially free of pores, and are relatively easily formed. The surfaces of the sludge suppression layers 35A and 35B are formed in a concavo-convex shape in the case of the structure of FIGS. 6A to 6C, and are formed in a flat plane in the case of the structure of FIG.

  Each of these methods and each structure produced by each method can be used in combination of two or more at different sites. In particular, according to each structure as shown in FIGS. 6 (A) to 6 (C), the surface area of the sludge suppression layer can be substantially enlarged as compared with the structure as shown in FIG. 6 (D). In addition, the contact area or reaction area between the sludge suppression layer and the acidic substance can be increased, and the neutralization reaction of the acidic substance can be promoted. Moreover, according to each structure as shown to FIG. 6 (A)-(C), an acidic substance can be physically absorbed or adsorbed. And if a sludge suppression layer is comprised from the sponge containing an alkaline substance, it will become possible to perform such absorption and adsorption easily. This also removes acidic substances and suppresses sludge generation and adhesion.

  In addition, the formation method and structure of a sludge suppression layer are not restricted to the above-mentioned thing. For example, while adopting a single-layer structure as shown in FIG. 6D, the surface may be formed in an uneven shape to substantially enlarge the surface area.

  The present inventors conducted a comparative test regarding this embodiment. According to this, when the sludge suppression layer was not provided on the upper and lower surfaces of the oil separator chamber, significant sludge-like sludge was attached and accumulated on the upper and lower surfaces of the oil separator chamber. On the other hand, when the sludge suppression layer was provided, almost no sludge was found on the upper and lower surfaces of the oil separator chamber when compared under the same conditions. Thus, the effect of the present invention could be confirmed.

  By the way, the site | part which forms a sludge suppression layer is not restricted to the head cover parts other than the above oil separator chambers or oil separator chambers. In FIG. 2, it is preferable to form the sludge suppression layer in the region surrounded by the one-dot chain line, but this region includes the head cover 6 as described above, the chain cover 17 and particularly the upper portion thereof. As with the head cover 6, the chain cover 17 is also easily cooled because its outer surface is exposed to the outside air. Further, the upper part of the chain cover 17 is not easily subjected to the heat of the engine, and the low temperature of the head cover 6 is transmitted, so that it is particularly easily cooled. Therefore, water due to condensation is likely to be generated on the chain cover 17, particularly on the inner surface of the upper portion thereof. Further, blow-by gas contained in the oil is evaporated in the space inside the chain cover 17, and oil mist is present, so that the oil as a liquid does not flow. Only a necessary and sufficient amount of oil for lubricating the chain 15 is supplied from the oil jet 16, and therefore there is no oil flow in the chain cover 17. For these reasons, it is preferable to form a sludge suppressing layer on the chain cover 17, particularly on the inner surface of the upper portion thereof.

  In addition, the following sites are also suitable for forming the sludge suppression layer. FIG. 7 schematically shows a dry sump engine 100. This dry sump engine 100 does not have an oil pan as an oil reservoir on the engine main body 101 side, and sucks oil from the bottom of the engine main body 101 with a scavenging pump 102 and collects it in an oil tank 103 installed separately. It is supposed to be. The oil stored in the oil tank 103 is circulated and supplied to each lubricating part of the engine 100 by the feed pump 109.

  By the way, since blow-by gas is mixed in the oil collected in the oil tank 103, blow-by gas and oil mist are generated in the oil tank 103. Therefore, similarly to the above, an oil separator chamber 104 that separates oil from blow-by gas is formed at the upper end of the oil tank 103. It is also preferable to form a sludge suppressing layer on the inner surface of the oil separator chamber 104, particularly on the upper and lower surfaces thereof. The blow-by gas after oil separation in the oil separator chamber 104 of the oil tank 103 is returned to the intake side through the PCV valve 108.

  In addition, the oil separator chamber may be installed adjacent to the crankcase or the cylinder block. Even in such a case, it is preferable to form a sludge suppressing layer on the inner surface of the oil separator chamber.

  As mentioned above, although preferred embodiment of this invention was described, this invention can also take other embodiment other than the above. For example, the alkaline substance forming the sludge suppression layer can be other than calcium carbonate. Various other parts can be considered as the part for forming the sludge suppressing layer.

  In the embodiment described above, the sludge suppression layer is formed on the upper and lower surfaces of the oil separator chamber. However, the sludge suppression layer may be formed only on the upper surface or only the lower surface of the oil separator chamber. In the above embodiment, the oil separator chamber is provided in the head cover, and the inner surface of the head cover and the upper surface of the oil separator chamber are combined. However, the head cover is not provided with the oil separator chamber. A sludge suppressing layer may be formed alone on the inner surface of the head cover. Further, in the case where the oil separator chamber is provided in the head cover, a sludge suppressing layer may be formed on the inner surface of the head cover in a portion other than the oil separator chamber. The installation position of the oil separator chamber is not particularly limited, and in particular, when the oil separator chamber has an outer surface exposed to the outside air, it is preferable to form a sludge suppression layer on the inner surface of the oil separator chamber located on the back side of the outer surface. .

  The embodiment of the present invention is not limited to the above-described embodiment, and includes all modifications, applications, and equivalents included in the concept of the present invention defined by the claims. Therefore, the present invention should not be construed as being limited, and can be applied to any other technique belonging to the scope of the idea of the present invention.

1,100 Engine 2 Cylinder block 5 Cylinder head 4 Crankcase 6 Head cover 15 Timing chain 17 Chain cover 23A, 23B Groove 24A, 24B Baffle plate 25A, 25B Oil separator chamber 35A, 35B Sludge suppression layer 36A, 36B Upper surface of oil separator chamber 37A, 37B Lower surface of oil separator chamber 42 Alkaline substance 38 Particle 39 Target surface 40 Hole 41 Plate

Claims (8)

  A sludge suppression layer for suppressing the generation or adhesion of sludge is formed on the surface of the internal combustion engine where oil as a liquid does not always flow and where oil mist as a gas is contacted A sludge adhesion suppressing structure for an internal combustion engine characterized by the above.   2. The sludge adhesion suppressing structure for an internal combustion engine according to claim 1, wherein the surface of the part is an inner surface of a part having an outer surface exposed to outside air.   The surface of the part is at least one of an inner surface of a head cover that covers a cylinder head, an inner surface of a chain cover that covers a timing chain, and an inner surface of an oil separator chamber that separates oil from blow-by gas. Item 3. A sludge adhesion suppressing structure for an internal combustion engine according to Item 2.   4. The sludge adhesion suppressing structure for an internal combustion engine according to claim 1, wherein the sludge suppressing layer is made of a solid alkaline substance.   The sludge adhesion suppressing structure for an internal combustion engine according to claim 4, wherein the alkaline substance is made of calcium carbonate.   6. The sludge adhesion suppressing structure for an internal combustion engine according to claim 1, wherein a surface of the sludge suppressing layer is formed in an uneven shape.   The sludge adhesion inhibiting structure for an internal combustion engine according to claim 6, wherein the sludge inhibiting layer is composed of at least one of a combination of a large number of particles and a foamed substance.   6. The sludge adhesion suppression structure for an internal combustion engine according to claim 1, wherein the sludge suppression layer is formed by coating.

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