JP2013204434A - Multi-cylinder internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the fork part of branched pipe from being broken by restraining an exhaust manifold from being pulled by thermal expansion of cylinder head, in an internal combustion engine in which the exhaust manifold including a plurality of branch pipes is fixed to the cylinder head.SOLUTION: An exhaust manifold 7 includes a plurality of branch pipes 7b and a flange 10 provided at the tip end of the branch pipe 7b is fixed to one side face 3a of a cylinder head 3 by a stud bolt 12 and a nut 13. In the cylinder head 3, the bolt 14 penetrates a portion where the exhaust manifold 7 is provided, and thermal expansion of the cylinder head 3 is suppressed by the bolt 14. It is more preferable to pre-compress the cylinder head 3 and the exhaust manifold 7 in a right and left direction.

Description

  The present invention relates to a multi-cylinder internal combustion engine having a plurality of cylinders.

  In an internal combustion engine, an exhaust manifold that discharges exhaust gas after combustion is fixed to one side surface of a cylinder head with bolts or stud bolts and nuts. In the multi-cylinder internal combustion engine, the exhaust manifold has a form in which a plurality of branch pipes are branched from one collecting portion. A flange is provided at the tip of each branch pipe, and the flange is fastened to the cylinder head via a gacket. ing. A gasket is interposed between the flange and the cylinder head, and the flange may be individually provided for each branch pipe, or the adjacent flange may be continuously integrated.

  Now, since the cylinder head receives heat by the combustion of fuel, it is inevitable that the cylinder head thermally expands during operation of the engine. In this case, since the cylinder head of the multi-cylinder internal combustion engine has a shape that is long in the direction in which the cylinder bores are arranged (the direction of the axis of the crankshaft), the cylinder head tends to expand greatly in the direction in which the cylinder bores are arranged. In addition, since the cylinder head is often made of aluminum or an aluminum alloy, the thermal expansion coefficient is considerably larger than that of steel (iron).

  On the other hand, because the exhaust manifold is exposed to exhaust gas, it is manufactured with iron castings or welded with steel pipes as the material, but iron castings and steel pipes also have a smaller thermal expansion coefficient than aluminum, Although thermal expansion occurs in the direction in which the branch pipes are arranged, the amount of thermal expansion is considerably smaller than that of the cylinder head. For this reason, due to the thermal expansion of the cylinder head, a pulling force that widens the interval between the branch pipes acts on the exhaust manifold, and as a result, the crotch portion where the branch pipes are connected to each other may be broken (broken). It was.

  In this regard, Patent Document 1 discloses that each branch pipe of the exhaust manifold is formed so as to become thinner as it goes to the tip (going to the side opposite to the assembly portion), thereby facilitating thermal deformation of each branch pipe. It is described that it is conditioned.

Japanese Utility Model Sho 62-98720 microfilm

  In Patent Document 1, the thermal expansion of the cylinder head itself is unavoidable and the exhaust manifold is easily deformed so as to absorb the thermal deformation of the cylinder head by the deformation of the exhaust manifold. If the thickness is reduced, there is a problem that the strength is lowered and corrosion is likely to proceed. Moreover, although patent document 1 is applicable to a cast product, there also exists a problem that it cannot apply to the exhaust manifold manufactured with the steel pipe.

  The present invention has been made to improve the current situation.

  The invention of the present application (invention of claim 1) has a cylinder head having a plurality of exhaust passages opened on one side surface, and an exhaust manifold in which a plurality of branch pipes communicating with the exhaust passages are gathered in a gathering portion. In the internal combustion engine in which each branch pipe of the exhaust manifold is provided with a flange that overlaps one side surface of the cylinder head, and the flange is fixed to the cylinder head with a fastener. Among them, there is adopted a configuration in which at least one side portion is provided with a restricting means for suppressing thermal expansion in the arrangement direction of the branch pipes of the exhaust manifold (that is, the axial direction of the crankshaft).

  As the restricting means, for example, a restricting body having a coefficient of thermal expansion smaller than that of the cylinder head is cast in a portion closer to one side surface of the cylinder head, and an exhaust manifold is fastened to the restricting body, or the cylinder head is arranged in an array of exhaust manifolds. Various means such as regulation with a bolt whose thermal expansion is smaller than that of the cylinder head can be employed so as not to thermally expand in the direction.

  In the case where a bolt is used as the restricting means, in claim 2, the bolt is used to more accurately prevent the exhaust manifold from being broken. That is, the invention of claim 2 is the invention according to claim 1, wherein the regulating means is a bolt having a thermal expansion coefficient smaller than that of the material of the cylinder head, and the bolt connects the cylinder head or the exhaust manifold 7 to the exhaust manifold. It is arranged so that it can be clamped in the direction in which the branch pipes are arranged, and by tightening the bolt, either one or both of the cylinder head and the exhaust manifold are pre-compressed so as to shrink in the direction in which the branch pipes are arranged. ing.

  In the present invention, the thermal expansion of the cylinder head is suppressed, so that it is possible to prevent or remarkably suppress the pulling of the crotch portion of the exhaust manifold from acting on the crotch portion of the exhaust manifold. And since it suppresses the thermal expansion of the cylinder head, the exhaust manifold may remain the conventional material and structure. Therefore, there is no inconvenience that the strength of the exhaust manifold is reduced and the exhaust manifold is easily corroded, and the exhaust manifold can be applied to the steel pipe exhaust manifold without any trouble.

  The restricting means may be configured to exhibit a function when the cylinder head receives heat and suppress its thermal expansion. However, the restricting means adopts the structure of claim 2 to provide the cylinder head, the exhaust manifold, If at least one of them is pre-compressed in the direction in which the branch pipes are arranged, the effect of preventing the exhaust manifold from breaking can be further improved.

  That is, when only the cylinder head is pre-compressed, even if the cylinder head expands by the amount of thermal expansion of the bolt, the cylinder head only returns to the free length where no thermal load is applied, Or since it can be in a state of only a slight expansion from the free length, it is possible to more accurately prevent or suppress the tensile force from acting on the exhaust manifold due to the thermal expansion of the cylinder head.

  On the other hand, if only the exhaust manifold is pre-compressed, even if the cylinder head expands by the amount of thermal expansion of the bolt and the exhaust manifold is pulled, the exhaust manifold will first have a free length that is not subject to thermal load. Then, since substantial thermal expansion then starts, it is possible to more accurately prevent or suppress the tensile force from acting on the exhaust manifold. That is, an expansion allowance that does not act on the exhaust manifold can be given to the exhaust manifold, and thereby, a breakage preventing effect can be realized more accurately. It is more preferable to pre-compress both the cylinder head 3 and the exhaust manifold 7.

It is a figure which shows 1st Embodiment, (A) is a top view, (B) is the BB view front view of (A). It is a figure which shows 2nd Embodiment, (A) is a top view, (B) is the BB view front view of (A). It is the II-II sectional view taken on the line of FIG. It is a figure which shows 3rd Embodiment.

  Next, an embodiment of the present invention will be described with reference to the drawings. In addition, in order to specify the direction in the following description, the terms “front and rear” and “left and right” are used for convenience, but the crankshaft is viewed from the direction orthogonal to the axis of the crankshaft and the cylinder bore. The axial direction of the shaft is the left-right direction, and the direction orthogonal to the crankshaft and the cylinder bore is the front-rear direction.

(1) First Embodiment First, the first embodiment shown in FIG. 1 will be described. The internal combustion engine of the present embodiment has four cylinders, and four cylinder bores 2 are formed in series in the cylinder block 1, and the cylinder head 3 that is overlapped and fixed on the upper surface of the cylinder block 1 is directed toward the cylinder bore 2. An open combustion recess 4 is formed. The cylinder head 3 is an aluminum casting.

  Further, the cylinder head 3 has four pairs of exhaust passages 4 and intake passages 5 communicating with the combustion recesses 4. The exhaust passages 4 open to one side surface 3a of the front and rear side surfaces, and the intake passage 5 Is formed to open to the other side surface 3b of the front and rear side surfaces, the exhaust manifold 7 is fixed (fastened) to one side surface 3a of the cylinder head 3, and the intake manifold 8 is fixed to the other side surface 3b. Has been. The exhaust manifold 7 is made of steel pipe or iron-based casting.

  The exhaust manifold 7 and the intake manifold 8 are in a form in which four branch pipes 7b and 8b are branched from the collecting portions 7a and 8a, and flanges 10 and 11 extending in series in the left-right direction at the ends of the branch pipes 7b and 8b. The flanges 10 and 11 are fastened to the cylinder head 3 with stud bolts 12 and nuts 13 as an example of fasteners (the stud bolts and nuts are not shown for the intake manifold 8). Although it is not necessary to mention, each branch pipe 7b, 8b is located in a line along the longitudinal direction of the crankshaft (alignment direction of the cylinder bores 2). A gasket is interposed between the flange 10 of the exhaust manifold 7 and the cylinder head 3.

  Two upper and lower bolts 14 in a posture parallel to the crankshaft are provided in a portion near the side surface 3a to which the exhaust manifold 7 is fixed in the cylinder head 3 and on both upper and lower portions sandwiching the exhaust passage 4. The cylinder head 3 is disposed so as to be exposed at the left and right end faces 3c, 3d. On one end surface 3c of the cylinder head 3, an up-and-down longitudinal attachment plate 15 through which both bolts 14 pass is disposed, and on the other end surface 3d of the cylinder head 3, the up-and-down longitudinal length at which both bolts 14 are screwed together. The plate-shaped nuts 16 are stacked. The bolt 14 is made of steel such as carbon steel or high-tensile steel, and has a thermal expansion coefficient close to that of the exhaust manifold 7. In this embodiment, the bolt 14, the accessory plate 15, and the plate-like nut 16 constitute the restricting means described in the claims.

  The accessory plate 15 overlaps one end surface 7 a of the left and right end surfaces of the exhaust manifold 7, and the plate-like nut 16 overlaps the other end surface 7 a of the left and right end surfaces of the exhaust manifold 7, and the exhaust manifold 7 is screwed into the nut 13. After fixing the cylinder head 3 to the cylinder head 3, the bolt 14 is screwed into the plate nut 16 and the cylinder head 3 and the exhaust manifold 7 are strongly clamped in the axial direction of the crankshaft. Is compressed from a free state in which no internal stress exists into a state of being compressed and deformed in the axial direction of the crankshaft.

  In FIG. 1 (A), the free length state of the cylinder head 3 is indicated by a one-dot chain line, and the free length state of the one-dot chain line and the compressed state of the solid line are displayed with a visible difference. Is an expedient display, and the actual amount of compressive deformation is a small amount that absorbs the thermal expansion accompanying the operation of the engine. Further, since the bolt 14 is disposed only in the vicinity of the one side surface 3a of the cylinder head 3, it is assumed that the cylinder head 3 is hardly or not compressed at the portion of the other side surface 3b. Since there are very few, the problem accompanying the deformation | transformation of the cylinder head 3 does not arise.

  When the temperature of the cylinder head 3 rises with the operation of the engine, the cylinder head 3, the exhaust manifold 7 and the bolt 14 tend to thermally expand in the axial direction of the crankshaft. In this case, since the exhaust gas directly touches the exhaust manifold 7, it can be said that the temperature rise is the fastest in the exhaust manifold 7, followed by the cylinder head 3 and then the bolt 14.

  Since the cylinder head 3 eventually becomes hot, it receives a thermal load that thermally expands in the axial direction of the crankshaft. In that case, the thermal expansion of aluminum, which is the material of the cylinder head 3, is larger than the steel (iron), which is the material of the exhaust manifold 7. When pulled in the direction, the crotch portion 7c between the adjacent branch pipes 7b may be torn.

  On the other hand, in the present embodiment, since the thermal expansion of the cylinder head 3 is restricted by the bolt 14 having a low thermal expansion, the cylinder head 3 is restrained from thermally expanding in the left-right direction. It is possible to prevent or remarkably suppress the action of a pulling force in the left-right direction, thereby preventing breakage.

  More specifically, since the bolt 14 is also thermally expanded, the cylinder head 3 is thermally expanded in the left-right direction by the amount of thermal expansion of the bolt 14, but the thermal expansion coefficient of the bolt 14 is almost the same as that of the exhaust manifold 7. Therefore, even if the cylinder head 3 is thermally expanded by the amount of thermal expansion of the bolt 14, it is possible to prevent or remarkably suppress the lateral pulling force from acting on the crotch portion 7 c of the exhaust manifold 7.

  Therefore, even if the cylinder head 3 and the exhaust manifold 7 are not strongly clamped by the bolts 14, the exhaust manifold 7 can be prevented from breaking even if the thermal expansion of the cylinder head 3 is simply suppressed by the bolts 14. In this embodiment, since the cylinder head 3 and the exhaust manifold 7 are preliminarily compressed by the bolts 14, even if the cylinder head 3 is thermally expanded by the same amount as the bolts 14, the exhaust manifold 7 has a thermal load. It only returns to the free length that is not applied, or only slightly thermal expansion from the free state, and thereby, the breakage of the crotch portion 7c can be prevented more accurately.

  As can be understood from the above description, the amount of preliminary compression deformation of the cylinder head 3 and the exhaust manifold 7 due to the clamping pressure of the bolt 14 is preferably set to the same size as the maximum thermal expansion amount of the exhaust manifold 7. . The bolt 14 is preferably not thermally expanded as much as possible. Accordingly, it is possible to fit a cylinder made of a heat insulating material into the bolt 14.

  When the exhaust manifold 7 is sandwiched between the attachment plate 15 and the plate-like nut 16 from the left and right, either the fastening of the exhaust manifold 7 or the clamping pressure by the bolt 14 may be performed first. When the exhaust manifold 7 is not sandwiched between the left and right nuts 16, it is preferable to first fasten the exhaust manifold 7 to the cylinder head 3 and then perform clamping with bolts 14 (otherwise, the exhaust manifold 7 Cannot be pre-compressed.)

  When the exhaust manifold 7 is not sandwiched between the attachment plate 15 and the plate-like nut 16 from the left and right, the flange 10 of the exhaust manifold 7 is set so that it cannot be displaced to the stud bolt 12 or a knock pin is provided separately. Thus, it is more beneficial to hold the exhaust manifold 7 and the cylinder head 3 so as not to slide in the left-right direction. Of course, it is also possible to apply a pre-compression deformation only to the cylinder head 3, and in this case, the exhaust manifold 7 may be fastened after the cylinder head 3 is pre-compressed.

(2) Other Embodiments In the second embodiment shown in FIG. 2, a restriction plate 18 as an example of a restriction means is cast into the cylinder head 3. The restricting plate 18 has a number of holes 19 in order to improve the integrity with the cylinder head 3. It is also possible to weld the stud bolt 14 to the restriction plate 18. Alternatively, a nut may be welded to the restriction plate 18 or a female screw may be formed in a burring portion provided on the restriction plate 18 and a bolt may be screwed into them to fasten the exhaust manifold 7. .

  The restricting plate 18 is made of a steel material such as carbon steel like the exhaust manifold 7. Therefore, in the second embodiment, even if the aluminum portion of the cylinder head 3 is largely thermally expanded, the restriction plate 18 does not thermally expand so much, and the coefficient of thermal expansion between the restriction plate 18 and the exhaust manifold 7 is almost the same. Since it is the same, the exhaust manifold 7 is not pulled in the left-right direction.

  In the third embodiment shown in FIG. 3, end plates 10 a that overlap the end surfaces 3 b and 3 c of the cylinder head 3 are integrally provided on the left and right ends of the flange 10 in the exhaust manifold 7, and the end plate 10 a is connected to the bolt 14 and the nut ( The cylinder head 3 is fastened together (not shown). In the case of FIG. 3, the distance between the left and right end plates 10 a is set to be slightly larger than the left and right lengths of the cylinder head 3, and the left and right end plates 10 a are bolted 14 with the exhaust manifold 7 compressed in the left and right direction. It is also possible to fasten to the cylinder head 3.

  That is, it is possible to pre-compress only the exhaust manifold 7. In this case, since the cylinder head 3 is thermally expanded only by the thermal expansion of the bolt 14, it exhibits substantially the same operations and effects as in the first embodiment. In the case of the first embodiment as well, it is possible to pre-compress only the exhaust manifold 7 by making the left and right lengths of the exhaust manifold 7 slightly longer than the left and right lengths of the cylinder head 3.

  The present invention can be embodied in various ways other than the above-described embodiment. For example, the flanges can be provided individually for each branch pipe, or can be provided in groups for a plurality of branch pipes. As the restricting means, it is also possible to adopt a giant vise method (clamp method) in which a bolt is provided on a U-shaped main body covering the cylinder head.

  It is also possible to use bolts with heads as fasteners. When a bolt is used as the restricting body, the splicing plate and the plate-like nut are not necessarily required, and a configuration in which the nut is screwed into the headed bolt may be employed. It is sufficient that the restricting means of the present invention is provided in the vicinity of the cylinder head where the exhaust manifold is fixed, but this does not exclude the provision of the restricting means in the portion where the intake manifold is fixed.

  The present invention can be actually manufactured by embodying an internal combustion engine. Therefore, it can be used industrially.

DESCRIPTION OF SYMBOLS 2 Cylinder bore 3 Cylinder head 6 Exhaust passage 7 Exhaust manifold 7a Collecting part 7b Branch pipe 7c Crotch part 10 Flange 12 Stud bolt which comprises a fastener 13 Nut which constitutes a fastener 14 Bolt as an example of main elements of a regulating body 15 Regulator 16 A plate-like nut as a part of the regulating body 18 A cast-in type regulating plate as an example of a regulating means

Claims (2)

A cylinder head having a plurality of exhaust passages open on one side surface; and an exhaust manifold in which a plurality of branch pipes communicating with the respective exhaust passages are gathered in a collecting portion. Provided with a flange overlapping one side surface of the cylinder head, and the flange is fixed to the cylinder head with a fastener,
The cylinder head is provided with a restricting means for suppressing thermal expansion of at least one side portion of the cylinder head in the direction in which the branch pipes of the exhaust manifold are arranged.
Multi-cylinder internal combustion engine. The restricting means is a bolt having a thermal expansion coefficient smaller than that of the material of the cylinder head, and the bolt is arranged so that the cylinder head or the exhaust manifold 7 can be clamped in the direction in which the branch pipes of the exhaust manifold are arranged. And, by tightening the bolts, either one or both of the cylinder head and the exhaust manifold is pre-compressed so as to contract in the direction in which the branch pipes are arranged,
Multi-cylinder internal combustion engine.

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