JP2011106395A - Cooling structure of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the increase of oil consumption by uniformizing a gap between a cylinder bore and a piston of each cylinder of a cylinder block in which a spacer is attached to a water jacket. <P>SOLUTION: A gap ε' between an intermediate cylinder bore 12a' and an intermediate piston 18' is set to be smaller than a gap ε between an end cylinder bore 12a and an end piston 18 in a cross section orthogonal to a cylinder line L1. Accordingly, even when the intermediate cylinder bore 12a' at relatively high temperature is thermally expanded more than the end cylinder bore 12a at relatively low temperature, the gap ε' between the intermediate cylinder bore 12a' and the intermediate piston 18' and the gap ε between the end cylinder bore 12a and the end piston 18 are uniformized. Thus, the increase of oil consumption can be prevented. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  According to the present invention, a spacer is mounted inside a water jacket formed so as to surround three or more cylinder bores juxtaposed on a cylinder row line of a cylinder block of an internal combustion engine, and cooling of the water jacket is performed by the spacer. The present invention relates to a cooling structure for an internal combustion engine that regulates the cooling state of the cylinder bore by regulating the flow of water.

  In such a cooling structure for an internal combustion engine, the heat transfer coefficient of the spacer mounted inside the water jacket is set so that the thrust / anti-thrust side of the cylinder bore (part away from the cylinder row line) and the bore of the cylinder bore (on the cylinder row line). It is known from Patent Document 1 below that the cylinder bore is cooled evenly over the entire circumference by making the difference between the first and second portions.

Japanese Patent No. 3596438

  By the way, in a cylinder block in which three or more cylinder bores are juxtaposed along the cylinder row line, two cylinder bores (end cylinder bores) at both ends in the cylinder row line direction have only one adjacent cylinder bore. While the amount of heat received from the cylinder bore becomes relatively low, the other cylinder bores (intermediate cylinder bores) excluding the end cylinder bore have two adjacent cylinder bores, so the amount of heat received from the adjacent cylinder bores increases and is compared. Becomes hot.

  In this way, there is a temperature difference between the end cylinder bore and the intermediate cylinder bore. However, if the end cylinder bore and the intermediate cylinder bore are kept warm evenly by the spacer, the hot intermediate cylinder bore expands greatly against the cold cylinder bore. The diameter increases, and the gap between the intermediate cylinder bore and the intermediate piston fitted thereto becomes larger than the gap between the end cylinder bore and the end piston fitted therein. As a result, although the friction between the intermediate cylinder bore and the intermediate piston is reduced, the oil in the crankcase leaks into the combustion chamber from the enlarged gap between the intermediate cylinder bore and the intermediate piston, and the oil consumption increases. There's a problem.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to uniformize the gap between the cylinder bore and the piston of each cylinder of a cylinder block in which a spacer is attached to a water jacket, thereby suppressing an increase in oil consumption. .

  In order to achieve the above object, according to the first aspect of the present invention, there is provided a water jacket formed so as to surround three or more cylinder bores juxtaposed on a cylinder row of a cylinder block of an internal combustion engine. In an internal combustion engine cooling structure in which spacers are mounted inside and the cooling water flow in the water jacket is regulated by the spacers to adjust the cooling state of the cylinder bores, end cylinder bores positioned at both ends in the cylinder row line direction An end piston is slidably fitted to the intermediate cylinder bore, and an intermediate piston is slidably fitted to the intermediate cylinder bore excluding the end cylinder bore, and the intermediate cylinder bore and the intermediate in a cross section perpendicular to the cylinder row line The clearance between the pistons is the end cylinder bore and the end piston in a cross section orthogonal to the cylinder row line. Cooling structure for an internal combustion engine, characterized in that it is set smaller than the gap between the emission is proposed.

  According to the second aspect of the present invention, in addition to the configuration of the first aspect, in the water jacket, one side surface of the cylinder row line is upstream in the flow direction of the cooling water and the other side surface is the cooling water. The gap between the intermediate cylinder bore and the intermediate piston facing the downstream side in the cross section perpendicular to the cylinder row line is smaller than the gap between the intermediate cylinder bore and the intermediate piston facing the upstream side. A cooling structure for an internal combustion engine is proposed, which is characterized by being set to a small value.

  According to a third aspect of the present invention, in addition to the configuration of the first aspect, in the cross section perpendicular to the cylinder row line, the intermediate cylinder bore and the intermediate piston facing the exhaust side surface of the cylinder block are arranged. A cooling structure for an internal combustion engine is proposed in which the gap is set smaller than the gap between the intermediate cylinder bore and the intermediate piston facing the intake side surface of the cylinder block.

  The end cylinder bore 12a and the intermediate cylinder bore 12a 'in the embodiment correspond to the cylinder bore of the present invention.

  According to the configuration of the first aspect, since the spacer is mounted inside the water jacket formed so as to surround the cylinder bore of the cylinder block of the internal combustion engine, the flow of the cooling water in the water jacket is regulated by the spacer. By keeping the cylinder bore warm, the cylinder bore can be thermally expanded to reduce friction with the piston. The cylinder bore has an end cylinder bore located at both ends in the cylinder row line direction, and an intermediate cylinder bore excluding the end cylinder bore. The end piston is slidably fitted to the end cylinder bore, and the intermediate cylinder bore The intermediate piston is slidably fitted. Since the gap between the intermediate cylinder bore and the intermediate piston is set to be smaller than the gap between the end cylinder bore and the end piston in the cross section perpendicular to the cylinder row line, the intermediate cylinder bore that is relatively high in temperature is relatively low in temperature. Even if the thermal expansion is larger than that of the end cylinder bore, the clearance between the intermediate cylinder bore and the intermediate piston and the clearance between the end cylinder bore and the end piston are made uniform to prevent an increase in oil consumption. be able to.

  According to the configuration of claim 2, the gap between the intermediate cylinder bore and the intermediate piston in the cross section orthogonal to the cylinder row line is a portion of the water jacket facing the downstream side in the cooling water flow direction where the intermediate cylinder bore is relatively hot. In the water jacket where the intermediate cylinder bore is relatively low in temperature and set large in the portion facing the upstream side of the cooling water flow direction, it is possible to effectively suppress the expansion of the gap due to the thermal expansion of the cylinder bore. it can.

  According to the third aspect of the present invention, the clearance between the intermediate cylinder bore and the intermediate piston in the cross section orthogonal to the cylinder row line is set small at the portion facing the exhaust side of the cylinder block that becomes relatively high in temperature, Since it is set large at the portion facing the intake side of the cylinder block that becomes low temperature, it is possible to effectively suppress the expansion of the gap due to the thermal expansion of the cylinder bore.

The perspective view of the cylinder block of an in-line 4 cylinder internal combustion engine. (First embodiment) The perspective view of a spacer. (First embodiment) FIG. 3 is a three-direction arrow view of FIG. 1. (First embodiment) FIG. 4 is a four-direction arrow view of FIG. 3. (First embodiment) FIG. 5 is a sectional view taken along line 5-5 of FIG. (First embodiment) FIG. 6 is an enlarged view of 6 parts in FIG. 5. (First embodiment) FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. 3. (First embodiment) FIG. 8 is a cross-sectional view taken along line 8-8 in FIG. 3. (First embodiment) FIG. 9 is a sectional view taken along line 9-9 in FIG. 3. (First embodiment) FIG. 10 is a sectional view taken along line 10-10 in FIG. 3; (First embodiment) Sectional view taken along line 11-11 in FIG. 3 (FIG. 11A), sectional view taken along line BB in FIG. 11A (FIG. 11B), and sectional view taken along the line CC in FIG. FIG. 11 (C). (First embodiment) 12-12 sectional view (FIG. 12A), BB sectional view of FIG. 12A (FIG. 12B), and CC sectional view of FIG. 12B. FIG. 12 (C). (First embodiment) Schematic diagram showing setting of clearance between cylinder bore and piston (first embodiment) Schematic diagram showing setting of clearance between cylinder bore and piston (second embodiment) Schematic diagram showing setting of clearance between cylinder bore and piston (third embodiment)

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, four cylinder sleeves 12 are embedded in the cylinder block 11 of the in-line four-cylinder internal combustion engine along the cylinder line L1 so as to surround the outer peripheral surfaces of the cylinder sleeves 12. A water jacket 13 is formed on the surface. The cylinder block 11 of the present embodiment is a siamese type, and the water jacket 13 is not formed between adjacent cylinder sleeves 12... Thereby shortening the dimension of the internal combustion engine in the direction of the cylinder row L1. . The water jacket 13 that opens to the deck surface 11a of the cylinder block 11 extends downward from the water jacket 13 at a certain depth toward the crankcase, and the cylinder block is interposed between the inner wall surface 13a and the outer wall surface 13b of the water jacket 13. A synthetic resin spacer 14 inserted from the opening side of the 11 deck surface 11a is disposed.

  In the present specification, the “vertical direction” is defined as “upper” on the cylinder head side in the cylinder axis L2 direction and “lower” on the crankcase side in the cylinder axis L2 direction.

  As apparent from FIGS. 1 to 5, the spacer 14 includes a spacer main body 14 a, a cooling water inlet 14 b and a cooling water outlet 14 c, whereby the four cylinder bores 12 a, 12 a; 'And 12a' are surrounded all around. The cooling water inlet portion 14b surrounds the intake side of one cylinder bore 12a located at one end side (timing train side) in the cylinder row line L1 direction, and the cooling water outlet portion 14c is one end side in the cylinder bore 12a cylinder row line L1 direction. And surrounds the exhaust side. The spacer 14 is formed to be thicker than the spacer main body 14a at a position slightly shifted from one end side in the cylinder row line L1 direction to the intake side and sandwiched between the cooling water inlet portion 14b and the cooling water outlet portion 14c. And the partition wall 14d which protrudes up and down from the upper edge and lower edge of the cooling water inlet part 14b and the cooling water outlet part 14c is provided integrally.

  Inside the water jacket 13, an upper cooling water passage 13 c is formed between the upper edge of the spacer body 14 a and the lower surface of the cylinder head 15 so as to surround the four cylinder bores 12 a, 12 a; 12 a ′, 12 a ′. At the same time, a lower cooling water passage 13d is formed between the lower edge of the spacer body 14a and the bottom of the water jacket 13 to surround the four cylinder bores 12a, 12a;

  The upper support leg 14e and the lower support leg 14f project into the upper cooling water passage 13c and the lower cooling water passage 13d from the position where the cylinder row line L1 intersects the cooling water outlet portion 14c on one end side, respectively. The upper support leg 14g and the lower support leg 14h protrude into the upper cooling water passage 13c and the lower cooling water passage 13d from a position where L1 intersects the spacer main body 14a on the other end side (transmission side). Therefore, when the spacer 14 is mounted inside the water jacket 13, the lower ends of the pair of lower support legs 14f and 14h are in contact with the bottom portions of the water jacket 13 at both ends of the spacer 14 in the cylinder row line L1 direction. When the upper ends of the support legs 14 e and 14 g are in contact with the lower surface of the gasket 16 sandwiched between the support heads 14 e and 14 g, the spacer 14 is positioned in the vertical direction.

  Pistons 18, 18; 18 ', 18' connected to the crankshaft 17 are slidably fitted to the cylinder bores 12a, 12a; 12a ', 12a', and the pistons 18, 18; 18 ', 18 A top ring 19, a second ring 20, and an oil ring 21 are mounted on the top 18 a.

  Hereinafter, the detailed structure of the spacer 14 will be sequentially described.

  As is apparent from FIG. 4, the height of the spacer main body portion 14a, the cooling water inlet portion 14b, and the cooling water outlet portion 14c in the cylinder 14 in the cylinder axis L2 direction is constant H over the entire circumference. As apparent from FIGS. 2 and 3, the thickness T1 of the spacer body 14a is basically constant, but the thickness T2 of the cooling water inlet 14b is thinner than the thickness T1 of the spacer body 14a. The thickness T3 of the cooling water outlet 14c is thinner than the thickness T1 of the spacer body 14a, and the thickness T4 of the partition wall 14d is thicker than the thickness T1 of the spacer body 14a. The inner peripheral surface of the cooling water inlet portion 14b is flush with the inner peripheral surface of the spacer main body portion 14a, and the outer peripheral surface of the cooling water inlet portion 14b is radially inward through a step with respect to the outer peripheral surface of the spacer main body portion 14a. It is biased to. The outer peripheral surface of the cooling water outlet portion 14c is flush with the outer peripheral surface of the spacer main body portion 14a, and the inner peripheral surface of the cooling water outlet portion 14c is radial with respect to the inner peripheral surface of the spacer main body portion 14a through a step. It is biased outward.

  As is apparent from FIG. 5, when the pistons 18, 18; 18 ', 18' move up and down in the cylinder bores 12a, 12a; 12a ', 12a' as the crankshaft 17 rotates, the pistons 18, 18; ′, 18 ′ and the cylinder bores 12a, 12a; the side thrust acting between the cylinder bores 12a ′, 12a ′ changes periodically, and the positions of the pistons 18, 18; 18 ′, 18 ′ in the expansion stroke shown by solid lines (for example, compression Side thrust is maximized at a crank angle of 15 ° after top dead center. At the position where the side thrust is maximized, the top rings 19 of the pistons 18, 18; 18 ′, 18 ′, the second ring 20, and the oil ring 21 are positioned above the upper edge of the spacer 14, and the piston The upper and lower positions of the spacer 14 in the water jacket 13 are set so that the skirt portions 18 b of the 18, 18; 18 ′, 18 ′ are positioned below the upper edge of the spacer 14. Further, at the bottom dead center position of the pistons 18, 18; 18 ', 18' indicated by chain lines, the top ring 19 ..., the second ring 20 ... and the oil ring 21 ... of the piston 18, 18; The vertical position of the spacer 14 in the water jacket 13 is set so as to be positioned below the lower edge.

  As can be seen from FIG. 6, the thickness T1 of the spacer body 14a is set slightly smaller than the width W of the water jacket 13 into which it is fitted. The reason is that since the dimensional accuracy of the inner wall surface 13a and the outer wall surface 13b of the as-cast water jacket 13 is not high, the spacer 14 is rubbed against the inner wall surface 13a and the outer wall surface 13b of the water jacket 13 and the assemblability is lowered. It is for preventing. Therefore, when the spacer 14 is assembled in the water jacket 13, a gap α is formed between the inner peripheral surface of the spacer main body 14a and the inner wall surface 13a of the water jacket 13, and the outer peripheral surface of the spacer main body 14a and the water are formed. A gap β is formed between the outer wall 13b of the jacket 13 and the gap α is smaller than the gap β. That is, the spacer main body 14a is closer to the inner wall 13a than the outer wall 13b of the water jacket 13. To be arranged.

  As apparent from FIGS. 3 and 7, between the bores of the cylinder block 11 where the two cylinder sleeves 12 and 12 approach each other, the water jacket 13 surrounding the circumference of each cylinder sleeve 12 and 12 has an acute angle with each other. Therefore, the width W ′ of the water jacket 13 in the direction perpendicular to the cylinder row line L1 is wider than the width W of the water jacket 13 in other portions. On the other hand, the thickness of the spacer main body 14a between the bores is the same as the thickness of the spacer main body 14a in the other portions, so the inner peripheral surface of the spacer main body 14a and the inner wall surface 13a of the water jacket 13 between the bores. Is exceptionally larger than the gap α in the other portions.

  However, between the bores where the two cylinder sleeves 12 and 12 approach each other, a radially inward convex portion 14i is formed at the upper end of the spacer main body portion 14a, and at the tip of these convex portions 14i, the water is formed. The gap α ″ between the inner wall surface 13a of the jacket 13 is set to be smaller than the gap α.

  As is apparent from FIGS. 1 to 3, 8, and 9, the cooling water supply passage 11 b extends from the end surface of the cylinder block 11 on the timing train side toward the transmission side, and downstream of the cooling water supply passage 11 b. A cooling water supply chamber 11 c connected to the end faces the cooling water inlet 14 b of the spacer 14 accommodated in the water jacket 13.

  As is apparent from FIGS. 1 to 3 and FIG. 9, four communication holes 15 a that open on the lower surface of a water jacket (not shown) formed in the cylinder head 15 are spacers accommodated in the water jacket 13. It faces the 14th cooling water outlet part 14c. The position of the cooling water outlet portion 14c substantially overlaps the extended spacer main body portion 14a when the spacer main body portion 14a is extended to the position of the cooling water outlet portion 14c.

  As apparent from FIGS. 1 to 3 and 10, the partition wall 14 d sandwiched between the cooling water inlet portion 14 b and the cooling water outlet portion 14 c of the spacer 14 is formed between the inner wall surface 13 a and the outer wall surface 13 b of the water jacket 13. There is a minimum gap γ (see FIG. 10) between which the spacer 14 can be assembled. A minute gap δ through which cooling water can pass is formed between the lower end of the partition wall 14d and the outer wall surface 13b of the water jacket 13. The upper and lower ends of the partition wall 14d have a function of positioning the spacer 14 in the vertical direction inside the water jacket 13 in the same manner as the upper support legs 14e and 14g and the lower support legs 14f and 14h.

  As is apparent from FIGS. 2 and 11, the portion sandwiched between the upper support leg 14e and the lower support leg 14f at the end of the spacer 14 on the timing train side (the portion of the cooling water outlet 14c) is the spacer body 14a. It is the thick part 14m of the same thickness. A slit 14n extending in the vertical direction is formed from the lower end of the lower support leg 14f to the upper end of the thick portion 14m, and the slit 22a of the fixing member 22 made of rubber having an H-shaped horizontal section is fitted into the slit 14n. Installed. The fixing member 22 is mounted within the range of the height in the vertical direction of the spacer body 14a, and its outer peripheral surface is not exposed to the outer peripheral surface of the spacer 14, but its inner peripheral surface is exposed to the inner peripheral surface of the spacer 14. And elastically contact the inner wall surface 13a of the water jacket 13. A part of the slit 14n exposed to the lower support leg 14f is for reducing the press-fitting resistance of the fixing member 22 and improving the assembling property.

  As is apparent from FIGS. 2 and 12, a slit 14o extending in the vertical direction is formed between the lower end of the lower support leg 14h and the lower end of the upper support leg 14g at the end of the spacer body 14a on the transmission side. The fixing member 22 made of rubber having an H-shaped horizontal cross section is attached to the slit 14o. The fixing member 22 is mounted within the range of the vertical height of the spacer body 14a, and the outer peripheral surface thereof is not exposed to the outer peripheral surface of the spacer 14, but the inner peripheral surface thereof is the water jacket 13 and the inner periphery of the spacer 14. It is exposed to the surface and elastically contacts the inner wall surface 13a of the water jacket 13. A part of the slit 14n exposed to the lower support leg 14o is for reducing the press-fitting resistance of the fixing member 22 and improving the assembling property.

  The two fixing members 22 and 22 are both arranged on the cylinder row line L1, and therefore the intake side portion and the exhaust side portion of the spacer 14 with respect to the line connecting the two fixing members 22 and 22 (that is, the cylinder row line L1). Is basically a symmetrical shape.

  The slits 14n and 14o are opened downward, and the fixing members 22 and 22 are fitted upward there. Therefore, when the spacer 14 to which the fixing members 22 and 22 are attached is inserted into the water jacket 13, the water Even if the fixing members 22, 22 are pushed upward by a frictional force acting between the inner wall surface 13a of the jacket 13, there is no possibility that the fixing members 22, 22 fall off from the slits 14n, 14o.

  As is apparent from FIG. 13, of the four cylinder bores 12a, 12a; 12a ′, 12a ′ juxtaposed on the cylinder row line L1, two of the cylinder bores 12a ′ and 12a ′ located at both ends in the direction of the cylinder row L1 are end cylinder bores 12a. , 12a, and the other two are called intermediate cylinder bores 12a 'and 12a'. The end pistons 18 and 18 are slidably fitted to the end cylinder bores 12a and 12a, and the intermediate pistons 18 'and 18' of the intermediate cylinder bores 12a 'and 12a' are slidably fitted.

  As exaggeratedly depicted in FIG. 13, the four cylinder bores 12a, 12a; 12a ', 12a' have the same shape, but the four pistons 18, 18; 18 ', 18' are end pistons 18; , 18 and the intermediate pistons 18 ', 18' are different in shape. That is, the diameters of the intermediate pistons 18 'and 18' on the exhaust side are larger than those of the end pistons 18 and 18, and the cylinder bores 12a and 12a; 12a 'and 12a' have a cross section perpendicular to the cylinder line L1. Where the cold clearance formed between the inner peripheral surface and the outer peripheral surfaces of the pistons 18, 18; 18 ', 18' should be essentially ε, the intermediate pistons 18 ', 18' have a larger diameter on the exhaust side. Therefore, the gap is ε ′ smaller than ε at that portion.

  Next, the operation of the embodiment of the present invention having the above configuration will be described.

  Before the cylinder head 15 is assembled to the deck surface 11a of the cylinder block 11, the water jacket is formed so as to surround the outer periphery of the cylinder bores 12a, 12a; 12a ', 12a' of the four cylinder sleeves 12 exposed on the deck surface 11a. 13 is open, and the spacer 14 is inserted into the water jacket 13 from the opening. Thereafter, the cylinder head 15 is fastened in a state where the gasket 16 is superimposed on the deck surface 11 a of the cylinder block 11.

  In the assembled state of the spacer 14, the lower ends of the lower support legs 14f and 14h and the lower end of the partition wall 14d are in contact with the bottom of the water jacket 13, and the upper ends of the upper support legs 14e and 14g and the upper end of the partition wall 14d are By contacting the lower surface of the gasket 16, the spacer 14 is positioned in the cylinder axis L2 direction. At this time, the inner peripheral surface of the spacer body 14a of the spacer 14 is arranged so as to be close to the inner wall surface 13a of the water jacket 13, but the dimensional accuracy of the inner wall surface 13a of the as-cast water jacket 13 is not high. In order to prevent the spacer 14 from rubbing against the inner wall surface 13a of the water jacket 13 and lowering the assemblability, a slight gap α is formed between the inner peripheral surface of the spacer main body 14a and the inner wall surface 13a of the water jacket 13. (See FIG. 6) is formed.

  If the spacer 14 moves up and down in the water jacket 13 due to vibration during operation of the internal combustion engine, the upper ends of the upper support legs 14e and 14g and the partition wall 14d may damage the lower surface of the gasket 16. The two fixing members 22, 22 provided at both ends of the line L <b> 1 direction fix the spacer 14 so as not to move with respect to the water jacket 13, thereby preventing the gasket 16 from being damaged due to the loose movement of the spacer 14.

  At this time, since the fixing members 22 are provided at both ends of the highly rigid spacer 14 in the cylinder row line L1, not only can the spacer 14 be firmly fixed inside the water jacket 13, but also the cylinder block. Since both ends of the cylinder 11 in the direction of the cylinder line L1 are lower in temperature than the side surfaces on the intake side and the exhaust side, it is possible to minimize the influence of heat on the rubber fixing members 22 and 22 attached thereto. it can.

  Further, since the fixing members 22 and 22 are provided in the middle portion of the spacer 14 in the cylinder axis L2 direction, that is, within the height range of the spacer main body 14a, the fixing members 22 and 22 are provided with the upper cooling water passage 13c and the lower cooling water. It is possible to prevent the flow of the cooling water in the passage 13d from being obstructed. Moreover, since the fixing member 22 on the timing train side of the spacer 14 is provided in the cooling water outlet portion 14c, the fixing member 22 affects the flow of the cooling water in the upper cooling water passage 13c and the lower cooling water passage 13d. There is no. In addition, since the cooling water makes a U-turn at the transmission side end portion of the water jacket 13, the flow velocity is lowered. Therefore, by providing the transmission side fixing member 22 there, the fixing member 22 is connected to the intake side of the water jacket 13 and the water jacket 13. Compared with the case where it is provided on the side surface on the exhaust side, the influence on the flow of the cooling water can be reduced.

  The upper support leg 14e and the lower support leg 14f on the timing train side of the spacer 14 are formed to be thinner in the radial direction than the thickness T1 of the spacer main body 14a, and the inside of the upper cooling water passage 13c and the lower cooling water passage 13d. Therefore, the water jacket 13 is arranged to be biased toward the outer wall surface 13b. Further, the upper support leg 14g and the lower support leg 14h on the transmission side of the spacer 14 are formed to be thinner in the radial direction than the thickness T1 of the spacer main body 14a, and inside the upper cooling water passage 13c and the lower cooling water passage 13d. Therefore, the water jacket 13 is arranged to be biased toward the inner wall surface 13a. As a result, the influence of the upper support legs 14e, 14g and the lower support legs 14f, 14h on the flow of the cooling water in the upper cooling water passage 13c and the lower cooling water passage 13d can be minimized, and the upper support legs 14e. , 14g and the lower support legs 14f, 14h are curved in an arc shape so as to follow the shapes of the inner wall surface 13a and the outer wall surface 13b of the water jacket 13, so that the influence on the flow of the cooling water can be further reduced. .

  Of the four cylinder bores 12a, 12a; 12a ', 12a', the outermost portion in the direction of the cylinder row L1 is difficult to receive heat from the other cylinder bores 12a ', 12a'. Is relatively low. On the other hand, portions of the four cylinder bores 12a, 12a; 12a ', 12a' located on the intake side and the exhaust side of the cylinder line L1 receive heat from the adjacent cylinder bores 12a, 12a; 12a ', 12a'. Since it is easy, the temperature of the part becomes comparatively high. In the present embodiment, the upper support legs 14e and 14g and the lower support legs 14f and 14h are provided at the outermost positions in the cylinder row line L1 direction where the temperature of the cylinder bores 12a and 12a is relatively low. Even if the cooling water flow in the water jacket 13 is somewhat obstructed by the upper support legs 14e and 14g and the lower support legs 14f and 14h, the influence of the water is reduced to a minimum, and the temperature of each cylinder bore 12a, 12a; 12a ', 12a' Can be made uniform.

  In particular, the upper support leg 14g and the lower support leg 14h on the transmission side are arranged along the inner wall surface 13a of the water jacket 13 facing the low temperature portion of the cylinder bore 12a on the transmission side. In 14 h, the cooling water is less likely to contact the inner wall surface 13 a of the water jacket 13, and the relatively low temperature cylinder bore 12 a can be kept warm, thereby further increasing the temperature of each cylinder bore 12 a, 12 a; 12 a ′, 12 a ′. It can be made more uniform.

  Since the fixing members 22 and 22 are made of rubber and are fitted and fixed to the slits 14n and 14o of the spacer 14, the fixing members 22 and 22 can be fixed to the spacer 14 without requiring a special member such as a bolt. . Further, since the fixing members 22 and 22 are provided directly above the lower support legs 14f and 14h, the spacer 14 faces down into the water jacket 13 while the fixing members 22 and 22 are pressed against the inner wall surface 13a of the water jacket 13. It is possible to prevent the spacer 14 from being deformed to be twisted when the lower end of the lower support legs 14f and 14h abuts against the bottom of the water jacket 13 and receives an upward reaction force.

  During operation of the internal combustion engine, cooling water supplied from a water pump (not shown) provided in the cylinder block 11 is supplied from a cooling water supply passage 11b provided at an end of the cylinder block 11 on the timing train side. It flows into the water jacket 13 through 11c. A spacer 14 is disposed inside the water jacket 13, and the thickness T2 of the cooling water inlet 14b of the spacer 14 facing the cooling water supply chamber 11c is smaller than the thickness T1 of the spacer main body 14a and has a diameter. Since it is biased inward in the direction, the cooling water is vertically divided along the radially outer surface of the cooling water inlet portion 14b and smoothly flows into the upper cooling water passage 13c and the lower cooling water passage 13d of the water jacket 13. .

  Although the cooling water flowing into the upper cooling water passage 13c and the lower cooling water passage 13d of the water jacket 13 tends to branch in the left-right direction, the flow is blocked by the partition wall 14d existing on the left side of the cooling water inlet portion 14b. The cooling water outlet portion 14c is turned to the right and flows substantially the entire length of the upper cooling water passage 13c and the lower cooling water passage 13d in the counterclockwise direction, and is located on the opposite side of the partition wall 14d when viewed from the cooling water inlet portion 14b. To the communication holes 15a of the cylinder head 15. When the cooling water flows through the water jacket 13, the upper cooling water passage 13c and the lower cooling water passage 13d are partitioned vertically by the spacer body 14a having a thickness T1 slightly smaller than the width W of the water jacket 13. The cooling water flowing through the upper cooling water passage 13c and the lower cooling water passage 13d is hardly mixed.

  When the cooling water flowing through the water jacket 13 is discharged to the water jacket (not shown) of the cylinder head 15 through the communication hole 15a that opens to the lower surface of the cylinder head 15, the cooling water flowing through the lower cooling water passage 13d is After passing through the cooling water outlet portion 14c of the spacer 14 from the bottom to the top and joining the cooling water flowing through the upper cooling water passage 13c, it flows into the communication holes 15a of the cylinder head 15.

  At this time, the thickness T3 of the cooling water outlet portion 14c is smaller than the thickness T1 of the spacer main body portion 14a, and the outer peripheral surface of the cooling water outlet portion 14c is flush with the outer peripheral surface of the spacer main body portion 14a. 13 is biased along the outer wall surface 13b, so that not only can the pressure loss of the cooling water passing upward through the cooling water outlet portion 14c be minimized, but also the cooling water flow rate is lowered and the cooling effect is reduced. Even in the vicinity of the cooling water outlet portion 14c where the temperature decreases, as much cooling water as possible can be interposed between the cooling water outlet portion 14c and the inner wall surface 13a of the water jacket 13 to ensure a cooling effect.

  In addition, since the cooling water that has exited the downstream end of the upper cooling water passage 13c merges with the cooling water that has exited the downstream end of the lower cooling water passage 13d and changed the flow direction upward, the cooling water from the upper cooling water passage 13c is cooled. The water can be deflected upward by the cooling water from the lower cooling water passage 13d and smoothly flown into the communication holes 15a.

  When the cooling water that has flowed through the upper cooling water passage 13c and the lower cooling water passage 13d changes its direction upward at the cooling water outlet portion 14c and is discharged from the communication hole 15a, a vortex is generated and the direction can be smoothly changed. Although there is a possibility that a part of the cooling water on the cooling water inlet 14b side passes through the gap δ (see FIG. 10) at the lower end of the partition wall 14d and flows into the cooling water outlet 14c side, It is possible to prevent the generation of the vortex and to allow the cooling water to smoothly flow into the communication holes 15a.

  Since the inner peripheral surface of the spacer main body 14a of the spacer 14 is close to the inner wall surface 13a of the intermediate portion of the water jacket 13 in the cylinder axis L2 direction, it is difficult for cooling water to come into contact with the inner wall surface 13a and cooling. It is suppressed. As a result, the cylinder bores 12a, 12a; 12a ', 12a' opposed to the spacer main body 14a have an intermediate portion in the direction of the cylinder axis L2 that is hotter than the other portions, and thermally expands to cause the pistons 18, 18; 18 ', Clearance between 18 'increases. As a result, particularly when a large side thrust is applied to the pistons 18, 18; 18 ', 18' in the compression stroke or the expansion stroke, the space between the pistons 18, 18; 18 ', 18' and the cylinder bores 12a, 12a; 12a ', 12a' This can reduce the friction and contribute to the improvement of the fuel consumption of the internal combustion engine. Also, the cylinder bores 12a, 12a; 12a ′, 12a ′ have higher temperatures in the cylinder axis L2 direction than the other parts, so that the oil that lubricates the parts rises in temperature and the viscosity decreases, reducing friction. The effect is further enhanced.

  On the other hand, the upper and lower portions of the cylinder bores 12a, 12a; 12a ′, 12a ′ in the cylinder axis L2 direction are sufficiently cooled by the cooling water flowing in the upper and lower upper cooling water passages 13c and the lower cooling water passage 13d of the spacer 14, The pistons 18, 18; 18 ′, 18 ′ slidably fitted in the cylinder bores 12 a, 12 a; 12 a ′, 12 a ′ are overheated by ensuring the cooling performance of the top portions 18 a. Can be prevented. Also, the upper portions of the cylinder bores 12a, 12a; 12a ', 12a' are not only directly subjected to the heat of the combustion chamber, but also the high temperature pistons 18, 18 that stay in the vicinity of the top dead center due to the change of the moving direction; Heat is easily transmitted from 18 ', 18' through the top ring 19 ..., the second ring 20 ..., and the oil ring 21 ... to reach a high temperature, but the spacer 14 is provided above the cylinder bores 12a, 12a; 12a ', 12a'. Cooling performance can be ensured by not exposing Further, the skirt portions 18b of the pistons 18, 18; 18 ', 18' are the places where the cylinder bores 12a, 12a; 12a ', 12a' are most slidably contacted to generate friction. Friction can be reduced by covering the cylinder bores 12a, 12a; 12a ', 12a' in contact with the spacers 14 and expanding the diameter by thermal expansion.

  As shown by the solid line in FIG. 5, when the side thrust of the pistons 18, 18; 18 ', 18' is maximized in the expansion stroke, that is, the pistons 18, 18; 18 ', 18' and the cylinder bores 12a, 12a; , 12a ', the vertical position of the spacer 14 is set so that the top ring 19 ..., the second ring 20 ..., and the oil ring 21 ... are located above the upper edge of the spacer body 14a. Therefore, the spacers 14 increase the inner diameters of the cylinder bores 12a, 12a; 12a ', 12a' to reduce the friction, while transferring the heat of the top portions 18a of the pistons 18, 18; Cylinder bore from top ring 19 with high heat, second ring 20 and oil ring 21 2a, 12a; 12a ', 12a' escape to the upper cooling water passage 13c of the water jacket 13 through the piston 18, 18; 18 ', 18' can be secured cooling performance.

  At this time, the spacer main body portion 14a of the spacer 14 is close to the inner wall surface 13a of the water jacket 13 via a minimum gap α, so that the spacer main body portion 14a and the inner wall surface 13a of the water jacket 13 are not in contact with each other. The amount of cooling water interposed therebetween can be minimized, and the cylinder bores 12a, 12a; 12a ', 12a' can be effectively warmed and expanded in diameter in the middle in the vertical direction.

  Further, at the bottom dead center position indicated by a chain line in FIG. 5, the moving speed of the pistons 18, 18; 18 ', 18' becomes low, so the pistons 18, 18; 18 ', 18' to the top ring 19 ..., the second ring 20 ... The amount of heat transferred to the cylinder bores 12a, 12a; 12a ', 12a' through the oil rings 21 ... increases, but the top ring 19, ..., the second ring 20, ..., and the oil ring 21 ... Since it is located below the lower edge, the heat of the pistons 18, 18; 18 ', 18' can be released to the cylinder bores 12a, 12a; 12a ', 12a' without being blocked by the spacer 14. The cooling performance of 18, 18; 18 ', 18' can be ensured.

  When the spacer 14 is assembled inside the water jacket 13, the gap α between the inner peripheral surface of the spacer main body portion 14 a and the inner wall surface 13 a of the water jacket 13 is equal to the outer peripheral surface of the spacer main body portion 14 a and the water jacket 13. It is set smaller than the gap β between the outer wall surface 13b. Therefore, even if the spacer 14 is biased in the radial direction due to an assembly error or deformation, and the inner peripheral surface of the spacer main body portion 14 a contacts the inner wall surface 13 a of the water jacket 13, the outer peripheral surface of the spacer main body portion 14 a is the water jacket 13. The outer wall surface 13b is not contacted.

  As described above, by ensuring a gap between the outer peripheral surface of the spacer main body portion 14a and the outer wall surface 13b of the water jacket 13, the following effects are exhibited. That is, if the outer peripheral surface of the spacer main body 14a is in contact with the outer wall surface 13b of the water jacket 13, contrary to the present embodiment, the lower support legs 14f and 14h of the spacer 14 are in contact with the bottom of the water jacket 13. Therefore, the striking sounds of the pistons 18, 18; 18 ', 18' are cylinder bores 12a, 12a; 12a ', 12a' → the bottom of the water jacket 13 → the lower support legs 14f, 14h of the spacer 14 → the spacer body 14a. → Propagated along the path of the outer wall surface 13b of the water jacket 13, causing noise. On the other hand, according to the present embodiment, the striking sound of the pistons 18, 18; 18 ', 18' propagates from the cylinder bores 12a, 12a; 12a ', 12a' to the spacer body 14a. Since it does not abut against the outer wall surface 13b of the jacket 13, the hitting sound is blocked there and the noise is reduced.

  If the spacer 14 is deformed by swelling or thermal expansion due to contact with cooling water, the inner peripheral surface of the spacer 14 may be tightly fitted to the inner wall surface 13a of the water jacket 13, but the spacer 14 may be fitted on the inner peripheral surface of the spacer main body 14a. Since the provided convex portions 14i are opposed to the inner wall surface 13a of the water jacket 13 so as to come into contact with each other, the inner peripheral surface of the spacer main body portion 14a and the inner wall surface 13a of the water jacket 13 are in close contact with each other. Can be prevented. When the convex portions 14i contact the inner wall surface 13a of the water jacket 13, the hitting sound may propagate through the convex portions 14i ..., but the hitting sound is far away from the cylinder row line L1 in the first place. Pistons 18, 18; 18 ', 18' are large on the outer peripheral surfaces of the intake side and the exhaust side, and hardly occur in the portion close to the cylinder row line L1 where the convex portions 14i are provided. The propagation of the hitting sound through 14i.

  Further, as shown in FIG. 2, the fixing members 22, 22 provided at both ends of the spacer 14 in the cylinder row line L1 direction elastically contact the inner wall surface 13a of the water jacket 13, so that the reaction forces F1, F1 The spacer 14 is extended in the direction of the cylinder row line L1. As a result, the side surfaces on the intake side and the exhaust side of the spacer main body portion 14a are deformed by receiving loads F2 and F2 in directions approaching each other, so that the inner peripheral surface of the spacer main body portion 14a becomes the inner wall surface 13a of the water jacket 13. , The gap α between the inner peripheral surface of the spacer main body 14a and the inner wall surface 13a of the water jacket 13 decreases. As a result, the amount of cooling water interposed between the spacer main body 14a and the inner wall surface 13a of the water jacket 13 is further reduced, and the intermediate portions in the vertical direction of the cylinder bores 12a, 12a; The diameter can be expanded by keeping warm.

  At this time, both the two fixing members 22 are disposed on the cylinder row line L1, and the intake side portion and the exhaust side portion of the spacer 14 are basically symmetrical with respect to the cylinder row line L1. The loads F2 and F2 that cause the intake side and exhaust side surfaces of the spacer body 14a to approach each other can be made equal, and the deformation amount of the intake side portion and the exhaust side portion of the spacer 14 can be made uniform.

  Moreover, the fixing members 22, 22 are attached to the spacer main body 14a so as not to reach the upper cooling water passage 13c and the lower cooling water passage 13d, so that the flow of the cooling water is not obstructed and the upper support legs 14e, Since it is attached to the spacer body 14a so as not to cover the 14g and the lower support legs 14f, 14h, the spacer body 14a can be efficiently deformed by the elastic force of the fixing members 22, 22.

  Now, since the end cylinder bore 12a faces only one intermediate cylinder bore 12a ', the intermediate cylinder bore 12a' faces one end cylinder bore 12a and one other intermediate cylinder bore 12a '. The intermediate cylinder bore 12a 'tends to be hotter than the end cylinder bore 12a. Further, when the cylinder bores 12a, 12a; 12a ', 12a' are expanded in diameter by thermal expansion, the cylinder bores 12a, 12a; There is a tendency to increase the diameter in a direction (intake / exhaust direction) orthogonal to the column line L1.

  Further, comparing the intake side and the exhaust side of the cylinder block 11, the cooling water flowing through the water jacket 13 enters from the intake side and is discharged from the exhaust side. Therefore, the temperature of the cooling water rises on the exhaust side on the downstream side. As the cooling effect decreases, the temperature of the cylinder block 11 becomes higher than that on the intake side. Moreover, since the high temperature exhaust gas passes through the exhaust side of the cylinder block 11, the temperature is higher than the intake side of the cylinder block through which the low temperature intake air passes. For this reason, the amount of expansion on the exhaust side of the intermediate cylinder bores 12a 'and 12a' is larger than that of the other portions, and the gap ε 'between the intermediate pistons 18' and 18 'becomes excessive in that portion. Thus, there is a problem that the oil on the crankcase side escapes to the combustion chamber side and the oil consumption increases.

  However, in the present embodiment, the diameter of the intermediate pistons 18 ', 18' on the exhaust side is larger than that of the end pistons 18, 18, so that the intermediate cylinder bores 12a ', 12a' and the intermediate pistons 18 ', 18' Since the cold clearance ε ′ on the exhaust side of the cylinder is set to be smaller than the cold clearance ε of other portions, the exhaust side of the intermediate cylinder bores 12a ′ and 12a ′ is more than the other portions for the reasons described above. Even if the thermal expansion is large, it is possible to prevent the gap ε ′ from excessively expanding and increasing the oil consumption.

  Next, a second embodiment of the present invention will be described with reference to FIG.

  In the first embodiment, the end pistons 18 and 18 and the intermediate pistons 18 'and 18' are made different in diameter to adjust the gaps ε and ε '. In the second embodiment, four pistons are used. 18, 18; 18 'and 18' have the same shape, and the diameters of the end cylinder bores 12a and 12a and the intermediate cylinder bores 12a 'and 12a' are made different to adjust the gaps ε and ε '. That is, on the exhaust side of the cylinder block 11 that is at a high temperature, the diameters of the intermediate cylinder bores 12a 'and 12a' when cold are set smaller than the diameters of the end cylinder bores 12a and 12a, so that the end cylinder bores 12a and 12a and The clearance ε ′ between the intermediate cylinder bores 12a ′, 12a ′ and the intermediate pistons 18 ′, 18 ′ is made smaller than the clearance ε between the end pistons 18, 18.

  As a result, even if the intermediate cylinder bores 12a 'and 12a' that are hot when hot are expanded more than the end cylinder bores 12a and 12a that are cold, the intermediate cylinder bores 12a 'and 12a' and the intermediate pistons 18 'and 18' It is possible to prevent the oil consumption from increasing due to excessive expansion of the gap ε ′.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, although an in-line four-cylinder internal combustion engine is exemplified in the embodiment, the present invention can be applied to an arbitrary type of internal combustion engine having three or more cylinders in which three or more cylinder bores 12a and 12a 'are juxtaposed.

  In the embodiment, the clearance ε ′ between the intermediate cylinder bore 12a ′ and the intermediate piston 18 ′ on the exhaust side of the cylinder block 11 is adjusted. However, the clearance ε ′ on the intake side or both the exhaust side and the intake side is adjusted. The gap ε ′ may be adjusted.

  In the present invention, the clearance ε ′ between the intermediate cylinder bore 12a ′ and the intermediate piston 18 ′ includes the clearance ε ′ between the piston rings of the intermediate cylinder bore 12a ′ and the intermediate piston 18 ′. That is, as shown in FIG. 15 as the third embodiment, the end piston 18 and the intermediate piston 18 ′ have the same shape, and the piston ring of the end piston 18 and the piston ring of the intermediate piston 18 ′ have different shapes ( The gap ε ′ may be adjusted by changing the diameter).

  The present invention also relates to an internal combustion engine that bifurcates the coolant supplied from one end side of the cylinder row line L1 into an intake side surface and an exhaust side surface and collects and discharges the coolant at the other end side of the cylinder row line L1. Can be applied.

11 Cylinder block 12a End cylinder bore (cylinder bore)
12a 'Intermediate cylinder bore (cylinder bore)
13 Water jacket 14 Spacer 18 End piston 18 'Intermediate piston L1 Cylinder row ε Clearance between end cylinder bore and end piston ε' Clearance between intermediate cylinder bore and intermediate piston

Claims (3)

A spacer (13) is formed inside a water jacket (13) formed so as to surround the periphery of three or more cylinder bores (12a, 12a ') juxtaposed on the cylinder row (L1) of the cylinder block (11) of the internal combustion engine. 14), and the cooling structure of the internal combustion engine for adjusting the cooling state of the cylinder bores (12a, 12a ′) by regulating the flow of the cooling water in the water jacket (13) with the spacer (14).
End pistons (18) are slidably fitted to end cylinder bores (12a) located at both ends of the cylinder row line (L1), and intermediate cylinder bores (12a ′) excluding the end cylinder bores (12a). ) Is slidably fitted with an intermediate piston (18 ')
A clearance (ε ′) between the intermediate cylinder bore (12a ′) and the intermediate piston (18 ′) in a cross section orthogonal to the cylinder row line (L1) is defined by the end cylinder bore in the cross section orthogonal to the cylinder row line (L1). A cooling structure for an internal combustion engine, wherein the cooling structure is set to be smaller than a gap (ε) between (12a) and the end piston (18). The water jacket (13) has one side surface of the cylinder row (L1) on the upstream side in the flow direction of the cooling water and the other side surface on the downstream side in the flow direction of the cooling water,
In a cross section orthogonal to the cylinder row line (L1), a gap (ε ′) between the intermediate cylinder bore (12a ′) facing the downstream side and the intermediate piston (18 ′) is formed in the intermediate cylinder bore ( 12. The cooling structure for an internal combustion engine according to claim 1, wherein the cooling structure is set to be smaller than a clearance between the intermediate piston (18 ′) and the intermediate piston (18 ′).   In the cross section perpendicular to the cylinder row line (L1), the gap (ε ′) between the intermediate cylinder bore (12a ′) and the intermediate piston (18 ′) facing the exhaust side surface of the cylinder block (11) is 2. The internal combustion engine according to claim 1, wherein the internal combustion engine is set to be smaller than a clearance between the intermediate cylinder bore (12 a ′) facing the intake side surface of the cylinder block (11) and the intermediate piston (18 ′). Cooling structure.

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