JP5064473B2 - Internal combustion engine cooling structure - Google Patents

Description

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

  Six spacers for suppressing the flow of cooling water are arranged inside the water jacket surrounding the three cylinder bores arranged in series, and the upper support legs and the lower support legs from the spacer main body of each spacer. Patent Document 1 below discloses that a support leg portion is protruded up and down and the spacer is positioned in the water jacket by the support leg in the vertical direction.

Japanese Patent No. 4149322

  By the way, in the above conventional one, the position where the six spacers are arranged is the position farthest from the cylinder row in the water jacket to the intake side and the exhaust side. The cross-sectional area of the water jacket where the spacer is mounted is reduced by the support legs with respect to the cross-sectional area, and the flow of cooling water around the support legs is obstructed, resulting in a problem that the cooling performance is lowered.

  In particular, at the positions on the intake side and exhaust side with respect to the cylinder row line, the temperature of the cylinder bore tends to be higher than the positions at both ends in the cylinder row line direction. If the flow of the cooling water is hindered, the temperature of each cylinder bore may become non-uniform.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to uniformize the temperature difference between the cylinder bores at both ends in the cylinder row line direction and the other cylinder bores using spacers.

To achieve the above object, according to the first aspect of the present invention, a water jacket formed so as to surround a plurality of cylinder bores juxtaposed on a cylinder row line of a cylinder block of an internal combustion engine is provided inside the water jacket. A cooling structure for an internal combustion engine in which a spacer is mounted and the cooling water flow in the water jacket is regulated by the spacer to adjust the cooling state of the cylinder bore. The spacer extends around the cylinder bore over the entire circumference. is formed integrally to surround the spacer main body part for regulating the flow of cooling water in the water jacket, and the upper support legs extending upward direction from the upper surface of the spacer main body part, downward from the lower surface of the spacer main body part and a lower support leg extending, the spacer main body part, the plurality of Shirindabo in a direction orthogonal to the cylinder row line An intake-side side and exhaust-side side curved along, and a cylinder row line direction end portion connecting the intake side side and exhaust-side side, the upper support legs and the lower support legs , said respectively curved in an arc shape along the inner wall surface or outer wall surface of the water jacket, while being arranged in the cylinder row line direction end portion, is its upper support leg and a lower support leg, the axis of the cylinder bore A cooling structure for an internal combustion engine is proposed, which is located on the same straight line parallel to.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the upper support leg and the lower support leg are arranged only at the ends in the cylinder row line direction. Is proposed.

According to a third aspect of the invention, in addition to the configuration of the first or second aspect, the upper support leg and the lower support leg are formed with a width in the circumferential direction of the cylinder bore. A structure is proposed.

According to the invention described in claim 4, in addition to the configuration of claim 1 or claim 3, wherein the upper support legs and the lower support legs of the cylinder row line Direction of the one end is the the water A cooling structure for an internal combustion engine that is biased toward the inner wall surface of the jacket is proposed.

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. Spacer includes a spacer main body part spacer main body part for regulating the flow of cooling water in the water jacket, and the upper support legs extending upward direction from the upper surface of the spacer main body part, lower support extending downwardly from the lower surface of the spacer main body part and a leg, so that the upper support legs and the lower support legs are arranged in easily cylinder row line direction end portion temperature becomes a low temperature relatively cylinder bores, some inhibition flow of the cooling water by their supporting legs Even if the cooling effect is lowered, the influence of the cylinder bore can be prevented from becoming uneven by minimizing the influence.

Further, since the upper support leg and the lower support leg are curved in an arc shape along the inner wall surface or the outer wall surface of the water jacket, the flow of the cooling water in the water jacket can be rectified by the support legs.

According to the fourth aspect of the present invention, since the upper support leg and the lower support leg are arranged biased toward the inner wall surface side of the water jacket, it is difficult for cooling water to intervene between the support leg and the inner wall surface of the water jacket. Become. As a result, it is possible to prevent the cylinder bores arranged at one end in the cylinder row line direction, which are likely to be relatively low in temperature, from being excessively cooled, and to more effectively suppress the temperature of each cylinder bore from becoming uneven.

The perspective view of the cylinder block of an in-line 4 cylinder internal combustion engine. The perspective view of a spacer. FIG. 3 is a three-direction arrow view of FIG. 1. FIG. 4 is a four-direction arrow view of FIG. 3. FIG. 5 is a sectional view taken along line 5-5 of FIG. FIG. 6 is an enlarged view of 6 parts in FIG. 5. FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. 3. FIG. 8 is a cross-sectional view taken along line 8-8 in FIG. 3. FIG. 9 is a sectional view taken along line 9-9 in FIG. 3. FIG. 10 is a sectional view taken along line 10-10 in FIG. 3; 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). 12-12 sectional view (FIG. 12A), BB sectional view of FIG. 12A (FIG. 12B), and CC sectional view of FIG. 12B. FIG. 12 (C).

  Hereinafter, embodiments 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, so that the four cylinder bores 12 a. Surrounded all around.

As shown in FIGS. 2 and 3, the spacer main body 14a includes an intake side portion 14in and an exhaust side portion 14ex that are curved along the plurality of cylinder bores 12a in a direction orthogonal to the cylinder row line L1, and The cylinder side line (L1) direction end part which connects the intake side part 14in and the exhaust side part 14ex is provided.

The cooling water inlet portion 14b surrounds the intake side of one cylinder bore 12a located on one end side (timing train side) in the cylinder row line L1 direction, and the cooling water outlet portion 14c is one end in the cylinder row line L1 direction of the cylinder bore 12a. Enclose the side and 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.

  In the water jacket 13, an upper cooling water passage 13c is formed between the upper edge of the spacer body 14a and the lower surface of the cylinder head 15 so as to surround the four cylinder bores 12a. A lower cooling water passage 13d surrounding the periphery of the four cylinder bores 12a is formed between the lower edge of 14a and the bottom of the water jacket 13.

  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.

The support legs 14e, 14f, 14g, and 14h are curved in an arc shape along the inner wall surface 13a or the outer wall surface 13b of the water jacket 13, excluding the intake side portion 14in and the exhaust side portion 14ex. It arrange | positions at the cylinder row line L1 direction edge part . Moreover, the upper support legs 14e and 14g and the lower support legs 14f and 14h are located on the same straight line parallel to the axis of the cylinder bore 12a.
A piston 18 connected to the crankshaft 17 is slidably fitted to each cylinder bore 12a. A top ring 19, a second ring 20 and an oil ring 21 are mounted on the top 18a side of the piston 18.

  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 piston 18 moves up and down in the cylinder bore 12a as the crankshaft 17 rotates, the side thrust acting between the piston 18 and the cylinder bore 12a changes periodically, and the expansion shown by the solid line The side thrust becomes maximum at the position of the piston 18 in the stroke (for example, the position at a crank angle of 15 ° after the compression top dead center). At the position where the side thrust is maximized, the top ring 19, the second ring 20 and the oil ring 21 of the piston 18 are located above the upper edge of the spacer 14, and the skirt portion 18 b of the piston 18 is the upper edge of the spacer 14. The vertical position of the spacer 14 in the water jacket 13 is set so as to be positioned below the water jacket 13. Further, the spacer 14 in the water jacket 13 is positioned so that the top ring 19, the second ring 20, and the oil ring 21 of the piston 18 are located below the lower edge of the spacer 14 at the bottom dead center position of the piston 18 indicated by a chain line. The vertical position of is set.

  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 jacket 13 and the outer wall surface 13b. The gap α is smaller than the gap β, that is, the spacer body 14a is closer to the inner wall surface 13a than the outer wall surface 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. Fixing member 22 is mounted within the vertical height of the spacer main body part 14a, the outer peripheral surface thereof is exposed to the inner peripheral surface of the spacer 14, the exposed inner peripheral surface thereof to the inner peripheral surface of the scan pacer 14 Then, it elastically contacts the inner wall surface 13a of the water jacket 13. A part of the slit 14 o exposed to the lower support leg 14 h 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.

  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 13 is opened so as to surround the outer periphery of the cylinder bores 12a of the four cylinder sleeves 12 exposed on the deck surface 11a. A 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 ends of the lower protrusions 14k of the partition wall 14d contact the bottom of the water jacket 13, and the upper ends of the upper support legs 14e and 14g and the partition wall 14d. The upper end of the upper protrusion 14j contacts the lower surface of the gasket 16, so that 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 upper projection 14j of the partition wall 14d may damage the lower surface of the gasket 16. However, the two fixing members 22 and 22 provided at both ends in the cylinder row line L1 direction fix the spacer 14 so as to be immovable with respect to the water jacket 13, thereby preventing the gasket 16 from being damaged due to the loose movement of the spacer 14. be able to.

  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 inhibited. 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. .

  Moreover, since the part located in the outermost side of the cylinder row line L1 among the four cylinder bores 12a is difficult to receive heat from the other cylinder bores 12a, the temperature of that part is relatively low. On the other hand, among the four cylinder bores 12a..., The portions located on the intake side and the exhaust side of the cylinder row L1 are likely to receive heat from the adjacent cylinder bores 12a. In the present embodiment, the upper support legs 14e and 14g and the lower support legs 14f and 14h are provided at the outermost position in the direction of the cylinder row L1 where the temperature of the cylinder bores 12a is relatively low. Even if the cooling water flow in the water jacket 13 is somewhat obstructed by the upper support legs 14e, 14g and the lower support legs 14f, 14h, the temperature of the cylinder bores 12a can be made uniform with the effect minimized. .

  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 14h, the cooling water hardly comes into contact with the inner wall surface 13a of the water jacket 13, and the relatively low-temperature cylinder bores 12a can be kept warm, whereby the temperatures of the cylinder bores 12a 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 intermediate portion in the cylinder axis L2 direction of the cylinder bore 12a facing the spacer main body portion 14a becomes hotter than the other portions, and is thermally expanded to increase the clearance with the piston 18. As a result, particularly when a large side thrust is applied to the piston 18 in the compression stroke or the expansion stroke, it is possible to reduce the friction between the piston 18 and the cylinder bore 12a, thereby contributing to an improvement in fuel consumption of the internal combustion engine. Further, when the intermediate portion of the cylinder bore 12a in the cylinder axis L2 direction becomes higher in temperature than the other portions, the oil that lubricates the portions rises in temperature and the viscosity decreases, so that the effect of reducing friction is further enhanced.

  On the other hand, the upper and lower portions of the cylinder bore 12a in the cylinder axis L2 direction are sufficiently cooled by the cooling water flowing through the upper and lower upper cooling water passages 13c and the lower cooling water passage 13d of the spacer 14, and are thus slidably fitted into the cylinder bore 12a. The cooling performance of the top portion 18a and the skirt portion 18b of the piston 18 that is likely to become high temperature can be ensured to prevent overheating. The upper part of the cylinder bore 12a not only receives the heat of the combustion chamber directly, but also changes the moving direction, so that it takes longer time to stay in the vicinity of the top dead center to the top ring 19, the second ring 20, and the oil ring. Although heat is easily transmitted through 21 and the temperature tends to be high, the cooling performance can be ensured by preventing the spacer 14 from facing the upper portion of the cylinder bore 12a. Furthermore, the skirt portion 18b of the piston 18 is a place where the cylinder bore 12a is slidably contacted with the cylinder bore 12a to generate friction. The cylinder bore 12a slidably contacted with the skirt portion 18b is covered with the spacer 14 and expanded by thermal expansion. Friction can be reduced.

  As shown by the solid line in FIG. 5, when the side thrust of the piston 18 is maximized in the expansion stroke, that is, when the friction between the piston 18 and the cylinder bore 12a is maximized, the top ring 19, the second ring 20 and the oil ring 21 are Since the upper and lower positions of the spacer 14 are set so as to be positioned above the upper edge of the spacer main body 14a, the spacer 14 increases the inner diameter of the cylinder bore 12a to reduce the friction, and the piston 18 that becomes high temperature is decreased. The heat of the top portion 18a is released from the top ring 19, the second ring 20, and the oil ring 21 having high heat conductivity to the upper cooling water passage 13c of the water jacket 13 through the cylinder bore 12a, and the cooling performance of the piston 18 can be ensured.

  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 intervening cooling water can be minimized, and the intermediate portion in the vertical direction of the cylinder bore 12a can be effectively warmed and expanded in diameter.

  Further, since the moving speed of the piston 18 is low at the bottom dead center position indicated by a chain line in FIG. 5, the amount of heat transferred from the piston 18 to the cylinder bore 12a through the top ring 19, the second ring 20 and the oil ring 21 increases. Since the top ring 19, the second ring 20, and the oil ring 21 are located below the lower edge of the spacer body 14a at the dead center position, the heat of the piston 18 can be released to the cylinder bore 12a without being blocked by the spacer 14. Thus, the cooling performance of the piston 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 sound of the piston 18 propagates along the path of the cylinder bore 12a → the bottom of the water jacket 13 → the lower support legs 14f and 14h of the spacer 14 → the spacer main body 14a → the outer wall surface 13b of the water jacket 13 to generate noise. It becomes a cause. On the other hand, according to the present embodiment, the striking sound of the piston 18 propagates from the cylinder bore 12a to the spacer main body 14a, but the spacer main body 14a does not come into contact with the outer wall surface 13b of the water jacket 13, and therefore strikes there. Sound is cut off and 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. It is generated largely on the outer peripheral surface of the piston 18 on the intake side and exhaust side, and hardly occurs in the portion close to the cylinder row line L1 where the projections 14i are provided. Propagation is virtually never a problem.

  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 body 14a and the inner wall surface 13a of the water jacket 13 can be further reduced, and the intermediate portion in the vertical direction of the cylinder bore 12a can be more effectively kept warm and expanded in diameter. it can.

  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.

  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 an arbitrary number of cylinders.

  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.

  In the embodiment, both the upper support legs 14e and 14g and the lower support legs 14f and 14h are provided, but the upper support legs 14e and 14g are not necessarily provided.

  In the embodiment, the upper support legs 14e and 14g and the lower support legs 14f and 14h of the spacer 14 are provided at both ends in the cylinder row line L1 direction, but may be provided only at one end portion in the cylinder row line L1 direction. .

11 Cylinder block 12a Cylinder bore 13 Water jacket 13a Inner wall surface 13b Outer wall surface 13c Upper cooling water passage 13d Lower cooling water passage 14 Spacer 14a Spacer main body portion 14e Upper support leg (support leg)
14f Lower support leg (support leg)
14g Upper support leg (support leg)
14h Lower support leg (support leg)
L1 Cylinder row line

Claims (4)

A spacer (14) is mounted inside a water jacket (13) formed so as to surround a plurality of cylinder bores (12a) juxtaposed on a cylinder row line (L1) of a cylinder block (11) of the internal combustion engine. In the internal combustion engine cooling structure in which the spacer (14) regulates the flow of the cooling water in the water jacket (13) to adjust the cooling state of the cylinder bore (12a).
The spacer (14) is integrally formed so as to surround the entire circumference of the cylinder bore (12a), and a spacer main body (14a) for restricting the flow of cooling water in the water jacket (13). with the, the spacer main body part (14a) upper surface upper support legs extending upward direction from (14e, 14 g) with a lower support leg (14f, 14h) extending downward from the lower surface of the spacer main body part (14a) and ,
The spacer body portion (14a) includes an intake side portion (14in) and an exhaust side portion (14ex) that are curved along the cylinder bores (12a) in a direction orthogonal to the cylinder row line (L1). A cylinder row line (L1) direction end portion connecting the intake side portion (14in) and the exhaust side portion (14ex);
The upper support legs (14e, 14g) and the lower support legs (14f , 14h) are respectively curved in an arc shape along the inner wall surface (13a) or the outer wall surface (13b) of the water jacket (13). the cylinder row line (L1) while being arranged in the axial end, the upper support legs (14e, 14 g) and the lower support legs (14f, 14h) and has, parallel to the same straight with the axis of the cylinder bore (12a) A cooling structure for an internal combustion engine, wherein the cooling structure is located on a line . 2. The internal combustion engine according to claim 1, wherein the upper support legs ( 14 e, 14 g) and the lower support legs (14 f , 14 h) are arranged only at the ends in the cylinder row line (L 1) direction. Cooling structure. The internal combustion engine according to claim 1 or 2, wherein the upper support leg (14e, 14g) and the lower support leg (14f , 14h) are formed with a width in the circumferential direction of the cylinder bore (12a). Engine cooling structure. The upper support leg (14g ) and the lower support leg ( 14h) at one end in the direction of the cylinder row (L1) are biased toward the inner wall surface (13a) side of the water jacket (13). The cooling structure for an internal combustion engine according to claim 1, 2, or 3.

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