JP2008082293A - Cooling structure of cylinder block - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling structure of a cylinder block capable of appropriately suppressing deflected temperature rising around a bore through correction of a temperature gradient generated in a cylinder. <P>SOLUTION: The cylinder block 1 is divided into a cylinder liner 2 constituting a wall surface of the cylinder and a cylinder block body 3 forming an outer wall of a water jacket by using, as a border, a part becoming the water jacket being a passage of cooling water, and the cylinder 21 is cooled by the cooling water flowing through the water jacket. On a circumferential surface 23 of a cylinder connection body 20 in the cylinder liner 2, a fin group 24 projecting on a part becoming the water jacket is formed in a form where the higher the temperature of the cylinder 21 is set, the more the contact area of the water jacket to the cooling water increases. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cylinder block cooling structure for cooling a cylinder block of an engine through a water jacket.

  As is well known, a water jacket is provided in a cylinder block of an engine so as to surround a group of cylinders, and cooling water is circulated in the water jacket to cool the cylinders. In general, in the cylinder block, a temperature gradient is generated in the vicinity of the combustion chamber located in the upper part of the cylinder and relatively low in the lower part far from the combustion chamber. Therefore, conventionally, it has been studied to correct the temperature gradient of each part of the cylinder by appropriately changing the properties of the water jacket.

For example, the cylinder block described in Patent Document 1 adopts a structure in which a cylinder liner portion that is formed on the cylinder side wall surface and a cylinder liner wall portion that is positioned inside the water jacket and a cylinder outer wall portion that surrounds the outer periphery of the water jacket are separately formed. In this manner, the properties of the water jacket are changed. That is, the cylinder outer wall portion is formed such that the lower portion of the inner peripheral surface constituting the outer wall of the water jacket is closer to the cylinder liner portion than the upper portion. Due to this structure as a cylinder block, the upper width of the water jacket itself and the high temperature cylinder is wider than the lower width, so the flow rate of cooling water flowing in the water jacket is higher on the upper side. Thus, the vicinity of the combustion chamber of the cylinder that becomes high temperature can be cooled more efficiently. In other words, the temperature gradient of each part of the cylinder can be corrected.
JP 2005-155600 A

  Due to the cooling structure as the cylinder block, the temperature gradient of each part of the cylinder is surely corrected as compared with the case where the water jacket is formed with the same width in the axial direction of the cylinder. However, although the combustion is always repeated in the vicinity of the combustion chamber of the cylinder, the actual temperature gradient in each part of the cylinder is extremely high, for example, cooling from the middle to the lower part of the cylinder is also performed by the lubricating oil. Therefore, even when the above cooling structure is adopted, such a temperature gradient is not always corrected sufficiently.

  On the other hand, in a multi-cylinder engine, normally, the water jacket is not formed between the cylinder bores arranged in series, and the combustion heat acts between the adjacent bores. Therefore, FIG. 9 shows the temperature distribution corresponding to the planar structure of the cylinder block, and FIG. 10 shows the relationship between the distance from the upper surface of the bore along the lines AA and BB in FIG. As illustrated, the temperature between the cylinder bores sandwiched between adjacent cylinders is particularly high, and the temperature tends to gradually decrease as the distance from these parts increases. That is, in the case of the temperature gradient of each part of the cylinder, it is actually necessary to be aware of such a three-dimensional gradient including the temperature distribution in the planar direction. And of course, such a three-dimensional temperature gradient is difficult to correct with the conventional cooling structure.

If correction of the temperature gradient at each part of the cylinder is insufficient,
・ It is difficult to maintain the roundness due to a local rise in the temperature around the bore, and as a result, between the oil ring and the cylinder bore (cylinder liner) provided on the outer periphery of the piston that reciprocates in the cylinder. There may be gaps.
When such a gap occurs, the lubricating oil enters the combustion chamber through the gap and is burned in the combustion chamber, and the lubricating oil is consumed wastefully.
To prevent such a situation, if the pressing force of the oil ring is set in a manner that can prevent the occurrence of the gap, the friction between the oil ring and the cylinder bore (cylinder liner) in the portion below the middle portion of the cylinder Will increase and fuel consumption will deteriorate.
On the other hand, the increase in the temperature around the bore also causes a decrease in the strength of the material forming the cylinder block, and as a result, the reliability as the cylinder block also decreases.
Inconveniences and so on can also be invited.

  The present invention has been made in view of such points, and an object of the present invention is to provide a cooling structure for a cylinder block that can suitably suppress an uneven temperature rise around the bore through correction of a temperature gradient generated in the cylinder. Is to provide.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
According to the first aspect of the present invention, the first structure constituting the wall surface of the cylinder and the outer wall of the water jacket are formed on the boundary of the portion that becomes the water jacket which is the flow path of the cooling water of the cylinder block. 2 is a cylinder block cooling structure that cools the cylinder with cooling water flowing through the water jacket, and the outer peripheral surface of the first structure receives a large amount of heat received by the cylinder. The gist of the present invention is that a heat dissipation mechanism that protrudes from the portion that becomes the water jacket is provided in such a manner that the contact area with the cooling water increases as the portion becomes.

  As described above, in the cylinder of the cylinder block, the upper side in the vicinity of the combustion chamber is higher in the axial direction of the cylinder, and the temperature is higher as it approaches between the cylinder bores sandwiched between the cylinders in the cylinder arrangement direction. A temperature gradient is generated. In this regard, according to the same configuration in which the heat dissipation mechanism is provided in the above-described aspect, a portion where the heat received by the cylinder increases, that is, a portion where the temperature of the cylinder increases, a larger amount of heat radiation to the cooling water is secured. Therefore, it is possible to correct the temperature gradient generated in the cylinder with a high degree of freedom according to the arrangement of the heat dissipation mechanism. As a result, an uneven temperature increase around the cylinder bore is naturally suppressed, so that cylinder bore deformation and the like are also preferably suppressed.

  The invention according to claim 2 is the cooling structure of the cylinder block according to claim 1, wherein the heat dissipation mechanism has a gradually increasing contact area with the cooling water from a lower portion of the cylinder to an upper portion that becomes a combustion chamber of the cylinder. The gist is to include a portion formed so as to be large and a portion formed so that a contact area with the cooling water gradually increases as approaching a connecting portion of cylinders adjacent to each other.

  According to such a configuration, at least with respect to the temperature gradient in the axial direction of the cylinder, the contact area with the cooling water gradually increases from the lower part of the cylinder of the heat dissipation mechanism to the upper part of the cylinder as the combustion chamber. The correction can be made by the formed part. In addition, at least the temperature gradient in the plane direction of the cylinder can be corrected by a portion formed so that the contact area with the cooling water gradually increases as it approaches the connecting portion of the adjacent cylinders of the heat dissipation mechanism. It becomes. That is, specifically, the three-dimensional temperature gradient correction can be easily realized through such a structure of the heat dissipation mechanism.

  According to a third aspect of the present invention, in the cylinder block cooling structure according to the first or second aspect, the first structure is formed by integrally forming a portion constituting the wall surface of the cylinder and the heat dissipation mechanism. This is the gist.

  In this case, the first structure can be processed by a casting technique using a mold in which, for example, a portion constituting the wall surface of the cylinder and the heat dissipation mechanism can be integrally formed. That is, by providing the heat dissipation mechanism, the workability of the first structure, which must have a complicated shape, is maintained, and the productivity as a cylinder block is also maintained high.

  According to a fourth aspect of the present invention, in the cylinder block cooling structure according to the first or second aspect of the present invention, the first structure includes a portion constituting the wall surface of the cylinder and the heat dissipation mechanism as separate members. The gist is that they are combined together.

  In this case, since the heat dissipation mechanism can be made of a different material with respect to the portion constituting the wall surface of the cylinder constituting the first structure, the number of processes is increased, but the heat dissipation mechanism has high thermal conductivity. By appropriately selecting and using the material, it is possible to accurately expand the heat dissipation efficiency to the cooling water. Moreover, it becomes possible to attach a heat dissipation mechanism having an arbitrary shape to the portion constituting the wall surface of the cylinder, and the degree of freedom in selecting the shape as the heat dissipation mechanism can be increased.

  A fifth aspect of the present invention is the cylinder block cooling structure according to any one of the first to fourth aspects, wherein the heat dissipation mechanism is a portion that becomes the water jacket from an outer peripheral surface of the first structure. It consists of a plurality of fins protruding in the gist.

As described above, by configuring the heat dissipating mechanism as a plurality of fins, the inventions according to the first to fourth aspects can be easily realized.
In this case, for example, according to the invention described in claim 6, the plurality of fins are formed in such a manner that the protruding length of the fins becomes longer as the heat receiving portion of the cylinder increases, or According to the invention described in item 7, the structure formed in such a manner that the distance between the adjacent fins becomes shorter as the portion of the cylinder that receives more heat, the combination thereof, and the like are particularly effective. In any of these structures, the contact area of the fins with the cooling water can be easily expanded as the heat receiving area of the cylinder increases. Therefore, it is possible to easily correct the temperature gradient generated in the cylinder in the above mode. Will be able to.

  The invention according to claim 8 is the cylinder block cooling structure according to any one of claims 1 to 7, wherein at least one of the first structure and the second structure is: The gist is that the lower surface is formed in a shape that is closer to the other structure than the upper portion on the surface facing the portion that becomes the water jacket.

  With such a structure, the width of the upper portion of the water jacket itself is wider than the width of the lower portion, so that the flow rate of the cooling water flowing in the water jacket is larger on the upper side. That is, it is possible to cool the vicinity of the combustion chamber of the cylinder more reliably by the cooperation of such a water jacket and the heat dissipation mechanism, and thus more reliably correct the temperature gradient generated in the cylinder. Will be able to.

On the other hand, for example, the following combinations are possible for the first structure and the second structure constituting the cylinder block.
That is, for example, according to the invention described in claim 9, the first structure is composed of a cylinder liner having a flange portion at an upper portion, and the second structure is disposed on the upper surface of the cylinder liner. It shall consist of a cylinder block main body which has a mounting surface in which a flange part is mounted. In this case, the cylinder block has a divided structure of a cylinder liner constituting the cylinder side of the water jacket and a cylinder block body constituting the outer wall of the water jacket. Then, the water jacket is defined by fitting the cylinder liner into the cylinder block body so that the flange portion provided at the upper portion of the cylinder liner is in contact with and supported by the mounting surface provided at the upper portion of the outer wall of the cylinder block. In addition to being formed, the heat dissipation mechanism is provided in the above-described manner on the outer peripheral surface of the cylinder liner.

  Alternatively, as in the invention according to claim 10, the first structure is composed of a cylinder block body having a surface projecting around the lower side of the cylinder, and the second structure is The cylinder block main body comprises a cylinder block outer wall on which a bottom surface is placed on the protruding surface. In this case, the cylinder block has a divided structure of a cylinder block main body having a surface protruding around the lower side of the cylinder and a cylinder block outer wall on which a bottom surface is placed on the protruding surface of the cylinder block main body. Become. And, by placing the cylinder block outer wall on the surface of the cylinder block body that protrudes around the lower part of the cylinder, a water jacket is defined between them, and with respect to the outer peripheral surface of the cylinder block body, A heat dissipation mechanism will be provided in the said aspect.

(First embodiment)
Hereinafter, a first embodiment in which a cylinder block cooling structure according to the present invention is embodied will be described with reference to the drawings. In the present embodiment, a case where the cooling structure according to the present invention is applied to a cylinder block used in an in-line four-cylinder engine in which four cylinders are arranged in series will be described as an example.

  FIG. 1 shows an exploded perspective structure of a cylinder block 1 to which the cooling structure of the present embodiment is applied. As shown in the figure, the cylinder block 1 is divided into a cylinder liner 2 that forms the wall surface of the cylinder and a cylinder block body 3 that forms the outer wall of the water jacket, with a water jacket portion as a boundary. It is said that. That is, the cylinder block 1 is formed by fitting the cylinder liner 2 into the cylinder block body 3. Here, in the present embodiment, the cylinder liner 2 constitutes the first structure, and the cylinder block body 3 constitutes the second structure.

  Among these, the cylinder liner 2 constituting the first structure includes a cylinder coupling body 20 in which a plurality of cylinders 21 are integrally coupled, and a substantially flat flange portion provided at an upper end portion of the cylinder coupling body 20. 22 is integrally formed.

  Here, the flange portion 22 constitutes an upper deck on which the cylinder head is placed when the cylinder block 1 is assembled with the cylinder head. In other words, the cylinder block 1 is configured as a closed deck structure cylinder block by the flange portion 22.

  Further, in the present embodiment, the outer peripheral surface 23 of the cylinder connecting body 20 is a plurality of sheets (here, projecting toward a portion that becomes a water jacket and formed in a substantially annular flat plate shape surrounding the cylinder connecting body 20) In the example, the first to seventh (seventh to seventh) fins 24 a to 24 g are provided in order from the upper part to the lower part of the outer peripheral surface 23. And the heat dissipation mechanism is comprised by the fin group 24 comprised by these fins 24a-24g.

  The cylinder liner 2 is made of an aluminum alloy, a magnesium alloy, or the like in order to reduce the weight of the engine, and uses a mold in which a portion constituting the wall surface of the cylinder 21 and the fin group 24 can be integrally formed. It is cast by die casting method. In consideration of wear due to the piston, a protective film such as iron is coated on the inner peripheral surface of the cylinder 21 by thermal spraying or the like.

  On the other hand, the cylinder block body 3 constituting the second structure is integrally formed with a crankcase portion 31 and a cylinder block outer wall portion 30 that protrudes upward from the upper end surface 32 thereof. A flange is provided at the upper end of the cylinder block outer wall 30 so as to protrude to the outer peripheral side, and the upper surface of this flange is a mounting surface 33 on which the flange 22 of the cylinder liner 2 is mounted. .

  Here, the inner peripheral surface 34 of the cylinder block outer wall portion 30 is formed in a substantially annular shape so as to oppose the outer peripheral surface 23 of the cylinder coupling body 20, and a stepped portion 35 is provided at a substantially intermediate portion in the vertical direction. It has been. The lower inner peripheral surface 34a below the step portion 35 of the inner peripheral surface 34 has a shape in which the outer peripheral surface 23 of the cylinder coupling body 20 is fitted, and the upper inner periphery above the step portion 35. The surface 34b is formed in a shape facing the outer peripheral surface 23 of the cylinder coupling body 20 with a predetermined distance from each other so as to form the inner wall surface of the water jacket 4.

The cylinder block body 3 is also made of an aluminum alloy, a magnesium alloy, or the like, like the cylinder liner 2, and is integrally cast using a die casting method.
When the cylinder liner 2 is fitted to the cylinder block body 3, the lower surface of the flange portion 22 of the cylinder liner 2 is abutted and supported by the mounting surface 33 of the cylinder block body 3, and the bottom surface of the cylinder liner 2 is 25 is abutted and supported by the upper end surface 32 of the cylinder block body 3. Further, as described above, the lower portion of the outer peripheral surface 23 of the cylinder liner 2 is fitted into the lower inner peripheral surface 34a of the cylinder block main body 3, and is abutted and supported by the lower inner peripheral surface 34a of the cylinder block main body 3. .

  In this way, the cylinder liner 2 is abutted and supported by the cylinder block body 3 at three locations, that is, the bottom surface 25, the lower surface of the flange portion 22, and the lower portion of the outer peripheral surface 23. Therefore, the cylinder liner 2 can be stably fixed to the cylinder block body 3, and the rigidity as the cylinder liner 2 can be easily secured.

  FIG. 2 shows a partial cross-sectional structure along the central axis of one cylinder in a direction orthogonal to the cylinder arrangement direction in a state where the cylinder liner 2 and the cylinder block body 3 are assembled. The side structure of is shown. 4A shows a planar structure centered on each cylinder 21 of the assembled cylinder block 1, and FIGS. 4B and 4C show the BB line in FIG. 4A, respectively. , The partial cross-section structure along CC line is shown.

  First, as shown in FIG. 2, the cylinder liner 2 and the cylinder block body 3 are assembled in the above-described manner, so that the gap between the outer peripheral surface 23 of the cylinder liner 2 and the inner peripheral surface 34 of the cylinder block main body 3 is increased. The water jacket 4 for circulating the cooling water is partitioned. However, as described above, even when the water jacket 4 is partitioned and the cooling water circulates therethrough, the heat receiving state from the inside of the cylinder in each cylinder 21 of the cylinder block 1 is different for each part. For example, in the axial direction of each cylinder 21, the amount of heat received from the combustion gas increases in a portion close to the combustion chamber exposed to the high-temperature combustion gas, that is, near the upper end of each cylinder 21. In the lower part separated from the combustion chamber, the amount of heat received is reduced by cooling with lubricating oil. On the other hand, in the plane direction perpendicular to the axis of the cylinder 21, the amount of heat received is particularly large because the combustion heat acts on each other at the connecting portions of the adjacent cylinders 21. Since 4 is not formed, it is difficult to radiate such heat itself.

  Therefore, in the present embodiment, the fin group 24 is provided on the outer peripheral surface 23 of the cylinder coupling body 20, and in the modes shown in FIGS. 2 and 3 and FIGS. The amount of heat released to the cooling water of the water jacket 4 is changed for each part of the cylinder 21 by changing the protruding length of each fin 24a to 24g. That is, the fin group 24 is formed in such a manner that the contact area with the cooling water of the water jacket 4 is basically increased as the portion of the cylinder 21 that receives heat increases. In accordance with the efficient and effective heat dissipation to the cooling water, the temperature gradient of each part of the cylinder is corrected.

  Specifically, with respect to the axial direction of the cylinder 21, as shown in FIGS. 2 and 3, each of the seven fins 24a to 24g is gradually shortened from the first fin 24a to the seventh fin 24g. It is formed to become. In the present embodiment, the distance between the fins is the shortest distance between the first fin 24a and the second fin 24b and the longest distance between the sixth fin 24f and the seventh fin 24g. In this manner, the distance between adjacent fins is increased as it goes below the cylinder 21.

  On the other hand, regarding the planar direction of the cylinder 21, as shown in FIGS. 4A to 4C, the seven fins 24a to 24g are formed in a substantially wave shape along the arrangement direction of the cylinder 21, The projecting lengths of the fins 24 a to 24 g are different depending on the positions in the arrangement direction of the cylinders 21. That is, the fins 24 a to 24 g have the longest protruding length in the vicinity of the connecting portion of the cylinders 21 adjacent to each other in the arrangement direction of the cylinders 21, and the protruding length increases as the distance from the connecting portion between the adjacent cylinders 21 increases. Is formed so that the length gradually decreases.

  With the above-described configuration of the fin group 24, the contact area between the fin group 24 and the cooling water of the water jacket 4 increases as the temperature of each part of the cylinder 21 increases. A part can secure more heat radiation to the cooling water flowing through the water jacket 4. This makes it possible to correct the temperature gradient of each part of the cylinder 21 that has conventionally occurred in the manner illustrated in FIGS. 9 and 10. The projecting length of each fin 24a to 24g (including the projecting length of each part) and the distance between the fins constituting the fin group 24 are the heat receiving state during engine operation, the thermal expansion coefficient of the cylinder liner 2, and the like. Through the experiments and simulations based on the above, the cylinder bore is set to a value that maintains the roundness and straightness of the cylinder well.

As explained above, according to the cooling structure of the cylinder block according to this embodiment, the effects listed below can be obtained.
(1) A fin group 24 is formed on the outer peripheral surface 23 of the cylinder liner 2, and the contact area of the fin group 24 with the cooling water in the water jacket 4 increases toward the upper side in the axial direction of the cylinder 21. In the plane direction, the contact area with the cooling water in the water jacket 4 is formed so as to be closer to the adjacent cylinder coupling portion. That is, the fin group 24 is formed in such a manner that the contact area with the cooling water flowing through the water jacket 4 increases as the portion of the cylinder 21 that receives heat increases. As a result, the portion of the cylinder 21 that receives more heat secures more heat radiation to the cooling water, so that the temperature gradient generated in the cylinder can be finely corrected, and the temperature rise around the cylinder bore becomes uneven. Will naturally be suppressed. That is, the cylinder bore deformation and the like are preferably suppressed.

  (2) The cylinder liner 2 is cast by a die casting method using a mold in which a portion constituting the wall surface of the cylinder and the fin group 24 are formed so as to be integrally molded. As a result, the workability of the cylinder liner 2 that must have a complicated shape by providing the fin group 24 is maintained, and the productivity as a cylinder block is also maintained high.

(Second Embodiment)
Next, a second embodiment that embodies the cooling structure of the cylinder block according to the present invention will be described with reference to FIGS. The second embodiment is different from the first embodiment in that the cooling structure according to the present invention is applied to a cylinder block having different division modes with a water jacket as a boundary. .

  FIG. 5 shows an exploded perspective structure of the cylinder block 101 to which the cooling structure of the second embodiment is applied. As shown in the figure, this cylinder block 101 is divided into a cylinder block main body 102 constituting the cylinder side and a cylinder block outer wall 103 constituting the outer wall of the water jacket, with a portion serving as a water jacket as a boundary. It is structured. That is, in the present embodiment, the cylinder block body 102 constitutes a first structure, and the cylinder block outer wall 103 constitutes a second structure.

  Among these, the cylinder block main body 102 constituting the first structure is formed by integrally forming a cylinder coupling body 120 in which a plurality of cylinders 121 are integrally coupled, and a crankcase portion 131. A mounting surface 132 on which the cylinder block outer wall 103 is mounted is formed so as to protrude from the lower periphery of the cylinder 121 of the cylinder block main body 102.

  Further, in the present embodiment, a substantially annular flat plate shape that protrudes toward a portion that becomes a water jacket on the outer peripheral surface 123 of the cylinder coupling body 120 of the cylinder block main body 102 and surrounds the cylinder coupling body 120. A plurality of (seven in this example) fins 124 a to 124 g formed in the above are provided in order from the upper part to the lower part of the outer peripheral surface 123. And the heat dissipation mechanism is comprised by the fin group 124 comprised by each of these fins 124a-124g.

  The cylinder block body 102 is also made of an aluminum alloy, a magnesium alloy, or the like in order to reduce the weight of the engine, and the wall surface of the cylinder 121, the crankcase portion 131, and the fin group 124 are formed so as to be integrally formed. It is cast by a die casting method using a mold. In consideration of wear caused by the piston, a cylinder liner 125 made of cast iron or the like cast in advance is formed on the inner peripheral surface of the cylinder 121 by casting.

  On the other hand, the cylinder block outer wall 103 that constitutes the second structure has an inner peripheral surface 134 that faces the outer peripheral surface 123 of the cylinder connecting body 120 of the cylinder block main body 102, and around the cylinder connecting body 120. This is also integrally formed by casting using an aluminum alloy, a magnesium alloy or the like as a material.

  The cylinder block outer wall 103 is assembled so as to be placed on the placement surface 132 of the cylinder block main body 102, whereby the outer peripheral surface 123 and the placement surface 132 of the cylinder block main body 102, A water jacket is defined around the cylinder coupling body 120 by the inner peripheral surface 134 of the cylinder block outer wall 103.

  FIG. 6 shows a longitudinal cross-sectional structure of the cylinder block 101 formed by assembling the cylinder block outer wall 103 to the cylinder block body 102, that is, a cross section along the central axis of one cylinder in a direction orthogonal to the cylinder arrangement direction. The structure is shown. As shown in FIG. 6, like the fin group 24 of the first embodiment, the fin group 124 has a protruding length that gradually increases from the lower part to the upper part of the cylinder 121 in the water jacket 104. The distance between the fins is formed so as to be gradually shortened. As is clear from FIG. 5, the fin group 124 is also adjacent to the cylinder 121 adjacent to each other in the plane direction perpendicular to the axis of the cylinder 121 as in the fin group 24 of the first embodiment. The protrusion length is formed so as to gradually increase as it approaches the connecting portion. That is, even in the present embodiment, the fin group 124 becomes the water jacket 104 in such a manner that the contact area with the cooling water flowing through the water jacket 104 increases as the temperature of the cylinder 121 increases. Projected at the site.

  Thereby, also by the cooling structure concerning this 2nd Embodiment, the effect similar to the effect as described in said (1), (2) of previous 1st Embodiment, or it can be acquired now. become.

(Other embodiments)
In addition, each said embodiment is not limited to the structure illustrated above, respectively, This can also be implemented with the aspect of the following modification 1-the modification 3 which changed the same embodiment suitably. For the sake of convenience, these modified examples 1 to 3 will be described taking a cylinder block having a divided structure of the cylinder liner and the cylinder block body as an example in accordance with the first embodiment. A cylinder block having a divided structure according to the second embodiment can be similarly applied.

(Modification 1)
In this embodiment, in each of the above-described embodiments, instead of integrally forming a portion constituting the cylinder wall surface and the fin group as the first structure on the cylinder side, the portion constituting the cylinder wall surface and the fin group Are formed as separate members, and they are joined together.

  FIG. 7 shows a cross-sectional structure in a state in which the cylinder liner 202 and the cylinder block body 203 in the cylinder block 201 in this modification are assembled as a diagram corresponding to FIG. As shown in FIG. 7, the cylinder liner 202 includes a cylinder liner body 220 and a plurality of cylinder liner bodies 220 formed as separate members from the cylinder liner body 220, that is, the first to seventh seven sheets in this example as well. And a fin group 224 including fins 224a to 224g. These fins 224a to 224g constituting the fin group 224 are fixed to the outer peripheral surface 223 of the cylinder 221 of the cylinder liner body 220 by fitting, welding, or the like. In the fin group 224, the fins 224a to 224g are formed in substantially the same shape as the fins 24a to 24g of the first embodiment, and the distance between the fins 224a to 224g is as described above. It is provided so as to have a length equivalent to the distance between the fins 24a to 24g of the first embodiment.

  Thus, according to this modification in which the fin group 224 is provided as a separate member, a material having high thermal conductivity such as copper can be appropriately selected and used for each of the fins 224a to 224g. That is, it is possible to secure a larger amount of heat radiation to the cooling water flowing through the water jacket 204. Further, since the fins 224a to 224g may be fixed to the outer peripheral surface 223 of the cylinder by welding or the like, a relatively free shape can be adopted as compared with a case where the fins 224a to 224g are integrally formed by casting or the like. For example, each fin 224a can be formed in a corrugated shape, and the degree of freedom in designing the fin surface area can be increased.

(Modification 2)
As shown in FIG. 7, in this modification, the width of the water jacket is changed according to each part in the cylinder axial direction.

  That is, an approximately half area of the lower portion of the outer peripheral surface 223 of the cylinder liner main body 220 is formed to gradually increase in thickness so as to approach the cylinder block main body 203 toward the lower portion of the cylinder 221. As a result, the width of the upper portion of the water jacket 204 becomes wider than the width of the lower portion. Therefore, the flow rate of the cooling water flowing in the water jacket 204 is larger on the upper side, and the combustion chamber side located above the cylinder 221 is located. It becomes possible to cool more efficiently.

  FIG. 7 shows, as an example, a case where the lower part of the outer peripheral surface 223 of the cylinder liner body 220 is smoothly formed in a so-called taper shape. In particular, the shape may approach the cylinder block body 203 side.

  Further, in FIG. 7, the surface facing the portion that becomes the water jacket 204 is shaped so that the lower region on the cylinder liner 202 side approaches the main body side of the cylinder block 203, but conversely, the portion facing the portion that becomes the water jacket 204 faces. On the surface, the area below the cylinder block body 203 may be close to the cylinder liner 202 side. Furthermore, it is good also as a shape where the downward area | region of those both structures 202 and 203 approaches mutually in the surface which faces the site | part used as the water jacket 204. FIG. In addition, the shape of each structure as the second modified example is not limited to the combination with the first modified example illustrated in FIG. 7 but can be implemented as a combination with the first or second embodiment. Needless to say.

(Modification 3)
In this modified example, each fin is formed in a substantially rectangular flat plate instead of forming each fin in a substantially annular flat plate surrounding the cylinder coupling body.

FIG. 8 shows a perspective structure of a cylinder liner 302 according to this modification as a view corresponding to a part of FIG.
As shown in FIG. 8, a plurality of fin rows 324 a to 324 g having a substantially rectangular flat plate shape are provided on the outer peripheral surface 323 of a cylinder coupling body 320 to which a cylinder 321 is coupled. It is provided as. Specifically, each of the fin rows 324a to 324g constituting the fin group 324 is provided so as to be arranged in seven rows vertically in the axial direction of the cylinder 321 on the outer peripheral surface 323 of the cylinder coupling body 320. The fins in the row are provided so as to spread substantially radially from the central axis of the cylinder 321 in a plane direction perpendicular to the axis of the cylinder 321. The fin rows 324a to 324g arranged in the vertical direction are arranged such that the fin projection length increases toward the upper side of the cylinder 321 and the fin row arranged at the upper side of the cylinder 321 is adjacent to the fin row. It is provided in such a manner that the distance to the row is shortened. Further, in the plane direction perpendicular to the axis of the cylinder, the fins gradually increase in length as the fins approach the connecting portion side of the cylinder 321, and the distance between adjacent fins also decreases. Is provided. That is, also in this case, the fin group 324 is provided in such a manner that the contact area with the cooling water flowing through the water jacket portion increases as the heat receiving portion of the cylinder increases. An effect comes to be acquired. Such a fin structure can also be combined with Modification 1 and Modification 2.

In addition, there are the following elements that can be changed in common with the above-described embodiments and modifications.
-The number of fins, the shape, and the like are not particularly limited to those shown in the above embodiments and the modifications thereof. That is, the number of fins arranged in the axial direction of the cylinder is not particularly limited. For example, the number of fins or the number of rows arranged in the axial direction of the cylinder may be increased as it approaches the connecting portion of the cylinder. Further, even when each fin is formed integrally with the first structure by casting or the like, the heat radiation area may be further expanded by forming the shape into a corrugated shape. Also, in this case, the portion of the fin that receives more heat, such as by reducing the period of the fin waveform as the portion that receives more heat from the cylinder, or increasing the amplitude of the waveform as the portion that receives more heat from the cylinder. The contact area with the cooling water may be increased.

  In each of the above embodiments and the modifications thereof, the fins or fin rows are arranged such that the distance between the adjacent fins or fin rows becomes shorter as the fins or fin rows arranged on the upper side in the axial direction to the cylinder. However, the fins or fin rows may be arranged at equal intervals.

  In the second modification, as the cooling water flow path structure of the water jacket for cooling the cylinder block in cooperation with the fin or the fin row, at least one of the first structure and the second structure is A structure was adopted in which the lower part is closer to the other structure than the upper part on the surface facing the water jacket. However, as described above, in the arrangement direction of the cylinders, the portions of the connecting portions of the cylinders adjacent to each other become high temperature, so that the cylinders are connected particularly through the change of the wall surface shape facing the water jacket of the second structure. You may make it make the water jacket shape that more cooling water flows, so that a part is approached. By cooperating with such a water jacket shape, the temperature gradient that has conventionally occurred in the cylinder can be corrected more efficiently.

  -Although the heat dissipation mechanism is configured by the fin group consisting of the fins and the fin row, the heat dissipation mechanism is not limited to these fin groups, and any mechanism can be used for heat exchange by projecting to the water jacket. Good. And as a cooling structure, the main point is that the portion where heat reception of the cylinder increases in the outer peripheral surface of the first structure constituting the wall surface of the cylinder with the portion serving as the water jacket of the cylinder block flowing in the water jacket. Any structure may be used as long as a heat dissipating mechanism that protrudes from a portion that becomes the water jacket in a mode in which the contact area with the cooling water is increased.

The perspective view which shows the decomposition | disassembly structure of the cylinder block to which the cooling structure was applied about 1st Embodiment of the cooling structure of the cylinder block which concerns on this invention. Sectional drawing which shows the longitudinal cross-section about the cooling structure of the cylinder block of the said 1st Embodiment. The side view which shows the side structure of the cylinder liner used for the cooling structure of the cylinder block of the said 1st Embodiment. (A) is a top view which shows the planar structure centering on each cylinder about the cooling structure of the cylinder block of 1st Embodiment. (B) is sectional drawing which shows the partial cross-section along the BB line of FIG. 4 (A). (C) is sectional drawing which shows the partial cross-section structure along CC line of FIG. 4 (A). The perspective view which shows the decomposition | disassembly structure of the cylinder block to which the cooling structure was applied about 2nd Embodiment of the cooling structure of the cylinder block which concerns on this invention. Sectional drawing which shows the longitudinal cross-section about the cooling structure of the cylinder block of the 2nd Embodiment. Sectional drawing which shows the longitudinal cross-section of the cooling structure of the cylinder block about the modification 1 or the modification 2 of 1st Embodiment. The perspective view which shows the perspective structure of the cylinder liner used for the cooling structure about the modification 3 of 1st Embodiment. The figure which shows the general temperature distribution to the plane direction in the cylinder periphery of a cylinder block. FIG. 10 is a temperature distribution diagram showing the relationship between the distance from the upper surface of the bore and the temperature of the bore portion at portions along the lines AA and BB in FIG. 9, respectively.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,101,201 ... Cylinder block, 2,125,202,302 ... Cylinder liner, 3,102,203 ... Cylinder block main body, 4,104,204 ... Water jacket, 20,120,320 ... Cylinder coupling body, 21 121,221,321 ... cylinder, 22 ... flange, 23, 123, 223, 323 ... outer peripheral surface, 24, 124, 224, 324 ... fin group, 24a-24g, 224a-224g ... fin, 25 ... bottom surface, 30 ... Cylinder block outer wall part, 31, 131 ... Crank case part, 32 ... Upper end surface, 33, 132 ... Placement surface, 34, 134 ... Inner peripheral surface, 34a ... Lower inner peripheral surface, 34b ... Upper inner peripheral surface, 35 ... Step part, 103 ... Cylinder block outer wall, 220 ... Cylinder liner body, 324a to 324g ... Fin row.

Claims (10)

A first structure that forms the wall surface of the cylinder and a second structure that forms the outer wall of the water jacket are provided on the boundary of the portion that becomes the water jacket that is the flow path of the cooling water of the cylinder block, A cooling structure of a cylinder block for cooling the cylinder with cooling water flowing through the water jacket,
The outer peripheral surface of the first structure is provided with a heat dissipation mechanism that protrudes to a portion that becomes the water jacket in such a manner that a contact area with the cooling water increases as a portion that receives heat from the cylinder increases. Cylinder block cooling structure characterized by The heat dissipating mechanism includes a portion formed such that a contact area with the cooling water gradually increases from a lower portion of the cylinder to an upper portion serving as a combustion chamber of the cylinder, and as the connecting portion of the cylinders adjacent to each other approaches each other. The cylinder block cooling structure according to claim 1, including a portion formed so that a contact area with the cooling water gradually increases. The cylinder block cooling structure according to claim 1 or 2, wherein the first structure is formed by integrally forming a portion constituting a wall surface of the cylinder and the heat dissipation mechanism. 3. The cooling structure for a cylinder block according to claim 1, wherein the first structure includes a portion constituting a wall surface of the cylinder and the heat dissipation mechanism as separate members, which are integrally coupled. The cylinder block cooling structure according to any one of claims 1 to 4, wherein the heat dissipation mechanism includes a plurality of fins protruding from an outer peripheral surface of the first structure body to a portion serving as the water jacket. 6. The cooling structure for a cylinder block according to claim 5, wherein the plurality of fins are formed in such a manner that the protruding length of the fins becomes longer as the portion of the cylinder that receives more heat. The cooling structure of a cylinder block according to claim 5 or 6, wherein the plurality of fins are formed in such a manner that a distance between adjacent fins becomes shorter as a part of the cylinder that receives more heat. At least one of the first structure and the second structure is formed in a shape in which the lower part is closer to the other structure than the upper part on the surface facing the portion that becomes the water jacket. The cooling structure of the cylinder block as described in any one of Claims 1-7. The first structure includes a cylinder liner having a flange portion at an upper portion, and the second structure includes a cylinder block body having a mounting surface on which the flange portion of the cylinder liner is mounted on an upper surface. The cooling structure of the cylinder block as described in any one of Claims 1-8. The first structure includes a cylinder block main body having a surface protruding around the lower side of the cylinder, and the second structure has a bottom surface mounted on the protruding surface of the cylinder block main body. The cylinder block cooling structure according to claim 1, comprising a cylinder block outer wall placed.

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