JP5175808B2 - Internal combustion engine cooling structure - Google Patents

Description

  The present invention relates to a cooling structure for an internal combustion engine, and more particularly, to a cooling structure for an internal combustion engine that cools a cylinder liner using a water jacket whose interior is partitioned by a spacer.

  2. Description of the Related Art Generally, a cylinder block of an internal combustion engine mounted on a vehicle such as an automobile includes a cylinder liner in which a cylinder bore for slidably storing a piston is formed, and a water jacket formed so as to surround the outer periphery of the cylinder liner. The cylinder liner is cooled by circulating cooling water in the water jacket.

  By the way, the cylinder liner has a combustion cycle caused by the reciprocating motion of the piston, and the piston top dead center side close to the combustion chamber directly receives the combustion heat of the combustion stroke, so that the temperature easily rises. The temperature at the bottom dead center side of the piston is difficult to rise. For this reason, a temperature gradient occurs in the height direction of the cylinder liner.

  Therefore, conventionally, the temperature gradient of each part of the cylinder liner is corrected by appropriately changing the shape of the water jacket. For example, in a cooling structure for an internal combustion engine in which a water jacket spacer for narrowing the flow width of the water jacket is disposed on the lower side of the water jacket, the flow rate of the cooling water is limited on the lower side of the water jacket. Become so. That is, since cooling of the lower part of the cylinder, which is lower in temperature than the upper part of the cylinder liner, is suppressed, the temperature gradient of each part of the cylinder liner can be made uniform (for example, see Patent Document 1). .

  By the way, the cylinder liner has an inter-bore region located in the vicinity of the boundary between adjacent cylinder bores, and the cylinder bore has a notch (constriction) formed in the inter-bore region. May not cool down.

  The reason is that the cooling water has inertia of the flow, so that a sufficient flow rate is not supplied to the deep cut portion of the inter-bore region, and the cooling water stagnates in the inter-bore region. Further, since the cross-sectional area of the cooling water passage is large in the region between the bores, it is conceivable that the flow rate is reduced and sufficient cooling is not performed. That is, in the region between the bores, cooling water with a sufficient flow rate is not supplied, and thus cooling may be insufficient.

In order to eliminate such problems, the cross-sectional area of the gap between the bore area of the cylinder liner and the water jacket spacer is larger than the cross-sectional area of the gap between the outer periphery of the cylinder bore and the water jacket spacer other than the area between the bores. It is known that the flow velocity between the water jacket spacer and the cylinder bore is increased in the region between the bores by reducing the flow rate so that the region between the bores where heat tends to accumulate can be sufficiently cooled (for example, , See Patent Document 2).
Moreover, in patent document 2, the fin which guides cooling water to the area | region between bores is provided in the water jacket spacer, and it introduce | transduces cooling water into the area | region between bore | bore where heat is easy to accumulate by fins, and sufficient area between bores Are described so that they can be cooled.

JP 2003-262155 A JP 2005-291005 A JP 2002-266695 A JP 2007-71039 A

  In such a cooling structure for a conventional internal combustion engine, for the purpose of improving the assemblability of the water jacket spacer with respect to the water jacket, or for absorbing variations in the dimensions of the water jacket spacer and the water jacket, It is necessary to ensure a gap between the water jacket and the water jacket spacer over the entire circumference of the water jacket.

  However, if a gap is formed over the entire circumference of the water jacket between the water jacket and the water jacket spacer in this way, the water jacket spacer in the water jacket is caused by a change in the flow rate of the cooling water flowing in the water jacket. Moves between a position close to the cylinder liner and a position away from the cylinder liner.

When the water jacket spacer moves away from the cylinder bore, the clearance between the water jacket spacer and the cylinder bore, that is, the cross-sectional area of the inner peripheral passage increases and the flow rate of the cooling water flowing through the inner peripheral passage decreases. As a result, it has become difficult to supply a sufficient amount of cooling water to the region between the bores where heat tends to accumulate.
For this reason, the area between the bores cannot be sufficiently cooled, and the cooling performance of the cylinder liner is lowered.

In order to solve such a problem, the water jacket spacer may be fixed in the water jacket in order to prevent the water jacket spacer from moving.
In order to fix the water jacket spacer in the water jacket in this way, a bolt is inserted into the cylinder block and the water jacket from the outside of the cylinder block, and the water jacket spacer is screwed into the water jacket spacer. Is known to be fixed in a water jacket (see, for example, Patent Document 3).
Also, the water jacket spacer is provided with a swelling member that is swollen by cooling water, and the swelling member is swollen so as to fill the gap between the cylinder liner and the water jacket spacer, thereby fixing the water jacket spacer to the water jacket. Is known (see, for example, Patent Document 4).

  However, since the water jacket spacer is fixed in the water jacket by bolts in the device described in Patent Document 3, there is a problem that the work of attaching the water jacket spacer is troublesome.

  Moreover, since the thing described in patent document 4 needs to provide a swelling member in a water jacket spacer, the problem that the manufacturing cost of a water jacket spacer will increase will generate | occur | produce.

  The present invention has been made in order to solve the above-described conventional problems, and even when the spacer moves in the water jacket so as to be close to and away from the cylinder bore, the area between the bores is sufficient. It is an object of the present invention to provide a cooling structure for an internal combustion engine that can cool the cylinder bore and improve the cooling performance of the cylinder bore.

  In order to achieve the above object, a cooling structure for an internal combustion engine according to the present invention includes (1) a plurality of cylinder liners that are provided adjacent to each other and in which a cylinder bore is formed, and surrounds the periphery of the cylinder liner. A water jacket in which cooling water flows, and an inner peripheral passage that is housed in the water jacket so as to surround the cylinder liner, and is located on the cylinder liner side in the water jacket. A cooling structure for an internal combustion engine, wherein the spacer has a region between bores located in the vicinity of a boundary between adjacent cylinder bores, and the spacer includes the inner circumferential passage. A guide portion that guides the cooling water flowing through the bore region to at least one of the guide portions. The flow direction downstream side of the 却水, and a one notch which communicates with the inner peripheral passage and said outer peripheral passage is formed.

  With this configuration, since the spacer has a guide portion that guides the cooling water flowing through the inner peripheral passage to the region between the bores, when the spacer moves to a position close to the cylinder bore in the water jacket, the spacer and the cylinder bore Therefore, the cross-sectional area of the inner peripheral passage is reduced, so that the flow rate of the cooling water flowing through the inner peripheral passage can be increased and supplied to the region between the bores of the cylinder bore by the guide portion.

  For this reason, the cooling rate (the amount of heat transfer per unit time) of the bore region can be increased, and the region between the bores where heat can easily accumulate can be sufficiently cooled.

  In addition, since the spacer has a cutout portion that communicates the outer peripheral passage and the inner peripheral passage on the downstream side in the coolant flow direction of the guide portion, when the spacer moves to a position separated from the cylinder bore in the water jacket. The gap between the spacer and the cylinder bore, that is, the cross-sectional area of the inner peripheral passage increases, so the flow rate of the cooling water flowing through the inner peripheral passage decreases and the cooling speed of the bore region decreases. Since the cross-sectional area of the outer peripheral passage decreases, the flow rate of the cooling water flowing through the outer peripheral passage increases. Since the cooling water flowing through the outer peripheral passage is supplied to the inner peripheral passage through the notch, the cooling speed of the bore region can be increased, and the inter-bore region can be sufficiently cooled.

  Thus, even if the spacer moves to either the position close to the cylinder bore in the water jacket or the position away from the cylinder bore, the area between the bores can be sufficiently cooled, and the cooling performance of the cylinder bore can be improved. Can be improved.

  Further, since the region between the bores can be sufficiently cooled without fixing the spacer in the water jacket using a bolt or a swelling member as in the prior art, the workability of the spacer mounting operation can be improved. At the same time, it is possible to prevent the manufacturing cost of the spacer from increasing.

  In the internal combustion engine cooling structure described in (1) above, (2) the guide portion is configured to be provided above the spacer.

  With this configuration, since the guide portion is provided on the upper portion of the spacer, the coolant can be introduced into the region between the bores of the piston liner on the piston top dead center side near the combustion chamber by the guide portion. For this reason, even if the spacer moves to either the position close to the cylinder bore in the water jacket or the position away from the cylinder bore, the region between the high-temperature bores close to the combustion chamber can be sufficiently cooled. The cooling performance of the cylinder bore can be improved.

  In the internal combustion engine cooling structure according to the above (2), (3) the guide portion is constituted by a protruding piece that protrudes from the upper end of the spacer to the vicinity of the upper end of the water jacket, and on the downstream side in the coolant flow direction. It is comprised from what the said notch part is formed.

  With this configuration, the guide portion is composed of a protruding piece that protrudes from the upper end of the spacer to the vicinity of the upper end of the water jacket, and a notch is formed on the downstream side in the cooling water flow direction, so that the piston top dead center near the combustion chamber The cooling water can be introduced into the region between the bores of the piston liner on the side by the guide portion. For this reason, even if the spacer moves to either the position close to the cylinder bore in the water jacket or the position away from the cylinder bore, the region between the high-temperature bores close to the combustion chamber can be sufficiently cooled. The cooling performance of the cylinder bore can be improved.

  In addition, a guide is provided on the upper part of the spacer facing the inter-bore area so that cooling water is preferentially supplied to the inter-bore area close to the combustion chamber. If the part is not provided, the flow rate of cooling water supplied to the upper part of the cylinder liner close to the high temperature combustion chamber is increased to cool the upper part of the high temperature cylinder liner, and the cylinder liner away from the combustion chamber An increase in temperature gradient between the lower portion and the upper portion of the cylinder liner can be suppressed, and the cooling performance of the cylinder liner can be further improved.

  According to the present invention, even when the spacer moves in the water jacket so as to approach and separate from the cylinder bore, the region between the bores can be sufficiently cooled, and the cooling performance of the cylinder bore is improved. Therefore, it is possible to provide a cooling structure for an internal combustion engine.

It is a figure which shows one Embodiment of the cooling structure of the internal combustion engine which concerns on this invention, and is a top view of the cylinder block provided with the cooling structure of the internal combustion engine. It is a figure which shows one Embodiment of the cooling structure of the internal combustion engine which concerns on this invention, and is a perspective view of a water jacket spacer. It is a figure which shows one Embodiment of the cooling structure of the internal combustion engine which concerns on this invention, and is the principal part perspective view of the water jacket spacer seen from the protrusion piece side which has a notch part. It is a figure which shows one Embodiment of the cooling structure of the internal combustion engine which concerns on this invention, and is a figure which shows the positional relationship of a water jacket spacer and a water jacket. FIG. 5 is a view showing an embodiment of a cooling structure for an internal combustion engine according to the present invention, and is a side view of the water jacket spacer of FIG. FIG. 5 is a view showing an embodiment of a cooling structure for an internal combustion engine according to the present invention, and is a side view of the water jacket spacer of FIG. It is a figure which shows one Embodiment of the cooling structure of the internal combustion engine which concerns on this invention, and is a block diagram of the water jacket spacer of the protrusion board part which has a notch part. It is a figure which shows one Embodiment of the cooling structure of the internal combustion engine which concerns on this invention, and is AA direction arrow sectional drawing of FIG. It is a figure which shows one Embodiment of the cooling structure of the internal combustion engine which concerns on this invention, (a) is BB direction arrow sectional drawing of FIG. 1, (b) is CC direction arrow of FIG. FIG. It is a figure which shows one Embodiment of the cooling structure of the internal combustion engine which concerns on this invention, and is a figure which shows the flow of a cooling water when a water jacket spacer is located in the constriction part side. It is a figure which shows one Embodiment of the cooling structure of the internal combustion engine which concerns on this invention, and is a figure which shows the flow of a cooling water when a water jacket spacer exists in the position spaced apart from the constriction part. It is a figure which shows one Embodiment of the cooling structure of the internal combustion engine which concerns on this invention, and is a figure which shows the cooling structure of the internal combustion engine of another structure.

DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of a cooling structure for an internal combustion engine according to the present invention will be described with reference to the drawings.
FIGS. 1-12 is a figure which shows one Embodiment of the cooling structure of the internal combustion engine which concerns on this invention.
First, the configuration will be described.
In FIG. 1, an engine cooling structure 1 as an internal combustion engine cools a cylinder block 2 with cooling water as a cooling medium. The engine is a water-cooled reciprocating multi-cylinder engine, for example, an in-line three-cylinder reciprocating engine. The reciprocating engine includes a cylinder block 2.

  In the cylinder block 2, for example, three cylinder liners 3a to 3c are arranged side by side so as to be adjacent to each other, and cylinder bores 4a to 4c are formed inside the cylinder liners 3a to 3c. Therefore, the cylinder bores 4a to 4c are arranged in series.

  The cylinder block 2 is made of an aluminum alloy and is formed by die casting or the like. The cylinder liners 3a to 3c are made of cast iron and an aluminum alloy surrounding the cast iron. Moreover, you may comprise the cylinder block 2 and the cylinder liners 3a-3c from cast iron.

  Pistons 23 (see FIG. 8) are respectively housed in the cylinder bores 4a to 4c so as to be able to reciprocate in the vertical direction, and combustion chambers 5 are formed above the cylinder bores 4a to 4c (see FIG. 8). ).

  A cylinder head (not shown) provided with an intake / exhaust port, a valve mechanism on the intake / exhaust side, a spark plug, an injector (none of which are shown) and the like is mounted on the upper part of the cylinder block 2. A shaft output is output from the crankshaft (not shown) to the transmission side by the reciprocating piston 23.

  Further, a water jacket 6 is formed in the cylinder block 2, and the water jacket 6 is formed by a groove portion having a predetermined width surrounding the cylinder liners 3a to 3c. That is, the water jacket 6 is constituted by a groove formed between the outer peripheral surfaces of the cylinder liners 3 a to 3 c and the inner peripheral surface of the cylinder block 2.

  A water pump 7 is provided on the side surface of the cylinder block 2, and the water pump 7 introduces cooling water into a water jacket 6 through a supply passage 8 formed in the cylinder block 2 through a pipe from a radiator (not shown). It is like that. The cooling water introduced into the water jacket 6 cools the cylinder liners 3 a to 3 c while flowing through the water jacket 6.

  Further, a gasket 9 is provided between the cylinder block 2 and the cylinder head so as to close the upper opening end of the water jacket 6 (see FIGS. 8 and 9), and the cylinder liner 3a is circulated through the water jacket 6. The cooling water deprived of heat from .about.3c is introduced into the cylinder head through the gasket hole 9a provided in the gasket 9 (the gasket hole 9a is shown in phantom in FIG. 1).

  Further, the cylinder head is provided with a cooling water discharge passage, and the cooling water introduced into the cylinder head is discharged from the discharge port after cooling the cylinder head, and is sent to the radiator through a pipe (not shown). It has become.

  A water jacket spacer 10 as a spacer is accommodated in the water jacket 6 so as to surround the cylinder liners 3a to 3c, and the water jacket spacer 10 is arranged in the thickness direction of the water jacket 6 as shown in FIG. It is composed of a frame part made of synthetic resin having an outer shape that occupies the middle part.

  Specifically, as shown in FIGS. 2 and 4, the water jacket spacer 10 is continuously formed so that cylindrical portions 11 a to 11 c along the outer diameter shape of the cylinder liners 3 a to 3 c are adjacent to each other. The cylindrical portions 11a to 11c are formed at a height of about 2/3 of the height of the water jacket 6 and have a base portion 17 (see FIGS. 2 and 8).

  As shown in FIGS. 2, 8, and 9, the base portion 17 is formed in the water jacket 6 between the outer peripheral surface of the cylinder liners 3 a to 3 c and the inner peripheral surface of the water jacket spacer 10. The outer peripheral passage 13 is formed between the outer peripheral surface of the water jacket spacer 10 outside the inner peripheral passage 12 and the outer wall surface of the water jacket 6.

Therefore, the water jacket spacer 10 reduces the flow rate of the cooling water on the bottom dead center side of the piston 23 away from the combustion chamber 5 where the temperature is difficult to rise because the base portion 17 is located below the water jacket 6. By releasing the upper side of the water jacket 6, the cooling water in the water jacket 6 is rectified so as to increase the flow rate of the cooling water on the top dead center side of the piston 23 close to the combustion chamber 5 where the temperature is likely to rise. It has become.
Further, the cylinder liners 3a to 3c have an inter-bore region 14, and the inter-bore region 14 is configured from the vicinity of the boundaries of the plurality of cylinder bores 4a to 4c.

  The inter-bore region 14 constitutes constricted portions 15a to 15d in which the connecting portions of the cylinder liners 3a to 3c are constricted toward the center line in the extending direction of the cylinder bores 4a to 4c. In the present embodiment, the constricted portions 15a to 15d correspond to the inter-bore region 14, and the constricted portions 15a to 15d have a large cross-sectional area of the inner peripheral passage 12, and heat is easily accumulated.

  As shown in FIGS. 2, 3, and 5, an inlet notch 16 is formed in the cylindrical portion 11 a of the water jacket spacer 10, and the inlet notch 16 faces the supply passage 8. It is formed at the site. The inlet notch 16 has a function of facilitating introduction of the cooling water introduced from the water pump 7 through the supply passage 8 into the water jacket 6 into the inner peripheral passage 12.

  As shown in FIGS. 2 and 3, the base portion 17 of the water jacket spacer 10 is formed with convex portions 18a to 18d, and the convex portions 18a to 18d are cylinders facing the constricted portions 15a to 15d. It is formed in the connection part of the parts 11a-11c. The convex portions 18a and 18b protrude toward the constricted portions 15a to 15d, and the convex portions 18a to 18d reduce the cross-sectional area of the inner peripheral passage 12 between the constricted portions 15a to 15d and the convex portions 18a to 18d. It is squeezed.

As shown in FIGS. 1, 2, and 4 to 6, protruding pieces 19 to 22 as guide portions are formed on the upper end 17 a of the base portion 17, and the protruding pieces 19 to 22 are convex. It protrudes upward from the convex portions 18a to 18d so as to be continuous above the portions 18a to 18d.
That is, in the present embodiment, the upper end 17a of the base portion 17 and the upper ends of the convex portions 18a to 18d are located on the same plane. The upper ends of the protruding pieces 19 to 22 are located in the vicinity of the opening end of the water jacket 6 (FIG. 9A shows only the protruding piece 19). The upper ends of the protruding pieces 19 to 22 may be located at the opening end of the water jacket 6.

  Thus, since the water jacket spacer 10 of this Embodiment has the convex parts 18a-18d and the protrusion pieces 19-22 in the position which opposes the constriction parts 15a-15b, it cools which distribute | circulates the inner peripheral channel | path 12. Water is guided to the constricted portions 15 a to 15 d by the convex portions 18 a to 18 d and the protruding pieces 19 to 22.

  Moreover, in this Embodiment, the cooling water introduced into the water jacket 6 from the entrance notch 16 is in order of one side of the cylindrical part 11a, one side of the cylindrical part 11b, and one side of the cylindrical part 11c. In order to distribute | circulate, the clearance gap between the protrusion piece 20 and the constriction part 15b is small with respect to the clearance gap between the protrusion piece 19 and the constriction part 15a.

  This is because if the clearance between the protruding piece 19 on the upstream side of the cooling water and the constricted portion 15a is small, the pressure loss of the cooling water increases and the cooling water does not flow efficiently downstream, so the upstream side of the cooling water This is because the gap between the projecting piece 19 and the constricted portion 15a is increased to reduce the pressure loss of the cooling water so that the cooling water can efficiently flow downstream.

  On the other hand, as shown in FIG. 1, FIG. 3, FIG. 4, FIG. 7, and FIG. 9 (b), the projecting piece 19 is formed with a notch 19a. It is formed downstream in the direction. For this reason, the outer peripheral passage 13 and the inner peripheral passage 12 are communicated with each other by the notch portion 19 a on the downstream side of the protruding piece 19.

  In the engine cooling structure 1 configured as described above, a part of the cooling water introduced into the water jacket 6 from the water pump 7 through the supply passage 8 flows into the outer peripheral passage 13 and the remaining cooling. Water flows into the inner peripheral passage 12 from below the inlet notch 16 and the water jacket spacer 10.

  Then, on the top dead center side of the piston 23 close to the combustion chamber 5, a coolant with a large flow rate flows through the water jacket 6 where the water jacket spacer 10 does not exist, and the bottom dead center side of the piston 23 away from the combustion chamber 5. Then, a small amount of cooling water flows through the inner peripheral passage 12.

  As indicated by an arrow W in FIG. 1, the cooling water flows from one side of the cylindrical portion 11a, cylindrical portion 11b, and cylindrical portion 11c to the other side of the cylindrical portion 11c, cylindrical portion 11b, and cylindrical portion 11c. The cylinder liners 3a to 3c are introduced into the cylinder head through the gasket hole 9a while cooling.

  For this reason, at the top dead center side of the piston 23, the cooling water flows at a flow rate and a flow velocity necessary for cooling, and appropriately cools the top dead center side of the piston 23 of the cylinder liners 3a to 3c. On the bottom dead center side of the piston 23, the lower portions of the cylinder liners 3 a to 3 c are cooled by the cooling water whose flow rate increases with a small flow rate by the inner peripheral passage 12. For this reason, the lower portions of the cylinder liners 3a to 3c are cooled to an optimum temperature without being supercooled, so that the friction of the piston 23 can be reduced and fuel efficiency can be improved.

  On the other hand, since the cooling water flowing through the inner peripheral passage 12 is guided to the constricted portions 15a to 15d by the convex portions 18a to 18d and the projecting pieces 19 to 22, the constricted portions 15a to 15d that are likely to accumulate heat are cooled.

  In particular, since projecting pieces 19 to 22 are provided above the base portion 17 and the upper ends of the projecting pieces 19 to 22 are projected to the vicinity of the opening end of the water jacket 6, the top dead center of the piston 23 close to the combustion chamber 5. The high-temperature constricted portions 15a to 15d on the side can be cooled.

  Here, in the cooling structure 1 of the engine, reasons such as improving the assembling property of the water jacket spacer 10 with respect to the water jacket 6 and absorbing the variation in the dimensions of the water jacket spacer 10 and the water jacket 6. Therefore, it is necessary to secure a gap between the water jacket 6 and the water jacket spacer 10 over the entire circumference of the water jacket 6.

  In this way, when a gap is formed over the entire circumference of the water jacket 6 between the water jacket 6 and the water jacket spacer 10, the water jacket 6 is changed in the water jacket 6 due to a change in the flow rate of the cooling water flowing in the water jacket 6. The water jacket spacer 10 moves between a position close to the cylinder liners 3a to 3c and a position spaced apart.

  In particular, since the water pump 7 is connected to the crankshaft of the engine, the rotational speed increases and the flow rate of cooling water introduced from the water pump 7 into the water jacket 6 increases, so that the engine rotational speed (water As the rotational speed of the pump 7 increases, the water jacket spacer 10 becomes easier to move. In the present embodiment, the gap between the projecting piece 19 and the constricted part 15a is larger than the gap between the constricted part 15b and the projecting piece 20. Since it is large, the amount by which the protruding piece 19 approaches and separates from the constricted portion 15a increases.

  In the present embodiment, when the water jacket spacer 10 moves to a position close to the constricted portion 15a in the water jacket 6, as shown in FIG. 10, the gap between the water jacket spacer 10 and the constricted portion 15a, that is, Since the cross-sectional area of the inner peripheral passage 12 is reduced, the flow rate of the cooling water W2 flowing through the inner peripheral passage 12 can be increased and supplied to the constricted portion 15a by the protruding piece 19.

  For this reason, the cooling rate (heat transfer amount per unit time) of the constricted portion 15a can be increased, and the constricted portion 15a in which heat is easily accumulated can be sufficiently cooled.

  On the other hand, when the water jacket spacer 10 moves to a position away from the constricted portion 15a in the water jacket 6, the gap between the water jacket spacer 10 and the constricted portion 15a, that is, the cross-sectional area of the inner peripheral passage 12 is large. Therefore, the flow rate of the cooling water flowing through the inner peripheral passage 12 decreases and the cooling speed of the constricted portion 15a decreases. At this time, the cross-sectional area of the outer peripheral passage 13 decreases. The water flow rate increases.

  In the present embodiment, the water jacket spacer 10 is provided with a protruding piece 19 that guides the cooling water flowing through the inner peripheral passage 12 to the constricted portion 15a, and the outer peripheral passage 13 is disposed downstream of the protruding piece 19 in the flowing direction of the cooling water. As shown in FIG. 11, the cooling water W3 flowing through the outer peripheral passage 13 can be supplied to the inner peripheral passage 12 through the notch 19a. it can. For this reason, the cooling rate of the constriction part 15a can be increased, and the constriction part 15a can fully be cooled.

  As described above, in the present embodiment, the water jacket spacer 10 is constricted regardless of whether the water jacket spacer 10 moves within the water jacket 6 to a position adjacent to the cylinder bores 4a to 4c or a position separated from the cylinder bores 4a to 4c. The portion 15a can be sufficiently cooled, and the cooling performance of the cylinder bores 4a to 4c can be improved.

  In the present embodiment, since the water jacket spacer 10 can be sufficiently cooled without fixing the water jacket spacer 10 in the water jacket 6 using bolts or swelling members as in the prior art, the water jacket spacer 10 can improve the workability of the attachment work and can prevent an increase in the manufacturing cost of the water jacket spacer 10.

  Since the gap between the constricted portions 15b to 15d and the projecting pieces 20 to 22 is formed in advance small, when the water jacket spacer 10 moves to a position away from the cylinder liners 3a to 3c in the water jacket 6. Since the gap between the constricted portions 15b to 15d and the projecting pieces 20 to 22 does not become larger than the gap between the constricted portion 15a and the projecting pieces 19, the constricted portions 15b to 15d are guided by the projecting pieces 20 to 22 in the cooling water. Sufficient cooling performance can be ensured only by this.

  Further, in the present embodiment, the protruding piece 19 is protruded from the upper end of the base portion 17 to the vicinity of the opening end of the water jacket 6, and the cutout portion 19a is formed on the downstream side of the protruding piece 19 in the coolant flow direction. That is, since the protruding piece 19 and the cutout portion 19a are provided on the upper portion of the water jacket spacer 10, the cooling water is introduced by the protruding piece 19 into the constricted portion 15a on the top dead center side of the piston 23 near the combustion chamber 5. Can do. For this reason, even if the water jacket spacer 10 moves to either the position close to the cylinder bores 4a to 4c or the position separated from the cylinder bores 4a to 4c in the water jacket 6, the high temperature close to the combustion chamber 5 is reached. The constricted portion 15a can be sufficiently cooled, and the cooling performance of the cylinder bores 4a to 4c can be improved.

  Further, in the present embodiment, the protruding pieces 19 to 22 are provided on the upper portion of the base portion 17 facing the constricted portions 15 a to 15 d so that the cooling water is preferentially supplied to the constricted portions 15 a to 15 d close to the combustion chamber 5. Therefore, if the protruding pieces 19 to 22 are not provided in the region close to the combustion chamber 5 other than the constricted portions 15a to 15d, the cooling supplied to the upper portions of the cylinder liners 3a to 3c close to the high temperature combustion chamber 5 The upper part of the high temperature cylinder liners 3a to 3c is cooled by increasing the flow rate of water, and the temperature gradient between the lower part of the cylinder liners 3a to 3c and the upper part of the cylinder liners 3a to 3c away from the combustion chamber 5 increases. Can be suppressed, and the cooling performance of the cylinder liners 3a to 3c can be further improved.

  In this embodiment, engine cooling structure 1 is applied to an in-line three-cylinder engine, but may be applied to an in-line four-cylinder or more engine. In addition to the inline engine, as shown in FIG. 12, the water jackets 36 and 37 surrounding the cylinder liners 34a to 34c and 35a to 35c formed in the right bank 32 and the left bank 33 of the V-type engine 31 are provided. You may store the water jacket spacer 10 mentioned above.

  Moreover, although the notch part 19a is formed only in the protrusion piece 19, you may form it in the protrusion pieces 20-22. In short, the notch portion is provided on the protruding plate so that the constricted portions 15a to 15d can be efficiently cooled in accordance with the flow rate of the cooling water such as the flow rate and flow rate of the cooling water flowing through the water jacket 6. What is necessary is just to form in the distribution direction downstream.

  The embodiment disclosed this time is illustrative in all respects and is not limited to this embodiment. The scope of the present invention is shown not by the above description of the embodiments but by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

  As described above, the internal combustion engine cooling structure according to the present invention can sufficiently cool the region between the bores even when the spacer moves in the water jacket so as to approach and separate from the cylinder bore. It is possible to improve the cooling performance of the cylinder bore, and it is useful as a cooling structure for an internal combustion engine that cools the cylinder liner using a water jacket whose interior is partitioned by a spacer.

DESCRIPTION OF SYMBOLS 1 Engine cooling structure 3 Cylinder liner 3a-3c Cylinder liner 4a-4c Cylinder bore 6 Water jacket 10 Water jacket spacer (spacer)
12 inner circumference passage 13 outer circumference passage 14 area between bores 15a to 15d constriction portion 19 to 22 projecting piece (guide portion)
19a Notch 34a-34c Cylinder liner 36, 37 Water jacket

Claims (2)

A plurality of cylinder liners provided adjacent to each other and having a cylinder bore formed therein;
A water jacket formed so as to surround the cylinder liner and through which cooling water flows;
A spacer which is accommodated in the water jacket so as to surround the cylinder liner, and which partitions the inside of the water jacket into an inner peripheral passage located on the cylinder liner side and an outer peripheral passage located outside the inner peripheral passage; With
In the internal combustion engine cooling structure, wherein the cylinder liner has a plurality of inter-bore regions located in the vicinity of a boundary between adjacent cylinder bores,
Said spacer has a plurality of guide portions for guiding the cooling water flowing through the inner circumferential passage thereon to an upper portion of the plurality of the inter-bore region,
A cooling structure for an internal combustion engine, characterized in that a notch portion that communicates the outer peripheral passage and the inner peripheral passage is formed downstream of at least one of the guide portions in the flow direction of the cooling water. The said guide part is comprised from the protrusion piece which protrudes in the vicinity of the upper end of the said water jacket from the upper end of the said spacer , The said notch part is formed in the distribution direction downstream of cooling water. The cooling structure of the internal combustion engine as described.