JP2003097264A - Cylinder block for internal combustion engine - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce the temperature difference in the depth direction of a cylinder bore wall, to prevent the cooling water in a water jacket from becoming hot at high engine load, and to make the cylinder bore at low temperature start or low load operation. Reducing the temperature drop at the top of the wall. A cooling water inlet portion of a water jacket is provided.
1, a first partition member 28 is provided near the downstream of the cooling water outlet 22, and a second partition member 29 is provided near the upstream of the cooling water outlet 22, and the water jacket 15 is connected to a first jacket portion 31 upstream of the first partition member 28. The partitioning member is partitioned into an intermediate jacket portion 32 between the two partition members 28 and 29 and a second jacket portion 33 downstream of the second partition member 29. The cooling water flows from the upper portion and the lower portion of the intermediate jacket portion 32 from the first jacket portion 31 to the intermediate jacket portion 32, and the cooling water flows from the intermediate jacket portion 32 to the second jacket portion 33. The cooling water flows out only from the upper part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder block for an internal combustion engine having a water jacket around a cylinder bore wall.

[0002]

2. Description of the Related Art In a cylinder block of a water-cooled internal combustion engine in which a water jacket is formed around a cylinder bore wall, the upper portion of the cylinder bore wall is closer to the combustion chamber as a heat source, so that the temperature becomes higher than that of the lower portion. This tendency becomes more remarkable as the water jacket becomes deeper. Therefore, in a cylinder block having a so-called deep groove structure in which the water jacket is formed near the lower portion of the cylinder bore wall, it is necessary to allow the cooling water to flow through the water jacket in consideration of such a temperature difference of the cylinder bore wall.

Therefore, Japanese Patent Laid-Open No. 2000-345838 proposes that a partition member is provided for partitioning the water jacket into an upper part and a lower part, and cooling water is caused to flow to another system above and below the water jacket. According to this technique, the cooling water flow rate in the upper part of the water jacket is made relatively larger than the cooling water flow rate in the lower part of the water jacket, whereby the upper part of the cylinder bore wall is preferentially and efficiently cooled. Therefore, it is possible to reduce the temperature difference between the upper portion and the lower portion of the cylinder bore wall.

[0004]

By the way, in order to secure the cooling capacity at the time of high load operation of the internal combustion engine, when the flow rate of the cooling water flowing through the water jacket is increased, the heat generation from the combustion chamber is small at the time of low temperature starting. The temperature of the cylinder bore wall becomes low during low load operation. As a result, there is a conflicting problem that friction loss of the piston increases and fuel efficiency deteriorates.

On the other hand, in the cylinder block described in the above publication, the degree of cooling of the upper and lower portions of the cylinder bore wall can be set arbitrarily. However, if a large amount of cooling water is caused to flow in the upper part of the water jacket while giving priority to the cooling capacity at the time of high load operation, the temperature at the upper part of the cylinder bore wall also becomes low at the time of cold start or low load operation, resulting in deterioration of fuel consumption.

The present invention has been made in view of the above circumstances, and an object thereof is to reduce the temperature difference in the depth direction of the cylinder bore wall and to reduce the cooling water in the water jacket under high engine load. An object of the present invention is to provide a cylinder block of an internal combustion engine capable of achieving both high temperature prevention and suppression of temperature decrease in the upper portion of the cylinder bore wall during low temperature starting and low load operation.

[0007]

[Means for Solving the Problems] Means for achieving the above-mentioned objects and their effects will be described below. According to the invention of claim 1, in a cylinder block of an internal combustion engine having a water jacket around a cylinder bore wall, a first partition member is provided in the vicinity of a cooling water inlet portion of the water jacket, and a cooling water outlet of the water jacket is provided. By providing a second partition member in the vicinity of the upstream side of the section, the water jacket is provided with a first jacket section upstream of the first partition member, an intermediate jacket section between the partition members, and a second partition member. Is also divided into a downstream second jacket part, and cooling water flows from the first jacket part to the intermediate jacket part from the upper and lower parts of the intermediate jacket part. The cooling water flows into the two jackets only from the upper part of the intermediate jacket.

According to the above construction, the cooling water flowing into the water jacket of the cylinder block through the cooling water inlet portion receives the first jacket portion, the first partition member, the intermediate jacket portion, the second partition member and the second jacket portion. Flow in order. After that, the cooling water flows out of the cylinder block from the cooling water outlet. In the process in which the cooling water flows in the water jacket in this way, the heat of the cylinder bore wall is taken by the cooling water, and the cylinder bore wall is cooled.

The cooling water flows from the intermediate jacket portion to the second jacket portion only from the upper portion of the intermediate jacket portion. For this reason, the flow of the cooling water is stagnated in the lower part of the intermediate jacket portion, and the cooling water tends to settle. Further, the cooling water flows from the first jacket portion to the intermediate jacket portion from the lower portion in addition to the upper portion. Therefore, it is possible to prevent the cooling water from flowing into the intermediate jacket portion from being obstructed by the first partition member. As a result, it is possible to prevent the temperature of the cylinder bore wall from lowering during cold start of the internal combustion engine or during low load operation, while preventing the temperature of the cooling water from rising in the water jacket during high engine load. Therefore, the temperature of the cylinder bore wall becomes low during cold start, etc.
It is possible to solve the problem that the friction loss of the piston increases and the fuel efficiency deteriorates.

Further, the fact that the cooling water tends to settle in the lower part of the intermediate jacket part and the cooling water flowing from the upper part into the intermediate jacket part combine with the lower part in which the cooling water tends to settle in the upper part of the intermediate jacket part. Cooling water is easier to flow than in. Since the flow of cooling water is different between the upper portion and the lower portion of the intermediate jacket portion in this manner, the upper portion of the cylinder bore wall, which becomes hot, can be cooled more than the lower portion, and the temperature distribution of the cylinder bore wall can be made uniform. This homogenization reduces the distortion of the cylinder bore wall due to the temperature difference in the depth direction of the cylinder bore wall. for that reason,
By reducing the sliding resistance between the piston ring and the cylinder bore wall, the friction loss of the piston can be reduced and the fuel consumption can be improved.

According to a second aspect of the present invention, in the first aspect of the present invention, the first upper portion that allows the first jacket portion and the intermediate jacket portion to communicate with each other via the upper portion and the lower portion of the first partition member. A communication part and a first lower communication part are provided, and a second communication part for communicating the intermediate jacket part and the second jacket part is provided via the upper part of the second partition member.

According to the above structure, when the cooling water flows from the first jacket portion to the intermediate jacket portion, the cooling water flows into the first upper communicating portion above the first partition member and the first partition member. It passes through the lower first communicating portion. In this way, the cooling water flows from the first jacket portion to the intermediate jacket portion from the upper and lower portions of the intermediate jacket portion. Further, when the cooling water flows out from the intermediate jacket portion to the second jacket portion, the cooling water passes through the second communicating portion above the second partition member. In this way, the cooling water flows from the intermediate jacket portion to the second jacket portion only from the upper portion.

According to a third aspect of the present invention, in the second aspect of the invention, at least one of the first upper communication portion and the second communication portion is formed of the first partition member and the second partition member. It is assumed that it is configured by a gap between at least one upper surface and the upper surface of the water jacket.

According to the above construction, when the first upper communicating portion is formed by the gap, when the cooling water flows from the first jacket portion to the intermediate jacket portion, a part of the cooling water is 1 Passes between the upper surface of the partition member and the upper surface of the water jacket. Further, when the second communication portion is formed by a gap, when the cooling water flows out from the intermediate jacket portion to the second jacket portion, the cooling water flows between the upper surface of the second partition member and the upper surface of the water jacket. Pass through

According to a fourth aspect of the present invention, in the second or third aspect of the invention, the first lower communication portion is formed by a gap between the lower surface of the first partition member and the bottom surface of the water jacket. It is configured.

According to the above construction, when the cooling water flows from the first jacket portion to the intermediate jacket portion, a part of the cooling water is between the lower surface of the first partition member and the bottom surface of the water jacket. Pass through the gap.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIGS. FIG. 2 shows a water-cooled cooling device 12 for the internal combustion engine 11. This cooling device 12 includes water jackets 15 and 16, a radiator 17 and a water pump (W / W) provided on a cylinder block 13 and a cylinder head 14 of an internal combustion engine 11, respectively.
P) 18, a fan (not shown), pipes 19 and 20, and the like.

In this cooling device 12, the cooling water circulates by circulating in each part in the order shown by the arrows in FIG. 2, and heat is transferred in the process of this circulation. That is, the cooling water that has been radiated by the radiator 17 and has a low temperature is sent by the water pump 18 to the water jacket 15 of the cylinder block 13 via the pipe 19 and the cooling water inlet portion 21. In the process in which the cooling water passes through the water jacket 15, the heat of the cylinder block 13 is removed by the cooling water. The cooling water is the cooling water outlet portion 22 or the inter-bore cooling water passage 2
The water flows out from the water jacket 15 through 3 and flows into the water jacket 16 of the cylinder head 14. In the process in which the cooling water passes through the water jacket 16, the heat of the cylinder head 14 is removed by the cooling water. In this way, the cooling water, which has taken away heat and increased in temperature, is guided to the radiator 17 through the pipe 20 and cooled by the fan and the traveling wind. The cooled cooling water is sent to the water jacket 15 in the cylinder block 13 again by the water pump 18.

As shown in FIGS. 1, 3 and 4, the main part of the cylinder block 13 is composed of an elongated block body 25 in the direction of arrangement of the cylinder bores 24 (left-right direction in FIG. 1). These cylinder bores 24
It is constituted by an internal space of a substantially cylindrical cylinder bore wall 26 forming a part of the block body 25. Although the coating 27 is formed on the inner peripheral portion of the cylinder bore wall 26 by a method such as thermal spraying, a cylinder liner may be press-fitted instead. A piston (not shown) is reciprocally housed in each cylinder bore 24. In the block body 25, the upper portion of the cylinder bore wall 26 is closer to the combustion chamber as a heat source, so the temperature becomes higher than that of the lower portion.

The water jacket 15 is formed around the cylinder bore wall 26 in the block body 25. The water jacket 15 has a bottom surface 1
5b is located near the lower part of the cylinder bore wall 26 and has a so-called deep groove structure.

Here, as shown in FIG. 1, when a surface along the arrangement direction of the cylinder bores 24 is defined as a side surface 25a on the outer surface of the block body 25, one (the lower side in FIG. 1) of the side surface 25a is located at the end. The cooling water inlet portion 21 is open near the cylinder bore 24. The cooling water outlet 22 is provided in the block body 25 near the cooling water inlet 21. This cooling water outlet 2
2 is connected to the water jacket 16 (see FIG. 2) of the cylinder head 14 as described above. And
The cooling water from the water pump 18 is cooled by the cooling water inlet 21.
Through to the water jacket 15, flows in the direction indicated by the arrow, and flows out from the cooling water outlet 22. The inter-bore cooling water passage 23 is for cooling between the adjacent cylinder bores 24, and is opened by a working method such as a drill path. As described above, the inter-bore cooling water passage 23 allows the water jackets 15 and 16
Are in communication.

Further, in the water jacket 15, a first partition member 28 is provided in the vicinity of the downstream of the cooling water inlet portion 21.
Are arranged. In the water jacket 15, a second partition member 29 is provided near the upstream side of the cooling water outlet 22. Each of the partition members 28 and 29 has a substantially rectangular plate shape, and is formed of a material having a width substantially the same as the flow passage width of the water jacket 15. This material has a coefficient of thermal expansion similar to that of the block body 25. When the block body 25 is made of aluminum, the material of the partition members 28 and 29 is preferably aluminum, stainless steel, or the like.
Further, the upper surfaces 28a, 29a and the lower surfaces 28b, 29b of both partition members 28, 29 are formed into flat surfaces.

Both partition members 28 and 29 are press-fitted between the cylinder bore wall 26 and the outer wall surface of the water jacket 15, and further the adhesive is applied to the cylinder bore wall 26.
Etc. are fixed. And these partition members 28,
The water jacket 15 includes a first jacket portion 31 upstream of the first partition member 28, an intermediate jacket portion 32 between the partition members 28 and 29, and a second jacket downstream of the second partition member 29. It is divided into a part 33.

As shown in FIGS. 3 and 5A, the upper surface 28a of the first partition member 28 is lower than the upper surface 15a of the water jacket 15, that is, the deck surface 13a of the cylinder block 13, for example, 1 to 2 mm. It is located in a low place. The gap between the upper surfaces 28a and 15a constitutes a first upper communicating portion 34 that allows the first jacket portion 31 and the intermediate jacket portion 32 to communicate with each other via the upper portion of the first partition member 28. The first upper communication portion 34 serves as a passage for the cooling water to flow into the intermediate jacket portion 32 from above.

The lower surface 28b of the first partition member 28 is located higher than the bottom surface 15b of the water jacket 15. The gap between the lower surface 28b and the bottom surface 15b constitutes a first lower communication portion 35 that allows the first jacket portion 31 and the intermediate jacket portion 32 to communicate with each other via the lower portion of the first partition member 28. The first lower communication portion 35 serves as a passage when cooling water flows into the intermediate jacket portion 32 from its lower portion.

Here, the ratio of the opening area of the first lower communicating portion 35 to the flow passage area of the water jacket 15 depends on the type of the internal combustion engine 11, but is generally 0.01 to 0.5. desirable. If it is less than 0.01, a small amount of cooling water flows through the first lower communication portion 35, so that a sufficient cooling effect cannot be obtained when the engine has a high load. On the other hand, when it exceeds 0.5, a large amount of cooling water flows through the first lower communication portion 35, which causes a decrease in the temperature of the cylinder bore wall 26 at the time of low temperature starting and low load operation, which results in deterioration of fuel efficiency. May occur.

As shown in FIGS. 4 and 5 (b), the upper surface 29a of the second partition member 29 is lower than the upper surface 15a of the water jacket 15, for example, 1 to 2 mm, like the first partition member 28. It is located in a low place. The gap between the upper surfaces 29a and 15a constitutes a second communication portion 36 that connects the intermediate jacket portion 32 and the second jacket portion 33 to each other via the upper portion of the second partition member 29. The second communication portion 36 serves as a passage when the cooling water flows from the upper portion of the intermediate jacket portion 32 to the second jacket portion 33.
Unlike the first partition member 28, the lower surface 29b of the second partition member 29 is in contact with the bottom surface 15b of the water jacket 15. Therefore, the cooling water cannot flow out from the lower portion of the second partition member 29 to the second jacket portion 33.

A cylinder head 14 is provided on the cylinder block 13 via a gasket (not shown).
Are fastened by head bolts (not shown). Reference numeral 30 in FIG. 1 denotes a bolt hole into which the head bolt is screwed.

According to the cylinder block 13 of the present embodiment configured as described above, the cooling water sent from the water pump 18 flows into the water jacket 15 through the cooling water inlet 21. Most of the cooling water in the water jacket 15 includes the first jacket portion 31, the first partition member 28, the intermediate jacket portion 32, the second partition member 29,
The second jacket portion 33 and the cooling water outlet portion 22 flow in this order. In the intermediate jacket portion 32, the cooling water flows from the cylinder bore 24 at the farthest end toward the cylinder bore at the opposite end, as indicated by the arrow in FIG. When reaching the vicinity of the cylinder bore at the opposite end, the direction is changed to flow toward the cylinder bore at the extreme end, and reaches the cooling water outlet 22. Then, the cooling water flowing out from the cooling water outlet 22 is
It flows into the water jacket 16 of the cylinder head 14. Further, a part of the cooling water flowing in the intermediate jacket portion 32 is guided to the water jacket 16 through the interbore cooling water passage 23. In this way, in the process in which the cooling water flows in the water jacket 15, the heat of the cylinder bore wall 26 is taken by the cooling water, and the cylinder bore wall 26 is cooled.

Here, as shown in FIG. 5 (a), when the cooling water flows from the first jacket portion 31 to the intermediate jacket portion 32, the cooling water is communicated with the first upper portion as shown by the arrow. It passes through the portion 34 and the first lower communication portion 35. That is, the first jacket portion 31 to the intermediate jacket portion 32
Cooling water flows from both the upper part and the lower part. Therefore, although the first partition member 28 is provided, a relatively large amount of cooling water flows into the intermediate jacket portion 32. Further, the first upper communication portion 34 and the first lower communication portion 35 reduce the flow resistance of the first partition member 28 to the cooling water. Therefore, the problem that the cooling water flowing into the water jacket 15 through the cooling water inlet portion 21 vigorously hits the first partition member 28 and swirls is unlikely to occur.

Further, as shown in FIG. 5B, when the cooling water flows from the intermediate jacket portion 32 to the second jacket portion 33, the cooling water passes through the second communicating portion 36.
That is, the cooling water flows from the intermediate jacket portion 32 to the second jacket portion 33 only from the upper portion of the intermediate jacket portion 32. Therefore, in the lower part of the intermediate jacket portion 32, the flow of cooling water is stagnated and the cooling water tends to settle, while
The cooling water flows without stagnation in the upper portion of the intermediate jacket portion 32.

According to this embodiment described in detail above, the following effects can be obtained. (1) The cooling water flows out only from the upper portion of the intermediate jacket portion 32. For this reason, the flow of the cooling water is delayed in the lower part of the intermediate jacket portion, and the cooling water tends to settle. Further, the cooling water is configured to flow into the intermediate jacket portion 32 from the upper and lower portions thereof. Therefore, it is possible to prevent the first partition member 28 from blocking the flow of the cooling water into the intermediate jacket portion. As a result, it is possible to prevent the temperature of the cooling water in the water jacket 15 from rising when the engine load is high, and to increase the temperature of the cylinder bore wall 26 during cold start of the internal combustion engine 11 and during low load operation to reduce the wall temperature. Can be suppressed. Therefore, the temperature of the cylinder bore wall 26 becomes low at the time of cold start, and the friction loss of the piston increases, and the fuel consumption deteriorates.

(2) The fact that the cooling water tends to settle in the lower portion of the intermediate jacket portion 32 and the cooling water flowing into the intermediate jacket portion 32 from the upper portion thereof contributes to Cooling water flows more easily than in the lower part. As described above, since the flow of cooling water is different between the upper portion and the lower portion of the intermediate jacket portion 32, the upper portion of the cylinder bore wall 26, which becomes hot, is cooled more than the lower portion, and the temperature distribution in the depth direction of the cylinder bore wall 26 is made uniform. Can be made. This uniformization reduces the strain on the cylinder bore wall 26 due to the temperature difference in the depth direction of the water jacket 15. Therefore, sliding resistance between the piston ring and the cylinder bore wall 26 can be reduced to reduce friction loss of the piston and improve fuel consumption.

(3) Block main body 2 of the first partition member 28
5, the partition member 28 is attached so that its upper surface 28a is lower than the upper surface 15a of the water jacket 15 by a predetermined height (or the lower surface 28b is higher than the bottom surface 15b by a predetermined height). It is only necessary to press fit and adhere to the outside of the cylinder bore wall 26 or the like. The gap forming the first upper communicating portion 34 and the gap forming the first upper communicating portion 34 can be respectively formed only by performing such a simple operation.

(4) Block main body 2 of the second partition member 29
When assembling the second partition member 29 into the cylinder bore wall 26 or the like, the upper surface 29a of the water jacket 15 may be lower than the upper surface 15a of the water jacket 15 by a predetermined height. This work is performed by the second partition member 2
The bottom surface 29b of 9 is the bottom surface 15b of the water jacket 15.
This is achieved by press-fitting the second partitioning member 29 until it comes into contact with. By performing such simple work,
It is possible to form a gap that constitutes the communication portion 36.

(5) As the first partition member 28, it is only necessary to prepare a square plate material, and it is not necessary to perform post-processing into a special shape. (6) Since press fitting is adopted as a method of fixing the first partition member 28 and the second partition member 29, each part of the block main body 25, such as the water jacket 15 and the cylinder bore wall 26, has a special shape for fixing. You don't have to. Therefore, for the block body 25, the existing cylinder block can be used as it is.

(7) The first partition member 28 is also the second partition member 2
9 may have a sectional shape smaller than the vertical sectional shape of the water jacket 15. Therefore, in order to partition the water jacket into upper and lower spaces, the partition members 28 and 29 are formed with a smaller amount of material as compared with the conventional partition member which requires a shape substantially equal to the horizontal sectional shape of the water jacket. be able to.

The present invention can be embodied in another embodiment shown below. The sizes of the first partition member 28 and the second partition member 29 may be changed according to the load of the internal combustion engine. For example, paying attention to the fact that the load of the internal combustion engine and the temperature of the cooling water have a correlation, the partition members 28 and 29 may be formed of a shape memory alloy. The sizes of the partition members 28, 29, and thus the first upper communication portion 34, the first lower communication portion 35, and the second communication portion 36 are made different at low temperatures and at high temperatures. By doing so, it is possible to further ensure both the prevention of the temperature rise of the cooling water in the water jacket 15 at the time of a high engine load and the suppression of the temperature decrease of the cylinder bore wall 26 at the time of a low temperature start or the like.

First upper communication portion 34, first lower communication portion 3
At least one of 5 and the 2nd communicating part 36 may be changed to the shape different from the above-mentioned embodiment. An example is shown in FIG.
It shows in (a) and FIG.6 (b). In FIG. 6A, the upper surface of the first partition member 28 is inclined by forming a notch 37 in the upper portion of the first partition member 28. Then, the inclined upper surface and the upper surface 15a of the water jacket 15
The first upper communication portion 34 is configured by the gap between The shape of the notch 37 is not limited to the triangular shape as shown in FIG. 6A, and any shape such as a polygonal shape or a semicircular shape can be adopted.

Further, in FIG. 6B, a hole 38 is formed in the upper portion of the first partition member 28, and the hole 38 constitutes the first upper communicating portion 34. The shape of the hole 38 is shown in FIG.
The shape is not limited to the circle as shown in (b), and any shape such as a polygon or an ellipse can be adopted. Further, the size and the number of the holes 38 can be changed appropriately. 6 (a) and 6 (b), the same members as those in the above embodiment are designated by the same reference numerals.

Even with the above modification, the same action and effect as those of the above embodiment in which the first upper communicating portion 34 is constituted by the gap can be obtained. -The above-mentioned embodiment and the above-mentioned FIG.
By combining the gap in (a) and the hole 38, the communication portion 34-
36 may be configured. For example, in FIG. 3, a hole may be formed in the upper portion of the first partition member 28 after leaving a gap.

Other technical ideas that can be understood from the above-described embodiments will be described together with their effects. (A) In the cylinder block for an internal combustion engine according to claim 2, at least one of the first upper communication portion, the first lower communication portion, and the second communication portion is a hole formed in the partition member. It is configured.

(B) In the cylinder block of the internal combustion engine according to claim 2, at least one of the first upper communication portion, the first lower communication portion and the second communication portion is formed in the partition member. It is composed of notches.

According to the above configuration (A) or (B), similarly to the case where the first upper communicating portion and the like are formed by the gap, the first jacket portion to the intermediate jacket portion has an upper portion of the intermediate jacket portion and Cooling water can be introduced from the bottom. Further, the cooling water can be made to flow from the intermediate jacket portion to the second jacket portion only from the upper portion of the intermediate jacket portion.

[Brief description of drawings]

FIG. 1 is a partial plan view showing a cylinder block of an internal combustion engine in an embodiment embodying the present invention.

FIG. 2 is a schematic configuration diagram of a cooling device for an internal combustion engine.

3 is an enlarged cross-sectional view taken along the line AA in FIG.

4 is an enlarged cross-sectional view taken along the line BB in FIG.

5 (a) is an enlarged cross-sectional view taken along line CC of FIG.
FIG. 2B is an enlarged sectional view taken along the line DD in FIG. 1.

6A and 6B are partial cross-sectional views showing another embodiment in which the shape of the first upper communicating portion in FIG. 3 is changed.

[Explanation of symbols]

11 ... Internal combustion engine, 13 ... Cylinder block, 15 ... Water jacket, 15a, 28a, 29a ... Top surface, 15
b ... bottom surface, 21 ... cooling water inlet portion, 22 ... cooling water outlet portion,
26 ... Cylinder bore wall, 28 ... First partition member, 28b ...
Lower surface, 29 ... Second partition member, 31 ... First jacket portion,
32 ... Intermediate jacket part, 33 ... Second jacket part, 3
4 ... 1st upper part communication part, 35 ... 1st lower part communication part, 36 ... 2nd communication part.

Claims (4)

[Claims] 1. A cylinder block for an internal combustion engine having a water jacket around a cylinder bore wall, wherein a first partition member is provided in the vicinity of the downstream of the cooling water inlet of the water jacket, and upstream of the cooling water outlet of the water jacket. By providing a second partition member in the vicinity, the water jacket is provided with a first jacket portion upstream of the first partition member, an intermediate jacket portion between the partition members, and a downstream portion of the second partition member. A second jacket part is provided, and cooling water flows from the first jacket part to the intermediate jacket part from above and below the intermediate jacket part, and from the intermediate jacket part to the second jacket part. The internal combustion engine is characterized in that the cooling water flows out only from the upper part of the intermediate jacket part Engine cylinder block. 2. A first upper communication portion and a first lower communication portion that communicate the first jacket portion and the intermediate jacket portion via the upper and lower portions of the first partition member,
The cylinder block for an internal combustion engine according to claim 1, further comprising a second communication portion that communicates the intermediate jacket portion and the second jacket portion with each other via an upper portion of the second partition member. 3. At least one of the first upper communication portion and the second communication portion is formed by a gap between an upper surface of at least one of the first partition member and the second partition member and an upper surface of the water jacket. The cylinder block of the internal combustion engine according to claim 2, which is configured. 4. The cylinder block for an internal combustion engine according to claim 2, wherein the first lower communication portion is formed by a gap between the lower surface of the first partition member and the bottom surface of the water jacket.