Internal combustion engine

A ringed coolant water passage 16 formed to surround a plurality of cylinders #1-#4 is provided. Two partitioning members having a larger thermal expansion coefficient as compared to that of a cylinder block 10, and separating the ringed coolant water passage 16 into first passage 22 and second passage 24 is provided. The first passage 22 exists mainly at one side of a longitudinal bore center plane which extends along the longitudinal direction of the cylinder block 10 while the second passage 24 exists mainly at the other side. An inlet which communicates with the first passage and an outlet which communicates with the second passage are provided. A cylinder head including a coolant water passage which opens to both of the first passage 22 and the second passage 24 is attached to the cylinder block 10. The cylinder block 10 and the partitioning members 12, 14 are formed so that stress acting between both of them in a condition where the internal combustion engine is warmed up does not reach to a breaking stress of the partitioning members 12, 14.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No. PCT/JP2009/068426 filed Oct. 27, 2009, the contents of all of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present invention relates to an internal combustion engine, particular to an internal combustion engine having a cooling system that is suitable to an internal combustion engine of the water cooling type.

BACKGROUND ART

An internal combustion engine in which coolant water is circulated by a way of so-called breadthwise flowing is described in Japanese Utility Model Laid-Open publication No. 64-34423. More particularly, the above publication discloses a cylinder block having three cylinders placed in series. This cylinder block is provided with two coolant water passages independent of each other on either side of the three cylinders. One of the coolant water passages is equipped with an inlet of coolant water. The other coolant water passage is equipped with an outlet of the coolant water.

A cylinder head is attached to the cylinder block. The cylinder head is provided with coolant water passages for cooling down surroundings of valve systems installed therein. Usually, this coolant water passage delivers and receives coolant water to and from coolant water passages in the cylinder block. According to the internal combustion engine disclosed by the above described publication, coolant water supplied to the inlet initially flows through inside of the coolant water passage installed in one side (it is assumed exhaust side) of the cylinder block. Subsequently, the coolant water flows into the coolant water passage in the cylinder head from openings provided at its exhaust side. The coolant water flowing through the inside of the cylinder head flows into the other side of the cylinder block, that is, into the coolant water passage installed in the intake side from intake side openings. The coolant water circulates along sides of the cylinders afterwards, so as to flow out from the outlet. As described above, the internal combustion engine disclosed by the publication can circulate the coolant water around the cylinder and the valve system by the way so-called breadthwise flowing.

As a technique to circulate coolant water inside of the internal combustion engine, the technique of so-called lengthwise flowing is known other than the technique of the breadthwise flowing. At Japanese Patent Laid-Open publication No. 2002-161743, an internal combustion engine in which coolant water is circulated by the technique of lengthwise flowing is disclosed. In this internal combustion engine, a ringed coolant water passage that is formed to surround a plurality of cylinders is provided to the cylinder block. In this case, the coolant water circulates along ringed coolant water passage so as to cool down the plurality of cylinders without distinguishing passage of the exhaust side from the passage of the intake side.

Patent document 1: Japanese Utility Model Laid-Open publication No. 64-34423

DISCLOSURE OF THE INVENTION

Problem to be Solved by the Invention

As described above, it is necessary to provide a cylinder block with two coolant water passages that are independent each other for making coolant water circulate by the technique of the breadthwise flowing. On the other hand, when the technique of the lengthwise flowing is used, it is necessary to provide to the intake side and the exhaust side of the cylinder with coolant water passages which communicates each other so as to be ringed. Thus, cylinder blocks must be manufactured according to a specialized design for adopting the breadthwise flowing or for adopting the lengthwise flowing, respectively.

The present invention has been made to solve the above described problem. It is an object of the present invention to provide an internal combustion engine which can circulate coolant water by the technique of the breadthwise flowing while using a cylinder block that can be converted into for the lengthwise flowing purpose.

Means for Solving the Problem

To achieve the above mentioned purpose, the first invention is an internal combustion comprising:

a cylinder block equipped with a ringed coolant water passage formed so as to surround a plurality of cylinders;

two partitioning members having a larger thermal expansion coefficient as compared to that of said cylinder block, and separating said ringed coolant water passage into first passage existing mainly at one side of a longitudinal bore center plane which extends along the longitudinal direction of said cylinder block and second passage existing mainly at the other side of said longitudinal bore center plane;

an inlet which communicates with said first passage;

an outlet which communicates with said second passage; and

a cylinder head provided with a coolant water passage opening to both said first passage and said second passage, wherein

said cylinder block and said partitioning members are manufactured so that stress acting between both of them in a condition where the internal combustion engine is warmed up does not reach to a breaking stress of said partitioning member.

The second invention is the internal combustion engine according to the first invention, wherein at least one of said cylinder block and said partitioning member includes stress lowering means which absorb by elastically deforming relative dimensional change occurring between the both of them between a cold condition and a warmed up condition.

The third invention is the internal combustion engine according to the first or second invention, wherein a gap is formed between said cylinder block and said partitioning member under a cold condition.

The fourth invention is the internal combustion engine according to any one of the first to third aspects of the present invention, wherein a gap is formed between said cylinder block and said partitioning member under a warmed up condition.

The fifth invention is the internal combustion engine according to any one of the first to fourth aspects of the present invention, wherein said partitioning member comprises a main body having rigidity and an elastic portion attached to said main body.

The sixth invention is the internal combustion engine according to any one of the first to fifth aspects of the present invention, wherein said partitioning member is formed of a base material and a heat conduction material having high heat conductivity as compared to that of the base material so as to show a high heat conductivity as compared to that of the base material itself between said first passage and said second passage.

The seventh invention is the internal combustion engine according to any one of the first to sixth aspects of the present invention, wherein

said inlet is provided in said other side at a vicinity of a longitudinal directional end of said cylinder block, and

one of said two partitioning members is placed in said other side at a place where is closer to the center of the internal combustion engine than a connecting portion of said inlet and said ringed coolant water passage is.

The eighth invention is the internal combustion engine according to any one of the first to seventh aspects of the present invention, wherein

said inlet is provided at a vicinity of one end in a longitudinal direction of said cylinder block,

said outlet is provided at a vicinity of the other end in the longitudinal direction of said cylinder block,

one of said two partitioning members is placed at a vicinity of said inlet, and

the other of said two partitioning members is placed in said one side at a position where is closer to said outlet than an other-end crosswise bore center plane which is perpendicular to said longitudinal bore center plane while extending through a bore center of the cylinder closest to said other end in the longitudinal direction is.

Advantages of the Invention

According to the first invention, coolant water supplied from the inlet can be circulated to the cylinder block from the first passage installed in one side of the cylinder block; further the same can be circulated from the cylinder head to the second passage which is installed in the other side of the cylinder head. Further, the cylinder block employed for the present invention can be converted into a cylinder block for the so-called lengthwise flowing purpose if no partitioning means are attached, because of having the ringed coolant water passage. Additionally, the cylinder block and the partitioning members do not suffer the breaking stress even under a wormed up state, regardless the thermal expansion coefficients of the both are different. Thus, the present invention can circulate the coolant water by the way so-called breadthwise flowing while assuring sufficient durability.

According to the second invention, at least one of the cylinder block and the partitioning members can be elastically deformed. Thus, the present invention can surely prevent the stress acting between the both from reaching the breaking stress of the partitioning members.

According to the third invention, the cylinder block and the partitioning members are formed so that a gap occurs between the both under a cold condition. Because of this, the partitioning members can be easily installed in the cylinder block according to the present invention. A bubble mixed in, for example, when coolant water is interchanged may be remained at the place of the partitioning members. According to the present invention, it is possible to remove such a bubble immediately after cold staring, thereby preventing cooling capability from being deteriorated. Further, the gap discussed above is reduced as warm up advances since the partitioning members get expand. Thus, it is possible to circulate sufficient amount of coolant water through the cylinder head in a warmed up condition since the coolant water amount directly flowing into the second passage from the first passage is reduced enough.

According to the fourth invention, a gap is formed between the cylinder block and the partitioning members in a wormed up condition. The present invention can generate a coolant water current around the partitioning members in the warmed up condition, in addition to implement the effects achieved by the third invention. Thus, the present invention can prevent the partitioning members from being overheated, thereby improving the durability thereof.

According to the fifth invention, the partitioning members include the elastic portion other than the main body having rigidity. Thus, according to the present invention, a change of dimension occurring in the partitioning members due to the difference of the expansion coefficient, or dimension variations of the partitioning members due to fabrication tolerance can be absorbed by the elastic portion.

According to the sixth invention, heat exchange can be effectively caused through the heat conduction material between the first passage and the second passage separated by the partitioning members. Thus, the present invention can effectively prevent the coolant water temperatures of the first passage and the second passage from being largely different each other, while forming the partitioning members using the main body having a low heat conductivity.

According to the seventh invention, the portion of the ringed coolant water passage at which the passage is connected to the inlet can be a part of the first passage in a case where the inlet which should be connected to the first passage is located in the second passage side due to an unavoidable circumstance. Thus, according to the present invention, it is possible to realize an efficient cooling system even under the above described unavoidable circumstance.

According to the eighth invention, the coolant water flowing into the first passage of the cylinder block from a vicinity of an upstream side end (one end) goes through the cylinder head to flow into the second passage, then backs into the cylinder head again at a vicinity of a downstream side end (the other end) so as to flow out from the outlet provided to the cylinder head. According to the present invention, it is possible to extend the second passage so as to largely come around between the end of the cylinder block and the cylinder located at the end. It is necessary that the second passage opens largely to a passage in the cylinder head which communicates with the outlet, in order to assure sufficient ability of coolant water draining. According to the configuration of the present invention, the opening in question can be made large, without taking measures such as expanding the width of the ringed coolant water passage at the vicinity of the above described other end. The present invention, therefore, can provide a sufficient draining ability without increasing the coolant water amount uselessly, thereby improving warming up characteristics of the internal combustion engine.

DESCRIPTION OF REFERENCE NUMERALS

Best Mode For Carrying Out The Invention

First Embodiment

[Configuration of First Embodiment]

FIG. 1Ashows a cylinder block10employed in a first embodiment of the present invention and two partitioning members12,14attached thereon. As shown inFIG. 1A, the cylinder block10has four cylinders #1-#4lining up in series. There is formed around the four one cylinder #1-#4a ringed coolant water passage16which is formed circumferentially to surround all of them. A plurality of head bolt holes18are provided at almost equal intervals further outside of the ringed coolant water passage16.

A cylinder head which is not illustrated is attached to a top of the cylinder block10. The head bolt holes18are used to which head bolts are tighten for fixing the cylinder head. The cylinder head is subjected to combustion pressure of the internal combustion engine. Thus, portions around the head bolt holes18are subjected to great force. If the force is transmitted to walls of the cylinders #1-#4, shape of the walls will be changed. Because of this, the ringed coolant water passage is formed so as to have enough depth so that the force acting around the head bolt holes18is not transmitted to the walls of the cylinders #1-#4directly.

InFIG. 1A, the cylinders #1-#4are provided with intake valves (not shown) placed at back side in the drawing as well as exhaust valves (not shown) placed at front side in the drawing, respectively. Hereinafter, a plane spreading along the longitudinal direction of the cylinder block10and going through the bore centers of the cylinders #1-#4will be called “longitudinal bore center”. Further, across the longitudinal bore center, the back side in the drawing will be called “intake side” while the front side in the drawing will be called “exhaust side”.

A connecting portion20for connecting an inlet of coolant water and the ringed coolant water passage16is provided at the exhaust side of the cylinder #1. Coolant water can be supplied to the ringed coolant water passage16from the connecting portion20through the inlet.

In the present embodiment, two partitioning members12,14are put into the ringed coolant water passage16. The partitioning members12,14have a length corresponding to the depth of the ringed coolant water passage16and a thickness corresponding to the width thereof.

FIG. 1Bshows a state in which the partitioning members12,14are put into the ringed coolant water passage16. As shown inFIG. 1B, one partitioning member12is attached to the ringed coolant water passage16at an end of the cylinder #1side in the longitudinal direction. The other partitioning member14is put into the vicinity of the head bolt hole18provided in the exhaust side (front side in the drawing) near the end of the cylinder #4side. The partitioning members12,14have the length and thickness corresponding to the depth and width of the ringed coolant water passage16, as stated above. Accordingly, the ringed coolant water passage16is substantially separated to two passages when the partitioning members12,14are put on. Hereinafter, among those passages, the passage mainly extending through the front side in the drawing (the exhaust side) is called “first passage22” while the passage mainly extending through the back side in the drawing (the intake side) is called “second passage24”.

A region of the ringed coolant water passage16mainly extending through the exhaust side of the cylinders becomes the first passage22when the partitioning members12,14are put into the position described above. Likely, a region of the ringed coolant water passage16mainly extending through the intake side of the cylinders becomes the second passage24. Further, a region of the ringed coolant water passage16between two head bolts18provided near the cylinder #4side end becomes a part of the second passage24. Hereafter, the region between the two head bolts18is called “come around portion25”.

FIG. 1Cshows an enlarged view of the partitioning member12. As shown inFIG. 1C, the partitioning member12is provided with a rail portion26projecting in a convex shape. A groove of a concave shape corresponding to the rail portion26is formed on the wall of the ringed coolant water passage16at a position where the partitioning member12is attached to. The partitioning member12is inserted into the ringed coolant water passage16so that the rail portion26goes in along the groove.

The cylinder block10is formed of metal such as cast iron or aluminum. On the other hand, the partitioning member12is formed of material having a greater thermal expansion coefficient as compared to the material of the cylinder block10, for example, PP, PA66, PA6, PA66GF33. The assembly of the partitioning member12is performed at room temperature. The partitioning member12is formed so that a gap of a little less than 1 mm is formed between it and the wall when being put into the ringed coolant water passage16under normal temperature.

In the present embodiment, the ringed coolant water passage16has a width of around 6 to 8 mm. Since the gap between the partitioning member12and the wall of the ringed coolant water passage16is of a little less than 1 mm, the ringed coolant water passage16can be assumed to be substantially divided into both sides of the partitioning member12at a time when the internal combustion engine is driven with a requirement of a large amount of circulation of coolant water. It should be noted that the partitioning member12is an element used to substantially close the ringed coolant water passage16partially, and satisfies its requirement when being capable of lowering the effective area of the ringed coolant water passage16to an extent of equal to or less than ⅙, or equal to or less than ⅛ under normal temperature, like in the present embodiment. Further, a member which lowers the effective area of the ringed coolant water passage16to about ¼ may employed as the partitioning member12in the present embodiment depending on ability for coolant water required in the internal combustion engine.

In a warming up process of the internal combustion engine, the partitioning member12expands greatly as compared to the cylinder block10. In a stage in which warming up has completed, the partitioning member12will be exposed to coolant water of around 85 degrees Celsius. In the present embodiment, the partitioning member12is formed so that a gap remains between it and the wall of the ringed coolant water passage16even in such a temperature environment.

[Current of Coolant Water in First Embodiment]

FIG. 2AthroughFIG. 2Care drawings to explain the course of coolant water flowing through the inside of the internal combustion engine according to the present embodiment. In these drawings, a cylinder head28is equipped with on the cylinder block16. Further, the upper part of the cylinder head28is covered by a cylinder-head cover30.

FIG. 2Ashows an exhaust side of the internal combustion engine according to the present embodiment. The cylinder block16has the first passage22in the exhaust side as stated above (seeFIG. 1B). The first passage22extends along the longitudinal direction of the cylinder block16while being connected to the inlet32of coolant water through the connecting portion20at one end thereof.

The cylinder head28is provided with a coolant water passage34having openings which face to the first passage22. The coolant water supplied from the inlet32flows through the first passage22so as to spread out all over one side (the exhaust side) of the cylinder block16, then flowing from all regions of the first passage22into the coolant water passage34, that is, into the cylinder head28.

FIG. 2Bis a drawing which shows a plane view of the internal combustion engine according to the present embodiment. As shown inFIG. 2B, the coolant water passage34is formed so as to cross the cylinder head28in the crosswise direction and communicate with the second passage24of the cylinder block16on the intake side (the left side in the drawing) of the cylinder. Thus, the coolant water flows into the cylinder head28from the cylinder block16on the exhaust side (the right side in the drawing) of the cylinder, then flowing out from the cylinder head28to the cylinder block on the intake side of the cylinder.

FIG. 2Cshows a side view of the intake side of the internal combustion engine according to the present embodiment. The coolant water flowing back from the cylinder head28to the cylinder block16goes through the second passage24so as to spread out all over the other side (the intake side) of the cylinder block24. The second passage24of cylinder block16has the come around portion25which comes around between the cylinder #4and the end of the cylinder block16, as stated above (see,FIG. 1B). The cylinder head28is provided with a draining passage36communicating with the second passage24at the come around portion25. Further, the drain passage28is provided with an outlet38of the coolant water. The come around portion25is located at the most downstream position in the current of the coolant water. Accordingly, the coolant water flowing into from the inlet32circulates through the interior of the cylinder block16and the cylinder head28, and then finally arrives at the come around portion25so as to be drained from the outlet through the drain passage36of the cylinder head28.

As described above, the internal combustion engine according to the present embodiment can circulate coolant water by order of: the exhaust side of the cylinder block → the exhaust side the cylinder head → the intake side of the cylinder head → the intake side of the cylinder block. In other words, this internal combustion engine can circulate coolant water by the technique of so-called breadthwise flowing. Such a breadthwise flowing of coolant water can be also implemented by forming partitions which separate the first passage22of the exhaust side and the second passage24of the intake side integrally with a cylinder block at a stage of such as casting.

However, a bubble may be mixed into coolant water, for example, when it is changed. A bubble once gets to a partition is not readily removed from there, since the partition acts as a member for shutting off the current of the cooking water. In this case, the cooling ability of the internal combustion engine may be deteriorated because of the bubble. The problem of the bubble appears particularly in an internal combustion engine, such as a V-type engine, in which a cylinder block is placed so that cylinders are slanted.

The problem of the bubble described above can be solved, for example, by providing a gap of the extent to permit the flowing through of the bubble to the partition formed from the beginning by casting or the like. On the other hand, such a gap acts as a passage which allows the coolant water flowing through from the first passage22to the second passage24directly. In other words, the gap forms a passage bypassing the coolant water passage in the cylinder head within a coolant water system employing the technique of the breadthwise flowing. Thus, it is desirable that the gap is small in order to improve the cooling efficiency of the cylinder head. Specially, it is desirable that the gap is sufficiently small after completion of warming up when high cooling efficiency is required.

If the partitions which divide the coolant water passage in the cylinder block into two are integrally made in a process of such as casting, the material of the partitions should be the same as the material of the cylinder block body. In a case where a gap is provided to the position of the partitions under such a condition, its size will be almost the same in a cold state or in a warmed up state. Thus, if a gap is increased to raise the removing ability of the bubble, the cooling ability in the warmed up state will be deteriorated, whereas if much value is placed on the cooling ability in the warmed up state, the removable ability of the bubble goes low.

In contrast, forming the partitions separating the coolant water passage with a material having a higher heat expansion coefficient as compared to that of the material of the cylinder block makes it possible that assuring a large gap in a cold state and reducing the gap as warm up process advances. Such partitions are capable of assuring great bubble removing ability in a cold state as well as realizing efficient cooling ability after completion of warming up.

In the present embodiment, therefore, the partitioning members12,14are formed so that the following requirements are satisfied.

First Requirement. Forming the partitioning members12,14with a material (or materials) having a higher heat expansion coefficient as compared to that of the material of the cylinder block10.

Second Requirement. A gap (preferably, of about a little less than 1 mm) is provided between the wall of the coolant water passage16and the partitioning members12,14under normal temperature (at the time of cold staring).

According to the configuration of the present embodiment, the following effect can be obtained since the requirements described above are satisfied.

First Effect. The removing capability of bubbles mixed into coolant water is high.

Second Effect. Cooling capability after completion of warming up can be secured enough.

Moreover, the effect such as follows can be also obtained if the first and second requirements discussed above are satisfied.

Third Effect. Assembly characteristics of the partitioning members12,14to the cylinder block10under normal temperature3will be improved.

Fourth Effect. The Cylinder block10can be used as a block of an internal combustion engine in which the technique so-called lengthwise flowing is employed when one of the partitioning members12,14is not put on, or none of them is put on. The issue of whether to use the lengthwise flowing or the breadthwise flowing as a technique to circulate coolant water will be determined depending on various conditions. The configuration of the present embodiment can vanish the necessity of manufacturing cylinder blocks specialized for use of the lengthwise flowing and cylinder blocks specialized for use of the breadthwise flowing independently, thereby realizing a large amount of cost cut when manufacturing various types of internal combustion engines is a presupposition.

Further, the partitioning member12,14in the present embodiment are subject to the following third requirement as well as the first and second requirement described above.

Third Requirement. A gap remains between the partitioning members12,14and the wall of the ringed coolant water passage16even after completion of warming up.

According to the configuration of the present embodiment, the following effect can be further achieved by being subject to the above described third requirement.

Fifth Effect. A stress is prevented from arising between the partitioning members12,14and the cylinder block10at a stage after completion of warming up. In other words, breaking stress due to thermal expansion is prevented from acting to the partitioning members12,14, whereby the partitioning member12,14obtain enough durability.

Sixth Effect. It is possible to flow appropriate amount of coolant water near the partitioning members12,14at a stage after completion of warming up. In a configuration in which coolant water can not flow near the partitioning members12,14, heat is accumulated near there whereby the partitioning members12,14are apt to be damaged due to overheat. In contrast, in a case where coolant water can circulate near there, it is possible to prevent the heat from accumulating; thereby preventing the partitioning members12,14from being damaged due to overheat.

Although it is described in the first embodiment that gaps remain between the wall of the ringed coolant water passage16and the partitioning members12,14, the present invention is not limited to this. That is, the gap discussed above may vanish at the time of completion of warming up in the extent that breaking stress due to thermal expansion does not occur, if the problem of overheat of the partitioning members12,14due to accumulation of heat does not arise after completion of the warming up.

Further, although the partitioning members12,14are made of a material or materials showing higher heat expansion coefficient as compared to the cylinder block10in the above described first embodiment, the present invention is not limited to this. That is, the partitioning members12,14may be made of a same material as that of the cylinder block10so as to be removable, and may be attached so that an appropriate gap is formed, under a condition in which sufficient bubble removable effect and enough cooling capability can be obtained even if a gap in a cold state is the same as a gap in a warmed up state.

Further, although a gap is formed between the wall of the coolant water passage16and the partitioning members12,14under normal temperature in the above described first embodiment, but the present invention is not limited to this. In a case where the problem of the remaining bubbles will not occur, for example, since cylinders are provided in a vertical state in an internal combustion engine, the partitioning members12,14may be formed of a material same as that of the cylinder block10; further the partitioning members12,14may be attached to the ringed coolant water pa passage16so that no gap is produced.

Next, there will be explained a second embodiment of the present invention, with reference toFIG. 3AandFIG. 3B.FIG. 3Ais a perspective view from a down oblique direction showing a water jacket spacer (W/J spacer)40employed in the present embodiment.FIG. 3Bis a perspective view from an up oblique direction showing the W/J spacer40.

The internal combustion engine according to the present embodiment can be realized by attaching the W/J spacer40to the cylinder block10in substitution for the partitioning members12,14, in the configuration of the first embodiment described above. The W/J spacer40includes a body section42received into the ringed cooling water passage16shown inFIG. 1A. The body part42is provided with two partitioning protrusions44,46. The body part42and the partitioning protrusions44,46are formed of a material same as that of the partitioning members12,14in the first embodiment, that is, a material with a higher heat expansion coefficient as compared to that of the cylinder block10, such as PP, PA66, PA6, PA66GF33.

The body42of the W/J spacer40is constructed so as to reduce the effective area of the ringed coolant water passage16in the whole region at a required rate. More specifically, the body42is formed so that no part of the ringed coolant water passage16is substantially closed. In the first embodiment, the partitioning members12,14are subjected to the requirement of reducing the effective area of the ringed coolant water passage16to less than or equal to one four of the original one. In contrast, the body42does not reduce the effective area of the ringed coolant water passage16to one fourth thereof at any part.

As stated above, the ringed coolant water passage16is given enough depth in order to avoid that the stress acting to the head bolt hole18is undesirably transmitted to the outer wall of the cylinder. As a result, the ringed coolant water passage16may be given surplus volume in some cases compared to the necessary cooling capability. When the ringed coolant water passage16has surplus volume, the amount of circulating water becomes superabundant, which uselessly deteriorates the warming up characteristics of the internal combustion engine while causing problems of increasing the weight of a vehicle idly. Thus, it is desirable that the volume of the ringed coolant water passage16is one which is necessary and sufficient to the required cooling capability.

The body42of the W/J spacer40is an element that was designed to satisfy such a requirement. Thus, when the W/J spacer40is put into the ringed coolant water passage16, the effective volume of the passage can be set to an appropriate amount which corresponds to the required cooling capability while giving enough depth to the passage.

In the W/J spacer40, the partitioning protrusions44,46are constructed so as to satisfy requirements same as those for the partitioning members12,14in the first embodiment. In other words, the partitioning protrusions44,46divide the ringed coolant water passage16into the first passage22and the second passage24like the partitioning members12,14in the first embodiment when the W/J spacer40is put into the passage. The configuration of the present embodiment, therefore, can achieve the same effects which are achieved in the first embodiment.

It should be noted that gaps remain even after completion of the warming up between the wall of the ringed coolant water passage16and the partitioning protrusions44,46in the second embodiment, likewise in the case of the first embodiment, according to the above described explanation. However, the present invention is not limited to this. That is, the gaps discussed above may vanish at the time of completion of warming up in the extent that breaking stress due to thermal expansion does not occur, if the problem of overheat of the partitioning protrusions44,46due to accumulation of heat does not arise after completion of the warming up.

Next, there will be explained a third embodiment of the present invention, with reference toFIG. 4AandFIG. 4B.FIG. 4Ashows the cylinder block10and partitioning members48,50employed in the present embodiment. Further,FIG. 4Bis a perspective view of the partitioning member48used in the present embodiment. The internal combustion engine according to the present embodiment can be realized by replacing the partitioning members12,14with the partitioning members48,50, in the configuration of the first embodiment described above.

As shown inFIG. 4A, the partitioning members48,50are put into the ringed coolant water passage16at positions same as those of the partitioning members12,14in the first embodiment. The ringed coolant water passage16, therefore, is divided into the first passage22and the second passage24(see,FIG. 1B) also in the present embodiment when the partitioning members48,50are attached.

The partitioning member48in the present embodiment includes a main body52with high rigidity and an elastic portion with high elasticity as shown inFIG. 4B. The main body52is formed of PP, PA66, PA6, PA66GF33 or the like as same as the partitioning members12,14in the first embodiment are. On the other hand, the elastic portion54is made of a heat-resisting rubber or the like.

The partitioning member48having the configuration discussed above can be manufactured by, for example, forming an elastic body made of rubber or the like on the formed main body52by injection molding. Alternatively, such a partitioning member48can be manufactured by providing the main body52with a trench and fitting an elastic body made of rubber or the like into the trench. Besides, the partitioning member48in the present embodiment can be manufactured by providing one of the main body52and the elastic portion54with a concave portion while providing the other with a convex portion and fitting them up together.

The elastic portion54is constructed so that its cross section has a rippled shape as shown inFIG. 4B. Further, the partitioning member48in the present embodiment is configured so that mountain parts of the elastic portion54transform slightly when being put into the ringed coolant water passage16under normal temperature. In this case, gaps are secured by valley parts of the elastic portion54between the wall of the ringed coolant water passage16and the partitioning member48.

Even more particularly, the elastic portion54in the present embodiment is configured so that thermal expansion occurring to the partitioning member48during the process of the warming up can be absorbed by deformation of its mountain parts. Thus, according to the configuration of the present embodiment, a gap remains in the vicinity of the partitioning member48while the partitioning member48does not suffer from the breaking stress at the time of completion of the warming up, likewise in the case of the first embodiment.

As described above, the partitioning member48in the present embodiment entirely satisfies the first through third requirements which are imposed on the partitioning members12,14in the first embodiment. The other partitioning member50employed in the present embodiment has a configuration same as that of the partitioning member48. Thus, the configuration of the present embodiment can entirely achieve the effects implemented by the first embodiment.

Even more particularly, the configuration of the present embodiment can prevent the partitioning members48,50from chattering in the ringed coolant water passage16. Thus, the present configuration can improve silent ability of the internal combustion engine as compared to the case of the first embodiment.

It should be noted that although gaps are remained after completion of the warming up between the wall of the coolant water passage16and the partitioning members48,50in the above described third embodiment 3, the present invention is not limited to this. That is, the gaps discussed above may vanish at the time of completion of the warming up in the extent that breaking stress due to thermal expansion does not occur, if the problem of overheat of the partitioning members48,50due to accumulation of heat does not arise after completion of the warming up.

Further, although the main bodies52of the partitioning members48,50are made of a material showing a larger expansion coefficient as compared to that of the cylinder block10in the above described third embodiment, the present invention is not limited to this. That is, the partitioning members48,50may be made of a same material as that of the cylinder block10, under a condition in which sufficient bubble removable effect and enough cooling capability can be obtained even if a gap in a cold state is the same as a gap in a warmed up state.

Further, although the main body is equipped with the elastic portion54of the one face thereof in the above described third embodiment, the present invention is not limited to this. That is, the elastic portion54may be attached to the other side of the main body52. Besides, the elastic portion54may be attached to the both side of the main body52.

Next, a fourth embodiment of the present invention will be described, with reference toFIG. 5.FIG. 5is a perspective view from a down oblique direction showing a W/J spacer56employed in the present embodiment. The W/J spacer56of the present embodiment includes a main body58and partitioning protrusions60,62. The partitioning protrusions60,62are provided with elastic portions64,66, respectively, at positions contacting to the wall of the ringed coolant water passage16. The elastic portions64,66can be attached to the main body58by injection molding, fitting up using a trench, or fitting up using a convex portion and a concave portion, likewise the elastic portion54in the third embodiment. The configuration of the present embodiment is similar to the configuration of the second embodiment except that the elastic portions64,66are attached to the W/J spacer56.

The elastic portions64,66satisfy the same requirements as those for the elastic portion54in the above described third embodiment. As a result, the W/J spacer56of the present embodiment will entirely satisfy the requirements imposed on the W/J spacer40in the second embodiment. Thus, the configuration of the present embodiment can achieve the effects achieved by the configuration of the second embodiment and the effects achieved by the third embodiment entirely.

It should be noted that gaps remain even after completion of the warming up between the wall of the ringed coolant water passage16and the partitioning protrusions60,62in the second embodiment, likewise in the case of the first embodiment, according to the above described explanation. However, the present invention is not limited to this. That is, the gaps discussed above may vanish at the time of completion of warming up in the extent that breaking stress due to thermal expansion does not occur, if the problem of overheat of the partitioning protrusions60,62due to accumulation of heat does not arise after completion of the warming up.

Next, a fifth embodiment of the present invention will be explained, with reference toFIG. 6.FIG. 6is a drawing showing the cylinder block10and partitioning members68,70employed in the present embodiment. The internal combustion engine according to the present embodiment can be realized by replacing the partitioning members12,14with the partitioning members68,70, in the configuration of the first embodiment described above.

The partitioning members68,70in the present embodiment are provided with elastic portions72,74at the top thereof. The elastic portions64,66can be attached by the technique such as injection molding, likewise the elastic portion54in the third embodiment. The configuration of the present embodiment is similar to the configuration of the first embodiment except that the elastic portions72,74are attached to the partitioning members68,70.

A cylinder-head (not shown) is placed on the top of the cylinder block10while a head gasket is placed between them. The more the top face positions of the partitioning members68,70accord with the face of the cylinder block10, the better the contact condition of the head gasket. It is necessary to strictly control the fabrication tolerances of the cylinder block10, (the bodies of) the partitioning members68,70, and the head gasket in order to satisfy the requirement without employing the elastic portions72,74.

In contrast, the fluctuation of face due to the fabrication tolerance can be absorbed by the elastic portions72,74if the elastic portions72,74are attached to the top of the partitioning members68,70. According to the configuration of the present embodiment, therefore, a satisfied contact condition can be obtained at the head gasket without requiring strict control of the fabrication tolerance.

It should be noted that, although the elastic portions72,74which contact to the gasket is applied to the configuration of the first embodiment in the above described fifth embodiment, the present invention is not limited to this. That is, the elastic portions72,74contacting to the gasket can be applied to the configuration according to any one of second through fourth embodiments.

Next, a sixth embodiment of the present invention will be explained, with reference toFIG. 7.FIG. 7is a perspective view of a partitioning member76employed in the present embodiment. The internal combustion engine according to the present embodiment can be realized by replacing the partitioning members12,14with the partitioning member76, in the configuration of the first embodiment described above.

The partitioning member76in the present embodiment includes a main body made of PP or the like and a coating film78formed around the main body. The coating film78is formed of a high heat conduction material such as copper. The partitioning member76can prevent the difference of coolant water temperature or of wall temperature between the first passage22and the second passage24from becoming overmuch.

In particular, internal combustion engines specified for cold region use may be equipped with a heater to warm its engine block at the time of staring. In the above described first embodiment, for example, it is possible to warm the coolant water in the second passage by providing a heater to the intake side of the internal combustion engine. However, it is impossible to effectively warm the coolant water in the first passage22since heat conduction is disturbed by the partitioning members12,14.

In contrast, according to the configuration of the present embodiment, heat can be efficiently exchanged between the first passage22and the second passage24through the coating film78of the partitioning member76. Thus, according to this configuration, it is possible to effectively warm the coolant water in the first passage22and the coolant water in the second passage24together by the heater placed to only one side of the internal combustion engine. Therefore, this configuration can effectively decrease the friction at the time of cold staring; thereby achieving an effect of oil consumption cutting, too.

Further, according to the partitioning member76described above, even in a case where the coolant water can not circulate well around it, it is possible to prevent the coolant water from being overheated locally without modifying the route of the circulation.

FIG. 8throughFIG. 10show alternatives of the partitioning member76, which can be used in the present embodiment. The partitioning member80shown inFIG. 8includes a core member82which penetrates through its maim body and is exposed to the intake side and the exhaust side. The partitioning member84shown inFIG. 9has a similar core member86. In these examples, the core members82,86are made of a high heat conduction material such as copper. Further, the partitioning member88shown inFIG. 10is formed of a material in which carbon nanotubes are orientationally dispersed within a parent material for securing a high thermal conductivity between the intake side and the exhaust side. According to these partitioning members76,80,84,88, the effects like those achieved by the partitioning member76shown inFIG. 7can be achieved.

It should be noted that, although the configuration in which thermal conductivity of the partitioning member is improved is applied to the configuration of the first embodiment in the above described fifth embodiment, the present invention is not limited to this. That is, the configuration in which thermal conductivity of the partitioning member is improved can be applied to the configuration according to any one of second through fourth embodiments.

Referring toFIG. 11, a seventh embodiment of the present invention will be explained next.FIG. 11is a drawing for describing the configuration of the internal combustion engine according to the present embodiment. The internal combustion engine according to the present embodiment includes a cylinder block90. Similar toFIG. 1,FIG. 11shows the cylinder block90so that the front side in the drawing becomes exhaust side of the internal combustion engine and the back side in the drawing becomes intake side of the internal combustion engine.

The cylinder block90has a ringed coolant water passage92which was formed so as to surround four cylinders #1-#4. A connecting portion94to connect an inlet (not shown) of coolant water to the ringed coolant water passage92is provided in the intake side (back side in the drawing) of the cylinder #1. The cylinder block90in the present embodiment differs from the cylinder block10in the first embodiment in the point that the connecting portion94is provided in the intake side as thus described.

The ringed coolant water passage92is equipped with the partitioning members12,14which are similar to those employed in the first embodiment. One partitioning member12is placed near the #1side end portion, while the other partitioning member14is placed near the #4side end portion.

More specifically, the partitioning member12is placed at a position satisfying the following two requirements.

1. Being in the intake side (back side in the drawing) of the longitudinal bore center plane of the cylinder block90.

2. Being at a position where is closer to the engine center96than the connecting portion94communicating with the inlet.

Here, the engine center96means the longitudinal direction center of the cylinder block90, that is, the middle between the cylinder #2and the cylinder #3in the present embodiment.

Further, the partitioning member14is placed at a position satisfying the following two requirements.

1. Being in the exhaust side (front side in the drawing) of the longitudinal bore center plane of the cylinder block90.

2. Being in the outlet side of a crosswise bore center plane of the cylinder which locates nearest to the outlet (the cylinder #4in the present embodiment).

Here, the outlet of the coolant water is provided at the cylinder #4side end surface of the internal combustion engine; and the above described outlet side means the side of the end surface where the outlet is provided. Further, the crosswise bore center plane means a plane which is perpendicular to the longitudinal bore center plane and goes through a bore center of any one of cylinders.

The ringed coolant water passage92is divided into a first passage98extending mainly in the exhaust side (front side in the drawing) and a second passage100extending mainly in the intake side (the back side in the drawing), when being provided with the partitioning members12,14as above. More specifically, the first passage98is formed so as to communicate with the connecting portion94in the intake side of the cylinder #1and extend along the exhaust side of the cylinder #1-#4by coming around the side region of the cylinder #1. On the other hand, the second passage100is formed so as to slightly overlap with the side region of the cylinder #1, extend along the intake side of the cylinders #2-#4, come around the side region of the cylinder #4, and reach to the region of the exhaust side by exceeding the longitudinal bore center plane. Hereinafter, the region exceeding the longitudinal bore center plane to come around into the exhaust side (the region from the longitudinal bore center plane to the partitioning member14) and its symmetrical region in the intake side to the longitudinal bore center plane are totally referred to as “come around portion102”.

In the present embodiment, the cylinder block90is equipped with a cylinder head104thereon. The cylinder head104includes a coolant water passage (not shown) to connect the exhaust side and the intake side, likewise the cylinder head28in the first embodiment (see,FIG. 2A). This coolant water passage becomes communicated with the first passage98in exhaust side and with the second passage100in the intake side when the cylinder head104is put on the cylinder block90. The cylinder head104is also provided with a draining passage which communicates with the come around portion102of the second passage under the above described situation. The draining passage communicates with the outlet installed in the cylinder head104.

In the present embodiment, it shall be required to circulate the coolant water through the internal combustion engine by a technique of the breadthwise flowing directing from the exhaust side toward the intake side. On the other hand, the installation position of the water pump shall be decided to the intake side of the internal combustion engine due to various limitations such as position arrangement of intake pipes or exhaust pipes, installation direction of the internal combustion engine, or the like. Under these requirements and the limitations, it is necessary to make the coolant water taken from the intake side of the internal combustion engine go around into the exhaust side once, and then flow through by the breadthwise flowing technique.

According to the configuration of the present embodiment, the first passage98mainly extending along the exhaust side of the cylinder block90goes around the side region of the cylinder #1so as to communicate with the connecting portion94in the intake side. Thus, according to this configuration, it is possible to make coolant water go around into the exhaust side by simply supplying coolant water to the connecting portion94which is installed in the same side as that of the water pump. That is, according to this configuration, it is possible to make coolant water go around from the intake side to the exhaust side of the cylinder block90without installing further guidance pipes or the like. Thus, the internal combustion engine according to the present embodiment can realize efficient breadthwise flowing of coolant water without being accompanied with the great increase of parts number or production cost under the above described requirements and limitations.

Further, the configuration of the present embodiment can suppress the total volume of the coolant water passage to low level as compared to a case in which a guidance pipe is newly installed to make the coolant water go around from the intake side to the exhaust side. Because of this, the configuration of the present embodiment can reduce the total amount of the coolant water needed in the internal combustion engine, thereby being able to improve the warming up characteristic of the internal combustion engine.

Further, in the configuration of the present embodiment, the partitioning member14of the #4side is placed at the exhaust side of the longitudinal bore center plane, as stated above. As a result, the come around portion102extending largely in the crosswise direction is formed at the side region of the cylinder #4. In other words the configuration of the present embodiment secures the come around portion102having a large surface by making the second passage100go around long toward the crosswise direction at the side region of the cylinder #4without executing measures such as widening the width of the ringed coolant water passage92at the side region of the cylinder #4.

In the present embodiment, the coolant water, which is supplied from the inlet, then arrives at the second passage100, is drained from the draining passage after going through the come around portion102. It is necessary to give a large surface to the come around portion102in order to sufficient coolant water draining ability in this stage. However, if the requirement will be satisfied by enlarging the width of the ringed coolant water passage92in a side region of the cylinder #4, the distance from the cylinder #4to the end portion of the cylinder block90is enlarged, whereby the internal combustion engine is grown in size. Even more particularly, in that case, the total volume of the coolant water passage is enlarged; thereby increasing the coolant water amount contained in the cooling mechanism.

In contrast, according to the configuration of the present embodiment, the internal combustion engine needs not to be grown in size as well as the cooling water amount to be needed is not increased, since there is no need to widen the ringed coolant water passage92. When the coolant water amount can be suppressed to low level, the internal combustion engine can be light weighted, as well as the warming up characteristics of the internal combustion engine can be improved. Because of this, the configuration of the present embodiment can realize an internal combustion engine which is small, light weighted, and outstanding in warming up characteristics.

It should be noted that, although the ringed coolant water passage92is divided into the first passage98and the second passage100by the partitioning member12,14in the first embodiment in the above described seventh embodiment, the present invention is not limited to this. That is, the configuration of partitioning member for separating the first passage98and the second passage100is not limited to the configuration of the first embodiment but may be the configuration of the partitioning member or the partitioning protrusion employed in any one of the second through sixth embodiments.