JP2014194219A - Overcooling prevention member of cylinder bore wall, and internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an overcooling prevention member of a cylinder bore wall, which enhances the uniformity of wall temperature of the cylinder bore wall and is easily insertable in a groove-like cooling water flow passage around the cylinder bore wall, and to provide an internal combustion engine.SOLUTION: An overcooling prevention member is installed in a groove-like cooling water flow passage formed around the cylinder bore wall of a cylinder block of an internal combustion engine and has a contact surface 1 which swells through contact with cooling water of 70°C or more and contacts with the wall surface on a groove-like cooling water flow passage side of the cylinder bore wall.

Description

  The present invention relates to a supercooling prevention member that can be easily installed in a grooved cooling water passage formed around a cylinder bore wall of a cylinder block of an internal combustion engine, and an internal combustion engine including the same.

  In the internal combustion engine, fuel explosion occurs at the top dead center of the piston in the bore, and the piston is pushed down by the explosion, so that the temperature is high on the upper side of the cylinder bore wall and the temperature is lower on the lower side. Therefore, there is a difference in the amount of thermal deformation between the upper side and the lower side of the cylinder bore wall, and the upper side expands greatly, while the lower side expansion decreases.

  As a result, the frictional resistance between the piston and the cylinder bore wall increases, and this is a factor that reduces fuel consumption. .

  Therefore, conventionally, in order to make the wall temperature of the cylinder bore wall uniform, a spacer is installed in the grooved cooling water flow path, and the flow of the cooling water in the grooved cooling water flow path is adjusted so that the cylinder bore wall caused by the cooling water Attempts have been made to control the cooling efficiency on the upper side and the cooling efficiency on the lower side. For example, in Patent Document 1, the groove-shaped cooling heat medium flow path is partitioned into a plurality of flow paths by being arranged in a groove-shaped cooling heat medium flow path formed in a cylinder block of an internal combustion engine. A channel partition member formed at a height less than the depth of the groove-shaped cooling heat medium flow channel, and the bore-side flow channel and the anti-bore side flow channel in the groove-shaped cooling heat medium flow channel And a flow path dividing member that is a wall portion that is divided into the groove-shaped cooling heat medium flow path, and a tip edge portion formed in the groove-shaped cooling heat medium flow direction toward the opening of the groove-shaped cooling heat medium flow path. By being formed of a flexible material so as to extend beyond one inner surface of the medium flow path, the leading edge portion is caused by its own bending restoring force after completion of insertion into the groove-shaped cooling heat medium flow path. Is in contact with the inner surface at an intermediate position in the depth direction of the groove-shaped cooling heat medium channel, and the bore-side channel and the A flexible lip member, the internal combustion engine cooling heat medium flow passage partition member comprising the disclosed which separates the bore side flow path.

JP 2008-31939 A (Claims)

  However, according to the heat medium flow path partition member for cooling the internal combustion engine of the cited document 1, the wall temperature of the cylinder bore wall can be made uniform to some extent, so that the difference in the amount of thermal deformation between the upper side and the lower side of the cylinder bore wall is reduced. In recent years, however, it has been demanded to further reduce the difference in thermal deformation between the upper side and the lower side of the cylinder bore wall. Moreover, since the groove-shaped cooling water flow path formed around the cylinder bore wall has a narrow flow path width, it may be inconvenient for mounting in the flow path.

  Accordingly, an object of the present invention is to provide a cylinder bore wall overcooling prevention member and an internal combustion engine that can increase the uniformity of the wall temperature of the cylinder bore wall and can be easily inserted into a grooved coolant flow path around the cylinder bore wall. It is in.

  As a result of intensive studies to solve the problems in the conventional technology, the present inventors have provided an overcooling prevention member on the cylinder bore wall that swells by contact with water at 70 ° C. or higher in the grooved cooling water flow path. Since the supercooling prevention member is thermally swollen and comes into contact with the cylinder bore wall when the cooling water is passed through, the cooling water is prevented from coming into direct contact with the cylinder bore wall, and the wall temperature of the cylinder bore wall is prevented. It is found that the supercooling prevention member can be made thinner than the groove-shaped cooling water channel width (width of the insertion port), and can be easily mounted in the groove-shaped cooling water channel, The present invention has been completed.

  That is, the present invention is installed in a groove-like cooling water flow path formed around a cylinder bore wall of a cylinder block of an internal combustion engine, and swells by contacting with cooling water of 70 ° C. or higher, An overcooling prevention member for a cylinder bore wall is provided, which has a contact surface in contact with the wall surface of the cylinder bore wall on the grooved coolant flow path side.

  The present invention also provides an internal combustion engine comprising an overcooling prevention member for the cylinder bore wall.

  According to the present invention, the uniformity of the wall temperature of the cylinder bore wall of the internal combustion engine can be increased. Therefore, the difference in the amount of thermal deformation between the upper side and the lower side of the cylinder bore wall can be reduced. In addition, according to the present invention, the supercooling prevention member can be made thinner than the grooved cooling water flow path width, and can be easily mounted in the grooved cooling water flow path.

The perspective view of the overcooling prevention member of the example of 1st Embodiment. The simplified top view at the time of mounting | wearing a groove-shaped cooling water flow path with a supercooling prevention member (before swelling). FIG. 3 is a simplified plan view when the overcooling prevention member expands by contacting with cooling water in FIG. 2. The expanded sectional view of the dashed-two dotted line part shown with the code | symbol Y of FIG. The simplified perspective view of the cylinder block shown in FIG. (A) is a cross-sectional view of a supercooling prevention member taken along the X ₁ -X ₁ line in FIG. 2, cross-sectional view of a supercooling prevention member was cut with X ₂ -X ₂ line in FIG. 3 (B). The front view of the overcooling prevention member of the example of 2nd Embodiment. The rear view of the overcooling prevention member of FIG. It is a figure which shows the installation position of a supercooling prevention member. It is a figure which shows the circumferential direction of a cylinder bore wall. The figure which shows the temperature distribution of the wall surface at the side of the groove-shaped cooling water flow path of the cylinder bore wall in an Example and a comparative example.

  Next, a structure including an overcooling prevention member (hereinafter also simply referred to as “overcooling prevention member”) for the cylinder bore wall according to the first embodiment of the present invention and an internal combustion engine including the structure are shown in FIGS. This will be described with reference to FIG. As shown in FIG. 2 and FIG. 3, a bore 12 for moving the piston up and down and a cooling water flow through the open deck type cylinder block 11 of the vehicle-mounted internal combustion engine where the overcooling prevention member 10 is installed. The groove-shaped cooling water flow path 14 is formed. A wall that divides the bore 12 and the grooved coolant flow path 14 is a cylinder bore wall 13. The cylinder block 11 has a cooling water supply port 15 for supplying cooling water to the grooved cooling water channel 11 and a cooling water discharge port 16 for discharging cooling water from the grooved cooling water channel 11. Is formed.

  The supercooling prevention member 10 is installed in the grooved cooling water flow path 14 and swells by contacting with the cooling water at 70 ° C. or higher, and the wall surface 17 on the grooved cooling water flow path side of the cylinder bore wall 13. The contact surfaces 1a to 1c are in contact with each other. That is, even when the supercooling prevention member 10 is installed in the grooved cooling water flow path 14, the contact surfaces 1 a to 1 c are arranged on the grooved cooling water flow path side of the cylinder bore wall 13 in a state where the cooling water is not passed. It does not need to be in contact with the wall surface 17 and swells by contact with the heated cooling water, and the contact surfaces 1a to 1c come into contact with the wall surface 17 of the cylinder bore wall 13 on the grooved cooling water flow channel side. As a result, the supercooling prevention member can be made thinner than the groove-shaped cooling water channel width, and can be easily mounted in the groove-shaped cooling water channel. In addition, the supercooling prevention member 10 after heating expansion can prevent the cooling water from directly contacting the wall surface of the cylinder bore wall 13 on the groove-like cooling water flow path 14 side.

  The supercooling prevention member 10 is divided into three parts 11 a to 11 c in the present example, and these are fixed (supported) by the resin molding support 2. Each part of the supercooling prevention member 10 is a concave plate-like body along the wall surface shape of the cylinder bore wall 13 on the grooved coolant flow channel 14 side.

  As the overcooling prevention member 10, for example, a thermal expansion material described in JP-A-2004-143262 can be used. The heat-sensitive expansion material is a composite in which a base foam material is impregnated with a thermoplastic material having a melting point lower than that of the base foam material and is compressed, and at room temperature, the compression state is at least due to a cured product of the thermoplastic material existing in the surface layer portion. Examples thereof include those that are held and heated to soften a cured product of the thermoplastic substance and release the compressed state.

  Examples of the base foam material include various polymer materials such as rubber, elastomer, thermoplastic resin, and thermosetting resin. Examples of these polymer materials include natural rubber, CR (chloroprene rubber), SBR (styrene butadiene rubber), NBR (nitrile butadiene rubber), EPDM (ethylene / propylene / diene terpolymer), silicone rubber, fluorine Examples include various synthetic rubbers such as rubber and acrylic rubber, various elastomers such as soft urethane, and various thermosetting resins such as hard urethane, phenol resin, and melamine resin. When synthetic rubber is used, the base foam material is crosslinked. In particular, a base foam material made of a thermosetting resin or a crosslinked rubber is preferable because there is little change in rigidity between normal temperature and heating. A base foam material mainly composed of soft urethane is particularly preferable because it is inexpensive, widely used as a cushioning material, and easily available. Further, even a base foam material made of a thermoplastic resin can be used as a base foam material if its softening temperature is higher than the softening temperature of the thermoplastic substance impregnated therein.

  It is preferable to use a thermoplastic material whose glass transition point, melting point or softening temperature is less than 120 ° C. Some of the above-mentioned base foam materials are deteriorated when heated to 120 ° C. or more for shape recovery and lose elastic restoring force, and do not exhibit shape restoring properties. In addition, since it takes a considerable time to heat the shape memory foam material to 120 ° C. or more for the shape recovery, it is necessary to use a heating device having a high heating capacity. The melting point and glass transition point can be measured by differential scanning calorimetry (DSC). The softening temperature can be measured by an air heating method defined in JIS K 7120.

  Examples of the thermoplastic substance include polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyacrylate, styrene-butadiene copolymer, chlorinated polyethylene, polyvinylidene fluoride, and ethylene-vinyl acetate. Copolymer, ethylene-vinyl acetate-vinyl chloride-acrylic acid ester copolymer, ethylene-vinyl acetate-acrylic acid ester copolymer, ethylene-vinyl acetate-vinyl chloride copolymer, nylon, acrylonitrile-butadiene copolymer , Thermoplastic resins such as polyacrylonitrile, polyvinyl chloride, polychloroprene, polybutadiene, thermoplastic polyimide, polyacetal, polyphenylene sulfide, polycarbonate, thermoplastic polyurethane, low melting glass frit, starch, Various thermoplastic compounds such as solder and wax may be mentioned.

  Any method can be used to impregnate the base foam material with the thermoplastic material, and any method can be used to obtain a shape-memory heat-sensitive expansion material. However, a method in which a thermoplastic material dissolved or dispersed in a solvent is immersed in the base foam material and the solvent is dried is most easily implemented, and is preferable because thermal deterioration of the base foam material hardly occurs. In that case, for example, the base foam material can be impregnated with the thermoplastic material by immersing the base foam material in an emulsion in which the thermoplastic material is dispersed or dissolved in the solvent and drying the solvent. As the solvent, any solvent such as water or an organic solvent can be used. However, it is preferable to use water as the solvent because of low toxicity during drying. In addition, an emulsion in which a thermoplastic resin is dispersed in water is commercially available and is relatively easy to obtain. Therefore, it is preferable as a raw material for the thermoplastic material of the heat-sensitive expansion material according to the present invention. Furthermore, the amount of the thermoplastic substance impregnated into the base foam material can be controlled by appropriately changing the concentration of the thermoplastic substance in the emulsion.

  As the heat-sensitive expansion material, an EPDM rubber containing a thermoplastic substance is particularly preferable. EPDM rubber as a base foam material is preferable in that it is easily cross-linked and has a good balance between price and heat resistance. The thermoplastic substance-containing EPDM rubber expands at about 70 ° C. or more, and its expansion rate is 3 to 5 times.

  The thickness of the supercooling prevention member 10 is appropriately selected according to the material of the supercooling prevention member, the width and size of the grooved cooling water flow path, the temperature and flow rate of the cooling water, etc. 1-6 mm, particularly preferably 2-4 mm. In addition, after expansion, the thickness of the supercooling prevention member 10 and the width of the grooved coolant flow path are determined so that the gap with the cylinder bore wall surface is filled.

  The supercooling prevention member structure includes a supercooling prevention member 10 and a resin molded support 2 that fixes the supercooling prevention member 10. As shown in FIG. 1, the resin-molded support 2 has a corrugated plan view in which one large concave plate-like member 21a and two concave plate-like members 21b and 21c smaller than the plate-like member 21a are connected. The main body 2 has a height smaller than the channel height of the grooved cooling water channel 14. A large supercooling prevention member 10a is fixed to the concave plate-like member 21a, and supercooling prevention members 10b and 10c smaller than the supercooling prevention member 10a are attached to the concave plate-like members 21b and 21c. In other words, the supercooling prevention member 10 of this example is in contact with the majority of the circumferential direction of the middle cylinder bore wall 13 after thermal swelling, and is in contact with about half of the circumferential direction of the cylinder bore walls 13 on both sides after thermal swelling. It is.

  Although it does not restrict | limit especially as a method of fixing the supercooling prevention member 10 to the main-body part 21 of the resin molding support body 2, The method using an adhesive agent is illustrated.

  The thickness of the overcooling preventing members 10a to 10c, which are concave plate-like members, is the total thickness including the resin-molded support 2 after being attached to the resin-molded support 2, and the channel of the groove-shaped cooling water channel 14 Setting the width slightly smaller than the width facilitates mounting on the grooved cooling water flow path 14 and expands after contacting with the cooling water having a temperature of 70 ° C. or higher, thereby causing the grooved cooling water flow in the cylinder bore wall 13 to flow. This is preferable in that it surely comes into contact with the road-side wall.

  The main body portion 21 of the resin-molded support 2 has vertical ribs 22 having a thickness larger than the thickness of the main body portion 21 extending in the height direction at both ends in the left-right direction in FIG. The vertical rib 24 has a thickness greater than the thickness of the main body 21 extending in the height direction and avoiding the overcooling prevention member 10. That is, the middle vertical rib 24 in the left-right direction is not continuous in the up-down direction, and is arranged separately in the upper part and the lower part. The vertical ribs 22 and 24 are located at the center in the circumferential direction of the bore, and can be regulated in the cylinder bore radial direction after being installed in the grooved coolant flow path 14. Moreover, the protrusion part by the side of the cylinder bore wall in the vertical ribs 22 and 24 can narrow the flow path width by the side of the cylinder bore wall 13, and can prevent the deformation | transformation by the flow of the water of the supercooling prevention member 10 which is a rubber material.

  The resin-molded support 2 further has a protrusion 3 that extends upward between the cylinder bores of the main body 21. The protruding portion 3 functions as a knob when the resin-molded support 2 is attached and detached, and has a function of promoting cooling between the two cylinder bore walls (necked portion). The entire resin-molded support body 2 including the protruding portion 3 enters the groove-shaped cooling water flow path 14. The shape of the protruding portion 3 is not particularly limited as long as it is smaller than the thickness of the main body portion 21. However, as shown in FIGS. It becomes easy to pinch with etc. Moreover, the protrusion part 3 can be made into the substantially V-shaped clearance gap between the cylinder bores by having a substantially V-shaped cross-sectional shape, can resist the flow of cooling water, and the installation stability is improved (see FIG. 4). .

Moreover, since the protrusion part 3 is a substantially V-shaped cross-sectional shape which has the right wing part 31 and the left wing part 32 as shown in FIG. 4, the cooling water flow by the side of the cylinder bore wall of the protrusion part 3 can be accelerated. That is, the cooling water (in the direction of the arrow in the figure) is separated into a flow a on the cylinder bore wall side and a flow b on the opposite side of the cylinder bore wall at the tip of the right wing portion 31. The cooling water a ₁ that flows on the cylinder bore side of the right wing portion 31 has a narrow gap between the right wing portion 31 and the cylinder bore wall 13, so that the flow rate becomes large and the cooling of the cylinder bore wall 13 is promoted. Then, the flow of water beyond between the cylinder bores flows directly along the cylinder bore wall 13 (code a _2). Thereby, the cooling effect of the cylinder bore wall 13 on the left wing portion 32 side is not lowered. In the resin-molded support body 2 of this example, the supercooling prevention members 10a to 10c of the main body 21 are arranged in the supercooling prevention region, and the protrusions 3 are arranged in the cooling promotion region. In the resin molding support 2, the arrangement positions of the supercooling prevention members 10a to 10c and the arrangement positions of the protrusions 3 are performed by appropriately setting the height of the main body 21 and the mounting height of the supercooling prevention members 10a to 10c. .

  The internal combustion engine of this example includes a supercooling prevention member 10. That is, in the internal combustion engine of this example, the resin-molded support body 2 to which the supercooling prevention members 10a to 10c are fixed is installed in the grooved cooling water flow path 14 formed around the cylinder bore wall 13 of the cylinder block 11 of the internal combustion engine. It is a thing. In the state where the cooling water is not passed, the supercooling prevention members 10a to 10c are not in contact with the cylinder bore wall surface 17 (FIG. 6A), and after the cooling water is passed, In a state where the temperature has risen, it thermally expands and contacts the cylinder bore wall surface 17 (FIG. 6B). It should be noted that some of the supercooling prevention members 10 a to 10 c may be in contact with the cylinder bore wall surface 17 in a state where the cooling water is not passed. Since the groove width of the groove-shaped cooling water flow path 14 is narrow, it is unavoidably excessive even after the supercooling preventing members 10a to 10c are mounted and before contact with the heated cooling water (before expansion). This is because the contact surfaces 1a to 1c of the cooling preventing members 10a to 10c and the cylinder bore wall surface 17 may come into contact with each other.

  The internal combustion engine of this example includes a piston, a cylinder head, a head gasket, and the like in addition to the cylinder block, the overcooling prevention member, and the fixing member.

  In the internal combustion engine of the present example, the supercooling prevention member of the present invention may be disposed in the whole circumferential direction of the cylinder bore wall. However, workability and thermal expansion when the supercooling prevention member of the present invention is installed. In consideration of the deformation due to the rate, the heat retaining effect due to the water stagnation on the downstream side of the cooling water flow in the installation portion, etc., as shown in FIG. 9, the overcooling prevention of the present invention is partially applied to the circumferential direction of the cylinder bore wall. There may be a portion not covered by the member. In FIG. 9, the blackened portion indicates the installation position (after expansion) of the supercooling prevention member 10. Further, as shown in FIG. 10, the circumferential direction 23 of the cylinder bore wall is a direction surrounding the outer periphery of the cylinder bore wall 13, and in the left-right direction of the cylinder bore wall 13 when the cylinder bore wall 13 is viewed from the side. is there. In addition, in FIG. 9, when arrange | positioning to a part of circumferential direction of one bore wall 17 like the supercooling prevention member 10 of the left end, installation of the projection part 3 as shown in FIG. 1 is abbreviate | omitted. Can do. 10A is a plan view showing only the cylinder bore wall 13 and FIG. 10B is a front view showing only the cylinder bore wall 13.

  In the internal combustion engine of this example, the installation position of the contact surface of the supercooling prevention member of the present invention is an area corresponding to the lower 2/3 of the grooved coolant flow path 14 in the vertical direction of the cylinder bore wall. In the cylinder bore wall, the temperature is high at the top dead center and the temperature is low at the bottom dead center. Therefore, if the region corresponding to the lower 2/3 of the low-temperature groove-like cooling water flow path 14 is kept warm, the wall temperature of the cylinder bore wall Can be made substantially uniform.

  In the conventional internal combustion engine, the lower part of the cylinder bore wall has a lower temperature than the upper part where the fuel explodes, and is thus easily cooled by the cooling water. Therefore, the temperature difference is large between the upper part and the lower part of the cylinder bore wall.

  On the other hand, in the internal combustion engine in which the supercooling prevention member 10 is installed, the supercooling prevention member 10 comes into contact with the cooling water and thermally expands and comes into contact with the cylinder bore wall, so that the cooling water directly contacts the cylinder bore wall 13. Therefore, the temperature of the lower part of the cylinder bore wall 13 can be prevented from becoming too low compared to the upper part. Furthermore, in the internal combustion engine in which the resin-molded support body 2 to which the overcooling prevention member 10 is attached is installed, the lower portion (overcooling) so that the protrusion 3 is located in the upper portion (cooling region) of the cylinder bore wall 13. If the supercooling prevention member 10 is placed in the prevention region), the cooling region can be suitably cooled, and the overcooling prevention region can be suitably prevented from being overcooled. Therefore, the temperature difference between the upper part and the lower part of the cylinder bore wall 13 can be reduced. By these things, the overcooling prevention member of the cylinder bore wall of the present invention can make the wall temperature of the cylinder bore wall uniform and reduce distortion due to thermal deformation of the bore.

  Next, a supercooling prevention member structure including the supercooling prevention member 1d according to the second embodiment will be described with reference to FIGS. 7 and 8, the same components as those in FIGS. 1 to 6 are denoted by the same reference numerals, description thereof is omitted, and different points are mainly described. That is, the structure provided with the supercooling prevention member 10d is different from the structure provided with the supercooling prevention member 10 in that the number of parts of the supercooling prevention member, the shape of the resin molding support, the resin molding support, It is the fixing method of a supercooling prevention member. That is, the structure including the overcooling prevention member 10d includes one part of the overcooling prevention member 10d, a window frame-shaped resin molded support 2b, a metal frame 40, and three belt-shaped clasps 31a. 31b and 32.

  The overcooling prevention member 10d is a concave plate-like body and has the same shape as the overcooling prevention members 10b and 10c. The overcooling preventing member 10d is fitted loosely into a concave metal frame 40 having left and right retaining plates 41 and upper and lower claw-shaped retaining plates 42. Thereby, the overcooling prevention member 10d and the metal frame 40 are integrated. In addition, a band-shaped clasp 32 is fixed to the back surface of the metal frame 40 in the center in the left-right direction in FIG. 8, and the hook-shaped upper end and lower end are outside the upper and lower ends of the metal frame 40. Respectively. Further, in the back surface of the metal frame body 40, band-shaped clasps 31a and 31b are respectively fixed near the ends in the left-right direction in FIG. It extends outward from the upper and lower ends. Further, the window frame-shaped resin molded support 2b has a through hole 50c whose center is slightly larger than the supercooling prevention member 10d, and the upper ends of the three belt-shaped clasps 31a, 31b, 32 at the upper part. Is formed, and a slit 50b is formed at the lower portion for engaging the lower ends of the three belt-like clasps 31a, 31b, 32. Then, the hooks at the upper ends of the three belt-shaped clasps 31a, 31b, 32 are locked to the upper slit 50a, and the hooks at the lower ends of the three belt-shaped clasps 31a, 31b, 32 are moved to the lower slit 50b. By locking, the overcooling preventing member 10d is fixed to the window frame-shaped resin molded support 2b. Thereby, the movement of the radial direction of a cylinder bore and the flow direction of a cooling water can be controlled, and installation stability increases. Such a contact surface (surface) 1d of the overcooling prevention member 10d is located slightly inward from the surface of the metal frame body 40 (indented) before thermal expansion by the heated cooling water. However, the supercooling prevention member 10d is thermally expanded by being installed in the groove-like cooling water flow path 14 formed around the cylinder bore wall 13 of the cylinder block 11 of the internal combustion engine and contacting the hot cooling water. Thus, the contact surface 1d protrudes from the metal frame 40 and comes into contact with the wall surface 17 of the cylinder bore wall 11 on the grooved coolant flow channel 14 side.

  According to the supercooling prevention member structure of the second embodiment, when the supercooling prevention member 10d is inserted into the groove-like cooling water flow path 14, the back surfaces of the hook portions at both ends of the belt-like clasps 31a and 31b. However, since it contacts the wall surface 18 on the opposite side to the cylinder bore wall 13 of the groove-shaped cooling water flow path 14, it may receive frictional resistance, but can be easily inserted. In the internal combustion engine in which the supercooling prevention member 10d is installed, the supercooling prevention member 10d comes into contact with the heated cooling water and thermally expands and comes into contact with the cylinder bore wall, so that the cooling water directly contacts the cylinder bore wall. Therefore, it is possible to prevent the temperature of the lower portion (overcooling prevention region) of the cylinder bore wall from becoming excessively lower than that of the upper portion.

  The supercooling prevention member 10d is not limited to the form shown in FIGS. 7 and 8, and the resin-molded support 2b covers three cylinder bore walls like the resin-formed support 2 in the first embodiment. It may be of a shape that does. In this case, you may have the projection part 3 between bores like the resin-formation body support body 2 of 1st Embodiment. The overcooling prevention member of the present invention may be supported by a metal support. As such a thing, use of the resin formation body support body 2 is abbreviate | omitted in the form of FIG.7 and FIG.8, for example.

EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, this is merely an example and does not limit the present invention.

(Confirmation test for adhesion to wall surface)
A supercooling prevention member having the shape shown in FIGS. 1 to 6 and having the following specifications was prepared. This supercooling prevention member is installed in a groove-like cooling water flow path formed around the cylinder bore wall of the cylinder block with the observation window of the test three-cylinder internal combustion engine having the following specifications as shown in FIG. Water was poured. After flowing the cooling water, whether the supercooling prevention member moves in the flow of the cooling water, whether the contact surface of the supercooling prevention member is in close contact with the wall surface on the grooved cooling water flow path side, continuously, It observed from the observation window. As a result, the supercooling prevention member was installed in the grooved cooling water flow path and then contacted with the cooling water, the temperature increased and expanded, and was sufficiently adhered to the cylinder bore wall. Further, the supercooling prevention member did not move in the flow of the cooling water.

(Overcooling prevention member)
-Thermally-expandable material: an ethylene-propylene-diene copolymer rubber impregnated with a thermoplastic material, which has been confirmed in advance to expand in volume three times by contact with water at 70 ° C.
-Maximum thickness of resin-molded support including overcooling prevention member: 6.4 mm
・ Resin molding support height: 50 mm

(Test internal combustion engine)
-Channel width of grooved cooling water channel; 8.4mm
-Channel height (vertical height) of grooved cooling water channel: 90mm
・ Installation position of the supercooling prevention member: Position where the lower end is 5 mm from the lower side of the grooved cooling water flow path ・ Supply cooling water temperature; 20 to 40 ° C.

(Numerical hydrodynamic analysis results)
After a confirmation test for adhesion to the wall surface, etc., a known computational fluid dynamics analysis was performed under the condition that the cooling water flow was stable. The result is shown in FIG. In FIG. 11, the temperature distribution at the center is that of the cylinder bore wall surface in the middle of the three cylinders, and the temperature distribution on the left and right sides is that of the cylinder bore wall surface adjacent thereto. In FIG. 11, the encircled portion indicated by the symbol A in Example 1 is a portion where the overcooling prevention member is in close contact.

Comparative Example 1
A numerical hydrodynamic analysis was performed in the same manner as in Example 1 except that the use of the supercooling prevention member was omitted. The result is shown in FIG.

Comparative Example 2
In place of the supercooling prevention member, numerical fluid dynamic analysis was performed by the same method as in Example 1 except that 10 g of a flexible lip member (spacer member) described in JP-A-2008-31939 was used. It was. The comparative example 2 restrict | limits the amount of cooling water in the part in which the overcooling prevention member of Example 1 was installed. The result is shown in FIG.

  As is apparent from the results of FIG. 11, Example 1 is 6 to 8 ° C. higher than Comparative Examples 1 and 2 on the wall surface with which the supercooling prevention member is in contact, and prevents overcooling of the wall surface. I understand that. Moreover, in Example 1, the temperature of the wall surface of the cylinder bore wall on the grooved coolant flow channel side is a difference of 5 ° C. in the vertical direction, and is found to be substantially uniform. Moreover, since the thickness of the supercooling prevention member before expansion is smaller than the channel width of the groove-like cooling water channel, it can be easily inserted into the channel.

  According to the present invention, since the difference in deformation amount between the upper side and the lower side of the cylinder bore wall of the internal combustion engine can be reduced, the friction of the piston can be reduced, so that a fuel-saving internal combustion engine can be provided.

DESCRIPTION OF SYMBOLS 1, 1a-1d Contact surface 2 Resin molding support body 3 Protruding part 10, 11a-11d Overcooling prevention member 11 Cylinder block 12 Bore 13 Cylinder bore wall 14 Groove-shaped cooling water flow path 15 Cooling water supply port 16 Cooling water discharge port 17 Cylinder bore Wall surface 18 on the groove-like cooling water flow path side wall surface 21, 21 a to 21 c on the opposite side to the cylinder bore wall of the groove-shaped cooling water flow path Main body portions 22, 24 (of the resin-molded support) Vertical rib 23 Circumferential direction of the cylinder bore wall

That is, the present invention is installed in a groove-like cooling water flow path formed around a cylinder bore wall of a cylinder block of an internal combustion engine, and swells by contacting with cooling water of 70 ° C. or higher, It has a concave contact surface in contact with the wall surface of the cylinder bore wall on the groove-like cooling water flow path side, and is supported by a resin-molded support, which is a part of the entire circumference of the cylinder bore wall, And providing a cylinder bore wall overcooling preventing member having a circumferential length corresponding to at least two adjacent cylinder bore walls, the concave contact surfaces contacting at least two adjacent cylinder bore walls, respectively. Is.

Claims (1)

It is installed in a groove-shaped cooling water flow path formed around a cylinder bore wall of a cylinder block of an internal combustion engine, and swells by contacting with cooling water at 70 ° C. or higher, and groove cooling of the cylinder bore wall An overcooling prevention member for a cylinder bore wall having a contact surface in contact with a wall surface on the water flow path side.

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