JP5812530B2 - Water jacket spacer - Google Patents

Description

  The present invention relates to a water jacket spacer that is inserted into a water jacket formed in a cylinder block of a water-cooled engine for an automobile and regulates the flow rate of cooling water flowing through the water jacket.

  In such a cylinder block, a water jacket is formed around the cylinder bore wall, and cooling water (including cooling water mixed with antifreeze liquid) is circulated through the water jacket to cool the heated cylinder bore wall. (See Patent Document 1 and Patent Document 2). In Patent Document 1, the difference in cooling efficiency of the bore wall at the cooling water inlet portion and the cooling water outlet portion is eliminated, and further, the difference in the cooling efficiency of the bore wall at the portion between adjacent bore holes and other portions is eliminated. Various shapes of water jacket spacers for preventing the bore holes from being deformed unevenly have been proposed. Patent Document 2 proposes water jacket spacers of various shapes that are improved for the purpose of shortening the time until the warm-up operation is completed.

Japanese Patent No. 3596438 JP 2006-90195 A

  Recently, as a reciprocating engine for automobiles, an engine in which a piston operates in a vertical direction (hereinafter referred to as a vertical engine) such as a serial type or a V type, or an engine in which a piston operates in a horizontal direction (hereinafter referred to as a horizontal engine). Is used). The engines shown in Patent Document 1 and Patent Document 2 are all vertical engines. In the case of a vertical engine, the upper part of the water jacket is close to the combustion chamber, and the temperature difference between the upper part and the lower part of the cooling water flowing through the water jacket tends to increase. In Patent Document 1, the water jacket spacer is basically positioned on the bottom wall side of the water jacket so that the circulation amount of the cooling water on the upper side is increased. Therefore, it is expected that the cooling water cooling effect becomes excessive during the warm-up operation, and the desired warm-up operation is not smoothly performed. Further, in Patent Document 2, the structure of the water jacket spacer itself is devised in order to shorten the time until the warm-up operation is completed. However, the structure is complicated and the cost is expected to increase.

  On the other hand, in the case of a horizontal engine, the cylinder axis is in a horizontal state, and the combustion chamber side and the anti-combustion chamber side (crankshaft side) are positioned in the horizontal direction. There is no temperature difference between the upper part and the lower part of the vertical engine. In the case of such a horizontal engine, the cooling water inlet (water supply port) is provided on the lower outer wall of the water jacket, and the outlet (drainage) is provided on the upper outer wall. The cooling water flowing into the water jacket circulates around the cylinder bore wall from the lower part to the upper part of the water jacket and is discharged from the drain outlet. In such a horizontal engine, when the specific gravity of the water jacket spacer is larger than the specific gravity of the cooling water, the water jacket spacer sinks close to the outer wall on the lower side of the water jacket near the water supply port. The distance from the cylinder bore wall becomes wider. For this reason, the cooling water having a low temperature flowing in from the water supply port easily goes around the widened interval portion. When a large amount of low-temperature cooling water flows into this portion, the lower cylinder bore wall may be supercooled, and smooth warm-up operation may not be achieved.

  The present invention has been made in view of the above, and an object of the present invention is to provide a water jacket spacer that has a simple structure, that can properly cool the cylinder bore wall with cooling water, and that also has a heat insulation function and a sound insulation function.

A water jacket spacer according to the present invention is a water jacket spacer that is inserted and assembled into a water jacket of a cylinder block, and adjusts the flow rate of cooling water flowing through the water jacket, and is provided in the water jacket. A spacer base that is loosely inserted and formed into a cylindrical shape along the shape of the spacer base. The spacer base has a specific gravity smaller than the specific gravity of the cooling water, and at least a part thereof is made of a synthetic resin foam. When the spacer base member is inserted into the water jacket and assembled, the spacer base member floats with respect to the cooling water so that the spacer base member abuts on the inner wall located in the upward direction among the inner walls surrounding the water jacket. Among the inner walls surrounding the water jacket, there is a gap between the lower inner wall and It wants, characterized in that it is formed to be the specific gravity.

  The water jacket spacer according to the present invention is assembled by being inserted into the water jacket of the cylinder block. Thereby, the capacity of the cooling water circulated in the water jacket is adjusted. Further, since the specific gravity of the spacer base body, which is the main body of the water jacket spacer, is smaller than the specific gravity of the cooling water, any one of the spacer bases that floats on the cooling water and surrounds the water jacket in the water jacket. A part of the inner wall is in contact with or close to the inner wall located in the flying direction (vertical direction). As a result, the position of the water jacket spacer within the water jacket is determined, the cooling water circulation state is stabilized, and the intended cooling water cooling function is exhibited. Furthermore, since the spacer base is at least partially made of a synthetic resin foam, it can be manufactured inexpensively and easily, and the temperature rise outside the cylinder block or the generation of noise due to heat insulation or sound absorption characteristics. Can be suppressed.

In the present invention, when the spacer base body is inserted into the water jacket and assembled, it floats against the cooling water, so that the inner wall surrounding the water jacket is abutted against the inner wall positioned upward. On the other hand, the gap between the inner wall surrounding the water jacket and the inner wall positioned in the downward direction is formed so as to have a specific gravity that increases . Therefore, the gap between the spacer base and the inner wall located in the downward direction of the water jacket is widened, so that a circulation area of the cooling water is secured and the circulation state of the cooling water is stabilized.

In the present invention, the cylinder block constitutes a horizontal engine, and the spacer base body floats with respect to the cooling water when inserted and assembled in the water jacket, thereby the spacer It is good also as what is formed so that the clearance gap between a base | substrate and the lower outer wall of the said water jacket may spread, and it may become the specific gravity which can narrow the clearance gap with an upper outer wall. In this case, it is desirable that the cylinder block is provided with a cooling water supply port at a lower portion and a drain port at an upper portion. According to this, in the lower part of the water jacket into which the low-temperature cooling water is introduced, the gap between the spacer base and the lower outer wall is widened, so that the gap between the spacer base and the cylinder bore wall is narrowed. Thus, the amount of cooling water flowing between the cylinder bore wall and the spacer base is suppressed, and overcooling of the cylinder bore wall temperature is prevented. On the other hand, in the upper portion of the water jacket, the gap between the spacer base and the upper outer wall is narrowed, that is, the gap between the spacer base and the upper cylinder bore wall is widened, and the cooling in which the temperature rises due to circulation in the water jacket. Water stays in this widened gap to keep the cylinder bore wall in this area warm. Such a circulation state of the cooling water contributes to an improvement in fuel consumption in this type of horizontal engine.

In the present invention, the cylinder block constitutes a vertical engine, and the spacer base body floats with respect to the cooling water when inserted and assembled in the water jacket, thereby the spacer The gap between the base and the bottom wall of the water jacket is widened, and it is formed so as to have a specific gravity that abuts on a cylinder head gasket interposed between the cylinder head and the cylinder head fastened to the upper end of the cylinder block. good. According to this, the spacer base body is floated by the cooling water and comes into contact with the cylinder head gasket constituting a part of the inner wall of the water jacket, so that it is stably maintained in a state where the gap between the spacer base and the bottom wall is widened. The As a result, the spacer base is positioned, and the intended distribution of the heat transfer coefficient within the water jacket is accurately maintained.

  In the present invention, when the cylinder block constitutes a vertical engine, the lower part of the spacer base may be configured to have a specific gravity greater than that of the upper part of the spacer base. According to this, the said floating attitude | position in the water jacket of a spacer base | substrate is stabilized more.

In the present invention, as described above, the following modes may be adopted as a configuration mode when there is a specific gravity difference between the lower part and the upper part of the spacer base.
a) The entire spacer base is made of a synthetic resin foam, and the foaming ratio of the upper part of the spacer base is higher than the foaming ratio of the lower part.
b) The upper portion of the spacer base is made of a synthetic resin foam, and the lower portion is made of a synthetic resin non-foam.
Further, in any one of a) and b), the upper portion and the lower portion of the spacer base may be formed separately and integrated later.
Since these are mainly made of synthetic resin foam, the amount of raw materials used is small and lightweight, and molding can be done easily, which can be supplied at low cost and contribute to improving the fuel efficiency of the engine. To do. And it is excellent also in heat insulation and sound insulation, and the temperature rise outside a cylinder block or generation | occurrence | production of noise can be suppressed more effectively.

  According to the water jacket spacer according to the present invention, the structure is simple, the cylinder bore wall is accurately cooled by the cooling water, the heat insulation function and the sound insulation function are provided, and the suitability as a constituent member of the automobile engine is improved. .

It is a schematic perspective view which shows the whole shape of 1st Embodiment of the water jacket spacer of this invention. It is sectional drawing in the cut surface orthogonal to a piston axis | shaft which shows an example of the cylinder block of the horizontal engine in which the water jacket spacer of the embodiment is assembled | attached. FIG. 3 is a cross-sectional view taken along line X-X in FIG. 2. It is a schematic perspective view which shows the whole shape of 2nd Embodiment of the water jacket spacer of this invention. It is sectional drawing in the cut surface orthogonal to a piston axis | shaft which shows an example of the cylinder block of the vertical engine in which the water jacket spacer of the embodiment is assembled | attached. FIG. 6 is a cross-sectional view taken along line YY in FIG. 5. It is the same figure as FIG. 6 which shows the modification of the embodiment. It is a figure similar to FIG. 6 which shows the other modification of the embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of a water jacket spacer according to the present invention. The water jacket spacer 1 is inserted and assembled into a water jacket 3 of a cylinder block 2 as shown in FIG. The illustrated cylinder block 2 constitutes an open deck type two-cylinder horizontal (horizontally opposed) engine, and includes two cylinder bores 4 arranged in series. A series of water jackets 3 are formed in an annular shape around the cylinder bore wall 4a of the two cylinder bores 4 as viewed from the side. A cylinder liner 4b is lined on the inner periphery of each cylinder bore wall 4a (see FIG. 3, not shown in FIG. 2). The cylinder bore wall 4 a constitutes the inner wall of the water jacket 3. A cooling water supply port 3a communicating with the water jacket 3 is formed on the lower side of the cylinder block 2, and a drainage port 3b is formed on the upper side. The cooling water supplied from the water supply port 3a is indicated by an arrow a. It circulates through the water jacket 3 while being circulated, and a part is sequentially discharged from the drainage port 3b. In the illustrated example, two water supply ports 3 a and two water discharge ports 3 b are formed, but one may be formed between the cylinder bores 4 and 4.

  As shown in FIG. 3, the cylinder head 5 is fastened to the side of the cylinder block 2 via a cylinder head gasket 6 (not shown). In this fastened state, the combined surface of the cylinder block 2 and the cylinder head 5 is Sealed by the cylinder head gasket 6. The open end of the water jacket 3 is watertightly closed by the cylinder head gasket 6, and the cylinder head gasket 6 constitutes a part of the inner wall of the water jacket 3. 2a... Are female screw holes for bolts (not shown) for fastening the cylinder head 5 to the cylinder block 2. The cylinder block 2 is manufactured, for example, by casting aluminum alloy or the like, and the cylinder bore 4 and the water jacket 3 are formed by a male part of a mold. In particular, the male part corresponding to the water jacket 3 requires a certain thickness in order to ensure the strength of the mold, and therefore the groove width of the formed water jacket 3 may be larger than necessary. . Therefore, the water jacket spacer 1 is inserted into the water jacket 3 and the substantial capacity of the cooling water flowing through the water jacket 3 is adjusted.

  The water jacket spacer 1 of the present embodiment has a cylindrical base shape that can be loosely inserted into the water jacket 3, and has a spacer base body 10 made of a synthetic resin independent foam. The water jacket spacer 1 shown in the figure is composed only of the spacer base 10, and the specific gravity of the spacer base 10 is set to be smaller than that of the cooling water. The peripheral surface of the spacer base 10 may be provided with a protrusion or the like for restricting the circulation of the cooling water. Even when such a protrusion or the like is provided, the overall specific gravity is made smaller than that of the cooling water. . As the synthetic resin foam constituting the spacer base 10, a foam made of a synthetic resin such as polyamide resin (PA66, PPA), polyphenylene sulfide resin (PPS), or polypropylene resin (PP) is preferably employed. For example, in the case of a polyamide resin (PPA), the specific gravity of the solid is 1.47. When a foaming agent 1 g is added to this solid 332 g, and a foaming agent 2 g is added to 276 g, the foam is molded into a predetermined shape while being foamed. Foams with specific gravity of 1.04 and 0.86 are obtained. Cooling water (LLC) mixed with antifreeze is used as cooling water for automobile engines, and the specific gravity varies depending on the specifications of LLC, but is adjusted to about 1.075. Therefore, the amount of the foaming agent is adjusted so that the specific gravity of the foam is less than 1.075.

  The spacer base 10 configured as described above is inserted into the water jacket 3 from its opening end as shown in FIGS. FIG. 3 shows a state in which the spacer base 10 is inserted into the water jacket 3 and the cylinder head 5 is fastened to the cylinder block 2 via the cylinder head gasket 6. Then, cooling water is supplied into the water jacket 3 from the water supply port 3a, and the water jacket 3 is filled with the cooling water. Thus, in the state where the cooling water is filled in the water jacket 3, the spacer base 10 floats with respect to the cooling water due to the difference in specific gravity between the spacer base 10 and the cooling water (see thick arrows in FIG. 3). The levitation is performed such that the gap d1 between the spacer base 10 and the lower outer wall (inner wall) 30 on the lower side of the water jacket 3 is widened and the gap d3 between the upper outer wall (inner wall) 31 is narrowed. As a result, the gap d2 between the cylinder bore wall (inner wall) 4a on the lower side of the water jacket 3 and the spacer base 10 is narrowed, and this gap d2 portion of the low temperature cooling water flowing into the water jacket 3 from the water supply port 3a. Is prevented from overcooling the cylinder bore wall 4a. Further, the gap d3 between the outer wall 31 and the spacer base 10 in the upper part of the water jacket 3 is narrowed, and thereby the gap d4 between the cylinder bore wall (inner wall) 4a in the upper part of the water jacket 3 and the spacer base 10 is widened. . The cooling water whose temperature has risen through circulation in the water jacket 3 has a longer residence time in the widened gap d4, and keeps the cylinder bore wall 4a in this portion warm. Accordingly, it is possible to maintain an appropriate temperature of the cylinder bore wall 4a, the warm-up operation is efficiently performed, and the fuel efficiency of the automobile engine is improved. In addition, since the spacer base 10 made of the foam of the cooling water and the synthetic resin in the water jacket 3 exists between the cylinder bore 4 and the outside of the cylinder block 2, the heat and sound generated in the cylinder bore 4 are exposed to the outside. Leakage is suppressed. In particular, the closed foam has excellent sound absorption characteristics and is effective in preventing noise generation.

FIG. 4 shows the overall shape of the second embodiment of the water jacket spacer of the present invention. FIG. 5 shows an example of a cylinder block of a vertical (series type, V type) engine to which the water jacket spacer of the embodiment is assembled, and FIG. 6 shows a cross-sectional view taken along the line YY in FIG. The water jacket spacer 1A is inserted and assembled into a water jacket 3 of a cylinder block 2A as shown in FIG. The illustrated cylinder block 2A constitutes an open deck type three-cylinder engine (corresponding to one side of a six-cylinder engine in the case of the V type), and includes three cylinder bores 4 arranged in series. ing. A series of water jackets 3 are formed in an annular shape around the cylinder bore wall 4a of the three cylinder bores 4 in plan view. A water supply port 3a for cooling water communicating with the water jacket 3 and a water discharge port 3b are formed on one side of the cylinder block 2A, and the cooling water supplied from the water supply port 3a is supplied to the water jacket as indicated by an arrow b. It distribute | circulates through the inside of 3 and it is comprised so that one part may be discharged | emitted sequentially from the drain port 3b. As shown in FIG. 6, a cylinder head 5A is fastened to the upper surface of the cylinder block 2A via a cylinder head gasket 6A. In this fastened state, the combined surface of the cylinder block 2A and the cylinder head 5A is held by the cylinder head gasket 6A. Sealed. The open end of the water jacket 3 is watertightly closed by the cylinder head gasket 6 </ b> A, and the cylinder head gasket 6 </ b> A constitutes a part of the inner wall of the water jacket 3.
Since the other configuration relating to the cylinder block 2A is the same as the example shown in FIGS. 2 and 3, the same reference numerals are given to the common parts and the description thereof is omitted.

  The water jacket spacer 1 </ b> A of the present embodiment has a cylindrical shape that can be loosely inserted into the water jacket 3, and has a spacer base 10 made of a molded body of an independent foam made of synthetic resin. The water jacket spacer 1A shown in the figure is also composed of only the spacer base 10 in the same manner as described above. However, even if the peripheral surface of the spacer base 10 is provided with a protrusion or the like for restricting the flow of cooling water. good. As the synthetic resin foam constituting the spacer base 10, a synthetic resin foam having a specific gravity smaller than that of the cooling water is used as described above. Furthermore, the spacer substrate 10 of the water jacket spacer 1A of the present embodiment is made of the synthetic resin foam having the same expansion ratio throughout, and the lower portion 10a of the spacer substrate 10 is formed thicker than the upper portion 10b. Yes.

  As shown in FIGS. 5 and 6, the spacer base 10 configured as described above is inserted into the water jacket 3 formed in the cylinder block 2 </ b> A from its open end. FIG. 6 shows a state in which the cylinder head 5A is fastened to the cylinder block 2 in which the spacer base 10 is inserted into the water jacket 3 via the cylinder head gasket 6A. Then, cooling water is supplied into the water jacket 3 from the water supply port 3a, and the water jacket 3 is filled with the cooling water. Thus, in the state where the cooling water is filled in the water jacket 3, the spacer base 10 floats with respect to the cooling water due to the difference in specific gravity between the spacer base 10 and the cooling water (see thick arrows in FIG. 6). This floating is performed such that a gap d5 between the spacer base 10 and the bottom wall (inner wall) 32 of the water jacket 3 is widened, and the upper end is in contact with the cylinder head gasket 6A. By this contact, the spacer base 10 is positioned in the vertical direction within the water jacket 3, and the intended cooling effect by the cooling water is exhibited accurately. Moreover, the flow path of the cooling water is ensured by widening the gap d5. Further, since the spacer base 10 is made of a closed cell synthetic resin foam, the heat insulation and sound insulation effects are also exhibited as described above. In addition, in this embodiment, since the lower part 10a of the spacer base 10 is formed thicker than the upper part 10b, a wide space is secured between the upper part 10b of the spacer base 10 and the cylinder bore wall 4a. The flow rate of the cooling water is increased, and this portion close to the combustion chamber is effectively cooled.

FIG. 7 shows a modification of the second embodiment. In the water jacket spacer 1A of this example, the spacer base 10 is entirely made of a synthetic resin foam as in the example of FIG. 6, but the foaming ratio of the upper part 10b is made higher than the foaming ratio of the lower part 10a. Yes. As a result, the lower portion 10a is set to have a higher specific gravity than the upper portion 10b, and the specific gravity of the entire spacer base 10 is smaller than that of the cooling water as described above. The spacer base 10 can be formed integrally by simultaneously molding the upper part 10b and the lower part 10a, but the upper part 10b and the lower part 10a are individually molded and fixed together by an adhesive or the like. It is also possible to do. The spacer base body 10 in this example is also inserted into a water jacket 3 formed in the vertical cylinder block 2A, and the cylinder head 5A is fastened to the upper end portion of the cylinder block 2A via a cylinder head gasket 6A. When the inside of the water jacket 3 is filled with the cooling water, the spacer base 10 floats with respect to the cooling water due to the difference in specific gravity between the spacer base 10 and the cooling water (see thick arrows in FIG. 7). This floating is also performed so that a gap d5 between the spacer base 10 and the bottom wall (inner wall) 32 of the water jacket 3 is widened, and the upper end is in contact with the cylinder head gasket 6A. By this contact, the vertical positioning of the spacer base 10 in the water jacket 3 is performed, and the flow path of the cooling water is secured by the widening of the gap d5, and the intended cooling effect by the cooling water is accurately exhibited. . Further, since the lower portion 10a of the spacer base 10 is set so that the specific gravity is larger than that of the upper portion 10b, the floating posture in contact with the cylinder head gasket 6A is stabilized, and the intended cooling effect is more accurate. To be demonstrated.
Since other configurations are the same as those in the example shown in FIG. 6, the same reference numerals are given to common portions, and descriptions thereof are omitted.

FIG. 8 shows another modification of the second embodiment. In the water jacket spacer 1A of this example, the upper portion 10b of the spacer base 10 is made of a synthetic resin foam, and the lower portion 10a is made of a synthetic resin non-foam. As a result, the lower portion 10a is set to have a higher specific gravity than the upper portion 10b. However, as a whole, the specific gravity of the spacer base 10 is lower than that of the cooling water. The spacer base 10 can be formed integrally by simultaneously molding the upper part 10b and the lower part 10a, but the upper part 10b and the lower part 10a are individually molded and fixed together by an adhesive or the like. It is also possible to do. The spacer base body 10 in this example is also inserted into a water jacket 3 formed in the vertical cylinder block 2A, and the cylinder head 5A is fastened to the upper end portion of the cylinder block 2A via a cylinder head gasket 6A. When the inside of the water jacket 3 is filled with the cooling water, the spacer base 10 floats with respect to the cooling water due to the specific gravity difference between the spacer base 10 and the cooling water (see the thick arrow in FIG. 8). This floating is also performed so that a gap d5 between the spacer base 10 and the bottom wall (inner wall) 32 of the water jacket 3 is widened, and the upper end is in contact with the cylinder head gasket 6A. By this contact, the spacer base 10 is positioned in the vertical direction within the water jacket 3, and the intended cooling effect by the cooling water is accurately exhibited. Further, since the spacer base 10 is set such that the specific gravity of the lower portion 10a is larger than that of the upper portion 10b, the floating posture in contact with the cylinder head gasket 6A is stabilized, and the intended cooling effect is exhibited. It is made more accurate.
Since other configurations are the same as the example shown in FIGS. 6 and 7, common portions are denoted by the same reference numerals, and description thereof is omitted.

  In addition, all the cross-sectional shapes of the spacer base | substrate 10 of an example are shown typically, and are not limited to these. Also, in the example shown in FIGS. 4 to 6, the upper portion 10b and the lower portion 10a of the spacer base 10 may be formed separately, and the spacer base 10 may be configured integrally with an adhesive or the like later. Furthermore, in the example shown in FIGS. 4 to 6, the thickness of the upper portion 10b and the lower portion 10a is made different, but the overall cross-sectional shape may be the same as that of the spacer base 10 as shown in FIG. As an engine to which the water jacket spacer of the present invention is applied, a two-cylinder horizontal engine and a three-cylinder vertical engine (6 cylinders in the case of the V type) are exemplified. It is also applicable to. Accordingly, it goes without saying that the overall shape of the water jacket spacer is appropriately changed according to the engine specifications.

1,1A Water jacket spacer 10 Spacer base 10a Lower part 10b Upper part 2,2A Cylinder block 3 Water jacket 3a Water supply port 3b Drain port 30 Lower outer wall (inner wall)
31 Upper outer wall (inner wall)
32 Bottom wall (inner wall)
5,5A Cylinder head 6,6A Cylinder head gasket d1-d5 Clearance

Claims (8)

A water jacket spacer that is inserted and assembled into a water jacket of a cylinder block and adjusts the flow rate of cooling water flowing through the water jacket,
It includes a spacer base that is loosely inserted into the water jacket and is formed in a cylindrical shape along the shape of the spacer base. The spacer base has a specific gravity smaller than the specific gravity of the cooling water, and at least a part thereof is synthesized. Ri Do from foam resin,
When the spacer base body is inserted into the water jacket and assembled, the spacer base body floats with respect to the cooling water, so that the spacer base body abuts on or is close to the upper inner wall surrounding the water jacket. On the other hand, the water jacket spacer is characterized by having a specific gravity in which a gap between the inner wall surrounding the water jacket and the inner wall located in the downward direction is widened . The water jacket spacer according to claim 1,
When the spacer base body is inserted into the water jacket of the cylinder block constituting the horizontal engine and assembled, the spacer base body floats with respect to the cooling water, so that the spacer base body and the lower side of the water jacket are positioned below. A water jacket spacer, wherein the water jacket spacer is formed so as to have a specific gravity such that a gap between the outer wall and the upper outer wall is narrowed . The water jacket spacer according to claim 2,
A water jacket spacer, wherein a cooling water supply port is provided at a lower portion of the cylinder block, and a drain port is provided at an upper portion . The water jacket spacer according to claim 3,
When the spacer base body is floated with respect to the cooling water when inserted into the water jacket of the cylinder block constituting the vertical engine and assembled, the spacer base body and the bottom wall of the water jacket The water jacket spacer is formed to have a specific gravity that abuts on a cylinder head gasket interposed between the cylinder block and the cylinder head fastened to the upper end of the cylinder block . The water jacket spacer according to claim 4 ,
A water jacket spacer , wherein the lower portion of the spacer base is configured to have a specific gravity greater than that of the upper portion of the spacer base . The water jacket spacer according to claim 5,
The entire spacer base is made of a synthetic resin foam,
The water jacket spacer according to claim 1 , wherein an expansion ratio of the upper portion of the spacer base is higher than an expansion ratio of the lower portion . The water jacket spacer according to claim 5 ,
The water jacket spacer according to claim 1 , wherein the upper portion of the spacer base is made of a synthetic resin foam and the lower portion is made of a synthetic resin non-foam . In the water jacket spacer according to any one of claims 5 to 7 ,
A water jacket spacer , wherein the upper portion and the lower portion of the spacer base are individually formed and integrated later .

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