JP4158597B2 - Cylinder block manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a cylinder block water jacket is formed for cooling the engine.
[0002]
[Prior art]
FIG. 6A is a schematic cross-sectional view of a general engine. As shown in the figure, a water jacket 3 through which cooling water passes is formed in the cylinder block 2. The water jacket 3 is formed over the entire region in the vertical direction along the cylinder liner 4, and cooling of the engine 1 (especially the cooling of the engine 1 by removing heat from the engine 1 when the cooling water passes through the water jacket 3). In this case, the cylinder block 2 is cooled).
[0003]
By the way, the temperature of the cylinder block 2 reaches a high temperature because it is close to the combustion chamber above the cylinder, but is relatively far from the combustion chamber below the cylinder, and therefore, the temperature is not as high as that above the cylinder. Therefore, in the conventional water jacket structure in which the water jacket 3 is formed below the cylinder liner 4, if the upper part of the cylinder is cooled to an appropriate temperature, it is overcooled below the cylinder and the temperature distribution becomes uneven. . As a result, the cylinder liner 4 is thermally deformed, leading to a decrease in durability and reliability.
[0004]
On the other hand, it is known that by making the water jacket depth shallow, the temperature distribution in the vertical direction of the cylinder liner 4 can be made substantially constant, and thermal deformation of the cylinder liner 4 can be reduced. In this case, it is also known that overcooling of the lower portion of the liner can be suppressed, thereby reducing friction loss.
Patent Document 1 discloses a technique in which the water jacket is shallow. Specifically, a technique is disclosed in which the bottom surface of the water jacket is set at a position substantially corresponding to the piston ring position when the piston is at bottom dead center in order to maintain the cylinder wall surface at a high temperature and reduce friction. ing.
[0005]
[Patent Document 1]
Japanese Patent No. 3171332 [0006]
[Problems to be solved by the invention]
However, in general, the water jacket 3 of the cylinder block 2 is molded by casting, and when the jacket depth of the existing engine 1 is simply shallowed (see FIG. 6B), the casting mold (upper mold and main mold) ) And the jacket core need to be changed, and the stress distribution changes as the structure of the cylinder block 2 changes, which necessitates a new confirmation of durability and reliability, which requires significant costs and man-hours. There is.
[0007]
Further, as a method with relatively few changes, it is conceivable to change only the upper mold of the casting or only the core of the water jacket to reduce the depth of the water jacket 3, but in this case, FIG. As shown in FIG. 4B, there is a problem that the wasteful portion (referred to as meat) 2a increases in the cylinder block 2 by the amount that the water jacket 3 is made shallow, and the weight increases by the amount of the meat 2a.
[0008]
Note that the technique disclosed in Patent Document 1 is not a technique for shallowing a water jacket of an existing engine, but merely a design in which the depth of the water jacket is shallower than that of the conventional one.
The present invention has been in view conceived of the above problems, changes or major equipment were to achieve shallow of water jacket of an existing engine without accompanying cost increase and weight increase, shea cylinder An object is to provide a block manufacturing method.
[0009]
[Means for Solving the Problems]
The cylinder block manufacturing method of the present invention has a cooling water passage communicating with the outside at a lower portion of an engine cylinder block, and the cooling water flows through a water jacket formed in the cylinder block through the cooling water passage. A block manufacturing method comprising: a first step of inserting a mold into the cooling water passage; a second step of filling a bottom portion of the water jacket with a low thermal conductivity material after the first step; It is characterized by comprising a third step of solidifying the low thermal conductivity material after the step, and a fourth step of removing the mold after the third step.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a water jacket structure of an engine according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing the configuration of the main part, where 1 is an engine, 2 is a cylinder block, 3 Is a water jacket formed in the cylinder block 2.
[0011]
Here, the cylinder block 2 shown in FIG. 1 is basically configured in the same manner as the existing cylinder block as described in the section of the prior art. That is, a water jacket 3 is formed over the entire area along the cylinder liner 4 in the cylinder block 2, and cooling of the engine 1 is performed when cooling water passes through the water jacket 3. Yes.
[0012]
By the way, as shown in the drawing, a filler 5 is injected into the bottom of the water jacket 3. The filler 5 is poured into the bottom of the water jacket 3 to make the water jacket 3 shallow.
And by aiming at the shallow bottom of the water jacket 3 with such a structure, the water jacket 3 can be shallowed without almost changing the existing equipment for engine production. Further, by using the filler 5 to make the water jacket 3 shallow, the cooling water does not flow below the water jacket 3, and overcooling of the lower portion of the cylinder liner 4 can be prevented.
[0013]
As shown in FIG. 2, when a hole (cooling water passage) 6 communicating with the outside, such as a water pump (not shown), exists in the lower portion of the water jacket 3, as shown in FIG. The filler 5 is injected after the molding die 7 is inserted from the cooling water passage 6 when the filler 5 is injected. Thereby, as shown in FIG.3 (b), it can prevent that the cooling water channel | path 6 is obstruct | occluded with the filler 5, and the cooling water channel | path 6 can be ensured.
[0014]
By the way, as the filler 5, a material having a smaller heat capacity, a lower thermal conductivity, and a lower specific gravity than the cooling water or the cylinder block 2 is preferable, and specifically, a resin or rubber is preferable. Moreover, if it is resin, it is preferable to use polyamide, a polypropylene, a polyurethane, etc., for example.
Here, FIG. 4 shows the comparison results when the cooling water (coolant) is set to 1 with respect to the specific gravity, heat capacity per unit volume (hereinafter simply referred to as heat capacity), and thermal conductivity of each resin. In addition to the resin materials, characteristic values are also shown for cast iron and aluminum, which are main materials applied to the cylinder block 2.
[0015]
The filler 5 preferably has a smaller specific gravity from the viewpoint of suppressing an increase in the weight of the engine 1 and also preferably has a small heat capacity and thermal conductivity from the viewpoint of preventing overcooling of the lower portion of the liner. On the other hand, in the case of polyamide, polypropylene and polyurethane, the specific gravity is 0.88 to 1.17, which is almost the same as that of cooling water, and even if a resin material is injected, no increase in weight is caused. On the other hand, the specific gravity of cast iron is 7.14, and the specific gravity of aluminum is 2.27. When the bottom of the water jacket 3 is integrally shallow with the cylinder block 2 using metal, that is, FIG. ) Is the same as the case where the bottom is shallowed by the method explained using).
[0016]
Moreover, the heat capacity of each resin is 0.47 to 0.61, which is approximately half the value of cooling water, and is smaller than cast iron (1.07) and aluminum (0.73). Furthermore, the thermal conductivity is also 0.20 to 0.42, which is significantly smaller than 55 of cast iron and 223 of aluminum, and the heat insulation effect is high.
Therefore, in this embodiment, the resin material as described above is applied as the filler 5, and by injecting such resin into the bottom of the water jacket 3, an increase in weight when achieving shallowness is achieved. It suppresses and improves the heat insulation.
[0017]
Since the water jacket structure of the engine according to one embodiment of the present invention is configured as described above, the cylinder block 2 is manufactured and the water jacket 3 is shallowed according to the manufacturing process shown in FIG. 5, for example. It is.
First, as in the prior art, the cylinder block 2 is formed by casting (step S1), and then roughing is performed (step S2). Then, the water jacket 3 is shallowed by processing in steps S3 to S6.
[0018]
That is, a jig is set in step S3. Here, the jig is an upper mold that enters the water jacket 3 from above the cylinder block 2 to a predetermined depth if the water jacket 3 is of an open deck type as shown in FIG. Further, when there is a cooling water passage 6 communicating with the outside, such as a water pump (not shown), in the lower part of the water jacket 3, it is a mold 7 for securing the cooling water passage 6.
[0019]
Next, the resin material 5 is injected into the water jacket 3 (step S4), and solidification processing according to the resin material 5 such as drying, heating, cooling, etc. is performed (step S5). When the solidification process is completed, the jig is removed (step S6), and finishing is performed (step S7).
This finishing process is conventionally performed in the manufacturing process of the cylinder block 2, but in the present embodiment, a finishing process for water jacket shallow bottoming is simultaneously performed in this finishing process. The finishing treatment for water jacket shallowing is specifically deburring of resin. Thereafter, cleaning (step S8), inspection (step S9), and the like are performed, and the process proceeds to the next process (for example, assembly of parts).
[0020]
Therefore, according to the present invention, there is an advantage that the water jacket 3 can be shallowed at a low cost with almost no change in existing engine production equipment. Further, by injecting the filler 5 into the water jacket 3 to achieve a shallow bottom, there is no flow of cooling water below the water jacket 3, and it is possible to prevent downward cooling of the cylinder liner 4. In addition, the temperature distribution in the vertical direction of the cylinder liner 4 can thereby be made substantially constant, and thermal deformation of the cylinder liner 4 can be reduced.
[0021]
Further, by applying a material having a low heat capacity, a low thermal conductivity, and a low specific gravity as the filler 5, there is an advantage that weight increase can be suppressed and heat dissipation can be suppressed.
Further, since no changes are made to the cylinder block 2 itself, structural analysis, strength analysis, and the like associated with shallowing are not required, and durability and reliability are not impaired.
[0022]
Furthermore, the additional process (steps S3 to S6) for shallowing can be easily outsourced (outsourcing), and in this case, there is no need to change the existing engine production equipment at all. There is.
In addition, this invention is not limited to the above-mentioned embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. For example, the injection height of the filler 5 with respect to the depth dimension of the water jacket 3 may be set as appropriate from data obtained from specifications such as engine displacement and data obtained through experiments.
[0023]
【The invention's effect】
As described above in detail, according to Shi cylinder block manufacturing how the present invention, by the material of low thermal conductivity is filled in the bottom portion of the water jacket, easily and inexpensively shallow the water jacket of the engine There are advantages that can be done. In addition, since there is no flow of cooling water below the water jacket and heat dissipation is suppressed, overcooling below the cylinder liner can be prevented, and the temperature distribution in the vertical direction of the cylinder liner can be made substantially constant. Further, this can reduce thermal deformation of the cylinder liner.
[0024]
In addition, since no changes are made to the cylinder block itself, structural analysis and strength analysis associated with shallowing are not required, and durability and reliability are not impaired. Moreover, since only the work (first process to fourth process) for shallowing the water jacket can be outsourced, there is an advantage that it is not necessary to change the engine production equipment so far.
In addition, by using the polyamide, either tree fat polypropylene and polyurethane as the material of low thermal conductivity, can be suppressed weight increase of the engine.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a main configuration of a water jacket structure of an engine according to an embodiment of the present invention.
FIG. 2 is a schematic perspective view of a cylinder block to which a water jacket structure of an engine according to an embodiment of the present invention is applied.
FIG. 3 is a schematic diagram for explaining a manufacturing method of a water jacket structure of an engine according to an embodiment of the present invention.
FIG. 4 is a view for explaining characteristics of a filler applied to a water jacket structure of an engine according to an embodiment of the present invention.
FIG. 5 is a view for explaining a manufacturing process of an engine water jacket structure according to an embodiment of the present invention;
FIG. 6 is a diagram for explaining a conventional technique.
[Explanation of symbols]
1 Engine 2 Cylinder block 3 Water jacket 4 Cylinder liner 5 Filler (resin material)

Claims (1)

A cylinder block manufacturing method having a cooling water passage communicating with the outside at a lower portion of a cylinder block of an engine, wherein the cooling water flows through a water jacket formed in the cylinder block through the cooling water passage,
A first step of inserting a mold into the cooling water passage;
After the first step, a second step of filling the bottom of the water jacket with a material having low thermal conductivity,
After the second step, a third step of solidifying the low thermal conductivity material;
A cylinder block manufacturing method comprising a fourth step of removing the mold after the third step.

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