JP7675983B2 - Engine block and method of manufacturing the engine block - Google Patents

Description

The present invention relates to an engine block and a method for manufacturing an engine block.

In the automotive sector, reducing the weight of cars and improving the efficiency of internal combustion engines remain essential to reducing global carbon dioxide emissions. Improving thermal efficiency requires new technologies that can significantly reduce the energy lost during the combustion process without being converted into power. From the perspective of weight reduction, the mainstream approach to engine weight reduction has been to use light metals such as aluminum alloys and magnesium alloys for engine parts, but the realization of resins is expected to lead to significant weight reductions.

Non-Patent Document 1 discloses an engine with a resin surrounding an iron cylinder liner. The document states that the cooling loss of an engine is reduced when the cylinder liner is surrounded by resin compared to when the cylinder liner is surrounded by aluminum.

Patent documents 1 and 2 disclose an engine block that includes a resin block that surrounds a metal cylinder liner, with a water jacket formed on the cylinder liner.

US Patent Application Publication No. 2015/0159581 US Patent Application Publication No. 2015/0159582

Takahiro Mizuno, Tatsuki Tsuji, Toshio Fujimura, "Prediction of fuel efficiency improvement of SI engines using one-dimensional simulation," Proceedings of the 65th General Meeting and Lecture Conference of the Tokai Branch of the Japan Society of Mechanical Engineers (March 17-18, 2016), No. 163-1

As mentioned above, engines have been proposed that aim to reduce cooling losses by surrounding the cylinder liner with resin, but in recent years there has been a demand for even greater energy efficiency, and new technology was needed to achieve the desired thermal design for such engines.

The objective of the present invention is to realize a technology that realizes a desired thermal design in an engine block equipped with a resin block.

According to the present invention,
an adhesive application step of applying an adhesive to an outer peripheral surface of a cylinder portion having a cylinder liner;
a resin block fixing step of attaching a resin block to the outer peripheral surface of the cylinder portion to which the adhesive is applied;
having
The adhesive application step can provide a method for manufacturing an engine block, in which the adhesive is applied to an area of the outer peripheral surface having a predetermined width in the stroke direction and covering an area of 50% or more in the circumferential direction.
According to the present invention, it is possible to provide an engine block manufactured by the above-mentioned method for manufacturing an engine block.

The present invention provides a technology that allows for the desired thermal design of an engine block equipped with a resin block.

FIG. 2 is an exploded view of an engine block and a cylinder head according to the embodiment. 2A to 2C are diagrams for explaining an example of a manufacturing method for the engine block shown in FIG. 1 . 2A to 2C are diagrams for explaining an example of a manufacturing method for the engine block shown in FIG. 1 . 2A to 2C are diagrams for explaining an example of a manufacturing method for the engine block shown in FIG. 1 . 2A to 2C are diagrams for explaining an example of a manufacturing method for the engine block shown in FIG. 1 . FIG. 2 is a cross-sectional view for explaining an example of details of a cylinder liner and a metal block. FIG. 2 is a vertical cross-sectional view for explaining an example of details of a cylinder liner and a metal block. FIG. 2 is a cross-sectional view for explaining an example of a method for manufacturing the engine block shown in FIG. 1, focusing on an adhesive layer. FIG. 2 is a vertical cross-sectional view for explaining an example of a method for manufacturing the engine block shown in FIG. 1, focusing on an adhesive layer. FIG. 2 is a diagram for explaining an example of the arrangement of adhesive layers in the method for manufacturing the engine block shown in FIG.

The following describes an embodiment of the present invention with reference to the drawings. Note that in all drawings, similar components are given similar reference numerals and descriptions are omitted where appropriate.

Figure 1 is a perspective view of an engine block 10 according to an embodiment. In this figure, the cylinder head attached to the upper side of the engine block 10 is omitted, and only the gasket 28 is shown.

<Engine block 10 overview>
An overview of an engine block 10 will be described with reference to Figure 1. The engine block 10 includes a cylinder liner 120 and a resin block 200. For convenience, the resin block 200 is shown painted black in Figure 1. The following describes an example of the engine block 10 for a two-cylinder engine.

The resin block 200 includes a first portion 210 and a void 230. The first portion 210 covers the metal outer peripheral surface 122 of the cylinder liner 120. The void 230 is located outside the first portion 210 and defines a water jacket 232.

The above-described configuration can reduce damage to the resin block 200 caused by heat generated from the cylinder liner 120.

Specifically, in the above-described configuration, the first portion 210 of the resin block 200 is surrounded by the water jacket 232. The coolant (e.g., water) flowing through the water jacket 232 can reduce thermal damage to the first portion 210 of the resin block 200.

<Engine block 10>
The engine block 10 will be described in detail with reference to FIG.
The engine block 10 includes a block member 110 , a cylinder liner 120 , a metal block 140 , a projection 130 , and a resin block 200 .

The block member 110 is made of metal (e.g., cast iron, aluminum alloy, or magnesium alloy). In the example shown in FIG. 1, the block member 110 functions as a base for supporting the resin block 200.

The cylinder liner 120 is attached to the block member 110. The cylinder liner 120 may be integral with the block member 110 or may be attachable and detachable to the block member 110.

The cylinder liner 120 is made of a metal (e.g., iron or aluminum). The cylinder liner 120 has an outer peripheral surface made of metal (i.e., the metal outer peripheral surface 122).

The metal block 140 is part of the block member 110, and is provided in a cylindrical shape so as to cover the metal outer peripheral surface 122 of the cylinder liner 120. The cylindrical shape may be a single block or a structure in which multiple blocks are connected together. A resin block 200 is provided so as to cover the block outer peripheral surface 142 of the metal block 140. Note that the metal block 140 may be omitted and the resin block 200 may be provided directly on the cylinder liner 120.

The protrusion 130 protrudes from the block member 110 toward the cylinder head (or the gasket 28). The protrusion 130 has an opening 132. The fastener 22 can be inserted into the opening 132. The fastener 22 secures the cylinder head to the engine block 10 by sandwiching the gasket 28. The fastener 22 can be, for example, a bolt.

<Resin block 200>
The resin block 200 includes a first portion 210, a second portion 220, and a gap 230. The second portion 220 is located outside the gap 230. The gap 230 is between the first portion 210 and the second portion 220. The first portion 210 and the second portion 220 are integrated with each other in a lower portion of the resin block 200.

The first portion 210 of the resin block 200 is attached to the block outer peripheral surface 142 of the metal block 140, for example, via an adhesive layer 300 (see FIG. 4). The adhesive of the adhesive layer 300 is located between the first portion 210 of the resin block 200 and the block outer peripheral surface 142 of the metal block 140, and bonds the first portion 210 of the resin block 200 and the block outer peripheral surface 142 of the metal block 140 to each other. The adhesive may function as a stress relief layer.

The first portion 210 of the resin block 200 may be integrally joined to the block outer peripheral surface 142 of the metal block 140 without the use of adhesive. In this case, a direct bond between the resin (resin block 200) and the metal (metal block 140) is formed at the interface between the first portion 210 of the resin block 200 and the block outer peripheral surface 142 of the metal block 140.

The resin block 200 has an upper surface 202. The upper surface 202 has a groove that forms a void 230, and the void 230 is exposed from the block member 110. In such a structure, thermal damage to the resin block 200 at the upper end of the cylinder liner 120 and its vicinity can be particularly reduced. Therefore, the above-mentioned structure is particularly useful when the temperature of the metal block 140 and the cylinder liner 120 particularly rises at their upper ends and their vicinity. Furthermore, in the above-mentioned structure, the void 230 can be formed not only before the resin block 200 is attached to the metal block 140, but also after the resin block 200 is attached to the metal block 140. Therefore, the degree of freedom in the process for forming the void 230 can be increased.

The void 230 may not be exposed from the top surface 202 of the resin block 200, and may be present inside the resin block 200. Even in this case, the refrigerant flowing through the water jacket 232 can reduce thermal damage to the first portion 210 of the resin block 200.

The second portion 220 has an opening 222. The resin block 200 is positioned so that the protrusion 130 passes through the opening 222 of the second portion 220. The protrusion 130 can function as a guide for attaching the resin block 200 to the block member 110.

<Materials and Properties of Resin Block 200>
The first portion 210 and the second portion 220 of the resin block 200 contain a cured product of a thermosetting resin. In other words, the resin block 200 is made of a thermosetting resin. The resin block 200 may further contain an inorganic filler (e.g., glass fiber). The resin block 200 may contain, for example, 50% by weight or more of the inorganic filler with respect to the total weight of the resin block 200. The thermosetting resin forming the resin block 200 may be, for example, a phenolic resin.

The thermal conductivity of the thermosetting resin forming the resin block 200 can be low, for example, 1.00 W/m·K or less. This low thermal conductivity can reduce the cooling loss of the engine block 10.

The density of the thermosetting resin forming the resin block 200 can be made small, for example, 2.2 g/cm ³ or less. The small density allows the weight of the engine block 10 to be reduced.

The glass transition point of the thermosetting resin forming the resin block 200 can be high, for example, 160°C or higher, and preferably 200°C or higher. The high glass transition point allows the engine block 10 to be used at high temperatures.

The linear expansion coefficient of the thermosetting resin forming the resin block 200 can be made equal to or close to the linear expansion coefficient of the metal forming the block outer peripheral surface 142 of the metal block 140. For example, the machine direction (MD) linear expansion coefficient of the thermosetting resin forming the resin block 200 may be 75% to 125% of the MD linear expansion coefficient of the metal forming the metal block 140, and the transverse direction (TD) linear expansion coefficient of the thermosetting resin forming the resin block 200 may be 75% to 125% of the TD linear expansion coefficient of the metal forming the metal block 140. By making the linear expansion coefficient of the thermosetting resin forming the resin block 200 and the linear expansion coefficient of the metal forming the metal block 140 equal to or close to each other, the stress from the metal block 140 to the resin block 200 when both the metal block 140 and the resin block 200 are heated can be alleviated.

The MD linear expansion coefficient of the thermosetting resin forming the resin block 200 and the MD linear expansion coefficient of the metal forming the metal block 140 can each be, for example, 10 ppm or more and 40 ppm or less.

The TD linear expansion coefficient of the thermosetting resin forming the resin block 200 and the TD linear expansion coefficient of the metal forming the metal block 140 can each be, for example, 10 ppm or more and 40 ppm or less.

If the metal block 140 is omitted and the resin block 200 is provided on the cylinder liner 120, the linear expansion coefficient of the thermosetting resin can be set to the above value in relation to the cylinder liner 120.

<Method of Manufacturing Engine Block 10>
2 to 5 are diagrams for explaining an example of a method for manufacturing the engine block 10 shown in FIG.

An example of a manufacturing method for the engine block 10 will be outlined with reference to Figures 2, 3, and 5. First, as shown in Figure 2, a base block 100 is formed. The base block 100 has a cylinder liner 120 and a metal block 140. The cylinder liner 120 has a metal outer circumferential surface 122. The metal block 140 surrounds the cylinder liner 120. Next, as shown in Figure 3, the base block 100 is processed to remove a portion of the metal block 140 so that the thickness of the metal block 140 is reduced. If the metal block 140 before processing has the desired thickness, no processing to remove the portion is necessary. Next, as shown in Figure 5, the metal block 140 is surrounded by a resin block 200.

According to the above-mentioned process, the manufacturing process for surrounding the metal block 140 and the cylinder liner 120 with the resin block 200 can be realized at low cost. Specifically, in the above-mentioned process, the base block 100 including the metal block 140 can be formed using existing equipment for forming an existing engine block (e.g., a mold used for casting to form an existing engine block). In other words, even when a portion of the metal block 140 is removed, it is not necessary to provide new equipment for forming the base block 100 from which the metal block 140 has been removed. Therefore, the manufacturing process for surrounding the metal block 140 and the cylinder liner 120 with the resin block 200 can be realized at low cost.

An example of a method for manufacturing the engine block 10 will be described in detail with reference to FIGS.
First, as shown in Fig. 2, a base block 100 is formed. The base block 100 has a block member 110, a cylinder liner 120, and a metal block 140. Each of the block member 110, the cylinder liner 120, and the metal block 140 is made of metal. In particular, the metal block 140 is made of, for example, cast iron, an aluminum alloy, or a magnesium alloy.

The base block 100 has a gap 150 between the cylinder liner 120 and the metal block 140. The gap 150 defines a water jacket 152. The base block 100 can be formed using existing equipment for forming an existing engine block (i.e., an engine block having a water jacket 152). In one example, the base block 100 can be formed by casting, or more specifically, die casting. In this example, the mold used for die casting can be the mold for forming the existing engine block.

The base block 100 further has an opening 132. As described with reference to FIG. 1, the fastener 22 (FIG. 1) can be inserted into the opening 132. The base block 100 includes a portion that forms the protrusion 130 shown in FIG. 3. This portion forms the protrusion 130 in the step shown in FIG. 3 (the step of removing the metal block 140).

Next, as shown in FIG. 3, a portion of the metal block 140 is removed from the base block 100 to reduce its thickness. In the example shown in FIG. 3, the metal block 140 is processed to reduce its thickness around the cylinder liner 120, and is removed so that a protrusion 130 is formed and an opening 132 remains.

Next, as shown in FIG. 4, an adhesive layer 300 is formed on the block outer peripheral surface 142 of the metal block 140. As shown in FIG. 4, the adhesive layer 300 may also be formed on the outer peripheral surface of the protrusion 130. As the adhesive for the adhesive layer 300, for example, a high heat dissipation one-component condensation type RTV silicone adhesive sealant (heat transfer coefficient: 0.83 W/mk) can be used.

Next, as shown in FIG. 5, the resin block 200 is fitted so as to surround the metal block 140. The resin block 200 is attached so that the protrusion 130 passes through the opening 222 of the resin block 200. The first portion 210 of the resin block 200 and the block outer peripheral surface 142 of the metal block 140 are bonded to each other via the adhesive layer 300, and the inner surface of the opening 222 of the resin block 200 and the outer peripheral surface of the protrusion 130 are bonded to each other via the adhesive layer 300.

The adhesive layer 300 does not have to be formed. If the adhesive layer 300 is not formed, the first portion 210 of the resin block 200 may be integrally joined to the block outer peripheral surface 142 of the metal block 140 without the use of adhesive.

In the example shown in FIG. 5, the resin block 200 includes a first portion 210, a second portion 220, and a void 230. The void 230 defines a water jacket 232. The void 230 may be formed before surrounding the metal block 140 with the resin block 200, or may be formed after surrounding the metal block 140 with the resin block 200.

The manufacturing method of the engine block 10 is not limited to the examples shown in Figures 2 to 5. The engine block 10 may be manufactured as shown in the following examples.

First, the block shown in FIG. 3 (block member 110, cylinder liner 120, and protrusion 130) may be formed without forming the base block 100 shown in FIG. 2. The block shown in FIG. 3 can be formed by casting, or more specifically, by die casting. In this example, the mold used for die casting has a shape that corresponds to the block shown in FIG. 3.

Secondly, the engine block 10 may be manufactured by insert molding. In this example, the block shown in FIG. 3 (block member 110 (metal block 140), cylinder liner 120, and protrusion 130) is placed in a mold, and resin for forming the resin block 200 is supplied into the mold. According to this example, the resin block 200 can be directly bonded to the metal block 140 without providing the adhesive layer 300 shown in FIG. 4.

<Cylinder liner 120 and metal block 140>
6 and 7 are cross-sectional views for explaining an example of details of the cylinder liner 120 and the metal block 140. Fig. 6 shows a cross section of the cylinder liner 120 and the metal block 140. Fig. 7 shows a cross section of the cylinder liner 120 and the metal block 140.

The cylinder liner 120 includes an iron layer 120a and an aluminum layer 120b. The iron layer 120a forms the inner peripheral surface of the cylinder liner 120. The iron layer 120a includes at least one of iron and an iron alloy. The aluminum layer 120b is located outside the iron layer 120a and forms the metal outer peripheral surface 122. The aluminum layer 120b includes at least one of aluminum and an aluminum alloy.

The metal block 140 is arranged to surround the aluminum layer 120b of the cylinder liner 120.

The surface roughness Ra (arithmetic mean roughness) of the block outer surface 142 of the metal block 140 can be, for example, 0.2 μm or more and 3.0 μm or less.

The block outer peripheral surface 142 of the metal block 140 may be free of protrusions having tip angles of less than 90°. Such protrusions may become areas of thermal stress concentration in the metal block 140 and the resin block 200, and may cause cracks in the resin block 200. If there are no such protrusions, cracks in the resin block 200 can be reduced.

<Arrangement of adhesive layer 300>
With reference to Figures 8 and 9, the process of attaching the resin block 200 to the metal block 140 in the above-mentioned manufacturing method of the engine block 10 will be described, focusing particularly on the arrangement of the adhesive layer 300. Figure 8 is a horizontal cross-sectional view illustrating the process of providing the adhesive layer 300 to the metal block 140 and attaching the resin block 200. Figure 9 is a vertical cross-sectional view illustrating the process of providing the adhesive layer 300 to the metal block 140 and attaching the resin block 200. Figure 9(a) is a cross-sectional view taken along X1-X1 in Figure 8(a), Figure 9(b) is a cross-sectional view taken along X2-X2 in Figure 8(b), and Figure 9(c) is a cross-sectional view taken along X3-X3 in Figure 8(c).

As shown in Figures 8(a) and 9(a), a metal block 140 is prepared in a state immediately before the resin block 200 is attached. This state corresponds to the metal block 140 shown in Figure 3 above, and the metal block 140 surrounds the periphery of the two cylinder liners 120 arranged side by side to a predetermined thickness.

Next, as shown in Figures 8(b) and 9(b), in the adhesive application process, adhesive is applied to a predetermined area of the block outer circumferential surface 142 of the metal block 140 to provide an adhesive layer 300. The resin block 200 and the metal block 140 having the cylinder portion 20 can be reliably bonded together, and heat transfer between the resin block 200 and the metal block 140 can be achieved as designed.

At this time, the adhesive layer 300 is provided on the block outer peripheral surface 142 in an area of a predetermined width in the stroke direction, covering at least 50% of the area in the circumferential direction, preferably at least 60%, and more preferably at least 70%. This ensures that the metal block 140 and the resin block 200 are bonded together reliably.

As shown in the figure, when the cylinder section 20 (here, the metal block 140) has a seating surface 149 against which the bottom surface 209 of the resin block 200 abuts, it is not necessary to apply adhesive to the seating surface 149. By not providing adhesive to the seating surface 149, it is possible to avoid a situation in which the upper end portions of the cylinder section 20 and the resin block 200 are misaligned due to the thickness of the adhesive layer 300 when fastening the cylinder head, which would result in inability to fasten them properly.

The adhesive is applied to the block outer peripheral surface 142 in a plurality of separate locations in the circumferential direction. That is, the adhesive layer 300 is provided in a plurality of separate locations in the circumferential direction. When the circumferential areas of the adhesive layers 300 at the plurality of locations are added together, the total area in the circumferential direction is 50% or more, as described above. At this time, it is preferable that the intervals between the adhesive layers 300 are constant. The intervals between the adhesive layers 300 function as air spaces when the resin block 200 is attached. The air space has a thermal resistance Rt that is generally large, unlike that of the adhesive layer 300. Therefore, by appropriately adjusting the arrangement of the adhesive layer 300 and the area of the area, the heat retention performance and heat dissipation performance in each area of the cylinder section 20 can be set as desired. As a result, an engine having such an engine block 10 can achieve improved energy utilization efficiency.

The adhesive is applied to an area of 50% or less of the block outer peripheral surface 142 in the stroke direction, with a predetermined width in the stroke direction. In other words, the adhesive layer 300 is applied to an area of 50% or less of the block outer peripheral surface 142 in the stroke direction. For example, it is preferable that the length L2 in the stroke direction of the area where the adhesive layer 300 is provided is 50% or less of the length L1 in the stroke direction of the block outer peripheral surface 142.

On the block outer peripheral surface 142, adhesive 165 is applied to an area within at least 20% of the stroke direction from the top dead center TDC side. In other words, an adhesive layer 300 is provided over an area of at least 50% of the circumferential direction within at least 20% of the stroke direction from the top dead center TDC side.

Figure 10 shows two different examples of the arrangement of the adhesive layer 300 in the stroke direction. The adhesive layer 300 shown in Figure 9 is provided as one mass in the stroke direction. Figure 10 (a) shows an example in which the adhesive layer 300 is divided into multiple regions in the stroke direction, specifically, three regions. Each adhesive layer 300 has the same width in the stroke direction. The interval between the adhesive layers 300, that is, the region that becomes an air layer when the resin block 200 is attached, can be the same as the width of the adhesive layer 300, for example. Figure 10 (b) shows an example in which the width of the adhesive layer 300 is wide on the top dead center TDC side and narrow on the bottom dead center BDC side in multiple (here, three) regions in the stroke direction. As with the above-mentioned circumferential direction, the arrangement of the adhesive layer 300 and the area of the region can be appropriately adjusted in the stroke direction to set the heat retention performance and heat dissipation performance in each region of the cylinder section 20 as desired.

8(c) and 9(c), in the resin block fixing process, the resin block 200 is attached to the outer peripheral surface of the cylinder section 20 (here, the block outer peripheral surface 142 of the metal block 140) to which the adhesive 165 has been applied and the adhesive layer 300 has been provided. This results in the engine block 10 shown in FIG. 1 and FIG. 5. By providing an area where the adhesive is not applied (i.e., an area where the adhesive layer 300 is not provided) in the adhesive application process, an air layer is provided between the block outer peripheral surface 142 and the resin block 200 without any adhesive when the resin block 200 is attached to the block outer peripheral surface 142 of the cylinder section 20 in the resin block fixing process. The air layer has a higher thermal resistance Rt (i.e., a lower thermal conductivity) than the adhesive layer 300.

The above describes an embodiment of the present invention with reference to the drawings, but these are merely examples of the present invention, and various configurations other than those described above can also be adopted. For example, in the above embodiment, an example was described in which the resin block 200 was applied to a two-cylinder engine (engine block 10), but the resin block 200 can be applied to a single-cylinder engine or an engine with three or more cylinders regardless of the number of cylinders.

10 engine block 20 cylinder head 100 base block 110 block member 120 cylinder liner 120a iron layer 120b aluminum layer 122 metal outer peripheral surface 140 metal block 142 block outer peripheral surface 149 seating surface 150 gap 152 water jacket (cooling water passage)
200 Resin block 209 Bottom surface 210 First portion 220 Second portion 230 Gap 232 Water jacket (cooling water channel)
300 Adhesive layer

Claims (8)

an adhesive application step of applying an adhesive to an outer peripheral surface of a cylinder portion having a cylinder liner;
a resin block fixing step of attaching a resin block to the outer peripheral surface of the cylinder portion to which the adhesive is applied;
having
the adhesive application step applies the adhesive to an area of a predetermined width in a stroke direction on the outer peripheral surface, the area being 50% or more in the circumferential direction, and the adhesive is applied to a plurality of locations in the stroke direction;
In the adhesive application step, a region where the adhesive is not applied is provided between the adhesive applied to a plurality of locations in the stroke direction , so that in the resin block fixing step, in a state where the resin block is attached to the outer circumferential surface of the cylinder portion, an air layer where no adhesive is present is provided between the outer circumferential surface of the cylinder portion and the resin block.
A method for manufacturing an engine block. The method for manufacturing an engine block according to claim 1, wherein the adhesive application process applies the adhesive in multiple locations in the circumferential direction. The method for manufacturing an engine block according to claim 1 or 2, wherein the adhesive application step applies the adhesive to an area of the outer circumferential surface that is 50% or less of the stroke direction as the predetermined width. The method for manufacturing an engine block according to claim 3, wherein the adhesive application process applies the adhesive to an area within at least 20% of the stroke direction from the top dead center side. The method for manufacturing an engine block according to claim 4, wherein the adhesive application step applies a larger amount of adhesive to an area within at least 20% of the stroke direction from the top dead center than to the other areas. The method for manufacturing an engine block according to any one of claims 1 to 5, wherein, when the cylinder portion has a seating surface on which the resin block sits when the resin block is attached to the cylinder portion, the adhesive application step does not apply the adhesive to the seating surface. The cylinder portion includes a cylinder block made of a metal material and a cylinder liner provided in the cylinder block,
The outer circumferential surface to which the adhesive is applied is the outer circumferential surface of the cylinder block.
A method for manufacturing an engine block according to any one of claims 1 to 6. An engine block manufactured by the method for manufacturing an engine block according to any one of claims 1 to 7.

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