JP2016089673A - Engine structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine structure for performing good heat transport to cooling water and oil while enhancing the thermal efficiency of an engine.SOLUTION: The engine structure includes a cylinder liner 51 forming a combustion chamber 10, and a water jacket 26 in which cooling water distributes, the cylinder liner 51 having heat-conductivity anisotropy such that the heat conductivity in the vertical direction along the center line thereof is greater than the heat conductivity in the thickness direction perpendicular to the vertical direction, the water jacket 26 being provided so that the cooling water distributes through a position near the upper end of the cylinder liner 51.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an engine structure.

  In recent years, a technique for improving the fuel efficiency by reducing the cooling loss by insulating the combustion chamber and thereby improving the thermal efficiency of the engine has been studied. For example, Patent Document 1 discloses an engine structure including a cylinder liner formed of a carbon fiber reinforced resin composite material (CFRP / Carbon Fiber Reinforced Plastics). This engine structure is intended to suppress engine noise and is not intended to directly reduce the engine cooling loss. However, according to this engine structure, since the cylinder liner is formed of the carbon fiber reinforced resin composite material having low thermal conductivity, heat dissipation to the cylinder block is suppressed. As a result, it contributes to a reduction in cooling loss of the engine and, in turn, an improvement in thermal efficiency.

JP 59-49352 A

  However, in the engine structure of Patent Document 1, since the heat radiation to the cylinder block is suppressed, the temperature rise of the cooling water and oil (cooling fluid) flowing outside the cylinder liner is also prevented. For this reason, for example, in a cold district, there is a possibility that the heating function using the heat energy of the cooling water may be adversely affected.

  The present invention has been made in view of the circumstances as described above, and provides an engine structure capable of satisfactorily transporting heat to a cooling fluid such as cooling water or oil while increasing the thermal efficiency of the engine. For the purpose.

  In order to solve the above problems, the present invention provides an engine structure including a combustion chamber forming member having a combustion chamber forming surface that forms a combustion chamber, and a fluid passage through which a cooling fluid flows. The member has a thermal conductivity anisotropy in which the thermal conductivity in the first direction along the combustion chamber forming surface is larger than the thermal conductivity in the second direction orthogonal to the combustion chamber forming surface, and the fluid passage includes The cooling fluid flows at least in the vicinity of the end portion of the combustion chamber forming portion in the first direction.

  According to this engine structure, since the combustion chamber forming member has the above-described heat conduction anisotropy, heat generated in the combustion chamber is directed exclusively toward the end of the fluid passage along the combustion chamber forming member. Therefore, the heat radiation from the combustion chamber forming member to the outside (the second direction outside) is suppressed. Therefore, while maintaining the combustion chamber at a high temperature and improving the thermal efficiency of the engine, it is possible to efficiently transport the heat to the cooling fluid flowing in the fluid passage and to raise the temperature of the cooling fluid satisfactorily.

  In this engine structure, the combustion chamber forming member may be formed of a material having the heat conduction anisotropy, or a plurality of members, that is, an inner member having the combustion chamber forming surface, and the second direction. The outer member located outside the inner member and having a lower thermal conductivity than the inner member may be used.

  In the former, the combustion chamber forming member is configured using the characteristics of the material itself, and in the latter, the combustion chamber forming member is configured with a plurality of members having different thermal conductivities. For any engine structure, it is possible to satisfactorily enjoy the above-described operational effects.

  In the former structure, the combustion chamber forming member is formed of a main portion formed of the carbon fiber reinforced resin composite material having thermal conductivity anisotropy and a metal material to form the combustion chamber forming surface. A structure having a reinforcing portion is preferable.

  According to this structure, it is possible to increase the strength of the entire combustion chamber forming member while imparting thermal conductivity anisotropy to the combustion chamber forming member using the carbon fiber reinforced resin composite material.

  In the engine structure, the combustion chamber forming member is connected to the main body having heat conduction anisotropy and to the main body at a specific position in the first direction so that heat can be transferred from the main body to the cooling unit. It is preferable to include a heat induction part that transfers heat to the fluid.

  According to this engine structure, the heat moving in the first direction by the combustion chamber forming member can be more efficiently transmitted to the cooling fluid in the fluid passage. Note that “connected to enable heat transfer” means that the main body part and the heat induction part are integrally formed of the same material, and that the main body part and the heat induction part are individually formed and contact each other. It is meant to include both cases where the heat transfer is possible.

  In this case, it is preferable that the heat induction part forms a wall surface of the fluid passage.

  According to this engine structure, since the contact area between the heat induction portion and the cooling fluid is increased, heat can be more efficiently transferred to the cooling fluid.

  In the engine structure described above, it is preferable that the fluid passage is provided only at a position near one end of the combustion chamber forming member in the first direction.

  According to this engine structure, it is possible to suppress excessive heat transfer (increase in cooling loss) to the cooling fluid. Moreover, since the volume of the cooling fluid in the fluid passage is reduced, it is possible to raise the temperature of the cooling fluid with a small amount of heat. Such a structure is particularly useful in a low heat capacity type engine having a relatively small calorific value.

  In the above engine structure, the combustion chamber forming member is at least one of a cylinder liner, a cylinder head, an intake valve, an exhaust valve, and a piston.

  According to the engine structure of the present invention as described above, heat transfer to a cooling fluid such as cooling water or oil can be favorably performed while increasing the thermal efficiency of the engine.

1 is a cross-sectional view (first embodiment) of a multi-cylinder engine to which an engine structure of the present invention is applied. It is principal part sectional drawing which shows the cylinder block of the said engine. It is explanatory drawing (the figure corresponding to FIG. 2) explaining the moving direction of heat. It is sectional drawing of the engine which shows the modification of the said engine structure. It is principal part sectional drawing (2nd Embodiment) of the engine to which this invention was applied. It is principal part sectional drawing (3rd Embodiment) of the engine to which this invention was applied. It is principal part sectional drawing (4th Embodiment) of the engine (piston) to which this invention was applied.

  Hereinafter, a first embodiment of the present invention will be described in detail with reference to the accompanying drawings.

(Overall engine structure)
FIG. 1 is a cross-sectional view of a multi-cylinder engine 1 (hereinafter abbreviated as engine 1) to which the present invention is applied. The engine 1 is an engine for a vehicle such as an automobile, and is an in-line 4-cylinder gasoline engine in which four cylinders are arranged in a direction perpendicular to the paper surface of FIG.

  The engine 1 includes an engine main body 2 and auxiliary machines such as an intake / exhaust manifold and various pumps (not shown) assembled thereto.

  The engine body 2 includes a cam cap 3, a cylinder head 4, a cylinder block 5, a crankcase (not shown), and an oil pan (not shown) that are connected vertically.

  Four cylinder bores 7 are formed in the cylinder block 5, and pistons 8 are slidably accommodated in the respective cylinder bores 7, and are combusted by these pistons 8, cylinder bores 7, cylinder heads 4, and intake / exhaust valves 14 and 15 described later. A chamber 10 is formed for each cylinder. Each piston 8 is connected via a connecting rod 9 to a crankshaft (not shown) that is rotatably supported by the crankcase.

  The cylinder head 4 is provided with the same number of recesses 4 a as the cylinder bore 7 for forming the combustion chamber 10. The cylinder head 4 is provided with an intake port 12 and an exhaust port 13 that open to the combustion chamber 10 at the position of each recess 4a for each cylinder, and an intake valve 14 and an exhaust valve that open and close the intake port 12 and the exhaust port 13, respectively. 15 is installed in each of the ports 12 and 13, respectively.

  The intake valve 14 and the exhaust valve 15 are urged in the direction of closing the ports 12 and 13 (upward in FIG. 1) by return springs 16 and 17, respectively, and are provided on the outer periphery of the camshafts 18 and 19. Each port 12 and 13 is configured to be opened by being pressed by the cam portions 18a and 19a. Specifically, as the cam shafts 18 and 19 rotate, the cam portions 18a and 19a push down the cam followers 20a and 21a provided at the center of the swing arms 20 and 21, so that the swing arms 20 and 21 are turned on. The top of the pivot mechanism of the hydraulic lash adjusters 24, 25 provided on one end side is swung around a fulcrum, and the other end of the swing arms 20, 21 is subjected to the biasing force of the return springs 16, 17 along with this swinging. The intake valve 14 and the exhaust valve 15 are pressed down against it. As a result, the ports 12 and 13 are opened.

  The cylinder head 4 and the cylinder block 5 are provided with a water jacket. Specifically, the cylinder block 5 is provided with a water jacket 26 so as to integrally surround the four cylinder bores 7. Further, the cylinder head 4 is provided with a water jacket 27 at a position on the intake side (right side in FIG. 1) of the combustion chamber 10 and below the intake port 12, and also on the exhaust side (in FIG. 1). A water jacket 28 is provided at a position below the exhaust port 13 on the left side), and a water jacket 29 is provided immediately above the combustion chamber 10 and between the ports 12 and 13. .

  Although not shown in detail, the water jacket 26 of the cylinder block 5 and the water jackets 27 and 28 of the cylinder head 4 are not shown in the drawing, and are connected to the gasket holes outside the drawing interposed between the cylinder head 4 and the cylinder block 5. Are communicated with each other.

  Each of the water jackets 26 to 29 is connected to a water pump (not shown). Thereby, the cooling water (cooling fluid) circulates between the engine main body 2 and the radiator (not shown), so that each water jacket 26 to 29 is provided. Are distributed in a predetermined order.

  Reference numerals 30 to 32 in FIG. 1 are oil gallery formed in the cylinder block 5 and the cylinder head 4. These oil galleries are connected to an oil pump (not shown), whereby hydraulic pressure for operation is supplied to hydraulic operating devices such as the hydraulic lash adjusters 24 and 25, and oil for cooling and cooling (cooling). Fluid) is supplied to each part of the engine body 2.

(Detailed structure of cylinder block 5)
As shown in FIGS. 1 and 2, the cylinder block 5 includes a block main body 50 that is a cast product of an aluminum alloy, and a cylindrical cylinder liner 51 that is cast or press-fitted into the block main body 50 (of the present invention). Corresponding to the combustion chamber forming member), and the cylinder bore 7 is formed by the cylinder liner 51. In this example, the inner peripheral surface of the cylinder liner 51 corresponds to the combustion chamber forming surface of the present invention.

  The block body 50 includes four cylinder portions 55, a skirt portion 56 that is connected to the lower side of the cylinder portion 55 to form a crank chamber, and a crankshaft bearing portion 57 that is formed inside the skirt portion 56. ing. The cylinder liner 51 is disposed in each cylinder portion 55.

  The cylinder liner 51 includes a first liner portion 52 (corresponding to a main body portion of the present invention) that forms a portion other than the upper end portion of the cylinder bore 7 and a second liner portion that forms the upper end portion of the cylinder bore 7. Liner portion 53 (corresponding to the heat induction portion of the present invention). In this example, the second liner portion 53 forms a certain region including the position of the piston ring of the piston 8 that has reached the top dead center in the cylinder bore 7.

  The first liner portion 52 is formed of a high thermal conductivity carbon fiber reinforced resin composite material (CFRP) and has thermal conductivity anisotropy. More specifically, the first liner portion 52 is made of, for example, a carbon fiber reinforced resin composite material obtained by impregnating and laminating pitch-based carbon fibers in an epoxy resin or the like, and the carbon fibers of the cylinder liner 51 (first liner portion 52). It is formed in a cylindrical shape so as to be parallel to the center line (axis). Accordingly, the first liner portion 52 has a thermal conductivity equal to or higher than that of the metal material, and the vertical direction (the direction parallel to the center line (the direction along the inner peripheral surface of the cylinder liner 51)) / first of the present invention. The thermal conductivity in the thickness direction (direction perpendicular to the center line / corresponding to the second direction of the present invention), that is, thermal conductivity anisotropy. It has a structure. In this example, for example, the thermal conductivity in the vertical direction is about 300 W / mK, whereas the thermal conductivity in the thickness direction is about 2.0 W / mK, and the first liner portion 52 has the heat conductivity in the vertical direction. The conductivity is 150 times the thermal conductivity in the thickness direction.

  On the other hand, the second liner portion 53 is in contact with the upper surface of the first liner portion 52 in a state where heat can be transferred. The second liner portion 53 is formed of a metal material. In this example, the second liner portion 53 is formed of cast iron, which is a general material of a cylinder liner. The thermal conductivity of cast iron is about 48 W / mK.

  The water jacket 26 is provided on the radially outer side (outer periphery) of the second liner portion 53. The water jacket 26 is formed by the outer peripheral surface of the second liner portion 53, the wall surface of the stepped portion 50a formed in the block main body 50, and the gasket. That is, the outer peripheral surface of the second liner portion 53 of the cylinder liner 51 is in direct contact with the cooling water.

(Effects of the above engine structure)
According to the engine structure described above, the first liner portion 52 of the cylinder liner 51 has the heat conduction anisotropy as described above, so that the heat received by the cylinder liner 51 is exclusively indicated by the arrows in FIG. As shown in FIG. 2, the heat moves toward the end portion on the water jacket 26 side where the temperature is low along the first liner portion 52, and heat radiation from the first liner portion 52 to the outside in the radial direction (thickness direction) is suppressed. Is done. That is, in the case of a cylinder block having a general cylinder liner having no thermal conductivity anisotropy, a lot of heat is radiated from the cylinder liner to the outside in the thickness direction, but according to the engine structure, Such wasteful heat dissipation is suppressed. In addition, since most of the heat moved along the cylinder liner 51 is transmitted to the cooling water via the second liner portion 53, the temperature rise of the cooling water in the water jacket 26 is thereby effectively promoted. Therefore, according to the engine structure described above, the combustion chamber 10 can be kept at a high temperature to increase the thermal efficiency of the engine, while the cooling water flowing in the water jacket 26 can also be raised in temperature satisfactorily. It is possible to avoid inconvenience that the heating function is hindered on the ground.

  Further, in this engine structure, a second liner portion 53 formed of cast iron is provided on the upper portion of the first liner portion 52, and the first liner portion 52 is provided in the water jacket 26 via the second liner portion 53. Since heat is transmitted to the cooling water, the cooling in the water jacket 26 located on the radially outer side of the cylinder liner 51 is provided while the first liner portion 52 having the heat conduction anisotropy as described above is provided in the cylinder liner 51. Heat can be transferred smoothly to water.

  Moreover, since the wall surface of the water jacket 26 is formed by the second liner portion 53, the cooling water directly contacts the second liner portion 53, so heat transfer from the second liner portion 53 to the cooling water is efficiently performed. Done. Therefore, according to the engine structure described above, the heat of combustion can be efficiently transmitted to the cooling water via the cylinder liner 51 (the first liner portion 52 and the second liner portion 53) to raise the temperature of the cooling water. There is also an advantage of being able to do it.

  In the engine structure shown in FIGS. 1 and 2, the first liner portion 52 has a single-layer structure formed from a carbon fiber reinforced resin composite material (CFRP). A two-layer structure as shown in FIG. The first liner portion 52 shown in FIG. 4 is provided integrally with an outer peripheral portion 52a (corresponding to a main portion of the present invention) formed of a high thermal conductivity carbon fiber reinforced resin composite material and an inner peripheral surface thereof. In addition, the cylinder bore 7 is formed by the inner peripheral portion 52b. The inner peripheral portion 52b includes an inner peripheral portion 52b (corresponding to the reinforcing portion of the present invention) made of a metal material such as cast iron. That is, the first liner portion 52 shown in FIG. 4 has a structure in which an outer peripheral portion 52a formed of a carbon fiber reinforced resin composite material is reinforced by an inner peripheral portion 52b made of a metal material. According to this engine structure, the rigidity and wear resistance of the first liner portion 52 are improved as compared with those shown in FIGS. 1 and 2. Therefore, there is an advantage that it is possible to improve the durability of the first liner portion 52 and, in turn, the durability of the engine 1 while enjoying the above-described effects.

(Second Embodiment)
FIG. 5 is a sectional view of the cylinder block 5 and corresponds to FIG. 2 of the first embodiment. As shown in the drawing, in the second embodiment, the cylinder liner 51 includes two inner and outer liner portions 62 and 63 (referred to as an inner liner portion 62 and an outer liner portion 63) formed in a cylindrical shape.

  Each liner part 62 and 63 is formed from the metal material from which heat conductivity differs mutually. Specifically, the inner liner portion 62 (corresponding to the inner member of the present invention) is formed of an aluminum alloy, and the outer liner portion 63 (corresponding to the outer member of the present invention) is more than the inner liner portion 62. Is formed of titanium or cast iron having a low thermal conductivity. The thermal conductivity of aluminum alloy is about 230 W / mK, and the thermal conductivity of titanium is about 17 W / mK. Note that the thermal conductivity of cast iron is about 48 W / mK as described above.

  A flange portion 62a protruding outward in the radial direction with a constant thickness is formed over the entire circumference at a position where the upper end portion of the inner liner portion 62, that is, the upper end portion of the cylinder bore 7 is formed. The outer liner portion 63 is fitted on the outer peripheral surface of the inner liner portion 62 with its upper end in contact with the lower surface of the flange portion 62a. As a result, the outer liner portion 63 is integrated with the inner liner portion 62.

  A water jacket 26 is provided on the radially outer side of the upper end portion of the inner liner portion 62. The water jacket 26 is formed by the outer peripheral surface of the flange portion 62a, the wall surface of the stepped portion 50a formed in the block body 50, and the gasket.

  According to the engine structure of the second embodiment as described above, the cylinder liner 51 is constituted by the inner liner portion 62 and the outer liner portion 63 having a lower thermal conductivity as described above. In a region other than the upper end portion of 51 (the portion corresponding to the flange portion 62a), the outer liner portion 63 suppresses heat radiation to the radially outer side, and the heat received by the cylinder liner 51 is exclusively along the inner liner portion 62. It moves toward the end on the water jacket 26 side where the temperature is low, and is transmitted from the flange 62a to the cooling water. That is, the cylinder liner 51 of the second embodiment also has a higher thermal conductivity in the vertical direction than the thermal conductivity in the thickness direction in the region other than the upper end portion, similarly to the first liner portion 52 of the first embodiment. The structure has thermal conductivity anisotropy.

  Therefore, the engine structure of the second embodiment can maintain the combustion chamber 10 at a high temperature and increase the thermal efficiency of the engine as in the first embodiment, while the cooling water flowing in the water jacket 26 is good. The temperature can be increased.

  In the engine structure of the second embodiment, in the region other than the upper end portion of the cylinder liner 51, as described above, the heat transfer to the block body 50 is suppressed by the outer liner portion 63. As a result, the cylinder liner 51 The heat transfer anisotropy is substantially larger in the vertical direction than in the thickness direction. That is, in the engine structure of the second embodiment, the region other than the upper end portion of the cylinder liner 51 corresponds to the main body portion of the present invention, and the upper end portion of the cylinder liner 51 (location corresponding to the flange portion 62a) is the main portion. It corresponds to the heat induction part of the invention.

(Third embodiment)
In the third embodiment, the present invention is applied to the intake valve 14.

  As shown in FIG. 6, the intake valve 14 includes a shaft portion 70 that is supported by the cylinder head 4 via a valve guide 73 so as to be able to advance and retreat, and an umbrella-shaped valve body 72 provided at the tip of the shaft portion 70. I have. The intake valve 14 has a closed position where the peripheral edge of the valve body 72 abuts on the opening peripheral edge of the intake port 12 by the elastic force of the return spring 16 and closes the intake port 12, and the peripheral edge of the valve main body 72 is inhaled. It moves away from the opening peripheral part of the port 12 to the open position where the intake port 12 is opened.

  The valve body 72 includes a valve surface (combustion chamber forming surface) that forms the combustion chamber 10 and a valve surface portion 72a (corresponding to the inner member of the present invention) that includes a portion that contacts the cylinder head 4 when the valve is closed. And a back surface portion 72b (corresponding to the outer member of the present invention).

  The valve surface portion 72a is formed of a metal material, and the back surface portion 72b and the shaft portion 70 are integrally formed of a metal material having a thermal conductivity different from that of the valve surface portion 72a. Specifically, the valve surface portion 72a is formed of an aluminum alloy (thermal conductivity: 230 W / mK), and the back surface portion 72b and the shaft portion 70 are made of titanium (thermal conductivity) having a lower thermal conductivity than the valve surface portion 72a. : 17 W / mK) or cast iron (thermal conductivity: 48 W / mK).

  According to the engine structure of the third embodiment, the thermal conductivity of the back surface portion 72b of the valve main body 72 is lower than the thermal conductivity of the valve surface portion 72a. Heat transfer is suppressed, and most of the heat received by the valve surface of the valve body 72 moves around the valve surface and is transmitted to the cylinder head 4 as shown by arrows in FIG. This is transmitted to the cooling water in the water jackets 27 and 29 provided in the vicinity of the port 12. That is, the valve body 72 has a thickness direction (corresponding to the second direction of the present invention) in which the thermal conductivity in the direction along the valve surface portion 72a (corresponding to the first direction of the present invention) is orthogonal to the valve surface. The structure has a thermal conductivity anisotropy larger than the thermal conductivity. Therefore, heat dissipation from the shaft portion 70 and the valve guide 73 to the cylinder head 4 and heat dissipation from the shaft portion 70 to the intake air in the intake port 12 are suppressed, while heat transport to the cooling water is promoted. Become.

  Therefore, also in the third embodiment, as in the first and second embodiments, the combustion chamber 10 can be maintained at a high temperature to increase the thermal efficiency of the engine, while the cooling water flowing in the water jackets 27 and 29 is increased. It is possible to raise the temperature satisfactorily.

  As a modification of the third embodiment, for example, the shaft portion 70 has a double structure having an inner shaft portion and an outer shaft portion, and the valve surface portion 72a of the valve main body 72 and the inner shaft portion of the shaft portion 70 are made of an aluminum alloy. However, it is also possible to adopt a structure in which the back surface portion 72b of the valve main body 72 and the outer portion of the shaft portion 70 are integrally formed of titanium or cast iron. According to this structure, part of the heat received by the valve surface portion 72a is guided to the end thereof through the inside (inner shaft portion) of the shaft portion 70, the oil supplied to the camshaft 18 and the swing arm 20, and the cylinder head 4 It becomes possible to give to the cooling water in the water jacket outside a figure formed in this. Therefore, it is advantageous in promoting the temperature rise of oil and cooling water.

  In the third embodiment, the example in which the present invention is applied to the intake valve 14 has been described. However, the present invention can also be applied to the exhaust valve 15 in the same manner.

(Fourth embodiment)
In the fourth embodiment, the present invention is applied to the piston 8.

  As shown in FIG. 7, the piston 8 includes a piston body 81 having first to third three piston rings 84 to 86 on the outer periphery, a pair of pin boss portions 83 having piston pin holes 83a, and a skirt portion 82. And integrated.

  The piston main body 81 has an upper upper body 81a including the top surface (piston top / combustion chamber forming surface) of the piston 8 with the position between the first ring 84 and the second ring 85 as a boundary line (in the present invention). And a lower main body 81b (corresponding to the outer member of the present invention) on the lower side. The upper main body 81a and the lower main body 81b are formed of metal materials having different thermal conductivities. Specifically, the upper body 81a is made of an aluminum alloy (thermal conductivity: 230 W / mK), and the lower body 81b is titanium (thermal conductivity: 17 W / mK) having a lower thermal conductivity than the upper body 81a. Or cast iron (thermal conductivity: 48 W / mK).

  The piston rings 84 to 86 are made of cast iron or steel (stainless steel, silicon chrome steel, carbon steel).

  According to the engine structure of the fourth embodiment, the top surface of the piston 8 is received because the thermal conductivity of the lower body 81b of the piston body 81 is lower than that of the upper body 81a. As shown by arrows in FIG. 7, most of the heat moves to the periphery of the upper body 81a and is transmitted to the cylinder block 5 (cylinder liner 51) via the first ring 84. 5 is transmitted to the cooling water in the water jacket 26 formed in the water jacket 26. That is, the heat conductivity of the piston 8 in the direction along the top surface (corresponding to the first direction of the present invention) is in the vertical direction (direction perpendicular to the top surface / corresponding to the second direction of the invention). The structure has a thermal conductivity anisotropy larger than the conductivity. Therefore, heat is radiated to the crankshaft via the pin boss portion 83 and the connecting rod 9 and heat radiation from the skirt portion 82 is suppressed, while heat transport to the cooling water is promoted.

  Therefore, also in the fourth embodiment, as in the first to third embodiments, the combustion chamber 10 can be maintained at a high temperature to increase the thermal efficiency of the engine, while the cooling water flowing in the water jackets 27 and 29 is increased. It is possible to raise the temperature satisfactorily.

  The first to fourth embodiments of the present invention described above are examples of preferred embodiments of the engine structure according to the present invention, and the specific configuration thereof does not depart from the gist of the present invention. It can be changed as appropriate.

  For example, the first liner portion 52 of the cylinder liner 51 shown in the first embodiment (FIG. 2) is formed of a high thermal conductivity carbon fiber reinforced resin composite material (CFRP) in the above example. , Composite materials of graphite and metal (aluminum, etc.), that is, composite materials in which graphite is oriented in the metal so that there is a difference in the heat transfer coefficient in the orthogonal direction, and thermal conductivity anisotropy using multi-walled carbon nanotubes You may be comprised with the material which has. In short, if the first liner portion 52 can be provided with a material having a heat transfer characteristic (heat conduction anisotropy) having a large heat transfer coefficient in the vertical direction as compared with the heat transfer coefficient in the thickness direction, various materials can be used. Applicable.

  In the second embodiment, the inner liner portion 62 is formed of an aluminum alloy, while the outer liner portion 63 is formed of titanium or cast iron having a lower thermal conductivity than the aluminum alloy, so that the cylinder liner 51 (upper end) is formed. (A region other than the portion) has a structure having thermal conductivity anisotropy, but the material forming each of the liner portions 62 and 63 is not limited to these, and a desired thermal conductivity anisotropy is obtained. It may be selected appropriately so that it can be. This also applies to the engine structures (intake valve 14 and piston 8) of the third and fourth embodiments.

  In the third embodiment, the valve surface 72a is formed of an aluminum alloy, while the back surface 72b is formed of titanium or cast iron having a thermal conductivity lower than that of the aluminum alloy. The valve body 72 is anisotropic in heat conduction by forming the valve face portion 72a from a highly heat conductive carbon fiber reinforced resin composite material (CFRP) having a thermal conductivity anisotropy. It is good also as a structure which has property. This also applies to the engine structure (piston 8) of the fourth embodiment.

  In the first embodiment, the water jacket 26 of the cylinder block 5 is provided at a position mainly corresponding to the upper end portion of the cylinder bore 7, but covers a wide range from the upper end portion of the cylinder bore 7 to the intermediate portion. It may be provided. Further, it may be provided at a position corresponding to the lower end portion of the cylinder bore 7.

  In the first to fourth embodiments, examples in which the present invention is applied to the cylinder liner 51, the intake valve 14 (exhaust valve), and the piston 8 have been described. However, the present invention can also be applied to the cylinder head 4 in addition to this. is there.

DESCRIPTION OF SYMBOLS 1 Multi-cylinder engine 2 Engine main body 3 Cam cap 4 Cylinder head 5 Cylinder block 10 Combustion chamber 26-29 Water jacket 50 Block main body 51 Cylinder liner (combustion chamber formation member)
52 1st liner part (main part)
53 2nd liner part (heat induction part)

Claims (8)

An engine structure including a combustion chamber forming member having a combustion chamber forming surface that forms a combustion chamber, and a fluid passage through which a cooling fluid flows,
The combustion chamber forming member has a thermal conductivity anisotropy in which the thermal conductivity in the first direction along the combustion chamber forming surface is larger than the thermal conductivity in the second direction orthogonal to the combustion chamber forming surface,
The engine structure according to claim 1, wherein the fluid passage is provided so that a cooling fluid flows at least in a position near an end of the combustion chamber forming member in the first direction. The engine structure according to claim 1,
The engine structure is characterized in that the combustion chamber forming member is formed of a single kind of material having the heat conduction anisotropy. The engine structure according to claim 2,
The combustion chamber forming member has a main portion formed of the carbon fiber reinforced resin composite material having thermal conductivity anisotropy and a reinforcing portion formed of a metal material to form the combustion chamber forming surface. An engine structure characterized by The engine structure according to claim 1,
The combustion chamber forming member includes an inner member having the combustion chamber forming surface, and an outer member that is located outside the inner member in the second direction and has a lower thermal conductivity than the inner member. , Engine structure characterized by that. The engine structure according to any one of claims 1 to 4,
The combustion chamber forming member is connected to the main body portion having the heat conduction anisotropy so that heat can be transferred to the main body portion at a specific position in the first direction, and heat induction is performed to transfer heat from the main body portion to the cooling fluid. And an engine structure including a part. The engine structure according to claim 5, wherein
The engine structure according to claim 1, wherein the heat induction part forms a wall surface of the fluid passage. The engine structure according to any one of claims 1 to 6,
The engine structure according to claim 1, wherein the fluid passage is provided only at a position near one end of the combustion chamber forming member in the first direction. The engine structure according to any one of claims 1 to 7,
The engine structure is characterized in that the combustion chamber forming member is at least one of a cylinder liner, a cylinder head, an intake valve, an exhaust valve, and a piston.

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